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).     

Cellular reuse patterns quality and efficiency comparison

Capacity enhancement and interference performance are among the most important issues in the 2nd and 3rd generation cellular networks planning. The main objective of the planning process is to reach a tradeoff between the quality and the capacity of the network. In this paper, we study and compare the CIR and spectral efficiency of different cellular reuse patterns. We also establish the exact analytical PDF expression of CIR assuming one interferer in the serving cell, we then generalize this expression to many interferer tiers. Shadowing effect is also carefully considered in the CIR distribution extension. Moreover, numerical computations are performed to estimate spectral efficiency values for the different patterns studied. Some simulations are also developed to give the comparison a concrete and a practical aspect. A reuse partitioning (RP) capacity scheme is used to serve as the basis of the study. In particular, RP sub‐cells' sizes and number of partitions are optimized in order to maximize the traffic capacity parameterized by spectral and trunking efficiency while involving the financial cost. The efficiency/cost comparison is among the main novel issues contributed by the paper. Copyright © 2006 John Wiley & Sons, Ltd.     

Fatty acids, 4‐desmethylsterols,and triterpene alcohols from Tunisian lentisc (Pistacia lentiscus) fruits

A comparative study was performed to determine the fatty acid, 4‐desmethylsterol and triterpenic alcohols compositions of three different Tunisian populations of Pistacia lentiscus fruit Rimel (RM), Korbous (KO), and Tebaba (TB). Fruits are rich in lipids, which varied from 39.37% (KO) to 42.48% (TB) on a dry weight basis. Qualitatively, fatty acid, sterol, mono‐ and dimethylsterol composition is identical for all populations. Oleic acid was the major fatty acid for all samples, accounting from 40.49% in TB population to 50.72% in RM population followed by the palmitic and linoleic acids. Other fatty acids are present at lower levels. Total sterol amount varied from 109.72 mg/100 g of oil (KO) to 434.26 mg/100 g of oil (RM) with an average of 248.74 mg/100 g of oil. The major 4‐desmethylsterol component in all studied Tunisian populations of P. lentiscus oil was ß‐sitosterol followed by campesterol in TB and KO, and by stigmasterol in RM. The amount of total triterpenic alcohols varied from 42.39 mg/100 g of oil in RM population to 70.41 mg/100 g oil in TB population. The quantitative difference in the fatty acids and 4‐desmethylsterols of the different populations studied could be due to the effect of geographic region and soil type.     

α-Tocopherol and fatty acids contents of some Tunisian table olives (Olea europea L.): Changes in their composition during ripening and processing

An experimental investigation was carried out on Tunisian olive-fruits of Meski, Sayali and Picholine cultivars. α-Tocopherol and fatty acids (FA) contents were analyzed, during both ripening and processing, according to the Spanish style. The relationship between oil, unsaponifiable and α-tocopherol contents was determined only during ripening. A genetic effect on FA composition was observed throughout the sampling periods. The highest oleic acid content was found in Sayali cultivar at green stage (78.5% of total FA). α-Tocopherol was positively correlated with unsaturated FA content (R = 0.71, p < 0.05), and oil amount (R = 0.984; R = 0.976; R = 0.952, p < 0.05 for Picholine, Sayali and Meski, respectively), but it was not correlated with unsaponifiable matter. In processed olive-fruits, the results showed primarily, that processing according to the Spanish style is not restricted to green olive-fruits but can be successfully used in cherry olives with guaranteed quality and nutritional value of processed product (Meski and Picholine) related to FA content. Secondly, both α-tocopherol and FA amounts decreased during processing for all cultivars. This decrease was cultivar dependent. It was more pronounced in the black fruit than in the green one for the same cultivar. During fermentation, pH variation showed the same profile in all cultivars. Final pH values at the end of fermentation depend on the concentration of free FA (acidity) in the brine.     

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.     

Removal of a wide range of dyes using 4-methyl-2-(naphthalen-2-yl)-N-propylpentanamide-functionalized ethoxy-silica and raw silica

The present research offers a comparative study on the character of the performance of dye removal using either functionalized silica or raw silica gel as adsorbents. First, these supports were characterized in terms of FT-IR and SEM analyses. Then, four different dye solutions were checked for the adsorption phenomenon: Eriochrome Black B (an acid dye), Methylene Blue (a basic dye), Direct Yellow 50 (a direct dye), and Reactive Blue 49 (a reactive dye). Experimental data revealed a dependence on the experimental conditions. Functionalized silica presented a higher removal of dyes than the raw silica. Among the four studied dyes, the highest capacity removal was achieved with Eriochrome Blue Black B (140 mg g^?1) using functionalized silica as adsorbent. This value was reduced to 55 mg g^?1 for raw silica. Further, kinetic and thermodynamic investigations of Eriochrome were discussed. Results gleaned from this study suggest that the functionalized silica could be considered as an efficient candidate to treat colored waters.     

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.     

FPGA implementation of a HW/SW platform for multimedia embedded systems

This paper presents a HW/SW platform for embedded video system. It has been designed around an embedded RISC processor and FPGA technologies and provides video input and output interfaces. The configurable platform has been used to implement a real time video processing and vision systems. The Altera’s Nios II development board was chosen to realise this real time video platform which uses μClinux as embedded Linux Operating System. Experimental results using H.263 video encoder show that this platform provides enough resources and speed to implement even complex multimedia embedded systems in real time.     

Study of RF N LDMOS critical electrical parameter drifts after a thermal and electrical ageing in pulsed RF

An innovative reliability test bench dedicated to RF power devices is currently implemented. This bench allows to apply both electric and thermal stress for lifetime test under radar pulsed RF conditions. This paper presents the first investigation findings of critical electrical parameter degradations after thermal and electrical ageing. It shows that the tracking of a set of parameters (drain–source current, on-state resistance, threshold voltage, feedback capacitance and transconductance) can give insight into the hot carrier injection phenomenon for a RF n⁻ channel lateral DMOS (N⁻ LDMOS) working under pulsed conditions.