تتناول هذه الدراسة إمكانية استخدام الأرض كوسيط تبريد لمبادل حراري في نظم تكييف بالمباني بديلا عن الهواء الجوي، وحيث أن تقييم الخواص الحرارية للأرض هامة جداً لمعرفة مدى نجاح هذا النظام فقد أجريت تجربة عملية للتحقق من ذلك. ومن اجل إنجاز هذه التجربة ثم دفن أنبوب عمودي في باطن الأرض ليتدفق من خلاله الماء عبر دائرة مغلقة، وتم تزويد المياه بكمية ثابته من الحرارة مناظرة للحرارة التي يفقدها المبادل الحراري في نظام التبريد الهوائي. غير أن الهدف من هذا الاختبار دراسة التغير في درجة حرارة المياه الداخلة والخارجة من الأنبوب المدفون في باطن الأرض أثناء تزويد المياه بالحرارة خلال فترة زمنيه، وهذا الاختبار يسمي باختبار الاستجابة الحرارية للأرض.لقد أوضحت النتائج المتحصل عليها أن درجة حرارة خروج المياه من الارض تكاد تكون ثابتة بعد فترة زمنية قصيرة من زمن الاختبار،وأن درجة حرارة المياه هذه ملائمة كوسيط تبريد لمبادل حراري في نظام تكييف المباني. كما أن ثبوت درجة الحرارة هذا يساعد في الحصول على حمل تبريد مستقر، وهو ما لا يتوفر عند استخدام الهواء الخارجي كوسيط للتبريد باعتبارهذا ذا درجة حرارة متغيره، وتم الاستفادة من هذا الاختبار في تقييم الخواص الحرارية للارض، وإن هذه الدراسة قد بينت أن الموقع الجغرافي الذي تم اختباره تميز بكفاءة عالية، ومشيرا لإمكانية استخدام هذا النظام في تكييف المباني. Abstract This study is investigating the use of ground as cooling medium in a heat exchanger system for air conditioning of buildings as a replacement to the ambient air. However, evaluating the ground properties is very important to known the range of success of this system. An experimental setup is conducted to realize the above. In order to perform this experiment, a pipe is buried into the ground where the water is flowing in a closed circuit. A constant quantity of heat power is supplied to the water equivalent to the rejected heat from the heat exchanger in the air heat pump system. However, the objective of this experiment is to study the change in the inlet and the outlet water flow temperature from the buried pipe in the ground, during the heat injection to the water for a specific time. This test is called the thermal response test of the ground.The test results are clearly indicating that the outlet water from the ground has a constant temperature after a short duration from the test period. This water temperature is convenient as a heat carrier for air conditioning of buildings. This constant water temperature is also assisting in obtaining a constant cooling load. This can not obtained in using the out side air as a cooling carrier where the air is of a changing temperature. This study is indicating that the test site has a high efficiency, and this system can be used for air conditioning of buildings.
عادل احمد سويسي (2008)

Almost all Libyan industries (both private and public) have struggled with many difficulties during the past three decades due to many problems. These problems have created a strongly negative impact on the productivity and utilization of many companies within Libya. This paper studies the current awareness and implementation levels of Just-In-Time (JIT) within the Libyan Textile private industry. A survey has been applied in this study using an intensive detailed questionnaire. Based on the analysis of the survey responses, the results show that the management body within the surveyed companies has a modest strategy towards most of the areas that are considered as being very crucial in any successful implementation of JIT. The results also show a variation within the implementation levels of the JIT elements as these varies between Low and Acceptable levels. The paper has also identified limitations within the investigated areas within this industry, and has pointed to areas where senior managers within the Libyan textile industry should take immediate actions in order to achieve effective implementation of JIT within their companies. arabic 17 English 88
ٌRajab HOKOMA(7-2010)

Abstract Glass fiber reinforced plastic (GRP) pipes, are widely used in many of industrial applications, such as oil industries and petrochemicals plants to transport a wide range of different liquids like fresh water, sea water, lubricant oils, acids and caustic etc. This related to their lightness, corrosion resistance, strength durability, high tensile strength, low density, and ease of installation, so that selected as better than traditional metal pipes in such applications. But the internal surfaces of these pipes can be exposed to slurry erosion due to the impact of sand particles mixed with fluids at high velocity leads to create, catastrophic failure, which limits the useful life of pipes and their efficiency. Therefore the erosion is a critical parameter for design, selection and operation of hydraulic transportation system. This thesis has studied experimentally the Slurry erosion wear behavior of GRP pips at various parameters such as impact angles, and velocity of particles. Jet type erosion tester was used as rig and sand used as solid particle mixture with water. The results clearly indicated that the factors contribute to wear of Pipes. The erosion rate or weight loss increased as time, and velocity of solid particles increased, the effect of impact angles shifts from ductile behavior to brittle behavior depending on the value of erosion efficiency. The comparison between predicted and experimental results shows agreement within ±7% for Epoxy and ±8% for Polyester.
خالد عيسي المحجوبي (2013)