This paper presents an optimization model for base station location in 3G UMTS downlink environment. The model concerns optimization of the base station parameters such as base station location, transmitted power and ...
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ISBN:
(纸本)0780377818
This paper presents an optimization model for base station location in 3G UMTS downlink environment. The model concerns optimization of the base station parameters such as base station location, transmitted power and antenna height, all of which can be individually assigned to each base station. All these choices must satisfy a set of constraints and optimize a set of objectives. This problem is NP-hard and consequently cannot be practically solved by exact methods for real size networks. Thus, we apply heuristic and stochastic optimization techniques for tackling this complex and highly combinatorial problem. To evaluate the effectiveness of the methods, an extensive experimental analysis is presented.
A construction of timetabling is considered to be a computationally hard problem. The problem lies not only in NP-completeness, but also in a number of complicated interactions between different users. The paper prese...
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ISBN:
(纸本)9539676967
A construction of timetabling is considered to be a computationally hard problem. The problem lies not only in NP-completeness, but also in a number of complicated interactions between different users. The paper presents System of Automated Timetabling (SA T), as a proposition for a global look at timetabling. It describes four tools for managing timetable. The constraint programming (CP) techniques were used for solving the problem. CP provides both declarativity and flexibility. Moreover it allows easily acid a new constraint and model numerous specific constraints that are often encountered in such problems. Additional local search was incorporated into CP to allow effectively optimise timetable.
This paper focuses on the problem of scheduling outages to computer systems in complex distributed environments. The interconnected nature of these systems makes scheduling global change very difficult and time consum...
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ISBN:
(纸本)3540200541
This paper focuses on the problem of scheduling outages to computer systems in complex distributed environments. The interconnected nature of these systems makes scheduling global change very difficult and time consuming, with a high degree of error. In addressing this problem, we describe the constraints on successful outage scheduling. Using these constraints, it describes a solution using constraint Logic programming, which is able to deliver rapid schedules for complex architectures. The developed approach is then applied and tested to several real world problems to ascertain its effectiveness and performance.
An extension of constraint logic programming that allows for weighted partial satisfaction of soft constraints is described and applied to the development of an automated timetabling system for Purdue University. The ...
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ISBN:
(纸本)3540406999
An extension of constraint logic programming that allows for weighted partial satisfaction of soft constraints is described and applied to the development of an automated timetabling system for Purdue University. The soft-constraint solver implemented in the proposed solution approach allows constraint propagation for hard constraints together with preference propagation for soft constraints. A new repair search algorithm is proposed to improve upon initially generated (partial) assignments of the problem variables. The model and search methods applied to the solution of the large lecture room component are presented and discussed along with the computational results.
constraint programming typically uses the technique of depth-first branch and bound as the method of solving optimization problems. Although this method can give the optimal solution, for large problems, the time need...
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constraint programming typically uses the technique of depth-first branch and bound as the method of solving optimization problems. Although this method can give the optimal solution, for large problems, the time needed to find the optimal can be prohibitive. This paper introduces a method for using local search techniques within a constraint programming framework, and applies this technique to vehicle routing problems. We introduce a constraint programming model for vehicle routing, and a system for integrating constraint programming and local search techniques. We then describe how the method can be accelerated by handling core constraints using fast local checks, while other more complex constraints are left to the constraint propagation system. We have coupled our local search method with a meta-heuristic to avoid the search being trapped in local minima. Several meta-heuristics are investigated ranging from a simple Tabu Search method to Guided Local Search. An empirical study over benchmark problems shows the relative merits of these techniques. Investigations indicate that the specific long-term memory technique used by Guided Local Search can be used as a diversification method for Tabu Search, resulting in significant benefit. Several new best solutions on the Solomon problems are found in relatively few iterations of our algorithm.
In this paper we show how to exploit in constraint programming (CP) a well-known integer programming technique, the additive bounding procedure, when using Limited Discrepancy Search (LDS). LDS is an effective search ...
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constraint programming is a technology which is now widely used to solve combinatorial problems in industrial applications. However, using it requires considerable knowledge and expertise in the field of constraint re...
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We are interested in Discrete Event Dynamic Systems and especially in Flexible Manufacturing Systems (FMS) and their production management. In order to master the combinatorial complexity, ive adopt steady, repetitive...
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We are interested in Discrete Event Dynamic Systems and especially in Flexible Manufacturing Systems (FMS) and their production management. In order to master the combinatorial complexity, ive adopt steady, repetitive and deterministic schedule. We have already determined an approach to compute this cyclic schedule (which corresponds to the steady state) while optimizing quantitative and qualitative performance criteria: cycle time (throughput), Work In Process, simplicity of the schedule. In order to apply this schedule ive consider and compute the transient periods to start and end the production. In a previous paper [9], ive gave a preliminary study of the transient states. We computed upper and lower bounds for the transient state, the steady state and the makespan then we established a method to optimize the makespan. In this paper, we recall some necessary assumptions and definitions for the study of the transient states then we give a heuristic for the computation and optimization of the makespan.
We propose an extension of concurrent constraint programming with primitives for process migration within a hierarchical network, and we study its semantics. To this purpose, we first investigate a "pure" pa...
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ISBN:
(数字)9783540449577
ISBN:
(纸本)3540677976
We propose an extension of concurrent constraint programming with primitives for process migration within a hierarchical network, and we study its semantics. To this purpose, we first investigate a "pure" paradigm for process migration, namely a paradigm where the only actions are those dealing with transmissions of processes. Our goal is to give a structural definition of the semantics of migration;namely, we want to describe the behaviour of the system, during the transmission of a process, in terms of the behaviour of the components. We achieve this goal by using a labeled transition system where the effects of sending a process, and requesting a process, are modeled by symmetric rules (similar to handshaking-rules for synchronous communication) between the two partner nodes in the network. Next, we extend our paradigm with the primitives of concurrent constraint programming and we show how to enrich the semantics to cope with the notions of environment and constraint store. Finally, we show how the operational semantics can be used to define an interpreter for the basic calculus.
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