Moath Mohammed Al Malki, Taher Laoui

كلية الهندسة-جامعة الملك فهد للبترول والمعادن · السعودية

Si3N4 ceramics are known for their outstanding performance in challenging environments. However, due to the covalent binding present between Si and N, fully-dense Si3N4 ceramics are difficult to achieve via solid state sintering. Thus, SiAlON ceramics have been introduced into the field, in which part of Si and N are replaced by Al and O, respectively.The use of nano-size starting powder materials in the present work proved its positive impact in accelerating the reaction kinetics, yielding lower sintering temperature and shorter holding (dwell) time. Spark plasma sintering technique was utilized for consolidation to benefit from its novelty in limiting phase transformation and undesirable grain growth, along with being an economical processing route when compared to conventional sintering techniques. Furthermore, calcium (Ca) additive was shown to enhance the densification and wetting through the production of a liquid phase, with the least crystal distortion in α- SiAlON unit cell, which was reflected in a higher stability of the latter phase.Aluminum (Al) metal precursor was also explored in the context of improving sinterability at lower temperature, by partial substitution of aluminum nitride (AlN), up to 30% mol. It was observed that by such replacement, Ca- α- SiAlON could be sintered at lower peak temperature (1450oC) with either retained or enhanced mechanical properties. Additionally, Al metal precursor was shown to be a novel tool in preserving α-SiAlON at high sintering temperature (1600oC) by hindering alpha to beta phase transformation. Si metal precursor was examined as well in a similar context, however, it did not show the same behavior due to the limited chemical reactivity and its relative high melting point when compared to Al metal.Barium (Ba) additive was also investigated in this study to establish a basis for comparison with Ca additive. The formation of S-SiAlON was shown to be typical with Ba additive. Moreover, an increase in the amount of β-phase occurred when β-Si3N4 was introduced into the starting mixtures in place of amorphous Si3N4. The mechanical properties of the sintered Ba-SiAlON were far below than those of Ca- α- SiAlON due to the ionic radius of Ba, which lowered the stability of α- SiAlON, and the presence of low- hardness phases, such as SiO2 and S-SiAlON.In an attempt to improve the fracture toughness of sintered Ca- α- SiAlON ceramics, post- sintering heat treatment of selected samples was carried out at 1500oC for 12 hours in Ar environment. The fracture toughness was measured using crack indentation technique. An enhancement in the fracture toughness was observed after heat treatment, due to several contributing phenomena, such as crack deflection and crack bridging mechanisms as well as alpha to beta phase transformation. As a result of the devitrification process after heat treatment, Ca amount and N:O ratio increased in the grain boundary, as revealed by energy dispersive spectroscopy analysis, leading to harder grain boundary and, consequently, intergranular crack propagation.

الطيب لحيلح, عواطف العمري

كلية العلوم الاقتصادية والتجارية وعلوم التسيير-جامعة العربي بن مهيدي - أم البواقي · الجزائر

تعتبر أزمة السكن في الجزائر أحد أهم المشاكل التي عجزت كل الحكومات المتعاقبة في البلاد على حلها، وفشلت كل السياسات المرتبطة بالقطاع من القضاء عليها، فهي أحد أهم عوامل التوترالاجتماعي ومصدر لكثير من الاحتجاجات التي تشهدها الجزائر.فالحضيرة السكنية الوطنية التي تزيد عن 6 ملايين وحدة سكنية، تبدو عاجزة عن استيعاب الطلبات المتراكمة لسنوات، نتيجة عجز الدولة من مواكبة هذا الطلب المتزايد على السكن، خاصة في ظل الزيادة السكانية الأخيرة التي قدرت بـ 2.16% مقارنة بسنة 2011. فبالرغم من اعتمد سياسة وطنية لمحاصرة هذا المشكل في مستويات مقبولة، بانتهاج منذ البداية سياسة سكنية اجتماعية لتمكين كل أبناء الشعب من الحصول على حقهم فيالسكن.إلا أن الواقع أثبت فشل هذه السياسات بالنظر لما واجهته من عراقيل عقدت المشكلة أكثر. من هنا كان لابد من تنظيم سوق العقار في الجزائر بما يتماشى مع الواقع المعيش،معإلغاء الفوائد نهائيا عن القروض الموجهة لها، بغرض تفادي الوقوع في مشكل الربا الذي ينفر منه الكثير من الجزائريين، هذا من جهة ومن جهة أخرى، لما قد يفعله التمويل الإسلامي من تنشيط للسوق السكني لامتلاكه صيغ وأساليب ملائمة للتمويل العقاري من صيغ الاستصناع والسلم، ومراعية لأوضاع الأفراد ذوي الدخول الضعيفة

Davor Svetinovic , Selamawit Tuku Woldeamlak

جامعة خليفة · الامارات

Complex systems, which are a focus of research and development, exhibit important characteristics that might limit the applicability of traditional systems engineering techniques. These Research-Intensive Complex Systems (RICS) are characterized through the existence of multiple proposed preliminary architectures, no implemented prototypes, no agreed upon standards and protocols, and overall lack of uniform vision of goals and requirements. RICS requirements are not well defined, and RICS are exposed to a wide variety of risks and uncertainties. The main source of the RICS domain knowledge, requirements, and goals are research publications and reports. There is often a lack of clear goals, and many goals are ambiguous or conflicting. However, it is important to get goals for RICS right in order to gain early market advantage, satisfy stakeholders, and leverage research investment efforts. This thesis evaluates the effectiveness of the Knowledge Acquisition in aut Omated Specification (KAOS) method applied to smart metering system, as an example of a sustainability-related RICS. The evaluation is performed using a set of qualitative criteria with respect to KAOS's ability to elicit and specify goals for RICS in comparison with the implemented goal models.

Cherrad Yasmina, Hanachi Daouia

كلية الاداب واللغات-جامعة الاخوة منتورى - قسنطينة 1 · الجزائر

Lamia Messali, Makhlouf Fedila, Sahra Meddour

كلية الآداب واللغات-جامعة عبد الرحمان ميرة - بجاية · الجزائر

Tazrawt-nneɣ terza taɣult n tesnalmudt n tutlayt n tmaziɣt, tewwi-d ɣef tzabut deg uselmed n tirawalt aswir wis kraḍ, aɣerbaz alemmas, iswi-nteɣ ad d-nesken tamlilt n ulaɣmu n tzabut deg usnerni n tzemmar n tirawalt ɣer yinelmaden.Amahil-a yebḍa ɣef sin n yixfawen, Ixef amezwaru yerza tiẓri d tesnarayt, yebḍa ɣef sin n yiḥricen, aḥric amezwaru d tiẓri, yewwi-d ɣef uselmed n tirawalt akked tzabut, nsassen-d deg-s tabadut n tirawalt, tixutert i tesɛa, tisekkiwin-is d uselmed-is, syin akkin yezzi-d wawal ɣef tzabut. Aḥric wis sin d tasnarrayt, nsassen-d dɣa tasnarrayt i neḍfer deg tezrawt-a, deg-s nemmeslay-d ɣef tmental n ufran n usentel akked wannar ideg nga tasestant, syin akkin newwi-d ɣef tfukas d tarrayin i neḍfer i ugmar n yinefkan d tesleḍt-nsen. Ma d ixef wis sin d ixef n tesleḍt n yinefkan, yebḍa ɣef sin n yeḥricen, aḥric amezwaru, nesleḍ deg-s inefkan n tannayt, i d-negmer deg kraḍ n temsirin n tirawalt i neḥḍer deg tneɣrit n uswir wis kraḍ, aɣerbaz alemmas, akken ad nesken amek i d-llant. Ma d aḥric wis sin, tella-d tesleḍt n leqdicat n tzabut n yinelmaden, iwakken ad nẓer ma smersen timsirin-a n tirawalt, ma lemdent-tent. S wakka, ad nẓer ma alɣamu n tzabut yettɛiwin inelmaden akken ad lemden tirawalt.Ɣer taggara, nefka-d igemmaḍ i yellan d tiririt ɣef usteqsi agejdan akked turda i d-nessebded

Abba Kolo, Rami Mohamad Fayad

الجامعة البريطانية في دبي · الامارات

The overarching purpose of this research is to discourse and contribute to the limited body of research addressing the extraordinary power of the employer to vary according to the UAE laws and FIDIC forms of contracts. The research is inspired by the need to help parties to a construction contract understand the power of the employer and the employer’s representative to vary, and to understand the protection given to the contractor in case there is a variation instruction.Gaining this understanding will go a long way to help reduce the number of disputes, which often slow down constructions thus affecting the industry, which immensely contributes to the economy of the UAE. Apart from interpreting different clauses in the UAE Civil Transaction Code (CTC) and FIDIC forms such as the Red Book, the paper also reviews relevant cases within and without the UAE jurisdiction. The paper concludes that while an employer’s power to vary is indeed extraordinary, it is justified to a large extend. The intention is to ensure that the employer, who might be a novice when it comes to construction and the relevant laws, is able to complete the project regardless of unforeseen circumstances. The paper also asserts that, the contractor is protected from unfair enrichment or exploitation by the employer.

Farah Chala, Lina Besseghir, Mahdi Cheradi, Samia Bouaziz-Cheradi

كلية هندسة معمارية-جامعة مولود معمري - تيزي وزو · الجزائر

Ce mémoire de fin d’études porte sur la revalorisation du site de Raïs Hamidou, situé sur un territoireriche en histoire et en traditions maritimes, le site souffre aujourd’hui d’un manque de mise en valeur,malgré sa forte valeur patrimoniale, sociale et paysagère. Face à la rupture entre l’urbain et la mer, et àla négligence de la culture maritime locale, notre projet vise à réactiver le lien entre la ville et la mer,tout en répondant aux besoins actuels des habitants, à travers la création d’un centre de loisirs et deculture maritime. Une attention particulière a été portée à l’inclusion sociale, notamment à travers des espaces dédiés aux femmes, afin de renforcer la mixité sociale.Mots clés : revalorisation, culture maritime, loisirs, mixité sociale.

Momen Ahmed Dahab Abdulatif, Elfadil Zakaria Yahia

كلية الدراسات العليا-جامعة السودان للعلوم والتكنولوجيا · السودان

The Optimal Power Flow Problem is a large and complicated non-linear optimization problem in power system transmission, design, planning and operation subjected to various types of constraints. This research focuses on the understanding of Optimal Power flow (OPF) using Linear programming (LP) optimization method, firstly, the OPF problem is discussed in a literature manner in view of the historical review, problem formulation and the different methods that used in order to solve the OPF problem, then a detailed illustration of LP as an optimization tool, likewise, Linear programming Optimal Power Flow (LPOPF) using Piecewise linear approach and the full AC Incremental LP method illustration and mathematical formulation was presented, moreover a conceptual review of reactive power pricing and a proposed formulation of including the VAR cost function to the objective function was presented, lastly, a brief illustration about the Locational Marginal Prices (LMPs) and an implementation of both methods using POWERWORLD Simulator and Microsoft Excel on the 6-bus test system using step by step procedure and the IEEE 30 bus system was made, and then a comparison between both methods before and after the OPF and before and after the inclusion of the VAR cost function was presented.

Stephanie Abboud, Elie Al Hindy

كلية الحقوق والعلوم السياسية-جامعة سيدة اللويزة · لبنان

Lebanon, the second smallest state in the Middle East, has been influenced by numerous foreign interventions, of which most significant are those by, regional and global powers, the French Republic and the United States of America. Beyond their direct military presence in the past, both the US and France have been constantly accused of meddling in Lebanon’s internal affairs. In the past few years, the United States had been regularly imposing sanctions on Lebanese companies and individuals, whereas, more recently still, France was becoming directly involved in the Lebanese political crisis. Indeed, while, both, USA and France have each, and even together at times, intervened in the internal issues of Lebanon, they have not always agreed on their foreign policy – not just in Lebanon. At times, some of their viewpoints and practices of foreign policy have converged, coming together to meet at a common understanding – at other times still, these have diverged, differing from each other in path and direction. After the Port of Beirut explosion on the 4th of August 2020, the President of the French Republic arrived in Lebanon and assured the Lebanese people that France will help the country find a path to reform. Standing in his way, however, were many obstacles, among which were the United States’ sanctions and foreign policy towards Lebanon. Since then, while some suppose that French efforts to get all parties on the table have been significantly delayed and impeded by the United States’ foreign policy towards Lebanon, many others believe that France and the United States have been coordinating every step of the way. This thesis studies the convergence and divergence of American and French foreign policy, taking Lebanon as a case study and specifically after the 31st of October 2016. It provides an up-to-date reading of the current foreign policy of the US and France towards the situation in Lebanon and of where these policies could be heading in the future.

Amina Mataoui, Zoubida Haddad

كلية الفيزياء-جامعة العلوم والتكنولوجيا هواري بومدين - الجزائر · الجزائر

Dans la première partie de ce présent travail de thèse, on a étudié numériquement le transfert thermique par convection naturelle du CuO-eau nanofluides pour une configuration de Rayleigh-Bénard. Cette étude a été effectuée en considérant l’effet du mouvement Brownien et l’effet thermophorèse. Les résultats trouvés sont comparés au cas où les deux effets sont négligés. Il a été trouvé que le transfert de chaleur est plus prononcé à faible concentration volumique de nanoparticules et lorsque le mouvement Brownien et l’effet du thermophorèse sont pris en considération. De plus, une détérioration du transfert thermique est observée quand on néglige le mouvement Brownien et l’effet du thermophorèse. Dans la seconde partie de notre étude, on a mesuré la conductivité thermique et la viscosité dynamique du SiO2─eau nanofluides pour différentes fractions volumiques des nanoparticules et différentes températures. Il a été observé que la conductivité thermique du nanofluide est en bonne concordance avec la théorie de Maxwell ; l’écart relatif de nos résultats et ceux du modèle de Maxwell est inférieur à 3.3%. En outre, la conductivité thermique mesurée ne montre aucune amélioration due à des effets associés aux mécanismes proposés pour le transfert thermique dans les nanofluides. Comme par exemple, le mouvement Brownien. De plus, la viscosité augmente avec la concentration des particules et diminue avec la température ; à 20°C. A une fraction massique de 20%, la viscosité du SiO2─eau nanofluides est d’environ deux fois la viscosité de l’eau. De plus, la viscosité relative ne varie pas significativement avec la température; elle diminue légèrement d’environ 4.8% seulement pour une concentration massique de 20%. Ce qui confirme clairement la dépendance de température. La viscosité du nanofluide est principalement en fonction de la température et de la viscosité du fluide de base. En outre, une analyse rhéologique a montré que le SiO2─eau nanofluide présente un comportement Newtonien. Finalement, les corrélations actuellement proposées dans la littérature notamment pour l'évaluation de la viscosité et de la conductivité thermique des nanofluides n'étaient pas appropriées et sous (ou sur) estimaient les résultats expérimentaux. Les écarts relevés sont dus à la précision des mesures de la taille moyenne des particules dans le fluide de base.