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A compact model for the single-poly multitime programmable (MTP) memory cells is presented in this paper for the first time. It is based on the charge balance approach, while the traditional old model is on the fixed capacitive coupling approach. The proposed cell model has been implemented by Verilog-A and integrated into commercial SPICE simulator. The model supports both dc and transient analyses, and the simulated results are consistent very well with those from device simulation and measurement, whereas the results by the traditional old model deviate substantially. Furthermore, the comprehensive optimization of the MTP cells is made feasible thanks to the new model, such as device size, high voltage ramp rate, and reliability prediction. As a result, this compact cell model will be very useful for the designers to evaluate and optimize a single-poly MTP cell. [ABSTRACT FROM AUTHOR]

It is generally known that the dc breakdown strength of low density polyethylene (LDPE) decreases with as the thickness and temperature of the sample increase. The breakdown strength is influenced by the charge transport and electric field distortion, and is also related to the molecular chain displacement and fracture. This paper investigates mutual relations among the charge transport, molecular chain displacement, and thickness dependent dc breakdown of LDPE. A model that combines the dynamics of charge transport and molecular displacement (CTMD) is used to calculate the space charge accumulation, molecular chain displacement, and dc breakdown properties of LDPE with various thicknesses at various constant voltage ramping rates. It is assumed that breakdown occurs when the molecular chain displacement reaches a critical value. The simulation results show that the breakdown field as a function of sample thickness satisfies an inverse power law with a power index of about 0.43 for various voltage ramping rates. This is consistent with experimental results. The CTMD model considers both the distortion of electric field and the displacement kinetics of molecular chains, resulting in a power index closer to the experiment than that calculated only from the electric field distortion. Adopted a Williams-Landel-Ferry type molecular chain mobility in the CTMD model, the simulation results are consistent with the results calculated by applying experimental results on polyisobutylene and polymethyl methacrylate to the free volume breakdown theory. It is also found that the CTMD model with temperature-dependent molecular chain mobility controlled by piecewise Arrhenius equations can explain well the temperature dependent breakdown experimental results of LDPE. [ABSTRACT FROM PUBLISHER]

Giant magnetoimpedance (GMI) thin-film magnetic sensors are modeled and evaluated using 3-D physical simulations. In the presented simulation model, the analytical multi-physics equations of MI phenomena are solved with the help of the advanced finite-element method software. In this paper, Co72Si12B6 is considered as the GMI material, forming a tri-layer of Co72Si12B6/Au/Co72Si12B6. The effects of changes in frequency and external magnetic field are discussed in detail. The geometrical dependence of thin-film GMI sensors is also studied. A batch of thin-film sensors is fabricated and tested. The measured data are in good agreement with the simulation results obtained by the proposed model. [ABSTRACT FROM PUBLISHER]

Voltage source back-to-back power converters are widely used in grid-tied applications. This paper presents a quasi-centralized direct model predictive control (QC-DMPC) scheme for back-to-back converter control without a dc-link outer-loop controller. Furthermore, the QC-DMPC is experimentally compared with a conventional proportional-integration (PI) dc-link controller-based DMPC (PI-DMPC) scheme. For the QC-DMPC scheme, the dc-link voltage is directly controlled by a grid-side predictive controller using a dynamic reference generation concept and load-side power estimation. For the PI-DMPC scheme, the dc-link voltage is controlled by an external PI controller. Both schemes are implemented on a field programmable gate array (FPGA)-based platform. Effectiveness of the proposed QC-DMPC is verified by both simulation and experimental data. Moreover, FPGA implementation issues (resource usage and timing information), dc-link control performance, and robustness to parameter variation of the two DMPC schemes are compared in detail. The results emphasize that the QC-DMPC may outperform the PI-DMPC scheme in normal operation but with a slightly higher usage of FPGA resources. However, PI-DMPC scheme is more robust when parameter variations are considered. [ABSTRACT FROM PUBLISHER]

This paper presents a numerical method to simulate the particle trajectory in the head–disk interface (HDI). The simulator solves the reduced Navier–Stokes equation with the second-slip boundary conditions to get the air velocity distribution, then solves the motion equations of particles and obtains the trajectories of the particles in the HDI using the binary Lagrange interpolation and the fourth-order Runge–Kutta method. The calculated trajectories of particles follow well with the air streamlines in the recessed regions. The particle density, diameter, and initial entering velocity have different effects on particle movement. Furthermore, particle velocity behaviors in the recessed regions are investigated for the first time. The particle is accelerated or decelerated by the action of the drag force and becomes close to the velocity of local air flow. Such effects are more obvious for small particles than large particles. The particle velocity becomes very small when it is close to the leading edge of the trailing pad. The numerical results also show that the particle goes up when it crosses the transition regions, and the particle moves upward more sharply with higher initial entrance height due to the larger vertical velocity of the local air flow. [ABSTRACT FROM AUTHOR]

This paper describes a simple approach to electromagnetic design of vane-type resonant system for high-power high-efficient industrial continuous wave (CW) magnetrons. It uses empirical equations in conjunction with normalization techniques to synthesize all the parameters of the resonant structure and then optimize them through simulation using computer simulation technology, microwave studio/particle studio. A method to select constant parameters in the empirical equations has been proposed and shown to be effective in designing practical high-power CW magnetrons. The approach has been benchmarked by designing and developing a double ring ten-vane resonator for a 10-kW output power at a 2.45 GHz ± 30 MHz frequency CW magnetron with a 75% efficiency. The measured circuit parameters such as $\pi $ -mode frequency, quality factors, and circuit efficiency were found in good agreement with the computed one validating the effectiveness of the proposed design approach. The particle-in-cell simulation of this magnetron predicted that an output power of 10.98 kW can be achieved with an efficiency of 71.45%. [ABSTRACT FROM PUBLISHER]

This paper presents the results of a spacecraft attitude control system based on magnetic actuators designed for low Earth orbits. The control system is designed by using a nonlinear control technique based on the approximating sequence of Riccati equations. The behavior of the satellite is discussed under perturbations and model uncertainties. Simulation results are presented when the control system is able to guide the spacecraft to the desired attitude in a variety of different conditions. [ABSTRACT FROM AUTHOR]

This paper presents a nonlinear 3D-vector guidance law. It is based on kinematic vector equations, where the commanded thrust is bounded, and the interceptor does not know the target evasive strategy. The resulting game theoretic guidance law with miss-distance as the cost, is nonlinear, aligned along the zero-effort-miss (ZEM) direction, and the time-to-go is a solution of a quartic polynomial equation in feedback form. This time-to-go is the actual one provided both players play optimal. If the evader does not play optimal, capture occurs earlier. Moreover, optimal strategies in line-of-sight (LOS) coordinates are also presented. It is found that these strategies are functions of the range, range rate, and the LOS rate. Simulations demonstrate the possibility of a miss at the first pass, but eventual capture. [ABSTRACT FROM PUBLISHER]

With the steady growth of chip complexity and shrinking feature size, multiple challenges are emerging for transistor level circuit simulation. Compact SPICE models are a fundamental part of circuit verification, serving as a bridge between the semiconductor design and foundry. It is also an integral part of SPICE simulators, which directly affects tool performance and therefore design schedule. While the advanced 3-D technology nodes deliver superior level of scalability, simulation cost is rapidly increasing due to the computational complexity introduced by device model equations and the number of iterations required for numerical methods. In this paper, an efficient solution is proposed to reduce the computational cost associated with UC Berkeley BSIM-CMG device model evaluation, by applying robust Verilog compiler and computer algebra techniques to the device model equations. As a result of this implementation, simulation time reduction is up to 72% for complex blocks of the latest generation processor design. [ABSTRACT FROM PUBLISHER]

In this paper, a sector-step approximation (SSA) model is introduced. With step admittance recurrence and field matching relation, the dispersion equation of rising-sun magnetron (RSM) with arbitrary resonators is derived. By this model, resonant frequencies of a 10-resonator sector and hole-and-slot resonator type RSM (SHSRSM) are theoretically calculated. In addition, computer simulation is performed to verify the accuracy of the theory. Besides, the effects of the hole radius on magnetron’s main characteristic parameters are analyzed, such as $\pi$ -mode resonant frequency, mode separation, and quality factor. The optimized SHSRSM is compared with two common kinds of RSMs, such as sector resonator type RSM (SRSM) and sector-and-slot resonator type RSM (SSRSM). The results show that the theoretical results are well consistent with the simulation results, and the maximum relative error is less than 3%, which verifies the accuracy and feasibility of the SSA model. Compared with SRSM and SSRSM, SHSRSM has greater mode separation and quality factor, which improves the stability and the energy storage of RSM. [ABSTRACT FROM PUBLISHER]

Since the flux leakage phenomenon is dominant in the inner and outer radii of axial flux magnetic gears (AFMGs), a prominent overestimation of torque prediction is obtained by the 2-D analytical method (AM) in comparison with the 3-D finite-element method (FEM) simulations. The main motivation of this paper is to present an improved quasi-3-D AM (IQAM), which is an improvement and amendment of the 2-D AM by a simple and effective radial dependence modeling of the axial and tangential magnetic field distribution in AFMGs. This IQAM plays an important role in a reliable and accurate prediction of static and transient behavior of AFMGs. The cogging torque of the AFMG is predicted using the obtained IQAM and Maxwell’s stress tensor. However, the proposed IQAM will become more prominent by focusing on the effects of single- and dual-skews’ designs for ferromagnetic pole-pieces and permanent magnets through suitable step changes in a combined skewed-MG model, as an effective passive method, in order to mitigate the cogging torque and thereby intensively augmenting torque quality in an exemplary AFMG. The accuracy of the developed skewing method is verified using 3-D FEM simulations. [ABSTRACT FROM AUTHOR]

This paper presents the results of an empirical study of training procedures enabling flexibility in the design and management of large-scale engineering systems. The work relies on the development and use of a simulation game environment to study decision-making dynamics under different treatment conditions. Evaluation of short-term, long-term, and in-game training is completed to assess the main and interaction effects on quantitative lifecycle performance indicators, and qualitative user impressions. Forty-six graduate engineering students participated in controlled experiments where they worked on the design and management of a flexible emergency medical services system. Results show that in-game training produces a statistically significant improvement on lifecycle performance score, while long-term flexibility training significantly reduces decision-making time. In-game training improves process satisfaction. Both short-term and in-game training lead to improved satisfaction with the results, and contribute to improved anticipated quality of the results. Correlation studies suggest that participants taking more time for decision-making may improve lifecycle performance scores. Lifecycle score improvement also increases as satisfaction with the process and anticipated quality of results increase. Experimental results show that different training procedures produce different effects on design and management decision-making for flexible engineering systems operating under uncertainty. They provide further insights to support the development and evaluation of novel training approaches useful for systems engineering practice and education. [ABSTRACT FROM AUTHOR]

Calculating the mutual coupling between antennas on vehicles using full-wave simulations requires a vast amount of computer resources due to the electrical size of the structures. We therefore propose an alternative and approximate method to determine mutual coupling between antennas on vehicles for the case where there is line-of-sight (LOS) between the antennas. The proposed method is based on approximating the mutual coupling between LOS antennas on vehicles as near-field transmission between antennas in free space. We begin the analysis with a brief review of four methods for calculating the near-field free-space transmission. Of the investigated methods, we demonstrate that a nonsingular form of the near-field transmission integral originally proposed by Yaghjian (1982) is the most suitable for LOS antennas on vehicles. We introduce a modification to this method, in order to only use the antenna far-fields and geometrical separation to determine the mutual coupling. The comparison with full-wave simulations indicates that the proposed method has a good accuracy for LOS antennas. This paper ends with a full-scale mutual coupling calculation for two monopoles on an aircraft under LOS conditions, demonstrating a root mean square (rms) accuracy of 6 dB for frequencies up to 5 GHz, as compared with full-wave simulations. [ABSTRACT FROM PUBLISHER]

This paper presents a parametric study of square loop and square slot frequency selective surfaces (FSSs) aimed at their equivalent circuit (EC) model optimization. Consideration was given to their physical attributes, i.e., the unit cell dimensions and spacing, substrate thickness and dielectric properties, for several frequencies and plane wave incident angles. Correlation analysis and evaluation of the influence of physical related input parameters on the FSS performance are presented. Subsequent optimization factor for the square loop classical EC model is analyzed, and a novel EC model formulation for the square slot FSS is proposed. The performance of the proposed EC model was assessed against results obtained from appropriate electromagnetic (EM) simulations, based on a root-mean-square error (RMSE) criteria. Results demonstrate the validity of the optimized EC model, in which good estimations of the frequency response of FSS structures were obtained. Significant reduction of the resonant frequency offsets, in the order of 650 (from 910 to 260) and 460 (770 to 310) MHz, was obtained for square loops and square slots, respectively. The models were further validated against measurements performed on two physical FSS prototypes inside an anechoic chamber at 2.4 GHz. Relatively good agreement was obtained between measurements of real FSS prototypes and results obtained with the EC model. Finally, this work is sought to provide the necessary refinement of elementary models for further studies with more complex and novel FSS structures. [ABSTRACT FROM PUBLISHER]

Nowadays, point-of-load (POL) converters’ investments are counted as a main part in power management markets; especially the synchronous buck converters. Today's products forces designers to highly integrate POL converters by increasing the switching frequency; so the latest technology has used megahertz range to obtain this target. On the other hand, increasing switching frequency means increasing the switching losses. Therefore, it is very important to optimize the operating switching frequency tradeoff, which requires an accurate model taking in consideration the converter operating conditions. This paper presents an accurate mathematical loss model taking in consideration the physical behavior of the MOSFET switch in addition to the converter operating conditions. This model introduces accurate equations for every switching intervals and so accurate loss calculations. An integrated POL synchronous buck converter of 5 MHz, 5–1.8 V/3 A prototype is fabricated. The results of the proposed model are compared with simulation and experimental results under variable operating conditions. Good matching between the mathematical, experimental, and simulation results are obtained. [ABSTRACT FROM AUTHOR]

The proper modeling of the transient thermal behavior of mutual heating effects between underground power cables is very important for the rating of transmission and distribution cables. The IEC standards proposed an accurate model based on exponential integrals that it can be difficult to implement in basic electrical software. The model is not consistent with the layered modeling of the cable thermal resistances. In this paper, a simple and easy-to-use alternative model is presented. It consists of injecting the correct current at the right position of the RC circuit representing the soil. The new model can accurately reproduce the full physics of the transient phenomenon and is consistent with the modeling of the cable used in the IEC standards themselves. The new model is tested and validated against numerous finite-element simulations for realistic cable installations. [ABSTRACT FROM AUTHOR]

This paper discusses the application of Nyquist plot and two statistical indicators to analyze the frequency response of power transformers. Five cases are presented based on both simulations and measurements. These include two types of winding deformation, namely tilting and bending of conductors. Initially, damage is simulated for five degrees of severity and analyzed using two statistical indicators. The indicators are compared for their performance in terms of evaluating the severity of damage. New findings from this comparison are presented. Additionally, the benchmark limit for one of the indicators is also assessed on all cases. Finally, a methodology is proposed to estimate the severity of damage from two frequency responses using the Nyquist plot. This method is tested on three different windings. [ABSTRACT FROM PUBLISHER]

The code design problem for multilevel coded modulation with iterative decoding (MLCM-ID) has been left unsolved over a decade. In this paper, we define the code design criterion for MLCM-ID based on a novel concept—parametrically-mapped EXIT (PM-EXIT) function. We derive the EXIT functions for MLCM-ID, and present the mathematical work by which the three area theorems of PM-EXIT function are proved. This gives theoretical support of the curve-fitting techniques used in MLCM-ID, and also provides firm proof that the PM-EXIT function design rule allows in principle capacity-achieving code assignment. The simulation results perfectly match the theoretical analysis, and also confirm that the design rule proposed fully exploits the flexibility of MLCM-ID in the choice of codes. Both in theory and simulations, our code design is verified. [ABSTRACT FROM PUBLISHER]

Acoustic tracking with propagation delay is a challenging problem for the following reasons: 1) It is difficult to perform an accurate state prediction, as the time interval between the current state and the previous state is varying and unknown due to the propagation delay; and 2) the target time (signal emission time) needs to be estimated in addition to the target position and velocity. With the state augmented with the target time, the state transition cannot be described by the commonly used explicit Gauss?Markov model. In this paper, we propose a new approach to solving this difficult problem by using the Gauss?Helmert model for the state transition, which consists of an implicit equation between two consecutive states. An unscented Gauss?Helmert filter is then developed based on this formulation. The new approach is applied to the bearings-only tracking problem with state-dependent propagation delay. Simulation tests are conducted to demonstrate the performance of the unscented Gauss?Helmert filter, which is shown to outperform other approaches in terms of estimation accuracy, especially when a target is moving at high speed. [ABSTRACT FROM PUBLISHER]

In this paper, an N-buffer layer has been introduced into the reversely switched dynistor (RSD). The relationship between the buffer layer and the device characteristics, together with the interaction among structural parameters, is discussed by the orthogonal method in detail. Based on the simulation results, buffer thickness $W_{{{\text {n-buffer}}}} and buffer concentration \textN{{\text {n-buffer}}} , \textN^{+} emitter concentration \textN{\text {n+}} , and \textP^+ emitter concentration \textN{\text {p+}} at anode can all affect the maximum turn-ON voltage $U_{{{F\text {max}}}}$ on the RSD. Furthermore, the $U_{{{F\text {max}}}}$ increases with increasing $W_{{{\text {n-buffer}}}} or decreasing \textN\text p+ , and if \textN{{\text {n-buffer}}} becomes higher continuously, the $U_{{{F\text {max}}}} slightly decreases first, and then dramatically goes up. Besides, the interaction between \textN{{\text {n-buffer}}} and W{{\text {n-buffer}}} has a dramatic impact on the $U_{{{F\text {max}}}} . When \textN{{\text {n-buffer}}}=1 E17 cm ^{-3} , $W_{{{\text {n-buffer}}}}=10\mu \text{m} , \textN{\text {p+}} =1 E18 cm ^{-3} , and \textN{n+} =1 E20 cm ^-3 , $U_{{{F\text {max}}}}$ reaches its minimum in all the simulations. The experimental results verify the device characteristic’s improvement by introducing the buffer layer. [ABSTRACT FROM PUBLISHER]

This paper describes 3D particle-in-cell (PIC) simulation of charge injection and transport through ferroelectric semicrystalline polymer (e.g. PVDF) film comprised of nanocrystallites in an amorphous matrix with varying degrees of crystallinity. The classical electrical double layer (EDL) model for a monopolar core is extended (eEDL) to represent the nanocrystallite by replacing it with a dipolar core. Charge injection at the electrodes assumes metal-polymer Schottky emission at low to moderate fields and Fowler-Nordheim tunneling at high fields. Injected particles propagate via field-dependent Poole-Frenkel mobility. In the eEDL model, the initial attachment of charge particles forms the bound Stern-Helmholtz layer leading to Maxwell-Wagner-Sillars polarization. Subsequent waves of charge particles are repelled by the attached charge resulting in the diffuse Gouy- Chapman transport layer. The simulation algorithm uses a boundary integral equation method (BIEM) for solution of the Poisson equation coupled with a second-order predictorcorrector scheme for robust time integration of the equations of motion. The stability criterion of the explicit algorithm conforms to the Courant-Friedrichs-Levy (CFL) limit assuring robust and rapid convergence. The model is capable of simulating a wide dynamic range spanning leakage current to pre-breakdown levels. Simulation results for semicrystalline film with varying degrees of crystallinity indicate that charge transport behavior depends on nanoparticle polarization with anti-parallel orientation showing the highest conduction and therefore lowest level of charge trapping in the interaction zone. Charge attachment to nanocrystallites increase with vol% loading or degree of crystallinity, and saturates at 40 vol% for the set of simulation parameters. The eEDL model predicts the intuitive meandering pathways of charge particle trajectories, which get progressively more inclined from normal incidence with increasing vol% loading. [ABSTRACT FROM AUTHOR]

Rail accelerators are superior to classical gas-driven accelerators with regard to attainable terminal velocity, ignition delay variation, and controllability. The behavior is generally described with a system of nonlinear differential equations, which can be solved in many ways. This is done in order to describe an existing launcher, to predict its performance when parameters change, or to estimate the properties of such a system in the design phase. This paper presents a simplified electromechanical system of differential equations in a novel form. This form enables scientists to solve the equations using one of the following software: Scilab, MATLAB, or a similar one. The model is robust and parameter changes have a low impact on the solving time. This makes it a reliable tool for parametric studies. The model comprises pulsed power capacitors, the pulse-forming network, cables, and the launcher itself. At first, the electrical part is described with its circuit equivalent and coupled with the mechanical process. Second, the system is analytically transposed to a standard form. This form is then transferred into the simulation software, which solves the equations. It can simply be adapted to other launchers and modified to comprise nonlinear side effects. The simulation results are compared with experimental results from the augmented rail accelerator at the French-German Research Institute of Saint-Louis, France. [ABSTRACT FROM PUBLISHER]

This paper presents an improved field weakening (FW) algorithm for synchronous-reluctance-motor drives. The proposed algorithm is robust to the variations in the machine $d$- and $q$-axis inductances. The transition between the maximum torque per ampere, current and voltage limits, and the maximum torque per flux trajectories is smooth. The proposed technique is combined with the direct-torque-control method to attain a high performance drive in the FW region. Simulation and experimental results are supplemented to verify the effectiveness of the proposed approach. [ABSTRACT FROM PUBLISHER]

This paper delivers a considerable improvement in the framework of the statistical simulation of highly nonlinear devices via polynomial chaos-based circuit equivalents. Specifically, a far more efficient and “black-box” approach is proposed that reduces the model complexity for nonlinear components. Based on recent literature, the “stochastic testing” method is used in place of a Galerkin approach to find the pertinent circuit equivalents. The technique is demonstrated via the statistical analysis of a low-noise power amplifier and its features in terms of accuracy and efficiency are highlighted. [ABSTRACT FROM AUTHOR]

In this paper, the mathematical modeling and simulation of the automatic control of the quintuple effect of evaporation of a sugar mill "El Palmar" in Venezuela is made. The multiple effect consist of 5 evaporators Robert type, with equal characteristics, connected in series. Starting from the desired operating conditions and control requirements: level in each evaporator vessel, cane syrup concentration and pressure in the fifth evaporator vessel using mass balances, balance on solids for each evaporator and energy to the barometric condenser is present at the output of the fifth vessel, the nonlinear model of the process is obtained, resulting in a system of multiple inputs and multiple outputs, with strong interactions between variables. In the design of the system of the automatic process control, we are interested in maintaining the variables that characterize the performance of it and they are regulated in an operating point; we proceed to linearize the model around an equilibrium point, resulting in a new model in terms of the variables variations around an environment from that point. Then, it is processed the model obtained in terms of input and output relations, based on the characterization of it in terms of variables and transfer relationships in the complex frequency domain. Finally, the evaporation process is simulated, establishing the adequacy of the model to the real process. [ABSTRACT FROM AUTHOR]

Background: Food tax-subsidy policies are proposed to hold promise for helping to produce healthier patterns of food purchasing and consumption at population level. Evidence for their effects derives largely from simulation studies that explore the potential effects of untried policies using a mathematical modelling framework. This paper provides a critique first of the nature of the evidence derived from such simulation studies, and second of the challenges of cumulating that evidence to inform public health policy. Discussion: Effects estimated by simulation studies of food taxes and subsidies can be expected to diverge in potentially important ways from those that would accrue in practice because these models are simplified, typically static, representations of complex adaptive systems. The level of confidence that can be placed in modelled estimates of effects is correspondingly low, and the level of associated uncertainty is high. Moreover, evidence from food tax-subsidy simulation studies cannot meaningfully be cumulated using currently available quantitative evidence synthesis methods, to reduce uncertainty about effects. Summary: Simulation studies are critical for the initial phases of an incremental research process, for drawing together diverse evidence and exploring potential longer-term effects. While simulation studies of food taxes and subsidies provide a valuable and necessary input to the formulation of public health policy in this area, they are unlikely to be sufficient, and policy makers should not place excessive reliance on evidence from such studies, either singly or cumulatively. To reflect known and unknown limitations of the models, results of such studies should be interpreted cautiously as tentative projections. Modelling studies should increasingly be integrated with more empirical studies of the effects of food tax and subsidy policies in practice. [ABSTRACT FROM AUTHOR]

Real-time (RT) simulation plays a fundamental role in the design and validation of hardware and software for power electronic converters and electric drives. In this paper, a field-programmable gate array (FPGA)-based RT platform for simulation of power converters and electric machines is presented. Strategies for modeling power electronic devices are explained and compared. In addition, a Thevenin-based equivalent model of a switch is enhanced to model the on characteristics of these devices. This motivates the design of an electrothermal algorithm for FPGA implementation. With respect to electric machines, different methods for modeling of the saturation characteristics are evaluated for their use in RT simulation. A procedure to efficiently compute the saturation characteristics is proposed. Finally, a hardware-in-the-loop model of an electric vehicle drive is used to illustrate the machine saturation. [ABSTRACT FROM PUBLISHER]

The step-stress model is becoming quite popular for analyzing lifetime data obtained from accelerated life testing experiments. In the usual step-stress experiment, stress levels are allowed to change at each step to get rapid failure of the experimental units. The simple step-stress model under different censoring schemes based on Weibull lifetimes is considered in this paper. It is assumed that the lifetime distributions of the experimental units have different scale parameters at different stress levels, but they have the same shape parameter. Moreover, it is assumed that the lifetimes follow the Khamis-Higgins model. It is further assumed that, as the stress level increases, the scale parameter also increases. We provide Bayesian inference of the unknown parameters of the Weibull distribution under this order restriction on the scale parameters. Monte Carlo simulations have been performed to see the effectiveness of the proposed method, and a data set has been analyzed for illustrative purposes. [ABSTRACT FROM PUBLISHER]

Visualizing the magnetic flux paths for wireless power transfer systems enables researchers and engineers to understand the operations and design the geometrical dimensions of the practical systems. However, time-domain transient simulations of 3-D electromagnetic fields of complex wireless power transfer systems with multiple coil-resonators are extremely time-consuming. This paper describes a fast hybrid approach that combines the time-domain coupled circuit modeling and the magnetostatic analysis to form a fast time-domain analytical tool for studying complex wireless power transfer systems. The proposed methodology has been successfully applied to several wireless domino-resonator systems. For the first time, the time-varying magnetic flux variations of wireless power domino-resonator systems can be visualized in computer simulations. [ABSTRACT FROM AUTHOR]

Insulator boundaries like electrode contacts, interfaces, and surfaces play decisive roles for the electric field distributions in high-voltage direct-current (HVDC) insulation. Well-known examples are charging effects at injecting and blocking electrode contacts, and at interfaces or surfaces. Reliable modeling of boundaries and interfaces poses a challenge and can be crucial for the quality of the resulting field distributions in HVDC equipment, but is in practice often put in second place of priority in simulation models. This paper emphasizes the macroscopic boundary conditions and related issues for electrical transport and illustrates their relevance with simple examples. Importance is attached to an appropriate compromise between physical generality and practical usability for simulations in the development process of HVDC insulation systems. [ABSTRACT FROM AUTHOR]

An array of weakly coupled oscillators can generate multiphase signals, i.e., multiple sinusoidal signals with specific phase separations. Multiphase oscillators are attractive solutions in many electronic applications such as the synchronization of multiple processing units in digital electronics and the frequency synthesis in mixed-signal radio frequency circuits. Due to the complexity of multiphase oscillators and the large number of design parameters, novel simulation techniques are highly desired to efficiently handle such large-scale problems. In this paper, an efficient phase-domain simulation technique is proposed to calculate the phase response of inductance capacitance oscillator array. By some practical examples, it is shown how the proposed method can be exploited to identify the array topologies and parameter settings that guarantee stable phase separations. It is also shown how the proposed technique can be used to evaluate phase-noise performance. [ABSTRACT FROM PUBLISHER]

The high-order $A$ - and $L$ -stable Obreshkov-based method was recently proposed for simulating the transient response of general nonlinear circuits in the time-domain. This method has consistently resulted in more than one order-of-magnitude speedup compared with the traditional methods used in the SPICE engine. Nonetheless, the formulation of this Obreshkov-based approach assumed that the memory elements in the circuits are characterized by a linear constituent equation. The goal of this paper is to generalize this approach to handle memory elements that are described by nonlinear constituent equations. [ABSTRACT FROM PUBLISHER]

In this paper, we set up an efficient Fréchet derivative algorithm of inversion of multicomponent induction logging (MCIL) data in horizontal layered transversely isotropic (TI) formations based on transmission line method (TLM) in order to simultaneously reconstruct the model vector including both horizontal and vertical conductivities, horizontal interfaces, borehole dipping angle, and tool azimuth in deviated well from the MCIL data. First, MCIL responses in the TI model are efficiently determined by both the spectrum EM fields obtained by TLM and the semianalytical computation of Sommerfeld integrals based on the cubic spline interpolation. Then, the Born approximations are executed to derive the MCIL Fréchet derivatives as the sixfold integrals of the products of two spectrum EM fields in infinite domains. By using the integral characters of the 2-D Dirac function, the sixfold integrals of Fréchet derivatives are further simplified into twofold integrals: One is the Sommerfeld integral in the radial spectrum domain, and the other is the definite integral in the vertical spatial domain. They are efficiently computed by the semianalytical approach similar to the MCIL simulation. Therefore, we obtain the linear equations between changes in the MCIL responses and small perturbations in the model vector. After that, we iteratively modify all of the model parameters to realize the best fit between the input data and the synthetic data of the inverted model by the normalization of the Fréchet derivative and singular value decomposition technique. Finally, we apply numerical results to investigate the characteristics of the Fréchet derivatives and to validate the inversion method and its antinoise ability. [ABSTRACT FROM PUBLISHER]

This paper presents a novel perturbation observer-based multiloop control method for the integrated control of the doubly-fed induction generator-based wind turbine (DFIG-WT) in a multimachine power system. The DFIG-WT is decoupled into four independent subsystems in accordance with four outputs. A perturbation state is introduced into each subsystem, and the optimal output feedback control of each subsystem is achieved with the estimate of perturbation obtained by a sliding-mode perturbation observer. Thus a four-loop perturbation observer-based control (POC) scheme is adopted to achieve the integrated control of the DFIG-WT. The design of the four-loop POC does not require any accurate system model, and it is robust to external disturbances and parameter variations. Meanwhile, the four-loop POC presents a fast tracking rate and shows the capability of damping the oscillations of output variables. Moreover, interactions between two DFIG-WT-based wind farms and their influence to the stability of power system are also investigated. Simulation studies reveal that superior integrated control of DFIG-WT can be achieved by the four-loop POC under various conditions compared with the conventional vector control scheme. [ABSTRACT FROM AUTHOR]

This paper mainly proposes a general model of eccentric squirrel-cage induction motor (SCIM), which includes the stator and rotor slotting effect as well as their individual tooth reluctance effect. Considering open slots on the stator and rotor, their rather exact shape is included in the machine's air gap function. Then, the resulting air gap function is used for evaluating various inductances of SCIM by the winding function approach (WFA). A simple general technique is used for adding eccentricity effect, including static, dynamic, and mixed eccentricities, on the air gap function and, therefore, on the inductances. Using a novel technique, saturable reluctance of each tooth of the stator and rotor is evaluated in every simulation step. Then, these reluctances are added to the model by equivalent increase of the air gap in front of the teeth; this reflects the teeth saturable reluctance effect on the inductances of the SCIM. In effect, dynamic simulation of SCIM with all aforementioned effects using WFA becomes possible. Simulation results compared to corresponding experimental results show accuracy and exactness of the proposed model. [ABSTRACT FROM PUBLISHER]

The modular multilevel converter (MMC) is a newly introduced switch-mode converter topology with the potential for high-voltage and high-power applications. This paper focuses on the design and control methods for fault-tolerant operation using redundant submodules (SMs), which is one of the most important features in the MMC topology. By comparing three design schemes of redundant SMs, the most economic and reliable scheme is identified. In addition, a mathematical model of the MMC with arms containing different numbers of SMs is developed. Based on the identified scheme and mathematical model, an energy-balancing control strategy is proposed to keep the MMC operating normally under SM fault conditions. Finally, time-domain simulations of a 61-level MMC system are performed, using the PSCAD/EMTDC software, while experiments are carried out on a 41-level MMC prototype. The simulation and experimental results validate the design scheme, mathematical model, and proposed energy-balancing control strategy. [ABSTRACT FROM AUTHOR]

Compressed sensing (CS) based radar imaging requires the use of a mathematical model of the observation process. Inaccuracies in the observation model may cause defocusing in the reconstructed images. In the observation process, the observation positions are usually not known perfectly. Imperfect knowledge of the observation positions is a major source of model errors in imaging. In this paper, a method is proposed to compensate the observation position errors in CS-based radar imaging. Instead of treating the observation-position-induced model errors as phase errors in the data, the proposed method can determine the observation position errors as part of the imaging process. It uses an iterative algorithm, which cycles through steps of target reconstruction and observation position error estimation and compensation. The proposed method can estimate the observation position errors accurately, and the reconstruction quality of the target images can be improved significantly. Simulation results and experimental results from rail-mounted radar and airborne synthetic aperture radar are presented to show the effectiveness of the proposed method. [ABSTRACT FROM PUBLISHER]

In this paper, we address a problem of 3-D reconstruction with generalized stereo data from multiple platforms of remote sensing. Nowadays, rational function model (RFM)-based 3-D reconstruction with stereo images obtained from a single platform of remote sensing like a satellite or an airborne platform has been widely investigated, but there are little attentions to be paid to the problem of 3-D reconstruction with stereo images from multiple platforms in the existing literature. In order to make full use of the generalized stereo images from different platforms with different rigorous sensor models for 3-D reconstruction, we need to form the least squares estimation model of the corresponding RFM-based forward-intersection task after collecting observations from different platforms. However, resolutions of the stereo images from different platforms are greatly different so that the observations in the corresponding least squares problem are mathematically seriously unbalanced. To solve this problem for achieving precise reconstruction, we first model how the spatial resolution of the observation images of different platforms changes pixel by pixel and then embed the variance-component-estimation technique into the RFM-based 3-D reconstruction procedure to adaptively adjust weights for different observations. Experiments are conducted on simulated and real data sets. Experimental results show that the proposed algorithm can efficiently fulfill the 3-D reconstruction task for multiplatform stereo images with noticeable improvement over the classical RFM-based 3-D reconstruction method in terms of precision. [ABSTRACT FROM PUBLISHER]

In this paper, we present a framework to analyze the propagation of measurement errors through the body composition equations. This is done through the equations for body composition assessment (BCA), for single/multifrequency (SF, MF) body impedance analysis (BIA) approaches. We show that it is possible to estimate a priori the error variance on the BCA parameters from the error measurement in the weight, height, and impedance. The theoretical results are validated through the simulation and experimental data coming from the low-cost AFE4300 impedance spectrometer developed by Texas Instruments. This new spectrometer has been calibrated and characterized by performing measurements on phantoms and foot-to-foot body impedance measurements. The influence of the number of measurement frequencies on the accuracy of BCA is also studied for MF-BIA approach. Ultimately, the measurement error framework can be used to evaluate the suitability of an impedance system for BIA. [ABSTRACT FROM PUBLISHER]

In this paper, a new method for modeling converter-based power generators in ac-distributed systems is proposed. It is based on the concept of electrostatic synchronous machines. With this new concept, it is possible to establish a simple relationship between the dc and ac side and to study stability in both the small and large signals of the microgrid by considering a dc-link dynamic and high variation in the power supplied. Also, for the purpose of illustration, a mathematical and electrical simulation is presented, based on MATLAB and PSCAD software. Finally, an experimental test is performed in order to validate the new model. [ABSTRACT FROM PUBLISHER]

This paper presents an electric circuit-based battery and a capacity fade model suitable for electric vehicles (EVs) in vehicle-to-grid applications. The circuit parameters of the battery model (BM) are extracted using genetic algorithm-based optimization method. A control algorithm has been developed for the battery, which calculates the processed energy, charge or discharge rate, and state of charge limits of the battery in order to satisfy the future requirements of EVs. A complete capacity fade analysis has been carried out to quantify the capacity loss with respect to processed energy and cycling. The BM is tested by simulation and its characteristics such as charge and discharge voltage, available and stored energy, battery power, and its capacity loss are extracted. The propriety of the proposed model is validated by superimposing the results with four typical manufacturers’ data. The battery profiles of different manufacturers’ like EIG, Sony, Panasonic, and Sanyo have been taken and their characteristics are compared with proposed models. The obtained battery characteristics are in close agreement with the measured (manufacturers’ catalogue) characteristics. [ABSTRACT FROM PUBLISHER]