Theoretical and experimental investigations have been carried out on developing laminar
combined free and forced convection heat transfer in a vertical concentric annulus with uniformly
heated outer cylinder (constant heat flux) and adiabatic inner cylinder for both aiding and opposing
flows. The theoretical investigation involved a mathematical modeling and numerical solution for
two dimensional, symmetric, simultaneously developing laminar air flows was achieved. The
governing equations of motion (continuity, momentum and energy) are solved by using implicit
finite difference method and the Gauss elimination technique. The theoretical work covers heat flux
range from (200 to 1500) W/m2, Re range from 400 to 2000 and (1.36×105 ≤ Ra ≤ 1.1×107) with
radius ratio of 0.555 which is the same radius ratio used in the experimental part of this study and
Pr=0.7. The experimental work includes construct a rig consists essentially of an annulus with
uniformly heated outer cylinder and adiabatic inner cylinder to give clear insight into heat transfer
process and compare its results with that obtained in theoretical part, the range of the study are
(Re= 383, 724, 1000, 1500) and heat flux equal to (q =370, 422, 588, 980) W/m2. Numerical results
were represented by the temperature profile, axial velocity profile, outer surface temperature and
the distribution of local Nusselt number along the dimensionless axial distance. The velocity and
temperature profile results have revealed that the secondary flow created by natural convection have
significant effects on the heat transfer process. Results reveal also that the experimental local
Nusselt number along the annulus follows the same trend as present theoretical results with mean
difference 10.23 %.
Abstract
The research aims to measure family negligence and its relationship with internet addiction among university students. The researcher has developed a scale of (20) items to measure the negligence of family, which was applied to (308) male and female university students in the first and fourth stages. The research concluded that University students suffer from family negligence. The research sample has an addiction to the Internet. There is a relationship between family neglect and addiction to the Internet among university students. The researcher came out with a number of suggestions and recommendations.
Calcifying epithelial odontogenic tumour (CEOT) is a benign odontogenic neoplasm of epithelial origin that secretes an amyloid‐like protein tending towards calcification. This study aims to describe a case series from Iraq of one of the rarest odontogenic tumours.
Clinical and histopathological analysis of Calcifying epithelial odontogenic tumour cases that are archived at the oral pathology laboratory of the college of dentistry (Baghdad University) from 2000 to 2019.
Six cases of CEOT were regi
To achieve the objectives of the study, a non –probability (purposive) sample of (50) nurses were selected those were working at the oncology wards at the above listed hospitals. The data selected according to the criteria of the study sample. The validity of the questionnaire was determined through an expert panel consists of (11) specialist expert and its reliability was determined through a pilot study by test – retest which was estimated as averages (R=0.89). Data was collected by direct interview technique using the questionnaire formal and data was analyzed by application of descriptive & inferential statistical methods (frequency, percentage, mean of score and Chi-Square). The resul
... Show MoreThe imbalances and economic problems which it face the countries, it is a result of international economic developments or changes or global crises such as deterioration in trade, sharp changes in oil prices, increasing global indebtedness, sharp changes in foreign exchange rates and other changes, all that, they affect the economic features of any country. and These influences vary from one country to another according to the rigidity of its economy and its potential in maneuvering with economic plans and actions that would reduce the impact or avoidance with minimal damage. Therefore, the countries that suffer from accumulated economic problems as a result of mismanagement and poor planning or suffe
... Show MoreBackground: ;Hepatitis C virus (HCV) is a major cause of chronic liver disease. Approximately 85% of patients acutely infected with HCV progress to chronic liver disease with persistence of HCV-RNA for more than 6 months Among patients with chronic HCV infection , 15-20% progress to end-stage liver disease main transmission methods of the virus is by : blood and blood products ; sharing needles and acupuncture .Objective: To evaluate Iraqi patients infected with chronic HCV, including their treatment, and factors that affect their response to treatment .Methods :This study was performed at Gastroenterology and Hepatology hospital in Baghdad from January 2011 to March 2012.The study enrolled 90 patients with HCV Antibody positive (Ab +ve)
... Show MoreWireless Multimedia Sensor Networks (WMSNs) are networks of wirelessly interconnected sensor nodes equipped with multimedia devices, such as cameras and microphones. Thus a WMSN will have the capability to transmit multimedia data, such as video and audio streams, still images, and scalar data from the environment. Most applications of WMSNs require the delivery of multimedia information with a certain level of Quality of Service (QoS). This is a challenging task because multimedia applications typically produce huge volumes of data requiring high transmission rates and extensive processing; the high data transmission rate of WMSNs usually leads to congestion, which in turn reduces the Quality of Service (QoS) of multimedia applications. To
... Show MoreBackground: The aim of this national oral health survey was to determine the prevalence of malocclusions due to some anomalies in the dentition among the 13 years old Kurdish students in sulaimani intermediate school. Materials and methods: The total sample was 950 (455 males and 495 females) which assessed by diagnostic set and special instrument. The clinical examination was mainly based on the definitions of Björk et al. Some variables were recorded as present or absent sometimes denoting the tooth or the teeth involved in malocclusion and their distribution according to the whole sample. Results: The results showed that 1)The most common extracted tooth was the mandibular first molar (2.9%). 2) At this age group the most common partial
... Show MoreABSTRACTBackground: dyslipidemia plays a crucial rule in the development of cardiovascular disease, which has become the leading cause of death in most developed countries as well as in developing countries (1). The effects of reducing low density lipoprotein – C (LDL-C) concentrations on the prevention of cardiovascular events and stroke have been well reported in many clinical trials.Objectives: Evidence supports the use of statins for lipid modifications in the primary prevention of coronary artery disease, morbidity and mortality. This study aims to determine the effectiveness of atorvastatin in treating dyslipidemia in Iraqi obese patients.Methods: 200 overweight and obese patients with hypercholesterolemia, according to NCEP ATP
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