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Partitioning and Ordering Large Radiosity Computations
, 1994
"... We describe a system that computes radiosity solutions for polygonal environments much larger than can be stored in main memory. The solution is stored in and retrieved from a database as the computation proceeds. Our system is based on two ideas: the use of visibility oracles to find source and blo ..."
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Cited by 49 (5 self)
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We describe a system that computes radiosity solutions for polygonal environments much larger than can be stored in main memory. The solution is stored in and retrieved from a database as the computation proceeds. Our system is based on two ideas: the use of visibility oracles to find source and blocker surfaces potentially visible to a receiving surface; and the use of hierarchical techniques to represent interactions between large surfaces efficiently, and to represent the computed radiosity solution compactly. Visibility information allows the environment to be partitioned into subsets, each containing all the information necessary to transfer light to a cluster of receiving polygons. Since the largest subset needed for any particular cluster is much smaller than the total size of the environment, these subset computations can be performed in much less memory than can classical or hierarchical radiosity. The computation is then ordered for further efficiency. Careful ordering of ene...
Towards A Discipline Of Experimental Algorithmics
"... The last 20 years have seen enormous progress in the design of algorithms, but very little of it has been put into practice, even within academia; indeed, the gap between theory and practice has continuously widened over these years. Moreover, many of the recently developed algorithms are very hard ..."
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Cited by 36 (8 self)
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The last 20 years have seen enormous progress in the design of algorithms, but very little of it has been put into practice, even within academia; indeed, the gap between theory and practice has continuously widened over these years. Moreover, many of the recently developed algorithms are very hard to characterize theoretically and, as initially described, suffer from large runningtime coefficients. Thus the algorithms and data structures community needs to return to implementation as the standard of value; we call such an approach Experimental Algorithmics. Experimental Algorithmics studies algorithms and data structures by joining experimental studies with the more traditional theoretical analyses. Experimentation with algorithms and data structures is proving indispensable in the assessment of heuristics for hard problems, in the design of test cases, in the characterization of asymptotic behavior of complex algorithms, in the comparison of competing designs for tractabl...
An ObservationBased Admission Control Algorithm for Multimedia Servers
 Proceedings of the IEEE International Conference on Multimedia Computing Systems (ICMCS'94
, 1994
"... In this paper, we propose a novel observationbased admission control algorithm, in which a client is admitted for service by a multimedia server only if the predicted extrapolation from the status quo measurements of the storage server utilization indicate that the service requirements of all the c ..."
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Cited by 30 (3 self)
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In this paper, we propose a novel observationbased admission control algorithm, in which a client is admitted for service by a multimedia server only if the predicted extrapolation from the status quo measurements of the storage server utilization indicate that the service requirements of all the clients can be met satisfactorily. The performance of the admission control algorithm, and hence, the number of clients admitted and serviced simultaneously are maximized by employing a disk scheduling algorithm that minimizes both seek and rotational latency incurred while accessing a sequence of media blocks from disk. The effectiveness of the observationbased admission control algorithm is demonstrated through extensive simulations. 1 Introduction 1.1 Motivation Since the timid debut of the first usable computer almost half a century ago, the world has witnessed dramatic improvements in computer and communications technologies. Whereas breakthroughs in computer technology have stimulat...
Algorithms for Designing Multimedia Servers
 COMPUTER COMMUNICATIONS
, 1995
"... In this paper, we propose a novel adaptive admission control algorithm, in which a client is admitted for service by a multimediaserver only if the extrapolation from the past measurements of the storage server performance characteristics indicate that the service requirements of all the clients can ..."
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Cited by 20 (0 self)
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In this paper, we propose a novel adaptive admission control algorithm, in which a client is admitted for service by a multimediaserver only if the extrapolation from the past measurements of the storage server performance characteristics indicate that the service requirements of all the clients can be met satisfactorily. Each client may request the retrieval of a variable bit rate (VBR) encoded media stream and may require a different quality of service. We also present a disk scheduling algorithm that minimizes both seek time and rotational latency incurred while accessing a sequence of media blocks from disk. We examine the effects of a finite readahead on the quality of service provided to each admitted client. The effectiveness of the admission control and disk scheduling algorithms is demonstrated through extensive simulations.
Algorithms for Designing LargeScale Multimedia Servers
, 1995
"... In this paper, we propose a novel adaptive admission control algorithm, in which a client is admitted for service by a multimedia server only if the extrapolation from the past measurements of the storage server performance characteristics indicate that the service requirements of all the clients ca ..."
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Cited by 19 (6 self)
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In this paper, we propose a novel adaptive admission control algorithm, in which a client is admitted for service by a multimedia server only if the extrapolation from the past measurements of the storage server performance characteristics indicate that the service requirements of all the clients can be met satisfactorily. Each client may request the retrieval of a variable bit rate (VBR) encoded media stream and may require a different quality of service. We also present a disk scheduling algorithm that minimizes both seek time and rotational latency incurred while accessing a sequence of media blocks from disk. We examine the effects of a finite readahead on the quality of service provided to each admitted client. The effectiveness of the admission control and disk scheduling algorithms is demonstrated through extensive simulations.
Provably Good Solutions for the Traveling Salesman Problem
, 1992
"... The determination of true optimum solutions of combinatorial optimization problems is seldomly required in practical applications. The majority of users of optimization software would be satisfied with solutions of guaranteed quality in the sense that it can be proven that the given solution is at m ..."
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Cited by 13 (6 self)
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The determination of true optimum solutions of combinatorial optimization problems is seldomly required in practical applications. The majority of users of optimization software would be satisfied with solutions of guaranteed quality in the sense that it can be proven that the given solution is at most a few percent off an optimum solution. This paper presents a general framework for practical problem solving with emphasis on this aspect. A detailed discussion along with a report about extensive computational experiments is given for the traveling salesman problem.
© 1996 INFORMS Use of Representative Operation Counts in Computational Testing of Algorithms
"... In the mathematical programming literature, researchers have conducted a large number of computational studies to assess the empirical behavior of various algorithms and have utilized CPU time as the primary measure of performance. CPU time has the following drawbacks as a measure of an algorithm's ..."
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In the mathematical programming literature, researchers have conducted a large number of computational studies to assess the empirical behavior of various algorithms and have utilized CPU time as the primary measure of performance. CPU time has the following drawbacks as a measure of an algorithm's performance: it is implementation dependent, hard to replicate, and limited in the insight it provides into an algorithm's behavior. In this paper, we illustrate the notion of representative operation counts that can complement the conventional CPU time analysis and can help us (i) to identify the asymptotic bottleneck operations in an algorithm, (ii) to estimate an algorithm's running time for different problem sizes, and (iii) to obtain a fairer comparison of several algorithms. These concepts are easily incorporated into empirical studies and often yield valuable insights into an algorithm's behavior.
Heuristics for Sparse General Travelling Salesman Problems
"... Abstract: The wellknown travelling salesman problem can be expressed in graphtheoretic terms as follows: find a minimumweight Hamiltonian cycle in a connected edgeweighted graph G(N, A). vVe concentrate here on the problem where G is large and sparse, i.e., where INI is 500 or more and IAI is O ( ..."
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Abstract: The wellknown travelling salesman problem can be expressed in graphtheoretic terms as follows: find a minimumweight Hamiltonian cycle in a connected edgeweighted graph G(N, A). vVe concentrate here on the problem where G is large and sparse, i.e., where INI is 500 or more and IAI is O ( INI). Such graphs arise frequently in practice, where G represents a road network, and each node (city) is connected directly to 3 or 4 other nodes. Sparse graphs may not have Hamiltonian cycles and hence there may be no solution to the problem as stated. vVhether this is the case or not, the requirement that the cycle is Hamiltonian is often unnecessarily restrictive. It is sufficient in many practical problems, such as traffic planning. to address only what is called the General Travelling Salesman Problem, which requires merely a minimumweight, closed spanning walk, in which any node can be repeated if this lowers the total weight. Such a walk can, of course, be found in any connected graph. vVe report on the results of an experimental comparison of some heuristic methods for this problem. 1.