تم دراسة المرنانات غير المستقرة في المنظومة الليزريه بشكل عام والتركيز على أحد المشاكل التي يواجهها هذا النوع من المرنانات وهي تأتيرات الحيود. فرغم ان هذه الظاهرة تعتبرالوسيله التي يخرج عن طريقها الشعاع من المنظومه الليزريه الا انها تسبب في فقدا كبيرا في قدرة الشعاع الليزري الخارج . احدي الطرق المقترحه للتقليل من تاتيرات الحيود السلبيه في هذه الحاله هو احدات تدرج في المرآه , فقد تم في هذا البحث مقارنة نتائج متقاربه وعليه تم استنباط معادلة خاصه بالحيود عبر مرآة بتدرجين وحساب القيمة الذاتية للشعاع الليزري الخارج وتحدي مدي التحسن في التقليل من الخسارة الناتجه من خلال التغير في قيمة عدد فرنيل وذلك بمقارنة العلاقات البيانية لمرآة عادية ومرآة بتدريج واحد وبتدرجين للمرنان نفسه , و تم أيضا دراسة تاثير القيمة الذاتية بعرض الدرجة في المرآة وعرض المنحنيات الخاصة بها . Abstract Unstable resonators in laser systems have been studied in general and the focus was on one of the problem facing this type of resonators namely the effect of diffraction .although diffraction Is the mean to get the laser rays out of the system, it causes major loss of power in the output If it is treated adequately. One of the suggested method to reduce the negative effect of diffraction is to make a gradual step on the output mirror. a comparison has been made between the results for a single step mirror with result from previous study . the two results agreed with each other to an acceptable range . an equation for a two-step mirror was derived and the Eigen Values of the outgoing laser beam were calculated . the amount of improvement in the output power was calculated by changing the value of Fresnel number and comparing the situation for an ordinary mirror , single step mirror and two-step mirror. The results show good improvement for the two-step mirror. also the dependence of the step with on the eigen value was studied. We can conclude from the current work that by introducing certain step width specific width could improve the output power from unstable resonators by minimizing the negative diffraction effect. The amount of improvement seems to increase with increasing number of steps. For future work we suggest that more exact methods to calculate the eigen values, such as proni method, should be tried and the effect of the output mirror tilt must be taken into account.
سهير محمود احمد ابو حجر (2001)

Abstract Murzuq Basin is located in south western of Libya. The theses represent a study of the concession (NC-174) area in Murzuq Basin. This theses consists of two major parts; the first part investigates the geophysical seismic interpretation of the concession (NC-174) area including the Elephant field area, and as a result the pressure of Elephant oil field (western part of (NC-174) concession) is not superior so that it needs to inject water interested in the oil structure. Therefore, the second part of theses provides better understanding of the aquifers study (Aquifers volume, extensions, isolation) within the concession (NC-174) area to be used for water injection of the oil reservoir of Elephant filed. The water injection method used in oil production is where water is injected back into the reservoir usually to increase pressure and thereby stimulate production. In this theses most visible horizons are interpreted by charisma software focused on the all aquifer water and (seal, reservoir, basement) formations, and the seismic interpretation includes all of the available 2-D and 3-D seismic data.The geophysical seismic interpretation method is used to cover the concession (NC-174) area, concentrates on the Elephant oil field using all the available seismic versions datasets. The main result of this thesis indicates that the Ordovician sandstone (Mamuniyat formation) is high-quality oil reservoir in the Elephant oil field and can be represent a saline aquifer outside the Elephant oil field structure (scorpion area_ southeast of Elephant oil structure ) either to the northern or southern hanging wall unless the main faults are not sealing. The Mamuniyat reservoirs sourced by hot shales of the Lower Silurian Tanezzuft Formation.
عادل المبروك التوجير (2009)

حل مسالة القيمة الذاتية للنمطين الكهربي TE و المغناطيسي TM المستعرضين لالفالم الرقيقة دورية الطبقات. arabic 241 English 4
عبدالسلام إمحمد إبراهيم ابوبكر, عبدالعزيز أحمد الكويلاني, علي امحمد بشير المجاهد(7-2019)