Turbulent free convection above a heated plate inclined at a small angle to the horizontal Journal

An investigation has been made of the structure of the motion above a heated plate inclined at a small angle (about 10°) to the horizontal. The turbulence is considered in terms of the similarities to and differences from the motion above an exactly horizontal surface. One effect of inclination is, of course, that there is also a mean motion. Accurate data on the mean temperature field and the intensity of the temperature fluctuations have been obtained with platinum resistance thermometers, the signals being processed electronically. More approximate information on the velocity field has been obtained with quartz fibre anemometers. These results have been supplemented qualitatively by simultaneous observations of the temperature and velocity fluctuations and also by smoke experiments. The principal features of the flow inferred from these observations are as follows. The heat transfer and the mean temperature field are not much altered by the inclination, though small, not very systematic, variations may result from the complexities of the velocity field. This supports the view that the mean temperature field is largely governed by the large-scale motions. The temperature fluctuations show a systematic variation with distance from the lower edge and resemble those above a horizontal plate when this distance is large. The largescale motions of the turbulence start close to the lower edge, but the smaller eddies do not attain full intensity until the air has moved some distance up the plate. The mean velocity receives a sizable contribution from a ‘through-flow’ between the side-walls. Superimposed on this are developments that show that the momentum transfer processes are complex and certainly not capable of representation by any simple theory such as an eddy viscosity. On the lower part of the plate there is surprisingly large acceleration, but further up the mixing action of the small eddies has a decelerating effect.

快速固化环氧-环硫树脂体系的研究

本文系统地研究了环氧-环硫-N,N-二甲基苄胺固化体系。结果认为,凝胶时间随环硫-环氧比的提高而线性降低。加入环硫树脂可减轻环氧树脂的应力集中,提高环氧树脂的使用温度。环硫树脂在三个方面加速环氧树脂的固化,即起催化作用,加速引发和共聚合。

Estudio interdisciplinar de la Comuniad de Madrid en el ciclo medio.

Pretende aumentar la participación del alumnado en su entorno mostrando la realidad social como un todo interrelacionado. Los objetivos son: preparar personas capaces de participar en la vida social, presentar al alumnado su entorno como una realidad en la que se puede actuar para mejorarlo, interesar al alumnado en el aprendizaje activo, reflexionar sobre el medio ambiente y la posibilidad de mejorar su calidad a través de su participación, lograr la participación de la comunidad educativa. La metodología es activa e interdisciplinar, basada en el aprendizaje por descubrimiento de forma que el alumnado realice sus propias investigaciones (observaciones, experimentos, consultas, etc.) reúna y ordene los datos obtenidos y establezca relaciones entre ellos.

Rapid preconditioning of data for accelerating convex hull algorithms

Given a dataset of two-dimensional points in the plane with integer coordinates, the method proposed reduces a set of n points down to a set of s points s ≤ n, such that the convex hull on the set of s points is the same as the convex hull of the original set of n points. The method is O(n). It helps any convex hull algorithm run faster. The empirical analysis of a practical case shows a percentage reduction in points of over 98%, that is reflected as a faster computation with a speedup factor of at least 4.

Synthesis and structural characterization of a new polymeric zinc(II) complex with thiophene-2-carboxylic acid

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

La apariencia industrial. Las townhouses en Lafayette Park de Mies van der Rohe = The industrial appearance. Townhouses in Lafayette Park by Mies van der Rohe

La apariencia industrial. Las townhouses en Lafayette Park de Mies van der Rohe = The industrial appearance. Townhouses in Lafayette Park by Mies van der Rohe