Search results for "tabu"
showing 10 items of 180 documents
A computational study of LP-based heuristic algorithms for two-dimensional guillotine cutting stock problems
2002
In this paper we develop and compare several heuristic methods for solving the general two-dimensional cutting stock problem. We follow the Gilmore-Gomory column generation scheme in which at each iteration a new cutting pattern is obtained as the solution of a subproblem on one stock sheet. For solving this subproblem, in addition to classical dynamic programming, we have developed three heuristic procedures of increasing complexity, based on GRASP and Tabu Search techniques, producing solutions differing in quality and in time requirements. In order to obtain integer solutions from the fractional solutions of the Gilmore-Gomory process, we compare three rounding procedures, rounding up, t…
Datu transformāciju iespējas Oracle vidē
2016
Datu transformācijas ir laikietilpīgs process regulārajās ielādēs. Tām jānotiek ātri, noteiktās laika robežās. Uzņēmuma datu noliktavā tiek izstrādāts viens problēmas risinājums, nevis vairāki, izvēloties ātrdarbīgāko, tāpēc autors apskata vairākas transformāciju alternatīvas 4 problēmu risināšanai: 1. Hierarhisko datu vairāku līmeņu attēlošanai rindā; 2. Hierarhisko slēguma datu attēlošana rindā; 3. Divu vēstures tabulu apvienošana ar pārklājošiem periodiem 4. Vēstures tabulas vispārināšana, pārrēķinot sākuma un beigu datumus. Praktiskajā daļā katrai no problēmām tika atrasti/izstrādāti, aprakstīti un salīdzināti 2 – 3 risinājumi, starp kuriem noteikts ātrākais izpildes laiks attiecīgās pr…
A model for designing callable bonds and its solution using tabu search
1997
Abstract We formulate the problem of designing callable bonds as a non-linear, global, optimization problem. The data of the model are obtained from simulations of holding-period returns of a given bond design, which are used to compute a certainty equivalent return, viz., some target assets. The design specifications of the callable bond are then adjusted so that the certainty equivalent return is maximized. The resulting problem is multi-modal, and a tabu search procedure, implemented on a distributed network of workstations, is used to optimize the bond design. The model is compared with the classical portfolio immunization model, and the tabu search solution technique is compared with s…
Mixed heuristic-non linear optimization of energy management for hydrogen storage-based multi carrier hubs
2014
In this paper, an heuristic and non-linear programming based algorithm to optimally operate an energy hub plant is proposed. The energy hub plant described in this work is the test system for the European INGRID research project. The Energy Management System defines the optimal energy flows dispatch in order to obtain the energy balance and the maximum profit for the owner of the plant. The problem is highly constrained and non-linear, for this reason the methodology cannot rely on Linear Programming (LP) methods. The Energy Management System manages two energy carriers, electricity and hydrogen, interfacing three distribution networks: the electricity, the hydrogen and the methane networks…
RutaRep: a computer package to design dispatching routes in the meat industry
2005
In this paper we present a computer program that has been developed to design the dispatching routes of a medium-sized meat company in Spain. We have modelled the real problem as a variant of the vehicle routing problem with Time Windows and implemented a number of heuristic algorithms based on the most advanced solution techniques for this problem. These algorithms have been embedded in a computer package that is intended to be used as a decision support system for the distribution manager. The program runs under Windows System and is straightforward to use. We also present some computational experiences based on real instances provided by the company. This experience shows important impro…
The Scatter Search Methodology
2011
Scatter search (SS) is an evolutionary approach for optimization. It has been applied to problems with continuous and discrete variables and with a single or multiple objectives. The success of SS as an optimization technique is well documented in a constantly growing number of journal articles and book chapters. This article first focuses on the basic SS framework, which is responsible for most of the outcomes reported in the literature, and then covers advanced elements that have been introduced in a few selected papers, such as the hybridization with tabu search, a well-known memory-based metaheuristic. We consider the maximum diversity problem to illustrate the search elements, methods …
Towards the design of organocatalysts for nerve agents remediation: The case of the active hydrolysis of DCNP (a Tabun mimic) catalyzed by simple ami…
2015
We report herein a study of the hydrolysis of Tabun mimic DCNP in the presence of different amines, aminoalcohols and glycols as potential suitable organocatalysts for DCNP degradation. Experiments were performed in CD3CN in the presence of 5% D2O, which is a suitable solvent mixture to follow the DCNP hydrolysis. These studies allowed the definition of different DCNP depletion paths, resulting in the formation of diethylphosphoric acid, tetraethylpyrophosphate and phosphoramide species as final products. Without organocatalysts, DCNP hydrolysis occurred mainly via an autocatalysis path. Addition of tertiary amines in sub-stoichiometric amounts largely enhanced DCNP depletion whereas non-te…
"La construction du personnage dans les derniers récits de Raffaele La Capria"
2018
C’est à la fin des années soixante-dix, au moment où d’anciens protagonistes des avant-gardes littéraires (comme Sollers en France ou Eco en Italie) renouent avec la fiction, que Raffaele La Capria, l’un des précurseurs dans la péninsule du roman expérimental, renonce définitivement au genre. Amore e Psiche, publié pour la première fois en 1973, fera l’objet de plusieurs remaniements sans que l’auteur en soit jamais satisfait. À partir des années quatre-vingt, La Capria ne publie plus que des...
Hybrid Genetic Algorithms in Data Mining Applications
2009
Genetic algorithms (GAs) are a class of problem solving techniques which have been successfully applied to a wide variety of hard problems (Goldberg, 1989). In spite of conventional GAs are interesting approaches to several problems, in which they are able to obtain very good solutions, there exist cases in which the application of a conventional GA has shown poor results. Poor performance of GAs completely depends on the problem. In general, problems severely constrained or problems with difficult objective functions are hard to be optimized using GAs. Regarding the difficulty of a problem for a GA there is a well established theory. Traditionally, this has been studied for binary encoded …
Principles of scatter search
2006
Scatter search is an evolutionary method that has been successfully applied to hard optimization problems. The fundamental concepts and principles of the method were first proposed in the 1970s, based on formulations dating back to the 1960s for combining decision rules and problem constraints. In contrast to other evolutionary methods like genetic algorithms, scatter search is founded on the premise that systematic designs and methods for creating new solutions afford significant benefits beyond those derived from recourse to randomization. It uses strategies for search diversification and intensification that have proved effective in a variety of optimization problems. This paper provides…