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Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 23 for “"constraint equations"”.
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Radiation field for Einstein vacuum equations
… behavior of solutions to the Einstein Vacuum equations, which are close to Minkowski space, at null infinity. By imposing harmonic gauge, the Einstein Vacuum equations reduce to a system of quasilinear wave equations on R"j". We show that if the space dimension n > 5 the Moller wave operator …
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Partially Covariant Quantum Theory of Gravitation
… by imposing a weaker form of the quantum constraint equations than that of the conventional theory. In order to justify this approach it is necessary to show that, in spite of the weak form of the constraint equations, the Einstein theory is recovered in the classical limit . A partial …
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Analysing Dynamic Processes in Range Data Sequences
… For the velocity estimation novel differential constraint equations for the depth and intensity data are introduced. These constraint equations are then combined in a general total least squares parameter estimation framework. It turns out that this method can be used for a much broader class of …
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Schur's Complement and Discontinuous Galerkin Methods for Domain Decomposition Solvers and Plasticity and Interface Evolution Analyses
… Galerkin schemes is that they do not introduce constraint equations and their resulting Lagrange multiplier fields as done in mixed and mortar methods. Without loss of generality we demonstrate our method by analyzing the Stefan problem of solidification.
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The Cauchy problem and the initial data problem in effective theories of gravity
… theories with second-order equations of motion. A subset of these theories can be motivated by effective field theory considerations and hence they could describe strong-field deviations from general relativity. In particular, the effects of some Horndeski theories might be …
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A study of integrability conditions for irrotational dust spacetimes
… conditions for fluid solutions of the field equations of general relativity. The exact non-linear dynamic equations for a generic irrotational dust spacetime are consistent. To analyse conditions characterizing pure gravity waves, linearization instability in general relativity and …
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A covariant approach to gravitational lensing
… be better understood through the propagation and constraint equations in the direction of the congruence. Thus, we derive these equations after describing the geomentry of a ray. We also derive a general from of the null geodesic deviation equation (NGDE) which can be used in any given space-time. …
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Oppenheimer-Snyder Collapse in the BSSN Formalism
… we find semi-analytic solutions to the constraint equations at linear order in angular momentum. In addition, we develop a Mathematica simulation code for modeling of spherical vacuum systems using the BSSN formalism. Diagnostics provide comparison of our results with theoretical …
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Optimal Slewing of a Constrained Telescope Using Seventh Order Polynomial Input Torques
… system is governed by nonlinear angular momentum equations of motion. This paper presents a method for slewing a telescope in space with a gimbaled sensor attached to a nominally non-rotating spacecraft using two seventh order polynomial input functions to characterize torques. To accomplish this …
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A study of solutions and perturbations of spherically symmetric spacetimes in fourth order gravity.
… f(R) theories of gravity and present the general equations for these theories. We investigate the problem of matching different regions of spacetime, shedding light on the problem of constructing realistic inhomogeneous cosmologies in the context of f(R) gravity. We also study strong lensing in …
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Transport theory for scalar quarks and gluons
… detailed the calculations of the transport and constraint equations for a theory of scalar quarks and gluons with self-interactions. Special care has been taken in particular in understanding how the transport equation, taken on its own, leads to a Boltzmann-like equation when considered in the …
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Theory and Application of a Class of Abstract Differential-Algebraic Equations
… of solutions for ordinary differential-algebraic equations (DAEs). Because of the geometric and operator-theoretic aspects of this particular method, it can be extended to the case of infinite-dimensional abstract DAEs. For example, partial differential equations (PDEs) are often formulated as …
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Improved Collocation Methods With Application to Six -Degree -of -Freedom Trajectory Optimization
… for the use of this method which generates constraint equations, gradients, and the system Jacobian for problems of arbitrary size. This code constitutes a much-improved tool for aerospace vehicle design but has application to all two-timescale optimization problems.
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Development and application of hybrid finite methods for solution of time dependent maxwell's equations
… of such weak-instability using divergence-free constraint equations is proposed. The method is directly extended to eliminate appearance of non-physical modes in the eigenvalue modeling of electromagnetic resonators. An efficient implementation of the constraint equation using tree-cotree …
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Influence of soil parameters on the motion of rocking walls
… the finite element model of the soil, applying constraint equations and inserting bilinear springs in the interface between the rocking wall and the soil. The dynamic response will be simulated with an implicit, unconditionally stable time domain method. Results show that the motion of the …
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Integral aerodynamic-structural-control wing design
… subject to divergence and control deflection constraints. The results of this study indicated that while the integrated approach produced a better design than the sequential approach, the difference was minimal. In the second example, a forward-swept composite wing is designed for a high …
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EFFICIENT SOLUTION METHODS FOR NONLINEAR FINITE ELEMENT ANALYSIS (DESIGN, GEOMETRIC MATERIAL, POST-BUCKLING, STRUCTURAL, MECHANICS, NUMERICAL).
… are developed for the nonlinear finite element equations, resulting from the discretization of governing incremental equations of equilibrium. The equations of equilibrium in the total Lagrangian formation are derived, based on continuum mechanics principles and by invoking the principle of …
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Semi-Analytical Model to Study Vibrations of High-Speed, Rotating Axisymmetric Bodies Coupled to Other Rotating/ Stationary Structures
… its deflection as well as external forces, constraints, and supports acting on the body are allowed to be asymmetric. These asymmetric elements can be stationary or rotating. The model includes Coriolis and centripetal effects. The prestress (or geometric) stiffness matrix that arises from …
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State space modeling of differential-algebraic systems using singularly perturbed sliding manifolds
… of dynamic systems in terms of differential equations ·and algebraic constraints provides a systematic framework that is well suited for object oriented modeling of thermo-fluid systems. In this approach, differential equations are used to describe the evolution of subsystem states and …
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Evaluating the feasibility of an intermodal transportation facility in Chattanooga
… the profit to the facility. The different constraints involved in the model and the constraint equations are presented. Also in order to utilize the LP model, and to understand the behavior of the model for different situations, seven different cases were run for the LP model. The results …
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