Investigation to define the propagation characteristics of a finite amplitude acoustic pressure wave Final report

Aerodynamic noise generation by finite amplitude pressure wave propagation through entropy producing region

Investigation to define the propagation characteristics of a finite amplitude acoustic pressure wave

A theoretical analysis of the propagation characteristics of a finite amplitude pressure wave is presented. The analysis attempts to study the contribution of entropy-producing regions to the mechanism of aerodynamic noise generation. It results in a nonlinear convective wave equation in terms of entropy and a thermodynamic 'J' function. A direct analogy between the derived governing equation and those used in classical literature is obtained. An idealization of the processes considered permits the uncoupling of the equations of motion with a consequent construction of an acoustic analogy treating shock wave emission of finite amplitude acoustic waves. An engineering approach is reflected in the concept of an extended plug nozzle whose function is to facilitate aerodynamic noise attenuation by modifying the entropy-producing regions

Working times in atypical forms of employment: the special case of part-time work

Chapitre 5, à la suite de la conférence ACSEG 2001 à RennesIn the present article, we attempt to devise a typology of forms of part-time employment by applying a widely used neuronal methodology called Kohonen maps. Starting out with data that we describe using category-specific variables, we show how it is possible to represent observations and the modalities of the variables that define them simultaneously, on a single map. This allows us to ascertain, and to try to describe, the main categories of part-time employment

電腦與香港法律研究

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Observation of accelerating parabolic beams

We report the first observation of accelerating parabolic beams. These accelerating parabolic beams are similar to the Airy beams because they exhibit the unusual ability to remain diffraction-free while having a quadratic transverse shift during propagation. The amplitude and phase masks required to generate these beams are encoded onto a single liquid crystal display. Experimental results agree well with theory

The Politics of Succession in Hong Kong

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Globular Cluster Formation in M82

We present high resolution mid-infrared (mid-IR; 11.7 and 17.65 micron) maps of the central 400 pc region of the starburst galaxy M82. Seven star forming clusters are identified which together provide ~ 15% of the total mid-IR luminosity of the galaxy. Combining the mid-IR data with thermal radio measurements and near- and mid-IR line emission, we find that these young stellar clusters have inferred masses and sizes comparable to globular clusters. At least 20% of the star formation in M82 is found to occur in super-star clusters.Comment: 12 pages including three color figures; accepted for publication in Ap