Supersonic flutter of composite skin panels of repeated-sublaminate layup

In high-speed aerospace vehicles, supersonic flutter is a well-known phenomenon of dynamic instability to which external skin panels are prone. In theory, the instability stage is expressed by the 'flutter critical parameter' Q(crit), which is a function of the stiffness-, and dynamic pressure parameters. For a composite skin panel, Q(crit) can be maximised by lay-up optimisation. Repeated-sublaminate lay-up schemes possess good potential for economical lay-up optimisation because the corresponding effort is limited to a family of sublaminates of few layers only. When Q(crit) is obtained for all sublaminates of a family, and the sublaminates ranked accordingly, the resulting ranking reveals not only the optimum lay-up, but also the near-optimum lay-ups, which are useful design alternatives, and the inferior lay-ups which should be avoided. In this paper, we examine sublaminate-ranking characteristics for a composite panel prone to supersonic flutter. In particular, we consider a simple supported midplane-symmetrical rectangular panel of typical aspect ratio alpha and flow angle psi, and for four-layered sublaminates, obtain the Q(crit)-based rankings for a wide range of the number of repeats, r. From the rankings, we find that an optimum lay-up can exist for which the outermost layer is oriented wide of, rather than along, the flow. Furthermore, for many lay-ups other than the optimum and the inferior, we see that as r increases, Q(crit) undergoes significant change in the course of converging. To reconcile these findings, eigenvalue-coalescence characteristics are discussed in detail for specific cases.

Non-linear resonance in strings under narrow band random excitation, part I: Planar response and stability

Non-linear planar response of a string to planar narrow band random excitation is investigated in this paper. A response equation for the mean square deflection σ2 is obtained under a single mode approximation by using the equivalent linearization technique. It is shown that the response is triple valued, as in the case of harmonic excitation, if the centre frequency of excitation Ω lies in a certain specified range. The triple valued response occurs only if the excitation bandwidth β is smaller than a critical value βcrit which is a monotonically increasing function of the intensity of excitation. An approximate method of investigating the almost sure asymptotic stability of the solution is presented and regions of instability in the Ω-σ2 plane have been charted. It is shown that planar response can become unstable either due to an unbounded growth of the in-plane component of motion or due to a spontaneous appearance of an out-of-plane component.

Metal-Nucleotide Interactions: Crystal Structures of Alkali (Li+, Na+, K+) and Alkaline Earth (Ca2+, Mg2+) Metal Complexes of Adenosine 2'-Monophosphate

Crystal structures of lithium, sodium, potassium, calcium and magnesium salts of adenosine 2'-monophosphate (2'-AMP) have been obtained at atomic resolution by X-ray crystallographic methods. 2'-AMP.Li belongs to the monoclinic space group P21 with a = 7.472(3)Å, b = 26.853(6) Å, c = 9.184(1)Å, b = 113.36(1)Å and Z= 4. 2'-AMP.Na and 2'-AMP.K crystallize in the trigonal space groups P31 and P3121 with a = 8.762(1)Å, c = 34.630(5)Å, Z= 6 and a = 8.931(4), Åc = 34.852(9)Å and Z= 6 respectively while 2'-AMP.Ca and 2'-AMP.Mg belong to space groups P6522 and P21 with cell parameters a = 9.487(2), c = 74.622(13), Z = 12 and a = 4.973(1), b = 10.023(2), c = 16.506(2), beta = 91.1(0) and Z = 2 respectively. All the structures were solved by direct methods and refined by full matrix least-squares to final R factors of 0.033, 0.028, 0.075, 0.069 and 0.030 for 2'-AMP.Li, 2'-AMP.Na, 2'- AMP.K, 2'-AMP.Ca and 2'-AMP.Mg, respectively. The neutral adenine bases in all the structures are in syn conformation stabilized by the O5'-N3 intramolecular hydrogen bond as in free acid and ammonium complex reported earlier. In striking contrast, the adenine base is in the anti geometry (cCN = -156.4(2)°) in 2'-AMP.Mg. Ribose moieties adopt C2'-endo puckering in 2'-AMP.Li and 2'-AMP.Ca, C2'-endo-C3'-exo twist puckering in 2'-AMP.Na and 2'-AMP.K and a C3'-endo-C2'-exo twist puckering in 2'-AMP.Mg structure. The conformation about the exocyclic C4'-C5' bond is the commonly observed gauche-gauche (g+) in all the structures except the gauche- trans (g-) conformation observed in 2'-AMP.Mg structure. Lithium ions coordinate with water, ribose and phosphate oxygens at distances 1.88 to 1.99Å. Na+ ions and K+ ions interact with phosphate and ribose oxygens directly and with N7 indirectly through a water oxygen. A distinct feature of 2'-AMP.Na and 2'-AMP.K structures is the involvement of ribose O4' in metal coordination. The calcium ion situated on a two-fold axis coordinates directly with three oxygens OW1, OW2 and O2 and their symmetry mates at distances 2.18 to 2.42Å forming an octahedron. A classic example of an exception to the existence of the O5'-N3 intramolecular hydorgen bond is the 2'-AMP.Mg strucure. Magnesium ion forms an octahedral coordination with three water and three phosphate oxygens at distances ranging from 2.02 to 2.11Å. A noteworthy feature of its coordination is the indirect link with N3 through OW3 oxygen resulting in macrochelation between the base and the phosphate group. Greater affnity of metal clays towards 5' compared to 2' and 3' nucleotides (J. Lawless, E. Edelson, and L. Manring, Am. Chem. Soc. Northwest Region Meeting, Seattle. 1978) due to macrochelation infered from solution studies (S. S. Massoud, H. Sigel, Eur. J. Biochem. 179, 451-458 (1989)) and interligand hydrogen bonding induced by metals postulated from metal-nucleotide structures in solid state (V. Swaminathan and M. Sundaralingam, CRC. Crit. Rev. Biochem. 6, 245-336 (1979)) are borne out by our structures also. The stacking patterns of adenine bases of both 2'-AMP.Na and 2'-AMP.K structures resemble the 2'-AMP.NH4 structure reported in the previous article. 2'-AMP.Li, 2'-AMP.Ca and 2'-AMP.Mg structures display base-ribose O4' stacking. An overview of interaction of monovalent and divalent cations with 2' and 5'-nucleotides has been presented.

Semi-similar solutions of the unsteady compressible second-order boundary layer flow at the stagnation point

Semi-similar solutions of the unsteady compressible laminar boundary layer flow over two-dimensional and axisymmetric bodies at the stagnation point with mass transfer are studied for all the second-order boundary layer effects when the free stream velocity varies arbitrarily with time. The set of partial differential equations governing the unsteady compressible second-order boundary layers representing all the effects are derived for the first time. These partial differential equations are solved numerically using an implicit finite-difference scheme. The results are obtained for two particular unsteady free stream velocity distributions: (a) an accelerating stream and (b) a fluctuating stream. It is observed that the total skin friction and heat transfer are strongly affected by the surface mass transfer and wall temperature. However, their variation with time is significant only for large times. The second-order boundary layer effects are found to be more pronounced in the case of no mass transfer or injection as compared to that for suction. Résumé Des solutions semi-similaires d'écoulement variable compressible de couche limite sur des corps bi-dimensionnels thermique, sont étudiées pour tous les effets de couche limite du second ordre, lorsque la vitesse de l'écoulement libre varie arbitrairement avec le temps. Le systéme d'équations aux dérivées partielles représentant tous les effets est écrit pour la premiére fois. On le résout numériquement á l'aide d'un schéma implicite aux différences finies. Les résultats sont obtenus pour deux cas de vitesse variable d'écoulement libre: (a) un écoulement accéléré et (b) un écoulement fluctuant. On observe que le frottement pariétal total et le transfert de chaleur sont fortement affectés par le transfert de masse et la température pariétaux. Néanmoins, leur variation avec le temps est sensible seulement pour des grandes durées. Les effets sont trouvés plus prononcés dans le cas de l'absence du transfert de masse ou de l'injection par rapport au cas de l'aspiration.

The Enlightenment Idea of History as a Legitimation Tool of Kemalism in Turkey

The study analyzes the effort to build political legitimacy in the Republic of Turkey by ex-ploring a group of influential texts produced by Kemalist writers. The study explores how the Kemalist regime reproduced certain long-lasting enlightenment meta-narrative in its effort to build political legitimacy. Central in this process was a hegemonic representation of history, namely the interpretation of the Anatolian Resistance Struggle of 1919 1922 as a Turkish Revolution executing the enlightenment in the Turkish nation-state. The method employed in the study is contextualizing narratological analysis. The Kemalist texts are analyzed with a repertoire of concepts originally developed in the theory of narra-tive. By bringing these concepts together with epistemological foundations of historical sciences, the study creates a theoretical frame inside of which it is possible to highlight how initially very controversial historical representations in the end manage to construct long-lasting, emotionally and intellectually convincing bases of national identity for the secular middle classes in Turkey. The two most important explanatory concepts in this sense are di-egesis and implied reader. The diegesis refers to the ability of narrative representation to create an inherently credible story-world that works as the basis of national community. The implied reader refers to the process where a certain hegemonic narrative creates a formula of identification and a position through which any individual real-world reader of a story can step inside the narrative story-world and identify oneself as one of us of the national narra-tive. The study demonstrates that the Kemalist enlightenment meta-narrative created a group of narrative accruals which enabled generations of secular middle classes to internalize Kemalist ideology. In this sense, the narrative in question has not only worked as a tool utilized by the so-called Kemalist state-elite to justify its leadership, but has been internalized by various groups in Turkey, working as their genuine world-view. It is shown in the study that secular-ism must be seen as the core ingredient of these groups national identity. The study proposes that the enlightenment narrative reproduced in the Kemalist ideology had its origin in a simi-lar totalizing cultural narrative created in and for Europe. Currently this enlightenment project is challenged in Turkey by those who are in an attempt to give religion a greater role in Turkish society. The study argues that the enduring practice of legitimizing political power through the enlightenment meta-narrative has not only become a major factor contributing to social polarization in Turkey, but has also, in contradiction to the very real potentials for crit-ical approaches inherent in the Enlightenment tradition, crucially restricted the development of critical and rational modes of thinking in the Republic of Turkey.

SEU Tolerant Robust Memory Cell Design

The implementation of semiconductor circuits and systems in nano-technology makes it possible to achieve high speed, lower voltage level and smaller area. The unintended and undesirable result of this scaling is that it makes integrated circuits susceptible to soft errors normally caused by alpha particle or neutron hits. These events of radiation strike resulting into bit upsets referred to as single event upsets(SEU), become increasingly of concern for the reliable circuit operation in the field. Storage elements are worst hit by this phenomenon. As we further scale down, there is greater interest in reliability of the circuits and systems, apart from the performance, power and area aspects. In this paper we propose an improved 12T SEU tolerant SRAM cell design. The proposed SRAM cell is economical in terms of area overhead. It is easy to fabricate as compared to earlier designs. Simulation results show that the proposed cell is highly robust, as it does not flip even for a transient pulse with 62 times the Q(crit) of a standard 6T SRAM cell.

REDUCED ORDER MODELLING OF COMBUSTION INSTABILITY IN A BACKWARD FACING STEP COMBUSTOR

This paper develops a fully coupled time domain Reduced Order Modelling (ROM) approach to model unsteady combustion dynamics in a backward facing step combustor The acoustic field equations are projected onto the canonical acoustic eigenmodes of the systems to obtain a coupled system of modal evolution equations. The heat release response of the flame is modelled using the G-equation approach. Vortical velocity fluctuations that arise due to shear layer rollup downstream of the step are modelled using a simplified 1D-advection equation whose phase speed is determined from a linear, local, temporal stability analysis of the shear layer just downstream of the step. The hydrodynamic stability analysis reveals a abrupt change in the value of disturbance phase speed from unity for Re < Re-crit to 0.5 for Re > Re-crit, where Remit for the present geometry was found to be approximate to 10425. The results for self-excited flame response show highly wrinkled flame shapes that are qualitatively similar to those seen in prior experiments of acoustically forced flames. The effect of constructive and destructive interference between the two contributions to flame surface wrinkling results in high amplitude wrinkles for the case when K-c -> 1.

Kohesioa ikasleek idatzitako iritzi gutunetan. Zenbait testu aztergai

[EUS]Argudiatzeko orduan izen kohesiorako mekanismoak nola erabiltzen diren aztertzen du lan honek. Horretarako 12 eta 14 urteko ikasleek iritzia emateko idazten dituzten gutunak hartzen dira kontuan, bi alderdi hauei erreparatuz: aurrekaria aurkeztu eta mantentzeko erabiltzen diren adierazpide anaforikoen ezaugarriei, eta adinaren arabera adierazpide horien erabileran egon daitezkeen ezberdintasunei. Adibide batzuen bitartez ikusiko dugunaren arabera, 14 urteko ikasleek estrategia diskurtsibo hobeak erabiltzen dituzte gutunari izen kohesioa emateko, besteak beste testuaren gestio globala eta planifikazioa ere hobeak direlako.

Gênero parte: polifonia e dispersão do sujeito na redação oficial

Este trabalho tem por objetivo investigar se haveria espaço para a polêmica num meio regido por princípios tão rígidos como os relacionados à hierarquia e à disciplina, o meio militar. Para isso, propusemo-nos estudar o emprego da partícula não nos enunciados de um gênero discursivo denominado parte, modalidade de documento cuja finalidade básica seria estabelecer a comunicação escrita entre os integrantes de uma mesma organização militar. Optamos por pesquisar as partes produzidas no ano de 2004 por dez setores da Base Aérea de Santa Cruz, em virtude de trabalhar nela há cerca de dez anos. Caso haja espaço para a polêmica no aludido meio, pretendemos averiguar como estariam sendo construídos os perfis dos enunciadores responsáveis pelos pontos de vista afirmativos subjacentes aos enunciados negativos das partes, bem como o tipo de polêmica que estariam instaurando nesse meio. Apresentamos, como considerações iniciais, os motivos que nos levaram à pesquisa, o problema, as hipóteses e o objetivo da pesquisa. No capítulo referente à introdução, discorremos sobre o gênero parte, bem como sobre as Instruções Normativas e os locais da enunciação, os setores da Base Aérea de Santa Cruz. No capítulo relativo ao quadro teórico, fizemos uma breve revisão da literatura. Nossa perspectiva teórica é a da Análise do Discurso de base enunciativa, com ênfase nos conceitos de dialogismo, de alteridade discursiva, de gêneros do discurso e de negação polêmica. A análise que conduzimos, considerando a noção de discurso como prática de linguagem socialmente instituída, traça os perfis dos enunciadores que estariam dialogando nos enunciados das partes. Como resultado, foi possível refletir sobre posições enunciativas dos enunciadores responsáveis pelos pontos de vista subjacentes aos enunciados negativos, identificadas em nosso corpus, sobre as relações de aproximação ou distanciamento entre os enunciadores postos em cena pelos enunciados negativos, bem como o embate entre seus pontos de vista e os dos veiculados pelos enunciados negativos e os efeitos de sentido que se podem depreender desse embate. Tais efeitos de sentido revelam a importância do gênero estudado e como os aportes teóricos da Análise do Discurso são produtivos mesmo para enunciados tão padronizados como os das partes

A imagem em meditação - Glitterbug e as formas de arquivamento no cinema de Derek Jarman

Este trabalho consiste em um estudo sobre a imagem, sobretudo em sua relação com a experiência do tempo e com a memória. Tendo por objeto central o filme Glitterburg, do diretor inglês Derek Jarman, esta dissertação procura pensar a constituição da imagem a partir de três processos distintos de arquivamento, sendo eles: o arquivamento da luz, o do tempo e o de si. A prática arquivistica será considerada, desse ponto de vista, não só como constituída por um conjunto de procedimentos (cortar, fixar, organizar, montar, etc), mas como uma operação que se encontra ligada a toda uma reflexão em torno da memória, da imagem, do tempo, da escrita de si e da morte. É, portanto, num esforço simultâneo de pensar tanto a dimensão processual quanto reflexiva da prática do arquivamento implicada nesse filme que esse estudo se desenvolve. Constituindo-se, nesse sentido, como trabalho geminado de análise focada numa obra cinematográfica particular e de conceituação do que se procura definir aqui, com base no cinema de Jarman, como imagem-arquivo.

Letras, ideias e culturas políticas: os escritos de Nabuco de Araújo (1843-1876)

A presente tese foi elaborada a partir do legado documental de José Thomaz Nabuco de Araújo (1813-1878), constituído de textos impressos, manuscritos políticos, cartas e bilhetes produzidos especialmente nas décadas de cinquenta e sessenta do oitocentos e conservados no Instituto Histórico e Geográfico Brasileiro. Político e homem de letras, frequentou bibliotecas e livrarias daquelas décadas, quando teve contato com obras e tendências do pensamento europeu. Os livros da biblioteca da Faculdade de Direito de Recife, onde se formou bacharel juntamente com outros burocratas de sua geração em 1835, marcaram o início de práticas de leitura e escrita voltadas para a apropriação do conteúdo e construção intencional de ideias políticas expressas no decorrer de sua rica e complexa trajetória como senador e ministro da justiça em gabinetes de diferentes siglas partidárias. O personagem fez uso das linguagens e matrizes do pensamento jusnaturalista, utitilarista, liberal e do humanismo cívico ao protagonizar importantes debates diretamente relacionados à prática da cidadania no Segundo Reinado, com destaque para temas como emancipação dos escravos, a participação civil de estrangeiros no Brasil, a liberdade de imprensa, a descentralização, reformas eleitorais e a missão dos partidos políticos. Nesse sentido, a temporalidade das ideias presentes no discurso evidenciaram não só os aspectos perenes, como também transitórios do pensamento de Nabuco de Araújo. Certas transformações e permanências são perceptíveis no final da década de 1850, ocasião em que o Gabinete da Conciliação deixou de existir e deu passagem, já em 1862, à Liga Progressista, uma aliança entre conservadores moderados e antigos liberais do Império. O estudo sobre o processo de emancipação gradativa dos escravos, especialmente no ano de 1871, ocasião em que o político pertenceu ao Movimento Centro Liberal, também constitui oportunidade ímpar para verificar a introdução de termos como pessoa nos escritos do personagem. Guiado por seus próprios interesses, ou por interesses do Governo e do seu partido, Nabuco de Araújo contribuiu para a formulação de novos conceitos e práticas e, portanto, exerceu influência na configuração da cultura política imperial, junto a seus pares. O referencial teórico fundamentado em autores da História das Ideias, especialmente Quentin Skinner, e nos estudos de produção de texto de Robert Darnton possibilitaram o entendimento dos limites e intersecções entre o liberalismo e o conservadorismo político no Segundo Reinado, além de desencadear certo revisionismo histórico da obra Um Estadista do Império, biografia póstuma de José Thomaz Nabuco de Araújo, elaborada por seu filho Joaquim Nabuco.

Reduced swimming abilities in fast-growing transgenic common carp Cyprinus carpio associated with their morphological variations

Critical swimming speeds (U-crit) and morphological characters were compared between the F-4 generation of GH-transgenic common carp Cyprinus carpio and the non-transgenic controls. Transgenic fish displayed a mean absolute U-crit value 22.3% lower than the controls. Principal component analysis identified variations in body shape, with transgenic fish having significantly deeper head, longer caudal length of the dorsal region, longer standard length (L-S) and shallower body and caudal region, and shorter caudal length of the ventral region. Swimming speeds were related to the combination of deeper body and caudal region, longer caudal length of the ventral region, shallower head depth, shorter caudal length of dorsal region and L-S. These findings suggest that morphological variations which are poorly suited to produce maximum thrust and minimum drag in GH-transgenic C. carpio may be responsible for their lower swimming abilities in comparison with non-transgenic controls.

Rapid growth cost in “all-fish” growth hormone gene transgenic carp: Reduced critical swimming speed

Evidence has accumulated that there is a trade-off between benefits and costs associated with rapid growth. A trade-off between growth rates and critical. swimming speed (U-crit) had been also reported to be common in teleost fish. We hypothesize that growth acceleration in the F-3 generation of "all-fish" growth hormone gene (GH) transgenic common carp (Cyprinus carpio L.) would reduce the swimming abilities. Growth and swimming performance between transgenic fish and non-transgenic controls were) compared. The results showed that transgenic fish had a mean body weight 1.4-1.9-fold heavier, and a mean specific growth rate (SGR) value 6%-10% higher than the controls. Transgenic fish, however, had a mean absolute U-crit (cm/s) value 22% or mean relative Ucrit (BL/s) value 24% lower than the controls. It suggested that fast-growing "all-fish" GH-transgenic carp were inferior swimmers. It is also supported that there was a trade-off between growth rates and swimming performance, i.e. faster-growing individuals had lower critical swimming speed.

Napięcia tożsamościowe, tematyczne i formalne w dziele Yasminy Khadry

Wydział Neofilologii Instytut Filologii Romańskiej

Vascular access, fluid resuscitation, and blood transfusion in pediatric trauma.

Trauma care in the general population has largely become protocol-driven, with an emphasis on fast and efficient treatment, good team communication at all levels of care including prehospital care, initial resuscitation, intensive care, and rehabilitation. Most available literature on trauma care has focused on adults, allowing the potential to apply concepts from adult care to pediatric care. But there remain issues that will always be specific to pediatric patients that may not translate from adults. Several new devices such as intraosseous (IO) needle systems and techniques such as ultrasonography to cannulate central and peripheral veins have become available for integration into our pre-existing trauma care system for children. This review will focus specifically on the latest techniques and evidence available for establishing intravenous access, rational approaches to fluid resuscitation, and blood product transfusion in the pediatric trauma patient.