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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.
131

Uma col?nia de formigas para o caminho mais curto multiobjetivo

Bezerra, Leonardo Cesar Teon?cio 07 February 2011 (has links)
Made available in DSpace on 2015-03-03T15:47:46Z (GMT). No. of bitstreams: 1 LeonardoCTB_DISSERT.pdf: 2119704 bytes, checksum: 5bdd21de8bfa668bba821593cdd5289f (MD5) Previous issue date: 2011-02-07 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / Multi-objective combinatorial optimization problems have peculiar characteristics that require optimization methods to adapt for this context. Since many of these problems are NP-Hard, the use of metaheuristics has grown over the last years. Particularly, many different approaches using Ant Colony Optimization (ACO) have been proposed. In this work, an ACO is proposed for the Multi-objective Shortest Path Problem, and is compared to two other optimizers found in the literature. A set of 18 instances from two distinct types of graphs are used, as well as a specific multiobjective performance assessment methodology. Initial experiments showed that the proposed algorithm is able to generate better approximation sets than the other optimizers for all instances. In the second part of this work, an experimental analysis is conducted, using several different multiobjective ACO proposals recently published and the same instances used in the first part. Results show each type of instance benefits a particular type of instance benefits a particular algorithmic approach. A new metaphor for the development of multiobjective ACOs is, then, proposed. Usually, ants share the same characteristics and only few works address multi-species approaches. This works proposes an approach where multi-species ants compete for food resources. Each specie has its own search strategy and different species do not access pheromone information of each other. As in nature, the successful ant populations are allowed to grow, whereas unsuccessful ones shrink. The approach introduced here shows to be able to inherit the behavior of strategies that are successful for different types of problems. Results of computational experiments are reported and show that the proposed approach is able to produce significantly better approximation sets than other methods / Problemas de otimiza??o combinat?ria multiobjetivo apresentam caracter?sticas peculiares que exigem que t?cnicas de otimiza??o se adaptem a esse contexto. Como muitos desses problemas s?o NP-?rduos, o uso de metaheur?sticas tem crescido nos ?ltimos anos. Particularmente, muitas abordagens que utilizam a Otimiza??o por Col?nias de Formigas t?m sido propostas. Neste trabalho, prop?e-se um algoritmo baseado em col?nias de formigas para o Problema do Caminho mais Curto Multiobjetivo, e compara-se o algoritmo proposto com dois otimizadores encontrados na literatura. Um conjunto de 18 inst?ncias oriundas de dois tipos de grafos ? utilizado, al?m de uma metodologia espec?fica para a avalia??o de otimizadores multiobjetivo. Os experimentos iniciais mostram que o algoritmo proposto consegue gerar conjuntos de aproxima??o melhores que os demais otimizadores para todas as inst?ncias. Na segunda parte do trabalho, uma an?lise experimental de diferentes abordagens publicadas para col?nias de formigas multiobjetivo ? realizada, usando as mesmas inst?ncias. Os experimentos mostram que cada tipo de inst?ncia privilegia uma abordagem algor?tmica diferente. Uma nova met?fora para o desenvolvimento deste tipo de metaheur?stica ? ent?o proposta. Geralmente, formigas possuem caracter?sticas comuns e poucos artigos abordam o uso de m?ltiplas esp?cies. Neste trabalho, uma abordagem com m?ltiplas esp?cies competindo por fontes de comida ? proposta. Cada esp?cie possui sua pr?pria estrat?gia de busca e diferentes esp?cies n?o tem acesso ? informa??o dada pelo ferom?nio das outras. Como na natureza, as popula??es de formigas bem sucedidas tem a chance de crescer, enquanto as demais se reduzem. A abordagem apresentada aqui mostra-se capaz de herdar o comportamento de estrat?gias bem-sucedidas em diferentes tipos de inst?ncias. Resultados de experimentos computacionais s?o relatados e mostram que a abordagem proposta produz conjuntos de aproxima??o significativamente melhores que os outros m?todos
132

Qualidade de serviço em rede IP utilizando logica fuzzy / Quality of service in IP network using fuzzy logic

Resende, Raulison Alves, 1970- 31 July 2006 (has links)
Orientador: Akebo Yamakami / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-06T20:32:53Z (GMT). No. of bitstreams: 1 Resende_RaulisonAlves_D.pdf: 558127 bytes, checksum: 8c65274e70573045a52e4b1101a2c32e (MD5) Previous issue date: 2006 / Resumo: A teoria de conjuntos fuzzy provê um ferramental para desenvolver processos aproximados de raciocínio quando a informação disponível é incerta, incompleta, imprecisa ou vaga. Com as novas ferramentas emergentes na área de inteligência computacional, tais como lógicas não padronizadas, redes neurais e raciocínio simbólico, esta nova teoria é um acréscimo bem-vindo ao repertório de ferramentas tradicionais apropriadas. Neste sentido, esta tese propõe três estratégias para o provimento de qualidade de serviço em redes IP, usando lógica fuzzy. Como primeira proposta é implementado um módulo inteligente para gerenciamento da QoS por meio da criação de políticas para roteadores do tipo DiffServ. A segunda estratégia consiste em um algoritmo fuzzy que resolve o problema de roteamento baseado em restrição de tempo com mínimo custo. Esta proposta apresentou resultados satisfatórios quando comparada com a solução sem lógica fuzzy. E, por último, se propõe um controlador de admissão de conexão para tratar as informações com certo grau de incertezas em redes IP com MPLS. O controlador apresenta as seguintes vantagens: flexibilização da admissão de conexão e possibilidade de incluir mais informações da rede e do tráfego na tomada da decisão sem aumentar consideravelmente a complexidade do controlador / Abstract: Fuzzy set theory provides a machinery for carrying out approximate reasoning processes when available information is uncertain, incomplete, imprecise, or vague. With the emergence of new tools in the area of computational intelligence, such as non standard logics, neural networks, and symbolic reasoning, this new theory is a welcome addition to the repertoire of traditional appropriate tools. In this sense, this thesis proposes three different strategies to apply Fuzzy Logic to provide QoS in IP Networks. The first one is the implementation of an intelligent, policy-based module for QoS management. The module permits the creation of policies to configure QoS in routers and a practical implementation has been performed for a DiffServ router. The second strategy proposes a fuzzy algorithm to solve the problem of routing based on time restrictions with minimum costs. The results obtained from this algorithm were satisfactory when compared to similar solutions that did not involve fuzzy logic. Finally, the third strategy proposes a Connection Admission Controller to process information that contains a high level of uncertainty in IP networks over MPLS. The controller offers the following advantages: flexibility for connections admission and the possibility of including more network and traffic information in the decision making process without considerably increasing the controller complexity / Doutorado / Telecomunicações e Telemática / Doutor em Engenharia Elétrica
133

Zona de empate : o elo entre transformadas de watershed e conexidade nebulosa / Tie-zone : the bridge between watershed transforms and fuzzy connectedness

Audigier, Romaric Matthias Michel 13 August 2018 (has links)
Orientador: Roberto de Alencar Lotufo / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-13T08:32:02Z (GMT). No. of bitstreams: 1 Audigier_RomaricMatthiasMichel_D.pdf: 1753584 bytes, checksum: 1d31eb6f095099ffb5c3ec8d0a96a9cf (MD5) Previous issue date: 2007 / Resumo: Esta tese introduz o novo conceito de transformada de zona de empate que unifica as múltiplas soluções de uma transformada de watershed, conservando apenas as partes comuns em todas estas, tal que as partes que diferem constituem a zona de empate. A zona de empate aplicada ao watershed via transformada imagem-floresta (TZ-IFT-WT) se revela um elo inédito entre transformadas de watershed baseadas em paradigmas muito diferentes: gota d'água, inundação, caminhos ótimos e floresta de peso mínimo. Para todos esses paradigmas e os algoritmos derivados, é um desafio se ter uma solução única, fina, e que seja consistente com uma definição. Por isso, propõe-se um afinamento da zona de empate, único e consistente. Além disso, demonstra-se que a TZ-IFT-WT também é o dual de métodos de segmentação baseados em conexidade nebulosa. Assim, a ponte criada entre as abordagens morfológica e nebulosa permite aproveitar avanços de ambas. Em conseqüência disso, o conceito de núcleo de robustez para as sementes é explorado no caso do watershed. / Abstract: This thesis introduces the new concept of tie-zone transform that unifies the multiple solutions of a watershed transform, by conserving only the common parts among them such that the differing parts constitute the tie zone. The tie zone applied to the watershed via image-foresting transform (TZ-IFTWT) proves to be a link between watershed transforms based on very different paradigms: drop of water, flooding, optimal paths and forest of minimum weight. For all these paradigms and the derived algorithms, it is a challenge to get a unique and thin solution which is consistent with a definition. That is why we propose a unique and consistent thinning of the tie zone. In addition, we demonstrate that the TZ-IFT-WT is also the dual of segmentation methods based on fuzzy connectedness. Thus, the bridge between the morphological and the fuzzy approaches allows to take benefit from the advance of both. As a consequence, the concept of cores of robustness for the seeds is exploited in the case of watersheds. / Doutorado / Engenharia de Computação / Doutor em Engenharia Elétrica
134

Robustness and preferences in combinatorial optimization

Hites, Romina 15 December 2005 (has links)
In this thesis, we study robust combinatorial problems with interval data. We introduce several new measures of robustness in response to the drawbacks of existing measures of robustness. The idea of these new measures is to ensure that the solutions are satisfactory for the decision maker in all scenarios, including the worst case scenario. Therefore, we have introduced a threshold over the worst case costs, in which above this threshold, solutions are no longer satisfactory for the decision maker. It is, however, important to consider other criteria than just the worst case.<p>Therefore, in each of these new measures, a second criteria is used to evaluate the performance of the solution in other scenarios such as the best case one. <p><p>We also study the robust deviation p-elements problem. In fact, we study when this solution is equal to the optimal solution in the scenario where the cost of each element is the midpoint of its corresponding interval. <p><p>Then, we finally formulate the robust combinatorial problem with interval data as a bicriteria problem. We also integrate the decision maker's preferences over certain types of solutions into the model. We propose a method that uses these preferences to find the set of solutions that are never preferred by any other solution. We call this set the final set. <p><p>We study the properties of the final sets from a coherence point of view and from a robust point of view. From a coherence point of view, we study necessary and sufficient conditions for the final set to be monotonic, for the corresponding preferences to be without cycles, and for the set to be stable.<p>Those that do not satisfy these properties are eliminated since we believe these properties to be essential. We also study other properties such as the transitivity of the preference and indifference relations and more. We note that many of our final sets are included in one another and some are even intersections of other final sets. From a robust point of view, we compare our final sets with different measures of robustness and with the first- and second-degree stochastic dominance. We show which sets contain all of these solutions and which only contain these types of solutions. Therefore, when the decision maker chooses his preferences to find the final set, he knows what types of solutions may or may not be in the set.<p><p>Lastly, we implement this method and apply it to the Robust Shortest Path Problem. We look at how this method performs using different types of randomly generated instances. <p> / Doctorat en sciences, Orientation recherche opérationnelle / info:eu-repo/semantics/nonPublished
135

Quelques Algorithmes pour des problèmes de plus court chemin et d'opérations aériennes / Algorithms for shortest path and airline problems

Parmentier, Axel 10 November 2016 (has links)
Cette thèse développe des algorithmes pour les problèmes de plus court chemin sous cont-rain-tes de ressources, et les applique à l'optimisation des rotations des avions et des équipages d'une compagnie aérienne dans le cadre d'approches par génération de colonnes.Les problèmes de plus court chemin sous contraintes de ressources sont généralement résolus grâce à une énumération intelligente de tous les chemins non dominés. Les approches récentes utilisent des bornes sur les ressources des chemins pour éliminer des solutions partielles. L'efficacité de la méthode est conditionnée par la qualité des bornes utilisées. Notre principale contribution au domaine est l'introduction d'une procédure générique pour calculer des bornes qui s'applique à la plupart des problèmes de chemins sous contraintes, et en particulier les problèmes stochastiques. A cette fin, nous introduisons une généralisation du problème de plus court chemin sous contraintes dans laquelle les ressources des chemins appartiennent à un monoïde ordonné comme un treillis. La ressource d'un chemin est la somme des ressources de ses arcs, le terme somme désignant l'opérateur du monoïde. Le problème consiste à trouver parmi les chemins qui satisfont une contrainte donnée celui dont la ressource minimise une fonction de coût croissante de la ressource des chemins. Nous généralisons les algorithmes d'énumération à ce nouveau problème. La théorie des treillis nous permet de construire une procédure polynomiale pour trouver des bornes de qualité. L'efficacité pratique de la méthode est évaluée au travers d'une étude numérique détaillée sur des problèmes de chemins déterministes et stochastiques. Les procédures de calcul des bornes peuvent être interprétées comme des généralisations aux monoïdes ordonnés comme des treillis d'algorithmes de la littérature définis pour résoudre un problème de chemin pour lequel les ressources des chemins prennent leur valeur dans un semi-anneau.Nos algorithmes de chemins ont été appliqués avec succès au problème de crew pairing. Étant donné un ensemble de vols opérés par une compagnie aérienne, les problèmes d'aircraft routing et de crew pairing construisent respectivement les séquences de vols opérées par les avions et par les équipages de manière à couvrir tous les vols à moindre coût. Comme certaines séquences de vols ne peuvent être réalisées par un équipage que s'il reste dans le même avion, les deux problèmes sont liés. La pratique actuelle dans l'industrie aéronautique est de résoudre tout d'abord le problème d'aircraft routing, puis le problème de crew pairing, ce qui aboutit à une solution non-optimale. Des méthodes de résolution pour le problème intégré ont été développées ces dix dernières années. Nous proposons une méthode de résolution pour le problème intégré reposant sur deux nouveaux ingrédients : un programme linéaire en nombre entier compact pour le problème d'aircraft routing, ainsi que de nouveaux pour le problème esclave de l'approche usuelle par génération de colonnes du problème de crew pairing. Ces algorithmes pour le problème esclave sont une application de nos algorithmes pour le problème de plus court chemin sous contraintes. Nous généralisons ensuite cette approche de manière à prendre en compte des contraintes de probabilités sur la propagation du retard. Ces algorithmes permettent de résoudre quasiment à l'optimum les instances industrielles d'Air France / This thesis develops algorithms for resource constrained shortest path problems, and uses them to solve the pricing subproblems of column generation approaches to some airline operations problems.Resource constrained shortest path problems are usually solved using a smart enumeration of the non-dominated paths. Recent improvements of these enumeration algorithms rely on the use of bounds on path resources to discard partial solutions. The quality of the bounds determines the performance of the algorithm. Our main contribution to the topic is to introduce a standard procedure to generate bounds on paths resources in a general setting which covers most resource constrained shortest path problems, among which stochastic versions. In that purpose, we introduce a generalization of the resource constrained shortest path problem where the resources are taken in a lattice ordered monoid. The resource of a path is the monoid sum of the resources of its arcs. The problem consists in finding a path whose resource minimizes a non-decreasing cost function of the path resource among the paths that satisfy a given constraint. Enumeration algorithms are generalized to this framework. We use lattice theory to provide polynomial procedures to find good quality bounds. The efficiency of the approach is proved through an extensive numerical study on deterministic and stochastic path problems. Interestingly, the bounding procedures can be seen as generalizations to lattice ordered monoids of some algebraic path problem algorithms which initially work with resources in a semiring.Given a set of flight legs operated by an airline, the aircraft routing and the crew pairing problem build respectively the sequences of flight legs operated by airplanes and crews at minimum cost. As some sequences of flight legs can be operated by crews only if they stay in the same aircraft, the two problems are linked. The current practice in the industry is to solve first the aircraft routing, and then the crew pairing problem, leading to a non-optimal solution. During the last decade, solution schemes for the integrated problem have been developed. We propose a solution scheme for the integrated problem based on two new ingredients: a compact integer program approach to the aircraft routing problem, and a new algorithm for the pricing subproblem of the usual column generation approach to the crew pairing problem, which is based on our resource constrained shortest path framework. We then generalize the algorithm to take into account delay propagation through probabilistic constraints. The algorithms enable to solve to near optimality Air France industrial instances
136

Système de gestion du stationnement dans un environnement dynamique et multi-objectifs / Parking management system in a dynamic and multi-objective environment

Ratli, Mustapha 12 December 2014 (has links)
Aujourd'hui, le problème de stationnement devient l'un des enjeux majeurs de la recherche dans la planification des transports urbains et la gestion du trafic. En fait, les conséquences de l'absence de places de stationnement ainsi que la gestion inadéquate de ces installations sont énormes. L'objectif de cette thèse est de fournir des algorithmes efficaces et robustes afin que les conducteurs gagnent du temps et de l'argent et aussi augmenter les revenus des gestionnaires de parking. Le problème est formulé comme un problème d'affectation multi-objectifs dans des environnements statique et dynamique. Tout d'abord, dans l'environnement statique, nous proposons de nouvelles heuristiques en deux phases pour calculer une approximation de l'ensemble des solutions efficaces pour un problème bi-objectif. Dans la première phase, nous générons l'ensemble des solutions supportées par un algorithme dichotomique standard. Dans la deuxième phase, nous proposons quatre métaheuristiques pour générer une approximation des solutions non supportées. Les approches proposées sont testées sur le problème du plus court chemin bi-objectif et le problème d'affectation bi-objectif. Dans le contexte de l'environnement dynamique, nous proposons une formulation du problème sous forme d'un programme linéaire en nombres entiers mixtes qui est résolue à plusieurs reprises sur un horizon de temps donné. Les fonctions objectives considérées, permettent un équilibre entre la satisfaction des conducteurs et l'intérêt du gestionnaire de parking. Deux approches sont proposées pour résoudre ce problème d'affectation dynamique avec ou sans phase d'apprentissage. Pour renforcer la phase d'apprentissage, un algorithme à estimation de distribution est proposé pour prévoir la demande future. Pour évaluer l'efficacité des algorithmes proposés, des essais de simulation ont été effectués. Aussi une mise en œuvre pilote a été menée dans le parking à l'Université de Valenciennes en utilisant une plateforme existante, appelée Context Aware Transportation Services (CATS), qui permet le déploiement dynamique de services. Cette plate-forme peut dynamiquement passer d'une approche à l'autre en fonction du contexte. Enfin cette thèse s'inscrit dans le projet SYstem For Smart Road Applications ( SYFRA). / The parking problem is nowadays one of the major issues in urban transportation planning and traffic management research. In fact, the consequences of the lack of parking slots along with the inadequate management of these facilities are tremendous. The aim of this thesis is to provide efficient and robust algorithms in order to save time and money for drivers and to increase the income of parking managers. The problem is formulated as a multi-objective assignment problem in static and dynamic environments. First, for the static environment, we propose new two-phase heuristics to calculate an approximation of the set of efficient solutions for a bi-objective problem. In the first phase, we generate the supported efficient set with a standard dichotomic algorithm. In the second phase we use four metaheuristics to generate an approximation of the non-supported efficient solutions. The proposed approaches are tested on the bi-objective shortest path problem and the biobjective assignment problem. For the dynamic environment, we propose a mixed integer linear programming formulation that is solved several times over a given horizon. The objective functions consist of a balance between the satisfaction of drivers and the interest of the parking managers. Two approaches are proposed for this dynamic assignment problem with or without learning phase. To reinforce the learning phase, an estimation of distribution algorithm is proposed to predict the future demand. In order to evaluate the effectiveness of the proposed algorithms, simulation tests have been carried out. A pilot implementation has also been conducted in the parking of the University of Valenciennes, using an existing platform called framework for context aware transportation services, which allows dynamic deployment of services. This platform can dynamically switch from one approach to another depending on the context. This thesis is part of the project SYstem For Smart Road Applications (SYFRA).
137

Dynamic Graph Generation and an Asynchronous Parallel Bundle Method Motivated by Train Timetabling

Fischer, Frank 09 July 2013 (has links)
Lagrangian relaxation is a successful solution approach for many combinatorial optimisation problems, one of them being the train timetabling problem (TTP). We model this problem using time expanded networks for the single train schedules and coupling constraints to enforce restrictions like station capacities and headway times. Lagrangian relaxation of these coupling constraints leads to shortest path subproblems in the time expanded networks and is solved using a proximal bundle method. However, large instances of our practical partner Deutsche Bahn lead to computationally intractable models. In this thesis we develop two new algorithmic techniques to improve the solution process for this kind of optimisation problems. The first new technique, Dynamic Graph Generation (DGG), aims at improving the computation of the shortest path subproblems in large time expanded networks. Without sacrificing any accuracy, DGG allows to store only small parts of the networks and to dynamically extend them whenever the stored part proves to be too small. This is possible by exploiting the properties of the objective function in many scheduling applications to prefer early paths or due times, respectively. We prove that DGG can be implemented very efficiently and its running time and the size of nodes that have to be stored additionally does not depend on the size of the time expanded network but only on the length of the train routes. The second technique is an asynchronous and parallel bundle method (APBM). Traditional bundle methods require one solution of each subproblem in each iteration. However, many practical applications, e.g. the TTP, consist of rather loosely coupled subproblems. The APBM chooses only small subspaces corresponding to the Lagrange multipliers of strongly violated coupling constraints and optimises only these variables while keeping all other variables fixed. Several subspaces of disjoint variables may be chosen simultaneously and are optimised in parallel. The solutions of the subspace problem are incorporated into the global data as soon as it is available without any synchronisation mechanism. However, in order to guarantee convergence, the algorithm detects automatically dependencies between different subspaces and respects these dependencies in future subspace selections. We prove the convergence of the APBM under reasonable assumptions for both, the dual and associated primal aggregate data. The APBM is then further extended to problems with unknown dependencies between subproblems and constraints in the Lagrangian relaxation problem. The algorithm automatically detects these dependencies and respects them in future iterations. Again we prove the convergence of this algorithm under reasonable assumptions. Finally we test our solution approach for the TTP on some real world instances of Deutsche Bahn. Using an iterative rounding heuristic based on the approximate fractional solutions obtained by the Lagrangian relaxation we are able to compute feasible schedules for all trains in a subnetwork of about 10% of the whole German network in about 12 hours. In these timetables 99% of all passenger trains could be scheduled with no significant delay and the travel time of the freight trains could be reduced by about one hour on average.
138

Balancing of Network Energy using Observer Approach

Patharlapati, Sai Ram Charan 01 September 2016 (has links)
Efficient energy use is primarily for any sensor networks to function for a longer time period. There have been many efficient schemes with various progress levels proposed by many researchers. Yet, there still more improvements are needed. This thesis is an attempt to make wireless sensor networks with further efficient on energy usage in the network with respect to rate of delivery of the messages. In sensor network architecture radio, sensing and actuators have influence over the power consumption in the entire network. While listening as well as transmitting, energy is consumed by the radio. However, if by reducing listening times or by reducing the number of messages transmitting would reduce the energy consumption. But, in real time scenario with critical information sensing network leads to information loss. To overcome this an adaptive routing technique should be considered. So, that it focuses on saving energy in a much more sophisticated way without reducing the performance of the sensing network transmitting and receiving functionalities. This thesis tackles on parts of the energy efficiency problem in a wireless sensor network and improving delivery rate of messages. To achieve this a routing technique is proposed. In this method, switching between two routing paths are considered and the switching decision taken by the server based on messages delivered comparative previous time intervals. The goal is to get maximum network life time without degrading the number of messages at the server. In this work some conventional routing methods are considered for implementing an approach. This approach is by implementing a shortest path, Gradient based energy routing algorithm and an observer component to control switching between paths. Further, controlled switching done by observer compared to normal initial switch rule. Evaluations are done in a simulation environment and results show improvement in network lifetime in a much more balanced way.
139

Route Planning of Battery Electric Heavy-Duty Commercial Vehicles : Using Contraction Hierarchies and Mixed Integer Programming

Delborg, Olle, Insulander, Elias January 2023 (has links)
This thesis addresses route planning of Battery Electric Heavy-Duty Commercial Vehicles to enhance the reliability of electric vehicle transport. Collaborating with Scania, a Swedish truck manufacturing company, the goal is to develop a pipeline that uses open source data from OpenStreetMap and performs a modified Contraction Hierarchy in order to create a graph that can be used as input to a modified Vehicle Routing Problem formulation using Mixed Integer Programming. The input graph is preprocessed to support a Battery Electric Heavy-Duty Commercial Vehicle model in order to more accurately predict energy consumption. The challenges lie in balancing computational efficiency and electric vehicle characteristics. The implemented pipeline demonstrates success but initial tests show that a naive version of the pipeline, not implementing Contraction Hierarchies, can perform better. Several speedups can be made in order to improve the efficiency of the pipeline, the main being in programming in a more efficient programming language than Python. Further testing is needed for larger input graphs to assess performance accurately.
140

Reproducibility and Applicability of a Fuzzy-based Routing Algorithm in Wireless Sensor Networks

Rönningen, Hannes, Olofsson, Erik January 2023 (has links)
Wireless sensor networks is a broad subject with many applications and interesting research areas, such as optimization within connectivity and energy efficiency. One problem is that most published articles in this field use customized simulation environments and do not provide source code of their implementation. By not including aspects of implementation, it becomes difficult to determine how the results are achieved, which questions the validity and reliability of the works. This thesis aims to reproduce one of these researched methods, an algorithm that balances battery life with efficient routing within a network using fuzzy logic, with the goal to increase the reliability of the methodology within its field. The research question constructed on the foundation of these premises is thus “Is reproducibility satisfactory in a research work on a multi-objective routing algorithm, using fuzzy logic, in wireless sensor networks?, a case study by Minhas et al”. Two additional research questions emerge from the first one: “How does the reproduced algorithm perform in comparison to a selection of dif erent routing algorithms?” and “Is the reproduced algorithm, as is, applicable to a less idealistic environment?” To answer the research questions a computer simulation method is used to build, execute, and analyze the output of the algorithms. The results show that the implemented algorithm performs noticeably better in both lifetime and ratio to the shortest path compared with the original implementation, hinting towards the implementation and reproducibility deviating from expected results. The reproduced algorithm is also compared to two other algorithms under a different simulation environment, where it performs better in lifetime and packet delivery rate whilst performing slightly worse in energy efficiency and total energy consumption. Due to the significant differences in performance against the reproduced article’s implementation the study concludes that the reproducibility is not satisfactory. Lastly, it concludes that it does not perform well in a less idealistic simulation environment, making it less applicable.

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