866 resultados para Vehicle routing problems with gains


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Membrane systems are parallel and bioinspired systems which simulate membranes behavior when processing information. As a part of unconventional computing, P-systems are proven to be effective in solvingcomplexproblems. A software technique is presented here that obtain good results when dealing with such problems. The rules application phase is studied and updated accordingly to obtain the desired results. Certain rules are candidate to be eliminated which can make the model improving in terms of time.

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Expert systems for decision support have recently been successfully introduced in road transport management. In this paper, we apply three state-of-the art ILP systems to learn how to detect traffic problems.

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We show a cluster based routing protocol in order to improve the convergence of the clusters and of the network it is proposed to use a backup cluster head. The use of a event discrete simulator is used for the implementation and the simulation of a hierarchical routing protocol called the Backup Cluster Head Protocol (BCHP). Finally it is shown that the BCHP protocol improves the convergence and availability of the network through a comparative analysis with the Ad Hoc On Demand Distance Vector (AODV)[1] routing protocol and Cluster Based Routing Protocol (CBRP)[2]

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As it is well known B.E.M. works efficiently in the treatment of a bread class of potential and elasticity problems. In this paper we present the results of several runs established with linear elements in plane potential theory and treating the importance of singularities and the pattern and size of elements used in the boundary discretization.

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In this paper we propose a novel fast random search clustering (RSC) algorithm for mixing matrix identification in multiple input multiple output (MIMO) linear blind inverse problems with sparse inputs. The proposed approach is based on the clustering of the observations around the directions given by the columns of the mixing matrix that occurs typically for sparse inputs. Exploiting this fact, the RSC algorithm proceeds by parameterizing the mixing matrix using hyperspherical coordinates, randomly selecting candidate basis vectors (i.e. clustering directions) from the observations, and accepting or rejecting them according to a binary hypothesis test based on the Neyman–Pearson criterion. The RSC algorithm is not tailored to any specific distribution for the sources, can deal with an arbitrary number of inputs and outputs (thus solving the difficult under-determined problem), and is applicable to both instantaneous and convolutive mixtures. Extensive simulations for synthetic and real data with different number of inputs and outputs, data size, sparsity factors of the inputs and signal to noise ratios confirm the good performance of the proposed approach under moderate/high signal to noise ratios. RESUMEN. Método de separación ciega de fuentes para señales dispersas basado en la identificación de la matriz de mezcla mediante técnicas de "clustering" aleatorio.

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In this paper we present a recurrent procedure to solve an inversion problem for monic bivariate Krawtchouk polynomials written in vector column form, giving its solution explicitly. As a by-product, a general connection problem between two vector column of monic bivariate Krawtchouk families is also explicitly solved. Moreover, in the non monic case and also for Krawtchouk families, several expansion formulas are given, but for polynomials written in scalar form.

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Heuristics for stochastic and dynamic vehicle routing problems are often kept relatively simple, in part due to the high computational burden resulting from having to consider stochastic information in some form. In this work, three existing heuristics are extended by three different local search variations: a first improvement descent using stochastic information, a tabu search using stochastic information when updating the incumbent solution, and a tabu search using stochastic information when selecting moves based on a list of moves determined through a proxy evaluation. In particular, the three local search variations are designed to utilize stochastic information in the form of sampled scenarios. The results indicate that adding local search using stochastic information to the existing heuristics can further reduce operating costs for shipping companies by 0.5–2 %. While the existing heuristics could produce structurally different solutions even when using similar stochastic information in the search, the appended local search methods seem able to make the final solutions more similar in structure.

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On 11 October, the top executives of ten European energy companies, which jointly own about half of the European Union’s electricity generating capacity, warned that “energy security is no longer guaranteed” and once again called for changes to EU energy policy. Due to persistent adverse conditions in the energy market (linked to, for example, the exceptionally low wholesale energy prices) more and more conventional power plants are being closed down. According to sector representatives, this could lead to energy shortages being seen as early as this winter. Meanwhile, in an interview with The Daily Telegraph published in September of this year, the European industry commissioner Antonio Tajani warned – in a rather alarmist tone – of the disastrous consequences the rising energy prices could have on European industry. Amongst the reasons for the high prices of energy, Tajani mentioned the overambitious pace and methods used to increase the share of renewables in the sector. In a similar vein, EU President Herman Van Rompuy has highlighted the need to reduce energy costs as a top priority for EU energy policy1. The price of energy has become one of the central issues in the current EU energy debate. The high consumer price of energy – which has been rising steadily over the past several years – poses a serious challenge to both household and industrial users. Meanwhile, the declining wholesale prices are affecting the cost-effectiveness of energy production and the profits of energy companies. The current difficulties, however, are first and foremost a symptom of much wider problems related to the functioning of both the EU energy market as well as to the EU’s climate and energy policies.

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National Highway Traffic Safety Administration, Washington, D.C.

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"Grant no. US NSF MCS75-21758."

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At head of title: International labour office.