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Highlights Textile composites are advanced materials composed of preforms combined with matrix materials. The fiber structure in the preform has a significant impact on the mechanical properties of the composite. Precise control over preform dimensions and internal fiber structural uniformity, termed ‘accurate shape control’, is essential to ensure reliable and stable composite component mechanical properties. This paper reviews current research progress on fabric deformation mechanisms, focusing on experimental characterization and numerical simulation. Experimental methods for fabric deformation include tensile, compression, bending, and shear deformation, whereas numerical methods encompass macroscopic continuum, discrete, and semi‐discrete models. The insights offered in this paper will aid a greater understanding of fabric deformation mechanisms, enabling an accurate prediction of complex shape molding and effective process parameter design, ultimately facilitating the structural design and engineering applications of textile composites. Recent trends and challenges in the study of fabric deformation mechanisms are presented. The experimental methods for fabric deformation were summarized and evaluated. Representative numerical modeling techniques and simulation methods are discussed. Some recommendations on potential future research directions are detailed. [ABSTRACT FROM AUTHOR]

For the simulation of acoustic-structure interaction problems, the coupled field equations must be solved. The structure is commonly discretized using finite elements, whereas for the acoustic field the boundary element method (BEM) is favorable. A mortar BEM-FEM coupling algorithm is developed that allows the combination of non-conforming meshes. The high flexibility for the choice of discretizations offers a high efficiency, since specialized shape functions and adaptive mesh refinement can be used in the subdomains. The mortar coupling algorithm yields a saddle point problem that is solved using a preconditioned inexact Uzawa algorithm. The iterative solver enables the use of the fast multipole BEM and thus coupled simulations on large boundary element models. [ABSTRACT FROM AUTHOR]

Many biological quantities cannot be measured directly but rather need to be estimated from models. Estimates from models are statistical objects with variance and, when derived simultaneously, covariance. It is well known that their variance–covariance (VC) matrix must be considered in subsequent analyses. Although it is always preferable to carry out the proposed analyses on the raw data themselves, a two‐step approach cannot always be avoided. This situation arises when the parameters of a multinomial must be regressed against a covariate. The Delta method is an appropriate and frequently recommended way of deriving variance approximations of transformed and correlated variables. Implementing the Delta method is not trivial, and there is a lack of a detailed information on the procedure in the literature for complex situations such as those involved in constraining the parameters of a multinomial distribution. This paper proposes a how‐to guide for calculating the correct VC matrices of dependant estimates involved in multinomial distributions and how to use them for testing the effects of covariates in post hoc analyses when the integration of these analyses directly into a model is not possible. For illustrative purpose, we focus on variables calculated in capture–recapture models, but the same procedure can be applied to all analyses dealing with correlated estimates with multinomial distribution and their variances and covariances. This paper proposes a how‐to guide about how to calculate the correct VC matrices of dependant estimates involved in multinomial distributions and how to use them for testing the effects of covariates in post hoc analyses when the integration of these analyses directly into a model is not possible. [ABSTRACT FROM AUTHOR]

The Particle Swarm Optimization method is one of the most powerful optimization methods available for solving global optimization problems. However, knowledge of adaptive strategies for tuning the parameters of the method for application to large-scale nonlinear nonconvex optimization problems is as yet limited. This paper describes an adaptive strategy for tuning the parameters of the PSO method based on some numerical analysis of the behavior of PSO. The proposed adaptive tuning strategy is based on self-tuning of the parameters of PSO, which utilizes the information about the frequency of an updated global best of a swarm. The feasibility and advantages of the proposed adaptive PSO algorithm are demonstrated through some numerical simulations using three different typical global optimization test problems. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 159(4): 38– 46, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10. 1002/eej. 20487 [ABSTRACT FROM AUTHOR]

Modeling the motion of the Earth's axis, i.e., its spin, nutation and its precession, is a prime example of our ongoing effort to simulate the behavior of complex mechanical systems. In fact, models of increasing complexity of this motion have been presented for more than 400 years leading to an increasingly accurate description. The objective of this paper is twofold namely, first, to provide a review of these efforts and, second, to provide an improved analysis, if possible, based on today's numerical possibilities. Newton himself treated the problem of the precession of the Earth, a.k.a. the precession of the equinoxes, in Liber III, Propositio XXXIX of his Principia . He decomposed the duration of the full precession into a part due to the Sun and another part due to the Moon, which would lead to a total duration of 25,918 years. This agrees fairly well with the experimentally observed value. However, Newton does not really provide a concise rational derivation of his result. This task was left to Chandrasekhar in Chapter 26 of his annotations to Newton's book . He follows an approach suggested by Scarborough starting from Euler's equations for the gyroscope and by calculating the torques due to the Sun and to the Moon on a tilted spheroidal Earth. These differential equations can be solved approximately in an analytic fashion, yielding something close to Newton's more or less fortuitous result. However, the equations can also be treated more properly in a numerical fashion by using a Runge-Kutta approach allowing for a study of their general non-linear behavior. This paper will show how and discuss the outcome of the numerical solution. A comparison to actual measurements will also be attempted. When solving the Euler equations for the aforementioned case numerically it shows that besides the precessional movement of the Earth's axis there is also a nutational one present. However, as we shall show, if Scarborough's procedure is followed, the period of this nutation turns out to be roughly half a year with a very small amplitude whereas the observed (main) nutational period is much longer, namely roughly nineteen years, and much more intense amplitude-wise. The reason for this discrepancy is based on the assumption that the torques of both the Sun and the Moon are due to gravitational actions within the equinoctial plane. Whilst this is true for the Sun, the revolution of the Moon around the Earth occurs in a plane, which is inclined by roughly 5° w.r.t. the equinoctial. Moreover, this plane rotates such that the ascending and descending nodes of the moon precede with a period of roughly 18 years. If all of this is taken into account the analytically predicted nutation period will be of the order of the observed value . As in the case of the precession we will provide a more stringent analysis based on a numerical solution of the Euler equations, which leads beyond the results presented in Sect.12.10 of . [ABSTRACT FROM AUTHOR]

The paper documents the construction of a novel nonlinear model of a noise-driven, multi-dimensional, bistable circuit employing stochastic resonance. Simulations are performed in order to characterize the various relevant device performance measures and their sensitivity to parameter values. The numerical results are considered in the context of nonlinear energy harvesting, and it is explained how the developed simulation tools could prove useful for the development of such devices. The topic of reduced-order modelling is discussed, and it is shown that this approach leads to incorrect results. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Recently, the present authors have applied the FDTD (Finite-Difference Time-Domain) method to acoustic problems. FDTD is one of the finite-difference methods in the time domain used in electromagnetic problems. However, in this method, phase errors cannot be neglected in a large-scale propagation analysis such as indoor acoustic propagation and they cause problems in the analysis. In order to reduce the phase error, Cole has invented the NS-FDTD (Non-Standard FDTD) method for electromagnetic problems. However, the numerical dispersion and stability condition are not described in Cole's paper. Also, the definition is given only for a cubic lattice. In this paper, an application of the three-dimensional NS-FDTD method to acoustic problems is attempted. Further, the method is extended to a rectangular lattice. The numerical dispersion and stability condition of the present method are derived. As a result, it is shown that the present method has much higher accuracy than the FDTD method. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 85(9): 15–24, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.1115 [ABSTRACT FROM AUTHOR]

This paper describes the current status of the development of electromagnetic launchers such as the railgun at ISAS. The railgun is the most improved accelerator of Electromagnetic Launchers (EML). EML offers a potential for accelerating a projectile to much greater velocities than achieved with conventional powder guns or light gas guns. However, there has been little progress in increasing the velocity of EMLs since the experiment by Rashleigh and Marshall. A few experiments have been reported achieving velocities greater than 6 km/s. The authors have achieved velocities greater than 6 km/s by reducing plasma leakage which is one of the factors limiting velocity. In this paper a 6 km/s launch is reported, compared with the results of two other shots considered from the viewpoint of plasma leakage, and the effect of entrainment of eroded material into the armature by rail ablation was discussed on the basis of simulated numerical calculations. [ABSTRACT FROM AUTHOR]

Eulerian‐based smoke simulations are sensitive to the initial parameters and grid resolutions. Due to the numerical dissipation on different levels of the grid and the nonlinearity of the governing equations, the differences in simulation resolutions will result in different results. This makes it challenging for artists to preview the animation results based on low‐resolution simulations. In this paper, we propose a learning‐based flow correction method for fast previewing based on low‐resolution smoke simulations. The main components of our approach lie in a deep convolutional neural network, a grid‐layer feature vector and a special loss function. We provide a novel matching model to represent the relationship between low‐resolution and high‐resolution smoke simulations and correct the overall shape of a low‐resolution simulation to closely follow the shape of a high‐resolution down‐sampled version. We introduce the grid‐layer concept to effectively represent the 3D fluid shape, which can also reduce the input and output dimensions. We design a special loss function for the fluid divergence‐free constraint in the neural network training process. We have demonstrated the efficacy and the generality of our approach by simulating a diversity of animations deviating from the original training set. In addition, we have integrated our approach into an existing fluid simulation framework to showcase its wide applications. [ABSTRACT FROM AUTHOR]

Summary: This paper studies the connected cruise control problem for a platoon of human‐operated and autonomous vehicles. The autonomous vehicles can receive motional data, ie, headway and velocity information from other vehicles by wireless vehicle‐to‐vehicle communication. The use of wireless communications in information exchange between vehicles inevitably causes input delay in the platooning system. Meanwhile, unpredictable behaviors of the leading vehicle constitute exogenous disturbance for the system. An adaptive optimal control problem with input delay and disturbance is formulated, and a novel data‐driven control solution is proposed such that each vehicle in the platoon can achieve safe distance and desired velocity. By adopting an adaptive dynamic programming technique with sampled‐data system theory, a data‐driven adaptive optimal control approach is proposed for autonomous vehicles by the learning strategies of policy iteration without the accurate knowledge of the dynamics of all human drivers and vehicles. The efficacy of the proposed controller is substantiated by rigorous analysis and validated by simulation results in different scenarios. [ABSTRACT FROM AUTHOR]

Summary: This paper discusses the formulation and the numerical performance of a fully implicit algorithm used to integrate a rate‐dependent model defined within a breakage mechanics framework. For this purpose, a Generalized Backward Euler (GBE) algorithm has been implemented according to two different linearization strategies: The former is derived by a direct linearization of the constitutive equations, while the latter introduces rate effects through a consistency parameter. The accuracy and efficiency of the GBE algorithm have been investigated by (1) performing material point analyses and (2) solving initial boundary value problems. In both cases, the overall performance of the underlying algorithm is inspected for a range of loading rates, thus simulating comminution from slow to fast dynamic problems. As the viscous response of the breakage model can be recast through a viscous nucleus function, the presented algorithm can be considered as a general framework to integrate constitutive equations relying on the overstress approach typical of Perzyna‐like viscoplastic models. [ABSTRACT FROM AUTHOR]

Abstract: In this paper we present a novel operator splitting approach for corotated FEM simulations. The deformation energy of the corotated linear material model consists of two additive terms. The first term models stretching in the individual spatial directions and the second term describes resistance to volume changes. By formulating the backward Euler time integration scheme as an optimization problem, we show that the first term is invariant to rotations. This allows us to use an operator splitting approach and to solve both terms individually with different numerical methods. The stretching part is solved accurately with an optimization integrator, which can be done very efficiently because the system matrix is constant over time such that its Cholesky factorization can be precomputed. The volume term is solved approximately by using the compliant constraints method and Gauss‐Seidel iterations. Further, we introduce the analytic polar decomposition which allows us to speed up the extraction of the rotational part of the deformation gradient and to recover inverted elements. Finally, this results in an extremely fast and robust simulation method with high visual quality that outperforms standard corotated FEMs by more than two orders of magnitude and even the fast but inaccurate PBD and shape matching methods by more than one order of magnitude without having their typical drawbacks. This enables a very efficient simulation of complex scenes containing more than a million elements. [ABSTRACT FROM AUTHOR]

Time‐dependent reliability analysis of structures by the use of an outcrossing approach normally requires the so‐called outcrossing rate to be estimated. A variety of methods has been recorded in the literature to evaluate this rate both for continues and discrete processes. Despite the availability of these methods, still more general and at the same time less sophisticated approaches are desired. In this paper, attempt is made to use the basic idea of "parallel system reliability formulation" to calculate the outcrossing rate for circumstances where the processes are continuous. These calculations are carried out by directional simulation. It is shown that this approach is simple to implement and may be used for the cases where the problem involves nonstationary processes and also for the cases where several limit state functions may have to be considered. [ABSTRACT FROM AUTHOR]

This paper aims at assessing the relevance of communicating central bank's forecasts to the private sector under discretionary monetary policy. In a New Keynesian environment, the central bank and the private sector have different information sets. The private sector uses the central bank's expectations as a signal in order to update its priors, which are constituted by standard adaptive learning expectations. E-stability is positively affected by a high correlation between actual inflation and the signal about inflation. Numerical simulations show that the presence of signals is beneficial both in the long and in the short run. [ABSTRACT FROM AUTHOR]

Capturing carbon dioxide (CO2) from large point sources and depositing it in a geological formation is an efficient way of decreasing CO2 concentration in the atmosphere. A comprehensive study is required to perform a safe and efficient CO2 capture and storage (CCS) project. The study includes different steps, such as selecting proper underground storage and keeping track of CO2 behavior in the storage environment. Numerical reservoir simulators are the conventional tools used to implement such an analysis. The intricacy of simulating multiphase flow, having a large number of time steps required to study injection and post-injection periods of CO2 sequestration, a highly heterogeneous reservoir, a large number of wells, etc., will lead to a complicated reservoir model. A single realization for such a reservoir takes hours to run. Additionally, a thorough understanding of the CO2 sequestration process requires multiple realizations of the reservoir model. Consequently, using a conventional numerical simulator makes the computational cost of the analysis too high to be practical. In this paper, we examine the application of a relatively new technology, the Surrogate Reservoir Model (SRM), as an alternative tool to solve the aforementioned problems. SRM is a replica of full-field reservoir simulation models. It can generate outputs in a very short time with reasonable accuracy. These characteristics make SRM a unique tool in CO2 sequestration modeling. This paper proposes developing an SRM for a CO2 sequestration project ongoing in the SACROC unit to model pressure behavior and phase saturation distributions during different time steps of the CO2 storage process. [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]

Interactive rigid body simulation is an important part of many modern computer tools, which no authoring tool nor game engine can do without. Such high-performance computer tools open up new possibilities for changing how designers, engineers, modelers and animators work with their design problems. This paper is a self contained state-of-the-art report on the physics, the models, the numerical methods and the algorithms used in interactive rigid body simulation all of which have evolved and matured over the past 20 years. Furthermore, the paper communicates the mathematical and theoretical details in a pedagogical manner. This paper is not only a stake in the sand on what has been done, it also seeks to give the reader deeper insights to help guide their future research. [ABSTRACT FROM AUTHOR]

The article focuses on the need for fast and accurate numerical simulation techniques due to advances in wireless and microwave communication systems. A number of practical geometries have been left untreated because of their complexity and the inability of existing techniques to deal with requirements for large size and higher resolution. An accurate characterization of the passive and active structures is the first step need for the development of efficient numerical algorithms.

This paper presents a method for nested fluid simulation based on smoothed particle hydrodynamics. Given suitable background flow information of an “external flow” as it evolves in time, our method simulates the motion of particles only within a local material region. In order to perform the simulation, the background physical quantities need to be transferred to the local fluid particles. We employ ghost particles to carry the given physical quantities to the nested fluid. We also solve the problem of density computation appropriately for the ghost particles. Our numerical tests show that accurate local fluid motion can be obtained in such a nested volume of fluid particles. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Reliability demonstration test (RDT) is a critical and necessary step before the acceptance of an industrial system. Generally, a RDT focuses on designing a test plan through which one can judge whether the system reliability indices meet specific requirements. There are many established RDT plans, but few have incorporated the reliability growth aspects of the corresponding products. In this paper, we examine a comprehensive test plan that involves information concerning the reliability growth stage. An approach for RDT under the assumption of the power-law model is proposed. It combines data related to the growth stage with those pertaining to the test stage of the product to reduce the cost of the test. Through simulation studies and numerical examples, we illustrate the characteristics of the test plan and significant reduction in test costs through our approach. Copyright © 2017 John Wiley & Sons, Ltd. [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]

This paper is concerned with the problem of stochastic stability analysis for a class of genetic regulatory networks with Markovian jump parameters and time-varying delays. A delay-dependent stability criterion is derived by using a novel mode-dependent Lyapunov functional. The derived stability criterion is expressed in terms of linear matrix inequalities and is less conservative than the existing ones in the literature. A numerical example is provided to demonstrate the effectiveness of the proposed stability criterion. Copyright © 2011 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society [ABSTRACT FROM AUTHOR]

A well-known control system that can reduce the adverse effects of disturbances is the disturbance observer. Whenever we apply a disturbance observer, the disturbance frequency should be known and constant. However, since in many cases of industrial systems the disturbance frequency is varied in some frequency spectrum, it may be difficult to reduce the adverse effect of such disturbances by use of the traditional disturbance observer. Therefore, we have proposed a disturbance observer which can handle frequency variation (DOFV). However, in order to apply DOFV we must measure the disturbance frequency in real time. Therefore, a frequency estimation scheme is required in order to apply DOFV. In this paper, a method for the design of a disturbance attenuation system that can handle frequency variation is proposed. The main idea of this design method is to combine DOFV with a frequency estimator that can estimate the disturbance frequency in real time. Even though the proposed disturbance attenuation system is a low-degree and low-gain controller, it has excellent steady-state disturbance attenuation performance. Numerical simulations and experiments show the usefulness of the proposed disturbance attenuation system. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 175(2): 46-53, 2011; Published online in Wiley Online Library (). DOI 10.1002/eej.21073 [ABSTRACT FROM AUTHOR]

This paper presents a novel feedforward compensation for the fast and precise positioning control in mechatronic systems. The proposed compensator is designed considering the frequency shaping in control input to suppress the residual vibration, under the constraint of a specified number of steps in position reference. A two-degree-of-freedom positioning controller with the proposed feedforward compensation can ensure the required settling performance with the specified number of steps regardless of the positioning amplitude in reference. The effectiveness of the proposed approach has been verified by numerical simulations and experiments using a prototype of galvano scanner. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 175(2): 54-62, 2011; Published online in Wiley Online Library (). DOI 10.1002/eej.21084 [ABSTRACT FROM AUTHOR]

Coxian phase-type distributions are a special type of Markov model that can be used to represent survival times in terms of phases through which an individual may progress until they eventually leave the system completely. Previous research has considered the Coxian phase-type distribution to be ideal in representing patient survival in hospital. However, problems exist in fitting the distributions. This paper investigates the problems that arise with the fitting process by simulating various Coxian phase-type models for the representation of patient survival and examining the estimated parameter values and eigenvalues obtained. The results indicate that numerical methods previously used for fitting the model parameters do not always converge. An alternative technique is therefore considered. All methods are influenced by the choice of initial parameter values. The investigation uses a data set of 1439 elderly patients and models their survival time, the length of time they spend in a UK hospital. [ABSTRACT FROM AUTHOR]

The purpose of this paper was to construct perfect samplers for length-interacting Arak–Clifford–Surgailis polygonal Markov fields in the plane with nodes of order 2 ( V-shaped nodes). This is achieved by providing for the polygonal fields a hard core marked point process representation with individual points carrying polygonal loops as their marks, so that the coupling from the past and clan of ancestors routines can be adopted. [ABSTRACT FROM AUTHOR]

The negative refraction phenomenon in electromagnetic band gap (EBG)-like structures is studied. It is found that the conventional “unit-cell” approach for calculating bandgap properties is not sufficient for predicting negative refraction. In this paper, we present an analysis of EBG-like structures using the “entire-cell” concept in order to consider how spatial-harmonics effects can enhance negative refraction prediction. The results obtained using numerical simulation show good agreement with the theory. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 258–261, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20110 [ABSTRACT FROM AUTHOR]

In this paper, we give statistical analyses and simulation studies on the Lyapunov exponents estimated from noisy chaotic time series. Through the Jacobian estimation approach, the asymptotic distribution of the estimated Lyapunov exponents are studied and characterized from the observed noisy chaotic time series. Theoretical results are visualized and verified by numerical simulations. [ABSTRACT FROM AUTHOR]

Recently, simulation has become important in the field of acoustics. As an acoustic simulation method, the FDTD (Finite-Difference Time-Domain) method has been proposed. However, when this method is applied to a large-scale propagation analysis such as indoor acoustic propagation, the phase error cannot be neglected and causes a problem in the analysis. Therefore, a highly accurate method of analysis that can reduce the phase error is strongly desired. In the present paper, a three-dimensional FDTD(2, 4) method with second- and fourth-order accuracy in time and space is formulated as a highly accurate method of analysis. Also, the numerical dispersion and stability condition, which are important for understanding the characteristics of the method, are derived. It is demonstrated that the present method provides much greater accuracy than the FDTD method. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(11): 30–37, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10076 [ABSTRACT FROM AUTHOR]

In this paper, we present a method based on reciprocity which can transmit and receive a baseband wide-bandwidth signal without distortion. The time-domain combined field integral equation (TD-CFIE) is used to get the simulation results. Numerical results are presented, which show the validity of the presented methodology. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 359–362, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11060 [ABSTRACT FROM AUTHOR]

Summary This paper introduces a multivariate parallelogram that can play the role of the univariate quantile in the location model, and uses it to define a multivariate trimmed mean. It assesses the asymptotic efficiency of the proposed multivariate trimmed mean by its asymptotic variance and by Monte Carlo simulation. [ABSTRACT FROM AUTHOR]

Generally, in image segmentation or object extraction, the edge image of the target object has a substantial effect on the extraction accuracy. In this paper, we focus on the characteristics of the currents flowing in an electrical circuit and propose a technique to interpolate and enhance the edges of a still image by simulating this circuit behavior and apply this technique to image segmentation. The proposed technique constructs a resistor circuit by mapping the edge intensity of each point in the edge image to a resistance, applies a suitable voltage to this circuit, and determines the distribution of the flowing current. Based on the property that the current concentrates in the path that minimizes the sum of the resistances, the current distribution that was obtained is inversely transformed again into the edge intensities in order to enhance weak edges and interpolate broken edges. In several experiments, the proposed technique produced better results than other edge interpolation and enhancement techniques. And when used with the watershed algorithm, highly accurate segmentation was obtained. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(9): 22–33, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10085 [ABSTRACT FROM AUTHOR]

Electro- and magnetorheological fluids are smart, synthetic fluids changing their viscosity from liquid to semi-solid state within milliseconds if a sufficiently strong electric or magnetic field is applied. When used in suitable devices, they offer the innovative potential of very fast, adaptively controllable interfaces between mechanical devices and electronic control units. This paper gives an overview on the basic properties of electro- and magnetorheological fluids and discusses various phenomenological models for whole devices and their applications. Numerical simulation results are presented for the passive suspension of a quarter vehicle model. [ABSTRACT FROM AUTHOR]

In this paper, the integral equations (guided-mode extracted integral equations) of a near field optics CAD proposed earlier are extended for a two-dimensional near field optics circuit using an aperture probe coated with metal. As a specific example, an aperture-probe manipulator with a two-dimensional configuration is chosen. In particular, a derivation of the boundary integral equation is described in detail for the incident TM mode, in which a simple extension of the previous results is not possible. The validity and effectiveness of the proposed integral equations are demonstrated by simulation using the boundary element method. It is shown that an attractive force directed toward the aperture is exerted on an infinitesimal dielectric cylinder placed near the aperture. The characteristics of the aperture probe coated with metal are compared in detail with those of the uncoated probe reported earlier. © 2000 Scripta Technica, Electron Comm Jpn Pt 2, 83(9): 32–41, 2000 [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]

In this paper, we address mainly 2 important issues, namely, characterizing co-channel interference and enforcing a minimum distance between femtocell base stations (FCBSs) for reusing resources in FCBSs deployed in a 3-dimentional multi-floor building. Each floor is modeled as a group of square-grid apartments, with one FCBS per apartment. We propose a simple yet reasonable analytical model by using planar-Wyner model for intra-floor interference and linear-Wyner model for inter-floor interference modeling in a 3-dimensional multi-floor building to derive a minimum distance between co-channel FCBSs for optimization constraints, namely, link level interference, spectral efficiency, and capacity. As opposed to orthogonal resource reuse and allocation (ORRA) where resources are reused once, using the proposed model, we develop 2 strategies for reusing resources more than once, that is, non-ORRA, within a multi-floor building. An algorithm of the proposed model is developed by including an application of the model to an ultra-dense deployment of multi-floor buildings. With an extensive numerical analysis and system level simulation, we demonstrate the capacity outperformance of non-ORRA over ORRA by manifold. Further, with a fairly accurate yet realistic estimation, we show that the expected spectral efficiency of fifth-generation networks can be achieved by applying the proposed model to an ultra-dense deployment of FCBSs. [ABSTRACT FROM AUTHOR]

In this paper, a protocol and a control law are designed for a single robot so that a team of such robots can interact and cooperate to reach the displacements from an eligible reference formation. Each robot is equipped with displacement sensors of limited sensing ranges. Communication channels are assumed to be unavailable to the team, and each robot works in stealth mode. The team is scalable such that new robots can be recruited, and existing robots can be dismissed. In order for the team size to be scalable, the extended formation based on relative displacement is established as the reference formation. Thus, using the extended formation as a reference, the control law and the protocol could be flexible. As potential conflicts deflect the robot team from the desired formation, the control law is designed to expose the conflicts to the involved neighboring robots such that the protocol can resolve them. A numerical example is given to illustrate how an extended formation is designed, and a simulation example is conducted to demonstrate the performance and merits of the proposed techniques. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper presents the first method that enables the fully automatic generation of triangular meshes suitable for the so-called non-uniform rational B-spline (NURBS)-enhanced finite element method (NEFEM). The meshes generated with the proposed approach account for the computer-aided design boundary representation of the domain given by NURBS curves. The characteristic element size is completely independent of the geometric complexity and of the presence of very small geometric features. The proposed strategy allows to circumvent the time-consuming process of de-featuring complex geometric models before a finite element mesh suitable for the analysis can be produced. A generalisation of the original definition of a NEFEM element is also proposed, enabling to treat more complicated elements with an edge defined by several NURBS curves or more than one edge defined by different NURBS. Three examples of increasing difficulty demonstrate the applicability of the proposed approach and illustrate the advantages compared with those of traditional finite element mesh generators. Finally, a simulation of an electromagnetic scattering problem is considered to show the applicability of the generated meshes for finite element analysis. ©2016 The Authors. International Journal for Numerical Methods in Engineering published by John Wiley & Sons Ltd. [ABSTRACT FROM AUTHOR]

Voltage instability is now under intensive study in Japan, and some dynamic methods for analyzing voltage collapse have already been presented. However, the suitability of load models used in the methods and the generality of the results have not been verified. In this paper, useful voltage collapse data acquired in real power systems are presented. The measured data are compared with the result of dynamic digital simulation to verify the suitability of an induction motor load model. In the latter half of this paper, dynamic simulations of voltage collapse with consideration of generator dynamics are carried out. An interconnected power model system with 10 nodes is analyzed. The generality of basic characteristics concerning voltage collapse which have already been obtained without considering generator dynamics is verified by such simulations. [ABSTRACT FROM AUTHOR]

This paper describes the basic items needed for design and simulation of optical integrated circuits and analysis tools for optical waveguides. Because the finite element method and beam propagation method are emphasized, the scalar wave approximation (which has been extensively used) is used in the discussion. In addition, using examples of analyses on various optical integrated circuits, the design and simulation technologies for optical integrated circuits will be introduced. [ABSTRACT FROM AUTHOR]

Differential PCM (DPCM) has often been used for encoding of images, but its efficiency is very poor at low transmission rates. Discussion of DPCM is based on an autoregressive (AR) model which is causal In the case of raster scan sampling. However, originally, images do not satisfy causality in this sense, and a better description of the two-dimensional image Information can be obtained by an interpolative model representing the relations between neighboring pixels. This paper proposes a two-dimensional interpolative DPCM which is based on such a model. This method has the following special feature: if the output samples of a DPCM process based on a causal AR model are regarded as intermediate decoded values, then the final decoded values are yielded by a filtering process based on an Interpolative model. The results of simulation using actual images demonstrate SN ratio improvement at a low bit rate (1 bit/pel) and also the stability of encoding characteristics in the case of quantitative step-size variations. It is shown that fixing of the prediction and interpolation coefficients results only in slight deterioration. [ABSTRACT FROM AUTHOR]

In the analysis of nonpersistent CSMA-CD protocol by Tobagi [1] et al., matrix computation is required. Hence, the computation time and required memory size increase with the number of stations and, moreover, under heavy load, the results become inaccurate. This paper presents an analysis of a nonpersistent CSMA-CD in which the matrix computations are not used and the slot size can be chosen arbitrarily small. The proposed analysis method requires less computational time and memory size. The analytical result for the performance under heavy load agrees well with the simulation result. [ABSTRACT FROM AUTHOR]

The charge simulation method has the Following characteristics compared with other approximate methods for the scattering problems: (1) Only the zeroth and first-order Hankel functions are used; (2) no processing of the singularities on the boundary is needed; (3) no numerical integration is necessary. As a result, it is an extremely simple method. However, the arrangements of the sources and contour points are arbitrary and such arrangements affect the accuracy of the approximate solutions. Previously, the source arrangements by the boundary contractions have been used in the charge simulation method. This choice provides good results if the shape of the scatterer is close to a circle or is a circle itself. The accuracy becomes poorer as the shape deviates more from the circle. Also, it is not possible to determine beforehand the arrangement that provides the best result. Hence, the boundary contraction is an important arrangement method. In this paper, arrangement of the sources and contour points is determined by means of the conformal mapping that transforms the boundary to a circle. Numerical calculations have been performed for typical convex shapes. It is found that the charge simulation method based on the present arrangement has the following properties. It exhibits much better accuracy than the arrangement by boundary contraction. The arrangement minimizing the error is found from the conformal mapping. Scatterers with edges on the boundary cannot be analyzed. [ABSTRACT FROM AUTHOR]

An adaptive mesh refinement scheme in the finite element method is presented in this paper. The new criterion Bdiff for adaptive refinement is tested for its validity. A technique for approximating curved boundaries employing the concept of triangle subdivision in conjunction with Delauney triangulation is also considered, so that the mesh produced is optimal. The implementation of the adaptive mesh refinement criterion in conjunction with the proposed technique of including the curved boundaries in the finite element model is described in detail and several examples of its application are given by way of illustration. [ABSTRACT FROM AUTHOR]

This paper develops an endogenous growth model having a progressive income tax structure in which heterogeneous agents, who differ in terms of their rates of time preference, supply labor elastically. We analyze the dynamic adjustment to an increase in progressivity and show that the economy will converge to an equilibrium growth path with nondegenerate distributions of both income and wealth. The role of the endogeneity of labor supply is emphasized and shown to have a major impact on the nature of the transitional path, as a result of the impact of the progressive tax on agents' work incentives. Our theoretical analysis is supplemented with, and supported by, numerical simulations, which generally match the empirical evidence rather closely. We also show that the responses of the different income groups contrast sharply from one another so that focusing on the economy-wide average provides an incomplete picture. [ABSTRACT FROM AUTHOR]

Recently, an effective and powerful approach for simulating seismic wave propagation in elastic media with an irregular free surface was proposed. However, in previous studies, researchers used the periodic condition and/or sponge boundary condition to attenuate artificial reflections at boundaries of a computational domain. As demonstrated in many literatures, either the periodic condition or sponge boundary condition is simple but much less effective than the well-known perfectly matched layer boundary condition. In view of this, we intend to introduce a perfectly matched layer to simulate seismic wavefields in unbounded models with an irregular free surface. We first incorporate a perfectly matched layer into wave equations formulated in a frequency domain in Cartesian coordinates. We then transform them back into a time domain through inverse Fourier transformation. Afterwards, we use a boundary-conforming grid and map a rectangular grid onto a curved one, which allows us to transform the equations and free surface boundary conditions from Cartesian coordinates to curvilinear coordinates. As numerical examples show, if free surface boundary conditions are imposed at the top border of a model, then it should also be incorporated into the perfectly matched layer imposed at the top-left and top- right corners of a 2D model where the free surface boundary conditions and perfectly matched layer encounter; otherwise, reflections will occur at the intersections of the free surface and the perfectly matched layer, which is confirmed in this paper. So, by replacing normal second derivatives in wave equations in curvilinear coordinates with free surface boundary conditions, we successfully implement the free surface boundary conditions into the perfectly matched layer at the top-left and top-right corners of a 2D model at the surface. A number of numerical examples show that the perfectly matched layer constructed in this study is effective in simulating wave propagation in unbounded media and the algorithm for implementation of the perfectly matched layer and free surface boundary conditions is stable for long-time wavefield simulation on models with an irregular free surface. [ABSTRACT FROM AUTHOR]

Orthogonal frequency-division multiplexing (OFDM) suffers from spectral nulls of frequency-selective fading channels. Linear precoded (LP-) OFDM is an effective method that guarantees symbol detectability by spreading the frequency-domain symbols over the whole spectrum. This paper proposes a computationally efficient and lowcost implementation for discrete Hartley transform (DHT) precoded OFDM systems. Compared to conventional DHT-OFDM systems, at the transmitter, both the DHT and the inverse discrete Fourier transform are replaced by a one-level butterfly structure that involves only one addition per symbol to generate the time-domain DHTOFDM signal. At the receiver, only the DHT is required to recover the distorted signal with a single-tap equalizer in contrast to both the DHT and the DFT in the conventional DHT-OFDM. Theoretical analysis of DHT-OFDM with linear equalizers is presented and confirmed by numerical simulation. It is shown that the proposed DHT-OFDM system achieves similar performance when compared to other LP-OFDMs but exhibits a lower implementation complexity and peak-to-average power ratio. [ABSTRACT FROM AUTHOR]

In this paper, the selective illumination approach is adopted to separately extract the shunt resistance of the individual subcells belonging to a tandem cell. The method relies on simple theoretical considerations and is based on the measurement of the current-voltage characteristic of the tandem cell by alternately keeping one of the subcells under dark conditions. Numerical simulations are employed to support the reliability of the technique, which is experimentally tested on micromorph devices deposited onto glass covered by a V-shaped transparent conducting oxide and subject to different thermal treatments. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this paper, we present a fast convergent technique that can generate an accurate FDTD simulation result using a relatively coarse mesh for PEC planar structures if an effective factor is properly selected. The effective size of a PEC is about one half cell smaller than its actual dimensions regardless of cell size. A microwave patch antenna and a low pass filter are used to validate the proposed scheme. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 39: 17–19, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11113 [ABSTRACT FROM AUTHOR]

SUMMARY A fifth-order accurate multistep weighted essentially non-oscillatory (WENO) scheme is constructed in this paper. Different from the traditional WENO schemes, which are designed to have (2 r−1)th order accuracy in the smooth regions directly from r candidate stencils, the new scheme is constructed through ( r−1) weighting steps. In each step, only two neighboring stencils are used to construct the intermediate fluxes (or the final flux), which are only one order higher than the fluxes obtained from the previous step. Henrick's mapping function is used in each step to satisfy the sufficient condition of fifth-order convergence for a fifth-order WENO scheme; hence, the new scheme is fifth-order accurate in smooth regions. The distinctive advantage of the new scheme is that it can improve the accuracy by one order higher than the traditional WENO schemes at transition points (connecting a smooth region and a discontinuity point); and hence, it improves the accuracy in the regions near discontinuities. Numerical examples show that the new scheme is robust and is less dissipative than the traditional fifth-order WENO schemes. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]