Spelling suggestions: "subject:"integral cooperator"" "subject:"integral inoperator""
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Analysis of the Three-dimensional Superradiance Problem and Some GeneralizationsSen Gupta, Indranil 2010 August 1900 (has links)
We study the integral equation related to the three and higher dimensional
superradiance problem. Collective radiation phenomena has attracted the attention
of many physicists and chemists since the pioneering work of R. H. Dicke in 1954.
We first consider the three-dimensional superradiance problem and find a differential
operator that commutes with the integral operator related to the problem. We
find all the eigenfunctions of the differential operator and obtain a complete set of
eigensolutions for the three-dimensional superradiance problem. Generalization of
the three-dimensional superradiance integral equation is provided. A commuting differential
operator is found for this generalized problem. For the three dimensional
superradiance problem, an alternative set of complete eigenfunctions is also provided.
The kernel for the superradiance problem when restricted to one-dimension is the
same as appeared in the works of Slepian, Landau and Pollak. The uniqueness of the
differential operator commuting with that kernel is indicated. Finally, a concentration
problem for the signals which are bandlimited in disjoint frequency-intervals is
considered. The problem is to determine which bandlimited signals lose the smallest
fraction of their energy when restricted in a given time interval. A numerical
algorithm for solution and convergence theorems are given. Orthogonality properties
of analytically extended eigenfunctions over L2(−∞,∞) are also proved. Numerical
computations are carried out in support of the theory.
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Migration preconditioning with curvelets.Moghaddam, Peyman P., Herrmann, Felix J. January 2004 (has links)
In this paper, the property of Curvelet transforms for preconditioning the migration and normal operators is investigated. These operators belong to the class of Fourier integral operators and pseudo-differential operators, respectively. The effect of this preconditioner is shown in term of improvement of sparsity, convergence rate, number of iteration for the Krylov-subspace solver and clustering of singular(eigen) values. The migration operator, which we employed in this work is the common-offset Kirchoff-Born migration.
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New results on the degree of ill-posedness for integration operators with weightsHofmann, Bernd, von Wolfersdorf, Lothar 16 May 2008 (has links) (PDF)
We extend our results on the degree of ill-posedness for linear integration opera-
tors A with weights mapping in the Hilbert space L^2(0,1), which were published in
the journal 'Inverse Problems' in 2005 ([5]). Now we can prove that the degree one
also holds for a family of exponential weight functions. In this context, we empha-
size that for integration operators with outer weights the use of the operator AA^*
is more appropriate for the analysis of eigenvalue problems and the corresponding
asymptotics of singular values than the former use of A^*A.
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A study of three variable analogues of certain fractional integral operatorsKhan, Mumtaz Ahmad, Sharma, Bhagwat Swaroop 25 September 2017 (has links)
The paper deals with a three variable analogues of certain fractional integral operators introduced by M. Saigo. Resides giving three variable analogues of earlier known fractional integral operators of one variable as a special cases of newly defined operators, the paper establishes certain results in the form of theorems including integration by parts.
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The Numerical Solutions of Fractional Differential Equations with Fractional Taylor VectorKrishnasamySaraswathy, Vidhya 12 August 2016 (has links)
In this dissertation, a new numerical method for solving fractional calculus problems is presented. The method is based upon the fractional Taylor vector approximations. The operational matrix of the fractional integration for the fractional Taylor vector is introduced. This matrix is then utilized to reduce the solution of the fractional calculus problems to the solution of a system of algebraic equations. This method is used to solve fractional differential equations, Bagley-Torvik equations, fractional integro-differential equations, and fractional duffing problems. Illustrative examples are included to demonstrate the validity and applicability of this technique.
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Critical exponents for semilinear Tricomi-type equationsHe, Daoyin 16 September 2016 (has links)
No description available.
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Semi-classical approximations of Quantum Mechanical problemsKarlsson, Ulf January 2002 (has links)
No description available.
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Semi-classical approximations of Quantum Mechanical problemsKarlsson, Ulf January 2002 (has links)
No description available.
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New results on the degree of ill-posedness for integration operators with weightsHofmann, Bernd, von Wolfersdorf, Lothar 16 May 2008 (has links)
We extend our results on the degree of ill-posedness for linear integration opera-
tors A with weights mapping in the Hilbert space L^2(0,1), which were published in
the journal 'Inverse Problems' in 2005 ([5]). Now we can prove that the degree one
also holds for a family of exponential weight functions. In this context, we empha-
size that for integration operators with outer weights the use of the operator AA^*
is more appropriate for the analysis of eigenvalue problems and the corresponding
asymptotics of singular values than the former use of A^*A.
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A novel Chebyshev wavelet method for solving fractional-order optimal control problemsGhanbari, Ghodsieh 13 May 2022 (has links) (PDF)
This thesis presents a numerical approach based on generalized fractional-order Chebyshev wavelets for solving fractional-order optimal control problems. The exact value of the Riemann– Liouville fractional integral operator of the generalized fractional-order Chebyshev wavelets is computed by applying the regularized beta function. We apply the given wavelets, the exact formula, and the collocation method to transform the studied problem into a new optimization problem. The convergence analysis of the proposed method is provided. The present method is extended for solving fractional-order, distributed-order, and variable-order optimal control problems. Illustrative examples are considered to show the advantage of this method in comparison with the existing methods in the literature.
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