Discrete Raman amplifier have many attractive aspects over rare-earth doped fiber amplifier such as (EDFA) including arbitrary gain band, better adjustability of gain shape, and better linearity. This paper shows that discrete Raman amplifier has higher gain in bidirectional pumping than counter pumping. The gain increases with increasing fiber length, and the noise figure remain at the same value for short fiber length.

The objective of this in vivo study is to investigate the effects of 337.1 nm pulsed N2 laser on cellular immune response represented by lymphocyte transformation capacity and phagocytosis activity in laboratory animals. The samples include 60 adult male BALB/c mice, were divided into control group and experimental groups. The experimental groups were divided into two main groups according to the time period after N2 laser irradiation. Each group was divided into 9 subgroups which exposed to N2 laser radiation at different values of pulse repetition rates and exposure times. The results of immunological tests demonstrated that the exposure to 180 J/cm2 of N2 laser radiation induce adverse effect to cellular immune response. The results o

In this work, results of a mathematical analysis of the role of workpiece preheating in laser keyhole welding were presented. This analysis considered the steady-state welding as well as certain range of boundary conditions over which preheating effect would be indicated. This work is an attempt to interpret the role of preheating to increase welding depth and perform keyhole welding with high quality using physical and thermal properties of steel alloys.

The propagation of laser beam in the underdense deuterium plasma has been studied via computer simulation using the fluid model. An appropriate computer code “HEATER” has been modified and is used for this purpose. The propagation is taken to be in a cylindrical symmetric medium. Different laser wavelengths (1 = 10.6 m, 2 = 1.06 m, and 3 = 0.53 m) with a Gaussian pulse type and 15 ns pulse widths have been considered. Absorption energy and laser flux have been calculated for different plasma and laser parameters. The absorbed laser energy showed maximum for  = 0.53 m. This high absorbitivity was inferred to the effect of the pondermotive force.

تضمن البحث تحقيق مخطوط"، سرور الفؤاد بالصافنات الجياد في معرفة الخيل
وأسمائياالشيخ محمد العمري" وكما ظاىر من عنوان المخطوط إنوُ يتناول الخيل، والخيل
موضوع ميم في حياة العربي قبل الاسلام باعتباره يمثل جزءاً من تفاصيل حياتو الملازمة لوُ
واعتماده عمييا ىذا أولاً وثانياً ماتحمموُ الخيول من معاني الفروسية والعنفوان وماتثيره في
الأنسان من حب الأقتناع والمتعة المتحققة من النظر إلييا وحبو لمسبق،

The microstructures of rapidly solidified laser clad layers of laser cladding of Inconel 617 with different nickel-aluminum premixed clad powders are discussed. The effect of different cladding speeds on the microstructures of rapidly solidified laser clad layers is discussed too. The detailed microstructural results showed that different growth mechanisms are produced during rapid solidification. These are planar, cellular, cellular/dendritic and dendritic.

One of the troublesome duties in chemical industrial units is determining the instantaneous drop size distribution, which is created between two immiscible liquids within such units. In this work a complete system for measuring instantaneous droplet size is constructed. It consists of laser detection system (1mW He-Ne laser), drop generation system (turbine mixer unit), and microphotography system. Two immiscible liquids, water and kerosene were mixed together with different low volume fractions (0.0025, 0.02) of kerosene (as a dispersed phase) in water (as a continuous phase). The experiments were carried out at different rotational speed (1180- 2090 r.p.m) of the turbine mixer. The Sauter mean diameter of the drops was determined by la

Diabetic retinopathy is one of most important complications of diabetes mellitus that can be treated by Nd:YAG laser. Laser is used in ophthalmic practice for photocoagulation and photodisruption. The purpose of this study is to evaluate changes in immunological ,hematological and biochemical values after treatment of diabetic retinopathy by laser. Blood samples from 10 patients suffering from diabetic retinopathy were taken before and after laser treatment to coagulate retina to prevent leakage and hemorraghe to avoid deterioration of vision.In group one (4 patients = 40%), blood tests were done one day after treatment. In group two (6 patients =60%) tests were done 7 days after treatment with laser. The study showed no clear changes in

تعدّ د راسة تاريخ الأزياء من أهم العوامل التي توضح مدى التقدم الحضاري
والاقتصادي لأي شعب من شعوب العالم .

يعد التعلم النشطعملية نشطة ذهنية يبذٌل بها العقل الجهد الكافي لإِكتشاف المعرفة فالمعلمليس ناقلاً فيه للمعرفة ،) وانما مرشداً وموجهاً والمتعلم محور العملية التدريسية فيه،إِي عمليةإِبداع يختار منها المعلمما يستطيع الابداع فيه وتركيبه)حارص، 2015:6 والتعلم النشط طريقة تعاونية يشترك فيها جميع المتعلمين بالأنشطة والواجبات المتنوعة التي تسمح لهم بالأصغاء الإِيجابي والتحليل السليم للمادة والتفكي ا رلابداعي اذ تت