Potential oscillations in a proton exchange membrane fuel cell with a Pd-Pt/C anode

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.

Use of Photovoltaic on an E-bike? : A Feasibility Study

In recent years the number of bicycles with e-motors has been increased steadily. Within the pedelec – bikes where an e-motor supports the pedaling – a special group of transportation bikes has developed. These bikes have storage boxes in addition to the basic parts of a bike. Due to the space available on top of those boxes it is possible to install a PV system to generate electricity which could be used to recharge the battery of the pedelec. Such a system would lead to grid independent charging of the battery and to the possibility of an increased range of motor support. The feasibility of such a PV system is investigated for a three wheeled pedelec delivered by the company BABBOE NORDIC.The measured data of the electricity generation of this mobile system is compared to the possible electricity generation of a stationary system.To measure the consumption of the pedelec different tracks are covered, and the energy which is necessary to recharge the bike battery is measured using an energy logger. This recharge energy is used as an indirect measure of the electricity consumption. A PV prototype system is installed on the bike. It is a simple PV stand alone system consisting of PV panel, charge controller with MPP tracker and a solar battery. This system has the task to generate as much electricity as possible. The produced PV current and voltage aremeasured and documented using a data logger. Afterwards the average PV power is calculated. To compare the produced electricity of the on-bike system to that of a stationary system, the irradiance on the latter is measured simultaneously. Due to partial shadings on the on-bike PV panel, which are caused by the driver and some other bike parts, the average power output during riding the bike is very low. It is too low to support the motor directly. In case of a similar installation as the PV prototype system and the intention always to park the bike on a sunny spot an on-bike system could generate electricity to at least partly recharge a bike battery during one day. The stationary PV system using the same PV panel could have produced between 1.25 and 8.1 times as much as the on-bike PV system. Even though the investigation is done for a very specific case it can be concluded that anon-bike PV system, using similar components as in the investigation, is not feasible to recharge the battery of a pedelec in an appropriate manner. The biggest barrier is that partial shadings on the PV panel, which can be hardly avoided during operation and parking, result in a significant reduction of generated electricity. Also the installation of the on-bike PV system would lead to increased weight of the whole bike and the need for space which is reducing the storage capacity. To use solar energy for recharging a bike battery an indirect way is giving better results. In this case a stationary PV stand alone system is used which is located in a sunny spot without shadings and adjusted to use the maximum available solar energy. The battery of the bike is charged using the corresponding charger and an inverter which provides AC power using the captured solar energy.

Assessment of PD Speech Anomalies @ Home

Background: Voice processing in real-time is challenging. A drawback of previous work for Hypokinetic Dysarthria (HKD) recognition is the requirement of controlled settings in a laboratory environment. A personal digital assistant (PDA) has been developed for home assessment of PD patients. The PDA offers sound processing capabilities, which allow for developing a module for recognition and quantification HKD. Objective: To compose an algorithm for assessment of PD speech severity in the home environment based on a review synthesis. Methods: A two-tier review methodology is utilized. The first tier focuses on real-time problems in speech detection. In the second tier, acoustics features that are robust to medication changes in Levodopa-responsive patients are investigated for HKD recognition. Keywords such as Hypokinetic Dysarthria , and Speech recognition in real time were used in the search engines. IEEE explorer produced the most useful search hits as compared to Google Scholar, ELIN, EBRARY, PubMed and LIBRIS. Results: Vowel and consonant formants are the most relevant acoustic parameters to reflect PD medication changes. Since relevant speech segments (consonants and vowels) contains minority of speech energy, intelligibility can be improved by amplifying the voice signal using amplitude compression. Pause detection and peak to average power rate calculations for voice segmentation produce rich voice features in real time. Enhancements in voice segmentation can be done by inducing Zero-Crossing rate (ZCR). Consonants have high ZCR whereas vowels have low ZCR. Wavelet transform is found promising for voice analysis since it quantizes non-stationary voice signals over time-series using scale and translation parameters. In this way voice intelligibility in the waveforms can be analyzed in each time frame. Conclusions: This review evaluated HKD recognition algorithms to develop a tool for PD speech home-assessment using modern mobile technology. An algorithm that tackles realtime constraints in HKD recognition based on the review synthesis is proposed. We suggest that speech features may be further processed using wavelet transforms and used with a neural network for detection and quantification of speech anomalies related to PD. Based on this model, patients' speech can be automatically categorized according to UPDRS speech ratings.

Evaluation of a thermally driven heat pump for solar heating and cooling applications

Exploiting solar energy technology for both heating and cooling purposes has the potential of meeting an appreciable portion of the energy demand in buildings throughout the year. By developing an integrated, multi-purpose solar energy system, that can operate all twelve months of the year, a high utilisation factor can be achieved which translates to more economical systems. However, there are still some techno-economic barriers to the general commercialisation and market penetration of such technologies. These are associated with high system and installation costs, significant system complexity, and lack of knowledge of system implementation and expected performance. A sorption heat pump module that can be integrated directly into a solar thermal collector has thus been developed in order to tackle the aforementioned market barriers. This has been designed for the development of cost-effective pre-engineered solar energy system kits that can provide both heating and cooling. This thesis summarises the characterisation studies of the operation of individual sorption modules, sorption module integrated solar collectors and a full solar heating and cooling system employing sorption module integrated collectors. Key performance indicators for the individual sorption modules showed cooling delivery for 6 hours at an average power of 40 W and a temperature lift of 21°C. Upon integration of the sorption modules into a solar collector, measured solar radiation energy to cooling energy conversion efficiencies (solar cooling COP) were between 0.10 and 0.25 with average cooling powers between 90 and 200 W/m2 collector aperture area. Further investigations of the sorption module integrated collectors implementation in a full solar heating and cooling system yielded electrical cooling COP ranging from 1.7 to 12.6 with an average of 10.6 for the test period. Additionally, simulations were performed to determine system energy and cost saving potential for various system sizes over a full year of operation for a 140 m2 single-family dwelling located in Madrid, Spain. Simulations yielded an annual solar fraction of 42% and potential cost savings of €386 per annum for a solar heating and cooling installation employing 20m2 of sorption integrated collectors.

Concentração nos mercados brasileiros de seguros, previdência e capitalização

Os mercados de seguros regulados pela SUSEP apresentaram queda no número de empresas e elevação no índice de concentração de Herfindahl Hirschman. O que parece um quadro preocupante no âmbito da regulação é atenuado pela diminuição do índice de Gini e outros testes de poder de mercado que não indicam que esta queda no número de empresas tenha tido impacto sobre o nível de preços. Assim como esperado a partir da evidência internacional, a concentração é maior nos mercados de seguros de vida do que nos não-vida. Este fato tem reflexo nos preços, que apresentam patamares mais altos nos seguros de vida, indicando diferença mais substancial entre mercados.

Regras monetárias e dinâmica macroeconômica no Brasil: uma abordagem de expectativas racionais

Neste artigo estimamos e simulamos um modelo macroeconômico aberto de expectativas racionais (Batini e Haldane [4]) para a economia brasileira, com o objetivo de identificar as características das regras monetárias ótimas e a dinâmica de curto prazo gerada por elas. Trabalhamos com uma versão forward-Iooking e uma versão backward-Iooking a fim de comparar o desempenho de três parametrizações de regras monetárias, que diferem em relação à variável de inflação: a tradicional regra de Taylor, que se baseia na inflação passada; uma regra que combina inflação e taxa de câmbio real (ver Ball [5]) e uma regra que utiliza previsões de inflação (ver Bank af England [3]). Resolvemos o modelo numericamente e contruímos fronteiras eficientes em relação às variâncias do produto e da infiação por simulações estocásticas, para choques i.i.d. ou correlacionados. Os conjuntos de regras ótimas para as duas versões são qualitativamente distintos. Devido à incerteza quanto ao grau de forward-Iookingness sugerimos a escolha das regras pela soma das funções objetivos nas duas versões. Concluímos que as regras escolhidas com base neste critério têm perdas moderadas em relação às regras ótimas, mas previnem perdas maiores que resultariam da escolha da regra com base na versão errada. Finalmente calculamos funções de resposta a impulso dos dois modelos para algumas regras selecionadas, a fim de avaliar como diferentes regras monetárias alteram a dinâmica de curto prazo dos dois modelos.

O uso de derivativos e o custo de capital total ponderado

O presente artigo tem por objetivo demonstrar como a gestão de derivativos e a participação de capital estrangeiro afetam o custo de capital das empresas. Para essa finalidade o trabalho irá testar como impactam nos custos de capital WACC (Weighted Average Cost of Capital) e TACC (Total Average Cost of Capital), ou custo de capital total. Utilizando uma base de dados construída com dados do Economatica, bem como informações retiradas dos demonstrativos financeiros das empresas, estimaram-se três modelos para explicar quais seriam as variáveis que poderiam impactar o custo de capital das empresas. No primeiro modelo explicou-se o WACC (custo de capital médio ponderado), no segundo, o TACC (custo de capital total) e, no terceiro modelo, explicou-se a diferença entre o WACC e o TACC, quando diferente de zero. No caso do WACC a variável de teste derivativo, que demonstra empresas que possuem hedges de proteção, reduz o custo de capital, entretanto a variável estrangeiro que reflete a presença de capital estrangeiro foi estatisticamente não significativa. Já para o TACC a variável de teste estrangeiro não foi estatisticamente significativa e a variável derivativo não esteve presente. Entende-se que isto ocorre pelo fato de empresas mais conservadoras possuírem menor custo de capital.

O BNDES gera lucro econômico? : utilização da metodologia do EVA® para verificar a criação de valor ao acionista

O objetivo deste trabalho foi verificar se o BNDES, no período entre 2000 e 2011 gerou lucro econômico para o seu principal acionista, o Governo Federal. Foram analisados demonstrativos financeiros e notas explicativas publicadas neste período para obtenção de dados para o cálculo do Valor Econômico Adicionado ou Economic Value added (EVA®). Esta metodologia deduz o custo de todo o capital empregado na empresa do lucro operacional após os impostos. Além disso, utiliza o custo médio ponderado de capital (CMPC) ou Weighted Average Cost of Capital (WACC) como taxa de remuneração do capital investido para cálculo do custo do capital. O WACC pondera o custo de capital de terceiros, após a dedução da alíquota dos impostos incidentes sobre o lucro e o custo de capital próprio. A utilização de algumas premissas e a elaboração de alguns cenários foram necessários para a estimativa do custo do capital próprio do acionista. Além disso, alguns ajustes, como a inclusão de dividendos e juros sobre capital próprio pagos pelo BNDES ao acionista foram realizados para o cálculo do EVA®, além de outros ajustes contábeis necessários. Ao final do estudo, observamos que, em todos os cenários utilizados, a geração de lucro econômico foi negativa.

Price discovery in dual-class shares across multiple markets

We extend the standard price discovery analysis to estimate the information share of dual-class shares across domestic and foreign markets. By examining both common and preferred shares, we aim to extract information not only about the fundamental value of the rm, but also about the dual-class premium. In particular, our interest lies on the price discovery mechanism regulating the prices of common and preferred shares in the BM&FBovespa as well as the prices of their ADR counterparts in the NYSE and in the Arca platform. However, in the presence of contemporaneous correlation between the innovations, the standard information share measure depends heavily on the ordering we attribute to prices in the system. To remain agnostic about which are the leading share class and market, one could for instance compute some weighted average information share across all possible orderings. This is extremely inconvenient given that we are dealing with 2 share prices in Brazil, 4 share prices in the US, plus the exchange rate (and hence over 5,000 permutations!). We thus develop a novel methodology to carry out price discovery analyses that does not impose any ex-ante assumption about which share class or trading platform conveys more information about shocks in the fundamental price. As such, our procedure yields a single measure of information share, which is invariant to the ordering of the variables in the system. Simulations of a simple market microstructure model show that our information share estimator works pretty well in practice. We then employ transactions data to study price discovery in two dual-class Brazilian stocks and their ADRs. We uncover two interesting ndings. First, the foreign market is at least as informative as the home market. Second, shocks in the dual-class premium entail a permanent e ect in normal times, but transitory in periods of nancial distress. We argue that the latter is consistent with the expropriation of preferred shareholders as a class.

Mecanismo LPVR - Least Present Value of Revenues como mitigador de riscos em concessões rodoviárias: uma aplicação a um caso brasileiro

Nos últimos anos o governo brasileiro tem adotado a postura de incentivo a projetos de infraestrutura, sendo as concessões rodoviárias um dos principais mecanismos. Muito se discute sobre a melhor forma de remuneração das concessionárias, sem que, ao mesmo tempo, os usuários não tenham um custo elevado e possam usufruir de bons serviçoes prestados.Essa discussão passa, principalmente, por uma análise de risco de tráfego, que hoje é inteiramente alocado as cconcessionárias. A metodologia utilizada nos últimos leilões segue uma exigência de Taxa Interna de Retorno ( TIR ) máxima, pelo Poder Concedente ( ANTT ), em termos reais e um prazo de concessão fixo. A partir de custos e investimentos estimados em determinada concessão, a ANTT define uma tarifa-teto a ser cobrada pela concessionária aos usuários através da TIR máxima exigida no projeto. Esta TIR é calculada com base no custo médio ponderado de capital ( WACC ) de empresas do setor, que tem ações negociadas na BM&F Bovespa, utilizando-se apenas dados domésticos. Neste trabalho é proposto um modelo alternativo, baseado no menor valor presente das receitas ( LPVR - Least Present Value of Revenues ). Neste modelo observamos que o risco de tráfego é bem menor para a concessionária, pois a concessão só se expira quando determinado nível de receitas exigido pela concessionária é atingido. Ou seja, para tal, é necessário um modelo de prazo flexível. Neste mecanismo, entretanto, com menor risco de tráfego, o upside e o downside, em termos de retorno, são menores em comparação com o modelo vigente. Utilizando este modelo, o Poder Concedente pode também definir um vencedor para o leilão ( a concessionária que ofertar o menor valor presente das receitas ) e também se utilizar da proposta de simulação de tráfegos para a definição de um prazo máximo para a concessão, em caso de implementação do mecanismo proposto.

Operational parameters of soybean seeding in santa fe system

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Efeitos da laserterapia de baixa potência sobre a fadiga do músculo quadríceps de indivíduos jovens

The objective of this study was to evaluate the effect of low laser power on the performance of anaerobic endurance of the quadriceps muscle in young subjects. Low-level laser therapy (LLLT) appears to decrease some indices of muscle fatigue. Most of these effects may be due to the influence of the laser on the muscles predominantly aerobic. Animal studies and clinical trials have already shown that the laser can improve the efficiency of mitochondrial metabolism for the resynthesis of adenosine triphosphate and thus slow down - or minimize, the deleterious effects of muscle fatigue. This research was characterized as an experimental study of the controlled clinical trial, randomized, blinded, attended by 93 volunteers, military, with ages between 18 and 19 years. The subjects were randomly allocated into three groups: Control (G1), Placebo (G2) and Laser (G3). All volunteers underwent an anthropometric assessment and a protocol Fatigue. This protocol was applied to an initial assessment (AV-1) for the collection of baseline data, and a final evaluation (AV-2). As the study variables, we used the blood lactate concentrations and indices of muscle power, as average power and peak velocity. The fatigue protocol consisted of a test of speed with twenty repetitions, performed on an exercise machine leg press 45º . In conclusion, it was found that, in this study, LLLT caused a significant increase in the Average of the Averages Powers, phase eccentric exercise in leg press 45º performed by young individuals

Estimation of genetic parameters for milk yield in Murrah buffaloes by Bayesian inference

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Extração de feições retas com precisão subpixel: estudo comparativo entre três métodos

In the fields of Machine Vision and Photogrammetry, extracted straight lines from digital images can be used either as vector elements of a digital representation or as control entities that allow the determination of the camera interior and exterior orientation parameters. Applications related with image orientation require feature extraction with subpixel precision, to guarantee the reliability of the estimated parameters. This paper presents three approaches for straight line extraction with subpixel precision. The first approach considers the subpixel refinement based on the weighted average of subpixel positions calculated on the direction perpendicular to the segmented straight line. In the second approach, a parabolic function is adjusted to the grey level profile of neighboring pixels in a perpendicular direction to the segmented line, followed by an interpolation of this model to estimate subpixel coordinates of the line center. In the third approach, the subpixel refinement is performed with a parabolic surface adjustment to the grey level values of neighboring pixels around the segmented line. The intersection of this surface with a normal plane to the line direction generates a parabolic equation that allows estimating the subpixel coordinates of the point in the straight line, assuming that this is the critical point of this function. Three experiments with real images were made and the approach based on parabolic surface adjustment has presented better results.

Efeito do método pilates no desempenho muscular e no equilíbrio corporal de mulheres idosas: ensaio clínico controlado randomizado

Background: The Pilates Method is a modality of exercise that has been growing in recent decades, but few researches has been conducted with elderly and little is known about its benefits in this population. Objective: To evaluate the effect of a program of Mat Pilates exercises in muscle performance and postural balance in elderly women. Materials and Method: This is a randomized controlled trial that evaluated the muscle performance (isokinetic dynamometer Biodex System 3 Pro®) and postural balance (Balance Master System®) of 33 women aged 65-80 years. The experimental group (EG) participated of a 12-week program of Mat Pilates exercises with two weekly sessions. Data normality was verified by the Shapiro - Wilk test and were adopted p value < 0.05 as significance level. Results: There were no differences between groups after training. However, the EG showed an increase in the values of extension and flexion average power to 60 ° / s after training (32.19 W to 37.04 W and 14.48 W to 17.56 W, respectively). Conclusion: The proposed exercise program was not effective in the total work and average power of flexor and extensor of the knee, as well as static and dynamic balance of participants