A numerical study of the two-dimensional steady free convection flow in an inclined annulus between two concentric square cavities filled with a porous medium is presented in this paper for the case when the side outer walls are kept with differentially heated temperature while the horizontal outer walls and the inner walls are insulated. The heated wall is assumed to have spatial sinusoidal temperature variation about a constant mean value. The Darcy model is used and the fluid is assumed to be a standard Boussinesq fluid. For the Cartesian coordinate system, the governing equations which were used in stream function form are discretized by using the finite difference method with successive under – relaxation method (SUR) and are solved by Gauss-Siedel iterative method. The upwind scheme was used for the transport terms in the energy conservation equation. The results are presented to demonstrate the streamlines, the isotherms, and the Nusselt number depending on the Rayleigh number ranging from (Ra =10 to 1000), dimension ratio from (Dr = 0.15 to 0.45), and the inclination angle from (= 0o to 45o). Also the effects of the amplitude (=0 to 1) and the wave number (f =0 to 5) of the heated side wall temperature variation on the free convection are investigated. The results show the effect of previous parameters (Ra, Dr,, , and f) on the flow fields and temperature profiles. It also show that the average Nusselt number is a strong function of the Rayleigh number, inclination angle, dimension ratio, and temperature variation. The peak value of the average Nusselt number based on the hot wall temperature is observed to occur at dimension ratio of (0.15), inclination angle of (40.1°), amplitude and wave number (1 & 0.75) for Rayleigh number of (1000).
A vital instrument to foster the long-term goal of high-quality education has developed in the form of digital technologies. The educational system has been found to be significantly impacted by these technologies. The recent COVID- Pandemic has strengthened the legitimacy of using digital tools in education. The entire educational system has undergone a paradigm shift as a result of these digital technologies. Along with sharing knowledge, it also serves as a mentor, an assessor, and a co-creator of information. Students' lives have been simpler as a result of educational technology advancements. Nowadays, students prepare presentations and projects utilizing a variety of software and tools rather than pen and paper. The weig
... Show MoreThese years Qatar has emerged as an important regional destination of foreign direct investment (FDI), which demonstrates the recent success of several smaller economies in attracting FDI. This paper aims to investigate the causal relationships between inward FDI and economic growth in the particular case of Qatar featured as oil production country. Vector Autoregressive (VAR) Impulse Responses and Granger Causality Tests were adopted as major research methods. Annual data set was used covering from 1990 to 2010. The main results demonstrated the bi-directional causality and long-run relationships between FDI inflows and economic growth in Qatar. And to attract FDI inflows into Qatar, the government shall continue its efforts in const
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Abstract Background Infections with helminths are associated with deficient sanitary facilities, unsafe human waste disposal, inadequate and lack of safe drinking water, and low socioeconomic status. Objective To determine the prevalence of some gastrointestinal helminths among Iraqi people, and association of infections with age, sex, and region in Iraq. Method This study is retrospective, including reported cases of infections using an available surveillance database from January 2013 to December 2013 of all provinces of Iraq by the Ministry of Health. Result The overall prevalence of gastrointestinal helminthiasis was 1.39%. Enterobius vermicularis found to be the predominant helminth parasite. No significant (P < 0.05) rel
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study was conducted on a stretch of Tigris river crossing Baghdad city to determine the concentration of some chlorophenols pollutants. Aqueous samples were preliminary enriched about 500 times and the chlorophenols have determined using high performance liquid chromatography HPLC. Limits of detection LOD were (0.007–0.012 mg L-1), relative standard deviations RSD% were 2.4%–5.59% and relative recoveries were 51.06%– 104.07%. The existence of chlorophenols in Tigris river was in the range 0.023–4.596 mg L-1. The developed method suggested in this study can be applied for routine analysis and monitoring of chlorinated phenols in environmental aqueous samples.
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The corrosion behavior of copper and carbon steel in 1M concentration of hydrochloric acid (HCl) and sulphuric acid (H2SO4) has been studied. The corrosion inhibition of copper and carbon steel in 1M concentration of hydrochloric acid (HCl) and sulphuric acid (H2SO4) by Ciprofloxacin has been investigated. Specimens were exposed in the acidic media for 7 hours and corrosion rates evaluated by using the weight loss method. The effect of temperature (from 283 ºK to 333 ºK), pH (from 1to 6), inhibitor concentration (10-4 to 10-2) has been studied. It was observed that sulphuric acid environment was most corrosive to the metals because of its oxidizing nature, followed by hydrochloric acid. The rate of metal dissolution increased with incre
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Hepatitis, an inflammation of the liver, has a number of infectious and non-infectious causes. Two of the viruses that cause hepatitis (hepatitis A and E) can be transmitted through water and food; hygiene is therefore important in their control. First, to assess the importance of HAV and HEV as a possible diagnosis for clinically diagnosed patients with acute viral hepatitis. Second, to assess the prevalence of hepatitis A and E in all provinces of Iraq and study its association with age, gender. This study consisted of two groups: The first group consisted of 2975 patients with a clinical diagnosis of acute viral hepatitis. The second group consisted of a total of 9610 persons, which were recruited by surveying a nationally representative
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