Abstract During the last years there has been an increasing consciousness of the environmental problems, created by the use of fossil fuels in electrical power generation consumed by converting cooling systems. In addition, the use of common working fluids (refrigerants), with their ozonedepleting and global warming potential, has become a serious environmental problem. This underlines the need to implement advanced, new concepts in building air-conditioning. The most common global type of thermally driven technology to produce chilled water is absorption cooling. For air-conditioning applications, absorption systems commonly use the water/lithium bromide or ammonia/water as working pair of fluids. The objective of this study is to establish a fundamental basis for further research and development within the field of solar cooling. In this study, an overview of possible systems for solar powered refrigeration and airconditioning systems will be presented. The concept of the ‘Solar Cooling Path’ is introduced, including a discussion of the energy source to the collector. Brief information and comparisons of different absorption refrigeration cycles are also presented. A solar-driven absorption refrigeration system has been selected as a case study for a further detailed investigation. A low temperature heat source can be used to drive the absorption refrigeration cycle, making the system suitable for integration with solar thermal collector. The Transient System Simulation program (TRNSYS) and Engineering Equation Solver (EES) simulation tools are used to model and analyze the performance of a solar-driven absorption refrigeration system. Analysis of the absorption cycle system is initiated by steady-state analysis. A modeling of single effect water/lithium bromide absorption cycle was constructed to study the effect of the operating variable on the system performance and to determine the optimum operating conditions for the absorption cycle. This model was developed by Engineering Equations Solver program (EES). In practice, the ambient conditions and solar radiation are not constant. Therefore, a dynamic analysis is useful for determining the characteristics of the system during the entire year, and dimensioning the important components of the solar collector subsystem, such as storage tanks and collector area. The overall solar absorption cooling system has been simulated by the TRNSYS program with a typical meteorological year file containing the weather parameters for the capital of Libya, Tripoli. Finally, a parametric study was carried out to investigate the influence of key parameters on the overall system performance of solar absorption cooling system and hence to improve and optimize the system design. Results from the parametric optimization indicated that with an area of 130m2 of flat plate collectors with an inclination of 32° and 3.5m3 of storage tank is achieved to cover the demand of air conditioning of a 35kW absorption chiller.
إبراهيم محمد علي الطويري (2011)

تمتلك ليبيا شبكة طرق كبيرة و تمتد فى كافة الاتجاهات ، و تجتاز الأقاليم المناخية المختلفة السائدة في ليبيا، و مع التطور العمراني الكبير الذى تشهده البلاد في مختلف المجالات مما يتطلب العمل على إنشاء شبكات طرق جديدة أو صيانة الطرق القائمة، فإنه بات من الضروري ضبط و مراقبة جودة الخواص الهندسية لمواد إنشاء الطرق والتي هي من أهم العوامل التي تؤثر على جودة الطرق . وتقاس الخصائص الهندسية للمواد المستخدمة في الرصف بواسطة أخذ عينات وعمل التجارب المعملية اللازمة ، وذلك للتحقق من جودتها ومواصفاتها الهندسية ، وحيث أن الركام هو المكون الرئيسي المستخدم في خلطات الرصف الإسفلتي والذي يتحمل الإجهادات المختلفة التي يتعرض لها منشأ الرصف خلال وجوده في طبقات الرصف المختلفة فإن عدم وجود دراسة شاملة لتوثيق خواص الركام المستخدم في تنفيذ الخلطات الإسفلتية في جميع مناطق ليبيا خلق مشكلة كبيرة وخاصة أثناء تنفيذ الطرق أو صيانتها وذلك لعدم معرفة خصائص مصادر الركام لكل منطقة ومدى ملائمتها للخواص الفنية المطلوبة لاستخدامها في أعمال الرصف .جاءت هذه الدراسة البحثية لتوثيق خواص الركام المستخدم في تنفيذ الخلطات الإسفلتية لأربع مناطق في ليبيا وهي كالأتي : المنطقة الشمالية الغربية.المنطقة الوسطى.المنطقة الشمالية الشرقية.المنطقة الجنوبية الغربية.حيث تم جلب عينات ركام مختلفة وبشكل عشوائي من عدة محاجر لكل منطقة من مناطق الدراسة المذكورة مع توثيق دراسة حقلية لكل محجر والتي تبين موقع ونوع الكسارة و مصدر الركام (جبل – وادي) وبعد ذلك تم عمل الإختبارات التي تحدد خواص الركام وشملت هذه الإختبارات الأتي : اختبارات التحليل المنخلي Tests Sieve Analysis ،اختبارات الكثافة والامتصاص Specific Gravity And Absorption Test ،اختبارات القوة للركام Strength Tests وتشمل :- اختبار لوس أنجلس Los Angeles Abrasion Test ،اختبار قيمة الصدم Impact Value Test ،اختبار قيمة التهشيم Crushing Value Test،اختبار قيمة المكافئ الرملي Sand Equivalent Value Test ،اختبارات تحديد الشكل Shape Tests،اختبارات التحليل الكيميائي والمعدني للركام Chemical and Mineral Composition of the Aggregates نتائج الإختبارات موضوع الدراسة كانت جيدة حيث أعطت الهدف المنشود من هذا البحث والمتمثل في توفير وتوثيق المعلومات الخاصة بخواص الركام لكل منطقة من مناطق الدراسة بحيث يسهل الوصول إليها والتعرف على مصادر وخواص الركام لكل محجر في هذه المناطق. Abstract Libya has a large road networks and extends in all directions of the country. Due to the highways development plan carried by the government to maintenance the existing road network or a new network construction it becomes a very important to Recognize and study the mechanical physical and chemical properties of the materials used in highway construction. These properties of pavement materials could be measured by taking samples and making necessary laboratory tests to verify the quality and the actual technical properties of these materials. Where the Mineral aggregates are one of the main components of the asphaltic concrete mixtures to resist the applied stresses on pavement in service, thus the lack of a comprehensive study to document the properties of aggregates used in asphaltic concrete mixture for all areas in Libya will be necessary , because there is no knowledge about the properties of aggregates sources for each area and their suitability for the technical properties required for using in the pavement construction.This study aims to document the properties of aggregates used in asphaltic concrete mixture from four areas in Libya. These regions as follows: North-western region.The central region.North-eastern region.South-western region. Different samples of these aggregates hare beam taken randomly from several sources for each area. Field study wear carried out, which reveals location, type and origin of each source (mountain, valley), and then laboratory tests were done to measure the properties of these aggregates. These tests are: Sieve Analysis Tests.Specific Gravity and Absorption tests.Strength Tests, and includes: Los Angeles Abrasion Test.Impact Value Test.Crushing Value Test.Sand Equivalent Value Test.Shape Tests.Chemical and Mineral Composition of the Aggregates. The results of these study give the eon get aim of this research in terms of providing and documentation the data related to properties of the aggregates for each region of the study, to ease the access to these data and identify the sources and properties of the aggregates for each source in these areas.
فضل محمد إدريس محمد (2012)

In this paper, we present an analytical traffic model for the Universal Mobile Telecommunication Systems (UMTS). In 3G networks we have dynamic capacity that depends on the interference levels in the covered area and the number of active users. This implies that the distance of the mobile user from the base station is also an important factor because of the signal fading. The first part of this paper is an algorithm written in c++ programming language that distributes users in different zones assuming that the cell area is virtually divided into Z zones depending on the number of users. The last part of this paper we build a mathematical model of a 3G cell using the above assumption , and to prove, that the product form holds in the case of two cells with uniform and non uniform traffic. By this result more complicated networks can be analyzed, to calculate the performance measures of the network.
WAEL S. ABUGHRES, MIKE E. WOODWARD(6-2006)