912 resultados para HIGH-VOLTAGE AND HIGH-CURRENT
Resumo:
The reality of the current international order makes it imperative that a just and effective climate regime balance the historical responsibility of developed countries with the increasing absolute emissions from many developing nations. In this short outlook article, key pillars are proposed for a new international climate architecture that envisions replacing the current annex system with two new annexes –Annex α, for countries with high current emissions and historically high emissions, and Annex β, for countries with high current emissions and historically low emissions. Countries in both annexes would implement legally binding targets under this framework. Additionally, this proposal includes tweaks and revisions to funding and technology transfer mechanisms to correct for weaknesses and inequities under the current Kyoto architecture. The proposed framework stems from a belief that a top-down, international approach to climate policy remains the most effective for ensuring environmental integrity. Given the slow rate of institutional learning, reforming and improving the current system is held as a more efficient course of action than abandoning the progress already achieved. It is argued that the proposed framework effectively accommodates key equity, environmental integrity and political feasibility concerns.
Resumo:
Flow injection analysis (FIA) using a carbon film sensor for amperometric detection was explored for ambroxol analysis in pharmaceutical formulations. The specially designed flow cell designed in the lab generated sharp and reproducible current peaks, with a wide linear dynamic range from 5 x 10(-7) to 3.5 x 10(-4) mol L-1, in 0.1 mol L-1 sulfuric acid electrolyte, as well as high sensitivity, 0.110 A mol(-1) L cm(-2) at the optimized flow rate. A detection limit of 7.6 x 10(-8) mol L-1 and a sampling frequency of 50 determinations per hour were achieved, employing injected volumes of 100 mu L and a flow rate of 2.0 mL min(-1). The repeatability, expressed as R.S.D. for successive and alternated injections of 6.0 x 10(-6) and 6.0 x 10(-5) mol L-1 ambroxol solutions, was 3.0 and 1.5%, respectively, without any noticeable memory effect between injections. The proposed method was applied to the analysis of ambroxol in pharmaceutical samples and the results obtained were compared with UV spectrophotometric and acid-base titrimetric methods. Good agreement between the results utilizing the three methods and the labeled values was achieved, corroborating the good performance of the proposed electrochemical methodology for ambroxol analysis. (C) 2008 Elsevier B.V. All rights reserved.
Resumo:
Flow injection analysis (FIA) with amperometric detection was employed for the quantification of N-acetylcysteine (NAC) in pharmaceutical formulations, utilizing an ordinary pyrolytic graphite (OPG) electrode modified with cobalt phthalocyanine (CoPc). Cyclic voltammetry was used in preliminary studies to establish the best conditions for NAC analysis. In FIA-amperometric experiments the OPG-CoPc electrode exhibited sharp and reproducible current peaks over a wide linear working range (5.0 x 10(-5)-1.0 x 10(-3) mol L(-1)) in 0.1 mol L(-1) NaOH solution. High sensitivity (130 mA mol(-1) cm(2)) and a low detection limit (9.0 x 10(-7) mol L(-1)) were achieved using the sensor. The repeatability (R.S.D.%) for 13 successive flow injections of a solution containing 5.0 x 10(-4) mol L(-1) NAC was 1.1%. The new procedure was applied in analyses of commercial pharmaceutical products and the results were in excellent agreement with those obtained using the official titrimetric method. The proposed amperometric method is highly suitable for quality control analyses of NAC in pharmaceuticals since it is rapid, precise and requires much less work than the recommended titrimetric method. (C) 2010 Elsevier B.V. All rights reserved.
Resumo:
Biological rhythms are regulated by homeostatic mechanisms that assure that physiological clocks function reliably independent of temperature changes in the environment. Temperature compensation, the independence of the oscillatory period on temperature, is known to play a central role in many biological rhythms, but it is rather rare in chemical oscillators. We study the influence of temperature on the oscillatory dynamics during the catalytic oxidation of formic acid on a polycrystalline platinum electrode. The experiments are performed at five temperatures from 5 to 25 degrees C, and the oscillations are studied under galvanostatic control. Under oscillatory conditions, only non-Arrhenius behavior is observed. Overcompensation with temperature coefficient (q(10), defined as the ratio between the rate constants at temperature T + 10 degrees C and at T) < I is found in most cases, except that temperature compensation with q(10) approximate to I predominates at high applied currents. The behavior of the period and the amplitude result from a complex interplay between temperature and applied current or, equivalently, the distance from thermodynamic equilibrium. High, positive apparent activation energies were obtained under voltammetric, nonoscillatory conditions, which implies that the non-Arrhenius behavior observed under oscillatory conditions results from the interplay among reaction steps rather than, from a weak temperature dependence of the individual steps.
Resumo:
We report in this paper the occurrence of potential oscillations in a proton exchange membrane fuel cell (PEMFC) with a Pd-Pt/C anode, fed with H(2)/100 ppm CO, and operated at 30 degrees C. We demonstrate that the use of Pd-Pt/C anode enables the emergence of dynamic instabilities in a PEMFC. Oscillations are characterized by the presence of very high oscillation amplitude, ca. 0.8 V. which is almost twice that observed in a PEMFC with a Pt-Ru/C anode under similar conditions. The effects of the H(2)/CO flow rate and cell current density on the oscillatory dynamics were investigated and the mechanism rationalized in terms of the CO oxidation and adsorption processes. We also discuss the fundamental aspects concerning the operation of a PEMFC under oscillatory regime in terms of the benefit resulting from the higher average power output. (c) 2010 Elsevier B.V. All rights reserved.
Resumo:
Citrus sudden death (CSD) is a new disease of sweet orange and mandarin trees grafted on Rangpur lime and Citrus volkameriana rootstocks. It was first seen in Brazil in 1999, and has since been detected in more than four million trees. The CSD causal agent is unknown and the current hypothesis involves a virus similar to Citrus tristeza virus or a new virus named Citrus sudden death-associated virus. CSD symptoms include generalized foliar discoloration, defoliation and root death, and, in most cases, it can cause tree death. One of the unique characteristics of CSD disease is the presence of a yellow stain in the rootstock bark near the bud union. This region also undergoes profound anatomical changes. In this study, we analyse the metabolic disorder caused by CSD in the bark of sweet orange grafted on Rangpur lime by nuclear magnetic resonance (NMR) spectroscopy and imaging. The imaging results show the presence of a large amount of non-functional phloem in the rootstock bark of affected plants. The spectroscopic analysis shows a high content of triacylglyceride and sucrose, which may be related to phloem blockage close to the bud union. We also propose that, without knowing the causal CSD agent, the determination of oil content in rootstock bark by low-resolution NMR can be used as a complementary method for CSD diagnosis, screening about 300 samples per hour.
Resumo:
The aim of this paper was to discover the functions and workings of personal networks and their advantages for self-employed sound designers and producers whose focus was upon the moving image (film, advertising, tv, etc). Investigations on how entrepreneurs develop their networks were made, as well as inquiries on how these networks are used for generating work. Another important aspect perused was whether or not the networks are dependent on specific geographical locations in order to function. A case study and comparative analysis was undertaken, based upon three qualitative interviews with entrepreneurs whose operations shared several similar characteristics. The results pointed out the importance of constantly making new contacts, and maintaining and managing current ones. There was no evidence that traditional marketing strategies or advertising were used by the interviewees. New commissions were often gained from former clients or acquaintances, or through referrals from them. There are definite advantages to having one's business in the geographical area where one's contacts exist. This also makes it easier to keep up these contacts for future prospects. However, it is very feasible to take on contracts, do the job, and to deliver work to clients in far away locations, due to the high speed internet connections available today.Målet med denna uppsats var att ta reda på hur personliga nätverk fungerar och verkar till fördel för egenföretagande ljuddesigers för rörlig bild (Film, Reklam och tv etc.). Hur entreprenörerna utvecklar nätverken utforskades, även hur de används för att generera arbete samt om nätverken bör vara lokaliserade på en speciell plats för att fungera. En fallstudie och komparativ analys utfördes, baserad på tre kvalitativa intervjuer med entreprenörer vars verksamheter liknade varandra på flera plan. Resultatet påvisade vikten av att hela tiden skapa nya kontakter och underhålla befintliga sådana. Inget tydde på att traditionell marknadsföring eller reklam används. Nya uppdrag uppkommer oftast genom tidigare kunder, kontakter eller rekommendationer från dessa. Det finns klara fördelar med att bedriva sin verksamhet i det område där kontakterna finns och det är även lättare att underhålla dem i dessa fall. Det är dock fullt möjligt att åta sig, utföra och leverera uppdrag för befintliga kontakter på långt håll tack vare dagens snabba internetuppkopplingar.
Resumo:
Bakgrund: Uppkomsten av vårdrelaterade infektioner (VRI) är ett globalt problem. Den vanligaste smittvägen är via personalens händer. Bra handhygien är väsentligt för att minska VRI. Med bättre följsamhet till handhygien kan uppkomsten av VRI minskas, därför har forskning om följsamhet till handhygien och faktorer som inverkar, stort betydelse. Syfte: Syftet var att sammanställa och beskriva aktuell forskning om sjuksköterskors följsamhet till handhygien och vilka faktorer främjar respektive hindrar följsamheten till handhygien. Metod: En litteraturöversikt som baserades på artiklar publicerade de senaste fem åren, från länder som följer Världshälsoorganisationens (WHO) handhygieniska riktlinjer. Sexton artiklar valdes efter kvalitetsgranskning för analys och beskrivning. Artiklarna bearbetades med innehållsanalys. Resultat: Sjuksköterskors följsamhet till handhygien var låg. Följande främjande faktorer identifierades: handhygien efter patientkontakt, materialtillgång, förebilder, utbildning, verbala och visuella påminnelser, positiva individuella attityder, kvinnlig könstillhörighet, yrkesgrupp, specialitet, patientens skydd, arbetskultur och samhällets inställning till handhygien. Följande hindrande faktorer identifierades: hög arbetsbelastning, bristande utbildning, kunskapsbrist, individuella attityder, hudpåverkan, materialtillgång, arbetskultur och samhällets inställning till handhygien, manlig könstillhörighet, yrkesgrupp, specialitet. Slutsats: Enligt resultat rekommenderas: samspelet med kollegor och patienter, stöd av teamarbete ledare, förebilder, materialtillgång, utbildning, påminnelser, intervention med tillgång till information, stöd, resurser och möjligheter för regelbunden kunskapsuppföljning, motivera till handhygien före patientkontakt, involvera patienter.
Resumo:
Highly indebted countries, particularly the Latin American ones, presented dismal economic outcomes in the 1990s, which are the consequence of the ‘growth cum foreign savings strategy’, or the Second Washington Consensus. Coupled with liberalization of international financial flows, such strategy, which did not make part of the first consensus, led the countries, in the wave of a new world wide capital flow cycle, to high current account deficits and increase in foreign debt, ignoring the solvency constraint and the debt threshold. In practical terms it involved overvalued currencies (low exchange rates) and high interest rates; in policy terms, the attempt to control de budget deficit while the current account deficit was ignored. The paradoxical consequence was the adoption by highly indebted countries of ‘exchange rate populism’, a less obvious but more dangerous form of economic populism.
Resumo:
O objetivo deste artigo é verificar a influência de variáveis políticas na determinação da taxa de câmbio em quatro países latino-americanos que conviveram com elevada inflação e déficit em Transações Correntes nas décadas de setenta e oitenta. Estudos empíricos já haviam demonstrado a influência das eleições. Nenhum, porém, havia incorporado a estrutura de decisão do Executivo e Legislativo neste processo. Só foi possível incorporar o regime político (Autoritário/Democrático) e a divisão de poder no Legislativo de todos os países num modelo standard de taxa de câmbio porque utilizamos a técnica de painel. Obtivemos os seguintes resultados: países classificados como Autoritários apresentaram uma taxa de câmbio mais valorizada e Legislativos mais fragmentados apresentaram uma taxa de câmbio mais desvalorizada. Vimos este último resultado com desconfiança uma vez que, entre os países da amostra, o regime Autoritário era, em alguns casos, uma ditadura militar e o Legislativo pouco intervia nas decisões. Interagimos o regime político com fragmentação e percebemos que o efeito da classificação do regime predomina. No caso, se existir um regime Autoritário, o câmbio resultante da interação ainda será valorizado. A divisão de poder no Legislativo apenas provoca uma redução no impacto da valorização.
Resumo:
O setor de mármore e granito do Espírito Santo constitui-se no maior pala industrial brasileiro do setor, sendo líder na comercialização dos produtos dele derivados, tanto no mercado interno como externo. Apesar do crescimento significativo observado nas exportações nos últimos anos, em peso e valor, bem como de estar comercializando a cada ano, produtos com maior valor agregado, convive com problemas de naturezas diversas, os quais se solucionados, proporcionarão maior participação nos mercados em que atua. Em termos sociais o reflexo será imediato, pois com os investimentos decorrentes, haverá geração de quantidade considerável de novos postos de trabalho, visto que trata-se de atividade altamente geradora de empregos. Por outro lado, os benefícios decorrentes do aumento de produção, proporcionarão a geração de renda e divisas para o país. Entre os problemas a serem solucionados encontra-se o alto índice de acidentes ocorridos no setor, conforme mostram as estatísticas apresentadas na presente dissertação. O estabelecimento de ações que visem a redução desses índices constitui o objetivo deste trabalho, tendo como meta principal, proporcionar a preservação da saú- de e segurança do trabalhador, e a implementação das mesmas, trarão como conseqüência natural, ganhos de produtividade e redução de custos, na medida que os acidentes implicam no surgimento de custos adicionais. A globalização da economia e a política econômica vigente no país, impuseram aos setores econô- micos uma competição cada vez mais acirrada, obrigando-os a buscarem alternativas que os viabilizem. A redução de custos por meio da prevenção de acidentes Vll no trabalho se constitui numa das alternativas. Esta dissertação, apresenta a partir de diagnóstico realizado nas diversas atividades do setor, ou seja, extração, serragem e beneficiamento, as tendências das ocorrências dos acidentes, caso não haja no futuro, nenhum tipo de intervenção. É estabelecida uma comparação com os demais setores da economia capixaba, através das respectivas curvas de tendências, na qual fica caracterizada a gravidade da situação e a importância da redução dos acidentes no setor de mármore e granito do Espírito Santo. Em fun- ção da dimensão com que o problema se apresenta, surge a necessidade de intervenções, as quais são classificadas como imediatas e de médio prazo. A observância à legislação vigente, representada pelas Normas Regulamentadoras, proporcionará maior segurança aos trabalhadores, possibilitando a esses, exercer suas atividades em ambiente onde os riscos referentes a lesões, com ou sem afastamentos, e morte, sejam minimizados, na medida que eles são inerentes ao setor e sempre existirão. Como metodologia é utilizado pesquisa de campo, através de entrevistas com empresários, trabalhadores, sindicatos patronal e dos trabalhadores, representantes da DRT e INSS, com as quais é possível o levantamento estatístico, consultas a revistas especializadas, jornais, Internet, disserta- ções e Normas Regulamentadoras. É ainda utilizado referencial teórico de diversos autores, na busca de dar sustentação conceitual ao tema abordado. Como resultado, é apresentado proposta que se constitui em uma série de ações a serem implementadas, para o atingimento do objetivo procurado.
Resumo:
O mundo está passando por grandes mudanças que vêm afetando as esferas sociais, tecnológicas, empresariais e mentais. As empresas têm sido ameaçadas por diversos fatores como rapidez no lançamento de novos produtos, interferência dos governos, clientes cada vez mais conscientes e exigentes, aumento da concorrência, globalização e o surgimento constante de novas tecnologias. Essas mudanças exigem das empresas uma estrutura mais flexível capaz de absorver as rápidas necessidades do ambiente, e o formato atual não tem se mostrado adequado para vencer estes desafios. Nesse contexto, a gestão baseada em processos tem se mostrado promissora ao ser incorporada nas principais tecnologias de gestão como BSC, NBR ISO 9000, gestão de custos com ABC, entre outras. Como toda nova abordagem, as tecnologias (ou modelos) baseadas em processos sofrem de vários problemas, sendo alguns já conhecidos, como resistência às mudanças, falta de preparo e apoio insuficiente da alta direção. Os estudos desses fatores são incipientes e em sua maioria não tratam de seus impactos em empresas públicas. Esse trabalho tem como objetivo justamente identificar esses fatores na literatura (teoria e casos de estudo) e confrontá-los com aqueles encontrados em uma empresa pública (estudo de caso), analisando sua pertinência. Os resultados encontrados, além de confirmarem os fatores, sugerem que a sua utilização, na forma de um checklist, podem beneficiar as empresas na prevenção, redução ou eliminação de problemas que impactam ou inviabilizam um projeto.
Resumo:
As reformas administrativas ocorridas no Brasil e no mundo, levaram a sociedade a repensar a formação dos dirigentes públicos, em consequência, escolas de governo foram desenvolvidas com o intuito de preparar gestores públicos para a modernização do Estado e para as novas tendências em gestão pública. No entanto, o que se observa é que esta nomenclatura vem sendo utilizada tanto para as escolas que formam altos dirigentes generalistas e capazes de criar novas políticas, quanto para a capacitação e treinamento dos servidores que compõem o quadro atual das organizações públicas e operacionalizam as políticas. O que se espera, portanto, é que estes núcleos de saber administrativo público sejam capazes de gerar uma massa crítica de pensadores sobre a política e a gestão, fortalecendo assim o desenvolvimento do conhecimento sobre o tema e a difusão através de redes para outras Instituições.
Resumo:
Over time the Physical Education on IFRN has considered the sport as the only possibility of pedagogical action. In the purpose of investigating the aspects that determine this condition, this study aimed the context of physical education within the institutional framework and its current perspectives in the process of institutional transformation. In this sense, were addressed the following study questions: What political pedagogical aspects that influenced the context of Physical Education on IFRN and how the pedagogical experience on Mossoro s campus incorporated the perspectives of curricular proposals transformation for the High School and the theoretical changes of the Brazilian Physical Education. Methodologically the work was based on a qualitative approach characterized as a descriptive- comparative research. The technique of discourse analysis was employed in the speech of research collaborators having as categories of analysis the professional activities time in the institution; The ratio of official use of the assumptions to the pedagogical practice of Physical Education in IFRN; The sport in the education process of students and The Prospects of Physical Education in the current configuration of IFRN. The data analysis allowed us to infer that the theoretical methodology of pedagogical practice of Physical Education in IFRN need to be reformulated and that it is necessary a contextualization with the curricular principles of the political institutional pedagogical project and with the Curriculum Guidelines for Secondary Education. The teaching experience developed in the Mossoro s Campus was contextualized with the national curriculum guidelines for secondary education and the theoretical changes of the Brazilian Physical Education. We conclude that it is necessary a collective action of the group of teachers to transform the educational profile of Physical Education of IFRN, beyond the institutional support to be able to consolidate the physical education curriculum component in the current dimensions of society, human being, education, science, technology and work, proposed by the philosophical principles and epistemological political project of IFRN educational
Resumo:
This work describes the study, the analysis, the project methodology and the constructive details of a high frequency DC/AC resonant series converter using sequential commutation techniques for the excitation of an inductive coupled thermal plasma torch. The aim of this thesis is to show the new modulation technique potentialities and to present a technological option for the high-frequency electronic power converters development. The resonant converter operates at 50 kW output power under a 400 kHz frequency and it is constituted by inverter cells using ultra-fast IGBT devices. In order to minimize the turn-off losses, the inverter cells operates in a ZVS mode referred by a modified PLL loop that maintains this condition stable, despite the load variations. The sequential pulse gating command strategy used it allows to operate the IGBT devices on its maximum power limits using the derating and destressing current scheme, as well as it propitiates a frequency multiplication of the inverters set. The output converter is connected to a series resonant circuit constituted by the applicator ICTP torch, a compensation capacitor and an impedance matching RF transformer. At the final, are presented the experimental results and the many tests achieved in laboratory as form to validate the proposed new technique