967 resultados para Reynolds Average Navier-Stokes (RANS)
Resumo:
Coherent anti-Stokes Raman scattering (CARS) microscopy is rapidly developing into a unique microscopic tool in biophysics, biology and the material sciences. The nonlinear nature of CARS spectroscopy complicates the analysis of the received spectra. There were developed mathematical methods for signal processing and for calculations spectra. Fourier self-deconvolution is a special high pass FFT filter which synthetically narrows the effective trace bandwidth features. As Fourier self-deconvolution can effectively reduce the noise, which may be at a higher spatial frequency than the peaks, without losing peak resolution. The idea of the work is to experiment the possibility of using wavelet decomposition in spectroscopic for background and noise removal, and Fourier transformation for linenarrowing.
Resumo:
The thesis examines the profitability of DMAC trading rules in the Finnish stock market over the 1996-2012 period. It contributes to the existing technical analysis literature by comparing for the first time the performance of DMAC strategies based on individual stock trading portfolios to the performance of index trading strategies based on the trading on the index (OMX Helsinki 25) that consists of the same stocks. Besides, the market frictions including transaction costs and taxes are taken into account, and the results are reported from both institutional and individual investor’s perspective. Performance characteristic of DMAC rules are evaluated by simulating 19,900 different trading strategies in total for two non- overlapping 8-year sub-periods, and decomposing the full-sample-period performance of DMAC trading strategies into distinct bullish- and bearish-period performances. The results show that the best DMAC rules have predictive power on future price trends, and these rules are able to outperform buy-and-hold strategy. Although the performance of the DMAC strategies is highly dependent on the combination of moving average lengths, the best DMAC rules of the first sub-period have also performed well during the latter sub-period in the case of individual stock trading strategies. According to the results, the outperformance of DMAC trading rules over buy-and-hold strategy is mostly attributed to their superiority during the bearish periods, and particularly, during stock market crashes.
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Experiments were performed to determine average heat transfer coefficients and friction factors for turbulent flow through annular ducts with pin fins. The measurements were carried out by means of a double-pipe heat exchanger. The total number of pins attached to the inner wall of the annular region was 560. The working fluids were air, flowing in the annular channel, and water through the inner circular tube. The average heat transfer coefficients of the pinned air-side were obtained from the experimental determination of the overall heat transfer coefficients of the heat exchanger and from the knowledge of the average heat transfer coefficients of the circular pipe (water-side), which could be found in the pertinent literature. To attain fully developed conditions, the heat exchanger was built with additional lengths before and after the test section. The inner circular duct of the heat exchanger and the pin fins were made of brass. Due to the high thermal conductivity of the brass, the small tube thickness and water temperature variation, the surface of the internal tube was practically isothermal. The external tube was made of an industrial plastic which was insulated from the environment by means of a glass wool batt. In this manner, the outer surface of the annular channel can be considered adiabatic. The results are presented in dimensionless forms, in terms of average Nusselt numbers and friction factors as functions of the flow Reynolds number, ranging from 13,000 to 80,000. The pin fin efficiency, which depends on the heat transfer coefficient, is also determined as a function of dimensionless parameters. A comparison of the present results with those for smooth sections (without pins) is also presented. The purpose of such a comparison is to study the influence of the presence of the pins on the pressure drop and heat transfer rate.
Resumo:
Psychotria ipecacuanha é uma espécie medicinal da família Rubiaceae, importante pela produção em suas raízes do alcalóide emetina. Foram feitas análises das três populações disjuntas que compõem a espécie e que ocorrem na América Central (Nicarágua, Costa Rica e Panamá) e Colômbia, sul da Floresta Amazônica (Rondônia e Mato Grosso) e Mata Atlântica (Pernambuco até Paraná). Foram utilizados, no estabelecimento dos limites inter e intraespecíficos, todos os dados morfológicos vegetativos e reprodutivos disponíveis e feita análise dos componentes principais, que permitiram concluir que não existem diferenças significativas entre as populações examinadas. As poucas diferenças individuais observadas não estão relacionadas com a distribuição geográfica das populações examinadas. Como conclusão, a ipecacuanha ao longo de toda sua distribuição geográfica foi considerada como uma só espécie, Psychotria ipecacuanha (Brot.) Stokes. Além da análise taxonômica, são apresentados neste trabalho dados anatômicos e sobre o número de cromossomos da espécie.
Resumo:
Psychotria ipecacuanha is a perennial, medicinal herb that grows in clusters in the understory of humid, shady areas of the Atlantic Rain Forest of southeastern Brazil. The present study characterized the variation in floral traits among 35 clusters from three natural populations of this plant species. Field observations showed that the clusters are isomorphic, that is, a given cluster will either set long-styled or short-styled flowers. Stigmas and anthers are reciprocally placed in each morph, a dimorphism characteristic of distyly. The populations are isoplethic, that is, a given population exhibits an equilibrium 1:1 ratio of floral morphs. Morphometric analyses revealed that anther length, stigma length, corolla diameter, and pollen grain diameter were consistently greater in short-styled flowers, regardless of the population investigated. Significant differences for floral traits in the short-styled morph were found among populations. Floral traits in the long-styled morph also showed some significant differences among populations, but not for stigma height and corolla length. Controlled pollinations carried out in natural populations showed that fruit production was higher after inter-morph pollination. Nevertheless, observations of pollen tube growth in style, and also fruit production after spontaneous self-pollination and intra-morph pollination, indicated partial intramorph compatibility in this plant species.
Resumo:
Exposure to air pollutants is associated with hospitalizations due to pneumonia in children. We hypothesized the length of hospitalization due to pneumonia may be dependent on air pollutant concentrations. Therefore, we built a computational model using fuzzy logic tools to predict the mean time of hospitalization due to pneumonia in children living in São José dos Campos, SP, Brazil. The model was built with four inputs related to pollutant concentrations and effective temperature, and the output was related to the mean length of hospitalization. Each input had two membership functions and the output had four membership functions, generating 16 rules. The model was validated against real data, and a receiver operating characteristic (ROC) curve was constructed to evaluate model performance. The values predicted by the model were significantly correlated with real data. Sulfur dioxide and particulate matter significantly predicted the mean length of hospitalization in lags 0, 1, and 2. This model can contribute to the care provided to children with pneumonia.
Resumo:
Frank Reynolds graduated from Brock University in 1970. While a student at Brock Mr. Reynolds was active in student life, as editor of the student newspaper and as president of the student union. He also produced other student publications, including yearbooks. In 1970 he organized the Rock at Brock, which brought various rock groups to the university campus.
Resumo:
Generation Y is entering the workforce in large numbers and, because this generation holds different values than previous generations, accounting firms are having difficulty managing these new hires. I t is important to determine whether Generation Y is associated with meaningful, long-term trends or i f they will adapt to the given situation. Gen Y' s association with average hours worked per person and average salaries in the Canadian Accounting, Marketing, and Legal professions is examined. I find that an increasing percentage of Generation Y employees in the workforce is associated with significant decreases in average hours worked, but is not associated with any significant trend in average salary. I t is concluded that Generation Y is associated with changing trends in the workplace. These trends are contrary to wha t might be expected under traditional definitions of success, therefore it is postulated that Gen Y may view workplace success differently than previous generations.
Resumo:
The Average White Band's debut album, Show your hand, was released in 1973. The "classic funk and R & B" band included members Alan Gorrie, Owen "Onnie" McIntyre, Malcolm "Mollie" Duncan, Roger Ball, Robbie McIntosh, and Mike Rosen. Rosen was quickly replaced by Hamish Stuart. The band, comprised of Scotsmen, released a second album in 1974 that featured the US number 1/UK Top 10 single "Pick up the Pieces". That same year, Robbie McIntosh died of a heroin overdose and was replaced by Steve Ferrone. The song "Cut the Cake" from their third album made the US top 10, and subsequent releases in the late 1970s and early 1980s proved successful. The members largely pursued individual projects in the years that followed, but re-formed in 1989 (with original members Gorrie, Ball and McIntyre, and new members Alex Ligertwood and Eliot Lewis) and released the album Aftershock. Over the years, the band's members have changed, and the band is currently comprised of Onnie McIntyre, Rocky Bryant, Alan Gorrie, Fred "Freddy V" Vigdor and Klyde Jones. Their most recent album, Times Squared, was released in 2009.
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Cette thèse de doctorat présente les résultats d'un relevé spectropolarimétrique visant la détection directe de champs magnétiques dans le vent d'étoiles Wolf-Rayet (WR). Les observations furent entièrement obtenues à partir du spectropolarimètre ESPaDOnS, installé sur le télescope de l'observatoire Canada-France-Hawaii. Ce projet débuta par l'observation d'un étoile très variable de type WN4 appelée EZ CMa = WR6 = HD 50896 et se poursuivit par l'observation de 11 autres étoiles WR de notre galaxie. La méthode analytique utilisée dans cette étude vise à examiner les spectres de polarisation circulaire (Stokes V) et à identifier, au travers des raies d'émission, les signatures spectrales engendrées par la présence de champs magnétiques de type split monopole dans les vents des étoiles observées. Afin de pallier à la présence de polarisation linéaire dans les données de polarisation circulaire, le cross-talk entre les spectres Stokes Q et U et le spectre Stokes V fut modélisé et éliminé avant de procéder à l'analyse magnétique. En somme, aucun champ magnétique n'est détecté de manière significative dans les 12 étoiles observées. Toutefois, une détection marginale est signalée pour les étoiles WR134, WR137 et WR138 puisque quelques-unes de leur raies spectrales semblent indiquer la présence d'une signature magnétique. Pour chacune de ces trois étoiles, la valeur la plus probable du champ magnétique présent dans le vent stellaire est respectivement de B ~ 200, 130 et 80 G. En ce qui concerne les autres étoiles pour lesquelles aucune détection magnétique ne fut obtenue, la limite supérieure moyenne de l'intensité du champ qui pourrait être présent dans les données, sans toutefois être détecté, est évaluée à 500 G. Finalement, les résultats de cette étude ne peuvent confirmer l'origine magnétique des régions d'interaction en co-rotation (CIR) observées chez plusieurs étoiles WR. En effet, aucun champ magnétique n'est détecté de façon convaincante chez les quatre étoiles pour lesquelles la présence de CIR est soupçonnée.
Resumo:
Il est connu qu’une équation différentielle linéaire, x^(k+1)Y' = A(x)Y, au voisinage d’un point singulier irrégulier non-résonant est uniquement déterminée (à isomorphisme analytique près) par : (1) sa forme normale formelle, (2) sa collection de matrices de Stokes. La définition des matrices de Stokes fait appel à un ordre sur les parties réelles des valeurs propres du système, ordre qui peut être perturbé par une rotation en x. Dans ce mémoire, nous avons établi le caractère intrinsèque de cette relation : nous avons donc établi comment la nouvelle collection de matrices de Stokes obtenue après une rotation en x qui change l’ordre des parties réelles des valeurs propres dépend de la collection initiale. Pour ce faire, nous donnons un chapitre de préliminaires généraux sur la forme normale des équations différentielles ordinaires puis un chapitre sur le phénomène de Stokes pour les équations différentielles linéaires. Le troisième chapitre contient nos résultats.
Resumo:
The thesis report results obtained from a detailed analysis of the fluctuations of the rheological parameters viz. shear and normal stresses, simulated by means of the Stokesian Dynamics method, of a macroscopically homogeneous sheared suspension of neutrally buoyant non-Brownian suspension of identical spheres in the Couette gap between two parallel walls in the limit of vanishingly small Reynolds numbers using the tools of non-linear dynamics and chaos theory for a range of particle concentration and Couette gaps. The thesis used the tools of nonlinear dynamics and chaos theory viz. average mutual information, space-time separation plots, visual recurrence analysis, principal component analysis, false nearest-neighbor technique, correlation integrals, computation of Lyapunov exponents for a range of area fraction of particles and for different Couette gaps. The thesis observed that one stress component can be predicted using another stress component at the same area fraction. This implies a type of synchronization of one stress component with another stress component. This finding suggests us to further analysis of the synchronization of stress components with another stress component at the same or different area fraction of particles. The different model equations of stress components for different area fraction of particles hints at the possible existence a general formula for stress fluctuations with area fraction of particle as a parameter