Queuing analysis of shared-buffer switches with control scheme under bursty traffic

Shared-buffer switches have many advantages such as relatively low cell loss rate and good buffer utilization, and they are increasingly favoured in recent VLSI switch designs for ATM. However, their performance degrades dramatically under nonuniform traffic due to the monopolization of the buffer by some favoured cells. To overcome this, restricted types of sharing and hot-spot pushout (HSPO) have been proposed, and the latter has been shown by simulation to perform better in all situations. In this paper we develop an analytical model for performance evaluation of a shared-buffer asynchronous transfer mode (ATM) switch with HSPO under bursty traffic. This analytical model is an improved version of the first model ever developed for this purpose. We balance the relative queues to approximate the effects of pushout, while keeping only four state-variables, and our model gives a good agreement with simulation, for calculating throughput and cell loss.     

The corrosion behaviour of Cr/Co/Mo-alloyed low residual carbon steels in seawater solutions

The general corrosion behaviour of low residual steels alloyed with chromium or cobalt or molybdenum in seawater solutions was studied. The carbon content of low residual steels ranged from 0.1 to 0.4%, chromium content between 1.0 and 4.0%, cobalt content between 1.0 and 3.0%, and molybdenum content between 0.3 and 1.0%. Repeated laboratory tests demonstrated that low levels of chromium reduce the dissolution rate of low residual steels in seawater solutions. The results of this study suggest that cobalt alloying plays a neutral role, whereas molybdenum plays a major role in reducing the corrosion rates, particularly in higher carbon steels.     

Removal of cyanide in aqueous solution by oxidation with hydrogen peroxide in presence of activated carbon prepared from olive stones

This work is dedicated to the removal of the very toxic free cyanide from aqueous solution by oxidation with hydrogen peroxide H₂O₂ in the presence of activated carbon prepared from olive stones. Effects of the initial molar ratio [H₂O₂]₀/[CN^?]₀, the initial cyanide concentration, the activated carbon concentration and the temperature on cyanide removal have been examined. The removal of free cyanide in absence of activated carbon showed very slow kinetics. The presence of activated carbon has increased the reaction rate showing thus a catalytic activity. The kinetics of cyanide removal has been found to be of pseudo-first-order with respect to cyanide and the rate constants have been determined for different values of the aforementioned parameters. The apparent activation energy has been determined from tests carried out at three different temperatures. It was found equal to 46.2 kJ/mol in the presence of activated carbon, which is about half of the 82.7 kJ/mol found for the oxidation in absence of the activated carbon.This process can be interesting for the cyanide removal from processed solutions because it does not use soluble metal catalyst and it consumes only hydrogen peroxide as chemical product.     

Electrochemical reduction of CO2: Two- or three-electrode configuration

Electrocatalytical conversion of CO₂ into various chemicals like hydrocarbons and CO is regarded as a promising approach to mitigate carbon emission and, meanwhile, to provide sustainable energy and value-added chemicals. Two different reactors are used in this work. One is based upon the two-electrode configuration powered by a DC power supply or Si solar cell, which is suitable for practical applications. Another is three-electrode one powered by a potentiostat, which is feasible to study the electrode performance. Polycrystalline Cu electrode is used as the cathode, and hematite is the anode. Performance of CO₂ reduction using the two- and three-electrode configurations is studied by measuring electrode potential, cell voltage, current density, Faradaic efficiency, and reduction selectivity of CO₂. Cu cathode used here exhibits a low overpotential for CO₂ reduction, specifically for the cell with two-electrode configuration. No obvious difference can be observed between the two types of configurations at a low bias like −0.3 and −0.4 V; while the reactor with two-electrode configuration exhibits better performance at a high bias like −0.8 V than the one with three-electrode configuration. Thus, the reactors with two-electrode configuration are desirable for practical applications, specifically considering solar cells can be used as the power source to provide green and sustainable energy.     

Effect of inulin and galactooligosaccharides on particle size distribution and rheological properties of prebiotic ketchup

The aim of this study was to evaluate the effects of different combinations of long-chain inulin and short-chain galactooligosaccharides mixed with different hydrocolloids on the physical/rheological attributes of prebiotic ketchup. Novel prebiotic ketchup was produced in which modified starch, xanthan, and guar gum was incorporated. Results showed that modified starch negatively influenced the physical properties of prebiotic samples and the optimum condition was 7.5% long-chain inulin and 2.5% galactooligosaccharides along with 0.4 % xanthan and 0.18% guar gum. Under these conditions, smaller hysteresis loop area, higher values of the linear viscoelastic region, larger G₀, η₀ in the creep test, and smaller sized suspended particles as compared to the other prebiotic samples were observed. In addition, galactooligosaccharides may interfere with the elastic behavior due to its high water solubility. Therefore, an appropriate amount (2.5%) of this ingredient may be used to produce a nutritive prebiotic ketchup with desirable textural properties. Environmental scanning electron microscopic images confirmed larger and inter-connected air bubbles entrapped into the semi-solid matrix of prebiotic sample produced under optimum condition.     

Arabic sign language intelligent translator

ABSTRACT

Arabic sign language (ArSL) is method of communication between deaf communities in Arab countries; therefore, the development of systemsthat can recognize the gestures provides a means for the Deaf to easily integrate into society. In this research we implemented a computational structurefor an intelligent interpreter that automatically recognizes the isolated dynamic gestures. The proposed system recognizes and translates gesturesperformed with one or both hands. It comprises five subsystems, building dataset, video processing, feature extraction, mapping between ArSL and Arabictext, and text generation. To apply the system, 100-signs of ArSL was used, which was applied on 1500 video files. It's were divided into five classes:alphabet, numbers, "prepositions, pronouns and question words", Arabic life expressions, and "nouns and verbs". The evaluation indicated that thesystem automatically recognizes and translates isolated dynamic ArSL gestures by highly accurate manner. The results showed that the system accuracy is 95.8%.     

Investigation of Interfaces by Atom Probe Tomography

We investigated the thermodynamic and transport properties of buried interfaces with atom probe tomography. Owing to the 3D subnanometer resolution and single atom sensitivity of the method, it is possible to obtain composition profiles with high accuracy both along or normal to the interfaces. We have shown that the width of the chemical interface between the Fe and Cr system follows the Cahn–Hilliard relation with a gradient energy coefficient of 1.86 × 10^?22 J nm². Sharpening of the Ni/Cu interface as a result of kinetic control was directly observed. We investigated the grain boundary and triple junction transport in Fe/Cr and Ni/Cu. Cr segregation enthalpy into Fe triple junctions was found to be 0.076 eV, which falls in between the surface (0.159 eV) and grain boundary (0.03 eV) segregation enthalpies. In the investigated 563 K to 643 K (290 °C to 370 °C) range, Ni transport is 200 to 300 times faster in the triple junctions of Cu than in the grain boundaries. The diffusion activation enthalpy in the triple junctions is two-thirds that of the grain boundaries (0.86 and 1.24 eV, respectively). These investigations have shown that triple junctions are defects in their own right with characteristic segregation and diffusion properties: They are preferred segregation sites and can be considered as a diffusion shortcut in the grain boundary network.     

An integrated methodology to control the risk of cardiovascular disease in patients with hypertension and type 1 diabetes

Today, air pollution, smoking, use of fatty acids and ready‐made foods, and so on, have exacerbated heart disease. Therefore, controlling the risk of such diseases can prevent or reduce their incidence. The present study aimed at developing an integrated methodology including Markov decision processes (MDP) and genetic algorithm (GA) to control the risk of cardiovascular disease in patients with hypertension and type 1 diabetes. First, the efficiency of GA is evaluated against Grey Wolf optimization (GWO) algorithm, and then, the superiority of GA is revealed. Next, the MDP is employed to estimate the risk of cardiovascular disease. For this purpose, model inputs are first determined using a validated micro‐simulation model for screening cardiovascular disease developed at Tehran University of Medical Sciences, Iran by GA. The model input factors are then defined accordingly and using these inputs, three risk estimation models are identified. The results of these models support WHO guidelines that provide medicine with a high discount to patients with high expected LYs. To develop the MDP methodology, policies should be adopted that work well despite the difference between the risk model and the actual risk. Finally, a sensitivity analysis is conducted to study the behavior of the total medication cost against the changes of parameters.