Nouvelle classe de simulateurs permettant la caractérisation de dispositifs embarqués sur des structures de grandes dimensions

This paper presents the qualification of an iemn exploitation original system, intended to create a realistic electromagnetic environment on large structures (planes, missiles, land vehicles). It consists in a horizontal polarization transmission line simulator which is supplied by a high voltage generator. The transient currents, induced on the wires, are solved by using integral equations in the space-time domain. The electromagnetic fields evaluated inside the working volumes are determined in each point and at each time. We include numerous comparisons with the experiments carried out by the Centre d’études de Gramat.     

Dielectric properties of poly(vinyl chloride) in tetrahydrofuran and cyclohexanone

The dielectric absorption and dispersion of poly(vinyl chloride), M M_v = 49 000, in THF and in cyclohexanone have been studied over a frequency range of 120 kHz to 11·0 MHz, at temperatures from ?22·5 to 35°C, and at concentrations ranging from 4 to 12·0(w/v)% PVC/THF and from 2 to 8·0(w/v)% PVC/cyclohexanone. The viscosities of the two systems have also been measured at temperatures from 20 to 50°C. A single relaxation time was found (β = 0·8–1·0), which indicates that relaxation occurs by segmental rotation. The dielectric and viscous activation energies have been calculated. The dipole moment associated with the relaxation process has also been calculated. The relaxation time, dielectric and viscous activation energies and the dipole moment were found to be dependent on the type of solvent. The dipole moment also showed a molecular weight dependence. The influence of the concentration and temperature on the apparent dipole moment and on the relaxation time is discussed.     

A comparison between CFD and Network models for predicting wind-driven ventilation in buildings

The aim of this paper is to compare the implementation of computational fluid dynamics (CFD) and Network models for airflow rate estimation in buildings. The CFD software used is Fluent 5.5. Comparison between the predicted and simulated airflow rate is suggested as a validation method of the implemented CFD code, while the common practice is to compare CFD outputs to wind tunnel or full-scale measurements. This could be useful for studies that have no access to laboratory or full-scale testing facilities. Results obtained from testing a number of cases have been compared and analysed, considering normal and oblique wind directions. The comparison held between mathematical and CFD results generally showed a good agreement, which seems to justify the use of CFD code for predicting natural ventilation in buildings.     

Corrosion inhibition of benzyl triethanol ammonium chloride and its ethoxylate on steel in sulphuric acid solution

The inhibitive effect of benzyl triethanol ammonium chloride (BTAC) and ethoxylated benzyl triethanol ammonium chloride (EBTAC) on the corrosion of carbon steel in sulphuric acid solution is measured by the weight loss method. The adsorption of these compounds (surfactants) leads to the formation of a monolayer on the metal surface. The relationships between the concentrations of these inhibitors and their surface properties, thermodynamic properties, surface coverage (θ) and inhibiting efficiency have been investigated. The results indicate that EBTAC is superior to BTAC.     

Strip Yield Model Numerical Application to Different Geometries and Loading Conditions

A new numerical method based on the strip yield analysis approach was developed for calculating the Crack Tip Opening Displacement (CTOD). This approach can be applied to any crack geometry, of either infinite or finite extent, with arbitrary applied loading conditions. The technique is an adaptation of the dislocation-density based boundary element method to obtain crack-face opening displacements at any point on a crack, and succeeds in obtaining the requisite values as a series of definite integrals, the functional parts of each of which are evaluated exactly in closed form. The power of the technique is demonstrated by obtaining solutions to several crack configurations of practical interest.     

Synthesis and characterization of cellulose triacetate and poly(ethylene imine) membranes containing a polyether macrobicyclic: Their application to the separation of copper(II) and silver(I) ions

A cellulose triacetate (CTA)–poly(ethylene imine) (PEI) membrane containing a polyether macrobicyclic (cryptand) as a carrier and 2‐nitrophenyloctyl ether (NPOE) as a plasticizer was prepared. The CTA–PEI–cryptand–NPOE membrane was characterized with chemical techniques as well as Fourier transform infrared, X‐ray diffraction, differential scanning calorimetry, and scanning electron microscopy. The permeation of silver and copper ions through the CTA–PEI–cryptand–NPOE membrane was comparable to that through a supported liquid membrane. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1401–1410, 2004     

Modeling the flow behavior of a medium carbon microalloyed steel under hot working conditions

The constitutive equations for the flow behavior of a commercial 0.34 pct C-1.5 pct Mn-0.7 pct Si-0.083 pct V-0.018 pct Ti microalloyed steel were determined. For this purpose, uniaxial hot compression tests were carried out over a wide range of strain rates (10⁻⁴ to 10 s⁻¹) and temperatures (1123 to 1423 K). In combination with models developed in the literature, the experimental results permit the flow stress of the present steel to be predicted within ± 5 pct. It is shown that the classical constitutive equations must be modified to take the grain size into account, particularly when the latter is below 30 μm.     

Prejudice and Stereotype Maintenance Processes: Attention, Attribution, and Individuation.

Three experiments examined the relationship between prejudice and processing of stereotypic information. Higher levels of prejudice were associated with greater attention to and more thorough encoding of stereotype-inconsistent than stereotype-consistent behaviors but only when processing capacity was plentiful (Experiments 1 and 3). High-prejudice participants attributed consistent behaviors to internal factors and inconsistent behaviors to external forces (Experiment 2). Together, these results suggest that high-prejudice people attend carefully to inconsistent behaviors to explain them away but only if they have sufficient resources to do so. Results also showed that low-prejudice but not high-prejudice participants formed individuated impressions by integrating the implications of the target's behaviors (i.e., individuating). High levels of prejudice appear to be associated with biased encoding and judgment processes that may serve to maintain stereotypes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A simulation optimisation tool for planning of low-income housing projects

Construction of low-income housing projects is a recurring process and is associated with uncertainties that arise from the unavailability of resources. This paper presents a case study that discusses how computer simulation and optimisation are used to aid government agencies and/or contractors in planning of such projects. It illustrates the optimisation of project objectives, taking into consideration the interaction amongst involved resources. As such, total duration and the associated total costs, including direct and indirect costs, can be estimated and optimised. One Youth Habitation project that is executed in 6th of October City in Egypt is analysed in a step-by-step procedure to demonstrate the capability of proposed computer simulation and optimisation prototype (named LIHouse{_}Sim) in the modelling construction of low-income housing projects using bearing block walls with hollow core technique. The presented tool proves its practicality to contractors in estimating the time and costs of the recurring process of low-income housing construction, considering complex interdependencies between construction resources and the uncertainties associated with construction activities. The LIHouse{_}Sim prototype is used to perform a wide analysis for the alternative of the effective optimisation criteria in the bearing block walls/hollow core technique and for the genetic algorithm optimisation approach elements.     

A Dempster–Shafer Based Tit-for-Tat Strategy to Regulate the Cooperation in VANET Using QoS-OLSR Protocol

In this paper, we address the problem of cooperation among vehicles in VANET using QoS-OLSR protocol in the presence of selfish nodes. QoS-OLSR is a proactive protocol that considers the Quality of Service (QoS) of the nodes while electing the cluster-heads and selecting the Multi-Point Relay (MPRs) nodes. Cluster-heads and MPRs might misbehave on the roads by over-speeding or under-speeding. Classical and generous Tit-for-Tats are proposed to analyze the interaction among vehicles. However, both strategies are not able to enforce the cooperation due the fact that they (1) count on individual watchdogs monitoring, (2) rely on the node-to-node cooperation decision, (3) and ignore the high mobility and packet collisions. Therefore, we propose a Dempster–Shafer based Tit-for-Tat strategy that is able to improve the decision and regulate the cooperation in the vehicular network. This is done by (1) launching a cooperative watchdogs monitoring, (2) correlating the observations of the different watchdogs using Dempster–Shafer theory, and (3) propagating the decisions among clusters. Thereafter, we compare the Dempster–Shafer based strategy with several strategies derived from the original Tit-for-Tat. Simulation results prove that the Dempster–Shafer based strategy is able to maintain the survivability of the vehicular network in the presence of high mobility and packet collisions with minimal time and overhead.