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60
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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Cited by 13 (1 self)
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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...
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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Cited by 11 (0 self)
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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 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 9 (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.
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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Cited by 9 (0 self)
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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.
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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Cited by 8 (1 self)
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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
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 7 (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...
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.
Enhancing Spatial Deformation for Virtual Sculpting
, 2000
"... The task of computerbased freeform shape design is fraught with practical and conceptual difficulties. Incorporating elements of traditional clay sculpting has long been recognised as a means of shielding a user from the complexities inherent in this form of modelling. The premise is to deform a m ..."
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Cited by 4 (2 self)
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The task of computerbased freeform shape design is fraught with practical and conceptual difficulties. Incorporating elements of traditional clay sculpting has long been recognised as a means of shielding a user from the complexities inherent in this form of modelling. The premise is to deform a mathematicallydefined solid in a fashion that loosely simulates the physical moulding of an inelastic substance, such as modelling clay or silicone putty. Virtual sculpting combines this emulation of clay sculpting with interactive feedback. Spatial deformations are a class of powerful modelling techniques well suited to virtual sculpting. They indirectly reshape an object by warping the surrounding space. This is analogous to embedding a flexible shape within a lump of jelly and then causing distortions by flexing the jelly. The user controls spatial deformations by manipulating points, curves or a volumetric hyperpatch. Directly Manipulated FreeForm Deformation (DMFFD), in particular, me...
A FaultTolerant Reconfiguration Scheme in the Faulty Star Graph
 In Proceedings of 1996 Second International Conference on Algorithms & Architectures for Parallel Processing, ICA PP
, 1996
"... In this paper, we propose a scheme to identify the maximal faultfree substarring. This is the first result to derive a reconfiguration scheme with high processor utilization in the faulty nstar graph. The maximal faultfree substarring is connected by a ring of faultfree virtual substars with di ..."
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Cited by 4 (4 self)
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In this paper, we propose a scheme to identify the maximal faultfree substarring. This is the first result to derive a reconfiguration scheme with high processor utilization in the faulty nstar graph. The maximal faultfree substarring is connected by a ring of faultfree virtual substars with dilation 3 and maximal length of the ring is n(n \Gamma 1)(n \Gamma 2). Our proposed scheme can tolerate n \Gamma 3 faults such that the processor utilization is n 2 \Gamma2n+3 n 2 \Gamman . This is a near optimal result since the maximal faultfree substarring is constructed by using all of the possible faultfree (n \Gamma 2)substars. Moreover, our algorithm can still work when number of faults exceeds n \Gamma 3. The simulation results also show that the processor utilization is more than 50% if the number of faults is less than n 2 \Gamman\Gamma1 2 in the nstar graph. Keywords: Fault tolerance, interconnection network, parallel processing, reconfiguration, star graph. 1. Intr...
Structural Analysis for Fault Diagnosis of DAE Systems Utilizing Graph Theory and MSS Sets
, 2002
"... When designing modelbased faultdiagnostic systems, the use of consistency relations (also called e.g. parity relations) is a common choice. Different consistency relations are sensitive to different subsets of faults, and thereby isolation can be achieved. This report presents an algorithm for fin ..."
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Cited by 4 (2 self)
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When designing modelbased faultdiagnostic systems, the use of consistency relations (also called e.g. parity relations) is a common choice. Different consistency relations are sensitive to different subsets of faults, and thereby isolation can be achieved. This report presents an algorithm for finding a small set of submodels that can be used to derive consistency relations with highest possible diagnosis capability. The algorithm handles differentialalgebraic models and is based on graph theoretical reasoning about the structure of the model. An important step towards finding these submodels, and therefore also towards finding consistency relations, is to find all minimal structurally singular (MSS) sets of equations. These sets characterize the fault diagnosability. The algorithm is applied to a large nonlinear industrial example, a part of a paper plant. In spite of the complexity of this process, a small set of consistency relations with high diagnosis capability is