Search

In this paper the accelerated aging experiments of oil-paper insulation are carried out to simulate the oil-paper aging process under normal thermal aging process. On the basis of the results of accelerated aging experiments, how the deviation degree of aging status change under the same aging factors is studied, and a method to calculate the failure probability due to the loss of mechanical strength of the insulation is put forward. This paper presents an approach for economic assessment on insulation diagnosis through accelerated aging experiments. The foundation of this approach for economic assessment on insulation diagnosis is to establish condition simulation method of triple relationships between condition status, aging time and failure probability according to data from accelerated aging experiments. The conclusions are made that the economic and technical factors can affect the optimum life cycle cost of each maintenance strategy, which consequently affects the economic feasibility of condition-based maintenance strategies. [ABSTRACT FROM AUTHOR]

In this paper, we solved a model of a well-known infectious disease called dengue fever via fractional natural decomposition and modified Predictor–Corrector (PC) methods. A study of the dengue epidemic in the Cape Verde Islands off the coast of West Africa in 2009 has been resumed here for a better understanding of the results. The results are obtained using Liouville–Caputo and new generalized Caputo-type fractional derivatives. The numerical simulations are presented for various orders of given derivatives. Existence and uniqueness analysis of the given problem are also performed in the new generalized Caputo sense. The explored results are verified using figures. The main target of this paper is to explore the different dynamics of the given dengue fever model via two types of fractional numerical algorithms. [ABSTRACT FROM AUTHOR]

To have a more realistic model, in this paper, This manuscript is devoted to investigating a fractional-order mathematical model of Kouidere et al. That describes the dynamics of spread of African swine fever virus (ASFV). The aim of this work is to protect susceptible pigs from the virus, In our model, by including three controls which represent: the iron fencing and spraying pesticides and get rid. The aims of this paper is to reduce the number of infected pigs and ticks by using optimal control strategy and fractinal order derivation. Pontryagin's maximal principle is used to describe optimal controls with Caputo time-fractional derivative and the optimal system is resolved in an iterative manner. Numerical simulations are presented based on the presented method. We finished tis article with a conclusion. [ABSTRACT FROM AUTHOR]

This paper contributes to the accurate and efficient computation of control system equations in electromagnetic-transient simulation tools. The proposed approach is based on the formulation of a reduced rank Jacobian matrix in a fully iterative Newton method. In addition, this paper compares the accuracy and efficiency for the proposed method's variants, including a hybrid approach with a fixed-point solution. [ABSTRACT FROM PUBLISHER]

Magnetic flux leakage (MFL) response predicting is important for defect estimation. This paper first proposes a concept of basic signal by discovering the combination property of the MFL response. The basic signal can be used to predict the MFL response conveniently by a basic signal combination method (BSCM), which is also innovatively put forward in this paper. In this method, the basic signal is calculated in advance, and the MFL response can be calculated by several transformation and combination operations. Both the simulation and experimental results demonstrate the feasibility of BSCM. Compared with other traditional methods (magnetic dipole method and finite-element method), BSCM shows a good performance on both the computational speed and accuracy. [ABSTRACT FROM AUTHOR]

This paper proposes a leader–follower-based model of mobile molecular communication networks for target detection applications. The proposed model divides the application functionalities of molecular communication networks into two types of mobile bio-nanomachine: leader and follower bio-nanomachines. Leader bio-nanomachines distribute in the environment to detect a target and create an attractant gradient around the target. Follower bio-nanomachines move according to the attractant gradient established by leader bio-nanomachines; they approach the target and perform necessary functionalities, such as releasing drug molecules. This paper develops mathematical expressions for the proposed model, describes wet laboratory experiments designed to estimate model parameters, and performs biologically realistic computer simulation experiments to evaluate the performance of the proposed model. The main contributions of this paper are to demonstrate the functional division of molecular communication networks, which will facilitate the design and development of molecular communication networks. Furthermore, insight into the application-level performance of molecular communication networks will be provided based on the proposed model. [ABSTRACT FROM PUBLISHER]

This paper presents a compact analytical I – V model for short-channel double-gate transition metal dichalcogenide filed-effect transistors in the subthreshold region. A closed-form expression is proposed for the characteristic length in the scale length approach, which is based on physical device parameters. It is then used to find the channel potential and drain current in the subthreshold region. This model is verified with the numerical results of a nonequilibrium Green’s function (NEGF) simulator. There is good agreement between the results of the proposed model and the numerical NEGF simulations in the subthreshold region, while it captures the effects of the device’s physical parameters. [ABSTRACT FROM PUBLISHER]

The dynamic interaction of vehicles/bridges is an important part of the research field of the Electromagnet Suspension (EMS) maglev train. However, multiple factors affect the dynamics of the coupling system, which increases the complexity of the vehicle-bridge coupling system, and makes it difficult to analyze. Herein, combining the advantages of theoretical derivation and numerical calculation, a fast and accurate analysis method of maglev vehicle and bridge system is proposed to analyze the influence of bridge and controller on the dynamics of the maglev system. This work is directed to the Changsha maglev express line, in which the mathematical equations for the vehicle- bridge system is presented. Then the influence of the parameter on the system is analyzed. Finally, the vibration experimental test system is set up, and the vibration test of the maglev vehicle bridge is tested by the test scheme, and the experimental results data are given. The test results of vibration acceleration are in good agreement with the calculation results of the proposed method, which verifies the accuracy of the model and the analysis method. Therefore, the research in this paper can provide theoretical guidance for Maglev engineering, and the analysis method in this paper can also be used in the study of other vehicles, such as the high-speed maglev train. [ABSTRACT FROM AUTHOR]

Lower limb rehabilitation robot (LLRR) users, to successfully conduct isotonic exercises, require real-time feedback on the torque they exert on the robot to meet the goal of the treatment. Still, direct torque measuring is expensive, and indirect encoder-based estimation strategies, such as inverse dynamics (ID) and Nonlinear Disturbance Observers (NDO), are sensitive to Body Segment Inertial Parameters (BSIPs) uncertainties. We envision a way to minimize such parametric uncertainties. This paper proposes two human–robot interaction torque estimation methods: the Identified ID-based method (IID) and the Identified NDO-based method (INDO). Evaluating in simulation the proposal to apply, in each rehabilitation session, a sequential two-phase method: (1) An initial calibration phase will use an online parameter estimation to reduce sensitivity to BSIPs uncertainties. (2) The torque estimation phase uses the estimated parameters to obtain a better result. We conducted simulations under signal-to-noise ratio (SNR) = 40 d B and 20% BSIPs uncertainties. In addition, we compared the effectiveness with two of the best methods reported in the literature via simulation. Both proposed methods obtained the best Coefficient of Correlation, Mean Absolute Error, and Root Mean Squared Error compared to the benchmarks. Moreover, the IID and INDO fulfilled more than 72.2% and 88.9% of the requirements, respectively. In contrast, both methods reported in the literature only accomplish 27.8% and 33.3% of the requirements when using simulations under noise and BSIPs uncertainties. Therefore, this paper extends two methods reported in the literature and copes with BSIPs uncertainties without using additional sensors. [ABSTRACT FROM AUTHOR]

The paper presents the results of experimental registrations and numerical simulations of the transient overvoltages caused by single phase intermittent arc earth fault in 35 kV network with isolated neutral. Experimental laboratory investigation is performed in order to implement appropriate arc fault model for arcs with low and discontinuous current. Single phase to earth arc fault is created in field in 35 kV network. Numerical model of the system is created in EMTP-ATP software. Overvoltage waveshapes and overvoltage factors are calculated and compared to measured values. Good agreement between the measured and calculated results is achieved. [ABSTRACT FROM AUTHOR]

Silicon carbide (4H-SiC) devices experiencing avalanche conditions can reach temperatures above 1500 K. Simulation of impact ionization in devices should, therefore, include models valid up to such high temperatures. However, calibrations of impact ionization coefficients are available only up to 580 K, and simulations of switching show deviations from measurements at higher temperatures. In this paper, a more accurate model based on the underlying physics of high temperature and anisotropic avalanche generation is proposed. This model enables calibrations performed at room temperature along the ${c}$ -axis to be more precisely extrapolated to any temperature of interest in 2-D device simulations. The model provides an excellent fit to the measurements of breakdown voltages during unclamped inductive switching tests of power MOSFETs, enabling a more accurate prediction of ruggedness. The more comprehensive physics included in the model makes it also applicable to other wide bandgap semiconductors such as GaN, diamond, and Ga2O3, which also exhibit a high critical electric field. [ABSTRACT FROM AUTHOR]

Accurate modeling of soft- and hard-magnetic materials for the numerical simulation of rotating electrical machines is required to allow predictions on the operational characteristics along the torque–speed map, already in the design stage. The full potential of most appropriate material selection and concurrent geometry adaption can only be utilized if models can represent actual material behavior. The accurate prediction of iron losses of soft-magnetic materials for various frequencies and magnetic flux densities, as well as the degradation due to manufacturing is eminent for the design of electrical machines. Therefore, advanced material models need to be adapted and their accuracy examined to further improve the modeling and enable progression. This paper will give an overview of the current modeling approaches applied at the Institute of Electrical Machines for soft- and hard-magnetic materials in the simulation of rotating electrical machines. A case example in the form of a traction drive is presented to which the models are applied. For the machine modeling, the inhouse solver pyMOOSE is utilized. In order to determine the losses with regard to manufacturing processes, the iron-loss model with material degradation is used in combination with a machine simulation scheme of the entire operating range of the machine. Here, various simulation approaches are combined to form the entire computational toolchain to obtain accurate results in the entire operational range. [ABSTRACT FROM AUTHOR]

This paper presents the numerical calculation of the relative sliding distance between the pad and the wafer in a rotary-type chemical-mechanical planarization (CMP) system. The numerical scheme developed in this paper considered most of the possible kinematical and geometrical variables. While the pad was rotating, and the wafer was rotating and sweeping, the point trajectories on the wafer were calculated by standard coordinate transformations. The effect of groove patterns on the pad surface was investigated for the relative sliding distance of the wafer. Three types of pad surface geometries, namely flat, circular-type, and rectangular-type grooves, were considered. From the simulation results, we evaluated the nonuniformity (NU) of the relative sliding distance distribution on the polished wafer surface. It was found that the groove patterns have a significant effect on the result of the CMP, as well as the width and pitch of the groove. It was found that the groove patterns increase the NU of the sliding distance distribution. The circular-type groove caused the greater NU than the rectangular-type groove under the identical operating conditions. The optimized operating conditions were varied for different types of the groove patterns. The simulation method proposed in this paper may be further extended to analyze other process variables. [ABSTRACT FROM AUTHOR]

In this paper, we present the design of metallic reflectarray antennas consisting of convex nonresonant elements to radiate multiple beams with optimum radiation gains and relatively orthogonal overlapping. In particular, an antenna is realized at 38 GHz to provide sufficient gains and beam widths for simultaneous link-budget and radio coverage satisfaction in the applications of fifth-generation mobile communications. The pattern optimization employs the steepest decent method (SDM) to optimize the phases of reflecting elements for gain tradeoff. The SDM procedure is very efficient because relatively simple formulations of analysis in closed form are developed to subsequently update the phases in each iteration. This procedure avoids the cumbersome and numerous full-wave numerical simulations of scattering fields. Design examples and their radiation characteristics are presented to demonstrate the concepts and validate the feasibility. [ABSTRACT FROM AUTHOR]

A conjugate-gradient-based regularization technique in $L^{p}$ Banach spaces, in conjunction with an inexact-Newton solving scheme, is presented in this paper. The proposed method is applied to obtain the reconstruction of the dielectric properties of human tissues in hemorrhagic brain stroke microwave imaging. The dielectric reconstruction is obtained by solving a nonlinear inverse problem, starting from a set of scattered-field measurements. The presented numerical simulations with 2-D and 3-D anatomically realistic phantoms, as well as the preliminary experimental results, show that this method can be useful for retrieving the dielectric properties of the human head with a reduced over-smoothing effect in the final images. [ABSTRACT FROM AUTHOR]

In earlier papers, analytical formulas were derived to estimate the maximum crosstalk in the frequency domain for systems with electrically long signal lines. These formulas were developed to give designers intuitive feedback as to the causes for crosstalk problems and methods for maximum crosstalk reduction. In one of these papers, the maximum crosstalk estimates are based on intuitive relationships for infinitely long transmission lines. While the resulting model is quite simple and easy to understand, its limitations are poorly understood. In another paper, the maximum crosstalk estimates are based on a mathematically rigorous integral formulation, but the resulting model is relatively complex. This rigorous model is derived assuming the signal lines are weakly coupled and the transmission line characteristic impedances are approximately the same over the entire lengths of the aggressor and victim circuits. The following paper illustrates how the less rigorously developed estimates, based on infinitely long transmission lines, may be derived from the mathematically rigorous maximum crosstalk estimates for lossless and homogeneous transmission lines in the frequency domain. The resulting derivation provides insight into the limitations and mathematical validity of the less rigorous estimates that are not available in the original paper. The mathematically rigorous maximum crosstalk estimates are shown to have fewer and less restrictive assumptions than the estimates based on infinitely long transmission lines. Measurements and simulations are presented that validate results and illustrate maximum crosstalk estimate limitations. [ABSTRACT FROM AUTHOR]

Industrial wind turbines are large constructions that require in-field monitoring. In this paper, short-range Doppler radar signatures of wind turbines are both mathematically analyzed and practically verified through simulations and experiments. Two custom-designed radar prototypes that operate at the $C$ and $K$ bands, respectively, are employed in the acquisition campaign. The unique features of the radar signal—in particular, some observed energetic flashes in the time-Doppler map—appear as curved lines for specific acquisition scenarios and/or for nonstraight blades. Furthermore, it is demonstrated that the use of high-frequency radar systems is beneficial in terms of improved spectrogram resolution. Experimental results coming from a 50-m-height wind turbine and a curved-blade 12-m-height turbine are also discussed, in this paper, in the context of the provided theoretical and simulation frameworks. This paper paves the way for noncontact structural health monitoring of industrial-type wind turbines through portable low-cost Doppler radar sensors. [ABSTRACT FROM AUTHOR]

Efficient performance modeling of today’s analog and mixed-signal circuits is an important yet challenging task, due to the high-dimensional variation space and expensive circuit simulation. In this paper, we propose a novel performance modeling algorithm that is referred to as Bayesian model fusion (BMF) to address this challenge. The key idea of BMF is to borrow the information collected from an early stage (e.g., schematic level) to facilitate efficient performance modeling at a late stage (e.g., post layout). Such a goal is achieved by statistically modeling the performance correlation between early and late stages through Bayesian inference. Furthermore, to make the proposed BMF method of practical utility, four implementation issues, including: 1) prior mapping; 2) missing prior knowledge; 3) fast solver; and 4) prior and hyper-parameter selection, are carefully considered in this paper. Two circuit examples designed in a commercial 32 nm CMOS silicon on insulator process demonstrate that the proposed BMF method achieves up to $9\times $ runtime speed-up over the traditional modeling technique without surrendering any accuracy. [ABSTRACT FROM AUTHOR]

Investigating random telegraph signals (RTS) observed in MOS devices is important for studying the gate-oxide defect characteristics and developing simulation and modeling tools in highly scaled devices. In this paper, we are presenting a comprehensive, variable-temperature, single-to-multitrap scalable RTS model and a simulation tool (RTSSIM) based on the first principles, and supported by experimental data. The physical and electrical characteristics of the actual oxide defects are considered, such as trapping barrier energy, capture cross section, trap-binding enthalpy, entropy change with emission, Coulombic scattering effect, and the trap location. Experimentally obtained time-domain switching data and RTS traces reconstructed by the developed simulation tool are compared for assessing the accuracy of the modeling. In this paper, we identified the trap species responsible for the RTS as an unrelaxed neutral oxygen deficiency center ( V^0 ODC II) with measured and theoretically verified relaxation energy of 1.11, 1.25, and 0.60 eV. RTSSIM is a tool used to mimic or reproduce a given noise measurement on a particular device. The simulation tool shows over 92% accuracy in replicating the RTS and trap characteristics. The model also represents the first realistic simulation of multilevel RTS. [ABSTRACT FROM AUTHOR]

In this paper, the use of the Dual Kalman Filter for the identification of photovoltaic system parameters is presented. The system includes the photovoltaic source, the dc/dc converter and the battery/dc bus and both its states and parameters in the actual operating conditions are identified. In particular, the proposed approach gives the confidence interval for the system settling time, which is used for the real-time optimization of the perturbative maximum power point tracking algorithm. The proposed technique is implemented by using a Field-Programmable Gate Array and it is validated by means of both simulation and experimental results. [ABSTRACT FROM PUBLISHER]

In this paper, the importance of inventory management for gaining a competitive advantage of a certain enterprise is shown. Furthermore, the basic - deterministic model of inventories is presented and the methodology for determining the optimal quantity of order is given. In addition, the stochastic inventory model has been developed with a detailed analysis of the uniform and normal distribution of demand probabilities. In order to introduce the reader to the computer simulation of inventory management, a brief overview of the general principles of simulation methods is given, with their advantages and disadvantages. Moreover, a computer simulation of the management of inventories for a specific case was performed by developing a software application in the Python programming language. The results of the simulation modeling are shown in tabular and graphical form. In the conclusion, an interpretation of the obtained results from the execution of the program is given and proposed guidelines for further research are given by simulating other parameters of the inventory, when the following occur as random variables: order quantities, the level to be re-ordered, the cost of inventory and delivery time. Validation of the mathematical model has been performed and it has been compared with similar mathematical models based on which it has been shown that the results are realistic and expected. [ABSTRACT FROM AUTHOR]

In this paper, characteristic model-based modeling and control approaches for complex dynamical networks based on sampled data are studied. It shows that the characteristic model, in which underline network topological structures are simplified, can provide a straightforward and implicit description for network dynamics. The induced parameter estimation method can further make the model adaptive and purely data-driven. Moreover, a control law based on this model is also proposed to govern the network dynamics. Finally, the theoretical results are verified through numerical simulations of modeling and stabilizing a dynamical network. [ABSTRACT FROM AUTHOR]

As is well known, a roadblock to realizing the full potential of GaN high-electron mobility transistors (HEMTs) for power amplifier applications is the peaked nature of the transconductance and the resulting power-gain roll-off exhibited by these devices. Motivated by promising work on compositionally graded HEMT designs, in this paper we explore this design solution using the numerical device simulation. Among other things, we examine the consequences of saturation velocity, grading profile, alloy scattering, and device scaling. In addition, lumped element modeling of the large-signal behavior is carried out to assess the power amplifier performance. We also compare the graded approach with another known method of linearity improvement in which the source resistance is reduced. In general, we find much to recommend in the graded-channel approach, especially for gate lengths greater than about 100 nm. [ABSTRACT FROM AUTHOR]

Microgrids (MGs) are often unbalanced due to the integration of single-phase generators, unbalanced loads, and asymmetrical faults. To better analyze such MGs, this paper presents an approach to analyze the transient response for an inverter-based MG under the unbalanced condition. The dynamic phasor (DP) concept is used for the MG modeling under the stationaryabcreference frame. First, the DP model of the inverter-based distributed generation (DG) is developed. The influence of unbalanced conditions on the inverter including oscillations on the dc side is considered in this paper. Then, the model of the network and loads is developed. Finally, all the submodules are combined on a time-variable system frequency to obtain the complete DP model of the unbalanced MG. To validate the proposed approach, the DP method is applied to an MG test system with three-phase and single-phase DGs. Small-signal analysis is carried out to derive the dominant modes and their influence on the system response. Simulation results from the DP model are compared against the detailed model built in MATLAB/SimPowerSystem. The results from load disturbances and asymmetrical faults are used to verify the DP model. [ABSTRACT FROM AUTHOR]

This paper has a twofold goal. The first aim is to provide a deeper understanding of the family of the real elliptically symmetric (RES) distributions by investigating their intrinsic semiparametric nature. The second aim is to derive a semiparametric lower bound for the estimation of the parametric component of the model. The RES distributions represent a semiparametric model, where the parametric part is given by the mean vector and by the scatter matrix, while the non-parametric, infinite-dimensional, part is represented by the density generator. Since, in practical applications, we are often interested only in the estimation of the parametric component, the density generator can be considered as nuisance. The first part of this paper is dedicated to conveniently place the RES distributions in the framework of the semiparametric group models. In the second part, building on the mathematical tools previously introduced, the constrained semiparametric Cramér–Rao bound (CSCRB) for the estimation of the mean vector and of the constrained scatter matrix of a RES distributed random vector is introduced. The CSCRB provides a lower bound on the mean squared error of any robust $M$ -estimator of mean vector and scatter matrix when no a priori information on the density generator is available. A closed-form expression for the CSCRB is derived. Finally, in simulations, we assess the statistical efficiency of the Tyler's and Huber's scatter matrix $M$ -estimators with respect to the CSCRB. [ABSTRACT FROM AUTHOR]

In this paper, a mixed finite-element time-domain (FETD) method is presented for the simulation of electrically complex materials, including general combinations of linear dispersion, instantaneous nonlinearity, and dispersive nonlinearity. Using both edge and face elements, the presented method offers greater geometric flexibility than existing finite-difference time-domain (FDTD) implementations, and in contrast to existing nonlinear FETD methods, also incorporates both linear and nonlinear material dispersions. Dielectric nonlinearity is incorporated into the Crank–Nicolson mixed FETD formulation via a straightforward Newton–Raphson approach, for which the associated Jacobian is derived. Moreover, the dispersion is modeled via the Möbius $z$ transform method, yielding a simpler more general algorithm. The method’s accuracy and convergence are verified, and its capability demonstrated via the simulation of several nonlinear phenomena, including temporal and spatial solitons in two spatial dimensions. [ABSTRACT FROM AUTHOR]

This paper presents the results of predictive calculations of the parameters of pulses of soft X-ray radiation (SXR) on a four-module electrophysical facility GAMMA-4 (the current pulse amplitude is ~3 MA with rise time of ~60 ns) that has been constructed in Russia. Scaling numerical simulation of implosion of a cylindrical single and nested multiwire array in 0-D, 2-D, and 3-D radiation magnetohydrodynamic– approximations is performed, taking into account, the updated double-loop equivalent electrical circuit of the GAMMA-4. The main purpose of the conducted studies was the numerical optimization of the multiwire array parameters to obtain the best characteristics of the SXR pulse generated as a result of Z-pinch implosion on the axis of the system. [ABSTRACT FROM AUTHOR]

This paper presents an algorithm for fast, directional detection of phase-to-ground faults in isolated neutral distribution grids. The method reacts directionally and very fast to fault conditions (1–2 samples after fault inception, even without large di0/dt). Moreover, the method is able to detect low- and high-impedance faults (HIF), permanent or transient faults. The algorithm is independent of the sampling frequency, very robust to noise, and does not need calibration of the sensors. The direction detection method relies on the fault model identification, based on the zero-sequence grid capacitance estimate for isolated neutral grids. The estimate is obtained from the fault circuit differential equation, solved with the least-squares method, where appropriate numerical modifications have been introduced. The sign of the estimate provides the directional information, whereas the magnitude of the modified estimate indicates the fault. The directional principle is validated in simulation and the fault detection method is validated with real fault records from the RedNA project. The paper reworks the equations that define the nondetection zone, so that the method is comparable to the classical residual overcurrent and overvoltage functions, typically used to detect HIF. [ABSTRACT FROM AUTHOR]

In this paper, the model predictive current control is introduced in the semicontrolled open-winding permanent magnet synchronous motor (OW-PMSM) generation system with a common dc bus to suppress the zero-sequence current for the first time. Particularly, the basic voltage vectors of the semicontrolled OW-PMSM, which are synthesized by the three-phase full-controlled converter and the three-phase uncontrollable diode bridge, is analyzed and their influences on the zero-sequence current are investigated for the first time in this paper. Then the current-error-based cost function that includes dq-axis current error and zero-sequence current error is designed to evaluate all the voltage vectors. Moreover, to further improve the steady-state control performance of the whole generation system, a zero-sequence current suppression method based on the uncontrollable side voltage vector adjustment, which has the advantage of low computation burden, is developed. In this method, two voltage vectors of the controllable converter are applied during one control period. Based on the distribution character of the basic voltage vector in the semicontrollable OW-PMSM generation system, the first voltage vector is selected according to the three-phase current direction to adjust equivalent vector of the uncontrollable diode bridge, whereas for the second voltage vector, the selection method based deadbeat voltage vector sector is designed to reduce the range of the candidate voltage vector. In addition, the vector durations are also computed. Finally, simulation and experiment are carried out to validate the proposed control approaches. [ABSTRACT FROM PUBLISHER]

This paper proposes a single-stage three-phase-to-single-phase current-fed high step-up ac–dc matrix converter. The proposed converter inserts a boost-type matrix converter, which is formed by three boost inductors and six bidirectional switches, between a three-phase ac source and a Cockcroft–Walton voltage multiplier (CWVM). By using this topology associated with power factor correction technique, the proposed converter not only achieves almost unity power factor and sinusoidal input currents with low distortion but also obtains high voltage gain at the output end. Moreover, the matrix converter generates an adjustable-frequency and adjustable-amplitude current, which injects into the CWVM to regulate the dc output voltage and smooth its ripple. With this flexible injection current, the performance of the proposed converter is superior to the conventional CWVM, which is usually energized by a single-phase ac source. The operation principle, control strategy, and design considerations of the proposed converter are detailed in this paper. Finally, simulation and experimental results demonstrate the claims and validity of the proposed converter. [ABSTRACT FROM PUBLISHER]

This paper presents an optimal control algorithm for connected cruise control (CCC) system in the presence of the stochastic communication delays. In the CCC system, wireless vehicle-to-vehicle (V2V) communication is the key factor to achieve comprehensive environment perception while it gives rise to delays in the meantime. In order to compensate for the influence of the stochastic delays and develop an optimal controller for the CCC system, we first analyze the vehicle dynamics with the car-following model. Then, the mathematical platoon model is formulated with heterogenous platoon structure. With the objective of minimizing the deviations of vehicle's headway and velocity, a linear quadratic optimization problem is formulated. The optimal control strategy is solved in an iterative manner by using a backward recursion which can be divided into two steps. In particular, the optimal control gain is iteratively derived off-line and the control strategy is calculated on-line. In addition, the control gain convergence, the stability analysis, and the effect of the packet losses and state noises are analyzed. Finally, the stability and performance of the proposed control algorithm are verified by numerical simulations to highlight its superiority compared with the existing algorithms. [ABSTRACT FROM AUTHOR]

In this paper, a technique for designing fixed parameter decentralized power system stabilizers (PSSs) for interconnected power systems is proposed. In the proposed method, local information available at each machine in the multimachine environment, is used to tune parameters of PSS. Conventional design techniques such as P-Vr frequency response approaches, and the method of residues are based on complete system information, wherein phase angles of residues are consistent with the P-Vr phase response and can be used with confidence for design purposes. It is shown that magnitude and phase information of the proposed GEP TF agrees closely with that of P-Vr TF and yields a robust stabilizer. Nonlinear simulation and eigenvalue analysis show the efficacy of the proposed stabilizer to damp out the interarea and local modes of oscillations effectively over a wide range of operating conditions. Superiority of the proposed approach over the conventional approaches is demonstrated with simulation studies on two widely used multimachine systems. [ABSTRACT FROM AUTHOR]

As wind penetration increases in power systems around the world, new challenges to the controllability and operation of a power system are encountered. In particular, frequency response is impacted when a considerable amount of power-electronics interfaced generation, such as wind, is connected to the system. This paper uses small-signal analysis and dynamic simulation to study frequency response in power systems and investigate how Type-3 DFAG wind turbines can impact this response on a test power system, whose frequency response is determined mainly by a frequency-regulation mode. By operating the wind turbines in a deloaded mode, a proposed pitch-angle controller is designed using a root-locus analysis. Time simulations are used to demonstrate the transient and steady-state performance of the proposed controller in the test system with 25% and 50% wind penetration. [ABSTRACT FROM PUBLISHER]

This paper presents a modified method for power system transient stability analysis, allowing the reduction of the computational requirements while retaining important system dynamics. The approach formulates the power balance equations depending on the area of interest. The detailed ac model, including full real and reactive power equations, is used for the area in which high accuracy is required, while the simpler dc model, including linear real power equation, is used for more remote areas where real power dynamics dominate. A high level of accuracy can be achieved using the ac model in the area of interest, and computational complexity can be reduced with the less detailed dc model in the remainder of the system. In order to prevent the loss of simulation accuracy, this paper proposes a way to compensate line losses neglected using the dc model. Case studies with the IEEE 118-bus system are provided to validate the performance of the proposed method. [ABSTRACT FROM PUBLISHER]

In this paper, we analyze dynamic switching networks, wherein the networks switch arbitrarily among a set of topologies. For this class of dynamic networks, we derive an epidemic threshold, considering the susceptible-infected-susceptible epidemic model. First, an epidemic probabilistic model is developed assuming independence between states of nodes. We identify the conditions under which the epidemic dies out by linearizing the underlying dynamical system and analyzing its asymptotic stability around the origin. The concept of joint spectral radius is then used to derive the epidemic threshold, which is later validated using several networks (Watts–Strogatz, Barabasi–Albert, MIT reality mining graphs, Regular, and Gilbert). A simplified version of the epidemic threshold is proposed for undirected networks. Moreover, in the case of static networks, the derived epidemic threshold is shown to match conventional analytical results. Then, analytical results for the epidemic threshold of dynamic networks are proved to be applicable to periodic networks. For dynamic regular networks, we demonstrate that the epidemic threshold is identical to the epidemic threshold for static regular networks. An upper bound for the epidemic spread probability in dynamic Gilbert networks is also derived and verified using simulation. [ABSTRACT FROM PUBLISHER]

This paper deals with embedded real-time (RT) simulators applied in power electronic applications and implemented in low-cost field-programmable gate arrays. Indeed, such simulators' intellectual properties (IPs) are not only intended for hardware-in-the-loop (HIL) testing but also can be advantageously embedded within digital controllers to ensure functions such as observation, estimation, diagnostic, or health monitoring. Conversely, to the HIL case, the main challenge when designing such simulators' IPs is to cope with their complexity having in mind that, in the case of embedded systems, the available hardware resources are limited due to the cost. Furthermore, this challenge is strengthened by the need of very short simulation time steps that is typically the case when simulating power converters. By this way, this paper presents the design of an embedded RT simulator of a three-phase grid-connected voltage-source rectifier, based on the associated discrete circuit modeling approach. This IP is associated with the one of a three-phase $RL$ filter, and both are implemented within the rectifier controller to estimate the grid currents. The latter is injected in the controller when a fault is detected in the current sensors. The ability of this estimator to guarantee the service continuity in case of faults has been validated through HIL tests and experiments. [ABSTRACT FROM PUBLISHER]

A new theory about terminal technology is proposed for superjunction lateral double-diffused metal–oxide–semiconductor field effect transistors with multiple floating buried layers (MFBL SJ-LDMOS) based on the bulk electric field (E-field) modulation in this paper for the first time. A concise and efficient analytical theory is presented to predict the vertical voltage and bulk E-field distributions of MFBL SJ-LDMOS. The analytical formulas for the breakdown voltage (BV) and the vertical peak E-field of MFBL SJ-LDMOS are derived in the closed-form equations, which starts from a single floating buried layer for the vertical E-field modulation, extending this theory to predict the vertical E-field peaks and vertical voltage distributions between the MFBLs. Quantitative analytical description has been given to explain the bulk E-field modulation for the MFBL. Moreover, the optimal spacing and the maximum BV are procedurally predicted. All analytical results are well verified by the 3-D numerical simulations, proving the applicability of the method presented in other power devices with MFBL including MFBL LDMOS, MFBL lateral insulated gate bipolar transistor, and MFBL diode. [ABSTRACT FROM AUTHOR]

This paper studies the network connectivity problem in a vehicular network and focuses on the two-way connectivity of vehicles moving on a one-way highway road with one entry and exit. The entry and exit separates the road into two segments, where vehicle arrivals follow a Poisson process. At the entry and exit, a vehicle may enter or exit from the road, or drive through the entry and exit. A connectivity analytical model is derived for analyzing the connectivity probability of vehicles moving on the road. The analytical model takes into account several parameters that may affect the connectivity probability, including a vehicle's arrival rate and moving speed as well as the probability that a vehicle drives through the entry and exit. Moreover, it considers two entry and exit scenarios: one with no roadside unit (RSU) deployed, and the other with one RSU deployed. The analytical model is justified through simulation results and the impacts of different parameters on the connectivity probability are investigated based on the derived analytical model. [ABSTRACT FROM PUBLISHER]

The nine-switch converter is a multiport converter having two three-phase terminals and a dc-link, just like a 12-switch back-to-back (BTB) converter, but with 25% reduction of active switch count. However, the reduction from 12-switch to 9-switch may not always be an efficient choice considering losses in the switches. Only the load–source combination for the ac–ac common frequency mode and the source–source combination for the ac–dc different frequency (ac–dc DF) mode have been reported, so far, to yield relatively lower loss for the nine-switch converter. This paper shows that the nine-switch converter can have relatively lower loss even with a load–source combination, instead of only source–source combination in its ac–dc DF mode—when the upper terminal is connected to a dc load and the lower terminal is connected to an ac source. Mathematical proof is presented with derivation of the particular operating parameters for which the nine-switch converter will have comparatively lower losses. The analysis is validated with simulation and experimental results of a 1-kW system. Finally, the benchmark of the application criteria of the nine-switch converter for having lower conduction loss than the BTB converter is updated in this paper. [ABSTRACT FROM AUTHOR]

The built-in potential ( V\text {bi} ) of an organic diode and solar cell is an important parameter that decides the rectification behavior of organic diodes and affects the open circuit voltage and thereby the efficiency of organic solar cells. In this paper, we propose a physics-based model and an experimental method to extract V\text {bi} from current density–voltage ( J – V ) characteristics. The proposed model is developed by solving the carrier transport and the continuity equations to obtain the analytic equations for charge carrier profile and current density. The proposed method is thoroughly verified using numerical simulation results. Applicability of this method on experimental results is further validated for poly(3-hexylthiophene):phenyl-C61-butyric acid methyl ester solar cells. Finally, V\text {bi} is extracted from dark J – V characteristics of fabricated devices. [ABSTRACT FROM PUBLISHER]

In order to solve the accuracy problem caused by lens distortions of nonmetric digital cameras mounted on an unmanned aerial vehicle, the estimation for initial values of lens distortion must be studied. Based on the fact that radial lens distortions are the most significant of lens distortions, a simple and efficient method for radial lens distortion estimation is proposed in this paper. Starting from the coplanar equation, the geometric characteristics of the relative orientation equations are explored. This paper further proves that the radial lens distortion can be linearly estimated in a continuous relative orientation model. The proposed procedure only requires a sufficient number of point correspondences between two or more images obtained by the same camera; thus it is suitable for a natural scene where the lack of straight lines and calibration objects precludes most previous techniques. Both computer simulation and real data have been used to test the proposed method; the experimental results show that the proposed method is easy to use and flexible. [ABSTRACT FROM PUBLISHER]

Power transmission through power cables installed in ventilated tunnels is increasingly used worldwide and offers a complex thermal environment. Established correlations currently in use have been deduced from a nonfully developed turbulent flow and the effect of the proximity to a tunnel wall is not accounted for. This paper details the experimental and numerical investigations conducted on a mock-up of the heat transfer from a single cable in a fully developed turbulent airflow, with emphasis on the effect of the cable spacing from the tunnel wall. Nusselt numbers have been compared for different spacing and Reynolds numbers. The overall heat transfer is found to be meaningfully lower than in previous studies as only a third of the heat transfer is found, possible explanation of these differences are given in this paper. A threshold value is observed for the heat transfer while the cable rating depreciation is more gradual. The radiative heat exchange is found to be up to 30% of the total heat loss. An improved cooling law for the case of a single cable in tunnel taking into account the proximity of the wall has been developed from this study and confronted to the experimental and simulated data. [ABSTRACT FROM AUTHOR]

Numerical modeling and simulations have been essential for rapid developments of vacuum electronic devices. Pseudospectral solvers have interesting capabilities to be considered, but up to now, they have not been extensively used for the modeling of vacuum tubes. In this paper, we present a novel 1-D time-domain numerical scheme which has the great aptitude of considering geometrical dispersion characteristic of helix traveling-wave tube (TWT) in time domain. This ability is interesting for one-run investigation of time-domain events such as pulse excitation of wideband tubes. The numerical model is extended to have simultaneously arbitrary order of accuracy in space and time derivations; so we achieve a code which presents a very low level of numerical dispersion error, without forcing a notable numerical calculation burden. To validate our new simulation tool, we have studied the experimental results of a TWT product, and successfully compared the results to the impulse response of the new 1-D code. [ABSTRACT FROM AUTHOR]

Simulated ultrasound data is a valuable tool for development and validation of quantitative image analysis methods in echocardiography. Unfortunately, simulation time can become prohibitive for phantoms consisting of a large number of point scatterers. The COLE algorithm by Gao et al. is a fast convolution-based simulator that trades simulation accuracy for improved speed. We present highly efficient parallelized CPU and GPU implementations of the COLE algorithm with an emphasis on dynamic simulations involving moving point scatterers. We argue that it is crucial to minimize the amount of data transfers from the CPU to achieve good performance on the GPU. We achieve this by storing the complete trajectories of the dynamic point scatterers as spline curves in the GPU memory. This leads to good efficiency when simulating sequences consisting of a large number of frames, such as B-mode and tissue Doppler data for a full cardiac cycle. In addition, we propose a phase-based subsample delay technique that efficiently eliminates flickering artifacts seen in B-mode sequences when COLE is used without enough temporal oversampling. To assess the performance, we used a laptop computer and a desktop computer, each equipped with a multicore Intel CPU and an NVIDIA GPU. Running the simulator on a high-end TITAN X GPU, we observed two orders of magnitude speedup compared to the parallel CPU version, three orders of magnitude speedup compared to simulation times reported by Gao et al. in their paper on COLE, and a speedup of 27000 times compared to the multithreaded version of Field II, using numbers reported in a paper by Jensen. We hope that by releasing the simulator as an open-source project we will encourage its use and further development. [ABSTRACT FROM AUTHOR]