حسين أحمد يوسف , ميسون محيي العقيلي
الجامعة التكنولوجية · العراق
Manel Ghimouze ép Mehila, Yasmina Cherrad - Benchefra
كلية الاداب واللغات-جامعة الاخوة منتورى - قسنطينة 1 · الجزائر
Chahinez Fares, Mohamed El Amine Belouchrani, Taoufik Boukharouba
كلية الهندسة الميكانيكية وهندسة الطرائق-جامعة العلوم والتكنولوجيا هواري بومدين - الجزائر · الجزائر
La présente étude vise à établir l'influence des paramètres de surfaces modifiés par le traitement électrochimique de conversion « anodisation » sur le comportement mécanique de l’alliage 2017A. En s'attachant, plus particulièrement, à identifier l'effet de la microstructure du matériau, qui peut être modifié par des traitements thermiques, sur la morphologie des couches anodiques. Le comportement mécanique des alliages anodisés a été évalué en statique et en fatigue. Pour le comprtement en traction, le traitement d’anodisation ne change que les propriétés de ductilité. Alors qu’en fatigue, le comportement des alliages anodisés est influencé par la microstructure de substrat. Une réduction de la durée de vie dans les domaines : limité et illimité est observée.
Madjid Diaf , Saddek Afifi
كلية العلوم-جامعة باجي مختار - عنابة · الجزائر
Kheladi Mokhtar, Karim Aggoune
كلية العلوم الاقتصادية والتجارية والإدارة-جامعة عبد الرحمان ميرة - بجاية · الجزائر
La métropole, de par les externalités qu‘elle génère, vient aujourd’hui en tête de la hiérarchie de compétitivité pour constituer un lieu d‘excellence pour une concentration de quantité et de qualité des hommes et des activités. Ce travail s‘est concentré sur l‘apport de la métropolisation dans l‘amélioration des conditions de compétitivité des territoires. La question à laquelle nous nous sommes attachés de répondre est de savoir qu‘offrent les grandes métropoles mondiales pour qu‘elles soient aussi déterminantes dans la hiérarchie de compétitivité. Autrement dit, il s‘agissait d‘identifier les spécificités des métropoles et leurs capacités élevées de production dans un environnement globalisé. Pour le cas d‘Alger, capitale et grande ville d‘Algérie, qui concentre l‘essentiel des activités hors hydrocarbures, le scénario est discutable ; si on admet que la métropole est la forme urbaine qui maximise les rendements en matière de compétitivité des territoires, autrement dit, si la compétitivité de l‘Algérie est subordonnée à la construction d‘une métropole, à quelles conditions, pour le cas d‘Alger, réussit-on cette métropolisation ? Dans ce travail, nous avons étudié les capacités d‘Alger ainsi que ses insuffisances pour faire de cet espace une métropole sud méditerranéenne capable de concurrencer les autres métropoles méditerranéennes, arabes, africaines, etc. Nous avons aussi essayé de déterminer les enjeux, les défis ainsi que des conditions de succès de cette métropolisation tout l‘en inscrire dans un contexte global de renouvellement urbain en Algérie.
حمد العبدالوهاب, خليل جواد خليل الأدهم
كلية الهندسة-جامعة الملك فهد للبترول والمعادن · السعودية
Kingdom of Saudi Arabia has invested in a massive road network over the past thirty five years. The roads, which have been built to the best international standards, have show nearly signs of distresses due to the harsh environment and traffic loading. Local asphalt pavement temperature ranges between 10 C in the winter to 73 C in the summer. This has led to an increased demand to modify asphalt binders to improve the performance of local asphalt binders to minimize cracking stress, which occurs at low temperatures, and permanent deformation, which occurs at high service-temperatures. Different methods have been used to upgrade the properties of asphalt binders. One of the most commonly used procedures is modification of asphalt by addition of polymers. Use of polymers is the most convenient for asphalt modification for local contractors. IN addition to the improvement of rutting and fatigue resistance of modified asphalt, it also improves the stripping resistance of asphalt concrete mixes which make it attractive to the local market. Many methods have been used for evaluation of the asphalt binders, but most of them are empirical and there is no specific and unify standard adopted by asphalt agencies and researchers. Asphalt researchers use Super pave specification (AASHTO M320) to investigate the behavior of unmodified asphalt binders and classify them according to the performance grading system. But for the case of polymer modified asphalt binders, highway agencies tried to supplement the existing Super pave specifications with additional tests to evaluate correctly the behavior of the polymer modified asphalts. Elastic Recovery criterion is used for this purpose by many agencies worldwide. But in Saudi Arabia, Ministry of Transport still uses the conventional Super pave standards and do not include the elastic recovery criteria in the evaluation. This additional test can only predict the presence of the polymer in the asphalt binder and does not evaluate the performance. In order to identify elastomeric polymer modified binders in terms of their fundamental properties and performance, the Multiple Stress Creep Recovery (MSCR) test (AASHTOTP 70-08) have been studied in this research and to be introduced to the local standards.Four types of elastomeric and plastomeric polymers are selected in this study that widely used in Saudi Arabia to modify the local asphalt that produced by different refineries in the Kingdom; Ras Tannura, Riyadh, Jeddah and Yanbu. The results of this study show that, there is a good correlation between the MSCR and Super pave Performance Grading (PG) system and also with Elastic Recovery test. This leads to the conclusion that the new test can be used as a replacement of other tests that had been used in the evaluation of polymer modified asphalt binders against rutting.
G.K. Sweatman, Nadir Mohamed Shoukrey
الجامعة الأمريكية في بيروت · لبنان
El Kiri Redouane , Hanan Ouahabi
كلية الطب والصيدلة -جامعة سيدي محمد بن عبدالله - فاس · المغرب
امنة بن منصور, شيماء بوشيخي, صليحة بلاحة
كلية الآداب واللغات والعلوم الاجتماعية-جامعة عين تموشنت - بلحاج شعيب · الجزائر
احمد النور عبد الله, محمد الامين احمد, مى الفاضل النور شمس الدين
كلية الطب-جامعة الجزيرة · السودان
Background: This is a descriptive cross-sectional study which was conducted in Pediatric Referred Clinic (PRC) of Wad Medani Heart Disease and Surgery Centre (WHD & SC) during the period Oct – Dec. 2011. The aim of the study was to determine the pattern of congenital heart disease (CHD) among children presenting to WHD & SC during the study period. Also to study the socio-demographic background, the presenting symptom, the presence of other congenital anomalies associated with CHD and to identify the type of management received by these children. The sample size was 200 children. Information was obtained by a structured questionnaire.Results: Most children had CHD (85%) compared to 10% who had Rheumatic heart disease ( RHD). More than 55% of parents were illiterate or had primary education. 81% of the mothers were housewives and 78% of the fathers were unskilled workers. 81% of the children were diagnosed in infancy. The commonest presenting complaints were as follows: shortness of breathing (SOB) 70.5%, cyanosis 11%, grunting 10%, failure to thrive (FTT) 2.5% and 10% were asymptomatic. The pattern of CHD was 73.5% a cyanotic and 26.5% was cyanotic .Male to female ratio was 1.1:1. with the following details: ventricular septal defect (VSD) 29% atrioventicular canal (AVC) 11%, tetrology of Fallot (TOF) 10%, pulmonary stenosis (PS) 8.5%, patent ductus arteriosus (PDA) 8%, mitral regurgitation(MR) 7.5%, atrial septal defect (ASD) 6%, transposition of great arteries (TGA) 5.5%,dextrocardia (DC) 1% and single ventrical (SV) 0.5% as well as mitral stenosis (MS) and aortic regurgitation (AR). The commonest type of CHD was VSD. 46% of VSDs were small. Pulmonary hypertension (PHT) presented in 2.5% of the patients, 60% of them were due to large VSD, 20% due to AVC as well as MR. Associated congenital anomalies that occurred with CHD were 13%. Of these Downs syndrome constituted 9%. Medical treatment was received by 55% of children and 68% of the patients were planned to have surgical management. Only 18.5% were operated on and 40% of these surgical operations were carried out in WHD & SC and the remainder were done in Khartoum and abroad.Conclusion: the study concluded that the incidence of CHD is high compared to RHD at the majority of cases were diagnosed in infancy. SOB was the commonest symptom. Common form of CHD is acyanotic. VSD represented the majority specially small, followed by AVC and PS. While the commonest cyanotic CHD is TOF followed by TGA and TA. The commonest associated anomaly with CHD was Down's syndrome, some of these cases were operated in WHD & SC and others in Khartoum Cardiac centre or abroad
