Magdi Bakur Mahmoud Amin, Mohammed Mustfa Ahmed Rahma, Osman Mohammed Dafa Alla

كلية الهندسة والتكنولوجيا-جامعة الجزيرة · السودان

The aim of this dissertation is to analyze the properties of optical amplifiers. There are many decisions to take so as optimize the implementation of optical amplifiers. To take those decisions, are must analyze group of typical key characteristics of amplifiers such as, gain and noise figure, versus the input wavelength, input power or input pump power. Most optical amplifiers amplify incident light through the gain mechanism, which is the ratio between the input and output of optical signals. According to this Principle, when the values of wavelength, and input power of light source are changed, the values of the gain and noise figure are changed. There are three types of optical amplifiers used, namely semiconductor optical amplifier (SOA), Raman amplifier and Erbium-doped fiber amplifier (EDFA). Optisystem software was used for analysis and implementation. The results showed that the maximum gain at input power of -90 dBm for the SOA was 69.185dB ,in the Raman amplifier it was126.79dB at pump power 36 dBm ,and in the EDFA was 45.459dB. The output power of Raman amplifier totally depends on the pump power. It was concluded that a suitable value for pump power is required to give a suitable value from output power to be detectable by optical receiver.

Barmaki Abdellatif, Z. Zerdoumi

كلية التكنولوجيا-جامعة محمد بوضياف - المسيلة · الجزائر

The purpose of this work is the study of the equalization techniques for digital communication channels. Two equalizers are presented, linear and non-linear namely the transverse linear equalizer (LTE) and the decision feedback equalizer (DFE). The simulations results have shown the performance of these equalizers in terms of constellation of the equalized symbols and the mean square error( MSE) for different communication channels. The linear equalizer LTE works best for linear low distortion channels its performance degrades significantly, for severs and nonlinear channels. The use of the non-linear equalizer DFE has exhibited consistent improvements in performance for all the considered channels.

AHMAD MAHMOUD EL HAJJ, karim kabalan

كلية مارون سمعان للهندسة والعمارة-الجامعة الأمريكية في بيروت · لبنان

The constant evolution in wireless technologies has allowed the advent of a plethora of applications with different quality of service (QoS) requirements. Resource allocation is the process by which the frequency and power resources are efficiently distributed to the users in the network to satisfy their QoS requirements while maximizing as much as possible the network performance. Existing resource allocation schemes have mainly focused on optimizing the users' performance, independently, on either the uplink or the downlink. However, next generation wireless services such as video conferencing and multiplayer gaming are expected to involve many end-to-end interactions between the users. For such services, there is a need to optimize a QoS metric that takes into account, jointly, the uplink and downlink performance of the users. In this dissertation, we propose a joint uplink-downlink resource management framework for the state-of-the-art, orthogonal frequency division multiple access (OFDMA)-based wireless standards. The developed framework will jointly exploit service flow QoS parameters, cross-layer network performance metrics, channel state information, and queue state information in both the uplink and downlink directions. A queue-level analysis of the joint resource allocation process is performed using decentralized Markov decision processes. This is complemented by the development of queue-aware joint uplink-downlink resource allocation approaches that induce a coupling in the queue dynamics at the base station and mobile user sides. Furthermore, several resource allocation problems in an OFDMA network are formulated and solved using optimization and game theoretic techniques. As a special case, we address the particular challenges in employing the time division duplexing (TDD) mode of operation by jointly optimizing the following important design aspects in multicellular TDD-OFDMA wireless networks: the uplink-downlink (UL-DL) switching points, the UL-DL subcarrier allocation, and the UL-DL power alloc

علم الدين موسى علي الحسن, مختار عثمان الصديق

كلية الدراسات العليا-جامعة القران الكريم والعلوم الاسلامية · السودان

هدف هذا البحث هو إبراز أهمية العلاقات العامة في المجال الرياضي . و إبراز مكانتها و وظائفها و وسائل إتصالها المستخدمة بالمؤسسات الرياضية ، و التأكيد على الطابع الخاص للعلاقات العامة كمنظومة متكاملة إهتمت بكل جوانب الحياة البشرية ، و تسليط الضوء على أن الرياضة ليست مجرد مباريات و أبطال ، بل هى مفهوم متكامل يعكس حياة متكاملة و بيان دعوة الإسلام لممارستها .

Abderrahmane Elmegbed, Chiekh Bakou, El Hocine Ben Cheikh, Fatiha Yettou

كلية العلوم والتكنولوجيا-جامعة غرداية · الجزائر

Ces dernières années, beaucoup de pays se tournent vers une bonne exploitation desénergies renouvelables. L'énergie solaire est l'énergie la plus prometteuse, largement disponiblesen Algérie.Ce travail consiste à étudier le dimensionnement de chauffe-eau solaires individuels enélaborant un programme basé sur l’utilisation d’une base de données des capteurs plans et,puisque appliqué à l’Algérie, une modélisation de l’éclairement solaire du pays. L’utilisation demodèles d'estimation de rayonnement solaire reste pratiquement l’un des seuls moyens pourpallie à la rareté des stations radiométriques sur le territoire national. Le programme sera réaliséet programmer à l’aide du langage Matlab et le dimensionnement est effectué en utilisant laméthode f-Chart. D'autres paramètres seront necessaire au programme tell que la températureambiante et la température d'eau froide. Le test de ce logiciel est indispensable et le relever desrésultats est nécessaire pour la validation du travail sur plusieurs villes de l'Algérie.

Roumaissa Hamri, Soumia Zemmouchi Khadidja

كلية الأداب واللغات-جامعة العربي بن مهيدي - أم البواقي · الجزائر

Notre travail de recherche a pour objectif de montrer que la présentation d'un exposé oral permet de développer la compétence communicative, chez les apprenants. Pour atteindre nos résultats, nous avons mené une enquête auprès d'étudiants de première année de licence en français, en optant pour deux outils d'investigation ; à savoir, l'observation et le questionnaire.Les résultats obtenus ont montré que l'exposé oral est une activité qui favorise le développement de la compétence communicative des apprenants. En effet, la présentation de plusieurs exposés permet de libérer la parole et de développer la fluidité verbale de l'apprenant. De plus, la maîtrise d'un sujet avant de le présenter permet à l'apprenant de faire face au stress et à la peur éprouvés lors de la prise de parole devant un public

عبدالعزيز حسن فضل البصير علي, إبتسام محمد أحمد محمد خير أحمد

كلية الدراسات العليا-جامعة السودان للعلوم والتكنولوجيا · السودان

يهدف هذا البحث الى دراسة التغير الاجتماعى والاقتصادى طبيعته ونوعه،وأثره على النظم والعلاقات الاجتماعية للوصول الى اتجاهات التغير فى نظام الزواج، وللكشف عن العوامل الاجتماعية ولاقتصادية التى أدت الى تاخر سن الزواج لدى الشباب فى مجتمع البحث......

إيمان جاد , عبير نجم جمعة بهوان الراسبي

الجامعة البريطانية في دبي · الامارات

Several studies have discussed the position of women in higher education institutions internationally through investigating her career progression and the factors that influenced their advancement to senior leadership positions either in academic or administrative paths, yet, this body of literature lacks any studies on Emirati women’s career development in higher education in United Arab Emirates. The purpose of this research project is to explore the success trajectories of a representative sample of first generation Emirati women in a university case study who are currently in academic and administrative senior leadership positions in order to design a career development model that both accurately describes these paths and inspires Emirati women to pursue leadership positions in higher education institutions in United Arab Emirates. This study uses the perspectives of Super’s Life Span Life Space theory, Lent, Brown, and Hackett’s Social Cognitive Career theory, and Savickas’s Career Construction theory to explore early childhood and adulthood experiences, role model influence, mentoring and networking, and education system critical factors in shaping their career development journey, and the nature of their successful leadership experiences using a qualitative exploratory case study approach.The new model includes family, society, institutional, and governmental influencers. It also investigates other influences like religion, culture, extended family, and self-development.

كرستيان عزام عيسى سعيد, محمد عوض شعيبات

كلية العلوم التربوية-جامعة القدس · فلسطين

جبر محمود الفضيلات, ناصر عمران علي عمران الكواري

كلية الشريعة-جامعة جرش · الاردن