Peter Russer has pioneered the unified derivation of numerical algorithms in computational electromagnetics from Maxwell's equations with the general method of moments. While he focused mainly on the derivation of...
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Peter Russer has pioneered the unified derivation of numerical algorithms in computational electromagnetics from Maxwell's equations with the general method of moments. While he focused mainly on the derivation of specific time domain algorithms, such as finite difference time domain (FDTD) and transmission line matrix (TLM) methods, he always cultivated a broad perspective of field modeling to avoid the inherent limitations of specialization. It is in this spirit that this contribution to the special issue at the occasion of Peter Russer's 65(th) birthday has been written. It demonstrates in simple terms that finite element. finite difference, finite integration and transmission line matrix (TLM) models, approaches so very different at first glance, can not only he derived from Maxwell's equations with the same general method of moments. out also lead to identical discrete field-solving algorithms when the same spatial discretization is used.
作者：
Josyula, EBailey, WFUSAF
Res Lab AFRL VAAC Wright Patterson AFB OH 45433 USA USAF
Inst Technol AFIT ENP Wright Patterson AFB OH 45433 USA
Evaluates the kinetics of vibration-dissociation coupling for hypersonic blunt-body flow. Shock-standoff distance; Airflow simulation past a blunt body; Depletion effects from the upper vibrational levels; Possible ef...
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Evaluates the kinetics of vibration-dissociation coupling for hypersonic blunt-body flow. Shock-standoff distance; Airflow simulation past a blunt body; Depletion effects from the upper vibrational levels; Possible effects of rotational energy on the dissociation mechanism.
Different extrapolation strategies are presented for the construction of starting values in implicit Newmark time-stepping schemes used for the solution of the electromagnetic wave equation. The implicit character of ...
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Different extrapolation strategies are presented for the construction of starting values in implicit Newmark time-stepping schemes used for the solution of the electromagnetic wave equation. The implicit character of this schemes implies the solution of a system of linear equations in each time step. The choice of a good start value derived from the extrapolation of the equation system is shown to improve the convergence of the iterative conjugate gradient solver which reduces the total simulation time.
A simple model is used to consider the effects of the atmospheric density gradient on the swinging motion of tension-controlled tethered subsatellites in LEO, as well as to design a suitable control system for the sat...
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A simple model is used to consider the effects of the atmospheric density gradient on the swinging motion of tension-controlled tethered subsatellites in LEO, as well as to design a suitable control system for the satellite. It is established that effects on the stability of a controlled system are more severe than on an uncontrolled one; a control system designed without taking the atmospheric density gradient into account can greatly destabilize the closed-loop system. (O.C.)
The computation of transonic flows using potential theory is fairly commonplace, although the computation cost is still high and, consequently, considerable effort has been expended in trying to reduce the total costs...
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The computation of transonic flows using potential theory is fairly commonplace, although the computation cost is still high and, consequently, considerable effort has been expended in trying to reduce the total costs of the necessary calculations. One approach toward cost reduction is the development of the transonic perturbation theory. This note presents an investigation into the behavior of the transonic perturbation theory when shock waves vanish. It is shown that, when shock waves vanish, a piecewise application of the perturbation theory is necessary at that point since the equation set is discontinuous there. It is also shown that the range of transonic solutions can be constructed if the incompressible solutions and one transonic solution are known.
A study of the time-dependent effects of interfacial layers and matrices on the mechanical properties of laminated composites with various fiber-matrix volume fractions. The study considered elastic and viscoelastic ...
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A study of the time-dependent effects of interfacial layers and matrices on the mechanical properties of laminated composites with various fiber-matrix volume fractions. The study considered elastic and viscoelastic constitutive relations for the matrix. An analysis of the effects of interphase mechanical properties was performed from a microscopic perspective on overall laminated composite properties using finite element methods.
Provides information on a study which examined the evolution strategies for the optimization of active control parameters for enhancing jet mixing. Information on evolution strategies; Optimized excitation of compress...
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Provides information on a study which examined the evolution strategies for the optimization of active control parameters for enhancing jet mixing. Information on evolution strategies; Optimized excitation of compressible jets; Details on the incompressible vortex model; Conclusions.
In this paper we present the solution to the algebraic Riccati-type equation of the state-dependent noise linear-quadratic optimal control problem in terms of algebraic Lyapunov iterations. By properly initializing th...
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In this paper we present the solution to the algebraic Riccati-type equation of the state-dependent noise linear-quadratic optimal control problem in terms of algebraic Lyapunov iterations. By properly initializing the sequence of algebraic Lyapunov iterations we got monotonic convergence from above to the positive-definite stabilizing solution of the algebraic Riccati-type equation (the solution that represents the optimal solution to the corresponding optimal control problem). The proposed algorithm requires much less computational efforts than those previously used to solve the same problem. (C) 1999 Elsevier Science Ltd. All rights reserved.
A classic result for the two-point boundary value problem in the framework of Keplerian motion allows the derivation of a novel parametrization of orbits passing through two arbitrary points in space. In particular, i...
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A classic result for the two-point boundary value problem in the framework of Keplerian motion allows the derivation of a novel parametrization of orbits passing through two arbitrary points in space. In particular, it is shown that these orbits *** unambiguously identified in terms of their eccentricity vector component in the direction perpendicular to the chord connecting the two points. The parametrization, in terms of transverse eccentricity component, lends itself to an efficient and intuitive solution algorithm for the classical Lambert problem, that is, the determination of the orbit that connects two points in space in a prescribed time. Although, from the computational point of view, the resulting numerical procedure does not provide advantages over the elegant Battin's method, its derivation is considerably less demanding from the mathematical standpoint and physically more intuitive.
The paper presents an algorithm for use with the discrete element method to study possible strain-gradient effects in granular materials. The algorithm produces an intentionally non-uniform displacement pattern by app...
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The paper presents an algorithm for use with the discrete element method to study possible strain-gradient effects in granular materials. The algorithm produces an intentionally non-uniform displacement pattern by applying external (body) forces to the particles within a simulated granular assembly. The paper describes a method for adjusting the external forces to attain the intended gross displacement pattern, but while allowing individual particles to be in equilibrium among neighbouring particles. The performance of the algorithm is tested in an example of quasi-static deformation, and the algorithm's performance is measured in three respects. The algorithm is shown to enforce the intended displacement pattern, to allow particles to equilibrate among neighbouring particles, and to produce a smooth distribution of the external forces among particles. Copyright (C) 2003 John Wiley Sons, Ltd.
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