1,583 research outputs found
Analysis and Optimization of Mixed-Criticality Applications on Partitioned Distributed Architectures
A tabu search algorithm for dynamic routing in ATM cell-switching networks
This paper deals with the dynamic routing problem in ATM cell-switching networks. We present a
mathematical programming model based on cell loss and a Tabu Search algorithm with short-term
memory that is reinforced with a long-term memory procedure. The estimation of the quality of the
solutions is fast, due to the specific encoding of the feasible solutions. The Tabu Search algorithm reaches
good quality solutions, outperforming other approaches such as Genetic Algorithms and the Minimum
Switching Path heuristic, regarding both cell loss and the CPU time consumption. The best results were
found for the more complex networks with a high number of switches and links
Combined Intra- and Inter-domain Traffic Engineering using Hot-Potato Aware Link Weights Optimization
A well-known approach to intradomain traffic engineering consists in finding
the set of link weights that minimizes a network-wide objective function for a
given intradomain traffic matrix. This approach is inadequate because it
ignores a potential impact on interdomain routing. Indeed, the resulting set of
link weights may trigger BGP to change the BGP next hop for some destination
prefixes, to enforce hot-potato routing policies. In turn, this results in
changes in the intradomain traffic matrix that have not been anticipated by the
link weights optimizer, possibly leading to degraded network performance.
We propose a BGP-aware link weights optimization method that takes these
effects into account, and even turns them into an advantage. This method uses
the interdomain traffic matrix and other available BGP data, to extend the
intradomain topology with external virtual nodes and links, on which all the
well-tuned heuristics of a classical link weights optimizer can be applied. A
key innovative asset of our method is its ability to also optimize the traffic
on the interdomain peering links. We show, using an operational network as a
case study, that our approach does so efficiently at almost no extra
computational cost.Comment: 12 pages, Short version to be published in ACM SIGMETRICS 2008,
International Conference on Measurement and Modeling of Computer Systems,
June 2-6, 2008, Annapolis, Maryland, US
Recent Advances in Graph Partitioning
We survey recent trends in practical algorithms for balanced graph
partitioning together with applications and future research directions
Planning of remote laser welding processes
The paper discusses the technical background of the remote laser welding (RLW) technology, its novel opportunities and implications for planning processes. Our ultimate goal is to develop a complete off-line programming toolbox for RLW which can provide an automated method for computing close-to-optimal robot programs. We suggest a workflow for the complete planning process, and propose new models and algorithms for solving the sequencing of welding tasks in conjunction with path planning, as well as for generating the inverse kinematics of the robot. The paper summarizes results of first computational experiments in an automotive case study using an industrial robot. The proposed method leads to a substantial reduction in the cycle time of the welding operation compared to an earlier approach
Optimal QoS aware multiple paths web service composition using heuristic algorithms and data mining techniques
The goal of QoS-aware service composition is to generate optimal composite services that satisfy the QoS requirements defined by clients. However, when compositions contain more than one execution path (i.e., multiple path's compositions), it is difficult to generate a composite service that simultaneously
optimizes all the execution paths involved in the composite service at the same time while meeting the QoS requirements. This issue brings us to the challenge of solving the QoS-aware service composition problem, so called an optimization problem. A further research challenge is the determination of the QoS characteristics that can be considered as selection criteria. In this thesis, a smart QoS-aware service composition approach is proposed. The aim is to solve the above-mentioned problems via an optimization mechanism based upon the combination between runtime path prediction method and heuristic algorithms. This mechanism is performed in two steps. First, the runtime path prediction method predicts, at runtime, and just before the actual composition, execution, the execution path that will potentially be executed. Second, both the constructive procedure (CP) and the complementary procedure (CCP) heuristic algorithms computed the optimization considering only the execution path that has been predicted by the runtime path
prediction method for criteria selection, eight QoS characteristics are suggested after
investigating related works on the area of web service and web service composition. Furthermore, prioritizing the selected QoS criteria is suggested in order to assist clients when choosing the right criteria. Experiments via WEKA tool and simulation prototype were conducted to evaluate the methods used. For the runtime path prediction method, the results showed that the path prediction method achieved promising prediction accuracy, and the number of paths involved in the prediction did not affect the accuracy. For the optimization mechanism, the evaluation was conducted by comparing the mechanism with relevant optimization techniques. The simulation results showed that the proposed optimization mechanism outperforms the relevant optimization techniques by (1) generating the highest overall QoS ratio solutions, (2) consuming the smallest computation time, and (3) producing the lowest percentage of constraints violated number
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