Preparation,characterization and evaluation of the catalytic power of an hybrid compound [H3PMo12O40-chitosan] for the azoic-colored solutions

Inorganic–organic hybrid structures have become novel alternatives for many applications as they combine the advantages of both systems. In this current study, a hybrid compound [H₃PMo₁₂O₄₀-chitosan] was prepared using a wet impregnation method with different proportions (0-100 wt. %, considering the polymer as the main component). The chemical structure and the morphology of the synthesized compounds were studied using FT-IR and SEM. Their catalytic powers were evaluated for Naphtol Blue Black and Eriochrome Blue Black B. Experimental data revealed that the decolorization phenomenon depends on the structure of the dye it-self, the pH value, the initial dye concentration, the time contact, the oxidant dose and the temperature. Kinetic data, well described using the first order model, allowed us to establish the thermodynamic parameters. The calculated low values of Ea (7.48 and 8.14 KJ. mol-1) proved the efficiency of the prepared catalyst. Eriochrome Blue Black B could be decomposed more rapidly than Naphtol Blue Black. As example, after a period of 30 min of reaction, the target removals were, respectively, 70% and 15% for mono and bi-azoic dyes. The reuse of the catalyst is carried out and it was found to be recyclable more than three consecutives cycles.     

Fleece Production,Scouring Yield,and Down Hair Yield of Tunisian Dromedary

The results show that the greasy fleece weight varied from 0.3 kg to 2.42 kg with an average of 0.75 kg. The fleece weight decreases according to the animal age. In fact, the factor “age” has a significant effect on the dromedary fleece weight. Average scoured yield was 96% with V% of 1.6%. This indicated that matter loss, after scouring dromedary fibres, was lower than wool and cashmere. Scoured yield did not vary between samples of varied dromedary body areas in any age. The down hair yield for the fleece of the Tunisian dromedary varies between 34% and 61% with a mean of 45%. This raises interest when compared to the cashmere yield. There is a clearly decreased dromedary down hair yield according the factor “age”. The analysis of the variance shows that the dromedary down hair yield was affected by the factors “age” and body area of the animal.

Following this work it will be possible to predict the amount of down yield in the fleece of Tunisian dromedary knowing age. Consequently, it will be possible to estimate the total amount of textile material camel from dromedary located in Tunisia.     

Iron(III) and Cobalt(III) Complexes with Oxalate and Phenanthroline: Synthesis,Crystal Structure,Spectroscopy Properties and Magnetic Properties

We report herein the synthesis and physicochemical characterization of two mixed-ligand complexes of the following stoichiometric formulae: [Fe(phen)₂(ox)](NO₃)?2H₂O (1) and [Co(phen)₂(ox)](NO₃)?4H₂O (2) (as phen: 1,10-orthophenanthroline; ox: oxalate dianion). Both compounds have been prepared by slow evaporation at room temperature and characterized by single-crystal X-ray diffraction. They have been characterized by IR and UV–Vis spectra and thermoanalysis (TG and DTA) The structures of these compounds are highly symmetric. Indeed, the two compounds are isomorphous and crystallize in the orthorhombic space group Ibca. In each material, the M^III ion has a slightly distorted square bipyramidal environment, coordinated by one oxalate ion and two 1,10-orthophenanthroline ligands. Structural cohesion is established essentially by π–π interactions between the rings of phen groups and intermolecular O–H…O hydrogen bonds connecting the ionic entities and uncoordinated water molecules. Magnetic susceptibility measurements of (1) in the range 5–300 K exhibit paramagnetic behavior at high temperature. However, at low temperature, the magnetic data show the occurrence of weak antiferromagnetic intermolecular interactions between the local spins.     

Secondary defect profile related to low energy implanted boron measured up to 3.5 µm depth into Si-substrates

Low energy implantation is one of the most promising options for ultra shallow junction formation in the next generation of silicon BiCMOS technology. Among the dopants that have to be implanted, boron is the most problematic because of its low stopping power (large penetration depth) and its tendency to undergo transient enhanced diffusion and clustering during thermal activation. This paper reports an experimental study of secondary defect profiles of low energy B implants in crystalline silicon. Shallow p⁺n junctions were formed by low energy B implantation—10¹⁵ cm⁻² at 3 keV—into a reference n-type crystalline silicon or pre-amorphized n-Si with germanium −10¹⁵ cm⁻² at 30 keV, 60 keV, and 150 keV. Rapid Thermal Annealing (RTA) for 15 s at 950°C was then performed. Secondary defect profiles induced by this process are measured with isothermal transient capacitance in association with Deep Level Transient Spectroscopy (DLTS). Relatively high concentrations of electrically active defects have been obtained up to 3.5 μm into the crystalline silicon bulk. The relation of these defects with boron is discussed. The results of this study are in agreement with boron transient enhanced diffusion in Si-substrate as has been reported by Collart using Secondary Ion Mass Spectrometry (SIMS) measurements.     

Research of critical causes and improvement of energy storage system reliability in power electronic applications

In order to prevent the critical failures in lead acid batteries, the authors propose a new multistep current charge profile based on mathematical methods to calculate the charge current for each step according to the battery voltage variations and state of charge. The energy management system is developed in order to avoid the deep discharge that causes stratification of electrolyte, sulfating and deterioration of active mass. In addition, the electrodes corrosion and gassing phenomena are prevented by adopting a suitable charge cycle. In this paper, the causal tree analysis is used to identify the critical failure modes of battery and their causes in different applications such as uninterruptible power supply, renewable energy and hybrid electric vehicle. The identification of the degradation causes allows properly proposes some recommendations in order to extend the battery lifetime by adding suitable additives in the manufacturing process and adopting an appropriate charge cycle. The experimental result of the multistep current profile is realized with lead acid battery 90 Ah to investigate their efficiency to ensure the maximum battery reliability. This current profile avoids the corrosion phenomenon generated by overcharge and the sulfating phenomenon caused by an incomplete charge with a charging time depends on the number of the chosen step. Therefore, the multistep current profile is a suitable charge cycle that preserves the battery capacity and increases its lifetime.     

Experimental study of metal–hydrogen reactor behavior during desorption under heating by electromagnetic induction

The objective of this work is to study experimentally the behavior of a metal–hydrogen reactor (MHR) during hydrogen desorption by the LaNi₅ hydride. The reactor is surrounded by a small coil traversed by an alternative sinusoidal current. The effect of the voltage applied to the coil is studied. Two kinds of tests are done. In the first one, the reactor is heated to the desired temperature and then it was put in contact with a tank at weak pressure (desorption), and in the second one, desorption and heating start simultaneously. Desorbed mass and temperature evolution within the hydride bed and in the reactor wall, as a function of time, are plotted. A comparison of results obtained by the electromagnetic induction heater and by heat exchanger provisioned by a hot fluid shows an improvement of the efficiency of the reactor when compared to the traditional hot system (fluid system).     

Formation of machine groups and part families in cellular manufacturing systems using a correlation analysis approach

The important step in the design of a cellular manufacturing (CM) system is to identify the part families and machine groups and consequently to form manufacturing cells. The scope of this article is to formulate a multivariate approach based on a correlation analysis for solving cell formation problem. The proposed approach is carried out in three phases. In the first phase, the correlation matrix is used as similarity coefficient matrix. In the second phase, principal component analysis (PCA) is applied to find the eigenvalues and eigenvectors on the correlation similarity matrix. A scatter plot analysis as a cluster analysis is applied to make simultaneously machine groups and part families while maximizing correlation between elements. In the third stage, an algorithm is improved to assign exceptional machines and exceptional parts using respectively angle measure and Euclidian distance. The proposed approach is also applied to the general group technology (GT) problem in which exceptional machines and part are considered. Furthermore, the proposed approach has the flexibility to consider the number of cells as a dependent or independent variable. Two numerical examples for the design of cell structures are provided in order to illustrate the three phases of proposed approach. The results of a comparative study based on multiple performance criteria show that the present approach is very effective, efficient and practical.     

Fast coding unit partitioning method based on edge detection for HEVC intra-coding

High efficiency video coding (HEVC) standard is the latest video coding standard generation. It employs powerful coding tools to obtain improved compression efficiency. To better exploit the redundancies, HEVC adopts a very flexible quad-tree coding structure, allowing the encoder to use a block partition that matches the image features. This exhaustive technique may achieve a higher coding efficiency; however, it induces a significant computational complexity in the encoding engine. This paper proposes a new texture parameter for classifying digital videos as a first contribution and then introduces an efficient coding unit (CU) partitioning algorithm based on the early defined texture parameter in order to speed up the encoding process. In fact, the proposed technique is based on edge detection by performing SOBEL filtering in order to decide the appropriate CU size. Compared to the original HEVC, the average execution time-saving is about 31 % while maintaining almost the same output video quality.