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This paper presents the interaction between the overhead transmission lines (OHTLs) and their towers. In this paper, the electric field around the tower of the overhead transmission lines is calculated. The charge simulation method, combined with the image method, is used to develop a model that consists of subconductors of the OHTLs and the tower. The charges on the surface of each subconductor of the overhead transmission lines are simulated by a set of infinite line charges, of various charge densities, along the length of the subconductor, and the induced charges on the surface of the tower are simulated by a set of finite line charges. [ABSTRACT FROM PUBLISHER]

Transient simulation programs, either nodal analysis-based electromagnetic transient program (EMTP-like) or state-variable-based, are used very extensively for modeling and simulation of various power and energy systems with electrical machines. It has been shown in the literature that the method of interfacing machine models with the external electrical network plays an important role in numerical accuracy and computational performance of the overall simulation. This paper considers the state-variable-based simulation packages, and provides a constant-parameter decoupled RL-branch equivalent circuit for interfacing the ac induction and synchronous machine models with the external electrical network. The proposed interfacing circuit is based on the voltage-behind-reactance formulation which has been shown to have advantageous properties. For the synchronous machines, this paper describes both implicit and explicit (approximate) interfacing methods. The presented case studies demonstrate the advantages of using the proposed interfacing method over the traditional qd-models that are conventionally used in many simulation packages. [ABSTRACT FROM AUTHOR]

Multiphase (more than three phases) power electronic converters are required mainly for feeding variable-speed multiphase drive systems. This paper presents one such solution by using a direct ac–ac converter that can be used to supply a nine-phase drive system. The input is a fixed-voltage and fixedfrequency three-phase input, and the output is a variable-voltage and variable-frequency nine-phase output. A simple pulsewidthmodulation technique is developed for the proposed ac–ac converter named as a nonsquare three-to-nine-phase matrixconverter configuration. The developed modulation technique is based on the comparison of a high-frequency carrier signal with the duty ratios. Although the carrier-based scheme is widely employed for the control of back-to-back converters, it has recently been used for controlling a three-to-three-phase matrix converter. This concept is extended in this paper for controlling a threeto-nine-phase matrix converter. With the two techniques that are proposed, one outputs 0.75 of the input magnitude and the other outputs reach 0.762 of the input. This is the maximum value of the output voltage in the linear modulation range that can be achieved in this configuration of the matrix converter. The viability of the proposed control techniques is proved analytically through simulation and an experimental approach. [ABSTRACT FROM PUBLISHER]

In this paper, the diagnosis of soft faults in lossy electric transmission lines is studied through the inverse scattering approach, extending a recently reported study on lossless transmission lines. The considered soft faults are modeled as continuous spatial variations of distributed characteristic parameters of transmission lines. The diagnosis of such faults from reflection and transmission coefficients measured at the ends of a line can be formulated as an inverse problem. The relationship between this inverse problem and the inverse scattering theory has been studied by Jaulent in 1982 through transformations from the telegrapher's equations of transmission lines to Zakharov-Shabat equations. The present paper clarifies and completes the computation of the theoretic scattering data required by the inverse scattering transform from the practically measured engineering scattering data. The inverse scattering method is then applied to numerically simulated lossy transmission lines to confirm the feasibility of the studied approach to soft fault diagnosis. [ABSTRACT FROM AUTHOR]

This paper presents the evaluation of the performance, in terms of uncertainty, of a tool designed to estimate the main parameters of a model of a photovoltaic panel (PVP) under real and/or simulated working conditions. The presented tool permits the characterization of the panel, and it is useful to predict its behavior in whatever working condition; in this way, it is possible to compare the actual and expected performance to prevent any decrease in the output power, so permitting the replacement of the monitored module before it goes out of order or its efficiency falls under a given threshold. The well-known two-diode model is used to estimate the parameters of the electrical equivalent circuit of the PVP and to simulate the I–V and P–V characteristic curves in any given environmental condition of irradiance and/or temperature. The model and the estimation algorithm are implemented with MATLAB functions, whereas data acquisition and result presentation are managed by a LabVIEW graphics user interface. The presented tool has been validated against an experimentally characterized PVP. The environmental parameters of the model such as irradiance and temperature have been set (with their respective uncertainties) during simulations or directly measured during the outdoor tests, whereas the others parameters have been evaluated using a best-fit algorithm on the measured data. The estimation is based on the minimization of a new objective function and on a modified expression of the model resistances, which differ from those mentioned in the available literature. After a review of the state of the art, this paper provides the description of the estimation technique and its validation by means of simulations and experiments. Some results are also provided to illustrate the performance of the proposed test method. [ABSTRACT FROM AUTHOR]

This paper presents a new solution method that combines state-space and nodal analysis for the simulation of electrical systems. The presented flexible clustering of state-space-described electrical subsystems into a nodal method offers several advantages for the efficient solution of switched networks, nonlinear functions, and for interfacing with nodal model equations. This paper extends the concept of discrete companion branch equivalent of the nodal approach to state-space described systems and enables natural coupling between them. The presented solution method is simultaneous and enables benefitting from the advantages of two different modeling approaches normally exclusive from one another. [ABSTRACT FROM AUTHOR]

This paper studies microgrids where loads are supplied by parallel-connected inverters controlled by decentralized active power/voltage frequency and reactive power-/voltage-magnitude droop control laws. A paralleled ac system, such as a multiinverter microgrid, is susceptible to circulating currents due to differences in voltage magnitude, frequency, phase angle, or dc offset. Circulating currents due to differences in voltage magnitude and dc offset have been known issues reported in literature. However, an in-depth analysis of the problem is required to ascertain the deviation of the system-operating condition from the desired condition. This paper provides a mathematical model that predicts the effect of voltage-magnitude offsets on reactive power sharing between inverters. Simulation and experimental results verify the accuracy of the analytical results obtained from the mathematical model. We examine the effect of dc-circulating currents and propose a simple capacitor emulation control law implemented in software to eliminate dc-circulating currents. This solution is a possible alternative for hardware implementation to eliminate dc-circulating currents. The effectiveness of the capacitor emulation control law has been verified through experimental results. [ABSTRACT FROM PUBLISHER]

This paper presents an online procedure for the automatic search of the maximum-torque-per-ampere operating region for a synchronous reluctance motor. The algorithm is based on a signal-injection method with a random-based perturbation pattern applied to a common direct-torque-controlled drive. Among motor parameters, only the stator resistance is required to perform the automatic procedure. Simulations and experimental results are presented in the paper, demonstrating the benefits of the proposed algorithm. The solution is easily extended to any ac drive. [ABSTRACT FROM PUBLISHER]

3-D hybrid finite-element (FE) boundary integral equation (BIE) formulations are widely used because of their ability to simulate large inhomogeneous structures in both open and bounded simulation domains by applying each method where it is the most efficient. However, some formulations suffer from breakdown frequencies at which the solution is not uniquely defined and errors are introduced due to internal resonances. In this paper, we investigate the occurrence of spurious solutions resulting from these resonances by using the concept of the Poincaré–Steklov or Dirichlet-to-Neumann operator, which provides a relation between the tangential electric field and the electric current on the boundary of a domain. By identifying this operator in both the FE and BIE method, several new properties of internal resonances in 3-D hybrid FE-BIE formulations are easily derived. Several conformal and nonconformal formulations are studied and the theory is then applied to a scattering problem. [ABSTRACT FROM AUTHOR]

Modular multilevel converters (MMC) are considered a top converter alternative for voltage-source converter (VSC) high-voltage, direct current (HVDC) applications. Main circuit design and converter performance evaluation are always important issues to consider before installing a VSC-HVDC system. Investigation into a steady-state analysis method for an MMC-based VSC-HVDC system is necessary. This paper finds a circular interaction among the electrical quantities in an MMC. Through this circular interaction, a key equation can be established to solve the unknown circulating current. A new steady-state model is developed to simply and accurately describe the explicit analytical expressions for various voltage and current quantities in an MMC. The accuracy of the expressions is improved by the consideration of the circulating current when deriving all the analytical expressions. The model's simplicity is demonstrated by having only one key equation to solve. Based on the analytical expressions for the arm voltages, the equivalent circuits for MMC are proposed to improve the current understanding of the operation of MMC. The feasibility and accuracy of the proposed method are verified by comparing its results with the simulation and experimental results. [ABSTRACT FROM AUTHOR]

Analytical derivation of scattered field from rough ocean surface can be accomplished by a two-step analysis involving ocean surface modeling and scattered-field calculation. In the first step, the simplest linear model is constructed by assuming a rough ocean state as composition of infinite number of linear waves with identical crests and troughs. Unfortunately, regardless of ocean circumstances, ocean surface waves always exceed the linear range and yield a typical nonlinear asymmetric waveform with sharper peaks and shallow troughs. In this paper, by using curve-fit method and the concept of fractal geometry, we propose a new fractal function named fractional Weierstrass function which may be viewed as a generalization of classical Weierstrass function, and then, a fractional Weierstrass model for ocean surface is proposed by combining the fractional Weierstrass function with the Pierson–Moskowitz spectrum. An important advantage of our proposed model is the ability to represent nonlinearity with different degrees of ocean surface depending on a new parameter c. Some simulations demonstrate ratio c as an invariant scale of fractal ocean surface. The second step is strongly related to the surface modeling result of the first step. Within Kirchhoff approximation, an analytical derivation of scattered field in a closed form is obtained from our proposed fractional Weierstrass model surface. Moreover, some related discussions, including the normalization constant of the model, the correlation length, the scattered-field structure, and the influence of fractal and electromagnetic parameters over scattered field, are given. Finally, edge effects caused by the truncation of scatterer surface are also analyzed in detail. [ABSTRACT FROM PUBLISHER]

Periodic circuits driven by multitone signals are still a challenging simulation problem despite several numerical methods being presented in the literature. In this paper, a mixed time–frequency method for the solution of this problem and suitable for both autonomous and nonautonomous circuits is presented. The method is based on an extension of the envelope following method, which allows us to reduce the number of unknowns involved in the steady-state problem with respect to previous mixed time–frequency approaches, and a suitable reformulation of the periodicity constraint that allows us to obtain a significant acceleration in the determination of the solution by reducing the time interval along which the envelope analysis must be performed. The method is first presented for nonautonomous circuits and then extended to autonomous ones. [ABSTRACT FROM AUTHOR]

In this paper, issues related to parameter identification and high-performance control of the drive system with an elastic joint are discussed. After a brief introduction, the mathematical model of the drive and the proposed high-performance control structure are presented. The effect of the location of closed-loop poles and cancellation of zeros of the structure is examined. Then, the mathematical models of the Kalman filters used in this study are presented, and the results of the identification procedure are described. The effectiveness of the proposed structure has been examined under simulation and experimental study. [ABSTRACT FROM PUBLISHER]

In this paper, we develop and validate a method to identify computationally efficient site- and patient-specific models of ultrasound thermal therapies from MR thermal images. The models of the specific absorption rate of the transduced energy and the temperature response of the therapy target are identified in the reduced basis of proper orthogonal decomposition of thermal images, acquired in response to a mild thermal test excitation. The method permits dynamic reidentification of the treatment models during the therapy by recursively utilizing newly acquired images. Such adaptation is particularly important during high-temperature therapies, which are known to substantially and rapidly change tissue properties and blood perfusion. The developed theory was validated for the case of focused ultrasound heating of a tissue phantom. The experimental and computational results indicate that the developed approach produces accurate low-dimensional treatment models despite temporal and spatial noises in MR images and slow image acquisition rate. [ABSTRACT FROM AUTHOR]

This paper presents for the first time the transient simulation of the 3-D \TE34, 19 mode converter with surface deformation. The simulation results were obtained by solving the Maxwell equations directly on a 3-D domain with a discontinuous Galerkin method. The presented full-wave simulation was possible only through the use of an advanced highly scalable numerical method operating on a large-scale high-performance computing system. Moreover, the properties of the Maxwell solver with respect to accuracy and computation time are discussed for the application to a smooth-wall \TE34, 19 waveguide where an analytical solution is available. [ABSTRACT FROM PUBLISHER]

In this paper, we consider the friction compensation problem for a class of mechanical systems. The friction behavior is described by a nonlinear dynamical model. Since it is difficult to know the nonlinear parts in the frictional model accurately, two neural networks (NNs) are employed in the proposed intelligent controller. Due to the learning capability of the NNs, the designed NN controller can compensate the effects of the nonlinear friction. Stability of the thus proposed learning control system is guaranteed by a rigid proof. Simulation and experimental results are provided to verify the effectiveness of the proposed intelligent scheme. [ABSTRACT FROM PUBLISHER]

Total variation (TV) has been used as a popular and effective image prior model in regularization-based image processing fields, such as denoising, deblurring, super-resolution (SR), and others, because of its ability to preserve edges. However, as the TV model favors a piecewise constant solution, the processing results in the flat regions of the image being poor, and it cannot automatically balance the processing strength between different spatial property regions in the image. In this paper, we propose a spatially weighted TV image SR algorithm, in which the spatial information distributed in different image regions is added to constrain the SR process. A newly proposed and effective spatial information indicator called difference curvature is used to identify the spatial property of each pixel, and a weighted parameter determined by the difference curvature information is added to constrain the regularization strength of the TV regularization at each pixel. Meanwhile, a majorization–minimization algorithm is used to optimize the proposed spatially weighted TV SR model. Finally, a significant amount of simulated and real data experimental results show that the proposed spatially weighted TV SR algorithm not only efficiently reduces the “artifacts” produced with a TV model in fat regions of the image, but also preserves the edge information, and the reconstruction results are less sensitive to the regularization parameters than the TV model, because of the consideration of the spatial information constraint. [ABSTRACT FROM AUTHOR]

Motor unit potential trains (MUPTs) extracted via electromyographic (EMG) signal decomposition can aid in the diagnosis of neuromuscular disorders and the study of the neural control of movement, but only if they are valid. In this paper, support vector machine (SVM)-based supervised classifiers are proposed to estimate the validity of extracted MUPTs. The classifiers use either the MU firing pattern or the MUP shape consistency of an MUPT, or both, to estimate its validity. The developed classifiers estimate the class label of an MUPT (i.e., valid/invalid) and a degree of support for the decision being made. A single SVM that estimates the validity of a given MUPT using extracted MU firing pattern and MUP shape features was investigated. In addition, the effectiveness of multiclassifier techniques which estimate the overall validity of a train by fusing the MU firing pattern and MUP shape validity of a given MUPT, determined separately by two distinct SVMs, was also investigated. Training based only on simulated data showed robust classification performance of the several multiclassifier methods when tested using both simulated and real test data. Of the methods studied, the multiclassifier constructed using trainable logistic regression to aggregate base classifier outputs had the best performance. Assuming 12.7% of extracted MUPTs are on average invalid, the estimated accuracy for this method in correctly categorizing MUPTs extracted during decomposition was 99.4% and 98.8% for simulated and real data, respectively. [ABSTRACT FROM PUBLISHER]

This paper treats the problems of the particle-in-cell (PIC) models at higher pressures. We discuss the influence of the time discretization on the results of a model of a highly collisional plasma using a simplified analytical model. A new algorithm is proposed that calculates the collisions independently of the simulation time step, thus eliminating the errors introduced by the time discretization. The benchmarks at the pressure of the neutral gas of 665 Pa show that the presented algorithm is approximately seven times faster than a classical PIC model with the same accuracy. [ABSTRACT FROM AUTHOR]

This paper deals with the identification of the multivariate fractional Brownian motion, a recently developed extension of the fractional Brownian motion to the multivariate case. This process is a p-multivariate self-similar Gaussian process parameterized by p different Hurst exponents Hi, p scaling coefficients \sigmai (of each component) and also by p(p-1) coefficients \rhoij,\etaij (for i,j=1,\ldots ,p with j>i) allowing two components to be more or less strongly correlated and allowing the process to be time reversible or not. We investigate the use of discrete filtering techniques to estimate jointly or separately the different parameters and prove the efficiency of the methodology with a simulation study and the derivation of asymptotic results. [ABSTRACT FROM AUTHOR]

Heat assisted magnetic recording (HAMR) is a promising hard disk drive technology to reach 4 Tb/in^2 storage densities. However, HAMR introduces significant thermal considerations that must be accounted for in air bearing simulations; the laser spot on the recording bit and heat dissipated into the slider by the laser delivery system result in boundary wall temperatures that are several hundred degrees Celsius above ambient. Since the air bearing film between the slider and disk is non-isothermal, the local air properties should be used in the lubrication equation that governs the pressure generation. A molecular gas lubrication equation for the air bearing that accounts for large temperature variation along the film was previously proposed by Fukui and Kaneko, but it has yet to be applied to a HAMR hard disk drive. This paper explains the generalized lubrication equation and also implements it into a realistic 2D simulation using a production slider with approximate HAMR conditions. The minimum flying height increases substantially, while the pitch and roll are inappreciably affected. Thermal creep flow is negligible compared with Poiseuille and Couette flows, and it can be omitted from consideration. The sensitivity of the read/write transducer would be affected by the large increase in minimum flying height; therefore, the thermal flying height control design process must consider these variations due to thermal variations in the air bearing. [ABSTRACT FROM AUTHOR]

Microwave lenses such as the Bootlace/Rotman lenses are designed by placing physical ports of lens input on the theoretical phase centers. These phase center positions are calculated using geometrical optic method under the assumptions of perfect cylindrical waves and true time delay. A real physical lens does not satisfy these conditions due to different port implementation approaches and mutual coupling effects. Full wave investigations and measurements have indicated strong variation at both phase and amplitude couplings between the input and output ports. Efficient theoretical models predicting both phase and amplitude performances are still in great demand to perform advanced lens optimization. The full wave simulation demonstrates accurate results. However, it is not convenient in optimization iterations due to its high computational cost and sophisticated programming process. Based on a ray tracing concept recently explored by the authors, this paper extends its design and formulate a suitable approach for general lens simulation. A microwave lens is systematically treated by hybrid of a flexible tapered port model and multiple-ray-path coupling approach. This method leads to designing the minimum return loss tapered port and fast lens simulation of reasonable accuracy. The predicted results of amplitude, phase couplings, array factors are validated by both full wave simulation and measurement. The comparison shows that the proposed method is fast, accurate and sufficient to predict various microwave lens parameters. This concept can be extended to designing stripline and waveguide lenses as well. [ABSTRACT FROM AUTHOR]

A primary-side controlled universal-line flyback converter is widely used for its low-cost and low standby power advantages; however, conventional overpower protection schemes that feature primary-side control often experience inaccurate protection. In this paper, a novel scheme is presented, which achieves a very significant improvement in overpower accuracy while simultaneously meets a critical goal of adding no extra pin compared to conventional schemes when implemented in an IC. Experimental and simulation results verified the proposed strategy, and the scheme was implemented successfully in an IC. [ABSTRACT FROM AUTHOR]

In this paper, a numerical simulation was carried out to analyze the effect of diffusion charging on collection efficiency of a wire-plate electrostatic precipitator (ESP). The gas flow field, the electric field, and the particle field with diffusion charging considered were included in the numerical model, which was implemented by using the commercial FLUENT software. Collection efficiency was calculated by using the Deutsch–Anderson equation, in which the parameters were provided from the numerical solutions. The simulated results indicate that the effect of diffusion charging on the wire-plate ESP particle collection increases with the decreasing particle diameter, as well as applied potential, particularly for PM10. Moreover, with the increasing applied potential, collection efficiency of PM10 is obviously improved, and the effect extent first increases and then decreases with particle size increasing, but also, the size range of particle, which is significantly affected by the diffusion charging, becomes smaller. As gas velocity becomes higher, the effect of diffusion charging on grade efficiency also becomes more obvious, and the affected range of particle size gets much larger, however, at the price of grade efficiency decreasing. Using collection efficiency as reference variable of judgment, instead of particle charge, may lead to a more accurate estimation of the aforementioned size range, which can provide a great help in the further analysis of fine particle collection. [ABSTRACT FROM PUBLISHER]

In this paper, a new bridgeless single-ended primary inductance converter power-factor-correction rectifier is introduced. The proposed circuit provides lower conduction losses with reduced components simultaneously. In conventional PFC converters (continuous-conduction-mode boost converter), a voltage loop and a current loop are required for PFC. In the proposed converter, the control circuit is simplified, and no current loop is required while the converter operates in discontinuous conduction mode. Theoretical analysis and simulation results are provided to explain circuit operation. A prototype of the proposed converter is realized, and the results are presented. The measured efficiency shows 1% improvement in comparison to conventional SEPIC rectifier. [ABSTRACT FROM AUTHOR]

To simulate semiconductor devices and circuits working at high frequencies or under a large signal input and to better understand their physical effects, a physically based simulation method is proposed in this paper. It utilizes a physical-model-based field simulation to analyze the semiconductor devices in a circuit and incorporates the field simulation into an equivalent-model-based circuit simulation to simulate the circuit. For the field simulation, a genetic-algorithm-based curve-fitting approach is proposed to extract the parameters of the semiconductor devices’ physical models. The proposed method is employed for the analysis of a few circuits containing a commercial p-i-n diode with model number mot_bal99lt1. The feasibility and accuracy of the proposed method are validated through a comparison of its simulation results with the measurement data, and good agreement is observed. The other merits of the proposed method are also illustrated, including its ability to provide useful physical mechanisms for the better understanding of the behavior of the p-i-n diode under various working conditions. [ABSTRACT FROM PUBLISHER]

Photovoltaic (PV) system performance is influenced by several factors, including irradiance, temperature, shading, degradation, mismatch losses, soiling, etc. Shading of a PV array, in particular, either complete or partial, can have a significant impact on its power output and energy yield, depending on array configuration, shading pattern, and the bypass diodes incorporated in the PV modules. In this paper, the effect of partial shading on multicrystalline silicon (mc-Si) PV modules is investigated. A PV module simulation model implemented in P-Spice is first employed to quantify the effect of partial shading on the I–V curve and the maximum power point (MPP) voltage and power. Then, generalized formulae are derived, which permit accurate enough evaluation of MPP voltage and power of mc-Si PV modules, without the need to resort to detailed modeling and simulation. The equations derived are validated via experimental results. [ABSTRACT FROM PUBLISHER]

In this paper, a modification of the Sugeno integral with interval type-2 fuzzy logic is proposed. The modification includes changing the original equations of the Sugeno Measures and the Sugeno integral that were initially proposed for type-1 fuzzy logic. The proposed modification enables calculation of the interval type-2 Sugeno integral for combining multiple source of information with a higher degree of uncertainty than with the traditional type-1 Sugeno integral. The advantages of the interval type-2 Sugeno integral are illustrated by reporting improved recognition rates in benchmark face databases. This new concept could also be a useful tool in other areas of applications. Also, the improvement provided by the type-2 integral is verified to be statistically significant in the recognition results for complex face databases (like the FERET database) when compared with the type-1 Sugeno integral. The proposed Sugeno integral is used to combine the modules' outputs of a modular neural network for face recognition. Simulation results show that the interval type-2 Sugeno integral is able to improve the recognition rate for the benchmark face databases. Recognition results are better or comparable to results produced by alternative approaches present in the literature reported for the same benchmark problems. [ABSTRACT FROM PUBLISHER]

This paper proposes a new yield model for integrated circuits using a spatial point process. The defect density variation by location on a wafer is modeled by a spatial nonhomogeneous Poisson process. The intensity function of the yield model describes the defect pattern on wafers. As a result, the model differs from the existing compound Poisson yield models in its capability to describe the spatial defect distribution. Using model-based clustering, the defect clusters from assignable causes, which contain the information about the variations of manufacturing processes, can be classified from others. The proposed model considers the defect density variation among wafers and the impact of defect size on the probability of a defect causing the circuit failure. The performance of the new yield model is verified using simulated data and real data. Simulation results show that the new yield model performs better than a compound Poisson yield model. [ABSTRACT FROM PUBLISHER]

In this paper a model selection algorithm for a nonlinear system identification method is proposed to study functional magnetic resonance imaging (fMRI) effective connectivity. Unlike most other methods, this method does not need a pre-defined structure/model for effective connectivity analysis. Instead, it relies on selecting significant nonlinear or linear covariates for the differential equations to describe the mapping relationship between brain output (fMRI response) and input (experiment design). These covariates, as well as their coefficients, are estimated based on a least angle regression (LARS) method. In the implementation of the LARS method, Akaike's information criterion corrected (AICc) algorithm and the leave-one-out (LOO) cross-validation method were employed and compared for model selection. Simulation comparison between the dynamic causal model (DCM), nonlinear identification method, and model selection method for modelling the single-input-single-output (SISO) and multiple-input multiple-output (MIMO) systems were conducted. Results show that the LARS model selection method is faster than DCM and achieves a compact and economic nonlinear model simultaneously. To verify the efficacy of the proposed approach, an analysis of the dorsal and ventral visual pathway networks was carried out based on three real datasets. The results show that LARS can be used for model selection in an fMRI effective connectivity study with phase-encoded, standard block, and random block designs. It is also shown that the LOO cross-validation method for nonlinear model selection has less residual sum squares than the AICc algorithm for the study. [ABSTRACT FROM AUTHOR]

Although the recently proposed single-implicit-equation-based input voltage equations (IVEs) for the independent double-gate (IDG) MOSFET promise faster computation time than the earlier proposed coupled-equations-based IVEs, it is not clear how those equations could be solved inside a circuit simulator as the conventional Newton–Raphson (NR)-based root finding method will not always converge due to the presence of discontinuity at the G-zero point (GZP) and nonremovable singularities in the trigonometric IVE. In this paper, we propose a unique algorithm to solve those IVEs, which combines the Ridders algorithm with the NR-based technique in order to provide assured convergence for any bias conditions. Studying the IDG MOSFET operation carefully, we apply an optimized initial guess to the NR component and a minimized solution space to the Ridders component in order to achieve rapid convergence, which is very important for circuit simulation. To reduce the computation budget further, we propose a new closed-form solution of the IVEs in the near vicinity of the GZP. The proposed algorithm is tested with different device parameters in the extended range of bias conditions and successfully implemented in a commercial circuit simulator through its Verilog-A interface. [ABSTRACT FROM PUBLISHER]

Electronically controlled air suspension systems have been used in vehicles to improve ride comfort and handling safety by adjusting vehicle height. This paper proposes a new nonlinear controller to adjust the height of the vehicle sprung mass (height control) and to regulate the roll and pitch angles of the vehicle body (leveling control) by an air suspension system. A sliding mode control algorithm is designed to improve the tracking accuracy of the control and to overcome nonlinearities and uncertainties in the air suspension system. A mathematical model of the air suspension system is formulated in a nonlinear affine form to describe the dynamic behavior of the system and to derive the control algorithm. The sliding mode observer is also designed to estimate the pressures inside four air springs. The effectiveness and performance of the proposed control algorithm are verified by simulations and actual vehicle tests. [ABSTRACT FROM PUBLISHER]

This correspondence paper presents an algorithm in which the independent components of link lengths are used as a medium to analyze the forward kinematics of a six-degree-of-freedom Stewart platform. The link lengths are firstly transformed into independent components through independent component analysis. Then, the value of positional variables is computed by using the Nelder–Mead algorithm by taking advantage of the relationships between the independent components and the positional variables. Simulations have been conducted to test the proposed algorithm. The experimental results show that the proposed algorithm can achieve a better performance than the other published algorithms. [ABSTRACT FROM PUBLISHER]

The calculation of magnetic fields in devices with a nonuniform distribution of magnetomotive force (MMF) and with nonlinear magnetic components has proven problematic within electromagnetic systems. This is caused by insufficiently precise determination of the dependence of magnetic induction B, on magnetic field H. This paper develops a method for analytically calculating the variation of magnetic fields H, in magnetic circuits by introducing a specific expression into to the Ampere's circuital law formula to take into account nonuniform MMF. The new formula uses a conformal mapping procedure which allows calculation of the magnetic field at different displacements from the field generating coil. The analytic approximation proposed is developed for the specific problem of a closed circuit magnetic core. This analytic model gives accurate results faster than can be achieved in FEM software. [ABSTRACT FROM PUBLISHER]

In this paper, a real-time walking trajectory generation method with three-mass models at constant body height for 3-D biped robots is extended for a diagonal walking. By realization of the diagonal walking, the availability is improved. The modeling of this method is more precise than that of conventional real-time walking trajectory generation methods. In this method, the zero-moment point equation of a body is derived, and an analytic solution of a body trajectory at a constant body height in a single support phase is obtained. Because the analytic solution is used, real-time trajectory generation can be realized. In addition, this method has advantages of the body trajectory at the constant body height. The validities are confirmed from simulations of the 2-D walking and an experiment of the 3-D diagonal walking. [ABSTRACT FROM AUTHOR]

In this paper, a theoretical model, taking into account the phonon-assisted excited-state absorption process \left(^3H5\rightarrow{^{3H4}}\right), has been constructed to explain the self-pulsing (SP) phenomenon in the Tm^3+-doped fiber lasers. Both numerical simulation and experimental investigation on the SP characteristics of \sim2\-\mum~Tm^3+-doped fiber lasers have been carried out. The numerical simulation shows agreement with the experimental results. Furthermore, the impacts of output coupling, pump intensity, and Tm^3+-ion doping concentration on the SP characteristics of the Tm^3+-doped fiber lasers have been studied explicitly, and optimization of the SP features has been discussed. In addition, the potential applications of SP in fiber lasers or solid-state lasers have also been proposed. [ABSTRACT FROM PUBLISHER]

This paper analyzes the sensorless control of ac machines based on the zero-sequence voltage generated by the injection of a carrier-signal voltage. The analysis focuses on rotor position estimation (tracking of rotor-position-dependent saliencies), but the methods discussed apply equally to flux position estimation (tracking of flux-dependent saliencies). Analyses of relevant aspects like selection of the carrier-signal frequency, measurement of the zero-sequence carrier-signal voltage, and decoupling of saturation-induced saliencies are included. [ABSTRACT FROM AUTHOR]

Turbine flow meters can be represented by a simple first-order nonlinear system adequately with two instrument constants: the meter scale-factor and the dynamic factor. Conventionally only the scale-factor is determined during calibration. This paper presents a method to ascertain the dynamic factor, so that the dynamic response of the flow meter is also taken into account. [ABSTRACT FROM AUTHOR]

This paper presents a numerical solution of electric field that is modified by the presence of volume charge within the region of interest. The effect of the presence of volume charge within the region of interest has been studied for both uniform and nonuniform fields. Charge simulation method coupled with the method of characteristics line is used to provide the numerical solution for the charge modified field. These two techniques are applied iteratively to converge to a self-consistent field model between the two surfaces in xerographic process. Detailed results are presented in the paper to show how the presence of toner as volume charges affects the field distribution when they are present within the field of interest. [ABSTRACT FROM AUTHOR]

This paper studies the performance of Non-persistent CSMA/CA protocols with Exponential Backoff scheduling algorithms. A multi-queue single-server system is proposed to model multiple access networks. The input buffer of each access node is modeled as a Geo/G/1 queue, and the service time distribution of head-of-line packets is derived from the Markov chain of underlying scheduling algorithm. The main results include the complete analysis of the throughput and delay distribution, from which we derived the characteristic equation of network throughput and obtained stable regions with respect to the throughput and bounded mean delay of the Exponential Backoff scheme. We show that the stable throughput region of Exponential Backoff can be obtained even for an infinite population. Since the variance of service time of Exponential Backoff can be unbounded due to the capture effect; thus, its bounded delay region is only a sub-set of its stable throughput region, and the maximum achievable throughput of the network within this region is slightly smaller than the absolute maximum throughput. Analytical results presented in this paper are all verified by simulation. [ABSTRACT FROM PUBLISHER]

A novel formulation has been proposed in this paper for the calculation of asymmetric electric field including surface resistance using Surface Charge Simulation Method (SCSM). The formulation has been tested for a partly conducting dielectric sphere placed in uniform sinusoidal field and also for an axi-symmetric post type insulator. Finally the method has been applied for computing the effects of resistivity on the field around the solid components of high voltage metal enclosed equipments having asymmetric geometries. The effects of surface resistivity on the field distribution for different examples have been reported in details. The results are in good agreement with those reported in previous literature for axi-symmetric insulator. For asymmetric spacers the results highlight the locations of field enhancement, which is practically significant for compact gas insulated systems. [ABSTRACT FROM PUBLISHER]

This review paper introduces fundamental knowledge about and presents recent developments in modeling and simulation of ion transport and electrohydrodynamic flow in dielectric liquids. Starting with the formulation of the governing equations, we introduce background ideas as well as the related modeling of ion dissociation, recombination, injection, and discharge, which play key roles in the charge creation and transport problem. Numerical methods and solutions are then presented for the onedimensional problem over the domain between a pair of parallel electrodes. In particular, we show how the electrical properties of a nonpolar liquid, m-xylene, can be derived from the matching of the numerical solutions with Novotny's experimental data. Two asymptotic solution methods, one for the overlap-layer and the other for the thin-layer regimes, are then presented; in particular, we show a remarkably high accuracy for the solutions. The current-voltage relation with ion dissociation and recombination is shown to be completely different from that without them. A historical review of the modeling and simulation of ion transport and electrohydrodynamic flow is finally touched upon. [ABSTRACT FROM PUBLISHER]

High frequency current transformers (HFCT) are widely used in partial discharge field and laboratory tests. Using these devices as sensors in partial discharge cable tests brings some advantages, namely: high degree of insulation, relatively good sensibility and the possibility of broadband measures. This paper analyzes the fundamentals of HFCTs measurements from the point of view of charge evaluation. Three different procedures for charge evaluation and the associated uncertainty are presented for partial discharge measurements in cables by means of HFCTs. Experimental and simulation data are presented and the associated uncertainty is calculated. [ABSTRACT FROM AUTHOR]

High-power ultrasound has many diverse uses in process applications in industries ranging from food to pharmaceutical. Because cavitation is frequently a desirable effect within many high-power, low-frequency systems, these systems are commonly expected to feature highly nonlinear acoustic propagation because of the high input levels employed. This generation of harmonics significantly alters the field profile compared with that of a linear system, making accurate field modeling difficult. However, when the short propagation distances involved are considered, it is not unreasonable to assume that these systems may remain largely linear until the onset of cavitation, in terms of classical acoustic propagation. The purpose of this paper is to investigate the possible nonlinear effects within such systems before the onset of cavitation. A theoretical description of nonlinear propagation will be presented and the merits of common analytical models will be discussed. Following this, a numerical model of nonlinearity will be outlined and the advantages it presents for representing nonlinear effects in bounded fields will be discussed. Next, the driving equipment and transducers will be evaluated for linearity to disengage any effects from those formed in the transmission load. Finally, the linearity of the system will be measured using an acoustic hydrophone and compared with finite element analysis to confirm that nonlinear effects are not prevalent in such systems at the onset of cavitation. [ABSTRACT FROM PUBLISHER]