An efficient piecewise‐linear DC analysis method for general non‐linear circuits

The convergence problems of conventional DC analysis can be partly avoided by using piecewise‐linear analysis. This paper proposes a piecewise‐linear DC analysis method that can efficiently handle arbitrary couplings between non‐linear circuit elements. Piecewise‐linear modelling of the non‐linear circuit elements is automatically performed during simulation, using simplicial subdivisions. The number of linear regions, and thereby iterations, is considerably reduced by combining the common parts of separate simplicial subdivisions. Due to these reasons and since the method is formulated with the commonly used modified nodal approach, it has been possible to implement the method in the general‐purpose circuit simulator APLAC. The correct operation of the method is demonstrated with three examples. Copyright © 1999 John Wiley & Sons, Ltd.     

On the terminal region of model predictive control for non‐linear systems with input/state constraints

This paper addresses the terminal region of model‐based predictive control (MPC) for non‐linear systems with control input and state constraints. Based on a stability condition of non‐linear MPC, a method to determine the terminal weighting term in the performance index and the terminal stabilizing control law to enlarge the terminal region and thus the domain of attraction of the non‐linear MPC is proposed. An LMI based optimization approach is developed to choose the terminal weighting item and fictitious terminal stabilizing control law so as to enlarge the terminal region of the non‐linear MPC method. The proposed method is illustrated by a numerical example and compares favourably with existing results. Copyright © 2003 John Wiley & Sons, Ltd.     

Generalized maximum correntropy detector for non‐Gaussian environments

This paper addresses the problem of multiple‐hypothesis detection. In many applications, assuming the Gaussian distribution for undesirable disturbances does not yield a sufficient model. On the other hand, under the non‐Gaussian noise/interference assumption, the optimal detector will be impractically complex. Therewith, inspired by the optimal maximum likelihood detector, a suboptimal detector is designed. In particular, a novel detector based on the generalized correntropy, which adopts the generalized Gaussian density function as the kernel, is proposed. Simulations demonstrate that, in non‐Gaussian noise models, the generalized correntropy detector significantly outperforms other commonly used detectors. The efficient and robust performance of the proposed detection method is illustrated in both light‐tailed and heavy‐tailed noise distributions.     

Updating stochastic model coefficients for prediction of arc furnace reactive power

The time varying nature of electric arc furnace (EAF) gives rise to voltage fluctuations which produce the effect known as flicker. The ability of static VAr compensator (SVC) in flicker reduction is limited by delays in thyristor ignition. To improve SVC performance in flicker compensation, EAF reactive power can be predicted for a half-cycle ahead, by using appropriate autoregressive moving average (ARMA) models. This paper uses huge field data collected from ac arc furnaces, and demonstrates that the EAF reactive power models coefficients are different from one data record to another and do not follow any specific law. Therefore, it is necessary to update the model coefficients for prediction purposes. For this purpose, two major adaptation algorithms, the least mean square (LMS) and recursive least square (RLS) are used to determine online the prediction relationship coefficients. By applying the methods to the data records and using some indices such as newly defined indices based on concepts of flicker frequencies and power spectral density, the transient and steady state performances of the methods are studied in EAF reactive power prediction. A simulation example on the application of the predictive models in a SVC control system is presented.     

A new current control method for energy‐efficient/wide‐speed‐range drive of permanent magnet synchronous motor

This paper proposes a new current control method for energy‐efficient and/or wide‐speed‐range drive of salient‐pole permanent magnet synchronous motors. The proposed method is distinguished from conventional ones by the following features. (1) The original command is a signed current norm. (2) The exact d‐axis and q‐axis current commands that perform energy‐efficient and/or wide‐speed‐range drive are analytically and simply determined from the singed current norm command. (3) For speed control mode, the system turns out to be nonlinear, but its stability can be guaranteed based on Popov's stability theorem. (4) It can be applied for a mode similar to torque control. (5) Current limitation can be carried out accurately but very simply. Concrete analytical d‐axis and q‐axis current commands are presented, which satisfy exactly one of three optimum current control codes such as maximum torque, maximum power factor, and voltage limitation. A design method for PI speed controller that guarantees system stability is also presented. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 161(3): 66–77, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20305     

An efficient paradigm for wavelet‐based image processing using cellular neural networks

We propose a novel paradigm for cellular neural networks (CNNs), which enables the user to simultaneously calculate up to four subband images and to implement the integrated wavelet decomposition and a subsequent function into a single CNN. Two sets of experiments were designated to test the performance of the paradigm. In the first set of experiments, the effects of seven different wavelet filters and five feature extractors were studied in the extraction of critical features from the down‐sampled low‐low subband image using the paradigm. Among them, the combination of DB53 wavelet filter and the r=2 halftoning processor was determined to be most appropriate for low‐resolution applications. The second set of experiments demonstrated the capacity of the paradigm in the extraction of features from multi‐subband images. CNN edge detectors were embedded in a two‐subband digital wavelet transformation processor to extract the horizontal and vertical line features from the LH and HL subband images, respectively. A CNN logic OR operator proceeds to combine the results from the two subband line‐edge detectors. The proposed edge detector is capable of delineating more subtle details than using typical CNN edge detector alone, and is more robust in dealing with low‐contrast images than traditional edge detectors. The results demonstrate the proposed paradigm as a powerful and efficient scheme for image processing using CNN. Copyright © 2008 John Wiley & Sons, Ltd.     

一种改进的瞬时导数法计算阻抗方法

阻抗的精确测量有利于提高继电器动作速度和准确性。导数法是微机保护中最常用的一种算法之一。传统的导数法计算阻抗精度对滤波器滤高频能力和采样频率有较高的要求。无误差修正思想虽能克服该不足,然而实时性较差。为了提高导数法计算阻抗的精度和实时性,提出了一种改进的瞬时导数法计算阻抗方法。理论推理和仿真结果都证明了该方法所需的数据窗少,有利于降低运算精度对数字滤波器滤高频能力和采样频率的高度依赖,可以实时地计算阻抗。     

Multiscalet basis in Galerkin's method for solving three‐dimensional electromagnetic integral equations

Multiscalets in the multiwavelet family are used as the basis and testing functions in Galerkin's method. Since the multiscalets are orthogonal to their translations under the Sobolev inner product, the resulting Galerkin's method behaves like a collocation method but possesses the ability of derivative tracking for unknown functions in solving integral equations. The former makes the method simple in implementation and the latter allows to use coarse meshes in discretization. These robust features have been demonstrated in solving two‐dimensional (2D) electromagnetic (EM) problems, but have not been exploited in three‐dimensional (3D) scenarios. For 3D problems, the unknown functions in the integral equations are dependent on two coordinate variables. In order to preserve the use of coarse meshes for 3D cases, we realize the omnidirectional derivative tracking by tracking the directional derivatives along two orthogonal directions, or equivalently tracking the gradient. This process yields a nonsquare matrix equation and we use the least‐squares method (LSM) to solve it. Numerical examples show that the multiscalet‐based Galerkin's method is also robust in solving for 3D EM integral equations with a minor cost increase from LSM. Copyright © 2007 John Wiley & Sons, Ltd.     

Device‐partition method using equivalent circuit model in two‐dimensional device simulation

In order to accomplish two‐dimensional device simulation with a large number of nodes, in this paper we propose the device‐partition method (DPM) to resolve the problem that the memory size of the simulation environment is insufficient. The idea of DPM is that the device can be divided into several parts and a matrix solver only solves one part at a time. DPM uses the iteration method to simulate the device. By continuous iteration, an accurate solution can be obtained. Hence, we use DPM to demonstrate the simulations of the MOSFET and the CMOS inverter. The simulation results of DPM and the coupled method (CM) are nearly approximate and correspond with the theory. Hence, DPM is a suitable method to develop a powerful simulation environment. Copyright © 2005 John Wiley & Sons, Ltd.     

Transient analysis of coupled non‐uniform transmission line using finite element method

This paper presents a finite element time domain model for a numerical solution of a coupled non‐uniform transmission line problem. On the basis of the finite element method, a novel numerical procedure for the solution of a system of the non‐uniform multi‐conductor transmission line equations in the time domain is presented. The results obtained by the proposed method have been compared with the solution obtained using the finite difference time domain method, and an excellent correlation has been demonstrated. Copyright © 2014 John Wiley & Sons, Ltd.     

Identification of errors‐in‐variables systems: An asymptotic approach

This work studies the identification of errors‐in‐variables (EIV) systems. An asymptotic method (ASYM) is developed for the EIV system. Firstly, an auto regressive with exogeneous (ARX) model estimation method is proposed, which is consistent for EIV systems. Then the asymptotic variance expression of the estimated high‐order ARX model is derived, which forms the basis of the ASYM method. In parameter estimation, the ASYM starts with a high‐order ARX model estimation followed by a frequency domain weighted model reduction. The obtained model is consistent, and its efficiency needs to be investigated. Besides parameter estimation, a criterion for model order selection is proposed, which is based on frequency domain considerations, and the frequency domain error bound is established that can be used for model validation. Simulations and comparisons with other methods are used to illustrate the performance of the method.     

An efficient class association rule‐pruning method for unified intrusion detection system using genetic algorithm

Genetic network programming (GNP)‐based class association rule mining has been demonstrated to be efficient for misuse and anomaly detection. However, misuse detection is weak in detecting brand new attacks, while anomaly detection has a defect of high positive false rate. In this paper, a unified detection method is proposed to integrate misuse detection and anomaly detection to overcome their disadvantages. In addition, GNP‐based class association rule mining method extracts an overwhelming number of rules which contain much redundant and irrelevant information. Therefore, in this paper, an efficient class association rule‐pruning method is proposed based on matching degree and genetic algorithm (GA). In the first stage, a matching degree‐based method is applied to preprune the rules in order to improve the efficiency of the GA. In the second stage, the GA is implemented to pick up the effective rules among the rules remaining in the first stage. Simulations on KDDCup99 show the high performance of the proposed method. © 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

A generalized CAD model for the full‐wave modeling of Coplanar striplines discontinuities

In this work, the coplanar stripline (CPS) and its discontinuities: open‐end, short‐end, gaps and resonator have been modeled. New integral equations for the electrical field components are formulated, in the spectral domain, using an exact dyadic Green's function, applied to the CPS structure. The use of this form of Green's function allows the consideration of the effects of the dielectric losses, the surface wave excitation and the space wave radiation on the propagation characteristics of the CPS and its discontinuities. The resulting integral equation has been solved using the two‐dimensional Galerkin's technique. The resolution of the resulting matrix equation gives the scattering parameters of the studied structures. The obtained results are commented and compared with those of other approaches and measurements. Copyright © 2011 John Wiley & Sons, Ltd.     

A systematic method for the development of a three‐phase transformer non‐linear model

In this work, a novel three‐phase transformer non‐linear model is developed. The proposed model takes into account the magnetic core topology and the windings connections. The non‐linear characteristic curve of the core material is introduced by its magnetization curve or by its hysteresis loop using the mathematical hysteresis model proposed by Tellinen or the macroscopic hysteresis model proposed by Jiles–Atherton. The eddy currents effects are included through non‐linear resistors using Bertotti's work. The proposed model presents several advantages. An incremental linear circuit, having the same topology with the magnetic circuit of the core, is used in order to directly write the differential equations of the magnetic part of the transformer. The matrix L _d that describes the coupling between the windings of the transformer is systematically derived. The electrical equations of the transformer can be easily written for any possible connection of the primary and secondary windings using the unconnected windings equations and transformation matrices. The proposed methods for the calculation of the coupling between the windings, the representation of the eddy currents and the inclusion of the core material characteristic curve can be used to develop a transformer model appropriate for the EMTP/ATP‐type programs. Copyright © 2009 John Wiley & Sons, Ltd.     

Green's function approach for modeling of electrostatic effects in nanoscale fully depleted double‐gate silicon‐on‐insulator metal‐oxide‐semiconductor field‐effect transistors

Exact solution of two‐dimensional (2D) Poisson's equation for fully depleted double‐gate silicon‐on‐insulator metal‐oxide‐semiconductor field‐effect transistor is derived using three‐zone Green's function solution technique. Framework consists of consideration of source–drain junction curvature. 2D potential profile obtained forms the basis for estimation of threshold voltage. Temperature dependence of front surface potential distribution, back surface potential distribution and front‐gate threshold voltage are modeled using temperature sensitive parameters. Applying newly developed model, surface potential and threshold voltage sensitivities to gate oxide thickness have been comprehensively investigated. Device simulation is performed using ATLAS 2D (SILVACO, 4701 Patrick Henry Drive, Bldg. Santa Clara, CA 95054 USA) device simulator, and the results obtained are compared with the proposed 2D model. The model results are found to be in good agreement with the simulated data. Copyright © 2013 John Wiley & Sons, Ltd.     

Investigation of numerical time‐integrations of Maxwell's equations using the staggered grid spatial discretization

The Yee‐method is a simple and elegant way of solving the time‐dependent Maxwell's equations. On the other hand, this method has some inherent drawbacks too. The main one is that its stability requires a very strict upper bound for the possible time‐steps. This is why, during the last decade, the main goal was to construct such methods that are unconditionally stable. This means that the time‐step can be chosen based only on accuracy instead of stability considerations. In this paper we give a uniform treatment of methods that use the same spatial staggered grid approximation as the classical Yee‐method. Three other numerical methods are discussed: the Namiki–Zheng–Chen–Zhang alternating direction implicit method (NZCZ), the Kole–Figge‐de Raedt method (KFR) and a Krylov‐space method. All methods are discussed with non‐homogeneous material parameters. We show how the existing finite difference numerical methods are based on the approximation of a matrix exponential. With this formulation we prove the unconditional stability of the NZCZ method without any computer algebraic tool. Moreover, we accelerate the Krylov‐space method with a skew‐symmetric formulation of the semi‐discretized equations. Our main goal is to compare the methods from the point of view of the computational speed. This question is investigated in ID numerical tests. Copyright © 2005 John Wiley & Sons, Ltd.     

Semi‐analytical non‐charge‐sheet and non‐depletion MOS model,for inversion charge calculation

A new computationally implemented semi‐analytic mathematical model is presented to obtain a more accurate estimation of the inversion charge in a MOS structure than standard models. The values of the error of the inversion charge obtained are compared with the assumed ‘exact’ numerical calculated values. These errors are appreciably smaller than the estimation coming from the classical charge‐sheet and depletion approximations. Also the calculation time to obtain the inversion charge is shown to be significantly lower than the numerical one. Because of its accuracy and its relatively low computational speed, the proposed model is a good alternative methodology for the calculation of the inversion charge of MOSFET transistors as a function of their physical features and gate bias voltage. In this sense it should be very useful to be implemented by computer‐aided design integrated circuit simulation software. Copyright © 2013 John Wiley & Sons, Ltd.     

A nonlinear two‐cluster Gaussian mixture scenario model for wind power

To overcome the low precision and poor flexibility of the wind power scenario model, this paper proposes a nonlinear two‐cluster Gaussian mixture scenario model for wind power based on the expectation maximization (EM) algorithm according to Wasserstein optimal scenario theory. First, the EM algorithm is used to classify the wind speed data and establish the Gaussian mixture model (GMM). Second, the Wasserstein distance scenarios of two Gaussian distributions with different parameters are calculated based on wind speed data and nonlinear wind turbine power curve, respectively. Finally, a cross combination of the two scenarios is used to obtain the nonlinear two‐cluster mixture scenario model with a mixture Gaussian probability parameters. The obtained results show that the nonlinear two‐cluster Gaussian mixture scenario model is applicable not only to the regular wind speed probability distribution but also to that with irregular and two‐peak characteristics. Moreover, the generated energy deviation can be controlled within 2.5%. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.