[pt] O desenvolvimento de materiais com propriedades elétricas incomuns, como é o caso dos polímeros condutores, vem sendo estudado por muito tempo. Este tipo de sistema orgânico apresenta característica isolante pura, mas quando são introduzidas impurezas por meio da dopagem variam a sua condutividade de forma significativa em comparação com os metais. No presente trabalho, investigamos o transporte de carga eletrônica no sistema molecular do polímero Polianilina (PAN), através de cálculos quânticos mediante o método de Hückel e acoplado com a metodologia das funções de Green de não equilíbrio (FGNE) foram obtidas expressões para a condutância e densidade local de estados (LDOS). Realiza-se o estudo da estrutura eletrônica da PAN conformada de 200 anéis apresentando algum tipo de defeito estrutural tipo polaron o bipolaron onde os efeitos provocados pela desordem desempenham um papel fundamental. Investigamos assim a LDOS e a condutância para formações de cadeias de PAN tanto protonadas e não protonadas, verificando assim que a rede bipolarônica presente na estrutura do sistema apresenta um deslocamento da energia de Fermi para dentro da banda de valência, região de estados espacialmente estendidos onde a condutância é finita, comprovando assim a transição metal-isolante para este material. / [en] The development of materials with unusual electrical properties as is the case of conducting polymers has been studied for a long time. This type of organic system provides insulation characteristic pure, but when impurities are introduced by doping the conductivity varies significantly in comparison with metals. In this study, we investigated the transport of electronic charge in the system polymer molecular Polyaniline (PAN) through quantum calculations by the Hückel method and coupled with the methodology of Green functions of nonequilibrium (FGNE) were obtained expressions for the conductance and local density of states (LDOS). Is carried out to study the electronic structure of PAN conformed to 200 rings showing some type of structural defect type polaron bipolaron where the effects of the disorder play a key role. Thus investigated the LDOS and conductance to PAN formation of chains of both protonated and non protonated, thus verifying that the structure of the bipolaron in this system has a displacement of the Fermi energy into the valence band region of spatially extended states where conductance is finite, thus proving the metal-insulator transition for this material.

Efficient planning of freight transportation requires a comprehensive look at wide range of factors in the operation and man- agement of any transportation mode to achieve safe, fast, and environmentally suitable movement of goods. In this regard, a combination of transportation modes offers flexible and environmentally friendly alternatives to transport high volumes of goods over long distances. In order to reflect the advantages of each transportation mode, it is the challenge to develop models and algorithms in Transport Management System software packages. This paper discusses the principles of green logistics required in designing such models and algorithms which truly represent multiple modes and their characteristics. Thus, this research provides a unique practical contribution to green logistics literature by advancing our understanding of the multi-objective planning in intermodal freight transportation. Analysis based on a case study from hinterland intermodal transportation in Europe is therefore intended to make contributions to the literature about the potential benefits from com bining economic and environmental criteria in transportation planning. An insight derived from the experiments conducted shows that there is no need to greatly compromise on transportation costs in order to achieve a significant reduction in carbon-related emissions.

Background: Rottne Industri is a Swedish heavy machinery manufacturer whose production process is divided in three manufacturing plants. The production takes place in the facilities of Stensele and Lenhovda while the one at Rottne is also used for the final assembly. Ten suppliers provide steel materials to each facility translating to relatively high transportation costs which may be reduced by adopting a more centralized structure. Purpose: The purpose of this paper is to identify the transportation costs between the steel suppliers and the three manufacturing plants at Stensele, Lenhovda and Rottne as well as the freight transportation costs for components from Stensele and Lenhovda to Rottne. Moreover, the research seeks to analyze the difference in transportation costs if Rottne Industri was to centralize all its activities into one single manufacturing facility at Rottne. Finally, the authors aim to identify the environmental cost related to freight transportation in order to evaluate the total transportation cost difference between the two scenarios. Method: The Master thesis focuses on an instrumental case study on a single company. Qualitative and quantitative research methods are used for the necessary data collection to bring up a broader picture of Rottne Industri transportation costs and how it will change in a different organizational structure. Results: The studied company would reduce its freight transportation cost from 2 471 735 SEK of the current decentralized structure to 398 265 SEK of the centralized one. The environmental cost would decrease by 91% (20 420 SEK) due to the decrease of material flow. Therefore Rottne Industri would reduce its total transportation costs by 84% by centralizing its manufacturing structure, for a monetary value estimated at 2 095 860 SEK. However these results contradict part of the theoretical framework concerning the advantages and the disadvantages of centralization and decentralization, as the new centralized structure appears to be more easily manageable while reducing the transportation costs from the different suppliers. Therefore further researches are required as a broader approach on the effects of switch in the organizational structure at Rottne Industri.

When integer programming (IP) models are used in operational situations there is a need to consider the tradeoff between the conflicting goals of solution quality and solution time, since for many problems solving realistic-size instances to a tight tolerance is still beyond the capability of state-of-the-art solvers. However, by appropriately defining small instances, good primal solutions frequently can be found quickly. We explore this approach in this thesis by studying the design of algorithms that produce solutions to an integer program by solving restrictions of the problem via integer programming technology. We refer to this type of algorithm as IP-based search and present algorithms for network design problems of both real-world and academic interest. Along with algorithms that exploit the structure of the problem studied we also present a general integer programming algorithm that uses column generation to choose the restrictions to solve.

Thesis (MScEng (Industrial Engineering))--Stellenbosch University, 2008. / Passenger cars are either imported to or assembled in South Africa, and then distributed to the customer. An important part of the supply chain is formed by the auto carrier companies who do this distribution. The basis of this thesis is a study that was executed in collaboration with a South African auto carrier company, and the objective was to improve the long-distance auto carrier fleet management through improved tactical operational policies. These policies focus on application of the fleet by assigning transportation vehicles to routes, as well as the business rules that must be followed at pick-up and drop-off locations. Several rules were developed during this study, which, together with specific transportation vehicle (carriers) assignments, form operational scenarios. The quality of each scenario was evaluated using discrete event simulation over a six month time-span, and considering four decision parameters simultaneously. These parameters are 1) useful kilometres travelled by the long-distance carriers, 2) empty kilometres travelled by the same long-distance carriers, 3) the expected number of cars waiting to be transported and 4) the expected time it takes to deliver a car to its destination. A high level of uncertainty prevails in these transportation operations, while fluctuating demand calls for the dynamic allocation and management of carriers in order to sustain an acceptable service level in a cost-effective manner. The best tactical policies should maximize the number of cars delivered on time at the lowest cost. Major constraints considered are staff- and maintenance schedules. While searching for the best of several scenarios, multiple, conflicting criteria had to be evaluated, as mentioned above. Two multi-criteria decision analysis (MCDA) methods were used namely SAW and TOPSIS, while the Mahalanobis distance method was also applied as an evaluation technique. These methods were used to rank scenarios. Additionally, the application of Portfolio theory and the efficient frontier was investigated for applicability to the problem studied. An analogy to the efficient frontier providing an additional means for scenario selection and evaluation was developed. The result of this study provides the decision maker of the auto carrier company with a tactical decision aid, consisting of the MCDA and Mahalanobis scenario rankings, a cost-benefit graph and a fleet portfolio efficient frontier, to aid long-distance carrier management. Additionally, a sensitivity analysis was also done for strategic planning concerned with the sufficient long-distance carrier fleet size. The first part of this thesis comprises a study of literature in which freight operations, auto carrier studies and the auto carrier context in South Africa are investigated. The problem is formulated and a suitable formulation and solution tool identified. Multi-criteria decision analysis is also investigated in order to enable scenario evaluation. The solution development phase consisted of the simulation model concept development, acquisition of input data, model verification and validation, scenario construction, simulation execution, and analysis of results.

The rapid pace of the development of the transport and vehicle industry in combination with megatrends such as digitalization, automation, and electrification can have huge effects on how transport planning and the society evolves. In order to meet goals such as increased traffic safety,improved environment, and reduced congestions a lot needs to be done. Two tools expected to be of significance when creating a more transport efficient society are automation and digitalization, whereby self-driving vehicles (SDVs) is an important area. The race towards fully autonomous vehicles is ongoing and scholars argue that the implementation of SDVs can be faster within freight transportation than passenger transportation. Higher costsavings, as well as decreasing availability on the labor market, are two arguments for why freighttransportation can be autonomous faster. Depending on how ambitious or slow the policy and planning are as well as the development of shared solutions, different future scenarios, as well as penetration rates of SDVs, can come through. One certain trend argued to continue to grow as well as having an impact on the development of SDVs is the rapid growth of e-commerce. This study addresses the uncertainty concerning SDVs from a transport administrator’s perspective by identifying important factors for Trafikverket regarding the implementation of SDVs within freight transportation. Four already developed future plausible scenarios for the year 2030 lay the ground for this study and a case study concerning the supply chain of e-commerce in Sweden is used to delimitate the study. Interviews with distributors were held to conduct the case and two workshops with experts within the transport sector, academia, and authorities, as well as a meeting with a reference group with representatives from Trafikverket were held to collect data. In the workshops, the experts identified trends and system impacts within the four future scenarios. A key insight gained in this study is that SDVs is an area with a lot of insecurity and thus, it needs to be investigated further. One solution to study the subject further is to implement restricted lanes for SDVs to test the technique properly. The results of this study clearly show that even though SDVs is a topical issue, it should not be studied as a solitary subject but rather in a larger context together with other significant factors. Nighttime transports and deliveries, platooning, and electricroads and electric vehicles are three factors that are likely to be implemented very soon and should, therefore, be studied together with SDVs. Moreover, the result from the workshops implies that there will be an increased number of vehicles as well as vehicle kilometers within the distribution of e-commerce packages in the future. In addition, the experts expect SDVs to be present in the year 2030, but the number of SDVs depend on multiple factors.

O transporte de cargas desempenha um papel fundamental nos sistemas logísticos uma vez que possibilita o fluxo de produtos entre os elementos dos canais de distribuição, além de representar um elevado percentual de participação nos custos logísticos totais. Desse modo, a eficiência dos serviços de transporte depende diretamente de um adequado processo de planejamento em nível estratégico, tático e operacional. O transporte rodoviário, em particular, apresenta em nível operacional, problemas de elevada complexidade como a roteirização e o carregamento de veículos. Durante os últimos 50 anos estes problemas vêm sendo objeto de intensos estudos e desenvolvimentos, porém de forma separada, conduzindo a resultados difíceis de serem implementados nas situações práticas, devido à grande interdependência existente entre roteirização e carregamento de veículos. A resolução integrada destes dois problemas é recente na literatura, o que abre um campo bastante promissor para novos desenvolvimentos. Assim, esta tese tem como objetivo propor uma abordagem integrada de resolução para o problema de roteirização e carregamento de veículos onde, além das restrições de carregamento tridimensionais, as restrições de tempo de ciclo e distribuição de peso nos eixos são consideradas. Este modelo adota uma abordagem aproximativa que combina o uso de heurísticas para construção dos carregamentos com a metaheurística de Busca Tabu para melhoria dos roteiros de entrega. Para execução dos testes computacionais é proposto um conjunto de 12 instâncias que buscam simular situações práticas encontradas nas operações de entrega feitas por empresas de transporte e prestadores de serviços logísticos. A partir desse conjunto de instâncias são construídos cenários que avaliam o uso de diferentes tipos de veículos e os respectivos custos operacionais. Testes complementares realizados com um conjunto de 27 instâncias disponíveis na literatura, demonstram a capacidade do modelo proposto de atingir boas soluções em um tempo de processamento aceitável. / Freight transportation plays a fundamental role in logistics systems, once it enables the product flow between distribution channels elements, besides to represents a high percentage of participation on the total logistics costs. In this way, transport service efficiency depends directly of a suitable process of planning in strategic, tactical and operational level. The road transportation, in particular, shows in operational level high complexity problems as routing and loading of vehicles. During the last 50 years, these problems has been object of deep studies and developments, but in a separate manner, leading to results that are difficult to implement in practical situation due to the interdependence between routing and loading of vehicles. The integrated resolution of these two problems is recent in the literature, what opens a quite promising field for new developments. Thus, this thesis has as objective to propose an integrated resolution approach for the vehicle routing and loading where, besides the three-dimensional loading constraints, constraints, the time cicle and the distribution load over de axles are considered. This model adopts an approximated approach that combines the use of heuristics for loading construction with Tabu Search metaheuristics to improve the delivery routes. For computational tests execution is proposed a 12 instances set that tries to simulate practical situation found in delivery operations made by freight firms and thirty party logistics. From this instance set, it is built scenarios that evaluate the use of different vehicle types and the respectives operational costs. Complementary tests made with a 27 instances set available in literature show the capacity of proposed model to get good solutions in an acceptable computational time.

O transporte de cargas desempenha um papel fundamental nos sistemas logísticos uma vez que possibilita o fluxo de produtos entre os elementos dos canais de distribuição, além de representar um elevado percentual de participação nos custos logísticos totais. Desse modo, a eficiência dos serviços de transporte depende diretamente de um adequado processo de planejamento em nível estratégico, tático e operacional. O transporte rodoviário, em particular, apresenta em nível operacional, problemas de elevada complexidade como a roteirização e o carregamento de veículos. Durante os últimos 50 anos estes problemas vêm sendo objeto de intensos estudos e desenvolvimentos, porém de forma separada, conduzindo a resultados difíceis de serem implementados nas situações práticas, devido à grande interdependência existente entre roteirização e carregamento de veículos. A resolução integrada destes dois problemas é recente na literatura, o que abre um campo bastante promissor para novos desenvolvimentos. Assim, esta tese tem como objetivo propor uma abordagem integrada de resolução para o problema de roteirização e carregamento de veículos onde, além das restrições de carregamento tridimensionais, as restrições de tempo de ciclo e distribuição de peso nos eixos são consideradas. Este modelo adota uma abordagem aproximativa que combina o uso de heurísticas para construção dos carregamentos com a metaheurística de Busca Tabu para melhoria dos roteiros de entrega. Para execução dos testes computacionais é proposto um conjunto de 12 instâncias que buscam simular situações práticas encontradas nas operações de entrega feitas por empresas de transporte e prestadores de serviços logísticos. A partir desse conjunto de instâncias são construídos cenários que avaliam o uso de diferentes tipos de veículos e os respectivos custos operacionais. Testes complementares realizados com um conjunto de 27 instâncias disponíveis na literatura, demonstram a capacidade do modelo proposto de atingir boas soluções em um tempo de processamento aceitável. / Freight transportation plays a fundamental role in logistics systems, once it enables the product flow between distribution channels elements, besides to represents a high percentage of participation on the total logistics costs. In this way, transport service efficiency depends directly of a suitable process of planning in strategic, tactical and operational level. The road transportation, in particular, shows in operational level high complexity problems as routing and loading of vehicles. During the last 50 years, these problems has been object of deep studies and developments, but in a separate manner, leading to results that are difficult to implement in practical situation due to the interdependence between routing and loading of vehicles. The integrated resolution of these two problems is recent in the literature, what opens a quite promising field for new developments. Thus, this thesis has as objective to propose an integrated resolution approach for the vehicle routing and loading where, besides the three-dimensional loading constraints, constraints, the time cicle and the distribution load over de axles are considered. This model adopts an approximated approach that combines the use of heuristics for loading construction with Tabu Search metaheuristics to improve the delivery routes. For computational tests execution is proposed a 12 instances set that tries to simulate practical situation found in delivery operations made by freight firms and thirty party logistics. From this instance set, it is built scenarios that evaluate the use of different vehicle types and the respectives operational costs. Complementary tests made with a 27 instances set available in literature show the capacity of proposed model to get good solutions in an acceptable computational time.

É de fundamental importância que as empresas do setor de transporte rodoviário de cargas mantenham um processo contínuo de avaliação da sua produtividade. Tendo em vista que o setor é bastante competitivo, as empresas de transporte de carga necessitam rever suas políticas operacionais e de marketing, oferecendo serviços de qualidade e otimizando a utilização de seus recursos e insumos. O objetivo deste trabalho é propor um conjunto de indicadores de desempenho relacionados à produtividade que possa ser utilizado pelas empresas de transporte de carga. Com base na literatura técnica e em questionários aplicados a algumas empresas, é proposto um conjunto de indicadores de desempenho, segundo seu grau de importância e de facilidade de implantação. O resultado deste trabalho revela que as empresas utilizam de forma parcial as medidas de desempenho, que são fundamentais no processo de redução de custos e aumento na produtividade global. / lt is of fundamental importance that road freight transportation enterprises maintaining a continuous evaluation process of their productivity. As such sector is excessively competitive, freight transportation enterprises need to verify their operational and marketing policies, offering services of good quality and optimizing the utilization of their resources and inputs. The aim of this study is to propose a set of performance indicators related with productivity which can be used by freight transportation enterprises. From technical literature index collections and questionnaires sent by their enterprises, a set of performance indicators is proposed, according to importance level and implementation facility. The result of this research reveals that currently few enterprises use in a controlled way these performance indicators that are fundamental in the cost reduction process and increasing the global productivity.

[pt] Esta dissertação de mestrado apresenta o desenvolvimento de um sistema computacional para fazer a alocação de fluxos de transporte de carga multiproduto em uma rede multimodal. Este sistema tem o objetivo de servir como uma ferramenta no planejamento estratégico de transporte. O software foi concebido inicialmente para trabalhar com o ótimo do sistema, minimizando o custo total de transporte na rede. Uma adaptação é sugerida, para que seja possível trabalhar também com o ótimo do usuário, minimizando as rotas individuais dos usuários da rede de transporte. Para fazer a alocação de fluxos multiproduto em uma rede multimodal o software utiliza o algoritmo de Frank-Wolfe que resolve o problema multimodal multiproduto. / [en] This dissertation presents the development of a computer system, wich performs the assignment of multicommodity freight transportation flows on a multimodal network. This systems should be used as a tool in strategic transportation planning. Initially the software the has been conceived to search for the system`s optimum, by minimizing the total transportation cost in the network. The Dissertation proposes an adaptation to make possible for the system to calculate the user`s optimum, by minimizing the costs of the individual paths of the transportation network users. To Implement the multicommodity flow assignment on the multimodal network, the software makes use of na adaptation of the Frank and Wolfe algorithm to solve the multimodal, multicommodity problem. / [es] En desarrollo