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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

Numerical Analysis of a Floating Harbor System and Comparison with Experimental Results

Kang, Heonyong 2010 May 1900 (has links)
As a comparative study, the global performance of two cases for a floating harbor system are researched by numerical analysis and compared with results from experiments: one is a two-body case such that a floating quay is placed next to a fixed quay, a normal harbor, and the other is a three-body case such that a container ship is posed in the middle of the floating quay and the fixed quay. The numerical modeling is built based on the experimental cases. Mooring system used in the experiments is simplified to sets of linear springs, and gaps between adjacent bodies are remarkably narrow as 1.3m~1.6m with reference to large scales of the floating structures; a water plane of the fixed quay is 480m×160m, and the ship is 15000 TEU (twenty-foot equivalent unit) class. With the experiment-based models, numerical analysis is implemented on two domains: frequency domain using a three dimensional constant panel method, WAMIT, and time domain using a coupled dynamic analysis program of moored floating structures, CHARM3D/HARP. Following general processes of the two main tools, additional two calibrations are implemented if necessary: revision of external stiffness and estimation of damping coefficients. The revision of the external stiffness is conducted to match natural frequency of the simulation with that of the experiment; to find out natural frequencies RAO comparison is used. The next, estimation of damping coefficients is carried out on time domain to match the responses of the simulation with those of the experiment. After optimization of the numerical analysis, a set of experimental results from regular wave tests is compared with RAO on frequency domain, and results from an irregular wave test of the experiment are compared with response histories of simulation on time domain. In addition, fender forces are compared between the simulation and experiment. Based on response histories relative motions of the floating quay and container ship are compared. And the floating harbor system, the three-body case, is compared with a conventional harbor system, a fixed quay on the portside of the container ship, in terms of motions of the container ship. As an additional simulation, the three-body case is investigated on an operating sea state condition. From the present research, the experimental results are well matched with the numerical results obtained from the simulation tools optimized to the experiments. In addition, the floating harbor system show more stable motions of the container ship than the conventional harbor system, and the floating harbor system in the operating sea state condition have motions even smaller enough to operate in term of relative motions between the floating quay and the container ship.
2

Physical Modeling of the Motions of a Container Ship Moored to a Dock with Comparison to Numerical Simulation

Zhi, Yuanzhe 16 December 2013 (has links)
Container vessel motions need to be small when loading and offloading cargo while moored to wharfs. Waves and their reflections from structures can induce ship motions. These motions are characterized by six degrees of freedom, including translations of surge, sway, and heave and rotations of pitch, roll, and yaw. Monitoring and quantifying these motions offer a reference for design and selection of the mooring system and wharf types. To measure the six degrees of freedom motions of a container ship moored to a dock, a 1:50 scale model is moored to two types of dock, solid wall dock and pile supported dock. Irregular waves of TMA spectrum with various periods, heights, and directions are generated in the wave basin to induce the motions of the model container ship. Optical motion capturing cameras are used to measure and quantify the six degree of freedom motions. Results of the effects of wave period, significant wave height, and wave direction on the motion characteristics of the model container ship moored at the solid dock and a pile supported dock are described in detail. A numerical simulation called aNySIM is applied to numerically predict the motion characteristics of the container ship moored to a solid wall dock only. The physical model experimental results of solid dock are also compared with the numerical simulation. These comparisons indicate that the motion characteristics of the model container ship represent similar trends for both rotations and translations. The experimental and numerical prediction values of motions of the ship moored to a solid wall dock display the same tendencies while differing in magnitude.
3

Uma abordagem para o problema de carregamento de navios-contêineres através do emprego de metaheurísticas baseadas na codificação por regras

Carraro, Luziana Ferronatto 25 March 2013 (has links)
Submitted by William Justo Figueiro (williamjf) on 2015-07-27T20:23:06Z No. of bitstreams: 1 09d.pdf: 2136888 bytes, checksum: 8bc73fd7975259c3bc984b913580a5c1 (MD5) / Made available in DSpace on 2015-07-27T20:23:06Z (GMT). No. of bitstreams: 1 09d.pdf: 2136888 bytes, checksum: 8bc73fd7975259c3bc984b913580a5c1 (MD5) Previous issue date: 2013 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Com a expansão do transporte marítimo, passou a ser adotado o uso de contêineres para o transporte de cargas, sendo evidenciados alguns problemas. Dentre eles, um dos principais, é o problema de carregamento e descarregamento de contêineres em navios. O problema surge devido aos altos custos operacionais gerados a partir da movimentação de contêineres. Este problema é o foco desta pesquisa, que tem como objetivo principal elaborar planos de carga eficientes que gerem um número mínimo de movimentações de contêineres, nas operações de carga e descarga de navios-contêineres, diminuindo assim os custos de operação. Neste trabalho, é proposta a aplicação da metaheurística Algoritmo Genético e da metaheurística Enxame de Abelhas, resolvendo o problema através de uma codificação baseada em regras de carregamento e descarregamento. A codificação por regras é compacta e adequada, assegurando que as soluções do problema sejam factíveis e de simples representação, acelerando o processo de solução. Nos experimentos realizados, as duas metaheurísticas foram empregadas, assumindo diferentes configurações de regras, com o intuito de comparar o seu desempenho. A proposta de novas regras de carregamento e descarregamento, em complemento às existentes na literatura, trouxeram bons resultados. Desta forma, foram obtidas soluções de boa qualidade e melhores que aquelas encontradas na literatura que abordam o mesmo problema. / With the expansion of maritime transportation, the use of containers for goods transportation has increased, being evidenced some problems. Among these problems, the container ship stowage problem arose as one of the main problems due to the high operational costs related to movement of containers. This problem is the focus of this research, where the main objective is the formulation of stowage plans that generate a minimum number of container shiftings in the operations of loading and unloading performed in port calls of container ships. In order to determine a suitable stowage plan, the application of Genetic Algorithm and Bee Swarm Optimization metaheuristics are proposed to solve the problem by using a rule-based encoding for the solution. The solution encoding based on loading and unloading rules is compact and suitable, ensuring the feasibility of solutions and also the simple representation of it, speeding up the solution procedures. In the performed experiments, both metaheuristics were applied assuming different rules settings with the objective to compare each performance. The proposal of new rules of loading and unloading, in addition with those existing in literature, has produced good solutions. Thereby, good quality solutions were achieved and also better than that found in the literature which discuss the same problem
4

An alternative future for shipping – the way there : Risks and benefits of energy efficiency measures and alternative fuels for CO2 reduction in

Sunneland, Johanna, Gutiérrez Dufourq, María Sofía January 2018 (has links)
Shipping is the world’s largest mode of transportation, considering mass moved a distance: it is the most e˙effective way to carry large volumes far. In order for the shipping industry to keep its position and develop even further, efforts are made to increase efficiency and reduce the environmental footprint from the industry. More efficient ships, reduced fuel consumption, use of alternative fuels and exhaust gas treatment are some of the choices to reduce shipping’s environmental footprint and achieve the sustainability goal established by EU and enforced by the International Maritime Organization.Throughout the thesis, en evaluation of 18 energy efficiency measures and 4 alternative fuels is performed. Energy efficiency measures reduce a ship’s fuel consumption and alternative fuels substitutes fossil fuels with higher content of environmentally harmful content. The measures and fuels, covered in the study, are evaluated for nine representative container ship´s. Data from year 2016 are used for the nine container ships. The current procedure followed for new investments is analyzed for all measures and fuels for each ship, focused on the financial study of each measure and fuel. The results are then included in a risk and benefit analysis that introduces external aspects, not included in the traditional financial evaluation, that include: those that influence the ship and the ship’s environment and those affected by the ship’s operations.The main goal is to evaluate the possibilities to reduce emissions by considering these aspects and involve more stakeholders in the investment of measures and fuels for shipping to keep its position as the most efficient mode of transportation.
5

Abordagem metaheurística híbrida para otimização do planejamento de estiva de navios porta-contêineres

Gonçalves Júnior, Joel da Silva 07 March 2016 (has links)
Submitted by Silvana Teresinha Dornelles Studzinski (sstudzinski) on 2016-06-10T15:26:09Z No. of bitstreams: 1 Joel da Silva Gonçalves Júnior_.pdf: 1935811 bytes, checksum: 2c6b67ad91c1de26271d67142ef7721b (MD5) / Made available in DSpace on 2016-06-10T15:26:09Z (GMT). No. of bitstreams: 1 Joel da Silva Gonçalves Júnior_.pdf: 1935811 bytes, checksum: 2c6b67ad91c1de26271d67142ef7721b (MD5) Previous issue date: 2016-03-07 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O transporte marítimo mercante desempenha um papel fundamental para a economia de uma nação, ligando a produção ao consumo. No cenário de expansão do transporte marítimo, a utilização de contêineres para organização das cargas confere maior facilidade, segurança e rapidez ao transporte, aumentando, assim, a produtividade dos terminais e dos navios. No entanto, a operação de navios porta-contêineres possui limitações de movimentação e de estabilidade que impactam no custo operacional de um terminal portuário. Como os guindastes só podem acessar as pilhas de contêineres a partir do topo, a realização de remoções desnecessárias de contêineres bloqueantes gera um custo adicional de movimentação e de tempo nas operações de carga e descarga. Desta forma, faz-se necessária a elaboração de um plano de estiva eficiente para estas atividades, minimizando tanto os remanejamentos quanto a instabilidade da embarcação. Este estudo propõe uma abordagem híbrida, elaborada através da combinação das metaheurísticas Algoritmo Genético e Busca Tabu, utilizando a codificação da solução baseada em regras, a fim de elaborar uma ferramenta computacional que faça a gestão do número de remanejamentos e da instabilidade da embarcação, que são objetivos conflitantes. Nos experimentos, as metaheurísticas puras foram comparadas ao algoritmo híbrido e os resultados comprovaram que a aplicação hibridizada apresenta uma eficiência maior do que as metaheurísticas puras. As diferentes configurações de regras assumidas mostraram que a proposta de um número maior de regras, em complemento àquelas propostas na literatura, implica em melhores resultados. Através da aplicação da abordagem com múltiplos objetivos, foi possível observar a importância de considerar a movimentação e a estabilidade no plano de estiva. Com os resultados obtidos, demonstrou-se que o uso da abordagem proposta gera soluções melhores que as encontradas até o momento na literatura. / The merchant shipping perform a fundamental role in the economy of a nation, by linking production to consumption. In shipping expansion scenario, the use of containers for cargo organizing provides greater facility, safety and velocity, thus increasing the productivity of terminals and ships. However, the use of container ships has handling and stability limitations that affect the operating cost of a port terminal. As the cranes can only access the container stacks from the top, carrying out unnecessary removals of blocking containers generates an additional cost of handling and time in loading and unloading operations. Thus, it is necessary to elaborate an efficient stowage plan for loading and unloading operations, minimizing both the shifting and the instability of the vessel. This study proposes an hybrid approach developed by the combination of Genetic Algorithms and Tabu Search metaheuristics, using a rules-based encoding for solution representation, in order to create a computational tool that manage both the rehandling and instability, which are conflicting. In the experiments, pure metaheuristics were compared to the hybrid algorithm and the results demonstrate that the hybridization presents greater efficiency than the pure metaheuristics. The different rules configuration have proven that the proposal of a greater number of rules, in addition to those proposed in the literature, implies better results. The application of a multiple objectives approach has proven the importance of considering the handling and stability in the stowage plan. With the results, it was showed that the use of the proposed approach produces better solutions than those found in the literature.

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