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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.
51

Characterization of mobility patterns and collective behavior through the analytical processing of real-world complex networks. / Caracterização de padrões de mobilidade e comportamento coletivo por meio de processamento analítico de redes complexas do mundo real.

Gabriel Spadon de Souza 31 July 2017 (has links)
Cities are complex systems of transportation and social activity; their structure can be used to model urban street networks i.e. complex network that represents the geometry of a city allowing analytical activities for data-driven decision-making. The geometry of a city holds intrinsic information that can support activities related to the analysis of the urban scenario; of higher importance is the use of such information to enhance the quality of life of its inhabitants and/or to understand the dynamics of an urban center. Several of these analytical processes lacks in-depth methodologies to analyze crime patterns and ill-designed urban structures, which can provide for public safety and urban design. Consequently, it is our goal to provide means for the structural and topological analysis of highly criminal regions of cities represented as complex networks, and for the identification of urban planning inconsistencies that point to regions that lack access from/to points of interest in a city. In this regard, we devised a set of algebraic and algorithmic procedures that are capable of revealing patterns and provide for data comprehension. More specifically, we introduced pre-processing techniques to transform georeferenced electronic maps into graph representations of cities; we used metric-based and epidemic processes to understand the dynamics of cities in what refers to criminality; finally, we introduced a novel set of formalisms and operations based on set theory to identify design flaws concerning access in urban centers. Our results refer to approaches to preprocess and prepare maps in the form of urban street networks; to the analyses of crimes based on their spatial disposition; to the development of a model to describe criminal activities; and, to the advance of a concept based on critical problems in the urban design. / As cidades são sistemas complexos de interação social e de transporte. Suas estruturas podem ser usadas para modelar redes de mobilidade urbana i.e. redes complexas que representam a geometria de uma cidade permitindo a consecução de atividades analíticas para descoberta de padrões e para a tomada de decisão baseada em dados. A geometria da cidade carrega informações intrínsecas que auxiliam atividades relacionadas à análise de dados provenientes do cenário urbano. As informações inerentes a tais análises podem ser usadas para melhorar a qualidade de vida dos habitantes de uma região, ou para entender a dinâmica de centros urbanos. Diversos processos analíticos aplicados a tais cenários carecem de metodologias para analisar o padrão criminal e para identificar estruturas urbanas mal planejadas. Deste modo, este trabalho tem por objetivo prover meios para análise topológica de regiões criminais e para a identificação de inconsistências urbanas, as quais apontam para regiões que carecem de mobilidade e acesso para outras regiões de uma cidade. Neste sentido, foi desenvolvido um conjunto de procedimentos algébricos e algorítmicos capazes de revelar padrões e meios para compreensão e análise dos dados. Mais especificamente, foram desenvolvidos métodos de pré-processamento para transformar mapas eletrônicos georreferenciados em grafos que representam cidades, foi utilizado um conjunto métrico analítico e outro com base em processos epidêmicos para entender a dinâmica intrínseca à criminalidade de uma cidade, e por fim, foi desenvolvido um conjunto de formalismos e operações baseados em teoria dos conjuntos para identificar falhas no desenho das estruturas urbanas que impactam no acesso viário em centros urbanos. Os resultados deste trabalho versam sobre o desenvolvimento de novos métodos para preparar mapas na forma de redes de mobilidade urbana; na análise de crimes baseada em sua disposição espacial; no desenvolvimento de um modelo capaz de descrever a atividade criminal de uma cidade; e, em um conceito baseado na análise de regiões críticas identificadas a partir do desenho urbano.
52

Paralelização do modelo BioCrowds para simulação de multidões em GPU e inclusão do efeito de pressão / Parallelization of BioCrowds algorithm for crowd simulation and inclusion of pushing effect

Nakashima, Natasha Sayuri Dias, 1988- 22 August 2018 (has links)
Orientador: Léo Pini Magalhães / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-22T13:25:48Z (GMT). No. of bitstreams: 1 Nakashima_NatashaSayuriDias_M.pdf: 3103281 bytes, checksum: 8241ca52a460ba9e5002a04b4660e03f (MD5) Previous issue date: 2013 / Resumo: O BioCrowds é um modelo para simulação de multidões virtuais, proposto por Alessandro Bicho (2009), baseado no algoritmo de colonização do espaço, o qual foi originalmente concebido para geração de padrões de nervuras em folhas vegetais e de ramificações em árvores. Em sua implementação sequencial, o BioCrowds apresenta uma diminuição na taxa de quadros por segundo em simulações com grande número de indivíduos. O presente trabalho implementa uma proposta para a simulação de multidões virtuais utilizando o BioCrowds através de técnicas de computação paralela para unidade de processamento gráfico (GPU). Aborda-se também a inclusão no modelo do efeito de pressão (pushing), o qual está relacionado a cenários onde há grande densidade de indivíduos. Para a paralelização do algoritmo utilizou-se a plataforma OpenCL juntamente com a plataforma CUDA, presente nas placas NVIDIA. Nas simulações realizadas com o algoritmo BioCrowds paralelo, obteve-se um aumento na taxa de quadros por segundo mantendo a qualidade da simulação dos comportamentos emergentes em multidões reais / Abstract: BioCrowds is a method for crowd simulation proposed by Alessandro Bicho (2009) based on the biologically-motivated space colonization algorithm. This algorithm was originally introduced to model leaf venation patterns and the branching architecture of trees. However, the increase on the number of individuals corresponds to a decrease on the framerate of the simulation. This work implements a solution to simulate virtual crowds using the BioCrowds and parallel computing. Additionally it approaches an extension of BioCrowds to treat simulation scenarios where there is a narrowing in the route. This effect is named pushing. The proposed parallel algorithm was implemented using the OpenCL and NVIDIA CUDA framework. The simulations with this algorithm resulted in a increase on the framerate, maintaining the reproduction of emergent behaviors on real crowds / Mestrado / Engenharia de Computação / Mestra em Engenharia Elétrica
53

Food Distribution in Ant Colonies: Trophallaxis and Self-Organization

Gräwer, Johannes Sebastian 01 June 2017 (has links)
No description available.
54

Uzavřené rezidenční oblasti v Istanbulu 21. století / Twenty-First Century Gated Communities in Istanbul

Uçar, Mehmet Yiğitcan January 2017 (has links)
in English The idea of gated communities was coined in the USA in 1970s and was a result of the post-modern period and suburbanization. During modernization, cities had gone through social, cultural, political, and economical revisions. Consequently, business and residential areas in the city continued to evolve and create new forms. Following this period gated communities offered new understanding of life, security, relations, and status. Subsequently, the phenomenon has rapidly spread all around the world after the 1980s. Istanbul was introduced to the idea of gated communities in 1980s as a result of globalization by following a new vision of a Global City. Being the historical, cultural, and economic center of Turkey, Istanbul holds a great value in terms of social and economical investments. Following the international neoliberal economic trends, Istanbul has attracted many investors and a large labor force. Consequently, the rising demand of housing and business areas invigorated the real estate market in Istanbul, and gated communities were seen as a modern way of housing. As a result, a variety of gated communities were built in Istanbul to meet this new demand. In this research, the social and cultural reasons for livıng in the gated communities and their impacts towards to its residents...
55

Intergroup conflict in soccer stadiums

Mazibuko, Vela Onke January 2009 (has links)
The aim of the present research is to investigate three factors, namely perceptions of fairness in intergroup situations, ingroup identification and spatial dimensions that are assumed to contribute to why individuals participate in violence against the police in soccer stadiums. In Study 1 perceptions of fairness, identification and spatial perspective were manipulated and the results indicated a significant interaction effect between identification and spatial perspective. This interaction effect had a significant influence on negative behavioural tendencies towards police. In Study 2, identification and spatial perspective were manipulated and once again the interaction effect between identification and spatial perspective was found. A main effect of identification was found in that participants who identified lower with fans showed significantly more positive attitudes towards police. The results of the two studies highlight the importance of looking beyond the inherent nature of the crowd itself when analysing situations of police/fan conflict, and also the need to further investigate the spatial dimension and how it influences social judgment and decision making.
56

Coordinating Individual Behavior in Collective Processes; Seed Choice in Harvester Ants (Pogonomyrmex californicus)

January 2020 (has links)
abstract: Social animals benefit from the aggregation of knowledge and cognitive processing power. Part of this benefit comes from individual heterogeneity, which provides the basis to group-level strategies, such as division of labor and collective intelligence. In turn, the outcomes of collective choices, as well as the needs of the society at large, influence the behavior of individuals within it. My dissertation research addresses how the feedback between individual and group-level behavior affects individuals and promotes collective change. I study this question in the context of seed selection in the seed harvester ant, Pogonomyrmex californicus. I use both field and laboratory studies to explore questions relating to individual behavior: how forager decision-making is affected through information available in the nest and at the seed pile; how workers interact with seeds in the nest; and how forager preferences diverge from each other’s and the colony’s preference. I also explore the integration between individual and colony behavior, specifically: how interactions between the foraging and processing tasks affect colony collection behavior; how individual behavior changes affect colony preference changes and whether colony preference changes can be considered learning behavior. To answer these questions, I provided colonies with binary choices between seeds of unequal or similar quality, and measured individual, task group, and colony-level behavior. I found that colonies are capable of learning to discriminate between seeds, and learned information lasts at least one month without seed interaction outside of the nest. I also found that colony learning was coordinated by foragers receiving updated information from seeds in the nest to better discriminate and make choices between seed quality during searches for seeds outside of the nest. My results show that seed processing is essential for stimulating collection of novel seeds, and that foraging and processing are conducted by behaviorally and spatially overlapping but distinct groups of workers. Finally, I found that foragers’ preferences are diverse yet flexible, even when colonies are consistent in their preference at the population level. These combined experiments generate a more detailed and complete understanding of the mechanisms behind the flexibility of collective colony choices, how colonies incorporate new information, and how workers individually and collectively make foraging decisions for the colony in a decentralized manner. / Dissertation/Thesis / Doctoral Dissertation Biology 2020
57

The Effects of Social Structure on Social Movements in Turkey

Can, Ali 08 1900 (has links)
The main objective of this study is to provide an in-depth analysis the association between a set of social structural factors and the certain types of social movement events in Turkey. The changing nature and significance of social movements over time and space makes this study necessary to understand and explain new trends related to the parameters that constitute a backdrop for social movements. Social movements are a very common mechanism used by groups of people who decide to take action against an unfair socio-political system, usually an authoritarian government or dictatorship. This kind of reactions, seen in history before, gives birth to a more multidimensional understanding of the relationship between society and state policies. Understanding social movements depends on understanding our own societies, and the social environment in which they are developed. An effective way of understanding this type of social movements is to recognize the perceived concerns of discontented groups in relation to cultural, ideological, economic, and political institutions and values. Social movement events included in the study refers to collective activities organized by two or more people with the purpose of protesting public policies or of increasing public awareness about certain social issues related to human rights and freedoms, environment, feminism, etc. All these types of events are chased by police forces, and their concerns, statements, and activities are recorded.
58

An optimization-based model of collective motion

Theriault, Diane H. 28 November 2015 (has links)
Computational models of collective motion have yielded many insights about the way that groups of animals or simulated particles may move together and self-organize. Recent literature has compared predictions of models with large datasets of detailed observations of animal behavior, and found that there are important discrepancies, leading researchers to reexamine some of the most widely used assumptions. We introduce FlockOpt, an optimization-based, variable-speed, self-propelled particle model of collective motion that addresses important shortcomings of earlier models. In our model, each particle adjusts its velocity by performing a constrained optimization of a locally-defined objective function, which is computed at each time step over the kinematics of the particle and the relative position of neighboring particles. Our model explains how ordered motion can arise in the absence of an explicitly prescribed alignment term and simulations performed with our model exhibit a wide variety of patterns of motion, including several not possible with popular constant-speed models. Our model predicts that variations in speed and heading of particles are coupled due to costs associated with changes in relative position. We have found that a similar coupling effect may also be present in the flight of groups of gregarious bats. The Mexican Free-tailed bat (Tadarida brasiliensis) is a gregarious bat that forms large maternity colonies, containing hundreds of thousands to millions of individuals, in the southwestern United States in the summer. We have developed a protocol for calibrating cameras used in stereo videography and developed guidelines for data collection. Our field protocol can be deployed in a single afternoon, requiring only short video segments of light, portable calibration objects. These protocols have allowed us to reconstruct the three-dimensional flight trajectories of hundreds of thousands of bats in order to use their flight as a biological study system for our model.
59

What is a Swarm? A Framework for Understanding Swarms and their Applications

Zhong Thai (9185855) 31 July 2020 (has links)
As problems in the world become increasingly complex, designers in multiple disciplines have begun to propose swarms as a solution. The espoused benefits include flexibility, resilience, and potential for decentralized control, yet there lacks consensus on what a swarm is, what characteristics they possess, and what applications they are able to address. This study addresses these questions by creating a unified approach for understanding and analyzing swarms, called the Swarm Analysis Framework. The framework pursues three goals: 1) provide extensive analysis on the many characteristics and applications that define a swarm, 2) remain flexible enough to facilitate design, testing, analysis, and other problems in understanding swarms, and 3) outline swarm applications specific to aircraft and spacecraft based swarms. Afterwards, the Swarm Analysis Framework is used to guide a case study in which the application is a swarm was developed to study one of these aerospace applications. Ultimately, the Swarm Analysis Framework, along with its extensions improvements, should be able to act as a guide or roadmap in understanding how swarms behave across multiple disciplines.<br>
60

Integral Feedback Control Is at the Core of Task Allocation and Resilience of Insect Societies

Schmickl, Thomas, Karsai, Istvan 26 December 2018 (has links)
Homeostatic self-regulation is a fundamental aspect of open dissipative systems. Integral feedback has been found to be important for homeostatic control on both the cellular and molecular levels of biological organization and in engineered systems. Analyzing the task allocation mechanisms of three insect societies, we identified a model of integral control residing at colony level. We characterized a general functional core mechanism, called the “common stomach,” where a crucial shared substance for colony function self-regulates its own quantity via reallocating the colony’s workforce, which collects and uses this substance. The central component in a redundant feedback network is the saturation level of this substance in the colony. An interaction network of positive and negative feedback loops ensures the homeostatic state of this substance and the workforce involved in processing this substance. Extensive sensitivity and stability analyses of the core model revealed that the system is very resilient against perturbations and compensates for specific types of stress that real colonies face in their ecosystems. The core regulation system is highly scalable, and due to its buffer function, it can filter noise and find a new equilibrium quickly after environmental (supply) or colony-state (demand) changes. The common stomach regulation system is an example of convergent evolution among the three different societies, and we predict that similar integral control regulation mechanisms have evolved frequently within natural complex systems.

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