An approximate solution method for boundary layer flow of a power law fluid over a flat plate

The work in this paper deals with the development of momentum and thermal boundary layers when a power law fluid flows over a flat plate. At the plate we impose either constant temperature, constant flux or a Newton cooling condition. The problem is analysed using similarity solutions, integral momentum and energy equations and an approximation technique which is a form of the Heat Balance Integral Method. The fluid properties are assumed to be independent of temperature, hence the momentum equation uncouples from the thermal problem. We first derive the similarity equations for the velocity and present exact solutions for the case where the power law index n = 2. The similarity solutions are used to validate the new approximation method. This new technique is then applied to the thermal boundary layer, where a similarity solution can only be obtained for the case n = 1.

"Blade Runner" o la pregunta por la dignidad humana

Al pensar en la relación entre el fundamento de la dignidad humana y la resolución de algunos problemas bioéticos, me vino a la cabeza Blade Runner, la película de Ridley Scott basada en un relato de Philip K. Dickque lleva el extravagante título de ¿Sueñan los androides con ovejas eléctricas? (extravagante si vemos la película pero no tanto si leemos el relato)...

Zenith angle distributions at Super-Kamiokande and SNO and the solution of the solar neutrino problem

We have performed a detailed study of the zenith angle dependence of the regeneration factor and distributions of events at SNO and SK for different solutions of the solar neutrino problem. In particular, we discuss the oscillatory behavior and the synchronization effect in the distribution for the LMA solution, the parametric peak for the LOW solution, etc. A physical interpretation of the effects is given. We suggest a new binning of events which emphasizes the distinctive features of the zenith angle distributions for the different solutions. We also find the correlations between the integrated day-night asymmetry and the rates of events in different zenith angle bins. The study of these correlations strengthens the identification power of the analysis.

Fixed-angle elastic hadron scattering

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A new and simple variable-angle accessory for infrared specular reflectance

A simple, low-cost accessory (patent pending) with only two flat mirrors and a new variable-angle mechanism has been developed for infrared specular reflectance measurements. The system allows the angles of incidence to be varied continuously from 15° (near normal incidence) to 85° (near grazing angle) without losing the alignment of the accessory. The reflectivity of boron nitride thin films deposited on metallic substrates has been measured at different angles of incidence to demonstrate the utility of this accessory.

Depinning transition of dislocation assemblies: Pileups and low-angle grain boundaries

We investigate the depinning transition occurring in dislocation assemblies. In particular, we consider the cases of regularly spaced pileups and low-angle grain boundaries interacting with a disordered stress landscape provided by solute atoms, or by other immobile dislocations present in nonactive slip systems. Using linear elasticity, we compute the stress originated by small deformations of these assemblies and the corresponding energy cost in two and three dimensions. Contrary to the case of isolated dislocation lines, which are usually approximated as elastic strings with an effective line tension, the deformations of a dislocation assembly cannot be described by local elastic interactions with a constant tension or stiffness. A nonlocal elastic kernel results as a consequence of long-range interactions between dislocations. In light of this result, we revise statistical depinning theories of dislocation assemblies and compare the theoretical results with numerical simulations and experimental data.

Morphological changes in convection-diffusion-limited deposition

The effect of hydrodynamic flow upon diffusion-limited deposition on a line is investigated using a Monte Carlo model. The growth process is governed by the convection and diffusion field. The convective diffusion field is simulated by the biased-random walker resulting from a superimposed drift that represents the convective flow. The development of distinct morphologies is found with varying direction and strength of drift. By introducing a horizontal drift parallel to the deposition plate, the diffusion-limited deposit changes into a single needle inclined to the plate. The width of the needle decreases with increasing strength of drift. The angle between the needle and the plate is about 45° at high flow rate. In the presence of an inclined drift to the plate, the convection-diffusion-limited deposit leads to the formation of a characteristic columnar morphology. In the limiting case where the convection dominates, the deposition process is equivalent to ballistic deposition onto an inclined surface.

"Blade Runner" o la pregunta por la dignidad humana

Al pensar en la relación entre el fundamento de la dignidad humana y la resolución de algunos problemas bioéticos, me vino a la cabeza Blade Runner, la película de Ridley Scott basada en un relato de Philip K. Dickque lleva el extravagante título de ¿Sueñan los androides con ovejas eléctricas? (extravagante si vemos la película pero no tanto si leemos el relato)...

Analyse de l'angle naso-labial

Nous avons analysé l'angle naso-labial et les différents facteurs qui l'influencent, chez des patients de 9 ans ± 1,4. Nous avons obten u une valeur moyenne de 115,30 ± 10,8. L'inclinaison et la position de l'incisive supérieure et l'angle ANB constituent les facteurs osseux et dentaires qui ont la plus grande répercussion sur l'angle naso-labial. Le sexe et l'age n'ont pas eu d'influences statistiquement significatives sur les résultats. L'incompétence labiale s'est avérée etre la cause d'un angle plus aigu

Analyse de l'angle naso-labial

Nous avons analysé l'angle naso-labial et les différents facteurs qui l'influencent, chez des patients de 9 ans ± 1,4. Nous avons obten u une valeur moyenne de 115,30 ± 10,8. L'inclinaison et la position de l'incisive supérieure et l'angle ANB constituent les facteurs osseux et dentaires qui ont la plus grande répercussion sur l'angle naso-labial. Le sexe et l'age n'ont pas eu d'influences statistiquement significatives sur les résultats. L'incompétence labiale s'est avérée etre la cause d'un angle plus aigu

Electronic properties of a quantum wire with arbitrary bending angle

The electron transmission and bound state properties of a quantum wire with a sharp bend at arbitrary angle are studied, extending results on the right angle sharp bend (the L¿shaped wire). These new results are compared to those of a similar structure, the circular bend wire. The possibility of using a bent wire to perform transistor action is also discussed.

Quantification of the bond-angle dispersion by Raman spectroscopy and the strain energy of amorphous silicon

A thorough critical analysis of the theoretical relationships between the bond-angle dispersion in a-Si, Δθ, and the width of the transverse optical Raman peak, Γ, is presented. It is shown that the discrepancies between them are drastically reduced when unified definitions for Δθ and Γ are used. This reduced dispersion in the predicted values of Δθ together with the broad agreement with the scarce direct determinations of Δθ is then used to analyze the strain energy in partially relaxed pure a-Si. It is concluded that defect annihilation does not contribute appreciably to the reduction of the a-Si energy during structural relaxation. In contrast, it can account for half of the crystallization energy, which can be as low as 7 kJ/mol in defect-free a-Si