تتعرض هذه الرسالة لدراسة نظرية لنموذجين مختلفين للمجمعات الشمسية، المعدنية وغير معدنية . وذلك لتعين معاملات الأداء لهذه المجمعات مثل معامل فقد الحرارة, عوامل فقد الحرارة الكلية, الكسب الحراري, الكفاءة اليومية, واللحظية.وقد أظهرت هذه الدراسة أن المجمعات المعدنية الشمسية متفوقة من حيت معاملات الأداء على المجمعات الشمسية الغير معدنية, تحت ظروف الجريان القسري. وقد دلت هذه الدراسة أيضا على أن عوامل فقد الحرارة الكلية لكلا النموذجين تظهر تغيرا طفيفا عند التغير في معدلات التدفق. كذلك فإن معامل الفقد الحراري يعتمد بصورة كبيرة على معدل التدفق لكلا لنموذجين, عند استخدام خزانات ذات سعة صغيرة. كما تبين أيضا أن الطاقة المختزنة, في المجمعات غير المعدنية, يمكن أن يستفاد منها كطاقة حرارية مفيدة حتى بعد غياب أشعة الشمس.وقد قورنت نتائج هذه الدراسة النظرية بنتائج دراسات عملية سابقة, و وجد أن هنالك تطابقا جيدا بينهما, ما عدا تلك النتائج التي تم الحصول عليها في ساعات الصباح الباكر وساعات المساء. Abstract This thesis presents a theoretical investigation of metallic and non-metallic solar water collector models for evaluating its performance parameters. The determined parameters include heat removal factor, overall heat loss coefficients, heat gain, daily and hourly efficiencies.The present study reports that, under forced circulation test, the non-metallic collector has an inferior performance parameters when compared to that of the metallic one. It was also revealed that the overall heat loss coefficients of both collectors show weak dependence on the flow rate variations. It was also noticed that the heat removal factor for both models is more sensitive to the flow rate variations when small storage tank capacities are used.The stored energy in the non-metallic flat plate solar collector model constitutes a significant part of the useful energy, even after the diminishing of the solar intensity.Finally, a comparison of performance parameters of the theoretical and experimental studies showed good agreements for most hours of the day, except the results obtained at the early morning and late after noon hours.
نورالدين عبد الحفيظ عبود (2009)

This paper identifies the most affecting factors that enhance the quality of the decision making process within some Libyan oil and gas companies. Based on the developed questionnaire along with the literature review, the analysis showed that it is a challenge to processing the proper procedure for making decisions. However, most decision makers are found to be focusing on using simple tools for making their decisions, whereas, lacking of an effective communication network during making decisions are considered with a negative impact on making the proper decisions within most surveyed companies. Furthermore, it was found that, the procedures for making decisions within most surveyed companies could be considered as the most crucial for improving the quality of the decision making processes, followed by the used tools and techniques, whereas, communications as a factor influencing the processes of making decisions is found to be at the lowest level throughout the entire decision making processes. arabic 15 English 98
Rajab HOKOMA, Hanan Zawam Aburas(3-2018)

Abstract The contribution of this thesis is to improve the understanding of acoustic dynamics in the audio duct with Helmholtz Resonator (HR). In this project, detail measurements of acoustic in a duct with HR induced loud–speaker at various frequencies have been carried out experimentally. Two-microphone technique have been used to measure the net acoustic power transmission in the duct downstream of HR along with the net acoustic power transmission in the duct without the HR. The acoustic wave signals are traveling in the duct as a plane wave, these waves are generated by a signal generator system with a know wave (sine wave). One of the microphone is located just before the neck–duct interface and the other microphone after the HR in the duct. Five type of necks ( perforated neck length 15cm, perforated neck length 10cm, cone–shape neck, Non- perforated neck length 15cm, Non-perforated neck length 10cm ) and three different material of the bottom wall of the cavity ( Teflon, water and cotton ) have been studied. The best results has a good advantage that by using (perforated neck length 15 cm and 4cm diameter because that reduction of noise has been reached 64% percentage and that value is the highest reduction from all experimenting.
إبراهيم فاضل عبد الحميد الزوي (2010)