Ce travail de thèse cherche à caractériser, à l'aide d’expériences de laboratoire, le mouvement d'un fluide stratifié à la fois tournant et cisaillé. Dans ce contexte on a considéré trois problèmes qui sont issus des observations géophysiques et astrophysiques où ces écoulements sont très communs. En premier nous avons observé expérimentalement et modélisé l'évolution en temps d'un anticyclone en milieu stratifié tournant, dans le but de comprendre la longévité des meddies, des vortex qui se forment à la sortie de la Méditerranée et peuvent perdurer pendant des années. Nos anticyclones modèles montrent une relaxation visqueuse anormale en raison de l’interaction entre stratification et cisaillement. Nos résultats expérimentaux ont été confirmés à l'aide d'un modèle géostrophique et de simulations numériques qui montrent aussi le rôle majeur joué par les circulations secondaires. Dans un deuxième temps nous avons considéré la stabilité linéaire de l'écoulement de Couette Plan, un des plus simple des écoulement plans cisaillés. On montre que cet écoulement devient instable lorsque l'on ajoute de la stratification verticale. Nous remarquons aussi que la structure spatiale de l'instabilité ressemble à celle de certains jets océaniques que l'on observe près de l'équateur. Enfin nous avons caractérisé une instabilité non linéaire dite des zombie vortex qui a été récemment découverte et pourrait jouer un rôle fondamental dans la déstabilisation des disques d'accrétion, une étape fondamentale de la formation des planétaire. Nous avons construit le diagramme de stabilité de la ZVI dans l'espace de trois fréquences caractéristiques et quantifié la dissipation visqueuse. / The present PhD work comes with the scope of characterizing, analysing and modelling some laboratory flows in the simultaneous presence of rotation, stratification and shear. To this aim we address three specific questions inspired by geophysics and astrophysics where these three ambient features are commonly relevant. First we characterize and model the time evolution of a compact anticyclone in a rotating and stratified laboratory flow. We aim to understand the longevity of analogous vortices known as meddies which populate the Atlantic ocean at the exit of the Mediterranean sea. We observe that viscous relaxation happens in an unusual way because of the balance between rotation and stratification. The results are confirmed by a quasi-geostrophic model and numerical simulations which show the crucial role played by secondary circulations. Secondly we consider the linear stability of one of the simplest parallel shear flow, namely the plane Couette Flow, and show that it becomes unstable when adding a vertical stratification. Interestingly the unstable pattern reminds of deep oceanic jets observed close to the equator. The signature of this instability is observed in an ad-hoc experimental flow and interpreted with the support of direct numerical simulations. Finally we characterize the behaviour of a recently disclosed finite amplitude instability, namely the zombie vortex instability or ZVI. This instability appears when rotation, stratification and shear are of the same order and may may destabilize proto-planetary disks. We construct a stability diagram for ZVI in the space of the three ambient frequencies and analyse the effect of viscous dissipation.

Orientador: Prof. Dr. Douglas Alves Cassiano / Dissertação (mestrado) - Universidade Federal do ABC. Programa de Pós-Graduação em Energia, 2015. / O acionamento de equipamentos rotativos na indústria petroquímica pode ser realizado a partir de motores elétricos ou turbinas a vapor. Os motores elétricos consomem energia elétrica e as turbinas a vapor consomem combustíveis, como Gás Natural e o Óleo Combustível. Os custos com estes insumos sofrem influência de vários fatores: políticas públicas, valor do dólar, valor do preço de mercado (PLD), valores de contrato e a própria eficiência de cada equipamento. Dessa forma, o objetivo geral deste trabalho é identificar oportunidades de eficiência energética na gestão do acionamento de equipamentos rotativos típicos de uma Indústria Petroquímica brasileira. Diante de tantas influências que variam em um curto espaço de tempo, uma ferramenta de apoio a gestão é a modelagem de equações lineares e integrais mistas (Mixed Integer Linear Programming ¿ MILP) para tomada de decisão com múltiplos critérios em relação ao consumo de energia nestes equipamentos. Comprovou-se que utilizando MILP é possível conquistar ganhos de eficiência energética. A escolha ótima do tipo de acionamento dos equipamentos rotativos e demais graus de liberdade apresentaram ganho anual médio de R$ 1.679.000/ano. A modelagem com MILP se mostrou eficaz, acurada e robusta. Foi confirmada a importância de uma modelagem e simulação de resposta rápida e a sua execução numa frequência maior possível, uma vez que os ganhos potenciais executando-se o modelo uma vez por dia foram 81% maiores do executando-se uma vez por mês. Esta metodologia apresenta um potencial de aplicação em outras plantas industriais, desde que possuam características semelhantes à estudada. / Rotating equipments in petrochemical industry are usually driven using steam turbines or electric motors. Electric motors consume electricity and steam turbines consume fuels such as natural gas and fuel oil. The costs of these energy inputs are influenced by: public policy, dollar rate, market prices, contracts values and equipments efficiency. Thus, the aim of this study is to identify energy efficiency opportunities at rotating equipment drive management of a Brazilian Petrochemical Industry. With so many influences that range in a short time, a management support tool is Mixed Integer Linear Programming ¿ MILP for decision making with multiple criteria. It was possible to prove that using MILP can achieve energy efficiency gains. The optimal rotating equipment drive choice and other degrees of freedom had an average annual gain of R$ 1,679,000/year. MILP proved effective, accurate and robust. It confirmed the importance of modeling and simulation with quickly response and its implementation in a higher possible rate, since the potential gains running the model once per day were 81% higher performing once a month. This methodology has a potential application in other industrial plants, since they have similar characteristics to the studied.

Modern gas turbine engines run at extremely high temperatures which require the high pressure turbine blades to be extensively cooled in order to reach life requirements. This must be done using the minimum amount of coolant in order to reduce the negative impacts on the cycle efficiency. In the design process the cooling configuration and stress distribution must be carefully considered before verification of the design is conducted. Improvements to all three of these blade design areas are presented in this thesis which investigates internal cooling systems in the form of ribbed, radial passages and leading edge impingement systems. The effect of rotation on the heat transfer distribution in ribbed radial passages is investigated. An engine representative triple-pass serpentine passage, typical of a gas turbine mid-chord HP blade passage, is simulated using common industrial RANS CFD methodology with the results compared to those from the RHTR, a rotating experimental facility. The simulations are found to perform well under stationary conditions with the rotational cases proving more challenging. Further study and simulations of radial passages are undertaken in order to understand the salient flow and heat transfer features found, namely the inlet velocity profile and rib orientation relative to the mainstream flow. A consistent rib direction gives improved heat transfer characteristics whilst careful design of inlet conditions could give an optimised heat transfer distribution. The effect of rotation on the heat transfer distribution in leading edge impingement systems is investigated. As for the radial passages, RANS CFD simulations are compared and validated against experimental data from a rotating heat transfer rig. The simulations provide accurate average heat transfer levels under stationary and rotating conditions. The full target surface heat transfer in an engine realistic leading edge impingement system is investigated. Experimental data is compared to RANS CFD simulations. Experimental results are in line with previous studies and the simulations provide reasonable heat transfer predictions. A new method of combined thermal and mechanical analysis is presented and validated for a leading edge impingement system. Conjugate CFD simulations are used to provide a metal temperature distribution for a mechanical analysis. The effect of changes to the geometry and temperature profile on stress levels are studied and methods to improve blade stress levels are presented. The thermal FEA model is used to quantify the effect of HTC alterations on different surfaces within a leading edge impingement system, in terms of both temperature and stress distributions. These are then used to provide improved target HTC distributions in order to increase blade life. A new method using Gaussian process regression for thermal matching is presented and validated for a leading edge impingement case. A simplified model is matched to a full conjugate CFD solution to test the method's quality and reliability. It is then applied to two real engine blades and matched to data from thermal paint tests. The matches obtained are very close, well within experimental accuracy levels, and offer consistency and speed improvements over current methodologies.

abstract: The subject of this thesis is concerned with the amount of cooling air assigned to seal high pressure turbine rim cavities which is critical for performance as well as component life. Insufficient air leads to excessive hot annulus gas ingestion and its penetration deep into the cavity compromising disc life. Excessive purge air, adversely affects performance. Experiments on a rotating turbine stage rig which included a rotor-stator forward disc cavity were performed at Arizona State University. The turbine rig has 22 vanes and 28 blades, while the rim cavity is composed of a single-tooth rim lab seal and a rim platform overlap seal. Time-averaged static pressures were measured in the gas path and the cavity, while mainstream gas ingestion into the cavity was determined by measuring the concentration distribution of tracer gas (carbon dioxide). Additionally, particle image velocimetry (PIV) was used to measure fluid velocity inside the rim cavity between the lab seal and the overlap. The data from the experiments were compared to an 360-degree unsteady RANS (URANS) CFD simulations. Although not able to match the time-averaged test data satisfactorily, the CFD simulations brought to light the unsteadiness present in the flow during the experiment which the slower response data did not fully capture. To interrogate the validity of URANS simulations in capturing complex rotating flow physics, the scope of this work also included to validating the CFD tool by comparing its predictions against experimental LDV data in a closed rotor-stator cavity. The enclosed cavity has a stationary shroud, a rotating hub, and mass flow does not enter or exit the system. A full 360 degree numerical simulation was performed comparing Fluent LES, with URANS turbulence models. Results from these investigations point to URANS state of art under-predicting closed cavity tangential velocity by 32% to 43%, and open rim cavity effectiveness by 50% compared to test data. The goal of this thesis is to assess the validity of URANS turbulence models in more complex rotating flows, compare accuracy with LES simulations, suggest CFD settings to better simulate turbine stage mainstream/disc cavity interaction with ingestion, and recommend experimentation techniques. / Dissertation/Thesis / Masters Thesis Mechanical Engineering 2016

Submitted by Lucienne Costa (lucienneferreira@ufcg.edu.br) on 2018-04-10T18:33:46Z No. of bitstreams: 1 ANDERSSON GUIMARÃES OLIVEIRA – DISSERTAÇÃO (PPGEM) 2017.pdf: 7033521 bytes, checksum: 309c4388940437a24da0b294b0476d2e (MD5) / Made available in DSpace on 2018-04-10T18:33:46Z (GMT). No. of bitstreams: 1 ANDERSSON GUIMARÃES OLIVEIRA – DISSERTAÇÃO (PPGEM) 2017.pdf: 7033521 bytes, checksum: 309c4388940437a24da0b294b0476d2e (MD5) Previous issue date: 2017-12-19 / Capes / Dentre as diversas fontes de vibração das máquinas rotativas, existe uma que decorre da ressonância entre a frequência natural da máquina e velocidade de rotação em um dado instante. Dependendo das dimensões do sistema rotativo e forças envolvidas, os efeitos decorrentes dessa ressonância podem ser danosos. A solução clássica para mitigar tal efeito é evitar que a máquina opere em frequências próximas à sua frequência natural ou projetá-la de tal modo que sua frequência de ressonância esteja acima da frequência de operação. Contudo, para situações onde as duas soluções supracitadas não se aplicam, uma alternativa é permitir que ocorra variação nos parâmetros da máquina com o intuito de ajustar sua frequência natural dinamicamente. Portanto, este trabalho propõe o uso de mancais de rigidez variável ao qual se denomina mancais adaptativos. Esses mancais utilizam elementos de máquina que empregam a tecnologia de ligas com memória de forma (LMF), valendo-se da capacidade que essas ligas possuem de mudar a rigidez em função da temperatura. Para tanto, foi projetado, caracterizado e testado um protótipo de mancal adaptativo empregando molas de NiTi. O protótipo sofreu ensaios dinâmicos em uma bancada didática de dinâmica da rotação, instalada no Laboratório de Vibrações e Instrumentação do Programa de Pós-Graduação em Engenharia Mecânica da UFCG. Foram obtidos resultados satisfatórios, tanto na variação da rigidez, como no tempo de resposta a partir das melhorias empregadas nos sistemas de aquecimento e resfriamento do dispositivo. / Among of many rotating machinery vibration sources, there are one that is due to resonance between natural machine frequency and rotating speed in a specific moment. Depending on rotating system dimensions and envolved forces, the effects due this resonance can make damages. The classical solution to mitigate this effect is avoid that machine operates in frequencies near from natural frequency or design it for your natural frequency been far from it operation frequency. However, for situations where there two solutions can´t be applied, an alternative is enable that the machine parameters changes to adjust the natural frequency of machine dynamically.This study proposes the use of variable stiffness bearing known as adaptative bearing. These bearings uses machine elements that apply SMA technology, which the possibility to change stiffness due temperature changes. So, was designed, characterized and tested a prototype at Laboratory of Vibration and Instrumentation of Mechanical Engineering Post Graduate UFCG Program. It was obtained satisfactory results relates to stiffness variation and response time due improvements on heating and cooling systems.

Made available in DSpace on 2014-06-11T19:29:47Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-04-15Bitstream added on 2014-06-13T18:59:35Z : No. of bitstreams: 1 oliveirafilho_mamb_me_arafcl.pdf: 992065 bytes, checksum: 312aca3f28bcd08bba714acf7864ed12 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / É observada, no atual contexto da sociedade capitalista, a manifestação em escala crescente de empreendimentos cooperativos baseados na autogestão. Tendo surgido e se desenvolvido no movimento operário em meados do século XIX, na perspectiva de uma sociedade mais justa e igualitária, com base socialista, essa forma de organização do trabalho tem sido adotada (e adaptada) pelo movimento da Economia Solidária após o contexto de crise instaurado por volta da década de 1970. O caráter voluntário da adesão aos empreendimentos coletivos fica comprometido em contextos de crise econômica, nos quais as possibilidades de ocupação são reduzidas. Deste modo, grande parte das pessoas acaba ingressando nos empreendimentos alheias ao seu projeto ideológico. A proposta desta pesquisa é sistematizar informações acerca da rotatividade de sócios em uma cooperativa de trabalho, com dez anos de existência, 327 sócios e 271 ex-sócios. A falta de um quadro estável de sócios pode conferir ao empreendimento um caráter de trabalho paliativo e lhe trazer uma série de problemas. Por meio de análises documentais e de entrevistas com atuais e ex-cooperados, analisou-se variáveis que poderiam estar relacionadas ao alto índice de rotatividade de sócios. O pouco tempo de permanência como sócios na cooperativa e a preferência pelo trabalho com relação de emprego representaram uma influência significativa na questão da alta rotatividade. Com base na pesquisa, foram ainda indicados alguns fatores que poderiam auxiliar na permanência do sócio na cooperativa por um tempo prolongado, durante o qual possa se envolver mais ativamente e absorver melhor a proposta do empreendimento / It is observed, on the current context of capitalist society, the manifestation of a growing scale of cooperatives enterprises based on self-management. Emerged and developed on labour movement in the mid-nineteenth century, on a perspective of fairest and more egalitarian society, with socialist base, this kind of working organization has been adopted (and adapted) by the movement of Social Economy after the crises circumstance around the decade of 1970. The voluntary character of adhesion to collective enterprises becomes implicated on economics’ crises context, on which the possibilities of occupations are reduced. Therefore, a large number of people join enterprises inattentive to their ideological project. The purpose of this research is to systematize information about the rotating of members on a worker cooperative, which has ten years of existence, 327 members and 271 ex-members. The lack of a stable working staff members can confer to the cooperative enterprise a palliative working character, bringing to it series of problems. Through documental analyses and interview with the actual and ex-members, it was observed variables that could be related to the high rate of rotating of members. The little time of permanence as members in a cooperative and the preference to the jobs which have an employ bond represent a significant influence on the rotating of members. According to the research, it was indicated some factors that could support the permanence of the members on the enterprises for a prolonged period of time, in which they could get more actively involved and absorb in a better way the proposal of the enterprises

Orientador: Osvaldir Pereira Taranto / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-06T05:10:47Z (GMT). No. of bitstreams: 1 Ribeiro_MarinadosSantos_M.pdf: 1906759 bytes, checksum: 068fcf7b154ad2dedadfc296efb7fbde (MD5) Previous issue date: 2005 / Resumo: O leito fluidizado pulsado rotativo (LFPR) tem sido estudado como uma alternativa para a fluidização de materiais que são difíceis de processar em leito fluidizado convencional (LFC). O LFPR é um leito fluidizado convencional modificado pela adição de um disco rotativo com uma abertura 60º abaixo do distribuidor. O disco rotativo assegura uma alimentação cíclica do gás no leito, fornecendo uma força extra para fluidizar as partículas. Tal característica torna o LFPR atrativo para o uso no processo de secagem, pois realça a transferência de calor e massa. No entanto, a freqüência da pulsação do gás no interior do leito depende da freqüência de rotação do disco. O objetivo deste trabalho foi estudar o comportamento fluidodinâmico de partículas secas e úmidas em um LFPR e compará-lo com os resultados obtidos em um LFC. As partículas selecionadas para o estudo foram celulose microcristalina e ácido adípico, e os parâmetros estudados foram: a carga da partícula, a freqüência de rotação do disco e o teor de umidade inicial. Verificou-se que em freqüência da rotação do disco baixa, jorros alternados se formaram, alternado com as regiões de leito fixo. Quando a freqüência da rotação do disco era elevada, o sistema todo fluidizou de uma maneira similar a um leito fluidizado convencional. Constatou-se que pode-se empregar o LFPR para processar materiais que apresentam características coesivas em condições inviáveis em LFC. A velocidade mínima de fluidização para o LFPR foi menor do que a obtida para o LFC, o que evidencia as condições mais fáceis de fluidização no primeiro equipamento e sua aplicabilidade ao processo de secagem / Abstract: The rotating-pulsed fluidized bed (RPFB) has been studied as an alternative for fluidization of materials that are difficult to operate in the Conventional Fluidized Bed (CFB). The RPFB apparatus is a conventional fluidized bed modified by the addition of a rotating plate with a 60º opening just below the distributor. The rotating plate insures a cyclic feed of the fluidizing gas into the bed, providing an extra force to fluidize the particles. This characteristics becomes the RPFB attractive for use in drying process, enhancing heat and mass transfer. In this way, the frequency of pulsed gas purges in the bottom of the bed depends upon the frequency of the rotating disk. The objective of this present work was to study the fluid dynamic behavior of both dry and moist particulate samples in a RPFB and compare with the results from a CFB. Selected samples were microcrystalline cellulose and adipic acid. The parameters used for the study were: particle load, disc rotation frequency and initial sample moisture content. It was possible to verify that when the disk rotation frequency was low, rotating spouts were formed, alternated with fixed bed regions. When disk rotation frequency was high, the total system was fluidized in a manner similar to a conventional fluidized bed. It was observed the RPFB can be used to material with cohesive characteristics, this conditions is not usual to CFB. The minimum fluidization velocity for the RPFB was lower than that for the CFB, which evidences the easier fluidization conditions in the first apparatus and its applicability to drying process / Mestrado / Engenharia de Processos / Mestre em Engenharia Química

Orientador: Katia Lucchesi Cavalca / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-08T21:19:55Z (GMT). No. of bitstreams: 1 Escobar_RobertoLuiz_M.pdf: 2961640 bytes, checksum: 516985920427d6083c04c1c5a22d6470 (MD5) Previous issue date: 2007 / Resumo: Os sistemas mecânicos são projetados para desempenhar funções específicas, e por essa razão as suas funções devem ser medidas para garantir seu desempenho dentro de uma certa precisão ou tolerância. A grande complexidade em se projetar e analisar novos projetos é a inserção de novas tecnologias, que envolvem aspectos multidisciplinares. Assim, o desenvolvimento e melhoria de projetos e produtos colocam o engenheiro projetista frente às diversas fontes de variabilidade, como por exemplo, as propriedades dos materiais, condições operacionais e ambientais e incertezas nas suposições feitas sobre seu funcionamento. Em termos de modelagem matemática, as aproximações inerentes e hipóteses feitas durante a concepção do sistema, conduzem normalmente a diferentes respostas obtidas através de simulações e/ou medidas experimentais. Dessa forma, em uma fase anterior à modelagem matemática,durante a concepção do sistema ou produto, as aplicações de ferramentas estatísticas e métodos de otimização podem fornecer estimativas sobre faixas de valores ou valores ótimos para parâmetros significativos de projeto, dentro do espaço experimental estudado. Esse tipo de abordagem estatística teve sua fundamentação teórica durante as décadas de 20 e 30 por Fisher, com a aplicação da teoria estatística sob diversos aspectos, como por exemplo: testes de hipóteses, estimativa de parâmetros, seleção de modelos, planejamento experimental e, mais tarde, no controle e melhoria de processos e produtos. Assim, este trabalho propõe um procedimento de estudo e otimização, integrando a teoria de planejamento experimental, a metodologia da superfície de resposta e otimização multi-objetivos através de algoritmos genéticos, para se obter a otimização dos parâmetros de projeto de componentes mecânicos. Em específico, foram utilizados dados de um sistema rotor-mancal e o estudo implica em minimizar as amplitudes no domínio da freqüência. Outro objetivo deste trabalho, foi desenvolver um programa para otimização multi-objetivos através de algoritmos genéticos / Abstract: The mechanical systems are designed to be applied to any specific situations, and in this waytheir features should be measured to guarantee confidence to the systems. Their development and analysis expose the designer to a series of unknown parameters from several sources such as material properties, environmental and operational conditions. In terms of mathematical modeling, the inherent approximation and hypotheses made during system conception lead to different responses obtained by simulations and/or experimental measurements. So, in a previous phase of mathematical modeling, during the design analysis, the application of statistical tools and optimization methods is possible to estimate the values and/or ranges of the critical design parameters inside an experimental space. The connection between optimization and statistical data back at least to the early part of the 20th century and encompasses many aspects of applied and theoretical statistics, including hypothesis testing, parameter estimation, model selection, design of experiments and process and product control. So, this work proposes a link between theory of design of experiments, response surface methodology and multi-objective optimization using genetic algorithms, in order to optimize parameters for mechanical components. This study makes possible to verify the application of multi-objective optimization using genetic algorithms in design parameters and optimize them. A rotor-bearing system was used and amplitude in frequency domain was minimized. An experimental software for multi-objective optimization using genetic algorithm was developed. / Mestrado / Mecanica dos Sólidos e Projeto Mecanico / Mestre em Engenharia Mecânica

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / Este trabalho descreve uma proposiÃÃo mecanÃstica para a deposiÃÃo de cÃdmio em meio de sulfato Ãcido sobre substrato de platina utilizando tÃcnicas eletroquÃmicas. Os estudos de eletrodeposiÃÃo de cÃdmio foram feitas em meio de sulfato de sÃdio 1 mol Lâ1 contendo 10â2 mol Lâ1 de sulfato de cÃdmio, em que o pH das soluÃÃes foi ajustado com Ãcido sulfÃrico PA. O intervalo de pH das soluÃÃes de trabalho foi variado entre 1 e 3. Em todos os meios estudados, as curvas de polarizaÃÃo potenciostÃtica mostraram a formaÃÃo de um patamar difusional que obedece a equaÃÃo de Levich. Os estudos de pH local revelaram a influÃncia do equilÃbrio Ãcidoâbase do Ãon bissulfato com formaÃÃo de compostos de coordenaÃÃo Cd(HSO4)+ no eletrodo de platina. PropÃe-se que o Ãon cÃdmio, associado ao equilÃbrio Ãcidoâbase do Ãon bissulfato, deposita como bissulfato de cÃdmio numa etapa irreversÃvel, e seguida pela deposiÃÃo de cÃdmio metÃlico reversÃvel com a saÃda do Ãon bissulfato, sendo esta Ãltima etapa mais lenta que a primeira. Desse modo, foi calculado um modelo matemÃtico para o mecanismo proposto, sendo realizados estudos qualitativos em relaÃÃo ao comportamento da curva de polarizaÃÃo e do espectro de impedÃncia eletroquÃmica / This work describes a mechanistical proposition for cadmium electrodeposition in acid sulfate medium on platinum substrate using electrochemical techniques. The cadmium electrodeposition studies were carried in sodium sulfate 1 mol Lâ1 medium containing cadmium sulfate 10â2 mol Lâ1, which the pH of the solutions were adjusted with analytical grade sulfuric acid. The pH interval of the work solutions were ranged between 1 and 3. In all studied medium, the potentiostatic polarization curves showed a diffusional plateau which obeys the Levich equation. The interfacial pH studies showed the influence of acidâbase equilibrium of bisulfate ion with the formation of a coordination compound Cd(HSO4)+ in platinum electrode. It is proposed that the cadmium ion associated in acidâbase equilibrium of bisulfate ion, deposits as cadmium bisulfate at an irreversible step, and followed by a reversible metallic deposition of cadmium with the leaving of bisulfate ion, and this step is slower than the first one. Then, a mathematical model was calculated for the mechanism proposed, and qualitative studies were carried regarding to the polarization curve and electrochemical impedance spectroscopy behavior

Es una empresa con más de 12 años de experiencia en el mercado automotriz, dedicada a la comercialización de autos, camiones y buses y a brindar servicio de Post Venta, fundada en Chile en 1986 para representar la distribución de vehículos Hyundai, inicio operaciones en Perú el 02 de mayo del 2003, consiguiendo una gran participación de Hyundai en el mercado peruano, es actualmente la segunda marca más vendida del Perú, según informe de ARAPER a Noviembre de 2013. En Perú las oficinas principales se encuentran en Lima, contamos con 8 sucursales en Lima y 2 en provincias, Trujillo y Piura, combinando estrategias con nuestra Red de Concesionarios a nivel nacional para alcanzar cubrir las expectativas de nuestros clientes. La participación de Hyundai en el mercado sigue creciendo cada año, sus diferentes modelos responden a diferentes exigencias cumpliendo con las variables que el parque automotor requiere: confort, calidad y precio. La sólida red de concesionarios a nivel nacional, la presencia de la marca en el Perú por más de 12 años y la garantía de 3 años o 100 mil Km (vehículos pasajeros), son actores muy importantes para asegurar la inversión de sus clientes y el respaldo de la marca. Actualmente la empresa presenta problemas de demoras en los plazos de entregas que trae como consecuencia sanciones por incumplimiento, problemas de espacio, elevados costo de almacenaje, mal pronóstico de la demanda, restricciones en el sistema, errores de inventario, y principalmente insatisfacción al cliente. Mediante un análisis de la situación y los procesos nos permitió realizar investigaciones para la realización del proyecto, los cuales nos permitieron identificar algunas causas de las cuales son: Gestión de placas únicas de rodaje demasiados largos establecidos por la Asociación Automotriz del Perú aprox. 15 días calendario como mínimo y en la mala operación en el traslado y almacenaje de los automóviles, viendo reflejado también en los altos costos logísticos en la que incurre la empresa. En la presente investigación se pretende identificar los problemas relevantes y mediante propuestas encontrar una solución con el fin de disminuir el plazo de entrega de los automóviles nuevos. It is a company with over 12 years experience in the automotive market, dedicated to the marketing of cars, trucks and buses and providing after sales service, founded in Chile in 1986 to represent the distribution of Hyundai vehicles, began operations in Peru May 2, 2003, achieving a great participation of Hyundai in the Peruvian market, is currently the second best-selling brand of Peru, according to a November report Araper 2013. In Peru's main offices are in Lima, we have 8 branches in Lima and 2 in provinces, Trujillo and Piura, combining strategies with our dealer network nationwide to achieve meet the expectations of our customers. Hyundai's participation in the market continues to grow every year, different models respond to different requirements in compliance with the fleet variables required: comfort, quality and price. The strong network of dealers nationwide, the brand presence in Peru for over 12 years and 3 year warranty or 100,000 kilometers (passenger vehicles) are very important players to ensure customer investment and support the brand. Currently the company has problems of delays in delivery times which results in sanctions for non-space problems, high storage costs, poor demand forecasting, restrictions on the system, inventory errors, and especially customer dissatisfaction. Through an analysis of the situation and processes allowed us to conduct research for the project, which allowed us to identify some causes of which are: Management of unique shooting too long established by the Automotive Association of Peru plates approx. At least 15 calendar days and in bad operation in the transfer and storage of cars, watching also reflected in the high logistics costs incurred by the company. In this research it is to identify relevant problems and find a solution through proposals in order to reduce the delivery of new cars.