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94
Automatic Frequency Assignment for Cellular Telephones Using Constraint Satisfaction Techniques
 Proceedings of the Tenth International Conference on Logic Programming
, 1993
"... We study the problem of automatic frequency assignment for cellular telephone systems. The frequency assignment problem is viewed as the problem to minimize the unsatisfied soft constraints in a constraint satisfaction problem (CSP) over a finite domain of frequencies involving cochannel, adjacent ..."
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We study the problem of automatic frequency assignment for cellular telephone systems. The frequency assignment problem is viewed as the problem to minimize the unsatisfied soft constraints in a constraint satisfaction problem (CSP) over a finite domain of frequencies involving cochannel, adjacent channel, and cosite constraints. The soft constraints are automatically derived from signal strength prediction data. The CSP is solved using a generalized graph coloring algorithm. Graphtheoretical results play a crucial role in making the problem tractable. Performance results from a realworld frequency assignment problem are presented. We develop the generalized graph coloring algorithm by stepwise refinement, starting from DSATUR and augmenting it with local propagation, constraint lifting, intelligent backtracking, redundancy avoidance, and iterative deepening. Key Words: frequency assignment, constraints, graph coloring, intelligent backtracking, iterative deepening. 1 Introduction...
An Application of Ontology Construction
, 1996
"... An important recent idea to facilitate knowledge sharing is to provide libraries of reusable components (models, ontologies) to end users. However, when libraries become large, finding the right library components is a knowledge demanding task in itself. Our suggestion therefore is that methods w ..."
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Cited by 11 (0 self)
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An important recent idea to facilitate knowledge sharing is to provide libraries of reusable components (models, ontologies) to end users. However, when libraries become large, finding the right library components is a knowledge demanding task in itself. Our suggestion therefore is that methods will be needed that help the user to gradually construct such knowledge.
Concept Hierarchy in Data Mining: Specification, Generation and Implementation
, 1997
"... Data mining is the nontrivial extraction of implicit, previously unknown, and potentially useful information from data. As one of the most important background knowledge, concept hierarchy plays a fundamentally important role in data mining. It is the purpose of this thesis to study some aspects of ..."
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Data mining is the nontrivial extraction of implicit, previously unknown, and potentially useful information from data. As one of the most important background knowledge, concept hierarchy plays a fundamentally important role in data mining. It is the purpose of this thesis to study some aspects of concept hierarchy such as the automatic generation and encoding technique in the context of data mining. After the discussion on the basic terminology and categorization, automatic generation of concept hierarchies is studied for both nominal and numerical hierarchies. One algorithm is designed for determining the partial order on a given set of nominal attributes. The resulting partial order is a useful guide for users to finalize the concept hierarchy for their particular data mining tasks. Based on hierarchical and partitioning clustering methods, two algorithms are proposed for the automatic generation of numerical hierarchies. The quality and performance comparisons indicates that the ...
An Analytical Model for Wormhole Routing with Finite Size Input Buffers
"... In this paper, we develop a queueing model for wormhole routing with finite size buffers. This model assumes the use of a deadlockfree routing scheme that guarantees no cycle of link dependency (defined in section 3). Several approximation methods for estimating the output link contention delay and ..."
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In this paper, we develop a queueing model for wormhole routing with finite size buffers. This model assumes the use of a deadlockfree routing scheme that guarantees no cycle of link dependency (defined in section 3). Several approximation methods for estimating the output link contention delay and buffer queueing delay are proposed. Comparing the analytical results to simulation, we show that the model is pessimistic with regard to network performance and that the difference in network throughput is less than 10 percent.
An Efficient Optimal Solution Method for the Joint Replenishment Problem
 European Journal of Operational Research
, 1996
"... During the last two decades, many heuristic procedures for the joint replenishment problem have appeared in the literature. The only available optimal solution procedure was based on an enumerative approach and was computationally prohibitive. In this paper we present an alternative optimal approach ..."
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Cited by 8 (5 self)
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During the last two decades, many heuristic procedures for the joint replenishment problem have appeared in the literature. The only available optimal solution procedure was based on an enumerative approach and was computationally prohibitive. In this paper we present an alternative optimal approach based on global optimisation theory. By applying Lipschitz optimisation one can find a solution with an arbitrarily small deviation from an optimal value. An efficient procedure is presented which uses a dynamic Lipschitz constant and generates a solution in little time. The running time of this procedure grows only linearly in the number of items. Keywords: Inventory, joint replenishment, multiitem, global optimisation, Lipschitz optimisation 1 Introduction In an inventory system with multiple items, cost savings can be obtained when the replenishment of several items are coordinated. Each time an order is placed, a major ordering cost is incurred, independent of the number of items ord...
Epidemic Spreading in Technological Networks
 INFORMATION INFRASTRUCTURE LABORATORY HP LABORATORIES BRISTOL
, 2002
"... This dissertation proposes a new epidemiological model to account for particular characteristics of computer worm epidemics. This new model, termed the Progressive SusceptibleInfectedDetectedRemoved (PSIDR) epidemiological model, incorporates new aspects related to the availability of antivi ..."
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This dissertation proposes a new epidemiological model to account for particular characteristics of computer worm epidemics. This new model, termed the Progressive SusceptibleInfectedDetectedRemoved (PSIDR) epidemiological model, incorporates new aspects related to the availability of antivirus signatures, to the existence of direct immunization, and to the presence of a curing phase. Various costs are incorporated in the model, which allow us to determine the best strategies to fight worms. The model undergoes an extensive series of validation tests, its properties being evaluated mostly numerically. The model shows good agreement with empirical data. The paper then investigates current response strategies as well as the effect of virus throttling. The model yields both practical recommendations and new insights about the observed low prevalence of worms over the Internet
Topology, scaling relations and Leonardo’s rule in root systems from African tree species
, 2001
"... ..."
Enhancing spatial deformation for virtual sculpting
"... Pages ii–iv and vi have been removed from this Technical Report to save space; they contained only a formal declaration relating to the PhD submission or were blank. Technical reports published by the University of Cambridge Computer Laboratory are freely available via the Internet: ..."
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Cited by 6 (2 self)
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Pages ii–iv and vi have been removed from this Technical Report to save space; they contained only a formal declaration relating to the PhD submission or were blank. Technical reports published by the University of Cambridge Computer Laboratory are freely available via the Internet:
Safety Properties Verification of Ladder Diagram Programs
 Journal Européen des systèmes automatisés
, 2002
"... ABSTRACT. Programmable Logic Controllers ensure the control of many reactive systems. These controllers are most of the time programmed with the languages defined in the IEC 61131– 3 standard. Our goal is the verification of safety properties of programs written in one of these languages: the Ladder ..."
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Cited by 5 (4 self)
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ABSTRACT. Programmable Logic Controllers ensure the control of many reactive systems. These controllers are most of the time programmed with the languages defined in the IEC 61131– 3 standard. Our goal is the verification of safety properties of programs written in one of these languages: the Ladder Diagram. The main approaches in this field are based on ModelChecking. We propose in this article a TheoremProving method by defining a formal framework to express and handle the Ladder Diagram programs with a specific algebra. Firstly, we translate the specific statements of the language into this algebra and we give some general theorems. Then, we present on an example an analysis leading to the verification of safety properties. RÉSUMÉ. Les automates programmables industriels assurent le contrôlecommande d’un grand nombre de systèmes réactifs. Leur programmation se fait le plus souvent avec des langages définis dans la norme IEC 61131–3. Notre objectif est la vérification de propriétés de sûreté dans les programmes écrits dans l’un de ces langages: le “Ladder Diagram”. Les principales approches dans le domaine abordent le problème par “ModelChecking”. Pour notre part, nous nous proposons d’explorer la voie du “TheoremProving ” en définissant un cadre formel pour exprimer et manipuler les programmes “Ladder Diagram ” dans une algèbre adaptée. Après avoir traduit les primitives de ce langage dans cette algèbre et donné des théorèmes généraux, nous présentons sur un exemple une analyse conduisant à la vérification de propriétés de sûreté.
A merging clustering algorithm for mobile ad hoc networks
 Proceedings of International Conference on Computational Science and Its Applications 2006, SpringerVerlag LNCS
, 2006
"... Abstract. Clustering is a widely used approach to ease implementation of various problems such as routing and resource management in mobile ad hoc networks (MANET)s. We first look at minimum spanning tree(MST) based algorithms and then propose a new algorithm for clustering in MANETs. The algorith ..."
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Abstract. Clustering is a widely used approach to ease implementation of various problems such as routing and resource management in mobile ad hoc networks (MANET)s. We first look at minimum spanning tree(MST) based algorithms and then propose a new algorithm for clustering in MANETs. The algorithm we propose merges clusters to form higher level clusters by increasing their levels. We show the operation of the algorithm and analyze its time and message complexities. 1