The structural and electronic properties of ScSb, ScAs, ScP and ScN III -V materials are investigated within a version of the first-principles full potential linear muffin-tin orbitals method (FPLMTO) that enables an accurate treatment of the interstitial regions. At high pressure, the transition from rocksalt (B1) to CsCl (B2) structure is found to be possible. The zinc blende phase is also investigated and is found to give a semiconductor behavior with a wide bandgap to all our materials. The latter is direct at X for ScAs, ScSb, ScP.

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Assuming local thermodynamic equilibrium (LTE), the total radiation which escapes from a - plasma is calculated in the temperature range between 5000 and 30 000 K. The evaluation of the net emission coefficient is performed by solving the radiative transfer equation in a cylindrical isothermal plasma taking into account line broadening phenomena. The radiation emission of methane depends mainly on the carbon species, whereas the presence of hydrogen in the mixture leads to a radiation decrease especially at high temperatures.

A new method of contrast enhancement based on steerable pyramid transform is presented in this work. The use of steerable filters is motivated by the fact that the images are to be observed by human and therefore it would be better to incorporate some knowledge on the Human Visual System in the design of the image processing tool. Here, the frequency and directional selectivity of the HVS is modeled by the steerable filters. The contrast is amplified using a selective nonlinear function which simulates the nonlinearity response of the HVS to the luminance stimuli. So the basic idea is to enhance the luminance signal irrespective of the two chrominance components using a multidirectional and multiscale decorrelation color transform. Initially the r gb (red, green and blue) color image is converted to lab (luminance and chrominance) color image. Only the luminance component is transformed by the steerable pyramid transform, so that the luminance component is independently decomposed into different scale and orientation sub-bands. The contrast in each sub-band is enhanced using a nonlinear mapping function. Finally the r gb color image is obtained from the enhanced luminance component along with the original chrominance components. The performance of the proposed method is objectively evaluated using spectrum energy analysis and a visibility map based on a perceptual filtering model. The obtained results confirm the efficiency of the method in enhancing subtle details without affecting color balance and without the usual noise amplification and edge ringing effect.

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