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This work is motivated by the fact that the reliability of electrical connectors influenced by their mechanical behavior and fatigue life directly affects the working performance of the whole equipment system. In this paper, theoretical analyses of insertion force, maximum stress, and fatigue life in an aviation electrical connector are presented and the corresponding mathematical models are firstly derived. Then, to numerically investigate its mechanical behavior and fatigue life, a simplified 3D FE model is developed by using ABAQUS and FE‐SAFE software and verified by experiments and theoretical analysis. Finally, the distribution and evolution characteristics of contact forces, stress and fatigue life considering the influences of reed thickness and slot width are quantitatively analyzed in details. The results indicate that the insertion force first increases and then stabilizes at the level of 0.16 N as the pin head is fully inserted into the jack, which shows an opposite to the evolution of extraction force. Moreover, the maximum value of stress and the minimum value of fatigue life are all located at the root of the jack reed. Besides, unlike the small effect of slot width, the Fimax and σmax values obviously increase and the Nf value decreases with the increment of reed thickness. [ABSTRACT FROM AUTHOR]

The focus of this paper is on the solution of Maxwell's equations for time-harmonic fields on triangular, possibly non-orthogonal meshes. The method described was first introduced in References 1 and 2 for eigenvalue problems arising in the design of accelerator components and dielectric loaded waveguides. It is based on the well-known Finite Integration Technique (FIT) which is a proven consistent discretization method for the computation of electromagnetic fields. The FIT-discretization on non-orthogonal 2D grids has close relations to the Nédélec elements or edge elements in the Finite Element Method. Revisiting FIT on triangular grids this paper intends to stimulate thorough studies of the latter subject which is well worth further investigations. Copyright © 1999 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Earlier work using the time dependent Poynting theorem has shown that the complete description of power in a multimodal radiation field requires the use of three numbers; two are sufficient only with a single modal field. Where three numbers are required it is not possible to correctly represent power as a complex number. In the common notation the third number is a suppressed phase angle; when multiple power fields are combined to form a single one it is essential to account for the suppressed phase angles. The differences in power calculations using the time and frequency domain power theorems are manifest in determination of the energy flow that remains local to the source, oscillating between the near field and source, which does not form part of the far field power. In this paper we numerically model, using commonly accepted frequency and time domain techniques, the simplest antenna design that clearly illustrates the differences between time and frequency domain representations of reactive power. We calculate and contrast the instantaneous and the steady-state far field and local powers emitted from two identical, perpendicularly oriented electrically small TM dipoles as a function of relative phase between the two dipoles. Copyright © 1999 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In recent years, the finite-difference time-domain (FDTD) method has been used to simulate a wide range of frequency dependent media. The accuracy of these simulations often depends on how accurately the complex dielectric constant is simulated in the sampled time domain used by FDTD. This paper describes the process of modelling the complex dielectric constant as a digital filtering problem and uses Z transforms to convert the frequency domain expression to a sampled time domain expression. Copyright © 1999 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The analysis of structures which contain thin wires or narrow microstrips using the FDTD method and without resorting to a very fine mesh, has been an area of intensive research for many years. Despite this activity, however, the problem is still not definitively solved. In this paper the problem is attacked by investigating the properties of the FDTD mesh when the material parameters of a single cell, or a small group of cells, are altered. From this, formulae are derived by which these parameters may be chosen in order to accurately represent a conductor of small cross-section. Results are presented which show that accurate results for wire and microstrip transmission lines can be achieved with little or no computational overhead and without the problems of late time instability or spurious field divergence. Copyright © 1999 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Frequency domain transfer functions of microwave systems are usually calculated either directly in the frequency domain or in the time domain in combination with a Fourier analysis. The computation of loss-free linear devices based on eigenfields (resonant fields) offers an alternative to obtaining broadband frequency characteristics with a high accuracy. Such methods are very effective for problems with multiple narrow resonances as many points in frequency domain have to be calculated to sample the maximas, or time domain computations have to deal with long transients. We describe a method of this type and then an improvement that leads directly to transfer functions, which are very accurate even if only modes in the chosen frequency range are taken into account. Generalized macroscopic parameters are introduced as input and output quantities, which are related to conventional quantities such as discrete currents and voltages, wave parameters, or even beam currents and voltages (as defined in accelerator physics for beams of ultra-relativistic charged particles). When the generalized input/output parameters are causal they are related to each other and to state parameters of the eletromagnetic fields by a differential equation with time independent system matrices. The input/output transfer matrix in the frequency domain is an impedance matrix, which is derived from the system matrices of the discretization as well as from a series expansion using eigensolutions. The number of eigenmodes is typically three times the number of meshpoints, but good approximations can be achieved even with a much smaller set of eigenvalues around the frequency range of interest. Another approach to characterizing the system response is based on the output/input relation described by an admittance matrix. Combining both approaches, the error of the approximations can be estimated and significantly reduced. The application of the method is shown for several examples. Copyright © 1999 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

A new approach using FIT-formulation (Finite Integration Technique) (T. Weiland, Electron. Commun., 31, 116–120 (1977); Int. J. Numer. Model., 9, 295–319 (1996)) for simulating waveguide propagation of optical pulses is presented. FIT-methods are widespread in use for broadband linear simulations. In recent years, several attempts have been made to describe different dispersive material-characteristics such as Drude, Debye or Lorentz dispersion. Today advanced FDTD-formulations (Finite Difference Time Domain) also consider non-linear effects (P. M. Goorjian and A. Taflove, IEEE Opt. Lett., 17(3), 180–182 (1992); D. M. Sullivan, IEEE Trans. Microwave Theory Techniques, 43(3), 676–682 (1995)). In the following presented method third-order non-linear effects were described, which can be observed in isotropic media in frequency ranges of optical pulses, by updating material polarization terms using classical descriptions of Lorentz dispersion, Raman scattering and the Kerr effect. The basic idea is transforming these description formulas into sets of linear differential equations and solving them with the help of the general exponential solution. Copyright © 1999 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The simulation of slowly varying electromagnetic fields is possible for very large, realistic problems with finite-difference implicit time-domain (FDiTD) and frequency-domain (FDFD) formulations on the basis of the consistent Finite-Integration Technique (FIT). Magneto-quasistatic time-domain formulations combined with implicit time marching schemes require the repeated solution of real-valued symmetric systems. The solution of driven frequency domain problems usually consists in the solution of one non-Hermitean system. Preconditioned conjugate gradient-type methods are well-suited for this task. They allow the efficient solution even for consistent singular or near-singular systems, which typically arise from formulations for slowly varying electromagnetic fields using the Maxwell-Grid-Equations of the FI-Method. Numerical results for TEAM workshop 11 benchmark problem and for a large practical problem, a shading ring sensor, show that the presented algorithms are capable of solving realistic problems for large numbers of unknowns in acceptable calculation times on contemporary medium sized workstations. Copyright © 1999 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper tries to obtain the maximum estimation accuracy of 2‐dimensional Direction of Arrival (2D‐DOA) from the spatial signal resource in the angle approaching the horizon by using the volume arrays pattern synthesizing. For this purpose, the well‐known Multiple Signal Classification (MUSIC) and the algorithm Root Mean Square Deviation (RMSD) are used to investigate 2D‐DOA estimation accuracy. For accurate design of array structure, the antenna elements' radiation pattern have been considered based on the full‐wave simulations along with the mutual coupling and shadow effects. The results show that the volume array structure presented with 13 radiative elements and the two side angles of 30 and 45 degrees has a much better DOA estimation accuracy in all angles especially in angles close to the horizon, compared to the planar array with the same number of radiative elements. Also, at the angle ±90° from broadside the presented volume aperture provides a maximum gain of up to 15.4 dBi, which is much more than the produced gain of planar aperture under the same conditions. [ABSTRACT FROM AUTHOR]

The numerical techniques required to prove the single‐photon emission from any type of quantum emitter (QE) after being coupled to any nanostructure are presented in this paper. The Purcell effect modifies the emission characteristics of QEs, such as color centers in nanodiamonds, for example, nitrogen‐vacancy (NV) centers, silicon vacancy (SiV) centers, and so forth, or semiconductor quantum dots. Our numerical approach is based on the unique QEs' experimental photophysics parameters and numerical analysis software, which are MATLAB and Quantum Toolbox in Python (QuTiP). Our results show a comparable g(2) (τ) behavior between our proposed numerical model and the other two experimental results for the QE before and after coupling to a plasmonic waveguide with subwavelength dimensions. Our proposed method is essential to prove the single‐photon emission of modeled single‐photon source (SPS) in an on‐chip polarization‐dependent quantum key distribution system (QKD). [ABSTRACT FROM AUTHOR]

This paper describes PWLFIT+, an extension to the frequency domain of PWLFIT, a new paradigm in time‐domain macromodeling for linear multiport systems, based on a piecewise‐linear (PWL) behavioral representation of the S‐parameters step response. While the impulse response of each S‐parameter is approximated as sum of delayed rectangles (rect) functions, its spectrum is interpolated as sum of the corresponding delayed cardinal sine (sinc) functions. Exploiting this correspondence, the model building is performed by an iterative procedure where the PWL macromodels can be determined in order to meet defined accuracy goals on the spectrum. At runtime, waves at macromodels ports are calculated using the Segment Fast Convolution (SFC) algorithm within the Digital Wave Simulator (DWS) framework. The proposed method is characterized by its simplicity, stability, speed and scalability, all features that are emphasized when it is used in the DWS framework. After an analysis of the excellent numerical features of SFC in the Z‐domain, clearly differentiated with respect conventional macromodeling methods based on poles and residues, two suitable application examples are presented to demonstrate the unique features of PWLFIT+. [ABSTRACT FROM AUTHOR]

Switch‐mode power converters are used in various applications to convert between different voltage (or current) levels. They use transistors to switch on and off the input voltage to generate a pulsed voltage whose arithmetic average is the desired output voltage of the converter. After smoothening by filters, the converter output is used to supply devices. The simulation of these switch‐mode power converters by conventional time discretization is computationally expensive since a high number of time steps is necessary to properly resolve the unknown state variables and detect switch events of the excitation. This paper proposes a multirate method based on the concept of multirate partial differential equations (MPDEs), which splits the solution into fast varying and slowly varying parts. The method is designed to work with pulse‐width modulated (PWM) excitation with a constant switching cycle and varying duty cycle. It is applicable to problems in which the circuit part generating the pulsed voltage, i.e., consisting of transistors, diodes, and voltage sources, can be approximated by an ideal PWM excitation. Switching‐event detection is no longer necessary and a much smaller number of time steps are required for a decent resolution, thus leading to a highly efficient method. The important case of varying duty cycles in the MPDE framework is addressed for the first time. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we develop a simple expression to evaluate the electric force acting on a carbon nanotube–(CNT) based nanoactuator assuming a nonparallel actuating plates (out‐of‐plane) arrangement. The actuating force is initiated by the asymmetry of the resultant electric fringing fields caused mainly due to the nonparallel electrodes arrangement. The nanoactuator is designed based on a CNT flexible electrode (nonstationary) and 2 symmetrically located actuating stationary rectangular shaped out‐of‐plane plates. The resultant electric force is mathematically approximated from the outcomes of a planar (2‐D) numerical solution of the electric problem via a finite element–based numerical analysis. The influence of the design geometrical parameters on the resultant electric force are examined. Several key design parameters were inspected: the width and thickness of the stationary actuating electrodes, the radius of the flexible electrode (the CNT), and the lateral and vertical separation distances between the movable and grounded electrodes. Through several simulations, we show the effect of the lateral and vertical offsets as well as the electrodes thickness in the optimization of the performance of the nanoactuator assuming such nonparallel plates actuating configuration. We also simulate the effect on the resultant actuating force level with the electrode thickness as well as the electrodes lateral separation distance. [ABSTRACT FROM AUTHOR]

Abstract: Some soft magnetic materials are strongly dependent of the temperature, because of their low Curie temperature. To be able to predict their behaviour in electrical devices, hysteresis models able to take into account the temperature are needed. The vector play static hysteresis model is an interesting hysteresis model that can be modified to be able to take into account the thermal behaviour. In this paper, the temperature is taken into account in this last model through its parameters. The variations of some parameters with temperature are mainly issued from numerical interpolation and specific assumptions. Simulation results are compared to measurements and discussed. [ABSTRACT FROM AUTHOR]

In this paper, the convolution perfectly matched layer (CPML) absorbing boundary conditions (ABC) in five-step locally one-dimensional finite-difference time-domain (LOD5-FDTD) method are deduced. The formulation of the LOD5-FDTD is derived and numerical results are demonstrated for different Courant Friedrich Levy numbers (CFL) in the simulation domain in the test. Then, using a sinusoidal source, the field phase distribution surrounded by the CPML-ABC is calculated. The results of these simulation experiments illustrate that the CPML-ABC can be used efficiently in the LOD5-FDTD method. [ABSTRACT FROM AUTHOR]

Energy-harvesting devices have been developed for the use of voltage sources in low-powered wireless sensors. Vibration energy harvesters generate electric power from ambient vibration of constructions such as bridges, tunnel walls, and power pylons. Vibration energy harvesters are required to have high power generation efficiency over a wide vibration frequency. This paper presents a vibration energy harvester in which closed magnetic circuits are formed aiming at high efficiency and double-well potential is formed to have chaotic vibration to realize wide frequency-range power generation. In particular, the conditions for emergence of chaotic vibration are clarified based on numerical analysis and experiments. [ABSTRACT FROM AUTHOR]

This paper deals with the effect of structural, doping, and work function parameter variations on the Radio-Frequency metrics, unity gain cutoff frequency (ft), non-quasi static delay, intrinsic gain, and noise figure in double-gate Fin Field Effect Transistor (FinFET), junctionless FinFETs, and conventional and junctionless gate-all-around devices using Technology Computer-Aided Design simulations. This is done quantitatively by performing a simple sensitivity study experiment and screening analysis through Plackett-Burman's design of experiment approach. The individual and overall rankings of the input parameters for the devices considered are given. Gate length affects FinFETs significantly, whereas it does not affect junctionless devices. The impact of work function on the output responses is more in junctionless devices compared with that of FinFET and gate-all-around devices. Ovality in gate-all-around devices has no impact on all the output responses. [ABSTRACT FROM AUTHOR]

ABSTRACT This paper analyzes and discusses some computational methods for the simulation of the electric and magnetic behavior versus frequency of heterogeneous soft magnetic materials (such as soft magnetic composites, soft ferrites, and polymer composites). All these media are characterized by a granular structure, with magnetic grains separated by high resistivity layers, so that the study involves phenomena occurring at both macroscopic (sample size) and microscopic scale (grain size). The main purpose of the analysis is the prediction of the effective magnetic and electric properties, and of the relative energy losses starting from the known properties of the constituents, as well as the extrapolation of the constituent parameters from the measured global properties of the heterogeneous medium (inverse problem). The adopted computational methodologies include both analytical mixing rules and numerical approaches on the basis of homogenization and multiscale methods. The paper reports some examples illustrating advantages and drawbacks of these techniques, giving also an outline of nonlinear media homogenization. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY In this paper, a propagator matrix method applied to logging-while-drilling tools is introduced and extended to deal with the anisotropic and radially inhomogeneous earth formations. This method expands the Maxwell's equations in the transverse direction, constructs the relationship between propagator matrix and reflection matrix, and obtains the solution by using the reflection matrix. We systematically derived the formulas of propagator matrix method in isotropic media, uniaxially anisotropic media, fully anisotropic media, and radially inhomogeneous media respectively. In order to obtain the propagator matrix in complex media, we used the fourth-order Runge-Kutta scheme. Numerical experiments show that, compared with traditional methods, the propagator matrix method has wide range of applications while maintaining low computational costs and high accuracy. All algorithms presented in the paper have been parallelized and implemented on a high-performance computing platform. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this paper, Monte Carlo (MC) simulation has been applied for the analysis and stochastic calculus of far-field radiation from the small, large, and infinite open-ended waveguide arrays. Elements of the arrays are excited by the fundamental TE10 mode and with equal amplitude and linear phase. The simulated results from MC are compared closely with the finite element method (FEM). Numerical analysis based on FEM is performed using Ansoft High Frequency Structural Simulator to calculate the far-field radiation characteristics of the arrays. The accuracy and the effectiveness of the aforesaid method, which is based on Monte Carlo integration technique, are also demonstrated in uniformly and nonuniformly spaced waveguide arrays for pattern synthesis or achieving side lobe level reduction. The arrays with arbitrary shapes are simply evaluated by MC method in equal spacing array. It is found that by applying MC simulation, the open-ended waveguide arrays have the ability to produce the desired radiation pattern and could satisfy requirements for many applications. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this paper, we develop some mesh-free particle methods for magneto-hydrodynamics equations. Our focus is on the problems with high Hartmann numbers, which generate unstable solutions in most numerical methods. Several numerical tests validate the efficiency of our methods. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this paper, an effective Schur complement method is presented to solve transmission-constrained dispatch (TCD) for Monte Carlo production costing. Several techniques for improving TCD performance are also proposed by taking the advantages of TCD special problem structures. Numerical testing on a real-life large-scale power system is presented to illustrate the performance of these proposed methodologies. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

A complementary metal-oxide semiconductor photodetector with ring-shaped structure is presented in this paper, which consists of a p-channel metal-oxide-semiconductor field-effect transistor and lateral photodiodes and can be applied for ultraviolet (UV)/blue detection. The p-channel metal-oxide-semiconductor is enclosed by ring-shaped lateral photodiodes and lateral ring-shaped photodiodes for enlarging near-surface depletion region of the photodetector. Photoelectric conversion process of the photodetector has been modeled, and some performance parameters of photodetector have been derived and evaluated. The simulation results show that the photodetector can exhibit a high current responsivity of 1 × 10−3 Å even for ultra-weak light such as 0.01 μW. The composite photodetector is fabricated in a standard 0.18 µm complementary metal-oxide semiconductor technology. The test results reveal that the presented photodetector, which just like predicted by the model, is an effective way to solve the low response of silicon-based UV detector. In a word, the presented photodetector has a big potential application value in weak light and UV/blue light detection. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY In this paper, a numerical meshless particle method is presented in order to solve the magnetoencephalography forward problem for analyzing the complex activation patterns in the human brain. The forward problem is devoted to compute the scalp potential and magnetic field distribution generated by a set of current sources representing the neural activity, and in this paper, it has been approached by means of the smoothed particle hydrodynamics method suitably handled. The Poisson equation generated by the quasi-stationary Maxwell's curl equations, by assuming Neumann boundary conditions has been considered, and the current sources have been simulated by current dipoles. The adopted meshless particle model has provided good results in agreement with the analytical ones and by overcoming the drawback of the mesh generation. The numerical model has been validated, at first, in computing the electric potential and the external magnetic field for a dipole plunged near the upper surface of a homogeneous sphere simulating the human brain. Simulation results obtained by simulating two concentric spheres with different conductivities are also reported. Moreover, in order to better assess the validity of the proposed approach, a realistic human brain cortex model has been also simulated and compared with boundary element method results. A satisfactory agreement has been reached. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper demonstrates the capability of our previously published undoped Double-Gate (DG) MOSFET explicit and analytical compact model to also forecast the effect of the volume inversion (VI) on the intrinsic capacitances. For that purpose, we present simulation results for these capacitances. We show now that the model presents an accurate dependence on the silicon layer thickness, consistent with two-dimensional numerical simulations, for both thin and thick silicon films. As opposed to our previous work, here we test the capacitance model for three different film thicknesses and also show that the transition from VI regime to dual gate behaviour is well simulated. We demonstrate in this paper that even if the current drive and transconductance are enhanced in VI regime, our results show that intrinsic capacitances are higher as well, which may limit the high-speed (delay time) behaviour of DG MOSFETs under VI regime. The good agreement between the numerical simulations and our model shows the high potential of our complete DG MOSFET model. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Hong Lei, Lian-Ze Wang and Zi-Niu Wu presented new simple and convenient solutions of the magnetic field for an arbitrary geometry coil with rectangular cross section. They treated two types of basic forms: the trapezoidal prism segment and curved prism segment. The curved prism segment has been divided into a series of small trapezoidal prism segments with the same cross section and its magnetic field is a vector sum of the individual fields created by each small trapezoidal prism conductor. For one trapezoidal prism conductor the magnetic field is obtained by 1-D integrals using Romberg numerical integration. In this paper, we give a completely analytical solution of these 1-D integrals that considerably saves the computational time especially in the computation of the magnetic field nearby the conductor surface, at the conductor surface and inside the conductor. From obtained analytical expressions the treatment of singularities can be easily done. Also, we tested four types of numerical integration (Gaussian, Romberg, Simpson and Lobatto) to find the most convenient singularity treatment of 1-D integrals. These obtained results are compared with those obtained analytically so that one can understand the advantage of the proposed approach. The paper points out on the accuracy and the computational cost. Copyright © 2005 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this paper, we propose a novel formulation to solve the time-domain combined field integral equation (TD-CFIE) for analysing the transient electromagnetic response from three-dimensional (3D) closed conducting bodies. Instead of the conventional marching-on in time (MOT) technique, the solution methods in this paper are based on the Galerkin's method that involves separate spatial and temporal testing procedure. Triangular patch basis functions are used for spatial expansion and testing functions for arbitrarily shaped 3D closed structures. The time-domain unknown coefficient is approximated as an orthonormal basis function set that is derived from the Laguerre functions. These basis functions are also used as the temporal testing. With the representation of the derivative of the transient coefficient in an analytic form, the time derivative terms in the integral equations can be handled analytically. We also propose an alternative formulation to solve the TD-CFIE. Two methods are presented that results in very accurate and stable transient responses from conducting objects. Numerical results are presented and compared with the inverse discrete Fourier transform (IDFT) of frequency-domain combined field integral equation (FD-CFIE) solutions. Copyright © 2004 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this paper an efficient algorithm is presented for the development of compact and passive macro-models of electromagnetic devices through the systematic reduction of the order of discrete models for these devices obtained through the use of finite elements. The proposed methodology is founded on a new finite element formulation that casts Maxwell's curl equations in a state-space form. Such state-space representations are very compatible with a class of robust model order reduction techniques based on Krylov subspaces. However, the advantage of this compatibility appears to be hindered by the fact that the state matrix of the discretized Maxwellian system is of dimension almost twice that obtained from the finite element approximation of the electromagnetic vector wave equation. It is shown in this paper that the apparent penalty in both memory and computation efficiency can be avoided by a proper selection of the finite element expansion functions used for the discretization of the electromagnetic fields. More specifically, it is shown that the proper selection of expansion functions renders the state-space form of the Maxwellian system equivalent to the discrete problem obtained from the approximation of the vector wave equation using tangentially continuous vector finite elements. This equivalence is then used to effect Krylov-based model order reduction directly from the finite element approximation of the vector wave equation. In particular, a passive model order reduction algorithm is used for this purpose. The proposed reduced order macro-modelling algorithm is demonstrated through its application to a variety of microwave passive components. Copyright © 2002 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper shows that evanescent waves may be so strongly absorbed within perfectly matched layers (PML) that they cannot be properly sampled by discrete methods. With the finite-difference time-domain (FDTD) method, this results in a severe numerical reflection from vacuum–PML interfaces. A similar reflection also is observed with the transmission line matrix (TLM) method. The case of the finite element method (FEM) is briefly discussed in the paper. Copyright © 2000 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

To make possible the application of the three-dimensional finite element method to electrically large problems, it is combined with the analytical solutions of arbitrary large cavity with aperture. In this paper, detailed analysis for this hybrid method is presented. The element matrices necessary for coupling the finite element method to analytical solutions are given. The proposed hybrid method significantly reduces the number of unknown since only the inhomogeneity needs to be discretized. Thus computer memory and storage demands are reduced. In addition, this hybrid method employs the edge element which is not expected to produce spurious solutions. Also, the formulation presented in this paper preserves the sparsity of the finite element matrix, and does not require any matrix inversion. This new hybrid method is used to compute the field distributions in various partially filled rectangular enclosures. The results match well with the pure edge- based finite element method and analytical solutions. [ABSTRACT FROM AUTHOR]

In this paper we demonstrate the use of differential equations by means of an example from network analysis and show that differential/algebraic equations (DAE), rather than explicit ordinary differential equations (ODE), are more suitable for the description of electrical systems and networks. The main ideas of numerical integration of ODEs are presented. We consider this material from the point of view of replacing the ODE by a difference equation (DE). In particular, the relationship between the ODE and the associated DE is discussed. In the last section the application of integration methods for ODEs upon DAEs and its difficulties are discussed. The paper is intended as a review; but a few new results are also included. [ABSTRACT FROM AUTHOR]

This paper presents an annotated bibliography of numerical modelling in electromagnetic compatibility with emphasis on coupled transmission lines. Although the papers cited generally appeared in the open literature between 1980 and 1990, very useful works prior to that period are covered. [ABSTRACT FROM AUTHOR]

Rigorous full-wave analysis techniques are presently receiving much attention in the design of MICs and, in particular, of MMICs due to increasing circuit packing densities and structural complexity. In this paper, the problems associated with such techniques and previous related work are briefly outlined in the introduction. To obtain self-consistency, the electrodynamic Green's functions and related terms are then formulated for the shielded (M)MIC problem. The final operator equation for the numerical solutions derived and the associated functions space are presented and discussed. The central portion of the paper describes a new numerical solution using a discretized Green's function database technique. The resulting linear system of equations is solved by direct inversion for geometrical complexities involving up to about 1000 unknowns; for a higher number of unknowns, an iterative solution is generated. As an alternative to the database technique developed, a variety of spectral domain iterative solutions has been written and tested as well. This includes application of the conjugate gradient method to the normal operator equation (CON algorithm), an implicit iterative Galerkin approximation called the modified planar conjugate gradient technique (MPCG) and monotonically convergent iteration procedure being a version of the conjugate residual algorithm (CR). Supplementary to this, the extraction of (M)MIC design data from the numerical 3D solutions obtained and error considerations are presented. The paper concludes with a variety of analysis examples of medium to high geometrical complexity and with verification of some results by comparison with measurements and with numerical data from other sources. CPU times required on typical workstations (MicroVAX, HP 9000, etc.) are moderate, thus rendering the techniques presented as useful in the solution of MIC and MMIC design problems. [ABSTRACT FROM AUTHOR]

This paper presents the dispersion characteristics of the FD-TD algorithm by showing the numerical phase and group velocities of the TEM, TE or TM modal solutions. For the TEM wave propagation, there exist three fundamental directions to which phase and group velocities can be expressed by only a single variable (wave number k or frequency ω). Those special directions were chosen to show the dispersive nature of the FD-TD algorithm of which the group and phase velocities depend explicitly on frequencies. In view of similarities between the TLM and FD-TD algorithms, a comparison of phase velocity characteristics of both methods was made. Under the special condition where the stability factor s is larger than ½, the FD-TD algorithm is found less dispersive than that of the original TLM. However, newly developed symmetrical TLM method appears less dispersive than the FD-TD algorithm. In the numerical simulation of waveguide modal solutions, it was found that there exists an optimum frequency which provide least numerical error in the FD-TD application. A procedure, which determines the stability factor s and the maximum allowed frequency Fmax for the best numerical results, is proposed in this paper. [ABSTRACT FROM AUTHOR]

In this paper, a unified cubic flux-controlled memristor is proposed, and how to choose its parameters to obtain an appropriate memristor is investigated. The relevant frequency band of the exciting source that enables the memristor to keep its characteristics (call it mem-frequency band) is analyzed, and the matter of high mem-frequency is also clinched. Based on the trend of their i-v curves versus time, the memristors are divided into two types: P and N. The design, simulations and experiments of the circuits for the presented memristor model are given to describe its dynamical behaviors. The results from simulations and experiments are in good agreement with the theoretical analysis, which are of special guidance for designing such device to satisfy the requirements in practical engineering. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The paper deals with the concept of magnetic current loop as a source model for finite thin-wire antennas. The formulation is based on the Pocklington integro-differential equation with reduced kernel, which is handled by means of various numerical techniques, mostly using the Galerkin-Bubnov variant of Indirect Boundary Element Method. Extensive numerical experiments were carried out on various dipole and monopole antennas using different sources (delta gap, magnetic frill, and magnetic current loop), and results for input admittance are compared with measured data. The magnetic current loop source ensures accurate solution for input admittance. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The paper brings a numerical method for finding multiple DC operating points of circuits containing bipolar and metal oxide semiconductor (MOS) transistors fabricated in micrometer technology. The method is based on the concept of separable Newton homotopy and division of the searching space into currently changed rectangles (boxes). The method traces a piecewise-linear homotopy path and intersects some specific plane at the points corresponding to the operating points. Numerical experiments show that the method is remarkably efficient. Three examples including bipolar junction transistors and metal oxide semiconductor circuits are given. [ABSTRACT FROM AUTHOR]

SUMMARY In a large variety of research areas, convolution products that relate a physical quantity in some observation points with their sources are encountered. When the sources and the observation points coincide, the numerical evaluation of the physical quantity typically leads to order N2 numerical problems. Here, fast Fourier transforms are widely used to reduce the computations to order Nlog N complexity. When adopting Fourier transforms (FFT) for finite physical problems, zero padding is required. Hence, in 2D and 3D problems, an optimization of the evaluation of the convolution product includes a non-execution of Fourier transforms on arrays containing only zeros in the forward 2D or 3D FFT scheme and their corresponding arrays in the inverse 2D or 3D FFT scheme. This paper describes the implementation of such an approach on graphical processing units (GPUs) and compares the time gains on GPU and on CPU. It is found that on CPU, the speedup corresponds with the theoretical limit, while in the GPU implementation, the memory bandwidth limits the speedup ratio. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY In order to reduce the computation time and the memory resources required to solve an electromagnetic field problem, model order reduction approaches can be applied to reduce the size of the linear equation system obtained after discretisation. In the literature, the POD is widely used in engineering. In this paper, we propose to apply the POD in the case of a finite element problem accounting for the movement. The efficiency of this method is evaluated by considering an electrical motor and by comparing with the full model in terms of computational time and accuracy. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY The multiport scattering (S-) parameter matrix is increasingly utilized to compose models of large bit-width interconnect systems with broadband characteristics (frequency range of zero to tens of gigahertz) to perform increasingly accurate signal-integrity and power-integrity simulations. The search for an optimal solution space often requires generation of S-parameter models of interconnect systems for various signal/ground pin mappings, a process that can be computationally costly if the structure is electromagnetically solved for each distinct pin mapping. To expedite this model-generation process, we propose a method in which an N-port structure is electromagnetically solved only once to yield an N × N S-matrix; then, a linear system is formulated and solved to yield an ( N − M) × ( N − M) post-suppressed S-matrix (where M is the number of suppressed ports). This approach results in significant computational savings through elimination of electromagnetic field-solver runs for each distinct pin mapping. Included in this paper is a discussion about the limitations of this technique and several numerical examples. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY In this paper, a numerical model of electromagnetic left-handed metamaterials is proposed. The dispersive properties of these materials are accounted for in the time domain by using the transmission-line matrix method based on Z-transforms. The close agreements obtained between the analytic and numerical results verify the validity, accuracy and stability of the approach. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY This paper discusses the practical implementation on graphics processing unit (GPU) of a computer code for the analysis of electromechanical devices. The software is based on a low frequency integral formulation of the Maxwell equations coupled with the rigid body dynamic equations. The formulation here considered is based on the development of an equivalent network whose parameters are functions of the relative positions and of the velocities of the subparts of the device. Positions and velocities on their turn depend on the force between them that are functions of the electromagnetic quantities. The choice of the numerical methods to manage such a complex coupled problem is an open issue in the electromagnetic community. The use of multicore CPUs can reduce the computation times, but a true breakthrough is achieved by running these codes on GPUs. The practical implementation of an existing code is used as a case study for discussing a number of issues that may arise in the implementation of other GPU-accelerated electromagnetic codes. The implementation here reported has been designed for a multi-GPUs environment where the efficient cooperation between GPUs is a further aspect to be considered. The overall performance of the accelerated code has been evaluated by considering the dynamic analysis of a passive magnetic bearing. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY To improve the efficiency of the harmonic analysis, this paper presents a direct phase-domain harmonic model for long coupled transmission lines, which can take the parameter frequency dependence, the configuration asymmetry, and the untransposition of the line into consideration. The steps of the proposed modeling method are as follows. First, in the direct phase domain and on the basis of the travelling wave equation, the coupled transmission line model was derived in a nodal admittance matrix form. Then the matrix series theory was adopted to realize the numerical calculation of the nodal admittance matrix without relying on the eigenvalue and eigenvector calculations of the propagation matrix. Finally, a recursive approach was proposed to handle the nodal equation of the network containing long transmission lines. Both the accuracy and the efficiency of the proposed approach were verified by comparing with the exact method in which it is necessary to calculate the eigenvalues and eigenvectors of the propagation matrix. The computation time and memory consumption analysis indicates that the proposed approach excels the exact method in saving computation time and memory. It should be emphasized that, by utilizing the recursive approach, the proposed approach is always numerically stable and can also be applied to DC transmission lines. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

ABSTRACT In this paper, a corrective economic dispatch problem formulation for distributed generators in a microgrid is presented, which considers the transition from grid-connected operation to islanded operation. Various constraints related to the operation of a microgrid are modeled, such as spinning reserve requirement for the variation of load demand and the output of intermittent sources, the flow limits between the control areas, and ramping limits of distributed generators. The resulting problem is then solved by an interior point method. Numerical tests based on a three-area ten-unit microgrid system show the effects of these constraints on the generation cost. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY This paper proposes general eigenvalue-based passivity tests for descriptor state space systems, extending the already available tests for standard state space systems. Generalized eigenvalue tests are proposed to identify passivity violations in the positive-real and bounded-real cases. The important practical case of singular descriptor state space systems is also treated. The proposed passivity tests for descriptor systems can be used in the important case of symmetric (reciprocal) systems, as symmetric systems can always be cast in an explicitly reciprocal descriptor state space format. Also, passivity violation assessment methods are developed in the important case of strictly proper symmetric systems, as in that case the classical test matrices for passivity assessment are undefined. Finally, some pertinent numerical examples are given to demonstrate the usefulness and scope of the different passivity violation assessment tests. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY Space mapping (SM) is one of the most popular techniques for creating computationally cheap and reasonably accurate surrogates of electromagnetic-simulated microwave structures (so-called fine models) using underlying coarse models, typically equivalent circuits. One of the drawbacks of SM is that although good modeling accuracy can be obtained using a limited number of training points, SM is not capable of efficiently utilizing larger amount of fine model information, even if it is available. In this paper, we consider various ways of enhancing SM surrogates by exploiting additional training data as well as two function approximation methodologies, kriging and co-kriging. To our knowledge, it is the first application of co-kriging for microwave circuit modeling. With three examples of microstrip filters, we present a comprehensive numerical study in which we compare the accuracy of the basic SM models as well as SM enhanced by kriging and co-kriging. Direct kriging interpolation of fine model data is used as a reference. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY Conventional finite-difference time-domain (FDTD) methodologies incorporate discrete operators with the smallest truncation errors, as those are determined from the application of Taylor expansions. It is generally accepted that such choices, although quite efficient, do not necessarily provide optimum solutions when simulating electromagnetic wave phenomena. With the aim at improving accuracy without increasing the involved computational burden, the present paper is concerned with the development of a higher-order FDTD algorithm, which, in contrast to classic trends, is primarily based on the application of error-controlling ideas to its difference approximations. In essence, a fourth-order scheme is presented, whose spatial expressions are designed to remedy the leading terms of suitable error formulae. The latter can be easily extracted for each operator, given that the general nature of the expected solutions is known in advance. A correction factor is next added to the temporal operators to compensate for remaining errors at a selected wavelength. Unlike other approaches with single-frequency optimization, our technique is not strictly narrowband but capable of outperforming the conventional fourth-order FDTD algorithm in wideband simulations as well, without further modifications. The properties of the proposed scheme are verified through theoretical studies, as well as harmonic and multifrequency numerical tests, where comparisons with other standard techniques are performed. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY The goal of this paper is to develop an efficient and accurate computation scheme based on mixed-order curved moment method for computing scattering from complex targets. To this end, the numerical performances of different kinds of higher-order basis functions are presented and compared numerically. The formulae in the improved Duffy method for higher-order curved moment method are derived and given explicitly. An efficient and accurate computation scheme is presented and implemented on the basis of the optimized triangular hierarchical higher-order basis function and the improved Duffy method. Numerical experiments are performed to show accuracy and efficiency of the presented computation scheme for complex targets. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY The scaled boundary FEM (SBFEM) is a novel semi-analytical approach, which combines the advantages of the FEM and BEM with appealing features of its own. In this paper, the method is applied to analyse the quadruple corner-cut ridged elliptical waveguide. A quarter of the waveguide is adopted and divided into a few subdomains. SBFEM only discretizes the surface boundaries of the subdomains in the sense of FEM, and no discretization of side-face boundaries is needed, leading to great flexibility in mesh generation with very few nodes. It transforms the governing PDEs to ODEs of the radial parameter by the variational principle. The radial differential equation is then solved fully analytically without adoption of any numerical scheme, which brings out the inherent advantage for solving a singularity problem. Based on the SBFEM governing equation and introducing the dynamic stiffness of waveguide, a generalised eigenvalue equation with respect to cut-off wave number is formulated by a continued fraction solution without introducing an internal mesh. The numerical example demonstrates the simplicity, excellent computation accuracy and efficiency of the present SBFEM approach. Influences of corner-cut ridge dimensions on the cut-off wave numbers of modes are examined in detail. Therefore, these results provide an extension to the existing design data for ridged waveguides and are considered helpful in practical applications. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY The task of reducing the noise and distortion generated by a laser transmitter has always been a challenge to improve the performance of radio over fiber systems. This paper presents a compensation system for nonlinear distortion of a laser transmitter supporting 5.2 GHz radio transmission over fiber employing a feed-forward linearization technique. The nonlinearity of the laser diode is modeled using Volterra series analysis. The proposed linearization system is also simulated using commercial optical system software. The novel design has achieved 30 dB nonlinearity reduction considering 800 MHz modulation bandwidth. As an addition, this work also analyzes the effect of transmission length towards distortion reduction of the proposed system. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]