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.
The electronic structure of zinc blend indium gallium phosphide In0.5Ga0.5P nanocrystals which have dimension (2-2.8 nm) is investigated using the density functional theory coupled with large unit cell (LUC) for the different size core (8 ,16,54,64) atoms respectively. The investigated properties include total energy, energy gap, conduction band, valence band, cohesive energy, ionicity and density of state etc. as a function of core size and lattice constant. Results show the shape effect of increasing the core size and lattice constant on these electronic properties
A Mini-TEA CO2 laser system was designed and operated to obtain a pulse at 10.6 μm. Output energy of 30 mJ, with preionization pins, and pulse duration of 100ns were obtained. While an output energy of 6mJ and pulse duration of 100 ns in absence of pre-ionization were obtained. The system was operated with Ernest profile main-discharge electrodes. Dependencies of supply voltage and output laser energy on the pressure inside laser cavity were investigated as well as dependencies of supply voltage and output energy on the main capacitor(8CO2 : 8N2 : 82He :2CO). Efficiency of was calculated to be 4.4%.
The Feedback Concept has been spread as an organized trend for scientific research since it has a significant importance for human behavior and how it has been directed and controlled by the individual, feedback has numerous definitions but the simplest definition is; feedback is the information received by the individual from the output of his behavior, In addition to the mutual relationship between the individual and the stimulation that provide him with the basic information by the biological control of his behavior, Since feedback cannot be accomplished without receiving information from the inner and outer environment, the biological and physiological information become the ma
... Show MoreFaintly continuous (FC) functions, entitled faintly S-continuous and faintly δS-continuous functions have been introduced and investigated via a -open and -open sets. Several characterizations and properties of faintly S-continuous and faintly -Continuous functions were obtained. In addition, relationships between faintly s- Continuous and faintly S-continuous function and other forms of FC function were investigated. Also, it is shown that every faintly S-continuous is weakly S-continuous. The Convers is shown to be satisfied only if the co-domain of the function is almost regular.
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Background: Pervasive Developmental Disorder (PDD) is a term refers to the overarching group of conditions to which autism spectrum disorder (ASD) belongs .
Objective: This study was designed to determine the existing behavior of children with autism in dental sitting, the behavior improvements in recall dental visits and evaluate the improvement in oral hygiene with using specific visual pedagogy chart.
Type of the study: Cross-sectional study.
Methods: Forty children of both genders, ages ranged from 4 – 6 years having primary teeth only were selected whose medical history included a diagnosis
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The current study aims to find out:
- The ingratiating behavior of university students.
- The differences of statistical significance in The ingratiating behavior among university students according to the variables of sex and specialization
The current study is determined by University of Baghdad students of both genders (males and females) and for both majors (scientific and humanities) for the academic year (2019-2020).
In order to achieve the researcher's objectives:Ingratiating behavior scale has been constructed. It consists in its final form of (32) items divided into four behaviors. The researcher has extracted scale validity and reliability.
The researcher based the two scales
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The printed circuit heat exchanger is a plate type heat exchanger with a high performance and compact size. Heat exchangers such as this need a unique form of bonding and other techniques to be used in their construction. In this study, the process of joining plates, diffusion bonding, was performed and studied. A special furnace was manufactured for bonding purposes. The bonding process of copper metal was carried out under specific conditions of a high temperature up to 700 oC, high pressure of 3.45 MPa, and in an inert environment (Argon gas) to make tensile samples. The tensile samples are cylindrical shapes containing groves representing the flow channels in the printed circuit heat exchanger and checking their tensile st
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The present study is concerned with the concept of ethics academically. It aims to investigate the major problems that contemporary Iraqi society suffers from; on top of which is the problem of sectarian and religious intolerance. Such a problem has a major role in the emergence of extremism and terrorism. It further destabilizes the security and stability of the country, exposing, as a result, the lives of citizens to the danger of genocide, disintegrating the social structure, stopping the wheel of development, rampant corruption, and deteriorating the political, social, moral and economic situation. Here comes the role of social work as governmental institutions and civil society organizations in curbing this reprehensible phenomenon
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Agent technology has a widespread usage in most of computerized systems. In this paper agent technology has been applied to monitor wear test for an aluminium silicon alloy which is used in automotive parts and gears of light loads. In addition to wear test monitoring، porosity effect on
wear resistance has been investigated. To get a controlled amount of porosity, the specimens have
been made by powder metallurgy process with various pressures (100, 200 and 600) MPa. The aim of
this investigation is a proactive step to avoid the failure occurrence by the porosity.
A dry wear tests have been achieved by subjecting three reciprocated loads (1000, 1500 and 2000)g
for three periods (10, 45 and 90)min. The weight difference a