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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.
11

An advanced tabu search approach to the intratheater airlift operations problem with split loading

Martin, Kiel 20 November 2012 (has links)
This dissertation details an algorithm to solve the Intratheater Airlift Operations Problem (IAOP) using advanced tabu search. A solution to the IAOP determines the routes and assignment of customer requests to a fleet of aircraft over a given time horizon. This problem and other variants comprise an ongoing challenge for United States Air Force (USAF) planners who manage detailed logistics throughout many theaters of operations. Attributes of the IAOP include cargo time windows, multiple cargo types, multiple vehicle cargo bay configurations, vehicle capacity, route duration limits, and port capacities. The IAOP multi-criteria objective embraces several components with the primary goal of satisfying as much of the demand as possible while minimizing cost. The algorithm is extended to allow split load deliveries of customer requests, allowing a shipment to be split into two or more sub-loads which are delivered separately to the customer. The split load relaxation, while significantly increasing the complexity of the problem, allows for possible improvement in the solution. The necessary changes to the model and algorithm are detailed, providing a foundation to extend any local search algorithm solving a vehicle routing problem to allow split loading. Results allowing split loading are presented and compared with results without split loading. The algorithm is also extended to include a rolling time horizon. Starting from a solution found at a previous time step, the algorithm is limited on how the solution can be modified. This reflects the reality of operations in which near-term plans are locked as they approach and enter execution while longer-term plans are continually updated as new information arrives. / text
12

Pickup and delivery problems with side constraints

Qu, Yuan, Ph. D. 22 February 2013 (has links)
Pickup and delivery problems (PDPs) have been studied extensively in past decades. A wide variety of research exits on both exact algorithms and heuristics for generic variations of the problem as well as real-life applications, which continue to spark new challenges and open up new opportunities for researchers. In this dissertation, we study two variations of pickup and delivery problem that arise in industry and develop new computational methods that are shown to be effective with respect to existing algorithms and scheduling procedures found in practice. The first problem is the pickup and delivery problem with transshipment (PDPT). The work presented here was inspired by a daily route planning problem at a regional air carrier. In structuring the analysis, we describe a unique way to model the transshipment option on a directed graph. With the graph as the foundation, we implemented a branch and price algorithm. Preliminary results showed that it has difficulty in solving large instances. As an alternative, we developed a greedy randomized adaptive search procedure (GRASP) with several novel features. In the construction phase, shipment requests are inserted into routes until all demand is satisfied or no feasible insertion exists. In the improvement phase, an adaptive large neighborhood search algorithm is used to reconstruct portions of the feasible routes. Specialized removal and insertion heuristics were designed for this purpose. We also developed a procedure for generating problem instances in the absence of any in the literature. Testing was done on existing PDP data sets and generated PDPT data set. For the former, the performance and solution quality of the GRASP were comparable to the best known heuristics. For the latter, GRASP found the near optimal solution in most test cases. In the second part of the dissertation, we focus on a new version of the heterogeneous PDP in which the capacity of each vehicle can be modified by reconfiguring its interior to satisfy different types of customer demands. The work was motivated by a daily route planning problem arising at a senior activity center. A fleet of configurable vans is available each day to transport participants to and from the center as well as to secondary facilities for rehabilitative and medical treatment. To find solutions, we developed a two-phase heuristic that makes use of ideas from greedy randomized adaptive search procedures with multiple starts. In phase I, a set of good feasible solutions is constructed using a series of randomized procedures. A representative subset of those solutions is selected as candidates for improvement by solving a max diversity problem. In phase II, an adaptive large neighborhood search (ALNS) heuristic is used to find local optima by reconstructing portions of the feasible routes. Also, a specialized route feasibility check with vehicle type reassignment is introduced to take full advantage of the heterogeneous nature of vehicles. The effectiveness of the proposed methodology is demonstrated by comparing the solutions it provided for the equivalent of several weeks with those that were used in practice and derived manually. The analysis indicates that anywhere from 30% to 40% savings can be achieved with the multi-start ALNS heuristic. An exact method is introduced based on branch and price and cut for settings with more restricted time windows. In the procedure, the master problem at each node in the search tree is solved by column generation to find a lower bound. To improve the bound, subset-row inequalities are applied to the variables of the master problem. Columns are generated by solving the pricing subproblems with a labeling algorithm enhanced by new dominance conditions. Local search on the columns is used to quickly find promising alternatives. Implementation details and ways to improve the performance of the overall procedure are discussed. Testing was done on a set of real instances as well as a set of randomly generated instances with up to 50 customer requests. The results show that optimal solutions are obtained in majority of cases. / text
13

In search of student engagement in high school physics through contextual teaching

Lukie, Michael Paul 23 July 2012 (has links)
This action research study compared student intellectual engagement between two different instructional delivery methods. The first instructional method was a non-contextual teaching approach using a textbook to teach the work outcomes for the S4 physics mechanics unit. The second instructional method was a contextual teaching approach where students built an electric guitar pickup and a simple electric guitar in order to provide a context for the teaching of the electromagnetism outcomes for the S4 physics electricity unit. To measure the intellectual engagement of students, data was collected from personal student journals and from questions generated by students following different instructional activities. The student generated questions were categorized and ranked to judge the degree of student intellectual engagement and depth of thought using a framework where numerical values were assigned to the questions. Each question was categorized as peripheral, factual, conceptual, or philosophical where the peripheral questions had the lowest intellectual ranking and the philosophical questions had the highest intellectual ranking. Data was also collected from cumulative unit tests, short exit slips and a personal teacher journal. The research revealed that students were more intellectually engaged and exhibited much more positive attitudes during the contextual lessons. The questions generated by students during the contextual lessons were of the higher order factual and conceptual types while the questions generated during the non-contextual lessons were predominantly of the lowest order peripheral type. By using the electric guitar and electric guitar pickup as a context, this action research study demonstrated that these contextual activities intellectually engaged students and helped to facilitate their deeper understanding of electromagnetism.
14

In search of student engagement in high school physics through contextual teaching

Lukie, Michael Paul 23 July 2012 (has links)
This action research study compared student intellectual engagement between two different instructional delivery methods. The first instructional method was a non-contextual teaching approach using a textbook to teach the work outcomes for the S4 physics mechanics unit. The second instructional method was a contextual teaching approach where students built an electric guitar pickup and a simple electric guitar in order to provide a context for the teaching of the electromagnetism outcomes for the S4 physics electricity unit. To measure the intellectual engagement of students, data was collected from personal student journals and from questions generated by students following different instructional activities. The student generated questions were categorized and ranked to judge the degree of student intellectual engagement and depth of thought using a framework where numerical values were assigned to the questions. Each question was categorized as peripheral, factual, conceptual, or philosophical where the peripheral questions had the lowest intellectual ranking and the philosophical questions had the highest intellectual ranking. Data was also collected from cumulative unit tests, short exit slips and a personal teacher journal. The research revealed that students were more intellectually engaged and exhibited much more positive attitudes during the contextual lessons. The questions generated by students during the contextual lessons were of the higher order factual and conceptual types while the questions generated during the non-contextual lessons were predominantly of the lowest order peripheral type. By using the electric guitar and electric guitar pickup as a context, this action research study demonstrated that these contextual activities intellectually engaged students and helped to facilitate their deeper understanding of electromagnetism.
15

Conception et évaluation d'outils décisionnels pour des systèmes réactifs d'aide à la mobilité / Design and evaluation of decision-making tools for reactive mobility support systems

Ren, Libo 05 October 2012 (has links)
Dans le cadre de cette thèse, nous nous intéressons au traitement des problèmes d’optimisation combinatoire liés à la conception d’outils de gestion des systèmes de véhicules partagés. Ces problèmes sont proches des problèmes de collecte et de livraison. Après avoir réalisé une étude théorique sur des problèmes d’optimisation combinatoire autour du transport et des méthodes de résolutions, nous nous sommes intéressés ici à trois problèmes particuliers : le PPRV, le PPRV-PM et le PPRV-T. Le premier problème est le Problème de Planification du Redéploiement de Véhicules partagés (PPRV). C’est une extension du One-commodity Pickup-and-Delivery Problem (1-PDP) car les véhicules partagés sont indifférenciés. Nous avons proposé un modèle linéaire et une heuristique utilisant le schéma hybride ILS/VND. L’approche développée repose sur la stratégie « route-first, cluster-second » : on commence par construire une tournée géante, puis on l’améliore par une procédure de perturbation et une recherche locale. Pendant la recherche locale, la contrainte de capacité des véhicules est momentanément relaxée et progressivement restaurée ; la tournée géante obtenue est ensuite transformée en plusieurs tournées à l’aide de la procédure Split. Les deux problèmes suivants sont considérés comme des extensions du PPRV en autorisant des livraisons partielles : PPRV avec Passage Multiple (PPRV-PM) et PPRV avec Transfert d’objets (PPRV-T). Nous proposons une approche de type « divide-first, route-second » pour la résolution du PPRV-PM. Elle consiste à effectuer d’abord un fractionnement de la demande, puis la résoudre à l’aide d’un schéma hybride de type GRASP/VND. Le PPRV-T étend le PPRV-PM au transfert d’objets entre les transporteurs lors du passage sur un sommet. Nous avons reformulé le PPRV-T comme un problème de multi-flots couplés sur un réseau dynamique. Nous avons proposé une méthode d’insertion basée sur cette modélisation. / In this thesis, we are interested to deal with combinatorial optimization problems related to design management tools for vehicle-sharing systems. These problems are close to the Pickup-and-Delivery Problems (PDP) in the literature. After performing a survey on the problems area and on the resolution methods, we focused on three specific problems and we proposed one approach for each problem. The first one is the sharing Vehicles Redeployment Planning Problem (VRPP), which is considered as a multi-vehicles extension of the One-commodity Pickup-and-Delivery Problem (1-PDP). We proposed a linear model and a hybrid heuristic which combines the ILS and VND. The proposed approach uses the rout-first, cluster-second strategy: we construct a Hamiltonian route, and then improve it using a procedure combines a shacking step and a VND local search. The used neighborhoods are adapted to the relaxation of capacity; the obtained route would be then split into several vehicles tours in the clustering phase.The two following problems are considered as extensions of VRPP introducing the split demand constraint : VRPP with Multi-Passage (VRPP-MP) and VRPP with Transferring objects (VRPP-T). We proposed an approach with the divide-first, route-second strategy for VRPP-MP. It consists of dividing in advance the demand, and then solves it using a hybrid scheme of GRASP/VND. In the VRPP-T, the objects carried could be exchanged between carriers when crossing on the sites. The VRPP-T is modeled here as a multi-flows problem on a dynamic network. We proposed an insertion method based on this modeling.
16

Busca tabu aplicada ao problema de roteamento de veiculos com coleta e entrega / A tabu search for the vehicle routing problem with pickup and delivery

Goraieb, Elias 14 October 2005 (has links)
Orientador: Vinicius Amaral Armentano / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-06T12:38:24Z (GMT). No. of bitstreams: 1 Goraieb_Elias_M.pdf: 21259035 bytes, checksum: 5e5d4e69c800350a20727695a2f33647 (MD5) Previous issue date: 2005 / Resumo: Este trabalho aborda o problema de roteamento de veículos com coleta e entrega, visando à minimização do número de veículos utilizado e a distância total percorrida. O pedido de serviço é atendido por um veículo na janela de tempo imposta pelo cliente, e envolve uma coleta na origem que precede a entrega no destino. A capacidade dos veículos é limitada e uma rota tem duração máxima. Um algoritmo de busca tabu é proposto para a resolução deste problema. Diversas estratégias avançadas são incorporadas ao algoritmo, tais como redução de vizinhança, diversificação da busca, e utilização da metodologia path relinking / Abstract: This work considers the vehicle routing problem with pickup and delivery with the objectives of minimizing the fleet size and the total traveI distance. Each service request is served by a vehicle within time windows imposed by the clients, and involves a pickup origin that precedes a delivery destination. The capacity of the vehicle and the total route duration are limited. A tabu search algorithm is proposed to solve this problem. Several advanced strategies are incorporated in the algorithm, such as neighborhood reduction, search diversification, and path relinking / Mestrado / Engenharia de Sistemas / Mestre em Engenharia Elétrica
17

'The World is Not a Safe Place for Men': The Representational Politics of the Manosphere

Lilly, Mary January 2016 (has links)
This thesis offers an overview of the representational politics of the online antifeminist community known as the ‘manosphere’. It analyzes how gender and gender politics are represented in the discourse, with an eye to how traditional gender constructs, and traditional gendered norms and inequalities, are reproduced. This project—the first study to focus exclusively on the manosphere—contributes to our understanding of the community in two ways; it addresses a significant gap in the literature on the topic, and it tests the accuracy of the ‘conventional wisdom’ on the manosphere. Using mixed-methods critical discourse analysis, the study analyzed the discourse of the two primary subcultures of the community, and found that traditional gender norms and relations are reproduced therein, and that for the most part the conventional wisdom is accurate: femininity and women are disparaged, masculinity is imagined to be ‘in crisis’ (constantly under siege by feminizing forces), and feminism is represented as hypocritical and oppressive.
18

Elektrické housle s MIDI výstupem / Electric Volin with MIDI Output

Spilka, Benedikt January 2018 (has links)
The main aim of this diploma thesis is to design and to construct a electric violin with MIDI output. This thesis include design and conctruction of violin pickup, violin electronic and software for translation of sound into MIDI messages. design of the instrument´s body is presented at the end of the thesis. Violin electronic include circuits for filtration, amplification, processing and AD/DA conversion of audio siganl. Software for MIDI transfer recognizes notes and translates them to MIDI messages.
19

Metody optimalizace plánování nákladní přepravy / Optimizations Methods for Freight Transportation

Gabonay, Michal January 2020 (has links)
The following work concerns the study of the evolutionary algorithm, which optimizes freight transport planning. The demand for freight transport is constantly increasing nowadays and with creating, implementing and using proper route planning we are able to significantly reduce transportation costs. However, it is preferably to implement it in companies with large numbers of served customers and with a sufficiently large fleet of vehicles.   The study starts by defining what fright transport planning problem is and by characterizing its existing specifications and variants. My work proceeds to give a background of the possible solutions to the multifaceted aspects of the problem. The specific subproblem I choose to focus on is the Vehicle routing problem with Pickup and Delivery for which I apply the optimization solution. In the main body of my thesis, I will elaborate on the chosen optimization solution which encompasses the genetic algorithm and evolutionary strategy. The aim of the study is to measure the suitability of the algorithms and techniques used, for which reason the final part of my work will deal with the analysis and evaluation of the experiments.
20

Models and algorithms for fleet management of autonomous vehicles / Modèles et algorithmes de gestion de flottes de véhicules autonomes

Bsaybes, Sahar 26 October 2017 (has links)
Résumé indisponible. / The VIPAFLEET project aims at developing a framework to manage a fleet of IndividualPublic Autonomous Vehicles (VIPA). We consider a fleet of cars distributed at specifiedstations in an industrial area to supply internal transportation, where the cars can beused in different modes of circulation (tram mode, elevator mode, taxi mode). The goalis to develop and implement suitable algorithms for each mode in order to satisfy all therequests either under an economic point aspect or under a quality of service aspect, thisby varying the studied objective functions.We model the underlying online transportation system as a discrete event basedsystem and propose a corresponding fleet management framework, to handle modes,demands and commands. We consider three modes of circulation, tram, elevator andtaxi mode. We propose for each mode appropriate online algorithms and evaluate theirperformance, both in terms of competitive analysis and practical behavior by computationalresults. We treat in this work, the pickup and delivery problem related to theTram mode and the Elevator mode the pickup and delivery problem with time windowsrelated to the taxi mode by means of flows in time-expanded networks.

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