4,670 research outputs found
On using Directional Information for Parameter Space Decomposition in Ellipse Detection
No full textIn this paper we use the parametric polar representation to extend the application of edge directional information from circle to ellipse extraction. As a result we obtain a mapping which decomposes the parameter space required for ellipse extraction into two independent sub-spaces and one final histogram accumulator. The mapping includes the tangent of the angle of the first and second directional derivatives. These tangents are computed by considering edge direction at two border points. We show that the use of gradient information for parameter space decomposition avoids the intensive point labelling imposed by geometric constraints used by other approaches
Large-scale patterns in turbulent Rayleigh-Bénard convection in very large aspect ratio cells
No full textLarge-scale patterns, which are well-known from the spiral defect chaos regime of thermal convection at Rayleigh numbers Ra 105. They are uncovered when the turbulent fields are averaged in time and turbulent fluctuations are thus removed. We apply the Boussinesq closure to calculate turbulent viscosities and diffusivities, respectively. The resulting turbulent Rayleigh number Ra_, that describes the convection of the mean patterns, is indeed in the spiral defect chaos range. Interestingly, the turbulent Prandtl numbers are smaller than one with 0:2 _ Pr_ _ 0:4 for Prandtl numbers 0:7 _ Pr _ 10. Finally, we demonstrate that these mean flow patterns are robust to an additional finite-amplitude side wall-forcing when the level of turbulent fluctuations in the flow is sufficiently high
Reynolds number effect on 3D turbulent offset jet reattaching to a free surface
No full textExperimental study was carried out to investigate the effect of Reynolds number on 3D offset jet reattaching to above free surface. Sharp edged square nozzle was used to produce the jets, and the measurements were performed at the following six different Reynolds numbers: 2300, 3700, 5100, 7900, 10300 and 11900. Detailed velocity measurements were made in the symmetry plane. From the PIV data, the mean velocity and turbulence statistics were obtained to study the effects of Reynolds number on the salient features of the jet flow. Preliminary results on streamwise mean velocity decay along the nozzle centerline, contours of streamwise mean velocity and Reynolds shear stress are presented herein
The Benefits of Being Economics Professor A (and not Z)
No full textAlphabetic name ordering on multi-authored academic papers, which is the convention in the economics discipline and various other disciplines, is to the advantage of people whose last name initials are placed early in the alphabet. As it turns out, Professor A, who has been a first author more often than Professor Z, will have published more articles and experienced afaster growth rate over the course of her career as a result of reputation and visibility. Moreover, authors know that name ordering matters and indeed take ordering seriously: Several characteristics of an author group composition determine the decision to deviate from the default alphabetic name order to a significant extent.performance measurement, incentives, economists, name ordering
<i>Entrenchment, wealth, power, and the constitution of democratic societies</i> by Paul Starr
No full textEntrenchment, Wealth, Power, and the Constitution of Democratic Societies, by Paul Starr, New Haven, CT: Yale University Press. 2019. 280 pages, hardcover.Why should we, as Management scholars and educators, care about a book on political diagnosis? The answer is twofold. First, the calibre of the author (Paul Starr), an awardee of both Bancroft and Pulitzer Prizes, a former policy advisor to the Clinton administration, and the author of The Transformation of American Medicine (1982), a book with a profound impact on American policy circles. Second, the core concept (entrenchment) of the book, and its potential to advance the process of institutional development, and the ways in which we can reform and change our institutions to better meet the current and pressing needs of the many, rather than preserve the unequal privileges of a few. In light of the geopolitical, social, and environmental pressures we see currently rising across the world (George, Howard-Grenville, Joshi & Tihanyi, 2016; Howard-Grenville, Buckle, Hoskins & George, 2014) there is no better time to examine whether and how we can address some of these grand challenges by reforming and improving our institutions
M.S. Kutorga and V.M. Vedrov: Conflict of Teacher and Student
No full textВ статье рассматривается конфликт между М.С. Куторгой и его учеником В.М. Ведровым. Исследуются причины конфликта, а также то влияние, которое он оказал на дальнейшую научную карьеру ученика. This article discusses the conflict between M.S. Kutorga and his student V.M. Vedrov. The author investigates the causes of the conflict and its impact on academic career V.M. Vedrov
A ilegitimidade constitucional crítica da infra-estrutura de chaves públicas brasileiras: uma semiótica do poder
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Engenharia de Produção
Ultra-fast escape of a deformable jet-propelled body
No full textIn this work a cephalopod-like deformable body that fills an internal cavity with fluid and expels it to propel an escape manoeuvre, while undergoing a drastic external shape change through shrinking, is shown to employ viscous as well as mainly inviscid hydrodynamic mechanisms to power an impressively fast start. First, we show that recovery of added-mass energy enables a shrinking rocket in a dense inviscid flow to achieve greater escape speed than an identical rocket in a vacuum. Next, we extend the shrinking body results of Weymouth & Triantafyllou (J. Fluid Mech., vol. 702, 2012, pp. 470–487) to three-dimensional bodies and show that three hydrodynamic mechanisms must be combined to achieve rapid escape performance in a viscous fluid: added-mass energy recovery; flow separation elimination; and an optimized energy storage and recovery. In particular, we show that the mechanism of separation elimination achieved through rapid body shrinking, coordinated with the mechanism of recovering the initially imparted added-mass energy, is critical to achieving a high escape speed. Hence a flexible, collapsing body can be vastly superior to a rigid-shell jet-propelled body
Desenvolvimento de métodos para análise inorgânica de biodiesel, matérias-primas e co-produtos utilizando espectrometria atômica
No full textTese (doutorado) - Universidade Federal de Santa Catarina, Centro de Ciências Físicas e Matemáticas. Programa de Pós-Graduação em Química.A concentração de metais e outros elementos no biodiesel, suas matérias-primas e co-produtos depende de vários fatores, incluindo o processo de produção utilizado. A presença destes elementos como contaminantes inorgânicos é um dos fatores que influenciam no processo produtivo, nas propriedades e, consequentemente, na qualidade do biodiesel. Atualmente, os diversos processos de produção do biodiesel, aliados a grande demanda de comercialização deste biocombustível, fazem com que as agências reguladoras que controlam a qualidade do biodiesel sejam cada vez mais rigorosas quanto à qualidade do produto comercializado. Neste trabalho, são propostas metodologias analíticas para a análise inorgânica do biodiesel, matérias-primas (sementes oleaginosas e óleos vegetais) e da glicerina. As metodologias foram desenvolvidas utilizando diferentes técnicas espectrométricas e procedimentos de preparo das amostras. Posteriormente, os métodos desenvolvidos foram aplicados para avaliação da estabilidade dos metais no biodiesel e para determinação de elementos em diferentes etapas do processo de produção do biodiesel. As metodologias foram propostas para a determinação de 19 elementos (Al, Ba, Ca, Cd, Co, Cu, Fe, Ga, K, Mg, Mn, Mo, Na, Ni, P, Pb, Rb, Sr e Zn) em sete diferentes sementes oleaginosas, utilizando as técnicas de ICP-MS e ICP-OES; para determinação de Ca, Cu, Fe, K, Mg, Na, Zn, P e S em óleos vegetais e biodiesel por ICP-OES, utilizando como procedimento de preparo das amostras a simples diluição em álcool (etanol ou 1-propanol) e para a determinação de Cr e Fe, utilizando ICP-DRC-MS. Além destas, foram avaliadas diferentes técnicas de calibração e modificadores para a determinação de Cd, Pb e Tl em biodiesel utilizando ET AAS. Para a glicerina, uma metodologia simples para a determinação de resíduos de catalisadores alcalinos (Na e K) utilizando F AES também foi desenvolvida. Todas as metodologias propostas foram simples e eficazes. A precisão de cada metodologia, avaliada através do desvio padrão relativo (RSD), assim como os limites de detecção (3s, n = 10) obtidos, foram adequados para as determinações. A verificação da exatidão para as metodologias propostas foi realizada através de testes de recuperação, comparação dos resultados entre diferentes técnicas analíticas e, quando possível, pela análise de material de referência certificado. A avaliação da estabilidade do Cu, Fe, Mn e Pb em diferentes amostras de biodiesel provenientes de diferentes fontes demonstrou que, nas condições estudadas, as concentrações destes metais foram estáveis por um período de 19 meses. Estes resultados de estabilidade podem ser importantes para o futuro desenvolvimento de novas amostras de referência com concentrações certificadas para elementos de interesse. As metodologias mostraram ser adequadas para o monitoramento da concentração dos elementos em diferentes etapas do processo de produção do biodiesel, possibilitando a identificação das possíveis fontes destes elementos e um maior controle de qualidade em todo o processo de produção do biodiesel. Observou-se que o óleo vegetal extraído com solvente apresentou maiores concentrações dos analitos do que o óleo extraído por prensagem e que a purificação é uma etapa importante para redução dos contaminantes.Metals and other elements concentrations in biodiesel, its raw materials and co-products depend on several factors, including the production process adopted. The presence of these elements, as inorganic contaminants, may affect the biodiesel production process and its properties, and consequently, the quality of the fuel. The great variety of raw materials and of production processes, as its high, spread and increasing consumption, is leading to stricter conditions by the fuel quality control agencies. In this work, analytical methods for the determination for inorganic analysis of biodiesel, raw materials (oilseeds and vegetable oils) and glycerin, which is the main co-product resulting from the biodiesel production, are proposed. The methodologies were developed using different procedures for sample preparation and different atomic spectrometric techniques for element determination. Additionally, the methods proposed were applied to evaluate the stability of some metals in the biodiesel matrix and for the determination of trace and others elements in different steps of the biodiesel production process. Methods are proposed for the determination of 19 elements (Al, Ba, Ca, Cd, Co, Cu, Fe, Ga, K, Mg, Mn, Mo, Na, Ni, P, Pb, Rb, Sr and Zn) in seven different oilseeds, using ICP-MS and ICP-OES; for the determination of Ca, Cu, Fe, K, Mg, Na, Zn, P and S in vegetable oils and biodiesel by ICP -OES, using a simple dilution in alcohol (ethanol or 1-propanol), as sample preparation procedure and for the determination of Cr and Fe using ICP-DRC-MS. Moreover, different calibration techniques and modifiers were evaluated for the determination of Cd, Pb and Tl in biodiesel using ET AAS. A simple method for the determination of Na and K, as residues of the catalysts, in glycerin by F AES has also been developed. All proposed methods proved to be simple, accurate and precise for the determination of trace and other elements in the mentioned samples. The obtained limits of detection (3s, n = 10) were suitable for the intended analysis. The accuracy of the methods was evaluated by recovery tests, by comparing the results to the ones obtained using a different analytical technique and in, some cases, by the analysis of certified reference materials. The evaluation along the time of the concentrations of Cu, Fe, Mn and Pb in different samples of biodiesel obtained from different raw materials, has been shown that, under the applied conditions, the concentrations were stable within a period of 19 months. These results of metal stability in biodiesel samples may be important for the development of new reference samples with certified concentrations for elements of interest. The methodology has shown to be suitable for monitoring the concentrations of trace and other elements in different steps of the biodiesel production process, enabling the identification of possible sources of these elements and allowing a better understanding of the presence and fate of the inorganic contaminants throughout the production process. It was found that the oil chemically extracted from the seeds is richer in the studied elements than the oil extracted under pressure and that oil purification is important to reduce the contaminants concentrations
AIEDAM thematic collection: a perspective on data-enabled design – design meet data science
No full textGreen Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Internet of ThingsDesign, Organisation and Strateg
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