Abstract: The motivation for his book stems from the complexity of on-wafer measurements and their associated characterization techniques. His intent is to bridge the gap between academic knowledge and real-world silicon design and measurement and also to satisfy the needs of modern RF integrated circuit designers and researchers. Dr. Lourandakis provides a complete and comprehensive guide to performing on-wafer measurements, calibration, and de-embedding of silicon-integrated passive devices. The book opens with an introduction to two basic domains of signal analysis: frequency- and time-domain analysis.
Abstract: Double-threshold method is a typical and simple time-of-flight (TOF) measurement method for time-difference-based ultrasonic flowmeter. Some improvements have been proposed to suppress the cycle-skip phenomenon in double-threshold method. However, there are still some application limitations when the waveform is distorted caused by the environment change, especially the temperature change. This paper proposes a similarity judgment-based double-threshold method to deal with the cycle-skip problem. In this method, time values of three consecutive positive zero-crossing points after the feature point are acquired and five consecutive cycles after the first obtained time are saved. The TOF is automatically selected from three acquired time values according to an adaptive determination function which bases on the similarity between signals from two adjacent measurements. These operations guarantee that the obtained TOF locates on the same positive zero-crossing point in each measurement. The proposed method was validated by both numerical and experimental tests. Comparison between the proposed method and other double-threshold methods shows that the proposed method successfully eliminates cycle-skip phenomenon under different working conditions.
Abstract: This paper establishes an ideal mathematical model for pin-to-pin electrostatic discharge (ESD) firing that takes the axial and radial temperature distribution of the bridgewire, heat release, and the reagent consumption into consideration. The model is solved using the finite difference method, and the ESD firing process is analyzed using the results of the time-varying bridgewire/reagent temperatures and the residual reagent percentages. The effects of the model parameters on the ESD firing voltage are analyzed. A comparison of the ESD test firing voltages and the calculated results and a comparison of the test values of normal capacitor firing voltages and the calculated results both verify that the presented model is effective. The model can be used for the estimation of ESD firing voltage. The theoretical guidance of ESD protection for electric explosive device (EED) was provided.
Abstract: A Denisov-type mode launcher having dimpled-wall tapered waveguide and a helical cut was combined with a set of four synthesized toroidal mirrors to design a converter for TE6,2 cavity mode to TEM0,0 Gaussian mode for a transverse output millimeter-wave gyrotron. A commercially available simulation tool, namely, Surf3d was used to design this mode converter, in which the variation of inside launcher boundaries couples the TE6,2 eigenmode fed to the launcher with its satellite modes, and thus the surface deformations at the radiator transforms TE6,2 cavity mode into a TEM0,0 Gaussian-like profile at the launcher cut aperture. This RF beam in TEM0,0 Gaussian-like profile was fed to a set of four synthesized toroidal mirrors to achieve an energy conservation of 96% and Gaussian fit of 98.9% after phase corrections within 336 mm of envelope length and 75 mm of envelope radius of the mode converter.
Abstract: Traditional methods for estimating land-surface parameters from remotely sensed data generally focus on a single parameter with a specific spectral region, resulting in physical and spatiotemporal inconsistencies in current satellite products. We recently proposed a unified inversion scheme to estimate a suite of parameters simultaneously from both visible and near-infrared and thermal-infrared MODIS data. In this letter, we implemented this scheme to estimate six time-series parameters [leaf area index, fraction of absorbed photosynthetically active radiation, surface albedo, land-surface emissivity, land-surface temperature (LST), and upwelling longwave radiation (LWUP)] from the Visible Infrared Imaging Radiometer Suite (VIIRS) data. Several components of these schemes are refined, including the incorporation of a snow bidirectional reflectance distribution function model, determination of the best band combination, and better estimation of the snow-covered surface emissivity by accounting for the snow-cover fraction. Validation using the measurements at 12 sites of SURFRAD, CarboEuropeIP, and FLUXNET, and intercomparisons with MODIS and Global Land-Surface Satellite products, are carried out: the retrieved albedo, LST, and LWUP achieved accuracies () of 0.77, 0.96, and 0.95, root mean square errors of 0.06, 2.9 K, and 18.3 W/m2, and biases of 0.01, 0.09 K, and −0.08 W/m2, respectively. The retrieved parameters can achieve comparable or higher accuracy than existing products, which indicates that the unified algorithm can be applied effectively to the VIIRS data with high physical and temporal consistency and accuracy.
Autors: Han Ma;Shunlin Liang;Zhiqiang Xiao;Dongdong Wang;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Abstract: Photonic generation of tunable microwave signal has gained the attention of many research communities. Various active components such as vertical-cavity surface-emitting laser diode, semiconductor optical amplifier, and Fabry–Perot laser diode have been used for generating microwave signals using different techniques including side mode injection, feedback injection, and frequency combs. In this paper, we propose and demonstrate a novel approach to generate millimeter wave, simultaneous microwave and millimeter wave, and microwave together with hopping of RF frequency using a single external beam. Furthermore, we demonstrate injecting multiple external beams in a spatial-mode Fabry–Perot laser diode (SMFP-LD) to generate simultaneous multiband signals with negative wavelength detuning. The generated signal ranges from microwave to terahertz. We inject four external beams in SMFP-LD to generate RF frequencies that lie in Ku-, K-, Ka-, V-bands and higher millimeter wave. The frequency of generated signals can be tuned from a few gigahertz to several terahertz. The effects of changing the dominant mode, injecting external beams to different side modes, wavelength and power stability of beating wavelengths, and harmonic generations are analyzed. The maximum linewidth of the generated RF signals with multiple input beams (up to 42.5 GHz) is found to be about 300 kHz.
Autors: Bikash Nakarmi;Shilong Pan;Yong Hyub Won;
Appeared in: IEEE Transactions on Microwave Theory and Techniques
Abstract: We propose and demonstrate an approach for high-sensitivity simultaneous temperature and strain measurement in a dual-core As2Se3-polymethyl methacrylate (PMMA) taper. High measurement sensitivity is achieved by combining the large thermal-expansion coefficient of the PMMA cladding, the low stiffness of the micrometer diameter As2Se3 core, and the large difference between the refractive indices of As2Se3 and PMMA. High measurement sensitivities of −115 pm/°C and −4.21 pm/ are measured from the transmission spectrum of one principal polarization axis of the dual-core fiber, and −35.5 pm/°C and −3.16 pm/ are obtained from the transmission spectrum of the second polarization axis of the dual-core fiber. Decorrelation between the temperature and strain measurement sensitivities of the principal polarization axes is achieved through thermally induced squeezing of the As2Se3 cores by the PMMA cladding due to an order of magnitude difference between the thermal-expansion coefficients of As2Se3 and PMMA, enabling simultaneous measurement of temperature and strain variations with the temperature and strain uncertainty of 0.15 °C and 1.87 .
Autors: Song Gao;Chams Baker;Liang Chen;Xiaoyi Bao;
Abstract: To fully take advantage of the enormous potential of functional nanodevices, it is crucial to automate their manufacture with efficient steering and manipulation of multiple nanowires with controlled orientations to specific spatial locations. In this paper, we present motion planning and control algorithms for simultaneously steering multiple nanowires in liquid suspension. The motion planning and control is designed for a microfluidic device that is actuated by a simple generic set of electrodes. We first present a motion control algorithm to simultaneously steer multiple nanowires along different desired trajectories under controlled electrophoretic forces. A two-stage motion planning algorithm is then presented to generate the desired trajectory for each individual nanowire. Both numerical simulation and experimental results are presented to demonstrate the performance of the motion planning and control design using electric fields to simultaneously steer and manipulate multiple nanowires.
Note to Practitioners—The automated steering and manipulation of multiple nanowires would enable the scalable assembly of nanodevices for a variety of applications. This paper presents an electric-field-based design for simultaneous motion planning and control of multiple nanowires in liquid suspension. The design uses a set of electrode arrays to drive and orient multiple nanowires from their starting locations to targeted locations under electrophoretic forces. The motion control of multiple nanowires in fluid suspension is first presented to steer the nanowires simultaneously along the given trajectories. Then, we present a two-stage motion planning algorithm to generate the total shortest distance trajectories for all nanowires while avoiding collision. We present extensive simulations and experiments to demonstrate the motion planning and control of multiple nanowires to form various geometric patterns. The results will help prov-
de a foundation for scalable automated methods for manipulating nanowires to build nanodevices.
Autors: Kaiyan Yu;Jingang Yi;Jerry Shan;
Appeared in: IEEE Transactions on Automation Science and Engineering
Abstract: We demonstrate simultaneous stabilization of optical and microwave signals on an optical-fiber link by independently stabilizing two optical signals that are separated by a nominated microwave frequency. This system can be implemented on conventional stabilized optical frequency transfer networks without degrading the stability of the optical signal, increasing the scope of applications of existing and future large-scale frequency transfer networks. For a 30 km optical-fiber link, we demonstrate a 193 THz optical carrier transfer absolute frequency stability of Hz at s, and a 10.02 GHz microwave signal transfer absolute frequency stability of Hz at s.
Autors: David R. Gozzard;Sascha W. Schediwy;Keith Grainge;
Abstract: In diffusion MRI (dMRI), a good sampling scheme is important for efficient acquisition and robust reconstruction. Diffusion weighted signal is normally acquired on single or multiple shells in q-space. Signal samples are typically distributed uniformly on different shells to make them invariant to the orientation of structures within tissue, or the laboratory coordinate frame. The electrostatic energy minimization (EEM) method, originally proposed for single shell sampling scheme in dMRI, was recently generalized to multi-shell schemes, called generalized EEM (GEEM). GEEM has been successfully used in the human connectome project. However, EEM does not directly address the goal of optimal sampling, i.e., achieving large angular separation between sampling points. In this paper, we propose a more natural formulation, called spherical code (SC), to directly maximize the minimal angle between different samples in single or multiple shells. We consider not only continuous problems to design single or multiple shell sampling schemes, but also discrete problems to uniformly extract sub-sampled schemes from an existing single or multiple shell scheme, and to order samples in an existing scheme. We propose five algorithms to solve the above problems, including an incremental SC (ISC), a sophisticated greedy algorithm called iterative maximum overlap construction (IMOC), an 1-Opt greedy method, a mixed integer linear programming method, and a constrained non-linear optimization method. To our knowledge, this is the first work to use the SC formulation for single or multiple shell sampling schemes in dMRI. Experimental results indicate that SC methods obtain larger angular separation and better rotational invariance than the state-of-the-art EEM and GEEM. The related codes and a tutorial have been released in DMRITool.1
Abstract: In this paper, a frequency-based analytical approach is presented for dynamic analysis of three-phase balanced systems in the presence of harmonic distortion based on single-phase analysis. By providing mathematical foundation, this study proves that a three-phase balanced system (linear or non-linear, supplied by periodic balanced sinusoidal or non-sinusoidal sources) is completely balanced during both transient and steady-state conditions. This is done by utilizing Dynamic Harmonic Domain (DHD) and defining a phase-shift matrix in frequency domain. As the most noteworthy application of the proposed methodology, single-phase modeling approach is put forward. Therefore, during the transient period, one can analyze only one phase of a three-phase balanced system and calculate exact quantities of the other phases without performing extra simulations, which is not possible through time domain. The introduced concept has been applied to different test cases including three-phase transformer inrush current. In addition, the proposed approach has been utilized to obtain a single-phase model of VSC-based power electronic devices for dynamic harmonic analysis, followed by discussion on results.
Autors: Ehsan Karami;Manuel Madrigal;Gevork B. Gharehpetian;Kumars Rouzbehi;Pedro Rodriguez;
Abstract: Signal-to-noise-plus-interference ratio (SINR) outage probability is among one of the key performance metrics of a wireless network. In this paper, we propose a semi-analytical method based on the saddle point approximation (SPA) technique to calculate the SINR outage of a wireless system whose SINR can be modeled in the form where denotes the useful signal power and denotes the power of the interference signal. Both and can also be random variables. The proposed approach is based on the saddle point approximation to cumulative distribution function as given by Wood-Booth-Butler formula. The approach is applicable whenever the cumulant generating function of the received signal and interference exists, and it allows us to tackle distributions with large skewness and kurtosis with higher accuracy. In this paper, we exploit a four parameter normal-inverse Gaussian (NIG) distribution as a base distribution. Given that the skewness and kurtosis satisfy a specific condition, NIG-based SPA works reliably. When this condition is violated, we recommend SPA based on normal or symmetric NIG distribution, both special cases of NIG distribution, at the expense of reduced accuracy. For the purpose of demonstration, we apply SPA for the SINR outage evaluation of a typical user experiencing a downlink coordinated multi-point transmission from the base stations that are modeled by homogeneous Poisson point process. Numerical results are presented to illustrate the accuracy of the proposed -
et of approximations.
Abstract: Heat transfer through interfaces in nanostructures is becoming ever more important in functional nanodevices. The existence of interface between two dissimilar materials overheats nanoelectronics and impacts heat transfer greatly. It is a challenge how to modulate interface to tailor the thermal transport properties of nanodevices from the perspective of atomic level. In this brief, we consider how size and interface strain affect thermal boundary resistance (TBR) as well as thermal conductivity (TC) of Si/Ge core–shell nanowires (CSNWs) using a thermal kinetic method in terms of atomic-bond-relaxation correlation mechanism and continuum medium mechanics. We propose a theoretical model to pursue the underlying mechanism on the TBR and TC that determined on the core or shell thickness, surface roughness, and interface mismatch. Our approach provides a useful guidance to the theoretical design and experimental control of epitaxial growth in the radial CSNWs for practice applications.
Autors: Liang Zhang;Gang Ouyang;
Appeared in: IEEE Transactions on Electron Devices
Abstract: We present a novel approach for improving the shape statistics of medical image objects by generating correspondence of skeletal points. Each object’s interior is modeled by an s-rep, i.e., by a sampled, folded, two-sided skeletal sheet with spoke vectors proceeding from the skeletal sheet to the boundary. The skeleton is divided into three parts: the up side, the down side, and the fold curve. The spokes on each part are treated separately and, using spoke interpolation, are shifted along that skeleton in each training sample so as to tighten the probability distribution on those spokes’ geometric properties while sampling the object interior regularly. As with the surface/boundary-based correspondence method of Cates et al., entropy is used to measure both the probability distribution tightness and the sampling regularity, here of the spokes’ geometric properties. Evaluation on synthetic and real world lateral ventricle and hippocampus data sets demonstrate improvement in the performance of statistics using the resulting probability distributions. This improvement is greater than that achieved by an entropy-based correspondence method on the boundary points.
Autors: Liyun Tu;Martin Styner;Jared Vicory;Shireen Elhabian;Rui Wang;Junpyo Hong;Beatriz Paniagua;Juan C. Prieto;Dan Yang;Ross Whitaker;Stephen M. Pizer;
Abstract: Scatterplot matrices (SPLOMs) are widely used for exploring multidimensional data. Scatterplot diagnostics (scagnostics) approaches measure characteristics of scatterplots to automatically find potentially interesting plots, thereby making SPLOMs more scalable with the dimension count. While statistical measures such as regression lines can capture orientation, and graph-theoretic scagnostics measures can capture shape, there is no scatterplot characterization measure that uses both descriptors. Based on well-known results in shape analysis, we propose a scagnostics approach that captures both scatterplot shape and orientation using skeletons (or medial axes). Our representation can handle complex spatial distributions, helps discovery of principal trends in a multiscale way, scales visually well with the number of samples, is robust to noise, and is automatic and fast to compute. We define skeleton-based similarity metrics for the visual exploration and analysis of SPLOMs. We perform a user study to measure the human perception of scatterplot similarity and compare the outcome to our results as well as to graph-based scagnostics and other visual quality metrics. Our skeleton-based metrics outperform previously defined measures both in terms of closeness to perceptually-based similarity and computation time efficiency.
Autors: José Matute;Alexandru C. Telea;Lars Linsen;
Appeared in: IEEE Transactions on Visualization and Computer Graphics
Abstract: Skyline queries have wide-ranging applications in fields that involve multi-criteria decision making, including tourism, retail industry, and human resources. By automatically removing incompetent candidates, skyline queries allow users to focus on a subset of superior data items (i.e., the skyline), thus reducing the decision-making overhead. However, users are still required to interpret and compare these superior items manually before making a successful choice. This task is challenging because of two issues. First, people usually have fuzzy, unstable, and inconsistent preferences when presented with multiple candidates. Second, skyline queries do not reveal the reasons for the superiority of certain skyline points in a multi-dimensional space. To address these issues, we propose SkyLens, a visual analytic system aiming at revealing the superiority of skyline points from different perspectives and at different scales to aid users in their decision making. Two scenarios demonstrate the usefulness of SkyLens on two datasets with a dozen of attributes. A qualitative study is also conducted to show that users can efficiently accomplish skyline understanding and comparison tasks with SkyLens.
Abstract: Racetrack memory (RM) has demonstrated great potential as nonvolatile mass storage in future advanced computer architectures. Domain wall (DW)-based RM first proposed in 2008 by IBM, however, suffers from challenges, such as storage density, scalability, and energy consumption. Recently, magnetic skyrmions, topologically protected particle-like spin textures, have expected to replace DWs as new information carriers in the RM design, owing to their superiorities to DWs in terms of topological stability, smaller size, as well as lower driving current density. Extensive investigations have been performed in skyrmion-based RM (Sky-RM) to date. Furthermore, skyrmions exhibits some unique properties that are inaccessible to DWs, thus enabling Sky-RM to explore some new functions that may be inaccessible to DW-RM. In this paper, a novel Sky-RM, capable of random information update/deletion/insertion, is proposed by exploiting the particle-like behaviors of skyrmions. Micromagnetic studies are performed to validate the function and performance of these novel data operations, which may bring performance benefits in data access operations and enable new applications.
Abstract: In this technical note, the sliding-mode control (SMC) problem is investigated for T–S fuzzy-model-based nonlinear Markovian jump singular systems subject to matched/unmatched uncertainties. To accommodate the model characteristics of such a hybrid system, a novel integral-type fuzzy sliding surface is put forward by taking the singular matrix and state-dependent projection matrix into account simultaneously, which is the key contribution of the note. The designed surface contains two important features: 1) local input matrices for different subsystems in the same system mode are allowed to be different; and 2) the matched uncertainties are completely compensated, and the unmatched ones are not amplified during sliding motion. Sufficient conditions for the stochastic admissibility of the corresponding sliding-mode dynamics are presented, and a fuzzy SMC law is constructed to ensure the reaching condition despite uncertainties. The applicability and effectiveness of our approach are verified by simulations on an inverted pendulum system.
Abstract: A smart fire detector preferably reacting before smoke breaks out and providing information about the substance going to start burning, is an unaccomplished hope for fire safety authority since decades. Here, we present an easy method to fabricate, hence cheap, smell detecting electronic nose (e-Nose) which is capable to operate as low cost smart detector for fire-related smells as an example application. Smell sensing in principle is achieved by measuring the resistance pattern of 16 sub-sensor elements combined on a single chip and a subsequent pattern recognition technique using multivariate data analysis. The sensing material of one single sub-sensor is SnO2 nanowires, fabricated in a high temperature condensation process and dispersed on digital aerosol jet printed interdigitated Au structure. Assisted by UV illumination, the basic chip performance was characterized using laboratory gases, such as synthetic air, Isopropanol, CO and Benzene and the detection limit of the e-Nose exposed to Benzene was measured to be 2.2 ppm. It needs only 6.6 mW to activate such sensor for continuous operation. As an application of such system, a smart fire detector was demonstrated, which can not only detect the pre burning smell of several substances, but it can also identify previously taught patterns of burning smell of test substances like, cotton, beech, and PCB.
Abstract: Snow in mountainous areas is a major source of surface water and groundwater recharge in the world. The water balance in mountainous regions is controlled by the interactions between the climate, cryospheric, and hydrological systems. Surface snow grain is a sensitive thermodynamic indicator of snowpack and plays an important role in the snow albedo. In mountainous regions, the complicated terrain conditions may introduce errors in the snow grain size estimated from satellite imagery. In this letter, an effective method based on the Snow Grain-Size and Pollution (SGSP) amount algorithm is proposed to estimate the surface snow grain size with careful topographic correction, using spectral reflectance data in Channel 5 (1.24 ) of the Moderate Resolution Imaging Spectrometer. The SGSP-estimated snow grain size was validated with in situ measurements collected from field campaigns in mountainous areas of Manasi River Basin, China, during the periods of snow accumulation and ablation from 2011 to 2015. The value of 0.90 and root mean squared error of were obtained.
Abstract: Although the development and widespread adoption of software bots has occurred in just a few years, bots have taken on many diverse tasks and roles. This article discusses current bot technology and presents a practical case study on how to use bots in software engineering.
Abstract: Cyber-physical systems (CPSs) offer many opportunities but pose many challenges—especially regarding functional safety, cybersecurity, and their interplay, as well as the systems’ impact on society. Consequently, new methods and techniques are needed for CPS development and assurance. The articles in this theme issue aim to help address some of these challenges.
Abstract: Solution- p-type thin-film transistors, consisting of sol-gel-processed CuO films, were fabricated. The optoelectric properties of sol-gel-processed, CuO-based back gate thin-film transistors were investigated, and a detectivity of (cm Hz was achieved. This detectivity for sol-gel-processed CuO thin-film transistors is higher than that of the previously reported layered two-dimensional material systems and comparable to that of devices based on a one-dimensional nanowire system. Our results indicate that the sol-gel–processed, CuO-based photodetector system is a promising candidate for applications, such as near-infrared imaging devices, sensors, solar cells, and p-type inks for future printed electronics.
Abstract: The voltage solution of DC railway traction power networks is classically obtained via the current injection (CI) method, which is based on solving a sequence of nodal voltage equations. Specialized techniques, which build on the CI method, have been proposed for simulating limited network receptivity due to voltage rise constraints and nonreversible substations. These techniques may require a multitude of power reduction steps for modeling the local controller operation of trains in regenerative braking mode, and they consequently lead to a large computational effort. This paper proposes a sensitivity-based approach for computing the regenerative train power that can be returned to the network without causing over voltage. In the case of nonreceptive substations, each regenerating train is switched to a voltage–current source model and the CI method is used to further adjust the power that can be received by the network; a two-phase approach is used to compute the regenerative train resistance without recourse to iterations. The proposed method is tested on network models with branched lines, detailed return circuits, and having up to 144 trains. The computational performance comparisons show that the proposed method for simulating local controllers can be significantly faster than the classical power reduction method.
Abstract: PTB7/PC71BM bulk heterojunction solar cell devices where the conventional calcium hole-blocking layer has been replaced by a solution processed bathocuproine (BCP) layer is described. The BCP thin film was deposited via spin coating from a dilute solution of BCP in a mixture of toluene and methanol directly on the top of the active layer. The silver cathode was subsequently deposited via thermal evaporation. The study shows that solar cells devices comprising solution-processed BCP show similar performance than devices made from either calcium or evaporated BCP. Moreover, the devices made from solution-processed BCP show superior stability in air than calcium and evaporated BCP-based devices. This is to the best of our knowledge, the first report of the use of solution processed BCP in organic solar cells.
Autors: Caterina Stenta;María Pilar Montero-Rama;Aurelien Viterisi;Werther Cambarau;Emilio Palomares;Lluis F. Marsal;
Abstract: In this letter, an organic field-effect transistor nonvolatile memory (NVM), based on single-walled carbon nanotubes (SWNTs) as a nano floating-gate, is demonstrated, for which a four-layer stacked core architecture was processed by following the sequential solution spin-coating method. The SWNTs, separated by spin-coating, are distributed in the matrix of copolymer poly (styrene-block-paraphenylene) to act as the charge trapping sites. The memory of the floating-gate organic transistor so prepared exhibits excellent NVM characteristics, with a large memory window of 26.7 V, memory on/off ratio larger than 103, stable charge storage retention capability for over s with a memory on/off ratio over 102, and the reliable memory endurance property of over 500 Hz.
Abstract: Clustering is a core building block for data analysis, aiming to extract otherwise hidden structures and relations from raw datasets, such as particular groups that can be effectively related, compared, and interpreted. A plethora of visual-interactive cluster analysis techniques has been proposed to date, however, arriving at useful clusterings often requires several rounds of user interactions to fine-tune the data preprocessing and algorithms. We present a multi-stage Visual Analytics (VA) approach for iterative cluster refinement together with an implementation (SOMFlow) that uses Self-Organizing Maps (SOM) to analyze time series data. It supports exploration by offering the analyst a visual platform to analyze intermediate results, adapt the underlying computations, iteratively partition the data, and to reflect previous analytical activities. The history of previous decisions is explicitly visualized within a flow graph, allowing to compare earlier cluster refinements and to explore relations. We further leverage quality and interestingness measures to guide the analyst in the discovery of useful patterns, relations, and data partitions. We conducted two pair analytics experiments together with a subject matter expert in speech intonation research to demonstrate that the approach is effective for interactive data analysis, supporting enhanced understanding of clustering results as well as the interactive process itself.
Autors: Dominik Sacha;Matthias Kraus;Jürgen Bernard;Michael Behrisch;Tobias Schreck;Yuki Asano;Daniel A. Keim;
Appeared in: IEEE Transactions on Visualization and Computer Graphics
Abstract: Every national spacecraft charging related design guideline or design standard includes prohibitions against floating, or ungrounded, connector pins. The rationale is obvious. A floating connector pin represents ungrounded metal with a propensity to accumulate charge from the space plasma environment and, upon breakdown, effectively couple the discharge energy directly into sensitive system electronics by virtue of adjacent pins and cables. Satellite designers may recognize that, seemingly as common as the rationale is obvious, there are instances in violation of this clear guideline and impassioned arguments for permissions to do so. This paper represents a comprehensive effort to quantitatively, theoretically, analytically, and empirically assess the risk associated with ungrounded connector pins in the selected (geostationary earth orbit and medium earth orbit) orbits.
Autors: Justin J. Likar;Kris Hartojo;George Ott;John Bird;Nigel P. Meredith;
Abstract: In this paper, we present a sparse regression (SpaRe) model-based yield analysis methodology and apply it to memory designs with state-of-the-art write-assist circuitry. At the core of its engine is a mixture importance sampling technique which consists of a uniform sampling stage and an importance sampling stage. The proposed methodology allows for fast and accurate statistical analysis of rare fail events. In our approach, a SpaRe model is built using the uniform sampling stage data points obtained via circuit simulation (CktSim). Along with the model, an optimal threshold value is determined for proper pass/fail predict capability. The model and the threshold value are then used to predict the response in the importance sampling stage. This alleviates the need for CktSims in the latter stage and introduces significant speedup compared to fully CktSim-based approaches. The SpaRe model-based yield analysis is tested on a 14-nm FinFET SRAM design, and the results corroborate well with that of full CktSim-based yield analysis. The methodology is used to compare multiple state-of-the-art SRAM designs including selective boost and write-assist designs. The operating ranges and trends corroborate well with hardware measurements.
Autors: Maria Malik;Rajiv V. Joshi;Rouwaida Kanj;Shupeng Sun;Houman Homayoun;Tong Li;
Appeared in: IEEE Transactions on Very Large Scale Integration Systems
Abstract: This letter shows that the sparse state recovery optimization method is equivalent to the well-known Huber M-estimator, and then justifies its robustness to bad data. We derive the total influence functions of the Huber M-estimator and the generalized maximum-likelihood (GM)-estimator, and give a formal proof that the Huber M-estimator is vulnerable to bad leverage points while the GM-estimator can handle them. Numerical results carried out on various IEEE systems validate our theoretical results.
Abstract: While the accurate delineation of tumor volumes in FDG-positron emission tomography (PET) is a vital task for diverse objectives in clinical oncology, noise and blur due to the imaging system make it a challenging work. In this paper, we propose to address the imprecision and noise inherent in PET using Dempster–Shafer theory, a powerful tool for modeling and reasoning with uncertain and/or imprecise information. Based on Dempster–Shafer theory, a novel evidential clustering algorithm is proposed and tailored for the tumor segmentation task in three-dimensional. For accurate clustering of PET voxels, each voxel is described not only by the single intensity value but also complementarily by textural features extracted from a patch surrounding the voxel. Considering that there are a large amount of textures without consensus regarding the most informative ones, and some of the extracted features are even unreliable due to the low-quality PET images, a specific procedure is included in the proposed clustering algorithm to adapt distance metric for properly representing the clustering distortions and the similarities between neighboring voxels. This integrated metric adaptation procedure will realize a low-dimensional transformation from the original space, and will limit the influence of unreliable inputs via feature selection. A Dempster–Shafer-theory-based spatial regularization is also proposed and included in the clustering algorithm, so as to effectively quantify the local homogeneity. The proposed method has been compared with other methods on the real-patient FDG-PET images, showing good performance.
Abstract: We study optimal geographic content placement for device-to-device () networks in which each file’s popularity follows the Zipf distribution. The locations of the users (caches) are modeled by a Poisson point process and have limited communication range and finite storage. Inspired by the Matérn hard-core (type II) point process that captures pairwise interactions between nodes, we devise a novel spatially correlated caching strategy called hard-core placement () such that the nodes caching the same file are never closer to each other than the exclusion radius. The exclusion radius plays the role of a substitute for caching probability. We derive and optimize the exclusion radii to maximize the hit probability, which is the probability that a given node can find a desired file at another node’s cache within its communication range. Contrasting it with independent content placement, which is used in most prior work, our strategy often yields a significantly higher cache hit probability. We further demonstrate that the strategy is effective for small cache sizes and a small communication radius, which are likely conditions for .
Autors: Derya Malak;Mazin Al-Shalash;Jeffrey G. Andrews;
Appeared in: IEEE Transactions on Wireless Communications
Abstract: We analyze a class of high performance, low decoding-data-flow error-correcting codes suitable for high bit-rate optical-fiber communication systems. A spatially coupled split-component ensemble is defined, generalizing from the most important codes of this class, staircase codes and braided block codes, and preserving a deterministic partitioning of component-code bits over code blocks. Our analysis focuses on low-complexity iterative algebraic decoding, which, for the binary erasure channel, is equivalent to a generalization of the peeling decoder. Using the differential equation method, we derive a vector recursion that tracks the expected residual graph evolution throughout the decoding process. The threshold of the recursion, for asymptotically long component codes, is found using potential function analysis. We generalize the analysis to mixture ensembles consisting of more than one type of component code. We give an example of a mixture ensemble consisting of two component codes, which has better performance than spatially-coupled split-component ensembles consisting of only one component code. The analysis extends to the binary symmetric channel by assuming miscorrection-free component-code decoding. Simple upper bounds on the number of errors correctable by the ensemble are derived. Finally, we analyze the threshold of spatially coupled split-component ensembles under beyond bounded-distance component decoding.
Autors: Lei M. Zhang;Dmitri Truhachev;Frank R. Kschischang;
Appeared in: IEEE Transactions on Information Theory
Abstract: We present a novel approach for spatiotemporal saliency detection by optimizing a unified criterion of color contrast, motion contrast, appearance, and background cues. To this end, we first abstract the video by temporal superpixels. Second, we propose a novel graph structure exploiting the saliency cues to assign the edge weights. The salient segments are then extracted by applying a spectral foreground detection method, quantum cuts, on this graph. We evaluate our approach on several public datasets for video saliency and activity localization to demonstrate the favorable performance of the proposed video quantum cuts compared to the state of the art.
Abstract: We propose and fabricate a dual-emitter light-induced neuromorphic device composed of two light-induced devices with a common collector and base. Two InGaN multiple-quantum-well diodes (MQW-diodes) are used as the emitters to generate light, and one InGaN MQW-diode is used as the common collector to absorb the emitted light. When the presynaptic voltages are synchronously applied to the two emitters, the collector demonstrates an adding together of the excitatory postsynaptic voltage (EPSV). The width and period of the two input signals constitute the code to generate spatial summation and recognition effects at the same time. Experimental results confirm that temporal summation caused by the repetitive-pulse facilitation could significantly strengthen the spatial summation effect due to the adding together behavior when the repetitive stimulations are applied to the two emitters in rapid succession. Particularly, the resonant summation effect occurs at the cosummation region when the two repetitive-pulse signals have a resonant period, which offers a more sophisticated spatiotemporal EPSV summation function for the dual-emitter neuromorphic device.
Abstract: The combination of massive multiple-input multiple-output (MIMO) and single-carrier (SC) aided spatial modulation (SM), is recently proposed for uplink multi-user transmission over dispersive channels, which has also attracted plenty of research interest. In this letter, first the spectral efficiency (SE) lower bound with non-uniform power allocation for uplink single-cell massive SC-SM MIMO systems is proposed, in which, the base station (BS) applies maximum ratio combining and many non-ideal factors of the wireless channels are all considered. Then, a barrier function-based gradient projection method is proposed to allocate power of each transmit antenna (TA) in terms of SE maximization. The SE lower bound is shown to be tight via simulation results, and simulation results also show that the SE gain introduced by our proposed PA algorithm is mainly dependent on the TA correlation and number of TAs.
Abstract: We propose spin torque nano-oscillators (STNOs) directly integrated on a metal-oxide-semiconductor field-effect-transistor (mosfet). In this model, we consider an array of STNOs, where the STNOs are synchronized via magnetodipolar interaction. We found that the ac voltage generated by magnetization precession of STNOs directly integrated on a mosfet can be amplified by the normally-on mosfet. We also found that the load resistance plays an important role with respect to increasing the output voltage of synchronized STNOs compared to a single STNO and in relation to the gate voltage of the mosfet. By using numerical calculation, we found that the emitted microwave power is greatly enhanced by amplifying the ac voltage generated by synchronized STNOs. It is anticipated that the results will be verified with existing experimental techniques.
Autors: Doo Hyung Kang;Jaehyun Lee;Woo Jin Jeong;Mincheol Shin;
Abstract: Split-type dual-band bandpass filters (DB-BPFs) with symmetric/asymmetric response are presented in this letter. Two different responses are achieved by placing transmission zeros inside the different position of the virtual wide passband, which originates from two-pole wideband BPF. Presented with the equivalent circuit of the coupling structure, the analytical formulas of the structure based on the /4 stepped impedance resonators are derived according to the synthesized coupling matrix. Compared with the conventional capacitive-coupled filters, low insertion loss and relieving the limitations of fabrication process can be obtained. Moreover, the proposed DB-BPFs have low insertion losses, good return losses, high selectivity, and wide stopband.
Abstract: Thin films of Fe have been epitaxially sputtered on GaAs substrates with native oxide removal prior to the deposition carried out by an Ar ion milling. Films grown at substrate temperatures above 100 °C show well-defined fourfold anisotropies. The onset of epitaxial growth is accompanied by an increase in the surface roughness with growth occurring in a distinct island-like pattern. The Fe layers show significantly reduced moments, which decrease with increasing temperature. Antiferromagnetic coupling between Fe layers with Cr spacers was measured in a multilayer with a Cr thickness of 2.7 nm, around the second antiferromagnetic peak. The magnetic properties of the films are discussed in the context of multilayer storage applications.
Autors: R. Mansell;D. C. M. C. Petit;A. Fernández-Pacheco;R. Lavrijsen;J. H. Lee;R. P. Cowburn;
Abstract: The problem of limited labeled training samples is challenging for the classification of remote sensing imagery. We develop a joint classification and segmentation algorithm to address this problem. Our algorithm combines semisupervised learning and conditional random fields (CRFs) into a single framework. The multimodal Gaussian maximum-likelihood classifier is used to estimate the probabilities for the unary potentials of the CRF. Unlike traditional methods based on random fields, region merging is concatenated with the CRF inference to reduce the number of nodes iteratively. Moreover, a semisupervised technique called self-training is used, which iteratively enlarges the training sample set and retrains the classifier. The selection of training samples is based on the region information, so that the risk of assigning wrong labels is largely reduced. The proposed algorithm is applied to hyperspectral image classification, and results on benchmark data sets show that the proposed algorithm significantly improves classification performance after using self-training, and outperforms state-of-the-art spectral–spatial methods for limited labeled training samples.
Autors: Fan Li;David A. Clausi;Linlin Xu;Alexander Wong;
Appeared in: IEEE Transactions on Geoscience and Remote Sensing
Abstract: We propose a method that uses piecewise positive comparison systems to analyze the stability of nonlinear differential systems with time-varying delays. A new stability criterion is provided and two numerical examples are given to demonstrate the advantages of our obtained result.
Abstract: This paper addresses the stability problem of linear systems with a time-varying delay. Hierarchical stability conditions based on linear matrix inequalities are obtained from an extensive use of the Bessel inequality applied to Legendre polynomials of arbitrary orders. While this inequality has been only used for constant discrete and distributed delays, this paper generalizes the same methodology to time-varying delays. We take advantages of the dependence of the stability criteria on both the delay and its derivative to propose a new definition of allowable delay sets. A light and smart modification in their definition leads to relevant conclusions on the numerical results.
Autors: Alexandre Seuret;Frédéric Gouaisbaut;
Appeared in: IEEE Transactions on Automatic Control
Abstract: In this paper, we investigate the almost sure stability of switched systems on randomly switching durations simultaneously with randomly switching interaction matrices. We not only allow the interaction matrix on each switching duration to take values randomly from either a countable, an uncountable, or even an unbounded state space, but also allow the corresponding probability density function to be time varying with the switching. We provide an example to show the difference between the almost sure stability and the moment stability. Then, we establish several practical stability criteria for switched systems, which may have linear or nonlinear subsystems. These stability criteria also enable us to find suitable conditions for realizing almost sure synchronization in complex networks, such as small-world networks, with both randomly switching durations and a few switching couplings that take values randomly in either an uncountable or an unbounded state space.
Autors: Yao Guo;Wei Lin;Guanrong Chen;
Appeared in: IEEE Transactions on Automatic Control
Abstract: Treemaps are a popular tool to visualize hierarchical data: items are represented by nested rectangles and the area of each rectangle corresponds to the data being visualized for this item. The visual quality of a treemap is commonly measured via the aspect ratio of the rectangles. If the data changes, then a second important quality criterion is the stability of the treemap: how much does the treemap change as the data changes. We present a novel stable treemapping algorithm that has very high visual quality. Whereas existing treemapping algorithms generally recompute the treemap every time the input changes, our algorithm changes the layout of the treemap using only local modifications. This approach not only gives us direct control over stability, but it also allows us to use a larger set of possible layouts, thus provably resulting in treemaps of higher visual quality compared to existing algorithms. We further prove that we can reach all possible treemap layouts using only our local modifications. Furthermore, we introduce a new measure for stability that better captures the relative positions of rectangles. We finally show via experiments on real-world data that our algorithm outperforms existing treemapping algorithms also in practice on either visual quality and/or stability. Our algorithm scores high on stability regardless of whether we use an existing stability measure or our new measure.
Autors: Max Sondag;Bettina Speckmann;Kevin Verbeek;
Appeared in: IEEE Transactions on Visualization and Computer Graphics
Abstract: This article presents the main revisions, updates, and additional materials that have been included in the IEEE 1566 adjustable-speed drive (ASD) standard first published in 2005. This revised standard includes suggestions and additions received from end users, manufacturers, and consultants that reflect both field experience and advances made over the past ten years.
Autors: Roger Lawrence;Robert Hanna;Bill Lockley;Richard Paes;
Abstract: Welcome to 2018's first issue of the IEEE Transactions on Parallel and Distributed Systems (TPDS). I'm excited with my new role as incoming Editor-in-Chief (EIC) of TPDS and look forward to serving the community over the next few years. My goal as EIC is to continue to work on increasing the visibility and relevance and impact of TPDS, as well as the quality and timeliness of the review process, to ensure that TPDS is the premier Transactions in the field. The IEEE is a hallmark of quality for technical publication. The value TPDS brings to the international community is in its collection of the highest quality research that is relevant to academia, industry, and laboratories. I will investigate new opportunities for TPDS to capture the best research while maintaining its emphasis on highest quality papers. TPDS also needs to respond to a dynamic and rapidly evolving research and publication landscape. As EIC, I will work with the IEEE community to ensure that TPDS does respond appropriately, and will carefully work with the editorial board to revisit the scope and recruit new editorial board members as needed. An important and rapid growing conversation is related to the repeatability of published research and the submission of supplementary material such as code and data. I am part of this conversation, and will work with the EB and the community to explore how to bring these practices in meaningful and measured ways to TPDS.
Autors: Manish Parashar;
Appeared in: IEEE Transactions on Parallel and Distributed Systems
Abstract: A statistical beamforming (SBF) scheme based on the effective channel gain (ECG) is proposed for spatially correlated massive multiple-input multiple-output systems. The proposed SBF scheme consists of outer and inner precoders. The outer precoder is designed to eliminate multiuser interference based on the correlation matrix of downlink channel. Then, according to the ECG defined as the squared inner product of the dedicated channel and an arbitrary precoding vector, the inner precoder is selected among the eigenvectors of the dedicated channel’s correlation matrix with the maximum ECG. Simulation results show that the proposed SBF scheme outperforms conventional schemes.
Abstract: Untethered miniature robotics have recently shown promising results in several scenarios at the microscale, such as targeted drug delivery, microassembly, and biopsy procedures. However, the vast majority of these small-scale robots have very limited manipulation capabilities, and none of the steering systems currently available enables humans to intuitively and effectively control dexterous miniaturized robots in a remote environment. In this paper, we present an innovative microteleoperation system with haptic assistance for the intuitive steering and control of miniaturized self-folding soft magnetic grippers in 2-D space. The soft grippers can be wirelessly positioned using weak magnetic fields and opened/closed by changing their temperature. An image-guided algorithm tracks the position of the controlled miniaturized gripper in the remote environment. A haptic interface provides the human operator with compelling haptic sensations about the interaction between the gripper and the environment as well as enables the operator to intuitively control the target position and grasping configuration of the gripper. Finally, magnetic and thermal control systems regulate the position and grasping configuration of the gripper. The viability of the proposed approach is demonstrated through two experiments involving 26 human subjects. Providing haptic stimuli elicited statistically significant improvements in the performance of the considered navigation and micromanipulation tasks.
Note to Practitioners—The ability to accurately and intuitively control the motion of miniaturized grippers in remote environments can open new exciting possibilities in the fields of minimally invasive surgery, micromanipulation, biopsy, and drug delivery. This paper presents a microteleoperation system with haptic assistance through which a clinician can easily control the motion and open/close capability of miniaturized wireless soft grippers. It intr-
duces the underlying autonomous magnetic and thermal control systems, their interconnection with the master haptic interface, and an extensive evaluation in two real-world scenarios: 1) following of a predetermined trajectory and 2) pick-and-place task of a microscopic object.
Autors: Claudio Pacchierotti;Federico Ongaro;Frank van den Brink;ChangKyu Yoon;Domenico Prattichizzo;David H. Gracias;Sarthak Misra;
Appeared in: IEEE Transactions on Automation Science and Engineering
Abstract: The numerical analysis of inter-core crosstalk in multicore fibers (MCFs) based on a novel theoretical approach that includes stimulated Raman scattering (SRS) and four-wave mixing (FWM) nonlinearities in the presence of random perturbations is presented. The coupled propagation equations can be employed to numerically analyze wavelength-division multiplexed systems with homogenous and heterogeneous cores. Propagation of ten optical channels, 200-GHz spaced, along 10 km of a homogeneous two-core fiber shows that the wavelength dependence of the relative average inter-core crosstalk induced by SRS and FWM is comparable with the one produced by only considering the wavelength dependence of the linear coupling coefficient, thus allowing tuning of the overall effect. Our formalism represents a valuable tool in the design of future multi-channel MCF systems.
Autors: D. E. Ceballos-Herrera;R. Gutierrez-Castrejon;J. A. Alvarez-Chavez;
Abstract: The increasing prevalence of electric vehicles (EVs) calls for the effective planning of the charging infrastructure. In this study, a multi-objective, multistage collaborative planning model is proposed for the coupled EV charging station infrastructure and power distribution network. The planning model aims to minimize the investment and operation costs of the distribution system while maximize the annually captured traffic flow. The uncertainties of EV charging loads are modeled for three different types of charging stations. The FISK's stochastic traffic assignment model is utilized to model realistic traffic flows. And a new class of volume-delay functions, conical congestion functions, is employed to overcome the shortcomings of the conventional Bureau of Public Roads function. The multi-objective evolutionary algorithm based on decomposition (MOEA/D) algorithm is applied to find the nondominated solutions of the proposed collaborative planning model. Finally, simulations based on a 54-node distribution system are conducted to validate the effectiveness of the proposed method.
Autors: Shu Wang;Zhao Yang Dong;Fengji Luo;Ke Meng;Yongxi Zhang;
Appeared in: IEEE Transactions on Industrial Informatics
Abstract: An oscillator-based true random number generator (TRNG) is experimentally demonstrated by exploiting inherently stochastic threshold switching in the insulator-to-metal transition (IMT) in vanadium dioxide. Through experimentation and modeling, we show that the origin of stochasticity arises from small perturbations in the nanoscale domain structure, which are then subsequently amplified through a positive feedback process. Within a 1T1R oscillator, the stochastic cycle-to-cycle variations in the IMT trigger voltage result in random timing jitter, which is harnessed for a TRNG. The randomness of the IMT TRNG output is validated using the NIST SP800-22 statistical test.
Autors: Matthew Jerry;Kai Ni;Abhinav Parihar;Arijit Raychowdhury;Suman Datta;
Abstract: The letter provides a thorough stochastic analysis of the impact of energy storage systems on the transient stability of transmission grids. This impact is evaluated considering the combined effect of different energy storage technologies, fault clearing times, and network topologies. The latter concerns the relative positions of faults, storage devices, and synchronous machines. The case study consists of stochastic time-domain simulations carried out for the all-island, 1479-bus model of the Irish transmission system that includes a real-world hybrid storage device. Results lead to some nonintuitive conclusions.
Abstract: In late August 2017, media out lets began reporting on the U.S. State Department's disclosure that Havana-based U. S. diplomats were experiencing health issues -. Their residences were described as having been targeted with bursts of sound waves. Diplomat ic staff and family members have repeatedly reported hearing loud buzzing or scraping sounds. Symptoms include severe hearing loss, headaches, ringing in the ears, nausea, and problems with balance or vertigo, which are suggestive of a connection to the inner ear apparatus within the human head.
Abstract: The coordination of various energy vectors under the concept of multi-energy system (MES) has introduced new sources of operational flexibility to system managers. In this paper, the behavior of multi-energy players (MEP) who can trade with more than one energy carrier to maximize their profits and mitigate their operational risks has been investigated. The MES is represented based on a multilayer structure, namely the energy market, MEP, the local energy system (LES), and multi-energy demand. In such environment, an MEP aggregates LES and participates in the wholesale electricity market, simultaneously to maximize its profit. The decision-making conflict of the MEP with other energy players for the aggregation of LES and participation in the electricity market is modeled based on a bilevel approach. Numerical results show the behavior of the MEP as a prosumer in the electricity market to produce smoother demand and price profiles. Results reveal a mutual effect of local and wholesale equilibrium prices by increasing the share of the MEP.
Autors: Maziar Yazdani-Damavandi;Nilufar Neyestani;Miadreza Shafie-khah;Javier Contreras;João P. S. Catalão;
Abstract: This paper proposes a stochastic bilevel program for strategic bidding of a hydropower producer. The price, quantity and ramp-rate bids are considered. The uncertainty of wind power generation, variation of inflows for the hydropower producer, and demand variability are modeled through the moment-matching scenario generation technique. Using discretization the stochastic bilevel program is reformulated as a stochastic mixed-integer linear program (MILP) with disjunctive constraints. We propose a modified Benders decomposition algorithm (MBDA), which fully exploits the disjunctive structure of reformatted MILP model. More importantly, the MBDA does not require optimal tuning of disjunctive parameters and it can be efficiently parallelized. Through an illustrative 5-node example, we identify possible strategies (specific to a hydropower producer) for maximizing profit, which in turn leads to market insights. We also use the IEEE 24-node, 118-node, and 300-node case studies to show how our parallelized MBDA outperforms the standard benders decomposition algorithm. The parallelized MBDA is also compared to the state-of-the-art CPLEX solver.
Abstract: The wide integration of gas-fired units and implementation of power-to-gas technologies bring increasing interdependence among the natural gas and electricity infrastructures. This paper studies the equilibrium of the coupled gas and electricity markets, which is driven by the strategic offering behaviors: each producer endeavours to maximize its own profit by taking the market clearing process into consideration. The market equilibrium can be obtained from an equilibrium problem with equilibrium constraints. A special diagonalization algorithm is devised, in which the unilateral equilibrium of the gas or electricity market is found in the inner loop given the rivals’ strategies; the interactions of the two markets are tackled in the outer loop. Case studies on two test systems validate the proposed methodology.
Abstract: The ability to calculate rigid-body transformations between arbitrary coordinate systems (i.e., registration) is an invaluable tool in robotics. This effort builds upon previous work by investigating strategies for improving the registration accuracy between a robotic arm and an extrinsic coordinate system with relatively inexpensive parts and minimal labor. The framework previously presented is expanded with a new test methodology to characterize the effects of strategies that improve registration performance. In addition, statistical analyses of physical trials reveal that leveraging more data and applying machine learning are two major components for significantly reducing registration error. One-shot peg-in-hole tests are conducted to show the application-level performance gains obtained by improving registration accuracy. Trends suggest that the maximum translation positioning error (postregistration) is a good, albeit not perfect, indicator for peg insertion performance.
Note to Practitioners—In a dynamic robotic workcell environment where robots may be frequently relocated or may need to collaborate with other robots, it is simpler and more robust to program robots in an external or unifying reference frame. The process of robot registration involves finding the location of a robot with respect to another reference frame. For instance, if parts are in known locations on a table and a robot can locate itself with respect to the table (an external reference frame), then the robot will also know the location of the parts. Furthermore, if two or more robots can locate themselves with respect to the table, then each robot will not only know the location of the parts, but also the location of every other robot. This knowledge facilitates the coordination of robot motions and robot collaboration and eases the integration of additional robots into the workcell. Since robot registration is critically necessary and occurs freq-
ently, its process needs to be inexpensive, fast, and accurate. This paper details the requirements for a relatively inexpensive and fast robot registration experience, along with detailing strategies that incur significant improvements to registered robot positioning accuracy with minimal overhead. A quantitative verification process is presented to evaluate the performance impacts of these strategies. Peg-in-hole experiments are conducted to validate the notion that more accurate robot registration translates to more reliable task-level performance.
Autors: Karl Van Wyk;Jeremy A. Marvel;
Appeared in: IEEE Transactions on Automation Science and Engineering
Abstract: Urban forms at human-scale, i.e., urban environments that individuals can sense (e.g., sight, smell, and touch) in their daily lives, can provide unprecedented insights on a variety of applications, such as urban planning and environment auditing. The analysis of urban forms can help planners develop high-quality urban spaces through evidence-based design. However, such analysis is complex because of the involvement of spatial, multi-scale (i.e., city, region, and street), and multivariate (e.g., greenery and sky ratios) natures of urban forms. In addition, current methods either lack quantitative measurements or are limited to a small area. The primary contribution of this work is the design of StreetVizor, an interactive visual analytics system that helps planners leverage their domain knowledge in exploring human-scale urban forms based on street view images. Our system presents two-stage visual exploration: 1) an AOI Explorer for the visual comparison of spatial distributions and quantitative measurements in two areas-of-interest (AOIs) at city- and region-scales; 2) and a Street Explorer with a novel parallel coordinate plot for the exploration of the fine-grained details of the urban forms at the street-scale. We integrate visualization techniques with machine learning models to facilitate the detection of street view patterns. We illustrate the applicability of our approach with case studies on the real-world datasets of four cities, i.e., Hong Kong, Singapore, Greater London and New York City. Interviews with domain experts demonstrate the effectiveness of our system in facilitating various analytical tasks.
Abstract: String similarity search is a fundamental query that has been widely used for DNA sequencing, error-tolerant query auto-completion, and data cleaning needed in database, data warehouse, and data mining. In this paper, we study string similarity search based on edit distance that is supported by many database management systems such as Oracle and PostgreSQL. Given the edit distance, , between two strings, and , the string similarity search is to find every string in a string database which is similar to a query string such that for a given threshold . In the literature, most existing work takes a filter-and-verify approach, where the filter step is introduced to re-
uce the high verification cost of two strings by utilizing an index built offline for . The two up-to-date approaches are prefix filtering and local filtering. In this paper, we study string similarity search where strings can be either short or long. Our approach can support long strings, which are not well supported by the existing approaches due to the size of the index built and the time to build such index. We propose two new hash-based labeling techniques, named label and label, for string similarity search. We assign a hash-label, , to a string , and prune the dissimilar strings by comparing two hash-labels, and , for two strings and
Autors: Hao Wei;Jeffrey Xu Yu;Can Lu;
Appeared in: IEEE Transactions on Knowledge and Data Engineering
Abstract: Signatures alignment and reference selection are an important task for signature verification. Due to inherent variability of the acquired signature, a novel technique called stroke point warping (SPW) is proposed. After incorporating the SPW technique, the normalized correlation coefficient of two signatures from the same signer is improved. A novel reference selection strategy is also proposed by combining the SPW method and the normalization of signature support. Two functional features based on shape signature and instantaneous phase are introduced. The corresponding global features, i.e., entropy of the shape signature and the first two statistical moments of instantaneous phase are also derived. Further, a novel fusion technique is proposed in this paper, where the global features (derived from dynamic signature profile) are combined with functional reference signature-based scores. In the signature verification framework, the number of sample signatures available for a person is small compared with the available features. The minimum redundancy maximum relevance method is applied to rank the features. After feature selection, the support vector machine-based verification is evaluated. The proposed algorithm, evaluated on the task 2 SVC2004 database, achieves the equal error rate of 1%, which is better than the state-of-the-art algorithms.
Autors: Biswajit Kar;Anirban Mukherjee;Pranab K. Dutta;
Appeared in: IEEE Transactions on Instrumentation and Measurement
Abstract: Structural, electronic and magnetic properties of the Heusler alloy Mn2VIn have been investigated using the density functional theory and experimental techniques. Unlike many other Heusler compounds, Mn2VIn is not predicted to be half-metallic at the optimized lattice constant, but is highly spin polarized at a slightly lower lattice constant. It however exhibits ferrimagnetic coupling between the Mn and V sublattices, as expected of Mn-based Heuslers. We have, then, synthesized the compound by arc melting and studied magnetic properties that are of interest fundamentally and for technological applications. The structural properties were determined using X-ray diffraction, revealing the presence of cubic and tetragonal phases in the sample. The chemical composition was determined using energy-dispersive X-ray spectroscopy together with the scanning electron microscope, and the magnetic properties were investigated by superconducting quantum interference device magnetometry. The alloy exhibits superparamagnetic spin blocking with a blocking temperature of 40 K.
Autors: Zipporah W. Muthui;Robinson J. Musembi;Julius M. Mwabora;Ralph Skomski;Arti Kashyap;
Abstract: We present a signal-processing framework for image-assisted geometry measurement in the image-based rendering (IBR). We study the utilized geometry information and estimating minimum sampling rate of the IBR. Our method combines decomposing a complex scene geometry into a collection of simpler structures on a block-by-block basis. The automatic simpler structure selection can be interactively refined by detected single salient points. In this manner, we reduce the spectral analysis problem of an irregular object to that of a simpler structure. Predictions on the frequency content can then be used to control the sampling rate. This extends previous work in which the IBR sampling is analyzed and estimated for nonuniform sampling. Extensive experimental evaluation demonstrates that our geometry simplification method significantly outperforms competing algorithms. Additionally, the minimum sampling rate of the IBR necessary for alias-free rendering will be reduced as the number of simpler structures increases.
Autors: Changjian Zhu;Hong Zhang;Li Yu;
Appeared in: IEEE Transactions on Instrumentation and Measurement
Abstract: We present a novel method to segment instances of glandular structures from colon histopathology images. We use a structure learning approach which represents local spatial configurations of class labels, capturing structural information normally ignored by sliding-window methods. This allows us to reveal different spatial structures of pixel labels (e.g., locations between adjacent glands, or far from glands), and to identify correctly neighboring glandular structures as separate instances. Exemplars of label structures are obtained via clustering and used to train support vector machine classifiers. The label structures predicted are then combined and post-processed to obtain segmentation maps. We combine hand-crafted, multi-scale image features with features computed by a deep convolutional network trained to map images to segmentation maps. We evaluate the proposed method on the public domain GlaS data set, which allows extensive comparisons with recent, alternative methods. Using the GlaS contest protocol, our method achieves the overall best performance.
Autors: Siyamalan Manivannan;Wenqi Li;Jianguo Zhang;Emanuele Trucco;Stephen J. McKenna;
Abstract: Mock-ups are rapid, low fidelity prototypes, that are used in many design-related fields to generate and share ideas. While their creation is supported by many mature methods and tools, surprisingly few are suited for the needs of information visualization. In this article, we introduce a novel approach to creating visualizations mock-ups, based on a dialogue between graphic design and parametric toolkit explorations. Our approach consists in iteratively subdividing the display space, while progressively informing each division with realistic data. We show that a wealth of mock-ups can easily be created using only temporary data attributes, as we wait for more realistic data to become available. We describe the implementation of this approach in a D3-based toolkit, which we use to highlight its generative power, and we discuss the potential for transitioning towards higher fidelity prototypes.
Autors: Romain Vuillemot;Jeremy Boy;
Appeared in: IEEE Transactions on Visualization and Computer Graphics
Abstract: Obtaining the land vehicle’s position, azimuth and attitudes autonomously and accurately is significant for vehicle-based weapon’s combat effectiveness. High performance inertial navigation system (INS) can provide high precision attitudes and azimuth reference information, however, it is usually very expensive. In addition, due to gyroscope drifts and accelerometer biases, INS navigation errors would diverge with time. To solve the problem, this paper proposed an integrated positioning and orientation method based on the FOG single-axis rotational INS (FRINS) and the odometer (OD). The proposed method adopted the rotation modulation technique to suppress the inertial sensor errors, particularly -axis FOG drift, by which the navigation accuracy, especially the azimuth accuracy, can be improved. At the same time, the proposed method integrated the FRINS with OD to suppress INS error’s divergence with time. Combining the above rotation modulation technique and the integration of FRINS and OD, the proposed method could improve the integrated system positioning and orientation accuracy as well as reduce the integrated system cost. This paper presented the FRINS/OD integrated navigation system configuration, established the FRINS/OD integrated system errors model, and then verified the performance of proposed method by simulations. The results show that the proposed method could achieve positioning accuracy of 0.03% (of total traveled distance) and orientation of ±20, respectively, using rotational INS with FOGs of 0.1°/h and accelerometers of 500 ug.
Abstract: Two wide-angle scanning linear array antennas (E- and H-planes scanning linear array antenna) are studied and presented. In order to improve the wide-angle scanning performance of the phased array antenna, a wide beamwidth U-shaped microstrip antenna with the electric walls is designed. The wide-angle scanning linear array antennas are studied in the frequency band from 3.2 to 3.8 GHz. The 3 dB beamwidth of the antenna is 140° in the E-plane scanning linear array center and 220° in the H-plane scanning linear array center at 3.5 GHz. The main beams of the H-plane scanning linear array antenna can scan from −90° to +90° with a gain fluctuation less than 3 dB and a maximum sidelobe level (SLL) less than −5 dB. Simultaneously, the main beam of the E-plane scanning linear array antenna can scan from −75° to +75° with a gain fluctuation less than 3 dB and SLL less than −5 dB. The H- and E-planes scanning linear array antennas with nine elements are fabricated and tested. The measured results have a good agreement with the simulation results.
Abstract: In this letter, the design, fabrication, and characterization of an SU-8 GPON diplexer based on directional couplers are presented. The polymeric devices on SiO2/Si lower cladding substrate were directly written by introducing H-nu 470 photoinitiator, which provides substantial improvement in mechanical and thermal stability, reliability, and low loss, allowing flexible prototyping through H-line lithography at a 405-nm wavelength. Design of the filters and waveguide processing and fabrication are described, and the experimental results of the designed diplexer are shown.
Autors: Jhonattan C. Ramirez;Celio A. Finardi;Roberto R. Panepucci;
Abstract: Voltage instability occurs when a power system is unable to meet the reactive power demand, and is typically corrected by switching on additional reactive power devices such as capacitor banks. Real-time monitoring and communication technologies can potentially improve voltage stability by enabling the rapid detection of low voltages and the implementation of corrective actions. These corrective actions, however, will only be effective in restoring stability if they are chosen in a timely, scalable manner. In this paper, we propose a submodular optimization approach for designing a control strategy that prevents voltage instability. Our key insight is that the voltage deviation from the desired level is a supermodular function of the set of reactive power injections that are employed, leading to computationally efficient control algorithms for stabilization with provable optimality guarantees. This submodular control framework is tested on the IEEE 300-bus transmission system.
Abstract: Co1−xZnxFe2O4 ferrites (–1) were successfully synthesized, for the first time, via sol-gel auto-combustion route using gelatin fuel. The auto-combustion was characterized using DTA-TG-DSC up to ferrite formation, and an appropriate gelation mechanism was suggested. The structural, morphological, magnetic, and electrical properties were investigated through X-ray diffraction (XRD), Fourier transform infrared (FT-IR), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), ac-conductivity, and dielectric constant measurements. XRD indicated the need for further calcination at 350 °C to obtain well crystalline ferrites. The slight changes in the lattice values up to suggested the substitution of Zn2+ ions for the Co2+ ions located in the octahedral sites. The large change at suggested the conversion into the normal spinel structure. Based on the structural data, an appropriate distribution for cations was suggested. This distribution was reinforced using FT-IR and magnetic measurements. TEM showed dense agglomeration at low substitutions released by increasing Zn-content. VSM exhibited hard magnetic properties with an obvious transition from ferromagnetic to paramagnetic by increasing zinc. The maximum saturation magnetization (56.7 emu/g) was obtained for Co0.8Zn0.2Fe2O4. The behavior of magnetization with Zn-substitution was explained in the view of the cationic stoichiometry. The coercivity decreases by increasing zinc, which was attributed to the anisotropic nature of z-
nc. AC-conductivity versus temperature revealed a semiconducting behavior with an obvious change from ferro- to paramagnetic by rising temperature. The conduction mechanism as well as the type of the charge carriers was discussed in the view of calculated activation energies and the frequency dependence of conductivity. The measured dielectric constants gave results that agreed well with the conductivity data.
Autors: M. A. Gabal;N. H. Al-Zahrani;Y. M. Al Angari;A. Saaed;
Abstract: In this technical note we study the delayed impulsive control of nonlinear differential systems, where the impulsive control involves the delayed state of the system for which the delay is state-dependent. Since the state dependence of the delay makes the impulsive transients dependent on the historical information of the states, which means that it is hard to know exactly a priori how far in the history the information is needed, the main challenge is how to determine the historical states. We resolve this challenge and establish some sufficient conditions for local stability of nonlinear differential systems with state-dependent delayed impulsive control based on impulsive control theory. Two examples are given to show the effectiveness of the proposed approach.
Autors: Xiaodi Li;Jianhong Wu;
Appeared in: IEEE Transactions on Automatic Control
Abstract: In this letter, the application of super-resolution (SR) techniques to GaoFen(GF)-4, which is the most advanced geostationary-orbit earth observing satellite in China, remote sensing images is investigated and tested. One of the shortcomings of the geostationary-orbit-based earth observing satellite is the limitation of spatial resolution. However, human beings never stop pursuing higher resolution in images. This is the first experiment of applying SR to a sequence of low-resolution (LR) images captured by GF-4 within a short time period. One of the barriers for applying SR to remote sensing images is the large time gaps between those LR image acquisition, because the reflection characteristic of the ground may change within the time period when those LR images were captured. However, GF-4 has the unique advantage of capturing a sequence of LR images of the same region in minutes, i.e., working as a staring camera from the point view of SR. The reconstructed high-resolution images of some regions in Beijing and Hainan are shown and evaluated in this letter. This letter demonstrates that the application of SR to geostationary-orbit-based earth observation data is feasible and valuable, and it has the potential to be applied to the images acquired by all other geostationary-orbit-based earth observing systems.
Abstract: High-resolution scanning radar mapping of the surface is an effective tool for addressing concerns in local environmental and social investigation fields. Regrettably, the azimuth resolution of a scanning radar is constrained by the antenna beamwidth. Multiple super-resolution approaches have been applied to the scanning radar to enhance the azimuth resolution, but they suffer from limited resolution improvement. In this paper, a methodology to derive surface estimates from the scanning radar at an improved azimuth resolution is proposed. We first consider the truncated spectrum by discarding the unreliable frequencies to suppress the noise amplification. Then, based on the iterative adaptive approach (IAA), a novel inverse filtering method is formulated to obtain lower sidelobes and a higher resolution. Finally, by taking advantage of the Fourier property of the steering matrix and the Toeplitz structure of the covariance matrix, we exploit the Gohberg-Semencul representation and the data-dependent trigonometric polynomials to derive a fast IAA (FIAA)-based inverse filtering to mitigate the computational burden. Simulation results and real data processing demonstrate that the proposed FIAA-based inverse filtering outperforms the existing super-resolution approaches in resolution improvement and results in a higher computational efficiency.
Abstract: Multimodule disk explosive magnetic generators (DEMGs) of microsecond pulses of electromagnetic energy up to hundreds of megajoules, based on the internal explosive energy into electromagnetic energy conversion (magnetic flux compression), are reviewed. Fundamentals of the DEMG operation are outlined. Conventional DEMGs with intricate disk profile are described in short. A numerical technique of DEMG simulations is outlined. Special attention is given to the modernized DEMGs with flat modules of different calibers. At preservation of the output characteristics of the DEMGs with profile discs, the factor of the explosive to electromagnetic energy conversion of the DEMGs with flat discs is twofold higher; such DEMGs achieve higher speeds, represent a technological advance and are less expensive.
Autors: Valery B. Kudel’kin;Leonid P. Babich;Boris E. Grinevich;Andreĭ V. Ivanovskiĭ;Andreĭ I. Kraev;Eugeny V. Shapovalov;
Abstract: The accuracy of time-delay estimation (TDE) in ultrasound elastography is usually measured by calculating the value of normalized cross correlation (NCC) at the estimated displacement. NCC value, however, could be very high at a displacement estimate with large error, a well-known problem in TDE referred to as peak-hopping. Furthermore, NCC value could suffer from jitter error, which is due to electric noise and signal decorrelation. Herein, we propose a novel method to assess the accuracy of TDE by investigating the NCC profile around the estimated time-delay. We extract several features from the NCC profile, and utilize support vector machine to classify peak-hopping and jitter error. The results on simulation, phantom, and in vivo data show the significant improvement of the proposed algorithm compared to the state of the art techniques.
Abstract: Image content analysis is an important surround perception modality of intelligent vehicles. In order to efficiently recognize the on-road environment based on image content analysis from the large-scale scene database, relevant images retrieval becomes one of the fundamental problems. To improve the efficiency of calculating similarities between images, hashing techniques have received increasing attentions. For most existing hash methods, the suboptimal binary codes are generated, as the hand-crafted feature representation is not optimally compatible with the binary codes. In this paper, a one-stage supervised deep hashing framework (SDHP) is proposed to learn high-quality binary codes. A deep convolutional neural network is implemented, and we enforce the learned codes to meet the following criterions: 1) similar images should be encoded into similar binary codes, and vice versa; 2) the quantization loss from Euclidean space to Hamming space should be minimized; and 3) the learned codes should be evenly distributed. The method is further extended into SDHP+ to improve the discriminative power of binary codes. Extensive experimental comparisons with state-of-the-art hashing algorithms are conducted on CIFAR-10 and NUS-WIDE, the MAP of SDHP reaches to 87.67% and 77.48% with 48 b, respectively, and the MAP of SDHP+ reaches to 91.16%, 81.08% with 12 b, 48 b on CIFAR-10 and NUS-WIDE, respectively. It illustrates that the proposed method can obviously improve the search accuracy.
Abstract: During asynchronous collaborative analysis, handoff of partial findings is challenging because externalizations produced by analysts may not adequately communicate their investigative process. To address this challenge, we developed techniques to automatically capture and help encode tacit aspects of the investigative process based on an analyst's interactions, and streamline explicit authoring of handoff annotations. We designed our techniques to mediate awareness of analysis coverage, support explicit communication of progress and uncertainty with annotation, and implicit communication through playback of investigation histories. To evaluate our techniques, we developed an interactive visual analysis system, KTGraph, that supports an asynchronous investigative document analysis task. We conducted a two-phase user study to characterize a set of handoff strategies and to compare investigative performance with and without our techniques. The results suggest that our techniques promote the use of more effective handoff strategies, help increase an awareness of prior investigative process and insights, as well as improve final investigative outcomes.
Abstract: The exponential growth of information and communication technologies have caused a profound shift in the way humans engineer systems leading to the emergence of closed-loop systems involving strong integration and coordination of physical and cyber components, often referred to as cyber–physical systems (CPSs). Because of these disruptive changes, physical systems can now be attacked through cyberspace and cyberspace can be attacked through physical means. The paper considers security and resilience as system properties emerging from the intersection of system dynamics and the computing architecture. A modeling and simulation integration platform for experimentation and evaluation of resilient CPSs is presented using smart transportation systems as the application domain. Evaluation of resilience is based on attacker–defender games using simulations of sufficient fidelity. The platform integrates 1) realistic models of cyber and physical components and their interactions; 2) cyber attack models that focus on the impact of attacks to CPS behavior and operation; and 3) operational scenarios that can be used for evaluation of cybersecurity risks. Three case studies are presented to demonstrate the advantages of the platform: 1) vulnerability analysis of transportation networks to traffic signal tampering; 2) resilient sensor selection for forecasting traffic flow; and 3) resilient traffic signal control in the presence of denial-of-service attacks.
Abstract: Transient stability and short-term voltage stability have successively attracted the attention of electric power industry. This paper proposes a novel systematic approach for dynamic VAR planning to improve short-term voltage stability level and transient stability level. The dynamic VAR planning problem is formulated as a multi-objective optimization (MOO) model with objectives including investment cost, short-term voltage stability level, and transient stability level. To reduce the complexity of the proposed MOO model, K-means clustering-based severe contingencies selection and global sensitivity analysis-based potential buses selection are employed, leading to a simplified MOO model. The combination of a surrogate modeling technique called support vector regression and the multi-objective evolutionary algorithm (MOEA) are then used to solve the simplified MOO model, considering both the accuracy of models and the optimization computation cost. This combination makes it feasible to perform multiple runs of MOEAs for weakening the effect of the MOEA's randomness to optimal results and offering more diverse Pareto-optimal solutions for decision makers. Simulations are carried on the IEEE 39-bus system and a real power grid of China, illustrating that our methodology is reliable with high efficiency.
Abstract: This paper proposes a blind digital audio water- marking algorithm that utilizes the quantization index modulation (QIM) and the singular value decomposition (SVD) of stereo audio signals. Conventional SVD-based blind audio watermarking algorithms lack physical interpretation since the matrix construction method for the input matrix for SVD is heuristically defined. However, in the proposed approach, because the SVD is directly applied to the stereo input signals, the resulting decomposed elements convey a conceptually meaningful inter- pretation of the original audio signal. As the proposed approach effectively utilizes the ratio of singular values, the embedded watermark is highly imperceptible and robust against volumetric scaling attacks; most QIM-based watermarking schemes are weak to these types of attacks. Experimental results under well-known practical attacks, such as compressions, resampling, and various types of signal processing, confirm that the proposed algorithm performs well compared to conventional audio watermarking algorithms.
Abstract: We propose uncalibrated photometric stereo methods that address the problem due to unknown isotropic reflectance. At the core of our methods is the notion of “constrained half-vector symmetry” for general isotropic BRDFs. We show that such symmetry can be observed in various real-world materials, and it leads to new techniques for shape and light source estimation. Based on the 1D and 2D representations of the symmetry, we propose two methods for surface normal estimation; one focuses on accurate elevation angle recovery for surface normals when the light sources only cover the visible hemisphere, and the other for comprehensive surface normal optimization in the case that the light sources are also non-uniformly distributed. The proposed robust light source estimation method also plays an essential role to let our methods work in an uncalibrated manner with good accuracy. Quantitative evaluations are conducted with both synthetic and real-world scenes, which produce the state-of-the-art accuracy for all of the non-Lambertian materials in MERL database and the real-world datasets.
Abstract: In this paper, we propose a generalized joint sparsity regularization prior and reconstruction framework for the synergistic reconstruction of positron emission tomography (PET) and under sampled sensitivity encoded magnetic resonance imaging data with the aim of improving image quality beyond that obtained through conventional independent reconstructions. The proposed prior improves upon the joint total variation (TV) using a non-convex potential function that assigns a relatively lower penalty for the PET and MR gradients, whose magnitudes are jointly large, thus permitting the preservation and formation of common boundaries irrespective of their relative orientation. The alternating direction method of multipliers (ADMM) optimization framework was exploited for the joint PET-MR image reconstruction. In this framework, the joint maximum a posteriori objective function was effectively optimized by alternating between well-established regularized PET and MR image reconstructions. Moreover, the dependency of the joint prior on the PET and MR signal intensities was addressed by a novel alternating scaling of the distribution of the gradient vectors. The proposed prior was compared with the separate TV and joint TV regularization methods using extensive simulation and real clinical data. In addition, the proposed joint prior was compared with the recently proposed linear parallel level sets (PLSs) method using a benchmark simulation data set. Our simulation and clinical data results demonstrated the improved quality of the synergistically reconstructed PET-MR images compared with the unregularized and conventional separately regularized methods. It was also found that the proposed prior can outperform both the joint TV and linear PLS regularization methods in assisting edge preservation and recovery of details, which are otherwise impaired by noise and aliasing artifacts. In conclusion, the proposed joint sparsity regularization within the presented a-
ADMM reconstruction framework is a promising technique, nonetheless our clinical results showed that the clinical applicability of joint reconstruction might be limited in current PET-MR scanners, mainly due to the lower resolution of PET images.
Autors: Abolfazl Mehranian;Martin A. Belzunce;Claudia Prieto;Alexander Hammers;Andrew J. Reader;
Abstract: Six-port-based mobile RF-receivers are a competitive alternative for the reception of today’s and future wideband communications signals and software-defined-radio systems. This paper provides a general, systematic, and analytic insight into the signal processing of six-port-based receivers. The influences of the rectified wave within the receivers’ signal processing will be identified to have significant impact on the practical application of six-port-based receivers. The presented, first analytically complete system analysis considers any higher-order non-linearity and enables limitation-free design and simulation of such topologies. To overcome the spurious influences of the rectified wave, enhanced receiver architectures are presented which compensate for the rectified wave in analog domain.
Autors: Marko Mailand;
Appeared in: IEEE Transactions on Circuits and Systems I: Regular Papers
Abstract: Modern system-on-chip (SoC) designs include a wide variety of highly sensitive assets which must be protected from unauthorized access. A significant aspect of SoC design involves exploration, analysis, and evaluation of resiliency mechanisms against attacks to such assets. These attacks may arise from a number of sources, including malicious intellectualproperty blocks (IPs) in the hardware, malicious or vulnerable firmware and software, insecure communication of the system with other devices, and side-channel vulnerabilities through power and performance profiles. Countermeasures for these attacks are equally diverse, which include architecture, design, implementation, and validation-based protection. In this paper, we provide a comprehensive overview of the security infrastructure in modern SoC designs, including both resiliency techniques and their validation paradigms at presilicon and postsilicon stages. We identify gaps in current resiliency and analysis architectures and propose design and validation solutions to address them. Finally, we provide industry perspectives on the role and impact of current practices on SoC security, and discuss some emerging trends in this important area.
Autors: Sandip Ray;Eric Peeters;Mark M. Tehranipoor;Swarup Bhunia;
Abstract: Multivariate, tabular data is one of the most common data structures used in many different domains. Over time, tables can undergo changes in both structure and content, which results in multiple versions of the same table. A challenging task when working with such derived tables is to understand what exactly has changed between versions in terms of additions/deletions, reorder, merge/split, and content changes. For textual data, a variety of commonplace “diff” tools exist that support the task of investigating changes between revisions of a text. Although there are some comparison tools which assist users in inspecting differences between multiple table instances, the resulting visualizations are often difficult to interpret or do not scale to large tables with thousands of rows and columns. To address these challenges, we developed TACO, an interactive comparison tool that visualizes the differences between multiple tables at various levels of detail. With TACO we show (1) the aggregated differences between multiple table versions over time, (2) the aggregated changes between two selected table versions, and (3) detailed changes between the selected tables. To demonstrate the effectiveness of our approach, we show its application by means of two usage scenarios.
Autors: Christina Niederer;Holger Stitz;Reem Hourieh;Florian Grassinger;Wolfgang Aigner;Marc Streit;
Appeared in: IEEE Transactions on Visualization and Computer Graphics
Abstract: In this paper we present a set of four user studies aimed at exploring the visual design space of what we call keyword summaries: lists of words with associated quantitative values used to help people derive an intuition of what information a given document collection (or part of it) may contain. We seek to systematically study how different visual representations may affect people's performance in extracting information out of keyword summaries. To this purpose, we first create a design space of possible visual representations and compare the possible solutions in this design space through a variety of representative tasks and performance metrics. Other researchers have, in the past, studied some aspects of effectiveness with word clouds, however, the existing literature is somewhat scattered and do not seem to address the problem in a sufficiently systematic and holistic manner. The results of our studies showed a strong dependency on the tasks users are performing. In this paper we present details of our methodology, the results, as well as, guidelines on how to design effective keyword summaries based in our discoveries.
Abstract: The gain medium of a free electron laser (FEL) is a relativistic electron beam. The challenge with oscillator FELs is to decouple the electron beam from the radiation. Here we present the results of simulations and experimental measurements of a Talbot effect resonator which effectively decouples the electron beam from the radiation without the use of bending magnets. Radiation from 95 to 110 GHz can be harvested. The free spectral range is 100 MHz, though it is possible for us to remotely adjust the length and so tune between the 100-MHz resonant frequencies. The resonator also can vary the power coupled out from the resonator, allowing optimization of the power extracted from the saturated electron gain medium.
Autors: H. S. Marks;A. Gover;
Appeared in: IEEE Transactions on Microwave Theory and Techniques
Abstract: In this paper, a tangential network transmission theory is established for the reflective metasurface composed of periodic subwavelength metallic elements and a perfect electrical conductor (PEC)-backed substrate. The theory is divided into two parts. The first part shows that the oblique incidence can be handled the same way as a normal incidence for a PEC-backed substrate in terms of tangential components of electric fields and a normal wave vector. Therefore, the network transmission theory is extended from the PEC-backed substrate to the reflective metasurface, whose total tangential reflection matrix depends on the induction matrix of the metallic elements in the air–substrate interface. The second part deals with the conversion of the induction matrices of different metallic elements into equivalent circuits, whose electrical parameters can be theoretically calculated or extracted from numerical simulations. Based on the obtained electrical parameters, the theory can be used to analyze or design reflective metasurfaces. Finally, the theory is verified by a metasurface, which is composed of periodic double-L shaped elements. The analytical results agree with the simulated ones for arbitrary substrate and incidence angle. The measured results further validate the proposed theory.
Abstract: This paper considers the problem of reconstructing true targets in a single-channel synthetic aperture radar (SAR) imaging system, which has been disturbed by deceptive jammings. Since the deceptive jammings are usually confined to the main lobe of an SAR antenna, their time–frequency distributions are different from those of the true echoes. This enables us to utilize a dynamic synthetic aperture (DSA) scheme to extract the characteristics of the true and false targets. Dictionaries about the true and false targets are constructed by taking interactions between scatterers into account. Then a sparsity-driven optimization problem is solved to reconstruct the true and false targets separately with super-resolution. Moreover, the deceptively jammed SAR data are divided into different areas to handle various scenarios efficiently, and strategies for DSA selection are addressed as well. Simulations are provided to verify the effectiveness of the proposed algorithm.
Autors: Bo Zhao;Lei Huang;Jian Li;Peichang Zhang;
Appeared in: IEEE Transactions on Geoscience and Remote Sensing
Abstract: In this paper, the temperature associated reliability issues of heterogeneous gate dielectric-gate all around-tunnel FET (HD GAA TFET) has been addressed, and the results are simultaneously compared with gate all around tunnel FET (GAA TFET). This is done by investigating the effect of interface trap charges such as donor (positive interface charges) and acceptor (negative interface charges) at various operating temperatures on the device analog parameters and RF figure of merits. It is observed that, at high gate bias, TFET exhibits weak temperature dependence owing to the weak dependence of band to band tunneling phenomenon on the temperature in comparison to the large temperature variation for lower gate bias due to the temperature dependence of Shockley-Read-Hall (SRH) phenomenon. Results reveal that extremely high off current at elevated temperatures degarades the device performance, making the device less reliable for high-temperature applications. Moreover, at elevated temperature, the decrease in threshold voltage and intrnsic delay, and increase in cut off frequency is found, thereby upgrading the device characteristics. All the simulations have been done on ATLAS device simulator.
Abstract: In this letter, we present a new structure composed by a long-period grating (LPG) and a microsphere in series, which works as a modal interferometer besides allowing the mode coupled to the cladding to be coupled back to the core. The LPG was written by the electric arc technique and the microsphere was fabricated using a splicing machine. It is possible to use this new structure for simultaneous measurement of strain and temperature. It also allows one to obtain a temperature compensated strain sensor by using a proper data processing algorithm, which utilizes two distinct wavelengths for strain and temperature. Then, a strain sensitivity of 0.86 pm/ and a reduced temperature sensitivity of 0.7 pm/°C were achieved.
Autors: Joaquin Ascorbe;Luís Coelho;José L. Santos;Orlando Frazão;Jesus M. Corres;
Abstract: Dynamic verification is widely used to ensure the logical correctness of system design. Verification progress is usually gauged by coverage metrics. Most coverage metrics measure the sub-structures of design under verification that are exercised. More importantly, the probability of a bug being detected is approximated by probabilistic coverage analysis. However, existing analysis methods do not consider the temporal nature of digital systems, i.e., it only applies to combinational circuit but not sequential circuit. In this brief, we propose a probabilistic analysis framework which takes into account the temporal behavior of system design. We propose an effective analysis algorithm which can estimate the probability of a bug being detected for sequential circuit. Experimental results on 17489 random instances show that our method is both efficient and accurate. The analysis has time complexity quadratic to the number of coverage bins and linear to the number of simulation cycles. The analysis result has an average relative error of about 7.38%. In practice, our analysis result can be used to measure the completeness of verification.
Autors: Min Zhou;William N. N. Hung;Xiaoyu Song;Ming Gu;Jiaguang Sun;
Appeared in: IEEE Transactions on Circuits and Systems II: Express Briefs
Abstract: In this paper, two kinds of cascaded metasurfaces are proposed for the simultaneous control of the reflected and transmitted wavefronts in the terahertz (THz) frequency band. First, an array of arrow-shaped elements backed by a strip grating is investigated. When the polarization of the incidence field is parallel to the orientation of the strip grating, the reflected and transmitted waves with approximately equal amplitude will be generated and there is a constant phase difference between them when the element dimensions are varied. Proved by the simulation and measured results, the metasurface based on the proposed element can simultaneously deflect the transmitted and reflected wavefronts but only by the same angle. Second, independent control of both amplitudes and phases of the transmitting and reflecting waves is achieved by cascading four metallic layers in order, i.e., a y-oriented strip layer, a y-directed grating layer, the arrow-shaped element, and an x-directed grating, with respect to different polarizations of the incident field. The simulation and measured results show that the y-polarized incident waves can be reflected by the four-layered metasurface into a designed reflection angle, while the x-polarized incident waves can be focused on the other side of the metasurface in a transmitting manner. Compared with the reported THz metasurfaces, the proposed elements can provide more advanced wavefront-control ability and they also feature the advantages of compact size, low cost, and lightweight. Therefore, the proposed metasurfaces can be applied as beam splitters for low-cost and compact THz imaging and detection systems.
Abstract: This paper characterizes Boolean expression faults as changes of the topological structures in terms of shrinking and/or expanding regions in K-map. A cell-covering is a set of cells (test cases) in K-map to cover the fault regions such that faults guarantee to be detected. Minimizing cell covering can be formulated as an Integer Linear Programming (ILP) problem. By analyzing the structures of the constraint coefficient matrix, the original problem can be decomposed into sub-programs that can be solved instead of the original problem, and this significantly reduces the time needed for ILP execution. An efficient approximate algorithm with a tight theoretical bound is used to address those complex Boolean expressions by corresponding the cell-covering problem to the set-covering problem. The optimal approach and the approximate approach are combined into a hybrid process to identify test cases based on the fraction analysis on the ILP relaxation. The proposed approach is evaluated by three sets of Boolean expressions and the results are compared with three leading approaches with respect to test sizes, time consumption and fault detection capabilities. For most Boolean expressions encountered, the proposed approach obtains optimal solutions quickly, and produces near-optimal solutions rapidly for those rare and complex expressions.
Autors: Lian Yu;Wei-Tek Tsai;
Appeared in: IEEE Transactions on Software Engineering
Abstract: The analysis of gait dynamics is helpful for predicting and improving the quality of life, morbidity, and mortality in neuro-degenerative patients. Feature extraction of physiological time series and classification between gait patterns of healthy control subjects and patients are usually carried out on the basis of 1-D signal analysis. The proposed approach presented in this paper departs itself from conventional methods for gait analysis by transforming time series into images, of which texture features can be extracted from methods of texture analysis. Here, the fuzzy recurrence plot algorithm is applied to transform gait time series into texture images, which can be visualized to gain insight into disease patterns. Several texture features are then extracted from fuzzy recurrence plots using the gray-level co-occurrence matrix for pattern analysis and machine classification to differentiate healthy control subjects from patients with Parkinson’s disease, Huntington’s disease, and amyotrophic lateral sclerosis. Experimental results using only the right stride-intervals of the four groups show the effectiveness of the application of the proposed approach.
Autors: Tuan D. Pham;
Appeared in: IEEE Transactions on Neural Systems and Rehabilitation Engineering
Abstract: The 2017 Visualization Career Award goes to Charles (Chuck) Hansen in recognition for his contributions to large scale data visualization, including advances in parallel and volume rendering, novel interaction techniques, and techniques for exploiting hardware; for his leadership in the community as an educator, program chair, and editor; and for providing vision for the development and support of the field. The IEEE Visualization & Graphics Technical Committee (VGTC) is pleased to award Charles Hansen the 2017 Visualization Career Award.
Autors: Charles Hansen;
Appeared in: IEEE Transactions on Visualization and Computer Graphics