Electrical and Electronics Engineering publications abstract of: 07-2017 sorted by title, page: 5

» Deep Learning Segmentation of Optical Microscopy Images Improves 3-D Neuron Reconstruction
Abstract:
Digital reconstruction, or tracing, of 3-D neuron structure from microscopy images is a critical step toward reversing engineering the wiring and anatomy of a brain. Despite a number of prior attempts, this task remains very challenging, especially when images are contaminated by noises or have discontinued segments of neurite patterns. An approach for addressing such problems is to identify the locations of neuronal voxels using image segmentation methods, prior to applying tracing or reconstruction techniques. This preprocessing step is expected to remove noises in the data, thereby leading to improved reconstruction results. In this paper, we proposed to use 3-D convolutional neural networks (CNNs) for segmenting the neuronal microscopy images. Specifically, we designed a novel CNN architecture, that takes volumetric images as the inputs and their voxel-wise segmentation maps as the outputs. The developed architecture allows us to train and predict using large microscopy images in an end-to-end manner. We evaluated the performance of our model on a variety of challenging 3-D microscopy images from different organisms. Results showed that the proposed methods improved the tracing performance significantly when combined with different reconstruction algorithms.
Autors: Rongjian Li;Tao Zeng;Hanchuan Peng;Shuiwang Ji;
Appeared in: IEEE Transactions on Medical Imaging
Publication date: Jul 2017, volume: 36, issue:7, pages: 1533 - 1541
Publisher: IEEE
 
» Deep Recurrent Neural Networks for Hyperspectral Image Classification
Abstract:
In recent years, vector-based machine learning algorithms, such as random forests, support vector machines, and 1-D convolutional neural networks, have shown promising results in hyperspectral image classification. Such methodologies, nevertheless, can lead to information loss in representing hyperspectral pixels, which intrinsically have a sequence-based data structure. A recurrent neural network (RNN), an important branch of the deep learning family, is mainly designed to handle sequential data. Can sequence-based RNN be an effective method of hyperspectral image classification? In this paper, we propose a novel RNN model that can effectively analyze hyperspectral pixels as sequential data and then determine information categories via network reasoning. As far as we know, this is the first time that an RNN framework has been proposed for hyperspectral image classification. Specifically, our RNN makes use of a newly proposed activation function, parametric rectified tanh (PRetanh), for hyperspectral sequential data analysis instead of the popular tanh or rectified linear unit. The proposed activation function makes it possible to use fairly high learning rates without the risk of divergence during the training procedure. Moreover, a modified gated recurrent unit, which uses PRetanh for hidden representation, is adopted to construct the recurrent layer in our network to efficiently process hyperspectral data and reduce the total number of parameters. Experimental results on three airborne hyperspectral images suggest competitive performance in the proposed mode. In addition, the proposed network architecture opens a new window for future research, showcasing the huge potential of deep recurrent networks for hyperspectral data analysis.
Autors: Lichao Mou;Pedram Ghamisi;Xiao Xiang Zhu;
Appeared in: IEEE Transactions on Geoscience and Remote Sensing
Publication date: Jul 2017, volume: 55, issue:7, pages: 3639 - 3655
Publisher: IEEE
 
» DeepID-Net: Object Detection with Deformable Part Based Convolutional Neural Networks
Abstract:
In this paper, we propose deformable deep convolutional neural networks for generic object detection. This new deep learning object detection framework has innovations in multiple aspects. In the proposed new deep architecture, a new deformation constrained pooling (def-pooling) layer models the deformation of object parts with geometric constraint and penalty. A new pre-training strategy is proposed to learn feature representations more suitable for the object detection task and with good generalization capability. By changing the net structures, training strategies, adding and removing some key components in the detection pipeline, a set of models with large diversity are obtained, which significantly improves the effectiveness of model averaging. The proposed approach improves the mean averaged precision obtained by RCNN [1] , which was the state-of-the-art, from to percent on the ILSVRC2014 detection test set. It also outperforms the winner of ILSVRC2014, GoogLeNet, by 6.1 percent. Detailed component-wise analysis is also provided through extensive experimental evaluation, which provides a global view for people to understand the deep learning object detection pipeline.
Autors: Wanli Ouyang;Xingyu Zeng;Xiaogang Wang;Shi Qiu;Ping Luo;Yonglong Tian;Hongsheng Li;Shuo Yang;Zhe Wang;Hongyang Li;Kun Wang;Junjie Yan;Chen-Change Loy;Xiaoou Tang;
Appeared in: IEEE Transactions on Pattern Analysis and Machine Intelligence
Publication date: Jul 2017, volume: 39, issue:7, pages: 1320 - 1334
Publisher: IEEE
 
» DeepShape: Deep-Learned Shape Descriptor for 3D Shape Retrieval
Abstract:
Complex geometric variations of 3D models usually pose great challenges in 3D shape matching and retrieval. In this paper, we propose a novel 3D shape feature learning method to extract high-level shape features that are insensitive to geometric deformations of shapes. Our method uses a discriminative deep auto-encoder to learn deformation-invariant shape features. First, a multiscale shape distribution is computed and used as input to the auto-encoder. We then impose the Fisher discrimination criterion on the neurons in the hidden layer to develop a deep discriminative auto-encoder. Finally, the outputs from the hidden layers of the discriminative auto-encoders at different scales are concatenated to form the shape descriptor. The proposed method is evaluated on four benchmark datasets that contain 3D models with large geometric variations: McGill, SHREC'10 ShapeGoogle, SHREC'14 Human and SHREC'14 Large Scale Comprehensive Retrieval Track Benchmark datasets. Experimental results on the benchmark datasets demonstrate the effectiveness of the proposed method for 3D shape retrieval.
Autors: Jin Xie;Guoxian Dai;Fan Zhu;Edward K. Wong;Yi Fang;
Appeared in: IEEE Transactions on Pattern Analysis and Machine Intelligence
Publication date: Jul 2017, volume: 39, issue:7, pages: 1335 - 1345
Publisher: IEEE
 
» Degradation Prediction of PEM Fuel Cell Stack Based on Multiphysical Aging Model With Particle Filter Approach
Abstract:
In this paper, a novel degradation prediction model for proton-exchange-membrane fuel cell (PEMFC) performance is proposed based on a multiphysical aging model with particle filter (PF) and extrapolation approach. The proposed multiphysical aging model considers major internal physical aging phenomena of fuel cells, including fuel cell ohmic losses, reaction activity losses, and reactants mass transfer losses. Furthermore, in order to obtain accurate values of electrochemical activation losses under a variable load profile, a bisection solver is presented to solve the implicit Butler–Volmer equation. The proposed aging model is initialized at first by fitting the PEMFC polarization curve at the beginning of lifetime. During the prediction process, the aging dataset is then divided into two parts, learning and prediction phases. The PF framework is used to study the degradation characteristics and update the aging parameters during the learning phase. The suitable fitting curve functions are then selected to satisfy the degradation trends of trained aging parameters, and used to further extrapolate the future values of aging parameters in the prediction phase. By using these extrapolated aging parameters, the prediction results are thus obtained from the proposed aging model. Three experimental validations with different aging testing profiles have been performed. The results demonstrate the robustness and advantages of the proposed prediction method.
Autors: Daming Zhou;Yiming Wu;Fei Gao;Elena Breaz;Alexandre Ravey;Abdellatif Miraoui;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Jul 2017, volume: 53, issue:4, pages: 4041 - 4052
Publisher: IEEE
 
» Delay Analysis and Routing for Two-Dimensional VANETs Using Carry-and-Forward Mechanism
Abstract:
For disconnected Vehicular Ad hoc NETworks (VANETs), the carry-and-forward mechanism is promising to ensure the delivery success ratio at the cost of a longer delay, as the vehicle travel speed is much lower than the wireless signal propagation speed. Estimating delay is critical to select the paths with low delay, and is also challenging given the random topology and high mobility, and the difficulty to let the message propagate along the selected path. In this paper, we first propose a simple yet effective propagation strategy considering bidirectional vehicle traffic for two-dimensional VANETs, so the opposite-direction vehicles can be used to accelerate the message propagation and the message can largely follow the selected path. Focusing on the propagation delay, an analytical framework is developed to quantify the expected path delay. Using the analytical model, a source node can apply the shortest-path algorithm to select the path with the lowest expected delay. Performance evaluation by simulation show that, when the vehicle density is uneven but known, the proposed Minimum Delay Routing Algorithm can achieve a substantial reduction in delay compared with the geocast-routing approach, and its performance is close to the flooding-based Epidemic algorithm, while our solution maintains only a single copy of the message.
Autors: Jianping He;Lin Cai;Jianping Pan;Peng Cheng;
Appeared in: IEEE Transactions on Mobile Computing
Publication date: Jul 2017, volume: 16, issue:7, pages: 1830 - 1841
Publisher: IEEE
 
» Delay-Aware Uplink Fronthaul Allocation in Cloud Radio Access Networks
Abstract:
In cloud radio access networks (C-RANs), the baseband units and radio units of base stations are separated, which requires high-capacity fronthaul links connecting both parts. In this paper, we consider the delay-aware fronthaul allocation problem for C-RANs. The stochastic optimization problem is formulated as an infinite horizon average cost Markov decision process. To deal with the curse of dimensionality, we derive a closed-form approximate priority function and the associated error bound using perturbation analysis. Based on the closed-form approximate priority function, we propose a low-complexity delay-aware fronthaul allocation algorithm solving the per-stage optimization problem. The proposed solution is further shown to be asymptotically optimal for sufficiently small residual interference. Finally, the proposed fronthaul allocation algorithm is compared with various baselines through simulations, and it is shown that significant performance gain can be achieved.
Autors: Wei Wang;Vincent K. N. Lau;Mugen Peng;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Jul 2017, volume: 16, issue:7, pages: 4275 - 4287
Publisher: IEEE
 
» Delay-Optimal Buffer-Aware Scheduling With Adaptive Transmission
Abstract:
In this paper, we aim to obtain the optimal tradeoff between the average delay and the average power consumption in a communication system. In our system, the arrivals occur at each timeslot according to a Bernoulli arrival process, and are buffered at the transmitter waiting to be scheduled. We consider a finite buffer and allow the scheduling decision to depend on the buffer occupancy. In order to capture the realism in communication systems, the transmission power is assumed to be an increasing and convex function of the number of packets transmitted in each timeslot. This problem is modeled as a constrained Markov decision process (CMDP). We first prove that the optimal policy of the Lagrangian relaxation of the CMDP is deterministic and threshold-based. We then show that the optimal delay-power tradeoff curve is convex and piecewise linear, and the optimal policies of the original problem are also threshold-based. Based on the results, we propose an algorithm to obtain the optimal policy and the optimal tradeoff curve. We also show that the proposed algorithm is much more efficient than using general methods. The theoretical results and the algorithm are validated by linear programming and simulations.
Autors: Xiang Chen;Wei Chen;Joohyun Lee;Ness B. Shroff;
Appeared in: IEEE Transactions on Communications
Publication date: Jul 2017, volume: 65, issue:7, pages: 2917 - 2930
Publisher: IEEE
 
» Delta Power Control Strategy for Multistring Grid-Connected PV Inverters
Abstract:
With a still increasing penetration level of grid-connected photovoltaic (PV) systems, more advanced active power control functionalities have been introduced in certain grid regulations. A delta power constraint, where a portion of the active power from the PV panels is reserved during operation, is required for grid support (e.g., during frequency deviation). In this paper, a cost-effective solution to realize delta power control (DPC) for grid-connected PV systems is presented, where the multistring PV inverter configuration is adopted. This control strategy is a combination of maximum power point tracking (MPPT) and constant power generation (CPG) modes. In this control scheme, one PV string operating in the MPPT mode estimates the available power, whereas the other PV strings regulate the total PV power by the CPG control strategy in such a way that the delta power constraint for the entire PV system is achieved. Simulations and experiments have been performed on a 3-kW single-phase grid-connected PV system. The results have confirmed the effectiveness of the proposed DPC strategy, where the power reserve according to the delta power constraint is achieved under several operating conditions.
Autors: Ariya Sangwongwanich;Yongheng Yang;Frede Blaabjerg;Dezso Sera;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Jul 2017, volume: 53, issue:4, pages: 3862 - 3870
Publisher: IEEE
 
» Delta–Sigma Encoder for Low-Power Wireless Bio-Sensors Using Ultrawideband Impulse Radio
Abstract:
This brief presents a systematic method to reduce the power consumption of a wireless sensor node for sensing biomedical signals. The design combines the delta–sigma modulator (DSM), the ultrawideband impulse radio (UWB-IR), and the proposed xnor-delay-based encoder/decoder, which replaces the decimation filter. The encoder and decoder for both the first- and second-order DSMs are presented. The clock synchronization problem is solved by using an asynchronous UWB-IR. The effects of window length, the order of delta–sigma modulation, and the oversampling ratio are studied by simulation using neural and electrocardiography signals. Based on the simulation results, the proposed method can save power by 50% compared to the system with decimation filters, and 53% compared to the system without the proposed encoder.
Autors: Xiaochen Tang;Qisong Hu;Wei Tang;
Appeared in: IEEE Transactions on Circuits and Systems II: Express Briefs
Publication date: Jul 2017, volume: 64, issue:7, pages: 747 - 751
Publisher: IEEE
 
» Demand-Side Resiliency and Electricity Continuity: Experiences and Lessons Learned in Japan
Abstract:
In March 2011, Japan suffered devastating damage from the Great East Japan Earthquake (GEJE) and accompanying tsunami, which caused massive blackouts affecting 8.5 million customers. Damage to power stations, including Fukushima Daiichi Nuclear Power Station, caused a long-term, nationwide power shortage. Other infrastructure and customer facilities were damaged as well. Demand-side resiliency means the availability of electricity to consumers, which is an important factor that affects business continuity. Onsite generation and microgrids have been recognized as important measures that improve resiliency; successful real-life applications of these technologies, such as the Sendai Microgrid and Roppongi Hills, have increased after the GEJE. Metrics on the importance of loads or facilities and resiliency are needed to encourage investment by supporting business operators' decision making and enabling quantitative analyses of the tradeoff between cost and resiliency improvement. This paper presents a comprehensive outline of experiences and lessons learned from the GEJE from the viewpoint of demand-side resiliency—or the availability of electricity to consumers. Damage to power systems and power supply capability through power source loss, best practices (including microgrids), and post-disaster responses and lessons learned are all examined.
Autors: Hirohisa Aki;
Appeared in: Proceedings of the IEEE
Publication date: Jul 2017, volume: 105, issue:7, pages: 1443 - 1455
Publisher: IEEE
 
» Demonstration of Polarization-Independent Surface Plasmon Resonance Polymer Waveguide for Refractive Index Sensing
Abstract:
The effect of the variation of the refractive index in a gold-coated ormocomp waveguide for sensing application is studied in this paper. The ormocomp waveguide is fabricated by using the nanoimprint method. A waveguide with width and height both equal to 10 μm is coated with 100 nm thick gold using the sputtering technique in order to introduce surface plasmon resonance at the vertical sides and also at the top of the structure. Here, polarization-independent waveguide is achieved by supporting both the plasmonic TE and TM modes and the light confinement in these modes are studied. Supermodes forming from coupling between the fundamental dielectric mode and the plasmonic supermode at the resonance peak are also investigated. This paper presents the numerical simulated results and also their experimental validations. For this structure, there are two dielectric-plasmon supermodes with two resonance peaks separated by 50 nm. A red shift is observed when the refractive index of the cladding material increases. The cladding material includes water (n = 1.333) and iso-propanol solutions with refractive indices of 1.344, 1.351, and 1.365. The gold-coated ormocomp waveguide has sensitivity of about 544.55 nm/RIU with a resolution of 5.3 × 10−3 RIU.
Autors: Charusluk Viphavakit;Wisarn Patchoo;Sakoolkan Boonruang;Christos Themistos;Michael Komodromos;Waleed S. Mohammed;B. M. Azizur Rahman;
Appeared in: Journal of Lightwave Technology
Publication date: Jul 2017, volume: 35, issue:14, pages: 3012 - 3019
Publisher: IEEE
 
» Demystifying Compressive Sensing [Lecture Notes]
Abstract:
The conventional Nyquist-Shannon sampling theorem has been fundamental to the acquisition of signals for decades, relating a uniform sampling rate to the bandwidth of a signal. However, many signals can be compressed after sampling, implying a high level of redundancy. The theory of compressive sensing/sampling (CS) presents a sampling framework based on the rate of information of a signal and not the bandwidth, thereby minimizing redundancy during sampling. This means that a signal can be recovered from far fewer samples than conventionally required.
Autors: Heinrich Edgar Arnold Laue;
Appeared in: IEEE Signal Processing Magazine
Publication date: Jul 2017, volume: 34, issue:4, pages: 171 - 176
Publisher: IEEE
 
» Denoising of Hyperspectral Image Using Low-Rank Matrix Factorization
Abstract:
Restoration of hyperspectral images (HSIs) is a challenging task, owing to the reason that images are inevitably contaminated by a mixture of noise, including Gaussian noise, impulse noise, dead lines, and stripes, during their acquisition process. Recently, HSI denoising approaches based on low-rank matrix approximation have become an active research field in remote sensing and have achieved state-of-the-art performance. These approaches, however, unavoidably require to calculate full or partial singular value decomposition of large matrices, leading to the relatively high computational cost and limiting their flexibility. To address this issue, this letter proposes a method exploiting a low-rank matrix factorization scheme, in which the associated robust principal component analysis is solved by the matrix factorization of the low-rank component. Our method needs only an upper bound of the rank of the underlying low-rank matrix rather than the precise value. The experimental results on the simulated and real data sets demonstrate the performance of our method by removing the mixed noise and recovering the severely contaminated images.
Autors: Fei Xu;Yongyong Chen;Chong Peng;Yongli Wang;Xuefeng Liu;Guoping He;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Jul 2017, volume: 14, issue:7, pages: 1141 - 1145
Publisher: IEEE
 
» Density Evolution for Deterministic Generalized Product Codes on the Binary Erasure Channel at High Rates
Abstract:
Generalized product codes (GPCs) are extensions of product codes (PCs), where code symbols are protected by two component codes but not necessarily arranged in a rectangular array. We consider a deterministic construction of GPCs (as opposed to randomized code ensembles) and analyze the asymptotic performance over the binary erasure channel under iterative decoding. Our code construction encompasses several classes of GPCs previously proposed in the literature, such as irregular PCs, blockwise braided codes, and staircase codes. It is assumed that the component codes can correct a fixed number of erasures and that the length of each component code tends to infinity. We show that this setup is equivalent to studying the behavior of a peeling algorithm applied to a sparse inhomogeneous random graph. Using a convergence result for these graphs, we derive the density evolution equations that characterize the asymptotic decoding performance. As an application, we discuss the design of irregular GPCs, employing a mixture of component codes with different erasure-correcting capabilities.
Autors: Christian Häger;Henry D. Pfister;Alexandre Graell i Amat;Fredrik Brännström;
Appeared in: IEEE Transactions on Information Theory
Publication date: Jul 2017, volume: 63, issue:7, pages: 4357 - 4378
Publisher: IEEE
 
» Dependable Structural Health Monitoring Using Wireless Sensor Networks
Abstract:
As an alternative to current wired-based networks, wireless sensor networks (WSNs) are becoming an increasingly compelling platform for engineering structural health monitoring (SHM) due to relatively low-cost, easy installation, and so forth. However, there is still an unaddressed challenge: the application-specific dependability in terms of sensor fault detection and tolerance. The dependability is also affected by a reduction on the quality of monitoring when mitigating WSN constrains (e.g., limited energy, narrow bandwidth). We address these by designing a dependable distributed WSN framework for SHM (called DependSHM) and then examining its ability to cope with sensor faults and constraints. We find evidence that faulty sensors can corrupt results of a health event (e.g., damage) in a structural system without being detected. More specifically, we bring attention to an undiscovered yet interesting fact, i.e., the real measured signals introduced by one or more faulty sensors may cause an undamaged location to be identified as damaged (false positive) or a damaged location as undamaged (false negative) diagnosis. This can be caused by faults in sensor bonding, precision degradation, amplification gain, bias, drift, noise, and so forth. In DependSHM, we present a distributed automated algorithm to detect such types of faults, and we offer an online signal reconstruction algorithm to recover from the wrong diagnosis. Through comprehensive simulations and a WSN prototype system implementation, we evaluate the effectiveness of DependSHM.
Autors: Md Zakirul Alam Bhuiyan;Guojun Wang;Jie Wu;Jiannong Cao;Xuefeng Liu;Tian Wang;
Appeared in: IEEE Transactions on Dependable and Secure Computing
Publication date: Jul 2017, volume: 14, issue:4, pages: 363 - 376
Publisher: IEEE
 
» Dependence of the Bremsstrahlung Spectral Temperature in Minimum-B Electron Cyclotron Resonance Ion Sources
Abstract:
The spectral temperature obtained from bremsstrahlung spectra emitted from electron cyclotron resonance (ECR) ion sources (ECRISs), in which the plasma is confined in a minimum-B magnetic field, is used as a relative indication of the temperature of the plasma hot electrons. Past bremsstrahlung measurements taken on ECRISs indicate that is strongly dependent on the magnetic field gradient at the resonance zone or . However, this dependence was never fully proven or explained. To further our understanding a more detailed study of the bremsstrahlung radiation for X-rays above 10 keV is underway using VENUS, a third-generation ECRIS at Lawrence Berkeley National Laboratory. Initial analysis of previous and new data has revealed that appears to be dependent solely on the minimum magnetic field rather than and the microwave frequency . Decoupling from , mainly , implies that does not depend on the magnitude of the heating frequency . While it certainly appears to be true that plasma density increases with heating frequency, as was postulated by Geller in 1987, a more careful consideration into the heating mechanism of the plasma electrons is warranted. The disassociation of from the heating frequency , while an interesting discovery, implies that we must change the way we understand how ECRISs operate. This paper presents new bremsstrahlung measurements, analyses, and discussions of the results.
Autors: J. Benitez;C. Lyneis;L. Phair;D. Todd;D. Xie;
Appeared in: IEEE Transactions on Plasma Science
Publication date: Jul 2017, volume: 45, issue:7, pages: 1746 - 1754
Publisher: IEEE
 
» Dependency Analysis and Improved Parameter Estimation for Dynamic Composite Load Modeling
Abstract:
Dynamic load modeling by fitting the input–output measurements during fault events is crucial for power system dynamic studies. The WECC composite load model (CMPLDW) has been developed recently to better represent fault-induced delayed-voltage-recovery (FIDVR) events, which are of increasing concern to electric utilities. However, the model nonlinearity and large number of parameters of the CMPLDW model pose severe identifiability issues and performance degradation for the measurement-based load modeling approach using the classical nonlinear least-squares (NLS) objective. This paper will first present a general framework that can effectively analyze and visualize the parameter dependence of complex dynamic load models with large numbers of parameters under FIDVR. Furthermore, we propose to improve the parameter estimation performance by regularizing the NLS error objective using a priori information about parameter values. Effectiveness of the proposed dependence analysis and parameter estimation scheme is validated using both synthetic and real measurement data during faults. Albeit focused on CMPLDW, the proposed approaches can be readily used for composite load modeling in general.
Autors: Kaiqing Zhang;Hao Zhu;Siming Guo;
Appeared in: IEEE Transactions on Power Systems
Publication date: Jul 2017, volume: 32, issue:4, pages: 3287 - 3297
Publisher: IEEE
 
» Depth Recovery for Kinect Sensor Using Contour-Guided Adaptive Morphology Filter
Abstract:
Consumer-grade RGB-D cameras, such as Kinect sensors, can provide support for much more real-time tasks of 3-D vision than game controllers. However, the inherent depth degradations caused by their infrared ranging will constrain their application potential, but can hardly be avoided through the improvement of the sensor design. Therefore, in this paper, we proposed a contours-guided shape-adaptive morphology filter to efficiently recover the depth of Kinect sensors. First, we put forward a statistical concept to quantitatively evaluate the texture richness of imaging sensors’ data and verify the applicability of morphology filtering on both Kinect 1 and 2 depth data. Then, considering the significance of the semantic contours, a multiresolution RGB-D contour extraction method is introduced to suppress the texture inside objects. Therewith, shape-adaptive structuring element (SASE) for each missing or untrusted depth pixel is created in terms of the contour guidance and the feature of human visual system. Efficient and accurate depth recovery can be finally achieved by combining morphology filtering and the obtained SASEs. Experiments on simulated data set, real Kinect 1, and Kinect 2 data show that our method performs better than many competing state-of-the-art approaches, and avoids the blurring around depth discontinuities.
Autors: Chunli Ti;Guodong Xu;Yudong Guan;Yidan Teng;
Appeared in: IEEE Sensors Journal
Publication date: Jul 2017, volume: 17, issue:14, pages: 4534 - 4543
Publisher: IEEE
 
» Depth-Preserving Stereo Image Retargeting Based on Pixel Fusion
Abstract:
In this paper, we propose a pixel fusion-based stereo image retargeting method, which could adaptively retarget stereo images with flexible aspect ratios, simultaneously preserving the depth. Retargeting each image independently by the pixel fusion method ignores the disparity relationship between pixels in the image pair and hence will introduce the distortion of disparity. To address this issue, we advocate to extend the single pixel fusion-based way to be applicable for stereo image pair. First, seams are selected based on the energy function, which simultaneously considers the seam selecting and seam matching. Second, a seam-matching-based matching map is proposed to preserve the disparity relationship between image pair. Then, the scaling factors for the left image are assigned considering both the important object and depth preservation. Subsequently, the scaling factors for the right image are obtained according to the proposed matching map. Based on these scaling factors, the stereo image pair is retargeted with pixel fusion. In contrast to removing pixels to resize image, the way of pixel fusion can obtain more smooth results with less depth distortion. Experimental results demonstrate that our method achieves more preferable qualities in both depth and shape preservation for stereo image retargeting.
Autors: Jianjun Lei;Min Wu;Changqing Zhang;Feng Wu;Nam Ling;Chunping Hou;
Appeared in: IEEE Transactions on Multimedia
Publication date: Jul 2017, volume: 19, issue:7, pages: 1442 - 1453
Publisher: IEEE
 
» Design and Analysis of a High Acceleration Rotary-Linear Voice Coil Motor
Abstract:
To meet the high requirements of precision machining, electrical machines with high acceleration and high precision have become a dedicated field of research. A rotary-linear voice coil motor (VCM) is proposed here, which features the advantage of a high acceleration and a two-degree-of-freedom motion. The structure and operating principle of the rotary-linear VCM is first introduced based on the equivalent magnetic circuit method; the method to eliminate the axial clearance is employed to ensure high precision. Then, the force characteristics of this motor are calculated and analyzed by means of the finite-element method. The mover in the VCM has a lightweight in order to achieve high acceleration, and a stress analysis of the mover brackets is thus conducted. A prototype of the VCM was manufactured and tested to validate its theoretical features. The main parameters of the prototype were obtained, the motor acceleration reaching 140.4 m/, which is enough to meet the requirement of multidimensional precision machining systems. This paper provides a theoretical reference and experimental data for high acceleration rotary-linear VCM in multidimensional precision machining systems.
Autors: Zijiao Zhang;Haibo Zhou;Ji-an Duan;
Appeared in: IEEE Transactions on Magnetics
Publication date: Jul 2017, volume: 53, issue:7, pages: 1 - 9
Publisher: IEEE
 
» Design and Analysis of a New Five-Phase Brushless Hybrid-Excitation Fault-Tolerant Motor for Electric Vehicles
Abstract:
High reliability and wide range of speed regulation are key factors for motor drive system in electric vehicles (EVs). To meet the requirement for EV application, this paper proposes and investigates a new five-phase brushless fault-tolerant hybrid-excitation motor. This motor has several advantages over the conventional permanent magnet (PM) motor, such as high fault tolerance and adjustable flux. In addition, to realize flux regulation, based on the utilization of the high-harmonic component of the stator magnetic motive force (MMF), the rotor field winding and the rotor harmonic winding are designed. Unlike the existing hybrid-excitation machines with rotor PM, the proposed motor can achieve the balance between simple structure and no sliding contacts. Moreover, the topology and operation principle of the proposed motor are analyzed. Also, the characteristics of the proposed motor are investigated by using finite-element analysis and experiments with a 2 kW prototype machine. The experimental results are given to be consistent with the theoretical analysis, which validates the correctness of the theory.
Autors: Li Zhang;Ying Fan;Robert D. Lorenz;Ronghua Cui;Chenxue Li;Ming Cheng;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Jul 2017, volume: 53, issue:4, pages: 3428 - 3437
Publisher: IEEE
 
» Design and Analysis of Compressed Windings for a Permanent Magnet Integrated Starter Generator
Abstract:
This paper focuses on the improved thermal performance of electrical machines by increasing the conductor fill factor. A comparative design study of the integrated starter generator is used as a case study to investigate the mechanical, electrical, and thermal aspects of pressing coils. By performing quasi-static explicit dynamics simulations, deformation of insulation has been investigated. Magnet wires of 1.25 mm diameter are simulated and demonstrated to be compressible up to a 0.73 fill factor without observing insulation failure. Thermal conductivity enhancement of the stator windings at improved slot fill factor is investigated by performing steady-state finite element analysis thermal simulations and short-time thermal transient tests.
Autors: Mehmet C. Kulan;Nick J. Baker;James D. Widmer;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Jul 2017, volume: 53, issue:4, pages: 3371 - 3378
Publisher: IEEE
 
» Design and Applications of Yb/Ga2Se3/C Schottky Barriers
Abstract:
In this paper, the Ga2Se3 crystals are used to design a Yb/Ga2Se3/C Schottky barrier. The device structure is investigated by the X-ray diffraction technique, which reveals a monoclinic-face-centered cubic interfacing type of structure. The barrier is studied by means of current ()–voltage () characteristics in the dark and under light through photoexcitation from tungsten lamp and from the He–Ne laser. In addition, the impedance spectroscopy of these devices is studied in the frequency range of 10–1400 MHz. The photoexcited curve analysis allowed investigating the biasing voltage, illumination power, and energy effects on the diode physical parameters, which are presented by the rectification ratio, the Schottky barrier height, the ideality factor, the series resistance, the photosensitivity, the responsivity, and the external quantum efficiency (EQE). While a maximum photosensitivity of 42 was observed for laser excitation with a wavelength of 632 nm at a reverse bias of 4.4 V, the EQE reached value of 1652% at 19.0 V. On the other hand, the ac current conduction analysis of the electrical conductivity, which was determined from the impedance spectral analysis, indicated that the ac signal processing through the Yb/Ga2Se3/C samples is due to the correlated hopping conduction through localized states of Fermi density of . The high-and biasing-dependent EQE% nominates the Yb/Ga2Se3/C as a tunable optoelectronic device.
Autors: Hazem K. Khanfar;Atef F. Qasrawi;Yasmeen A. Zakarneh;N. M. Gasanly;
Appeared in: IEEE Sensors Journal
Publication date: Jul 2017, volume: 17, issue:14, pages: 4429 - 4434
Publisher: IEEE
 
» Design and Characterization of a Meander-Type Dynamic Inductively Coupled Power Transfer Coil
Abstract:
Dynamic inductive coupled power transfer (DICPT) is one of the most promising technologies for railway power supply where no catenary is available and light boarded energy storage system is desired. This paper presents the design and characterization of a DICPT system based on meander-type coils with different geometrical constraints. Constant coupling is demonstrated with a three-phase solution, simplifying dramatically the control stage. A small-scale prototype is built verifying the power transmission equations. Additionally, different resonance configurations are analyzed with the aim of designing the most efficient solution. Finally, electric equations are presented and a 60-kW DICPT system is designed.
Autors: Ugaitz Iruretagoyena;Irma Villar;Asier Garcia-Bediaga;Luis Mir;Haritza Camblong;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Jul 2017, volume: 53, issue:4, pages: 3950 - 3959
Publisher: IEEE
 
» Design and Development of a Novel Compliant Gripper With Integrated Position and Grasping/Interaction Force Sensing
Abstract:
This paper proposes a new compliant gripper with integrated position and force sensors dedicated to automated microassembly tasks. The uniqueness of the gripper is that it possesses a large gripping range with a bidirectional drive, and it is capable of detecting grasping force and environmental interaction forces in horizonal and vertical axes, respectively. This is enabled by a mechanism design based on a rotary flexure bearing. Moreover, a compliant mechanism with two-stage stiffness is designed to provide the force sensing with dual sensitivities and measuring ranges to accommodate the grasp of objects with different sizes and weights. Analytical models are derived to predict the grasping range, force sensing sensitivities, and ranges. These models are verified by conducting finite-element analysis simulations. A proof-of-concept prototype gripper is developed for experimental calibration and performance testing. Results reveal that the single set of strain-gauge force sensor is able to detect both grasping and interaction forces in an alternate manner. The dual-sensitivity, dual-range force sensor provides a solution to large-range gripper with finer and coarser force sensing in a small and large ranges, respectively .
Autors: Qingsong Xu;
Appeared in: IEEE Transactions on Automation Science and Engineering
Publication date: Jul 2017, volume: 14, issue:3, pages: 1415 - 1428
Publisher: IEEE
 
» Design and Fabrication of a 300 GHz Modified Sine Waveguide Traveling-Wave Tube Using a Nanocomputer Numerical Control Machine
Abstract:
The sine waveguide slow-wave structure is a promising interaction circuit for traveling-wave tubes in the terahertz region because it possesses advantageous properties such as high transmission, easy fabrication, and elimination of the electron beam tunnel. These waveguides could be fabricated by nanocomputer numerical control (CNC) machining, a fabrication method capable of fabricating microscale components. In our study, we evaluate the practical feasibility of manufacturing 300-GHz sine waveguides with the ideal design, using nano-CNC machining. It is found that the ideal sine waveguide circuit must be modified, because of the limitations imposed by the actual tool size of the nano-CNC machine. Simulations of cold- and hot-tests of the circuit—including the electron beam effect—were conducted for both the ideal and the modified sine waveguide circuits. A modified sine waveguide was successfully machined using a nano-CNC machine with a 0.12-mm diameter tool tip. The S-parameters of the fabricated circuit were measured and compared to simulation data. A detailed analysis of the measured transmission loss was performed, and this loss was found to be attributable to a gap left by the assembly process between the two copper plates.
Autors: Wonjin Choi;Ingeun Lee;EunMi Choi;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Jul 2017, volume: 64, issue:7, pages: 2955 - 2962
Publisher: IEEE
 
» Design and Implementation of a Digital Secure Code-Shifted Reference UWB Transmitter and Receiver
Abstract:
This paper presents the first compact hardware implementation of a digital code-shifted reference (CSR) ultra-wideband (UWB) transceiver. The security of the transmission is based on changing the physical properties of the transmission without the use of higher level security options. The software models of the designed transceiver are simulated and verified in both floating-point and fixed-point numerical representations. The synthesizable Verilog description of the transceiver architecture is simulated and verified against its fixed-point simulation model. The secure transceiver is implemented on our custom-developed field-programmable gate array (FPGA) board. The characteristic and implementation results of the secure transceiver architecture on the FPGA are presented. The bit error rate performance of the transceiver is measured in real time on the FPGA using an accurate on-chip Gaussian noise generator and is compared with that of the software simulation model. An ASIC architecture of the CSR-UWB transceiver is estimated to occupy 0.019 mm2 and dissipate 0.63 mW from a 1.0 V supply while operating at 82 MHz in a standard 32-nm CMOS technology.
Autors: Andrew Hennessy;Amirhossein Alimohammad;
Appeared in: IEEE Transactions on Circuits and Systems I: Regular Papers
Publication date: Jul 2017, volume: 64, issue:7, pages: 1927 - 1936
Publisher: IEEE
 
» Design and Measurement of Integrated Converters for Belt-Driven Starter-Generator in 48 V Micro/Mild Hybrid Vehicles
Abstract:
With reference to a 48 V belt-driven starter-generator used in micro/mild hybrid vehicles, this paper shows the design and measurement of an integrated H-bridge and of a compact dc/dc converter, both fabricated in low-cost high voltage-metal oxide semiconductor (HV-MOS) technology. The H-bridge is in charge of rotor excitation and, thanks to a direct copper bonding of the HV-MOS devices on a ceramic substrate, it ensures a full-integrated solution with low on-resistance values. The compact dc/dc converter interfaces the 48 V power domain with the lower voltage domain of sensing and control electronics, such as 5 and 1.65 V in this case study, without using cumbersome inductors and transformers. The latter are difficult to integrate into silicon technology. The converter has a multistage architecture where each stage implements a switched capacitor regulation. Multiple voltage outputs are supported with a configurable regulation factor sustaining an input voltage variation from 6 V (in case of cranking) up to 60 V. Specific design techniques have been implemented to reduce electromagnetic interference (EMI), typical of switching converters. Experimental measurements on fabricated prototype chipsets confirm the suitability of the presented designs for low-EMI 48 V applications.
Autors: Sergio Saponara;Pierre Tisserand;Pierre Chassard;Dieu-My Ton;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Jul 2017, volume: 53, issue:4, pages: 3936 - 3949
Publisher: IEEE
 
» Design and Modeling of Blue-Enhanced and Bandwidth-Extended PN Photodiode in Standard CMOS Technology
Abstract:
A photodiode (PD) structure based on junctions is presented to enhance the responsivity in the blue region and extend the optical bandwidth. The use of subsections or multiple junctions increase the number of generated blue photo-carriers as well as the collection speed of photo-carriers at the edges of the depletion regions. An N-well/Psub PD formed of subsections is designed and fabricated in a standard AMS 0.35- CMOS technology with an OPTO process option. The PD is compared to a solid structure with a single section having the same optical window of . A responsivity improvement of around 10%–15% is measured between 400- and 550-nm wavelengths. The normalized ac responsivity shows a increase in bandwidth compared with the solid PD at 1-V reverse-bias voltage. S-parameter-based voltage-bias-dependent lumped-RLC models are proposed to accurately represent the optoelectrical conversion and the output impedance for both PDs as a function of the reverse-bias voltage and operating frequency range.
Autors: Bassem Fahs;Asif Jahangir Chowdhury;Yiwen Zhang;Javad Ghasemi;Collin Hitchcock;Payman Zarkesh-Ha;Mona Mostafa Hella;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Jul 2017, volume: 64, issue:7, pages: 2859 - 2866
Publisher: IEEE
 
» Design and Optimization for VoD Services With Adaptive Multicast and Client Caching
Abstract:
Multicast and prefix caching are two promising approaches to provide scalable video-on-demand (VoD) services. We contribute to solve the adaptive multicast delivery and the cache allocation problem for VoD services with client caching under asynchronous client requests. We first propose a client caching enabled adaptive multicast delivery scheme, which combines the stream merginglike method with prefix caching and adaptive modulation and coding, to fully exploit the multicast opportunity among asynchronous requests from heterogeneous clients. Next, we derive the bandwidth consumption of the proposed delivery scheme under a given prefix cache allocation and Poisson arrival request. We then optimize the cache allocation to minimize the average bandwidth consumption, and the problem is proved to be convex and solved effectively. Finally, three extreme cases are studied to provide closed-form solutions and more insight on the cache allocation and the delivery scheme for VoD systems.
Autors: Hao Feng;Zhiyong Chen;Hui Liu;
Appeared in: IEEE Communications Letters
Publication date: Jul 2017, volume: 21, issue:7, pages: 1621 - 1624
Publisher: IEEE
 
» Design and Optimization on Training Sequence for mmWave Communications: A New Approach for Sparse Channel Estimation in Massive MIMO
Abstract:
In the next generation of cellular networks, millimeter wave (mmWave) communications will play an important role. With the utilization of mmWave communications, the massive multiple-input multiple-output (MIMO) technique can be effectively employed, which will significantly improve system capacity. However, an effective channel estimation scheme is the prerequisite of system stability and in great need for improvement in massive MIMO systems. In this paper, a channel estimation scheme based on training sequence (TS) design and optimization with high accuracy and spectral efficiency is investigated in the framework of structured compressive sensing. As a new perspective to optimize the block coherence of the sensing matrix, the auto-coherence and cross-coherence of the blocks are proposed and specified as two kinds of key merit factors. In order to optimize the two factors, specific TS is designed and obtained from the inverse discrete Fourier transform of a frequency domain binary training sequence, and a genetic algorithm is adopted afterwards to optimize the merit factors of the TS. It is demonstrated by the simulation results that the block coherence of the sensing matrix can be significantly reduced by the proposed TS design and optimization method. Moreover, by using the proposed optimized TS’s, the channel estimation outperforms the conventional TS design obtained by the brute force search in terms of the correct recovery probability, mean square error, and bit error rate, and can also approach the Cramer–Rao lower bound.
Autors: Xu Ma;Fang Yang;Sicong Liu;Jian Song;Zhu Han;
Appeared in: IEEE Journal on Selected Areas in Communications
Publication date: Jul 2017, volume: 35, issue:7, pages: 1486 - 1497
Publisher: IEEE
 
» Design and Simulation of a 128 kb Embedded Nonvolatile Memory Based on a Hybrid RRAM (HfO2 )/28 nm FDSOI CMOS Technology
Abstract:
Emerging nonvolatile memories (NVM) based on resistive switching mechanism such as RRAM are under intense R&D investigation by both academics and industries. They provide high write/read speed, low power, and good endurance (e.g., >1012) beyond mainstream NVMs, enabling them to be a good candidate for Flash replacement in microcontroller unit. This replacement could significantly decrease the power consumption and the integration cost on advanced CMOS nodes. This paper presents first the HfO2-based RRAM technology and the associated compact model, which includes related physics and model card fitting experimental electrical characterizations. The 128 kb memory architecture based on RRAM technology and 28 nm fully depleted silicon on insulator (FDSOI) CMOS core process is presented with a bottom-up approach, starting from the bit-cell definition up to the complete memory architecture implementation. The key points of the architecture are the use of standard logic MOS exclusively, avoiding any high voltage MOS usage, program/verify procedure to mitigate cycle to cycle variability issue and direct bit-cell read access for characterization purpose. The proposed architecture is validated using postlayout simulations on MOS and RRAM corner cases.
Autors: Jean-Michel Portal;Marc Bocquet;Santhosh Onkaraiah;Mathieu Moreau;Hassen Aziza;Damien Deleruyelle;Kholdoun Torki;Elisa Vianello;Alexandre Levisse;Bastien Giraud;Olivier Thomas;Fabien Clermidy;
Appeared in: IEEE Transactions on Nanotechnology
Publication date: Jul 2017, volume: 16, issue:4, pages: 677 - 686
Publisher: IEEE
 
» Design and Simulation of Compact Optical Modulators and Switches Based on Si–VO2 –Si Horizontal Slot Waveguides
Abstract:
In this paper, a horizontal slot Si–VO2–Si optical waveguide is proposed and its optical properties are investigated. Numerical simulation results show that the effective index and the propagation loss of the proposed waveguide undergo substantial changes upon the VO2 transition from insulating to metallic phase. The effective index and the propagation loss variations of the proposed waveguide are then maximized by optimizing waveguide dimensions. It is shown that 0.226 change in the effective index (Δn eff = 0.226) and 30 dB/μm change in the propagation loss (Δl dB = 30 dB/μm) are achievable using the optimum dimensions. These extraordinary variations in waveguide properties recommend the proposed waveguide as an excellent candidate for optical active device realization. To investigate these applications, performance parameters of the proposed waveguide are further studied in terms of the transition speed and the power consumption. In these studies, the VO2 phase transition is assumed to be actuated by applying an electric field. Two examples of optical active devices based on the proposed waveguide are then presented: an electro-absorption modulator and a 1 × 2 directional coupler optical switch. Finite-difference time-domain simulation of the proposed devices shows very high extinction ratio of 21 dB along the ultrasmall propagation length of 1 μm, for the proposed electro-absorption modulator, and high extinction ratios of ∼18.5 dB and ∼8.6 dB in off- and on-state of the proposed 1 × 2 switch, which has very small length of ∼6 μm. Further simulations also show interesting properties of the proposed devices in terms of the power consumption, insertion loss, and bandwidth.
Autors: Babak Janjan;Mehdi Miri;Abbas Zarifkar;Mohsen Heidari;
Appeared in: Journal of Lightwave Technology
Publication date: Jul 2017, volume: 35, issue:14, pages: 3020 - 3028
Publisher: IEEE
 
» Design Guidelines for Contactless Integrated Photonic Probes in Dense Photonic Circuits
Abstract:
This paper provides detailed guidelines for the optimal design of contactless integrated photonic probes suitable to track and control the local optical power in photonic circuits. With reference to current technology platforms, this paper provides a guide to extract the electrical parameters of the probe and to highlight their role in defining the achievable resolution. Crucial technological and geometrical choices are discussed, together with layout and interconnection solutions oriented to a highly dense integration of the probes. Finally, the criteria for the optimal coupling of the probes to the most suitable readout electronics providing the maximization of the SNR are presented. With these guidelines in mind, transparent in-line local power monitors featuring –35 dBm sensitivity, 40 dB of dynamic range, broadband response from 1.3 to 1.6 μm, a speed down to tens of microsecond and a minimum size of tens of micrometer can be effectively designed for high performance reconfiguration and closed-loop control of complex photonic circuits.
Autors: Marco Carminati;Andrea Annoni;Francesco Morichetti;Emanuele Guglielmi;Giorgio Ferrari;Douglas O. M. de Aguiar;Andrea Melloni;Marco Sampietro;
Appeared in: Journal of Lightwave Technology
Publication date: Jul 2017, volume: 35, issue:14, pages: 3042 - 3049
Publisher: IEEE
 
» Design Methodologies for Low-Power 3-D ICs With Advanced Tier Partitioning
Abstract:
Low power is considered as the driving force for 3-D ICs, yet there have been few thorough design studies on how to reduce power in 3-D ICs. In this paper, we discuss computer-aided design techniques and design methodologies to reduce power consumption in 3-D IC designs using a commercial grade CPU core (OpenSPARC T2 core). To demonstrate power benefits in 3-D ICs, four design techniques are explored: 1) 3-D floorplanning; 2) metal layer usage control for intrablock-level routing; 3) dual-Vth design; and 4) functional unit block (FUB) folding. The benefits and challenges of multiple FUB folding are also discussed. Finally, the through-silicon via technology scaling impact on FUB folding and 3-D power benefit is examined. With the aforementioned methods combined, our 2-tier 3-D designs provide up to 52.3% reduced footprint, 27.9% shorter wirelength, 35.4% decreased buffer cell count, and 27.8% power reduction over the 2-D counterpart under the same performance.
Autors: Moongon Jung;Taigon Song;Yarui Peng;Sung Kyu Lim;
Appeared in: IEEE Transactions on Very Large Scale Integration Systems
Publication date: Jul 2017, volume: 25, issue:7, pages: 2109 - 2117
Publisher: IEEE
 
» Design Methodology for Phase-Locked Loops Using Binary (Bang-Bang) Phase Detectors
Abstract:
We present a linearized analysis of bang-bang phase-locked loops (PLLs) in the frequency domain that is complete and self-consistent. It enables the manual design of frequency synthesis PLLs for loop bandwidth, output phase noise and minimum jitter. Tradeoffs between various parameters of the loop become clear. The analysis is validated against measurements on four very different loops, and helps to answer long-standing questions on aspects of these circuits attributable a hard nonlinearity. A brief designer’s guide is included.
Autors: Hao Xu;Asad A. Abidi;
Appeared in: IEEE Transactions on Circuits and Systems I: Regular Papers
Publication date: Jul 2017, volume: 64, issue:7, pages: 1637 - 1650
Publisher: IEEE
 
» Design of 6–18-GHz High-Power Amplifier in GaAs pHEMT Technology
Abstract:
This paper presents a design procedure for a wideband 6–18-GHz monolithic microwave integrated circuit high-power amplifier (HPA) in 0.25- AlGaAs-InGaAs pHEMT technology. The design is mainly focused on the realization of the passive circuits to provide the required low-loss and wideband impedance transformation networks. The two-stage GaAs HPA achieves an average output power of 39.6 dBm and a peak output power of 40.5 dBm at 11 GHz, in pulsed mode operation, with a small-signal gain of dB over the entire bandwidth. The average power added efficiency (PAE) is 22%, with a peak PAE of 29% at 11 GHz. The HPA chip occupies an area of . The achieved output power and the corresponding power density of 0.51 W/ are amongst the highest reported values in wideband GaAs HPAs.
Autors: Masoud Meghdadi;Ali Medi;
Appeared in: IEEE Transactions on Microwave Theory and Techniques
Publication date: Jul 2017, volume: 65, issue:7, pages: 2353 - 2360
Publisher: IEEE
 
» Design of a Compact UWB Filter With High Selectivity and Superwide Stopband
Abstract:
This letter presents a design of compact ultra-wideband bandpass filter (BPF) with high selectivity and superwide stopband. Three resonant modes from the multiple-mode resonator (MMR) based on half-mode substrate integrated waveguide (HMSIW) structure and four resonant modes from a pair of electromagnetic bandgap loaded parallel-coupled lines can constitute a wideband performance. Superwide stopband can be achieved and two transmission zeros are realized on both sides of the passband to improve the filter selectivity. A prototype of the BPF operating from 3.1 to 10.4 GHz with an extremely broad stopband region from 10.7 to 24 GHz and a rejection level of 15 dB is demonstrated in the measured results.
Autors: Chun-Xia Zhou;Pei-Pei Guo;Kang Zhou;Wen Wu;
Appeared in: IEEE Microwave and Wireless Components Letters
Publication date: Jul 2017, volume: 27, issue:7, pages: 636 - 638
Publisher: IEEE
 
» Design of a Gait Phase Recognition System That Can Cope With EMG Electrode Location Variation
Abstract:
Electromyogram (EMG) signal-based gait phase recognition for walking-assist devices warrants much attention in human-centered system design as it well exemplifies human-in-the-loop control where the system's prediction directly affects subsequent walking motion. Since walking motion poses considerable variations in electrode placement, performance reliability of such systems is contingent on a combination of electrode montage and a feature extraction method that takes into account underlying physiological factors of peripheral muscles where electrodes are placed. In many practical applications, however, proper consideration of effects of the electrode location variation on performance reliability of the system has received scant empirical attention. Here, based on a user-centered design principle, we establish a gait phase recognition system that is capable of rigidly controlling ill effects due to this covariate by carrying out a large-scale analysis that combines statistical, model-based, and empirical approaches. In doing so, we have developed a special sensing suit for the control of electrode placement and a reliable data acquisition. We then have conducted a nonparametric statistical analysis on class separability values of thirty types of EMG feature sets, followed by a model-based analysis to address the tradeoff between class separability and dimensionality. To further address the issue of how these results generalize to independent systems and data sets, we have carried out an empirical performance assessment over six classification methods. First, the two feature types, Integral of Absolute Value and Histogram, and a combination of the two are shown to be robust against electrode location variations while providing a firm performance guarantee. Second, system organization scenarios are presented on a case-by-case basis, allowing us to trade off system complexity for on-line adaptation capability. Collectively, our integrated analysis l- nds itself to formulating a guideline for design of highly reliable EMG signal-based walking assistant systems in a variety of smart home scenarios.
Autors: Sang Wan Lee;Taeyoub Yi;Jin-Woo Jung;Zeungnam Bien;
Appeared in: IEEE Transactions on Automation Science and Engineering
Publication date: Jul 2017, volume: 14, issue:3, pages: 1429 - 1439
Publisher: IEEE
 
» Design of a Multipolarized RFID Reader Antenna for UHF Near-Field Applications
Abstract:
This paper presents our investigation into a novel ultrahigh-frequency (UHF) radio frequency identification (RFID) multipolarized reader antenna based on a pair of symmetrical meandering open-ended microstrip lines for near-field applications. The near-field and multipolarization operation is achieved by introducing a 90° phase shift between the currents flowing along the opposite side of two branches. The proposed antenna is shown to generate a uniform and strong electric field in its near-field region within a reading volume: mm (). The simulated and measured impedance bandwidths (−10 dB) agree very well, ranging from 825 to 965 MHz and covering the UHF RFID standard. In addition, it exhibits a low far-field gain, avoiding to misreading the tags outside the near-field region. The fabricated antenna was fully tested with multiple tag antennas that are placed in different orientations and even in a conveyor system, demonstrating a 100% reading rate of arbitrarily oriented tags within the reading zone.
Autors: Yuan Yao;Yishan Liang;Junsheng Yu;Xiaodong Chen;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Jul 2017, volume: 65, issue:7, pages: 3344 - 3351
Publisher: IEEE
 
» Design of a Single-Stage Inductive-Power-Transfer Converter for Efficient EV Battery Charging
Abstract:
This paper studies wireless charging of lithium-ion batteries for electric vehicles. The charging profile mandates a constant-current (CC) charging for a discharged battery until the battery voltage reaches the cutoff voltage at rated power. The charging continues at the cutoff voltage with a constant-voltage (CV) charging at a power level down to 3% of the rated power in order to fully charge the battery. An inductive-power-transfer (IPT) converter should be designed with minimal number of stages to achieve high efficiency. However, high efficiency for such a wide load range is difficult to achieve. Moreover, the efficiency-to-load relationship is distinctly different for CC and CV charging operations, posing difficulties for the single-stage design. This paper describes the design of a single-stage IPT converter that complies with the battery charging profile and, at the same time, achieves optimal efficiency. Design optimization includes soft switching for the entire battery load range, efficiency optimization for CC and CV modes of operation, and system efficiency optimization for the whole battery charging profile. Measured results of two experimental IPT battery chargers are presented for illustration and verification.
Autors: Zhicong Huang;Siu-Chung Wong;Chi K. Tse;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Jul 2017, volume: 66, issue:7, pages: 5808 - 5821
Publisher: IEEE
 
» Design of an Axial-Type Magnetic Gear for the Contact-Less Recharging of a Heavy-Duty Bus Flywheel Storage System
Abstract:
This paper presents the electromagnetic design and performance assessment of an axial flux magnetic gear (AMG) for the contact-less energy transfer to an on-board flywheel energy storage system (FESS) to supply heavy-duty electric buses. The AMG electromagnetic configuration is designed to cope with the system torque/speed requirements according to the FESS specifications for a typical driving cycle of an urban bus. Starting from a preliminary sizing by analytical formulations, the torque performance is improved by more accurate finite element analyses based on simplified models. Different parameters also affecting the AMG size are considered to identify an optimized feasible configuration. Finally, the evaluation of the core losses for a full recharge operation enables one to choose the more convenient ferromagnetic material.
Autors: Mauro Andriollo;Fabio Graziottin;Andrea Tortella;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Jul 2017, volume: 53, issue:4, pages: 3476 - 3484
Publisher: IEEE
 
» Design of Arbitrary-Order Photonic Temporal Differentiators Based on Phase-Modulated Fiber Bragg Gratings in Transmission
Abstract:
All-optical arbitrary-order temporal differentiators are demonstrated with phase-modulated fiber Bragg gratings (PM-FBGs) in transmission for the first time. The transmissive PM-FBGs are designed by employing a novel two-step nonlinear optimization method, which consists of unconstrained nonlinear optimization method step and constrained nonlinear optimization method step. Specifically, the first unconstrained nonlinear step is used to get appropriate parameters as input to the second step, while the second constrained nonlinear step is employed to generate more accurate result based on the output of the first step. The proposed method does not impose much restriction on the initial input parameters and also improves the result accuracy compared with previous one-step nonlinear optimization method. Examples of 0.5th-order, first-order, and second-order differentiators are designed and numerically simulated. The numerical results show that the designed PM-FBG differentiators are very accurate with a bandwidth up to 500 GHz. Moreover, the proposed method can be applied in designing arbitrary-order differentiators with the differentiation order n > 0.
Autors: Xin Liu;Xuewen Shu;
Appeared in: Journal of Lightwave Technology
Publication date: Jul 2017, volume: 35, issue:14, pages: 2926 - 2932
Publisher: IEEE
 
» Design of Electric Buses of Rapid Transit Using Hybrid Energy Storage and Local Traffic Parameters
Abstract:
In this paper, an electric powertrain for a bus of rapid transit (BRT) is designed, which includes the driving behavior, road infrastructure, orography, and traffic system as a fundamental part of the design. An electric hybrid power source is proposed to efficiently recover the braking energy and for fast charging at bus stations. Since the local traffic parameters have direct influence over the BRT energy consumption, an energy methodology to obtain a characteristic and energy representative synthetic driving cycle is proposed and then experimentally tested in a real BRT system. The Transmilenio BRT system of Bogotá, Colombia, was chosen as a case study. This BRT system is selected due to its particular orography that increases the energy consumption. Additionally, a BRT dynamic model is proposed to analyze the energy requirements prior to designing the electric powertrain and the two energy storage systems. As a result, and as the main contribution, an innovative general methodology to BRT powertrain design is established using the BRT dynamic model and local traffic parameters.
Autors: Walter Naranjo;Luis E. Muñoz Camargo;Javier E. Pereda;Camilo Cortes;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Jul 2017, volume: 66, issue:7, pages: 5551 - 5563
Publisher: IEEE
 
» Design of Highly Nonlinear Few-Mode Fiber for C-Band Optical Parametric Amplification
Abstract:
We present a thorough description of the dominating intramodal and intermodal four-wave mixing interactions occurring in a highly nonlinear few-mode fiber and describe their phase matching conditions. Those interactions that result in few-mode parametric amplification using a single-frequency pump are of particular interest. Thus, based on the phase matching conditions of such interactions, we outline the dispersion properties that a fiber should possess in order to achieve few-mode parametric amplification, while having minimal modal crosstalk. Accordingly, we design and optimize two fibers such that they meet the dispersion requirements for parametric amplification of two and four spatial modes, respectively. The two-mode fiber provides a maximum differential modal gain (DMG) of 0.21 dB across the C-band with a minimum gain of 9.5 dB per mode, while the four-mode fiber provides a maximum DMG of 1.51 dB with a minimum gain of 6.5 dB per mode over a 19 nm bandwidth in the C-band. The designed fibers are highly nonlinear dispersion-shifted few-mode fibers that provide both high nonlinearity and low dispersion for several modes in the C-band, which have not been demonstrated simultaneously to date. We also take practical fabrication issues into account and analyze and compare the tolerances of the structural parameters of both fibers to small deviations from their optimal values.
Autors: Elham Nazemosadat;Abel Lorences-Riesgo;Magnus Karlsson;Peter A. Andrekson;
Appeared in: Journal of Lightwave Technology
Publication date: Jul 2017, volume: 35, issue:14, pages: 2810 - 2817
Publisher: IEEE
 
» Design of Low-Profile Metamaterial-Loaded Substrate Integrated Waveguide Horn Antenna and Its Array Applications
Abstract:
A metamaterial-loaded substrate integrated wave-guide (SIW) horn antenna and its array application are researched in this communication. The mushroom-type metamaterial is placed in front of SIW horn aperture, and much improvement in impedance matching is achieved on a 1/-thickness substrate. Due to the backward wave generated by the metamaterial, backward endfire radiation pattern is observed for the proposed antenna. Experimental results indicate that a fractional impedance bandwidth of 10.6% is obtained for a fabricated prototype. Furthermore, a shunt four-element array and a monopulse four-element array are designed based on the novel SIW horn element to further enhance the radiation performance. Results show that performances of wide operating bandwidth, low profile, and backward endfire radiation pattern are maintained for the designed two arrays.
Autors: Yang Cai;Yingsong Zhang;Liu Yang;Yufan Cao;Zuping Qian;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Jul 2017, volume: 65, issue:7, pages: 3732 - 3737
Publisher: IEEE
 
» Design of Nonvolatile SRAM with Ferroelectric FETs for Energy-Efficient Backup and Restore
Abstract:
Nonvolatile SRAM (nvSRAM) has emerged as a promising approach to reducing the standby energy consumption by storing the state into an in situ nonvolatile memory element and shutting down the power supply. Existing nvSRAM solutions based on a nonvolatile backup in magnetic tunnel junction and ReRAM, however, are costly in backup and restore energy due to static current. This cost results in a long break-even time (BET) when compared with a lowered voltage standby volatile SRAM. This brief proposes an nvSRAM based on ferroelectric FETs (FeFETs) that are capable of fully avoiding such static current. A simple differential backup and restore circuitry is proposed, achieving sub-fJ/cell total energy per backup and restore operation at the 10-nm node. This leads to hundreds of times BET improvement over existing ReRAM nvSRAM solutions. This nvSRAM also indicates the future FeFET design trends for such memory-logic synergy.
Autors: Xueqing Li;Kaisheng Ma;Sumitha George;Win-San Khwa;John Sampson;Sumeet Gupta;Yongpan Liu;Meng-Fan Chang;Suman Datta;Vijaykrishnan Narayanan;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Jul 2017, volume: 64, issue:7, pages: 3037 - 3040
Publisher: IEEE
 
» Design of Silicon Phoxonic Crystal Waveguides for Slow Light Enhanced Forward Stimulated Brillouin Scattering
Abstract:
We propose and design the silicon phoxonic crystal waveguides to achieve forward stimulated Brillouin scattering (FSBS). The waveguides with honeycomb-lattice structure are able to support the photonic and phononic band gaps simultaneously. By the optimized design, the corresponding optical and acoustic defect modes are tightly confined in the line defect to enhance acousto-optic coupling, resulting in the intramode and intermode FSBS. The three-dimensional (3D) full-vectorial theoretical formulation is applied to analyze the influences of structural parameters on FSBS gain. By the coupled-mode equations, we explore the FSBS process taking into account the slow light enhanced factor, two-photon and free-carrier absorptions in the slow-light phoxonic crystal waveguide. The results indicate that 18 dB Stokes amplification is obtained with 100 mW pump power in a short waveguide length of 200 μm. Such approach enables the realization of on-chip FSBS with CMOS technologies.
Autors: Ruiwen Zhang;Junqiang Sun;
Appeared in: Journal of Lightwave Technology
Publication date: Jul 2017, volume: 35, issue:14, pages: 2917 - 2925
Publisher: IEEE
 
» Design of Ultrawideband Stepped-Frequency Radar for Imaging of Obscured Targets
Abstract:
A stepped-frequency radar that allows for adaptability in the radiated spectrum while maintaining high-resolution radar imagery has been developed. The spectrally agile frequency-incrementing reconfigurable (SAFIRE) radar system is a vehicle-mounted, ground-penetrating radar that is capable of producing high-resolution radar imagery for the detection of obscured targets (either buried or concealed surface targets). It can be easily transitioned between forward- and side-looking orientations. The SAFIRE system is capable of precisely excising subbands within its operating bandwidth, thus making the system “spectrally agile.” It is also highly reconfigurable thereby allowing for on-the-fly adjustment of many of the system parameters. The spectrally agile and reconfigurable aspects of the SAFIRE radar together with its enhanced IF processing scheme represent a novel contribution to the state of the art. This paper discusses the system design, implementation, and performance characteristics, and also presents preliminary high-resolution imagery.
Autors: Brian R. Phelan;Kenneth I. Ranney;Kyle A. Gallagher;John T. Clark;Kelly D. Sherbondy;Ram M. Narayanan;
Appeared in: IEEE Sensors Journal
Publication date: Jul 2017, volume: 17, issue:14, pages: 4435 - 4446
Publisher: IEEE
 
» Design Optimization of a Hydrogen Sensor for ITER Pb16Li Blankets
Abstract:
A new design of a hydrogen sensor for Pb-16Li, based on the previous experience and testing results, is performed. The new permeation sensor is made of pure iron. The intention of this optimized design is to improve the response time and to minimize the number of welds to be made. Some simulations were conducted to estimate the time taken for the sensor to reach equilibrium with the partial pressure of hydrogen in the lead–lithium. With respect to the old sensor design, the diameter of the steel connection pipe has been reduced, while its length has been increased. In this way, it was possible to reduce the dead volume within the sensor and increase the permeation area, giving the sensor a faster time response.
Autors: Luigi Candido;Iuri Nicolotti;Marco Utili;Massimo Zucchetti;
Appeared in: IEEE Transactions on Plasma Science
Publication date: Jul 2017, volume: 45, issue:7, pages: 1831 - 1836
Publisher: IEEE
 
» Design, Realization, and Evaluation of a Riemann Pump in GaN Technology
Abstract:
The realization of a novel Riemann Pump for radio frequency digital-to-analog converters (RF DACs) in combination with a power amplifier is presented, which improves the signal-to-noise ratio of conventional converter concepts. The presented concept results in an arbitrary waveform generator that at the same time is capable to provide several watts of output power at RF-frequencies to . Furthermore, the gallium nitride (GaN) high-electron-mobility transistor technology provides high-switching frequencies to ensure an oversampling ratio of 5 for a wide baseband bandwidth. The Riemann Pump, which is controlled with a digital bit-stream, is based on the current-steering topology and provides the possibility to synthesize arbitrary waveforms. A 2-b RF DAC was designed with multiple GaN monolithic microwave-integrated circuits and proves the feasibility to generate arbitrary waveforms. Measurement results yield triangular signals with a baseband frequency of 100 MHz for an input-control data rate of 200 Mb/s.
Autors: Markus Weiß;Christian Friesicke;Thomas Metzger;Edgar Schmidhammer;Rüdiger Quay;Oliver Ambacher;
Appeared in: IEEE Microwave and Wireless Components Letters
Publication date: Jul 2017, volume: 27, issue:7, pages: 672 - 674
Publisher: IEEE
 
» Designed Simulation and Experiment of a Piezoelectric Energy Harvesting System Based on Vortex-Induced Vibration
Abstract:
To transform kinetic energy of flowing water into electricity, an energy harvesting system based on vortex-induced vibration is investigated. In accordance with the theory of flow around bluff bodies, the Karman vortex street is first created to improve the vibrational energy of water. After that, the forces from shedding vortices make the polyvinylidene fluoride (PVDF) beam vibrate periodically. The electromechanical energy conversion is then completed based on the direct piezoelectric effect. The mathematical model is divided into a hydroelasticity coupled system and an electromechanics system based on material properties. Afterward, COMSOL Multiphysics is adopted to simulate the system performance with physical fields fully coupled, which presents the system vibration clearly. The forces applied on the beam have positive relationships with the flow velocity and the diameter of the cylinder and so does the output voltage. The electromechanical conversion efficiency of the PVDF beam reaches 17.8% with the highest vibration frequency. With low flow velocities, the results from the corresponding experiments agree well with the simulation data. The feasibility of this energy harvesting system is proved in water.
Autors: Feifei Pan;Zhike Xu;Long Jin;Peng Pan;Xiu Gao;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Jul 2017, volume: 53, issue:4, pages: 3890 - 3897
Publisher: IEEE
 
» Detection and Compensation of Periodic Motion in Magnetic Particle Imaging
Abstract:
The temporal resolution of the tomographic imaging method magnetic particle imaging (MPI) is remarkably high. The spatial resolution is degraded for measured voltage signal with low signal-to-noise ratio, because the regularization in the image reconstruction step needs to be increased for system-matrix approaches and for deconvolution steps in -space approaches. To improve the signal-to-noise ratio, blockwise averaging of the signal over time can be advantageous. However, since block-wise averaging decreases the temporal resolution, it prevents resolving the motion. In this paper, a framework for averaging motion-corrupted MPI raw data is proposed. The motion is considered to be periodic as it is the case for respiration and/or the heartbeat. The same state of motion is thus reached repeatedly in a time series exceeding the repetition time of the motion and can be used for averaging. As the motion process and the acquisition process are, in general, not synchronized, averaging of the captured MPI raw data corresponding to the same state of motion requires to shift the starting point of the individual frames. For high-frequency motion, a higher frame rate is potentially required. To address this issue, a binning method for using only parts of complete frames from a motion cycle is proposed that further reduces the motion artifacts in the final images. The frequency of motion is derived directly from the MPI raw data signal without the need to capture an additional navigator signal. Using a motion phantom, it is shown that the proposed method is capable of averaging experimental data with reduced motion artifacts. The methods are further validated on in-vivo data from mouse experiments to compensate the heartbeat.
Autors: N. Gdaniec;M. Schlüter;M. Möddel;M. G. Kaul;K. M. Krishnan;A. Schlaefer;T. Knopp;
Appeared in: IEEE Transactions on Medical Imaging
Publication date: Jul 2017, volume: 36, issue:7, pages: 1511 - 1521
Publisher: IEEE
 
» Detection and Correction of Systematic Errors in Instrument Transformers Along With Line Parameter Estimation Using PMU Data
Abstract:
We consider the following two estimation problems from synchrophasor measurements: first, estimation of positive sequence transmission line parameters and second, estimation of ratio correction factors for instrument transformers (ITs), also known as remote meter calibration (RMC). These two seemingly distinct problems are actually interrelated because incorrect parameters of any one set adversely affects the results of another. Hence, a simultaneous line parameter and RMC approach is proposed. Following extensions and adaptions viz., implicit RMC, explicit RMC, solving an individual line problem, and solving a network level problem are proposed. Open-circuit tests on transmission lines are proposed to improve accuracy in RMC. A decibel-scale-based statistical score is introduced for detection of ITs which require calibration. Extensive simulation results are presented to justify the claims.
Autors: Kedar V. Khandeparkar;Shreevardhan A. Soman;Gopal Gajjar;
Appeared in: IEEE Transactions on Power Systems
Publication date: Jul 2017, volume: 32, issue:4, pages: 3089 - 3098
Publisher: IEEE
 
» Detection and Localization of Robotic Tools in Robot-Assisted Surgery Videos Using Deep Neural Networks for Region Proposal and Detection
Abstract:
Video understanding of robot-assisted surgery (RAS) videos is an active research area. Modeling the gestures and skill level of surgeons presents an interesting problem. The insights drawn may be applied in effective skill acquisition, objective skill assessment, real-time feedback, and human–robot collaborative surgeries. We propose a solution to the tool detection and localization open problem in RAS video understanding, using a strictly computer vision approach and the recent advances of deep learning. We propose an architecture using multimodal convolutional neural networks for fast detection and localization of tools in RAS videos. To the best of our knowledge, this approach will be the first to incorporate deep neural networks for tool detection and localization in RAS videos. Our architecture applies a region proposal network (RPN) and a multimodal two stream convolutional network for object detection to jointly predict objectness and localization on a fusion of image and temporal motion cues. Our results with an average precision of 91% and a mean computation time of 0.1 s per test frame detection indicate that our study is superior to conventionally used methods for medical imaging while also emphasizing the benefits of using RPN for precision and efficiency. We also introduce a new data set, ATLAS Dione, for RAS video understanding. Our data set provides video data of ten surgeons from Roswell Park Cancer Institute, Buffalo, NY, USA, performing six different surgical tasks on the daVinci Surgical System (dVSS) with annotations of robotic tools per frame.
Autors: Duygu Sarikaya;Jason J. Corso;Khurshid A. Guru;
Appeared in: IEEE Transactions on Medical Imaging
Publication date: Jul 2017, volume: 36, issue:7, pages: 1542 - 1549
Publisher: IEEE
 
» Detection of a Moving Magnetic Dipole Target Using Multiple Scalar Magnetometers
Abstract:
A detection procedure for a moving magnetic dipole target by using at least three scalar magnetometers is proposed in this letter. The magnetometers are deployed on the ground or seafloor, while the target is traveling along a straight line at a constant speed above the ground. First, the range from each magnetometer to the closest point of approach (CPA) on the flight line as well as the instant that the target passes by the CPA is estimated by adopting the orthonormal basis function expansion method. Then, the moving parameters, including the moving direction, speed, and elevation, are found through basic geometry relations. Finally, the magnetic moment is determined by solving a linear system by using the least-squares method. Both simulated and field experimental data are employed to demonstrate the proposed scheme.
Autors: C. P. Du;M. Y. Xia;S. X. Huang;Z. H. Xu;X. Peng;H. Guo;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Jul 2017, volume: 14, issue:7, pages: 1166 - 1170
Publisher: IEEE
 
» Development and Evaluation of a Wearable Device for Sleep Quality Assessment
Abstract:
Objective: In this study, a wearable actigraphy recording device with low sampling rate (1 Hz) for power saving and data reduction and a high accuracy wake-sleep scoring method for the assessment of sleep were developed. Methods: The developed actigraphy recorder was successfully applied to overnight recordings of 81 subjects with simultaneous polysomnography (PSG) measurements. The total length of recording reached 639.8 h. A wake-sleep scoring method based on the concept of movement density evaluation and adaptive windowing was proposed. Data from subjects with good (N = 43) and poor (N = 16) sleep efficiency (SE) in the range of 52.7–97.42% were used for testing. The Bland–Altman technique was used to evaluate the concordance of various sleep measurements between the manual PSG scoring and the proposed actigraphy method. Results: For wake-sleep staging, the average accuracy, sensitivity, specificity, and kappa coefficient of the proposed system were 92.16%, 95.02%, 71.30%, and 0.64, respectively. For the assessment of SE, the accuracy of classifying the subject with good or poor SE reached 91.53%. The mean biases of SE, sleep onset time, wake after sleep onset, and total sleep time were −0.95%, 0.74 min, 2.84 min, and −4.3 min, respectively. Conclusion: These experimental results demonstrate the robustness and reliability of our method using limited activity information to estimate wake-sleep stages during overnight recordings. Significance: The results suggest that the proposed wearable actigraphy system is practical for the in-home screening of objective sleep mea- urements and objective evaluation of sleep improvement after treatment.
Autors: Chih-En Kuo;Yi-Che Liu;Da-Wei Chang;Chung-Ping Young;Fu-Zen Shaw;Sheng-Fu Liang;
Appeared in: IEEE Transactions on Biomedical Engineering
Publication date: Jul 2017, volume: 64, issue:7, pages: 1547 - 1557
Publisher: IEEE
 
» Development of a High Gain 325–500 GHz Antenna Using Quasi-Planar Reflectors
Abstract:
A high gain quasi-planar reflector antenna for 325–500 GHz applications is investigated in this paper. The antenna is composed of four parts: a feeding horn, quasi-planar reflectors, choke slots, and an E-plane flared horn. The quasi-planar reflectors are designed to expand the H-plane radiation aperture. The choke slots are used to suppress the reflected wave from the sidewall and reduce the impact on the radiation performance. Detailed design principle is presented, and a prototype having a center frequency of 400 GHz is designed for demonstrations. To verify the design, the fabricated prototype is measured using a terahertz vector network analyzer in a THz chamber. Measured results show that the fabricated prototype achieves a wide impedance bandwidth of 43.75% from 325 to 500 GHz with a reflection coefficient below −20 dB. The maximum gain is 32 dBi at 500 GHz and the gain is higher than 26.5 dBi over the whole operating band. The proposed antenna has a quasi-planar form which can be accurately fabricated by using the conventional low-cost metallic milling process. It has a compact size, a low fabrication cost, a high radiation gain, and a wide operating bandwidth.
Autors: Kuikui Fan;Zhang-Cheng Hao;Quan Yuan;Wei Hong;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Jul 2017, volume: 65, issue:7, pages: 3384 - 3391
Publisher: IEEE
 
» Development of a New Low-Cost and Reliable Core-Less Current Probe for Conductor With Reduced Access
Abstract:
A new coreless non-intrusive current probe is presented in this paper. Most of the existing current sensors require 360° access to the wire, while the proposed probe accurately measures the current even if the access to the wire is limited to a small angle. Another new feature of the probe is that its output is not sensitive to the variation in the gap between the wire and the probe, which is a major advantage as it helps to provide reliable measurement over time. The proposed probe employs two sets of high sensitive and lightweight Hall effect or giant magneto-resistance-based sensors. Results from the experimental studies conducted showed that the proposed configuration is insensitive to the variation in the gap between the wire and the probe. This feature ensures that the output is independent of the insulation thickness, vibration, thermal expansion, etc. Two prototypes of the proposed probes have been developed and tested. The results obtained established the feasibility of the proposed low-cost current sensor.
Autors: Noby George;S. Gopalakrishna;
Appeared in: IEEE Sensors Journal
Publication date: Jul 2017, volume: 17, issue:14, pages: 4619 - 4627
Publisher: IEEE
 
» Development of a Subterahertz Folded-Waveguide Extended Interaction Oscillator
Abstract:
A novel type of two-section folded wave- guide (TSFW) slow wave structure for the development of a subterahertz (sub-THz) extended interaction oscillator (EIO) is proposed in this paper. We focus on the development of sub-THz EIO, in which the key parts, including the electron optics system, the high frequency structure for beam–wave interaction, and output window, are fabricated and tested. Based on the key parts, the prototype of EIO is developed. The experimental results show that over 12-W output power at the frequency of 107.9 GHz at 2% duty cycle is achieved. This paper demonstrates that the feasibility of a high power THz oscillator can be obtained by the use of a prebunching electron beam produced by TSFW.
Autors: Wenxin Liu;Zhaochuan Zhang;Chao Zhao;Xin Guo;Zhenxia Zhang;Suying Liao;
Appeared in: IEEE Transactions on Plasma Science
Publication date: Jul 2017, volume: 45, issue:7, pages: 1731 - 1738
Publisher: IEEE
 
» Development of Dithienosilole-Pyridalthiadiazole-Based Copolymer as an Electron Donor in Organic Photovoltaic Cells
Abstract:
The effect of nitrogen insertion in a benzothiadiazole (BT) moiety was investigated via the synthesis of a novel copolymer based on dithienosilole (DTS) and pyridalthiadiazole (PT), the heterocyclic counterpart. Stille cross coupling of the electron rich and electron poor units yields poly[(4, 4’-didodecyldithieno[3, 2-b:2’, 3’-d]silole-2, 6-diyl)-alt-(2, 1, 3-pyridalthiadiazole-4, 7-diyl), a nonsoluble polymer. Dense π–π stacking interactions that inhibited polymer solubility were cured by the introduction of two solubilizing hexylthiophene spacers, and a new soluble low-bandgap copolymer, namely poly[(4, 4’-didodecyldithieno[3, 2-b:2’, 3’-d]silole-2, 6-diyl)-alt-{4, 7-bis[2-(3-hexyl)thienyl]-2, 1, 3-pyridalthiadiazole-5, 5’-diyl}] (PDTSDTPT), was alternatively obtained. For reasons of comparison, the corresponding oligomer, i.e., ODTSDTPT, was also synthesized. Their chemical, thermal, optical, electrical, and electrochemical properties were investigated. UV–visible spectroscopy revealed that PDTSDTPT alternating copolymer is more absorbing than its BT analog. It has a lower optical bandgap, higher absorptivity, and red-shifted absorption spectrum into the near-infrared region up to 900 nm. Photovoltaic applicability was investigated for PDTSDTPT and its derived oligomer in bulk heterojunction solar cells employing PC 60BM, [6,6]-phenyl-C60 butyric acid methyl ester, as the n-type semiconductor. Significant improvement of open-circuit voltage was evidenced with PT-based materials. The short-circuit current (J SC) and fill factor (FF), however, remain a material of continuous improvement by morphology control.
Autors: Zeinab El-Moussawi;Hussein Medlej;Ali Nourdine;Solenn Berson;Joumana Toufaily;Tayssir Hamieh;Lionel Flandin;
Appeared in: IEEE Transactions on Nanotechnology
Publication date: Jul 2017, volume: 16, issue:4, pages: 574 - 581
Publisher: IEEE
 
» Development of ReFaST Pyrometer for Measuring Surface Temperature With Unknown Emissivity: Methodology, Implementation, and Validation
Abstract:
The accuracy of temperature measurement by optical pyrometer depends largely on the emissivity configuration. However, determination of emissivity is a hard task as it varies with wavelength, temperature, and physical state of the surface. In this paper, we propose a new type of pyrometer named Reflector with a Fast Switching Tube to measure surface temperature as well as emissivity. The invention is featured by a novel reflector equipped with a fast switching tube inside. The tube can be moved to make two measurements, one is to measure intrinsic radiation from the target, and the other is to measure intrinsic and multiple reflectance radiation; then, the emissivity and temperature are solved out simultaneously. For accuracy validation, we make a new type of thermocouple, namely, flat-type thermocouple and measure the surface of it. By measuring the thermocouple immediately, the temperature drop between the measured surface and the thermocouple can be avoided. The measurement difference is 1.0 °C on average compared with the flat-type thermocouple ranging from 600 °C to 900 °C. The measurement uncertainty is evaluated based on a Monte Carlo method, and the standard uncertainty is 1.4 °C at 750 °C.
Autors: Xunjian Che;Zhi Xie;
Appeared in: IEEE Transactions on Instrumentation and Measurement
Publication date: Jul 2017, volume: 66, issue:7, pages: 1845 - 1855
Publisher: IEEE
 
» Device-Free Wireless Localization and Activity Recognition: A Deep Learning Approach
Abstract:
Device-free wireless localization and activity recognition (DFLAR) is a new technique, which could estimate the location and activity of a target by analyzing its shadowing effect on surrounding wireless links. This technique neither requires the target to be equipped with any device nor involves privacy concerns, which makes it an attractive and promising technique for many emerging smart applications. The key question of DFLAR is how to characterize the influence of the target on wireless signals. Existing work generally utilizes statistical features extracted from wireless signals, such as mean and variance in the time domain and energy as well as entropy in the frequency domain, to characterize the influence of the target. However, a feature suitable for distinguishing some activities or gestures may perform poorly when it is used to recognize other activities or gestures. Therefore, one has to manually design handcraft features for a specific application. Inspired by its excellent performance in extracting universal and discriminative features, in this paper, we propose a deep learning approach for realizing DFLAR. Specifically, we design a sparse autoencoder network to automatically learn discriminative features from the wireless signals and merge the learned features into a softmax-regression-based machine learning framework to realize location, activity, and gesture recognition simultaneously. Extensive experiments performed in a clutter indoor laboratory and an apartment with eight wireless nodes demonstrate that the DFLAR system using the learned features could achieve 0.85 or higher accuracy, which is better than the systems utilizing traditional handcraft features.
Autors: Jie Wang;Xiao Zhang;Qinhua Gao;Hao Yue;Hongyu Wang;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Jul 2017, volume: 66, issue:7, pages: 6258 - 6267
Publisher: IEEE
 
» DGLB: Distributed Stochastic Geographical Load Balancing over Cloud Networks
Abstract:
Contemporary cloud networks are being challenged by the rapid increase of user demands and growing concerns about global warming, due to their substantial energy consumption. This requires future data centers to be both energy efficient and sustainable, which calls for leveraging cutting-edge features and the flexibility provided by the modern smart grids. To fulfill those goals, this paper puts forward a systematic approach to designing energy-aware traffic-efficient geographical load balancing schemes for data-center networks that are not only optimal, but also computationally efficient and amenable to distributed implementation. Under this comprehensive approach, workload and power balancing schemes are designed jointly across the network, both delay-tolerant and interactive workloads are accommodated, novel smart-grid features such as energy storage units are incorporated to cope with renewables, and incentive pricing mechanisms are adopted in the design. To further account for the spatio-temporal variation of demands, energy prices and renewables, the task is formulated as a two-timescale stochastic optimization. Leveraging dual stochastic approximation and the fast iterative shrinkage-thresholding algorithm (FISTA), the proposed optimization is decomposed across time slots (first-stage) and data centers (second-stage). While the resultant online algorithm is strictly feasible and provably optimal under a Markovian assumption for the underlying random processes, extensive numerical tests further demonstrate that it also works well in real-data scenarios, where the underlying randomness is highly correlated across time.
Autors: Tianyi Chen;Antonio G. Marques;Georgios B. Giannakis;
Appeared in: IEEE Transactions on Parallel and Distributed Systems
Publication date: Jul 2017, volume: 28, issue:7, pages: 1866 - 1880
Publisher: IEEE
 
» Differential Structure With Graphene Oxide for Both Humidity and Temperature Sensing
Abstract:
A graphene oxide (GO)-based sensor with differential structure was designed to detect both humidity and temperature. Two identical units have been fabricated with patterned gold electrodes on which a layer of GO was deposited by the drop-casting or spraying coating method. One unit was then covered by a layer of polydimethylsiloxane to modify its response to the temperature and humidity. Using this differential structure, the sensor shows great linearity in a temperature range from 20 °C to 60 °C and a humidity range from RH25% to RH95%. The humidity response of the two units varied for three orders of magnitude under the same temperature, which indicates a good sensitivity of the device. We have also found that the spray-coated sensor has a relatively short response and recovery times than the drop-casted one.
Autors: Xiaohui Leng;Weinan Li;Dan Luo;Fei Wang;
Appeared in: IEEE Sensors Journal
Publication date: Jul 2017, volume: 17, issue:14, pages: 4357 - 4364
Publisher: IEEE
 
» Digital 2-/3-Phase Switched-Capacitor Converter With Ripple Reduction and Efficiency Improvement
Abstract:
This paper presents a digitally controlled 2-/3-phase 6-ratio switched-capacitor (SC) dc-dc converter with low output voltage ripple and high efficiency. To achieve wide input and output voltage ranges, six voltage conversion ratios are generated with only two discrete flying capacitors by using both 2- and 3-phase operations. An adaptive ripple reduction scheme is proposed to achieve up to four times reduction in the output voltage ripple. The complexity of controller design is reduced by using digital synthesis, and the technique is scalable with process. Fast loop response is achieved by using synchronized hysteretic control. The SC converter was fabricated in a 0.13- CMOS process. It can deliver a maximum power of 250 mW to an output of 0.5–3 V with a wide input voltage range of 1.6–3.3 V. Compared to an SC converter with only 2-phase operation, the maximum efficiency improvement is 20%. The converter achieves a peak efficiency of 91%.
Autors: Junmin Jiang;Wing-Hung Ki;Yan Lu;
Appeared in: IEEE Journal of Solid-State Circuits
Publication date: Jul 2017, volume: 52, issue:7, pages: 1836 - 1848
Publisher: IEEE
 
» Digital Envelope Detection: The Good, the Bad, and the Ugly [Tips and Tricks]
Abstract:
During a recent consulting job to analyze acoustic telemetry signals transmitted by a deep-sea drill pipe, I was forced to investigate a process called digital envelope detection. This process is used to estimate the instantaneous magnitude of a zero-mean fluctuating-amplitude digital signal. While much tutorial information regarding envelope detection is available, that information is spread out over a number of communications textbooks and many websites. The purpose of this article is to collect and describe various digital envelope detection methods in one concise and consistent lesson.
Autors: Richard Lyons;
Appeared in: IEEE Signal Processing Magazine
Publication date: Jul 2017, volume: 34, issue:4, pages: 183 - 187
Publisher: IEEE
 
» Digital Event-Based Control for Nonlinear Systems Without the Limit of ISS
Abstract:
In this brief, the problem of event-triggered control (ETC) for nonlinear systems is considered. By using the perturbation theorem, event-triggering mechanisms (ETMs), not based on the framework of input to state stable, are proposed for a class of nonlinear systems with suitable exponentially converging threshold signals. Under mild conditions, the Zeno behavior of the ETC systems is excluded. Moreover, the presented ETMs ensure the solutions of the closed-loop ETC systems exponentially converging to the origin. The effectiveness of the proposed methods is shown by simulations.
Autors: Yong-Feng Gao;Rui Wang;Changyun Wen;Wei Wang;
Appeared in: IEEE Transactions on Circuits and Systems II: Express Briefs
Publication date: Jul 2017, volume: 64, issue:7, pages: 807 - 811
Publisher: IEEE
 
» Digital Multiplierless Realization of a Calcium-Based Plasticity Model
Abstract:
Calcium is a highly widespread and versatile intracellular ion that can control a wide range of temporal dynamics in the brain such as synaptic plasticity. This brief presents a novel and efficient digital circuit for implementing a calcium-based plasticity model aimed at reproducing relevant biological dynamics. Accordingly, we investigate the feasibility of the proposed model in a minimal neural network stressing on the effect of calcium oscillations on synaptic plasticity with various neuronal stimulation protocols. MATLAB simulations and physical implementations on field-programmable gate array confirm that the proposed model, with considerably low hardware overhead, can fairly mimic the relevant biological dynamics.
Autors: Ehsan Jokar;Hamid Soleimani;
Appeared in: IEEE Transactions on Circuits and Systems II: Express Briefs
Publication date: Jul 2017, volume: 64, issue:7, pages: 832 - 836
Publisher: IEEE
 
» Digital Predistortion of Single and Concurrent Dual-Band Radio Frequency GaN Amplifiers With Strong Nonlinear Memory Effects
Abstract:
Electrical anomalies due to trapping effects in gallium nitride (GaN) power amplifiers (PAs) give rise to long-term or strong memory effects. We propose novel models based on infinite impulse response fixed pole expansion techniques for the behavioral modeling and digital predistortion of single-input single-output (SISO) and concurrent dual-band GaN PAs. Experimental results show that the proposed models outperform the corresponding finite impulse response (FIR) models by up to 17 dB for the same number of model parameters. For the linearization of a SISO GaN PA, the proposed models give adjacent channel power ratios (ACPRs) that are 7–17 dB lower than the FIR models. For the concurrent dual-band case, the proposed models give ACPRs that are 9–14 dB lower than the FIR models.
Autors: Shoaib Amin;Peter Händel;Daniel Rönnow;
Appeared in: IEEE Transactions on Microwave Theory and Techniques
Publication date: Jul 2017, volume: 65, issue:7, pages: 2453 - 2464
Publisher: IEEE
 
» Digital psychiatry
Abstract:
Meanwhile, software on his phone has detected changes in Zach, including subtle differences in the language he uses, decreased activity levels, worsening sleep, and cutbacks in social activities. Unlike Zach, the software acts quickly, pushing him to answer a customized set of questions. Since he doesn’t have to get out of bed to do so, he doesn't mind.
Autors: John Torous;
Appeared in: IEEE Spectrum
Publication date: Jul 2017, volume: 54, issue:7, pages: 45 - 50
Publisher: IEEE
 
» Direct Quantile Regression for Nonparametric Probabilistic Forecasting of Wind Power Generation
Abstract:
The fluctuation and uncertainty of wind power generation bring severe challenges to secure and economic operation of power systems. Because wind power forecasting error is unavoidable, probabilistic forecasting becomes critical to accurately quantifying the uncertainty involved in traditional point forecasts of wind power and to providing meaningful information to conduct risk management in power system operation. This paper proposes a novel direct quantile regression approach to efficiently generate nonparametric probabilistic forecasting of wind power generation combining extreme learning machine and quantile regression. Quantiles with different proportions can be directly produced via an innovatively formulated linear programming optimization model, without dependency on point forecasts. Multistep probabilistic forecasting of 10-min wind power is newly carried out based on real wind farm data from Bornholm Island in Denmark. The superiority of the proposed approach is verified through comparisons with other well-established benchmarks. The proposed approach forms a new artificial neural network-based nonparametric forecasting framework for wind power with high efficiency, reliability, and flexibility, which can be beneficial to various decision-making activities in power systems.
Autors: Can Wan;Jin Lin;Jianhui Wang;Yonghua Song;Zhao Yang Dong;
Appeared in: IEEE Transactions on Power Systems
Publication date: Jul 2017, volume: 32, issue:4, pages: 2767 - 2778
Publisher: IEEE
 
» Dirty-Paper Coding Based Secure Transmission for Multiuser Downlink in Cellular Communication Systems
Abstract:
This paper studies the secure transmission in a multiuser broadcast channel where only the statistical channel state information of the eavesdropper is available. We propose to apply secret dirty-paper coding (S-DPC) in this scenario to support the secure transmission of one user and the normal (unclassified) transmission of the other users. By adopting the S-DPC and encoding the secret message in the first place, all the information-bearing signals of the normal transmission are treated as noise by potential eavesdroppers and thus provide secrecy for the secure transmission. In this way, the proposed approach exploits the intrinsic secrecy of multiuser broadcasting and can serve as an energy-efficient alternative to the traditional artificial noise (AN) scheme. To evaluate the secrecy performance of this approach and compare it with the AN scheme, we propose two S-DPC-based secure transmission schemes for maximizing the secrecy rate under constraints on the secrecy outage probability (SOP) and the normal transmission rates. The first scheme directly optimizes the covariance matrices of the transmit signals, and a novel approximation of the intractable SOP constraint is derived to facilitate the optimization. The second scheme combines zero-forcing dirty-paper coding and AN, and the optimization involves only power allocation. We establish efficient numerical algorithms to solve the optimization problems for both schemes. Theoretical and simulation results confirm that, in addition to supporting the normal transmission, the achievable secrecy rates of the proposed schemes can be close to that of the traditional AN scheme, which supports only the secure transmission of one user.
Autors: Bo Wang;Pengcheng Mu;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Jul 2017, volume: 66, issue:7, pages: 5947 - 5960
Publisher: IEEE
 
» Discovering Newsworthy Themes from Sequenced Data: A Step Towards Computational Journalism
Abstract:
Automatic discovery of newsworthy themes from sequenced data can relieve journalists from manually poring over a large amount of data in order to find interesting news. In this paper, we propose a novel -Sketch query that aims to find striking streaks to best summarize a subject. Our scoring function takes into account streak strikingness and streak coverage at the same time. We study the -Sketch query processing in both offline and online scenarios, and propose various streak-level pruning techniques to find striking candidates. Among those candidates, we then develop approximate methods to discover the most representative streaks with theoretical bounds. We conduct experiments on four real datasets, and the results demonstrate the efficiency and effectiveness of our proposed algorithms: the running time achieves up to 500 times speedup and the quality of the generated summaries is endorsed by the anonymous users from Amazon Mechanical Turk.
Autors: Qi Fan;Yuchen Li;Dongxiang Zhang;Kian-Lee Tan;
Appeared in: IEEE Transactions on Knowledge and Data Engineering
Publication date: Jul 2017, volume: 29, issue:7, pages: 1398 - 1411
Publisher: IEEE
 
» Discrete Wavelet Transform Method for High Flux $n-\gamma $ Discrimination With Liquid Scintillators
Abstract:
A Novel method based on discrete wavelet transform (DWT) for n– discrimination in high radiation flux is presented. We investigated the behavior of higher order wavelets from different families such as the Daubechies family, symlets, and coiflet type wavelets for pulse shape discrimination. A DWT-based average pulse analysis of neutron and -ray pulses suggests less sensitivity of db2, db3, sym4, and coif1 wavelets over the widely used Haar wavelet and the charge comparison method for the pile-up events. The DWT method with proposed wavelets is applied to a mixed radiation field at an energy threshold of 500 keVee obtained from an americium–beryllium source exposed to BC501 liquid scintillator which was coupled to a 12-b digital oscilloscope with sampling rate of 2.5 GSamples/s. The proposed wavelets require a short processing gate and are more suitable when applied to high count rate measurement with large fraction of pile-up events in the data set. Furthermore, these wavelets are very stable toward the variation in the width of processing gate in DWT. This feature is very helpful in the optimization of processing gate for the real-time applications.
Autors: Harleen Singh;Rohit Mehra;
Appeared in: IEEE Transactions on Nuclear Science
Publication date: Jul 2017, volume: 64, issue:7, pages: 1927 - 1933
Publisher: IEEE
 
» Dispersion Free 450-V p GaN-Gated CAVETs With Mg-ion Implanted Blocking Layer
Abstract:
In this letter, a GaN-based current aperture vertical electron transistor (CAVET) with a p-type gate layer and an implantation-based current blocking structure is presented. The devices measured showed a breakdown voltage of 450 V and no dispersion. The factors limiting higher breakdown voltages in these devices were carefully studied and discussed. The devices were grown on sapphire and relied on a box-shaped Mg implanted current blocking scheme. This is the first demonstration of an implantation-based CAVET, grown on sapphire blocking of 450 V with respectable on-state characteristics.
Autors: Saptarshi Mandal;Anchal Agarwal;Elaheh Ahmadi;K. Mahadeva Bhat;Dong Ji;Matthew A. Laurent;Stacia Keller;Srabanti Chowdhury;
Appeared in: IEEE Electron Device Letters
Publication date: Jul 2017, volume: 38, issue:7, pages: 933 - 936
Publisher: IEEE
 
» Distance Verification for Classical and Quantum LDPC Codes
Abstract:
The techniques of distance verification known for general linear codes are first applied to the quantum stabilizer codes. Then, these techniques are considered for classical and quantum (stabilizer) low-density-parity-check (LDPC) codes. New complexity bounds for distance verification with provable performance are derived using the average weight spectra of the ensembles of LDPC codes. These bounds are expressed in terms of the erasure-correcting capacity of the corresponding ensemble. We also present a new irreducible-cluster technique that can be applied to any LDPC code and takes advantage of parity-checks’ sparsity for both the classical and quantum LDPC codes. This technique reduces complexity exponents of all existing deterministic techniques designed for generic stabilizer codes with small relative distances, which also include all known families of the quantum stabilizer LDPC codes.
Autors: Ilya Dumer;Alexey A. Kovalev;Leonid P. Pryadko;
Appeared in: IEEE Transactions on Information Theory
Publication date: Jul 2017, volume: 63, issue:7, pages: 4675 - 4686
Publisher: IEEE
 
» Distortion of the Frequency Dependence of Bottom Attenuation $\alpha(f)$ Inverted From Modal Attenuation $\beta_{m}$ due to Bottom Model Mismatching
Abstract:
The geoacoustic (GA) parameters (sound speed , density , and attenuation ) of the bottom play crucial roles in broadband acoustical propagation in shallow water. In general, these parameters and their profiles are very hard to measure directly, especially the bottom attenuation at low frequencies. A common way to get these parameters is inverting them from the acoustical field data collected by a hydrophone array. Since the true bottom environment is not known, most inversions assume an approximate bottom model, such as a single layer or a half-space. It has been recognized that the “model mismatching” impact is an important issue to be investigated. This work will discuss the distortion of the frequency dependence of the bottom attenuation inverted from the modal attenuation due to the bottom model mismatching. It is found that if an inaccurate layered bottom model is used for the inversion the intrinsic dispersion character of GA parameters will be contaminated under the constraint of the forced data fitting. An analytic expression of the distortion factor is obtained using perturbation theory and numerical simulation examples are presented to show how the waveguide dispersion behavior is partially transferred to the intrinsic dispersion of the medium attenuation. A simple way is also suggested to compensate for the distortion factor.
Autors: Juan Zeng;Z. D. Zhao;Li Ma;E. C. Shang;
Appeared in: IEEE Journal of Oceanic Engineering
Publication date: Jul 2017, volume: 42, issue:3, pages: 672 - 680
Publisher: IEEE
 
» Distributed Consensus of Multiple Euler–Lagrange Systems Networked by Sampled-Data Information With Transmission Delays and Data Packet Dropouts
Abstract:
In this paper, the distributed consensus problem for a class of multiple Euler–Lagrange systems is solved. The considered issues are: 1) sampled-data information; 2) transmission delay; and 3) data packet dropouts. The considered mathematical models can describe a large number of practical systems in the actual engineering. In particular, all of the information exchanges are modeled by a sample-and-hold mechanism, which is more reliable and practical in applications. Moreover, this framework can deal with time-varying transmission delays and data packet dropouts by taking into account the limited communication capacity of information exchanges. By utilizing model transformation and applying the Lyapunov-Krasovskii functional method, sufficient conditions are first established with single-packet information exchanges to ensure that the networked Euler-Lagrange systems can achieve consensus under undirected communication topology. Then, the obtained results are further extended to the multiple-packet transmission case. Finally, an example of four two-link manipulators with time-varying transmission delays and data packet dropouts is addressed to verify the effectiveness and applicability of our theoretical results.Note to Practitioners—The motivation of this paper is to investigate a practical networking strategy for the cooperative control of multiple Euler–Lagrange systems that have been widely applied in modeling robotic manipulators, autonomous underwater vehicles, and spacecrafts. Existing approaches are mainly based on the continuous-time communication network, which are difficult to be implemented in the real-world applications. In addition, energy consumption problems for multi-agent systems have received increasing attention in recent years, which also motivate us to carry out the present study. Since continuous-time communications inevitably consume much energy, how to find an - ffective way to reduce energy cost is an urgent task. Therefore, this paper presents a novel method for communications among multiple Euler–Lagrange systems based on the sampled-data information, where discrete-time communications are used instead of continuous-time communications. Another advantage of the proposed method is that it can significantly reduce the transmission energy consumption. Furthermore, both transmission delays and data packet dropouts are taken into account which make our results more applicable in practice.
Autors: Xudong Zhao;Xiaolong Zheng;Chao Ma;Ren Li;
Appeared in: IEEE Transactions on Automation Science and Engineering
Publication date: Jul 2017, volume: 14, issue:3, pages: 1440 - 1450
Publisher: IEEE
 
» Distributed Continuous Event-Based Data Acquisition Using the IEEE 1588 Synchronization and FlexRIO FPGA
Abstract:
High-speed event driven acquisition is normally performed by analog-to-digital converter (ADC) boards with a given number of pretrigger sample and posttrigger sample that are recorded upon the occurrence of a hardware trigger. A direct physical connection is, therefore, required between the source of event (trigger) and the ADC, because any other software-based communication method would introduce a delay in triggering that would turn out to be not acceptable in many cases. This paper proposes a solution for the relaxation of the event communication time that can be, in this case, carried out by software messaging (e.g., via an LAN), provided that the system components are synchronized in time using the IEEE 1588 synchronization mechanism. The information about the exact event occurrence time is contained in the software packet that is sent to communicate the event and is used by the ADC FPGA to identify the exact sample in the ADC sample queue. The length of the ADC sample queue will depend on the maximum delay in software event message communication time. A prototype implementation using a National FlexRIO FPGA board connected with an ADC device is presented as the proof of concept.
Autors: C. Taliercio;A. Luchetta;G. Manduchi;A. Rigoni;
Appeared in: IEEE Transactions on Nuclear Science
Publication date: Jul 2017, volume: 64, issue:7, pages: 1970 - 1974
Publisher: IEEE
 
» Distributed Coordinated Tracking Control for a Class of Uncertain Multiagent Systems
Abstract:
This technical note studies the distributed coordinated tracking control for multiagent systems with model uncertainties. Both unknown model parameters and unknown system dynamics are considered. It is assumed that there exist parametric uncertainties and unknown dynamics with the informed agent as well, and only the state value of the informed agent can be accessed by a limited number of agents. With the utilization of neural network approximation and adaptive estimation, a new distributed adaptive tracking control is proposed to make all agents cooperatively follow the desired trajectory specified by the informed agent. The control design is first presented for the first-order multiagent systems, and then extension is made to the second-order multiagent systems using backstepping. A unique feature of the proposed control is that the unknown bounds of neural network approximation errors are also estimated online. Using Lyapunov stability theorem, it is rigorously proved that asymptotically cooperative tracking can be achieved under the assumption that the sensing/communication topology among agents is connected. Simulation results are included to illustrate the proposed control.
Autors: Jing Wang;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Jul 2017, volume: 62, issue:7, pages: 3423 - 3429
Publisher: IEEE
 
» Distributed Decode–Forward for Relay Networks
Abstract:
A new coding scheme for general -node relay networks is presented for unicast, multicast, and broadcast. The proposed distributed decode–forward scheme combines and generalizes Marton coding for single-hop broadcast channels and the Cover–El Gamal partial decode–forward coding scheme for three-node relay channels. The key idea of the scheme is to precode all the codewords of the entire network at the source by multicoding over multiple blocks. This encoding step allows these codewords to carry partial information of the messages implicitly without complicated rate splitting and routing. This partial information is then recovered at the relay nodes and forwarded further. For -node Gaussian unicast, multicast, and broadcast relay networks, the scheme achieves within bits from the cutset bound, and thus from the capacity (region), regardless of the network topology, channel gains, or power constraints. Roughly speaking, distributed decode–forward is dual to noisy network coding, which generalized compress–forward to unicast, multicast, and multiple access relay networks.
Autors: Sung Hoon Lim;Kwang Taik Kim;Young-Han Kim;
Appeared in: IEEE Transactions on Information Theory
Publication date: Jul 2017, volume: 63, issue:7, pages: 4103 - 4118
Publisher: IEEE
 
» Distributed Energy Resources Topology Identification via Graphical Modeling
Abstract:
Distributed energy resources (DERs), such as photovoltaic, wind, and gas generators, are connected to the grid more than ever before, which introduces tremendous changes in the distribution grid. Due to these changes, it is important to understand where these DERs are connected in order to sustainably operate the distribution grid. But the exact distribution system topology is difficult to obtain due to frequent distribution grid reconfigurations and insufficient knowledge about new components. In this paper, we propose a methodology that utilizes new data from sensor-equipped DER devices to obtain the distribution grid topology. Specifically, a graphical model is presented to describe the probabilistic relationship among different voltage measurements. With power flow analysis, a mutual information-based identification algorithm is proposed to deal with tree and partially meshed networks. Simulation results show highly accurate connectivity identification in the IEEE standard distribution test systems and Electric Power Research Institute test systems.
Autors: Yang Weng;Yizheng Liao;Ram Rajagopal;
Appeared in: IEEE Transactions on Power Systems
Publication date: Jul 2017, volume: 32, issue:4, pages: 2682 - 2694
Publisher: IEEE
 
» Distributed Finite-Element Kalman Filter for Field Estimation
Abstract:
The paper deals with decentralized state estimation for spatially distributed systems described by linear partial differential equations from discrete in-space-and-time noisy measurements provided by sensors deployed over the spatial domain of interest. A fully scalable approach is pursued by decomposing the domain into possibly overlapping subdomains assigned to different processing nodes interconnected to form a network. Each node runs a local finite-dimensional discrete-time Kalman filter which exploits the finite element approach for spatial discretization, a backward Euler method for time-discretization and the parallel Schwarz method to iteratively enforce continuity of the field predictions over the boundaries of adjacent subdomains. Numerical stability of the adopted approximation scheme and stability of the proposed distributed finite element Kalman filter are mathematically proved. The effectiveness of the proposed approach is then demonstrated via simulation experiments concerning the estimation of a bi-dimensional temperature field.
Autors: Giorgio Battistelli;Luigi Chisci;Nicola Forti;Giuseppe Pelosi;Stefano Selleri;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Jul 2017, volume: 62, issue:7, pages: 3309 - 3322
Publisher: IEEE
 
» Distributed Generalized Spatial Modulation Based on Chinese Remainder Theorem
Abstract:
In this letter, we divide distributed antennas into several transmit antenna groups (TAGs), and extend the generalized spatial modulation (GSM) idea to a new distributed multiple-input multiple-output system, which is so called as a distributed GSM (DGSM) system. The spare antenna combinations in the component TAGs are exploited to increase the transmission rate of DGSM. To reduce the complexity of the optimal maximum-likelihood (ML) detector, a low-complexity Chinese remainder theorem-based ML (CRT-ML) detector is also derived. Simulation results show that the proposed CRT-ML detector performs similar to the optimal ML detector.
Autors: Xue-Qin Jiang;Miaowen Wen;Jun Li;Wei Duan;
Appeared in: IEEE Communications Letters
Publication date: Jul 2017, volume: 21, issue:7, pages: 1501 - 1504
Publisher: IEEE
 
» Distributed Guidance for Interception by Using Multiple Rotary-Wing Unmanned Aerial Vehicles
Abstract:
A distributed guidance law is proposed to intercept multiple intruding targets by using multiple rotary-wing unmanned aerial vehicles (UAVs). The proposed distributed guidance law is based on the integration of the classic parallel navigation and a velocity feedback. Direction-based potential functions are applied to avoid inter-agent collisions and mis-interceptions. It is proved that, with the proposed distributed guidance law, each UAV is capable of intercepting its specific target within finite time and with nonzero hitting velocity, and there exist neither inter-agent collisions nor mis-interceptions. Task allocation strategies are proposed to allocate targets to UAVs for optimal time efficiency. Theoretical results are illustrated by simulations and a semi-physical experiment.
Autors: Bing Zhu;Abdul Hanif Bin Zaini;Lihua Xie;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: Jul 2017, volume: 64, issue:7, pages: 5648 - 5656
Publisher: IEEE
 
» Distributed Intermittent Connectivity Control of Mobile Robot Networks
Abstract:
In this paper we develop an intermittent communication framework for teams of mobile robots. Robots move along the edges of a mobility graph and communicate only when they meet at the vertices of this graph, giving rise to a dynamic communication network. We design distributed controllers for the robots that determine meeting times at the nodes of the mobility graph so that connectivity of the communication network is ensured over time, infinitely often. We show that this requirement can be captured by a global Linear Temporal Logic (LTL) formula that forces robots to meet infinitely often at the meeting points. To generate motion plans that satisfy the LTL expression, we propose a novel technique that approximately decomposes the global LTL formula into local LTL formulas and assigns them to the robots. Since the approximate decomposition of the LTL formula can result in conflicting robot behaviors, we develop a distributed conflict resolution scheme that generates conflict-free motion plans that satisfy the global LTL expression. By appropriately introducing delays in the execution of the generated motion plans we show that the proposed controllers can be executed asynchronously.
Autors: Yiannis Kantaros;Michael M. Zavlanos;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Jul 2017, volume: 62, issue:7, pages: 3109 - 3121
Publisher: IEEE
 
» Distributed Mining of Contrast Patterns
Abstract:
In this paper we propose a novel algorithm for mining contrast patterns using a distributed, map-reduce like framework. Contrast patterns describe differences between contrasted data sets and have previously been used for building highly accurate classifiers. However, mining for contrast patterns is a computationally expensive task and existing algorithms are designed to run in a sequential manner on a single machine. Consequently, existing approaches are unable to handle dense, high volume and high dimensional databases. Our algorithm addresses this problem by partitioning the search-space for contrast patterns into small, independent units. These units can be mined in parallel, providing a scalable solution for mining large data sets. Using three different real-world data sets we test an implementation of our algorithm on a Spark cluster. Results of these tests indicate that our algorithm achieves a high-degree of parallelism and scalability.
Autors: David Savage;Xiuzhen Zhang;Pauline Chou;Xinghou Yu;Qingmai Wang;
Appeared in: IEEE Transactions on Parallel and Distributed Systems
Publication date: Jul 2017, volume: 28, issue:7, pages: 1881 - 1890
Publisher: IEEE
 
» Distributed Optimization for Linear Multiagent Systems: Edge- and Node-Based Adaptive Designs
Abstract:
This paper studies the distributed optimization problem for continuous-time multiagent systems with general linear dynamics. The objective is to cooperatively optimize a team performance function formed by a sum of convex local objective functions. Each agent utilizes only local interaction and the gradient of its own local objective function. To achieve the cooperative goal, a couple of fully distributed optimal algorithms are designed. First, an edge-based adaptive algorithm is developed for linear multiagent systems with a class of convex local objective functions. Then, a node-based adaptive algorithm is constructed to solve the distributed optimization problem for a class of agents satisfying the bounded-input bounded-state stable property. Sufficient conditions are given to ensure that all agents reach a consensus while minimizing the team performance function. Finally, numerical examples are provided to illustrate the theoretical results.
Autors: Yu Zhao;Yongfang Liu;Guanghui Wen;Guanrong Chen;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Jul 2017, volume: 62, issue:7, pages: 3602 - 3609
Publisher: IEEE
 
» Distributed Pinning Droop Control in Isolated AC Microgrids
Abstract:
This paper presents a distributed pinning droop control mechanism for accurate active and reactive power sharing in isolated converter-fed microgrids (MG). Under this framework, both power converters and loads in the MG are treated as agents in a multiagent system (MAS). Since only a fraction of the agents in the network have access to critical information, the required communication bandwidth and control cost can be significantly reduced without degrading the dynamical performance of the power sharing compared to consensus-based droop control techniques. Theoretical studies of this pinning-based distributed droop control, including pinning localization, grid partition, and convergence criteria, will be explored in detail. In order to validate the feasibility and the correctness of the proposed distributed droop control method, an MAS platform is developed for a test-bed MG system in Taiwan. Simulation tests under normal conditions, loading conditions, and plug-in and plug-out scenarios are investigated in MATLAB/Simulink and the Java Agent Development Framework. Simulation results demonstrate that the proposed pinning-based distributed droop control can indeed improve autonomous operations of an isolated ac MG.
Autors: Nelson Fabian Avila;Chia-Chi Chu;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Jul 2017, volume: 53, issue:4, pages: 3237 - 3249
Publisher: IEEE
 
» Distributed Power-Generation Systems and Protection
Abstract:
Continuously expanding deployments of distributed power-generation systems (DPGSs) are transforming the conventional centralized power grid into a mixed distributed electrical network. The modern power grid requires flexible energy utilization but presents challenges in the case of a high penetration degree of renewable energy, among which wind and solar photovoltaics are typical sources. The integration level of the DPGS into the grid plays a critical role in developing sustainable and resilient power systems, especially with highly intermittent renewable energy resources. To address the challenging issues and, more importantly, to leverage the energy generation, stringent demands from both utility operators and consumers have been imposed on the DPGS. Furthermore, as the core of energy conversion, numerous power electronic converters employing advanced control techniques have been developed for the DPGS to consolidate the integration. In light of the above, this paper reviews the power-conversion and control technologies used for DPGSs. The impacts of the DPGS on the distributed grid are also examined, and more importantly, strategies for enhancing the connection and protection of the DPGS are discussed.
Autors: Frede Blaabjerg;Yongheng Yang;Dongsheng Yang;Xiongfei Wang;
Appeared in: Proceedings of the IEEE
Publication date: Jul 2017, volume: 105, issue:7, pages: 1311 - 1331
Publisher: IEEE
 
» Distributed Stochastic MPC of Linear Systems With Additive Uncertainty and Coupled Probabilistic Constraints
Abstract:
This technical note develops a new form of distributed stochastic model predictive control (DSMPC) algorithm for a group of linear stochastic subsystems subject to additive uncertainty and coupled probabilistic constraints. We provide an appropriate way to design the DSMPC algorithm by extending a centralized SMPC (CSMPC) scheme. To achieve the satisfaction of coupled probabilistic constraints in a distributed manner, only one subsystem is permitted to optimize at each time step. In addition, by making explicit use of the probabilistic distribution of the uncertainties, probabilistic constraints are converted into a set of deterministic constraints for the predictions of nominal models. The distributed controller can achieve recursive feasibility and ensure closed-loop stability for any choice of update sequence. Numerical examples illustrate the efficacy of the algorithm.
Autors: Li Dai;Yuanqing Xia;Yulong Gao;Mark Cannon;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Jul 2017, volume: 62, issue:7, pages: 3474 - 3481
Publisher: IEEE
 
» Distributed Synchronization on Weakly Connected Networks
Abstract:
Distributed synchronization for wireless networks is based on the mutual exchange of the same chirp-signature by nodes. Collisions of these signatures drive the system toward time and (carrier) frequency synchronization using distributed consensus algorithms. This letter investigates the convergence and the asymptotic distortion properties on noisy networks when neighboring clusters of nodes are weakly connected to each other only through a subset of nodes and bridging links. These heavily connected clusters act as macroagents, and the consensus properties of the ensemble depend on the number of bridge links between them. The convergence rate and mean square synchronization deviation are derived as functions of the number of bridge links for different examples of weakly connected noisy networks via the analytic calculation of Laplacian spectra. Our approach facilitates the study of network topology optimization for distributed synchronization.
Autors: Stojan Denic;Orestis Georgiou;Umberto Spagnolini;
Appeared in: IEEE Communications Letters
Publication date: Jul 2017, volume: 21, issue:7, pages: 1577 - 1580
Publisher: IEEE
 
» Distributed Time-Varying Quadratic Optimization for Multiple Agents Under Undirected Graphs
Abstract:
This paper considers a class of distributed quadratic optimization problem under an undirected and connected graph. Different from most of the existing distributed optimization works that consider the optimal solutions to be constants, the optimal solution and the objective functions at the optimal solution are both assumed to be time varying. For the case where there is no constraint on the decision variables, gradient-based searching methods are proposed to track the unknown optimal solution. The tracking errors are proven to be asymptotically stable. For the case where there exists a local compact convex constraint set for each agent, projected gradient-based methods are proposed for both neighboring coupled and generally coupled objective functions, and the tracking errors are proven to be uniformly ultimately bounded with arbitrarily small bound.
Autors: Chao Sun;Maojiao Ye;Guoqiang Hu;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Jul 2017, volume: 62, issue:7, pages: 3687 - 3694
Publisher: IEEE
 
» Distributed Tracking Control of an Interconnected Leader–Follower Multiagent System
Abstract:
In the existing control problems for the leader–follower multiagent systems, the leader's dynamics are independent of the followers. In this paper, we consider a tracking control problem for an interconnected leader–follower multiagent system, where the leader's dynamics are interconnected with the states of the followers. It is shown that such a problem can be used to model the autonomous power sharing problem of grid-connected microgrids. In order to solve this problem, a distributed control law using only local information is synthesized. Simulation results are provided to show the effectiveness of the proposed control law.
Autors: He Cai;Guoqiang Hu;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Jul 2017, volume: 62, issue:7, pages: 3494 - 3501
Publisher: IEEE
 
» Distribution Load Capability With Nodal Power Factor Constraints
Abstract:
Unity power factor (PF) injections through distributed grid-tie inverters reduce net real power demand at distribution substations. This reduces line utilization, but can also result in undesirable PFs within the system. PF constraints, therefore, may limit injection or “load” capability (LC) in circuits with growing distributed resource penetration. Therefore, this work presents a PF-based estimator of LC for distribution systems, which can be appended to existing LC formulations without additional inputs. A solution algorithm is provided, and simulation results are presented for an actual 2556-node distribution system. An increase in distributed photovoltaic injections resulted in reduction of overall system LC due to substation PF constraints. Finally, series acceleration is investigated for LC problems; in the tested cases, the acceleration technique reduced the number of iterations for a current-based LC estimator by an average of 85%.
Autors: Nicholas S. Coleman;Karen N. Miu;
Appeared in: IEEE Transactions on Power Systems
Publication date: Jul 2017, volume: 32, issue:4, pages: 3120 - 3126
Publisher: IEEE
 
» Diurnal Scale Controls on C-Band Microwave Backscatter From Snow-Covered First-Year Sea Ice During the Transition From Late Winter to Early Melt
Abstract:
Diurnal observations of coincident in situ physical-, electrical-, and surface-based C-band microwave scattering properties of a 16-cm saline snow cover on smooth, moderately saline, first-year sea ice are presented for the transition period between late winter and early melt. Statistical regression analysis and backscatter modeling are employed to explore the scattering mechanisms within the snowpack and to assess associations between backscatter and snow properties for both periods. Our results demonstrate substantial variation in both measured snow properties and C-band microwave backscatter over the diurnal cycle during the late winter period when the difference between maximum and minimum air and snow surface temperature was approximately 5 °C. No such variation in snow properties and backscatter occurred for the early melt period when our case study exhibited a small diurnal variation (~1°C) in air and snow surface temperature. Statistical and modeled results show significant association between the microwave backscatter and snow properties for the top 8 cm of the snowpack. Basal snow properties do not contribute toward total backscatter in either case. As a result, we are certain that the sea ice surface was a negligible scattering interface during both cases. Correlations between backscatter and snow properties are incidence angle dependent, demonstrating the highest association at 50°. Diurnal backscatter from RADARSAT-2 synthetic aperture radar acquisitions support the influence of varying diurnal snow properties on C-band backscatter, showing a difference of ~4 dB for and during the late winter period. This differenc- is reduced to <1 dB for the early melt period.
Autors: John J. Yackel;Jagvijay P. S. Gill;Torsten Geldsetzer;Mark Christopher Fuller;Vishnu Nandan;
Appeared in: IEEE Transactions on Geoscience and Remote Sensing
Publication date: Jul 2017, volume: 55, issue:7, pages: 3860 - 3874
Publisher: IEEE
 
» Diversity Pulse Shaped Transmission in Ultra-Dense Small Cell Networks
Abstract:
In ultra-dense small cell networks, spatial multiplexing gain is a challenge because of the different propagation conditions. The channels associated with different transmit–receive pairs can be highly correlated due to the: 1) high probability of line-of-sight (LOS) communication between user equipment (UE) and base station (BS) and 2) insufficient spacing between antenna elements at both UE and BS. In this paper, we propose a novel transmission technique titled Diversity Pulse Shaped Transmission (DPST), to enhance the throughput over the correlated multiple-input multiple-output (MIMO) channels in an ultra-dense small cell network. The fundamental of DPST is to shape transmit signals at adjacent antennas with distinct interpolating filters, introducing pulse shaping diversity. In DPST, each antenna transmits its own data stream with a relative deterministic time offset—which must be a fraction of the symbol period—with respect to the adjacent antenna. The delay is interpolated with the pulse shaped signal generating a virtual MIMO channel that benefits from increased diversity from the receiver perspective. To extract the diversity, the receiver must operate in an oversampled domain, and hence, a fractionally spaced equalizer (FSE) is proposed. The joint impact of DPST and FSE helps the receiver to sense a less correlated channel, eventually enhancing the UE's throughput. Moreover, in order to minimize the spatial correlation, we aim to optimize the deterministic fractional delay. Simulation results show that applying DPST to a correlated channel can approximately enhance the UE throughput by 1.93 and 3.76 in and ${\text{4}}\,\times \,{\text{4}}$ MIMO systems, respectively.
Autors: Amir H. Jafari;Vijay Venkateswaran;David López-Pérez;Jie Zhang;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Jul 2017, volume: 66, issue:7, pages: 5866 - 5878
Publisher: IEEE
 
» Dose Rate Linearity in 4H-SiC Schottky Diode-Based Detectors at Elevated Temperatures
Abstract:
The outstanding material properties make silicon carbide radiation hard and this ability has enabled it to be demonstrated in a range of detector structures for deployment in extreme environments, including those where the ability to tolerate high radiation dose is imperative. This includes applications in space and nuclear environments, where the ability to detect highly energetic radiation is important. In contrast, detectors used in medical treatment, such as imaging and radiotherapy, use a range of radiation dose rates and energies for both particulate and photonic radiation. Here, we report the response and dose rate linearity of detectors fabricated from silicon carbide to dose rates in the range of 0.185 mGy min−1, typical of those used for medical imaging. The data show that the radiation detected current originates within the depletion region of the detector and that the response is linearly dependent on the volume of the space charge region. The realization of a vertical detector structure, coupled with the high quality of epitaxial layers, has resulted in a high dose sensitivity of the detector that is highly linear. The temperature dependence of the characteristics indicates that silicon carbide Schottky diode-based detectors offer a performance suitable for medical applications at temperatures below 100 °C without the need for external cooling.
Autors: N. S. Mohamed;N. G. Wright;A. B. Horsfall;
Appeared in: IEEE Transactions on Nuclear Science
Publication date: Jul 2017, volume: 64, issue:7, pages: 1912 - 1919
Publisher: IEEE
 

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