Structural and frequency dependencies of a.c. and dielectric characterizations of epitaxial InSb-based heterojunctions

In this work, heterojunction of InSb/InP was grown by liquid phase epitaxy (LPE). Surface morphology and crystalline structure of the heterojunction were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The frequency and temperature dependences of a.c. conductivity and dielectric properties of the heterojunctions were investigated in the ranges of 100 kHz–5 MHz and 298–628 K, respectively. The a.c. conductivity and its frequency exponents were interpreted in terms of correlated barrier hopping model (CBH), as the dominant conduction mechanism for charge carrier transport. The calculated activation energy, from the Arrhenius plot, was found to decrease with increasing frequency. Experimental results of both dielectric constant ε ₁ and dielectric loss ε ₂ showed a remarkable dependence of both frequency and temperature.     

HOW TO USE FLUIDIZATION TO OBTAIN DRYING KINETICS COUPLED WITH QUALITY EVOLUTION

Abstract

This paper presents the main activities of the Gas Fluidization and Drying Team of the Chemical Engineering Laboratory at Toulouse. The emphasis has been put on the modeling of a fluidized bed dryer and its derivates such as a flotation fluidized bed, by the analysis of heat and mass transfer together with the physico-chemical transformations of the product during drying. Several studies have been performed on different solids (cereal and chemical products) to illustrate the effect of the operating conditions on dehydration and degradation kinetics The knowledge of heat and mass transfer coefficients in flotation fluidized bed allows to determine intrinsec drying and degradation kinetics. These kinetics can be used in any conductive or convective drier model.     

Immunogenicity and Allergenicity of Whey Protein Hydrolysates

Allergic reactions to cow's milk are common in children. The sera of allergic subjects have been found to contain specific IgE antibodies against several whey proteins such as α-lactalbumin (α-la) and β-lactoglobulin (β-lg). This work aims to study the effect of hydrolysis on the immunogenicity and the allergenicity of α-la and β-lg. Whey proteins were submitted to hydrolysis with immobilized α-chymotrypsin. High performance liquid chromatography analysis showed a decrease of native whey proteins and the appearance of low molecular weight peptides. The immunogenicity of these hydrolysates was not modified, but their allergenicity, as assessed by RAST inhibition, was decreased. The results may have important clinical implications.     

Electrocardiogram de-noising based on forward wavelet transform translation invariant application in bionic wavelet domain

In this paper, we propose a new technique of Electrocardiogram (ECG) signal de-noising based on thresholding of the coefficients obtained from the application of the Forward Wavelet Transform Translation Invariant (FWT_TI) to each Bionic Wavelet coefficient. The De-noise De-noised ECG is obtained from the application of the inverse of BWT (B W T ^?1) to the de-noise de-noised bionic wavelet coefficients. For evaluating this new proposed de-noising technique, we have compared it to a thresholding technique in the FWT_TI domain. Preliminary tests of the application of the two de-noising techniques were constructed on a number of ECG signals taken from MIT-BIH database. The obtained results from Signal to Noise Ratio (SNR) and Mean Square Error (MSE) computations showed that our proposed de-noising technique outperforms the second technique. We have also compared the proposed technique to the thresholding technique in the bionic wavelet domain and this comparison was performed by SNR improvement computing. The obtained results from this evaluation showed that the proposed technique also outperforms the de-noising technique based on bionic wavelet coefficients thresholding.     

ON THE PROBABILITY/POSSIBILITY TRANSFORMATIONS:A COMPARATIVE ANALYSIS

In this paper, we investigate some of the most common probability/possibility transformations found in the literature. Some meaningful criteria, on which the performance of these transformations are evaluated and compared, will be proposed. It concerns respectively the specificity order, i.e., the specificity value of the resulting distributions, the strength of the preference preservation, or in other words, how is the behavior of the result when initial points are close to each other with some strength or according to some function. The third one is related to the result of the transformation where initial distribution tends towards the ignorance state. Finally, we study the influence of incomplete data (subnonnal distribution) to the result of each transformation. This analysis will be illustrated with some theoretical foundation and followed with some numerical examples.     

A New Correlation for the Estimation of Moisture Diffusivity in Corn Kernels from Drying Kinetics

ABSTRACT

The modelisation of cereal drying kinetics is more, and more often performed by the diffusion equation (Fick's law) Eor homogeneous materials rather than lumped or semi-empirical equations. The heterogeneity of the material is accounted for by the use of an effective diffusivity the prediction of which is essential for the determination of the functional relationship between diffusion coefficient and arain moisture content and temperature. For this dependence, the method of resolution may be analytical or numerical. In this study, the estimation of diffusion coefficient is based on drying curves obtained with arains in the ranae of initial moisture content of 18-509 and a temperature of 50:120??. The important result corresponds to the finding that the moisture diffusivity is a function not only of variabies of the state i.e. moisture content and temperature, but also of the initial moisture content as in the following : 'D = P4g X, exp(8 X ). AD and B are both dependent on temperature     

Determination of paper filler Z-distribution by low-vacuum SEM and EDX

Paper, mainly constituted of cellulose fibres, often contains mineral fillers. These fillers increase some of the properties of the paper (whiteness, printability, etc.) and are cheaper than the cellulose fibres. Nevertheless, the fillers reduce the mechanical properties of the sheet. Paper presents an anisotropy corresponding to three main directions. This anisotropy characterises the sheet mechanical properties, structure and filler distribution. Analyses of the cross section of the paper sheet with a low‐vacuum scanning electron microscope with an energy dispersive spectrometer analysis module can show this distribution. The procedure developed consists in analysing discrete profiles to build the mean profile known as filler Z‐distribution for each of the fillers. To develop this method, problems such as determination of the surface points, the number of points to analyse to define a cross section profile and the time required for the test, have been solved. Paper is sensitive to electron irradiation. In order to avoid deterioration of the material and to obtain satisfactory results, the time span for analyses is restricted to 40 s with a 12 kV electron beam accelerating voltage. Monte Carlo simulations are used to determine the diffusion cloud size and thus to determine the number of points that constitute a profile. The samples are gold sputtered and, with the aid of backscattered imaging, the coated surface allows determination of the sample surface points.