L. Djabri , Messaoud Benhamza

كلية العلوم-جامعة باجي مختار - عنابة · الجزائر

فهد بن إبراهيم الحبيب, فهد بن عباس العتيبي

كلية التربية-جامعة الملك سعود · السعودية

Mohcine Bennani Mechita, Khaoula Hamdouch , Manuel Valdivia

كلية العلوم والتقنيات - طنجة-جامعة عبدالمالك السعدي · المغرب

جامعة جرش · الاردن

زينب زيود, لميس نديم عبد الرازق

كلية التربية-جامعة دمشق · سوريا

Khaled Youssef, Mariem Chamakh

كلية الآداب والعلوم-جامعة قطر · قطر

Thermoelectric technology converts thermal energy to electricity. Many studies were conducted on thermoelectric materials such as Bismuth Telluride and Lead Telluride. And the goal was to achieve an average ZT >2 which is required for waste heat recovery applications. Recently Tin Selenide (SnSe) showed a promising performance with a ZT of nearly 2.6 at 923 K for its single crystal structure at the b-axis. However, single crystal SnSe is very fragile and the production of single crystal SnSe structure is a complicated and costly process. Therefore, great interest was given to polycrystalline SnSe.In this work, the thermoelectric performance of polycrystalline SnSe was enhanced through nanostructuring and nano-composting with graphene via a cost-effective methodology. Nanocrystalline SnSe composites were successfully prepared by high energy ball milling and SPS techniques, and the structural characterization by X-ray Diffraction and Transmission Electron Microscopy revealed that the average grain size of both pristine SnSe and SnSe with Graphene was approximately (~ 10 nm). The mechanical properties were evaluated and showed an enhancement with high hardness values. The nanostructuring contributed in the enhancement of Seebeck coefficient and the highest reported value so far was obtained for pristine SnSe with 1032 μV/K at 873K. A significant improvement in ZT value was observed for the pristine nanostructured SnSe with a value of 0.9 at 873 K, and the addition of Graphene increased the ZT to 1.2 at 873 K due to the increased power factor and the lower thermal conductivity. Graphene was detected to be mainly present around the grain boundaries and this finding represents the first ever reported evidence to identify the location of graphene in a nanocrystalline TE material.

المختار طويسي , ليلى لبيض

كلية الحقوق والعلوم السياسية-جامعة زيان عاشور - الجلفة · الجزائر

حاولنا في بحثنا هذا تسليط بعض الضوء على موضوع وظيفة الوقف وآليات تسييره. وإذا أردنا فعلاً أن يلعب الوقف الدور التنموي المنتظر منه، فإنه لابد من العمل على توعية الناس بالمفهوم الجديد للوقف، بحيث يقتنع كل فرد مسلم بأن العين التي وقفها ستكون لا محالة بمثابة دعم للمركز المالي للمؤسسة الوقفية وزيادة رأسمالها. وبهذا أنهِ بحثي هذا بمجموعة من التوصيات ألخصها في الآتي: 1/ إبراز أهمية الوقف في الحياة الاجتماعية والدينية والاقتصادية للفرد، وتبيان المعالم الوقفية التي كانت موجودة في الجزائر لمحاولة بعثها من خلال تطويره واستغلال ثرواته وتثميرها. 2/ إبراز جملة من الآليات والعقود والأساليب الاستثمارية التي يستمد معظمها من الشريعة الإسلامية باعتبارها المصدر المادي للعمل الوقفي، وما لوحظ عليها أنها لم تعطِ نتائج إيجابية لعدم إمكان تطبيقها بسبب عدم توفر منظومة مالية وبنكية تشجع الاستثمار في هذا المجال. 3/ المحافظة على الأصول الوقفية وذلك من خلال تنمية ريعها لتحقيق أغراضها المستهدفة وفق اشتراطات الواقف وبما لا يتعارض مع أحكام قانون الأوقاف 91/10 المعدل والمتمم، وكذا أحكام الشريعة الإسلامية كمصدر له. 4/ إتمام معالجة ملف الأراضي الوقفية المؤممة بموجب الأمر 71/73 المؤرخ في 08/11/1971 المتعلق بالثورة الزراعية، والذي بموجبه صودرت الأملاك الوقفية وألحقت بأراضي الصندوق الوطني للأراضي الزراعية. 5/ إدراج صفة متولي الوقف وبصورة واضحة في المرسوم التنفيذي 91/176 التي تسمح له بطلب رخصة البناء في إطار تثمير الملك الوقفي والمحافظة عليه بالبناء. 6/ صارت الدولة اليوم عاجزة عن تغطية جميع القطاعات وتلبية كل الحاجيات التي يحتاج إليها أفراد المجتمع، لذا من واجب الدولة استغلال واستثمار الأملاك الوقفية لإمكانية تخفيف بعض الأعباء عن ميزانيتها المالية، لأن الوقف يعمل على تغطية بعض القطاعات الخدمية كالتعليم والصحة والتكوين

Sami Muhaidat, Arafat Al-Dweik, Lina Bariah, Mohammed Al-Mualla

جامعة خليفة · الامارات

The increased proliferation of connected user devices, offering a variety of services at different levels of performance, represents a major challenge for broadband wireless networks. An efficient solution for such challenge would require a paradigm shift towards the development of key enabling technologies for next generation wireless networks and beyond. One of the critical challenges towards realizing the next generation networks, however, is the scarcity of spectrum, owing to the unprecedented broadband penetration rate and the growing number of broadband users in recent years. Multiple access technologies play a pivotal role in determining the feasibility of satisfying the newly imposed requirements of the future wireless networks, such as, higher data rate, enhanced spectrum efficiency, increased connectivity and reduced energy consumption. Consequently, a growing research interest is devoted towards the development of new technologies, such as, orthogonal and non-orthogonal multiple access, massive multiple-input multiple output (MIMO), and cognitive radio (CR), to address some of the aforementioned challenges that face next generation networks. In this respect, this dissertation focus on the analysis of orthogonal and non-orthogonal multiple access techniques for wireless networks. In the first part of this thesis, we investigate a spectrally and computationally efficient blind channel estimation technique for orthogonal frequency division multiplexing (OFDM) systems over frequency selective fading channels, where a hybrid frame structure is utilized to enable blind detection of data symbols. Amplitude coherent detection (ACD) is considered for the hybrid frame structure, where several modulation schemes are used to modulate particular subcarriers, such as amplitude shift keying (ASK), phase shift keying (PSK) and quadrature amplitude modulation (QAM). To evaluate the performance of the considered estimator, a novel accurate closed-form symbol error rate (SER) expression is derived for the ASK symbols. The obtained SER analytical expression is then utilized to derive an accurate formula for the mean squared error (MSE) of the initial channel estimates. The obtained analytical results, veri_ed by Monte Carlo simulations, show that the SER and MSE are highly dependent on the channel correlation factor. Yet, accurate detection and estimation can be obtained for most practical channel models. The second part of the thesis is devoted to investigate the error rate performance of non-orthogonal multiple access (NOMA) systems over generalized Nakagami-m fading channels, under realistic assumptions, such as, imperfect successive interference cancellation (SIC). In particular, we derive novel pairwise error probability (PEP) expressions to characterize the performance of all users under different fading scenarios. The obtained PEP expressions are then used to obtain a union bound on the bit error rate (BER) and to investigate the achieved diversity gain of all users. Motivated by the fact that power allocation have a critical impact on the reliability of all users, and given that optimum power allocation should be applied to realize users' fairness in NOMA systems, we exploit the derived BER union bound to formulate and evaluate an optimization problem that aims at finding the optimum power coefficients that minimize the average BER union bound, under individual BER union bounds and average power constraints. The obtained analytical and simulation results demonstrate that the error rate performance of all users and the achieved diversity order is highly susceptible to users order and fading scenarios, represented by the fading parameter m. The third part of the thesis provides a comprehensive analytical framework devoted to evaluate the error rate performance of NOMA-based underlay CR networks. In specific, we consider a secondary NOMA-based relay network, which shares the full spectrum with a primary network, under interference power constraints. Given that secondary users, who adopt NOMA, operate under interference power constraints, we investigate the PEP performance of all secondary users while considering imperfect SIC. Particularly, we derive an accurate PEP expression which is then used to evaluate the BER union bound. The derived BER union bound is then used to examine the achieved diversity order of all users and optimize the power coefficients that allow exploiting the full potential of NOMA systems. Finally, the fourth part of the thesis provides a mathematical framework to analyze the error rate performance of NOMA-based relay networks with simultaneous wireless information and power transfer (SWIPT). An exact closed form expression is derived for the PEP of each user while considering an imperfect SIC process. Then the derived PEP is used to derive a tight union bound on the BER. The derived analytical results demonstrate that the error rate of all users is highly affected by the power splitting ratio, energy conversion efficiency and power allocation scheme.

صالح عوده بن طيار, هاشم عبدالرحمن محمد, يحيى الطايب العربي

كلية الصحة العامة وصحة البيئة-جامعة الخرطوم · السودان

Objectives: To compare the outcomes of tension-free mesh and sutured repairs in inguinal, paraumbilicaland incisional hernias.Patients and methods:This randomized controlled study of 1190 patients with primary inguinal (n=403),para-umbilical (n=372) and incisional (n=415) hernias, has been carried out at Ibn-Sina Central.Teaching.Hospital, and Al-Amal H., Hadhramout-Yemen., betweenSeptember 2004 and December 2007. The patients were allocated to either mesh orsutured repairs after matching of risk factors for recurrences. The primary outcomemeasure was hernia recurrence over a period of 3 years of follow-up.Results:There were statistically significant differences in the recurrence rates between meshand sutured repair groups of inguinal (1.5% versus 10.5%) para-umbilical (2.7%versus 12.9%), and incisional (4.3% versus 27.5%) hernias ( p <0.001). The pain scoreand the analgesic consumption seemed to be significantly greater in the sutured groups(p < 0.001). Return to normal activities was significantly shorter in the mesh groupsthan sutured repair group in inguinal (16.2±4. days versus 20.8±0.9 days) paraumbilical(20.9±5.6 days versus 23.6±10.5 days), and incisional hernias (23.8±6.8days versus 26.6±13.5 days). The patients who had mesh repairs were significantlymore satisfied with the procedure than those who had sutured repairs ( p<0.001). Themedian operating time, hospital stay and the complications were comparable in thetwo groups, except that chronic pain was more in the sutured groups than in the meshgroups of inguinal (12.4% versus 4%), para-umbilical (14%versus 5.4%), andincisional (13% versus 4.3%) hernia repairs. The differences were statisticallysignificant (p<0.001).Conclusion:Tension-free mesh techniques are safe, effective and easy to learn. They result inlower recurrences, lesser post-operative pain, less consumption of analgesia, andquicker rehabilitation. The study confirms superiority of tension-free repair oversutured repair.

Belhadj Younes, انيس حمو, خليل بلقواسمية

كلية العلوم التكنولوجية-جامعة عبد الحميد بن باديس مستغانم · الجزائر

Ce projet présente une étude détaillée d’un bâtiment à usage d’habitation et commercial constitué d'un sous-sol et d'un Rez de chaussée plus (08) étages, implanté à ELHCHEM dans la wilaya de MOSTAGANEM. Cette région est classée en zone sismique IIa selon le RPA99 version 2003. En utilisant les nouveaux règlements de calcul et vérifications du béton armé (RPA99V2003 et B.A.E.L91 modifié99), cette étude se compose de quatre parties : La première entame la description générale du projet avec une présentation de caractéristiques des matériaux, ensuite le pré dimensionnement de la structure et enfin la descente des charges. La deuxième partie a pour objectif l'étude des éléments secondaires (poutrelles, escaliers, acrotère, balcon et dalle pleine). L'étude dynamique de la structure a été entamée dans la troisième partie par logiciel ROBOT 2019 afin de déterminer les différentes sollicitations dues aux chargements (charges permanentes, d'exploitation et charge sismique). En fin l’étude des éléments résistants de la structure (poteaux, poutres, voiles, radier général) sera calculé dans la dernière partie.Mots clés : Bâtiment, Béton armé, ROBOT 2019, RPA99 modifié 2003, BAEL91 modifié 99.ملخص هذا المشروع يقدم دراسة مفصلة لإنجاز بناية سكنية وتجارية تتألف من طابق تحت الارض+ طابق أرضي + 8طوابق بالحشم ولاية مستغانم المصنفة ضمن المنطقة الزلزالية رقم lla حسب المركز الوطني للبحث المطبق في هندسة مقاومة الزلازل . باستخدام القواعد الجديدة للحساب والتحقق من الخرسانة المسلحة RPA99 version 2003, BAEL91 ) (modifié99 تتكون هذه الدراسة من أربعة أجزاء و هم : الجزء الأول: يبدأ بالوصف العام للمشروع ثم إعطاء الأبعاد الأولية للعناصر المكونة له مع عرض لخصائص المواد وحمولة كل عنصر. الجزء الثاني: يهدف إلى دراسة العناصر الثانوية للبناية. الجزء الثالث : يتضمن الدراسة الديناميكية للبناية بواسطة الحاسوب . الجزء الرابع و الأخير : يشمل على دراسة الأجزاء المقاومة للبناية ( الأعمدة ، الروافد ، الجدران المسلحة و الاساسات )الكلمات المفتاحية RPA99V2003 : ، , ROBOT 2019 الخرسانة المسلحة , الدراسة الديناميكيةBAEL91, معدل 99Abstract This project presents a detailed study of a building used for residential and commercial consists of a basement and a ground floor addition (08) floors, located in EL HCHAM in the wilaya of MOSTAGANEM. This region is classified as seismic zone IIa according to the RPA99 version 2003. Using the new rules of calculation and verification of reinforced concrete (RPA99 2003 version, BAEL91 modifié99), this study consists of four parts: The first starts the general description of the project with a presentation of material properties, then the Pre-design of the structure and finally the descent of the load. The second part aims to study secondary elements (beams, stairs, parapet, balcony, elevator, and full slab). The dynamic study of the structure was begun in the third part software ETABS Nonlinear 16 to determine the various stresses due to loads (permanent loads, operational and seismic loading). At the end, the reinforcement of structural elements (columns, beams, walls sails, and raft) will be calculated in the last part.Key words : Building, Reinforced concrete, ROBOT 2019, RPA 99 modified 2003, BAEL 91 modified 99.