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This research presents a finite element method to analyze the electromechanical coupled field of a hydrodynamic-bearing (HDB) spindle motor of computer hard disk drives considering electromagnetics, thermal analysis, HDB, and rotor dynamics to investigate the coupling effect. Simulation results are verified by the experiments, and it shows that it is essential to include the appropriate coupled fields to predict the performance accurately. This research also investigates the electromechanical characteristics of a HDB spindle motor due to the electromechanical coupling effect. [ABSTRACT FROM AUTHOR]

A novel digitally-actuated shaped micromirror for on-off optical switch applications is described. Reflective static spherical mirrors were designed and fabricated using conventional surface micromachining and the MultiPoly process, a technique for depositing multilayers of LPCVD polysilicon in order to con- trol the overall stress and stress gradient. The resulting mirrors were measured to have radii of curvature of approximately 9 mm in agreement with design predictions. Based upon these static mirrors, an actuatable micromirror (diameter = 500 pm, static radius of curvature = 6.4 mm) was designed for snap action. This mirror was simulated using an electromechanical coupled-field model and fabricated using the MultiPoly process. Its performance was measured dynamically using an interferometer. A curved-to-flat digital actuation of the mirror was successfully achieved with a pull-in voltage of 38 V. [1211] [ABSTRACT FROM AUTHOR]

The generalized 2-D problem of a half-infinite interfacial electrode layer between two arbitrary piezoelectric half-spaces is studied. Based on the Stroh formalism, exact expressions for the Green’s functions of a line force, a line charge and a line electric dipole applied at an arbitrary point near the electrode edge, were prsented, respectively. The corresponding solution for the intensity factors of fields were also obtained in an explicit form. These results can be used as the foundational solutions in boundary element method (BEM) to solve more complicated fracture problems of piezoelectric composites. [ABSTRACT FROM AUTHOR]

This paper studies a class of coupled Van der Pol (CVDP) cellular neural networks (CNNs) that can be realized via a coupled fourth-order circuit with two synaptic currents. The local activity theory, developed by Chua in 1997, is applied to study the CVDP CNN, thereby revealing that the bifurcation diagram of the CVDP CNN has a local activity domain with an edge of chaos, as well as a one-dimensional locally passive domain. Although no chaotic phenomena have been identified in simulations, many complex dynamical behaviors have been observed, such as the co-existence of one-periodic, divergent, and convergent orbits, at the edge of chaos. [ABSTRACT FROM AUTHOR]

Thermal interface materials (TIMs) are used in electronics cooling application to decrease the thermal contact resistance between surfaces in contact. A methodology to determine the optimal volume fraction of filler particles in TIMs for minimizing the thermal contact resistance is presented. The method uses finite element analysis to solve the coupled thermo-mechanical problem. It is shown that there exists an optimal filler volume fraction which depends not only on the distribution of the filler particles in a TIM but also on the thickness of the TIM layer,. the contact pressure and the shape and the size of the filler particles. A contact resistance alleviation factor is defined to quantify the effect of these parameters on the contact conductance with the use of TIMs. For the filler and matrix materials considered--platelet-shaped boron nitride filler particles in a silicone matrix--the maximum observed enhancement in contact conductance with the use of TIMs was by a factor of as much as 9. [ABSTRACT FROM AUTHOR]

We analyze the behavior of some coupled chaotic systems, which are synchronization-like. This phenomenon occurs when all conditional Lyapunov exponents of a system are not negative. Recently, Shuaiet et al. [1997] observed that synchronization can be achieved even with positive conditional Lyapunov exponents. In this paper we review this observation, and, based on this observation, we will see that not only interesting synchronization behaviors occur with positive or zero conditional Lyapunov exponents, but also these behaviors depend on different eigenvalues of the linearized system describing the evolution of the difference between the pair of chaotic systems. [ABSTRACT FROM AUTHOR]

The theory of poroelasticity is extended to include physico-chemical swelling and used to predict the transient responses of normal and degenerate articular cartilage to both chemical and mechanical loading; with emphasis on isolating the influence of the major parameters which govern its deformation. Using a new hybrid element, our mathematical relationships were implemented in a purpose-built poroelastic finite element analysis algorithm (u-π-c fortran program) which was used to resolve the nature of the coupling between the mechanical and chemical responses of cartilage when subjected to ionic transport across its membranous skeleton. Our results demonstrate that one of the roles of the strain-dependent matrix permeability is to limit the rate of transmission of stresses from the fluid to the collagen-proteoglycan solid skeleton in the incipient stages of loading, and that the major contribution of the swelling pressure is that of preventing any excessive deformation of the matrix. [ABSTRACT FROM AUTHOR]

We study systematical detection of the state variables for a quasi-static coupled circuit-field problem, which may consist of several disjoint domains for both field problems and electric networks. We translate the relevant questions about coupling into linear algebraic problems, i.e., use the homology theory. This enables us to express the state variable detection problem with readily programmable and computable concepts. [ABSTRACT FROM AUTHOR]

In this research, a new design to reduce the discontinuities of the pumping forces of the magnetic fluid linear pump (MFLP) is studied. Continuous pumping of the newly designed MFLP by using ac current with a phase shift increases pumping efficiency and reduces the pumping shock. Forming shapes of the magnetic fluid at the intermediate state are computed and compared to measurement. Because the back flow of the fluid is reduced remarkably, 4-yoke ac driving is more efficient than 7-yoke dc driving, The size, weight, and pumping discontinuity is also reduced. [ABSTRACT FROM AUTHOR]

Despite worldwide efforts and many recent advances, electrical machine modeling using finite elements can be computationally very expensive, especially if three-dimensional models are required. This contribution is concerned with speeding up the process. Some examples of line start permanent magnet machines and induction motors are provided. [ABSTRACT FROM AUTHOR]

Numerical instability occurs in analyses of an electro- magnetic and structural coupled problem or a magnetic damping problem when the matrix equations of structure and eddy cur- rent are solved alternately. In this paper, an augmented staggered method is proposed for the coupled analysis. The stability of this method is demonstrated for the magnetically damped vibration by finite element analyses. According to the characteristic equation obtained from the recurrence relation of this time integration scheme, it is confirmed that this method is unconditionally stable for the intensity of magnetic field and the size of time increment. [ABSTRACT FROM AUTHOR]

This paper describes a three-dimension (3-D) over- lapping finite-element scheme for modeling movement in electro- magnetic devices, which results in a continuously changing air gap. The method uses separate finite-element meshes to model the individual parts of the device. These meshes are coupled together electromagnetically on an interface using the Lagrange sliding interface technique. Treatments of overlapping mesh volumes are also discussed. The method was used to model a jumping eddy-current disc experiment. The results of the simulations compared favorably with measurements. [ABSTRACT FROM AUTHOR]

This work analyzes the use of different types of finite elements (Lagrange, hierarchic, and Hermite) in order to improve the calculation accuracy when they are submitted to distortion due to the movement. The moving band technique is used with different elements in thin air gap machines. Results are shown for comparing the performance of Lagrange, hierarchic, and Hermite elements. [ABSTRACT FROM AUTHOR]

The Seul–Andelman membrane is a system of two coupled fields: the composition φ of one of the two (A and B) constitutive molecules, and the height profile h of the flexible membrane. The free energy of the system consists of two parts. The first part is the usual Ginzburg–Landau free energy of φ; the second part is attributed to the bending of the membrane and the coupling of φ to h. The coupling term models the tendency that the two molecular constituents display an affinity for regions of the membrane of different local curvature. In a particular parameter range we prove the existence of the soliton-stripe pattern, using the Γ-limit theory in perturbative variational calculus. This pattern, modeled by one-dimensional local minimizers of the free energy of the system, consists of A-rich and B-rich stripes covering the membrane, delineated by sharp domain walls. The optimal spacing between domain walls is determined from the global minimizer of the Γ-limit. [Copyright &y& Elsevier]

This paper deals with the study of high speed switched reluctance motors and their pre-dimensioning. The pre-dimensioning is tackled towards the inductance profile and the torque generation. Then, the power density is assessed in terms of three defined fundamental parameters, each depending on electrical, mechanical and geometrical design of the motor. The mechanical limitations studied are the centrifugal stresses and the vibratory behavior of the motor. A shape optimization of the rotor teeth leans then on a coupled magnetic-mechanic coupled problem,, solved with finite elements simulations. After that, mechanic, magnetic and copper losses are given in terms of the rotor external volume so as to assess the weight of each heat source in the global motor heating. Once all the losses are linked to temperature, a criterion to improve the ability to develop a high speed motor is finally proposed. [ABSTRACT FROM AUTHOR]

In this research, an identification method for joint parameters has been developed by using the substructure synthesis method and frequency response functions (FRFs). A matrix form for the joint model was proposed. Identifying the joint parameters of a beam screwed down at one of its end was conducted. Only two measurement points were used in the experiment. The simulated results of the FRFs of the constrained beam with the properly identified joint parameters agree with the experimental results very satisfactorily. The accuracy of the identified results is strongly sensitive to the parameters. The rotational stiffness of the screw joint is identified to be located in the sensitive region, so the identified result of the rotational stiffness is very good. However, the less accurate results for the translational stiffness located in the insensitive region do not affect apparently the accuracy of the simulated results. The cross-coupled term between the translational and rotational stiffness in the joint model was identified, which greatly improved the accuracy of the simulated FRFs in higher frequency regions. [Copyright &y& Elsevier]

Studies the influence of gravity waves on the sodium layer by using a linear photochemical-dynamical coupling gravity wave model. Details of the model, which includes the background photochemistry and the photochemical reactions in the sodium layer; Calculation of amplitude and phase difference in the sodium mixing ratio to gravity waves; Indication that the lower part of the sodium layer is most sensitive to gravity waves; How temperature fluctuation is linked with in phase and out of phase conditions of the sodium mixing ratio.

First, the general solution for transversely isotropic magnetoelectroelastic media is given concisely in form of five harmonic functions. Second, the extended Boussinesq and Cerruti solutions for the magnetoelectroelastic half-space are obtained in terms of elementary functions by utilizing this general solution. Third, the coupled fields for elliptical Hertzian contact of magnetoelectroelastic bodies are solved in smooth and frictional cases. At last, the graphic results are presented. [Copyright &y& Elsevier]

Presents a study that investigated changes in the magnetic field along the axial direction when simulating the operations of electric machines using a multislice circuit-field coupled finite element method. Background on basic equations in the field regions; Details of coupling with the external circuits; Results and implications.

Presents a study that analyzed the system of coupled equations describing an electrostatic painting device. Description of the behavior of the device; Comparison of time integration schemes for the steady-state solution of the convection equation; Results and implications.

This study compares numerical modeling results of contaminant transport using a multi-component coupled reactive mass transport model and a distribution coefficient (Kd)-based transport model. The study site is a contaminated groundwater aquifer underneath a uranium mill tailings pond in the western USA. Advective–dispersive–reactive transport is simulated for a 5-year period of intrusion of tailings fluid into the shallow aquifer, followed by flushing with uncontaminated upgradient groundwater for 1600 years. The coupled model shows that groundwater–sediment interactions result in multiple concentration waves, strong interactions among solutes, and chemical heterogeneity in both space and time. As a result, calculated Kd values vary spatially and temporarily. None of these characteristics can be simulated with a Kd-based model. These results illustrate the shortcomings of the Kd approach, the usage of which is prevalent in the regulatory environment. [Copyright &y& Elsevier]

In this work a coupled thermo-mechanical problem of non-homogeneous shells with variable thickness and variable Young modulus (a so-called Timoshenko type model) is considered. The problem is reduced to uniformly correct problem in the form of a first order difference operator equation. In addition, a similar approach can easily be applied to the Kirchhoff–Love model. [Copyright &y& Elsevier]

A fully coupled two-dimensional sub-critical and/or supercritical, free-surface flow numerical model is developed to calculate bed variations in alluvial channels. Vertically averaged free-surface flow equations in conjunction with sediment transport equation are numerically solved using an explicit finite-volume scheme in integral form. The capabilities of the proposed method are first demonstrated by analyzing supercritical flow in an expansion channel. Thereafter, one and two-dimensional applications referring to aggradation and scouring are reported. For each of these test cases, computed results compare satisfactorily with measurements as well as with other numerical solutions. The method is stable, reliable and accurate, although time consuming, handling a variety of sediment transport equations with rapid changes of sediment transport at the boundaries. [ABSTRACT FROM AUTHOR]

Discusses the coupled transient computation of the interacting electromagnetic-thermal fields in electrical energy transducers containing significantly different time constants. Interactions that justify the importance of studying the electromagnetic and thermal behavior of electrical energy transducers; Calculation of the iron and permanent-magnet eddy-current losses; Use of block iteration algorithms in calculating the couple field problem.

In this paper we study the complicated dynamics generated by the planar periodic system z˙=z¯1+eiκt&z.sfnc;z&z.sfnc;2, for 0<κ&les;0.495. We prove the existence of infinitely many (geometrically distinct) periodic solutions with some special properties. [Copyright &y& Elsevier]

Presents a method for modeling magnetoelastic material where magnetic and mechanical phenomena are coupled in consequence of magnetic forces and magnetostriction. Continuum description of magnetoelastic material; Numerical applications of magnetic and mechanical equations; Illustration of the magnetoelastic theory.

Presents an electromagnetic-thermal simulation of microwave heating during curing process of polymer resin. Application of finite-element framework in the simulation; Computational analysis of microwave heating.

The theories of thermopiezoelectricity and magnetoelasticity for micropolar continua have been systematically developed by W. Nowacki. In this paper, the theories are restudied. The reason why they were restricted to linear cases is analyzed. The more general conservation principle of energy, energy balance equation and Hamilton principle of thermopiezoelectricity and magnetoelasticity for micropolar continua are established. The corresponding complete equations of motion and boundary conditions as well as balance equations of energy rate for local and nonlocal micropolar thermopiezoelectricity and magnetothermoelasticity are naturally derived. By means of two new functionals and total variation the boundary conditions of displacement, microrotation, electric potential and temperature are also given. [ABSTRACT FROM AUTHOR]

Driven by the needs of engineered underground systems, the field of rock mechanics is evolving to address the interactions of in situ mechanical, thermal, hydrologic, and chemical processes and their effects on system performance. Important technical issues include understanding how the relevant loads and gradients drive in situ processes; rock mass variability, discontinuity, and heterogeneity; process and parameter scale dependence; and the degree of coupling between processes. Major challenges include scaling information from short-duration laboratory tests up to long-term, full-scale system performance and the lack of experimental investigations or simulations of fully coupled thermal-mechanical-hydrologic-chemical behavior. Technical trends and opportunities that may benefit rock engineering include applied research in reactive geochemistry, information technology for measurement systems, and modeling and monitoring combined in an observational method to improve system performance. [Copyright &y& Elsevier]

We present the first analytical investigation of lag chaos synchronization between two unidirectionally coupled identical time-delayed systems in the case when these systems are governed by two characteristic times: the delay time in the coupling is generally different from the delay time in the coupled systems. Also, for the first time we demonstrate that parameter mismatches can explain the fact that the lag time is equal to the coupling delay. These findings can be helpful to explain coupling-delay lag time in chaos synchronization. [Copyright &y& Elsevier]

An invariant manifold based chaos synchronization approach is proposed in this letter. A novel idea of using only a partial state of chaotic systems to synchronize the coupled chaotic systems is presented by taking into account the inherent dynamic properties of the chaotic systems. The effectiveness of the approach and idea is tested on the Lorenz system and the fourth-order Rossler system. [ABSTRACT FROM AUTHOR]

The network approach to the modelling of complex technical systems results frequently in a set of differential-algebraic systems that are connected by coupling conditions. A common approach to the numerical solution of such coupled problems is based on the coupling of standard time integration methods for the subsystems. As a unified framework for the convergence analysis of such multi-rate, multi-method or dynamic iteration approaches we study in the present paper the convergence of a dynamic iteration method with a (small) finite number of iteration steps in each window. Preconditioning is used to guarantee stability of the coupled numerical methods. The theoretical results are applied to quasilinear problems from electrical circuit simulation and to index-3 systems arising in multibody dynamics. [ABSTRACT FROM AUTHOR]

Presents information on a study which investigated the voltage between the AC-coupled readout strips and the silicon strip implants on a silicon microstrip detector on a high radiation field. Theory of the E-Field breakdown; Deposited energy at different laser intensities; Anticipated charges and voltages in high energy physics applications.

Presents a study which proposed an adaptive scheme for coupled thermo-electromagnetic problems. Use of relaxation scheme in order to prevent divergence; Coupling aspects; Discussion on relaxation principle.

Proposes a systematic definition of coupled problems for a proper classification of these problems and related solution methods. Overview of coupled fields; Factors considered in coupled problems; Classification scheme; Conclusions.

Presents details of coupling circuit equations and motion with two dimensional transient magnetic analysis. Use of finite elements with overlapping shape functions; Torque calculation through Mawell's stress method (MSM); Conclusions.

Present a study on the coupling between physical arc modelling in circuit-breaker and external circuit modeling. Numerical procedures; Results and discussion; Conclusions.

Presents information on a study which developed the marsh plain equations, the coupled field equations for subsurface flow and salinity transport in the continuous saturated/unsaturated flow domain of a tidal wetland. Factors in the development of the equations; Methodology; Results and conclusions.

Investigates a two-dimensional system of nonlocally coupled complex Ginzburg-Landau oscillators numerically. Model; Anomalous spatio-temporal chaos; Spatial correlation function; Noisy on-off intermittency; Multiscaling analysis; Probability distributions of the measures.

Different notions of generalized synchronization of uni-directionally coupled dynamical systems are briefly discussed. An example is given demonstrating that generalized synchronization may not only occur for pairs of different systems but also for identical systems that do not synchronize in the usual sense. [ABSTRACT FROM AUTHOR]

A procedure to predict the occurrence of periodic clusters in a system of globally coupled maps displaying a constant mean field is presented. The method employs the analogy between a system of globally coupled maps and a single map driven by a constant force. By obtaining the asymptotic orbits of the driven map, an associated coupling function can be constructed. This function allows to establish a direct connection between both systems. Some applications are shown. [ABSTRACT FROM AUTHOR]

In this paper, the length scales included both in rate-dependent single phase materials and in coupled problems such as saturated and partially saturated porous media where the viscous terms are introduced naturally by the fluid mass balance equations, are discussed. The viscous effects in the two problems are quite different and the internal length scales hence have different expressions. Also the wave speeds have different relationships with the wave number. [ABSTRACT FROM AUTHOR]