In this paper the finite-difference time-domain (FDTD) method is reviewed and then used to model and predict the geometric parameters used for the design of the device. The waveguide consists of a periodic array of air gap etched into a silicon (Si) strip on a silicon dioxide (SiO2) layer. The width and the depth of the grooves of the air gap (n = 1) as well as the length of the silicon layer (n = 3.4) are investigated. Using FDTD, the optical parameters are characterized. The effect of the air gap on the field profile distribution of the whole structure is calculated and performed in the range 0.09687 μm –1.55 μm. The field profile, and the response of the microcavity against frequency are calculated from sinusoidal sources. The spectral behavior of the structure is performed and its validity is verified by calculation of the reflectance spectra.

In this paper we have studied the contribution of reversed shear in reducing the anomalous transport in a Tokamak using both an analytical approach and simulations. We have used a special model for the drift wave fields. Comparison between particles trajectories for normal and negative shear is carried out. The diffusion coefficient of particles for the two cases; normal and reversed shear is evaluated.

Electrical properties of a device depend primarily on the active dopant concentration; understanding of the activation (annealing) process is crucial for the prediction of device behaviour. The present paper reports results from a computer based simulation approach to improve the breakdown performance of the device by studying the annealing behaviour of boron implanted in silicon. In order to have deep insight of the effect of defect complexes on the device performance, extended defect model has been incorporated in the simulation program. Optimization of annealing time, annealing temperature and dose has been performed, for the first time, incorporating a complete set of process induced defects like {113} defects, interface traps, dislocation loops and the optimization has been validated in terms of the breakdown performance of the device.

An ultrasonic method using a large bandwidth transducer with a spherical lens and based on acoustic waves separation near the focal region is presented. The aim of this technique is to reduce the investigation size for non destructive mechanical properties evaluation. Compared to traditional acoustic microscopy (acoustic signature) the size of the analysed zone on the sample has been highly reduced. For instance, this technique has been applied on an aluminium sample with an acoustic frequency of 15 MHz. The Rayleigh wave velocity has been measured individually on grains smaller than one millimetre. Such local measurements would have required an acoustic lens working at higher frequency. All the efficiency of our experimental method and numerical signal processing has been proved by conclusive experiments on different materials such as glass, steel, silicon and uranium dioxide at different frequencies. This new method has also been tested at 100 MHz and we have demonstrated that its resolution was similar to performances of higher frequency acoustic microscopy working around 500 MHz. Furthermore our study shows that with this microdefocusing method, it is possible to assess directly from the same acquisition data Rayleigh, longitudinal and transverse velocities and consequently the elastic properties.

From the Helmholtz free energy, the pressure, the mole fraction, the internal energy and the specific heat capacity at constant volume in temperature range of 1 000 to 20 000 K in the plasma formed of insulator vapours of PC and POM for various densities (0.05 kg/m3 to 5 kg/m3) and at LTE are calculated. The virial and Debye-Hückel corrections on pressure are discussed. The graphite formation is studied.

The effect of inter particle collisions on a “kinematic” shock wave produced by a velocity gradient in a cold atomic gas is studied, to the end of establishing a connection between such kinematic shocks and the “traditional” fluid dynamic shock front. In order to include the collisional effects we use both a DSMC (Direct Simulation Monte Carlo) model and a Monte Carlo solution of the Bhatnagar-Gross-Krook equation (BGK/MC). The substantial agreement of DSMC and BGK/MC results for a sufficiently high value of the collision frequency proves that the kinematic and thermodynamic descriptions of the shock front can be smoothly joined by scaling this parameter.

The purpose of the present study was to apply knowledge of structural properties to perform numerical simulations with models of bones and knee ligaments exposed to dynamic tensile loading leading to tissue damage. Compact bones and knee ligaments exhibit the same geometrical pattern in their different levels of structural hierarchy from the tropocollagen molecule to the fibre. Nevertheless, their mechanical behaviours differ considerably at the fibril level. These differences are due to the contribution of the joints in the microfibril-fibril-fibre assembly and to the mechanical properties of the structural components. Two finite element models of the fibrous bone and ligament structure were used to describe damage in terms of elastoplastic laws or joint decohesion processes.

The main factors limit the field of the magnetic lenses are the current density σ and the accelerating voltage Vr. Optical properties such as chromatic and spherical aberration have been studied in terms of σ and Vr. Values of the other aberration coefficients for the optimum lens size corresponding to the desired minimum aberration are estimated.

With a laboratory built X-ray microscope, analysis of a thermal diffusion process in a KBr solution has been performed. A solution of a salt submitted to a constant temperature gradient gives rise to a stationary concentration gradient of the species after a few hours: this is the so called Soret effect. From the digital image of the liquid, acquired in the steady state of the process, it is easy to obtain the concentration map of the species in the solution. The average concentration profile then deduced permits to reach the value of the Soret coefficient and the heat of transport of the binary compound. X-ray radiography is an alternative powerful technique to analyse this kind of complicated phenomenon where composition matter fluxes are driven by both temperature and composition gradient.

A new approach to determine the displacement field between a reference and a deformed image is introduced. The method is based on a spectral decomposition of the displacement field which is determined through a multi-scale approach. The method is tested here on an artificial example by using computer-generated images devoid of boundary effects (i.e., periodic boundary conditions are used in the image texture and displacement field). The performance of the proposed algorithm allows for the determination of the prescribed displacement field up to machine precision, for a strain field whose trace extends from −50% to 40% with a root-mean-square average of 15%, within sub-minute runs on a standard PC.

A simple EDXRF technique to obtain the relative concentrations of different elements present in a sample is described here. Only those elements have been considered whose characteristic X-rays fall within the sensitivity range of the X-ray detector that we used. A small computer program where the fundamental parameters such as photoionisation cross sections, fluorescence yields, Coster-Kronig transition rates, etc. have been used as inputs was written to calculate the relative concentrations of the elements. The technique used here requires only a single run with the sample and does not require any knowledge of the incoming X-ray flux or geometry of the experimental arrangement. Using this method, three alloys have been analysed in our existing EDXRF system.