Dissertations / Theses on the topic 'Transmission problem'
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Ali, Habib K. "Mathematical modelling of the optimal power dispatch problem." Thesis, University of Strathclyde, 1990. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=21285.
Full textSmith, William Corbett. "Production costing with transmission constraints." Ohio : Ohio University, 1989. http://www.ohiolink.edu/etd/view.cgi?ohiou1182517746.
Full textPEREIRA, FELIPE ERNESTO LAMM. "TRANSMISSION CONGESTION ANALYSIS APPLIED ON VOLTAGE SECURITY REINFORCEMENT PROBLEM." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2003. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=3953@1.
Full textApós a incidência de inúmeros colapsos ocorridos nos sistemas de transmissão de energia devido ao uso extremo das linhas de transmissão, a estabilidade, ou mais adequadamente, a segurança de tensão tornou-se um assunto importante ao longo dos últimos anos. Este trabalho foi desenvolvido com o intuito de complementar um método de reforço das condições de estabilidade de tensão. O método consta de ações de controle para diminuir o fluxo de potência ativa no ramo crítico do caminho de transmissão mais carregado associado a uma barra crítica, conceitos estes apresentados nesta dissertação. Para o propósito citado, e considerando que o problema de estabilidade de tensão causa restrições nos fluxos de potência na rede de transmissão, são estudados métodos que analisam o congestionamento dessas redes. Se destacam algoritmos que, a partir dos fluxos de potência ativa e reativa que deixam um gerador, ou que chegam a uma carga, determinam a distribuição nos ramos de um sistema de transmissão, e o algoritmo que avalia os impactos no sistema de transmissão devido a uma determinada transação, entre barras geradoras e/ou de cargas. São mostrados exemplos numéricos que ilustram a possibilidade ou não da adequação destes métodos para o problema do reforço das condições de segurança de tensão.
After a number of collapses due to the extreme use of the transmission lines, the voltage stability, or voltage security, became an important issue. This work was developed in order to contribute to a voltage security reinforcement method. The method calculates control actions to decrease the power flowing through the critical branch of the most loaded transmission path associated with the critical bus (concepts present in this dissertation). For this propose, and considering that the power flow in a transmission network may be restricted by voltage stability limits, transmission congestion analysis methods were study. Two of them deal with the contribution of real and reactive outflows of individual generator buses, and real and reactive inflows of individual load buses, in all network branches. Another method assess the impact of a given power transaction on the network. Numerical examples are presented to illustrate whether it is the possible or not to employ the studied methods in the voltage security reinforcement problem.
Wasyk, Rebecca Dawn. "Numerical Solution of a Transmission Problem with Prefractal Interface." Digital WPI, 2007. https://digitalcommons.wpi.edu/etd-dissertations/407.
Full textPeabody, Alan Bowe. "Applying shock damping to the problem of transmission line cascades." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=84308.
Full textWhile not all structural failures result in cascades, longitudinal cascades begin with a failure in the structural system that maintains tension in the overhead wires. These failures are represented most simply by a broken wire. Broken wires cause dynamic loads on the towers much higher than the intact wire tensions.
This research tests the hypothesis that adding supplemental springs and mechanical dampers to electric transmission towers can help control the dynamic forces on towers that lead to cascades. Two new methods of incorporating springs and dampers into towers were invented: the "post spring-damper" and the "rotating crossarm spring-damper." A case study modeling a typical 230 kV line using the finite element dynamics program ADINA (ADINA 2003) was used to test these two new methods.
Both the post spring-damper and the rotating crossarm spring-damper proved to be effective. They substantially reduce the peak dynamic loads while dissipating a large fraction of the total energy released by broken wires.
Cossonnière, Anne. "Valeurs propres de transmission et leur utilisation dans l'identification d'inclusions à partir de mesures électromagnétiques." Thesis, Toulouse, INSA, 2011. http://www.theses.fr/2011ISAT0011/document.
Full textThe theory of inverse scattering for acoustic or electromagnetic waves is an active area of research with significant developments in the past few years. The Linear Sampling Method (LSM) is a method that allows the reconstruction of the shape of an object from its acoustic or electromagnetic response with a few a priori knowledge on the physical properties of the scatterer. However, this method fails for resonance frequencies called transmission eigenvalues in the case of penetrable objects. These transmission eigenvalues are the eigenvalues of a new type of problem called the interior transmission problem. Their main feature is that not only they can give information on the physical properties of the scatterer but they can also be computed from far field measurements. In this thesis, we prove the existence and the discreteness of the set of transmission eigenvalues for two new configurations corresponding to the cases of a scatterer containing a cavity or a perfect conductor. A new approach using surface integral equations is also developed to compute numerically transmission eigenvalues for general geometries
Escobar, Vargas Laura Mónica. "Specialized models for the long-term transmission network expansion planning problem /." Ilha Solteira, 2018. http://hdl.handle.net/11449/180548.
Full textResumo: A análise de sistemas altamente complexos quando e analizado o problema de planejamento de expansão de redes de transmissão de longo prazo, é o foco principal deste trabalho. Os modelos e metodos propostos são aplicados ao problema de planejamento estático tradicional, que é um problema de otimização matemática classificado como NP-completo, não-linear inteiro misto. O qual envolve no investimento, variáveis operacionais contínuas e variáveis inteiras. O comportamento normal de cada sistema pode conter informação essencial para a criação de novos métodos, como os planos de corte baseados em cortes de diferença de ângulos para problemas de grande escala, o que é a base é o ponto de partida deste trabalho, derivando em desigualdades válidas é ciclos críticos. Os cortes angulares básicos reduzem o espaço de busca do problema e o tempo total de cálculo deste problema, enquanto ao método de inequações válidas que pode ser usado para fornecer limites inferiores sólidos no investimento ótimo do planejamento de transmissão, já que a diferença entre o modelo DC (modelo exato) e o modelo de transporte (modelo mais relaxado) são as restrições angulares. Os ciclos críticos têm sido desenvolvidos para melhoraralguns dos modelos tradicionais do problemas de planejamento da expansão da rede de transmissão de longo prazo. A razão por trás disso é a ausência da segunda lei de Kirchhoff, que completa a representação do sistema, mas aumenta a complexidade. Para resolver os problemas resultantes... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The analysis of highly complex systems when solving the long-term transmission network expansion planning problem is the main focus of this work. The proposed improved models and methodology are applied to the traditionalstatic planning problem, which is a mathematical optimization problem classified as NP-complete and mixed-integer nonlinear problem. It involves continuousoperating variables and integer investment variables. The normal behavior of each system can be shown essential information to the creation of new methods, as the cutting-planes based in bus-angle difference cuts for large-scale problems which were the starting point of this work, deriving in valid inequalities and critic cycles. The angular cuts aim to reduce the search space of the problem and the total computation time of this NP-hard problem as for the valid inequalities methodthat can be used to provide strong lower bounds on the optimal investment of the transmissionplanning, since the difference between the DC model (exact model) and the transport model (more relaxed model) are the angular constraints. Critic cycles has been develop in order to improve some of the traditional long-term transmission network expansion planning problem models. The reason behind it is the absence of second Kirchhoff’s law which completes the representationof the system, but increase the complexity. In order to solve the resulting problems, this work uses the modeling language AMPL with the solver CPLEX. In test systems w... (Complete abstract click electronic access below)
Doutor
Al-awaji, Saleh Hussein. "Investigation and comparison of solution methods of the unit commitment problem for thermal units." Thesis, University of Strathclyde, 1990. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=21293.
Full textRoberts, T. Dale (Terrance Dale) Carleton University Dissertation Computer Science. "Learning automata solutions to the capacity assignment problem." Ottawa, 1997.
Find full textTomiyama, Elias Kento 1981. "Estudo do aspecto locacional da alocação de custos da transmissão = Study of the locational aspect in the transmission cost allocation problem." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/262018.
Full textDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação
Made available in DSpace on 2018-08-21T03:54:49Z (GMT). No. of bitstreams: 1 Tomiyama_EliasKento_M.pdf: 3080864 bytes, checksum: 7293fe7b3271c5c27e9b967c48a4e245 (MD5) Previous issue date: 2012
Resumo: Esta dissertação de mestrado apresenta quatro metodologias de alocação de custos da transmissão: Pro rata (PR), Divisão Proporcional (PS), Zbus-médio (Zbus_AVG) e Nodal. Enquanto a primeira desconsidera o aspecto locacional e aloca os custos baseado apenas na quantidade de potência produzida pelos geradores e consumida pelas cargas, as últimas três levam em conta este aspecto, ou seja, as tarifas pagas por geradores e cargas dependem do seu ponto de conexão na rede elétrica. Através de simulações computacionais são levantadas várias situações de operação no sentido de avaliar a influência e as possíveis implicações de ordem regulatória, política, econômica e social de um país provocadas pela inclusão do aspecto locacional na definição das tarifas de uso do sistema de transmissão. Por fim, mostra-se a possibilidade de se considerar as tarifas pagas pelos agentes do sistema como um critério de decisão a mais no problema do planejamento da expansão da transmissão
Abstract: This dissertation describes four transmission cost allocation methodologies: Pro rata (PR), Proportional sharing (PS), Zbus-average (Zbus_AVG) and Nodal. While the first one disregards the locational aspect and allocates costs based only on the amount of power delivered by generators and consumed by loads, the last three ones take this aspect into account, i.e. charges are dependent on where generators and demands are connected in the network. Several computer simulations were made in order to assess the influence of the locational aspect into transmission pricing scheme and the results were used for a critical analysis, including political, regulatory, economic and social aspects. Finally, we discuss the possibility of using the fees paid by transmission system agents as an additional criterion for the Transmission Expansion Planning problem
Mestrado
Energia Eletrica
Mestre em Engenharia Elétrica
Wunder, Gerhard. "A theoretical framework for the peak to average power control problem in OFDM transmission." [S.l.] : [s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=970360150.
Full textMacKay, Cameron. "An optimisation approach to the frequency-domain inverse problem for a nonuniform transmission line." Thesis, University of Strathclyde, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.410242.
Full textMitchell-Colgan, Elliott. "Modeling Considerations for the Long-Term Generation and Transmission Expansion Power System Planning Problem." Thesis, Virginia Tech, 2015. http://hdl.handle.net/10919/78068.
Full textMaster of Science
Axelsson, Andreas, and kax74@yahoo se. "Transmission problems for Dirac's and Maxwell's equations with Lipschitz interfaces." The Australian National University. School of Mathematical Sciences, 2002. http://thesis.anu.edu.au./public/adt-ANU20050106.093019.
Full textShi, Qiang. "Sharp estimates of the transmission boundary value problem for dirac operators on non-smooth domains." Diss., Columbia, Mo. : University of Missouri-Columbia, 2006. http://hdl.handle.net/10355/4358.
Full textThe entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (May 1, 2007) Vita. Includes bibliographical references.
Sousa, Neto Gilcenio Rodrigues de. "Desigualdade de Carleman global para uma Equação da Onda de Transmissão e Aplicação a um Problema Inverso." Universidade Federal da Paraíba, 2012. http://tede.biblioteca.ufpb.br:8080/handle/tede/7417.
Full textCoordenação de Aperfeiçoamento de Pessoal de Nível Superior
We consider a transmission wave equation in two embedded domains in R2, where the speed is a1 > 0 in the inner domain and a2 > 0 in the outer domain. We prove a global Carleman inequality for this problem under the hypothesis that the inner domain is strongly convex and a1 > a2. As a consequence of this inequality, uniqueness and Lipschitz stability are obtained for the inverse problem of retrieving a stationary potential for the wave equation with Dirichlet data and discontinuous principal coeficient from a single time dependent Neumann boundary measurement.
Considerando uma equação da onda de transmissão em dois domínios imersos em R2, onde a velocidade é a1 > 0 no domínio interior e a2 > 0 no domínio exterior, provamos uma desigualdade de Carleman global para este problema sobre a hipótese de o domínio interior ser fortemente convexo e a1 > a2. Como consequência dessa desigualdade, são obtidas a unicidade e a estabilidade lipschitziana para o problema inverso de retomar um potencial estacionário para a equação da onda com dados de Dirichlet e coeficiente principal descontínuo. Estes dois resultados são obtidos a partir de um único dado (dependente do tempo) de Neumann na fronteira.
Abe, Hiroshi. "Visualization of photoacoustic images in a limited-View measuring system using eigenvalues of a photoacoustic transmission matrix." Kyoto University, 2018. http://hdl.handle.net/2433/232314.
Full textSchormann, Christoph. "Analytische und numerische Untersuchungen bei inversen Transmissionsproblemen zur zeitharmonischen Wellengleichung." Doctoral thesis, [S.l.] : [s.n.], 2000. http://deposit.ddb.de/cgi-bin/dokserv?idn=961894423.
Full textOnofre, Jose Alberto de Mesquita. "Analysis and modeling of the acoustic tomography signal transmission from Davidson Seamount to Sur Ridge : the forward problem." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1999. http://handle.dtic.mil/100.2/ADA376359.
Full text"September 1999". Thesis advisor(s): Ching-Sang Chiu, Curtis A. Collins. Includes bibliographical references (p. 39-40). Also Available online.
Djaziri, Leila. "Diagnostic de défauts d'isolement dans des lignes de transmission électriques : application aux cables de signalisation SNCF." Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112134/document.
Full textThis thesis work focuses on the detection of insulation faults in very long transmission lines. This is detecting soft defects related to the insulation between the conductors of a long cable which are represented by the leakage conductance parameter. Detect these faults, signs of a possible future short-circuit, is an important issue but requires a noninvasive method. For example, in the case of railway signaling cables, it is to develop a method of diagnosis of very low leakage conductances in signaling cables along railways compatible with the movement of trains. Be aware estimate from measurements in one point of the cable, strong resistance distributed over several hundred meters without disturbing the continuous frequency range to 40 kHz, reserved for service signals. Indeed, the signal cables from the train that interest us have an average length 1500 m and are used in the frequency band 0-40 kHz.We propose so a frequency method for estimating low defects to medium frequency in uniform transmission lines with losses. It is based on two main ideas : a detailed analysis of joint effects of dissipation and dispersion and a method of comparing two lines having the same characteristics and differing only leak conductance parameter. This method of comparison was widespread in the case of multiconductor lines by adopting a statistical approach.This thesis has brought new results : losses estimation formulas resulting from the detailed analysis of a share of joint effects of dissipation and dispersion and also the method of comparing two lines. Numerical simulations were made in both cases to validate the proposed frequency method. Experiments were performed to validate the statistical analysis in the case of multiconductor lines
Kubina, Lindsay M. "Problem solving and social learning in spotted hyenas (Crocuta crocuta)." Diss., Kansas State University, 2014. http://hdl.handle.net/2097/18258.
Full textDepartment of Psychological Sciences
Jerome Frieman
Spotted hyenas (Crocuta crocuta) live in highly-complex, female-dominated groups called “clans.” Due to their social arrangement, spotted hyenas were a logical species on which to test the social complexity hypothesis. In the present study, they were presented with a series of puzzle boxes designed to test problem-solving behavior. The five puzzles varied in difficulty. All spotted hyenas solved the puzzle with the lowest difficulty level, five out of six solved the medium puzzles at least once, and one out of six solved the high difficulty puzzle. Some decreases in behavior diversity and time working on the puzzles were observed over successful trials; however, the decreases were only significant for successful trials of one medium-level puzzle. Decreases in work time were observed for some unsuccessful trials and the decrease was statistically significant for the highest difficulty puzzle. Overall, spotted hyenas were proficient at problem solving in the present study. Social learning is an important component of a lengthy juvenile period for spotted hyenas, and they have also been shown to influence one another’s feeding behavior. Furthermore, spotted hyenas participate in scramble competition when feeding and forage for and hoard food. In light of these behaviors, social learning was examined using the social transmission of a flavor preference (STFP) procedure. STFP was not observed overall. The sex of the subjects did not significantly influence the results; however, subjects that interacted with each other longer were significantly more likely to show STFP. The STFP procedure may not be sensitive enough to detect social learning in spotted hyenas. Perhaps spotted hyenas have no need to learn STFP due to their digestive and/or immune systems. The results of the current experiments make important contributions to existing knowledge. Data from other species like spotted hyenas are vital for evaluating the generality of the social complexity hypothesis since support thus far has come from data on primates. This study was the first to investigate STFP in a species from the Feliformia suborder. Additionally, finding more evidence that spotted hyenas have advanced cognitive abilities is essential for researchers and zoo personnel who work with spotted hyenas in captivity.
Nafkha, Amor. "A geometrical approach detector for solving the combinatorial optimisation problem : application in wireless communication systems." Lorient, 2006. http://www.theses.fr/2006LORIS067.
Full textThe demand for mobile communication systems with high data rates and improved link quality for a variety of applications has dramatically increased in recent years. New concepts and methods are necessary in order to cover this huge demand, which counteract or take advantage of the impairments of the mobile communication channel and optimally exploit the limited resources such as bandwidth and power. The problem of finding the least-squares solution to a system of linear equations where the unknown vector is comprised of integers, but the matrix coefficients and given vector are comprised of real numbers, arise in many applications: communications, cryptography, MC-CDMA, MIMO, to name a few. The Maximum Likelihood (ML) decoding is equivalent to finding the closest lattice point in an n-dimensional real space. In general, this problem is known to be non deterministic NP hard. In this thesis, a polynomial-time approximation method called Geometrical Intersection and Selection Detector (GISD) is applied to the MLD problem. Moreover, the proposed approach is based on two complementary "real time" operational research methods: intensification and diversification. Our approach has three important characteristics that make it very attractive for for VLSI implementation. First, It will be shown that the performance of GISD receiver is superior as compared to other sub-optimal detection methods and it provides a good approximation to the optimal detector. Second, the inherent parallel structure of the proposed method leads to a very suitable hardware implementation. Finaly, The GISD allows a near optimal performance with constant polynomial-time, O(n3), computational complexity (unlike the sphere decoding that has exponential-time complexity for low SNR). The proposed Detector can be efficiently employed in most wireless communications systems: MIMO, MC-CDMA, MIMO-CDMA etc. .
Zheng, Hong. "Efficient Algorithms for the Cell Based Single Destination System Optimal Dynamic Traffic Assignment Problem." Diss., The University of Arizona, 2009. http://hdl.handle.net/10150/195304.
Full textGiannopoulos, Antonios. "The investigation of transmission-line matrix and finite-difference time-domain methods for the forward problem of ground probing radar." Thesis, Online version, 1998. http://ethos.bl.uk/OrderDetails.do?did=1&uin=uk.bl.ethos.245873.
Full textBrenot, Dominique. "Transmission du son à l'intérieur d'une structure axisymétrique." Paris 6, 1986. http://www.theses.fr/1986PA066022.
Full textLa, Valérie. "Correction d'atténuation en géométrie conique avec mesures de transmission en tomographie d'émission mono-photonique." Grenoble INPG, 1997. http://www.theses.fr/1997INPG0106.
Full textDalling, Ryan R. "An Investigation of Positive Engagement, Continuously Variable Transmissions." Diss., CLICK HERE for online access, 2008. http://contentdm.lib.byu.edu/ETD/image/etd2391.pdf.
Full textKlas, Juliana. "Planejamento da expansão do sistema de transmissão com dispositivos FACTS e links CC empregando metodologia Branch-and-Bound adaptada." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2013. http://hdl.handle.net/10183/108467.
Full textThis work proposes a mathematical model to the transmission expansion system problem based on the DC power flow model considering the use of DC links and FACTS that is solved using a solution method considering the first and second Kirchhoff’s Law in an enumerative adapted branch-and-bound process. It is possible to highlight two key aspects of the proposed approach: i) presents a mathematical model that can be directly used on expansion transmission systems problems that have AC transmission lines, transformers, DC links and FACTS and ii) is an exact solution method that guarantees the optimum problems’s solutions and contributes to the traditional branch-and-bound method bringing additional relaxations. The solution method applied to Garver’s six-bus network and southeast Brazilian 46 bus network provides correct answers and the mathematical model tested on a modified Garver’s six-bus network presents new possible configurations that enables overall cost reduction to the problem.
Rodriguez, Usaquén Yuly Tatiana. "Experimental study of oil coking problem and contribution to the modelling of heat transfer in turbochargers." Doctoral thesis, Universitat Politècnica de València, 2019. http://hdl.handle.net/10251/117314.
Full text[CAT] La industria automotriz representa uno de los sectores más importantes del mundo. Dada su influencia socioeconómica, la investigación está destinada a reducir el consumo de combustible y las emisiones. Los turbocompresores ofrecen varios beneficios, entre ellos, mayor potencia para un tamaño de motor determinado, mejor economía de combustible y reducción de emisiones. El turbocompresor es una pieza importante para la nueva generación de motores que deben cumplir con la normativa Euro 6 o en el programa estándar de emisiones y combustible de los EE. UU. Tier 3. A medida que se hacen más esfuerzos para aumentar la eficiencia y reducir las emisiones, la complejidad del sistema aumenta. Las altas velocidades de rotación, las condiciones de flujo pulsante y las altas diferencias de temperatura entre los fluidos de trabajo (gases de escape, aire comprimido, aceite lubricante, fluidos refrigerantes) hacen que la turbocarga sea una tarea desafiante. La simulación numérica abre un rango de posibilidades para estudiar el rendimiento, la eficiencia y el diseño de los componentes en el turbocompresor, pero requiere continuos refinamientos de precisión. En esta tesis, se ha hecho un gran esfuerzo para mejorar la comprensión global de los diferentes fenómenos físicos que ocurren al interior del turbocompresor. Se han hecho esfuerzos experimentales y de modelado para comprender el comportamiento térmico del turbocompresor en condiciones de arranque/parada del motor. Luego de una revisión de los estudios térmicos y de los códigos de simulación de transferencia de calor, éste trabajo presenta una extensa campaña de pruebas experimentales que incluye una caracterización térmica del turbocompresor en condiciones estacionarias y transitorias. Posteriormente, se midieron varios turbocompresores para evaluar las consecuencias que los aceites degradados pueden generar en el sistema de rodamientos durante pruebas de resistencia de coque de aceite. Para minimizar las posibilidades de formación de coque, se realizaron algunos estudios teóricos. En primer lugar, se usó un modelo de turbocompresor 1D en GT-PowerTM para un estudio detallado del aumento de temperatura de la carcasa central del turbocompresor durante un paro en caliente del motor. Las estrategias de enfriamiento simuladas apuntan a encontrar un óptimo en términos de minimizae el consumo de energía extra por reducción de la temperatura de la carcasa en Kelvin. Posteriormente, se propone un modelo radial 2D como mejora de un modelo unidimensional existente desarrollado en la CMT - Universitat Politècnica de València. Con el objetivo de conseguir un bajo costo computacional, el modelo radial 2D se desarrolló para ser compatible con simulaciones unidimensionales rápidas de motor. Después, se realizó una solución detallada de los flujos de calor mediante CFD utilizando un diseño 3D de la carcasa central del turbocompresor. El modelo 3D mejora los resultados cuando se requiere la temperatura de los cojinetes/eje. Además, con ésta campaña de CFD se pueden obtener propiedades térmicas dentro del turbocompresor y, por lo tanto, una reducción de las tareas experimentales en el banco de pruebas termohidráulico. Ambos modelos 2D y 3D fueron validados utilizando datos experimentales, demostrando mejoras de precisión de predicción sobre los resultados de modelos anteriores.
[EN] La indústria automotriu representa un dels sectors més importants del món. Donada la seua influència socioeconòmica, la investigació està destinada a reduir el consum de combustible i les emissions. Els turbocompressors oferixen diversos beneficis, entre ells, major potència per a una grandària de motor determinat, millor economia de combustible i reducció d'emissions. El turbocompressor és una peça important per a la nova generació de motors que han de complir amb la normativa Euro 6 o en el programa estàndard d'emissions i combustible dels EE. UU. Tier 3. A mesura que es fan més esforços per a augmentar l'eficiència i reduir les emissions, la complexitat del sistema augmenta. Les altes velocitats de rotació, les condicions de flux polsen-te i les altes diferències de temperatura entre els fluids de treball (gasos de fuga, aire comprimit, oli lubricant, fluids refrigerants) fan que la turbocarga siga una tasca desafiador. La simulació numèrica obri un rang de possibilitats per a estudiar el rendiment, l'eficiència i el disseny dels components en el turbocompressor, però requerix continus refinaments de precisión. En aquesta tesi, s'ha fet un gran esforç per a millorar la comprensió global dels diferents fenòmens físics que ocorren a l'interior del turbocompressor. S'han fet esforços experimentals i de modelatge per a comprendre el comportament tèrmic del turbocompressor en condicions d'arranque/parada del motor. Després d'una revisió dels estudis tèrmics i dels codis de simulació de transferència de calor, este treball presenta una extensa campanya de proves experimentals que inclou una caracterització tèrmica del turbocompressor en condicions estacionàries i transitòries. Posteriorment, es van mesurar uns quants turbocompressors per a avaluar les conseqüències que els olis degradats poden generar en el sistema de rodaments durant proves de resistència de coc d'aceite. Per a minimitzar les possibilitats de formació de coc, es van realitzar alguns estudis teòrics. En primer lloc, es va usar un model de turbocompressor 1D en GT- Power \textsuperscript{TM} per a un estudi detallat de l'augment de temperatura de la carcassa central del turbocompressor durant una desocupació en calent del motor. Les estratègies de refredament simulades apunten a trobar un òptim en termes de minimizae el consum d'energia extra per reducció de la temperatura de la carcassa en Kelvin. Posteriorment, es proposa un model radial 2D com a millora d'un model unidimensional existent desenrotllat en la CMT - Universitat Politècnica de València. Amb l'objectiu d'aconseguir un baix cost computacional, el model radial 2D es va desenrotllar per a ser compatible amb simulacions unidimensionals ràpides de motor. Después, es va realitzar una solució detallada dels fluxos de calor per mitjà de CFD utilitzant un disseny 3D de la carcassa central del turbocompressor. El model 3D millora els resultats quan es requerix la temperatura dels cojinetes/eje. A més, amb esta campanya de CFD es poden obtindre propietats tèrmiques dins del turbocompressor i, per tant, una reducció de les tasques experimentals en el banc de proves termohidráulico. Ambdós models 2D i 3D van ser validats utilitzant dades experimentals, demostrant millores de precisió de predicció sobre els resultats de models anteriores.
Rodriguez Usaquén, YT. (2019). Experimental study of oil coking problem and contribution to the modelling of heat transfer in turbochargers [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/117314
TESIS
Kambou, Samy Jacques André. "Transmission de multimédia dans les réseaux sans fil à qualité de service garantie." Thesis, Poitiers, 2016. http://www.theses.fr/2016POIT2290/document.
Full textThis thesis focuses on the transmission strategies of the multimedia content in wireless networks. The advantage of a such strategy is its ability to manage the resources, according to the objectives of the targeted applications. We propose a transmission scheme, which guarantees the quality of service (QoS), depending on the channel state information and on the multimedia content specifications. We take advantage of the radio channel diversities (spatial, frequency, etc.). ln fact, the association of MIMO and OFDM techniques appears as effective solution to increase the system performance. For this reason, we propose a MIMO-OFDMA system, which considers cross-layer srtategies based on link adaptation schemes to dynamically adjust the system parameters. Firstly, we develop a PHY/APPL cross-layer strategy, dedicated to a single user of a MIMO-OFDMA system, which transmits an H.264/SVC video. The Iink adaptation scheme allows to define the optimum parameters, which minimize the end-ta-end video distortion by using an optimization algorithm under power and bit error rate constraints. To consider the realistic transmission aspects, we propose a PHY/MAC cross-layer strategy, dedicated to a multi-user, multi-service, MIMOOFDMA system. This scheme combines a scheduling policy with optimal parameterization to provide a satisfied troughput to a maximum number of users, acheiving the required services. Finally, the first two solutions are combined to determine the optimal parameters which minimize the end-ta-end distortion of the received video by user, and also acheive QoS requirements of the other services
Galymov, Birzhan. "Distribution Network Reconfiguration For Loss Reduction By Multi-branch Exchange Method." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614663/index.pdf.
Full textGruhne, Volker. "Numerische Behandlung zeitabhängiger akustischer Streuung im Außen- und Freiraum." Doctoral thesis, Universitätsbibliothek Leipzig, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-112604.
Full textChanguel, Nesrine. "Régulation de la qualité lors de la transmission de contenus vidéo sur des canaux sans fils." Phd thesis, Université Paris Sud - Paris XI, 2011. http://tel.archives-ouvertes.fr/tel-00659806.
Full textXu, Qing. "Flexible Radio Resource Management for Multicast Multimedia Service Provision : Modeling and Optimization." Thesis, Belfort-Montbéliard, 2014. http://www.theses.fr/2014BELF0237/document.
Full textThe high throughputs supported by the multimedia multicast services (MBMS) and the limited radio resources result in strong requirement for efficient radio resource management (RRM) in UMTS 3G networks. This PhD thesis proposes to solve the MBMS RRM problem as a combinatorial optimization problem. The work starts with a formal modeling of the problem, named as the Flexible Radio Resource Management Model (F2R2M). An in-depth analysis of the problem complexity and the search landscape is done from the model. It is showed that, by relaxing the OVSF code constraints, the MBMS RRM problem can be approximated as a Multiple-Choice Knapsack Problem (MCKP). Such work allows us to compute the theoretical solution bounds by solving the approximated MCKP. Then the fitness landscape analysis shows that the search spaces are rough and reveal several local optimums. Based on the analysis, some metaheuristic algorithms are studied to solve the MBMS RRM problem. We first show that a Greedy Local Search (GLS) and a Simulated Annealing (SA) allow us to find better solutions than the existing approaches implemented in the UMTS system, however the results are instable due to the landscape roughness. Finally we have developed a Tabu Search (TS) mixed with a Variable Neighborhood Search (VNS) algorithm and we have compared it with GLS, SA and UMTS embedded algorithms. Not only the TS outperforms all the other approaches on several scenarios but also, by comparing it with the theoretical solution bounds generated by the MCKP solver, we observe that TS is equal or close to the theoretical optimal solutions
Deheuvels, Thibaut. "Contributions à l'étude d'espaces de fonctions et d'EDP dans une classe de domaines à frontière fractale auto-similaire." Phd thesis, Université Rennes 1, 2013. http://tel.archives-ouvertes.fr/tel-00869946.
Full textLiang, Haodong. "Fractal Interfaces and Heat Transmission Problems." Digital WPI, 2013. https://digitalcommons.wpi.edu/etd-dissertations/124.
Full textSantiago, Fabio 1985. "Utilização do método da integral dupla em problemas de condução de calor unidimensional em regime transitório." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/263430.
Full textDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
Made available in DSpace on 2018-08-21T01:50:40Z (GMT). No. of bitstreams: 1 Santiago_Fabio_M.pdf: 8778625 bytes, checksum: 682efcdc5efb8549b7c4dbd3564ef87e (MD5) Previous issue date: 2012
Resumo: O objetivo deste trabalho é utilizar o método da integral dupla na obtenção de soluções analíticas aproximadas para problemas de condução térmica unidimensional em regime transitório. Sendo o método da integral dupla um refinamento do amplamente utilizado método da integral simples, também conhecido Karman-Pohlhausen para a camada limite ou método de Goodman para mudança de fase, inicialmente foi proposto um minucioso estudo do capítulo Application of Integral Methods to Transient Nonlinear Heat transfer, cujo objetivo era compreender o funcionamento deste método, assim como selecionar os problemas apresentados neste trabalho. Posteriormente realizou-se o estudo do artigo primordial de aplicação do método da integral dupla publicado por Volkov, bem como dos principais trabalhos envolvendo o método da integral dupla. Ao todo foram selecionados seis casos do trabalho original de Goodman, os quais foram resolvidos com o uso do método da integral dupla para perfis quadrático e cúbico. A escolha de perfis polinomiais se justifica uma vez que estes são de fácil manipulação diante das operações de diferenciação e integração comum os métodos integrais, além disso, o uso de perfis de grau distinto tem como objetivo mostrar a influência da variação deste na obtenção de melhores aproximações. De modo a convalidar os resultados apresentados pelo método da integral dupla, estes foram comparados com as soluções analíticas exatas presente na literatura assim como, com as soluções aproximadas apresentadas por Goodman e com a solução numérica obtida pelo método de volumes de controles. Os resultados obtidos neste trabalho revelam o melhor desempenho do método da integral dupla quando comparado com os resultados obtidos por Goodman em seu trabalho anteriormente citado
Abstract: The objective of this work is to use the method of the double integral to obtain approximate analytical solutions for one-dimensional heat conduction problems in the transitional regime. As the method of a double integral refinement of the widely used simple integral method, also known Karman-Pohlhausen for the boundary layer or the Goodman method for phase change, was initially proposed a thorough study of Chapter Application of Integral Methods to Transient Nonlinear Heat transfer, the objective of which was to understand the functioning of this method as well as selecting the problems presented in this paper. Subsequently we carried out the study of the primary article of the method of the double integral posted by Volkov as well as major works involving the method of double integral. In all six cases were selected from the original work of Goodman, which were solved using the method of the double integral for quadratic and cubic profiles. The choice of polynomial profiles is justified as they are easy to handle before the operations of common differentiation and integration methods, moreover, the use of profiles of different degree is intended to show the influence of the variation in obtaining better approximations. In order to validate the results presented by the method of the double integral, they were compared with the exact analytical solutions in the literature as well as with the approximate solutions presented by Goodman and the numerical solution obtained from a volume control. The present results show the improved performance of the method of the double integral compared with the results obtained by Goodman in their work cited above
Mestrado
Termica e Fluidos
Mestre em Engenharia Mecânica
Schulze, Bert-Wolfgang. "Boundary value problems with the transmission property." Universität Potsdam, 2009. http://opus.kobv.de/ubp/volltexte/2009/3037/.
Full textMelnyk. "PROBLEMS OF THE UKRAINE GAS TRANSMISSION SYSTEM." Thesis, Київ 2018, 2018. http://er.nau.edu.ua/handle/NAU/33815.
Full textNascimento, Edgar [UNESP]. "Modelagem generalizada do problema de planejamento da expansão de sistemas de transmissão." Universidade Estadual Paulista (UNESP), 2014. http://hdl.handle.net/11449/111137.
Full textNeste trabalho foi apresentado uma nova modelagem matemática para problemas de Planejamento da expansão de sistemas de transmissão ao longo prazo que permite uma mudança no conceito de expansão de sistema de transmissão. Nos problemas de planejamento da expansão de sistemas de transmissão tradicionais apenas as adições de linhas candidatas são consideradas. Neste trabalho um novo conceito de planejamento da expansão do sistema de transmissão é encontrar uma nova solução para a topologia base onde todas as linhas estão temporariamente desconectadas e a implementação dessas linhas são reconsideradas quando elas podem voltar à sua posição anterior. Portanto as linhas da topologia de base não será restabelecida se impedir o desempenho do sistema. Depois um novo problema é resolvido para encontrar o plano futuro da rede do sistema elétrico, com a adição de novas linhas de candidatas na topologia base modificada. A fim de encontrar um plano mais eficiente para a rede futura, a metodologia proposta é implementada usando a linguagem de modelagem para a programação matemática (AMPL) e solucionada usando o solver comercial CPLEX. A fim de validar a abordagem proposta e fazer alguma comparação com o método na literatura, três sistemas de testes são realizados, tais como: o sistema de 24-Bus IEEE teste com 41 linhas de candidatas, um estudos de casos práticos do sistema de 46-Bus do Sul do Brasil com 79 linhas de candidatas, e do sistema colombiano 93-Bus com 155 candidatas. Para sistemas de grande porte, a fim de facilitar a implementação do modelo matemático, uma estratégia é apresentada para reduzir o espaço de busca das barras em que a geração ou a demanda. Nos problemas de planejamento da expansão da transmissão geralmente nos deparamos com um problema de programação não-linear inteira mista (PNLIM) usando o modelo DC, o que torna impossível usar o solver linear ...
In this work and in order to solve the long-term transmission expansion planning problems, a novel mathematical model which is based on a change in the concept of expanding a transmission system is presented. In traditional transmission system expansion planning, only the additions of candidate lines are considered. In this work, a new concept of transmission system expansion planning is to find a new solution for the base topology where all the lines are temporarily disconnected and the implementation of these lines are reconsidered when they may return to their previous position. Therefore, the lines of the base topology will not be reconnected if they prevent the system performance. Afterwards a new problem is solved to find the future plan of the electrical system network with the addition of new candidate lines in the modified base topology. In order to find a more efficient plan for the future network, the proposed methodology is implemented using a Modeling Language for Mathematical Programming (AMPL) and solved using the commercial solver of CPLEX. In order to validate the proposed approach and make some comparison with the method in the literature, three test systems are conducted such as: the 24-Bus IEEE test system with 41 candidate lines, a practical case studies of 46-Bus South Brazilian system with 79 candidate lines, and the 93-Bus Colombian system with 155 candidates. For large-scale systems, in order to facilitate the implementation of the mathematical model, a strategy to reduce the search space of the buses in which the generation or demand has been presented. In the transmission expansion planning problems, usually we face with a mixed integer non-linear programming problem (MINLP) using the DC model, which make it impossible to use the linear solver of CPLEX. The strategy to overcome this problem is using the disjunctive linear model, which is a DC linear equivalent model. The ...
Nascimento, Edgar. "Modelagem generalizada do problema de planejamento da expansão de sistemas de transmissão /." Ilha Solteira, 2014. http://hdl.handle.net/11449/111137.
Full textBanca: José Roberto Sanches Mantovani
Banca: Antonio Padilha Feltrin
Banca: Carlos Roberto Mendonça da Rocha
Banca: Edgar Manuel Carreño Franco
Resumo: Neste trabalho foi apresentado uma nova modelagem matemática para problemas de Planejamento da expansão de sistemas de transmissão ao longo prazo que permite uma mudança no conceito de expansão de sistema de transmissão. Nos problemas de planejamento da expansão de sistemas de transmissão tradicionais apenas as adições de linhas candidatas são consideradas. Neste trabalho um novo conceito de planejamento da expansão do sistema de transmissão é encontrar uma nova solução para a topologia base onde todas as linhas estão temporariamente desconectadas e a implementação dessas linhas são reconsideradas quando elas podem voltar à sua posição anterior. Portanto as linhas da topologia de base não será restabelecida se impedir o desempenho do sistema. Depois um novo problema é resolvido para encontrar o plano futuro da rede do sistema elétrico, com a adição de novas linhas de candidatas na topologia base modificada. A fim de encontrar um plano mais eficiente para a rede futura, a metodologia proposta é implementada usando a linguagem de modelagem para a programação matemática (AMPL) e solucionada usando o solver comercial CPLEX. A fim de validar a abordagem proposta e fazer alguma comparação com o método na literatura, três sistemas de testes são realizados, tais como: o sistema de 24-Bus IEEE teste com 41 linhas de candidatas, um estudos de casos práticos do sistema de 46-Bus do Sul do Brasil com 79 linhas de candidatas, e do sistema colombiano 93-Bus com 155 candidatas. Para sistemas de grande porte, a fim de facilitar a implementação do modelo matemático, uma estratégia é apresentada para reduzir o espaço de busca das barras em que a geração ou a demanda. Nos problemas de planejamento da expansão da transmissão geralmente nos deparamos com um problema de programação não-linear inteira mista (PNLIM) usando o modelo DC, o que torna impossível usar o solver linear ...
Abstract: In this work and in order to solve the long-term transmission expansion planning problems, a novel mathematical model which is based on a change in the concept of expanding a transmission system is presented. In traditional transmission system expansion planning, only the additions of candidate lines are considered. In this work, a new concept of transmission system expansion planning is to find a new solution for the base topology where all the lines are temporarily disconnected and the implementation of these lines are reconsidered when they may return to their previous position. Therefore, the lines of the base topology will not be reconnected if they prevent the system performance. Afterwards a new problem is solved to find the future plan of the electrical system network with the addition of new candidate lines in the modified base topology. In order to find a more efficient plan for the future network, the proposed methodology is implemented using a Modeling Language for Mathematical Programming (AMPL) and solved using the commercial solver of CPLEX. In order to validate the proposed approach and make some comparison with the method in the literature, three test systems are conducted such as: the 24-Bus IEEE test system with 41 candidate lines, a practical case studies of 46-Bus South Brazilian system with 79 candidate lines, and the 93-Bus Colombian system with 155 candidates. For large-scale systems, in order to facilitate the implementation of the mathematical model, a strategy to reduce the search space of the buses in which the generation or demand has been presented. In the transmission expansion planning problems, usually we face with a mixed integer non-linear programming problem (MINLP) using the DC model, which make it impossible to use the linear solver of CPLEX. The strategy to overcome this problem is using the disjunctive linear model, which is a DC linear equivalent model. The ...
Doutor
Zampaulo, Amarildo José. "Uma abordagem do problema de contaminação de sistemas de transmissão por fluidos e o controle através da técnica de contagem de partículas." Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/18/18150/tde-07022017-105608/.
Full textThe technological advance has proportionated to the industry in general to develop and to manufacture more sophisticated products in all the fields of science. Not distant of this reality, the industry of mobility also comes incorporating through bold projects the new technologies in its products, thus answering to the needs and expectations of its customers, who ask for products with high productivity and availability to work. These technologies are related with the power transmission systems by fluids through the introduction of electrohydraulic valves, and also by the reduction of tolerance between smooth and rotary parts of the system. From the introduction of this new technology, the emphases of this dissertation was show the importance of the contamination control in the process phases of conception, manufacturing and assembly of the product, including brake the paradigm related with human factors, and specially the fluid contamination control of the power transmission using the particle counting technology. To show that through the determination of acceptable limits of contamination for each type of power transmission system, as a function of the type of added technology, it is possible to drastically reduce the failures in the power transmission systems by fluids during the operation of the product in the field, even being this contamination considered an invisible enemy.
Mölder, Mikael, and Felicia Schnell. "Informationsstöd för patienter som genomgår intern strålbehandling : Mobilapplikation som kommunikationsverktyg inom sjukvården." Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-193914.
Full textThe global life expectancy increases with an aging population, which leads to more demanding requirements on healthcare. Humans live longer but at the same time spend longer time of their lives being sick, which requires higher capacities within the healthcare system. Communication forms a problem by complicating the possibilities of healthcare to handle the situation, which indicates a need of change. A possible solution is to utilize the possibilities of digitalisation, with the help of e-health, to achieve development of the welfare where healthcare maintains high quality and patients are in focus. Mobile phones have shown to be a suitable tool for this cause due to the fact that they form a central tool for communication in today’s society. Nuclear medicine is the diagnostics and treatment with the help of radioactive substances and is part of today’s treatment of thyroid diseases. Using these preparations results in a number of restrictions, which has to be taken into consideration by the patient and should be given by the responsible physician. On behalf of the department for nuclear medicine at Karolinska univer-sity hospital a mobile application has been developed where patients and relatives, in a conven-ient way, can take part of information about their treatment. With the application, a complementary information channel can be created between patients and the department staff in order to support the communication. The importance of correct and transparent information in close cooperation with healthcare professionals has been discussed, which forms the base of the applications design. For the purpose of investigating the potential of ICT in healthcare, a pre-study in form of an interview was conducted. Together with a survey in order to evaluate the concept, these two form the basis of the discussion on the possibilities to contribute to the communication in the studied section of healthcare. The result shows that there is a lot of potential for ICT within healthcare, but the systems that are in use today lacks in quality, which is demanded and expected by the care situation. By introducing the concept, patients can take part of information about their treatment in an early stage, which allows them to prepare on their own terms, and is a step towards the healthcare of the future.
Manrique, John Peter Oyardo. "Reconstrução do espectro de fótons de aceleradores lineares clínicos com base na curva de transmissão e no algoritmo de recozimento simulado generalizado." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/59/59135/tde-31012016-151001/.
Full textThe spectral distribution of megavoltage X-rays used in radiotherapy departments is a fundamental quantity from which, in principle, all relevant information required for radiotherapy treatments can be determined. The direct measurement is difficult to achieve clinically and analyzing the transmission is a clinically viable indirect method for determining clinical linear accelerators photon spectra. In this method, transmission signals are acquired after the beam passes through different thicknesses of attenuators. The objective of this work was the establishment and application of an indirect method that used a spectral model based on generalized simulated annealing algorithm to determine the spectrum of clinical linear accelerators photons based on the transmission curve. Analysis of the spectra was made by analytical determination of dosimetric quantities and related parameters.
Witwit, Abdul-Mehdi Rahim Mohammed. "Meshing techniques for TLM diffusion problems." Thesis, University of Hull, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.296281.
Full textAragonès, Martín Àngels. "Graph theory applied to transmission path problems in vibroacoustics." Doctoral thesis, Universitat Ramon Llull, 2015. http://hdl.handle.net/10803/299378.
Full textA fundamental aspect when solving a vibroacoustic problem in a mechanical system is that of finding out how energy flows from a given source to any part of the system. This would help making decisions to undertake actions for diminishing, for example, the noise or vibration levels at a given system area. The dynamic behavior of a mechanical system can be estimated using different numerical methods, each of them targeting a certain frequency range. Whereas at low frequencies deterministic methods such as the Finite Element Method (FEM) or the Boundary Element Method (BEM) can be applied, statistical methods like Statistical Energy Analysis (SEA) become unavoidable at high frequencies. In addition, a large variety of approaches such as the hybrid FE-SEA, the Energy Distribution (ED) models or the Statistical modal Energy distribution Analysis (SmEdA), among many others, have been recently proposed to tackle with the so-called mid-frequency problem. However, although numerical methods can predict the pointwise or averaged vibroacoustic response of a system, they do not directly provide information on how energy flows throughout the system. Therefore, some kind of post-processing is required to determine energy transmission paths. The energy transmitted through a particular path linking a source subsystem, where external energy is being input, and a target subsystem, can be computed numerically. Yet, identifying which paths dominate the whole energy transmission from source to target usually relies on the engineer's expertise and judgement. Thus, an approach for the automatic identification of those paths would prove very useful. Graph theory provides a way out to this problem, since powerful path algorithms for graphs are available. In this thesis, a link between vibroacoustic models and graph theory is proposed, which allows one to address energy transmission path problems in a straightforward manner. The dissertation starts focusing on SEA models. It is first shown that performing a transmission path analysis (TPA) in SEA makes sense. Then a graph that accurately represents the SEA model is defined. Given that the energy transmission between sources and targets is justified by the contribution of a limited group of dominant paths in many cases of practical interest, an algorithm to find them is presented. Thereafter, an enhanced algorithm is devised to include the stochastic nature of SEA loss factors in the ranking of paths. Next, it is discussed how transmission path analysis can be extended to the mid frequency range. The graph approach for path computation becomes adapted for some ED models, as well as for SmEdA. Finally, we outline another possible application of graph theory to vibroacoustics. A graph cut algorithm strategy is implemented to achieve energy reduction at a target subsystem with the sole modification of a reduced set of loss factors. The set is found by computing cuts in the graph separating source and receiver subsystems.
Un aspecto fundamental a la hora de resolver un problema vibroacústico en un sistema mecánico es el de determinar cómo fluye la energía desde una determinada fuente hasta cualquier parte del sistema. Ello ayudaría a tomar decisiones para emprender acciones destinadas a disminuir, por ejemplo, los niveles de ruido y vibraciones en un área del sistema dada. El comportamiento dinámico de un sistema mecánico se puede estimar utilizando varios métodos numéricos, cada uno de ellos enfocado a un determinado rango de frecuencia. Mientras en las bajas frecuencias se pueden aplicar métodos deterministas como el Método de los Elementos Finitos (FEM) o el método de Elementos de Contorno (BEM), los métodos estadísticos como el Análisis Estadístico Energético son inevitables en las altas frecuencias. Además, se han desarrollado gran variedad de técnicas como el FE-SEA híbrido, los modelos de Distribución de Energía (ED) o el Análisis Estadístico de distribución de Energía modal (SmEdA), entre otras, para tratar el llamado problema de las medias frecuencias. Sin embargo, aunque los métodos numéricos pueden predecir la respuesta vibroacústica puntual o promediada de un sistema mecánico, ellos no proporcionan información sobre como fluye la energía en el sistema. Por lo tanto, hace falta algún tipo de post-procesado para determinar las vías de transmisión de energía. La energía transmitida a través de un determinado camino que conecta un subsistema fuente, donde se introduce la energía, y un subsistema receptor, se puede calcular numéricamente. A pesar de ello, identificar qué caminos dominan la transmisión de energía desde la fuente al receptor normalmente suele recaer en la experiencia o el juicio del ingeniero. Así pues, un método automático para identificar estos caminos resultaría muy útil. La teoría de grafos proporciona una solución a este problema, ya que existen potentes algoritmos de cálculos de caminos en grafos. En esta tesis, se propone un enlace entre los modelos vibroacústicos y la teoría de grafos, que permite abordar los problemas de vías de transmisión de forma directa. La disertación empieza centrándose en los modelos SEA. Primeramente, se muestra que tiene sentido realizar un análisis de vías de transmisión (TPA) en un modelo SEA. Seguidamente, se define un grafo que representa fielmente un modelo SEA. Teniendo en cuenta que en muchos casos de interés práctico, la transmisión de energía entre fuentes y receptores se puede justificar mediante la contribución de un grupo finito de vías de transmisión, se define un algoritmo para encontrarlas. A continuación, se implementa un algoritmo que incluye en el cómputo de caminos la naturaleza estocástica de los factores de pérdidas SEA. Luego, se trata la extensión del análisis de vías de transmisión al rango de media frecuencia. La técnica de teoría de grafos aplicada a cálculo de caminos se adapta para algunos modelos ED y también SmEdA. Finalmente, se presenta otra posible aplicación de la teoría de grafos a la vibroacústica. Se implementa una estrategia basada en algoritmos de cortes en grafos destinada a reducir la energía en un subsistema receptor mediante la simple modificación de un grupo reducido de factores de pérdidas. El grupo se encuentra calculando cortes que separen en el grafo los subsistemas fuentes de los subsistemas receptores.
Baig, Adam Mirza. "Reflection and transmission problems in vertically inhomogeneous elastic media." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0017/MQ47005.pdf.
Full textHummel, Felix Benjamin [Verfasser]. "Stochastic Transmission and Boundary Value Problems / Felix Benjamin Hummel." Konstanz : KOPS Universität Konstanz, 2019. http://d-nb.info/1189067293/34.
Full textASSIS, FERNANDO APARECIDO DE. "CONSTRUCTIVE METAHEURISTIC ALGORITHM FOR SOLVING TRANSMISSION EXPANSION PLANNING PROBLEMS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2018. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=35771@1.
Full textCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
PROGRAMA DE EXCELENCIA ACADEMICA
O planejamento da expansão da transmissão (PET) visa identificar reforços para a rede a fim de permitir uma adequada interligação entre a demanda e a geração de energia elétrica, ambas previstas para um determinado horizonte futuro de planejamento. Um bom plano de expansão deve garantir o adequado equilíbrio entre o custo de investimento e o custo de operação, mantendo ainda um nível satisfatório de confiabilidade no fornecimento da energia. Entretanto, a identificação de bons planos de expansão para a rede de transmissão tem se tornado uma tarefa cada vez mais difícil. Isso se deve, principalmente, às características e dimensões dos sistemas atuais e, ainda, às incertezas inerentes ao problema. Dessa forma, torna-se necessário o desenvolvimento de ferramentas cada vez mais ela-boradas para auxílio dos planejadores. Neste sentido, é proposto nesta tese de dou-torado um algoritmo metaheurístico construtivo, denominado AMC-PET, o qual realiza um processo gradual e concomitante de construção de soluções viáveis (planos de expansão). Por meio de mecanismos baseados principalmente em índices de sensibilidade para avaliação dos reforços candidatos e na troca de informações entre as soluções correntes, o processo construtivo proposto é conduzido, parcimoniosamente, na direção de planos de excelente qualidade. Para validação da metodologia proposta, é utilizado o problema PET estático de longo prazo, considerando o critério de segurança N-1 para a rede de transmissão. Um mode-lo linearizado de rede com a inclusão de perdas ôhmicas é utilizado para análise das configurações obtidas. Dois sistemas teste, comumente utilizados neste tópico de pesquisa e, também, um sistema real de grande porte, que corresponde à rede elétrica do sul do Brasil, são empregados na validação.
The transmission expansion planning (TEP) aims to identify reinforcements for the network in order to allow an adequate interconnection between load and electric power generation, both foreseen for a given future planning horizon. A good expansion plan must ensure the proper balance between investment and operating costs, while preserving a satisfactory reliability level in the energy supply. However, identifying good expansion plans for the transmission network has become an increasingly difficult task. This is mainly due to the characteristics and dimensions of current power systems and also to the uncertainties inherent to the problem. Thus, it becomes necessary to develop even more elaborate tools to assist system planners. This doctoral thesis proposes a new optimization tool named constructive metaheuristic algorithm (CMA-TEP). The proposed CMA-TEP tool performs a gradual and parallel process of building feasible solutions (expansion plans). By means of mechanisms mainly based on sensitivity indices for the evaluation of candidate reinforcements and on the information exchange among current solutions, the proposed constructive process is parsimoniously conducted towards high quality plans. To verify the performance of the proposed methodology, the long-term static PET problem considering the N-1 security criterion for the transmission network is solved. A linearized network model with the inclusion of ohmic losses is used to analyze the obtained configurations. Two test systems, commonly utilized in this research area, and also a real large network, which corresponds to the electric grid of Southern Brazil, are used to validate the proposed method.
Lopes, Valber Sardi [UNESP]. "Metaheurística GRASP para o problema de planejamento da expansão de sistemas de transmissão de energia elétrica." Universidade Estadual Paulista (UNESP), 2013. http://hdl.handle.net/11449/87168.
Full textO Problema do Planejamento da Expansão de Sistemas de Transmissão é um problema de otimização combinatória, cujo objetivo é buscar o atendimento de requisitos de cargas a custos mínimos de investimentos, percebendo um horizonte de longo prazo. A perspectiva do planejamento otimizado deve ser feita observando duas possiblidades: o planejamento estático e o planejamento multiestágio. No planejamento estático, o planjedor procura responder as questões onde e que tipos de elementos de transmissão precisam ser adicionados ou construídos para integrar a solução do sistema futuro. No entanto, quando a estratégia de expansão ótima abrange todo um período, o planejador deseja saber quando o circuito deve ser instalado, trata-se de um planejamento multiestágio. Em ambas alternativas, a resolução do problema do planejamento deve abranger duas etapas consecutivas: a modelagem matemática e a técnica de solução para resolver essa modelagem. Neste trabalho é apresentada uma proposta de planejamento estático utilizando aMetaheurística GRASP como técnica de solução para o problema do planejamento.
The Problem of Expansion Planning of Transmission Systems is a combinatorial optimization problem whose goal is to seek the assistance of cargo requirements at minimal cost investment, realizing a long-term horizon.The prospect of planning should be optimized observing two possibilities: planning static and multistage planning. In planning static, designer seeks to answer the questions where and what types of transmission elements need to be added or built to integrate the solution of the future system. However, when the optimal expansion strategy covers the whole period, the planner wants to know when the circuit must be installed, it is a multistage planning. In both alternatives, solving the problem of planning should cover two consecutive steps: mathematical modeling and solution technique to solve this modeling.This work presents a planning proposal using the static technique as GRASP metaheuristic solution to the problem of planning.