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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
211

Avaliação de uma metodologia para restabelecimento de energia baseada em algoritmos evolutivos multi-objetivos no sistema de distribuição de energia da COPEL na cidade de Londrina / Evaluation of a methodology for service restoration based on multi-objective evolutionary algorithms for Copel distribution system in Londrina city

Marcos Henrique Marçal Camillo 12 September 2013 (has links)
Desenvolver um sistema de distribuição de energia confiável é certamente um desafio inerente aos profissionais do setor elétrico. Porém, os sistemas estão sujeitos a falhas e, sendo assim, o rápido restabelecimento traz a satisfação do cliente e reduz as compensações pagas pelas concessionárias de energia. Neste contexto a presente dissertação visa avaliar a metodologia para restabelecimento de energia denominada AEMT-H que se baseia em algoritmos evolutivos multi-objetivo se na estrutura de dados chamada Representação Nó- Profundidade (RNP). Esta avaliação ocorrerá através da aplicação do AEMT-H para obtenção de planos de restabelecimento de energia após a ocorrência de faltas simples no sistema COPEL da cidade de Londrina. Os resultados gerados serão avaliados estatisticamente e ainda subjetivamente pelos profissionais do COD da concessionária. Os algoritmos evolutivos têm apresentado resultados animadores para os problemas de restabelecimento de energia. Em especial, os resultados obtidos, quando da representação computacional de sistemas de distribuição de grande porte (com milhares de barras e chaves) através da RNP, possuem como característica o tempo de resposta da ordem de segundos, instigando a evolução das pesquisas para utilização desta metodologia inclusive em aplicativos de tempo real. O sistema de Londrina possui 30.156 barras, 2.660 chaves \"NF\", 250 chaves \"NA\" e atende um universo de mais de 231.000 consumidores ligados diretamente ao sistema de 13,8 kV ou, após os transformadores de distribuição, nas tensões de 220V e 127V. Neste sistema estão presentes 6 subestações 138 kV/13,8 kV e 64 circuitos alimentadores, totalizando uma capacidade de transformação de energia de 541,7 MVA. / The development of a reliable distribution system is certainly a challenge to electrical industry professionals. However, these systems are subject to failures and thus the fast restoration brings customer satisfaction and reduces the compensation paid by the electricity utilities. In this context, this dissertation aims to evaluate the methodology for service restoration called \"AEMT-H\", which is based on multi-objective evolutionary algorithms and in the data structure called Node Depth Encoding (NDE). This evaluation will occur by applying the \"AEMT-H\" to obtain service restoration plans considering the occurrence of simple faults in the COPEL system of the city of Londrina. The obtained results will bee valuated statistically and subjectively by professionals of the Distribution Operation Center. It is important to highlight that Evolutionary algorithms have shown promising results to treat the service restoration problem in distribution systems. In particular, the results obtained when using NDE tocomputationally represent the electrical topology of large distribution systems (with thousand of buses and switchers) are very interesting in terms of time processing (in the order of seconds). The system of Londrina has 30,156 buses, 2,660 switchers normally closed, 250 switchers normally opened and supplies a universe of more than 231,000 consumers connected directly to the system with voltage of 13.8 kV or, after distribution transformers, with voltages of 220V and 127V. This system contains 6 substations 138 kV/13,8 kV and 64 feeders, and a installed power of 541.7 MVA.
212

Sistema inteligente para alocação eficiente de dispositivos indicadores de falta em alimentadores de distribuição / An intelligent system for efficient allocation of fault indicators in distribution feeders

Wesley Fernando Usida 22 August 2011 (has links)
Os dispositivos Indicadores de Faltas (IFs) contribuem para a melhoria do processo de localização de faltas em alimentadores de distribuição e, consequentemente, para a qualidade do fornecimento de energia elétrica. Todavia, a grande dificuldade de se aplicar tais dispositivos em larga escala está na escassez de metodologias eficientes que apontem em quais pontos do sistema de distribuição eles devem ser instalados. Por isso, o presente trabalho propõe uma abordagem computacional evolutiva capaz de alocar dispositivos IFs em alimentadores primários de distribuição de energia elétrica. De forma mais específica, o problema de se obter o melhor local de instalação é solucionado por meio da técnica de Algoritmos Genéticos (AGs), que busca obter uma configuração eficiente de instalação de IFs no tronco principal do alimentador de distribuição. A metodologia proposta é aplicada a dois alimentadores reais. Aspectos de viabilidade técnica e financeira dos IFs também são analisados. Os resultados apresentados comprovam a eficiência da metodologia proposta. / Fault Indicator (FIs) devices have contributed to improve the location of faults on primary feeders, and consequently the reliability of distribution systems. However, one of the main problems facing their installation in a large scale in a distribution system is the lack of efficient methods to analyze big networks and to pinpoint exactly on which buses these devices should be placed. Thus, this paper proposes an evolutionary computing strategy to solve the problem of fault indicator placement in primary distribution feeders. Specifically, a genetic algorithm (GA) is employed to search for an efficient configuration of FIs, located at the best positions in the main feeder. The proposed methodology was applied in two actual distribution feeders. Technical and financial viability aspects are also analyzed. Finally, the results confirm the efficiency of the GA approach to the FI placement problem.
213

Modelos de otimização para avaliação de investimentos em redes de distribuição de energia elétrica considerando índices de confiabilidade / Optimization models for evaluation of investiment in electrical distribution network considering indexes reliability

Caetano, Ana Paula Pereira Tsuyuguchi 20 March 2015 (has links)
Made available in DSpace on 2017-07-10T17:11:49Z (GMT). No. of bitstreams: 1 Ana Paula P T Caetano 2.pdf: 4372875 bytes, checksum: b5eda892daea23dd9f2cf33a7a4045c5 (MD5) Previous issue date: 2015-03-20 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The simulation results obtained using three models which minimize the distribution system reliability indexes and investment through sectionalizing switches allocation and/ or installation of tie lines are presented in this work. This is a problem with conflicting goals that were simultaneously minimized through a multi-objective Genetic Algorithm (Non- Dominated Sorting Genetic Algorithm II - NSGA II), seeking trade-off solutions between investment costs and network reliability. As constraints, the continuity indexes (DEC and FEC) and the power flow of the system were considered. The three models presented have two objective functions, being the first one the investment cost (CINV) of allocated equipment. The second function is one of three reliability indexes: Cost of Energy not Supplied (CENS), DEC and FEC. In the first model (CINV and CENS), results with higher quantities of sectionalizing switches allocation were found, so it was the model which presented higher investment costs. In the second model (CINV and DEC) results presenting lower values for the DEC were found, comparing with the first model, and lower investment cost, but the total cost were similar to those of the first model, since it has an increased CENS. The third model (CINV and FEC) was the model which allocated less sectionalizing switches and presented lower investment costs, since the allocation of these devices do not influence the minimization of FEC, only the allocation of tie lines change the system configuration influencing the FEC. All results obtained through the models met the expectations of finding a set of diverse solution considering the constraints. / Neste trabalho foram apresentados e analisados os resultados obtidos de três modelos matemáticos que minimizam indicadores de confiabilidade do sistema de distribuição e custo de investimento através da alocação de chaves seccionadoras e/ou instalação de ramais de interconexão. Trata-se de um problema com objetivos conflitantes que foram minimizados simultaneamente através de um algoritmo genético multiobjetivo (Non-Dominated Sorting Genetic Algorithm II NSGA II), buscando soluções com bons compromissos (trade-off) entre o custo de investimento e a confiabilidade da rede. Foram considerados como restrições os indicadores de continuidade (DEC e FEC) e o fluxo de potência do sistema. Os três modelos apresentados possuem duas funções objetivos, uma das funções representa o custo de investimento (CINV) dos equipamentos alocados e a outra função é um indicador de confiabilidade, sendo que foram adotados o custo de energia não suprida (CENS) e os indicadores DEC e FEC respectivamente ao primeiro, segundo e terceiro modelo. No primeiro modelo (CENS e CINV) foram encontrados resultados com maior quantidade de alocação de chaves, deste modo foi o modelo que apresentou maiores custos de investimentos. No segundo modelo (DEC e CINV) foram encontrados resultados com menores valores para o DEC em relação ao primeiro modelo e com menor custo de investimento, porém com custo total aproximados dos valores do primeiro modelo, visto que tiveram um aumento do CENS. O terceiro modelo (FEC e CINV) foi o modelo que menos alocou chaves seccionadoras e apresentou menores custos de investimento, uma vez que a alocação destes dispositivos não influencia na minimização do FEC, somente a alocação dos ramais de interconexão que alteram a configuração do sistema influenciando no FEC. Todos os resultados obtidos nos modelos atenderam às expectativas de encontrar um conjunto de solução diversificado respeitando as restrições impostas.
214

Characterization of bacterial diversity in three oligotrophic environments using high-throughput sequencing technology / Caractérisation de la diversité bactérienne dans trois environnements oligotrophes en utilisant la technologie de séquençage à haut débit.

An, Shu 07 September 2012 (has links)
Les milieux oligotrophes sont pauvres en éléments nutritifs. En utilisant la technologie de séquençage à haut débit, on a étudié la diversité bactérienne dans trois environnements oligotrophes différents, y compris A. sâbles du désert, B. sâbles dans les tempêtes de l'Asie et C. l’eau et biofilms dans les réseaux de distribution d'eau potable.A. Le désert représente 30% de la surface de la terre. Les conditions de vie dans ces environnements sont un réel défi pour les micro-organismes à cause de nombreux facteurs limitants : peu d’eau et/ou de carbone disponible, une variation importante de température et une forte exposition aux irradiations UV. Le but de cette recherche est donc d’étudier la diversité bactérienne à la surface du sable du désert Taklemaken et du désert de Gobi en utilisant la technologie de séquençage à haut débit. Nos résultats ont révélé une grande diversité bactérienne dans le sol du désert comparable à d'autres types de sols. En outre, nous avons observé une corrélation positive entre la richesse bactérienne et le rapport C/N du sol.B. Les tempêtes de sable d'Asie se produisent presque toujours au printemps, elles sont générées dans les régions arides d'Asie telles que le désert Taklamaken et le désert de Gobi. L'arrivée des tempêtes de sable pourrait largement modifier l'environnement de l'air dans ces régions sous l’effet du vent, surtout dans les villes asiatiques qui sont le plus souvent touchées. Nos travaux visent à étudier la modification de la composition et la diversité des bactéries associées aux particules au moment de tempête de sable en Asie par la technologie de séquençage à haut débit. Nos résultats ont démontré que les compositions des bactéries associées aux particules sont modifiées pendant les tempêtes, en particulier, la proportion des Proteobacteria qui augmentent les jours de tempête. Nous avons signalé neuf genres bactériens détectés en plus pendant les jours de tempêtes, cela nécessite des études plus approfondies.C. Après avoir analysé la population bactérienne dans les tempêtes de sable, et celles des déserts, nous poursuivons notre objectif de recherche à un environnement aquatique. Nous avons suivi le flux d'eau provenant de l'usine d'Orly (DW-A) à l'entrée du réservoir (DW-B), et à la sortie du réservoir (DW-C). Nous avons constaté une forte variation de la communauté bactérienne, dans DW-A et DW-B, les bactéries prédominantes appartiennent aux populations des Betaproteobacteria, puis nous avons observé une conversion vers la population de Alphaproteobacteria dans DW-C. Le DW-C a montré une forte similitude avec un échantillon de biofilm (BF-C), ce qui suggère l'effet important du biofilm sur la modification des communautés bactériennes dans l'eau lors de la distribution. / Oligotrophic ecosystems can be loosely defined as environments that exhibit low ambient nutrient levels. During my thesis, I used 454 DNA pyrosequencing of partial 16S rDNA to explore the bacterial diversity in three different oligotrophic environments, including A. surface desert soil, B. Asian sandstorm dust and C. a section of the city of Paris’s drinking water distribution system.A. Arid regions represent nearly 30% of the Earth’s terrestrial surface. The living conditions at the surface of deserts are a challenge for microorganisms, as there is little available water and/or carbon, a very large range of temperatures and high exposure to UV irradiation from the Sun. In surface sand samples from two large Asian deserts, unexpectedly large bacterial diversity residing was revealed. Sequences belonging to the Firmicutes, Proteobacteria, Bacteroidetes and Actinobacteria phyla were the most abundant. An increase in phylotype numbers with increasing C/N ratio was noted, suggesting a possible role in the bacterial richness of these desert sand environments.B. Desert sandstorms are a meteorological phenomenon which have been postulated affect the Earth's climate and public health. We examined the particle-associated (dust and sand-associated) bacterial populations of atmospheric sand in the absence (as control) and presence of sandstorms in five Asian cities. Greater than 90% of the sequences can be classified as representing bacteria belonging to four phyla: Proteobacteria, Bacteriodetes, Actinobacteria and Firmicutes. Principal component analyses showed that the sandstorm-associated bacterial populations were clustered by sampling year, rather than location. Members belonging to nine bacterial genera (Massilia, Planococcus, Carnobacterium, Planomicrobium, Pontibacter, Pedobacter, Lysobacter, Sanguibacter, Ohtaekwangia) were observed to increase in sand-associated samples from sandstorms, versus the controls. C. We characterized the bacterial communities in three water and three biofilm samples from one part of the Parisian drinking water distribution system. A dramatic change in bacterial population in the water during flow through the distribution system from the water treatment plant to the exit from the reservoir was found. The richness of the bacterial population was reduced from the water treatment plant to the reservoir (from 336 to 165 OTUs for water samples leaving the reservoir and from 947 to 275 for biofilm samples in the network). Several OTUs belonging to pathogenic genera were detected in our samples, mostly in the biofilm samples, thus suggesting that the biofilms may be an important source of bacteria during water distribution to the consumers.
215

Algoritmos evolutivos multi-objetivo para reconfiguração de redes em sistemas de distribuição de energia elétrica / Multi-objective evolutionary algorithm for network reconfiguration in distribution systems

Sanches, Danilo Sipoli 14 January 2013 (has links)
Encontrar a configuração de mínimas perdas ôhmicas ou que forneça um adequado plano de restabelecimento aptos a ocorrência de faltas permanentes são problemas de natureza combinatorial, com múltiplos objetivos e restrições, que envolvem funções cujas características, em geral, dificultam o uso de técnicas de programação matemática. Algoritmos Evolutivos têm apresentado resultados animadores para esses problemas, especialmente quando aplicados em sistemas de distribuição de grande porte. Neste trabalho são propostas duas novas metodologias, baseadas em Algoritmos Evolutivos Multi-Objetivo, para reconfiguração de redes em sistemas de distribuição, que podem ser aplicadas para o tratamento dos problemas de redução de perdas ôhmicas e restabelecimento de energia em sistemas de grande porte (com milhares de barras, linhas e chaves). Para o desenvolvimento dessas metodologias, foi utilizado uma estrutura de dados para manipular grafos produzindo exclusivamente configurações radiais e conexas, chamada Representação Nó-profundidade. As metodologias propostas foram testadas para diversos sistemas, dentre os quais destaca-se um com 30:880 barras, tendo sido satisfatórios os resultados obtidos. Para o problema de restabelecimento de energia foram testados falta única e múltiplas faltas. / Find the distribution system configuration of minimum power losses or that provides an adequate service restoration plan is a combinatorial, multi-objective and multi constraint problems, which involves functions whose characteristics, in general, difficult the use of mathematical programming techniques. Evolutionary Algorithms have shown relevant results for these problems, especially for Large-Scale Distribution Systems. This work proposes two methodologies for network reconfiguration based on Multi-Objective Evolutionary Algorithms, which can be applied to treat the problems of power loss reduction and service restoration in large scale distribution systems (with thousands of buses, lines and switches). In order to develop these methodolgies, it was used a data structure to manipulate graphs producing exclusively radial and connected connections, called Node Depth Encoding. The proposed methodologies were successfully tested in several distribution systems, among them one with 30,880 buses. The problem of service restoration is analyzed considering cases of single and multiple faults.
216

Optimal Allocation Of Sectionalizing Switches In Rural Distribution Systems

Daldal, Mustafa 01 February 2012 (has links) (PDF)
The distribution system which forms the final connection between customers and power source plays a vital role in an electrical network. Different studies show that substantial proportion of the customer interruptions occurs due to the failures on distribution network. The ongoing privatization process of the electrical distribution services in Turkey raises the importance of reliable and continuous electricity supply significantly. The new regulations come up with this privatization process and the electrical distribution companies are strictly required to comply with these regulations to ensure the reliability of the distribution network. The legal framework and severe punishments applied to the electrical distribution companies exceeding the continuity of supply indices force them to invest on their network in order to increase the reliability of their system. As the reliability of electricity supplied increases, investment cost also increases. However, low system reliability causes higher outage frequency and duration which will increase the damage of these outages to customers and also increases the cost of the distribution company as a result of the penalty payments. This tradeoff between Outage Cost and Utility Cost requires consideration of an optimization when determining the optimal reliability level. In rural areas where electrical distribution network consists of long radial overhead lines in arborescent structure, continuity of supply is a major problem due to the high failure rates. The implementation of protection devices having reclosing capability and automated sectionalizing switches enhances the continuity of supply on rural networks substantially. The balance between the cost associated with installation of switches and the reduction on Outage Cost is an important optimization issue for distribution network operators. In this thesis study an algorithm is developed in order to determine the optimum number and locations of the sectionalizing switches on a rural electrical distribution network in Turkey which gives an optimum investment level with an optimum Outage Cost.
217

Efficient city logistics : Can travel patterns of goods and people be intertwined?

Merkel, Pontus January 2015 (has links)
Optimizing city logistics is a topic of great importance for big cities today. Even though the environmental- and economical consequences of the increasing goods transportation fleet has been present for quite some time, actions from affected stakeholders has not been taken until just recently.  In this brief 9 week project the aim has been to,  from a design point-of-view, in this complex topic, give a suggestion and raise a discussion onto how goods transportation in cities can be made in the future.  The basic idea is to get the consignments as close to the consignees and their travel patterns as possible. Public transportation networks are an existing grid where people are moving around and can potentially be used for combined transport of goods and people. The outcome of this concept is focusing on light parcel delivery towards private consignees, due to the increasing e-commerce trend. By using small transporter vehicles connected to buses, light parcels can be distributed throughout a city and easily accessible for consignees at the bus stops.  The transporter vehicle developed through this project aims to conceptualize connectivity and integration between mobility and parcel delivery services, to ease the every day life of urban citizens as well as decrease the environmental- and economical impacts which the distribution vehicle-fleet of today entails.  The design of the transporter vehicle is an interpretation of how a autonomous distribution vehicle can look like in a future city environment where the integration of public-utility-vehicles is of greater importance.
218

Characterization of bacterial diversity in three oligotrophic environments using high-throughput sequencing technology

An, Shu 07 September 2012 (has links) (PDF)
Oligotrophic ecosystems can be loosely defined as environments that exhibit low ambient nutrient levels. During my thesis, I used 454 DNA pyrosequencing of partial 16S rDNA to explore the bacterial diversity in three different oligotrophic environments, including A. surface desert soil, B. Asian sandstorm dust and C. a section of the city of Paris's drinking water distribution system.A. Arid regions represent nearly 30% of the Earth's terrestrial surface. The living conditions at the surface of deserts are a challenge for microorganisms, as there is little available water and/or carbon, a very large range of temperatures and high exposure to UV irradiation from the Sun. In surface sand samples from two large Asian deserts, unexpectedly large bacterial diversity residing was revealed. Sequences belonging to the Firmicutes, Proteobacteria, Bacteroidetes and Actinobacteria phyla were the most abundant. An increase in phylotype numbers with increasing C/N ratio was noted, suggesting a possible role in the bacterial richness of these desert sand environments.B. Desert sandstorms are a meteorological phenomenon which have been postulated affect the Earth's climate and public health. We examined the particle-associated (dust and sand-associated) bacterial populations of atmospheric sand in the absence (as control) and presence of sandstorms in five Asian cities. Greater than 90% of the sequences can be classified as representing bacteria belonging to four phyla: Proteobacteria, Bacteriodetes, Actinobacteria and Firmicutes. Principal component analyses showed that the sandstorm-associated bacterial populations were clustered by sampling year, rather than location. Members belonging to nine bacterial genera (Massilia, Planococcus, Carnobacterium, Planomicrobium, Pontibacter, Pedobacter, Lysobacter, Sanguibacter, Ohtaekwangia) were observed to increase in sand-associated samples from sandstorms, versus the controls. C. We characterized the bacterial communities in three water and three biofilm samples from one part of the Parisian drinking water distribution system. A dramatic change in bacterial population in the water during flow through the distribution system from the water treatment plant to the exit from the reservoir was found. The richness of the bacterial population was reduced from the water treatment plant to the reservoir (from 336 to 165 OTUs for water samples leaving the reservoir and from 947 to 275 for biofilm samples in the network). Several OTUs belonging to pathogenic genera were detected in our samples, mostly in the biofilm samples, thus suggesting that the biofilms may be an important source of bacteria during water distribution to the consumers.
219

Evaluering av det lovbaserte legefordelingssystemet i Norge i perioden 1999 til 2013 / Evaluation of the government-regulated physician distribution systemin Norway,1999–2013

Østraa, Inger Elisabeth January 2014 (has links)
Formål:Hensikten med studien er å undersøke hvilken effekt det lovbaserte legefordelingssystemet, som var aktivt i Norge fra 1.1.1999 til 30.6.2013, har hatt, og hvordan ordningen har påvirket utviklingen i legestillinger i primærhelsetjenesten og spesialisthelsetjenesten i Norge. Studien kan gi myndighetene et bedre kunnskapsgrunnlag om statlig regulering av legestillinger. Metode: Forskningsspørsmålene er i hovedsak belyst gjennom kvantitative deskriptive analyser av registerdata og tilgjengelig statistikk. Saksdokumenter og vedtak om tildeling av legestillinger er gjennomgått, og det er gjennomført en kvalitativ analyse av bakgrunnsdokumentene ved innføringen av ordningen. Den teoretiske rammen for studien er folkehelsearbeid, organisasjonsteori og resultatkjeden som et styringsverktøy ved gjennomføring av evalueringer. Resultat: Studienviser at nye legestillinger i primærhelsetjenesten har vært prioritert i hele perioden. Dette kan ha bidratt til å redusere sosiale ulikheter i helse. Antall ubesatte legestillinger er i perioden 1.1.1999 til 30.6.2013 redusert til under 1% av alle legestillinger, både i primærhelsetjenesten og spesialisthelsetjenesten. I samme periode økte antall utdanningsstillinger for leger i spesialisering med 36%. I alt 54% av alle nye legestillinger i spesialisthelsetjenesten er gitt innen nasjonale satsningsområder og prioriterte spesialiteter. Av de nordiske landene har Norge hatt høyest økningen i legedekning pr 1000 innbyggere i allmennlegetjenesten. Konklusjon: Studien viser at den statligereguleringenav nye legestillinger har hatt en effekt, og at et målrettet reguleringssystem kan være et godt administrativt virkemiddel for nasjonal legefordeling og geografisk fordeling av leger. God forankring og bred deltaking er suksesskriterier. / Purpose: This study aimedto investigate the effect of the legally based system for allocating new positions for physiciansunder a policy that wasin effectin Norway between 1 January 1999 and 30 June 2013.The study also aimed to increase understanding of a government-regulated physician distribution system. Method: The primary methodology involved using quantitative descriptive analysis to review registry data and available statistics. Case documents and decisions related to theallocation of physician positions, and case and policy documents related to the original justification for the government-regulated physician distribution systemw ere also reviewed. The theoretical thesis and framework for this study is public health, organization theory, and the "result chain" as a management tool for executing evaluations and deliberations. Result: Theresults of the study show that vacant positions for physicians, both primary and specialists, decreased to less than 1% during the study period. During this same time period, 54% of all new hospital positions were assigned a priority specialty. Positions for specialist education increased 36%. Among the Nordic countries, Norway had the highest increase in coverage by primary care physiciansper 1,000 capita during the past 15 years. Conclusion:The government-regulated physician distribution systemin Norway has been effective. Robustness, consensus building, and broad participation are key conditions and ingredients in the recipe for success. / <p>ISBN 978-91-982282-2-9</p>
220

Multi Item Integrated Location/inventory Problem

Balcik, Burcu 01 January 2003 (has links) (PDF)
In this study, the design of a three-level distribution system is considered in which a single supplier ships a number of items to the retailers via a set of distribution centers (DC) and stochastic demand is observed at the retailers. The problem is to specify the number and location of the DCs, and the assignment of the retailers to the DCs in such a way that total facility, transportation, safety stock, and joint ordering and average inventory costs are minimized, and customer service requirements are satisfied. Single source constraints are imposed on the assignment of the retailers to the DCs. The integrated location/inventory model incorporates the inventory management decisions into the strategic location/allocation decisions by considering the benefits of risk pooling and the savings that result in the joint replenishment of a group of items. We develop two heuristic methods to solve the non-linear integer-programming model in an integrated way: (1) Improvement type heuristic, (2) Constructive type heuristic. The heuristic algorithms are tested on a number of problem instances with 81 demand points (retailers) and 4 different types of items. Both of the heuristics are able to generate solutions in very reasonable times. The results are compared to the results of the p-median problem and found that the total cost and the number of DCs can be lowered using our integrated model instead of the p-median problem. Finally, sensitivity analysis is performed with respect to the changes in inventory, transportation, and ordering cost parameters, and variability of the demand.

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