Porous silicon (P-Si) has been produced in this work by photoelectrochemical (PEC) etching process. The irradiation has been achieved using diode laser of (2 W) power and 810 nm wavelength. The influence of various irradiation times on the properties of P-Si material such as P-Si layer thickness, surface aspect, pore diameter and the thickness of walls between pores as well as porosity and etching rate was investigated by depending on the scanning electron micrograph (SEM) technique and gravimetric measurements.
An experimental and numerical study has been carried out to investigate the heat transfer by natural convection in a three dimensional annulus enclosure filled with porous media (silica sand) between two inclined concentric cylinders with (and without) annular fins attached to the inner cylinder under steady state condition; The experiments were carried out for a range of modified Rayleigh number (0.2 ≤Ra*≤ 11) and extended to Ra* =500 for numerical study, annulus inclination angle of (δ = 0˚, 30˚, 60˚ and 90˚). The numerical study was to write the governing equation under an assumptions used Darcy law and Boussinesq’s approximation and then solved numerically using finite difference approximation. It was found that the averag
... Show MoreAbstract:
This study deals with the influence of the industrial buyer behavior in Channels of distribution. It concentrates on one section of management levels in the company. Which is that of administrative managers The research problem is attempt to study and analysis the influence of industrial buyer behavior in channels of distribution.. The aiming at achieving a number of applicable goals depending on one major hypotheses I set a questionnaire in collecting the data and information relating to the study، which was distributed to sample of ( 30) department manager heads of section states company . In order to process the data resorted to many statistical methods such as arithmetic means the sta
... Show MoreCollapsible behaviour of soil is considered as one of the major problems in the stability of roadway embankment, the lack of cohesion between soil particles and its sensitivity to the change of moisture content are reasons for such problem. Creation of such cohesion may be achieved by implementation of liquid asphalt and introduction of Nano additives. In this work, silica fumes, fly ash and lime have been implemented with the aid of asphalt emulsion to improve the unconfined compressive strength of the collapsible soil. Specimens of 38 mm in diameter and 76 mm height have been prepared with various percentages of each type of Nano additive and fluid content. Specimens were subjected to unconfined compressive strength determination at dry a
... Show MoreNon-thermal argon plasma needle at atmospheric pressure was
constructed. The experimental setup was based on a simple and low
cost electric component that generates a sufficiently high electric
field at the electrodes to ionize the argon gas which flow at
atmospheric pressure. A high AC power supply was used with 1.1
kV and 19.57 kHz. Non-thermal Argon plasma used on blood
samples to show the ability of non-thermal plasma to promote blood
coagulation. Three tests have been done to show the ability of plasma
to coagulate both normal and anti-coagulant blood. Each blood
sample has been treated for varying time from 20sec. to 180sec. at
different distances. The results of the current study showed that the
co
Increasing the variety of products that are being designed with sculptured surfaces, efficient machining of these surfaces has become more important in many manufacturing industries. The objective of the present work is the investigation of milling parameters for the sculptured surfacesthat effecting of surface roughness during machining of Al-alloy. The machining operation implemented on C-TEK CNC milling machine. The influence of the selected variables on the chosen characteristics have been accomplished using Taguchi design approach, also ANOVA had been utilized to evaluate the contributionsof each parameter on proc
... Show More