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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.
141

Identificação de funções de transferência utilizando como entrada um degrau /

Silva, Dárcio dos Santos. January 2008 (has links)
Resumo: O objetivo do trabalho consiste em estudar e implementar um método de identificação de modelos de funções de transferência que utiliza como entrada de teste um degrau e que foi proposto inicialmente em Kosaka (2005) e compreende duas fases: obtenção de dados referentes à saída do sistema após a aplicação da entrada degrau e a composição de um sistema matricial formado por uma matriz de Toeplitz a partir desses dados. Na solução deste sistema matricial, estima-se os parâmetros da função de transferência do sistema. Neste estudo é proposta uma generalização do método de identificação, descrito em Kosaka, para funções de transferências instáveis. Esse novo método tem como base a multiplicação, no domínio do tempo, da saída da planta y(t) por uma função exponencial do tipo e-at, sendo a um número real positivo. A constante "a" deve ser suficientemente grande, de modo que y(t)e-at ->0 quando t ->infinito. Com esse procedimento o método identifica uma função de transferência estável (G(s+a)) e então é identificada a função de transferência da planta (G(s)). Os resultados da avaliação mostram que o método generalizado e proposto para funções de transferência instáveis também pode ser aplicado em funções de transferência estáveis. O método generalizado fornece melhores resultados quando é comparada a resposta ao degrau da função de transferência estimada pelo método generalizado com a resposta ao degrau do método proposto originalmente por Kosaka em relação à resposta ao degrau da função de transferência da planta com ruído branco na saída. / Abstract: The objective of this work is to study and implement a method of identifying models of transfer functions which uses as input one step and that was initially proposed in Kosaka (2005).This method comprises two phases: obtaining data relating to the output of the system after application of the step and the composition of a system matrix composed of by a Toeplitz matrix from these data. With the solution of this matrix system, it is estimated the parameters of the transfer function of the system. In this study is proposed a generalization of the identification method, described in Kosaka, for unstable transfer functions. This new method is based on the multiplication in time domain of the plant's output y (t) by an exponential function of the type and e- at,, where a is a positive real number. The constant "a" must be large enough so that y (t)e- at ->0 when t -> infinite. With this procedure the method identifies a stable transfer function (G (s + a)) and then is identified the transfer function of the plant (G (s)). The results of the evaluation showed that the method widespread and proposed for unstable transfer functions can also be applied to stable transfer functions. The generalized method showed better results when compared with the step response of the transfer functions estimated by the method with the step response of the transfer function estimed by the method originally proposed by Kosaka (2005), regarding the step response of the transfer function of the plant with white noise in the output. / Orientador: Francisco Villarreal Alvarado / Coorientador: Marcelo Carvalho Minhoto Teixeira / Banca: Edvaldo Assunção / Banca: Márcio Roberto Covacic / Mestre
142

Strategie podniku

BARTUŠKOVÁ, Martina January 2009 (has links)
The aim of this diploma thesis is the development of the {\clq}qA`` company, focused on the sales of lighting appliances. The analytic period has covered the years 2005-2007. For the investigation were used SWOT and PEST analyses and in addition the financial analysis. The synthetic part of the thesis contains the proposal of change of the strategy for the years 2008-2010.
143

Modelo de planejamento agregado multiobjetivo

Teixeira de Almeida Filho, Adiel January 2006 (has links)
Made available in DSpace on 2014-06-12T17:42:20Z (GMT). No. of bitstreams: 2 arquivo7439_1.pdf: 870168 bytes, checksum: aea24203766388e11d6885b2b79b16f2 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2006 / Universidade Federal de Pernambuco / A atividade de planejamento agregado consiste numa etapa intermediária do planejamento da produção, que busca uma estratégia de atendimento da demanda que direcione as quantidades de itens a serem produzidos em cada alternativa de produção, abrangendo todos os períodos do horizonte de planejamento, os níveis de estoque ao longo do horizonte de planejamento e as variações na força de trabalho para que a demanda prevista seja atendida. Buscando o alinhamento da atividade de planejamento agregado com a estratégia de produção definida, este trabalho apresenta dois modelos de apoio multicritério a decisão para o problema de planejamento agregado, ambos baseados no mesmo princípio, o de estender as prioridades da estratégia de produção para as decisões a serem tomadas no contexto do planejamento agregado da produção. Dessa maneira, o gerente pode fazer o planejamento dos recursos a serem utilizados para atender à demanda priorizando os objetivos de desempenho que melhor refletem os fatores competitivos do negócio. Os modelos propostos neste trabalho buscam fazer com que um problema típico do contexto de planejamento da produção permita que a função produção possa atuar como implementadora da estratégia de produção adotada. A cada estratégia de atendimento da demanda será associado um custo. Portanto, o modelo aqui proposto busca encontrar uma estratégia de atendimento da demanda (obtida através do Planejamento Agregado) que esteja alinhada com as estratégias de produção definidas, respeitando a prioridade e as relações estabelecidas entre os objetivos de desempenho
144

Ruminal characteristics and feedlot performance of steers during accelerated step-up to high-concentrate diets using Megasphaera elsdenii (Lactipro advance).

Ellerman, Tara Jo January 1900 (has links)
Master of Science / Department of Animal Sciences and Industry / James S. Drouillard / Ruminal characteristics and feedlot performance were measured for steers adapted to a high-grain diet using a traditional 22-d step-up program (Control) and for steers adapted over 10 d with the aid of M. elsdenii NCIMB 41125 fresh culture administered as an oral gavage (Fresh), an oral gavage of rehydrated lyophilized culture (Rehyd), or Rehyd combined with lyophilized culture powder administered daily as a ration top-dress (Rehyd+Daily). Yearling steers (n = 435; initial BW = 408 ± 5 kg) were blocked by weight and randomly allocated to 64 concrete surfaced pens with 7 steers/pen and 16 pens/treatment. Step-up diets contained 40, 30, and 20% corn silage, and were followed by a finishing diet containing 10% corn silage and 90% concentrate. Ruminal fluid was obtained from a subset of steers by rumenocentesis 26 h after their first feeding, and inoculated into culture tubes containing lactate medium to determine differences in capacity for lactate metabolism over 24 h. A radiofrequency pH bolus was placed in the reticulorumen of 32 steers, that measured ruminal pH every 10 min for 124 d. Steers were fed once daily ad libitum for 156 d, then weighed, and transported 450 km to a commercial abattoir for harvest. HCW and incidence of liver abscesses were determined at harvest and carcass traits were evaluated after 36 h of refrigeration. No differences were detected for feedlot performance (P > 0.20), liver abscesses (P = 0.45), or carcass traits (P > 0.20). Capacity for lactate utilization was increased with all forms of M. elsdenii, as evidenced by increases in optical density (absorbance) of M. elsdenii cultures, disappearance of lactate, and increase in butyrate production (P < 0.01). Steers on Rehyd and Rehyd+Daily treatments spent less time between pH thresholds of 5.6 > pH > 5.2 (P < 0.01); 5.2 > pH > 5.0 (P < 0.01); and pH < 5.0 (P < 0.01) than Controls throughout the finishing period. In conclusion, steers dosed with M. elsdenii can be stepped up to finishing diets in 10 d with no adverse effects on performance. Ruminal fluid containing fresh cultures or freeze-dried and rehydrated cultures of M. elsdenii NCIMB 41125 were equally effective in metabolizing lactic acid. Lyophilized M. elsdenii resulted in less time below important pH thresholds, but no further benefit of daily administration was realized in this experiment.
145

Understanding Electrochemical CO2 Reduction using Polycrystalline Au Electrode in WiS Electrolyte

Zhang, Xizi January 2018 (has links)
Thesis advisor: Dunwei Wang / Electrochemical CO2 reduction reaction (CRR) provides a solution to both the increasing global demand of energy by forming valuable chemical products for fuel production, and global warming by reducing the amount of CO2 in the environment. To efficiently reduce CO2, we sought to understand the reaction mechanism using a polycrystalline Au electrode and the super concentrated LiTFSI solution (WiS) as the electrolyte. By varying both the electrolytic potential and the concentration of WiS, we investigated the factors determining product selectivity and found that reaction kinetics and mass transport together direct the selectivity towards CO. We probed the rate limiting step (RLS) of CO2 reduction by observing the variation of product distribution with water availability in solution, and discovered that the RLS was likely to involve only a single electron transfer to form COO*–. Lastly, we proposed that in WiS, H2O were the dominant proton sources for both CO2 reduction and H2 evolution reactions. In 21m WiS, the competing hydrogen evolution reaction was kinetically inhibited, so CO production was favored with a selectivity of 90% at a potential as early as -0.4V vs RHE. This study demonstrated the great potential of WiS as a platform for studying multi-proton, multi-electron transfer reactions. / Thesis (BS) — Boston College, 2018. / Submitted to: Boston College. College of Arts and Sciences. / Discipline: Scholar of the College. / Discipline: Chemistry.
146

Řízený zdroj napětí a proudu připojitelný přes USB / USB controlled voltage and current source

Pytela, Ondřej January 2015 (has links)
This diploma thesis is focused on complete construction of lab source which is controlled and powered by USB in personal computer. Different types of possible solutions are mentioned and finally one of them has been picked up as a best choice, which is developed in the rest of this thesis. Besides hardware construction there is also shown creation of main program for PIC18F14K50 microcontroller and main application that provides controlling of USB source via personal computer.
147

Rehabilitate : a sub-acute facility in collaboration with Louis Pasteur private hospital in the Pretoria CBD

Beckenstrater, Andrea Frances 01 December 2010 (has links)
This dissertation investigates the need for a change in popular perception of what an institutional building should and could look and feel like. This is achieved through the exploration of ways to create a therapeutic environment that houses a sub-acute facility which provides operational after care for patients discharged from Louis Pasteur Private Hospital in the Pretoria CBD. As well as providing for certain functional requirements, the architectural exploration aims to enrich and encourage the healing process of patients within the city with a rich mixture of stimulating and therapeutic experiences and qualities. Through the exploration and incorporation of various theories, these aims are set as an end goal not only throughout the design process, but are also used to guide the technical development and solutions that are used within the finalization of the facility. With a constant concept of creating a space for healing within the city of Pretoria, a Centre for Healing is created which holds these ideals at the core of its existence. / Dissertation (MArch(Prof))--University of Pretoria, 2010. / Architecture / unrestricted
148

A Study of the Effects of Fatigue, as Induced by the Harvard Step Test, on Kinesthetic Perception

Bryant, James C. 05 1900 (has links)
The purpose of the study was to ascertain the effects of induced fatigue on performance of the balance, lengthwise test, the leg raise test, the vertical space te4st, and the separate feet test.
149

Three-dimensional fluid flow structures and heat transfer characteristics of a backward-facing step flow in a rectangular duct / ダクト内バックステップ流れの三次元流動と熱伝達特性 / ダクトナイ バック ステップ ナガレ ノ サンジゲン リュウドウ ト ネツデンタツ トクセイ

邹 帅, Shuai Zou 22 March 2021 (has links)
Flow with separation and reattachment has been encountered in many thermo-fluidic devices. Although it causes energy loss due to pressure drops, it is sometimes intentionally used for heat transfer enhancement. To improve the performance of heat exchangers, understanding the details of such complicated flow and thermal structures is very important. Therefore, attention was paid in this study to a representative typical simple model that can generate separating and reattaching flow called backward-facing step (BFS) flow, the fundamental flow and thermal characteristics of a 3-D BFS flow have been investigated experimentally and a flow modification was also made by numerical simulation aimed to promote the heat transfer enhancement. / 博士(工学) / Doctor of Philosophy in Engineering / 同志社大学 / Doshisha University
150

Orogenesis and landscape evolution above the subduction-transform transition at the southeast Caribbean plate corner, Trinidad and Tobago

Arkle, Jeanette C. January 2019 (has links)
No description available.

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