Results 1  10
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15
Routing and Wavelength Assignment in AllOptical Networks
 IEEE/ACM Transactions on Networking
, 1995
"... This paper considers the problem of routing connections in a reconfigurable optical network using wavelength division multiplexing, where each connection between a pair of nodes in the network is assigned a path through the network and a wavelength on that path, such that connections whose paths sha ..."
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Cited by 207 (10 self)
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This paper considers the problem of routing connections in a reconfigurable optical network using wavelength division multiplexing, where each connection between a pair of nodes in the network is assigned a path through the network and a wavelength on that path, such that connections whose paths share a common link in the network are assigned different wavelengths. We derive an upper bound on the carried traffic of connections (or equivalently, a lower bound on the blocking probability) for any routing and wavelength assignment (RWA) algorithm in such a network. The bound scales with the number of wavelengths and is achieved asymptotically (when a large number of wavelengths is available) by a fixed RWA algorithm. Although computationally intensive, our bound can be used as a metric against which the performance of different RWA algorithms can be compared for networks of moderate size. We illustrate this by comparing the performance of a simple shortestpath RWA (SPRWA) algorithm via...
Performance Analysis and Optimization of Asynchronous Circuits
, 1991
"... We present a method for analyzing the time performance of asynchronous circuits, in particular, those derived by program transformation from concurrent programs using the synthesis approach developed by the second author. The analysis method produces a performance metric (related to the time needed ..."
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Cited by 136 (7 self)
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We present a method for analyzing the time performance of asynchronous circuits, in particular, those derived by program transformation from concurrent programs using the synthesis approach developed by the second author. The analysis method produces a performance metric (related to the time needed to perform an operation) in terms of the primitive gate delays of the circuit. Such a metric provides a quantitative means by which to compare competing designs. Because the gate delays are functions of transistor sizes, the performance metric can be optimized with respect to these sizes. For a large class of asynchronous circuitsincluding those produced by using our synthesis methodthese techniques produce the global optimum of the performance metric. A CAD tool has been implemented to perform this optimization. 1 Introduction Performance analysis of a synchronous computer system is simplified by an external clock that partitions the events in the system into discrete segments. In a...
Secondorder rigidity and prestress stability for tensegrity frameworks
 SIAM J. Discrete Math
, 1996
"... Abstract. This paper defines two concepts of rigidity for tensegrity frameworks (frameworks with cables, bars, and struts): prestress stability and secondorder rigidity. We demonstrate a hierarchy of rigidityfirstorder rigidity implies prestress stability implies secondorder rigidity implies ri ..."
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Cited by 33 (9 self)
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Abstract. This paper defines two concepts of rigidity for tensegrity frameworks (frameworks with cables, bars, and struts): prestress stability and secondorder rigidity. We demonstrate a hierarchy of rigidityfirstorder rigidity implies prestress stability implies secondorder rigidity implies rigiditymfor any framework. Examples show that none of these implications are reversible, even for bar frameworks. Other examples illustrate how these results can be used to create rigid tensegrity frameworks. This paper also develops a duality for secondorder rigidity, leading to a test which combines information on the self stresses and the firstorder flexes of a framework to detect secondorder rigidity. Using this test, the following conjecture of Roth is proven: a plane tensegrity framework, in which the vertices and bars form a strictly convex polygon with additional cables across the interior, is rigid if and only if it is firstorder rigid. Key words, tensegrity frameworks, rigid and flexible frameworks, stability of frameworks, static stress, firstorder motion, secondorder motion AMS subject classifications. Primary, 52C25; Secondary, 70B15, 70C20 1. Introduction. A
A General Approach to Performance Analysis and Optimization of Asynchronous Circuits
, 1995
"... A systematic approach for evaluating and optimizing the performance of asynchronous VLSI circuits is presented. Indexpriority simulation is introduced to efficiently find minimal cycles in the state graph of a given circuit. These minimal cycles are used to determine the causality relationships bet ..."
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Cited by 14 (0 self)
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A systematic approach for evaluating and optimizing the performance of asynchronous VLSI circuits is presented. Indexpriority simulation is introduced to efficiently find minimal cycles in the state graph of a given circuit. These minimal cycles are used to determine the causality relationships between all signal transitions in the circuit. Once these relationships are known, the circuit is then modeled as an extended eventrule system, which can be used to describe many circuits, including ones that are inherently disjunctive. An accurate indication of the performance of the circuit is obtained by analytically computing the period of the corresponding extended eventrule system.
Optimized Halftoning Using Dot Diffusion and Methods for Inverse Halftoning
, 2000
"... Unlike the error diffusion method, the dot diffusion method for digital halftoning has the advantage of pixellevel parallelism. However, image quality offered by error diffusion is still regarded as superior to most of the other known methods. In this paper, we show how the dot diffusion method can ..."
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Cited by 12 (2 self)
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Unlike the error diffusion method, the dot diffusion method for digital halftoning has the advantage of pixellevel parallelism. However, image quality offered by error diffusion is still regarded as superior to most of the other known methods. In this paper, we show how the dot diffusion method can be improved by optimization of the socalled class matrix. By taking the human visual characteristics into account we show that such optimization consistently results in images comparable to error diffusion, without sacrificing the pixellevel parallelism. Adaptive dot diffusion is also introduced and then a mathematical description of dot diffusion is derived. Furthermore, inverse halftoning of dot diffused images is discussed and two methods are proposed. The first one uses projection onto convex sets (POCS) and the second one uses wavelets. Of these methods, the wavelet method does not make use of the knowledge of the class matrix. Embedded multiresolution dot diffusion is also discussed, which is useful for rendering at different resolutions and transmitting images progressively.
Channel Assignment Algorithms Satisfying Cochannel and Adjacent Channel Reuse Constraints in Cellular Mobile Networks
, 1998
"... Recently improved channel assignment algorithms for cellular networks were designed by modelling the interference constraints in terms of a hypergraph [1]. However these algorithms only considered cochannel reuse constraints. Receiver filter responses impose restrictions on simultaneous adjacent cha ..."
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Cited by 9 (0 self)
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Recently improved channel assignment algorithms for cellular networks were designed by modelling the interference constraints in terms of a hypergraph [1]. However these algorithms only considered cochannel reuse constraints. Receiver filter responses impose restrictions on simultaneous adjacent channel usage in the same cell or in neighbouring cells. We first present some heuristics for designing fixed channel assignment algorithms with a minimum number of channels satisfying both cochannel and adjacent channel reuse constraints. An asymptotically tight upper bound for the traffic carried by the system in the presence of arbitrary cochannel and adjacent channel reuse constraints was developed in [2]. However this bound is computationally intractable even for small systems like a regular hexagonal cellular system of 19 cells. We have obtained approximations to this bound using the optimal solutions for cochannel reuse constraints only, and a further graph theoretic approach. Our approximations are computationally much more efficient and have turned out to track very closely the exact performance bounds in most cases of interest.
A Review of the Theory and Applications of Optimal Subband and Transform Coders
 Journal of Applied and Computational Harmonic Analysis
, 2001
"... this paper we first give a review of the older "classical approaches" to filter bank optimization, to place the ideas in the right perspective. We then review more recent results on optimal filter banks. This includes a review of principal component filter banks, their optimality properties, and som ..."
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Cited by 9 (4 self)
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this paper we first give a review of the older "classical approaches" to filter bank optimization, to place the ideas in the right perspective. We then review more recent results on optimal filter banks. This includes a review of principal component filter banks, their optimality properties, and some applications of these. To emphasize the generality of these results we show an application in digital communications (the discrete multitone channel). We show, for example, that the PCFB minimizes transmitted power for a given probability of error and bit rate. We finally discuss future directions and open problems in this broad area
Dynamics, Friction, And Complementarity Problems
 Proceedings Internat. Conf. Complementarity Problems
, 1995
"... . An overview is presented here of recent work and approaches to solving dynamic problems in rigid body mechanics with friction. It begins with the differential inclusion approach to Coulomb friction where the normal contact force is known. Numerical methods for these differential inclusions commonl ..."
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Cited by 7 (3 self)
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. An overview is presented here of recent work and approaches to solving dynamic problems in rigid body mechanics with friction. It begins with the differential inclusion approach to Coulomb friction where the normal contact force is known. Numerical methods for these differential inclusions commonly lead to linear or nonlinear complementarity problems. Then the measure differential inclusion formulation of rigid body dynamics due to Moreau and others is presented. A novel algorithm for timestepping for rigid body dynamics is given which avoids the "nonexistence" issues that arise in many other formulations. The timestepping algorithm requires the solution of an NCP at each step. Results on the convergence of the numerical solutions to solutions in the sense of measure differential inclusions are given, and numerical results for an implementation of the method are shown. Key Words. friction, differential inclusions, rigid body dynamics, complementarity problem 1. Introduction. Thi...
Asymptotic Performance Limits for Routing and Rate Allocation In RateBased MultiClass Networks
 In Proc. IEEE GLOBECOM
, 2002
"... In this paper we investigate the performance of Routing and Rate Allocation (RRA) algorithms in ratebased multiclass networks, in particular, a network of routers that support the IntServ Guaranteed Services. We measure the performance of an RRA algorithm in terms of its weighted carried traffic. W ..."
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Cited by 3 (2 self)
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In this paper we investigate the performance of Routing and Rate Allocation (RRA) algorithms in ratebased multiclass networks, in particular, a network of routers that support the IntServ Guaranteed Services. We measure the performance of an RRA algorithm in terms of its weighted carried traffic. We derive an upper bound on the weighted carried traffic of any RRA algorithm. The bound can be computed by linear programming. Moreover we show that a Fixed RRA algorithm achieves the bound asymptotically. Therefore the bound can be used as an absolute benchmark for the performance of various RRA algorithms. We illustrate this by comparing the simulated performance of a simple shortestpath RRA (SPRRA) algorithm with the bound.
On voter incentives to become informed
 California Institute of Technology Social Science Working Paper 968
, 1996
"... Before an election, two candidates choose policies which are lotteries over electionday distributive positions. I find conditions under which there exist mixedstrategy probabilisticvoting equilibria which are independent, treating voter groups independently. When voter efforts determine the qualit ..."
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Cited by 1 (0 self)
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Before an election, two candidates choose policies which are lotteries over electionday distributive positions. I find conditions under which there exist mixedstrategy probabilisticvoting equilibria which are independent, treating voter groups independently. When voter efforts determine the quality of their signals regarding candidate positions, voters can have strong incentives regarding their visible efforts made before candidates choose policies. Also, scale economies in group information production can make voters prefer large groups. Even with zero information costs, however, voters can ex ante prefer ignorance to full information. Optimal ignorance emphasizes negative over positive news, and induces candidates to take stable positions. ∗ I thank Mike Alvarez, Matt Jackson, Steven Knack, John Ledyard, Richard McKelvey, and Thomas Palfrey for comments on earlier versions of this paper. I especially thank Kim Border for help in thinking about proving existence. I thank the New Millennium Program Office of the Jet Propulsion Lab of NASA for financial support. This paper is a chapter in my 1997 Caltech Ph.D. dissertation.