An investigation of wind tunnel wall effects at high Mach numbers

<p>This paper presents the results of an investigation of wind tunnel wall interference in a two-dimensional wind tunnel at high Mach numbers. The results are presented in the form of curves of lift coefficient versus the ratio of model chord to tunnel height, as functions of Mach number and angle of attack. The investigation was carried out by the authors at the Guggenheim Aeronautical Laboratory of the California Institute of Technology during the school year 1944-45.p> <p>Tests were carried out on the NACA low drag airfoil section 65,1-012 at Mach numbers from .60 to .80, and angles of attack of from 1 to 3 degrees. Models were 1", 2", 4" and 6" chord, giving values of the chord to tunnel height ration of .1 to .6. Schlieren photographs were made of shock waves where they occurred.p>

I. Efforts toward the synthesis of aliphatic iodonium salts. II. Flourine-19 nuclear magnetic resonance spectroscopy of cyclic and bicyclic systems

<p>The synthesis of iodonium salts of the general formula [C₆H₅IR]p>+p>Xp>-p>, where R is an alkyl group and x- is a stabilizing anion, was attempted. For the choice of R three groups were selected, whose derivatives are known to be sluggish in S_N1 and S_N2 substitutions: cyclopropyl, 7, 7 -dimethyl-1-norbornyl, and 9 -triptycyl. The synthetic routes followed along classical lines which have been exploited in recent years by Beringer and students. Ultimately, the object of the present study was to study the reactions of the above salts with nucleophiles. In none of the three cases, however, was it possible to isolate a stable salt. A thermodynamic argument suggests that this must be due to kinetic instability rather than thermodynamic instability. Only iodocyclopropane and 1-iodoapocamphane formed isolable iododichlorides.p> <p>Several methylated 2, 2-difluoronorbornanes were prepared with the intent of correlating fluorine -19 chemical shifts with geometric features in a rigid system. The effect of a methyl group on the shielding of a β -fluorine is dependent upon the dihedral angle; the maximum effect (an upfield shift of the resonance) occurs at 0° and 180°, whereas almost no effect is felt at a dihedral angle of 120°. The effect of a methyl group on a γ -fluorine is to strongly shift the resonance downfield when fluorine and methyl group are in a 1, 3 - diaxial-like relationship. Molecular orbital calculations of fluorine shielding in a variety of molecules were carried out using the formalism developed by Pople; the results are, at best, in modest agreement with experiment.p>

Structure theorems for noncommutative complete local rings

<p>If R is a ring with identity, let N(R) denote the Jacobson radical of R. R is local if R/N(R) is an artinian simple ring and ∩N(R)p>ip> = 0. It is known that if R is complete in the N(R)-adic topology then R is equal to (B)_{nb>, the full n by n matrix ring over B where E/N(E) is a division ring. The main results of the thesis deal with the structure of such rings B. In fact we have the following.p> <p>If B is a complete local algebra over F where B/N(B) is a finite dimensional normal extension of F and N(B) is finitely generated as a left ideal by k elements, then there exist automorphisms gib>,...,gk of B/N(B) over F such that B is a homomorphic image of B/N[[x1b>,…,xk;g1b>,…,gk]] the power series ring over B/N(B) in noncommuting indeterminates xib>, where xib = gi(b)xi for all b ϵ B/N.p> <p>Another theorem generalizes this result to complete local rings which have suitable commutative subrings. As a corollary of this we have the following. Let B be a complete local ring with B/N(B) a finite field. If N(B) is finitely generated as a left ideal by k elements then there exist automorphisms g1b>,…,gk of a v-ring V such that B is a homomorphic image of V [[x1b>,…,xk;g1b>,…,gk]].p> <p>In both these results it is essential to know the structure of N(B) as a two sided module over a suitable subring of B. p>}

On the Cesari fixed point method in a Banach space

<p>In a paper published in 1961, L. Cesari [1] introduces a method which extends certain earlier existence theorems of Cesari and Hale ([2] to [6]) for perturbation problems to strictly nonlinear problems. Various authors ([1], [7] to [15]) have now applied this method to nonlinear ordinary and partial differential equations. The basic idea of the method is to use the contraction principle to reduce an infinite-dimensional fixed point problem to a finite-dimensional problem which may be attacked using the methods of fixed point indexes.p> <p>The following is my formulation of the Cesari fixed point method:p> <p>Let B be a Banach space and let S be a finite-dimensional linear subspace of B. Let P be a projection of B onto S and suppose Г≤B such that pГ is compact and such that for every x in PГ, P<sup>-1p>x∩Г is closed. Let W be a continuous mapping from Г into B. The Cesari method gives sufficient conditions for the existence of a fixed point of W in Г. p> <p>Let I denote the identity mapping in B. Clearly y = Wy for some y in Г if and only if both of the following conditions hold:p> <p>(i) Py = PWy.p> <p>(ii) y = (P + (I - P)W)y.p> <p>Definition. The Cesari fixed paint method applies to (Г, W, P) if and only if the following three conditions are satisfied:p> <p>(1) For each x in PГ, P + (I - P)W is a contraction from P<sup>-1p>x∩Г into itself. Let y(x) be that element (uniqueness follows from the contraction principle) of P<sup>-1p>x∩Г which satisfies the equation y(x) = Py(x) + (I-P)Wy(x).p> <p>(2) The function y just defined is continuous from PГ into B.p> <p>(3) There are no fixed points of PWy on the boundary of PГ, so that the (finite- dimensional) fixed point index i(PWy, int PГ) is defined.p> <p>Definition. If the Cesari fixed point method applies to (Г, W, P) then define i(Г, W, P) to be the index i(PWy, int PГ).p> <p>The three theorems of this thesis can now be easily stated.p> <p>Theorem 1 (Cesari). If i(Г, W, P) is defined and i(Г, W, P) ≠0, then there is a fixed point of W in Г.p> <p>Theorem 2. Let the Cesari fixed point method apply to both (Г, W, P<sub>1) and (Г, W, P<sub>2). Assume that P<sub>2P<sub>1=P<sub>1P<sub>2=P<sub>1 and assume that either of the following two conditions holds:p> <p>(1) For every b in B and every z in the range of P<sub>2b>, we have that ‖b=P<sub>2b‖ ≤ ‖b-z‖p> <p>(2)P<sub>2Г is convex.p> <p>Then i(Г, W, P<sub>1) = i(Г, W, P<sub>2).p> <p>Theorem 3. If Ω is a bounded open set and W is a compact operator defined on Ω so that the (infinite-dimensional) Leray-Schauder index i_LS(W, Ω) is defined, and if the Cesari fixed point method applies to (Ω, W, P), then i(Ω, W, P) = i_LS(W, Ω).p> <p>Theorems 2 and 3 are proved using mainly a homotopy theorem and a reduction theorem for the finite-dimensional and the Leray-Schauder indexes. These and other properties of indexes will be listed before the theorem in which they are used.p>

PIXE and ICP-AES analysis of early glass unearthed from Xinjiang (China)

Early glasses (about 1066 BC-220 AD) unearthed from Xinjiang of China were chemically characterized by using PIXE and ICP-AES. It was found that these glasses were basically attributed to PbO-BaO-SiO2 system, K2O-SiO2 system, Na2O-CaO-SiO2 system and Na2O-CaO-PbO-SiO2 system. The results from the cluster analysis showed that some glasses had basically similar recipe and technology. The PbO-BaO-SiO2 glass and the K2O-SiO2 glass were thought to come from the central area and the south of ancient China, respectively. The part of the Na2O-CaO-SiO2 glass (including the Na2O-CaO-PbO-SiO2 glass) might be imported from Mesopotamia, while the other part might be locally produced. (c) 2005 Elsevier B.V. All rights reserved.

Influência da espessura do filme de cimento na resistência adesiva de pinos de fibra de vidro cimentados em condutos radiculares de dentes humanos

O presente estudo visa avaliar a influência da espessura do filme de cimento sobre a resistência de união de pinos de fibra de vidro em diferentes regiões do conduto radicular (cervical, médio e apical), cimentados com cimento resinoso autoadesivo, com e sem a adição de Rodamina B, por meio do teste de push-out. Quarenta raízes foram incluídas em resina epóxi, submetidas a tratamento endodôntico e obturadas com guta percha e cimento endodôntico sem eugenol. Após sete dias, os condutos foram desobstruídos e aleatoriamente divididos em 4 grupos (n=10), de acordo com as brocas do sistema de pinos de fibra WhitePost DC (FGM) usadas: (G1) broca #2; (G2) broca #3; (G3) broca #4; (G4) broca #2. O preparo foi realizado a uma profundidade de 10 mm. A cimentação foi realizada com o cimento resinoso autoadesivo RelyX U100 (3M ESPE), e apenas nos grupos G1, G2 e G3 uma pequena quantidade de Rodamina B em pó foi usada como corante no cimento. Após uma semana, cada raiz foi seccionada em máquina de corte, obtendo-se 6 fatias de 1 0,1 mm de espessura. Antes do ensaio de push-out, imagens digitais foram obtidas, por meio de um estereomicroscópio, de ambas as faces de cada fatia, para determinação do raio dos pinos e da espessura do filme de cimento. Após o ensaio mecânico, novas imagens foram obtidas para determinação do modo de falha. Para determinar a espessura de cimento, foi desenvolvida uma rotina (macro) no software KS 400. Os dados foram estatisticamente analisados com análise de variância (ANOVA) 2 fatores (influência do diâmetro da broca e influência dos terços) e Kruskal-Wallis (influência da espessura do filme de cimento). Comparações múltiplas foram realizadas com o teste Duncan. Todos os testes foram aplicados com α=0,05. Houve diferenças significantes entre os grupos em relação ao diâmetro da broca (p<0,0001), sendo G2 (14,62 5,15 MPa) > G1 (10,04 5,13 MPa) > G3 (7,68 6,14 MPa). O terço do conduto exerceu influência significativa sobre a resistência adesiva (p<0,0001), sendo os maiores valores obtidos no terço apical. As espessuras do filme de cimento foram estatisticamente diferentes nos grupos. Os maiores valores de espessura de cimento foram obtidos no G3 (248,78 μm), seguido de G2 (185,91 μm) e G1 (110,16 μm), sendo o último estatisticamente semelhante ao G4 (119,99 μm). Os resultados de G1(10,04 5,13 MPa) e G4 (8,89 + 5,18 MPa) foram estatisticamente semelhantes, indicando que a presença da Rodamina B não influencia significativamente na resistência de união. O tipo de falha predominante no G1 foi mista, no G2, adesiva entre pino e cimento, e no G3 e G4, adesiva entre cimento e dentina. O diâmetro da broca influenciou significativamente nos resultados de resistência de união ao teste de push-out. O ligeiro aumento na espessura do filme de cimento promoveu um aumento nos valores de resistência, quando comparado com filmes de cimento muito finos ou muito espessos.

Self-organized microvoid array perpendicular to the femtosecond laser beam in CaF2 crystals

Microvoid arrays were self-organized when femtosecond laser beam was tightly focused at a fixed point inside CaF2 crystal sample. Except void array grown below the focal point which had been reported before, we found another void array grown vertical to the laser propagation direction. This result has potential application in the fabrication of integrated micro-optic elements and photonic crystals. The possible mechanism of the phenomenon was proposed and verified experimentally.

Essais d'utilisation de "nourrisseur à la demande" pour l'alimentation de Chrysichthys nigrodigitatus en cage-enclos

An experiment using demand feeder was carried out on the catfish Chrysichthys nigrodigitatus reared in cage-enclosure in the lagoon Ebrié (Côte d'Ivoire). The study lasted 5 months, from October to March, and showed that the demand feeder improves the growth rate of the fish and the feed conversion. It was able, as well as the conventional hand feeding, to show monthly variations of performances.

Strengthening governance across scales in aquatic agricultural systems

Aquatic agricultural systems in developing countries face increasing competition from multiple stakeholders operating from local to national and regional scales over rights to access and use natural resources—land, water, wetlands, and fisheries-essential to rural livelihoods. A key implication is the need to strengthen governance to enable equitable decision-making amidst such competition, building capacities for resilience and transformations that reduce poverty. This paper provides a simple framework to analyze the governance context for aquatic agricultural system development focused on three dimensions: stakeholder representation, distribution of power, and mechanisms of accountability. Case studies from Cambodia, Bangladesh, Malawi/Mozambique, and Solomon Islands illustrate the application of these concepts to fisheries and aquaculture livelihoods in the broader context of intersectoral and cross-scale governance interacti

Cellular and molecular responses of zebrafish to legacy and emerging pollutants: the specific cases of PAHs and metal oxide nanoparticles

270 p.