Abstract As user applications continue to drive network growth and evolution, demand to support different types of traffic is also increasing. Different types of applications with differing network requirements create a need for administrative policies mandating how individual applications are to be treated by the network. Network traffic from business-critical applications must be protected from other types of traffic. Requests from business-critical and delay-sensitive applications must be serviced with priority. The employment and enforcement of quality of service (QoS) policies within a network play an essential role in enabling network administrators and architects to meet networked application demands. QoS is a crucial element of any administrative policy that mandates how to handle application traffic on a network. Networks must provide secure, predictable, measurable, and, sometimes, guaranteed services. Network administrators and architects can better achieve this performance from network by managing delay, delay variation (Jitter), bandwidth provisioning, and packet loss parameters with quality of service (QoS) techniques. As the concept of converged network is being widely used today where all types of traffic are required to be sent and transmitted on the same wide area network (WAN) link. Hence different applications need to be differentiated and treated according to their sensitivity to business. QoS is the suitable answer and method to solve this issue and make sure that each traffic type will be treated differently using various mechanisms of QoS. In this research different types of traffic that represent different applications are generated in WAN and local area network (LAN) where various techniques of QoS are implemented. Network performance is indicated by capturing different parameters on real time such as, delay, jitter, packet loss, and bandwidth. Based on results obtained, a set of recommendations is concluded for each QoS mechanism highlighting the suitable traffic type for this technique to be used for along with appropriate network locations for this technique to be implemented.
نسرين عادل بن لطيف (2011)

تعتبر ظاهرة تحرك الكثبان الرملية و وزحفها على الطرق الرئيسية من الظواهر الخطيرة التي تتسبب في حوادث قاتلة وعرقلة لحركة المرور، إضافة إلى الخسائر الاقتصادية الكبيرة . ومن الطرق التي تعاني مثل هذه المشاكل الطريق الرابط بين نالوت و غدامس والطريق الرابط بين الوطية و الجوش والطريق الرابط بين العزيزية و غريان وكذلك طرق الجنوب مثل طريق سبها براك وطريق سبها أوباري ... الخ ، لهذا كان من الضروري القيام بعمل دراسة ميدانية ( حقلية ) للأماكن المتضررة من الطرق وإجراء الاختبارات المعملية اللازمة واقتراح الحلول المناسبة لمعالجة هذه الظاهرة يأتي هذا البحث لدراسة ظاهرة زحف الكثبان الرملية على الطرق المتضررة من هذه الظاهرة والتي تقع في شمال وجنوب غرب ليبيا وهي طريق نالوت غدامس وطريق الجوش الوطية وطريق العزيزية غريان وطريق براك سبها ، حيث تم تحديد القطاعات المتضررة في الطرق سالفة الذكر وإجراء عملية الرفع المساحي لتلك القطاعات للتعرف على وضعية الرمال وحجمها ، حيث تم رسم قطاعات عرضية وطولية لكل القطاعات المتضررة . وكذلك إجراء اختبارات معملية للتربة المكونة لتلك الكثبان والمتمثلة في تحليل الحجم الحبيبي واختبار بركتور المعدل لمعرفة خواص التربة وتصنيفها وذلك حسب نظام تصنيف التربة الموحد ، وتحديد أقصى كثافة جافة ونسبة المياه المناظرة لها ، ونسبة الرطوبة ، كما تم دراسة تضاريس كل منطقة يقع فيها القطاع المتضرر والتعرف على مصادر المياه بها ،والظروف المناخية مثل اتجاهات الرياح السائدة وسرعتها وباستخدام النتائج المتحصل عليها والدراسات السابقة التي قامت بها العديد من الدول التي تتأثر بهذه الظاهرة والتي استعرضنا منها في هذا البحث دراسة كل من الولايات المتحدة الأمريكية والكويت والجزائر ومصر ، تم اقتراح ثلاثة حلول لعلاج هذه الظاهرة وهي مقطع الديناميكا الهوائية والذي تم تجربته في دولة الكويت ، والحل الاستثماري وهو اقتراح قام به الباحث بالرجوع إلى حجم المرور اليومي على القطاعات المتضررة ، و الاقتراح الثالث يتمثل في التثبيت البيولوجي مع مصدات الرياح لتثبيت التربة . وقد تم تحديد أفضل الحلول العلاجية لكل قطاع . Abstract The main aim of this study is to analyze and evaluate the movement and creeping of the sand dune on the main roads considered as dangerous phenomena which caused accidents and resulted in hindering traffic movement. It also caused great economical losses. The roads which suffer from this problem are Nalut - Gadams road, Al Gush – Al Wtyah road and Azizia - Garyian road. Similarly in the south of the Libya there are many roads which suffer from the movement and creeping of the sand dunes, such as Sebha - Brak road, Sebha - Obary road ....ECT. To study this problem it is very important to do a field study about roads that suffer from this problem and need laboratory tests in order to suggest suitable solutions for the treatment of this phenomenon.This study, as indicated above, analyzed and evaluated the movement and creeping of the sand dunes phenomenon in the damged roads located in North and South West of the country. These roads include Nalut-Gadams road, Al Gush-Al watyah road, Sebha-Brak road and Azizia-Gryan road.After identifying the critical section in the above mentioned roads, the researcher carried out a surveying work for sections to identify the sand passivism in relation to the damaged sections and its volume. In this regard, cross sections and longitudinal sections were drawn. Also laboratory sand tests were conducted .These tests include: Sieve Analysis Test. Modified Proctor Test.for identifying sand classifications and characteristics according to its unified system, identifying water dry density and percentage of the parallel water, percentage the humidity. In addition, a study was carried out on the topographic relief of each critical sections to identify the water sources and climatic conditions such as the speed and directions of the dominated winds.The application of the main findings of this study, and other previous studies done by some other countries influenced by this phenomenon, such as United States of America, Kuwait, Algeria and Egypt conclude to three solutions for treating this phenomenon. These solution include: 1- Aerodynamic Profile section which tested in Kuwait. 2- Investment solution which depend on the daily traffic size on the hurt sections. 3- Biological fixing with wind obstructs for fixing the sand. Finally, the best solution for each section was determined.
أبوبكر موسى محمد (2009)

In reinforced concrete design, the concrete in the tensile zone is assumed to be ineffective and increase the dead load of the structural elements. In order to reduce the self-weight, this paper examines the structural behavior of reinforced concrete beams containing lightweight concrete in the tensile region and normal weight concrete in the rest of the beam. The lightweight concrete was made from waste polystyrene. Four reinforced concrete beams were prepared with different depth of lightweight concrete. The control beam B1 consists of normal concrete. In Beams B2, B3 and B4, the depth of lightweight concrete was 25%, 50% and 75% of the total depth of the beam measured from the bottom surface respectively. A four-point bending test was conducted on all beams. The beams were loaded in increments until failure. At each load increment, the central deflection was determined. Cracks initiation and the mode of failure were observed during the experiment. The failure load was found to decreases with the increase of depth of lightweight concrete. The presence of lightweight aggregate tends to cause brittle failure. In addition, the mode of failure for reinforced concrete beams containing lightweight concrete was a shear failure. arabic 11 English 79
Hakim S. Abdelgader(6-2020)