• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 11
  • 3
  • 1
  • 1
  • Tagged with
  • 17
  • 4
  • 3
  • 3
  • 3
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 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.
11

Uticaj pojava mehaničkih oscilacija na sigurnost funkcionisanja sklopova u sistemu prenosa snage tekstilnih mašina / The influence of mechanical oscillations on safety of funcioningof testile machines

Stefanović Slobodan 21 December 2006 (has links)
<p>Analiza sigurnosti funkcionisanja sastavnih komponenti sklopa boksa predenja i sklopa<br />za namotavanje kalemova gotovom pređom kod OE - predilice se može najpreciznije pratiti formiranjem monitoring sistema praćenja njihovog rada. Na osnovu nje vr&scaron;e se procedure preventivnog održavanja, koje se baziraju na konceptu planskog održavanja koje obuhvataju ocene stvarnog stanja rada i ispravnosti sastavnih komponenti analiziranih sklopova. Ovaj vid praćenja stanja obuhvata korelacionu povezanost pouzdanosti i nivoa mehaničkih oscilacija na sastavnim komponentama analiziranih sklopova i uzroke koje one dovode do njihovih otkaza.<br />Korelacija je izvr&scaron;ena formiranjem univerzalnog optimalnog modela rada analiziranih sklopova prema izabranim mernim mestima na osnovu uticaja mehaničkih oscilacija (vibracija). Metodologija praćenja stanja je obuhvatila nivoe amplitudnih spektra mernih veličina oscilovanja na komponentama analiziranih sklopova za izvr&scaron;ena redosledna merenja. Dobijene vrednosti su une&scaron;ene u univerzalni optimalni model za različite vremenske intervale rada<br />komponenata analiziranih sklopova, pa je na osnovu njih određena zavisnost modela&nbsp;u funkciji eksploatacionog vremena (t) , koja predstavlja određivanje frekventne sigurnosti rada sklopova. Ova zavisnost podržala je ocenu sigurnosti funkcionisanja<br />sastavnih komponenti analiziranih sklopova u slučajevima kada na njima nisu sprovođeni postupci tehnologije preventivnog održavanja i kada su ovi postupci sprovođeni.</p> / <p>The analysis of functioning of basic components of technical system is the basic type of monitoring systems and state analyzing. Based on this, there are procedures of preventive maintenance, which have the grades of real state of work and components of technical system. This work contains co-relation between levels of mechanical oscillations of components in the system and their influence on the cause of system mallfunction. Corelation is based on forming the universal optimal working model for analvzing the system on chosen measurement points based on the influence of mechanical oscillations (vibrations). The methodology of state tracking has levels of amplitude spectres of measurement values and oscillating the components of<br />analized systems for those results. The values are the input for basic universal optimal model for different time intervals of system work, and based on those values were defmite the model dependence in the time oscillations (t), which represents the dependence of frequent safety of sub - system in function of their work)).These dependence is supported in the functioning of basic components of analized system in the ča&scaron;e of their work with and without the basic maintenance.</p>
12

Development of grey-box models for simulating heating consumption in buildings : A study applying system identification methodology to a physics-based framework

Klockar, Zack January 2021 (has links)
This study models the energy used for heating in buildings by applying system identification methodology. The model development is grounded in physics to provide guidance and interpretability when evaluated. Time-series of heating demand, outdoor temperature, indoor temperature and solar irradiation are considered for the modelling purpose. Evaluation is done through simulation and relies on quantitative measures, residual analysis and visual inspection of model output. Through model development, the study seeks to extrapolate information of physical properties that drives heating demand in buildings. Seven buildings located in the same geographic area are studied. It is found that linear ARX-models can simulate heating demand with high precision but at times low accuracy. A common system model structure can be identified between buildings, indicating that physical properties shared between buildings can be identified through this methodology. A sensitivity analysis is conducted to derive the contributions from model constituents to simulation results. Two buildings were also modelled as OE-models. These models performed better than the respective ARX-models but were deemed more difficult to use for the purpose of this study. The study finds difficulties in implementing aggregated time-series of indoor temperature, which could be explored further in future studies for more detailed interpretations.
13

Modelagem Paramétrica de Cubas Eletrolíticas para Predição do Efeito Anódico. / Parametric modeling of electrolytic smelter pot for anodic effect prediction.

SILVA, Antonio José da 05 June 2009 (has links)
Submitted by Maria Aparecida (cidazen@gmail.com) on 2017-09-06T13:31:47Z No. of bitstreams: 1 Antonio_José_da_Silva2.pdf: 2564341 bytes, checksum: ff7454362aecf3bf6afd177edfd5c821 (MD5) / Made available in DSpace on 2017-09-06T13:31:47Z (GMT). No. of bitstreams: 1 Antonio_José_da_Silva2.pdf: 2564341 bytes, checksum: ff7454362aecf3bf6afd177edfd5c821 (MD5) Previous issue date: 2009-06-05 / FAPEMA / The Anode effect that occurs in electrolytic smelter pot is responsible for gases such as PFC s. These gases contribute to the greenhouse effect, and in addition jeopardizes its productive capacity. From the voltage (output) and current (input) are estimate ARX and OE models of the electrolytic smelter pot using the Systems Identification Theory, the ARX and OE models of the electrolytic smelter pot are built to represent the steady state operation and the anode effect occurrence. After the simulation are chosen the models with better adjustment to the measure exit. For the selection are used established criteria along the research, the ARX and OE models of electrolytic smelter pot, are built to represent the full state operation of the electrolytic smelter pot. Based on real data and via algebraic properties, the models generate the functions of specific transfer of each model that are validated with real data obtained in the industry, the answer in time, in the convergence frequency and speed are analyzed. From the transfer function is made the representation of the normal stage of operation of the electrolytic smelter pot, and by the properties of the estimate model is made the prediction the anode effect identifying the increase of the voltage in the validation stage. Therefore, this work introduces the investigation of ARX and OE parametric models how better represent the operation of the electrolytic smelter pot to can enable the prediction of the anode effect in the productive process of the aluminum. In this dissertation, we propose the models development in the domain of the continuous and discreet time with a study of her transitory answers and of steady state as well as your answer in frequency of your normal operation and in the phase that precedes the anode effect. / O efeito anódico que ocorre nas cubas eletrolíticas é responsável pela emissão de gases como os PFC s, gases esses, que contribuem para o efeito estufa, além de comprometer sua capacidade produtiva. A partir dos sinais de tensão (saída) e corrente (entrada) são estimados modelos ARX e OE da cuba eletrolítica utilizando a Teoria de Identificação de Sistemas. Após a simulação são escolhidos os modelos com melhor ajuste à saída medida. Para a seleção são utilizados critérios estabelecidos ao longo da pesquisa. Os modelos ARX e OE das cubas eletrolítica, são construídos para representar o pleno estado de funcionamento da cuba. Baseados em dados reais e via propriedades algébricas, os modelos geram as funções de transferência específicas de cada modelo que são validadas com dados reais obtidos na indústria, a resposta no tempo, na freqüência e velocidade de convergência são analisadas. A partir da função de transferência é feita a representação da fase normal de funcionamento da cuba eletrolítica, e pelas propriedades do modelo é feita a predição do efeito anódico identificando o aumento da tensão na fase de validação. Portanto, este trabalho apresenta a investigação de modelos paramétricos ARX e OE que melhor representam o funcionamento da cuba eletrolítica para possibilitar a predição do efeito anódico no processo produtivo do alumínio. Nesta dissertação propomos o desenvolvimento de modelos no domínio do tempo contínuo e discreto com um estudo das suas respostas transitória e de regime permanente assim como sua resposta em freqüência de seu funcionamento normal e na fase que antecede o efeito anódico.
14

Observadores de Estados para Sistemas de Medição Indireta e Controle RLQD-GA / Observers of States for Systems Indirect Measurement and Control RLQD-GA

Cerqueira, Marcio Mendes 05 February 2010 (has links)
Made available in DSpace on 2016-08-17T14:53:08Z (GMT). No. of bitstreams: 1 Marcio Mendes Cerqueira.pdf: 4042726 bytes, checksum: a65c6a7174271eecc553e3a5b0ceb33a (MD5) Previous issue date: 2010-02-05 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Motivated by the necessity of efficient algorithms, it s presented the development of a methodology for the design and analysis of state observers in open and closed loops that are dedicated to monitoring and control of dynamic systems. The development of observers are based on OE models, description in state space and Kalman filter. The models are evaluated for temperature control of a aluminum cube that is inside of a sterilizer oven. In addition to the models assessment in terms of its ability to represent behavior of plants, these models also evaluated for the design of discrete linear quadric regulator DLQR that are tuned by genetic algorithms. The monitoring models are evaluated for open and closed loops structures that are represented by algorithms in terms of difference equations, these algorithms are seen as software core for the indirect measurement systems. / Motivado pela necessidade de algoritmos eficientes, apresenta-se o desenvolvimento de uma metodologia para projeto e análise de observadores de estado em malhas aberta e fechada que são dedicados a monitoração e controle de sistemas dinâmicos. O desenvolvimento dos observadores estão fundamentados em modelos OE, descrição no espaço de estados e filtro de Kalman. Os modelos são avaliados para o controle da temperatura de um cubo de alumínio que encontra-se no interior de uma estufa. Além das avaliações dos modelos em termos de sua habilidade em representar comportamento de plantas, estes são também avaliados para o projeto do regulador linear quadrático discreto (RQLD) que são sintonizados por algoritmos genéticos. Aplicação dos modelos para monitoração é avaliada nas estruturas das malhas aberta e fechada que são representadas por algoritmos em da equação à diferença, tendo em vistas o desenvolvimento de núcleos de software para os sistemas de medição indireta.
15

El rendimiento financiero de las empresas sociales de Lima: un análisis desde su orientación empresarial y al mercado / The financial performance of social enterprises in Lima: Analyzing their business and market orientation

Aquino Porras, Angela Karolina, Hernandez Huamañahui, Kelly Esther 20 February 2019 (has links)
La presente investigación se desarrolló a partir de los diversos problemas sociales que acontecen en nuestro país, debido a que las empresas sociales cumplen un rol fundamental en grupos vulnerables; se determinó como finalidad principal de esta investigación el estudio de estas en base a variables de gestión, que según la literatura afectarían el rendimiento de estas organizaciones. De esta manera, se plantea conocer el comportamiento del rendimiento financiero de las empresas sociales en estudio y de las variables orientación al mercado y orientación empresarial; según si estas poseen una orientación empresarial y al mercado: fuertes o débiles. Asimismo, se consideró relevante definir el tipo de interacción entre las variables orientación al mercado y orientación empresarial y se planteó identificar si las variables orientación al mercado y orientación empresarial influyen en la variable rendimiento financiero en las empresas sociales. En ese sentido, se busca que las empresas sociales puedan garantizar una contribución constante a aquellos sectores desatendidos a través de la autosostenibilidad financiera. Sin embargo, los hallazgos para la muestra del presente estudio demostraron que no es posible afirmar la existencia de la relación entre el rendimiento financiero y las orientaciones empresarial y al mercado. No obstante, se determinó que para dicha muestra existen indicios de interacción entre las variables independientes orientación empresarial y al mercado. / The present research has taken place from the diverse social problems in our country, so that social enterprises fulfill a fundamental role of contribution in vulnerable groups, the main purpose of this research was to study the behavior of their financial performance based on management variables; that according to the literature would affect the financial performance of these organizations. In this way, it is intended to know the behavior of the financial performance of the social enterprises under study and the market orientation and business orientation variables. For which, it was determined if these have a business orientation and market: strong or weak. Likewise, it was considered relevant to define the type of interaction between the market orientation and business orientation variables; It was also intended to identify if the market orientation and business orientation variables influence the variable financial performance in the context of the social ecosystem. In this sense, it is expected that business companies can guarantee a constant contribution to those sectors unattended through financial self-sustainability. However, the findings for the present sample show that it is not possible to affirm the existence relationship between profitability and business and market orientation in our study sample. Likewise, it was determined that for this sample there are possible signs of interaction between the independent variables, the business orientation and market orientation. / Tesis
16

Design and fabrication of a photonic integrated circuit comprising a semi-conductor optical amplifier and a high speed photodiode (SOA-UTC) for >100 Gbit/s applications / Etude d'un récepteur pré-amplifié de type PIC (Photonic Integrated Circuit) réalisé par intégration monolithique d'un amplificateur (SOA) optique à semi-conducteur et d'une photodiode (UTC) pour les liaisons courtes distances à 100 Gbit/s et au delà

Anagnosti, Maria 13 November 2015 (has links)
Ce travail porte sur la conception, la fabrication et la caractérisation d’une photodiode très haut débit (UTC PD) et son intégration avec un préamplificateur optique à semi-conducteur (SOA) pour les liaisons optiques à courte distance à 100 Gbit/s en bandes C et O. Il porte également sur la conception d'un duplexeur (Tx / Rx) avec liaison montante en bande C et liaison descendante en bande O. L'intégration monolithique d’un SOA avec une photodiode haut débit sans filtre optique entre les deux présente des avantages majeurs parmi lesquels: - Augmentation de la distance de transmission. - Augmentation du nombre d'utilisateurs connectés. - Diminution des coûts globaux de fabrication incluant l’assemblage. La première partie de cette étude porte sur l'optimisation SOA pour un fonctionnement à forte puissance (Psat). Un faible facteur de bruit (NF) et une faible dépendance à la polarisation (PDL) sont requis pour les récepteurs préamplifiés. De plus, un fonctionnement du et opérer en régime linéaire est nécessaire pour les schémas de modulation complexes. Le SOA actuel possède un gain de 18 dB avec un facteur de bruit de 8 dB, une faible PDL (<2 dB), et une bonne puissance de saturation en entrée (-8 dBm). Grâce à l’optimisation de la structure verticale du SOA et de son couplage avec la fibre les performances attendues sont améliores : Psat >-5 dBm, NF <8 dB, PDL et gain similaire. D'autre part, les interconnexions électriques de la photodiode ont été optimisées ce qui a permis de démontrer des photodiodes avec une bande passante supérieure à 100 GHz. Les photodiodes présentent un fort coefficient de réponse (R) (0,6 A/W à 1,3 μm et 0,55 A/W à 1,55 μm) et une faible PDL <1 dB. Un fort courant de saturation de 14 mA à 100 GHz a aussi été démonté. Enfin, la caractérisation des SOA-UTC réalisés a montré simultanément une très forte responsivité (95 A/W), une faible dépendance à la polarisation PDL (<2 dB), un faible NF (8 dB) et une large bande passante à 3 dB (> 95 GHz), qui placent nos composants au meilleur niveau de l’état de l’art avec un produit gain-bande record de 6,1 THz. Les Mesures numériques à 64 Gbit/s montrent que notre récepteur atteint une sensibilité de -17 dBm pour un taux d'erreur de 10-9, et la sensibilité attendue à 100 Gbit/s est de -14 dBm / This work focuses on the design, fabrication and measurements of a uni-travelling carrier high speed photodiode (UTC PD) and its integration with a semiconductor optical preamplifier (SOA) for short reach 100 Gbit/s optical links, in O- and C- bands. This work also focuses on the design of a duplexer (Tx/Rx) with downstream in O-band and upstream in C-band. The SOA monolithic integration with a high speed PD without an optical filter in between yields major benefits among which: - Increase in the transmission distance. - Increase in the split ratio correlated to the number of connected users. - Decrease of the overall fabrication and assembling cost. The first part of this work is dedicated to optimizing the SOA for high power operation (Psat). The low noise figure (NF), and polarization dependence loss (PDL) are critical parameters for a preamplified receiver. Also complex modulation formats require linear gain regime of the SOA. The current SOA presents 18 dB gain with NF (8 dB), low PDL (<2 dB), and good input power saturation (-8 dBm). Thanks to further optimization of the SOA vertical structure and coupling with the optical fiber, the expected SOA performance is higher Psat >-5 dBm, NF <8 dB, similar PDL and gain. Secondly, the electrical interconnects of the photodiode is optimized to increase the photodiodes’ bandwidth, which allows to demonstrate photodiode with >100 GHz bandwidth. The PD presents high responsivity (R) (0,6 A/W at 1,3 μm and 0.55 A/W at 1,55 μm) and low PDL <1 dB. Also the saturation photocurrent is high (14 mA at 100 GHz). Finally, the SOA-UTC demonstrates high responsivity (95 A/W), low PDL (<2 dB), low NF (8 dB) and a wide 3 dB bandwidth (>95 GHz), which yields a record gain-bandwidth product of 6.1 THz. Large signal measurements at 64 Gbit/s show that our receiver reaches a low sensitivity of -17 dBm for a bit error rate of 10-9, and is expected to reach -14 dBm at 100 Gbit/s
17

Vztahy mezi staroseverskými adjektivními výpůjčkami a jejich staroanglickými protějšky ve střední angličtině / Relationships between Old Norse adjectival borrowings and their Old English counterparts in Middle English

Müllerová, Světlana January 2020 (has links)
CHARLES UNIVERSITY - FACULTY OF ARTS DEPARTMENT OF ENGLISH LANGUAGE AND ELT METHODOLOGY Relationships between the borrowed Old Norse adjectives in English and their Old English counterparts MA THESIS Supervisor: prof. PhDr. Jan Čermák, CSc. Author: Světlana Müllerová Abstract: The aim of this MA thesis is to examine the relationship between six word pairs, each comprising an Old Norse adjectival borrowing in Middle English and its Old English counterpart along with its Middle English reflex for further reference. The inquiry into their relationship involves an analysis of: their (i) formal aspects, (ii) syntactic properties, (iii) semantic fields and (iv) external factors possibly contributing to their obsolescence or survival, such as the restriction to certain text types or geographic localization, as suggested by the individual linguistic profiles in the Linguistic Atlas of Early Middle English and Linguistic Atlas of Late Mediaeval English. The description of individual semantic fields of the given words is based on their semantic classification within the Historical Thesaurus of English. This analysis is based on the occurrences of the individual words as taken from the dictionaries Middle English Dictionary and Dictionary of Old English, and related corpora Dictionary of Old English Corpus and...

Page generated in 0.0192 seconds