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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.
21

Condition Monitoring of Control Loops

Horch, Alexander January 2000 (has links)
<p>The main concern of this work is the development of methodsfor automatic condition monitoring of control loops withapplication to the process industry. By condition monitoringboth detection and diagnosis of malfunctioning control loops isunderstood, using normal operating data and a minimum amount ofprocess knowledge.</p><p>The use of indices for quantifying loop performance is dealtwith in the first part of the thesis. The starting point is anindex proposed by Harris (1989). This index has been modifiedin order to cover a larger range of processes. The same conceptis then used to assess the sampling rate in control loops.Other index-based monitoring methods where some amount ofprocess knowledge is available are discussed.</p><p>The evaluation of the performance indices discussed requiresknowledge of the process dead-time. Therefore a concept calledevent-triggered estimation is introduced in the second part ofthe thesis. Both automatic data selection and dead-timeestimation methods are proposed and conditions for successfulestimation are discussed.</p><p>The last part of the thesis deals with the diagnosis ofoscillations. A method to automatically diagnose staticfriction (stiction) in the actuator is presented. Furthermore,two methods are proposed which allow automatic distinction ofexternally and internally generated oscillations. All describedmethods have been implemented in a MATLAB-based graphical userinterface which is briefly described.</p>
22

Produktivita a ekonomická výkonnost u malých a středních podniků ve zpracovatelském průmyslu / Productivity and economic performance of small and medium-sized enterprises of manufacturing industry

HRUŠKOVÁ, Václava January 2018 (has links)
This theses deals with productivity and economic performance of small and medium-sized enterprises of chosen sector of manufacturing industry in Czech Republic. The main goal of this thesis is to assess the relation between labour productivity and economic performance in the selected sector of furniture manufacture. Required data are gained from database Albertina. The theses is devided into two sectors. The first part of thesis describes scientific findings about productivity and economic performance.Practical part focuses on analysis of labour productivity and economic performance of chosen companies. The last section of pratical part is devoted to proving the relations between labour productivity and economic performance represented by indicator ROA and indexes of financial health: IN99 and Reliability index. Regression and correlation analysis evaluates described relations from the static and dynamic view.
23

Análise do desempenho de sistemas de controle

Souza, Davi Leonardo de 14 September 2007 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / When the controller s performance is reduced along the time and the control efficiency is no longer satisfactory, then it is necessary to develop certain techniques for continuously monitor control systems such as it can keep track of process changes maintaining the characteristics of efficiency of the original controller design. The divergences between controlled variables and the desired setpoint can be quantified by a single number that is known as performance index. In the present work, a novel way of evaluating the control process performance is introduced and applied as a new measure of performance for a control structure. For doing that, the knowledge of the invariants of the process under feedback and factorization tools of linear local models were applied for designing a new reference model. The proposed techniques were used as a reference of what can or cannot be achieved by a particular system operating under the action of a feedback control law: minimum variance control (MVC), proportional-integral (PI), and model predictive control (MPC). Hence, the proposed performance indexes are the tools for the evaluation of the behavior of the control system during regular industrial operation, not only based upon the physical point of view, in which the reference is treated as a realizable system, but also from a theoretical point of view, in which the model factorization procedure takes place, and therefore allowing the extraction of the invariant part of a system, changing the system to its easiest controlled form description, and then serving as a reference model for the calculation of the performance index, with a low computing cost and preserving the importance of interactions and high frequency effects for balancing the reference behavior. In this work was investigated, with success, the effect of coupling, interactions and quality degradation of the control for SISO (Single-Input and Signle-Output) and MIMO (Multiple-Input and Multiple-Output) processes. The results show that the proposed technique are effective and a viable tool for process monitoring and controlled systems performance evaluation. / Quando o desempenho de um controlador se reduz ao longo do tempo e a eficiência de controle já não é mais satisfatória, tem-se que o controle em vigor ficou obsoleto devido às mudanças ocorridas no processo. Dessa forma, surge a necessidade de se desenvolver técnicas de monitoramento contínuo de sistemas de controle para que o mesmo possa acompanhar as mudanças ocorridas no processo, mantendo as características de eficiência do projeto original do controlador. As divergências entre variáveis controladas e os valores desejados (setpoint) podem ser quantificadas por um número que ´e conhecido como ´índice de desempenho. Neste trabalho, investiga-se o desempenho de sistemas de controle através de novas medidas de desempenho para estruturas de controle. As medidas propostas utilizam o conhecimento dos invariantes do processo obtidos através de ferramentas de fatoração de modelos locais lineares e da definição de um padrão de referencia `a ação possível de controle para plantas operando com controladores feedback para casos de controladores com variância mínima (MVC), proporcional-integral (PI) e controlador preditivo baseado em modelos (MPC). Desta forma, a técnica proposta neste trabalho serve como uma ferramenta para a avaliação do comportamento do sistema de controle durante a operação industrial, pois, tanto do ponto de vista físico, por se tratar de uma referencia realizável, quanto do ponto de vista teórico, que ao realizar a fatoração, as informações dos invariantes dos modelos são extraídos, fazendo com que os mesmos se tornem mais fáceis de serem controlados, então, servindo como referencia para o cálculo do ´índice de desempenho para o sistema. As técnicas propostas possuem baixo custo computacional e preservam a importância de interações e efeitos de elevadas freqüências no compromisso entre a atenuação da sensibilidade das perturbações e a velocidade de resposta da malha de controle avaliada. Investigou-se então, com sucesso, o efeito de acoplamentos, interações e degradação da qualidade do controle para processos com uma entrada e uma saída (SISO) e sistemas com múltiplas entradas e múltiplas saídas (MIMO), comprovando então a eficácia da técnica proposta como uma ferramenta viável para o monitoramento e avaliação de sistemas de controle. / Mestre em Engenharia Química
24

Caracterização e avaliação do fluxo produtivo de habitação em madeira de plantios florestais segundo indicadores de sustentabilidade: consumo de energia e resíduos gerados / not available

Juliana Cortez Barbosa 23 October 2003 (has links)
O setor da construção civil é hoje considerado não somente o maior consumidor de recursos e energia, mas também o maior gerador de resíduos nos centros urbanos. Uma reformulação no setor faz-se necessária para a melhoria dos processos de produção e prevenção dos efeitos da poluição. Estas mudanças são essenciais para que se desenvolvam tecnologias construtivas mais limpas e mais eficientes, que reduzam os impactos ao meio ambiente através de um uso mais racional dos recursos naturais (com menor consumo energético e diminuição dos resíduos gerados), minimizando o desperdício de matéria-prima já escassas. Este trabalho foi realizado a partir de dados coletados em 10 serrarias que processam madeira serrada de pinus na região administrativa de Sorocaba. Nesta região concentra-se atualmente o maior potencial madeireiro do Estado de São Paulo, 42,3% de toda a área de florestas plantadas do Estado, sendo também o maior centro produtor de pinus do Estado, com 58,5%. Esses dados foram convertidos para o cálculo do consumo energético no processamento do eucalipto. Dada a relevância do consumo de energia e a quantidade de entulhos gerados pelo setor da construção civil, o presente trabalho tem como objetivo analisar, dentro da cadeia produtiva da madeira serrada, o consumo energético e os resíduos gerados na produção de componentes construtivos utilizados em painéis de vedação para casas de madeira. Foram analisadas peças de seções comerciais utilizadas em três tipos diferentes de painéis. Dois destes sistemas pré-fabricados, executados na cidade de São Carlos - SP, possuem sistema estrutural em madeira serrada de eucalipto com paredes duplas de pinus. Um deles possui na face interna, lambri e, na externa, deck horizontal, enquanto o outro sistema construtivo possui na face interna, lambri e, na face externa, tábua mata-junta. O terceiro sistema de vedação, construído em Campos do Jordão - SP, é composto por estrutura em pórticos de madeira serrada de pinus com paredes externas de fechamento duplo de lambri de 2,2 cm de espessura. A parede interna é simples com apenas uma camada de lambri de igual espessura. O consumo de energia foi medido para cada tipologia de painel construído, calculando-se o número de operações de corte e a potência de cada equipamento envolvido. Os resíduos gerados foram obtidos a partir do cálculo da área de material particulado removido. O índice de desempenho energético foi aferido em kWh por metro quadrado de painel (energia) e em metros cúbicos por metro quadrado de painel (resíduo). Estes resultados poderão vir a ser comparados com diferentes materiais de construção utilizados em sistemas de vedação, assim como fornecer informações para análise do grau de sustentabilidade na produção de um edifício de madeira em relação ao consumo energético. / The civil construction sector today is considered not only the greatest consumer of material and energy resources in urban centres, but also a major generator of waste. The sector needs a reformulation for the improvement of production and for the prevention of pollution. It is therefore essential to consider cleaner and more efficient technological processes, i. e., to decrease environmental impacts through a more rational use of resources (with lower consumption of energy anbd less production-related waste), minimizing the squandering of scarce resources. The study reported on here was based on data collected from ten pine sawmills in the region of Sorocaba, state of São Paulo, Brazil. This region currently possesses the greatest potential for sawed wood in the state of São Paulo, 42.3% of all the forest planted in State, and is the state\'s largest pinewood producer, about 58.5%. Those datas were also aplicated to calculate the energy consumed for sawn eucalyptus pieces. Given the relevance of energy consumption and the quantity of produced rubbish by the construction sector, the purpose of this work is to analyse the consumption of energy and the produced waste in the productive cycle of boards for wooden housing, from the cutting stage, processing, and prefabrication of componentes to the assembly of wall panels. This study involved wooden boards of commercial dimensions applied in three different types of panelling in three buildings. Two of theseprefabricated systems, executed in the city of São Carlos, have a structural system made of sawn eucalyptus wood with double walls of pine. One of them is lined internally with wainscoting and externally with horizontal decking, while the other system has internal wainscotting and external match boarding. The third system, built in Campos de Jordão, is composed of a structural framework of sawed pine, with external double shutter walls of 2.2 mm match boarding and simple internal walls consisting of a single layer of 2.2 mm thick match boarding. The consumption of energy was measured for each kind of board produced, calculated from the number of cutting operations and the power of each machines involved. The produced waste was calculated by the area of removed particulate material. The energy performance index were expressed in kWh consumed per square meter of wood panel produced (enegy) and in m3 produced per square meter of wood panel produced (waste). These data will serve as the basis for a comparison with various types of construction materials used in wall systems (concrete, brick and others), and provide information for the analysis of the sustainability of wooden construction systems from the standpoint of energy consumption.
25

Řízení rizik projektu ve společnosti / Risk Management of Project in a Company

Klimeš, Marek Unknown Date (has links)
The diploma thesis deals with risk management in a newly starting project in a company, with a special attention to risks before and after beginning of the project. Based on the analysis of the company, the proposal for risk driving is introduced
26

Risk-adjusted Earned Value and Earned Duration Management models for project performance forecasting

Apostolidou, Ilektra-Georgia, Karmiris, Georgios January 2019 (has links)
Project control is essential to ensure that the investment on a project is providing the intended benefits and is valuable to the customers. Previous methods offer project performance monitoring and forecasting tools, but they lack accuracy and the associated techniques omit the project financial risk (any unplanned event that has an impact on schedule and budget); the main factor of project failure. Poor project execution, and particularly failure to control and accurately forecast the project performance, may lead to increased costs, upset customers and eventually loss of market share. These gaps have been filled in this study by the development of novel models that use statistical analysis of the previous project performance, including risk evaluation techniques. The proposed models succeeded in providing remarkably improved forecasts in three project dimensions: duration, cost and resources. The robustness of the models has been verified by testing them on real projects. The results show superiority in terms of accuracy and easy application compared to any existing method, proving that the risk inclusion provides improvement compared to previous studies. The most important features of the models are: risk-based adjustment of the forecasted values, periodic and completion forecasts, statistical processing and holistic approach. The greatest advancements have been made in the cost forecast, for which the risk adjustment inclusion is examined for the first time. The resources (man-hours) forecast is another pioneer element of the proposed models. All the above provide a complete image of the project status and paint the picture of future performance. The models results are fed in a Decision Support System, which highlights the overperforming and underperforming areas of the project. This confirms the proposition that the model results can be used to initiate restorative action. The contribution of this study to the project management field is easy-to-use and accurate models, which include the financial risk and facilitate the project manager’s decisions and actions. Anticipation of the project performance, by considering the risk, can result to significant time and cost savings, crucial for project success.
27

La Responsabilité Sociétale des Entreprises : un levier pour la durabilité écologique. Validation empirique pour la Méditerranée / The Corporate social responsibility : a lever for the ecological durability. Empirical Validation for the Mediterranean Sea

Ben Abdallah Golli, Olfa 01 December 2017 (has links)
L’objet de cette thèse est de contribuer à l’étude du rôle de l’intervention de l’État dans les pays méditerranéens, et ce dans la promotion de la démarche responsable. Ce travail doctoral fournit une revue générale de l’étude du rôle des facteurs environnementaux dans le cadre du développement qualifié durable, il évoque, entre autres, les changements intervenus au niveau de la perception de la politique RSE, dans la région méditerranéenne. Dans l’étude que nous menons sur la RSE, nous focalisons notre recherche sur les démarches responsables aussi bien volontaires que celles menées obligatoirement, suite à des contraintes institutionnelles, et les soumettons à comparaison. Ce faisant, nous nous penchons en particulier sur la manière dont le concept RSE a été fortement relié à la notion de la durabilité environnementale. La première partie de ce travail présente une revue exhaustive et critique de la littérature sur les démarches responsables. Au niveau de la deuxième partie, essentiellement factuelle, nous cadrons les fondements empiriques et institutionnels d’un modèle de la croissance verte. L’estimation et la validation sont présentées au niveau de dernier chapitre. Les résultats obtenus nous amènent à affirmer, qu’en premier lieu, la RSE affecte positivement la qualité de l’environnement. En deuxième lieu, des démarches différentes se juxtaposent pour proposer des scénarios de la performance environnementale à l’échelle de la Méditerranée. En troisième lieu, il ressort que l’intervention contraignante de l’État fait perdre à la RSE son efficacité, à quoi s’ajoute l’impact - sur la RSE - de la disparité au niveau institutionnel et la différence du niveau de développement d’un pays à l’autre. En dernier lieu, nous pensons que l’interaction entre la volonté et l’obligation de mener des actions responsables pourrait être à l’origine d’une perfection en termes de durabilité écologique au niveau des pays riverains de la Méditerranée / The purpose of this thesis is to contribute to the study of the role of State intervention in the Mediterranean countries, and this in the promotion of the responsible approach. This doctoral work provides a general review of the study of the role of environmental factors in the context of sustainable qualified development. It discusses, among other things, changes in the perception of CSR policy in the Mediterranean region. In our study on CSR, we focus our research on both voluntary and obligatory approaches, following institutional constraints, and subject them to comparison. In doing so, we focus in particular on how the CSR concept has been strongly related to the notion of environmental sustainability. The first part of this work presents an exhaustive and critical review of the literature on responsible approaches. In the second part, which is essentially factual, we frame the empirical and institutional foundations of a green growth model. Estimation and validation are presented at the last chapter level. The results highlight the relationship between CSR and governance as regards sustainable growth and sustainable environmental-friendly growth, at the macroeconomic level.The results obtained allow us to confirm that firstly, CSR plays a positive role in order to improve the quality of the environment. Secondly, various approaches overlap and tie together to propose environmental-performance scenarios throughout the Mediterranean.Thirdly, it appears that the restrictive intervention of the state weakens CRE efficiency, added to this the impact on -CSR- of the disparity at the institutional level and between countries of different development level. Finally, according to the results obtained, we believe that the interaction between the will and the duty to carry out responsible actions could in turn constitute/ lead to a perfection in terms of ecological sustainability for Mediterranean-bordering countries.
28

Development of a Novel Performance Index and a Performance Prediction Model for Metallic Drinking Water Pipelines

St. Clair, Alison Marie 23 April 2013 (has links)
Previous authors have developed many different types of water pipe condition and failure models using the various methodologies available.  Contrary, current utilities are struggling to maintain their current water infrastructure system, due to the lack of effective prediction tools at hand.  The gap between the methodologies available in academic research and the tools available to current water utilities needs to be addressed.  This paper presents a fuzzy inference prediction model used to forecast the performance rating of individual drinking water pipeline sections (node to node) in which utilities can easily apply to their drinking water infrastructure system. Prior to the development of a prediction model, a through literature and current practice review is completed detailing and summarizing all the available mathematical models.  Following, an infrastructure overview is presented detailing the various pipe materials, lifecycle and failure modes and mechanisms.  A data structure is also detailed which lists all parameters that affect the condition and/or performance of a pipeline.  All of these tools are successfully used to develop a fuzzy inference performance model. The fuzzy inference performance model is considered novel in that it considers close to 30 pipe parameters.  Moreover, the performance model is applied using the Western Virginia Water Authority (WVWA) and the Washington Suburban Sanitary Commission (WSSC) databases to evaluate and verify the predicting results.  Lab testing of several pipe samples is also used to evaluate the model.  The testing consists of a ring bearing test which is used to calculate the rupture modulus of the pipe.  Comparing the original vs. the current rupture modulus can determine the remaining strength of the pipe.  The remaining strength can then be used to assess the performance results predicted by the fuzzy inference model. Further a framework is set forth which utilizes the model's predicted performance ratings to develop deterioration curves which can be used as a tool to forecast and plan future inspection, repair, rehabilitation and replacement of water pipelines.  The deterioration model is made up of a Markov chain approach coupled with a non-optimization technique. / Ph. D.
29

Användande av myocardial performance index vid bedömning av vänster och höger kammares systoliska och diastoliska funktion / Assessment of systolic and diastolic function in both ventricles with myocardial performance index

Lundqvist, Michelle January 2023 (has links)
Vid en ekokardiografisk undersökning läggs fokus främst på klaffunktion, hjärtrumsstorlek och vänstersidans systoliska funktion. Vänstersidans diastoliska funktion har dock börjat få större betydelse, men upplevs ofta vara svårbedömd. Höger kammare har en komplex anatomi med ett trabekulerat myokardie och är otillgängligt placerad i bröstkorgen, vilket gör den svårare att bedöma än vänster kammare. 1995 publicerades ett index för bedömning av hjärtats kombinerade systoliska och diastoliska funktion, myocardial performance index (MPI). Syftet med studien var att undersöka om MPI kan vara en användbar och kompletterande metod vid bedömning av systolisk och diastolisk funktion i höger respektive vänster kammare. I den aktuella studien ingick 33 personer i åldrarna 21–80. MPI beräknades med pulsad vävnadsdoppler under en hjärtcykel. MPI jämfördes mot traditionella ekokardiografiska mätmetoder som speglar systolisk och diastolisk funktion för vänster respektive höger kammare. Normalfördelnings-, korrelations- och överrensstämmelseanalyser utfördes. För vänstersidig kammarfunktion sågs en signifikant korrelation mellan MPI och MAPSE. Ingen eller dålig överensstämmelse sågs mellan MPI och samtliga traditionella mätmetoder för systolisk funktion. För högersidig kammarfunktion sågs en starkt signifikant korrelation mellan MPI och FAC samt TAPSE. Mindre god överensstämmelse sågs mellan högersidans MPI och FAC samt TAPSE. För MPI och E/e’ sågs ingen signifikant korrelation hos vare sig vänster eller höger kammare och en sämre överensstämmelse än om klassificeringen hade gjorts rent slumpmässigt. Användbarheten av MPI för bedömning av vänster kammarfunktion anses, baserat på aktuell studie, vara låg. MPI kan vara användbart vid bedömning av höger kammares systoliska funktion, men inte avseende diastolisk funktion.
30

The impact of Chinese airport infrastructure on airline pollutant emissions: A hybrid stochastic-neural network approach based on utility functions

Cui, Q., Antunes, J., Wanke, P., Tan, Yong, Roubaud, D., Jabbour, C.J.C. 18 January 2024 (has links)
Yes / With China being the world’s largest emitter of greenhouse gases and its aviation sector burgeoning, the environmental performance of Chinese airlines has global significance. Amidst rising demands for eco-friendly practices from both customers and regulators, the interplay between airport infrastructure and environmental performance becomes pivotal. This research offers an innovative methodology to gauge the environmental performance of Chinese airlines, emphasizing the distance traveled between airports using weighted additive utility functions. Leveraging neural networks, the study investigates the impact of various airport infrastructural characteristics on environmental performance. Noteworthy findings indicate that ground control measures, automatic information services at origin airports, surface concrete on runways at both ends, and a centerline lighting system in destination airports positively influence environmental performance. In contrast, longer and wider runways at origin airports, increased distances to control towers, and asphalt runways at destination airports adversely affect it. These insights not only underscore the importance of strategic infrastructure enhancements for reducing carbon footprints but also hold profound policy implications. As global climate change remains at the forefront, fostering sustainable airport infrastructure in China can significantly contribute to worldwide mitigation efforts. / The full-text of this article will be released for public view at the end of the publisher embargo on 18 Jan 2025.

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