The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform
D. Towsley - One of the best experts on this subject based on the ideXlab platform.
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On optimal routing with multiple traffic matrices
Proceedings IEEE 24th Annual Joint Conference of the IEEE Computer and Communications Societies., 2005Co-Authors: Chun Zhang, Weibo Gong, J. Kurose, R. Moll, D. TowsleyAbstract:Routing optimization is used to find a set of routes that minimizes cost (delay, utilization). Previous work has addressed this problem for the Case of a known, static end-to-end traffic Matrix. In the Internet, it is difficult to accurately estimate a traffic Matrix, and the constantly changing nature of Internet traffic makes it costly to maintain optimal routing by responding to traffic changes. Thus, it is of interest to maintain a set of routes that are "good" for a number of different possible traffic scenarios. In this paper, we explore ways to find an optimal set of routes with multiple traffic matrices to minimize expected cost. We focus on two general approaches, source-destination routing and destination routing. In the Case of source-destination routing, we extend existing methods with a single traffic Matrix to solve the optimization problem with multiple traffic matrices: we extend the convex optimization solution methods for a single traffic Matrix to the multiple traffic Matrix Case; we also extend the gradient-based solution methods for a single traffic Matrix to the multiple traffic Matrix Case. However, the multiple traffic Matrix Case requires many more control variables. In the Case of destination routing, we encounter many more differences from the single traffic Matrix Case. The loop-free property, which is valid for the single traffic Matrix Case, is no longer valid for the multiple traffic Matrix Case, and it is difficult to extend existing methods for a single traffic Matrix to solve the optimization problem with multiple traffic matrices. We show that it is NP-complete even to determine the feasibility of multiple traffic matrices. We thus propose and evaluate a heuristic algorithm for this Case.
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INFOCOM - On optimal routing with multiple traffic matrices
Proceedings IEEE 24th Annual Joint Conference of the IEEE Computer and Communications Societies., 2005Co-Authors: Chun Zhang, Weibo Gong, J. Kurose, R. Moll, D. TowsleyAbstract:Routing optimization is used to find a set of routes that minimizes cost (delay, utilization). Previous work has addressed this problem for the Case of a known, static end-to-end traffic Matrix. In the Internet, it is difficult to accurately estimate a traffic Matrix, and the constantly changing nature of Internet traffic makes it costly to maintain optimal routing by responding to traffic changes. Thus, it is of interest to maintain a set of routes that are "good" for a number of different possible traffic scenarios. In this paper, we explore ways to find an optimal set of routes with multiple traffic matrices to minimize expected cost. We focus on two general approaches, source-destination routing and destination routing. In the Case of source-destination routing, we extend existing methods with a single traffic Matrix to solve the optimization problem with multiple traffic matrices: we extend the convex optimization solution methods for a single traffic Matrix to the multiple traffic Matrix Case; we also extend the gradient-based solution methods for a single traffic Matrix to the multiple traffic Matrix Case. However, the multiple traffic Matrix Case requires many more control variables. In the Case of destination routing, we encounter many more differences from the single traffic Matrix Case. The loop-free property, which is valid for the single traffic Matrix Case, is no longer valid for the multiple traffic Matrix Case, and it is difficult to extend existing methods for a single traffic Matrix to solve the optimization problem with multiple traffic matrices. We show that it is NP-complete even to determine the feasibility of multiple traffic matrices. We thus propose and evaluate a heuristic algorithm for this Case.
Chun Zhang - One of the best experts on this subject based on the ideXlab platform.
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On optimal routing with multiple traffic matrices
Proceedings IEEE 24th Annual Joint Conference of the IEEE Computer and Communications Societies., 2005Co-Authors: Chun Zhang, Weibo Gong, J. Kurose, R. Moll, D. TowsleyAbstract:Routing optimization is used to find a set of routes that minimizes cost (delay, utilization). Previous work has addressed this problem for the Case of a known, static end-to-end traffic Matrix. In the Internet, it is difficult to accurately estimate a traffic Matrix, and the constantly changing nature of Internet traffic makes it costly to maintain optimal routing by responding to traffic changes. Thus, it is of interest to maintain a set of routes that are "good" for a number of different possible traffic scenarios. In this paper, we explore ways to find an optimal set of routes with multiple traffic matrices to minimize expected cost. We focus on two general approaches, source-destination routing and destination routing. In the Case of source-destination routing, we extend existing methods with a single traffic Matrix to solve the optimization problem with multiple traffic matrices: we extend the convex optimization solution methods for a single traffic Matrix to the multiple traffic Matrix Case; we also extend the gradient-based solution methods for a single traffic Matrix to the multiple traffic Matrix Case. However, the multiple traffic Matrix Case requires many more control variables. In the Case of destination routing, we encounter many more differences from the single traffic Matrix Case. The loop-free property, which is valid for the single traffic Matrix Case, is no longer valid for the multiple traffic Matrix Case, and it is difficult to extend existing methods for a single traffic Matrix to solve the optimization problem with multiple traffic matrices. We show that it is NP-complete even to determine the feasibility of multiple traffic matrices. We thus propose and evaluate a heuristic algorithm for this Case.
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INFOCOM - On optimal routing with multiple traffic matrices
Proceedings IEEE 24th Annual Joint Conference of the IEEE Computer and Communications Societies., 2005Co-Authors: Chun Zhang, Weibo Gong, J. Kurose, R. Moll, D. TowsleyAbstract:Routing optimization is used to find a set of routes that minimizes cost (delay, utilization). Previous work has addressed this problem for the Case of a known, static end-to-end traffic Matrix. In the Internet, it is difficult to accurately estimate a traffic Matrix, and the constantly changing nature of Internet traffic makes it costly to maintain optimal routing by responding to traffic changes. Thus, it is of interest to maintain a set of routes that are "good" for a number of different possible traffic scenarios. In this paper, we explore ways to find an optimal set of routes with multiple traffic matrices to minimize expected cost. We focus on two general approaches, source-destination routing and destination routing. In the Case of source-destination routing, we extend existing methods with a single traffic Matrix to solve the optimization problem with multiple traffic matrices: we extend the convex optimization solution methods for a single traffic Matrix to the multiple traffic Matrix Case; we also extend the gradient-based solution methods for a single traffic Matrix to the multiple traffic Matrix Case. However, the multiple traffic Matrix Case requires many more control variables. In the Case of destination routing, we encounter many more differences from the single traffic Matrix Case. The loop-free property, which is valid for the single traffic Matrix Case, is no longer valid for the multiple traffic Matrix Case, and it is difficult to extend existing methods for a single traffic Matrix to solve the optimization problem with multiple traffic matrices. We show that it is NP-complete even to determine the feasibility of multiple traffic matrices. We thus propose and evaluate a heuristic algorithm for this Case.
Yingning Peng - One of the best experts on this subject based on the ideXlab platform.
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The characteristic polarization states and the equi-power curves
IEEE Transactions on Geoscience and Remote Sensing, 2002Co-Authors: Jian Yang, Y. Yamaguchi, H. Yamada, Z.h. Czyz, W.-m. Boerner, H. Mott, E. Luneburg, Yingning PengAbstract:Characteristic polarization state theory is restudied for the symmetric coherent Sinclair scattering Matrix Case. First, the geometric relations of the characteristic polarization states on the Poincare sphere are derived. Based on these relations, simple formulas are given for all of the characteristic polarization states of this Sinclair Matrix in Stokes vector form. From the formulation, it is clear that the CO-POL Nulls are fundamental characteristic polarization states for the symmetric coherent Sinclair scattering Matrix Case, in that the others can straightforwardly be obtained from the Stokes vectors of the CO-POL Nulls. For further study of the characteristic polarization state and the distribution of the received powers on the Poincare sphere, the authors introduce the concept of the equi-power curve. It is defined as the curve on the Poincare sphere on which the received powers in some defined channel have the same value. They deal with the characteristics of the equi-power curves for various special Cases. In addition, they show how the characteristic polarization states are generated by the equi-power curves. It is demonstrated that the characteristic polarization states can usually be regarded as the points of contact of the Poincare sphere and a conicoid representing a power-related quadratic form. This leads to a new method to introduce the characteristic polarization states.
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Development of target null theory
IEEE Transactions on Geoscience and Remote Sensing, 2001Co-Authors: Jian Yang, Y. Yamaguchi, H. Yamada, W.-m. Boerner, H. Mott, Yingning PengAbstract:In a co- or cross-polarized channel, the polarization states of the transmitting and receiving antennas are the same or orthogonal, and the corresponding target nulls (i.e., the co-pol nulls or x-pol nulls) are defined as the polarization states of the transmitting antenna such that the received power equals zero. However, no systematic studies have been carried out to solve the problem of the corresponding target nulls if the polarization states of the transmitting and receiving antennas are independent. In this paper, the target null theory is extended to the Case of two independent polarization states. For two arbitrary independent symmetric scattering matrices, it is proved that there exists only one pair of polarization states such that both of the received powers equal zero. This polarization states' pair is called the co-null of the two targets, which can easily be obtained by solving an eigenvalue problem. Based on this concept and algebraic theory, the concept of the co-null space is introduced for the symmetric scattering Matrix Case, and many important results are presented, e.g., the relations between the co-null and the co-pol/x-pol nulls, the properties of the co-null space, and the relation between the co-null and target decomposition. Finally, the co-null for the asymmetric scattering Matrix Case is studied. The concepts of the mono-co-null space and the bi-co-null space are introduced, and the relations between both spaces are presented.
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Extension of the Kennaugh null theory
2000 5th International Symposium on Antennas Propagation and EM Theory. ISAPE 2000 (IEEE Cat. No.00EX417), 2000Co-Authors: Jian Yang, Yingning Peng, Y. Yamaguchi, H. YamadaAbstract:In radar polarimetry, Kennaugh (1952) first introduced the concept of the characteristic polarization states. This paper introduced the concepts of the co-null and the co-null Abelian group for extending the Kennaugh null theory to the Case of two independent polarization states. For two arbitrary targets, it is proved that there exists one pair of polarization states such that the received powers of both targets equal zero. This polarization states' pair is called the co-null of the two targets, which can easily be obtained by solving an eigenvalue problem. Based on group theory, another concept- the co-null Abelian group is introduced for the symmetric scattering Matrix Case, and many important results are presented: e.g., the relations between the co-null and the co-pol/X-pol nulls, the structure of the co-null Abelian group, and the relations between the co-null Abelian group and two classes of targets: symmetric targets and H-targets. Finally, the co-null for the asymmetric scattering Matrix Case is studied. The concepts of the mono-co-null Abelian group and the bi-co-null Abelian group are introduced, and the relations between both groups are presented.
Harish K Pillai - One of the best experts on this subject based on the ideXlab platform.
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a parametrisation for dissipative behaviours the Matrix Case
International Journal of Control, 2009Co-Authors: Ishan Pendharkar, Harish K PillaiAbstract:We study linear, time-invariant dynamical systems that are dissipative with respect to a generalised power defined by a quadratic differential form. We address several Cases, in an increasing order of complexity, and show how dissipative systems can be parametrised. In this process, we also establish a number of results for polynomial matrices that are of independent interest. The present article is a generalisation of our earlier work that dealt with single-input single-output dissipative systems (Pendharkar, I., and Pillai, H.K. (2004), ‘A Parametrization for Dissipative Behaviours’, Systems and Control Letters, 51, 123–132).
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A parametrisation for dissipative behaviours ― the Matrix Case
International Journal of Control, 2009Co-Authors: Ishan Pendharkar, Harish K PillaiAbstract:We study linear, time-invariant dynamical systems that are dissipative with respect to a generalised power defined by a quadratic differential form. We address several Cases, in an increasing order of complexity, and show how dissipative systems can be parametrised. In this process, we also establish a number of results for polynomial matrices that are of independent interest. The present article is a generalisation of our earlier work that dealt with single-input single-output dissipative systems (Pendharkar, I., and Pillai, H.K. (2004), ‘A Parametrization for Dissipative Behaviours’, Systems and Control Letters, 51, 123–132).
Weibo Gong - One of the best experts on this subject based on the ideXlab platform.
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On optimal routing with multiple traffic matrices
Proceedings IEEE 24th Annual Joint Conference of the IEEE Computer and Communications Societies., 2005Co-Authors: Chun Zhang, Weibo Gong, J. Kurose, R. Moll, D. TowsleyAbstract:Routing optimization is used to find a set of routes that minimizes cost (delay, utilization). Previous work has addressed this problem for the Case of a known, static end-to-end traffic Matrix. In the Internet, it is difficult to accurately estimate a traffic Matrix, and the constantly changing nature of Internet traffic makes it costly to maintain optimal routing by responding to traffic changes. Thus, it is of interest to maintain a set of routes that are "good" for a number of different possible traffic scenarios. In this paper, we explore ways to find an optimal set of routes with multiple traffic matrices to minimize expected cost. We focus on two general approaches, source-destination routing and destination routing. In the Case of source-destination routing, we extend existing methods with a single traffic Matrix to solve the optimization problem with multiple traffic matrices: we extend the convex optimization solution methods for a single traffic Matrix to the multiple traffic Matrix Case; we also extend the gradient-based solution methods for a single traffic Matrix to the multiple traffic Matrix Case. However, the multiple traffic Matrix Case requires many more control variables. In the Case of destination routing, we encounter many more differences from the single traffic Matrix Case. The loop-free property, which is valid for the single traffic Matrix Case, is no longer valid for the multiple traffic Matrix Case, and it is difficult to extend existing methods for a single traffic Matrix to solve the optimization problem with multiple traffic matrices. We show that it is NP-complete even to determine the feasibility of multiple traffic matrices. We thus propose and evaluate a heuristic algorithm for this Case.
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INFOCOM - On optimal routing with multiple traffic matrices
Proceedings IEEE 24th Annual Joint Conference of the IEEE Computer and Communications Societies., 2005Co-Authors: Chun Zhang, Weibo Gong, J. Kurose, R. Moll, D. TowsleyAbstract:Routing optimization is used to find a set of routes that minimizes cost (delay, utilization). Previous work has addressed this problem for the Case of a known, static end-to-end traffic Matrix. In the Internet, it is difficult to accurately estimate a traffic Matrix, and the constantly changing nature of Internet traffic makes it costly to maintain optimal routing by responding to traffic changes. Thus, it is of interest to maintain a set of routes that are "good" for a number of different possible traffic scenarios. In this paper, we explore ways to find an optimal set of routes with multiple traffic matrices to minimize expected cost. We focus on two general approaches, source-destination routing and destination routing. In the Case of source-destination routing, we extend existing methods with a single traffic Matrix to solve the optimization problem with multiple traffic matrices: we extend the convex optimization solution methods for a single traffic Matrix to the multiple traffic Matrix Case; we also extend the gradient-based solution methods for a single traffic Matrix to the multiple traffic Matrix Case. However, the multiple traffic Matrix Case requires many more control variables. In the Case of destination routing, we encounter many more differences from the single traffic Matrix Case. The loop-free property, which is valid for the single traffic Matrix Case, is no longer valid for the multiple traffic Matrix Case, and it is difficult to extend existing methods for a single traffic Matrix to solve the optimization problem with multiple traffic matrices. We show that it is NP-complete even to determine the feasibility of multiple traffic matrices. We thus propose and evaluate a heuristic algorithm for this Case.