Abstract: A transparent polycrystalline diamond field-effect transistor (FET) was fabricated and measured in room temperature measurements, which reveals comparatively high maximum current density and high breakdown voltage of more than 1000 V. A harsh stress environment is proposed for simple and time-effective reliability stress measurement of the FET using a method of 50 continuous cycles of 500-V voltage stress. A 400-nm-thick Al2O3 counter-destructive passivation layer was implemented on the FET for the stress measurements. Devices with wide gate–drain length () retain their FET characteristics after the harsh stress measurements by only 50% reductions maximum current density.
Autors: Mohd Syamsul;Yuya Kitabayashi;Takuya Kudo;Daisuke Matsumura;Hiroshi Kawarada;
Abstract: Effect of silicon technology limitations, including transistor nonidealities, layout parasitics, and low-quality factor on-chip passive components on millimeter wave stacked switching power amplifiers operating at the -band frequencies (75–110 GHz), is presented in this paper. To mitigate the performance degradation in output power and PAE arising from such causes, high-breakdown voltage, high- multiport stacked-transistor topologies are proposed for realizing power amplifiers with high output power and high efficiency at 75–110 GHz. A 90-nm silicon germanium (SiGe) BiCMOS process is used to propose active structures comprising of two and three stacked transistors with integrated layout parasitics that achieve and breakdown voltage of 295 GHz and 8 V and 260 GHz and 11 V, respectively. Functionality of such multiport transistor topologies is demonstrated in proof-of-concept implementations, including a five-stage two-stacked switching power amplifier (PA) that achieves peak output power and PAE of 22 dBm and 19% at 85 GHz, and a six-stage three-stacked PA that achieves peak output power and PAE of 23.3 dBm and 17% at 83 GHz, respectively. For comparison with conventional switching PA designs using native transistor footprints, a five-stage -band nonstacked Class-E amplifiers is also fabricated in the same 90-nm SiGe BiCMOS process with output power and PAE of 19.5 dBm and 16% at 88 GHz. The superior performance of output power and PAE in designs using the multiport transistor topologies highlights the benefit of the proposed approach.
Abstract: A novel poly-Si reconfigurable device with a programmable bottom-gate (BG) array is demonstrated for the first time. The BG has non-volatile memory functionality. This device is very efficient in terms of device size and functionality. By changing the bias or program/erase state of the BGs, a device can be transformed to a certain device type among -/-MOSFETs, and - and - diodes. The threshold voltage () and contact resistance () of MOSFETs can be controlled independently by the BGs. The subthreshold swings for -/-MOSFETs are 200 and 230 mV/decade, respectively. The s of the -/-MOSFETs measured from a single reconfigurable device are more than , which are comparable to those of conventional poly-Si devices.
Autors: Jun-Mo Park;Jong-Ho Bae;Jai-Ho Eum;Sung Hun Jin;Byung-Gook Park;Jong-Ho Lee;
Abstract: This paper presents a new approach for the design of high-gain and wide-bandwidth planar antenna arrays. It is based on the coupling matrix theory which allows the design of the arrays using all-resonator structures. The parameters of the matrix offer the flexibility of achieving a controllable bandwidth. They also introduce a frequency filtering functionality into the arrays which can remove the need to place a bandpass filter after the arrays at the very front end of a communication system. The new approach has been applied to using novel topologies to form two wideband planar antenna arrays utilizing rectangular waveguide cavity resonators operated at X-band frequencies. The first topology is seventh order and based on 39 resonators configured in two waveguide-layers; that is one layer for the feed resonators and one layer for the radiating resonators. The second topology is fourth order based on 25 resonators configured only in a single waveguide-layer. Fabrication and measurements have been performed, showing very good agreement with the simulations.
Autors: Rashad H. Mahmud;Michael J. Lancaster;
Appeared in: IEEE Transactions on Antennas and Propagation
Abstract: In this letter, we have proposed a novel AlGaN/GaN FinFET featuring T-shaped gate and extremely linearity of transconductance characteristics (. The formation of AlGaN/GaN nano-fins only in the gate opening region is enabled by a developed fabrication process, which is simple and well compatible with the conventional one. When normalized to effective channel width, the fabricated FinFET delivers a 1.45 times higher current density and a 1.66 times higher output power density as high as 11.3 W/mm at 8 GHz compared with the planar HEMTs, along with clearly improved linearity characteristics thanks to a flatter response afforded by much lower source access resistance. To the best of our knowledge, this is the first demonstration of superior power performance of high-linearity GaN FinFETs, indicating significant advantages of tri-gate configuration over planar HEMTs for microwave power applications.
Autors: Kai Zhang;Yuechan Kong;Guangrun Zhu;Jianjun Zhou;Xinxin Yu;Cen Kong;Zhonghui Li;Tangsheng Chen;
Abstract: We report high performance, orientation-controlled, and locally back-gated black phosphorus (BP) n-MOSFETs and p-MOSFETs with titanium and permalloy contacts, respectively. Devices with channel length ranging from 0.3 to are analyzed. Armchair-oriented BP p-MOSFETs (n-MOSFETs) display 3.5 times (1.5 times) higher maximum current compared with zigzag devices. Saturated transconductance values up to 4.8 times (1.6 times) higher for BP p-MOSFETs (n-MOSFETs) oriented along the armchair direction compared with the zigzag direction are observed. Using this orientation control and contact engineering, n-MOSFETs with transconductance of and p-MOSFETs with contact resistance as low as 0.31 are demonstrated.
Autors: Nazila Haratipour;Seon Namgung;Roberto Grassi;Tony Low;Sang-Hyun Oh;Steven J. Koester;
Abstract: Ternary logic is a promising alternative to the conventional binary logic in VLSI design as it provides the advantages of reduced interconnects, higher operating speeds, and smaller chip area. This paper presents a pair of circuits for implementing a ternary half adder using carbon nanotube field-effect transistors. The proposed designs combine both futuristic ternary and conventional binary logic design approach. One of the proposed circuits for ternary to binary decoder simplifies further circuit implementation and provides excellent delay and power advantages in data path circuit such as adder. These circuits have been extensively simulated using HSPICE to obtain power, delay, and power delay product. The circuit performances are compared with alternative designs reported in recent literature. One of the proposed ternary adders has been demonstrated power, power delay product improvement up to 63% and 66% respectively, with lesser transistor count. So, the use of these half adders in complex arithmetic circuits will be advantageous.
Abstract: In this paper, one proposed an effective method to enhance current drivability of junctionless FETs (JL-FETs) by utilizing uniaxial tensile strain effects. The strained layers were deposited on JL-FETs on silicon-on-insulator (SOI) and bulk Si wafers, respectively. Strained JL SOI FETs show an extremely low subthreshold swing (S.S.) of 65 mV/decade with ; strained JL bulk FinFETs show an S.S. of 75 mV/decade with . For strained JL bulk FinFETs, a triangular fin shape could suppress leakage current effectively. Regardless of substrates, JL FETs showed excellent performance owing to uniaxial tensile strain technology. Analysis of leakage current in strained JL FETs included effects on Gate-induced drain leakage trap-assisted tunneling effects were discussed by – curves under various temperatures and activation energy. Compared with JL SOI gate-all-around structures, JL bulk FinFET possesses higher and offer the promise of higher integration flexibility for Si CMOS compatible process for the future applications.
Abstract: We present a novel optical feeding technique to achieve efficient excitation of an ultrawideband-connected array (CA) antenna. The passive fiber optic feed allows for preservation of the theoretical bandwidth and low profile of elementary connected dipole elements. In order to improve effective radiated power, high-power charge compensated modified unitravelling carrier photodiodes are integrated into an antenna array for the first time. Circuit and full-wave simulations, which include all required antenna and feed components, are conducted for the optimization of the array's performance. A 9 × 12 element CA is populated with a 1-D array of four photodiode-integrated active elements to demonstrate the concept. The optically fed array is confirmed experimentally to have a 3-dB bandwidth of approximately 7–17 GHz, in good agreement with simulations.
Autors: Matthew R. Konkol;Dylan D. Ross;Shouyuan Shi;Charles E. Harrity;Andrew A. Wright;Christopher A. Schuetz;Dennis W. Prather;
Abstract: This paper presents an investigation of terahertz (THz) wave generation by optical rectification of a Gaussian laser pulse propagating in plasma having periodic density perturbation in the presence of an externally applied static magnetic field in the axial direction. The nonuniform intensity of laser pulse leads to the generation of quasi-static ponderomotive force. The electrons acquire nonlinear oscillatory velocity under the influence of the force. This velocity, on coupling with the density perturbation, induces a nonlinear current density in the radial direction. This nonlinear current density drives a wave, the frequency of which depends on the pulse duration of the laser. The frequency falls in the THz range if the pulse duration of the laser is chosen thoughtfully. For the resonant excitation of the radiation, phase matching is required, which is provided by the periodic density perturbation. Axially applied external magnetic field can be utilized as a controlling parameter to enhance the nonlinear coupling and the yield of the generated wave. The effect of the axial magnetic field on the generated THz intensity is investigated. Variations in THz radiation intensity as functions of the density ripple amplitude and background plasma density have also been studied.
Abstract: This paper presents novel structures of planar microwave sensors for detecting and characterizing the dielectric properties in common solid materials which produce high Q-factors with capability to suppress undesired harmonic spurious. These sensors are based on novel planar symmetrical split ring resonator with spurlines filters by employing the perturbation theory, in which the dielectric properties of the resonator affect the Q-factor and resonance frequency. The proposed sensors achieve narrow resonance with low insertion loss and high-Q and sensitivity which peaked up to 652 at 2.22 GHz operating frequency. By using a specific experimental methodology, practical materials are applied as standards (Roger 5880, Roger 4350, FR4) to validate the sensitivity of the sensors for permitting potentially material characterization and detection. Accordingly, the mathematical equation is derived to extract the materials with unknown properties. The average accuracy percentage of the measured results for all cases of the designed sensors is found within 97%–98% compared with those in the literature for the same tested standard materials. It is believed that these sensors would lead for a promising solution of characterizing material particularly in determining material properties and quality, such as in food industry, bio-sensing medicine applications, and therapeutics goods detections.
Autors: Rammah Ali Alahnomi;Zahriladha Zakaria;Eliyana Ruslan;Siti Rosmaniza Ab Rashid;Amyrul Azuan Mohd Bahar;
Abstract: A high-quality and stable electron device of aligned gold nanogap arrays is demonstrated by using a well-controlled method with electron beam lithography and focused ion beam. Sub-30-nm nanogap arrays could be precisely fabricated with reproducibility. Field emission (FE) properties of the nanogaps are directly measured in the vacuum chamber of scanning electron microscopy with a nanomanipulator. Experimental investigation and calculations are carried out to reveal the transition process from the leakage current to the FE. Importantly, the controllable method could allow us to readily construct varying nanospacings. Besides, we also illustrate the independence of emission current on the vacuum degree over a large range, widening the applied range of the devices. These studies clearly demonstrate that electronic devices with sub-30-nm vacuum channel can be readily achieved by coupling varying nanogaps into nanostructures. It may pave the way for exploring the physics in tunneling transport devices, and therefore enable a new generation of high-performance, high-speed and low-cost electronic devices.
Autors: Ji Xu;Qilong Wang;Zhi Tao;Yusheng Zhai;Chen Guangdian;Zhiyang Qi;Xiaobing Zhang;
Appeared in: IEEE Transactions on Electron Devices
Abstract: Surface acoustic wave (SAW) resonators are used for a broad range of wireless sensing applications, some of them having high demands on the resolution as well as the measurement update rate. This paper presents a new interrogation method for precise and fast frequency determination of passive SAW resonators based on instantaneous frequency measurement by a low-cost six-port interferometer. Using a delay line, the frequency measurement is reduced to a phase measurement that can be instantaneously evaluated by the six-port network. No complex signal processing is necessary providing high update rates and low hardware costs. An in-depth analysis of the system concept and its building blocks is presented, and the advantages as well as the limitations are discussed and compared with the current state of the art. Finally, a demonstrator in the 2.4-GHz frequency band shows the feasibility and the precision of the concept with measurement times of only a few microseconds.
Abstract: In this paper, the improved asymptotic solutions of eigenmodes (leaky and Berenger modes) are provided for a circular waveguide terminated by a perfectly matched layer. Furthermore, a systematic asymptotic approach is developed by the inverse power series. Numerical simulations demonstrate that the high-precision asymptotic eigenmodes can be obtained.
Abstract: In this paper, we consider the problem of multi-dimensional dynamic texture analysis, and we introduce a new higher order linear dynamical system (h-LDS) descriptor. The proposed h-LDS descriptor is based on the higher order decomposition of the multidimensional image data and enables the analysis of dynamic textures by using information from various image elements. In addition, we propose a methodology for its application to video-based early warning systems that focus on smoke identification. More specifically, the proposed methodology enables the representation of video subsequences as histograms of h-LDS descriptors produced by the smoke candidate image patches in each subsequence. Finally, to further improve the classification accuracy, we propose the combination of multidimensional dynamic texture analysis with the spatiotemporal modeling of smoke by using a particle swarm optimization approach. The ability of the h-LDS to analyze the dynamic texture information is evaluated through a multivariate comparison against the standard LDS descriptor. The experimental results that use two video datasets have shown the great potential of the proposed smoke detection method.
Abstract: Low-gain and narrow bandwidth problems are associated with patch antennas, and due to their inverse relation with each other, these problems cannot be improved simultaneously. It is well understood that the patch antenna excited at the higher order modes (HOMs) can overcome the problems of low gain and narrow bandwidth, provided that the modes are excited properly. For a given geometry, all the resonant frequencies are related in fixed ratios, providing no flexibility for the designer. Furthermore, high side lobe levels and undesirable radiation patterns are associated with the higher order modes. The excitation of higher order modes in given dimensions of the patch is achieved by surface modification and loading of slots on the patch. Two antennas based on a novel design procedure are discussed in the Ku and Ka bands to validate the proposed facts. The antenna in the Ka band has a peak gain of 8.5 dBi with 15.14% of bandwidth, while the one in the Ku band has a peak gain of 11.84 dBi with 17.6% of bandwidth. The design procedure is particularly important in designing antennas for applications like mobile satellite communication, wideband and multimedia applications, collision avoidance systems in vehicles, etc.
Autors: Qasim Umar Khan;Mojeeb Bin Ihsan;Dilaawaiz Fazal;Fahad Mumtaz Malik;Shahzad Amin Sheikh;Muhammad Salman;
Appeared in: IEEE Transactions on Vehicular Technology
Abstract: A simple D-shaped photonic crystal fiber (PCF)-based surface plasmon resonance (SPR) biosensor is proposed for refractive index sensing in visible to near infrared (IR) region. A thin Titanium di-oxide (TiO2) layer is used as an adhesive layer to strongly attach the plasmonic gold (Au) layer with silica fiber surface. TiO2 also helps to tune the operating sensor wavelength from visible to near IR (550–1770-nm wavelength). Finite-element method has been used to investigate the guiding properties. The proposed sensor shows the maximum wavelength interrogation sensitivity of 46 000 nm/RIU and the average sensitivity of 9,800 nm/RIU in the sensing range of 1.33–1.43. It also shows the maximum amplitude sensitivity of 1,086 RIU. Using the wavelength and amplitude interrogation methods, proposed sensor gives the theoretical maximum resolution of 2.2 and 9.2 RIU, respectively. To the best of our knowledge, it has the highest sensitivity and sensor resolution among the reported PCF SPR sensors. The proposed D-shaped PCF has been fabricated following the standard stack-and-draw method to show the feasibility of the proposed sensor. Due to the promising results over the broad range of analyte RI, it would be an excellent candidate for the detection of biomolecules, organic chemicals, chemical, and other analytes.
Autors: Ahmmed A. Rifat;Rajib Ahmed;G. Amouzad Mahdiraji;F. R. Mahamd Adikan;
Abstract: A novel highly sensitive optical fiber twist sensor based on a Lyot filter is proposed and experimentally demonstrated in this paper. The evolution of the transmission spectra of the Lyot filter with respect to twist, temperature, and strain are investigated, respectively. The amplitude of the resonance dip changes as a sine-like function with the twist angle varying, which agrees well with the theoretical analysis. Based on analyzing the amplitude response of the resonance dip, the sensitivities of the sensor with respect to twist, temperature, and strain are found to be −15.586 dB/rad, 0.003 dB/°C, and −0.001 dB/μϵ, indicating the viability of implementing a temperature- and strain-independent twist sensor based on a Lyot filter.
Abstract: This brief introduces a highly configurable ultrawideband triangular wave baseband pulse generator designed in 40-nm complementary metal–oxide–semiconductor technology. The baseband pulse width is adjustable between 660 ps and 3.8 ns. An extra amplitude compensation loop is implemented to prevent amplitude changes when the pulse width varies. The amplitude variations are limited to 13% compared with the maximum amplitude over the entire pulse width range. The amplitude compensation loop allows a pulse amplitude tuning range between 280 and 640 mV, whereas the pulse width only varies 80 ps over this entire range. The pulse generator has a maximum simulated signal-to-noise ratio of 59 dB and a measured maximum power consumption of 6.2 pJ/pulse from a 0.9-V power supply and a 100-MHz pulse repetition frequency.
Autors: B. Faes;P. Reynaert;P. Leroux;
Appeared in: IEEE Transactions on Circuits and Systems II: Express Briefs
Abstract: In both new and aging military and civilian aircraft, all critical power wiring has been typically protected against overheating by using combinations of thermal and magnetic circuit breakers or solid-state power controllers (SSPCs). However, the conventional types of these protective devices do not detect and react to hazardous arcing faults, and it is important that they do so to mitigate the risk of aircraft fires caused by aging, damaged insulation, wire chafing, wire breakage, chemical exposure, maintenance procedures, and contamination. Most aircraft electrical systems operate at 115 Vac, 400 Hz, both single and three phase. In addition to this ac power, they utilize 28 Vdc. Hazardous arcing faults can occur in all these power systems between parallel conductors, to ground, or in series (due to a broken or frayed wire or at a loose connection).
Abstract: Light-field imaging and holographic imaging are currently the two mostly investigated 3-D imaging technologies because of their potentials to create the viewing environment conforming to a natural viewing condition. The basic optical geometries for image display in these imaging are not different from that of integral photography. The images in the two type of imaging are a set of different view images. These images are arranged as a 2-D point image array, and each point image is expanded with a certain angle to form a viewing zone. The differences between the two types of imaging are the number of point images in the array and the physical entities forming the images. Holographic imaging has many more point images than light-field imaging, and each image in the array consists of coherent right rays from different positions of an object. In light-field imaging, an array of pixels represents a direction view of the object. Despite these differences, they share the same goal of providing a continuous parallax to viewers and require display panels of almost the same characteristics. It is expected that in the future these two imaging techniques will be integrated into the same flat panel along with the plane image.
Abstract: Electroluminescence microscopy and spectroscopy are used to compare the average hot-electron concentration and temperature under radio frequency (RF) operation class A, class B, and class F modes. From the results obtained, class A results, on average, in the highest hot-electron concentration, while class F is the mode with the lowest concentration due to its “L”-shaped load line. The electron temperature extracted from the electroluminescence spectra is reduced with increasing RF power, reflecting the dominance of electroluminescence from the portion of the load line in the semi-on region. The electroluminescence method is not able to give substantial information on the portion of the load line with high field and low current density which will be responsible for the potentially damaging hottest electrons present in the channel.
Autors: Tommaso Brazzini;Michael A. Casbon;Michael J. Uren;Paul J. Tasker;Helmut Jung;Hervé Blanck;Martin Kuball;
Appeared in: IEEE Transactions on Electron Devices
Abstract: The abundance of processing power is changing the nature of software engineering. By reducing the cost of failure, abundance changes how developers use computing technologies. Also, abundance changes the developer's role by moving the focus from technology to management. This article also contains an erratum. In "App Store 2.0: From Crowdsourced Information to Actionable Feedback in Mobile Ecosystems" (DOI: 10.1109/MS.2017.46) from the Mar./Apr. 2017 issue, in the fifth line of the second column on p. 83, "see sia" should be "see Figure 2a."
Abstract: Scholars and practitioners have recently shifted their attention from traditional closed internal innovation to open innovation (OI). Building on both the resource-based view and the network perspective, we explore the roles of three types of informal ties (i.e., business, government, and university) in driving inbound and outbound OI, and further examine such effects contingent on market dynamism. Empirical results from our study of 260 Chinese firms show that all three types of informal ties positively affect inbound innovation openness, whereas only business ties facilitate outbound innovation openness. In addition, market dynamism strengthens the relationship between university ties and inbound innovation openness, but weakens the effect of business ties on inbound innovation openness. These findings indicate the salience of informal ties in increasing innovation openness and the contingent role of external market conditions. The findings contribute to the understanding of the drivers of innovation openness, and help clarify the differences between inbound and outbound OI.
Abstract: In this paper, we study the impact of aliased out-of-band (OOB) interference signals on the information sum rate of the maximum ratio combining receiver in massive multiple-input multiple-output (MIMO) uplink, with both perfect and imperfect channel estimates, in order to determine the required out-of-band attenuation in radio-frequency (RF) bandpass filters (BPFs). With imperfect channel estimates, our study reveals that as the number of base-station (BS) antennas ( ) increases, the required attenuation at the BPFs increases as with , provided the desired information sum rate (both in the presence and in the absence of aliased OOB interferers) remains fixed. This implies a practical limit on the number of BS antennas due to the increase in BPF design complexity and power consumption with increasing .
Autors: Sudarshan Mukherjee;Saif Khan Mohammed;
Appeared in: IEEE Transactions on Vehicular Technology
Abstract: Hull structure monitoring is needed to provide healthy suggestions for a ship. Inertial Measurement Units (IMUs) are available for this application. By installing IMUs on different points of the ship hull, the angular velocity and acceleration of each point can be measured. Once the hull flexure changes, the movement parameters of those points will be different, and the hull flexure can be estimated through matching these parameters by a Kalman filter. We deduced proper measurement equations of the Kalman filter, which is essential for the flexure estimation, and designed real data and simulation data experiments to verify the equation. Results showed that the hull structure can be effectively monitored by the proposed method.
Abstract: We propose to classify human activities based on transmission coefficient () and reflection coefficient () of on-body antennas with deep convolutional neural networks (DCNNs). It is shown that spectrograms of and exhibit unique time-varying signatures for different body motion activities that can be used for classification purposes. DCNN, a deep learning approach, is applied to spectrograms to learn the necessary features and classification boundaries. It is found that DCNN can achieve classification accuracies of 98.8% using and 97.1% using . The effects of operating frequency and antenna location on the accuracy have been investigated.
Autors: Youngwook Kim;Yang Li;
Appeared in: IEEE Transactions on Antennas and Propagation
Abstract: Security Operation Centers (SOCs) are being operated by universities, government agencies, and corporations to defend their enterprise networks and identify and thwart malicious behaviors in both networks and hosts. The success of a SOC depends on combining good tools and processes with efficient and effective analysts. During four years of anthropological fieldwork methods to study SOCs, the authors discovered that successful SOC innovations must resolve multiple internal and external conflicts to be effective and efficient. This discovery, guided by activity theory (AT) as a framework for analyzing the fieldwork data, enabled them understand these realities. Their research indicates conflict resolution is a prerequisite for continuous improvement of SOCs in both human and technological aspects. Failure to do so can lead to adverse effects, such as analyst burnout and reduction in overall effectiveness.
Abstract: We propose a hybrid precoding design for spatial multiplexing in millimeter wave massive multiple-input multiple-output systems. The proposed design relies on the popular orthogonal matching pursuit (OMP) algorithm. The OMP algorithm uses necessary columns of the right/left (for receiver/transmitter) unitary matrix of the channel (obtained via a singular value decomposition) to obtain the initial baseband (digital) precoder using principles of basis pursuit. The resulting baseband precoder is then used to refine the RF (analog) precoder. This iterative refinement improves the quality of hybrid preocders. Quantization of the RF and baseband precoding matrices is also discussed for limited feedback systems, where the high-dimensional RF precoder is quantized using codebooks generated using the means clustering algorithm. On the other hand, the low-dimensional baseband precoder is quantized using well-known Grassmannian codebooks. Simulation results show that the proposed scheme performs close to the fully digital precoding scheme.
Autors: Jawad Mirza;Bakhtiar Ali;Syed Saud Naqvi;Saqib Saleem;
Abstract: This paper investigates artificial noise (AN) injection along the temporal and spatial dimensions of a legitimate system to secure its transmissions from potential eavesdropping. In particular, we consider a multiple-input multiple-output (MIMO) orthogonal frequency-division multiplexing (OFDM) system in the presence of a multiple-antenna passive eavesdropper and characterize both the secrecy rate and average secrecy rate of the legitimate system. We assume that the legitimate transmitter knows the full channel state information (CSI) of the links connecting it with its legitimate receiver but does not know the instantaneous CSI of the passive eavesdropper. Closed-form expressions for the secrecy rate and average secrecy rate are derived for the asymptotic case of a large number of transmit antennas. We compare the degrading effects of spatial and temporal AN on the eavesdropper's rate. We also investigate the power allocation between the data and the AN and the power allocation between the spatial and the temporal AN. An upper bound on the secrecy rate loss due to the presence of the eavesdropper is also derived, and computer simulations are carried out to demonstrate the performance of our proposed AN scheme.
Autors: Ahmed El Shafie;Zhiguo Ding;Naofal Al-Dhahir;
Appeared in: IEEE Transactions on Vehicular Technology
Abstract: A Software Product Line (SPL) is defined as a set of software systems that share a common and managed set of features satisfying specific needs of a particular market segment or domain . The SPL offers a number of common artifacts for building products, including mandatory and variable elements. SPL approaches have been adopted by many software companies1 to ease reuse and reduce time and production costs. A feature represents a functionality that is visible to the user and can be designed as a variability, which represents a variable functionality that may or may not be present in a product. On the other hand, mandatory features are common to all SPL products. To facilitate feature management, most SPL methodologies use the Feature Model (FM)  to represent all the SPL variabilities and commonalities.
Autors: Thiago N. Ferreira;Jackson A. Prado Lima;Andrei Strickler;Josiel N. Kuk;Silvia R. Vergilio;Aurora Pozo;
Appeared in: IEEE Computational Intelligence Magazine
Abstract: Automatic computation of surface correspondence via harmonic map is an active research field in computer vision, computer graphics and computational geometry. It may help document and understand physical and biological phenomena and also has broad applications in biometrics, medical imaging and motion capture industries. Although numerous studies have been devoted to harmonic map research, limited progress has been made to compute a diffeomorphic harmonic map on general topology surfaces with landmark constraints. This work conquers this problem by changing the Riemannian metric on the target surface to a hyperbolic metric so that the harmonic mapping is guaranteed to be a diffeomorphism under landmark constraints. The computational algorithms are based on Ricci flow and nonlinear heat diffusion methods. The approach is general and robust. We employ our algorithm to study the constrained surface registration problem which applies to both computer vision and medical imaging applications. Experimental results demonstrate that, by changing the Riemannian metric, the registrations are always diffeomorphic and achieve relatively high performance when evaluated with some popular surface registration evaluation standards.
Abstract: The fusion of hyperspectral imaging (HSI) sensor and airborne lidar scanner (ALS) data provides promising potential for applications in environmental sciences. Standard fusion approaches use reflectance information from the HSI and distance measurements from the ALS to increase data dimensionality and geometric accuracy. However, the potential for data fusion based on the respective intensity information of the complementary active and passive sensor systems is high and not yet fully exploited. Here, an approach for the rigorous illumination correction of HSI data, based on the radiometric cross-calibrated return intensity information of ALS data, is presented. The cross calibration utilizes a ray tracing-based fusion of both sensor measurements by intersecting their particular beam shapes. The developed method is capable of compensating for the drawbacks of passive HSI systems, such as cast and cloud shadowing effects, illumination changes over time, across track illumination, and partly anisotropy effects. During processing, spatial and temporal differences in illumination patterns are detected and corrected over the entire HSI wavelength domain. The improvement in the classification accuracy of urban and vegetation surfaces demonstrates the benefit and potential of the proposed HSI illumination correction. The presented approach is the first step toward the rigorous in-flight fusion of passive and active system characteristics, enabling new capabilities for a variety of applications.
Autors: Maximilian Brell;Karl Segl;Luis Guanter;Bodo Bookhagen;
Appeared in: IEEE Transactions on Geoscience and Remote Sensing
Abstract: Hyperspectral image (HSI) classification has become an active research area in the remote sensing field. In order to construct a simple and reliable classifier, learning an adequate distance metric from a given HSI dataset is still a critical and challenging task in many HSI applications. In this paper, a novel distance metric learning (DML) framework based on 1-D manifold embedding (1DME), named DL1DME, is proposed for HSI classification. The 1DME framework was developed by using the recently developed smooth ordering technique. This framework enables us to elaborately exploit the benefits of DML in the development of the 1DME algorithm. The core of the state-of-the-art DML is to learn a Mahalanobis matrix from the given dataset that better describes the similarity between pixels. Largest margin nearest neighbors (LMNN) and information theoretic metric learning (ITML) are employed for the Mahalanobis matrix learning. Then, based on the affinity defined by the Mahalanobis matrix, the preclassifiers are constructed using the simple 1-D regularization on 1DME; and they predict the labels of the test data. By a voting rule, the pixels labeled in the same class by most of the preclassifiers are voted into the confidently predicted set, which are then merged with the current labeled set. The labeled set enlargement process is repeated if the original one has a very small size. The final classifier is then constructed in the 1DME framework again, but based on the enlarged labeled set. According to the aforementioned strategy, two novel DML-based 1DME classification algorithms, DL1DME-LMNN and DL1DME-ITML, are developed in this paper. Experimental results on three popular real-world HSIs demonstrate that the classification performance of the proposed DL1DME is superior to other most popular SSL methods in terms of classification accuracies.
Autors: Huiwu Luo;Yuan Yan Tang;Yulong Wang;Jianzhong Wang;Robert P. Biuk-Aghai;Jianjia Pan;Runzong Liu;Lina Yang;
Appeared in: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Abstract: Hyperspectral image superresolution is a highly attractive topic in computer vision and has attracted many researchers’ attention. However, nearly all the existing methods assume that multiple observations of the same scene are required with the observed low-resolution hyperspectral image. This limits the application of superresolution. In this paper, we propose a new framework to enhance the resolution of hyperspectral images by exploiting the knowledge from natural images: The relationship between low/high-resolution images is the same as that between low/high-resolution hyperspectral images. In the proposed framework, the mapping between low- and high-resolution images can be learned by deep convolutional neural network and be transferred to hyperspectral image by borrowing the idea of transfer learning. In addition, to study the spectral characteristic between low- and high-resolution hyperspectral image, collaborative nonnegative matrix factorization (CNMF) is proposed to enforce collaborations between the low- and high-resolution hyperspectral images, which encourages the estimated solution to extract the same endmembers with low-resolution hyperspectral image. The experimental results on ground based and remote sensing data suggest that the proposed method achieves comparable performance without requiring any auxiliary images of the same scene.
Autors: Yuan Yuan;Xiangtao Zheng;Xiaoqiang Lu;
Appeared in: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Abstract: Traditional web-based Question and Answer (Q&A) websites cannot easily solve non-factual questions to match askers’ preference. Recent research efforts begin to study social-based Q&A systems that rely on an asker's social friends to provide answers. However, this method cannot find answerers for a question not belonging to the asker's interests. To solve this problem, we propose a distributed Q&A system incorporating both social community intelligence and global collective intelligence, named as iASK. iASK improves the response latency and answer quality in both the social domain and global domain. It uses a neural network based friend ranking method to identify answerer candidates by considering social closeness and Q&A activities. To efficiently identify answerers in the global user base, iASK builds a virtual server tree that embeds the hierarchical structure of interests, and also maps users to the tree based on user interests. To accurately locate the cooperative experts, iASK has a fine-grained reputation system to evaluate user reputation based on their cooperativeness and expertise, and uses a reputation based reward strategy to encourage users to be cooperative. To further improve the performance of iASK, we propose a weak tie assisted social based potential answerer location algorithm and an interest coefficient based uncategorized question forwarding algorithm. To further improve the response quality and cooperativeness, we propose a reputation based reward strategy that motivates users to answer questions from unknown users. Experimental results from large-scale trace-driven simulation and real-world daily usages of the iASK prototype show the superior performance of iASK. It achieves high answer quality with 24 percent higher accuracy, short response latency with 53 percent less delay and effective cooperative incentives with 16 percent more answers compared to other social-based Q&A systems. Th-
results also show the effectiveness of the enhancement algorithms in improving the performance of iASK.
Autors: Guoxin Liu;Haiying Shen;
Appeared in: IEEE Transactions on Parallel and Distributed Systems
Abstract: This study introduces an individualized tool for identifying mammogram interpretation errors, called eye-Computer Assisted Perception (iCAP). iCAP consists of two modules, one which processes areas marked by radiologists as suspicious for cancer and classifies these as False Positive (FP) or True Positive (TP) decisions, while the second module classifies fixated but not marked locations as False Negative (FN) or True-Negative (TN) decisions. iCAP relies on both radiologists’ gaze-related parameters, extracted from eye tracking data, and image-based features. In order to evaluate iCAP, eye tracking data from eight breast radiologists reading 120 two-view digital mammograms were collected. Fifty-nine cases had biopsy proven cancer. For each radiologist, a user-specific support vector machine model was built to classify the radiologist’ s reported areas as TPs or FPs and fixated locations as TNs or FNs. The performances of the classifiers were evaluated by utilizing leave-one-out cross validation. iCAP was tested retrospectively in a simulated scenario in which it was assumed that the radiologists would accept all iCAP decisions. Using iCAP led to an average increase of 12%±6% in the number of correctly localized cancer and an average decrease of 44.5%±22.7% in the number of FPs per image.
Autors: Ziba Gandomkar;Kevin Tay;Will Ryder;Patrick C. Brennan;Claudia Mello-Thoms;
Abstract: Innovation is not a trivial process and ideas are the raw material of this process. Oriented systems to idea management domain seek to identify and develop effective and efficient ideas. However, there are challenges such as information overload with ideas submissions peaks and trivial description of collecting ideas, thereby making the process of selection and identification of relevant ideas. By using clustering techniques can bring together groups of like-minded and easy viewing of information. The objective of this study is to present an ontology-based model and cluster analysis to support the Idea Management, to contribute in the decision making process. The demonstration of feasibility of the proposed model was through the development of a prototype. The prototype was used in both study scenarios using ideas collected on the websites of Starbucks® and Dell® companies. It was found that when analyzing groups of similar ideas, patterns and trends can be highlighted. As a result presents a model to assist in decision making and in the process of identification and selection of ideas for implementation.
Autors: Marina Carradore Sergio;Joao Artur de Souza;Alexandre Leopoldo Goncalves;
Abstract: In this paper, an application of the theoretical algebraic notion of a separable ring extension in the realm of cyclic convolutional codes or, more generally, ideal codes, is investigated. It is worked under very mild conditions that cover all previously known as well as new non-trivial examples. It is proved that ideal codes are direct summands, as left ideals, of the underlying non-commutative algebra, in analogy with cyclic block codes. This implies, in particular, that they are generated by a non-commutative idempotent polynomial. Hence, by using a suitable separability element, an efficient algorithm for computing one of such idempotents is designed. We show that such an idempotent generator polynomial can be used to get information on the free distance of the convolutional code.
Autors: José Gómez-Torrecillas;F. J. Lobillo;Gabriel Navarro;
Appeared in: IEEE Transactions on Information Theory
Abstract: In this paper, a new identification and control scheme using multitime scale recurrent high-order neural networks is proposed to control the singularly perturbed nonlinear systems with uncertainties. First, a novel identification scheme using modified optimal bounded ellipsoid based weight's updating laws is developed to identify the unknown nonlinear systems. By adding two additional terms to the original optimal bounded ellipsoid based weight's updating laws, the new modified identification scheme can achieve high convergence speed due to the adaptively adjusted learning gain at the beginning of the identification process and remain effective during the whole identification process. Based on the identified model, a new indirect adaptive control scheme for trajectory tracking problem using singular perturbation theory is developed, which is different from the control scheme proposed previously that can only be applied to a regulation problem. The closed-loop stability is analyzed and the convergence of system states is guaranteed. Experimental results are presented to demonstrate the effectiveness of the identification and control scheme.
Abstract: A discrete-time output error (OE) model identification method is proposed for industrial integrating processes with time delay, to facilitate the discrete-time controller design and implementation in sampled systems. By subtly introducing a differential filter to the input excitation, an open-loop identification test can be performed for such a process while complying with the output limit. Correspondingly, the parameter estimation is equivalently transformed to identify a stable type OE model with time delay. A recursive identification algorithm is developed to simultaneously estimate all the model parameters including the integer delay, and a linear interpolation of the input excitation is given for the recursive computation to guarantee consistent estimation. The convergence of parameter estimation is analyzed with a proof. An illustrative example is used to demonstrate the effectiveness of the proposed method.
Autors: Tao Liu;Shijian Dong;Fengwei Chen;Dewei Li;
Appeared in: IEEE Transactions on Automatic Control
Abstract: This paper proposes an identification method for induction motor parameters at standstill using integral calculations. The rotor time constant and magnetizing inductance are identified. During the identification process, the induction motor to be tested is consistently excited according to a predetermined current reference. Using the predetermined current, the induction motor emulates the rated rotor flux and the rated slip condition, even at standstill. This method is based on an integral calculation so that the results are robust to measurement noise. Based on these features, the identification result of the proposed method is quite accurate, and the method shows excellent repeatability. Due to the simplicity of the proposed technique, this method can be easily applied to commercial inverter products. Simulation and experimental results confirm the effectiveness of the proposed method.
Abstract: The number and locations of transmission lines that are likely to get simultaneously congested are useful information for analysis of power market. In this paper, we present a study that demonstrates the number of simultaneously congested transmission lines is very limited, as well as an algorithm for identifying a small set of transmission lines that may become simultaneously congested based on the current states of the system and market. To this end, we first investigate the maximum number of simultaneously congested lines. Then, a novel algorithm is developed to identify a smaller set using two scientific criteria – one is concerned with the absolute impact of generation dispatch decisions, and the other, the relative sensitivities of line flows with respect to the changes of generation outputs. The effectiveness of the proposed algorithm is demonstrated through two simulation studies, one based on IEEE 39-bus for illustration of concepts, and the other based on a large-scale, real-world power system for showing the practical application and significance of results.
Autors: Milad Javadi;Mingguo Hong;Ruth N. Angarita;Seyed Hossein Hosseini;John Ning Jiang;
Abstract: This work presents a simple method for obtaining the main parameters, such as the torque constant and the d - and q-axis inductances and , for a brushless internal permanent magnet motor by measuring the machine torque during testing. These tests are relatively simple to carry out compared with other test procedures described in the literature, and they neither require sophisticated and expensive test equipment nor are they affected by temperature effects as happens with other techniques. The machine under test is supplied through a dc supply at different rotor positions. The shaft torque is measured through a torque sensor during the tests. The test current magnitude is varied to take care of the saturation effects. From the measured torque data and known rotor position, the required parameters can be obtained. Tests performed on two different internal permanent magnet machines confirm the validity and effectiveness of the proposed method.
Autors: Shafiq Ahmed Odhano;Radu Bojoi;Eric Armando;Guilherme Homrich;Aly Ferreira Flores Filho;Mircea Popescu;David George Dorrell;
Appeared in: IEEE Transactions on Industry Applications
Abstract: Hardware-based image processing offers speed and convenience not found in software-centric approaches. Here, we show theoretically that a 2-D periodic array of dipole-coupled elliptical nanomagnets, delineated on a piezoelectric substrate, can act as a dynamical system for specific image processing functions. Each nanomagnet has two stable magnetization states that encode pixel color (black or white). An image containing black and white pixels is first converted to voltage states and then mapped into the magnetization states of a nanomagnet array with magneto-tunneling junctions (MTJs). The same MTJs are employed to read out the processed pixel colors later. Dipole interaction between the nanomagnets implements specific image processing tasks, such as noise reduction and edge enhancement detection. These functions are triggered by applying a global strain to the nanomagnets with a voltage dropped across the piezoelectric substrate. An image containing an arbitrary number of black and white pixels can be processed in few nanoseconds with very low energy cost.
Abstract: Using 3-D technology computer aided design simulation, we investigated the impact of equivalent oxide thickness (EOT) on threshold voltage () variation induced by work-function variation (WFV) in multigate devices. The WFV-induced variation in multigate devices does not significantly vary with the dielectric constant of the gate dielectric material, but increases with decreasing physical oxide thickness (). As becomes thinner, electric field tends to be locally concentrated, causing a large variation of electrostatic potential in channel. The slope of the ratio of average grain size to gate area (RGG) plot is observed with various oxide thicknesses. It is confirmed that we can alleviate the WFV-induced variation without significant performance degradation if gate dielectric layer becomes thicker with appropriately adopted higher-k engineering. In addition, the impact of EOT (including interface layer) on the WFV-induced variation is studied.
Autors: Youngtaek Lee;Changhwan Shin;
Appeared in: IEEE Transactions on Electron Devices
Abstract: We report on investigation of the mechanical properties of paper electronics (printed and made out of paper). One key objective of such paper electronics is to achieve ultraflexibility. Therefore, it is important to understand electrical functionality and reliability of paper electronics under various physical (mechanical) deformations. Here, we show the general mechanical properties of the cellulose paper used and its electrical behavior under applied strain, tackling the main effects that need to be identified when building paper-based systems, from product performance and stability perspective. An overview of the stress–strain behavior of silver ink on paper is discussed, and then, we tackle a more specific analysis of the performance variations of paper sensors made with recyclable household materials when exposed to various mechanical conditions of tensile and compressive bending. This paper is important for developing stable wearable sensors for incorporation into Internet of Everything applications.
Autors: Joanna M. Nassar;Muhammad M. Hussain;
Appeared in: IEEE Transactions on Electron Devices
Abstract: This letter presents the optimum value of skin-electrode capacitance for a capacitive electromyography (CEMG) biosensor design. Skin-electrode capacitance is proved to be an important variable when defining the input characteristic of a capacitive biosensor by an electrical model of skin–electrode interface. The experimental results show that a CEMG biosensor with the skin-electrode capacitance range of between 255 and 340 pF yields the best performance, low noise, and is small in size.
Abstract: To measure the nonlinear impedance of interdigital electrode-solution system, a novel method based on free damped oscillation is proposed. A high valued active inductance with adjustable negative resistance is constructed by an operational amplifier. A second order oscillation system for measurement is then set up by connecting the active inductance with the device under test. The active inductance is designed to be around 470H to meet the measurement requirements of low frequency. The negative resistor is utilized to adjust damping coefficient of the oscillation system in order to obtain enough number of ring-down oscillation cycles for parameter estimation. The free damped oscillation signal of the oscillation system is obtained under square wave voltage excitation. After processed by Hilbert transform, the instantaneous capacitance and resistance can be calculated simultaneously to implement nonlinear impedance measurement. The operational availability of the proposed method is verified by experimental results of commercial available resistors and capacitors. The impedance nonlinearity of a gold interdigital electrode immersed in KCl solutions of different concentration is tested and compared with that obtained by sweep-amplitude sinusoidal excitation methods. The results indicate that the proposed method can successfully obtain impedance nonlinearity in half of the square wave period.
Abstract: Electromagnetic induction coils are widely used in a variety of applications, many of them safety-critical. The insulation around the wire in an electromagnetic coil accounts for a significant portion of the failures in solenoid-operated valves and in electric motors. This paper presents a method of detecting the degradation of insulation used in low-voltage applications by assessing changes in impedance responses. The results indicate that coil impedance, resolved into resistance and reactance, evolves differently when the coil is subjected to different loading conditions, which reflects insulation degradation signatures due to different failure mechanisms. This method can be used to assess the insulation life of an electromagnetic coil, allowing replacement prior to the formation of harmful shorts or critical coil opens.
Autors: Noel Jordan Jameson;Michael H. Azarian;Michael Pecht;
Appeared in: IEEE Transactions on Industrial Electronics
Abstract: In this paper, an online empirical mode decomposition (EMD) based algorithm is proposed for the control of a shunt active filter (AF). Standard EMD algorithm has worked on the principle of time-scale difference between the upper maximum values and lower minimum values of a signal, and for a long time it has been considered good for offline analysis of signals. This paper deals with the real-time application of EMD for the control of AF under balanced and unbalanced loads. Linear interpolators are employed for construction of upper and lower envelopes to avoid computation complexity. Moreover, customized iterative computations for extraction of intrinsic mode functions maintain the efficiency of algorithm. The algorithm extracts the fundamental component of load current and helps in estimating reference currents. Simulations are performed on MATLAB/Simulink platforms. Simulation results are verified with experimental results of a developed prototype of shunt AF.
Abstract: Controllers based on Synchronous Finite State Machines (SFSM) are widely used in the control unit design of complex digital systems. These systems can present serious problems related to the global clock. In this context, the asynchronous paradigm shows interesting features that fit as an alternative for the design, despite of the difficulties of the application of asynchronous logic. An interesting architecture for the Asynchronous Finite State Machines (AFSM) is based on local clock, because it reduces the requirements of asynchronous logic. This manuscript proposes a novel architecture of local clock for AFSMs, which is described by a popular specification known as Extended Burst-Mode (XBM). This architecture presents a better latency time when compared with other local clock architectures. Furthermore, the manuscript proposes a “necessary and sufficient” condition for local clock AFSMs to be synthesized completely on the proposed architecture by using only conventional tools. Through a case study, we present the architecture, its robustness, the synthesis procedure and a comparison with other local clock architectures, highlighting its advantages.
Autors: Felipe Tuyama De Faria Barbosa;Duarte Lopes De Oliveira;Tiago S. Curtinhas;Lester de Abreu Faria;Jocemar Francisco De Souza Luciano;
Appeared in: IEEE Transactions on Circuits and Systems I: Regular Papers
Abstract: Software-defined radio (SDR) platforms represent a compelling solution for low-cost, flexible, dual-polarized radar systems. However, the phase coherency requirements of a dual-polarized radar system between the transmit ports and between the receive ports as well as between transmission and reception, are difficult to attain in popular SDRs. In this paper, we provide high-level overviews of SDR radar systems, dual-polarization radars, and system phase calibration procedures found in literature. The method adopted to achieve coherency involves a manual calibration procedure, which is applied to four dual-polarized radar system configurations designed around commercial off-the-shelf SDR platforms. The implemented, calibrated designs were exercised in a laboratory setting to determine the coherence performance of the SDR-based radar architectures in characterizing a fixed target’s full-polarization scattering matrix.
Autors: Jeremy Hershberger;Thomas Pratt;Robert Kossler;
Appeared in: IEEE Transactions on Microwave Theory and Techniques
Abstract: This paper proposes an improved analytical model for the study of steady-state performance of droop-controlled VSC-MTDC systems. When power disturbances occur, such as those imposed by normal changes in power settings and converter outages, the powers of the converters with droop control may hit their limits and hence such converters no longer contribute to power sharing, which should be paid special attention when analyzing the impacts of power disturbances on the performance of multi-terminal HVDC (MTDC) systems. Based on the bisection algorithm and superposition principle, the proposed analytical model provides an easy way to estimate the results of power distributions, dc voltage deviations, and power loss variations of the MTDC system taking converter outage and converter overload into account. Simulations of a modified New England 39-bus system incorporating a four-terminal MTDC system are carried out for validating the proposed analytical model.
Abstract: Caching at the network edge has emerged as a viable solution for alleviating the severe capacity crunch in modern content centric wireless networks by leveraging network load-balancing in the form of localized content storage and delivery. In this paper, we consider a cache-aided network, where the cache storage phase is assisted by a central server and users can demand multiple files at each transmission interval. To service these demands, we consider two delivery models: 1) centralized content delivery, where user demands at each transmission interval are serviced by the central server via multicast transmissions; and 2) device-to-device assisted distributed delivery, where users multicast to each other in order to service file demands. For such cache-aided networks, we present new results on the fundamental cache storage versus transmission rate tradeoff. Specifically, we develop a new technique for characterizing information theoretic lower bounds on the storage-rate tradeoff and show that the new lower bounds are strictly tighter than cut-set bounds from literature. Furthermore, using the new lower bounds, we improve the constant factor approximation of the optimal storage-rate tradeoff for cache-aided systems under both delivery models.
Abstract: This paper reports further investigation on a recently proposed -plane and -plane loaded slow-wave structure (SWS) for terahertz traveling-wave tube (TWT) amplifier. An improved input–output coupler is designed to enable easy fabrication by microfabrication technology, UV-lithography, electroplating, and molding (LIGA), and deep reactive-ion etching. The coupler shows very low reflection coefficient, dB over a frequency range 360–450 GHz. To improve the beam-wave interaction and enhance the saturated output power of the TWT, the SWS with tapered design is implemented. By tuning the period, the wave is resynchronized with the beam at the end of the SWS, resulting in more than 60% increase in the saturated output power across the 80-GHz bandwidth. In addition, the sensitivity of the output power of the TWT to the fabrication tolerance of the individual geometrical parameters is also studied in detail. It is found that the output power reduces by 80% for approximately 2% variation in the synchronized beam voltage. The KMPR-based UV-LIGA technique is adopted to fabricate the -plane and -plane loaded SWS. The measured lateral dimensional accuracy within and rms roughness of metal sidewall surface less than 80 nm is obtained.
Abstract: This paper presents an improved way of applying Monte Carlo simulation using the crossentropy method to calculate the risk of capacity deficit of a composite power system. By applying importance sampling for load states in addition to the generation and transmission states in a systematic manner, the proposed method is many orders of magnitude more efficient than the crude Monte Carlo simulation and considerably more efficient than other crossentropy-based algorithms that apply other ways of estimating the importance sampling distributions. An effective performance metric of system states is applied in order to find optimal importance sampling distributions during presimulation that significantly reduces the required computational effort. Simulations, using well-known IEEE reliability test systems, show that even problems that are nearly intractable using crude Monte Carlo simulation become very manageable using the proposed method.
Abstract: This paper analyzes and simulates wind shear and tower shadow effects in doubly-fed induction generators, which are known to induce a low-frequency oscillation. Such oscillation is called a 3p oscillation, which can cause shaft torsion load aggravation and shaft torque oscillation, it inevitably lead to electromagnetic torque and power fluctuation in the generator and further affect the whole wind power system. By analyzing a two-mass model, it can be known that a flexible drive train has a low-damping characteristic and an amplification of the input of low-frequency wind torque disturbances. Based on this point, this paper presents a new control scheme to restrain 3p oscillation is presented, which is a damping torque observation. A novel torque observer is designed to ascertain the required damping torque. A small-signal model is established for the system and used to analyze the system's static and dynamic characteristics. The effectiveness of the proposed strategy is finally verified by simulation and experimental results.
Abstract: The origin of positive-gate-bias-stress (PGBS)-induced instability and the effects of fluorine treatment on the instability of an InGaZnO thin-film transistor (TFT) are investigated. The fluorine treatments on the dielectric/InGaZnO interface and InGaZnO back channel of the device can effectively modulate their electrical properties. By characterizing the TFTs with various fluorine treatments, it is found that the back channel rather than the dielectric/InGaZnO interface dominates the PGBS instability. Electrons induced by moisture absorption near the back channel migrate from the back channel to the interface under PGBS at room temperature, thus resulting in a threshold-voltage decrease. Moreover, the fluorine treatment on the back channel effectively suppresses the PGBS instability due to reduced moisture absorption caused by the fluorine passivation.
Abstract: Numerical weather prediction (NWP) and buoy ocean surface winds show some systematic differences with satellite scatterometer and radiometer wind measurements, both in statistical results and in local geographical regions. It is possible to rescale these reference winds to remove certain aspects of these systematic differences. Space-borne ocean surface winds actually measure ocean surface roughness, which is related more directly to stress. Air mass density is relevant in the air–sea momentum transfer as captured in the stress vector. Therefore, apart from the already common “neutral wind correction” for atmospheric stratification, also a “mass density wind correction” is investigated here to obtain a better correspondence between satellite stress measurements and buoy or NWP winds. The bicorrected winds are called stress-equivalent winds. Stress-equivalent winds do not strongly depend on the drag formulation used and provide a rather direct standard for comparison and assimilation in user applications. This paper presents details on how this correction is performed and first results that show the benefits of this correction mainly in the extratropical regions.
Autors: Jos de Kloe;Ad Stoffelen;Anton Verhoef;
Appeared in: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Abstract: Ammonia (NH3) gas sensors with unique oxide semiconductor thin-film transistor (TFT) configuration using ZnO nanoparticles (NPs) as gas-sensing element were fabricated and their gas-sensing responses were evaluated. The ZnO NPs composing the sensing elements were synthesized using atomic layer deposition (ALD). The optimum ALD conditions for the particle-like island-growth of ZnO were established by systematically investigating the ALD temperature and cycle conditions from 140 °C to 160 °C and from 5 to 30, respectively. Controlled devices of the sensor TFTs were prepared with different ALD conditions, in which sensing and read-out elements were designed to be physically separated. This unique device configuration provided us both benefits of improvement in gas-sensing property and stability of the device characteristics. The device showed instant gas responses as well as stable device behaviors at different operating temperature even with repeated gas measurements. Sufficiently good response to NH3 were obtained at 150 °C, which was significantly lower than the operating temperature of previously reported NH3 gas sensors. Based on the results the combination of novel TFT configuration and ALD-prepared ZnO NPs could be an effective method for the improvement in device characteristics of the gas sensors.
Abstract: This letter identifies causes of the deterioration of the Global Satellite Mapping of Precipitation rain detection over the Tibetan Plateau during the summer monsoon season. Using the rain/no-rain classification (RNC) method over the Plateau, observed brightness temperature (Tb) at 21 (23) GHz from the Tropical Rainfall Measuring Mission Microwave Imager (the Defense Meteorological Satellite Program Special Sensor Microwave Imager) [Tb(21 V) and Tb(23 V)], and surface emissivity ( was substituted for surface temperatures (Ts) to exclude areas of low Ts as snow cover because it is difficult to distinguish between the scattering signals of precipitation and snow cover. A case study demonstrates that rain systems are excluded because Ts is often below the threshold for snow cover due to the use of an inadequate value for (constant value throughout the year), even though a rain scattering signal at high-frequency channels under no snow cover is evident. After is replaced with values from a monthly mean satellite observation-based land surface emissivity database, rainfall detection is improved. In addition, it is suggested that a database of RNCs should also consider diurnal variations in Tb(21 V) and Tb(23 V) due to large diurnal differences over the Plateau.
Autors: Munehisa K. Yamamoto;Ippei Tanaka;Shoichi Shige;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Abstract: Dense network deployments comprising small cells pose a series of important challenges when it comes to achieving an efficient resource use and curbing intercell interference in the downlink. This paper examines different techniques to treat these problems in a dynamic way, from the network and the receiver sides. As a network coordination scheme, we apply a centralized joint cell association and scheduling mechanism based on dynamic cell switching by which users are not always served by the strongest perceived cell. The method simultaneously results in more balanced loads and increased performance. Interference management at the receiver is achieved through the use of a network-assisted interference cancellation and suppression (NAICS) receiver. In order to further boost the fifth percentile user data rates, the transmission rank at the interferers is selectively reduced by a centralized rank coordination functionality. These mechanisms are evaluated in an LTE-Advanced dense small cell scenario with dynamic traffic. Simulation results illustrate that a combination of the centralized cell association and scheduling scheme and interference cancellation at the receiver can provide fifth percentile data rate gains of up to 80% without a detrimental effect on the median user rates, under the applied assumptions and simulation settings. The gains reach 110% when rank coordination is applied.
Autors: Víctor Fernández-López;Klaus I. Pedersen;Beatriz Soret;Jens Steiner;Preben Mogensen;
Appeared in: IEEE Transactions on Vehicular Technology
Abstract: Electricity is unique among energy sources in that its use is virtually ubiquitous in everyday life, yet it also has the potential to be instantly fatal when contacted. Due to its familiarity and commonplace use, people are often complacent about electrical hazards and underestimate the risks associated with exposure to electricity. Many veterans in the electrical industry came of age in an era when best practices for electrical work had not yet been established, and as a result they experienced firsthand the consequences of electrical incidents. Over the past several decades, there has been a movement in the industry to improve safe work practices based on these experiences. This has resulted in great improvements to electrical safety, making electrical incidents not as common. The challenge today is to transfer the knowledge gained from past experience to workers who may not have witnessed serious electrical incidents and, as a result, may fail to recognize the potential for injury associated with electrical work. This article explores how perception of risk affects a worker's decision-making process for recognizing electrical hazards and assessing the likelihood and severity of the associated risks.
Abstract: Fundamental to an electrical safety program is establishing electrically safe work conditions. De-energizing equipment, following adequate lockout/tagout procedures, and verifying the absence of voltage are key to accomplishing this. As industry strives to make the practice of de-energizing equipment before performing electrical work standard practice, verifying the absence of voltage has become one of the most frequent tasks performed by qualified electrical workers.
Abstract: The 2D transfer function based on scalar value and gradient magnitude (SG-TF) is popularly used in volume rendering. However, it is plagued by the boundary-overlapping problem: different structures with similar attributes have the same region in SG-TF space, and their boundaries are usually connected. The SG-TF thus often fails in separating these structures (or their boundaries) and has limited ability to classify different objects in real-world 3D images. To overcome such a difficulty, we propose a novel method for boundary separation by integrating spatial connectivity computation of the boundaries and set operations on boundary voxels into the SG-TF. Specifically, spatial positions of boundaries and their regions in the SG-TF space are computed, from which boundaries can be well separated and volume rendered in different colors. In the method, the boundaries are divided into three classes and different boundary-separation techniques are applied to them, respectively. The complex task of separating various boundaries in 3D images is then simplified by breaking it into several small separation problems. The method shows good object classification ability in real-world 3D images while avoiding the complexity of high-dimensional transfer functions. Its effectiveness and validation is demonstrated by many experimental results to visualize boundaries of different structures in complex real-world 3D images.
Abstract: This study aims at improving the assimilation of scatterometer wind observations in global Numerical Weather Prediction (NWP) model by refining the background quality control and optimizing the observation sampling strategy. To improve the background quality control, different Huber Norm distribution implementations are tested and compared against the current “Gaussian plus flat” distribution. Sensitivity experiments show that the usage of the Huber Norm distribution improves the analysis and forecasts. The benefit is mainly seen in the lower model levels in the tropics and extra-tropical Southern Hemisphere. The optimal wind sampling is investigated by testing several combinations of thinning scheme and observation error standard deviation. The impact is demonstrated with a large sample and illustrated by a case study. The case study shows the impact of different settings on the analysis and forecast of a tropical cyclone. A revised wind sampling setting, where four times more observations and a higher observation error than the current operational one are used, showed slightly positive impact on the European Centre for Medium-Range Weather Forecasts (ECMWF) global NWP analyses and forecasts.
Autors: Giovanna De Chiara;Massimo Bonavita;Stephen J. English;
Appeared in: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Abstract: John Staudhammer, who died in February 2017, profoundly influenced computer graphics technology and people. His work in computer graphics education and his contributions to the field as a whole significantly impacted the computer graphics technology we now take for granted.
Autors: David J. Kasik;
Appeared in: IEEE Computer Graphics and Applications
Abstract: This letter reports a conceptual in-die through-back-end-of-the-line metal wall structure for noise isolation demonstrated in a foundry 180-nm fully depleted silicon-on-insulator (FD-SOI) CMOS technology. The near-closed-loop isolation wall was made of a trench ring etched by focused ion beam and filled with silver nano powder in a post-CMOS process module developed. Crosstalk suppression was confirmed in measurement that shows a reduction of around 9 dBm in the third-order intermodulation interferers as predicted full-wave electromagnetic co-simulation. The structure can be readily integrated into the foundry technologies as a potential crosstalk reduction solution for mixed-signal integrated circuits in FD-SOI CMOS processes.
Abstract: The paper provides real-word wireless measurement data of the intravehicular channel for both the and the frequency bands under similar conditions. By spatially averaging channel impulse response realizations within a grid, we obtain the power-delay profile (PDP). The data measured at and exhibit significant differences in terms of root mean square (RMS) delay spread, number of resolvable clusters, and variance of the maximal excess delay. Moreover, we evaluate the spatial stationarity via the Pearson correlation coefficient and via the PDP collinearity, depending on the distance in the grid. The measured and calculated results indicate that a strong reverberation inside the vehicle produces similar PDPs within the range of approximately ten wavelengths. We also provide a linear piecewise model of the PDP in logarithmic scale and a generalized extreme value model of a small-scale signal fading. Our channel model is validated utilizing the Kolmogorov–Smirnov test.
Abstract: In this letter, we propose a novel incentive pricing mechanism, where wireless service provider (WSP) offers additional benefits (called bonus) to motivate the adoption of hybrid access in femtocells. The problem is formulated as a two-stage Stackelberg game to reach a win–win situation, where WSP determines the pricing policy as the leader and FOs respond as the followers. The optimal proportion of shared resources for each FO and the optimal pricing factor for WSP are decided independently. Furthermore, a Quality of Service (QoS) based admission control scheme is also designed to admit or reject macro users access. Numerical simulations have been conducted and the results show that the utilities of both WSP and FOs are significantly improved due to the exploitation of incentive pricing mechanism.
Abstract: We present a novel data programming scheme for flash memory. In each word-line, exactly out of memory cells are programmed while the rest are kept in the erased state. Information is then conveyed by the index set of the programmed cells, of which there are possible choices (also called activation patterns). In the case of multi-level flash, additional information is conveyed by the threshold-voltage levels of the programmed cells (similar to traditional programming). We derive the storage efficiency of the new scheme as a function of the fraction of programmed cells and determine the fraction that maximizes it. Then, we analyze the effect of this scheme on cell-to-cell interference and derive the conditions that ensure its reduction compared with the traditional programming. Following this, we analyze the performance of our new scheme using two detection methods: fixed reference detection and dynamic reference detection, and conclude that using dynamic reference detection will result in page error performance improvements that can reach orders of magnitude compared with that attainable by the fixed reference approach. We then discuss how logical pages can be constructed in the index programming similarly to traditional programming. Finally, we discuss the results and tradeoffs between storage efficiency and error resilience proposed by the scheme along with some future directions.
Autors: Hachem Yassine;Justin P. Coon;David E. Simmons;
Abstract: This work aims to propose a framework with guidelines applicable to three-dimensional learning environments from the usability heuristics appropriate for these systems, in order to evidence the elements that allow to measure an application within the emphasis on education and/or training. The research was carried out based on a systematic review on immersive three dimensional environment heuristics with an emphasis on education and training. Initially, a compilation of research was done through the digital scientific databases. The heuristics will be presented as a statement and will aim to measure the degree of agreement of the interviewees, for which each statement is associated with a Likert scale of frequency of five points. In this way, the present article proposes an evaluation approach that allows to measure elements through heuristics that can be used by several educational professionals. In addition, the present approach allows the reuse of existing systems, evaluating them according to the application emphasis, which enables the adaptation of a three-dimensional virtual learning environment to both educational and training needs.
Autors: Adriana Porto Proenca;Milton Miranda Neto;Rodrigo Godoy Domingues;Ludymila Ribeiro Borges;Alexandre Cardoso;Pollyana Notargiacomo;
Abstract: Motor current signature analysis (MCSA) has recently become widespread in industry for on-line detection of rotor cage faults in induction motors for preventing forced outages. Although it can provide low cost remote monitoring of rotor faults, cases of false indications have been reported, where the causes of some false indications are still unknown. It is shown for the first time in this work that high-amplitude blade pass frequency (BPF) vibrations produced in pumps, fans, or compressors can cause false rotor fault indications if the number of motor poles is an integer multiple of the number of blades. The influence of BPF vibration on MCSA-based rotor fault detection is analyzed, and it is shown that the interaction between BPF vibration and rotor faults can produce false positive and negative fault indications. Alternative test methods capable of separating the influence of the BPF vibration and rotor faults are suggested for avoiding false MCSA alarms. The claims made in the paper are verified experimentally on a custom-built 380 V induction motor-centrifugal pump system setup.
Autors: Yonghyun Park;Myung Jeong;Sang Bin Lee;Jose Alfonso Antonino-Daviu;Mike Teska;
Appeared in: IEEE Transactions on Industry Applications
Abstract: This paper presents an in-depth analysis of the impact of body-biasing, supply voltage, and temperature on the detection of resistive short defects in FDSOI technology. Three types of short defects are considered for our investigation, namely resistive short to ground terminal, resistive short to power supply terminal (VDD), and intergate resistive bridging defect. The two implementation options offered by the technology, i.e., low VT (LVT) and regular VT (RVT) devices are also studied. Defect detectability is evaluated in the context of logic test using the concept of critical resistance. The optimal body-biasing, supply voltage, and temperature settings to achieve the maximum defect coverage are determined through HSPICE simulations using a didactic circuit implemented with 28-nm UTBB FDSOI gate library. An analytical analysis is also proposed based on the on-resistance model of P and N networks, which permits to evaluate the value of the critical resistance without performing fault simulations. In addition, this paper quantifies the individual as well as the combined improvements in detection brought by body-biasing, supply voltage, and temperature settings for the different defect types and different implementations.
Autors: Amit Karel;Mariane Comte;Jean-Marc Galliere;Florence Azais;Michel Renovell;
Abstract: With the increase of the capacity of a fully air-cooled hydro-generator, the electromagnetic and thermal designs of such machine face more and more pressure. To ensure the reliability of a large hydro-generator, the thermal issue in rotor should be emphasized. In this paper, the temperature distribution in exciting windings and the fluid flowing between rotor poles are highlighted and investigated. Taking a 250 MW fully air-cooled large hydro-generator as an example, a three-dimensional solid–fluid heat transfer coupling model of the fluid and temperature was established, which includes half-axial rotors, two poles in circumferential direction, and the yoke with four radial ventilation ducts. Via investigating on the loss distribution and the heat transfer condition in the rotor, the fluid and temperature fields of half-axial rotors are calculated by using the conjugated heat transfer method. The obtained results are verified by the measured values. The influences of the velocity and temperature of fluid on its effectiveness of cooling excitation windings, and the relationship between the fluid flow velocity and the heat transferred from outer surface of rotor windings are investigated as well. Similarly, the variations of fluid temperature distribution, the flowing velocity, and the heat transfer coefficient distribution in rotors with two or three ventilation ducts are investigated. The effects of the corresponding velocity and temperature of fluid on temperature distribution within both the windward and leeward side excitation windings are also studied.
Abstract: For several years, our research group has developed electrohydrodynamic (EHD) actuators able to set dielectric liquid in motion. More precisely, these actuators are designed to produce electroconvective flows up to 1 m/s. These flows are jets (impinging jet, wall jet, etc.) that can be used in various applications such as mixing, flow control, cooling systems, etc. The main advantages of these actuators are direct conversion of electric energy into inertial energy (without moving parts), low cost, and easy miniaturization. EHD pumps could be used in microfluidic applications. Nevertheless, the fundamental physics of these flows remains complex, and in order to have a better understanding of these electroconvective flows, we need a more reliable analysis method. The best method to date is particle image velocimetry. However, in order to show liquid movement, this method requires seeding particles, which can be electrically charged and so on can be influenced by the electric field produced by the electrodes. In this work, we study the behavior of three types of seeding particles under high electric field in order to estimate the error induced by the electric field on the measurement of the liquid velocity.
Abstract: During manufacturing of electrical machines, shape giving production steps such as punching and cutting introduce plastic deformations and residual stress to the soft magnetic material. As a result, the magnetic properties of the material decrease and locally both static and dynamic hysteresis losses increase in the vicinity of the cut surfaces. For consideration of local permeability deteriorations, different models have been published. These are capable of describing the changing local magnetization and loss behavior. Current approaches subdivide the magnetic core into slices of different magnetic properties, thereby discretizing the continuous deterioration. This paper analyzes the effects of material degradation due to cutting on the performance and machine parameters of a permanent magnet synchronous machine using a continuous material model for efficient numerical modeling of the local magnetization behavior. By replacing inefficient sliced models, the continuous model is independent of the discretization and converges in case of coarse meshes to the sliced model. Influences on the machine behavior are studied in terms of local flux density distributions, iron losses, efficiency, torque, and inductances on the operating map and an exemplary working point.
Abstract: Spatial modulation (SM) has recently attracted plenty of academic interest due to its low complexity and high energy efficiency. However, the performance of SM transmission in dispersive channels is still limited due to the strong intersymbol interference (ISI) caused by frequency-selective fading. In this paper, we propose a novel a priori information-aided iterative equalization scheme for single-carrier SM (SC-SM) systems. Unlike the conventional equalization schemes for SC-SM, the proposed receiver manages to utilize the soft information from the decoder to improve the equalization performance, which eliminates the ISI in an iterative manner and leads to significant performance gain. Simulations show that the proposed system is capable of outperforming state-of-the-art equalization schemes while only a limited amount of complexity is required.
Autors: Longzhuang He;Jintao Wang;Jian Song;
Appeared in: IEEE Transactions on Vehicular Technology
Abstract: The information-centric networking (ICN), which is an important research direction of future internet architecture, has gained lots of attention from the research community. This paper investigates the impact of a correlated mobility on the throughput and delay performance of mobile ad hoc networks (MANETs) under information-centric environments, where the main concern of nodes is to retrieve contents stored by other nodes. Based on the degree of correlation among nodes, we consider two network regimes, i.e., the cluster-dense regime and cluster-sparse regime. In each regime, we study two mobility time scales: 1) fast mobility, where node mobility is at the same time scale as packet transmissions, and 2) slow mobility, where node mobility is at a much slower time scale than the packet transmissions. In each regime, we characterize the network performance under fast mobility and slow mobility, respectively. Our results indicate that
under fast mobility, correlated mobility improves delay performance at the cost of throughput performance;
Abstract: Enabling the high data rates of millimeter wave (mmWave) cellular systems requires deploying large antenna arrays at both the basestations and mobile users. Prior work on coverage and rate of mmWave cellular networks focused on the case when basestations and mobile beamforming vectors are predesigned for maximum beamforming gains. Designing beamforming/combining vectors, though, requires training, which may impact both the SINR coverage and rate of mmWave systems. This paper evaluates mmWave cellular network performance while accounting for the beam training/association overhead. First, a model for the initial beam association is developed based on beam sweeping and downlink control pilot reuse. To incorporate the impact of beam training, a new metric, called the effective reliable rate, is defined and adopted. Using stochastic geometry, the effective rate of mmWave cellular networks is derived for two special cases: near-orthogonal pilots and full pilot reuse. Analytical and simulation results provide insights into the answers of two important questions. First, what is the impact of beam association on mmWave network performance? Then, should orthogonal or reused pilots be employed? The results show that unless the employed beams are very wide, initial beam training with full pilot reuse is nearly as good as perfect beam alignment.
Autors: Ahmed Alkhateeb;Young-Han Nam;Md. Saifur Rahman;Jianzhong Zhang;Robert W. Heath;
Appeared in: IEEE Transactions on Wireless Communications