MOURA uma empresa que enorgulhece o Brasil, com 66 anos de historia lider do setor de baterias AUTOMOTIVAS,INDUSTRIAIS,ESTACIONARIAS,SOLAR

 

https://picasion.com/
Tive a satisfação de visitar a Empresa Moura genuinamente Brasileira junto com meus colegas peruanos Sr. Rodolfo Araujo Diretor da empresa peruana INTERSAC junto com seu filho Edson Araujo e o Sr. Cesar Quintero Gerente de Moura na Colombia,devo expresar meu agradecimento especial a Srta.Debora Daiana Silva Gerente Comercial LATAM | Gestão de Contas | Abertura de Mercado | Expansão de Negócios | Planejamento Estratégico | Liderança e Formação de Equipes,realmente o que mais me impresionou foi sua organização,seu Instituto de Pesquisa e Desenvolvimento,seu proceso de produção e Controle de Qualidade,devo resaltar seu Programa Social com Instituto Moura de Formação Tecnica de jovem talentos de jovens da comunidade da Cidade Bela Jardim,tem cursos de Robótica,Matemáticas,Ciências de \Computação e aulas de musica,e um Cinema,todos estes serviços são totalmente gratuitos, alem de isso continuan expandiendo seus investimentos no desenvolvimento de novas aplicações no setor de energia como os automoveis elétricos,desejo que o sucesso continue.

Muito Obrigado Moura.

리튬 배터리의 화재 및 폭발 위험성에 관한 연구 A Study on the Explosion and Fire Risk of the Lithium Battery-Author Sang-Bo Sim- Hoseo University

리튬 배터리의 화재 및 폭발 위험성에 관한 연구 A Study on the Explosion and Fire Risk of the Lithium Battery-Author Sang-Bo Sim- Hoseo University

ABSTRACT 

Due to recent development of IT technology, information level of Korea is said to be the world-best. Thus mobile devices such as cell phones, notebook, and tablet PC that could be used without limitations are trending. Along the trend, high energy high density secondary batteries used as the power source for portable devices are also in the spotlight, and among them Lithium battery demand is rising. Generally a Lithium battery should be certified with KS C 8541 (Lithium secondary battery rule) in order to be on the market. However, battery accidents are growing in number and people are raising questions about the safety of the batteries. Certified Lithium battery’s safety is guaranteed within normal state, but at abnormal states such as damage to protective circuit, the danger rises due to elimination of minimum protection. Recent studies regarding Lithium batteries only measured ignition status for flammable gas, but did not provide detailed analysis. Also, risk analysis according to battery capacity and comparative analysis between the two representative batteries, Lithium Polymer battery and Lithium Ion battery are rarely carried out. Also, research about general danger of Lithium batteries such as ignition at high temperature environment is incomplete. This study selected five types of Li-Polymer batteries and three types of Li-Ion batteries of different capacity in order to analyze ignition and fire danger according to usage environment. The results are as following. 1. We designed an ignition circuit using IEC type spark ignition test apparatus based on KS C IEC 60079-11 standard in order to measure the explosion hazard of Lithium battery spark discharge. Through measuring the ignition limit of methane, propane, ethylene, and helium, the result showed that gas with higher danger showed more explosion to less number of battery connection. Also, batteries with not Protection Circuit Module (PCM) exploded more often during connection with battery compared with batteries that had protection circuits. 2. An experiment was conduction using a pyrostat based on UL 1642 and KS C 8541 standard in order to measure Lithium battery’s explosion danger at high temperature environment. As the result, Li-Polymer batter with pack type external material had higher risk of explosion compared to cap type Li-Ion battery. Li-Polymer battery had 160~170℃ explosion between 1970~2700 seconds, and the explosion occurred for the electrolytes seeped out from the cracked battery pack after swelling due to evaporation. On the other hand, Li-Ion battery had 176~197℃ explosion between 3000~3800 seconds caused by vaporized electrolyte increasing the pressure within the battery and protruding to the vulnerable positive (+) end. 3. Short circuit was designed in order to measure the temperature increase according to the short circuit current. For batteries with protection circuit, there was no temperature change caused by short circuit current due to current limitation. However, for batteries with no protection circuit, 30.7~35.6A of maximum short circuit current was produced. For Li-Polymer battery, the current fell until 3.9~12.7A after the maximum short circuit current, but increased again to 5.5~17.8A, showing two-step curve pattern. The maximum temperature was 125℃. For Li-Ion battery, the maximum short circuit current fell steeply to 1.3A and decreased steadily, showing a single step curve pattern. It is because the PTC thermistor embed inside limited the flowing current. The maximum temperature was 95℃. Thus in order to minimize the danger of Lithium battery explosion, the Lithium battery connection number and discharge characteristics should be considered when used at environment with flammable gas. And swelling and explosive characteristics should be considered when using Li-Polymer and Li-Ion batteries at high temperature environment. Also, to prevent hazards caused by mistakes and abnormal statues, a dual safety device of protection circuits are recommended.

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Задачник по физике. Чертов А.Г., Воробьев А.А. -Problem in physics. Chertov A.G., Vorobiev A.A. -

 

-Problem in physics. Chertov A.G., Vorobiev A.A. 

 The problem book was compiled in accordance with the current syllabus for the physics course for college students. Each section includes a sufficient number of tasks, the difficulty of which increases with increasing serial number. At the beginning of each paragraph, basic laws and formulas are given, and examples of solving typical problems are given. At the end of the book, answers to all problems are given. The 7th edition (6th - 1997) includes more than 150 new problems and examples, the theoretical part of each section has been significantly expanded, and the necessary corrections have been made. For students of higher technical educational institutions.

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Collected Papers Of P. L. Kapitza -PRIMER VOLUME-TOMO i

 

Collected Papers of P. L. Kapitza, Volume I 

Compiles the scientific papers written between 1916 and 1934 by Piotr Leonidovich Kapitza, a leading Soviet physicist and Nobel laureate. This book begins by introducing the life and career of P. L. Kapitza, which includes his studies and investigations of nuclear physics, strong magnetic fields, liquefaction, liquid helium, and high-power electronics. Other topics discussed include electron inertia in molecular ampere currents; Koch recording microphotometer; metallic conductivity and its change in a magnetic field; and methods of experimenting in strong magnetic fields. The liquefaction of helium by an adiabatic method; Zeeman and Paschen-Back effects in strong magnetic fields; and theoretical and empirical expressions for the heat transfer are also emphasized in this text. This compilation is a good reference for students and researchers conducting work on the biography and scientific contributions of P. L. Kapitza. 

 Volume 1 here:

https://archive.org/details/collected-papers-of-p.-l.-kapitza-volume-1

ДОВУДОВ Сарфароз Умедович ПОВЫШЕНИЕ ЭНЕРГЕТИЧЕСКОЙ ЭФФЕКТИВНОСТИ АВТОМАТИЗИРОВАННЫХ ЭЛЕКТРОПРИВОДОВ НА ОСНОВЕ ИСПОЛЬЗОВАНИЯ ЧАСТОТНО-ИМПУЛЬСНОЙ МОДУЛЯЦИ------DOVUDOV Sarfaroz Umedovich AUMENTANDO A EFICIÊNCIA ENERGÉTICA ACIONAMENTOS ELÉTRICOS AUTOMATIZADOS BASEADOS EM USANDO MODULAÇÃO DE FREQUÊNCIA DE PULSO

INTRODUÇÃO 

Relevância do tema de pesquisa da dissertação. Acionamentos elétricos automatizados (DEA) de corrente contínua e alternada constituem uma parte importante dos equipamentos industriais modernos para sistemas de produção e transporte [1-3]. Ao mesmo tempo, a qualidade do controle e o desempenho energético dos acionamentos elétricos dependem significativamente dos algoritmos de controle utilizados. Atualmente, o método de controle mais popular para DEAs de corrente contínua e alternada pode ser considerado um método de controle usando modulação por largura de pulso (PWM), que pode fornecer os parâmetros necessários para controlar a velocidade angular de motores elétricos [3-5]. Tais tipos de PWM provaram-se tecnicamente bem, como modulação única, PWM senoidal, PWM com introdução de um terceiro harmônico, etc. [4-34]. Uma contribuição significativa para o desenvolvimento da teoria dos sistemas de controle pulsado para motores elétricos de corrente contínua e alternada foi feita pelos trabalhos científicos de G.A. Belova, O.G. Bulatova, A.I. Tsarenko, B.Yu. Vasilyeva, B.I. Firago, K, Hasse, F. Blaschke, SR. Bowes, D. Holliday, S. Grewal e outros pesquisadores. Os fundamentos metodológicos da pesquisa na área de controle de motores elétricos são estabelecidos nos trabalhos de A.G. Ivanova, A.S. Sandler, R.T. Schreiner, S.G. Alemão-Galkin, Yu.A. Sabinina, M.P. Kostenko, I. Takahashi, T. Noguchi e outros cientistas [3, 7, 10, 14]. No entanto, o método de controle PWM apresenta uma série de desvantagens em relação à sua eficiência energética: perdas dinâmicas significativas de potência causadas pelos processos de ligar e desligar as chaves semicondutoras do conversor de potência controlado e a eficiência relativamente baixa do conversor PWM - gerenciamento. Aumentando a eficiência energética de conversores semicondutores pulsados ​​de potência (PSCs) para sistemas elétricos automatizados 7 A movimentação de complexos de produção industrial pode ser facilitada pelo uso de modulação de frequência de pulso (PFM) [22, 24, 27, 35, 36]. No entanto, deve-se notar que este método de controle como parte de um DEA ainda não foi totalmente estudado. Este trabalho se dedica a melhorar a eficiência do DEA de complexos produtivos industriais baseados no uso de PFM. O objetivo do estudo é utilizar modulação em frequência de pulso da tensão de alimentação para aumentar a eficiência energética de acionamentos elétricos automatizados com conversores semicondutores pulsados.

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