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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.
31

Link-focused prediction of bike share trip volume using GPS data: A GIS based approach

Brown, Matthew January 2020 (has links)
Modern bike share systems (BSSs) allow users to rent from a fleet of bicycles at hubs across the designated service area. With clear evidence of cycling being a health-positive form of active transport, furthering our understanding of the underlying processes that affect BSS ridership is essential to continue further adoption. Using 286,587 global positioning system (GPS) trajectories over a 12-month period between January 1st, 2018 and December 31st, 2018 from a BSS called SoBi (Social Bicycles) Hamilton, the number of trips on every traveled link in the service area are predicted. A GIS-based map-matching toolkit is used to generate cyclists’ routes along the cycling network of Hamilton, Ontario to determine the number of observed unique trips on every road segment (link) in the study area. To predict trips, several variables were created at the individual link level including accessibility measures, distances to important locations in the city, proximity to active travel infrastructure (SoBi hubs, bus stops), and bike infrastructure. Linear regression models were used to estimate trips. Eigenvector spatial filtering (ESF) was used to explicitly model spatial autocorrelation. The results suggest the largest positive predictors of cycling traffic in terms of cycling infrastructure are those that are physically separated from the automobile network (e.g., designated bike lanes). Additionally, hub-trip distance accessibility, a novel measure, was found to be the most significant variable in predicting trips. A demonstration of how the model can be used for strategic planning of road network upgrades is also presented. / Thesis / Master of Science (MSc)
32

Stability Analysis of Systems of Difference Equations

Clinger, Richard A. 01 January 2007 (has links)
Difference equations are the discrete analogs to differential equations. While the independent variable of differential equations normally is a continuous time variable, t, that of a difference equation is a discrete time variable, n, which measures time in intervals. A feature of difference equations not shared by differential equations is that they can be characterized as recursive functions. Examples of their use include modeling population changes from one season to another, modeling the spread of disease, modeling various business phenomena, discrete simulations applications, or giving rise to the phenomena chaos. The key is that they are discrete, recursive relations. Systems of difference equations are similar in structure to systems of differential equations. Systems of first-order linear difference equations are of the form x(n + 1) = Ax(n) , and systems of first-order linear differential equations are of the form x(t) = Ax(t). In each case A is a 2x2 matrix and x(n +1), x(n), x(t), and x(t) are all vectors of length 2. The methods used in analyzing systems of difference equations are similar to those used in differential equations.Solutions of scalar, second-order linear difference equations are similar to those of scalar, second-order differential equations, but with one major difference: the composition of their general solutions. When the eigenvalues of A, λ1 and λ2, are real and distinct, general solutions of differential equations are of the form x(t) = c1eλ1t +c2eλ2t, while general solutions of difference equations are of form x(n) = 1λn1 + c2λn2. So, on the one hand, while the methods used in examining systems of difference equations are similar to those used for systems of differential equations; on the other hand, their general solutions can exhibit significantly different behavior.Chapter 1 will cover systems of first-order and second-order linear difference equations that are autonomous (all coefficients are constant). Chapter 2 will apply that theory to the local stability analysis of systems of nonlinear difference equations. Finally, Chapter 3 will give some example of the types of models to which systems of difference equations can be applied.
33

Grafos e suas aplicações / Graphs and their applications

Santos Júnior, Jânio Alves dos 14 December 2016 (has links)
Submitted by Cássia Santos (cassia.bcufg@gmail.com) on 2017-01-26T09:20:52Z No. of bitstreams: 2 Dissertação - Jânio Alves dos Santos Júnior - 2016.pdf: 3798217 bytes, checksum: c2acd93260ead52c126f4b37d994825f (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2017-01-30T10:25:56Z (GMT) No. of bitstreams: 2 Dissertação - Jânio Alves dos Santos Júnior - 2016.pdf: 3798217 bytes, checksum: c2acd93260ead52c126f4b37d994825f (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-01-30T10:25:56Z (GMT). No. of bitstreams: 2 Dissertação - Jânio Alves dos Santos Júnior - 2016.pdf: 3798217 bytes, checksum: c2acd93260ead52c126f4b37d994825f (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-12-14 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / This work aims to study some topics of graph theory in order to solve some problems. In order to complement, we approached a light study of matrices, eigenvalues and eigenvectors. The first problem is known as Königsberg Bridge Problem, where this was considered the problem that gave rise to the study on graphs. The House Problem is a joke, which shows us several propositions about planar and bipartite graphs. Some models we can relate graphs, such as we can observe in the problem of cannibals and in the game of chess. Finally, we will work with applications in the adjacency matrix as in the Problem of the Condominium of Farms and in the Number of Possible Paths in a graph, where we will work with geometric figures, apparently resolving a counting problem using eigenvalues and graph. As a methodological support will be approached Linear Algebra. / O objetivo deste trabalho é estudar alguns tópicos da teoria de grafos com o intuito de resolver alguns problemas. Para complementar, abordamos um leve estudo de matrizes, autovalores e autovetores. O primeiro problema é conhecido como o Problema da Ponte de Königsberg, onde tal, foi considerado o problema que deu origem ao estudo sobre grafos. O Problema das Casas que é uma brincadeira, que nos mostra várias proposições sobre grafos planares e bipartidos. Alguns modelos que podemos relacionar grafos, tais como veremos no problema dos canibais e no jogo de xadrez. Por fim, trabalharemos com aplicações na matriz de adjacência como no problema do Condomínio de Chácaras e no Número de Caminhos Possíveis em um Grafo, onde trabalharemos com figuras geométricas, resolvendo aparentemente um problema de contagem, utilizando autovalores e grafos. Como suporte metodológico será abordado Álgebra Linear.
34

Compressed wavefield extrapolation with curvelets

Lin, Tim T. Y., Herrmann, Felix J. January 2007 (has links)
An explicit algorithm for the extrapolation of one-way wavefields is proposed which combines recent developments in information theory and theoretical signal processing with the physics of wave propagation. Because of excessive memory requirements, explicit formulations for wave propagation have proven to be a challenge in {3-D}. By using ideas from ``compressed sensing'', we are able to formulate the (inverse) wavefield extrapolation problem on small subsets of the data volume, thereby reducing the size of the operators. According {to} compressed sensing theory, signals can successfully be recovered from an imcomplete set of measurements when the measurement basis is incoherent} with the representation in which the wavefield is sparse. In this new approach, the eigenfunctions of the Helmholtz operator are recognized as a basis that is incoherent with curvelets that are known to compress seismic wavefields. By casting the wavefield extrapolation problem in this framework, wavefields can successfully be extrapolated in the modal domain via a computationally cheaper operatoion. A proof of principle for the ``compressed sensing'' method is given for wavefield extrapolation in 2-D. The results show that our method is stable and produces identical results compared to the direct application of the full extrapolation operator.
35

Applications of Linear Algebra to Information Retrieval

Vasireddy, Jhansi Lakshmi 28 May 2009 (has links)
Some of the theory of nonnegative matrices is first presented. The Perron-Frobenius theorem is highlighted. Some of the important linear algebraic methods of information retrieval are surveyed. Latent Semantic Indexing (LSI), which uses the singular value de-composition is discussed. The Hyper-Text Induced Topic Search (HITS) algorithm is next considered; here the power method for finding dominant eigenvectors is employed. Through the use of a theorem by Sinkohrn and Knopp, a modified HITS method is developed. Lastly, the PageRank algorithm is discussed. Numerical examples and MATLAB programs are also provided.
36

Face Recognition Using Eigenfaces And Neural Networks

Akalin, Volkan 01 December 2003 (has links) (PDF)
A face authentication system based on principal component analysis and neural networks is developed in this thesis. The system consists of three stages / preprocessing, principal component analysis, and recognition. In preprocessing stage, normalization illumination, and head orientation were done. Principal component analysis is applied to find the aspects of face which are important for identification. Eigenvectors and eigenfaces are calculated from the initial face image set. New faces are projected onto the space expanded by eigenfaces and represented by weighted sum of the eigenfaces. These weights are used to identify the faces. Neural network is used to create the face database and recognize and authenticate the face by using these weights. In this work, a separate network was build for each person. The input face is projected onto the eigenface space first and new descriptor is obtained. The new descriptor is used as input to each person&amp / #8217 / s network, trained earlier. The one with maximum output is selected and reported as the host if it passes predefined recognition threshold. The algorithms that have been developed are tested on ORL, Yale and Feret Face Databases.
37

Solution Of Helmholtz Type Equations By Differential Quadarature Method

Kurus, Gulay 01 September 2000 (has links) (PDF)
This thesis presents the Differential Quadrature Method (DQM) for solving Helmholtz, modified Helmholtz and Helmholtz eigenvalue-eigenvector equations. The equations are discretized by using Polynomial-based and Fourier-based differential quadrature technique wich use basically polynomial interpolation for the solution of differential equation.
38

Largest eigenvalues of the discrete p-Laplacian of trees with degree sequences

Biyikoglu, Türker, Hellmuth, Marc, Leydold, Josef 08 November 2018 (has links)
Trees that have greatest maximum p-Laplacian eigenvalue among all trees with a given degree sequence are characterized. It is shown that such extremal trees can be obtained by breadth-first search where the vertex degrees are non-increasing. These trees are uniquely determined up to isomorphism. Moreover, their structure does not depend on p.
39

Esquemas cognitivos e mente matemática inerentes ao objeto matemático autovalor e autovetor: traçando diferenciais na formação do engenheiro

Nomura, Joelma Iamac 19 March 2014 (has links)
Made available in DSpace on 2016-04-27T16:57:30Z (GMT). No. of bitstreams: 1 Joelma Iamac Nomura.pdf: 7399337 bytes, checksum: 3b1b78708c15a38620c94201d8ab977e (MD5) Previous issue date: 2014-03-19 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The objective of this research harnesses to the results obtained in the Master's Dissertation defended in September 2008 in Postgraduate Studies Program in Mathematics Education at PUC - SP. In this same essay, issues related to teaching and learning of linear algebra sought to answer and find new ways of targeting and perspectives of students in a graduate in Electrical Engineering, asking Why and How should it be taught the discipline of linear algebra on a course with this profile? Among the results, we identified that the interdisciplinarity inherent to the topics of Linear Algebra and specific content of engineering or applied constituted an essential factor for the recognition of mathematical disciplines as theoretical and conceptual basis. Interdisciplinarity reflected in specific mathematical objects of linear algebra and practical situations of engineering materials for the formation of conceptual and general engineer seeking the theoretical foundation and basic justification for the technological improvement of its area. Based on a scenario and results envisioned in the dissertation we propose to investigate the cognitive structures involved in the construction of mathematical object eigenvalue and eigenvector in the initial and final student education phases in Engineering courses, showing the cognitive schemes in their mathematical minds. For this, the following issues are highlighted: ( 1 ) What conceptions (action - process -object- schema ) are evidenced in students after studying the mathematical object eigenvalue and eigenvector in the initial and final phases of their academic training courses in Engineering? and ( 2 ) these same phases, which concept image and concept definition are highlighted in the study of eigenvalue and eigenvector mathematical object? Substantiated by the theoretical contributions of Dubinsky (1991), on the APOS Theory and Vinner (1991), about the concept image and concept definition, we consider the cognitive processes involved in the construction of mathematical object, identifying the nature of their cognitive entities portrayed in mathematical mind. The discussion focuses on mathematical mind both the mathematical structure that is designed and shared by the community as the design in which each mental biological framework handles such ideas. To do so, we consider the relationship between the ideas which constitute the APOS theory, concepts image and definition and some aspects of Cognitive Neuroscience. Characterized as multiple case studies, data collection covered the speech of students in engineering courses in various training contexts, established by the institutions. The analysis of the specific mathematical concept called genetic decomposition led to this concept, which was proposed by System Dynamic Discrete problem, described by the difference equation K K x A.x 1 = + , (K = 0,1,2 , ... ) . Based on the ideas of Stewart (2008) and Trigueros et al. (2012) it was possible to us to identify some characteristics of showing the different conceptions of the students. Moreover, we consider some ideas that characterize the concept image and concept definition according Vinner (1991) and Domingos (2003). As a result of our investigation, we identified that the students of the first case study, at different stages of training, present the design process and the concept image on an instrumental level mathematical object eigenvalue and eigenvector. Have students in the second case, particularly, all of the first phase, and two of the second, showed signs of action and concept image incipient level. As a student of the second phase, have also highlighted the design process and the concept image on an instrumental level as the subject of the first case study. Therefore, we find no significant evolution between the inherent APOS Theory concepts and the concepts image of the object of study. We show that all students presented their speeches in relations between the Linear Algebra course and other courses in the program, such as Numerical Calculation, Electrical Circuits , Computer Graphics and Control Systems, with lesser or greater degree of depth and knowledge. We realize that students attach importance to mathematical disciplines in its formations and seek for a new approach to teaching that address the relationships between them and the disciplines of Engineering / O objetivo desta pesquisa atrela-se aos resultados obtidos na Dissertação de Mestrado defendida em setembro de 2008 no Programa de Estudos Pós-Graduados em Educação Matemática da PUC-SP. Nesta mesma dissertação, questões relacionadas ao ensino e aprendizagem de Álgebra Linear buscaram responder e encontrar novas formas de direcionamento e perspectivas de ensino em uma graduação em Engenharia Elétrica, indagando Por que e Como deve ser lecionada a disciplina de Álgebra Linear em um curso com este perfil? Dentre os resultados obtidos, identificou-se que a interdisciplinaridade inerente aos tópicos de Álgebra Linear e conteúdos específicos ou aplicados da Engenharia constituiu-se de fatores imprescindíveis para ao reconhecimento das disciplinas matemáticas, como base teórica e conceitual. A interdisciplinaridade refletida em objetos matemáticos específicos da Álgebra Linear e situações práticas da Engenharia prima pela formação do engenheiro conceitual e generalista que busca na fundamentação teórica e básica a justificativa para o aprimoramento tecnológico de sua área. Com base no cenário e resultados vislumbrados na defesa da dissertação, propusemonos investigar as estruturas cognitivas envolvidas na construção do objeto matemático autovalor e autovetor nas fases inicial e final de formação do aluno dos cursos de Engenharia, evidenciando os esquemas cognitivos e a mente matemática dos estudantes, sujeitos de nossa investigação. Para tanto, as seguintes questões são destacadas: (1) Quais concepções (ação-processo-objeto-esquema) são evidenciadas nos alunos, após o estudo do objeto matemático autovalor e autovetor nas fases inicial e final de sua formação acadêmica em cursos de Engenharia?; e (2) Nessas mesmas fases, quais conceitos imagem e definição são evidenciados no estudo do objeto matemático autovalor e autovetor? Fundamentados pelos aportes teóricos de Dubinsky (1991), sobre a Teoria APOS, e Vinner (1991) nos conceitos imagem e definição, foram considerados os processos cognitivos envolvidos na construção do objeto matemático, identificando a natureza de suas entidades cognitivas retratadas na mente matemática. A discussão sobre mente matemática foca-se tanto na estrutura matemática que é concebida e compartilhada pela comunidade como no delineamento em que cada estrutura biológica mental trata essas mesmas ideias. Para tanto, considerou-se a relação entre as ideias que constituem a Teoria APOS, os conceitos imagem e definição e alguns aspectos da Neurociência Cognitiva. A pesquisa caracterizada como estudos de caso múltiplos, identificou os dados a partir do discurso dos estudantes dos cursos de Engenharia em contextos diversos de formação, estabelecidos pelas instituições de ensino. A análise do conceito matemático específico levou à chamada decomposição genética desse conceito, que foi proposto pelo problema de Sistema Dinâmico Discreto, descrito pela equação de diferença K K x A.x 1 = + (K=0,1,2,...). Com base nas ideias de Stewart (2008) e Trigueros et al. (2012), foi possível identificar algumas características que evidenciassem as diferentes concepções dos estudantes. Além disso, foram consideradas algumas ideias que caracterizam o conceito imagem e definição de acordo com Vinner (1991) e Domingos (2003). Como resultado desta investigação, identificou-se que os alunos do primeiro estudo de caso, em fases distintas de formação, apresentam a concepção processo e o conceito imagem em nível instrumental do objeto matemático autovalor e autovetor. Já os alunos do segundo de caso, particularmente, todos os da primeira fase, e dois da segunda apresentaram indícios da concepção ação e conceito imagem em nível incipiente. Apenas um aluno da segunda fase também evidenciou ter a concepção processo e o conceito imagem em nível instrumental, como os sujeitos do primeiro estudo de caso. Portanto, constatou-se que não houve evolução significativa entre as concepções inerentes à Teoria APOS e os conceitos imagem do objeto de estudo. Evidenciou-se que todos os alunos apresentaram em seus discursos relações existentes entre a disciplina Álgebra Linear e demais disciplinas do curso, como Cálculo Numérico, Circuitos Elétricos, Computação Gráfica e Sistemas de Controle, com menor ou maior grau de profundidade e conhecimento. Percebe-se que os alunos atribuem relevância às disciplinas matemáticas em suas formações e buscam por um novo enfoque de ensino que contemple as relações entre as mesmas e as disciplinas da Engenharia
40

Social capital in large-scale projects and it's impact on Innovation: Social network analysis of Genome Canada (2000-2009)

2012 December 1900 (has links)
The contemporary era is witnessing a systemic transition in the Canadian science and research paradigm. The research world is shrinking rapidly in response to modern technological developments, commercial and regulatory integration, faster communications and transportation and proactive science, technology and innovation policy. It is increasingly challenging to make competitive progress in world-class innovation or to gain global leadership in science. Big-science is now proposed as one of the means to realize national innovation goals and international competitiveness. As a result, government support for large-scale innovation projects has increased multifold. This dissertation examines a range of hypotheses large-scale research projects enhance investigator exchanges and generate social capital that has significant downstream benefits, which would provide a reason to support big science beyond the instrumental goals of the projects themselves. Taking Genome Canada as an example, this dissertation examines the production and role of social capital generated through large-scale research projects to assess the evidence base for funding big science research. A group of 139 investigators who raised capital in the Genome Canada Applied Bioproducts and Crops (ABC) Competition in 2009 are examined in the context of their engagements and networks in 2000-2009 in four relational arenas, namely their area of expertise, institutional connections, research grants, and co-publications. The investigation reveals three main findings. First, large-scale innovation projects as delivered through Genome Canada, comply with the fundamentals of contemporary innovation network theory. Second, the ties amongst investigators generate social capital, which offers positional advantage and differential superior access to networked resources. Third, the social capital generated in actor relations has pronounced long term impacts on downstream research success. Inter-disciplinary and cross-institutional large-scale research projects that have strong elements of knowledge production and financial exchange are found to assist the federal government in advancing research and innovation objectives. The results of the current investigation provide a strong rationale for the integration of people, disciplines, and institutions under the umbrella of large-scale genomics and proteomics research, and possible lessons for other research fields.

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