Computational study of three-dimensional laminar and turbulent flows around electronic chip (heat source) located on a printed circuit board are presented. Computational field involves the solution of elliptic partial differential equations for conservation of mass, momentum, energy, turbulent energy, and its dissipation rate in finite volume form. The k-ε turbulent model was used with the wall function concept near the walls to treat of turbulence effects. The SIMPLE algorithm was selected in this work. The chip is cooled by an external flow of air. The goals of this investigation are to investigate the heat transfer phenomena of electronic chip located in enclosure and how we arrive to optimum level for cooling of this chip. These parameters, which will help enhance thermal performance of electronic chip and flow patterns, through the understanding of different factors on flow patterns. The results show the relation between the temperature rise, heat transfer parameters (Nu, Ra) with (Ar, Q) for two cases of laminar and turbulent flows.
Background: The long term survival of dental implants is evaluated by the amount of crestal bone loss around the implants. Some initial loss of bone around dental implants is generally expected. There is reason to believe that reflecting a mucoperiosteal flap promotes crestal bone loss in the initial phase after an implant has been inserted. The surgical placement of a dental implant fixture is constantly changing and in recent years, there has been some interest in developing techniques that minimize the invasive nature of the procedure, with flapless implant surgery being advocated. The purpose of this study was to compare the radiographic level of the peri- implant bone after implant placement between traditional flapped surgery and f
... Show More
(1)
This paper deal with the estimation of the shape parameter (a) of Generalized Exponential (GE) distribution when the scale parameter (l) is known via preliminary test single stage shrinkage estimator (SSSE) when a prior knowledge (a0) a vailable about the shape parameter as initial value due past experiences as well as suitable region (R) for testing this prior knowledge.
The Expression for the Bias, Mean squared error [MSE] and Relative Efficiency [R.Eff(×)] for the proposed estimator are derived. Numerical results about beha
... Show More
(3)
(1)
Free water surface constructed wetlands (FSCWs) can be used to complement conventional waste water treatment but removal efficiencies are often limited by a high ratio of water volume to biofilm surface area (i.e. high water depth). Floating treatment wetlands (FTWs) consist of floating matrices which can enhance the surface area available for the development of fixed microbial biofilms and provide a platform for plant growth (which can remove pollutants by uptake). In this study the potential of FTWs for ammoniacal nitrogen (AN) removal was evaluated using experimental mesocosms operated under steady-state flow conditions with ten different treatments (two water depths, two levels of FTW mat coverage, two different plant densities and
... Show More
(8)
(8)
ملخص البحث
العولمة ظاهرة اقتصادية سياسية اجتماعية لها انعكاساتها المختلفة على المجتمعات وعلى منظمات الأعمال في مختلف دول العالم، هذه الظاهرة أدت إلى المزيد من النتائج التي زادت منظمات الأعمال في الدول الغنية غناً وزادت منظمات الأعمال في دول العالم الثالث فقر، وقد ترتب على ذلك نتائج ايجابية لدى المجتمعات الغربية والمؤتلفة معها بسبب سيطرة منظمات الأعمال في تلك الدول على الأسواق في البلدان الن
... Show More
In research it is an important phonemic change for the speaker to reach Ease and lightness ,wich is the kinetic follow-up , and we tried to collect the scattered matter in the various dialects
The research intended to take into consideration the phenomena of employing the temporary employees through the business organization increasingly, which has become one of the most apparent features of the contemporary strategy of the human resources management. It depends on the analytical descrptive Approach to meet the research problem which has been focalized around the dispute praising regarding the phenomena of the temporary employment and its dimensions and challenges which can be faced by the management of human resources as a result .The importance of the research is represented as one of rare research which confronts to the phenomena of the temporary employment in the Iraqi business environment. The most prominent objec
... Show More
In research it is an important phonemic change for the speaker to reach Ease and lightness ,wich is the kinetic follow-up , and we tried to collect the scattered matter in the various dialects.
it is studied with the ancient and modern Showing the occurrence of this term between both sides Then we clarified the phoneme explanation for this phenomenon
احتلت قضية غسيل الاموال أهمية كبيرة على الساحة الاقتصادية العالمية خلال الفترة الاخيرة إدراكا من المجتمع الدولي لأثارها السلبية على الاستقرار الاقتصادي و خاصة على الاستثمار المحلي و الدولي و لذلك يتزايد الاهتمام بها و سبل مواجهتها من قبل العديد من الدول و المنظمات الدولية و المراكز المالية الكبرى , حيث تهدد هذه الظاهرة الاقتصاد العالمي و خاصة اقتصاديات العالم النامي و من بينها الاقتصاديات العربية .
ان
... Show More