2,706 research outputs found
Deformation and Aerodynamic Performance of a Ram-Air Wing
No full textRam-air wings form an ever increasing market of soft fabric, air inflated wings. They are primairily used in air sports such as parachuting, paragliding and kiting. Ram-air kites may also be used for electric power generation by letting the kite pull a cable from a drum that is connected to a generator. An example if this principle is the Laddermill concept. But since ram-air wings are flexible by nature they will deform and depart from their intended design shape when they are loaded by aerodynamic forces. These deformations generally affect the performance of the wings adversely. Kites with a higher lift-to-drag ratio on the Laddermill could mean a direct increase of the energy produced per square meter of kite. Besides this benefit for the Laddermill there is a huge, world-wide market of parachuting, paragliding and kiting that can benefit from more research and a better understanding of the deformation and aerodynamic performance of ram-air wings. The goals of this thesis are to be able to point out where a ram-air kite departs from the intended design shape, to investigate how well the kite performs, to understand how the deformations affect the airflow and to make suggestions for possible improvements of the design. Since little has been published about these subjects this report will most of all form a basis for further research. This report presents a method to analyse the shape and the aerodynamics of a ram-air kite. The kite is tested in the windtunnel. Its 3D shape is captured using two techniques: photogrammetry and laser scanning. Using the geometry data the structural deformation of the wing is dissected. With computational fluid dynamics the aerodynamics of the deformed shape is analyzed. An extra result of this study is the comparison of photogrammetry and laser scanning in terms of their suitability to capture the 3D shape of the ram-air kite. A number of interesting deformations and flow features were found on the ram-air wing: - Theoretically the bumps (ballooning) and grooves on a ram-air wing hinder the spanwise flow on a 3-dimensional wing, but in practise this effect is only visible on small parts of the upper surface. - The pull of the suspension lines on the under surface and the internal construction of the wing make the upper surface of the wing deform. This results in a decrease of the upper surface curvature, especially near the nose. This curvature decrease causes a loss of lift of at least 5%. - Because the flat, 2-dimensional fabric is inflated into a 3-dimensional shape the fabric wrinkles. The wrinkles continue from the top and bottom surface into the ribs that internally connect and support the top and bottom surface. On average these wrinkles shorten the ribs in chordwise direction by 3.5%. This decreases the surface area of the wing and it makes the ribs effectively thicker. Many more details became visible with the thorough analysis of the wing’s shape. The conclusion is that the performance of the ram-air wing can be improved by changing these details. The photogrammetry measuring technique gave better results than laser scanning and is very suitable tool to make these details visible. It allows a designer to identify where the real flying shape deviates from the design shape. This can help kite designers and designers of other ram-air wings to reverse-Aerospace Engineerin
Great Expectatrics: Great Papers, Great Journals, Great Econometrics
No full textThe paper discusses alternative Research Assessment Measures (RAM), with an emphasis on the Thomson Reuters ISI Web of Science database (hereafter ISI). The various ISI RAM that are calculated annually or updated daily are defined and analysed, including the classic 2-year impact factor (2YIF), 5-year impact factor (5YIF), Immediacy (or zero-year impact factor (0YIF)), Eigenfactor score, Article Influence, C3PO (Citation Performance Per Paper Online), h-index, Zinfluence, and PI-BETA (Papers Ignored - By Even The Authors). The ISI RAM data are analysed for 8 leading econometrics journals and 4 leading statistics journals. The application to econometrics can be used as a template for other areas in economics, for other scientific disciplines, and as a benchmark for newer journals in a range of disciplines. In addition to evaluating high quality research in leading econometrics journals, the paper also compares econometrics and statistics, alternative RAM, highlights the similarities and differences in alternative RAM criteria, finds that several ISI RAM capture similar performance characteristics for the leading econometrics and statistics journals while the new PI-BETA criterion is not highly correlated with any of the other ISI RAM, and hence conveys additional information regarding ISI RAM, highlights major research areas in leading journals in econometrics, and discusses some likely future uses of RAM.Research assessment measures, impact factors, Immediacy, Eigenfactor score, Article influence, h-index, C3PO, Zinfluence, PI-BETA
Scientometric portrait of Ram Gopal Rastogi
No full textPublication productivity of Indian scientist (R.G. Rastogi) has been documented.
Scientometric analysis of 312 papers by Ram Gopal Rastogi published during 1954 to 1992 in various domains: (a) Luni -solar activity and quiet -time E & F- region (57); (b) Equatorial electric field and low and mid latitude iof:osphere (78); (c) Ionospheric E- region irregularities (19); (dj Ionospheric F- region irregularities (32); and (e) Magnetic disturbance effects on the equatorial low and mid latitude ionosphere (23) were analysed. Interdomainery contents and of the number of papers: a+b were 36; b+c and b+d were 20 each; b+e were 16;. c+e were 5; a+e were 3; d+e were 2; and a+d had only one publication. Highest collaborations were with H. Chandra (61), M.R. Deshpande (42), and G. Sethia (19) out of his total 97 collaborators. His highest productivity was during 1978 with 28 papers followed by 19 papers during 1977. The core journals preferred by him for publishing papers were: Indian Journal of Radio & Space Physics, India, and Journal of Atomic & Terrestrial Physics, UK (59 each), followed by Proceedings of the Indian Academy of Sciences, India (34). Most prolific title keywords with their frequencies were: Ionosphere (92); Equatorial (61); F-region (53); Equatorial electrojet region (40), and Magnetic equator (30)
Great Expectatrics: Great Papers, Great Journals, Great Econometrics
No full textThe paper discusses alternative Research Assessment Measures (RAM), with an emphasis on the Thomson Reuters ISI Web of Science database (hereafter ISI). The various ISI RAM that are calculated annually or updated daily are defined and analysed, including the classic 2-year impact factor (2YIF), 5-year impact factor (5YIF), Immediacy (or zero-year impact factor (0YIF)), Eigenfactor score, Article Influence, C3PO (Citation Performance Per Paper Online), h-index, Zinfluence, and PI-BETA (Papers Ignored - By Even The Authors). The ISI RAM data are analysed for 8 leading econometrics journals and 4 leading statistics journals. The application to econometrics can be used as a template for other areas in economics, for other scientific disciplines, and as a benchmark for newer journals in a range of disciplines. In addition to evaluating high quality research in leading econometrics journals, the paper also compares econometrics and statistics, alternative RAM, highlights the similarities and differences in alternative RAM criteria, finds that several ISI RAM capture similar performance characteristics for the leading econometrics and statistics journals while the new PI-BETA criterion is not highly correlated with any of the other ISI RAM, and hence conveys additional information regarding ISI RAM, highlights major research areas in leading journals in econometrics, and discusses some likely future uses of RAM.Research assessment measures; impact factors; Immediacy; Eigenfactor score; Article influence; h-index; C3PO; Zinfluence; PI-BETA
Steady-State Solver for a Ram-Air Kite Aeroelastic Model Based on Dynamic Relaxation
No full textWe present a computationally efficient steady-state solution method to model the aeroelastic deformation of a ram-air kite for airborne wind energy applications. The kite’s weight in comparison to the aerodynamic forces is small which justifies a quasi-steady analysis, neglecting gravitational and inertial force effects [1]. The approach is suitable to efficiently determine the deformed configuration of a ram-air kite for design and optimization purposes as found in [2]. Because of the expected large deformations and changes in the flow field, fluid-structure interaction has to be taken into account in the analysis.Wind Energ
Night-Time Stories from The Panchatantra
No full textSimilar to Arora's 101 Moral Stories of Grandpa, this hardbound book with dust-jacket has 100 pages. The T of C on 6 lists fifteen numbered stories. This book is remarkable for offering a large picture on almost every page. New to me is The Sparrows & the Tusker (51). An elephant breaks off a limb and unwittingly destroys a nest. The sparrows get help from a woodpecker, a fly, and a frog, Together they lull the elephant, blind him by pecking out his eyes, and mislead him into a deep pit he mistakes for a water-hole. It is nice to meet old friends from the Panchatantra and Kalila and Dimna tradition, and I enjoy Ram-Lakshman's art. One of the best images here is that of the lion springing into the well as the hare runs away (99). The dust-jacket is glued to the covers.This is a hardbound book (hard cover)This book has a dust jacket (book cover)Retold by Reinu Bhano
Minimização do risco em carteira: aplicação da moderna teoria do portfólio
No full textTCC (graduação) - Universidade Federal de Santa Catarina. Centro Sócio-Econômico. Economia.O elevado nível de oscilação no preço dos ativos no mercado acionário, ocasionado por expectativas dos agentes econômicos resulta em alto risco para os investidores, uma vez que tal comportamento torna-se imprevisível na presença de choques econômicos. Nesse sentido, os investidores procuram ao máximo inibir o componente aleatório dos preços dos ativos financeiros, por meio de um processo de diversificação de ativos. Dentre as metodologias existentes para a minimização do risco estão a de Markowitz e Sharpe. A metodologia de Markowitz é caracterizada pela otimização do trade-off entre risco e retorno, e permite delinear uma fronteira eficiente de portfólios, no qual se identifica as melhores composições de ativos para cada nível de risco assumido. Enquanto isso, o método de Sharpe, mais conhecido como CAPM, complementa a base da teoria moderna do portfólio. Dessa forma, o objetivo do presente estudo é utilizar uma metodologia de otimização de portfólio capaz de minimizar o risco e identificar seu maior retorno médio para cada nível de risco assumido. A partir da inclusão de um ativo livre de risco à fronteira eficiente de Markowitz, é possível determinar seu retorno exigido para os ativos. Conclui-se que a aplicação dos métodos à um caso real, por meio da utilização do software MatLab, apresentou-se eficaz, uma vez que foi possível identificar a minimização do risco mediante o procedimento de diversificação de ativos e a composição ideal para o alcance do ponto máximo do índice Sharpe
Narrativas de futebol: etnografia da mídia no Avaí FC (Florianópolis/SC)
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Filosofia e Ciências Humanas. Programa de Pós-Graduação em Antropologia SocialEsta etnografia é um estudo das performances de jornalistas e jogadores de futebol do Avaí FC durante entrevistas esportivas em Florianópolis,SC. Os sujeitos da pesquisa são repórteres, cinegrafistas, fotógrafos e jogadores, assessores de imprensa e dirigentes do Avaí FC. Ao etnografar os momentos espetaculares dessa relação, onde se constrói imagens mundialmente reconhecidas do futebol, a dissertação descreve e analisa estas entrevistas enquanto situações ritualísticas, refletindo sobre as dimensões culturais e simbólicas da comunicação no futebol. Tendo como eixo central dessa reflexão a eficácia destes símbolos nestas narrativas de futebol, analiso como são construídas estas performances, enfocando os aspectos não-discursivos e os diferentes níveis retóricos utilizados pelos sujeitos na interação. O objetivo foi construir um modelo de interpretação sobre o termo êmico "fazer" utilizado pelos jornalistas quando se referem ao trabalho com os jogadores, que identifiquei em cinco gêneros de performance no Avaí FC - treino, aeroporto, especial, jogo e coletiva. A etnografia dessas performances revelam elementos que tencionam as prerrogativas econômicas e as dimensões de verdade-falsidade atribuídas a esta interação na mídia. Durante a etnografia foram elaborados quatro documentários etnográficos, não apenas como forma de expressão, mas como forma de problematização da pesquisa delimitada pelo uso da câmera no trabalho de campo. As imagens indicaram diferentes formas de engajamento dos interlocutores com os filmes produzidos, fizeram com que, juntos com o antropólogo, estivessem implicados na construção daquilo que se tornou visível e público acerca das entrevistas no contexto do futebol de espetáculo.This is an ethnographic study of the performance of journalists and soccer players during interviews sports in Avaí FC, Florianópolis, SC. The research subjects are reporters, cameramen, photographers and players, press officers and leaders of Avail FC. When researching the spectacular moments of this relationship, which builds images globally recognized football, the dissertation describes and analyzes these interviews as ritualistic situations, reflecting on the cultural and symbolic dimensions of communication in football. Taking this as a central consideration the effectiveness of these symbols in these narratives football, I analyze how these performances are built, focusing the non-discursive and different rhetorical levels used by subjects in this interaction. The goal was to build a model of emic interpretation of the term "make" used by journalists when referring to work with the players, I have identified five genres of performance in Avaí FC - training, airport, especially, game and conference. The ethnography of these performances show elements that they intend economic prerogatives and dimensions of the true-false attributed to this interaction in the media. During the ethnographic four ethnographic documentaries were produced, not only as a means of expression, but as a way of questioning the research delineated by use of the camera. The images showed different forms of engagement with stakeholders films, made together with the anthropologist, were involved in the construction of what became visible and the public about the interviews in the context of the soccer spectacle
Aerodynamic analysis of the closure flap mechanism inside the NACA ram-air intake
No full textA low-speed aerodynamic analysis on the conventional NACA ram-air inlet of the Airbus A320 with a new closure flap was conducted. The conventional closure flap mechanism inside the NACA ram-air inlet is replaced by a morphing plate design. Steady-state Reynolds-Averaged Navier-Stokes (RANS) based Computational Fluid Dynamics (CFD) simulations were conducted in order to analyse the aerodynamic performance of the baseline model and the new design with morphing flap for a range of operating settings. For validation, the Least Squares version of the Grid Convergence Index was carried out to show the grid independence. The results show an improvement in pressure recovery with a maximum of 13.5% for the NACA ram-air inlet with a morphing flap installed compared to the baseline model with a hinged flap. The maximum drag reduction by replacing the hinged flap with a morphing flap was found to be 33.8%.Aerospace Engineerin
Ram-air kite airfoil and reinforcements optimization for airborne wind energy applications
No full textWe present a multidisciplinary design optimization method for the profile and structural reinforcement layout of a ram‐air kite rib. The aim is to minimize the structural elastic energy and to maximize the traction power of a ram‐air kite used for airborne wind energy generation. Because of the large deformations occurring during flight, a fluid‐structure interaction (FSI) routine is included in the optimization, which determines the actual deformed rib geometry and its corresponding aerodynamic characteristics. A qualitative comparison between FSI inclusion and exclusion in the optimization is given. Discrepancies in airfoil profile and structural layout are observed.Wind Energ
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