The Experts below are selected from a list of 300 Experts worldwide ranked by ideXlab platform
John M Wallace - One of the best experts on this subject based on the ideXlab platform.
-
sensitivity test of pop system matrices an application of spectral portrait of a Nonsymmetric Matrix
Journal of Climate, 1997Co-Authors: Yuan Zhang, Valentin P Dymnikov, John M WallaceAbstract:By using the POP (principal oscillation pattern) system matrices as examples, this study introduces to the meteorological community the concept and application of spectral portrait (or pseudospectra) of a Nonsymmetric Matrix. An analytical formula is provided to estimate the system error of a POP Matrix due to the inversion of a covariance Matrix. By comparing the spectral portrait and the system error, this study demonstrates a possible tool to test the sensitivity of a POP analysis.
-
Sensitivity Test of POP System Matrices—An Application of Spectral Portrait of a Nonsymmetric Matrix
Journal of Climate, 1997Co-Authors: Yuan Zhang, Valentin P Dymnikov, John M WallaceAbstract:By using the POP (principal oscillation pattern) system matrices as examples, this study introduces to the meteorological community the concept and application of spectral portrait (or pseudospectra) of a Nonsymmetric Matrix. An analytical formula is provided to estimate the system error of a POP Matrix due to the inversion of a covariance Matrix. By comparing the spectral portrait and the system error, this study demonstrates a possible tool to test the sensitivity of a POP analysis.
M. Mrozowski - One of the best experts on this subject based on the ideXlab platform.
-
Fast and accurate analysis of whispering gallery modes by the finite difference frequency domain method
13th International Conference on Microwaves Radar and Wireless Communications. MIKON - 2000. Conference Proceedings (IEEE Cat. No.00EX428), 2000Co-Authors: A. Cwikla, M. MrozowskiAbstract:The analysis of whispering gallery modes in a cylindrical sapphire resonator is shown. The formulation involves only two components of the electric flux density. Using the FDFD method on Yee's mesh, the electromagnetic problem is converted to a standard Nonsymmetric Matrix eigenvalue problem with a highly sparse and structured Matrix. The resonant modes are found by means of the implicitly restarted Arnoldi method with Chebyshev acceleration. Is is shown that the application of Chebyshev preconditioning allows one to significantly reduce the computing time without increasing the memory cost.
-
Comments on "Computation of cutoff wavenumbers of TE and TM modes in waveguides of arbitrary cross sections using a surface integral formulation" [with reply]
IEEE Transactions on Microwave Theory and Techniques, 1990Co-Authors: M. Mrozowski, Michal Okoniewski, M. Swaminathan, E. Arvas, T.k. Sarkar, A.r. DjordjevicAbstract:For the original article see ibid., vol.38, no.2, p.154-9 (1990). The authors use the method of moments and convert the E-field integral equation into a homogeneous set of equations of the form ZJ=0, where Z is a complex Nonsymmetric Matrix whose elements depend on the wavenumber and J is a vector containing the expansion coefficients for the surface current. They compute the determinant of the Matrix as a product of eigenvalues and claim that the computation requires on the order of n/sup 2/ operations, which represents a considerable savings over conventional methods. The commenters point out that since the Matrix is complex and Nonsymmetric, and the authors state that they first compute eigenvalues and then sort them, it is sensible to assume that the general QR algorithm was used for which the number of operation is much higher than approximately=n/sup 2/ claimed by the authors. The authors reply that the confusion arises because some important statements were left out of their paper as a result of page limitations. They provide the missing statements and clarify their conclusion.
Yuan Zhang - One of the best experts on this subject based on the ideXlab platform.
-
sensitivity test of pop system matrices an application of spectral portrait of a Nonsymmetric Matrix
Journal of Climate, 1997Co-Authors: Yuan Zhang, Valentin P Dymnikov, John M WallaceAbstract:By using the POP (principal oscillation pattern) system matrices as examples, this study introduces to the meteorological community the concept and application of spectral portrait (or pseudospectra) of a Nonsymmetric Matrix. An analytical formula is provided to estimate the system error of a POP Matrix due to the inversion of a covariance Matrix. By comparing the spectral portrait and the system error, this study demonstrates a possible tool to test the sensitivity of a POP analysis.
-
Sensitivity Test of POP System Matrices—An Application of Spectral Portrait of a Nonsymmetric Matrix
Journal of Climate, 1997Co-Authors: Yuan Zhang, Valentin P Dymnikov, John M WallaceAbstract:By using the POP (principal oscillation pattern) system matrices as examples, this study introduces to the meteorological community the concept and application of spectral portrait (or pseudospectra) of a Nonsymmetric Matrix. An analytical formula is provided to estimate the system error of a POP Matrix due to the inversion of a covariance Matrix. By comparing the spectral portrait and the system error, this study demonstrates a possible tool to test the sensitivity of a POP analysis.
A.r. Djordjevic - One of the best experts on this subject based on the ideXlab platform.
-
Comments on "Computation of cutoff wavenumbers of TE and TM modes in waveguides of arbitrary cross sections using a surface integral formulation" [with reply]
IEEE Transactions on Microwave Theory and Techniques, 1990Co-Authors: M. Mrozowski, Michal Okoniewski, M. Swaminathan, E. Arvas, T.k. Sarkar, A.r. DjordjevicAbstract:For the original article see ibid., vol.38, no.2, p.154-9 (1990). The authors use the method of moments and convert the E-field integral equation into a homogeneous set of equations of the form ZJ=0, where Z is a complex Nonsymmetric Matrix whose elements depend on the wavenumber and J is a vector containing the expansion coefficients for the surface current. They compute the determinant of the Matrix as a product of eigenvalues and claim that the computation requires on the order of n/sup 2/ operations, which represents a considerable savings over conventional methods. The commenters point out that since the Matrix is complex and Nonsymmetric, and the authors state that they first compute eigenvalues and then sort them, it is sensible to assume that the general QR algorithm was used for which the number of operation is much higher than approximately=n/sup 2/ claimed by the authors. The authors reply that the confusion arises because some important statements were left out of their paper as a result of page limitations. They provide the missing statements and clarify their conclusion.
Michal Okoniewski - One of the best experts on this subject based on the ideXlab platform.
-
Comments on "Computation of Cutoff Wavenumbers of TE and TM Modes in Waveguides of Arbitrary Cross Sections Using a Surface Integral Formulation"
1990Co-Authors: Michal Mrozowski, Michal OkoniewskiAbstract:In the above paper’ the authors present a method for treating hollow conducting waveguides. By using the method of moments they convert the E-field integral equation into a homogeneous set of equations of the form ZI=O where, as the authors noted, Z is a complex Nonsymmetric Matrix whose elements depend on the wavenumber and J is a vector containing the expansion coefficients for the surface current. The cutoff frequencies are found from the condition
-
Comments on "Computation of cutoff wavenumbers of TE and TM modes in waveguides of arbitrary cross sections using a surface integral formulation" [with reply]
IEEE Transactions on Microwave Theory and Techniques, 1990Co-Authors: M. Mrozowski, Michal Okoniewski, M. Swaminathan, E. Arvas, T.k. Sarkar, A.r. DjordjevicAbstract:For the original article see ibid., vol.38, no.2, p.154-9 (1990). The authors use the method of moments and convert the E-field integral equation into a homogeneous set of equations of the form ZJ=0, where Z is a complex Nonsymmetric Matrix whose elements depend on the wavenumber and J is a vector containing the expansion coefficients for the surface current. They compute the determinant of the Matrix as a product of eigenvalues and claim that the computation requires on the order of n/sup 2/ operations, which represents a considerable savings over conventional methods. The commenters point out that since the Matrix is complex and Nonsymmetric, and the authors state that they first compute eigenvalues and then sort them, it is sensible to assume that the general QR algorithm was used for which the number of operation is much higher than approximately=n/sup 2/ claimed by the authors. The authors reply that the confusion arises because some important statements were left out of their paper as a result of page limitations. They provide the missing statements and clarify their conclusion.
