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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

Rozvozní problém s heterogenními vozidly / Vehicle routing problem with heterogeneous fleet

Künzelová, Barbora January 2014 (has links)
The master's thesis deals with the new modification of vehicle routing problem -- 3PL vehicle routing problem with heterogeneous fleet and split delivery. In addition to classical vehicle routing problem, we consider a heterogeneous suppliers fleet and also external carrier, which charges a fixed value per unit of transported goods. The reader is first introduces to vehicle routing problem, its history and possible solutions. Furthermore, the reader is acquainted with logistics and logistics providers. In the main part of this thesis is described 3PL vehicle routing problem and its mathematical model. At first we try to get optimal solution via CPLEX solver. But since this is an NP-hard task, heuristic method is proposed (in two variants) for solving this problem. The heuristic is then tested on the selected test tasks. Results obtained using the proposed heuristics are compared with the optimal solution. Even larger problems are then solved using this heuristics. In the end other modifications and possible improvements of this heuristic method are proposed.
12

Método beam search aplicado ao problema de escalonamento de tarefas flexível / Beam search method applied to the flexible job shop scheduling problem

José Eurípedes Ferreira de Jesus Filho 06 June 2013 (has links)
O Job Shop Scheduling Problem é um problema NP-Difícil que chama a atenção de muitos pesquisadores devido seu desafio matemático e sua aplicabilidade em contextos reais. Geralmente, principalmente em cenários próximos aos de fábricas e indústrias, obter um escalonamento ótimo por meio de métodos computacionais exatos implica em um alto desprendimento de tempo. Em contrapartida, devido às exigências de um mercado cada vez mais competitivo, as decisões de onde, como, quando e com o que produzir devem ser tomadas rapidamente. O presente trabalho propõe o desenvolvimento de um método heurístico Beam Search para solucionar o Job Shop Scheduling Problem e o Flexible Job Shop Scheduling Problem. Para isso, inicialmente um algoritmo do tipo list scheduling é definido e então o método Beam Search é construído baseado neste algoritmo. Os métodos propostos foram avaliados em diferentes níveis de complexidade utilizando instâncias da literatura que retratam diferentes cenários de planejamento. Em linhas gerais, as soluções encontradas se mostraram bastante competitivas quando comparadas a outras soluções da literatura. / The Job Shop Scheduling Problem is a NP-Hard problem which draws the attention of researchers due to both its mathematical challenge and its applicability in real contexts. Usually, mainly in industry and factory environments, an optimal schedule got by the use of exact computational methods implies in a long spending time. On the other hand, due to a more and more competitive marketplace, the decisions on where, how, when and with which to produce must be taken quickly. The present work proposes the development of an heuristic Beam Search method to solve both the Job Shop Scheduling Problem and the Flexible Job Shop Scheduling Problem. To that end, at rst a list scheduling algorithm is dened and then the Beam Search method is built based on the list scheduling algorithm. The proposed methods were evaluated over dierent complexity levels using instances from the literature that report dierent planning environments. In general terms, the solutions implemented have been proved very competitive when compared against other solutions in the literature.
13

Podpora manažerského rozhodování o dopravních sítích / Support of management decision-making on transport networks

Přibyl, Vladimír January 2009 (has links)
The presented thesis is focused on a set of problems related to managerial decision-making concerning networks (particularly transportation networks), respectively - if we put it more precisely - the thesis focuses on the support of this decision-making by means of quantitative methods. A set of problems related to nets and decision-making concerning their individual parts or elements represents a very complex sphere which has been a subject of research for a number of decades. Out of this sphere, the thesis formulates and elaborates in great detail two problems, which - from the point of view of their practical significance - are important for the decision-making of managers of carriers, or the public sphere, and which have not been published in this form yet. The main point is the problem of how to find a subnet with a limited prolongation of routes between important pairs of vertices. Another problem is a design of a bus route in an area with a low demand. For each of these problems, the thesis offers an exact combinatorial solution method, furthermore a method based on integer linear programming, and - last but not least - also, of course, heuristic methods of solution. All these methods have been tested on a set of networks, which has been created for this purpose in a pseudo-random way in the frame of this thesis. The testing has been focused primarily on the comparison of the results provided by heuristic methods, which are of great importance - with regard to a great computational difficulty of exact methods - for feasible tasks on a larger scale. The tests have proved that the proposed heuristic methods are practically applicable and show results whicheven represent the optimal solution in a number of cases, or are only slightly distant from the optimal solution.
14

The effect of using Lakatos' heuristic method to teach surface area of cone on students' learning : the case of secondary school mathematics students in Cyprus

Dimitriou-Hadjichristou, Chrysoula 02 1900 (has links)
The purpose of this study was to examine the effect of using Lakatos’ heuristic method to teach the surface area of the cone (SAC) on students’ learning. The Lakatos (1976) heuristic framework and the Oh (2010) model of “the enhanced-conflict map” were employed as framework for the study. The first research question examined the impact of the Lakatosian heuristic method on students’ learning of the SAC, which was addressed in three sub-questions: the impact of the method on the students’ achievement, the impact of the method on their conceptual learning and the impact of the method on their higher order thinking skills. The second question examined whether the heuristic method of teaching the SAC helped students to sustain their learning better than the traditional method (Euclidean method). The third question examined whether the heuristic method of teaching SAC could change students’ readiness level, according to Bloom’s taxonomy. A pre-test and post-test quasi-experimental research design was used in the study that involved a total of 198 Grade 11 students (98 in the experimental group and 100 in the control group) from two schools in Cyprus. The instruments used for data collection were cognitive tests, lesson observations (video-recorded), interviews and questionnaire. Data was analysed using inferential statistics and the Oh (2010) model of the enhanced conflict map. Student achievement within time was the dependent variable and the method of training the independent variable. Therefore, time was the “within” factor and each group was measured three times (pre-test, post-test and delayed). The differences in students’ achievement within each group over time were examined. Results indicated that the average mean score achievement of the students in the experimental group was double that of the students in the control group. The Jun- Young Oh’s model of the enhanced conflict map showed that students in both groups changed from alternative conceptions to scientific conceptions with the experimental group showing greater improvement. It was also observed that from the post-test to delayed test, the Lakatosian method of teaching the SAC has a significant positive effect on students’ achievement at all levels of Bloom’s taxonomy, especially at the higher order thinking (HOT) levels (application and analysis-synthesis levels) as compared to the Euclidean method of teaching. In addition, the Lakatosian method helped the students to sustain their learning over time better than the Euclidean method did and also helped them to change their readiness level, especially at the HOT levels. The Lakatosian method helped students to foster skills that promote active learning. Of great importance was the use of mathematical language, as well as, the enhanced perception in the experimental group in comparison with the control group, through the use of the Lakatosian method. The results of this study are promising. It is recommended that pre-service teachers should be trained on how to effectively implement the Lakatosian heuristic method in their teaching. / Mathematics Education / D. Phil. (Mathematics, Science and Technology Education (Mathematics Education))
15

Livros didáticos e a matemática do ginásio: um estudo da vulgata para a reforma Francisco Campos

Pires, Inara Martins Passos 05 November 2004 (has links)
Made available in DSpace on 2016-04-27T16:58:12Z (GMT). No. of bitstreams: 1 dissertacao_inara_martins_pires.pdf: 12123644 bytes, checksum: fd8a44b5f2ad765d8ea36378d4c0608e (MD5) Previous issue date: 2004-11-05 / This study analyses how Mathematics, as a school subject, developed itself within the first years of its creation, from the so-called Francisco Campos Reform, in 1931. Based on the ideas of academics such as André Chervel and Roger Chartier, among others, the study intends to answer the following question: How Brazilian school books, which have been written after the Francisco Campos Reform, organized and stabilized the Mathematics as a subject, which was created from the fusion of Arithmetic, Algebra, and Geometry. The answer to such a question points towards the appropriation of the official text, which reveals to us incorporations of the project of globally restructuring the teaching of Mathematics from the heuristic method / Esta pesquisa analisa como se desenvolveu a disciplina escolar Matemática nos primeiros anos de sua criação, a partir da chamada Reforma Francisco Campos, de 1931. Lançando mão de teóricos como André Chervel e Roger Chartier, dentre outros, o trabalho busca responder à questão: Como os livros didáticos escritos a partir da Reforma organizaram e estabilizaram a nova disciplina, Matemática, criada a partir da fusão da Aritmética, da Álgebra e da Geometria. A resposta à questão aponta para uma apropriação do texto oficial, que revela a nós incorporações do projeto de reestruturar globalmente o ensino da Matemática a partir do método heurístico
16

The effect of using Lakatos' heuristic method to teach surface area of cone on students' learning : the case of secondary school mathematics students in Cyprus

Dimitriou-Hadjichristou, Chrysoula 02 1900 (has links)
The purpose of this study was to examine the effect of using Lakatos’ heuristic method to teach the surface area of the cone (SAC) on students’ learning. The Lakatos (1976) heuristic framework and the Oh (2010) model of “the enhanced-conflict map” were employed as framework for the study. The first research question examined the impact of the Lakatosian heuristic method on students’ learning of the SAC, which was addressed in three sub-questions: the impact of the method on the students’ achievement, the impact of the method on their conceptual learning and the impact of the method on their higher order thinking skills. The second question examined whether the heuristic method of teaching the SAC helped students to sustain their learning better than the traditional method (Euclidean method). The third question examined whether the heuristic method of teaching SAC could change students’ readiness level, according to Bloom’s taxonomy. A pre-test and post-test quasi-experimental research design was used in the study that involved a total of 198 Grade 11 students (98 in the experimental group and 100 in the control group) from two schools in Cyprus. The instruments used for data collection were cognitive tests, lesson observations (video-recorded), interviews and questionnaire. Data was analysed using inferential statistics and the Oh (2010) model of the enhanced conflict map. Student achievement within time was the dependent variable and the method of training the independent variable. Therefore, time was the “within” factor and each group was measured three times (pre-test, post-test and delayed). The differences in students’ achievement within each group over time were examined. Results indicated that the average mean score achievement of the students in the experimental group was double that of the students in the control group. The Jun- Young Oh’s model of the enhanced conflict map showed that students in both groups changed from alternative conceptions to scientific conceptions with the experimental group showing greater improvement. It was also observed that from the post-test to delayed test, the Lakatosian method of teaching the SAC has a significant positive effect on students’ achievement at all levels of Bloom’s taxonomy, especially at the higher order thinking (HOT) levels (application and analysis-synthesis levels) as compared to the Euclidean method of teaching. In addition, the Lakatosian method helped the students to sustain their learning over time better than the Euclidean method did and also helped them to change their readiness level, especially at the HOT levels. The Lakatosian method helped students to foster skills that promote active learning. Of great importance was the use of mathematical language, as well as, the enhanced perception in the experimental group in comparison with the control group, through the use of the Lakatosian method. The results of this study are promising. It is recommended that pre-service teachers should be trained on how to effectively implement the Lakatosian heuristic method in their teaching. / Mathematics Education / D. Phil. (Mathematics, Science and Technology Education (Mathematics Education))
17

Caracterização e modelagem da histerese e das perdas magnéticas em aços elétricos através do SCaMMa / Characterization and modeling of the hysteresis and the magnetic losses in silicon steels through the SCaMMa

Pinheiro, Matheus Levi Paranaguá 26 October 2016 (has links)
Submitted by JÚLIO HEBER SILVA (julioheber@yahoo.com.br) on 2016-11-22T18:13:24Z No. of bitstreams: 2 Dissertação - Matheus Levi Paranaguá Pinheiro - 2016.pdf: 7647037 bytes, checksum: bf9bc878e354cc06e12bc89d9e7be3c6 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Jaqueline Silva (jtas29@gmail.com) on 2016-11-30T15:46:12Z (GMT) No. of bitstreams: 2 Dissertação - Matheus Levi Paranaguá Pinheiro - 2016.pdf: 7647037 bytes, checksum: bf9bc878e354cc06e12bc89d9e7be3c6 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2016-11-30T15:46:13Z (GMT). No. of bitstreams: 2 Dissertação - Matheus Levi Paranaguá Pinheiro - 2016.pdf: 7647037 bytes, checksum: bf9bc878e354cc06e12bc89d9e7be3c6 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-10-26 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / Initially in this work, are presented the development and implementation of a new methodology to control the magnetic induction waveform, which was inserted into the automated measurement system for the characterization of soft magnetic materials, called SCaMMa. In the sequence, studies related to the magnetic hysteresis and to the magnetic losses, especially in silicon steels, are presented. The magnetic hysteresis in silicon steels has been analysed through the inverse version of the Jiles–Atherton classical model and through a modified one found in the literature. Concerning the determination of its parameters, the theory and the computational implementation of the heuristic method known as “Shuffled Frog Leaping Algorithm (SFLA)” have been addressed. Within this context, it was possible to investigate two drawbacks of the Jiles–Atherton model: i) the modeling of the so–called inner loops; and ii) the modeling of the minor loops. In the study of the magnetic losses in silicon steels, it was employed in this work the Bertotti´s model, which establishes the total magnetic losses division in three independent components: hysteresis losses, classical losses, and excess losses. It was investigated two versions of this model, so–called B1 and B2, in which the magnetic hysteresis losses are modeled respectively through the Steinmetz´s model and through the theory of two–portion hysteresis losses subdivision: the one so-called high induction hysteresis losses, and the other, low induction hysteresis losses. Due to some failures, a new approach was chosen reviewing two of the model coefficients calculation: the one related to the classic loss, and the other related to the excess loss. After this reviewing, the magnetic loss models could present predictions that are more exact. / Apresenta-se inicialmente neste trabalho o desenvolvimento e a implementação de uma nova metodologia para controlar a forma de onda da indução magnética, a qual foi inserida no sistema de medição automatizado para a caracterização de materiais magnéticos moles, denominado SCaMMa. Na sequência, apresentam-se estudos relativos à histerese magné- tica e às perdas magnéticas que ocorrem nesses materiais, especialmente os aços para fins elétricos. A histerese magnética em aços para fins elétricos foi abordada através da versão inversa do modelo clássico de Jiles–Atherton e através de uma versão modificada, encontrada na literatura, desse mesmo modelo. Em relação à determinação dos parâmetros desse modelo, são abordadas a teoria e a implementação computacional do método heurístico conhecido como “Algoritmo do Embaralhamento dos Sapos Saltitantes” (tradução livre de Shuffled Frog Leaping Algorithm (SFLA)). Nesse contexto, pôde-se investigar duas deficiências do modelo de Jiles–Atherton: modelagem dos laços de histerese ditos internos e modelagem dos laços de histerese menores. No estudo das perdas magnéticas em aços elétricos, empregou–se o modelo de Bertotti, o qual estabelece a divisão das perdas magnéticas totais em três componentes independentes: perdas por histerese, perdas clássicas e perdas em excesso. Foram investigadas duas versões desse modelo, os modelos denominados B1 e B2, nos quais as perdas por histerese são modeladas respectivamente através do modelo de Steinmetz e da teoria de subdivisão destas perdas em duas outras: perdas por histerese em altas e em baixas induções. Diante de alguns insucessos, optou-se por uma nova abordagem desse assunto, fazendo uma revisão do cálculo dos coeficientes relacionados à perda clássica e à perda em excesso desses modelos. Essa revisão se mostrou bastante efetiva, no sentido de que a partir de então, os modelos de previsão de perdas possibilitaram a obtenção de resultados mais exatos.

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