Two-Dimensional Modeling of Thermoelectric Cells

The present paper is aimed at putting forward a two-dimensional model for thermoelectric cells. The energy conservation equation was formulated in order to account for the Fourier, the Thomson and the Joule effects on the temperature distribution. The electric field was also solved to come out with the current and voltage distributions. The governing equations were discretized by means of the finite-volume method, whereas the TDMA algorithm was adopted for solving the sets of linear equations. An explicit iterative solution scheme was employed to address the temperature influence on the Seebeck coefficient. The model results were compared with experimental data, when a satisfactory agreement was achieved for both cooling capacity and COP, with errors within a ?10% band. In addition, the model was employed to assess the effects of the thermoelectric properties and the couple geometry on the thermodynamic performance of the thermoelectric cell

IFRS and Stock Returns: an Empirical Analysis in Brazil

In recent years, the convergence of accounting standards has been an issue that motivated new studies in the accounting field. It is expected that the convergence provides users, especially external users of accounting information, with comparable reports among different economies. Considering this scenario, this article was developed in order to compare the effect of accounting numbers on the stock market before and after the accounting convergence in Brazil. The sample of the study involved Brazilian listed companies at BM&FBOVESPA that had American Depository Receipts (levels II and III) at the New York Stock Exchange (NYSE). For data analysis, descriptive statistics and graphic analysis were employed in order to analyze the behavior of stock returns around the publication dates. The main results indicate that the stock market reacts to the accounting reports. Therefore, the accounting numbers contain relevant information for the decision making of investors in the stock market. Moreover, it is observed that after the accounting convergence, the stock returns of the companies seem to present lower volatility

Health-promoting effects of Thymus herba-barona, Thymus pseudolanuginosus, and Thymus caespititius decoctions

Thymus herba-barona, Thymus pseudolanuginosus, and Thymus caespititius decoctions were screened for their phenolic constituents, along with their potential antioxidant, anti-inflammatory, and antibacterial activities. The total phenolic compounds in the extracts of the three plants ranged from 236.0 ± 26.6 mgGAE/g (T. caespititus) to 293.0 ± 30.5 mgGAE/g of extract (T. pseudolanuginosus), being particularly rich in caffeic acid derivatives, namely rosmarinic acid and its structural isomers, as well as flavones, such as luteolin-O-glucuronide. The T. pseudolanuginosus extract presented the best DPPH radical scavenging ability (EC 50 = 10.9 ± 0.7 µg/mL), a high reducing power (EC 50 = 32.2 ± 8.2 µg/mL), and effectively inhibited the oxidation of β-carotene (EC 50 = 2.4 ± 0.2 µg/mL). The extracts also showed NO· scavenging activity close to that of ascorbic acid, and thus might be useful as anti-inflammatory agents. In addition, they exhibited antibacterial activity against gram-negative and gram-positive bacteria. Staphylococcus aureus strains were the most sensitive bacteria to thyme extracts, with minimum inhibitory concentration and minimum bactericidal concentration values in the range of 0.6–3.5 mg/mL. Overall, this work is an important contribution for the phytochemical characterization and the potential antioxidant, anti-inflammatory, and antimicrobial activities of these three Thymus species, which have been poorly explored.The authors acknowledge to the Foundation for Science and Technology (FCT), the European Union, the National Strategic Reference Framework (QREN), the European Regional Development Fund (FEDER), and Operational Programme Competitiveness Factors (COMPETE), for funding the Organic Chemistry Research Unit (QOPNA) (project PEst-C/QUI/UI0062/2013; FCOMP-01-0124-FEDER-037296).info:eu-repo/semantics/publishedVersio

Clear-water scour at comparatively large cylindrical piers

New long-duration clear-water scour data were collected at single cylindrical piers with the objective of investigating the effect of sediment coarseness, Dp=D50 (Dp = pier diameter; D50 = median grain size) on the equilibrium scour depth and improving the scour depth time evolution modeling by making use of the exponential function suggested in the literature. Experiments were carried out for the flow intensity close to the threshold condition of initiation of sediment motion, imposing wide changes of sediment coarseness and flow shallowness, d=Dp (d = approach flow depth). The effect of sediment coarseness on the equilibrium scour depth was identified; existing predictors were modified to incorporate this effect for U=Uc ≈ 1.0; Dp=D50 > ≈60 and d=Dp ≥ 0.5; the complete characterization of a known scour depth time evolution model was achieved for U=Uc ≈ 1.0, 60 < Dp=D50 < 500 and 0.5 ≤ d=Dp ≤ 5.0

Tropical Urban heat Island Simulation Using the Topographic Vorticity Mesoscale (tvm) Model

In this work, a numerical simulation of the Urban Heat Island(UHI) of Rio de Janeiro City is set up using the Topographic VorticityMesoscale (TVM) model. At noon, the resulting surface potentialtemperature presents a strong UHI core across the Fluminense Lowlands(Baixada Fluminense), whereas the specific humidity reaches its lowestvalues.Neste trabalho, uma simulação numérica da Ilha de Calor Urbana(ICU) da cidade de Rio de Janeiro é feita usando o modeloTopographic Vorticity Mesoscale (TVM). A temperatura potencial resultantemostra ao meio dia uma forte ICU na região da Baixada Fluminensee um mínimo de umidade específica

Irradiância Solar em Cânions Urbanos

Neste trabalho apresenta-se a metodologia de derivação das equaçõesda média azimutal da irradiância solar incidente sobre superfícies quecompõem os cânions urbanos (telhados, paredes e vias), exemplificada nestetrabalho para a irradiância sobre as vias. As equações foram implementadasem um modelo de superfície urbana derivado do modelo Town EnergyBudget (TEB). Os resultados obtidos em um teste de sensibilidade domodelo, em relação aos fatores (1) variação do albedo e (2) razão de aspectodos cânions urbanos, indicam a importância relativa destes fatores para aintensidade e evolução do fluxo de calor sensível da cidade e da temperaturado ar dentro dos cânions

Fuel Costs Minimization on a Steel Billet Reheating Furnace Using Genetic Algorithms

Metallurgy industries often use steel billets, at a proper temperature, to achieve the desired metallurgical, mechanical, and dimensional properties of manufactured products. Optimal operation of steel billet reheating furnaces requires the minimization of fuel consumption while maintaining a homogeneous material thermal soak. In this study, the operation of a reheating furnace is modeled as a nonlinear optimization problem with the goal of minimizing fuel cost while satisfying a desired discharge temperature. For this purpose, a genetic algorithms approach is developed. Computational simulation results show that it is possible to minimize costs for different charge temperatures and production rates using the implemented method. Additionally, practical results are validated with actual data, in a specific scenario, showing a reduction of 3.36% of fuel consumption