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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.
51

Modelling container logistics processes in container terminals : a case study in Alexandria

ElMesmary, Hebatallah Mohammed January 2015 (has links)
This study aims to optimize the logistics processes of container terminals. Potentially powerful pipe-flow models of container terminal logistics processes have been neglected to date and modelling of terminals is rare. Because research which adopts a pipe flow and dynamic operational perspective is rare, a case application in Alexandria, Egypt collated empirical container and information flows using interviews and company records to describe its logistics processes and model container and information flows. The methodology used includes qualitative and quantitative methods and a descriptive methodology proceeds sequentially. Primary and secondary data were presented as a pipe flow model to show interrelations between the company’s resources and to identify bottlenecks. Simulation modelling used Simul8 software. Operational level modelling of both import and export flows simulated the actual inbound and outbound flows of containers from entry to exit. The import logistics process includes activities such as unloading vessels by quay cranes, moving containers by tractors to yard cranes to go for storage where customs procedures take place before exiting the terminal by customer’s truck. The export logistics process includes the activities associated with customers’ trucks, lifters, storage yards, tractors and quay cranes. The model takes into account the uncertainties in each activity. This study focuses on operational aspects rather than cost issues, and considers container flows rather than vessel flows. Although the simulated model was not generalized, implementation elsewhere is possible. Following successful validation of a base simulation model which reproduces the case company’s historical scenario, scenario testing empowered the case company to pro-actively design and test the impact of operational changes on the entire logistics process. The study evaluates a typical container terminal logistics system including both import and export containers in the presence of multiple uncertainties in terminal operations (e.g. quay crane operations, tractor operations, yard crane operations). Sensitivity testing and scenario analysis can empower terminal managers to make decisions to improve performance, and to guide terminal planners, managers, and operators in testing future investment scenarios before implementation.
52

Optimization and Robustness in Planning and Scheduling Problems. Application to Container Terminals

Rodríguez Molins, Mario 31 March 2015 (has links)
Despite the continuous evolution in computers and information technology, real-world combinatorial optimization problems are NP-problems, in particular in the domain of planning and scheduling. Thus, although exact techniques from the Operations Research (OR) field, such as Linear Programming, could be applied to solve optimization problems, they are difficult to apply in real-world scenarios since they usually require too much computational time, i.e: an optimized solution is required at an affordable computational time. Furthermore, decision makers often face different and typically opposing goals, then resulting multi-objective optimization problems. Therefore, approximate techniques from the Artificial Intelligence (AI) field are commonly used to solve the real world problems. The AI techniques provide richer and more flexible representations of real-world (Gomes 2000), and they are widely used to solve these type of problems. AI heuristic techniques do not guarantee the optimal solution, but they provide near-optimal solutions in a reasonable time. These techniques are divided into two broad classes of algorithms: constructive and local search methods (Aarts and Lenstra 2003). They can guide their search processes by means of heuristics or metaheuristics depending on how they escape from local optima (Blum and Roli 2003). Regarding multi-objective optimization problems, the use of AI techniques becomes paramount due to their complexity (Coello Coello 2006). Nowadays, the point of view for planning and scheduling tasks has changed. Due to the fact that real world is uncertain, imprecise and non-deterministic, there might be unknown information, breakdowns, incidences or changes, which become the initial plans or schedules invalid. Thus, there is a new trend to cope these aspects in the optimization techniques, and to seek robust solutions (schedules) (Lambrechts, Demeulemeester, and Herroelen 2008). In this way, these optimization problems become harder since a new objective function (robustness measure) must be taken into account during the solution search. Therefore, the robustness concept is being studied and a general robustness measure has been developed for any scheduling problem (such as Job Shop Problem, Open Shop Problem, Railway Scheduling or Vehicle Routing Problem). To this end, in this thesis, some techniques have been developed to improve the search of optimized and robust solutions in planning and scheduling problems. These techniques offer assistance to decision makers to help in planning and scheduling tasks, determine the consequences of changes, provide support in the resolution of incidents, provide alternative plans, etc. As a case study to evaluate the behaviour of the techniques developed, this thesis focuses on problems related to container terminals. Container terminals generally serve as a transshipment zone between ships and land vehicles (trains or trucks). In (Henesey 2006a), it is shown how this transshipment market has grown rapidly. Container terminals are open systems with three distinguishable areas: the berth area, the storage yard, and the terminal receipt and delivery gate area. Each one presents different planning and scheduling problems to be optimized (Stahlbock and Voß 2008). For example, berth allocation, quay crane assignment, stowage planning, and quay crane scheduling must be managed in the berthing area; the container stacking problem, yard crane scheduling, and horizontal transport operations must be carried out in the yard area; and the hinterland operations must be solved in the landside area. Furthermore, dynamism is also present in container terminals. The tasks of the container terminals take place in an environment susceptible of breakdowns or incidences. For instance, a Quay Crane engine stopped working and needs to be revised, delaying this task one or two hours. Thereby, the robustness concept can be included in the scheduling techniques to take into consideration some incidences and return a set of robust schedules. In this thesis, we have developed a new domain-dependent planner to obtain more effi- cient solutions in the generic problem of reshuffles of containers. Planning heuristics and optimization criteria developed have been evaluated on realistic problems and they are applicable to the general problem of reshuffling in blocks world scenarios. Additionally, we have developed a scheduling model, using constructive metaheuristic techniques on a complex problem that combines sequences of scenarios with different types of resources (Berth Allocation, Quay Crane Assignment, and Container Stacking problems). These problems are usually solved separately and their integration allows more optimized solutions. Moreover, in order to address the impact and changes that arise in dynamic real-world environments, a robustness model has been developed for scheduling tasks. This model has been applied to metaheuristic schemes, which are based on genetic algorithms. The extension of such schemes, incorporating the robustness model developed, allows us to evaluate and obtain more robust solutions. This approach, combined with the classical optimality criterion in scheduling problems, allows us to obtain, in an efficient in way, optimized solution able to withstand a greater degree of incidents that occur in dynamic scenarios. Thus, a proactive approach is applied to the problem that arises with the presence of incidences and changes that occur in typical scheduling problems of a dynamic real world. / Rodríguez Molins, M. (2015). Optimization and Robustness in Planning and Scheduling Problems. Application to Container Terminals [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/48545 / TESIS
53

Creating a Transportation Strategy for North Dakota Exporters

Goldade, Ashley Lynn January 2010 (has links)
North Dakota's transportation problem is centered on geography and volume. Being a land-locked state and not having an intermodal facility within the economic range of 150 miles from North Dakota production sites, transportation costs severely reduce shipper profit margins. Options available to containerized shippers are limited and expensive. The purpose of this research is to develop a model that evaluates tradeoffs regarding the development of intermodal shipping capabilities in North Dakota. The following are specific objectives to the research process: 1. Examine historical and current issues pertaining to intermodal transportation in North Dakota; 2. Develop an empirical model to evaluate intermodal pricing, revenues, and demand; 3. Conduct a sensitivity analysis on key random variables and interpret the results; 4. Analyze a variety of coalition cooperative efforts among key players and their effect on North Dakota' s transportation environment; 5. Describe a business model that could enable efficient intermodal transportation for North Dakota intermodal operators. Examining both the base case model and sensitivities applied to the base model allowed for examining today's transportation environment and its potential. The results are reported in chapter five and applied to game theory. Incorporating the results to game theory allows development of a business model focused on subsidizing network operators to cooperate and reposition containers to service North Dakota. A linear programming model was developed to analyze logistical costs and payoffs associated with varying game alternatives. Data collected was analyzed using GAMS software to determine the cost minimizing solutions for exporters across the eight regions of North Dakota. Base model results indicate hard IP producers in North Dakota realize minimized costs by draying containers to the intermodal terminals of Saskatoon, Winnipeg, or Minneapolis. Sensitivities were applied to answer "what if" questions related to North Dakota transportation. The first sensitivity test allows for cost of shipping by bulk to the point of export versus required loading of containers at the site of production. Results show that for the three regions encompassing the eastern border and southeast comer of North Dakota (ND4, ND7 and ND8), stuffing containers at the site of production remains the cost minimizing solution. Sensitivity accounts for hard IP shipments and includes the Minot intermodal terminal. Results show that North Dakota realizes the Minot terminal as an important shipping option. The expanded model and final sensitivity accounts for the 21 metric tons per TEU limitation placed on a containers load weight moving by rail. The addition of this parameter slightly changed model results to reflect a loss of market share to the Minot terminal. Sensitivities were then conducted on the expanded model. These sensitivities display a shift in shipping patterns due to the cost of repositioning empty containers, container stuffing fees, and Minot`s terminal handling fee.
54

Análise das estratégias competitivas dos terminais privados de contêineres da região Sul do Brasil: contribuições e aprendizado a partir de um exemplo internacional

Daudt, Claúdio Gustavo 12 June 2007 (has links)
Made available in DSpace on 2015-03-05T18:38:00Z (GMT). No. of bitstreams: 0 Previous issue date: 12 / Nenhuma / O objetivo deste trabalho é o de analisar as estratégias dos terminais privados de contêineres que participam da indústria de terminais da Região Sul do Brasil, a partir da identificação das principais características do ambiente externo e interno dessas empresas. A análise dá-se mediante utilização do modelo das cinco forças competitivas e das estratégias genéricas. Adicionalmente, utilizam-se conceitos sobre a estrutura de monopólio natural, de modo a viabilizar entendimento complementar sobre o ambiente de competição. O trabalho tem caráter qualitativo, e faz-se uso do estudo de casos múltiplos como estratégia de pesquisa, que foi dividida em duas etapas. A primeira, que contou com entrevistas semi-estruturadas e estruturadas, tem como objetivo identificar as principais características do ambiente competitivo dos terminais privados da Região Sul do Brasil, assim como as estratégias adotadas pelos terminais participantes da indústria, TCP, TECONVI e TECON. Na segunda etapa, desenvolvida no Porto de Hamburgo / This dissertation aims the analysis of the strategies adopted by container private terminals that are part of southern Brazilian terminals industry, taking as standpoint, the identification of the main characteristics of the external and internal enviroment of these firms. The analysis makes use of the theorical Five Forces Model, as well as of the generic strategies framework. Additionally, it has been used concepts concerning the idea of natural monopolies, in order to provide further understanding around the competitive structure of the analysed industry. The research is classified as a qualitative one. Case study method has been chosen, and the whole research process is divided in two different parts. The first one, uses semi-structured and structured enterviews, with the objective to identify the characteristics of the competitive enviroment of Southern Brazil container terminals industry, and also the strategies selected by the private terminals TCP, TECONVI and TECON. The second part of the research wa
55

Planning Container Drayage Operations at Congested Seaports

Namboothiri, Rajeev 19 May 2006 (has links)
This dissertation considers daily operations management for a fleet of trucks providing container pickup and delivery service to a port. Truck congestion at access points for ports may lead to serious inefficiencies in drayage operations, and the resultant cost impact to the intermodal supply chain can be significant. Recognizing that port congestion is likely to continue to be a major problem for drayage operations given the growing volume of international containerized trade, this research seeks to develop optimization approaches for maximizing the productivity of drayage firms operating at congested seaports. Specifically, this dissertation addresses two daily drayage routing and scheduling problems. In the first half of this dissertation, we study the problem of managing a fleet of trucks providing container pickup and delivery service to a port facility that experiences different access wait times depending on the time of day. For this research, we assume that the wait time can be estimated by a deterministic function. We develop a time-constrained routing and scheduling model for the problem that incorporates the time-dependent congestion delay function. The model objective is to find routes and schedules for drayage vehicles with minimum total travel time, including the waiting time at the entry to the port due to congestion. We consider both exact and heuristic solution approaches for this difficult optimization problem. Finally, we use the framework to develop an understanding of the potential impact of congestion delays on drayage operations, and the value of planning with accurate delay information. In the second half of this dissertation, we study methods for managing a drayage fleet serving a port with an appointment-based access control system. Responding to growing access congestion and its resultant impacts, many U.S. port terminals have implemented appointment systems, but little is known about the impact of such systems on drayage productivity. To address this knowledge gap, we develop a drayage operations optimization approach based on a column generation integer programming heuristic that explicitly models a time-slot port access control system. The approach determines pickup and delivery sequences with minimum transportation cost. We use the framework to develop an understanding of the potential efficiency impacts of access appointment systems on drayage operations. Findings indicate that the set of feasible drayage tasks and the fleet size required to complete them can be quite sensitive to small changes in time-slot access capacities at the port.
56

Solutions globales d'optimisation robuste pour la gestion dynamique de terminaux à conteneurs / Global robust optimization solutions for dynamic management of container terminals

Schepler, Xavier 09 October 2015 (has links)
Cette thèse s’intéresse au cas d’un port maritime dans lequel des terminaux à conteneurs coopèrent afin de fournir un meilleur service global. Pour coordonner les opérations entre les terminaux, un modèle et plusieurs méthodes de résolution sont proposés. L’objectif est de minimiser les temps de rotation des navires aux longs cours, des navires caboteurs, des barges fluviales et des trains. Une solution au modèle fournit une affectation des véhicules de transport de conteneurs aux terminaux, ce qui inclue les camions, ainsi qu’une allocation de ressources et des intervalles temporels pour leurs prises en charge et pour celles de leurs conteneurs. Pour obtenir des solutions au modèle, une formulation du problème comme un programme linéaire en variables mixtes est proposée, ainsi que plusieurs heuristiques basées sur la programmation mathématique. Une méthode de planification en horizon glissant est introduite pour la gestion dynamique avec prise en compte des incertitudes. Des expériences numériques sont conduites avec des milliers d’instances réalistes variées, dont les résultats indiquent la viabilité de notre approche. Des résultats démontrent qu’autoriser la coopération entre terminaux augmente significativement la performance du système. / This thesis deals with the case of a maritime port in which container terminals are cooperating to provide better global service. In order to coordinate operations between the terminals, a model and several solving methods are proposed. The objective is to minimize turnaround times of mother and feeder vessels, barges and trains. A solution to the model provides an assignment of container-transport vehicles to the terminals, including trucks, as well as an allocation of resources and time intervals to handle them and their containers. To obtain solutions to the model, a mixed-integer programming formulation is provided, as well as several mathematical programming based heuristics. A rolling horizon framework is introduced for dynamic management under uncertainty. Numerical experiments are conducted on thousands of various realistic instances. Results indicate the viability of our approach and demonstrate that allowing cooperation between terminals significantly increases the performance of the system.
57

Study of the possibillity of container port alliance

Chao, Chung-min, Christina., 趙仲敏. January 2006 (has links)
published_or_final_version / Transport Policy and Planning / Master / Master of Arts in Transport Policy and Planning
58

Application of a critical systems approach to understanding ship turnaround in the Port of Durban.

Rappetti, Eugene Alec January 2012 (has links)
Seaborne container shipping plays a major and important role in the world transportation system and the global supply chain. Shipping lines have designed their product offering to shippers around providing regular calls at designated ports. This works well for most firms that operate on a just-in-time philosophy. The real costs of trade – the transport and other costs of doing business internationally – are important determinants of a country’s ability to participate fully in the world economy. This is an important indicator for port performance in a globalised economy; therefore, any inefficiency that increases costs must be addressed. This means that ports have to ensure very high productivity and efficiency levels so that ships have a quick turnaround. Clark et al., (2002) conclude that a 50% improvement in port efficiency can reduce shipping costs by about 12%. The general question that is studied in this research is: How can the Marine Services within the Port of Durban assist in reducing ship turnaround times? This study seeks to determine what role the marine services plays in ship turnaround. The analysis in this study will be to determine the source of delays and ways to improve on efficiency. The resultant improvement in efficiency should lead to a possible reduction in shipping costs. The Market Demand Strategy employed by Transnet in 2012 must be implemented in such a manner that it must not only address the current infrastructural backlogs but it must also endeavour to alleviate several logistic chain bottlenecks that tend to constrain the economy. When analysing 2010-2011 a worrying trend emerges that the average waiting times for ships at anchor has increased significantly and the time on the berth has also increased significantly despite a reduction in the number of ships calling to the port. This is partly due to the fact that much larger ships now arriving at the port and more crucially are working a larger number of containers per port call. However, there is still concern about the operational efficiency of the terminals in the port (Pier One and Durban Container Terminal). The Marine Operations service times have also increased marginally 1.23% (0.98 hours) but this is due to longer time required for berthing and sailing of larger ships. This study has clearly shown that the Marine Operations within the Port of Durban do not significantly impact on overall ship turnaround time. However, there are areas of improvement that can be implemented to ensure high service levels within the port. By increasing the tug fleet and ensuring adequate human resources, the service offering can immediately be improved. Extremely lengthy anchorage waiting times and high berth occupancy impact negatively on ship-owners, shippers, and the economy at large. The Port Authority must interrogate these areas to understand clearly what is driving these extended times and determine strategies and performance measures to mitigate these. / Thesis (M.Com.)-University of KwaZulu-Natal, Durban, 2012.
59

Improved operational efficiency as a measure for alleviating port congestion at the Cape Town container terminal

Powles, Michael John January 2004 (has links)
Thesis (MTech (Business Administration))--Cape Technikon, 2004. / The Cape Town Container Terminal (CTCT) facilitates the handling process ofImport and Export containers for the Western Cape and other regions. South African Port Operations (SAPO), a division of the transport parastatal Transnet, is the operator that handles container volumes through the terminal. Due to the nature of its operations, it focuses on service standards within the industry. The International Shipping Industry expects this container terminal to conform by providing the same operational standards and service they receive from other international ports. Container terminal efficiency and productivity were not providing a reliable and efficient service for vessels calling to CTCT. Delays became so endemic that the shipping lines instituted a seventy-five dollar congestion surcharge on each container being handled This surcharge was passed on to the consumer therefore increasing the logistical cost of goods and services. The fact that a shipping line was bypassing Cape Town altogether was an indication that the Terminal was experiencing difficulty in maintaining its port status as a prominent and efficient container terminal at the southern tip of Africa.
60

Algoritmo de seleção clonal para a minimização de rearranjos em operações de pilhas de contêineres

Carraro, Luiz Antonio 16 February 2012 (has links)
Made available in DSpace on 2016-03-15T19:37:43Z (GMT). No. of bitstreams: 1 Luiz Antonio Carraro.pdf: 1226702 bytes, checksum: 3cef29694a4e26f233b0aae16da69cf0 (MD5) Previous issue date: 2012-02-16 / Universidade Presbiteriana Mackenzie / A container is a broadly used solution for the cargo storage to be transported between ports, playing a central role in international trade. Consequently, ships grew in size in order to maximize their container transportation capacity in each trip. Due to increasing demand, container terminals face the challenges of increasing their service capacity and optimizing the loading and unloading time of ships. Optimization problems, such as these, often present features that make it impossible to obtain closed analytical solutions, requiring iterative search procedures in high-dimensional spaces, or subject to a combinatorial explosion of possible solutions. This dissertation presents the proposal of a novel meta-heuristic based on the Clonal Selection Algorithm, named MRC, to minimize the number of reshuffles in operations involving piles of containers. The performance of the proposed model was evaluated through simulations and results comparison with those obtained by algorithms from the literature under the same test conditions. The results obtained show that MRC is competitive in terms of minimizing the need of reshuffles, besides presenting a reduced processing time compared with models of similar performance. / A utilização de contêineres é uma solução amplamente adotada para o armazenamento da carga a ser transportada entre portos, tornando-se de grande importância no comércio internacional e, consequentemente, navios cresceram de tamanho com o objetivo de transportar a maior quantidade possível de contêineres em cada viagem. Devido à crescente demanda, terminais de contêineres enfrentam os desafios de aumentar a sua capacidade de atendimento e otimizar os tempos de carregamento e descarregamento de navios. Problemas de otimização como estes geralmente apresentam características que inviabilizam a obtenção de soluções analíticas fechadas, requerendo processos iterativos de busca em espaços de dimensão muitas vezes elevada, ou ainda sujeitos a explosão combinatória de possíveis soluções. Esta dissertação apresenta a proposta de uma meta-heurística bioinspirada baseada no Algoritmo de Seleção Clonal para a minimização de rearranjos em operações que envolvem pilhas de contêineres, denominado MRC. O desempenho do algoritmo foi avaliado por meio de simulações e comparação dos resultados com os obtidos por algoritmos da literatura sob as mesmas condições de teste. Os resultados obtidos permitem concluir que o MRC possui resultados competitivos em termos de minimização de rearranjos, além de apresentar um tempo de processamento reduzido quando comparado aos modelos tradicionalmente empregados na solução desse tipo de problema.

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