Search

The effect of the coarse aggregate type on the fatigue flexural behavior of concrete was investigated in this work. Three types of the coarse aggregates were selected from three different careers (CA1, CA2 and CA3). The mechanical parameters of these aggregates were determined (Los Anglos and Micro Deval). Prismatic specimens (70×70×280 mm) for each concrete mixture were made with aggregates of each source. The flexural fatigue tests were conducted on these concrete samples with varying levels of loading of 55 to 80% and the ultimate flexural strength. The test frequency is around 80 Hz and it is automatically determined by pulsing the fatigue machine for a resonance situation (the phase shift is δ=0) between the mass-spring-specimen system. The obtained results show that the aggregates which have the similar parameters (Micro Deval and LA), provide better adhesion with cement paste, and therefore a greater bending strength. The strength evolution at short-term age is typical for specimens based on aggregates with low wear resistance by triturate (a high Micro Deval coefficient). Regarding the fatigue flexural behavior, the concrete specimens based on CA1, which have similar coefficients of Los Angeles and Micro Deval (respectively 18 and 16) present the behavior (load/cycle numbers) close to that of the model prototype of the Wohler curve. This can be explained by a high homogeneity of the charge distribution during fatigue test compared to other concrete mixtures. Also, it was noted that the relationship between the endurance limit and the coefficient of Los Angeles is inversely proportional: The aggregates which have good strength to fragmentation (low coefficient of LA), as aggregates CA2 case give an endurance limit at around 70% max bending load. Key words: Coarse aggregate, Los Angeles, Micro Deval, bending test, fatigue testing, endurance limit.

This study aimed to identify the relationship between the tactical skills level of tactical thinking among football players. To achieve this, the researchers used the analytical descriptive approach to preserve the suitability nature of the study on a sample of 75 players from 3 clubs of football at the level of clubs Bouira province, randomly chosen. By testing their standard tactical skills and tactical thinking, it has been found the following results: there is a strong positive relationship between the level of tactical skill and tactical thinking. In the light of the outcome, the researchers recommended as follows: (1) focus on footwork drills competent skills game handlers collective or tactical skills and connect it with the tactical thinking and (2) the need to identify the causes of ambitious player’s sports teams.

Dynamic Software Updating (DSU) consists in updating running programs on the fly without any downtime. This feature is interesting in critical applications that must run continuously. Because updates may lead to safety errors and security breaches, the question of their correctness is raised. Formal methods are a rigorous means to ensure the high level of safety requested by such applications. The detection of points to perform safe updates is a critical issue in DSU. Indeed, an hazardous update point leads the updated system to erroneous and unexpected behavior. We present in this paper a mechanism to detect safe update points in DSU for Java Card applications. The mechanism is then formally verified using model checking against correctness properties: deadlock free, activeness safety and DSU-liveness.

Une rétrospective de l'évolution de la formation des enseignants de lycée professionnel au cours des trente dernières années permet de mieux saisir la portée de ces changements et de s'interroger sur leurs conséquences.

SSCI-VIDE+ATARI+AAU; International audience; Cobalt and mixed iron-cobalt spinel oxides CoxFe(3-x)O4 supported on SiO2 'IMP-Co-x-500' and their bulk analogues 'CP-Co-x-500' were prepared via impregnation and co-precipitation methods respectively and calcined at 500 degrees C. Thermogravimetric analysis 'ATG/DTG', X-ray Diffraction method 'XRD', Texture measurements 'BET/BJH' and Temperature Programmed Reduction technique 'TPR' were used for their characterization. Their catalytic behavior in ethanol combustion was investigated. Results showed that nanostructured oxide materials with spinel structure were obtained with a good dispersion of the active phase at the surface of silica in the case of IMP-Co-x-500 compounds. The reduction behavior of the prepared samples is highly dependent on the oxide composition and interaction with the support; which is directly related to the catalytic behavior. The use of supported catalysts improves the catalytic performance and leads the reaction towards a total oxidation by decreasing greatly the formation of partial oxidation products. The obtained values of activation energies are relatively low in comparison with the literature data. A compensation effect was found by carrying out ethanol combustion through the spinel systems considered in this work. (C) 2016 Elsevier B.V. All rights reserved.

Volatile organic compounds are ubiquitous atmospheric contaminants, affecting both indoor and outdoor environments. Attention is overall paid to toxicants, among which mono-aromatic species, in particular to benzene, toluene, ethylbenzene and xylenes are cumulatively indicated as BTEX. Mono-aromatic hydrocarbons were investigated in the air of Ouargla, Algeria, between 2014 and 2015. Measurements were conducted indoors and outdoors at the hospital and university estates of the city. BTEX were enriched from air by means of Analyst-I type diffusive sampling devices, which allowed continuous sampling over weeks. After collection, the samplers were spiked with bromobenzene (used as internal reference compound for analysis) and extracted with carbon disulfide directly in the vessel, then the analytes were characterized by means of capillary gas chromatography coupled with flame ionization detection. Total BTEXs ranged from ca. 41 to 131μg/m3; among them toluene (22–87μg/m3) was the most abundant congener. Benzene, ranging from 12 to 27μg/m3, always exceeded the limit value imposed by European normative for health preservation purposes (5μg/m3). At the hospital, the indoor/outdoor BTEX concentration ratio (I/O) exceeded all-the-time 1.0 (range: ∼1.5–2.0), which suggested the existence of internal sources for BTEX. This finding was confirmed by the analysis of concentration ratios between the BTEX compounds, which changed from outdoors to indoors as well as with the internal locations examined.

Dymanic software updating (DSU) consists in updating running programs on-the-fly without any downtime that leads to systems unavailability. The use of DSU in critical applications raises several is...

Silicon etching in alkaline solutions has been employed for many years, in the fabrication of solar cells. Surface texturisation of crystalline silicon was performed by using different etching solutions. Recently, a strong oxidising reagent NaOCl has been used successfully by several authors to texture the silicon surface. In this work, the effect of the etching parameters such as solution composition on the silicon surface morphology is studied. The surface of etched samples was analysed by scanning electron microscopy (SEM), spectrophotometry and secondary ion mass spectroscopy (SIMS). The results clearly show that the presence of ethanol in the solution leads to the formation of pyramids, while its absence induces the formation of nanostructures (nanowire or nanoneedle).

The present study was conducted to survey about sero-epidemiological status of Newcastle disease (ND), Infectious bronchitis (IB) and Infectious bursal disease (IBD) on Algerian broiler chicken (30 flocks/1200 sera) using ELISA method and to assess the influence of some risk factors related to each disease. Among all investigated flocks, ND was the most seroprevalent disease (63.33%); however, IB and IBD showed less serological positivity (40% and 16.66% respectively). For ND, Cobb 500 Flocks were significantly more seropositive by 78% (p = 0.025) than other strains. Nevertheless, flocks with good hygiene were significantly less seropositive to ND by 26% (p = 0.022). For IB, the risk of seropositivity was significantly lower in spring by 40% (p = 0.036). Although, flocks with higher density or with more than 30 days old were more seropositive respectively by 47% (p = 0.041) and 45% (p = 0.019). At last, when broiler chicken were not boosted by IBD vaccine, flocks appeared to be more seropositive by 48% (p = 0.047); especially in spring by 45% (p = 0.048); or in farms with poor hygiene by 65% (p = 0.004); however, more than flocks 30 days old flocks were less seropositive by 30% (p = 0.009).

International audience; Dynamic Software Updating (DSU) consists in updating running programs on the y without any downtime. This feature is interesting in critical applications that must run continuously. Because updates may lead to safety errors and security breaches, the question of their correctness is raised. Formal methods are a rigorous means to ensure the high level of safety requested by such applications. The detection of points to perform safe updates is a critical issue in DSU. Indeed, an hazardous update point leads the updated system to erroneous and unexpected behavior. We present in this paper a mechanism to detect safe update points in DSU for Java Card applications. The mechanism is then formally veried using model checking against correctness properties: deadlock free, activeness safety and DSU-liveness.

The air of our living places is affected by organic compounds, which can exist as vapors (VOCs, e.g. benzene group) or aggregated to airborne particulates and dusts (e.g., polycyclic aromatic hydrocarbons PAHs and very polar substances). The occurrence of organic contaminants was investigated in the hospital and university of Ouargla city, Algeria, by applying the diffusive sampling technique. For our purposes, Analyst-2 type sampling devices (produced by Marbaglass, Rome, Italy) were deployed both inside and outside, in the autumn 2015. Analyst-2 has been developed for semi-volatile organics at low virtual flow rates, and allows to collect gaseous PAHs in the 128-202 molecular weight range, namely from naphthalene up to pyrene). Therefore, the air contaminants are determined by solvent extraction (toluene) and gas chromatographic - mass spectrometric analysis (GC/MS). In our case, total PAHs ranged between 1.8 and 8.6 µg/m3 in interiors and from 0.6 to 0.8 µg/m3 in the open air, with an in/out concentration ratio exceeding 3 at both sites. This means that internal sources affected the location investigated; meanwhile, PAH pollution was more important at the university than at hospital. Abatement measures must be implemented in both sites, to mitigate the exposure of population to these toxicants.

Avian urolithiasis is one of the major causes of mortality in poultry. However, in Algeria this condition has never been described. An outbreak of avian urolithiasis was observed on a large commercial egg complex in the department of Chlef (West of Algeria). The clinical features of this condition are to be described. Mortality associated to urolithiasis started at the onset of egg production, estimated to 0.7 % per week. Urolithiasis induced an egg drop estimated to 12%. Dead and live layers were both necropsied and examined for kidney lesions. Most of the birds examined presented enlarged ureters, renal atrophy and visceral gout deposition.

The deposition by electrochemical way in the form of an iron thin film was studied on a vitreous carbon electrode in various aqueous and organic media. The deposit of iron was studied by cyclic voltammetry; the quantity of iron deposited was determined by integration of the cathodic and anodic peaks of Fe (0) and Fe (II) of the various media.

International audience; This paper deals with formal specification and verification of Java bytecode update. Programs update for java applications has gained a wide interest since it is used for several purposes: transforming semantics of a program, adding features to a program or performing optimizations. In this paper, we focus on program transformations for java programs at the bytecode level. Because these transformations may introduce errors, our goal is to provide a formal way to verify the update and establish its correctness. Our approach for formal specification and verification of updated Java bytecode programs is based on four ingredients: a formal interpretation of the semantics of update operations, a functional representation of bytecode, bytecode annotation and predicate transformation calculus. We use the concept of Hoare predicate transformation to derive a specification of an annotated bytecode. Annotations are used to express update operations within the code. A functional representation is used to model annotations and bytecode. The approach derives then a new specification for the annotated bytecode using a weakest precondition calculus defined to deal with update operations. Verification conditions are then generated and proved to establish the correction of the update.

In this paper, we present a model of a hysteresis motor based on Maxwell's equations coupled with the Jiles-Atherton (J-A) hysteresis model solved by the finite element method. The aim of this work is to validate such a model by comparison with the experimental results (electromagnetic torque, voltage, current). We also present an analysis of this motor when imposing current or voltage in the 2D vector potential formulation.

Dynamic software updating (DSU) consists in updating running programs on the fly without any downtime. This feature is interesting in critical applications that must run continuously. Because updates may lead to safety errors and security breaches, the question of their correctness is raised. Formal methods are a rigorous means to ensure the correctness required by applications using DSU. In this paper, we present a formal verification of correctness of DSU in a Java-based embedded system. Our approach is based on three major contributions. First, a formal interpretation of the semantic of update operations to ensure type safety of the update. Secondly, we rely on a functional representation of bytecode, the predicate transformation calculus and a functional model of the update mechanism to ensure the behavioural correctness of the updated programs. It is based on the use of Hoare predicate transformation to derive a specification of an updated bytecode. Thirdly, we use the functional representation to model the safe update point detection mechanism. This mechanism guarantees that none of the updated methods are active. This property is called activeness safety. We propose a functional specification that allows to derive proof obligations that guarantee the safety of the mechanism.

The effectiveness of stimulation using hydrochloric acid in high permeability, fractured carbonate reservoir is a challenge due to several reasons like fast acid spending rates, high leak off and non-effective diversion. All these limit the success rate of matrix stimulation using hydrochloric acid. Ultimately the communication between reservoir and wellbore will be less optimum leading to less than expected well performance. The industry is in continuous search of an effective stimulation technique through which good communication between reservoir and wellbore can be established. In the pursuit of maximizing oil production, Kuwait Oil Company is implementing various new technologies. Recently, acid tunneling technology was piloted in an old producer well in one of its prolific yet challenging Mauddud carbonate reservoir. Acid tunneling is a new approach of stimulation that supersedes normal matrix stimulation in carbonate reservoirs to enhance reservoir contact by creating tunnels through dissolution of rock in acid. Mauddud is a super-giant depletion-drive oil reservoir in NK field undergoing massive development efforts with enhancement in oil production through phased pattern-water flood. The reservoir has 10 layers and the average permeability of the reservoir ranges between 15 md to 1D predominantly due to fractures and vugs, which are distributed and extended variedly from layer to the other. The acid tunneling pilot was performed in an old well in Mauddud limestone located in south-eastern part of Raudhatain field where the rock quality is poor compared to the crestal area. The well was selected for pilot due to poor production. The well does not enjoy injection support due to a sealing fault between it and an injector, lying a kilometer away. The well penetrated three layers A, B and C in Mauddud. Two tunnels of 25 ft each were created using 15% HCl acid. The well showed good production after acid tunneling job and the productivity index of the well increased three times. The well is still showing good performance even after one year. These pilot results lead to full scale field implementation of this technology. The paper presents a case study describing advantages of acid tunneling, well selection criteria for this technology application, selection of effective acid concentration for the job and also limitations of the technology. All these informations work as a guideline to implement this technology in mass scale.

In this paper we present an accurate analytical model to calculate the losses in an insulate gate bipolar transistor (IGBT) with free-wheeling diode. The nonlinearity of capacitances of the devices and the parasitic inductance in the power circuit are considered. This mathematical model estimates the total power losses in a simple way with a clear physical meaning, high accuracy and without a significant reduction in the speed of numerical calculations. The datasheet results are provided to verify the model; the simulation results are in good agreement with those given by the manufacturer’s data sheets.

Cette thèse présente le sous-système ISIS, une méthode d'expression et de contrôle de l'intégrité sémantique, dans les bases de données relationnelles. Celle-ci est réglée par un ensemble de lois appelées contraintes d'intégrité sémantique (CIS). Une réalisation est effectuée dans le cadre du projet MICROBE