ABCelectronique : portail d'information dans le domaine de l'électronique
Pages: 0123456789


Publications dans les journaux scientifiques dans le domaine de l'ingénierie : 05-2017 trié par par titre, page: 8
» Riemannian Geometry Applied to Detection of Respiratory States From EEG Signals: The Basis for a Brain–Ventilator Interface
Résumé:
Goal: During mechanical ventilation, patient-ventilator disharmony is frequently observed and may result in increased breathing effort, compromising the patient's comfort and recovery. This circumstance requires clinical intervention and becomes challenging when verbal communication is difficult. In this study, we propose a brain–computer interface (BCI) to automatically and noninvasively detect patient-ventilator disharmony from electroencephalographic (EEG) signals: a brain–ventilator interface (BVI). Methods: Our framework exploits the cortical activation provoked by the inspiratory compensation when the subject and the ventilator are desynchronized. Use of a one-class approach and Riemannian geometry of EEG covariance matrices allows effective classification of respiratory states. The BVI is validated on nine healthy subjects that performed different respiratory tasks that mimic a patient-ventilator disharmony. Results: Classification performances, in terms of areas under receiver operating characteristic curves, are significantly improved using EEG signals compared to detection based on air flow. Reduction in the number of electrodes that can achieve discrimination can be often desirable (e.g., for portable BCI systems). By using an iterative channel selection technique, the common highest order ranking, we find that a reduced set of electrodes ($n=6$ ) can slightly improve for an intrasubject configuration, and it still provides fairly good performances for a general intersubject setting. Conclusion: Results support the discriminant capacity of our approach to identify anomalous respiratory states, by learning from a training set containing only normal respiratory epochs. Significance: The proposed framework opens the door to BVIs for monitoring pati- nt's breathing comfort and adapting ventilator parameters to patient respiratory needs.
Auteurs: X. Navarro-Sune;A. L. Hudson;F. De Vico Fallani;J. Martinerie;A. Witon;P. Pouget;M. Raux;T. Similowski;M. Chavez;
Apparue dans: IEEE Transactions on Biomedical Engineering
Date publication: 05.-2017, volume: 64, issue:5, pages: 1138 - 1148
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Right Ventricular Strain, Torsion, and Dyssynchrony in Healthy Subjects Using 3D Spiral Cine DENSE Magnetic Resonance Imaging
Résumé:
Mechanics of the left ventricle (LV) are important indicators of cardiac function. The role of right ventricular (RV) mechanics is largely unknown due to the technical limitations of imaging its thin wall and complex geometry and motion. By combining 3D Displacement Encoding with Stimulated Echoes (DENSE) with a post-processing pipeline that includes a local coordinate system, it is possible to quantify RV strain, torsion, and synchrony. In this study, we sought to characterize RV mechanics in 50 healthy individuals and compare these values to their LV counterparts. For each cardiac frame, 3D displacements were fit to continuous and differentiable radial basis functions, allowing for the computation of the 3D Cartesian Lagrangian strain tensor at any myocardial point. The geometry of the RV was extracted via a surface fit to manually delineated endocardial contours. Throughout the RV, a local coordinate system was used to transform from a Cartesian strain tensor to a polar strain tensor. It was then possible to compute peak RV torsion as well as peak longitudinal and circumferential strain. A comparable analysis was performed for the LV. Dyssynchrony was computed from the standard deviation of regional activation times. Global circumferential strain was comparable between the RV and LV (−18.0% for both) while longitudinal strain was greater in the RV (−18.1% vs. −15.7%). RV torsion was comparable to LV torsion (6.2 vs. 7.1 degrees, respectively). Regional activation times indicated that the RV contracted later but more synchronously than the LV. 3D spiral cine DENSE combined with a post–processing pipeline that includes a local coordinate system can resolve both the complex geometry and 3D motion of the RV.
Auteurs: Jonathan D. Suever;Gregory J. Wehner;Linyuan Jing;David K. Powell;Sean M. Hamlet;Jonathan D. Grabau;Dimitri Mojsejenko;Kristin N. Andres;Christopher M. Haggerty;Brandon K. Fornwalt;
Apparue dans: IEEE Transactions on Medical Imaging
Date publication: 05.-2017, volume: 36, issue:5, pages: 1076 - 1085
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Road Structure Refined CNN for Road Extraction in Aerial Image
Résumé:
In this letter, we propose a road structure refined convolutional neural network (RSRCNN) approach for road extraction in aerial images. In order to obtain structured output of road extraction, both deconvolutional and fusion layers are designed in the architecture of RSRCNN. For training RSRCNN, a new loss function is proposed to incorporate the geometric information of road structure in cross-entropy loss, thus called road-structure-based loss function. Experimental results demonstrate that the trained RSRCNN model is able to advance the state-of-the-art road extraction for aerial images, in terms of precision, recall, F-score, and accuracy.
Auteurs: Yanan Wei;Zulin Wang;Mai Xu;
Apparue dans: IEEE Geoscience and Remote Sensing Letters
Date publication: 05.-2017, volume: 14, issue:5, pages: 709 - 713
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Robust Channel Phase Error Calibration Algorithm for Multichannel High-Resolution and Wide-Swath SAR Imaging
Résumé:
High-resolution and wide-swath synthetic aperture radar (SAR) imaging can be achieved by the azimuth multichannel system. The minimum variance distortionless response (MVDR) beamformer can be utilized to suppress azimuth ambiguities. However, the presence of channel phase errors significantly deteriorates the performance of the azimuth multichannel SAR system. Instead of employing subspace techniques, this letter proposes a robust channel phase error calibration algorithm via maximizing the MVDR beamformer output power. Compared with the conventional subspace-based calibration methods, there is no redundancy of channels required to estimate the subspaces in the proposed algorithm. Also, the proposed algorithm is relatively robust, because it avoids the subspace swap phenomenon, which probably takes place at low signal-to-noise ratios for the subspace techniques. Moreover, the proposed method has the advantage of estimating the channel phase errors without covariance matrix decomposition, which reduces the computation load. The simulation experiments and the real data processing validate the effectiveness of the proposed calibration method.
Auteurs: Linjian Zhang;Yesheng Gao;Xingzhao Liu;
Apparue dans: IEEE Geoscience and Remote Sensing Letters
Date publication: 05.-2017, volume: 14, issue:5, pages: 649 - 653
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Robust Collaborative Spectrum Sensing Using PHY-Layer Fingerprints in Mobile Cognitive Radio Networks
Résumé:
Collaborative spectrum sensing has been proposed to significantly improve the performance of spectrum sensing in cognitive radio networks (CRNs). However, a serious attack, called a primary user emulation attack (PUEA), could decrease the performance of collaborative spectrum sensing. In this letter, according to mobile CRNs, we propose a novel robust collaborative spectrum sensing method using physical-layer fingerprints power in a multipath Rayleigh fading channel. Moreover, a fingerprints-power-belief-based noncentral detection algorithm is designed to defend against PUEAs. Simulation results show that our proposed method can rapidly detect the presence of a primary user under PUEAs with good performance.
Auteurs: Ning Gao;Xiaojun Jing;Hai Huang;Junsheng Mu;
Apparue dans: IEEE Communications Letters
Date publication: 05.-2017, volume: 21, issue:5, pages: 1063 - 1066
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Robust Detection of Cyber Attacks on State Estimators Using Phasor Measurements
Résumé:
This letter proposes a statistical consistency check-based imperfect false data injection attacks detector that is more effective than the conventional residual-based methods. It is shown that the proposed detector could detect attacks with high probability by using a limited number of secure PMU measurements even if the probability of the false alarm is low. Numerical results validate its effectiveness and practicability.
Auteurs: Junbo Zhao;Gexiang Zhang;Rabih A. Jabr;
Apparue dans: IEEE Transactions on Power Systems
Date publication: 05.-2017, volume: 32, issue:3, pages: 2468 - 2470
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Robust Finite-Time Tracking of Stewart Platform: A Super-Twisting Like Observer-Based Forward Kinematics Solution
Résumé:
The paper presents the robust finite-time tracking of Stewart platform using super-twisting sliding mode observer based forward kinematics solution. The forward kinematics problem—finding the states from the leg length measurements—in Stewart platform gives nonunique solution for any given leg lengths, and due to this it poses difficulties in the control design. The super-twisting observer is designed from the available leg length measurements which is the output of the system to obtain the position and orientation of movable platform and their respective derivatives. The finite-time convergence of this observer and the stability of the closed loop system are presented in detail. It is shown that using this leg length measurements, the states of the observer converge to actual state in finite-time and hence, it provides a solution to the forward kinematics problem. Using these estimated states, a robust finite-time tracking control is designed for the Stewart platform by considering all the uncertainties and parameter variations. However, the proposed method for forward kinematics solution can also be incorporated with any other control strategies. Simulation results are given to demonstrate the performance of the proposed observer for the Stewart platform.
Auteurs: P. R. Kumar;Abhisek K. Behera;Bijnan Bandyopadhyay;
Apparue dans: IEEE Transactions on Industrial Electronics
Date publication: 05.-2017, volume: 64, issue:5, pages: 3776 - 3785
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Robust Generalized Low-Rank Decomposition of Multimatrices for Image Recovery
Résumé:
Low-rank approximation has been successfully used for dimensionality reduction, image noise removal, and image restoration. In existing work, input images are often reshaped to a matrix of vectors before low-rank decomposition. It has been observed that this procedure will destroy the inherent two-dimensional correlation within images. To address this issue, the generalized low-rank approximation of matrices (GLRAM) method has been recently developed, which is able to perform low-rank decomposition of multiple matrices directly without the need for vector reshaping. In this paper, we propose a new robust generalized low-rank matrices decomposition method, which further extends the existing GLRAM method by incorporating rank minimization into the decomposition process. Specifically, our method aims to minimize the sum of nuclear norms and $l_{1}$ -norms. We develop a new optimization method, called alternating direction matrices tri-factorization method , to solve the minimization problem. We mathematically prove the convergence of the proposed algorithm. Our extensive experimental results demonstrate that our method significantly outperforms existing GLRAM methods.
Auteurs: Hengyou Wang;Yigang Cen;Zhihai He;Ruizhen Zhao;Yi Cen;Fengzhen Zhang;
Apparue dans: IEEE Transactions on Multimedia
Date publication: 05.-2017, volume: 19, issue:5, pages: 969 - 983
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Robust Infrared Maritime Target Detection Based on Visual Attention and Spatiotemporal Filtering
Résumé:
It has always been a great challenge to efficiently detect small infrared targets from complex image backgrounds without any prior knowledge. This is especially true when both strong and weak targets appear in the same image or when the weak targets come up on image borders. The main contribution of this paper is to design a robust infrared maritime target detection method, in which a visual attention and pipeline-filtering model is proposed by integrating a revised visual attention model (VAM) and the antivibration pipeline-filtering algorithm. The revised VAM, a single-frame target detection strategy, will first compute a saliency map (SM) from a specific modality, which is automatically selected according to image background smoothness. Then, an automatic strategy for extracting suspected targets from an SM is also proposed here, which highlights targets and suppresses background clutters in SMs through local saliency singularity evaluation. Moreover, contrary to the original VAM, we adopt border saliency preservation in center-surround difference so that robust detection can be guaranteed for targets on image borders. Finally, to eliminate the interference of sea glints and confirm real targets, we adopt the antivibration pipeline-filtering algorithm, a multiframe-based clutter removal method. Compared with the original VAM and two other existing target detection algorithms, experimental results have proven that our strategy can detect infrared maritime targets much better under different environmental conditions. This research can significantly improve the success rate and efficiency of searching maritime targets in different weathers using infrared imager, especially in heavy sea fog and strong ocean waves.
Auteurs: Lili Dong;Bin Wang;Ming Zhao;Wenhai Xu;
Apparue dans: IEEE Transactions on Geoscience and Remote Sensing
Date publication: 05.-2017, volume: 55, issue:5, pages: 3037 - 3050
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Robust Matrix Discriminative Analysis for Feature Extraction From Hyperspectral Images
Résumé:
Linear discriminative analysis (LDA) is an effective feature extraction method for hyperspectral image (HSI) classification. Most of the existing LDA-related methods are based on spectral features, ignoring spatial information. Recently, a matrix discriminative analysis (MDA) model has been proposed to incorporate the spatial information into the LDA. However, due to sensor interferers, calibration errors, and other issues, HSIs can be noisy. These corrupted data easily degrade the performance of the MDA. In this paper, a robust MDA (RMDA) model is proposed to address this important issue. Specifically, based on the prior knowledge that the pixels in a small spatial neighborhood of the HSI lie in a low-rank subspace, a denoising model is first employed to recover the intrinsic components from the noisy HSI. Then, the MDA model is used to extract discriminative spatial–spectral features from the recovered components. Besides, different HSIs exhibit different spatial contextual structures, and even a single HSI may contain both large and small homogeneous regions simultaneously. To sufficiently describe these multiscale spatial structures, a multiscale RMDA model is further proposed. Experiments have been conducted using three widely used HSIs, and the obtained results show that the proposed method allows for a significant improvement in the classification performance when compared to other LDA-based methods.
Auteurs: Renlong Hang;Qingshan Liu;Yubao Sun;Xiaotong Yuan;Hucheng Pei;Javier Plaza;Antonio Plaza;
Apparue dans: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Date publication: 05.-2017, volume: 10, issue:5, pages: 2002 - 2011
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Robust Object Tracking via Locality Sensitive Histograms
Résumé:
This paper presents a novel locality sensitive histogram (LSH) algorithm for visual tracking. Unlike the conventional image histogram that counts the frequency of occurrence of each intensity value by adding ones to the corresponding bin, an LSH is computed at each pixel location, and a floating-point value is added to the corresponding bin for each occurrence of an intensity value. The floating-point value exponentially reduces with respect to the distance to the pixel location where the histogram is computed. An efficient algorithm is proposed that enables the LSHs to be computed in time linear in the image size and the number of bins. In addition, this efficient algorithm can be extended to exploit color images. A robust tracking framework based on the LSHs is proposed, which consists of two main components: a new feature for tracking that is robust to illumination change and a novel multiregion tracking algorithm that runs in real time even with hundreds of regions. Extensive experiments demonstrate that the proposed tracking framework outperforms the state-of-the-art methods in challenging scenarios, especially when the illumination changes dramatically. Evaluation using the latest benchmark shows that our algorithm is the top performer.
Auteurs: Shengfeng He;Rynson W. H. Lau;Qingxiong Yang;Jiang Wang;Ming-Hsuan Yang;
Apparue dans: IEEE Transactions on Circuits and Systems for Video Technology
Date publication: 05.-2017, volume: 27, issue:5, pages: 1006 - 1017
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Robust Operation of Distribution Networks Coupled With Urban Transportation Infrastructures
Résumé:
We study the energy dispatch of power distribution networks (PDNs) coupled with urban transportation networks. The electricity demand at each charging/swapping facility is influenced by the arrival rates and charging requests of electric vehicles, which further depends on the spatial distribution of traffic flows over the entire transportation system. We consider the impact of the road congestion on route choices of vehicles from a system-level perspective. The traffic flow pattern in steady state is characterized by the Wardrop user equilibrium. We consider the PDN load perturbation caused by the traffic demand uncertainty, and propose a robust dispatch method that maintains the feasibility of an alternating current power flow constraints. By applying the convex relaxation to nonlinear branch power flow equations, the proposed model yields a two-stage robust convex optimization problem with an implicit uncertainty set. Moreover, a decomposition framework is proposed, in which the first phase determines the uncertainty set of electricity demand by solving two traffic assignment problems associated with the extreme scenarios, and the second phase solves a two-stage robust second-order cone program following a delayed constraint generation framework. Several issues regarding the scalability and conservatism are elaborated. Case studies corroborate the applicability and efficiency of the proposed method.
Auteurs: Wei Wei;Shengwei Mei;Lei Wu;Jianhui Wang;Yujuan Fang;
Apparue dans: IEEE Transactions on Power Systems
Date publication: 05.-2017, volume: 32, issue:3, pages: 2118 - 2130
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Robust Registration of Multimodal Remote Sensing Images Based on Structural Similarity
Résumé:
Automatic registration of multimodal remote sensing data [e.g., optical, light detection and ranging (LiDAR), and synthetic aperture radar (SAR)] is a challenging task due to the significant nonlinear radiometric differences between these data. To address this problem, this paper proposes a novel feature descriptor named the histogram of orientated phase congruency (HOPC), which is based on the structural properties of images. Furthermore, a similarity metric named HOPCncc is defined, which uses the normalized correlation coefficient (NCC) of the HOPC descriptors for multimodal registration. In the definition of the proposed similarity metric, we first extend the phase congruency model to generate its orientation representation and use the extended model to build HOPCncc. Then, a fast template matching scheme for this metric is designed to detect the control points between images. The proposed HOPCncc aims to capture the structural similarity between images and has been tested with a variety of optical, LiDAR, SAR, and map data. The results show that HOPCncc is robust against complex nonlinear radiometric differences and outperforms the state-of-the-art similarities metrics (i.e., NCC and mutual information) in matching performance. Moreover, a robust registration method is also proposed in this paper based on HOPCncc, which is evaluated using six pairs of multimodal remote sensing images. The experimental results demonstrate the effectiveness of the proposed method for multimodal image registration.
Auteurs: Yuanxin Ye;Jie Shan;Lorenzo Bruzzone;Li Shen;
Apparue dans: IEEE Transactions on Geoscience and Remote Sensing
Date publication: 05.-2017, volume: 55, issue:5, pages: 2941 - 2958
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Robust Tracking Control of Networked Control Systems With Communication Constraints and External Disturbance
Résumé:
This paper addresses the problem of robust tracking control of networked control systems with communication constraints (network-induced delay, packet dropouts, and packet disorder) and external disturbance. A novel networked predictive control algorithm based on k-order adaptive discrete-time sliding-mode control (k -ADSMC) is proposed. The ADSMC, which can self-adapting adjust sliding-mode parameters and ensure faster convergence, is designed based on the error and error difference of tracking output. Furthermore, k -ADSMC is designed, which uses the estimated disturbance as weight factors and synthesizes the sliding- mode values of all k times, in order to improve the robust of tracking control. Finally, the stability of the system is proved, and a dc motor servo system is utilized to verify the effectiveness of the proposed method.
Auteurs: Meng Li;Yong Chen;
Apparue dans: IEEE Transactions on Industrial Electronics
Date publication: 05.-2017, volume: 64, issue:5, pages: 4037 - 4047
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Robust Visual Tracking With Multitask Joint Dictionary Learning
Résumé:
Dictionary learning for sparse representation has been increasingly applied to object tracking, however, the existing methods only utilize one modality of the object to learn a single dictionary. In this paper, we propose a robust tracking method based on multitask joint dictionary learning. Through extracting different features of the target, multiple linear sparse representations are obtained. Each sparse representation can be learned by a corresponding dictionary. Instead of separately learning the multiple dictionaries, we adopt a multitask learning approach to learn the multiple linear sparse representations, which provide additional useful information to the classification problem. Because different tasks may favor different sparse representation coefficients, yet the joint sparsity may enforce the robustness in coefficient estimation. During tracking, a classifier is constructed based on a joint linear representation, and the candidate with the smallest joint decision error is selected to be the tracked object. In addition, reliable tracking results and augmented training samples are accumulated into two sets to update the dictionaries for classification, which helps our tracker adapt to the fast time-varying object appearance. Both qualitative and quantitative evaluations on CVPR2013 visual tracking benchmark demonstrate that our method performs favorably against state-of-the-art trackers.
Auteurs: Heng Fan;Jinhai Xiang;
Apparue dans: IEEE Transactions on Circuits and Systems for Video Technology
Date publication: 05.-2017, volume: 27, issue:5, pages: 1018 - 1030
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Robustness of Electricity and Chilled Water Supply Systems Subject to Change Technical and Economic
Résumé:
This paper presents a methodology to evaluate the economic robustness of thermal systems designed to supply air conditioning and electricity for shopping malls in an Brazilian northeastern state. The procedure uses a hybrid method to minimize the Net Present Value (NPV) of the life costs. The optimization considers technical and economic aspects such as curves of demand, tariff variation along the day, equipment efficiencies and costs. It was studied the robustness of the systems in relation to variations of fuel tariff, electricity tariff, engine price, dollar fluctuation and demand profile.
Auteurs: Lucas Ademar Freitas;Fabio Santana Magnani;Eric Monroe Hornsby;
Apparue dans: IEEE Latin America Transactions
Date publication: 05.-2017, volume: 15, issue:5, pages: 908 - 915
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Rotated Nonuniform Subgrids in the FDTD Method With Application to a Hemispherical Antenna Array
Résumé:
The use of subgrids in the finite-difference time-domain method to facilitate the analysis of multiscale problems is now well established. However, many of the proposed algorithms are restricted to cases where the subgrid and the main grid share the same Cartesian coordinate system and where the ratio of the cell sizes in the two grids has a constant integer ratio. More recently, it has been shown that subgrids, based on Cartesian grids which are rotated with respect to the main grid, can be effectively used, but the cell size ratio was still kept constant. In this contribution, the method is further generalized in order to allow nonuniform subgrids to be used. This greatly increases the range of structures which can be efficiently analyzed. The effectiveness of the method is demonstrated by application to a 31-element hemispherical array of broadband cavity backed slot antenna elements.
Auteurs: Chris J. Railton;
Apparue dans: IEEE Transactions on Antennas and Propagation
Date publication: 05.-2017, volume: 65, issue:5, pages: 2460 - 2466
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Safety and Standards ? Closely Interlinked [Standards News]
Résumé:
Examines the relationship between safety and standards development. Standards may be divided into two distinct categories, safety and performance. In the first instance, safety standards provide rules, recommendations, and mitigation techniques to eliminate or minimize risks associated with the identified hazards. Legal requirements are normally issued in the form of standards. In the second circumstance, performance standards define the performance of a product or the practices under a certain set of conditions for evaluation and application between products of various suppliers.
Auteurs: Daleep Mohla;
Apparue dans: IEEE Industry Applications Magazine
Date publication: 05.-2017, volume: 23, issue:3, pages: 71 - 72
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Safety in Vehicle Platooning: A Systematic Literature Review
Résumé:
Vehicle platooning has been studied for several decades, with objectives such as improved traffic throughput on existing infrastructure or reduced energy consumption. All the time, it has been apparent that safety is an important issue. However, there are no comprehensive analyses of what is needed to achieve safety in platooning, but only scattered pieces of information. This paper investigates, through a systematic literature review, what is known about safety for platooning, including what analysis methods have been used, what hazards and failures have been identified, and solution elements that have been proposed to improve safety. Based on this, a gap analysis is performed to identify outstanding questions that need to be addressed in future research. These include dealing with a business ecosystem of actors that cooperate and compete around platooning, refining safety analysis methods to make them suitable for systems-of-systems, dealing with variability in vehicles, and finding solutions to various human factors issues.
Auteurs: Jakob Axelsson;
Apparue dans: IEEE Transactions on Intelligent Transportation Systems
Date publication: 05.-2017, volume: 18, issue:5, pages: 1033 - 1045
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Sampled Observability and State Estimation of Linear Discrete Ensembles
Résumé:
We consider the problem of reconstructing the initial states of a finite group of structurally identical linear systems in the situation that output measurements of the individual systems are received at discrete time steps and in an anonymized manner: While we do know all output measurements of the individual systems in the group, we do not know which output measurement corresponds to which system. This state estimation problem addresses the essence of state estimation problems for populations, in which the output measurements of the individual systems are given only as statistics. We adopt a measure theoretical approach in which the group is modelled by an LTI system describing the structure of the individual systems and an initial state which is expressed by a discrete measure. In this framework we derive a geometric characterization for the state estimation to admit a unique solution, which combined with a result on the observability of linear systems under irregular sampling, yields a sufficient condition for the sampled observability of discrete ensembles. As a supplement to our theoretical findings, we provide illustrations by means of simulation examples. Furthermore we consider the practical state estimation problem under noisy output measurements.
Auteurs: Shen Zeng;Hideaki Ishii;Frank Allgöwer;
Apparue dans: IEEE Transactions on Automatic Control
Date publication: 05.-2017, volume: 62, issue:5, pages: 2406 - 2418
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Sampled-Data Stabilization of Nonlinear Dynamics With Input Delays Through Immersion and Invariance
Résumé:
In this technical note, we show that Immersion and Invariance is a natural framework for the design of sampled-data stabilizing controllers for input-delayed systems. Assuming the existence of a continuous-time feedback in the delay free case, Immersion and Invariance stabilizability of the equivalent sampled-data dynamics is proven. The proof is constructive for the stabilizing controller. Two simulated examples illustrate the performances.
Auteurs: Salvatore Monaco;Dorothée Normand-Cyrot;Mattia Mattioni;
Apparue dans: IEEE Transactions on Automatic Control
Date publication: 05.-2017, volume: 62, issue:5, pages: 2561 - 2567
Editeur: IEEE
Document complet vers site de l'éditeur
 
» SAR Image Content Retrieval Based on Fuzzy Similarity and Relevance Feedback
Résumé:
This paper presents a new content-based synthetic aperture radar (SAR) image retrieval method to search out SAR image patches, which consists of two essential parts: an initial retrieval and later refined results. To obtain the proper initial retrievals, we develop a similarity measure named region-based fuzzy matching (RFM) to evaluate the similarities between SAR image patches. First, to reduce the negative influence of speckle noise, we segment the SAR image patches into brightness-texture regions at the superpixel level rather than the pixel level. Second, a multiscale edge detector is utilized to resolve the multiscale property of the SAR image patches, and then the edge regions of the SAR image patches are defined by those edge features. Third, to overcome the segmented uncertainty and the blurry boundaries, the obtained regions are described by fuzzy features. Finally, the RFM similarity between two SAR image patches is converted into the linear summation of the resemblance between different fuzzy feature sets. After we obtain the initial retrieval results, the multiple relevance feedback (MRF) scheme is proposed to refine the original ranked list. In this scheme, different relevance feedback approaches are carried out respectively, and then their results are fused to improve the initial retrieval. In addition, a new kernel function based on the RFM measure is developed for MRF. The encouraging experimental results counted on a manually constructed ground truth SAR image patch dataset demonstrate that our retrieval method is effective for SAR images compared with some existing approaches proposed in the remote sensing community
Auteurs: Xu Tang;Licheng Jiao;William J. Emery;
Apparue dans: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Date publication: 05.-2017, volume: 10, issue:5, pages: 1824 - 1842
Editeur: IEEE
Document complet vers site de l'éditeur
 
» SAR Image Denoising via Sparse Representation in Shearlet Domain Based on Continuous Cycle Spinning
Résumé:
How to suppress speckle noise effectively has become one of the key problems in remote sensing image processing. This problem also restricts the development of key technology severely, especially in military applications and so on. To overcome the shortcoming that the optimal solution of image denoising based on sparse representation does not have one-to-one mapping of the original signal space, in this paper, we propose a novel synthetic aperture radar (SAR) image denoising via sparse representation in Shearlet domain based on continuous cycle spinning. First, the Shearlet transform is applied to the noised SAR image. Second, a new optimal denoising model is constructed using the sparse representation model based on the cycle spinning theory. Finally, the alternate iteration algorithm is used to solve the optimal denoising model to obtain the denoised image. The experimental results show that the proposed method not only effectively suppresses the speckle noise and improves the peak signal-to-noise ratio of denoising SAR image, but also obviously improves the visual effect of the SAR image, especially by enhancing the texture of the SAR image.
Auteurs: Shuaiqi Liu;Ming Liu;Peifei Li;Jie Zhao;Zhihui Zhu;Xuehu Wang;
Apparue dans: IEEE Transactions on Geoscience and Remote Sensing
Date publication: 05.-2017, volume: 55, issue:5, pages: 2985 - 2992
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Satellite-Based Nowcasting of Extreme Rainfall Events Over Western Himalayan Region
Résumé:
Western Himalayan (WH) region is considered to be one of the most vulnerable spots for flash flooding-related natural disasters in the world. The confluence of moist air advected from Arabian sea with complex terrain has produced a series of extreme rainfall triggered disasters in recent past. However, the causal events leading to these enhanced episodes of precipitation lack clarity and thus flash flood forecasting still remains a big challenge. In this paper, we address the problem by studying cloud development over this region and its relationship with the underlying topography. Our results demonstrate that WH region is mostly inhabited by low-medium level clouds and governed by warm rain processes. Satellite-based analysis shows that in comparison to cloud top temperature, cloud top cooling rate (CTCR) is a better indicator for extreme rain producing events over this region. A model for nowcasting of extreme orographic rain events has thus been developed using the spatial characteristics of CTCR to predict potential locations for orographically induced severe precipitation events. The heavy rainfall nowcasts produced by this methodology, when compared with global precipitation fields, show very encouraging results. The probability of positive identification of a heavy rainfall event is 82.8%, with a false alarm rate of 29.7% and average lead time of 2–3 h. The insights provided by this study will give an impetus to the flash flood advance warning over WH region bringing about a significant beneficial societal impact.
Auteurs: Bipasha Paul Shukla;C. M. Kishtawal;Pradip K. Pal;
Apparue dans: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Date publication: 05.-2017, volume: 10, issue:5, pages: 1681 - 1686
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Scalable Design of Heterogeneous Networks
Résumé:
A systematic approach to the analysis and design of a class of large dynamical systems is presented. The approach allows decentralized control laws to be designed independently using only local subsystem models. Design can be conducted using standard techniques, including loopshaping based on Nyquist and Popov plots, $mathbf{H}_infty$ methods, and $mu$-synthesis procedures. The approach is applied to a range of network models, including those for consensus, congestion control, electrical power systems, and distributed optimization algorithms subject to delays.
Auteurs: Richard Pates;Glenn Vinnicombe;
Apparue dans: IEEE Transactions on Automatic Control
Date publication: 05.-2017, volume: 62, issue:5, pages: 2318 - 2333
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Scanning the Issue
Résumé:
Safety in Vehicle 1 Platooning: A Systematic Literature Review
Auteurs: Petros Ioannou;
Apparue dans: IEEE Transactions on Intelligent Transportation Systems
Date publication: 05.-2017, volume: 18, issue:5, pages: 1029 - 1032
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Scattering Property Analysis of Supraglacial Debris Using Target Decomposition on Polarimetric SAR Imagery
Résumé:
Supraglacial debris is widely distributed in the ablation zones of the glaciers in mountain valleys, and it influences glacier melting considerably. Polarimetric Synthetic Aperture Radar (SAR) presents promising results in terms of glacier classification and monitoring, but the scattering mechanism of debris has been unclear until now. In this paper, we attempted to verify the main scattering components of debris in the L- and C-bands polarimetric SAR images. A newly developed target decomposition method that is specially designed for debris is used to quantitatively analyze the scattering component. The method combines the X-Bragg surface scattering, double bounce, and completely random volume scattering models. The results from the target decomposition agree well with the scattering property analysis from the phase difference and entropy-alpha methods. The Keqikaer glacier, which is in the southern Tianshan Mountains, is selected as the study area. Phased-Array L-band SAR (PALSAR) images from the Advanced Land Observing Satellite (ALOS), PALSAR-2 images from ALOS-2, and RADARSAT-2 polarimetric SAR images are employed. The results show that in the C-band, surface scattering is dominant in debris, and it accounts for approximately 70% of the total power; in the L-band, volume scattering increases to a larger portion (approximately 40%), but remains slightly weaker than surface scattering (approximately 56%).
Auteurs: Lei Huang;Bang-sen Tian;Zhen Li;Jian-min Zhou;
Apparue dans: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Date publication: 05.-2017, volume: 10, issue:5, pages: 1843 - 1852
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Scenario Reduction With Submodular Optimization
Résumé:
Stochastic programming methods have been proven to deal effectively with the uncertainty and variability of renewable generation resources. However, the quality of the solution that they provide (as measured by cost and reliability metrics) depends on the accuracy and the number of scenarios used to model this uncertainty and variability. Scenario reduction techniques are used to manage the computational burden by selecting representative scenarios. The common drawback of existing scenario reduction techniques is that the number of representative scenarios is a user-defined parameter. We propose a scenario reduction algorithm based on submodular function optimization to endogenously optimize the number of scenarios as well as rank these scenarios. This algorithm is compared, both qualitatively and quantitatively, with the state-of-the-art fast forward selection algorithm.
Auteurs: Yishen Wang;Yuzong Liu;Daniel S. Kirschen;
Apparue dans: IEEE Transactions on Power Systems
Date publication: 05.-2017, volume: 32, issue:3, pages: 2479 - 2480
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Schottky Barrier in Organic Transistors
Résumé:
Organic FETs (OFETs) are essential devices in future flexible electronics. Yet, a crucial issue associated with electronic contact is still unsolved and our fundamental understanding remains very limited. Unlike many other previous reports talking about the contact resistance, in this paper, we specifically discuss its major root: the Schottky barrier, by comparison of the conventional metal-silicon contacts, and the unconventional metal–organic contacts, where the special features in OFETs are underlined. We not only examine the basics of the Schottky barrier but also the extrinsic effects as well as the characterization methods. The key factors in device fabrication are also reviewed in order to minimize the detrimental impacts of the Schottky barrier for obtaining optimum device performance.
Auteurs: Yong Xu;Huabin Sun;Yong-Young Noh;
Apparue dans: IEEE Transactions on Electron Devices
Date publication: 05.-2017, volume: 64, issue:5, pages: 1932 - 1943
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Screening Tests for Lasso Problems
Résumé:
This paper is a survey of dictionary screening for the lasso problem. The lasso problem seeks a sparse linear combination of the columns of a dictionary to best match a given target vector. This sparse representation has proven useful in a variety of subsequent processing and decision tasks. For a given target vector, dictionary screening quickly identifies a subset of dictionary columns that will receive zero weight in a solution of the corresponding lasso problem. These columns can be removed from the dictionary prior to solving the lasso problem without impacting the optimality of the solution obtained. This has two potential advantages: it reduces the size of the dictionary, allowing the lasso problem to be solved with less resources, and it may speed up obtaining a solution. Using a geometrically intuitive framework, we provide basic insights for understanding useful lasso screening tests and their limitations. We also provide illustrative numerical studies on several datasets.
Auteurs: Zhen James Xiang;Yun Wang;Peter J. Ramadge;
Apparue dans: IEEE Transactions on Pattern Analysis and Machine Intelligence
Date publication: 05.-2017, volume: 39, issue:5, pages: 1008 - 1027
Editeur: IEEE
Document complet vers site de l'éditeur
 
» SDBD: A Hierarchical Region-of-Interest Detection Approach in Large-Scale Remote Sensing Image
Résumé:
Region-of-interest (ROI) detection techniques are of great importance in the analysis of remote sensing images, especially in target detection, since the size of the image to be dealt with grows substantially with the improvement of spatial resolution. Most of current studies are not aiming at the specific type of object area detection, and the processed images are rather small compared to the size of the raw data acquired by high-resolution satellite. In this letter, a hierarchical task-driven ROI detection method, based on saliency and density, is proposed to address the detection of the potential object areas in large-scale remote sensing images. The proposed saliency and density-based detection method (SDBD) integrates bottom–up and top–down strategies, where the saliency-based multilevel histogram contrast is presented in the bottom–up phase to obtain the preliminary regions, while the centroid density distribution index (CDDI) is defined in the top–down scheme to refine the previous results. Specifically, superpixel segmentation is introduced in this letter to narrow down the ROI candidates. SDBD is capable of extracting ROI of different objects by adjusting the threshold of CDDI. The experiments are conducted on two data sets to extract ROIs of storage tanks and residence. Experimental results demonstrate that the proposed method is effective in identifying ROI in large-scale data.
Auteurs: Tong Li;Junping Zhang;Xiaochen Lu;Ye Zhang;
Apparue dans: IEEE Geoscience and Remote Sensing Letters
Date publication: 05.-2017, volume: 14, issue:5, pages: 699 - 703
Editeur: IEEE
Document complet vers site de l'éditeur
 
» SDN-Based Anchor Scheduling Scheme for Localization in Heterogeneous WSNs
Résumé:
In this letter, the anchor scheduling scheme for localization in heterogeneous wireless sensor networks is studied. In order to minimize the number of actively participating anchors to prolong the network lifetime, we propose a centralized anchor scheduling scheme on the basis of the software-defined networking (SDN) paradigm. First, an expression evaluating the connectivity degree of an agent is derived and used to judge if this agent has desired number of connected anchors for its localization. Then, the state of each anchor is determined by the SDN controller through a flow table via sensor OpenFlow. Simulations show that the proposed anchor scheduling scheme reduces the number of active anchors and prolongs the network lifetime. It can also be shown that this scheme ensures the desired number of anchors for the localization, and can tradeoff the localization accuracy for energy by ensuring a better balance of energy consumption among minimum number of active anchors.
Auteurs: Yaping Zhu;Feng Yan;Yueyue Zhang;Rui Zhang;Lianfeng Shen;
Apparue dans: IEEE Communications Letters
Date publication: 05.-2017, volume: 21, issue:5, pages: 1127 - 1130
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Search Based Software Engineering [Guest Editorial]
Résumé:
The articles in this special section focus on search-based software engineering. Search Based Software Engineering (SBSE) consists of the application of computational intelligence (CI) algorithms to hard optimization problems in software engineering (SE). It has become an important application field for CI. The term SBSE was coined by Harman and Jones in 2001, although there was work on the application of CI algorithms to SE before this date. After more than fifteen years development, CI algorithms have been used to solve SE tasks in almost all the stages of an SE lifecycle, including requirements, designing, coding, testing and maintenance. solved by three steps.
Auteurs: He Jiang;Ke Tang;Justyna Petke;Mark Harman;
Apparue dans: IEEE Computational Intelligence Magazine
Date publication: 05.-2017, volume: 12, issue:2, pages: 23 - 71
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Second-Order and Moderate Deviations Asymptotics for Successive Refinement
Résumé:
We derive the optimal second-order coding region and moderate deviations constant for successive refinement source coding with a joint excess-distortion probability constraint. We consider two scenarios: 1) a discrete memoryless source (DMS) and arbitrary distortion measures at the decoders and 2) a Gaussian memoryless source (GMS) and quadratic distortion measures at the decoders. For a DMS with arbitrary distortion measures, we prove an achievable second-order coding region, using type covering lemmas by Kanlis and Narayan and by No, Ingber, and Weissman. We prove the converse using the perturbation approach by Gu and Effros. When the DMS is successively refinable, the expressions for the second-order coding region and the moderate deviations constant are simplified and easily computable. For this case, we also obtain new insights on the second-order behavior compared with the scenario where separate excess-distortion proabilities are considered. For example, we describe a DMS, for which the optimal second-order region transitions from being characterizable by a bivariate Gaussian to a univariate Gaussian, as the distortion levels are varied. We then consider a GMS with quadratic distortion measures. To prove the direct part, we make use of the sphere covering theorem by Verger–Gaugry, together with appropriately-defined Gaussian type classes. To prove the converse, we generalize Kostina and Verdú’s one-shot converse bound for point-to-point lossy source coding. We remark that this proof is applicable to general successively refinable sources. In the proofs of the moderate deviations results for both scenarios, we follow a strategy similar to that for the second-order asymptotics and use the moderate deviations principle.
Auteurs: Lin Zhou;Vincent Y. F. Tan;Mehul Motani;
Apparue dans: IEEE Transactions on Information Theory
Date publication: 05.-2017, volume: 63, issue:5, pages: 2896 - 2921
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Secure Communications in Millimeter Wave Ad Hoc Networks
Résumé:
Wireless networks with directional antennas, like millimeter wave (mmWave) networks, have enhanced security. For a large-scale mmWave ad hoc network in which eavesdroppers are randomly located, however, eavesdroppers can still intercept the confidential messages, since they may reside in the signal beam. This paper explores the potential of physical layer security in mmWave ad hoc networks. Specifically, we characterize the impact of mmWave channel characteristics, random blockages, and antenna gains on the secrecy performance. For the special case of uniform linear array (ULA), a tractable approach is proposed to evaluate the average achievable secrecy rate. We also characterize the impact of artificial noise in such networks. Our results reveal that in the low transmit power regime, the use of low mmWave frequency achieves better secrecy performance, and when increasing transmit power, a transition from low mmWave frequency to high mmWave frequency is demanded for obtaining a higher secrecy rate. More antennas at the transmitting nodes are needed to decrease the antenna gain obtained by the eavesdroppers when using ULA. Eavesdroppers can intercept more information by using a wide beam pattern. Furthermore, the use of artificial noise may be ineffective for enhancing the secrecy rate.
Auteurs: Yongxu Zhu;Lifeng Wang;Kai-Kit Wong;Robert W. Heath;
Apparue dans: IEEE Transactions on Wireless Communications
Date publication: 05.-2017, volume: 16, issue:5, pages: 3205 - 3217
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Secure Full-Duplex Two-Way Relaying Networks With Optimal Relay Selection
Résumé:
The secrecy outage probability (SOP) of cooperative communication systems with optimal relay selection (ORS) scheme in the presence of an eavesdropper is investigated by implementing decode-and-forward-based full-duplex (FD) two-way relayingmode. Under Rayleigh fading assumptions, the closed-form expressions for the distributions of end-to-end signal-to-interference-plus-noise ratio in each wireless link are derived. Furthermore, the closed-form expression for the exact SOP of the proposed ORS scheme is given out. Numerical results show that the SOP of the proposed system can be substantially impacted by several parameters involved, including the number of relays, the average signal-to-noise ratio (SNR) of eavesdropper links, and the average residual self-interference (SI) imposed on the FD relays. In particular, the impact of residual SI is shown to be more obvious in terms of eroding the system’s secrecy performance in a low-to-medium SNR regime than in a high-SNR regime. As long as the residual SI power is not beyond the background noise level, the proposed FD-TWC scheme can always outperform the conventional half-duplex mode in terms of SOP.
Auteurs: Bin Zhong;Zhongshan Zhang;
Apparue dans: IEEE Communications Letters
Date publication: 05.-2017, volume: 21, issue:5, pages: 1123 - 1126
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Secure Orthogonal Transform Division Multiplexing (OTDM) Waveform for 5G and Beyond
Résumé:
In this letter, a secure waveform design for future 5G wireless system is proposed. The developed waveform referred to as secure orthogonal transform division multiplexing (OTDM) waveform, is designed to diagonalize the multi-path channel matrix of only the legitimate receiver (Bob), while degrading eavesdropper’s reception. In particular, instead of using fixed exponential basis functions, generated by IFFT and FFT as in OFDM, orthogonal transform basis functions, which are extracted from the Bob’s channel, are utilized to modulate and demodulate the data symbols securely. The simulation results prove that the proposed design provides a significant practical security gap between the Bob’s and Eve’s performance. The design is shown to be robust against channel imperfection, and it neither sacrifices communication resources nor considers any knowledge on the eavesdropper’s channel. Besides security, the scheme results in a higher SNR, leading to a 3-5-dB gain over OFDM at BER = ${10^{-3}}$ .
Auteurs: Jehad M. Hamamreh;Huseyin Arslan;
Apparue dans: IEEE Communications Letters
Date publication: 05.-2017, volume: 21, issue:5, pages: 1191 - 1194
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Securing Coding-Based Cloud Storage Against Pollution Attacks
Résumé:
The widespread diffusion of distributed and cloud storage solutions has changed dramatically the way users, system designers, and service providers manage their data. Outsourcing data on remote storage provides indeed many advantages in terms of both capital and operational costs. The security of data outsourced to the cloud, however, still represents one of the major concerns for all stakeholders. Pollution attacks, whereby a set of malicious entities attempt to corrupt stored data, are one of the many risks that affect cloud data security. In this paper we deal with pollution attacks in coding-based block-level cloud storage systems, i.e., systems that use linear codes to fragment, encode, and disperse virtual disk sectors across a set of storage nodes to achieve desired levels of redundancy, and to improve reliability and availability without sacrificing performance. Unfortunately, the effects of a pollution attack on linear coding can be disastrous, since a single polluted fragment can propagate pervasively in the decoding phase, thus hampering the whole sector. In this work we show that, using rateless codes, we can design an early pollution detection algorithm able to spot the presence of an attack while fetching the data from cloud storage during the normal disk reading operations. The alarm triggers a procedure that locates the polluting nodes using the proposed detection mechanism along with statistical inference. The performance of the proposed solution is analyzed under several aspects using both analytical modelling and accurate simulation using real disk traces. Our results show that the proposed approach is very robust and is able to effectively isolate the polluters, even in harsh conditions, provided that enough data redundancy is used.
Auteurs: Cosimo Anglano;Rossano Gaeta;Marco Grangetto;
Apparue dans: IEEE Transactions on Parallel and Distributed Systems
Date publication: 05.-2017, volume: 28, issue:5, pages: 1457 - 1469
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Security Analysis of LTE/SAE Networks Under De-synchronization Attack for Hyper-Erlang Distributed Residence Time
Résumé:
In this letter, we analyze the security of a long term evolution/system architecture evolution-based network in the presence of de-synchronization attack. For a random mobile user, with the mobility management entity residence time distributed as a Hyper-Erlang random variable, we derive closed form expressions for the distribution of key exposure time, expected volume of exposed packets, and expected additional signaling overhead rate. Furthermore, we present a novel framework for a cellular operator to select the trade-off between security and computational complexity for various practical scenarios. Finally, we verify the proposed results through extensive simulations.
Auteurs: Pranay Agarwal;Dhanuja Elizabeth Thomas;Abhinav Kumar;
Apparue dans: IEEE Communications Letters
Date publication: 05.-2017, volume: 21, issue:5, pages: 1055 - 1058
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Security-Aware 2.5D Integrated Circuit Design Flow Against Hardware IP Piracy
Résumé:
To combat security threats to integrated circuit (IC) fabrication outsourcing, 2.5D integration can obfuscate the outsourced design by lifting a portion of the wires into an interposer layer. A security-aware physical design flow for 2.5D IC technology can then help defend against attacks by increasing the layout and functionality obfuscation.
Auteurs: Yang Xie;Chongxi Bao;Ankur Srivastava;
Apparue dans: Computer
Date publication: 05.-2017, volume: 50, issue:5, pages: 62 - 71
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Seeking Opportunities [My First Job]
Résumé:
Reports on a recent engineering graduate's experience after college and the career path taken.
Auteurs: Lori Hogan;
Apparue dans: IEEE Potentials
Date publication: 05.-2017, volume: 36, issue:3, pages: 44 - 46
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Segmentation-Based Fine Registration of Very High Resolution Multitemporal Images
Résumé:
In this paper, a segmentation-based approach to fine registration of multispectral and multitemporal very high resolution (VHR) images is proposed. The proposed approach aims at estimating and correcting the residual local misalignment [also referred to as registration noise (RN)] that often affects multitemporal VHR images even after standard registration. The method extracts automatically a set of object representative points associated with regions with homogeneous spectral properties (i.e., objects in the scene). Such points result to be distributed all over the considered scene and account for the high spatial correlation of pixels in VHR images. Then, it estimates the amount and direction of residual local misalignment for each object representative point by exploiting residual local misalignment properties in a multiple displacement analysis framework. To this end, a multiscale differential analysis of the multispectral difference image is employed for modeling the statistical distribution of pixels affected by residual misalignment (i.e., RN pixels) and detect them. The RN is used to perform a segmentation-based fine registration based on both temporal and spatial correlation. Accordingly, the method is particularly suitable to be used for images with a large number of border regions like VHR images of urban scenes. Experimental results obtained on both simulated and real multitemporal VHR images confirm the effectiveness of the proposed method.
Auteurs: Youkyung Han;Francesca Bovolo;Lorenzo Bruzzone;
Apparue dans: IEEE Transactions on Geoscience and Remote Sensing
Date publication: 05.-2017, volume: 55, issue:5, pages: 2884 - 2897
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Selecting Representative Days for Capturing the Implications of Integrating Intermittent Renewables in Generation Expansion Planning Problems
Résumé:
Due to computational restrictions, energy-system optimization models (ESOMs) and generation expansion planning models (GEPMs) frequently represent intraannual variations in demand and supply by using the data of a limited number of representative historical days. The vast majority of the current approaches to select a representative set of days relies on either simple heuristics or clustering algorithms and comparison of different approaches is restricted to different clustering algorithms. This paper contributes by: i) proposing criteria and metrics for evaluating representativeness, ii) providing a novel optimization-based approach to select a representative set of days, and iii) evaluating and comparing the developed approach to multiple approaches available from the literature. The developed optimization-based approach is shown to achieve more accurate results than the approaches available from the literature. As a consequence, by applying this approach to select a representative set of days, the accuracy of ESOMs/GEPMs can be improved without increasing the computational cost. The main disadvantage is that the approach is computationally costly and requires an implementation effort.
Auteurs: Kris Poncelet;Hanspeter Höschle;Erik Delarue;Ana Virag;William D’haeseleer;
Apparue dans: IEEE Transactions on Power Systems
Date publication: 05.-2017, volume: 32, issue:3, pages: 1936 - 1948
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Selection of Reference Channels Based on Mutual Information for Frequency-Dependent Subtraction Method Applied to Fetal Biomagnetic Signals
Résumé:
Objective: We propose a method that uses minimal redundancy and maximal relevance (mRMR) based on mutual information as criteria to automatically select references for the frequency-dependent subtraction (SUBTR) method to attenuate maternal (mMCG) and fetal (fMCG) magnetocardiograms of fetal magnetoencephalography recordings. Methods: mRMR is calculated between all channels and mMCG/fMCG target channels and the most promising sensors are used as references to perform SUBTR. We measured the performance of SUBTR at removing interferences in two steps for different number of references in 38 real datasets. The evaluation was based on the MCG amplitude reduction. We compared the performance of the mRMR approach with random selection of references. Results: Significant differences in interference removal were found when a distinct number of references were chosen by mRMR compared to random selection. Conclusion: mRMR provides an effective tool to automatically select a set of featured references. Significance: Although we show the utility of the mRMR method to biomagnetic signals, the approach can easily be adapted to sensor array data from other applications.
Auteurs: D. Escalona-Vargas;E. R. Siegel;P. Murphy;C. L. Lowery;H. Eswaran;
Apparue dans: IEEE Transactions on Biomedical Engineering
Date publication: 05.-2017, volume: 64, issue:5, pages: 1115 - 1122
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Self-Balancing Decentralized Distributed Platform for Urban Traffic Simulation
Résumé:
Microscopic traffic simulation is the most accurate tool for predictive analytics in urban environments. However, the amount of workload (i.e., cars simulated simultaneously) can be challenging for classical systems, particularly for scenarios requiring faster than real-time processing (e.g., for emergency units having to make quick decisions on traffic management). This challenge can be tackled with distributed simulations by sharing the load between simulation engines running on different computing nodes, hence balancing the processing power required. This paper studies the performance of dSUMO, i.e., a distributed microscopic traffic simulator. dSUMO is fully decentralized and can dynamically balance the workload between its computing nodes, hence showing important improvements against classical, centralized and not dynamic, solutions.
Auteurs: Quentin Bragard;Anthony Ventresque;Liam Murphy;
Apparue dans: IEEE Transactions on Intelligent Transportation Systems
Date publication: 05.-2017, volume: 18, issue:5, pages: 1190 - 1197
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Self-Balancing Signal Conditioning Circuit for a Novel Noncontact Inductive Displacement Sensor
Résumé:
A noncontact inductive type displacement sensor is presented here. The sensor is realized with an inductive voltage divider possessing a floating wiper operated by a self-balancing feedback type signal conditioning circuit. The output of the self-balancing signal conditioning circuit is: 1) linear to the displacement of the floating wiper and 2) independent of the coupling capacitance that arises due to the air gap between the inductive element and the floating wiper. Error analysis and simulation studies presented here bring out the pitfalls that have to be avoided to obtain an optimal design for linear or angular displacement sensing. Experimentation on an emulated sensor and results obtained from a prototype angle sensor built and tested establish the efficacy of the proffered technique.
Auteurs: Srinivas Rana;Boby George;V. Jagadeesh Kumar;
Apparue dans: IEEE Transactions on Instrumentation and Measurement
Date publication: 05.-2017, volume: 66, issue:5, pages: 985 - 991
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Self-Biased Differential Rectifier With Enhanced Dynamic Range for Wireless Powering
Résumé:
A self-biased cross-coupled differential rectifier is proposed with enhanced power-conversion efficiency (PCE) over an extended range of input power. A prototype is designed for ultrahigh-frequency (UHF) 433-MHz radio-frequency power-harvesting applications and is implemented using a 0.18- $mutext{m}$ CMOS technology. The proposed rectifier architecture is compared with the conventional cross-coupled rectifier. It demonstrates an improvement of more than 40% in the rectifier PCE and an input power range extension of more than 50% relative to the conventional cross-coupled rectifier. A sensitivity of −15.2-dBm (30- $mutext{W}$) input power for 1-V output voltage and a peak PCE of 65% are achieved for a 50- $text{k}Omega$ load.
Auteurs: Mahmoud H. Ouda;Waleed Khalil;Khaled N. Salama;
Apparue dans: IEEE Transactions on Circuits and Systems II: Express Briefs
Date publication: 05.-2017, volume: 64, issue:5, pages: 515 - 519
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Self-Calibrated Microwave Characterization of High-Speed Optoelectronic Devices by Heterodyne Spectrum Mapping
Résumé:
A four-in-one electrical method is proposed based on heterodyne spectrum mapping for self-calibrated frequency response measurements of high-speed semiconductor laser diodes, Mach–Zehnder modulators, phase modulators, and photodetectors with a shared self-heterodyne interferometer. The self-heterodyne interferometer provides mapping of the desired optical spectrum components from the optical domain to electrical domain, and allows indirect but self-calibrated measurement of these optical spectra in the electrical domain. Frequency responses including modulation index of semiconductor laser diodes, half-wave voltage and chirp parameter of Mach–Zehnder modulators, half-wave voltage of phase modulators, and responsivity of photodetectors are experimentally extracted with this method, and compared to the results obtained with conventional methods for accuracy.
Auteurs: Shangjian Zhang;Chong Zhang;Heng Wang;Xinhai Zou;Yali Zhang;Yong Liu;John E. Bowers;
Apparue dans: Journal of Lightwave Technology
Date publication: 05.-2017, volume: 35, issue:10, pages: 1952 - 1961
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Self-Gravitational Instability of Collisional Dusty Plasma With Dust Charge Variation and Radiative Effects
Résumé:
The self-gravitational instability of partially ionized dusty plasma with radiative effects of electrons and ions, dust polarization force, and dust charge fluctuation has been studied. Using basic sets of fluid equations for ion, electron, neutral, and dust components, a general dispersion relation is derived. In the dynamics of dust charge, an equilibrium dust charge inhomogeneity along with the dust charge fluctuation is also considered. It is found that the presence of radiative cooling of ions and electrons, polarization force, and dust charge fluctuation significantly affects the criterion as well as the growth rate of self-gravitational instability while the dust charge inhomogeneity and dust-neutral collisions affect only the growth rate of instability. The outcomes of this paper are useful in dusty molecular clouds.
Auteurs: Prerana Sharma;Archana Patidar;
Apparue dans: IEEE Transactions on Plasma Science
Date publication: 05.-2017, volume: 45, issue:5, pages: 774 - 785
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Self-Heating Phase-Change Memory-Array Demonstrator for True Random Number Generation
Résumé:
The stochastic nature of the switching mechanism of phase-change memory (PCM) arrays, which is a drawback for memory applications, can fruitfully be exploited to implement primitives for hardware security. By applying a set voltage pulse, whose amplitude corresponds to a switching probability of 50%, to a memory array initially placed in the full-reset state, half of the memory bits are statistically switched and programmed to state “1,” whereas the remainder of the bits persist in state “0.” Such a natural randomness can be exploited to create a true random number generator (TRNG), which is the building block of cryptographic applications. The feasibility of a TRNG by means of self-heating PCM cells is assessed and demonstrated through simulations based upon the random network model, i.e., a microscopic transport model previously developed and tested by the authors.
Auteurs: Enrico Piccinini;Rossella Brunetti;Massimo Rudan;
Apparue dans: IEEE Transactions on Electron Devices
Date publication: 05.-2017, volume: 64, issue:5, pages: 2185 - 2192
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Self-Regulated Bias Circuits for Efficient Adjustment of the Operating Temperature of Chemoresistive Gas Sensors
Résumé:
A bias circuit is required for chemoresistive gas sensors to appropriately adjust their operating temperature and facilitate the readout of their output response. If the sensor is properly biased, its overall performance regarding sensitivity, selectivity, and power consumption can be greatly enhanced. We have introduced the concept of self-regulated biasing as an alternative to the conventional fixed biasing methods. In self-regulated bias circuits, the gas sensor is an active component in its own bias circuit, so the operating point is dynamically adjusted during a measurement. This will provide the sensor with different modes of operation. Here, we have proposed two self-regulated bias circuits the operation of which is analytically and experimentally studied. Results show that the first circuit puts the sensor in a low-power idle mode when no target gas is presented, and hence the power consumption is considerably reduced and the sensor lifetime may be prolonged. The second circuit puts the sensor in a power-down mode upon sensing a gas. This state is held until the circuit is reset. So the second bias circuit acts as a gas latch besides other important features like increased safety in explosive environments. Obviously, other self-regulated bias circuits can be designed for additional desired modes of operations.
Auteurs: Vahid Ghafarinia;Mohammad Maleki;
Apparue dans: IEEE Sensors Journal
Date publication: 05.-2017, volume: 17, issue:10, pages: 2984 - 2991
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Self-Taught Feature Learning for Hyperspectral Image Classification
Résumé:
In this paper, we study self-taught learning for hyperspectral image (HSI) classification. Supervised deep learning methods are currently state of the art for many machine learning problems, but these methods require large quantities of labeled data to be effective. Unfortunately, existing labeled HSI benchmarks are too small to directly train a deep supervised network. Alternatively, we used self-taught learning, which is an unsupervised method to learn feature extracting frameworks from unlabeled hyperspectral imagery. These models learn how to extract generalizable features by training on sufficiently large quantities of unlabeled data that are distinct from the target data set. Once trained, these models can extract features from smaller labeled target data sets. We studied two self-taught learning frameworks for HSI classification. The first is a shallow approach that uses independent component analysis and the second is a three-layer stacked convolutional autoencoder. Our models are applied to the Indian Pines, Salinas Valley, and Pavia University data sets, which were captured by two separate sensors at different altitudes. Despite large variation in scene type, our algorithms achieve state-of-the-art results across all the three data sets.
Auteurs: Ronald Kemker;Christopher Kanan;
Apparue dans: IEEE Transactions on Geoscience and Remote Sensing
Date publication: 05.-2017, volume: 55, issue:5, pages: 2693 - 2705
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Semantic Segmentation of Remote Sensing Imagery Using an Object-Based Markov Random Field Model With Auxiliary Label Fields
Résumé:
The Markov random field (MRF) model has attracted great attention in the field of image segmentation. However, most MRF-based methods fail to resolve segmentation misclassification problems for high spatial resolution remote sensing images due to insufficiently using the hierarchical semantic information. In order to solve such a problem, this paper proposes an object-based MRF model with auxiliary label fields that can capture more macro and detailed information and apply it to the semantic segmentation of high spatial resolution remote sensing images. Specifically, apart from the label field, two auxiliary label fields are first introduced into the proposed model for interpreting remote sensing images from different perspectives, which are implemented by setting a different number of auxiliary classes. Then, the multilevel logistic model is used to describe the interactions within each label field, and a conditional probability distribution is developed to model the interactions between label fields. A net context structure is established among them to model the interactions of classes within and between label fields. A principled probabilistic inference is suggested to solve the proposed model by iteratively renewing the label field and auxiliary label fields, in which different information of auxiliary label fields can be integrated into the label field during iterations. Experiments on different remote sensing images demonstrate that our model produces more accurate segmentation than the state-of-the-art MRF-based methods. If some prior information is added, the proposed model can produce accurate results even in complex areas.
Auteurs: Chen Zheng;Yun Zhang;Leiguang Wang;
Apparue dans: IEEE Transactions on Geoscience and Remote Sensing
Date publication: 05.-2017, volume: 55, issue:5, pages: 3015 - 3028
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Semi-External Memory Sparse Matrix Multiplication for Billion-Node Graphs
Résumé:
Sparse matrix multiplication is traditionally performed in memory and scales to large matrices using the distributed memory of multiple nodes. In contrast, we scale sparse matrix multiplication beyond memory capacity by implementing sparse matrix dense matrix multiplication (SpMM) in a semi-external memory (SEM) fashion; i.e., we keep the sparse matrix on commodity SSDs and dense matrices in memory. Our SEM-SpMM incorporates many in-memory optimizations for large power-law graphs. It outperforms the in-memory implementations of Trilinos and Intel MKL and scales to billion-node graphs, far beyond the limitations of memory. Furthermore, on a single large parallel machine, our SEM-SpMM operates as fast as the distributed implementations of Trilinos using five times as much processing power. We also run our implementation in memory (IM-SpMM) to quantify the overhead of keeping data on SSDs. SEM-SpMM achieves almost 100 percent performance of IM-SpMM on graphs when the dense matrix has more than four columns; it achieves at least 65 percent performance of IM-SpMM on all inputs. We apply our SpMM to three important data analysis tasks—PageRank, eigensolving, and non-negative matrix factorization—and show that our SEM implementations significantly advance the state of the art.
Auteurs: Da Zheng;Disa Mhembere;Vince Lyzinski;Joshua T. Vogelstein;Carey E. Priebe;Randal Burns;
Apparue dans: IEEE Transactions on Parallel and Distributed Systems
Date publication: 05.-2017, volume: 28, issue:5, pages: 1470 - 1483
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Semiconductor-Free Nonvolatile Resistive Switching Memory Devices Based on Metal Nanogaps Fabricated on Flexible Substrates via Adhesion Lithography
Résumé:
Electronic memory cells are of critical importance in modern-day computing devices, including emerging technology sectors such as large-area printed electronics. One technology that has being receiving significant interest in recent years is resistive switching primarily due to its low dimensionality and nonvolatility. Here, we describe the development of resistive switching memory device arrays based on empty aluminum nanogap electrodes. By employing adhesion lithography, a low-temperature and large-area compatible nanogap fabrication technique, dense arrays of memory devices are demonstrated on both rigid and flexible plastic substrates. As-prepared devices exhibit nonvolatile memory operation with stable endurance, resistance ratios > $10^{4}$ and retention times of several months. An intermittent analysis of the electrode microstructure reveals that controlled resistive switching is due to migration of metal from the electrodes into the nanogap under the application of an external electric field. This alternative form of resistive random access memory is promising for use in emerging sectors such as large-area electronics as well as in electronics for harsh environments, e.g., space, high/low temperature, magnetic influences, radiation, vibration, and pressure.
Auteurs: James Semple;Gwenhivir Wyatt-Moon;Dimitra G. Georgiadou;Martyn A. McLachlan;Thomas D. Anthopoulos;
Apparue dans: IEEE Transactions on Electron Devices
Date publication: 05.-2017, volume: 64, issue:5, pages: 1973 - 1980
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Semisupervised Hyperspectral Image Classification Using Small Sample Sizes
Résumé:
Hyperspectral image classification is a challenging task when only a small number of labeled samples are available due to the difficult, expensive, and time-consuming ground campaigns required to collect the ground-truth information. It is also known that the classification performance is highly dependent on the size of the labeled data. In this letter, a semisupervised learning-based hyperspectral image classification framework is proposed as a solution to these problems. One of the contributions of this letter is the selection of the initial labeled training samples with a subtractive clustering-based approach, which provides the most informative samples for graph-based self-training. Another contribution is the decision-level combination of results obtained by support vector machines and kernel sparse representation classifiers. Additionally, a combination of the spatial and spectral information by creating a window structure is also proposed via integrating contextual information from the neighboring pixels. The explanatory experiments confirm that the proposed framework offers better and more promising results, even using a small number of initial labeled samples.
Auteurs: Muhammet Said Aydemir;Gokhan Bilgin;
Apparue dans: IEEE Geoscience and Remote Sensing Letters
Date publication: 05.-2017, volume: 14, issue:5, pages: 621 - 625
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Semisupervised Online Multikernel Similarity Learning for Image Retrieval
Résumé:
Metric learning plays a fundamental role in the fields of multimedia retrieval and pattern recognition. Recently, an online multikernel similarity (OMKS) learning method has been presented for content-based image retrieval (CBIR), which was shown to be promising for capturing the intrinsic nonlinear relations within multimodal features from large-scale data. However, the similarity function in this method is learned only from labeled images. In this paper, we present a new framework to exploit unlabeled images and develop a semisupervised OMKS algorithm. The proposed method is a multistage algorithm consisting of feature selection, selective ensemble learning, active sample selection, and triplet generation. The novel aspects of our work are the introduction of classification confidence to evaluate the labeling process and select the reliably labeled images to train the metric function, and a method for reliable triplet generation, where a new criterion for sample selection is used to improve the accuracy of label prediction for unlabeled images. Our proposed method offers advantages in challenging scenarios, in particular, for a small set of labeled images with high-dimensional features. Experimental results demonstrate the effectiveness of the proposed method as compared with several baseline methods.
Auteurs: Jianqing Liang;Qinghua Hu;Wenwu Wang;Yahong Han;
Apparue dans: IEEE Transactions on Multimedia
Date publication: 05.-2017, volume: 19, issue:5, pages: 1077 - 1089
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Sensitive Element on Cross-Wound Helices
Résumé:
A novel sensitive element, formed by cross-wound helices, is investigated and described in this paper. Based on the outstanding properties of the coupled slow-wave structures, such as splitting electric and magnetic fields and the multiple increase in the slowdown, this sensitive element combines the advantages of the elements with distributed parameters and the relatively low operating frequencies. Concentrating the electromagnetic field in a measurement volume, caused by the slowing of the wave, and splitting electric and magnetic fields lead to a significant increase in sensitivity. The main properties and some characteristics of the cross-wound helices are analyzed, calculated, and measured. The practical realization of the described sensitive element is demonstrated on the example of a linear displacement sensor, patented, and placed on the market.
Auteurs: Yuriy N. Pchelnikov;Andrey A. Yelizarov;
Apparue dans: IEEE Sensors Journal
Date publication: 05.-2017, volume: 17, issue:9, pages: 2734 - 2740
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Sensor Fusion-Based Low-Cost Vehicle Localization System for Complex Urban Environments
Résumé:
This paper proposes a sensor fusion-based low-cost vehicle localization system. The proposed system fuses a global positioning system (GPS), an inertial measurement unit (IMU), a wheel speed sensor, a single front camera, and a digital map via the particle filter. This system is advantageous over previous methods from the perspective of mass production. First, it only utilizes low-cost sensors. Second, it requires a low-volume digital map where road markings are expressed by a minimum number of points. Third, it consumes a small computational cost and has been implemented in a low-cost real-time embedded system. Fourth, it requests the perception sensor module to transmit a small amount of information to the vehicle localization module. Last, it was quantitatively evaluated in a large-scale database.
Auteurs: Jae Kyu Suhr;Jeungin Jang;Daehong Min;Ho Gi Jung;
Apparue dans: IEEE Transactions on Intelligent Transportation Systems
Date publication: 05.-2017, volume: 18, issue:5, pages: 1078 - 1086
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Sensor Optimization in Smart Insoles for Post-Stroke Gait Asymmetries Using Total Variation and L1 Distances
Résumé:
By deploying pressure sensors on insoles, the forces exerted by the different parts of the foot when performing tasks standing up can be captured. The number and location of sensors to use are important factors in order to enhance the accuracy of parameters used in assessment while minimizing the cost of the device by reducing the number of deployed sensors. Selecting the best locations and the required number of sensors depends on the application and the features that we want to assess. In this paper, we present a computational process to select the optimal set of sensors to characterize gait asymmetries and plantar pressure patterns for stroke survivors based upon the total variation and L1 distances. The proposed mechanism is ecologically validated in a real environment with 14 stroke survivors and 14 control users. The number of sensors is reduced to 4, minimizing the cost of the device both for commercial users and companies and enhancing the cost to benefit ratio for its uptake from a national healthcare system. The results show that the sensors that better represent the gait asymmetries for healthy controls are the sensors under the big toe and midfoot and the sensors in the forefoot and midfoot for stroke survivors. The results also show that all four regions of the foot (toes, forefoot, midfoot, and heel) play an important role for plantar pressure pattern reconstruction for stroke survivors, while the heel and forefoot region are more prominent for healthy controls.
Auteurs: Mario Muñoz-Organero;Jack Parker;Lauren Powell;Richard Davies;Sue Mawson;
Apparue dans: IEEE Sensors Journal
Date publication: 05.-2017, volume: 17, issue:10, pages: 3142 - 3151
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Sentient Tools and the Future of Work
Résumé:
People work and collaborate differently, so believing that there can only be one type of AI is too limiting.
Auteurs: Brian David Johnson;
Apparue dans: Computer
Date publication: 05.-2017, volume: 50, issue:5, pages: 99 - 99
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Sentinel-1 Interferometric SAR Mapping of Precipitable Water Vapor Over a Country-Spanning Area
Résumé:
This paper presents a methodology to generate maps of atmosphere's precipitable water vapor (PWV) over large areas with a length of hundreds of kilometers and a width of about 250 km, based on the use of interferometric Sentinel-1A/B C-band synthetic aperture radar (SAR) data with a high spatial resolution of 5 × 20 m2 and the revisiting time of six days. An algorithm to calibrate and merge PWV maps from different swaths of Sentinel-1 acquired along the same track, using global navigation satellite system (GNSS) measurements, is described. The proposed methodology is tested on Sentinel-1A SAR images acquired over the Iberian Peninsula, along both descending and ascending tracks. The assessment with an independent set of GNSS measurements shows a mean difference of a fraction of millimeter and a dispersion lower than 2 mm. Both the use of Sentinel-1A/B SAR images and the proposed methodology open new perspectives on the application of SAR meteorology for the high-resolution mapping of PWV over large region-spanning areas and the assimilation of interferometric SAR data into numerical weather models.
Auteurs: Pedro Mateus;João Catalão;Giovanni Nico;
Apparue dans: IEEE Transactions on Geoscience and Remote Sensing
Date publication: 05.-2017, volume: 55, issue:5, pages: 2993 - 2999
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Sequential Monte Carlo Instant Radiosity
Résumé:
Instant Radiosity and its derivatives are interactive methods for efficiently estimating global (indirect) illumination. They represent the last indirect bounce of illumination before the camera as the composite radiance field emitted by a set of virtual point light sources (VPLs). In complex scenes, current algorithms suffer from a difficult combination of two issues: it remains a challenge to distribute VPLs in a manner that simultaneously gives a high-quality indirect illumination solution for each frame, and to do so in a temporally coherent manner. We address both issues by building, and maintaining over time, an adaptive and temporally coherent distribution of VPLs in locations where they bring indirect light to the image. We introduce a novel heuristic sampling method that strives to only move as few of the VPLs between frames as possible. The result is, to the best of our knowledge, the first interactive global illumination algorithm that works in complex, highly-occluded scenes, suffers little from temporal flickering, supports moving cameras and light sources, and is output-sensitive in the sense that it places VPLs in locations that matter most to the final result.
Auteurs: Peter Hedman;Tero Karras;Jaakko Lehtinen;
Apparue dans: IEEE Transactions on Visualization and Computer Graphics
Date publication: 05.-2017, volume: 23, issue:5, pages: 1442 - 1453
Editeur: IEEE
Document complet vers site de l'éditeur
 
» SESAM $Q$ -Switched Ho3+-Doped ZBLAN Fiber Laser at 1190 nm
Résumé:
We report a semiconductor saturable absorber mirror $Q$ -switched holmium (Ho3+)-doped ZrF4–BaF2–LaF3–AlF3–NaF fiber laser operating at ~1190 nm in a linear cavity. Stable $Q$ -switched operation was established at a threshold pump power of 92.8 mW with a repetition rate of 26.1 kHz and a pulsewidth of $4~mu text{s}$ . The repetition rate increased and the pulsewidth decreased with an increasing pump power. When the pump power was increased to 830 mW, 800-ns $Q$ -switched pulses with a pulse energy of $0.18~mu text{J}$ at a repetition rate of 170 kHz were generated.
Auteurs: Yuchen Wang;Xiushan Zhu;Chuanxiang Sheng;Li Li;Qian Chen;Jie Zong;Kort Wiersma;Arturo Chavez-Pirson;R. A. Norwood;N. Peyghambarian;
Apparue dans: IEEE Photonics Technology Letters
Date publication: 05.-2017, volume: 29, issue:9, pages: 743 - 746
Editeur: IEEE
Document complet vers site de l'éditeur
 
» SesToCross: Semantic Expert System to Manage Single-Lane Road Crossing
Résumé:
This paper presents an Advanced Driver Assistance System called SesToCross, which helps those vehicle drivers who want to cross an intersection nonsignalized. SesToCross is based on a semantic expert system devoted to the intelligent management of crossroads without requiring any centralized reasoning process. SesToCross gives intelligence to each vehicle involved in the crossroad applying an ontology (CrossRoad) implemented at every single vehicle, providing a common semantic over a global and distributed architecture. SesToCross recommends, in real time, to the drivers the best choice to cross safely the intersection in an intuitive, simple, and informative, but not distractive, way. SesToCross is described, developed, and validated on real circumstances and scenarios.
Auteurs: Alberto Córdoba;José Javier Astrain;Jesús Villadangos;Leire Azpilicueta;Peio López-Iturri;Erik Aguirre;Francisco Falcone;
Apparue dans: IEEE Transactions on Intelligent Transportation Systems
Date publication: 05.-2017, volume: 18, issue:5, pages: 1221 - 1233
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Setting the Pace: Experiments With Keller's PSI
Résumé:
The ideal of self-paced learning, which was introduced nearly 50 years ago by Keller in his Personalized System of Instruction (PSI), has not yet been widely adopted. In spite of its perceived promise of helping students to learn at the speed aligned to their individual backgrounds, motivation, and skills, PSI has been challenging to implement. University teaching practice with weekly plans means that instructors expect students to learn at the same pace. Against this backdrop, this paper reports experiences from deploying PSI in multiple offerings of an introductory programming course at a Scandinavian university over five years. These include variations, such as a buddy system, rightsizing modules, encouraging pacing, alternative targets, intermediate milestones, active coaching, and time management, all primarily aimed at overcoming a key concern associated with PSI, namely, procrastination. The lessons associated with each are described with a view to providing fellow instructors with strategies and options that they can consider for implementing PSI into introductory programming courses.
Auteurs: Sandeep Purao;Maung Sein;Hallgeir Nilsen;Even Åby Larsen;
Apparue dans: IEEE Transactions on Education
Date publication: 05.-2017, volume: 60, issue:2, pages: 97 - 104
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Ship Detection From Optical Satellite Images Based on Saliency Segmentation and Structure-LBP Feature
Résumé:
Automatic ship detection from optical satellite imagery is a challenging task due to cluttered scenes and variability in ship sizes. This letter proposes a detection algorithm based on saliency segmentation and the local binary pattern (LBP) descriptor combined with ship structure. First, we present a novel saliency segmentation framework with flexible integration of multiple visual cues to extract candidate regions from different sea surfaces. Then, simple shape analysis is adopted to eliminate obviously false targets. Finally, a structure-LBP feature that characterizes the inherent topology structure of ships is applied to discriminate true ship targets. Experimental results on numerous panchromatic satellite images validate that our proposed scheme outperforms other state-of-the-art methods in terms of both detection time and detection accuracy.
Auteurs: Feng Yang;Qizhi Xu;Bo Li;
Apparue dans: IEEE Geoscience and Remote Sensing Letters
Date publication: 05.-2017, volume: 14, issue:5, pages: 602 - 606
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Should Engineers Be on Tap or on Top?
Résumé:
In preparation for writing an article for the Proceedings of the IEEE Centennial issue in May 2012, I reviewed the predictive articles from the 50th Anniversary Issue from 1962. Several articles made interesting predictions that give insight into the world of Electrical Engineering and how we think and even fantasize. Many of the predictions were amazingly accurate, while others were well off the mark, often in the same article. There are a couple of “misses” that I will use as a springboard to discuss current issues in this article and one to follow. This first Point of View reflects on the role of scientists and engineers in government and policy making.
Auteurs: H. Joel Trussell;
Apparue dans: Proceedings of the IEEE
Date publication: 05.-2017, volume: 105, issue:5, pages: 783 - 785
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Si CMOS Image-Sensors Designed With Hydrogen-Ion Implantation Induced Nanocavities for Enhancing Output Voltage Sensing Margin via Proximity Gettering
Résumé:
Si CMOS image-sensor (CIS) cells were designed by implementing proximity relaxation gettering sites of hydrogen-ion implantation-induced nanocavities (20–35 nm in diameter) underneath Si photodiode regions to enhance the sensing margin of output voltage in CIS cells. They enabled almost no degradation in the output voltage sensing margin, although ~ $ 10^{{mathsf {14}}}$ cm $^{{mathsf {-2}}}$ of Fe, Cu, Ni, and Co contaminants were introduced in the photodiode regions of CIS cells, demonstrating an excellent relaxation gettering ability. However, Si CIS cells designed with p/p++ epitaxial wafers, which are widely used, showed that the sensing margin of the CIS cells significantly decreased as the concentration of Cu and Ni contaminants in the Si photodiode regions increased, indicating no segregation gettering ability.
Auteurs: Il-Hwan Kim;Jun-Seong Park;Tae-Hun Shim;Jea-Gun Park;
Apparue dans: IEEE Transactions on Electron Devices
Date publication: 05.-2017, volume: 64, issue:5, pages: 2345 - 2349
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Signal Processing for Finance, Economics, and Marketing: Concepts, framework, and big data applications
Résumé:
Economic data and financial markets are intriguing to researchers working on data and quantitative models. With rapid growth of and increasing access to data in digital form, finance, economics, and marketing data are poised to become one of the most important and tangible big data applications, owing not only to the relatively clean organization and structure of the data but also to clear application objectives and market demands. However, data-related economic studies often have different viewpoints from signal processing (SP). Also, many fundamental economics and business problems have been well formulated and studied in both theory and practice. The knowledge of foundational finance and economic theories will help SP and data researchers avoid reinventing the wheel and develop meaningful and useful research in these areas.
Auteurs: Xiao-Ping Steven Zhang;Fang Wang;
Apparue dans: IEEE Signal Processing Magazine
Date publication: 05.-2017, volume: 34, issue:3, pages: 14 - 35
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Signal Processing for Social Good [In the Spotlight]
Résumé:
Communication, speech processing, seismology, and radar are well known applications of signal processing that contribute to the betterment of humanity. But is there a more direct way that signal and information processing can reduce poverty, hunger, inequality, injustice, ill health, and other causes of human suffering? The member states of the United Nations ratified 17 sustainable development goals in 2015, which, if achieved by the targeted year 2030, will end or greatly curtail these problems. Achieving the global goals, however, will require cooperation from all, including the signal processing community.
Auteurs: Kush R. Varshney;
Apparue dans: IEEE Signal Processing Magazine
Date publication: 05.-2017, volume: 34, issue:3, pages: 112 - 108
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Silicon-core Coaxial Through Silicon Via for Low-loss RF Si-interposer
Résumé:
In this letter, a new low-loss and low-cost through silicon via (TSV) process is presented. The proposed silicon-core coaxial via (S-COV) process is very simple and time-saving compared with a conventional TSV. In this structure, a metal-coated silicon-pole is used as a vertical interconnect instead of a fully filled metal via. The depth of the fabricated S-COV is 120 $mu text{m}$ and the minimum diameter of the signal core and dielectric gap to ground are 40 and $20~mu text{m}$ , respectively. In the well-matched condition, the measured insertion loss of the single S-COV is 0.053 dB at 10 GHz.
Auteurs: Won-Chul Lee;Byung-Wook Min;Jun Chul Kim;Jong-Min Yook;
Apparue dans: IEEE Microwave and Wireless Components Letters
Date publication: 05.-2017, volume: 27, issue:5, pages: 428 - 430
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Similarity-Based Multiple Kernel Learning Algorithms for Classification of Remotely Sensed Images
Résumé:
Multiple kernel learning (MKL) algorithms are proposed to address the problems associated with kernel selection of the kernel-based classification algorithms. Using a group of kernels rather than one single kernel, the MKL algorithms aim to provide better classification efficiency. This paper presents new similarity-based MKL algorithms to classify remote-sensing images. These algorithms find the optimal combination of kernels by maximizing the similarity between a combination of kernels and an ideal kernel. In this framework, we initially introduced three similarity measures to be used: kernel alignment, norm of kernel difference, and Hilbert–Schmidt independence criterion. Then, we proposed to solve the optimization problems of the MKL algorithm associated with each similarity measure adopting heuristic and convex optimization methods. The performances of the proposed algorithms were compared with a single kernel support vector machines as well as other MKL algorithms for classifying the features extracted from the high-resolution and hyperspectral images. The results demonstrated that the similarity-based MKL algorithms performed better than other algorithms, especially when their optimization problems were solved using the convex optimization methods or when few training samples were available. Moreover, when the optimization problems of these algorithms were solved using the heuristic optimization methods, they were able to yield acceptable performances and were faster than other MKL algorithms.
Auteurs: Saeid Niazmardi;Abdolreza Safari;Saeid Homayouni;
Apparue dans: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Date publication: 05.-2017, volume: 10, issue:5, pages: 2012 - 2021
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Simple Binary Ovonic Threshold Switching Material SiTe and Its Excellent Selector Performance for High-Density Memory Array Application
Résumé:
In this letter, simple binary Ovonic threshold switching (OTS) material with outstanding selector device performance has been demonstrated. Even with its simple material composition and easy fabrication process, the selector device with the binary OTS material showed excellent selector performance such as high-OFF resistance (> 1 G $Omega $ at 0.1 V), low-ON resistance (< 1 k $Omega $ at 2.0 V), extremely sharp switching slope (< 1 mV/dec), fast operating speed ( $text{t}_{mathrm {transition}} <2$ ns, $text{t}_{mathrm {delay}} <7$ ns), high endurance (> 108 cycles of 150 ns pulse), high electrical stability (> 1 ks at 1.2 V), and high thermal stability (> 400 °C / 30 min). Furthermore, conduction mechanism of the OTS has been explained by Poole-Frenkel-based analytical modeling.
Auteurs: Yunmo Koo;Sangmin Lee;Seonggeon Park;Minkyu Yang;Hyunsang Hwang;
Apparue dans: IEEE Electron Device Letters
Date publication: 05.-2017, volume: 38, issue:5, pages: 568 - 571
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Simple Hybrid ARQ Schemes Based on Systematic Polar Codes for IoT Applications
Résumé:
Hybrid ARQ (H-ARQ) schemes enable wireless reliability with high transmission efficiency, which is demanded for battery-operated low-complexity applications, such as Internet of Things. We propose two schemes to enable type-II H-ARQ based on systematic polar codes. We introduce code inversion for polar codes to recover the message from the redundant bits only. The first scheme we propose is an H-ARQ based on half-rate polar codes and code inversion. The second scheme develops a more general H-ARQ technique assuming an arbitrary code rate. We provide a theoretical framework for calculation of the frame error rate in polar codes with incomplete codeword elements. Simulations show that the proposed schemes can achieve a significant performance gain up to 4 dB in terms of throughput efficiency compared with the state-of-the-art H-ARQ scheme used in the high-quality-of-service mode of the IEEE 802.15.6-2012 standard for wireless body area networks.
Auteurs: Mohammad Sadegh Mohammadi;Iain B. Collings;Qi Zhang;
Apparue dans: IEEE Communications Letters
Date publication: 05.-2017, volume: 21, issue:5, pages: 975 - 978
Editeur: IEEE
Document complet vers site de l'éditeur
 
» SimRadar: A Polarimetric Radar Time-Series Simulator for Tornadic Debris Studies
Résumé:
In an effort to study and characterize scattering mechanisms of debris particles in tornadoes, a numerical polarimetric radar emulator was developed. This paper is primarily motivated by attempts to explain radar observations near tornadoes. One such observation is the regions of negative differential reflectivity, which have been found near tornadoes but they are yet to be explained physically. There are hypotheses that suggest common debris alignment and/or dominant scattering from objects with high radar-cross-section (RCS) values that cause negative ZDR, but they are extremely challenging to verify due to the inherent danger near the vicinity of tornadoes. It is, however, possible to numerically construct the scenes through representative simulations to verify the plausible causes. This serves as our primary motivation to develop the radar emulator. The novel aspects of this paper are the realistic trajectory derivation, which is based on a physical air-drag model, and the representative diversity of RCS contributions from each debris object, developed through realistic polarimetric RCS modeling and anechoic chamber measurements.
Auteurs: Boon Leng Cheong;David J. Bodine;Caleb J. Fulton;Sebastián M. Torres;Takashi Maruyama;Robert D. Palmer;
Apparue dans: IEEE Transactions on Geoscience and Remote Sensing
Date publication: 05.-2017, volume: 55, issue:5, pages: 2858 - 2870
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Simulation and Analysis of Conductively Guided Borehole Radar Wave
Résumé:
In a borehole radar (BHR) survey, a steel cable or a metallic drill pipe attached to a BHR can act as a waveguide, and often gives measured radargrams with strong, obliquely striped events. These guided BHR wave events are commonly considered as interference noise for conventional BHR surveys and have not been fully investigated. To better understand these events, a 2-D cylindrical finite-difference time-domain method is used in this paper for simulation and investigation of the guided BHR wave propagation. Snapshots of wavefields and response profiles for different configurations are simulated and analyzed to understand the generation and interaction process of the guided waves with the borehole and the surrounding formation. The simulation results confirm that if a conventional BHR is attached with a conductive waveguide, the BHR wave can be coupled with the waveguide to generate guided BHR waves propagating along the borehole. The backward-looking or forward-looking guided BHR reflections from the strata discontinuities are recorded on BHR profiles. The generation of forward-looking events makes it feasible to image ahead of a drill bit in real time while drilling using a conventional BHR. A simple formula to estimate the location of the interface using the forward-looking events is given. Based on the synthetic data with a BHR 3-7 m away from the interface, it was demonstrated that the location of the interface can be accurately predicted with an error of about 1 cm. Finally, the effect of the length of the waveguide on the guided waves is also discussed.
Auteurs: Lifeng Mao;Binzhong Zhou;
Apparue dans: IEEE Transactions on Geoscience and Remote Sensing
Date publication: 05.-2017, volume: 55, issue:5, pages: 2646 - 2657
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Simulation and Experiments of an $S$ -Band 20-kW Power-Adjustable Phase-Locked Magnetron
Résumé:
A 3-D particle-in-cell simulation model of a commercial industrial heating magnetron is developed as a guide for improving a fixed-output-power magnetron. After this improvement, the magnetron is transformed into a 20-kW power-adjustable phase-locked magnetron, which can then be injection-locked with tunable power output. For the first-time ever, the output power of the injection-locked magnetron is continuously tuned from 2 to 19 kW. This large-power magnetron is both phase and amplitude controlled, and is useful for the coherent power combining of multiple magnetrons. The magnetron frequency pushing effect, which affects the injection-locked frequency range of the phase-locked magnetron, is observed in both simulations and measurements. In the injection-locking experiments, the locking bandwidth varies from 11.7 to 2.4 MHz when the output power is tuned from 5 to 19.1 kW and the injection power is kept at 120 W. Moreover, the center frequency of the phase-locked magnetron increases with increasing output power.
Auteurs: Heping Huang;Yu Wei;Xiaojie Chen;Kama Huang;Changjun Liu;
Apparue dans: IEEE Transactions on Plasma Science
Date publication: 05.-2017, volume: 45, issue:5, pages: 791 - 797
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Simulation and SMAP Observation of Sun-Glint Over the Land Surface at the L-Band
Résumé:
We investigate the magnitude of Sun-glint through modeling the Soil Moisture Active Passive (SMAP) brightness temperature (BT). Model results show that the specular reflection of Sun-glint in the L-band can spread over a wide range of view angles due to the roughness and undulation of the land surface and therefore affect SMAP radiometer observations. Due to SMAP's low incidence angle (40°), Sun-glint in the specular direction is never observed, and only the noncoherent component of Sun-glint has influence on SMAP observations. Sun-glint is particularly an issue over wet soil surfaces at low solar zenith angles (SZAs), and caution has to be taken for the terrain effect even for high SZAs, because the local solar incident angle can be significantly changed by the terrain slope and then the specular reflection of Sun-glint can be viewed by SMAP. Model results also show that BT in V-pol is less contaminated by Sun-glint than that in H-pol. During an intense solar radio burst, it was found that the land surface BT in H-pol increased by 50 K in the forward scattering direction from the SMAP observation. This is roughly equivalent to 1 K increment by every 100 solar flux units on a dry soil and/or dense vegetation. When the solar activity is quiet in 2015, the Sun-glint from both wet land and ocean surfaces can reach up to 10 K in the SMAP L1B BT product. This paper suggests that BT observations around the solar specular direction should be masked for soil moisture retrieval at the L-band.
Auteurs: Liming He;Jing M. Chen;Kun-Shan Chen;
Apparue dans: IEEE Transactions on Geoscience and Remote Sensing
Date publication: 05.-2017, volume: 55, issue:5, pages: 2589 - 2604
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Simulation of a Channel With Another Channel
Résumé:
In this paper, we study the problem of simulating a discrete memoryless channel (DMC) from another DMC under an average-case and an exact model. We present several achievability and infeasibility results, with tight characterizations in special cases. In particular, for the exact model, we fully characterize when a binary symmetric channel can be simulated from a binary erasure channel when there is no shared randomness. We also provide infeasibility and achievability results for the simulation of a binary channel from another binary channel in the case of no shared randomness. To do this, we use the properties of Rényi capacity of a given order. We also introduce a notion of “channel diameter” which is shown to be additive and satisfy a data processing inequality.
Auteurs: Farzin Haddadpour;Mohammad Hossein Yassaee;Salman Beigi;Amin Gohari;Mohammad Reza Aref;
Apparue dans: IEEE Transactions on Information Theory
Date publication: 05.-2017, volume: 63, issue:5, pages: 2659 - 2677
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Simulations of Junction Termination Extensions in Vertical GaN Power Diodes
Résumé:
Simulations of reverse breakdown behavior of GaN power diodes with junction termination extensions (JTEs) are presented. The p-type JTE is located at the edge of the main p-n-junction, and under reverse bias, the charge in the JTE causes spreading and reduction of the peak electric fields to avoid premature avalanche breakdown. To determine the available charge in the JTE, it is shown that the electric field under reverse bias causes severe band bending within the JTE and full ionization of the Mg acceptor. Therefore, all the Mg dopants contribute charge and determine the performance of the JTE. The dependence of the breakdown voltage on the JTE’s acceptor concentration and thickness is shown. When the JTE is properly designed, the simulations show improved reverse breakdown behavior and breakdown efficiencies approaching 98% of the ideal limit for planar geometry. Finally, the challenges of creating JTEs within GaN power diodes are discussed.
Auteurs: Jonathan J. Wierer;Jeramy R. Dickerson;Andrew A. Allerman;Andrew M. Armstrong;Mary H. Crawford;Robert J. Kaplar;
Apparue dans: IEEE Transactions on Electron Devices
Date publication: 05.-2017, volume: 64, issue:5, pages: 2291 - 2297
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Simultaneous Input and State Estimation for Linear Time-Varying Continuous-Time Stochastic Systems
Résumé:
In this technical note, we consider the problem of optimal filtering for linear time-varying continuous-time stochastic systems with unknown inputs. We first show that the unknown inputs cannot be estimated without additional assumptions. Then, we discuss some conditions under which meaningful estimation is possible and propose an optimal filter that simultaneously estimates the states and unknown inputs in an unbiased minimum-variance sense. Conditions for uniform asymptotic stability, and the existence of a steady-state solution, as well as the convergence rate of the state and input estimate biases are given. Moreover, we show that a principle of separation of estimation and control holds and that the unknown inputs may be rejected. A nonlinear vehicle reentry example is given to illustrate that our filter is applicable even when some strong assumptions do not hold.
Auteurs: Sze Zheng Yong;Minghui Zhu;Emilio Frazzoli;
Apparue dans: IEEE Transactions on Automatic Control
Date publication: 05.-2017, volume: 62, issue:5, pages: 2531 - 2538
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Simultaneous Monitoring of Ballistocardiogram and Photoplethysmogram Using a Camera
Résumé:
We present a noncontact method to measure ballistocardiogram (BCG) and photoplethysmogram (PPG) simultaneously using a single camera. The method tracks the motion of facial features to determine displacement BCG, and extracts the corresponding velocity and acceleration BCGs by taking first and second temporal derivatives from the displacement BCG, respectively. The measured BCG waveforms are consistent with those reported in the literature and also with those recorded with an accelerometer-based reference method. The method also tracks PPG based on the reflected light from the same facial region, which makes it possible to track both BCG and PPG with the same optics. We verify the robustness and reproducibility of the noncontact method with a small pilot study with 23 subjects. The presented method is the first demonstration of simultaneous BCG and PPG monitoring without wearing any extra equipment or marker by the subject.
Auteurs: Dangdang Shao;Francis Tsow;Chenbin Liu;Yuting Yang;Nongjian Tao;
Apparue dans: IEEE Transactions on Biomedical Engineering
Date publication: 05.-2017, volume: 64, issue:5, pages: 1003 - 1010
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Simultaneous Spectrum Sensing and Data Reception for Cognitive Spatial Multiplexing Distributed Systems
Résumé:
A multi-user cognitive (secondary) radio system is considered, where the spatial multiplexing mode of operation is implemented amongst the nodes, under the presence of multiple primary transmissions. The secondary receiver carries out minimum mean-squared error detection to effectively decode the secondary data streams, while it performs spectrum sensing at the remaining signal to capture the presence of primary activity or not. New analytical closed-form expressions regarding some important system measures are obtained, namely, the outage and detection probabilities, the transmission power of the secondary nodes, the probability of unexpected interference at the primary nodes, and the detection efficiency with the aid of the area under the receive operating characteristics curve. The realistic scenarios of channel fading time variation and channel estimation errors are encountered for the derived results. Finally, the enclosed numerical results verify the accuracy of the proposed framework, while some useful engineering insights are also revealed, such as the key role of the detection accuracy to the overall performance and the impact of transmission power from the secondary nodes to the primary system.
Auteurs: Nikolaos I. Miridakis;Theodoros A. Tsiftsis;George C. Alexandropoulos;Mérouane Debbah;
Apparue dans: IEEE Transactions on Wireless Communications
Date publication: 05.-2017, volume: 16, issue:5, pages: 3313 - 3327
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Simultaneous Switching at Multiple Wavelengths Using Plasmon Induced Transparency and Fano Resonance
Résumé:
Plasmon-induced transparency, an effect analogous to electromagnetically induced transparency in atomic systems, is investigated theoretically in a plasmonic waveguide-coupled resonator device. Transmittance peak is induced through modulation of an external control beam, which alters the nonlinear optical response of a third-order Kerr medium incorporated within the structure. This induced transparency is utilized to achieve optical switching simultaneously at two wavelengths. At higher intensities, an induced peak exhibiting Fano resonant feature enables demonstration of simultaneous switching at three wavelengths. The performance of the switch is evaluated by determining the differential transmittance at the switching wavelengths.
Auteurs: Sushmita Paul;Mina Ray;
Apparue dans: IEEE Photonics Technology Letters
Date publication: 05.-2017, volume: 29, issue:9, pages: 739 - 742
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Single Bit Filtering Circuit Implemented in a System for the Generation of Colored Noise
Résumé:
The generation of complex signal sources is important for test and validation of electronic systems. With reference to noise sources, commercial systems usually provide white noise sources, while the scientific literature only recently proposed circuits that generate programmable colored noise. This paper proposes a filtering circuit and an algorithm to design the same that produces an arbitrary colored electrical noise. The proposed system improves the performances of the previously proposed circuits in terms of spectral characteristics of the output, in terms of logic resource occupation and power dissipation, while providing no penalty on the working frequency.
Auteurs: Ettore Napoli;Gerardo Castellano;Davide De Caro;Darjn Esposito;Nicola Petra;Antonio Giuseppe Maria Strollo;
Apparue dans: IEEE Transactions on Circuits and Systems I: Regular Papers
Date publication: 05.-2017, volume: 64, issue:5, pages: 1040 - 1050
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Single-Carrier Frequency-Domain Equalization With Hybrid Decision Feedback Equalizer for Hammerstein Channels Containing Nonlinear Transmit Amplifier
Résumé:
We propose a nonlinear hybrid decision feedback equalizer (NHDFE) for single-carrier (SC) block transmission systems with nonlinear transmit high power amplifier (HPA), which significantly outperforms our previous nonlinear SC frequency-domain equalization (NFDE) design. To obtain the coefficients of the channel impulse response (CIR) as well as to estimate the nonlinear mapping and the inverse nonlinear mapping of the HPA, we adopt a complex-valued (CV) B-spline neural network approach. Specifically, we use a CV B-spline neural network to model the nonlinear HPA, and we develop an efficient alternating least squares scheme for estimating the parameters of the Hammerstein channel, including both the CIR coefficients and the parameters of the CV B-spline model. We also adopt another CV B-spline neural network to model the inversion of the nonlinear HPA, and the parameters of this inverting B-spline model can be estimated using the least squares algorithm based on the pseudo training data obtained as a natural byproduct of the Hammerstein channel identification. The effectiveness of our NHDFE design is demonstrated in a simulation study, which shows that the NHDFE achieves a signal-to-noise ratio gain of 4dB over the NFDE at the bit error rate level of $10^{-4}$ .
Auteurs: Sheng Chen;Xia Hong;Emad F. Khalaf;Ali Morfeq;Naif D. Alotaibi;Chris J. Harris;
Apparue dans: IEEE Transactions on Wireless Communications
Date publication: 05.-2017, volume: 16, issue:5, pages: 3341 - 3354
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Single-Port Reconfigurable Magneto-Electric Dipole Antenna With Quad-Polarization Diversity
Résumé:
We propose a magneto-electric (ME) dipole antenna which is able to provide four states of polarization control, namely, the linear polarization (LP) in $x$ -direction, LP in $y$ -direction, left-hand circular polarization (CP), and right-hand CP. Under each of the two LP states, the reconfigurable ME dipole can be further tuned to work in two adjacent frequency ranges (i.e., a relatively higher band and a lower band). The uniqueness of this design arises from the fact that all the polarization and frequency agilities can be realized with a single port and without complicate feeding network, thus eliminating the insertion loss and considerably increased design complexity associated with a reconfigurable feeding network. Other advantages that make the proposed design attractive comparing with conventional reconfigurable microstrip antennas include the comparatively stable and high gain, nearly the same gain for both linear and CPs, symmetrical radiation pattern, and low back radiation level at the operating frequencies.
Auteurs: Fan Wu;Kwai Man Luk;
Apparue dans: IEEE Transactions on Antennas and Propagation
Date publication: 05.-2017, volume: 65, issue:5, pages: 2289 - 2296
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Single-Stage High Power Factor Converters Requiring Low DC-Link Capacitance to Drive Power LEDs
Résumé:
This paper proposes two nonisolated single-stage high power factor converters requiring low dc-link capacitance for power LEDs systems. Both converters result from the integration of the power factor correction and the LEDs driver stages, and require a relatively low dc-link capacitance value. A high power factor is demonstrated to be an inherent property of the proposed topologies and no input current control is necessary. The LEDs current is regulated by a symmetrical soft-switching half-bridge converter associated with a capacitive output filter. An accurate mathematical analysis valid for the two converters is detailed, yielding the elaboration of a step-by-step design procedure. In order to verify the analyses carried out, experimental results for two 90 W, 50 kHz, and 220 V converters are also presented.
Auteurs: Zito Palhano da Fonseca;Arnaldo José Perin;Eloi Agostini Junior;Claudinor Bitencourt Nascimento;
Apparue dans: IEEE Transactions on Industrial Electronics
Date publication: 05.-2017, volume: 64, issue:5, pages: 3557 - 3567
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Six Tech Trends Impacting Software Security
Résumé:
The past few years have seen radical shifts in the way software is developed, in terms of both process and the technology stack. We must actively track these changes to ensure that software security solutions remain relevant.
Auteurs: Gary McGraw;
Apparue dans: Computer
Date publication: 05.-2017, volume: 50, issue:5, pages: 100 - 102
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Slot Antenna Miniaturization Using Slit, Strip, and Loop Loading Techniques
Résumé:
The design of a miniaturized slot antenna fed by microstrip line is proposed based on loop, slit, and strip loading techniques. The antenna topologies considered are different combination of loops, slits, and strips on top and bottom of the substrate. It is found that the antenna topology with proper combination of slit and loop on top of substrate and strip on bottom of substrate provides 48.01% reduction in resonant frequency unlike only loop or slit on either end of slot antenna fed by coplanar waveguide. It is also observed that the radiation characteristics of loaded antenna are almost similar to that of unloaded antenna, with low cross polarization and −10 dB bandwidth of miniaturized antennas are also enhanced more than 60% compare to the unloaded antenna topology in all the three cases.
Auteurs: SK. Moinul Haque;Khan Masood Parvez;
Apparue dans: IEEE Transactions on Antennas and Propagation
Date publication: 05.-2017, volume: 65, issue:5, pages: 2215 - 2221
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Slowly but Surely: Smart Grids Are Just Around the Corner [Guest Editorial]
Résumé:
The articles in this special section focus on the development and applications supported by new smart grid technologies. The term smart grid means different things to different people, and quite rightly so. Our relationship with electricity varies significantly around the world. Many countries are trying to decarbonize their electricity systems; for them, a smart grid should be able to integrate large volumes of renewables. In other parts of the globe, the main concern is reducing the number of outages during common and uncommon events (such as natural disasters). For these countries, a smart grid is one that uses innovative solutions to increase reliability and also to make the grid more resilient. We also have countries that simply want to use electricity more efficiently; hence, a smart grid should help, for instance, in reducing technical and nontechnical losses. On the other side of the spectrum, we cannot forget that around a billion people in the world still do not have access to electricity. For those countries, cost-effectiveness and remoteness are major challenges, and a smart grid might be able to bring about innovative yet inexpensive community-based solutions. It is because of this diversity of contexts and objectives that different implementations of smart grid concepts have emerged in the last few years—and continue to emerge.
Auteurs: Luis Nando Ochoa;
Apparue dans: IEEE Power and Energy Magazine
Date publication: 05.-2017, volume: 15, issue:3, pages: 16 - 18
Editeur: IEEE
Document complet vers site de l'éditeur
 
» SMA: A System-Level Mutual Authentication for Protecting Electronic Hardware and Firmware
Résumé:
Due to the enhanced capability of adversaries, electronic systems are now increasingly vulnerable to counterfeiting and piracy. The majority of counterfeit systems today are of cloned type, which have been on the rise in the recent years. Ensuring the security of such systems is of great concern as an adversary can create a backdoor or insert a malware to bypass security modules. The reliability of such systems could also be questionable as the components used in these systems may be counterfeit and/or of inferior quality. It is of prime importance to develop solutions that can prevent an adversary from creating these non-authentic systems. In this paper, we present a novel system-level mutual authentication approach for both the hardware and firmware. The hardware authenticates the firmware by verifying the checksum during the power-up. On the other hand, firmware verifies the identity of the hardware and cannot produce correct results unless it receives a unique hardware fingerprint, which we call as system ID. We propose two secure protocols, TIDP and TIDS, to construct the system ID and authenticate the system by using this unique ID. We show that our approach is resistant to various known attacks.
Auteurs: Ujjwal Guin;Swarup Bhunia;Domenic Forte;Mark M. Tehranipoor;
Apparue dans: IEEE Transactions on Dependable and Secure Computing
Date publication: 05.-2017, volume: 14, issue:3, pages: 265 - 278
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Small Sample Setting and Frequency Band Selection Problem Solving Using Subband Regularized Common Spatial Pattern
Résumé:
For the last few years, motor imagery electroencephalogram (EEG)-based brain-computer interface (BCI) systems have received the significant amount of attention in various areas, including medicine and engineering. The common spatial pattern (CSP) algorithm is the most commonly used method to extract features from motor imagery EEG. However, the CSP algorithm has limited applicability in small-sample setting (SSS) situations because these rely on a covariance matrix. In addition, the large differences in performance depend on the frequency bands that are being used. To address these problems, 4–40 Hz band EEG signals are divided into nine subbands, and regularized CSP (R-CSP) is applied to individual subbands. Fisher’s linear discriminant (FLD) is applied to the features of R-CSP extracted from individual subbands, and the results obtained through the foregoing are connected for all subbands to make an FLD score vector. Furthermore, principal component analysis is applied to use the FLD score vectors as the inputs of the classifier least square support vector machine. The proposed method yielded a classification accuracy of 86.61%, 98.21%, 63.78%, 87.05%, and 77.78% from five subjects (“ $aa$ ”, “ $l$ ”, “ $av$ ”, “ $aw$ ”, and “ $ay$ ”, respectively) for BCI competition III data set IVa by using 18 c- annels in the vicinity of the motor area of the cerebral cortex. The proposed method offers particularly excellent performance in SSS situations.
Auteurs: Sang-Hoon Park;Sang-Goog Lee;
Apparue dans: IEEE Sensors Journal
Date publication: 05.-2017, volume: 17, issue:10, pages: 2977 - 2983
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Smart World [Editor's Remarks]
Résumé:
Presents the introductory editorial for this issue of the publication.
Auteurs: Hisao Ishibuchi;
Apparue dans: IEEE Computational Intelligence Magazine
Date publication: 05.-2017, volume: 12, issue:2, pages: 2 - 2
Editeur: IEEE
Document complet vers site de l'éditeur
 
» SoC Speed Binning Using Machine Learning and On-Chip Slack Sensors
Résumé:
Speed binning of system-on-chips (SoCs) using conventional $F_{mathrm {max}}$ test requires application of complex functional test patterns. Functional workload-based speed binning techniques incur high test-cost in terms of long test-time and complexity in functional test generation, and require high-end automatic test equipment. In this paper, we propose a novel speed binning flow that uses path timing slacks, extracted with robust digital embedded sensor IPs, of selected critical/near-critical paths. We apply machine learning techniques to model a predictor considering the extracted slacks and the $F_{mathrm {max}}$ values from a set of randomly tested die during wafer sort. The trained predictor is used to obtain the $F_{mathrm {max}}$ for the remaining chips. The proposed flow has been demonstrated in an SoC benchmark circuit at 28 nm technology. For sufficient number of training samples, $F_{mathrm {max}}$ is correctly predicted for 99% of the prediction samples.
Auteurs: Mehdi Sadi;Sukeshwar Kannan;LeRoy Winemberg;Mark Tehranipoor;
Apparue dans: IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems
Date publication: 05.-2017, volume: 36, issue:5, pages: 842 - 854
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Soccer Video Event Annotation by Synchronization of Attack–Defense Clips and Match Reports With Coarse-Grained Time Information
Résumé:
The annotation of significant events within soccer videos is a fundamental step in content-based soccer video retrieval. In this paper, we propose a soccer video annotation approach based on semantic matching with coarse time constraints, where video events and external text information (match reports) are synchronized using their semantic correspondence in the temporal sequence. Unlike the state-of-the-art soccer video analysis methods that assume that the time of an event’s occurrence is given precisely by the external text information, this paper considers the problem of annotating soccer videos using match reports with coarse-grained time information. The contributions of the proposed approach are: 1) we propose a more generalized approach that synchronizes video events with text descriptions using high-level semantics with coarse time constraints, rather than assuming that the timestamp is given exactly in the text description; 2) the detection of event boundaries is improved by attack–defense transition analysis (ADTA); 3) a robust and fast center circle detection algorithm is proposed for the classification of soccer field zones and ADTA; and 4) unlike conventional audio-based whistle detection, we propose a novel Hough-transform-based algorithm from the perspective of image processing. This allows the game start time to be detected, and further helps the synchronization of video and text events. The experimental results conducted on a large number of soccer videos validate the effectiveness of the proposed approach.
Auteurs: Zengkai Wang;Junqing Yu;Yunfeng He;
Apparue dans: IEEE Transactions on Circuits and Systems for Video Technology
Date publication: 05.-2017, volume: 27, issue:5, pages: 1104 - 1117
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Soft-Switching Dual-Flyback DC–DC Converter With Improved Efficiency and Reduced Output Ripple Current
Résumé:
This paper presents a soft-switching dual-flyback dc–dc converter with improved efficiency and reduced output ripple current. Zero-voltage-switching (ZVS) technique and a dual-flyback module for reducing the number of snubber current paths are adopted to improve efficiency. For the ZVS technique, a self-driven synchronous rectifier (SR) is used instead of an output diode. By turning the self-driven SR off after a short delay, a main switch is turned on under the ZVS condition. For reducing the number of snubber current paths, a dual-flyback module and a snubber diode are used. When the main switch is turned off, leakage inductance energy is absorbed by a snubber diode into an input source and a primary dc-bus capacitor. Then, this energy is reprocessed by the dual-flyback dc-dc module to secondary side. Hence, there is only one snubber current path. In addition, the proposed converter features a reduced output ripple current because of the continuous current. Consequently, the proposed converter can achieve high efficiency and reduced output ripple current. To verify the performance of the proposed converter, operating principles, steady-state analyses, and experimental results from a 340 to 24-V, 100-W prototype are presented.
Auteurs: Jae-Won Yang;Hyun-Lark Do;
Apparue dans: IEEE Transactions on Industrial Electronics
Date publication: 05.-2017, volume: 64, issue:5, pages: 3587 - 3594
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Software for Checking Style and Grammar in Scientific Writing
Résumé:
The IEEE Professional Communication Society promotes that technical and scientific communication is an essential part of engineering. Engineering students are required to write reports, research papers, theses, and dissertations. After you graduate, you will be asked to write many other types of documents.
Auteurs: Mike Unwalla;
Apparue dans: IEEE Potentials
Date publication: 05.-2017, volume: 36, issue:3, pages: 38 - 40
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Solution Processed Top-Gate High-Performance Organic Transistor Nonvolatile Memory With Separated Molecular Microdomains Floating-Gate
Résumé:
In this letter, a top-gate high-performance floating-gate organic field-effect transistor nonvolatile memory (FG-OFET-NVM), where the four-layer stacked core architecture is processed by a successive solution spin-coating method, is demonstrated. The floating-gate layer is prepared by spin-coating from a blend solution consisting of poly(styrene) (PS) and 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-Pen). As a result of phase separation, TIPS-Pen aggregates and forms many separated microdomains, which uniformly distribute in thematrix of PS as the charge-trapping sites. The optimal FG-OFET-NVM exhibits excellent memory characteristics, with a large memory window of 26 V, a desired reading voltage of 0 V, a memory ON/OFF ratio larger than 3500, programming/erasing switching endurance over 500 cycles, and good charge-storage retention with a memory ON/OFF ratio larger than 103 over 5000 s.
Auteurs: Chao Wu;Wei Wang;Junfeng Song;
Apparue dans: IEEE Electron Device Letters
Date publication: 05.-2017, volume: 38, issue:5, pages: 641 - 644
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Solving k-Set Agreement Using Failure Detectors in Unknown Dynamic Networks
Résumé:
The failure detector abstraction has been used to solve agreement problems in asynchronous systems prone to crash failures, but so far it has mostly been used in static and complete networks. This paper aims to adapt existing failure detectors in order to solve agreement problems in unknown, dynamic systems. We are specifically interested in the k-set agreement problem. The problem of k-set agreement is a generalization of consensus where processes can decide up to k different values. Although some solutions to this problem have been proposed in dynamic networks, they rely on communication synchrony or make strong assumptions on the number of process failures. In this paper we consider unknown dynamic systems modeled using the formalism of Time-Varying Graphs, and extend the definition of the existing $Pi Sigma _{x,y}$ failure detector to obtain the $Pi Sigma _{bot, x,y}$ failure detector, which is sufficient to solve k-set agreement in our model. We then provide an implementation of this new failure detector using connectivity and message pattern assumptions. Finally, we present an algorithm using $Pi Sigma _{bot, x,y}$ to solve k-set agreement.
Auteurs: Denis Jeanneau;Thibault Rieutord;Luciana Arantes;Pierre Sens;
Apparue dans: IEEE Transactions on Parallel and Distributed Systems
Date publication: 05.-2017, volume: 28, issue:5, pages: 1484 - 1499
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Some assembly (language) required - Three games that make low-level coding fun [Resources_Geek Life]
Résumé:
Ah, assembly. Where all the pretense of high-level languages—the program structures, the data handling, the wealth of functions-gets stripped away. You get branches, bytes, and if you're lucky, a subtraction command. True, directly manipulating the state of a computer can be powerful, but few people code in assembly by choice. . So I was surprised to find not one but three polished games that do a surprisingly good job of making coding in assembly language fun. To be clear, none of these titles involve writing assembly for real hardware. They all use virtual systems with minimal instruction sets. Still, they do capture the essence of assembly coding, with complex behaviors squeezed out of simple commands. . The first game is Human Resource Machine, originally released in 2015 by Tomorrow Corp. and now available for Windows, Mac, Linux, and the new Nintendo Switch. In this game the player takes on the role of an office worker who must handle numbers and letters arriving on an "in" conveyor belt and put the desired results on an "out" conveyor belt. As you begin, you're given just two instructions to work with. As you progress and face more complex challenges, more instructions are provided. Challenges range in difficulty from outputting the larger of a pair of input numbers to sorting variable-length sequences.
Auteurs: Stephen Cass;
Apparue dans: IEEE Spectrum
Date publication: 05.-2017, volume: 54, issue:5, pages: 19 - 20
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Source Transmit Antenna Selection for Space Shift Keying With Cooperative Relays
Résumé:
In this letter, we propose a cooperative multiple-input multiple-output (MIMO) scheme combining transmit antenna selection (TAS) and space shift keying (SSK). In this scheme, source transmit antennas are selected and SSK is applied by using the selected antennas. Besides the direct link transmission, the relays, that decode the source signal correctly, take part in the transmission. Exact expressions and a considerably accurate approximate expression for the symbol error rate of the proposed SSK system are derived. It is shown that the proposed scheme outperforms the SSK system without TAS and also the conventional cooperative MIMO system, which employs source TAS, at practical signal-to-noise ratio values for especially high data rates and sufficient number of receive antennas at the destination.
Auteurs: Ferhat Yarkin;Ibrahim Altunbas;Ertugrul Basar;
Apparue dans: IEEE Communications Letters
Date publication: 05.-2017, volume: 21, issue:5, pages: 1211 - 1214
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Source/Drain Asymmetry in InGaAs Vertical Nanowire MOSFETs
Résumé:
This paper demonstrates InGaAs vertical nanowire (VNW) MOSFETs fabricated via an improved top–down approach, the performance of which is comparable to that of the best bottom–up devices in terms of the balance between transport and electrostatics. These devices, when contrasted with an earlier generation fabricated by a similar technology, have enabled the first experimental study of source/drainasymmetry in InGaAs VNWMOSFETs. The transconductance differs significantly when swapping source and drain due to inherently different top and bottom contact electrical resistance. This also results in distinct asymmetry in the saturation behavior of the output characteristics. On the other hand, diameter nonuniformity along the nanowire (NW) length is responsible for asymmetry in the subthreshold characteristics. A uniform NW cross section, enabled by our improved InGaAs dry etch technology in the present devices, eliminates the asymmetry of the electrostatics, which was observed in our previous work.
Auteurs: Xin Zhao;Christopher Heidelberger;Eugene A. Fitzgerald;Jesús A. del Alamo;
Apparue dans: IEEE Transactions on Electron Devices
Date publication: 05.-2017, volume: 64, issue:5, pages: 2161 - 2165
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Space Codes for MIMO Optical Wireless Communications: Error Performance Criterion and Code Construction
Résumé:
In this paper, we consider a multiple-input-multiple-output optical wireless communication (MIMO-OWC) system in the presence of log-normal fading. In this scenario, a general criterion for the design of full-diversity space code (FDSC) with the maximum likelihood detector is developed. This criterion reveals that in a high signal-to-noise ratio regime, MIMO-OWC offers both large-scale diversity gain, governing the exponential decay of the error curve, and small-scale diversity gain, producing traditional power-law decay. Particularly for a two by two MIMO-OWC system with unipolar pulse amplitude modulation, a closed-form solution to the design problem of a linear FDSC optimizing both diversity gains is attained by taking advantage of the available properties on the successive terms of Farey sequences in number theory as well as by developing new properties on the disjoint intervals formed by the Farey sequence terms to attack the continuous and discrete variables mixed max–min design problem. In fact, this specific design not only proves that a repetition code is the optimal linear FDSC optimizing both the diversity gains but also uncovers a significant difference between MIMO radio frequency communications and MIMO-OWC that space dimension alone is sufficient for a full large-scale diversity achievement. Computer simulations demonstrate that FDSC substantially outperforms uncoded spatial multiplexing with the same total optical power and spectral efficiency, and the latter provides only the small-scale diversity gain.
Auteurs: Yan-Yu Zhang;Hong-Yi Yu;Jian-Kang Zhang;Yi-Jun Zhu;Jin-Long Wang;Tao Wang;
Apparue dans: IEEE Transactions on Wireless Communications
Date publication: 05.-2017, volume: 16, issue:5, pages: 3072 - 3085
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Space-Time Interference Alignment: DoF of Two-User MIMO X Channel With Alternating CSIT
Résumé:
In this letter, we consider the sum degrees of freedom (sum-DoFs) of the two-user multiple-input multiple-output (MIMO) X channel with alternating channel state information (CSI) at the transmitters (CSIT), which implies that the CSI available to the transmitters is distributed. Two space-time interference alignment schemes are proposed for the same channel, which possess novel ingredients, namely, interference regeneration and symbolic elimination. The new sum-DoFs achieved by these two schemes are mutually complementary over different antenna configurations. Moreover, the achieved sum-DoFs for certain antenna configurations are greater than the best known sum-DoFs in the literature with delayed CSIT.
Auteurs: Tengda Ying;Wenjiang Feng;Guoling Liu;
Apparue dans: IEEE Communications Letters
Date publication: 05.-2017, volume: 21, issue:5, pages: 1167 - 1170
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Sparse and Redundant Representation-Based Smart Meter Data Compression and Pattern Extraction
Résumé:
Smart meters play vital roles in the aspects of the management and operation of smart grids such as demand response, energy efficiency improvement, and electricity pricing. Massive amounts of data are being collected owing to the popularity of smart meters. Two main issues should be addressed in this context. One is the communication and storage of big data from smart meters at reduced cost. The other is the effective extraction of useful information from this massive dataset. In this paper, the K-SVD sparse representation technique, which includes two phases (dictionary learning and sparse coding), is used to decompose load profiles into linear combinations of several partial usage patterns (PUPs), which allows the smart meter data to be compressed and hidden electricity consumption patterns to be extracted. Then, a linear support vector machine (SVM) based method is used to classify the load profiles into two groups, residential customers and small and medium-sized enterprises (SMEs), based on the extracted patterns. Comprehensive comparisons with the results of k-means clustering, the discrete wavelet transform (DWT), principal component analysis (PCA), and piecewise aggregate approximation (PAA) are conducted on real datasets in Ireland. The results show that our proposed technique outperforms these methods in both compression ratio and classification accuracy.
Auteurs: Yi Wang;Qixin Chen;Chongqing Kang;Qing Xia;Min Luo;
Apparue dans: IEEE Transactions on Power Systems
Date publication: 05.-2017, volume: 32, issue:3, pages: 2142 - 2151
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Sparse Low-Rank Matrix Approximation for Data Compression
Résumé:
Low-rank matrix approximation (LRMA) is a powerful technique for signal processing and pattern analysis. However, its potential for data compression has not yet been fully investigated. In this paper, we propose sparse LRMA (SLRMA), an effective computational tool for data compression. SLRMA extends conventional LRMA by exploring both the intra and inter coherence of data samples simultaneously. With the aid of prescribed orthogonal transforms (e.g., discrete cosine/wavelet transform and graph transform), SLRMA decomposes a matrix into a product of two smaller matrices, where one matrix is made up of extremely sparse and orthogonal column vectors and the other consists of the transform coefficients. Technically, we formulate SLRMA as a constrained optimization problem, i.e., minimizing the approximation error in the least-squares sense regularized by the $ell _{0}$ -norm and orthogonality, and solve it using the inexact augmented Lagrangian multiplier method. Through extensive tests on real-world data, such as 2D image sets and 3D dynamic meshes, we observe that: 1) SLRMA empirically converges well; 2) SLRMA can produce approximation error comparable to LRMA but in a much sparse form; and 3) SLRMA-based compression schemes significantly outperform the state of the art in terms of rate–distortion performance.
Auteurs: Junhui Hou;Lap-Pui Chau;Nadia Magnenat-Thalmann;Ying He;
Apparue dans: IEEE Transactions on Circuits and Systems for Video Technology
Date publication: 05.-2017, volume: 27, issue:5, pages: 1043 - 1054
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Sparse Representation-Based Hyperspectral Data Processing: Lossy Compression
Résumé:
This paper presents a method for lossy hyperspecral data compression based on sparse representation. The idea is to learn a dictionary that induces sparsity in the coefficient vectors that represent new input signals. The energy compaction feature of such sparse coefficient vectors is then evaluated in a lossy hyperspectral data compression framework. Experimental results on a number of hyperspectral data show that this approach is effective in hyperspectral data compression, and comparable to some of the state-of-the-arts data compression schemes, such as JPEG2000 with multiple component transformations and three-dimensional-set partitioning in hierarchical trees. Specifically, using the proposed framework, dictionaries that exploit spectral correlation, or spectral and spatial correlations, are trained using online dictionary learning. A hyperspectral data is represented using the learned dictionary via sparse coding. The resulting sparse coefficients are then encoded to formulate the final bit stream. The proposed framework allows using a base dictionary trained offline, or incorporating an update to the base dictionary, to achieve more adaptivity.
Auteurs: Hairong Wang;Turgay Celik;
Apparue dans: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Date publication: 05.-2017, volume: 10, issue:5, pages: 2036 - 2045
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Sparse Spatio-Spectral LapSVM With Semisupervised Kernel Propagation for Hyperspectral Image Classification
Résumé:
The information contained in the hyperspectral data allows the characterization, identification, and classification of the land covers with improved accuracy and robustness. Many methods have been explored in the hyperspectral image classification (HIC). Among these methods, spatio-spectral Laplacian support vector machine (SS-LapSVM) combines the spatial and spectral information on both the labeled and unlabeled samples together through the weight sum of a spectral regularization term and a spatial regularization term. Thus, it can achieve accurate classification with very few labeled samples and has proved to be effective in HIC. In this paper, a sparse SS-LapSVM with semisupervised Kernel Propagation (S3LapSVM-KP) is constructed to achieve higher accuracy and efficiency in HIC. First, data-driven semisupervised KP is proposed to carefully learn a kernel matrix from a small number of labeled pixels. Furthermore, a one-step sparse pruning algorithm is advanced by solving sparse weight vectors associated with network nodes in SS-LapSVM. By combining semisupervised KP with sparse coding, S3LapSVM-KP can not only automatically determine kernels from data, but also avoid overfitting and reduce computation cost resulted from the nonsparse topology of SS-LapSVM. The performance of S3LapSVM-KP is evaluated on several real hyperspectral datasets, and the results show that S3LapSVM-KP can achieve accurate and rapid classification with very few labeled data.
Auteurs: Lixia Yang;Min Wang;Shuyuan Yang;Rui Zhang;Pingting Zhang;
Apparue dans: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Date publication: 05.-2017, volume: 10, issue:5, pages: 2046 - 2054
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Spatially Coherent Activation Maps for Electrocardiographic Imaging
Résumé:
Objective: Cardiac mapping is an important diagnostic step in cardiac electrophysiology. One of its purposes is to generate a map of the depolarization sequence. This map is constructed in clinical routine either by directly analyzing cardiac electrograms (EGMs) recorded invasively or an estimate of these EGMs obtained by a noninvasive technique. Activation maps based on noninvasively estimated EGMs often show artefactual jumps in activation times. To overcome this problem, we present a new method to construct the activation maps from reconstructed unipolar EGMs. Methods: On top of the standard estimation of local activation time from unipolar intrinsic deflections, we propose to mutually compare the EGMs in order to estimate the delays in activation for neighboring recording locations. We then describe a workflow to construct a spatially coherent activation map from local activation times and delay estimates in order to create more accurate maps. The method is optimized using simulated data and evaluated on clinical data from 12 different activation sequences. Results: We found that the standard methodology created lines of artificially strong activation time gradient. The proposed workflow enhanced these maps significantly. Conclusion: Estimating delays between neighbors is an interesting option for activation map computation in electrocardiographic imaging.
Auteurs: Josselin Duchateau;Mark Potse;Remi Dubois;
Apparue dans: IEEE Transactions on Biomedical Engineering
Date publication: 05.-2017, volume: 64, issue:5, pages: 1149 - 1156
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Spatially Sparse Beamforming Training for Millimeter Wave MIMO Systems
Résumé:
To realize high beamforming gain and thus sufficient link budget, millimeter wave (MMW) multiple-input multiple-output (MIMO) systems employ large antenna arrays at both the transmitter and receiver. However, due to the power and cost limitation, only a limited number of radio frequency (RF) chains are available for MMW antenna arrays. In other words, the number of RF chains is far smaller than that of antenna elements. This MMW MIMO setup poses a formidable challenge for channel estimation, which is conventionally required to realize the optimal singular value decomposition (SVD) beamforming. To circumvent the formidable channel estimation, this paper proposes two iterative antenna training schemes for the SVD beamforming in MMW MIMO systems. Relying on the channel reciprocity in time division duplex, the proposed schemes employ power iteration and Lanczos iteration, respectively, to gradually approach the SVD beamforming. During iterations, we only need to estimate several channel-related vectors instead of the MIMO channel matrix. Thanks to the spatial sparsity in MMW channels, the training overheads required by the proposed schemes are moderate. Simulations demonstrate that the proposed schemes outperform the counterpart in terms of performance and training overhead, and can achieve the performance very close to that of the perfect SVD beamforming.
Auteurs: Xiantao Cheng;Niannian Lou;Shaoqian Li;
Apparue dans: IEEE Transactions on Wireless Communications
Date publication: 05.-2017, volume: 16, issue:5, pages: 3385 - 3400
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Spatiotemporal Fuzzy Clustering Strategy for Urban Expansion Monitoring Based on Time Series of Pixel-Level Optical and SAR Images
Résumé:
Monitoring urban expansion dynamically using remote sensing technology is an essential method for obtaining and understanding urban spatial structure. However, the quality of traditional optical images in some areas is poor due to clouds and fog. Compared to optical images, synthetic aperture radar (SAR) can achieve earth observations without the limits of sunlight and weather conditions, but its speckle is too obvious. This paper combined the advantages of pixel-level optical image and SAR image time series and proposed a spatiotemporal fuzzy clustering (STFC) strategy for urban expansion monitoring. This strategy includes three parts: 1) the construction of optical-SAR image mixed time series; 2) a time-series fuzzy information granulation method to ascertain change nodes; and 3) STFC to determine the change types and range. In our study, 13 TM images and 25 SAR scenes taken from 2005 to 2011 were selected as raw data. We used the proposed method to monitor the urban expansion of Chengdu, China, and then, analyzed its main causes according to the monitoring results. The results suggested that: 1) the proposed methods could effectively extract the change nodes and change pixels, with the correctness of 85.20% and the completeness of 86.06%, outperforming the time series only (nonspatial) fuzzy clustering method, as well as traditional classification methods; and 2) the urban expansion of Chengdu is most apparent from 2005 to 2011, with the expansion direction shifting from the traditional ring structure expansion to point-axis expansion following the priority given to construction of new urban areas.
Auteurs: Shuang Li;Yafei Wang;Peipei Chen;Xinliang Xu;Chengqi Cheng;Bo Chen;
Apparue dans: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Date publication: 05.-2017, volume: 10, issue:5, pages: 1769 - 1779
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Special Issue on The 2016 IEEE International Instrumentation and Measurement Technology Conference
Résumé:
The 15 papers in this Special Issue were originally presented at the IEEE International Instrumentation and Measurement Technology Conference, held in Taipei, Taiwan on May 23-26, 2016.
Auteurs: Alessandra Flammini;Ruqiang Yan;Huang-Chen Lee;
Apparue dans: IEEE Transactions on Instrumentation and Measurement
Date publication: 05.-2017, volume: 66, issue:5, pages: 850 - 851
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Spectral Characterization of the AisaOWL
Résumé:
The AisaOWL is a recent-to-market thermal hyperspectral instrument. As such, there is little information about the sensor performance in the literature. The sensor covers the 7.6-12.6 μm part of the long-wave infrared region with 102 continuous bands, and is capable of imaging in low-light conditions. This paper presents an independent characterization of the AisaOWL sensor, examining the spectral accuracy of black body measurements at different temperatures and validating manufacturer recommendations for warm-up, integration, and calibration times. This analysis is essential for establishing high quality operational procedures and in giving confidence to users of the data. In this paper, the sensor has been found to have a maximum error of 2 °C in absolute temperature measurement, and provides spectra most accurate in the 8-9 μm region. The recommended warm-up time of 15 min has been confirmed, with a 1% increase in error identified for data collected only 7 min after switch on. The optimal integration time of 1.18 ms has been validated and an exponential decrease in performance observed outside the 0.85-1.2 ms range. The detector used by the sensor is shown to have stability issues and this has been examined by comparing black body data processed with different calibration data. While the detector is operating in a stable regime compatible with the calibration, these black body readings stay within 5% across the central bands, approaching 10% below 8 μm and just exceeding 20% above 11 μm.
Auteurs: Laura Harris;Mark Warren;Mike Grant;Gary M Llewellyn;
Apparue dans: IEEE Transactions on Geoscience and Remote Sensing
Date publication: 05.-2017, volume: 55, issue:5, pages: 2751 - 2756
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Spectral Efficiency and Relay Energy Efficiency of Full-Duplex Relay Channel
Résumé:
Full-duplex relaying has the potential to improve the spectral efficiency (SE) of cooperative communication systems. Due to residual self-interference (RSI), increase of the relay power does not always contribute to SE improvement. To fully utilize full-duplex relaying in cooperative communications, the effect of RSI on the SE achieved by different relay schemes need to be investigated. In this paper, we study bounds on the SE of full-duplex relay channel with decode-forward (DF) relaying, compress-forward (CF) relaying, and amplify-forward (AF) relaying in the presence of RSI. For respective schemes, optimal relay power and the corresponding maximal SE are derived in closed-form. Bounds on the relay energy-efficiency (REE) are presented for different schemes, which are useful for system design under per-node energy efficiency constraint. Based on the SE performance, the conditions of employing full-duplex relay, criteria for selecting relay scheme among DF, CF, and AF schemes, and the conditions of adopting hybrid full-duplex or half-duplex mode are elaborated regarding to RSI strength. In summary, this paper investigates the relationship among SE, REE, and system design by taking into account the effect of RSI for a general class of cooperation schemes.
Auteurs: Zhengchuan Chen;Tony Q. S. Quek;Ying-Chang Liang;
Apparue dans: IEEE Transactions on Wireless Communications
Date publication: 05.-2017, volume: 16, issue:5, pages: 3162 - 3175
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Spectral Ensemble Clustering via Weighted K-Means: Theoretical and Practical Evidence
Résumé:
As a promising way for heterogeneous data analytics, consensus clustering has attracted increasing attention in recent decades. Among various excellent solutions, the co-association matrix based methods form a landmark, which redefines consensus clustering as a graph partition problem. Nevertheless, the relatively high time and space complexities preclude it from wide real-life applications. We, therefore, propose Spectral Ensemble Clustering (SEC) to leverage the advantages of co-association matrix in information integration but run more efficiently. We disclose the theoretical equivalence between SEC and weighted K-means clustering, which dramatically reduces the algorithmic complexity. We also derive the latent consensus function of SEC, which to our best knowledge is the first to bridge co-association matrix based methods to the methods with explicit global objective functions. Further, we prove in theory that SEC holds the robustness, generalizability, and convergence properties. We finally extend SEC to meet the challenge arising from incomplete basic partitions, based on which a row-segmentation scheme for big data clustering is proposed. Experiments on various real-world data sets in both ensemble and multi-view clustering scenarios demonstrate the superiority of SEC to some state-of-the-art methods. In particular, SEC seems to be a promising candidate for big data clustering.
Auteurs: Hongfu Liu;Junjie Wu;Tongliang Liu;Dacheng Tao;Yun Fu;
Apparue dans: IEEE Transactions on Knowledge and Data Engineering
Date publication: 05.-2017, volume: 29, issue:5, pages: 1129 - 1143
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Spectral Quantification for High-Resolution MR Spectroscopic Imaging With Spatiospectral Constraints
Résumé:
Objective: To obtain reliable spectral estimation from magnetic resonance spectroscopic imaging (MRSI) data. Methods: The proposed method takes advantage of prior knowledge: 1) along the spectral dimension in the form of spectral bases, and 2) along the spatial dimensions in the form of spatial regularizations (e.g., smoothness or transform sparsity) and jointly estimates parameters from all the voxels. Results: Simulation and in vivo studies have been performed to demonstrate the performance of the proposed method. A Cramér–Rao-bound-based analysis is also provided. Conclusion: Incorporation of both spatial and spectral constraints can significantly improve spectral quantification of MRSI data. Significance: The proposed method is expected to be useful for various quantitative MRSI studies.
Auteurs: Qiang Ning;Chao Ma;Fan Lam;Zhi-Pei Liang;
Apparue dans: IEEE Transactions on Biomedical Engineering
Date publication: 05.-2017, volume: 64, issue:5, pages: 1178 - 1186
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Spectral–Spatial Adaptive Area-to-Point Regression Kriging for MODIS Image Downscaling
Résumé:
The moderate resolution imaging spectroradiometer (MODIS) sensor contains 36 bands at spatial resolutions of 250 m (e.g., bands 1–2), 500 m (e.g., bands 3–7), and 1000 m (e.g., bands 8–36). The first seven bands covering the visible to midinfrared wavelengths have been used widely for monitoring the Earth's surface. However, 500 m MODIS bands 3–7 present challenges for use in land cover/land use applications, as many land cover features on the Earth's surface possess complex structures with a spatial resolution finer than 500 m. Fusing MODIS 250 m bands 1–2 and 500 m bands 3–7 is an attractive proposition, that is, increasing the spatial resolution of bands 3–7. The geostatistical based downscaling approach, area-to-point regression kriging (ATPRK), has shown great potential for MODIS image downscaling. However, it considers the global relationship between bands 1–2 and each of bands 3–7 to select a 250 m PAN-like band from bands 1–2, which may not take full advantage of both bands 1 and 2. In this paper, a new geostatistical downscaling method of spectral–spatial adaptive ATPRK (SSAATPRK) is proposed for MODIS image downscaling. Both fine spatial resolution bands (i.e., bands 1 and 2) are used as the input to SSAATPRK, and there is no need to choose a PAN-like band for each coarse band, as in the original ATPRK method. SSAATPRK was compared to four benchmark image fusion methods, including principal component analysis, high-pass filtering, ATPRK, and adaptive ATPRK (AATPRK), using one synthetic MODIS image experiment and two real MODIS image experiments. Both visual and quantitative evaluations demonstrated that SSAATPRK produced results consistently with the greatest amount of spatial detail and the la- gest accuracy. Furthermore, SSAATPRK inherits completely the advantages of ATPRK and AATPRK, while extending them for MODIS image downscaling.
Auteurs: Yihang Zhang;Peter M. Atkinson;Feng Ling;Qunming Wang;Xiaodong Li;Lingfei Shi;Yun Du;
Apparue dans: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Date publication: 05.-2017, volume: 10, issue:5, pages: 1883 - 1896
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Spectrum-Energy Efficiency Optimization for Downlink LTE-A for Heterogeneous Networks
Résumé:
Heterogeneous networks have been pointed out to be one of the key network architectures that help increase system capacity and reduce power consumption for efficient communications. Although conceivably, high operational efficiency brings a high profit for mobile service providers, it is noteworthy that the potential for maximizing the profit has not been explored for the heterogeneous environment. This paper investigates profitability for network operators with the spectrum-energy efficiency metric on the downlink of LTE Advanced communication systems. We pursue optimal policies by employing the techniques of cell size zooming, user migration, and sleep mode in the deployment of different base station types. The problem is formulated as a quasiconvex optimization problem and it is transformed into an equivalent form of the MILP problem; the former is solved with a bisection algorithm and the latter is approached by an off-the-shelf software package. Since the formulated optimization problem is NP hard, a sub-optimal approach with a lower computational complexity is also proposed. Numerical analysis through case studies are presented to evaluate the efficiency improvements, and demonstrate the performance of the near-optimal solution.
Auteurs: Chan-Ching Hsu;J. Morris Chang;
Apparue dans: IEEE Transactions on Mobile Computing
Date publication: 05.-2017, volume: 16, issue:5, pages: 1449 - 1461
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Spectrum-Oriented FFBP Algorithm in Quasi-Polar Grid for SAR Imaging on Maneuvering Platform
Résumé:
In this letter, a new spectrum-oriented fast factorized backprojection (FFBP) algorithm is proposed for synthetic aperture radar (SAR) imaging on a maneuvering platform. Specifically, an analytical SAR image spectrum is derived in a novel quasi-polar coordinate system based on the FFBP, which makes it easy to incorporate with an autocalibration process for both systematic and nonsystematic errors. Different from the conventional FFBP algorithms developed in polar grid, the proposed algorithm devised in quasi-polar gird conducts the motion-induced phase error as a space-invariant component, which will definitely facilitate the phase autofocusing process during the FFBP recursions. Subsequently, a phase autofocusing process is incorporated in the resultant SAR image formation algorithm. Simulations and discussions are presented to show the focusing quality improvement made by the proposed algorithm.
Auteurs: Lei Yang;Lifan Zhao;Song Zhou;Guoan Bi;Huan Yang;
Apparue dans: IEEE Geoscience and Remote Sensing Letters
Date publication: 05.-2017, volume: 14, issue:5, pages: 724 - 728
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Spherically Punctured Reed–Muller Codes
Résumé:
Consider a binary Reed–Muller code RM $(r,m)$ defined on the $m$ -dimensional hypercube $mathbb {F}_{2}^{m}$ . In this paper, we study punctured Reed–Muller codes $P_{r}(m,b)$ , whose positions are restricted to the $m$ -tuples of a given Hamming weight $b$ . In combinatorial terms, this paper concerns $m$ -variate Boolean polynomials of any degree $r$ , which are evaluated on a Hamming sphere of some radius $b$ in $mathbb {F}_{2}^{m}$ . Codes $P_{r}(m,b)$ inherit some recursive properties of RM codes. In particular, they can be built from the shorter codes, by decomposing a spherical $b$ -layer into sub-layers of smaller dimensions. However, these sub-layers have different sizes and do not form the classical Plotkin construction. We analyze recursive properties of the spherically punctured codes $P_{r}(m,b)$ and find their distances for the arbitrary values of parameters $r,m$ , and $b$ . Finally, we describe recursive (successive cancellation) decoding of these codes.
Auteurs: Ilya Dumer;Olga Kapralova;
Apparue dans: IEEE Transactions on Information Theory
Date publication: 05.-2017, volume: 63, issue:5, pages: 2773 - 2780
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Square-Pulse Excitation Characteristics of Vitroperm
Résumé:
A pulse-charged coaxial transmission line test stand was developed to evaluate the loss and saturation characteristics of the magnetic core material Vitroperm 500Z under square-pulse excitation (SPE) conditions. The test stand was developed to generate a 100 kV square pulse that was discharged into the primary winding of a Vitroperm magnetic core load. The magnetization rates achieved ranged from 5 to $50~T/mu s$ , and saturation times ranged from 40 to 100 ns. The design of the SPE test stand is discussed, and experimental results for the Vitroperm core material are presented.
Auteurs: Nicholas D. Kallas;Randy D. Curry;Alexander B. Howard;Russell A Burdt;
Apparue dans: IEEE Transactions on Magnetics
Date publication: 05.-2017, volume: 53, issue:5, pages: 1 - 5
Editeur: IEEE
Document complet vers site de l'éditeur
 
» SSBI Mitigation and the Kramers–Kronig Scheme in Single-Sideband Direct-Detection Transmission With Receiver-Based Electronic Dispersion Compensation
Résumé:
The performance of direct-detection transceivers employing electronic dispersion compensation combined with DSP-based receiver linearization techniques is assessed through experiments on a 4 × 112 Gb/s wavelength-division multiplexing direct-detection single-sideband 16 quadratic-amplitude modulation Nyquist-subcarrier-modulation system operating at a net optical information spectral density of 2.8 b/s/Hz in transmission over standard single mode fiber links of up to 240 km. The experimental results indicate that systems with receiver-based dispersion compensation can achieve similar performance to those utilizing transmitter-based dispersion compensation, provided it is implemented together with an effective digital receiver linearization technique. The use of receiver-based compensation would simplify the operation of a fiber link since knowledge of the link dispersion is not required at the transmitter. The recently proposed Kramers–Kronig receiver scheme was found to be the best performing among the receiver linearization techniques assessed. To the best of our knowledge, this is the first experimental demonstration of the Kramers–Kronig scheme.
Auteurs: Zhe Li;M. Sezer Erkılınç;Kai Shi;Eric Sillekens;Lidia Galdino;Benn C. Thomsen;Polina Bayvel;Robert I. Killey;
Apparue dans: Journal of Lightwave Technology
Date publication: 05.-2017, volume: 35, issue:10, pages: 1887 - 1893
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Stability Analysis of Frame Slotted Aloha Protocol
Résumé:
Frame Slotted Aloha (FSA) protocol has been widely applied in Radio Frequency Identification (RFID) systems as the de facto standard in tag identification. However, very limited work has been done on the stability of FSA despite its fundamental importance both on the theoretical characterization of FSA performance and its effective operation in practical systems. In order to bridge this gap, we devote this paper to investigating the stability properties of p -persistent FSA by focusing on two physical layer models of practical importance, the models with single packet reception and multipacket reception capabilities. Technically, we model the FSA system backlog as a Markov chain with its states being backlog size at the beginning of each frame. The objective is to analyze the ergodicity of the Markov chain and demonstrate its properties in different regions, particularly the instability region. By employing drift analysis, we obtain the closed-form conditions for the stability of FSA and show that the stability region is maximized when the frame length equals the number of packets to be sent in the single packet reception model and the upper bound of stability region is maximized when the ratio of the number of packets to be sent to frame length equals in an order of magnitude the maximum multipacket reception capacity in the multipacket reception model. Furthermore, to characterize system behavior in the instability region, we mathematically demonstrate the existence of transience of the backlog Markov chain. Finally, the analytical results are validated by the numerical experiments.
Auteurs: Jihong Yu;Lin Chen;
Apparue dans: IEEE Transactions on Mobile Computing
Date publication: 05.-2017, volume: 16, issue:5, pages: 1462 - 1474
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Stability Analysis of Switched Linear Systems Defined by Regular Languages
Résumé:
In this work, we study the stability of an autonomous discrete-time linear switched system whose switching sequences are generated by a Muller automaton. This system arises in various engineering problems such as distributed communication and automotive engine control. The asymptotic stability of this system, referred to as regular asymptotic stability (RAS), generalizes two well-known definitions of stability of autonomous discrete-time linear switched systems, namely absolute asymptotic stability (AAS) and shuffle asymptotic stability (SAS). We also extend these stability definitions to robust versions. We show that absolute asymptotic stability, robust absolute asymptotic stability and robust shuffle asymptotic stability are equivalent to exponential stability. In addition, by using the Kronecker product, we prove that a robust regular asymptotic stability problem is equivalent to the conjunction of several robust absolute asymptotic stability problems.
Auteurs: Yu Wang;Nima Roohi;Geir E. Dullerud;Mahesh Viswanathan;
Apparue dans: IEEE Transactions on Automatic Control
Date publication: 05.-2017, volume: 62, issue:5, pages: 2568 - 2575
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Stability of Power Control in Multiple Coexisting Wireless Networks: An $mathscr {L}_{2}$ Small-Gain Perspective
Résumé:
Owing to the emerging techniques such as heterogeneous network and cognitive radio that allow a large number of wireless networks to intensively and flexibly use resources of radio spectrum, the network densification and dynamic spectrum access have become two important trends of wireless networking systems, so that the spectral environments will be increasingly crowded in the near future. Under such a background, this study addresses the stability related problem of the power control in multiple coexisting wireless networks. We develop an analytical framework that is capable of utilizing the small-gain theorem to show the considered power control is bounded-input bounded-output (BIBO) stable in the sense of the $ {mathscr {L}}_{2}$ gain if proper sufficient conditions are satisfied. Through modeling the power control as a feedback system and making use of the uncertainty representation, this framework can derive generalized results for the power-control algorithms that emerge in previous works. The framework developed in this study also admits the incorporation of multipath propagation that is a very common phenomenon in wireless communication systems. Within our derivation, making use of the theory for positive systems dramatically simplifies the analysis and leads to many refined results.
Auteurs: Rongrong Qian;Zhisheng Duan;Yuan Qi;
Apparue dans: IEEE Transactions on Circuits and Systems I: Regular Papers
Date publication: 05.-2017, volume: 64, issue:5, pages: 1235 - 1246
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Stabilization by Output Feedback of Multivariable Invertible Nonlinear Systems
Résumé:
In this paper, the problem of global stabilization of a rather general class of MIMO nonlinear systems is addressed. The systems considered in the paper are invertible, have a trivial zero dynamics and possess a “normal form” in which certain multipliers are functions of the state vector of a special kind. While special structural dependence of such multipliers on the components state vector has been exploited before in the context of achieving stabilization (via full-state feedback, though), the novelty in the approach of this paper is that a peculiar structure is identified which happens to be intimately related to the property of uniform complete observability (thus making the design of observers possible) and to the property of uniform invertibility, relations never established before in the literature. As a result, for this class of MIMO nonlinear systems, a dynamic output feedback law can be designed, yielding semiglobal (and even global, under appropriate assumptions) asymptotic stability.
Auteurs: Lei Wang;Alberto Isidori;Lorenzo Marconi;Hongye Su;
Apparue dans: IEEE Transactions on Automatic Control
Date publication: 05.-2017, volume: 62, issue:5, pages: 2419 - 2433
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Standardizing Ethical Design for Artificial Intelligence and Autonomous Systems
Résumé:
AI is here now, available to anyone with access to digital technology and the Internet. But its consequences for our social order aren't well understood. How can we guide the way technology impacts society?
Auteurs: Joanna Bryson;Alan Winfield;
Apparue dans: Computer
Date publication: 05.-2017, volume: 50, issue:5, pages: 116 - 119
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Static Modeling of Microgrids for Load Flow and Fault Analysis
Résumé:
Inverter interfaced distributed generators (DGs) in microgrids have different characteristics and models that are not available in the existing conventional power flow analysis tools. This paper presents a static modeling approach for inverter interfaced DGs that can be applied for time spread load flow analysis and fault analysis of microgrids, including droop-based voltage controlled DGs. The static models have been derived from the common control schemes applied to inverter interfaced DGs, including the constraints emerging from droop control and reflect steady-state behaviors of inverters accurately. In addition to simplification of analysis procedure, the static models can provide a base for the analysis of microgrids with conventional numeric analysis tools. The presented static modeling approach has been validated comparatively with the dynamic modeling results of a test microgrid.
Auteurs: Bülent Dağ;Ali Rıfat Boynueğri;Yavuz Ateş;Arif Karakaş;Abdullah Nadar;Mehmet Uzunoğlu;
Apparue dans: IEEE Transactions on Power Systems
Date publication: 05.-2017, volume: 32, issue:3, pages: 1990 - 2000
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Statistical Timing Analysis Considering Device and Interconnect Variability for BEOL Requirements in the 5-nm Node and Beyond
Résumé:
In an increasing interconnect resistance era and aggressive metal pitch scaling, the elevating RC delay could significantly shadow the improvements from advanced device architectures and become a severe design issue. This paper will holistically analyze the interplay between transistors and interconnect delay and the variability induced by back-end-of-line (BEOL) process for the 5-nm node. A global sensitivity analysis using Monte Carlo simulation is employed as a powerful tool for understanding the significance of different variation sources and propagating these process uncertainties to circuit performance and parametric yield. For the BEOL integration process, our results show that dielectric ${kappa }$ -value is the most sensitive parameter. Regarding the patterning options, the BEOL process using self-aligned quadruple pattering with positive tone process requires more than a $4times $ process margin and suffers from 50% parametric yield loss. The required guardband for litho-etch litho-etch becomes as critical as for the self-aligned double patterning process when the overlay control is $6times $ higher than the critical dimension control. For trench patterning using spacer-defined techniques, a negative tone process is required to achieve a large process window. From a design perspective, the wire length in SoC can be optimized using a disruptive architecture as a vertical FET, which could potentially reduce the average wire length by 11%.
Auteurs: Trong Huynh-Bao;Julien Ryckaert;Zsolt Tőkei;Abdelkarim Mercha;Diederik Verkest;Aaron Voon-Yew Thean;Piet Wambacq;
Apparue dans: IEEE Transactions on Very Large Scale Integration Systems
Date publication: 05.-2017, volume: 25, issue:5, pages: 1669 - 1680
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Stochastic Geometry Analysis for Mean Interference Power and Outage Probability in THz Networks
Résumé:
Mean interference power and probability of outage in the THz band (0.1–10 THz) networks are studied. The frequency band has potential for enabling future short range communication systems because of the large available spectrum resources. This can enable huge data rates, or on the other hand, large numbers of users sharing the resources. The latter case is closely related to the subject of this paper on interference modeling for dense THz networks with stochastic geometry. We use it to estimate the average behavior of random networks. The literature has shown convenient closed form solutions for the mean interference power in ultrahigh frequency band (UHF, 300 MHz – 3 GHz). Those are not always readily applicable for the THz band. This is especially the case when THz band is modeled with the molecular absorption and free space path loss. Still, the mean interference power does have closed form solutions in all cases, but in some, numerical approximations have to be used. We provide the derivation and analysis of the mean interference power and the outage probability. The results are verified with computer simulations.
Auteurs: Joonas Kokkoniemi;Janne Lehtomäki;Markku Juntti;
Apparue dans: IEEE Transactions on Wireless Communications
Date publication: 05.-2017, volume: 16, issue:5, pages: 3017 - 3028
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Stochastic Interchange Scheduling in the Real-Time Electricity Market
Résumé:
The problem of inter-regional interchange scheduling in the presence of stochastic generation and load is considered. An interchange scheduling technique based on a two-stage stochastic minimization of expected operating cost is proposed. Because directly solving the stochastic optimization is intractable, an equivalent problem that maximizes the expected social welfare is formulated. The proposed technique leverages the operator's capability of forecasting locational marginal prices and obtains the optimal interchange schedule without iterations among operators. Several extensions of the proposed technique are also discussed.
Auteurs: Yuting Ji;Tongxin Zheng;Lang Tong;
Apparue dans: IEEE Transactions on Power Systems
Date publication: 05.-2017, volume: 32, issue:3, pages: 2017 - 2027
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Stories in the Data
Résumé:
To some degree, comics have always been used to convert data into stories, from ancient Egyptian heiroglyphics to crude biology diagrams in grade-school textbooks. By their very nature, comics communicate through a variety of visualization techniques. Benjamin Bach, who along with his coauthors Nathalie Henry Riche, Sheelagh Carpendale, and Hanspeter Pfister created this issue's Art on Graphics special contribution about the emerging genre of data comics, here talks about their attempts to leverage the massive untapped potential for data-driven comics to explain multiple threads of simultaneous data.
Auteurs: Gary Singh;
Apparue dans: IEEE Computer Graphics and Applications
Date publication: 05.-2017, volume: 38, issue:3, pages: 4 - 5
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Strategic Bidding for Producers in Nodal Electricity Markets: A Convex Relaxation Approach
Résumé:
Strategic bidding problems in electricity markets are widely studied in power systems, often by formulating complex bi-level optimization problems that are hard to solve. The state-of-the-art approach to solve such problems is to reformulate them as mixed-integer linear programs (MILPs). However, the computational time of such MILP reformulations grows dramatically, once the network size increases, scheduling horizon increases, or randomness is taken into consideration. In this paper, we take a fundamentally different approach and propose effective and customized convex programming tools to solve the strategic bidding problem for producers in nodal electricity markets. Our approach is inspired by the Schmudgen's Positivstellensatz Theorem in semialgebraic geometry; but then we go through several steps based upon both convex optimization and mixed-integer programming that results in obtaining close to optimal bidding solutions, as evidenced by several numerical case studies, besides having a huge advantage on reducing computation time. While the computation time of the state-of-the-art MILP approach grows exponentially when we increase the scheduling horizon or the number of random scenarios, the computation time of our approach increases rather linearly.
Auteurs: Mahdi Ghamkhari;Ashkan Sadeghi-Mobarakeh;Hamed Mohsenian-Rad;
Apparue dans: IEEE Transactions on Power Systems
Date publication: 05.-2017, volume: 32, issue:3, pages: 2324 - 2336
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Strongly Coupled Two-LP Mode Ring Core Fiber With Low Effective Index Difference
Résumé:
We propose a strongly coupled ring core fiber for mode-division multiplexed (MDM) transmission with multiple-input multiple-output (MIMO) digital signal processing (DSP) supporting two linearly polarized (LP) modes over the C-band. We show numerically that the mode coupling efficiency of ring-core fiber can be increased by optimizing the structural parameters of the fiber based on an S-bend model. Accordingly, the coupling coefficient is successfully controlled using ring-core fiber fabricated with an effective index difference between the modes Δn eff of 0.3 × 10−3 and an effective area Aeff of 290 μm 2 for the LP01 and LP11 modes. Finally, we experimentally demonstrate the applicability of our fiber to MDM transmission with MIMO DSP, and successfully reduce the signal quality difference by employing mode coupling in a fabricated 15.4-km fiber.
Auteurs: Takayoshi Mori;Taiji Sakamoto;Masaki Wada;Azusa Urushibara;Takashi Yamamoto;Kazuhide Nakajima;
Apparue dans: Journal of Lightwave Technology
Date publication: 05.-2017, volume: 35, issue:10, pages: 1936 - 1944
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Structured Non-Uniformly Spaced Rectangular Antenna Array Design for FD-MIMO Systems
Résumé:
Full-dimensional multiple-input multiple-output (FD-MIMO) systems, whereby each base station is equipped with a uniformly spaced rectangular antenna array (URA), provides a practical means of realizing massive MIMO systems. However, the spectral efficiency of URA is considerably lower than that of its uniformly spaced linear array counterpart having the same number of antenna elements. In this paper, we first introduce a discrete angular resolution metric for quantifying the low resolution of URA in the antenna-elevation domain. This motivates us to propose a novel antenna device design, referred to as the structured non-uniformly spaced rectangular array (NURA), in which the antenna elements are non-uniformly distributed in the elevation-angle domain. Specifically, we conceive a structured NURA device for which the nonuniform distribution of the elevation-domain antenna elements is controlled by a single parameter. The design of the optimally structured NURA for the given nonlinear antenna-element-positioning function then becomes a single-parameter optimization, namely, that of maximizing the spectral efficiency of the FD-MIMO system, which can be solved efficiently. Our simulation results demonstrate that our structured NURA design significantly outperforms the standard URA in terms of achievable spectral efficiency. Our proposed structured NURA design therefore offers an effective practical framework for enhancing the achievable performance of FD-MIMO systems.
Auteurs: Wendong Liu;Zhaocheng Wang;Chen Sun;Sheng Chen;Lajos Hanzo;
Apparue dans: IEEE Transactions on Wireless Communications
Date publication: 05.-2017, volume: 16, issue:5, pages: 3252 - 3266
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Study of a Novel Bidirectional Compression Electron Gun for $W$ -Band Sheet Beam TWT
Résumé:
A novel bidirectional compression electron gun is designed for a W-band sheet beam traveling-wave tube. A parabolic curved cathode and a beam focusing electrode based on spline interpolation curves are proposed to obtain a beam with good quality. Two directional compressions are introduced to reduce the beam loading of cathode. A 30-kV, 0.97-A beam is emitted by a curved 0.112-cm2 cathode with a beam loading of 8.66 A/cm2. The beam at waist position is 1.4 mm $times0.4$ mm with a compression ratio of 2 and 10 in two directions separately. Studies of beam emittance and sensitivity of beam dynamics to mechanical errors are also carried out to understand the influence of structure parameters on electron gun performance.
Auteurs: Liusha Yang;Jianxun Wang;Hao Li;Wei Jiang;Kun Dong;Yong Luo;
Apparue dans: IEEE Transactions on Plasma Science
Date publication: 05.-2017, volume: 45, issue:5, pages: 805 - 810
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Study of Heat Transport Behavior in GaN-Based Transistors by Schottky Characteristics Method
Résumé:
The dynamic behavior of the thermal transport characteristics in the active region of AlGaN/GaN transistors was investigated experimentally. The transient temperature rise, the sectional temperature distribution, and the heat transport characteristics were all measured using the Schottky gate junction voltage characteristics method. The results show that three steps were observed in the transient temperature rise and/or Schottky gate voltage drop curves. The transient temperature rise behavior at different positions in the active region under various power conditions is discussed in detail. In addition, the heat transport delay in the active region of the AlGaN/GaN transistors is also studied. The results indicated that the transport velocity of the heat is 1.47 m/s. This is important when changes occur to the electrical characteristic parameters of the device, because any heat transport-related delay would also induce associated delays in the changes to the electrical characteristic parameters in the AlGaN/GaN transistors.
Auteurs: Yamin Zhang;Shiwei Feng;Hui Zhu;Chunsheng Guo;Yanbin Qiao;Jin Shao;Xiaodong Han;
Apparue dans: IEEE Transactions on Electron Devices
Date publication: 05.-2017, volume: 64, issue:5, pages: 2166 - 2171
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Subcategory Classifiers for Multiple-Instance Learning and Its Application to Retinal Nerve Fiber Layer Visibility Classification
Résumé:
We propose a novel multiple-instance learning (MIL) method to assess the visibility (visible/not visible) of the retinal nerve fiber layer (RNFL) in fundus camera images. Using only image-level labels, our approach learns to classify the images as well as to localize the RNFL visible regions. We transform the original feature space into a discriminative subspace, and learn a region-level classifier in that subspace. We propose a margin-based loss function to jointly learn this subspace and the region-level classifier. Experiments with an RNFL data set containing 884 images annotated by two ophthalmologists give a system-annotator agreement (kappa values) of 0.73 and 0.72, respectively, with an interannotator agreement of 0.73. Our system agrees better with the more experienced annotator. Comparative tests with three public data sets (MESSIDOR and DR for diabetic retinopathy, and UCSB for breast cancer) show that our novel MIL approach improves performance over the state of the art. Our MATLAB code is publicly available at https://github.com/ManiShiyam/Sub-category-classifiers-for-Multiple-Instance-Learning/wiki.
Auteurs: Siyamalan Manivannan;Caroline Cobb;Stephen Burgess;Emanuele Trucco;
Apparue dans: IEEE Transactions on Medical Imaging
Date publication: 05.-2017, volume: 36, issue:5, pages: 1140 - 1150
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Subcutaneous Photovoltaic Infrared Energy Harvesting for Bio-implantable Devices
Résumé:
Wireless biomedical implantable devices on the millimeter-scale enable a wide range of applications for human health, safety, and identification, though energy harvesting and power generation are still looming challenges that impede their widespread application. Energy scavenging approaches to power biomedical implants have included thermal, kinetic, radio frequency, and radiative sources. However, the achievement of efficient energy scavenging for biomedical implants at the millimeter-scale has been elusive. Here, we show that photovoltaic cells at the millimeter-scale can achieve a power conversion efficiency of more than 17% for silicon and 31% for GaAs under 1.06 $mu text{W}$ /mm2 infrared irradiation at 850 nm. Finally, these photovoltaic cells demonstrate highly efficient energy harvesting through biological tissue from ambient sunlight, or irradiation from infrared sources such as used in present-day surveillance systems, by utilizing the near infrared transparency window between the 650- and 950-nm wavelength range.
Auteurs: Eunseong Moon;David Blaauw;Jamie D. Phillips;
Apparue dans: IEEE Transactions on Electron Devices
Date publication: 05.-2017, volume: 64, issue:5, pages: 2432 - 2437
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Subpixel Mapping of Urban Areas Using EnMAP Data and Multioutput Support Vector Regression
Résumé:
Hyperspectral remote sensing data offer the opportunity to map urban characteristics in detail. Though, adequate algorithms need to cope with increasing data dimensionality, high redundancy between individual bands, and often spectrally complex urban landscapes. The study focuses on subpixel quantification of urban land cover compositions using simulated environmental mapping and analysis program (EnMAP) data acquired over the city of Berlin, utilizing both machine learning regression and classification algorithms, i.e., multioutput support vector regression (MSVR), standard support vector regression (SVR), import vector machine classifier (IVM), and support vector classifier (SVC). The experimental setup incorporates a spectral library and a reference land cover fraction map used for validation purposes. The library spectra were synthetically mixed to derive quantitative training data for the classes vegetation, impervious surface, soil, and water. MSVR and SVR models were trained directly using the synthetic mixtures. For IVM and SVC, a modified hyperparameter selection approach is conducted to improve the description of urban land cover fractions by means of probability outputs. Validation results demonstrate the high potential of the MSVR for subpixel mapping in the urban context. MSVR outperforms SVR in terms of both accuracy and computational time. IVM and SVC work similarly well, yet with lower accuracies of subpixel fraction estimates compared to both regression approaches.
Auteurs: Johannes Rosentreter;Ron Hagensieker;Akpona Okujeni;Ribana Roscher;Paul D. Wagner;Björn Waske;
Apparue dans: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Date publication: 05.-2017, volume: 10, issue:5, pages: 1938 - 1948
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Sulfur Dioxide and Nitrogen Dioxide Gas Sensor Based on Arsenene: A First-Principle Study
Résumé:
Properties of sulfur dioxide (SO2) and nitrogen dioxide (NO2) adsorbed on different types of arsenenes (pristine, boron-, and nitrogen-doped arsenene) are studied with the first-principle approach, which is based on the density functional theory. Adsorption energy, adsorption distance, Hirshfeld charge, and I–V characteristic are calculated. The results demonstrate that NO2 and SO2 exhibit a chemisorption character on boron-doped arsenene (B-arsenene) while a physisorption character on pristine and nitrogen-doped arsenene (P- and N-arsenene) with moderate adsorption energy. Moreover, analysis of density of state shows a positive change of electronic property when the two gas molecules are adsorbed on pristine/doped arsenenes. According to the I–V characteristic curves, N-arsenene can be treated as an excellent sensing material for SO2 gas sensor. Meanwhile, P-arsenene has a potential application in the NO2 gas sensor.
Auteurs: Xian-Ping Chen;Li-Ming Wang;Xiang Sun;Rui-Sheng Meng;Jing Xiao;Huai-Yu Ye;Guo-Qi Zhang;
Apparue dans: IEEE Electron Device Letters
Date publication: 05.-2017, volume: 38, issue:5, pages: 661 - 664
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Summation Inequalities to Bounded Real Lemmas of Discrete-Time Systems With Time-Varying Delay
Résumé:
Summation inequality is an important technique for analysis of discrete-time systems with a time-varying delay. It seems that from the literature a tighter inequality usually leads to a less conservative criterion. Based on $H_{infty}$ performance analysis problem, this note presents different findings on the relationship between the conservatism of bounded real lemma (BRL) and the tightness of summation inequality. Firstly, the BRL obtained by the Wirtinger-based inequality (WBI) is not always less conservative than the one by the Jensen-based inequality although the WBI is tighter. Secondly, the WBI is tighter than a general free-matrix-based inequality (GFMBI) developed in this note, while the BRL obtained via the GFMBI is less conservative than the WBI-based BRL. Finally, a numerical example is given to demonstrate those findings.
Auteurs: Chuan-Ke Zhang;Yong He;Lin Jiang;Min Wu;Hong-Bing Zeng;
Apparue dans: IEEE Transactions on Automatic Control
Date publication: 05.-2017, volume: 62, issue:5, pages: 2582 - 2588
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Super Normal Vector for Human Activity Recognition with Depth Cameras
Résumé:
The advent of cost-effectiveness and easy-operation depth cameras has facilitated a variety of visual recognition tasks including human activity recognition. This paper presents a novel framework for recognizing human activities from video sequences captured by depth cameras. We extend the surface normal to polynormal by assembling local neighboring hypersurface normals from a depth sequence to jointly characterize local motion and shape information. We then propose a general scheme of super normal vector (SNV) to aggregate the low-level polynormals into a discriminative representation, which can be viewed as a simplified version of the Fisher kernel representation. In order to globally capture the spatial layout and temporal order, an adaptive spatio-temporal pyramid is introduced to subdivide a depth video into a set of space-time cells. In the extensive experiments, the proposed approach achieves superior performance to the state-of-the-art methods on the four public benchmark datasets, i.e., MSRAction3D, MSRDailyActivity3D, MSRGesture3D, and MSRActionPairs3D.
Auteurs: Xiaodong Yang;YingLi Tian;
Apparue dans: IEEE Transactions on Pattern Analysis and Machine Intelligence
Date publication: 05.-2017, volume: 39, issue:5, pages: 1028 - 1039
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Superior NBTI in High- $k$ SiGe Transistors–Part I: Experimental
Résumé:
SiGe quantum-well pMOSFETs have recently been introduced for enhanced performance of transistors. Quite surprisingly, a significant reduction in negative bias temperature instability (NBTI) was also found in these devices. Furthermore, a stronger oxide field acceleration of the degradation in SiGe devices compared with Si devices was reported. These observations were speculated to be a consequence of the energetical realignment of the SiGe channel with respect to the dielectric stack. As these observations were made on large-area devices, only the average contribution of many defects to NBTI could be studied. In order to reveal the microscopic reasons responsible for the improved reliability, a detailed study of single defects is performed in nanoscale devices. To provide a detailed picture of single charge trapping, the step-height distributions for different device variants are measured and found to follow a unimodal and bimodal distribution. This finding suggests two conducting channels, one in the SiGe and one in the thin Si cap layer. We, furthermore, demonstrate that similar trap depth distributions are present among the device variants supported by a similar stress bias dependence of the capture times of the identified single defects. We conclude that NBTI is primarily determined by the dielectric stack and not by the device technology.
Auteurs: M. Waltl;G. Rzepa;A. Grill;W. Goes;J. Franco;B. Kaczer;L. Witters;J. Mitard;N. Horiguchi;T. Grasser;
Apparue dans: IEEE Transactions on Electron Devices
Date publication: 05.-2017, volume: 64, issue:5, pages: 2092 - 2098
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Superior NBTI in High-k SiGe Transistors–Part II: Theory
Résumé:
The susceptibility of conventional silicon p-channel MOS transistors to negative bias temperature instabilities (NBTIs) is a serious threat to further device scaling. One possible solution to this problem is the use of a SiGe quantum-well channel. The introduction of a SiGe layer, which is separated from the insulator by a thin Si cap layer, not only results in high mobilities but also superior reliability with respect to NBTI. In part one of this paper, we provide experimental evidence for reduced NBTI by thoroughly studying single traps in nanoscale devices. In this paper, we present detailed TCAD simulations and employ the four-state nonradiative multiphonon model to determine the energetical and spatial positions of the identified single traps. The found trap levels agree with the defect bands estimated in large-area devices. Our conclusions are also supported by the observation of similar activation energies for defects present in transistors of various device geometries. From the calibrated TCAD simulations data, an impressive boost of the time-to-failure for the SiGe transistor can be predicted and explained.
Auteurs: M. Waltl;G. Rzepa;A. Grill;W. Goes;J. Franco;B. Kaczer;L. Witters;J. Mitard;N. Horiguchi;T. Grasser;
Apparue dans: IEEE Transactions on Electron Devices
Date publication: 05.-2017, volume: 64, issue:5, pages: 2099 - 2105
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Superpixel-Based Difference Representation Learning for Change Detection in Multispectral Remote Sensing Images
Résumé:
With the rapid technological development of various satellite sensors, high-resolution remotely sensed imagery has been an important source of data for change detection in land cover transition. However, it is still a challenging problem to effectively exploit the available spectral information to highlight changes. In this paper, we present a novel change detection framework for high-resolution remote sensing images, which incorporates superpixel-based change feature extraction and hierarchical difference representation learning by neural networks. First, highly homogenous and compact image superpixels are generated using superpixel segmentation, which makes these image blocks adhere well to image boundaries. Second, the change features are extracted to represent the difference information using spectrum, texture, and spatial features between the corresponding superpixels. Third, motivated by the fact that deep neural network has the ability to learn from data sets that have few labeled data, we use it to learn the semantic difference between the changed and unchanged pixels. The labeled data can be selected from the bitemporal multispectral images via a preclassification map generated in advance. And then, a neural network is built to learn the difference and classify the uncertain samples into changed or unchanged ones. Finally, a robust and high-contrast change detection result can be obtained from the network. The experimental results on the real data sets demonstrate its effectiveness, feasibility, and superiority of the proposed technique.
Auteurs: Maoguo Gong;Tao Zhan;Puzhao Zhang;Qiguang Miao;
Apparue dans: IEEE Transactions on Geoscience and Remote Sensing
Date publication: 05.-2017, volume: 55, issue:5, pages: 2658 - 2673
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Superpixel-Based Multitask Learning Framework for Hyperspectral Image Classification
Résumé:
Due to the high spectral dimensionality of hyperspectral images as well as the difficult and time-consuming process of collecting sufficient labeled samples in practice, the small sample size scenario is one crucial problem and a challenging issue for hyperspectral image classification. Fortunately, the structure information of materials, reflecting region of homogeneity in the spatial domain, offers an invaluable complement to the spectral information. Assuming some spatial regularity and locality of surface materials, it is reasonable to segment the image into different homogeneous parts in advance, called superpixel, which can be used to improve the classification performance. In this paper, a superpixel-based multitask learning framework has been proposed for hyperspectral image classification. Specifically, a set of 2-D Gabor filters are first applied to hyperspectral images to extract discriminative features. Meanwhile, a superpixel map is generated from the hyperspectral images. Second, a superpixel-based spatial-spectral Schroedinger eigenmaps (S4E) method is adopted to effectively reduce the dimensions of each extracted Gabor cube. Finally, the classification is carried out by a support vector machine (SVM)-based multitask learning framework. The proposed approach is thus termed Gabor S4E and SVM-based multitask learning (GS4E-MTLSVM). A series of experiments is conducted on three real hyperspectral image data sets to demonstrate the effectiveness of the proposed GS4E-MTLSVM approach. The experimental results show that the performance of the proposed GS4E-MTLSVM is better than those of several state-of-the-art methods, while the computational complexity has been greatly reduced, compared with the pixel-based spatial-spectral Schroedinger eigenmaps method.
Auteurs: Sen Jia;Bin Deng;Jiasong Zhu;Xiuping Jia;Qingquan Li;
Apparue dans: IEEE Transactions on Geoscience and Remote Sensing
Date publication: 05.-2017, volume: 55, issue:5, pages: 2575 - 2588
Editeur: IEEE
Document complet vers site de l'éditeur
 
» Supervisor Synthesis for Mealy Automata With Output Functions: A Model Transformation Approach
Résumé:
Recently, Ushio and Takai have proposed a Mealy-automata-based framework to study the non-blocking supervisory control problem under partial observation. This framework can handle observation uncertainties by taking both state-dependent observations and nondeterministic outputs into account. In this technical note, we propose a model-transformation-based approach to solve the supervisor synthesis problem in this framework. First, we propose a transformation algorithm that transforms the non-blocking supervisor synthesis problem for Mealy automata to a conventional supervisory synthesis problem under partial observation, which can be solved effectively by an existing algorithm. Then we show that the supervisor synthesized for the transformed problem indeed solves the original problem. Our results bridge the gap between the conventional supervisory control framework under partial observation and the recently proposed Mealy automata framework where nondeterministic output function is used.
Auteurs: Xiang Yin;
Apparue dans: IEEE Transactions on Automatic Control
Date publication: 05.-2017, volume: 62, issue:5, pages: 2576 - 2581
Editeur: IEEE
Document complet vers site de l'éditeur
 


Publication archives by date
    2017:   janvier     février     mars     avril     mai     juin     juillet     août     septembre     octobre     novembre     décembre    
    2016:   janvier     février     mars     avril     mai     juin     juillet     août     septembre     octobre     novembre     décembre    
    2015:   janvier     février     mars     avril     mai     juin     juillet     août     septembre     octobre     novembre     décembre    
    2014:   janvier     février     mars     avril     mai     juin     juillet     août     septembre     octobre     novembre     décembre    
    2013:   janvier     février     mars     avril     mai     juin     juillet     août     septembre     octobre     novembre     décembre    
    2012:   janvier     février     mars     avril     mai     juin     juillet     août     septembre     octobre     novembre     décembre    
    2011:   janvier     février     mars     avril     mai     juin     juillet     août     septembre     octobre     novembre     décembre    
    2010:   janvier     février     mars     avril     mai     juin     juillet     août     septembre     octobre     novembre     décembre    
    2009:   janvier     février     mars     avril     mai     juin     juillet     août     septembre     octobre     novembre     décembre