Fatima Bahreïn, Ibtissem Saadouni, S. Makhloufi

كلية العلوم والتكنولوجيا-جامعة أحمد دراية - أدرار · الجزائر

L'énergie est un facteur primordial dans le développement que connait le monde dans les différentsdomaines. Les énergies fossiles comme le charbon le pétrole ainsi que l'énergie nucléaire ont un grave impact sur l'environnement, de plus ces énergiesne sont pas renouvelables, Les énergies renouvelables comme le solaire l'éolien,……sont considérés commues l'alternatif à ces énergie classiques. L'Algérie dispose d'un potentiel énorme en ce qui concerne les énergies renouvelables, ce qui nous à motivé pour effectuer ce travail qui consiste à étudier l’intérêtd'utiliser l'hydrogène comme moyenne de stockage dans les systèmes photovoltaïque et ce dans la région d'Adrar.

محسن شيحة, نجوى أحمد نجوم

كلية العلوم-جامعة حمص · سوريا

Ahmed Haj Hamid Mohamed , Mohammed Bakhit. Y, Muhammad Bello Danladi

كلية التربية الحصاحيصا-جامعة الجزيرة · السودان

The sources of information in academic libraries are considered one of the basic pillars with regard to the process of selecting, organizing and retrieving them, so the process of knowledge, quantity, quality and evaluation of them is important for the dynamic work in these libraries. The aim of the research was to find out the causes for low patronage by the users. Thus, the study identified the information resources available in the Libraries; it discovered how these resources were organized; it identified the services offered; it examined the utilization of resources by patrons of the libraries; it also discovered reasons for low patronage of the resources. Survey research method was employed and questionnaire was used as instrument for collecting data where Pearson Product Moment Correlation (PPMC) was used for testing the hypotheses. Four hundred and twenty sixty (426) respondents participated in this study, out of four hundred and sixty seven (467) distributed questionnaires to the library staff and students of the institutions. The findings of the study revealed that although, the quantity and quality of the majority of the information resources and services were satisfactory, the major challenge nearly everyone faced in the libraries was inadequate accommodation that is; there was lack of sufficient seating capacity, lack of quiet and well-furnished study areas, comfortable seating arrangement, book stack spacing, proper lighting, ventilation and conducive atmosphere which would encourage students’ use of library and information services in the libraries. Other challenges revealed by the findings of this study included; Inadequate staff to attend to users; slow internet connectivity, most of the library staff were not friendly, most of the libraries were not marketing their services, and unsuitable opening and closing hours. It was therefore recommended that, the respective managements of Yobe State Tertiary Institutions must ensure convenient, favourable and conducive library environments for meaningful and effective utilization of resources. The managements of academic libraries should boost the marketing strategies of their products and services because through marketing, libraries can increase the reach of their services and promote themselves. Above all, employment of adequate library staff in both quantity and quality was strongly recommended.

Asmaa Miloudi, Nedjma Dellaoui, Sabrina Khaldi

كلية العلوم التطبيقية-جامعة ابن خلدون – تيارت · الجزائر

Le but de ce travail était d'étudier l'utilisation d'un matériau à changement de phase(MCP) lié à un panneau photovoltaïque courbe (PV) afin d'améliorer sa performance de régulation thermique et de limiter l'élévation de température sur sa face avant, Un modèle de transfert de chaleur à volume fini implicite à deux dimensions a été utilisé pour résoudre des équations de Navier-Stokes et d'énergie instationnaires avec le code commercial FLUENT 6.3Cependant, pour améliorer les performances thermiques de ce panneau PV incurvé, nous avons varié le rayon de courbure jusqu'à ce que le panneau PV soit aplati. Pour la validation,les contours isothermes et l'évolution temporelle de la température sont comparés aux données de la littérature.Les résultats montrent que la température des cellules photovoltaïques augmente pour les courbures élevées mais que les plus basses n'ont plus d'influence sur celle-ci plustard, tandis que l'ajout de MCP derrière le panneau PV peut maintenir sa température.

Omar Huzayyin , Mohamed Elmorsi, Mohamed Mahmoud Osman

كلية العلوم والهندسة-الجامعة الأمريكية بالقاهرة · مصر

The potential of integrating phase change materials (PCM) directly to solar collectors is proposed as a promising innovative modification for solar collectors in recent years. Accordingly, several compact PCM-collector designs are presented and compared to the conventional solar collector systems. In this study, a single vacuum tube is experimentally tested as a building block of the novel evacuated tube collector-storage solar water heater (ETCS). The free space of a single evacuated tube with a U-bend copper pipe is filled with Paraffin wax as a PCM, while water is used as heat transfer fluid (HTF). In addition, a longitudinal aluminum fin is used to enhance the heat transfer between the copper tube and the PCM. The performance of the proposed building blocks is evaluated under several charging and discharging experiments at different operating conditions. The tested tubes are evaluated in terms of cumulative recovered energy, energy storage/recovery efficiency, effectiveness, and charging-discharging cycle time. The results show that natural convection is the dominating heat transfer mode for 65% of the charging time. For the finned tube, the results show that increasing the PCM initial temperature from 65℃ to 80℃, increases the recovered energy and the total energy efficiency by 19% and 24%, respectively. For the un-finned tube, such an increase in PCM initial temperature increases the recovered energy and total energy efficiency by 5% and 9%, respectively. On the other hand, increasing the flow rate of the HTF from 0.3 l/min to 0.5 l/min decreases the effectiveness to 18% and 11% for the finned and un-finned tube, respectively. The heat loss test shows that the heat retention of the finned and un-finned tube after 12 hours test is almost similar at 34% and 32%, respectively. Further, the experimental results are used to validate a numerical model that is used to investigate the effect of tube design on thermal performance. Moreover, the effective heat capacity method is used to model the proposed building block, and the model is validated using both the experimental and numerical results. In addition, a simplified 2-D model is developed and used for investigating tube performance with different design parameters. Finally, the simplified model is integrated with a design methodology that is developed to be used as a designing tool for novel ETCS systems. The methodology presented in this study is used to design a new generation of solar collectors that work as a stand-alone compact solar water heater for heat demand in the night.

خليفة برايس, عيسى شقبقب

كلية العلوم الاقتصادية والعلوم التجارية وعلوم التسيير-جامعة الجزائر 3 - إبراهيم سلطان شيبوط · الجزائر

نظريات و سياسات التجارة الخارجية و تحليل تطور الميزان التجاري و مؤشرات التجارة الخارجية في الجزائر و دراسة قياسية للصادرات و الواردات في الجزائر.

مليكة بن منصور, نجاة ناصر

كلية العلوم الإنسانية والاجتماعية-جامعة أبو بكر بلقايد - تلمسان · الجزائر

Le mariage est considéré comme l’une des relations humaines primordiale et essentiel àl’existence, et la consanguinité existe depuis l'Antiquité.Vu que les coutumes et les traditions arabes, sont plus concernées par cette pratiqueque d’autres, en effet, la consanguinité augmente la fréquence des homozygotes dansla population et de là le risque d’atteintes des maladies héréditaires.En ce qui concerne la présente étude, elle vise à révéler la culture de la société envers laconsanguinité dans la région de Tlemcen dans l'ouest de l'Algérie, ainsi que mettrel'accent sur la pertinence de ce style traditionnel du mariage et les maladieshéréditaires, et il est basé sur un échantillon de 480 couples.Les résultats de l’étude ont révélé que la consanguinité semble être étroitement lié austatut socio-économique et culturel de la population étudiée, et que la fréquence de cetype de mariage dans la même famille augmente les chances de transmission demaladies héréditaires chez les enfants.

Billel Benilles, Rania Zerdoum

المدرسة العليا للتجارة - الجزائر · الجزائر

La fusion de la technologie numérique et des services financiers a donné naissance à un concept appelé FinTech. Cette ère n’est pas définie par les produits et les services financiers fournis, mais par ceux qui les fournissent et par l’application d’une technologie en développement rapide aux niveaux de détail et de gros. Cette dernière évolution de la FinTech, dirigée par des start-ups, pose des défis aux régulateurs ainsi qu’aux acteurs du marché. Dans certaines économies, il y a eu une forte demande d’innovations en matière de technologie financière, tandis que d’autres pays ont mis à disposition un environnement économique et réglementaire plus bienveillant, rendant la demande trop restrictive. Ce travail de recherche vise à déterminer les conditions de développement des FinTech en Algérie et les apports potentiels que la FinTech peut offrir au secteur financier en général et bancaire en particulier, à travers une analyse thématique par l’utilisation du logiciel « Nvivo 12 Plus ». Cette étude est basée sur un échantillon composé de vingt responsables de différents segments du secteur financier algérien. Les résultats de notre étude montrent comment les différents acteurs de l’écosystème FinTech et leurs interrelations permettent d’accélérer l’essor du développement des FinTech en Algérie. Ainsi, si l’Algérie parvient à créer un écosystème FinTech et à adapter sa réglementation à ces nouvelles entités, le secteur bancaire et financier algérien bénéficiera d’une plus grande inclusion financière et deviendra plus performant et en phase avec le contexte mondial actuel.

سالم جعفر العلوي, طارق المالكي

كلية الطب والصيدلة - مراكش-جامعة القاضي عياض · المغرب

Alaeddin Ebrahim, Mehiddin al-baali, N.sundaararajan

كلية العلوم-جامعة السلطان قابوس · عمان

This thesis presents findings from a comprehensive geochemical and geophysical investigations for uranium and associated minerals in a few selected though limited areas of the Sultanate of Oman. Based on the knowledge that Proterozoic basins produce ~ 30-40% or even more of the global uranium production, the Proterozoic basement of Dhofar assumes significance with possible uranium targets, which were identified in reconnaissance investigations that were carried out in the late 1970s. The objective of this study was to re-investigate several of the uranium anomalies found in this region, particularly in the Neoproterozoic rocks of southern Oman and some members of the Huqf Super group in Al Wasta region in addition to further potential sites. An association of shales rich in organic carbon and rocks with hydrocarbon accumulations presents possible geochemical traps for an initial pre-concentration of uranium. Accordingly, five different locations (Area-I, Area-II, Area-III, Area-IV and Area-V) were investigated including the basement outcrops at Mirbat (Dhofar) and NW of Muhut (central Oman), shale outcrops near Rakhyut (Dhofar near Yemeni border-Area-I) and fault intersections near Marmul (~ 170 km NE of Salalah-Area-II), plus the salt dome of Qarat Kibrit (oil acting as possible geochemical Uranium trap, while mobile brines are potential uranium carriers-Area-III), a silicified volcanic unit exposing radiation halos, typically seen in roll-front deposits, at Al-Ashkharah (South of Sur-Area-IV), and a radiogenic placer (heavy minerals containing zircon) in the siliciclastic Ordovician Amdeh formation, SE of Muscat (West of Al-Amirat-Area-V). The methods of investigation comprise in-situ and laboratory XRF analyses, geophysical methods consisting of gamma ray spectroscopy, very low frequency electromagnetic (VLF-EM) and magnetic surveys and gravity only in Murmul.The XRF and gamma-ray spectroscopy surveys in fields (Area-I, U Loc-1 to U Loc-4), detected only very weak uranium anomalies, some areas in Dhofar (Near Oman-Yemen) border yielded an elevated uranium concentrations of 30-40 ppm from small-scale anomalies (highly mobile when affected by weathering) which are uneconomic. Further, the geophysical surveys in U Loc-2 explored concealed faults underneath a plateau with depth in the range 10 m– 80 m. These faults were believed to have acted as conduits to the U-carrying fluids that emplaced U in its present location or near the surface. In addition, gamma ray and XRF analyses revealed a U-Th decoupling, indicating a high mobility of uranium than thorium. Further, the results from Marmul, Qarat Kibrit salt dome (near Adam) and Al-Ashkharah fields represent weak uranium anomalies. In the case of the Qarat Kibrit salt dome, the geophysical study figured out the precise spatial location of the salt unit and probable trend of a subsurface fault at an estimated depth from different methods range 10 m- 60 m. However, no enrichment of radiogenic elements was recorded here. Finally, the placer deposits of Al-Amirat (Area-V) have shown moderate enrichments for radiogenic uranium (~ 90 ppm) and thorium (~ 900 ppm), however, the basement outcrops did not indicate uranium enrichment and basically showed background values for the respective igneous/metamorphic rocks. Results of interpretation of VLF-EM and magnetic signals have revealed the possible mineralized structures as deep as 9 m- 44 m, emphasizing the need for further detailed investigations. Among the five different areas investigated, it may be stated that the possible occurrence of uranium of low grade and moderately high concentration of thorium could be seen near Al-Amirat (Area-V) though not commercially viable. In all the other areas of investigation, the geophysical signals particularly total magnetic field and VLF-EM have identified the subsurface faults and established their depth.