A fundamental problem in ecology is determining what factors affect the distribution of organisms across a landscape. Landscapes are by their nature heterogeneous and different habitat types confer different fitness benefits and costs to organisms that inhabit them. Ecologists are now aware of the importance of examining multiple spatial scales when designing studies quantifying animal resource selection. Scale of analysis has been shown to be important, since ecological pressures relating to the establishment of a home range differ from those relating to the use of resources within the home range. Most studies that examine multiple spatial scales examine the effect of modifying extent. Here, I examine the role of grain, an underappreciated component of scale, on our interpretation of habitat selection patterns and functional response. The goal of this thesis was to examine how grain size affects the interpretation of animal resource selection and functional response across multiple habitats. The perceptual range of an individual is known to change with habitat, therefore I hypothesized that resource selection and functional response would be both grain- and habitat-dependent, and that resource selection functions computed using different grains for different resources would be more predictive than models computed using only a single grain. I used GPS-collared white-tailed deer (Odocoileus virginianus) to quantify resource selection functions at various grains and used generalized linear mixed effects modelling and multi-model inference techniques to examine how resource selection patterns changed with spatial scale across habitat types. I used selection ratios to examine functional response across grains. Model coefficients changed with grain and the strength of selection varied by habitat type. Multi-grain resource selection functions had lower AIC values and better cross-validation scores than single grain models. Functional response varied with scale and habitat type, displaying a unique relationship for each habitat. My results suggest that spatial memory and habitat-dependent perceptual range play an important role in resource selection. I conclude that the examination of multiple grains in the study of animal habitat selection and functional response represents a step forward in our ability to understand what drives the distribution and abundance of organisms.

Made available in DSpace on 2016-06-02T19:50:21Z (GMT). No. of bitstreams: 1 5362.pdf: 3103757 bytes, checksum: c0986f222ab0a46277298663c0ba7619 (MD5) Previous issue date: 2013-06-18 / This study approach the Critical Chain Method. This method is the Theory of Constraints applied to project management. The main contribution of this thesis is to propose a method for determining buffer size. Some literature reviews were performed on research methodology, production systems, project management, Critical Chain and Fuzzy Logic. A case study in a multiple project environment in a company that works with engineering to orders in the segment of capital goods was done. At the literature for determining buffer size, were identified in addition to the original method "Cut and Paste Method" proposed by Goldratt, four other methods: "Root Square Error Method (RSEM)", "Adaptive Procedure with Density (APD)," Adaptive Procedure with Resource Tightness (APRT) "and" Improved Root Square Error Method (IRSEM)". In the literature considered in this work, there was no application of any of the Critical Chain method in cases of multiple projects, with these four methods for determining buffer size. For the proposal of a new method for determining buffer size, elaborated in this thesis, we considered five variables that influence the outcome of the contracts and thus integrate the formulation. They are: contractual penalty, profit margin, customer importance, project complexity and resource constraints. Fuzzy logic is used to establish an adjustment factor to determining the buffer size. All these methods were simulated in the environment of multiple projects studied and some indicators were compared. In general, the proposed of buffer size using Fuzzy Logic allows the use of a greater number of project specific characteristics to determining the buffer size and the results of applications were goods when compared with other buffer size methods considered in this literature. / Este estudo tem como foco o método de gerenciamento de projetos originado da Teoria das Restrições chamado de Corrente Crítica. A principal contribuição desta tese está na proposta de um método para cálculo de pulmão de tempo. Para isso, foram realizadas algumas revisões bibliográficas sobre metodologia de pesquisa, sistemas de produção, gerenciamento de projetos, Corrente Crítica e Lógica Fuzzy. Foi realizado também um estudo de caso em um ambiente de múltiplos projetos em uma empresa que trabalha com pedidos sob encomenda no segmento de Bens de Capital. Na literatura para cálculo de pulmão de tempo, foram identificados, além do método original Cortar e Colar proposto por Goldratt, outros quatro métodos: Método da Raiz Quadrada do Erro , Procedimento Adaptativo com Densidade , Procedimento Adaptativo com Escassez de Recurso e Método Melhorado da Raiz Quadrada do Erro . Na bibliografia considerada neste trabalho, não se observou nenhuma aplicação desses quatro métodos para cálculo de pulmão de tempo em ambientes de múltiplos projetos. Para a proposta de um novo método para cálculo de pulmão de tempo, foram consideradas cinco variáveis que influenciam no resultado dos contratos e, dessa forma, participaram dos cálculos: multa contratual, margem de lucro, importância do cliente, complexidade do projeto e escassez de recurso. A Lógica Fuzzy foi utilizada para estabelecer um fator de ajuste do pulmão de tempo. Todos esses métodos foram simulados no ambiente de múltiplos projetos estudado e alguns indicadores foram comparados. Em geral, a aplicação da proposta para cálculo de pulmão de tempo utilizando a Lógica Fuzzy, além de permitir a utilização de um número maior de características específicas do projeto no dimensionamento dos pulmões de tempo, apresentou bons resultados em comparação com os demais métodos considerados neste trabalho.

Detta arbete har gjorts åt Scania som är ett av de ledande företagen inom lastbilstillverkning. Arbetet har utförts på plats I Södertälje på Scanias cylinderhuvudstillverkning. Området som arbetet behandlar är relativ nytt och därför upptäcks en del nya problem. Ett av dessa problem är att en befintlig 7 bitars buffert mellan två maskiner, OP70 och OP80, antingen står full eller tom, vilket leder till produktionsbortfall. Dessutom har OP80 många stopp vilket leder till att bufferten snabbt fylls upp och OP70 inte kan fortsätta arbeta. Därför ville Scania undersöka om en förändring på buffertstorlek skulle kunna lösa detta problem. För att kunna undersöka huruvida en större buffert skulle lösa problemet användes simulering som verktyg. I simuleringsprogrammet ExtendSim 10 byggdes två simuleringar upp. Den ena simuleringen som kallas “nuläge” är baserad på hur det såg ut då arbetet startades. Den andra kallas “målbild” och är uppbyggd med de cykeltider och stoppfrekvenser som Scania önskar att dessa maskiner har I framtiden. Under arbetets gång började man använda nya verktyg I OP80 maskinerna och det beslutades att dessa nya verktyg används i simuleringen av målbilden men inte I simuleringen av nuläget. När ett stort antal olika buffertstorlekar hade simulerats kunde grafer ställas upp som visar hur många bitar man får ut vid varje buffertstorlek samt hur stor ökning det motsvarar jämfört med den befintliga bufferten med 7 platser. Genom detta kunde även den optimala buffertstorleken för de två simuleringarna fastställas. Utifrån resultaten diskuteras tre olika handlingsalternativ, fördelar och nackdelar med dessa handlingsalternativ samt vilket av handlingsalternativen som de som utfört arbetet rekommenderar. / This project has been done for Scania, which is one of the leading companies in truck manufacturing. The work has been carried out on site in Södertälje at Scania’s cylinder head manufacturing. The production line the project has been carried out on is relatively new and has had a few problems during its start up. One of these problems is a buffer located between the machines OP70 and OP80 that, most of the time, is either full or empty. This leads to loss of production. That is why Scania wants to investigate whether a change in buffer size can solve this problem. To help with investigating whether a larger buffer would solve the problem simulation was used. In the simulation program ExtendSim 10 two simulation models were built. One model was named “nuläge” and is a reflection of how the production line looked at the start of the project. The other was named “målbild” and uses the cycle times and shut down frequencies Scania wishes to have in the future. During the course of the project Scania started using new tools in the OP80 machines and it was decided to use these new tools in the målbild simulation but not in the nuläge simulation. When all relevant buffer sizes had been simulated, graphs showing how many manufactured pieces you would get at different buffer sizes could be plotted. Graphs showing the percentage of which production was increased, compared to the existing buffer with 7 places, was also created in a similar way. Through these graphs the optimal buffer size for both simulations could be established. From these results three courses of action were discussed and compared by their pros and cons. Lastly a recommended course of action is chosen.

Content of master’s thesis is description field of Sliding window and it’s expansion algorithms, witch are Slow start, Congestion avoidance, Fast Retransmit and Fast Recovery algorithm. Thereinafter is described creation of model in Opnet Modeler’s simulation area. In this simulation area was analyzed reactions of average transfer speed onto variance of data size, lost ratio, latency in short and long time slot and variance of receiver’s buffer size. In last section of this document is method design witch makes it possible of transfer speed control through the use of receiver’s buffer size dynamic setting.