The spreading phase in Lighthill's model of the Weis-Fogh lift mechanism

2009 ◽  
Vol 641 ◽  
pp. 195-204 ◽  
Author(s):  
DARREN CROWDY
Keyword(s):  
Analytical Model ◽  
Opening Angle ◽  
Second Phase ◽  
Two Dimensional ◽  
Flat Plates ◽  
Critical Opening ◽  
Lift Mechanism ◽  
Centre Of Rotation ◽  
Opening Phase

Lighthill's analysis (J. Fluid Mech., vol. 60, 1973, p. 1) of the Weis-Fogh lift mechanism is extended to include the spreading phase of the cycle. Lighthill proposed a two-dimensional inviscid irrotational analytical model to compute the circulation around two flat plates (the wings) as they open out, in opposite directions, about a common centre of rotation taken to be at the point of contact of an edge of each plate (the ‘opening phase’). At a critical opening angle, the plates separate and move apart horizontally (the ‘spreading phase’). During this second phase, the fluid region becomes doubly connected and is not analysed by Lighthill. It can, however, also be studied analytically and the results are presented here. We also extend a similar analysis, in an application to turbomachinery, due to Furber & Ffowcs Williams (J. Fluid Mech., vol. 94, 1979, p. 519).

The Wedge Under a Concentrated Couple: A Paradox in the Two-Dimensional Theory of Elasticity

1958 ◽  
Vol 25 (4) ◽  
pp. 575-581
Author(s):  
Eli Sternberg ◽  
W. T. Koiter
Keyword(s):  
Wedge Angle ◽  
Theory Of Elasticity ◽  
Opening Angle ◽  
Two Dimensional ◽  
Elastic Wedge ◽  
Singular Behavior ◽  
Dimensional Theory ◽  
Dimensional Solution ◽  
Critical Opening ◽  
Concentrated Couple

Abstract The classical two-dimensional solution for the stress distribution in an elastic wedge which is subjected to a concentrated couple at the vertex, breaks down when the opening angle 2α of the wedge satisfies the equation tan 2α = 2α, i.e., when 2α is approximately 257 deg. As the foregoing critical opening angle 2α* is approached, all of the nonvanishing components of stress become infinite throughout the field, while the solution displays no obvious pathological characteristics for other values of the wedge angle. It is the purpose of the present paper to account for this peculiar singular behavior and to show that the solution under examination has physical significance only for wedge angles below the critical angle; for opening angles in the range 2α* ≤ 2α < 2π, the notion of a “concentrated couple” at the vertex of an elastic wedge, is found to be inherently deficient in meaning. The present investigation, as a by-product, augments the supply of counterexamples to the traditional version of Saint Venant’s principle.

Representação e simbolismo: artes visuais na fronteira Brasil/Bolívia

2020 ◽  
Vol 4 (3) ◽  
pp. 286
Author(s):  
Paulo César Antonini de Souza ◽  
Derick Trindade Bezerra
Keyword(s):  
Visual Arts ◽  
Social Order ◽  
Research Field ◽  
Border Region ◽  
Second Phase ◽  
Two Dimensional ◽  
Santa Cruz ◽  
Cultural Conditions ◽  
Two Phases ◽  
America Latina

ResumoTendo por campo de investigação o Festival da América do Sul Pantanal (FASP) em 2018, na cidade de Corumbá (Brasil), objetiva-se identificar a materialidade e conceitos que permeiam as manifestações artísticas bidimensionais nesta região de fronteira, a partir da percepção de artistas da Bolívia. A pesquisa se organizou em duas fases: na primeira foi realizado um levantamento em plataformas online de produções acadêmicas em artes visuais, com foco no trabalho bidimensional, utilizando os descritores “arte popular” e “estética latina” resultando em três artigos. Na segunda fase foram selecionados dois trabalhos de uma artista da Bolívia, participante da mostra “Conexão Santa Cruz”, realizada durante o FASP 2018, que foram analisados em seus níveis representacional e simbólico. Pela interpretação das imagens foi possível construir uma leitura sobre a perspectiva da artista a respeito de suas condições culturais dentro da ordenação social em que se encontra situada.Palavras-chave: Artes Visuais. Arte Popular. Arte Regional. América Latina. Representation and symbolism: visual arts on the Brazil/Bolivia frontierAbstractHaving as research field the Festival da América do Sul Pantanal (FASP) in 2018, in the city of Corumbá (Brazil), the objective is to identify the materiality and concepts that permeate the two-dimensional artistic manifestations in this border region, from the perception of artists from Bolivia. The research was organized in two phases: in the first, a survey was carried out on online platforms of academic productions in visual arts, focusing on two-dimensional work, using the descriptors “arte popular” and “estética latina” resulting in three articles. In the second phase, two works were selected by an artist from Bolivia, participating in the exhibition “Conexão Santa Cruz”, held during FASP 2018, which were analyzed at their representational and symbolic levels. Through the interpretation of the images, it was possible to construct a reading on the artist’s perspective regarding her cultural conditions within the social order in which she is located.Keywords: Visual Arts. Folk Art. Regional Art. Latin America.Representación y simbolismo: artes visuales en la frontera de Brasil/BoliviaResumenTeniendo como campo de investigación el Festival de Sudamérica Pantanal (FASP) en 2018, en la ciudad de Corumbá (Brasil), el objetivo es identificar la materialidad y conceptos que permean las manifestaciones artísticas bidimensionales en esta región fronteriza, desde la percepción de artistas de Bolivia. La investigación se organizó en dos fases: en la primera, se realizó una encuesta en plataformas online de producciones académicas en artes visuales, con foco en el trabajo bidimensional, utilizando los descriptores “arte popular” y “estética latina” dando como resultado tres artículos. En la segunda fase, dos obras fueron seleccionadas por un artista de Bolivia, participante de la exposición “Conexão Santa Cruz”, realizada durante FASP 2018, que fueron analizadas en sus niveles representativos y simbólicos. A través de la interpretación de las imágenes, fue posible construir una lectura sobre la perspectiva de la artista sobre sus condiciones culturales dentro del orden social en el que se ubica.Palabras clave: Artes Visuales. Arte Popular. Arte Regional. América Latina.

Two dimensional analytical model for a reconfigurable field effect transistor

2018 ◽  
Vol 114 ◽  
pp. 62-74 ◽  
Author(s):  
R. Ranjith ◽  
Remya Jayachandran ◽  
K.J. Suja ◽  
Rama S. Komaragiri
Keyword(s):  
Analytical Model ◽  
Field Effect ◽  
Field Effect Transistor ◽  
Two Dimensional ◽  
Effect Transistor

Research on Micro-Mechanism of Nanocomposite Ceramic in Two-Dimensional Ultrasound Grinding

2007 ◽  
Vol 359-360 ◽  
pp. 344-348 ◽  
Author(s):  
Bo Zhao ◽  
Yan Wu ◽  
Guo Fu Gao ◽  
Feng Jiao
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Deformation Mechanism ◽  
Ground Surface ◽  
Grain Boundary Sliding ◽  
Second Phase ◽  
Two Dimensional ◽  
Composite Ceramics ◽  
Nano Composite ◽  
Boundary Sliding

Surface microstructure of nano-composite ceramics prepared by mixed coherence system and machined by two-dimensional ultrasonic precision grinding was researched using TEM, SEM, XRD detector and other equipments. Structure, formation mechanism and characteristic of metamorphic layer of ground surface of nano-composite ceramics were researched. The experiment shows micro deformation mechanism of ceramic material in two-dimensional ultrasound grinding is twin grain boundary and grain-boundary sliding for Al2O3, and it is crystal dislocation of enhanced phase, matrix grain boundary sliding, coordination deformation of intergranular second phase as well as its deformation mechanism for nano-composite ceramics. The fracture surfaces of nano-composite materials with different microscopic structure were observed using TEM and SEM. Research shows that ZrO2 plays an important influence on the generation and expansion of crack, and enhances the strength of grain boundaries. When grain boundaries is rich in the ZrO2 particles, the crack produced in grinding process will be prevented, and the surface with plastic deformation will be smooth. The results shows nanoparticles dispersed in grain boundary prevents crack propagation and makes materials fracture transgranularly which makes the processed surface fine.

A two-dimensional analytical model of homojunction GaAs BMFET structures

1996 ◽  
Vol 39 (8) ◽  
pp. 1221-1229 ◽  
Author(s):  
S. Bellone ◽  
N. Rinaldi ◽  
G.F. Vitale ◽  
G. Cocorullo ◽  
G. Schweeger ◽  
...  
Keyword(s):  
Analytical Model ◽  
Two Dimensional
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