A numerical investigation has been performed to study the effect of eccentricity on unsteady state, laminar aiding mixed convection in a horizontal concentric and eccentric cylindrical annulus. The outer cylinder was kept at a constant temperature
while the inner cylinder was heated with constant heat flux. The study involved numerical solution of transient momentum (Navier-Stokes) and energy equation using finite difference method (FDM), where the body fitted coordinate system (BFC) was
used to generate the grid mesh for computational plane. The governing equations were transformed to the vorticity-stream function formula as for momentum equations and to the temperature and stream function for energy equation.
A computer program (Fortran 90) was built to calculate the bulk Nusselt number (Nub) after reaching steady state condition for fluid Prandtl number fixed at 0.7 (air) with radius ratio ( =2.6), Rayleigh number (Ra=200), Reynolds number (Re=50) for both concentric and eccentric cylindrical annulus with different eccentricity ratios (ε=0, 0.25, 0.50, 0.75) and angular positions (φo=0o
, 45o , 90o , 135o , 180o ).
The results show a reasonable representation to the relation between Nusselt number and (ε, φo). Generally, Nub decreased with the increase in (ε and φo). Also, results show that the best thermal performance for the inner cylinder was at the angular
position (φo=0o ) for eccentricity ratio (ε=0.25), while the maximum reduction in the rate of heat transfer for the inner cylinder was at the angular position (φo=180o) for eccentricity ratio (ε=0.75).
Comparison of the result with the previous work shows a good agreement.
In this work a study was made in centrifugal fan blower to investigate the effect of impeller blade design on sound pressure level (SPL). Shroud and unshroud impeller of nine blades are used. The sound generation from flow inside the test rig at different positions was displayed by using spectral analyzer. The experiments were carried out in anechoic chamber with small holes in its walls, under ambient condition about (25-27) C ° to avoid the effect of temperature on the sound pressure level. The results showed that (SPL) decreased with the increase of distance from the source about (3-4)dB when distance varied about (0.8-1.06)m, and the (SPL) decreased with the decrease of velocity about (8-12)dB when velocity varied between (13000-260
... Show MoreThe logistic regression model regarded as the important regression Models ,where of the most interesting subjects in recent studies due to taking character more advanced in the process of statistical analysis .
The ordinary estimating methods is failed in dealing with data that consist of the presence of outlier values and hence on the absence of such that have undesirable effect on the result. &nbs
... Show MoreThe research problem consisted in answering the question that revolves around what is the impact of localizing employees’ salaries on bank deposits, and did it lead to an increase in their size? The research also aimed to nominate some initial solutions to improve the role of salary localization, in terms of reviewing the concept of electronic payment systems, its tools and channels, and then identifying the concept of salary localization, its importance, objectives and obstacles to its application, and then analyzing the reality of the state of localization of salaries and bank deposits to banks, the research sample for the period (2017- 2021), and the use of the statistical program (SPSS V25) to test the research hypotheses. The stud
... Show MoreThe researchers reached many conclusions, the most important of which was the distinction of practitioners of sports activity with high degrees in the trait (social). At the same time, it was low in the trait (aggression –restraint-desisting) and non-practitioners were distinguished by sports activity with high degrees in the trait (aggression –restraint-desisting). In contrast, the degree was low in the trait (social), and there were significant differences in favor of practitioners of the activity of the athlete, Through the conclusions, the researchers recommend the need for university students to practice sports activities because of their positive impact on their health in general and on the deve
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Objective : the aim of the study is to evaluate the effectiveness of nurse’s practices and knowledge program toward care of patient with cardiopulmonary bypass .Methodology: A pre-experimental design (one group pretest- posttest design) was used to carry out this study in three governmental hospitals in Baghdad ( Iraqi Centre for Heart Diseases , Ibn – Albitar Centre for Cardiac Surgery and Ibn – Alnafees Centre for Cardiothoracic and Vascular Surgery ) for the period from 15th of May 2022 into 20th of April 2023.The construction and development of the program and instruments had carry out by the researcher to measured the purposes of the study , twenty two nurses was purposively assigned for the study group . The
... Show MoreThe research seeks to examine the ability of fifth preparatory students in solving a mathematical problem in relation to system thinking. To this end, the researcher chose (140) fifth preparatory students from four-different secondary schools in Kirkuk city for the academic year (2016-2017). Two tests were adopted to collect study data: a test of (5) items about skills in solving math problem designed by (Al-raihan, 2006); and a test of system thinking skills designed by the researcher himself consisted of (14) items. It was divided into four skills (analyzing the main system to subsystems, eliminating all inner gaps of system, identifying the inner connection of system, and reorganizing the system). The findings indicated a good ability
... Show MoreThe research study and analysis of the integration of marketing communications and their impact on the marketing performance of a number of telecom companies, as included in the research problem to know the role of marketing communications community in achieving sales and market share, profitability and customer satisfaction. The importance of research begins to be the right choice for the elements of marketing communications, lead to savings in time, effort and money and create a more idea about the effectiveness of the application of the concept of integration. The research to determine the role of marketing communications in promoting the integration of the marketing performance of companies in the field of sales and marke
... Show MoreThe research included studying the effect of different plowing depths (10,20and30) cm and three angles of the disc harrows (18,20and25) when they were combined in one compound machine consisting of a triple plow and disc harrows tied within one structure. Draft force, fuel consumption, practical productivity, and resistance to soil penetration. The results indicated that the plowing depth and disc angle had a significant effect on all studied parameters. The results showed that when the plowing depth increased and the disc angle increased, leads to increased pull force ratio, fuel consumption, resistance to soil penetration, and reduce the machine practical productivity.
Microfluidic devices provide distinct benefits for developing effective drug assays and screening. The microfluidic platforms may provide a faster and less expensive alternative. Fluids are contained in devices with considerable micrometer-scale dimensions. Owing to this tight restriction, drug assay quantities are minute (milliliters to femtoliters). In this research, a microfluidic chip consisting of micro-channels carved on substrate materials built using an Acrylic (Polymethyl Methacrylate, PMMA) chip was designed using a Carbon Dioxide (CO2) laser machine. The CO2 parameters influence the chip’s width, depth, and roughness. To have a regular channel surface, and low roughness, the laser power (60 W), with scanning speed (250 m/s)
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