Etude des ondes rampantes sur un corps convexe vérifiant une condition ďimpédance par une méthode de développement asymptotique

We study the creeping waves propagating on a convex object, whose surface impedance is Z. To this end, we seek, by using an asymptotic expansion method, a solution of Maxwell equations, propagating along a geode sic, and satisfying Silver-Müller radiation condition at infinity, and the impedance boundary condition at the surface of the body. By using a geodesic coordinate system suited to the problem, we obtain a closed form solution. The electric and magnetic fields are given in term of the components of these fields along the binormal to the geodesic. We show that two types of creeping waves exist: the electric (resp. magnetic) type, with a non zero binormal component of the electric (resp magnetic) field. They are uncoupled, except in the vicinity of Z = 1, where a rotation of the polarization, similar to Rytov’s law, is evidenced.     

Hemispheric contributions to nonverbal abstract reasoning and problem solving.

Hemispheric involvement in reasoning abilities has been debated for some time, and it remains unclear whether the right hemisphere's involvement in problem solving is modality specific or dependent on the type of spatial reasoning required. In the current study, 2 types of nonverbal reasoning abilities were examined, spatial reasoning and proportional reasoning, in 109 patients with cerebrovascular disease that was confined to either the right or the left hemisphere or was diffuse in nature. Results indicated that no lateralizing effects were present based on type of spatial reasoning. Findings are consistent with the suggestion that higher order cognitive processes involved in nonverbal abstraction and problem solving are not strongly lateralized to the right hemisphere but rather are more generally distributed throughout the cortex. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A new minimum zone method for evaluating flatness errors

A new minimum zone method for flatnes error analyis is proposed in this article. Based on the criteria for the minimum zone solution and strict rules for data exchange, a simple and rapid algorithm, called the control plane rotation scheme, is developed for the flatness analysis of a flat surface. Experimental work was performed, and some examples are given in terms of the minimum zone and least-squares solutions.     

Electronic properties of CuO2 planes

We study a 3-band model of CuO₂ with “bare bones” interactions: hopping from copper ions to nearest-neighbor oxygenst _pd only, a two-body interaction on the copper ionsU _dd only, and an overlap copper-oxygen parameter λ_pd. In the limitt _pd ∝U _dd ^1/2→∞, t^*=t _pd ²/2U _dd is the unit of energy with 8λ_pd ² as the only parameter of significance. If the two-body interaction is invariant under particle-hole interchange, the low-lying states (energy O(t^*)) can be described by conserved particles and can all be classified. They are quite distinct from the high-lying states (energies O(U _dd)). The dynamics of the conserved fermion-like elementary particles are well described by a modifiedt-J model with extended hopping and nearest-neighbor superexchange attraction. This is a scenario known to be favorable to high-temperature superconductivity, but it must be noted that both the hopping range and the exchange are functions of 8λ_pd ². Moreover, if the Hamiltonian isnot invariant under particle-hole interchange the dynamics becomes much more complex and possibly more inimical to high-temperature superconductivity. This may provide an explanation for the deleterious effect on superconductivity of very small concentrations of certain impurities.     

Combustion synthesis of advanced materials: Part I. Reaction parameters

An explanation of combustion (self propagating high temperature) synthesis (SHS) is given together with a historical perspective of the examination of such exothermic reactions. The application of thermochemical functions has been used to predict theoretically the maximum adiabatic temperature, T_ad. This, combined with a knowledge of the ignition temperature, T_ig, and the actual combustion temperature, T_c, has been used to determine the heat loss from the SHS reaction and the amount of heat needed to raise the adjacent, cold, reactant layer to the ignition temperature in order to maintain the self sustaining nature of the propagating mode of the reaction. The pertinent reaction parameters that control self propagating high temperature (combustion) synthesis reactions have been examined. These include: reactant particle size and shape; powder mixing and compaction; green density; reaction stoichiometry; impurities; volatiles and diluents; reaction environment; mode and technique of ignition; heating rate; and the effect of these parameters on the generation of heat, exothermicity and control of the SHS reaction.     

Analysis of the effect of shrinkage on macrosegregation in alloy solidification

Numerical calculations based on a continuum model are used to examine the effects of solidification shrinkage on the redistribution of solute in a Pb-19.2 pct Sn mixture which is convectively cooled at a sidewall. For each of three different cooling rates, separate calculations are performed for shrinkage and buoyancy-induced flows, as well as for the combined influence of shrinkage and buoyancy effects. The calculations reveal that flow and macrosegregation patterns are more strongly influenced by buoyancy effects over a wide range of solidification rates. Although extremely large solidification rates yield small regions near the chilled wall in which shrinkage-induced flows control the redis-tribution of solute, the overall effect on macrosegregation is small relative to that associated with buoyancy. Scaling analysis of the governing equations produces reference shrinkage and buoyancy velocities which can be used to extend the current numerical results to other binary systems.     

Comparisons of taste perceptions and preferences of Japanese and Australian consumers: overview and implications for cross-cultural sensory research

A program of research that compared the taste perceptions and preferences of Japanese and Australian consumer panels is reviewed from the point of view of the general issues that have emerged. These studies revealed few cross-cultural differences in the perceptions of the panels, implicating an important role for dietary experience in differences in preference. There was also little evidence for cross-cultural influences on panellists' assessment behaviour, such as scale usage. Studies of predominantly sweet and salty foods from both Australia and Japan illustrated the importance of familiarity with the overall product as an influence on the assessment of individual sensory characteristics. Subsequent attempts to overcome this influence by comparing cross-cultural responses to the manipulation of tastes within foods common to both cultures revealed no differences in the optimum tastant level within each of the foods. The implications of these studies for future cross-cultural research is addressed, and it is argued that future studies need to develop methods for determining the acceptability of relatively novel foods specifically developed for export markets, and also to address the complexity of food preferences from the point of view of both sensory and non-sensory influences.     

Response spectrum analysis of piping systems with elastic-plastic gap supports

A new seismic support device and its application in piping systems is described. The device, E-BAR (patented), can be cost effectively used for snubber replacement programs, mitigation of hydraulic transients, pipe whip and as a thermal stop. The device has pre-set gaps to allow free thermal movement. During a seismic or other dynamic load event, if the pipe movement exceeds the gap dimension, the device acts as an elastic or elastic-plastic restraint. The device also has a unique design feature for not exceeding the restraint force beyond a specified limit design value. To analyze piping systems with gap supports having elastic-plastic characteristics, modal analysis procedures for both response spectrum and time history methods are developed. The comparison of responses obtained from the procedures with nonlinear time history analysis and test results available in the literature shows excellent correlation. A pilot program conducted for snubber replacement with E-BARs demonstrates that the limit force feature of E-BAR makes them very attractive for snubber replacement. This is because a particular E-BAR with a specified limit design force can be selected, such that, the E-BAR replacing the snubber does not require any modifications be made to the existing support steel and hardware.