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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.
1

Northeast Asian containerised maritime logistics : supply chain collaboration, collaborative advantage and performance

Seo, Young-Joon January 2014 (has links)
This thesis aims to develop and validate the dimensions of supply chain collaboration and collaborative advantage in the containerised maritime industry and explores the impact of supply chain collaboration on collaborative advantage and port performance. Additionally, this thesis tests a mediation effect of collaborative advantage on the relationship between supply chain collaboration and port performance. This thesis employs a quantitative method. A theoretical model is built based on thorough literature reviews of supply chain management and maritime studies, in-depth discussions with experts, item review and Q-sorting techniques to signify ambiguity or misunderstanding with the scales and to suggest modifications. The proposed model is empirically tested with survey data using 178 responses from terminal operators, shipping lines, inland transport companies, freight forwarders, ship management companies and third-party logistics providers involved in maritime logistics in the major containers ports of Busan, Gwangyang and Incheon for a comprehensive and balanced view by using structural equation modelling. With regard to the findings of the empirical research, three main constructs were successfully validated as multi-dimensional constructs. The structural paths support hypotheses that supply chain collaboration has a positive influence on collaborative advantage, and collaborative advantage has a strong contribution to port performance. However, the direct impact of supply chain collaboration on port performance is insignificant. A hierarchical approach of the mediation test and bootstrapping test found that the association between supply chain collaboration and port performance is fully mediated by collaborative advantage. In other words, the greater degree of supply chain collaboration between the port and port user enables them to gain a higher degree of collaborative advantage, and, in turn, this collaborative advantage can contribute to augmenting port performance. This thesis synthesises transaction cost theory, resource based theory and a relational view to explain how supply chain collaboration influences collaborative advantage and port performance. Its theoretical contribution expands the concept of supply chain collaboration and collaborative advantage into containerised maritime contexts, capturing the perspective of the ports and port users. Further, despite numerous maritime studies which extol the importance of collaboration between the ports and port users, no systematic approach has previously developed and validated those constructs and relationships. The various maritime logistics organisations would benefit from applying the results of this study to their supply chain collaboration practices when seeking greater collaborative advantage. The results heed practitioners in containerised maritime logistics organisations to focus on balancing the facets of supply chain collaboration to transport flows of containers seamlessly and efficiently from door-to-door, as supply chain management philosophy drives the maritime logistics industry to become more integrated into shippers' supply chains.
2

Optimization in maritime inventory routing

Papageorgiou, Dimitri Jason 13 November 2012 (has links)
The primary aim of this thesis is to develop effective solution techniques for large-scale maritime inventory routing problems that possess a core substructure common in many real-world applications. We use the term “large-scale” to refer to problems whose standard mixed-integer linear programming (MIP) formulations involve tens of thousands of binary decision variables and tens of thousands of constraints and require days to solve on a personal computer. Although a large body of literature already exists for problems combining vehicle routing and inventory control for road-based applications, relatively little work has been published in the realm of maritime logistics. A major contribution of this research is in the advancement of novel methods for tackling problems orders of magnitude larger than most of those considered in the literature. Coordinating the movement of massive vessels all around the globe to deliver large quantities of high value products is a challenging and important problem within the maritime transportation industry. After introducing a core maritime inventory routing model to aid decision-makers with their coordination efforts, we make three main contributions. First, we present a two-stage algorithm that exploits aggregation and decomposition to produce provably good solutions to complex instances with a 60-period (two-month) planning horizon. Not only is our solution approach different from previous methods discussed in the maritime transportation literature, but computational experience shows that our approach is promising. Second, building on the recent successes of approximate dynamic programming (ADP) for road-based applications, we present an ADP procedure to quickly generate good solutions to maritime inventory routing problems with a long planning horizon of up to 365 periods. For instances with many ports (customers) and many vessels, leading MIP solvers often require hours to produce good solutions even when the planning horizon is limited to 90 periods. Our approach requires minutes. Our algorithm operates by solving many small subproblems and, in so doing, collecting and learning information about how to produce better solutions. Our final research contribution is a polyhedral study of an optimization problem that was motivated by maritime inventory routing, but is applicable to a more general class of problems. Numerous planning models within the chemical, petroleum, and process industries involve coordinating the movement of raw materials in a distribution network so that they can be blended into final products. The uncapacitated fixed-charge transportation problem with blending (FCTPwB) that we study captures a core structure encountered in many of these environments. We model the FCTPwB as a mixed-integer linear program and derive two classes of facets, both exponential in size, for the convex hull of solutions for the problem with a single consumer and show that they can be separated in polynomial time. Finally, a computational study demonstrates that these classes of facets are effective in reducing the integrality gap and solution time for more general instances of the FCTPwB.
3

Modelagem da programação de navios para otimização no canal de acesso ao porto de Santos. / Scheduling model optimize the canal access of vessels to Porto de Santos.

Mota, Daniel de Oliveira 19 February 2016 (has links)
A gestão de um recurso para se obter a sua máxima ocupação requer não somente a técnica de planejamento adequada, mas também a consideração das incertezas durante o seu uso. Este trabalho utiliza o ponto forte das duas principais vertentes da pesquisa operacional: otimização e simulação em um contexto logístico portuário. Portanto, a técnica de programação de produção aplicada a um sistema logístico, associada à flexibilidade das aleatoriedades inerentes ao mesmo processo, provê aos tomadores de decisão de sistemas portuários um modelo matemático que auxilia na melhor ocupação de um canal de acesso aos terminais portuários. Assim, foi desenvolvido um modelo de otimização, inspirado no \"job shop\" aplicado em um sistema logístico, capaz de propor, partindo de um conjunto de navios, a melhor programação de acesso ao porto, através das informações relacionadas às operações portuárias. Uma vez estipulada a melhor programação, ela foi testada em um modelo simulação contemplando todas as etapas de um processo de carregamento/descarregamento de um navio em um terminal portuário, incluindo as incertezas de cada uma das etapas, bem como disponibilidade de ativos, regras de cruzamento e movimentações no canal. Através desta modelagem híbrida, obteve-se uma avaliação realista da proposta gerada pelo otimizador com a apuração dos resultados utilizando indicadores de desempenho atualmente empregados por profissionais de sistemas portuários como ocupação do sistema, tempo em fila e tempo de estadia do navio. Assim, foram comparados os impactos na mudança da forma de se operar um canal (liberando ou não o cruzamento dos navios durante seu curso) e calculados os ganhos operacionais de se programar os navios em sua entrada ao invés de simplesmente respeitar a ordem de chegada das embarcações. / The resource management in order to reach its maximum occupation requires not only the appropriate technique, but the incorporation of the uncertainties built in the process. This research uses the strength of each main streams of Operations Research: optimization and simulation in a logistic maritime context. Hence, the scheduling technique applied in a logistic system, and associated to the flexibility of having the uncertainties of its process provides the maritime logistic decision makers a mathematical model that helps them to deliver a better occupation rate of the canal to access the port terminals. To accomplish such objective, it was developed an optimization model, inspired in the job shop problem, and applied in a logistic system capable to propose, from a ship list, the best schedule, changing the order of entrance and exit of the vessels, using information related to its port operations. Once the best order of vessel is found, it was tested in a simulation model with most of constraints incorporated including all steps of the process, loading/unloading process, and all uncertainties within each step of the process (resources availability, navigation rules, safety, and operations policy). Such hybrid modeling technique, it was achieved a realistic evaluation of the optimization proposition, with the results measurements well known by the port practicioners, such as occupancy rates, waiting time, and complete service time (Makespan). To reach such evaluation it was compared the impact of changing the operations policy of the canal (allowing or not the crossing of the ships while navigating) and calculated the operational benefits of using a dispatching efford to coordinate the canal instead of respecting its arrival order.
4

Modelagem da programação de navios para otimização no canal de acesso ao porto de Santos. / Scheduling model optimize the canal access of vessels to Porto de Santos.

Daniel de Oliveira Mota 19 February 2016 (has links)
A gestão de um recurso para se obter a sua máxima ocupação requer não somente a técnica de planejamento adequada, mas também a consideração das incertezas durante o seu uso. Este trabalho utiliza o ponto forte das duas principais vertentes da pesquisa operacional: otimização e simulação em um contexto logístico portuário. Portanto, a técnica de programação de produção aplicada a um sistema logístico, associada à flexibilidade das aleatoriedades inerentes ao mesmo processo, provê aos tomadores de decisão de sistemas portuários um modelo matemático que auxilia na melhor ocupação de um canal de acesso aos terminais portuários. Assim, foi desenvolvido um modelo de otimização, inspirado no \"job shop\" aplicado em um sistema logístico, capaz de propor, partindo de um conjunto de navios, a melhor programação de acesso ao porto, através das informações relacionadas às operações portuárias. Uma vez estipulada a melhor programação, ela foi testada em um modelo simulação contemplando todas as etapas de um processo de carregamento/descarregamento de um navio em um terminal portuário, incluindo as incertezas de cada uma das etapas, bem como disponibilidade de ativos, regras de cruzamento e movimentações no canal. Através desta modelagem híbrida, obteve-se uma avaliação realista da proposta gerada pelo otimizador com a apuração dos resultados utilizando indicadores de desempenho atualmente empregados por profissionais de sistemas portuários como ocupação do sistema, tempo em fila e tempo de estadia do navio. Assim, foram comparados os impactos na mudança da forma de se operar um canal (liberando ou não o cruzamento dos navios durante seu curso) e calculados os ganhos operacionais de se programar os navios em sua entrada ao invés de simplesmente respeitar a ordem de chegada das embarcações. / The resource management in order to reach its maximum occupation requires not only the appropriate technique, but the incorporation of the uncertainties built in the process. This research uses the strength of each main streams of Operations Research: optimization and simulation in a logistic maritime context. Hence, the scheduling technique applied in a logistic system, and associated to the flexibility of having the uncertainties of its process provides the maritime logistic decision makers a mathematical model that helps them to deliver a better occupation rate of the canal to access the port terminals. To accomplish such objective, it was developed an optimization model, inspired in the job shop problem, and applied in a logistic system capable to propose, from a ship list, the best schedule, changing the order of entrance and exit of the vessels, using information related to its port operations. Once the best order of vessel is found, it was tested in a simulation model with most of constraints incorporated including all steps of the process, loading/unloading process, and all uncertainties within each step of the process (resources availability, navigation rules, safety, and operations policy). Such hybrid modeling technique, it was achieved a realistic evaluation of the optimization proposition, with the results measurements well known by the port practicioners, such as occupancy rates, waiting time, and complete service time (Makespan). To reach such evaluation it was compared the impact of changing the operations policy of the canal (allowing or not the crossing of the ships while navigating) and calculated the operational benefits of using a dispatching efford to coordinate the canal instead of respecting its arrival order.

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