Global ETD Search
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 14 of 14 for “"difference operator"”.
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Difference-operator-based models in statistical signal processing
Difference-operator-based models are an alternative to conventional shift-operator-based models for modeling stationary discrete-time random processes obtained by sampling continuous-time processes, when the sampling rate is rapid relative to the dynamics of the continuous-time process. In this …
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Effects of tool positions on borehole acoustic measurements : a stretched grid finite difference approach
… logging. The first one is a novel finite difference time domain algorithm that features non- uniform grid, wavelet-based difference operator and anisotropic perfectly matched layer. This algorithm reduces numerical reflections and wave distortions introduced by grid change to a minimum by …
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Numerical solutions for a class of singular integrodifferential equations
… integrodifferential equations with a nonatomic difference operator. Our interest in this particular class has been motivated by an application in aeroelasticity. By applying nonconforming finite element methods, we are able to establish convergence for a semi-discrete scheme. We use an ordinary …
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Row Projection Methods for Linear Systems
… matrices arising from the seven point centered difference operator applied to three dimensional elliptic partial differential equations. This approach allows large scale parallelism in the computations, requires only a few extra vector of additional storage, provides good data locality, gives …
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Generalized Kummer congruences and Iwasawa invariants
… character $\chi,\ \Delta\sb{\rm c}$ is the difference operator$$\Delta\sb{\rm c} x\sb{n} = x\sb{n+c} - x\sb{n}\ {\rm and}\ \left\lbrack {p\sp{-1}\Delta\sb{\rm c}\atop j}\right\rbrack$$is a binomial coefficient operator.
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Reliable Decentralized Controller Design for Discrete/continuous-Time, Sampled-Data, and Multirate Systems
… sensors or actuators. The discrete-time divided-difference operator formulation facilitates the solution of three problems: the unification of discrete- and continuous-time results for sampled-data systems, providing a numerical method for solving the decentralized discrete-time design equation; …
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Well-posedness questions and approximation schemes for a general class of functional differential equations
… equations of neutral-type (NFDE) where the difference operator does not have an atom at zero. Equations of this type occur in the modeling of certain aeroelastic control problems and include many singular integro-differential equations. We obtain general necessary and sufficient conditions …
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Analysis of Discrete Fractional Operators and Discrete Fractional Rheological Models
… Monotonicity results on discrete fractional operators and discrete fractional rheological constitutive equations. In the first part of the thesis, we introduce and prove new monotonicity concepts in discrete fractional calculus. In the remainder, we carry previous results about fractional …
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Calculation of wave resistance and elevation of arbitrarily shaped bodies using the boundary integral element method
… the use of an one-sided upstream 4-point finite difference operator for the free surface condition. Wave elevations are computed using the linearized free surface condition. In this study two different bodies were considered: a submerged spheroid and a sphere. The wave resistance was computed for …
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Lie group invariant finite-difference schemes for the neutron diffusion equation
Finite difference techniques are used to solve a variety of differential equations. For the neutron diffusion equation, the typical local truncation error for standard finite difference approximation is on the order of the mesh spacing squared. To improve the accuracy of the finite difference …
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Orthogonal matrix polynomials and differential, difference and q-difference matrix operators
… orthogonal polynomials satisfying differential, difference or q-difference equations. The search for examples of matrix polynomials which are also eigenfunctions of certain matrix operators is a rather dificult issue. This dificulty is due to several reasons. The most important of these reasons …
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Modeling and Simulation of Cutting in Soft Biological Tissues for Surgical Simulation
… of equilibrium are integrated usingthe central difference operator. The algorithm uses node snapping and edgerelocation procedures to align the edge of the element with the direction of cut.</p><p>The second part of the thesis focuses on determining a stress-based cuttingcriterion to mark the …
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Time-stable high-order finite difference methods for overset grids
… framework for implementing high-order finite difference methods to simulate compressible viscous flows over complex geometries. Although overset methods have been widely used to solve time-dependent partial differential equations, very few proofs of stability exist for them. In practice, the …
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Asymptotic spectral analysis and tunnelling for a class of difference operators
… in the limit epsilon to zero for a wide class of difference operators H_epsilon = T_epsilon + V_epsilon with underlying multi-well potential. They act on the square summable functions on the lattice (epsilon Z)^d. We start showing the validity of an harmonic approximation and construct …