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: 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: 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
Abstract: Magnetically driven micromachines play an essential role in a number of biomedical and other remote control applications. In this paper, a magnetically driven robot composed of customized UV-curable resin was fabricated by (3-D) printing via initiator-triggered radical polymerization and the subsequent polyelectrolyte-brush-assisted electroless plating. A layer of magnetic material was grown in situ on the 3-D printed structure, which exhibited soft-magnetic properties proved by the vibrating sample magnetometer measurement. The magnetic robot was successfully actuated under the rotating magnetic field produced from a manipulator of permanent magnet. By utilizing the spiral structure, the 3-D robot was designed to translate rotational movement into linear motion. A comprehensive investigation was also carried out on the optimization of spiral shape, liquid viscosity and the strategy of magnetic controlling. The remote controlling experiments demonstrate that this initiator-integrated 3-D printing is an effective technique for making magnetically driven objects.
Abstract: This paper describes a study of teaching a programming language in a C programming course by having students assemble and program a low-cost mobile robot. Writing their own programs to define the robot’s behavior raised students’ motivation. Working in small groups, students programmed the robots by using the control structures of structured programming. Over the course, there was a significant improvement in students’ academic performance and motivation. The approach took into account four of the motivational factors that feature in the ARCS model: 1) attention; 2) relevance; 3) confidence; and 4) satisfaction. The main achievements of the approach were to be able to: 1) catch and hold students’ attention throughout the course; 2) increase students’ confidence in the learning process; 3) achieve a high student satisfaction level with their acquired skills; and 4) demonstrate to students the practical usefulness of the knowledge they had learned. This paper also determines the extent to which this strategy was effective in meeting the teaching goals.
Autors: Octavio Ortiz Ortiz;Juan Ángel Pastor Franco;Pedro María Alcover Garau;Ruth Herrero Martín;
Abstract: Organic thin-film transistors (OTFTs) were fabricated using a novel small molecule, C6-NTTN, as the semiconductor layer in several different architectures. The C6-NTTN layer was deposited via both vacuum evaporation at different substrate temperatures and via solution-processing, which yield maximum hole mobilities of 0.16 and 0.05 cm2/, respectively. Surface treatments of the substrate, insulator, and metal contacts used for OTFT fabrication employing polymer films and different self-assembled monolayers were investigated. In particular, in bottom-gate devices, the insulator surface hydrophobicity was optimized by the deposition of poly(methyl methacrylate) or hexamethyldisilazane, while in the top-gate geometry, pentafluorobenzenethiol was efficiently used to modify the substrate surface energy and to change the contact work function. Atomic force microscopy analysis was exploited to understand the relationship between the semiconductor thin-film morphology and the device electrical performance. The results shown here indicate an inverse proportionality between the mobility and the interface trap density, with parameters depending especially on semiconductor–insulator interfacial properties, and a correlation between the threshold voltage and the characteristics of the semiconductor–metal interface.
Abstract: This paper proposes a method to detect and evaluate surface and subsurface cracks in aluminum multilayer structures using a planar eddy current testing (ECT) probe and processing an inverse problem algorithm. The proposed excitation method using this ECT probe allows the induction of eddy currents with different orientations on the metal surface without rotating the probe during the scan. An inversion algorithm was applied to evaluate the geometry of the cracks. The main result of this inversion algorithm is the determination of the shape of the cracks using the reconstructed eddy current pattern inside the specimen. These reconstructed patterns give the indication of the length, orientation, and geometry profile of the crack. In this paper, complex geometry cracks at different depths are inspected. Experimental data were obtained around a star crack at different depths in a stack of four aluminum plates where each plate has a thickness equal to 1 mm. The presented work shows that the distance between the sensor and the layer under analysis must be adjusted in the inversion process in order to obtain the best reconstructed images when subsurface cracks are under study. This consideration affects the quality of the resulting images.
Abstract: This paper presents two fuel-prioritized feedback controllers, which are called the estimated minimum principle (EMP) and kinetic energy conversion (KEC), to realize eco-cruising on varying slopes for vehicles with conventional powertrains. The former is derived from the minimum principle with an estimated Hamiltonian, and the latter is designed based on the equivalent conversion between the kinetic-energy change of vehicle body and the fuel consumption of the engine. They are implemented with analytical control laws and rely on current road slope information only without look-ahead prediction. This feature results in a very light computing load, with the average computing time of each step less than one millisecond. Their fuel-saving performances are quantitatively studied and compared with a model predictive control and a constant speed control. As an expansion, the control rule for avoiding rear-end collision is also designed by using a safety-guaranteed car-following model to constrain the high-risk behaviors.
Abstract: Diverse conditions in power systems, such as massive use of nonlinear loads, continuous switching and operation of large electrical loads, and the integration of renewable energies, among others, have adversely affected the power quality (PQ) because they produce undesirable distortions in the waveforms of voltage and current. The conventional way to quantify the PQ is using the PQ indices (PQIs). Yet, the nonstationary properties of voltage and current signals degrade the PQIs estimation whenever classical techniques are used. In this paper, a methodology based on single-sideband modulation method and the Wavelet and Hilbert transforms for the estimation of instantaneous PQIs is proposed. It is shown that the proposal yields better tracking of transitory changes in the voltage/current signals than classical techniques such as the short-time Fourier transform. The PQIs used are the root-mean-square values, frequency, total harmonic distortion, active power, reactive power, apparent power, distortion power, power factor, and total power factor. PQIs performance is validated using synthetic and real signals.
Autors: Ismael Urbina-Salas;Jose R. Razo-Hernandez;David Granados-Lieberman;Martin Valtierra-Rodriguez;Jose E. Torres-Fernandez;
Appeared in: IEEE Transactions on Instrumentation and Measurement
Abstract: Power distribution equipment is the backbone of any industrial process infrastructure. Safety and reliability are the two most important criteria in the proper functioning of the power distribution system. Low-voltage switchgear (LVS) is an important part of power distribution. Minimizing arc faults in the switchgear is a matter of utmost concern to maintain a safe environment. Arc-resistant LVS is designed to provide an additional degree of protection for operating personnel performing normal duties near the equipment. In this article, we report a series of arc-flash simulations performed on an arc-resistant LVS in both bare bus (noninsulated) and insulated or isolated bus configurations. In all simulations, the insulated or isolated bus had a significantly shorter arc duration and lower energy emissions.
Abstract: Electrical safety is imperative for kee ping workers safe, and a safety management system is a means to implement it. The safety management system known as Integrated Safety Management (ISM) is a formal and proven system for the safe execution of work activities. The ISM system can be incorporated into a work-control process and structure an electrical safety program through its guiding principles and core functions. An electrical safety work-control process has two components that need to be implemented for success: a National Fire Protection Association (NFPA) 70E-based electrical safety program and an ISM-based work-control process. An electrical safety program that implements the seven guiding principles and five core functions listed in Table 1 gives a well-defined and document-supported process to keep workers safe.
Abstract: As more and more proofs show that fine particles (diameter of and below) pose more risk on human health than coarse particles, an increasing need for monitoring fine particles has emerged. A miniaturized sensor designed for measuring fine particle concentration is presented in this paper. The proposed sensor possesses a compact size of only 15 mm mm mm. A virtual impactor has been integrated as a particle size selector and the design is optimized by simulation-assisted analysis. The sensor is realized by silicon microfabrication and wafer-level packaging. Testing results show that a high measurement accuracy of has been achieved.
Abstract: What does an online programming course need to engage students and improve their skills? To answer this question, the authors designed and tested a feature-rich collaborative environment for an online class and found that it enhanced learning through methods such as remote pair programming, live coding, and a tight code-to-artifact feedback loop.
Abstract: Light detection and ranging (LiDAR) data classification provides useful thematic maps for numerous geospatial applications. Several methods and algorithms have been proposed recently for LiDAR data classification. Most studies focused on object-based analysis because of its advantages over per-pixel-based methods. However, several issues, such as parameter optimization, attribute selection, and development of transferable rulesets, remain challenging in this topic. This study contributes to LiDAR data classification by developing an approach that integrates ant colony optimization (ACO) and rule-based classification. First, LiDAR-derived digital elevation and digital surface models were integrated with high-resolution orthophotos. Second, the processed raster was segmented with the multiresolution segmentation method. Subsequently, the parameters were optimized with a supervised technique based on fuzzy analysis. A total of 20 attributes were selected based on general knowledge on the study area and LiDAR data; the best subset containing 12 attributes was then selected via ACO. These attributes were utilized to develop rulesets through the use of a decision tree algorithm, and a thematic map was generated for the study area. Results revealed the robustness of the proposed method, which has an overall accuracy of ∼95% and a kappa coefficient of 0.94. The rule-based approach with all attributes and the k nearest neighbor (KNN) classification method were applied to validate the results of the proposed method. The overall accuracy of the rule-based method with all attributes was ∼88% (kappa = 0.82), whereas the KNN method had an overall accuracy of <70% and produced a poor thematic map. The selection of the ACO algorithm was justified through a comparison with three well-known feature selection methods. On the oth-
r hand, the transferability of the developed rules was evaluated by using a second LiDAR dataset at another study area. The overall accuracy and the kappa index for the second study area were 92% and 0.90, respectively. Overall, the findings indicate that the selection of a subset with significant attributes is important for accurate LiDAR data classification with object-based methods.
Autors: Maher Ibrahim Sameen;Biswajeet Pradhan;Helmi Z. M. Shafri;Mustafa Ridha Mezaal;Hussain bin Hamid;
Appeared in: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Abstract: In this paper, an optimization model is developed to find a plug-in hybrid electric vehicle (PHEV) optimum charging rate profile that dynamically varies throughout the day. From the grid point of view, the model takes into account the constraints of maximum demand and charging facilities, while from the driver’s point of view, waiting and charging time restrictions are considered. The novelty of this paper lies in maximizing the energy delivered to PHEVs in a region equipped with smart grid technology by intelligently alternating charging rates during the day while incorporating both driver satisfaction constraints as well as grid limitations. Using the proposed optimization model, two cases with optimized charging rates are studied and compared with constant charging levels. Furthermore, quantitative results from the perspective of both power grid contribution and driver satisfaction are presented and discussed in detail for each case.
Autors: Zahra Darabi;Poria Fajri;Mehdi Ferdowsi;
Appeared in: IEEE Transactions on Intelligent Transportation Systems
Abstract: This article discusses issues related to the application of the user interactivity in optimization process, aided by the method of the Evolution Strategies, with the objective of improve the minimization process of the evaluated functions, both in their response and in the time of obtaining, through the intervention of the user. Its development is based on the methodology of the Evolution Strategies, characterized by the concept of natural selection. However, the minimization process requires an intervention in the stagnations of local minima to get a better efficiency. To increase the applicability of the approached methodology, it is proposed the use of the user interactivity in minimization process, allowing the manipulation of mutation rate and recombination, activation of the mutation of self-adaptive parameters as well as monitoring the whole process. The proposed methodology was used in the evaluation of test functions for optimization, as well as in the evaluation of a real case.
Autors: Luiz Henrique Reis Jesus;Leonardo Cunha Brito;
Abstract: The increasing integration of distributed renewable energy resources highlights the need to design new control strategies for hybrid wind turbine-photovoltaic (WT-PV)-battery microgrid (MG) clusters. This paper proposes a two-level optimization model for the coordinated energy management between distribution systems and clustered WT-PV-battery MGs. The upper level of the model deals with the operation of the distribution network, while the lower level considers the coordinated operation of multiple MGs. An interactive game matrix (IGM) is applied to coordinate the power exchange among multiple MGs, and between the distribution network and MGs. The model is solved by a modified hierarchical genetic algorithm. Case studies on a distribution system with MGs, as well as a practical multi-MG system, demonstrate the effectiveness of the proposed method in improving power quality, reliability, and environmental benefits.
Abstract: Efforts are underway to advance technical standards education into science, technology, engineering, and mathematics (STEM) university programs. This article provides an overview of Project ISTEE: Integrating Standards into Telecommunication Engineering Education. We discuss the background and motivations behind this project and describe its tasks and deliverables. The project produces a university course in telecommunication standards and standardization processes. Evaluation results of two offerings of this course are reported and discussed. Our findings confirm that interactive research-based instruction strategies are particularly suitable for standards education. A model for standards education is developed that can be adopted by other STEM disciplines.
Abstract: Automatic change detection is one of the remote sensing applications that has received an increasing attention during the last years. However, fully automatic solutions reach their limitation; on the one hand, it is difficult to design general decision criteria able to select area of changes for images under various acquisition conditions, and on the other hand, the relevance of changes may differ from one user to another. In this letter, we introduce an alternative change detection method based on relevance feedback. The proposed algorithm is iterative and based on a query and answer model that: 1) asks the user questions about the relevance of his targeted changes and 2) according to these answers, updates change detection results. Our method is also based on a new formulation of canonical correlation analysis (CCA), referred to as context-aware CCA, that learns transformations, which map data from different input spaces (related to multitemporal satellite images) into a common latent space, which is sensitive to relevant changes while being resilient to irrelevant ones. These CCA transformations correspond to the optimum of a particular constrained maximization problem that mixes an alignment term with a context-based regularization criterion. The particularity of this novel CCA approach resides in its ability to exploit spatial geometric context resulting into better performances compared with other CCA approaches, as shown in experiments.
Autors: Hichem Sahbi;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Abstract: A design education program must unite traditionally siloed disciplines, spanning rigid academic boundaries from engineering to social sciences. Work to establish the Kyoto University Design School had to meet these challenges in promoting interdisciplinary cooperation and provides a solid model for others to build on. The web extra at https://youtu.be/bTWoIew-lpg features interviews and further details about Kyoto University Design School's innovative curriculum.
Abstract: Advanced Land Observing Satellite-2 (ALOS-2) is designed to routinely acquire both scanning synthetic aperture radar (ScanSAR) and stripmap data. In this paper, we present a special multiband bandpass filter (MBF) to remove azimuth nonoverlap spectra for the interferometric processing of ALOS-2 full-aperture ScanSAR product. As required by the MBF, we estimate the important ScanSAR system parameters and the start times of raw bursts using ALOS-2 full-aperture ScanSAR image. The resulting MBF can remove the nonoverlap spectra caused by both Doppler centroid frequency difference and burst misalignment. It can be used in ScanSAR-ScanSAR interferometry, as well as ScanSAR-stripmap interferometry. Based on the MBF, we propose a single processing workflow that is able to implement both ScanSAR-ScanSAR interferometry and ScanSAR-stripmap interferometry. Finally, we present example interferograms of the 2015 Gorkha earthquake in Nepal processed using the proposed processing workflow. The interferograms are greatly improved after applying the MBF to remove the significant amount of nonoverlap spectra in the data.
Autors: Cunren Liang;Eric J. Fielding;
Appeared in: IEEE Transactions on Geoscience and Remote Sensing
Abstract: This paper analyzes a duopoly-like situation in the wet shaving industry featuring an innovation leader and a follower. In this, the leader claims to have filed “interlocking” patents. The explorative case study examines how the leader filed said patents and how their structures have affected potential value appropriation. In fact, the market leader has claimed technical elements in multiple patents, while the patents themselves do not legally overlap. This analysis will also cover triggers and boundary conditions that facilitate or limit such claim compositions. Finally, the market leader has seemingly been able to successfully appropriate value from its strategy. This study will contribute to the literature on value appropriation, the interplay between corporate engineering and intellectual property functions, as well as the economics literature on patent thickets.
Autors: Christian Sternitzke;
Appeared in: IEEE Transactions on Engineering Management
Abstract: In celebration of IEEE Internet Computing's 20th anniversary, the inaugural Editor-in-Chief Charles Petrie reminisces about the time period surrounding the magazine's beginnings, as well as how IC became the IEEE Computer Society's first magazine posted online.
Abstract: Open education resources (OERs) are public domain learning objects used extensively in both online and traditional education settings. To facilitate the use of OERs, a novel chemistry-inspired framework links learning objects to help the education community contribute, augment, and locate these valuable resources.
Abstract: A method is explored and developed for significantly accelerating the computation of the Ewald series representation for periodic homogeneous media Green’s functions. The method involves extracting corner singularity terms from the corners of the unit cell, resulting in a smooth regularized Green’s function that is amenable to interpolation. The approach can be used to accelerate layered-media problems, where application of Kummer’s method splits the spectral (Floquet modal) series representation into a rapidly converging difference series that is regular plus a residual series that contains any spatial singularities present. The residual series corresponds to a homogeneous medium, and can thus be treated with the method proposed here.
Autors: Ferhat Turker Celepcikay;Donald R. Wilton;David R. Jackson;William A. Johnson;
Appeared in: IEEE Transactions on Antennas and Propagation
Abstract: A physical layer encryption method is proposed for orthogonal frequency division multiplexing with offset quadrature amplitude modulation. The proposed method uses intentionally added pure imaginary symbols as keys, so that their intrinsic interferences can obfuscate true data symbols at the eavesdroppers. The key generation method and four loading patterns are proposed. Also, the impact of channel estimation error, the robustness against ciphertext attacks, and the information leakage at the eavesdropper are analyzed. Finally, the performance of the proposed method is evaluated through numerical simulations.
Abstract: This issue of the IEEE Journal of Solid-State Circuits includes a selection of papers presented at last year’s Radio-Frequency Integrated Circuits (RFIC) Symposium, highlighting some of the main advances in radio-frequency integrated circuit design. The RFIC Symposium, which is part of the IEEE MTT-S Microwave Week, is considered the premier conference for publishing advances in the area of wireless IC design. The focus areas of last year’s meeting, held in San Francisco, CA, USA, cover a broad range of topics from 5G millimeter-wave-integrated systems to low-power wireless sensors, from spectrum sensing to mixed-signal power amplifiers, from terahertz to baseband circuits.
Abstract: Advances in wireless communications and microelectronics have spearheaded the development of unmanned aerial vehicles (UAVs), which can be used to augment a ground network composed of sensors and/or vehicles in order to increase coverage, enhance the end-to-end delay, and improve data processing. While UAV-aided networks can potentially find applications in many areas, a number of issues, particularly security, have not been readily addressed. The intrusion detection system is the most commonly used technique to detect attackers. In this paper, we focus on addressing two main issues within the context of intrusion detection and attacker ejection in UAV-aided networks, namely, activation of the intrusion monitoring process and attacker ejection. In fact, when a large number of nodes activate their monitoring processes, the incurred overhead can be substantial and, as a consequence, degrades the network performance. Therefore, a tradeoff between the intrusion detection rate and overhead is considered in this work. It is not always the best strategy to eject a node immediately when it exhibits a bad sign of malicious activities since this sign could be provisional (the node may switch to a normal behavior in the future) or be simply due to noise or unreliable communications. Thus, a dilemma between detection and false positive rates is taken into account in this paper. We propose to address these two security issues by a Bayesian game model in order to accurately detect attacks (i.e., high detection and low false positive rates) with a low overhead. Simulation results have demonstrated that our proposed security game framework does achieve reliable detection.
Autors: Hichem Sedjelmaci;Sidi Mohammed Senouci;Nirwan Ansari;
Appeared in: IEEE Transactions on Intelligent Transportation Systems
Abstract: In February 2014, the FBI charged a Florida man, Marc Heera, with selling a cloned version of the Hondata s300, a plug-in module for the engine computer that reads data from sensors in Honda cars and automatically adjusts the air-fuel mixture, idle speed, and other factors to improve performance. The plug-in also allows users to monitor the engine via Bluetooth and make their own adjustments. The clones certainly looked like the genuine product, but in fact they contained circuit boards that had likely been built in China, according to designs Heera had obtained through reverse engineering. Honda warned that cars using the counterfeits exhibited a number of problems, including random limits on engine rpm and, occasionally, failure to start. Devices that connect to an engine control unit (ECU) present particular safety concerns; researchers have demonstrated that, through ECU access, they could hijack a car's brakes and steering.
Autors: Mark M. Tehranipoor;Ujjwal Guin;Swarup Bhunia;
Abstract: This paper analyzes the performance of cooperative hybrid automatic repeat request with incremental redundancy (HARQ-IR) and proposes a new approach of outage probability approximation for performance analysis. A general time-correlated Nakagami fading channel covering fast fading and Rayleigh fading as special cases is considered here. An efficient inverse moment matching method is proposed to approximate the outage probability in a closed form. The effect of approximation degree is theoretically analyzed to ease its selection. Moreover, diversity order of cooperative HARQ-IR is analyzed. It is proved that the diversity order is irrelevant to the time correlation coefficient , as long as , and full diversity from both spatial and time domains can be achieved by cooperative HARQ-IR under time-correlated fading channels. The accuracy of the analytical results is verified by computer simulations, and the results reveal that cooperative HARQ-IR scheme can benefit from high fading order and low channel time correlation. Optimal rate selection to maximize the long-term average throughput given a maximum allowable outage probability is finally discussed as one application of the analytical results.
Abstract: The problem of subsurface inverse profiling of a 2-D inhomogeneous buried dielectric target is addressed in this letter. An iterative optimization technique is proposed that utilizes Covariance Matrix Adaption Evolutionary Strategy (CMA-ES) as its inverse solver and Method of Moments, using Conjugate Gradient-fast Fourier transform, as the forward solver. The numerical results indicate that CMA-ES, as its first reported implementation in buried target reconstruction, can successfully be applied to this challenging reconstruction problem. Also, comparison with Evolutionary Programming and Particle Swarm Optimization indicates that CMA-ES can significantly outperform the other two-optimization techniques in the inhomogeneous subsurface imaging. In addition, examples of various scenarios involving noisy data, lossy targets and multiple targets further demonstrate that CMA-ES can be considered as a robust, simple, and efficient optimization tool in the reconstruction of complex buried targets.
Abstract: The hump phenomenon along with a negative shift of threshold voltage emerging in the transfer characteristics of amorphous InGaZnO thin-film transistors under negative bias stress was investigated. Higher measurement temperature and larger bias voltage can induce more and faster hole injection, thus leading to the increased parasitic ON-state current and more negative shift of the threshold voltage. Nevertheless, the parasitic current is independent of the channel width, illustrating that the parasitic channel originates from the hole trapping near the IGZO edges along the channel length. Integrated Systems Engineering Technology Computer-aided Design simulation confirms that the electric field near the IGZO edge is relatively dense, and the direction is more conducive for the holes in IGZO to inject into passivation (PV), to gate insulator (GI), or at PV/GI interface.
Abstract: The use of nonlinear architectures for energy harvesting can significantly improve the efficiency of the conversion mechanism, as respect to the use of linear devices, especially when the mechanical energy is distributed over a wide frequency bandwidth. This is the case of energy harvesting form wideband vibrations. In this paper, performances of a piezoelectric energy harvester exploiting a snap-through buckling configuration are investigated. The device is supposed to switch between its stable states, where two piezoelectric transducers are positioned to implement the mechanical-to-electric conversion mechanism. A simple theoretical two-state model of the device is presented along with a complete experimental characterization aimed at investigating the mechanical and electrical behaviors of the device. The device is demonstrated to be capable of scavenging energy from vibration sources in the range 0.5–5 Hz, but could be exploited up to 15 Hz with an acceptable loss of efficiency. The bandwidth of the device is compatible with applications where the vibrations occur at low frequencies, e.g., in the case of a running human. In this paper, we demonstrate the viability of our setup for harvesting energy from mechanical vibrations. The device is seen to generate power up to at 5 Hz; the power is sufficient to operate a standard wireless sensor node. The conversion efficiency of the harvester in the range 0.5–5 Hz is from 13% up to 18% with an average of 15%.
Autors: Bruno Andò;Salvatore Baglio;Adi R. Bulsara;Vincenzo Marletta;Antonio Pistorio;
Appeared in: IEEE Transactions on Instrumentation and Measurement
Abstract: Amorphous InGaZnO (a-IGZO) thin-film transistors (TFTs) are investigated for a possible application to infrared (IR) photodetector through subgap density-of-states over the forbidden bandgap. The origin of the sub-bandgap( photo-response in a-IGZO TFTs is due to optically pumped electrons from the photo-responsive subgap states (-. Among the sub-bandgap lights, we investigate the reproducible IR photo-response in a-IGZO TFTs as a photodetector without the persistent photoconductivity (PPC) effect. In this letter, we characterize the IR photo-response mechanism through various optical and electrical measurements on the wavelength, optical power, bias-modulated quasi-Fermi level, and photo-responsive states. This result is expected to provide independent and/or integrated IR detector with transparent substrate combined with a-IGZO TFTs.