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 %.
In the presence of deep submicron noise, providing reliable and energy‐efficient network on‐chip operation is becoming a challenging objective. In this study, the authors propose a hybrid automatic repeat request (HARQ)‐based coding scheme that simultaneously reduces the crosstalk induced bus delay and provides multi‐bit error protection while achieving high‐energy savings. This is achieved by calculating two‐dimensional parities and duplicating all the bits, which provide single error correction and six errors detection. The error correction reduces the performance degradation caused by retransmissions, which when combined with voltage swing reduction, due to its high error detection, high‐energy savings are achieved. The res
... Show MoreEach sport has its own energy requirements that differ from the energy requirements of other sports, and a different method is used in each of them, so the trainer must first rely on the principle of privacy in training first, that is, privacy according to the working energy system, that is, he defines the controlling energy system In that event, and how the muscles use the available energy to perform according to the energy production systems. As we find the serving skill is the first volleyball skill with which the team starts the match in order to be able to gain points directly, through knowledge it turns out that there is a weakness in the skill performance, especially the skill of serving and being The key to victory for volle
... Show MoreBackground: Polycystic ovary syndrome (PCOS) is one of the most frequent endocrine illnesses affecting reproductive - age women. L-carnitine has important roles in oxidative stress, energy production and glucose metabolism. It affects insulin resistance as decreased plasma carnitine level has been well reported in type II diabetes mellitus. Hence, it means L-carnitine may reduce insulin resistance which is found in PCO disease. Objective: This study aims to measure the level of L-carnitine and insulin resistance in both obese and non- obese patients with PCOS. Patients and Methods: Sixty women within the reproductive age with PCOS (30 obese and 30 non- obese) were recruited from the Gynecology and Obstetrics Outpatient Clinic in Baghdad T
... Show MoreThis paper investigated the treatment of textile wastewater polluted with aniline blue (AB) by electrocoagulation process using stainless steel mesh electrodes with a horizontal arrangement. The experimental design involved the application of the response surface methodology (RSM) to find the mathematical model, by adjusting the current density (4-20 mA/cm2), distance between electrodes (0.5-3 cm), salt concentration (50-600 mg/l), initial dye concentration (50-250 mg/l), pH value (2-12 ) and experimental time (5-20 min). The results showed that time is the most important parameter affecting the performance of the electrocoagulation system. Maximum removal efficiency (96 %) was obtained at a current density of 20 mA/cm2, distance be
... Show MoreType-1 diabetes is defined as destruction of pancreatic beta cell, virus and bacteria are some environmental factor for this disease. The study included 25 patients with type-1 diabetes mellitus aged between 8 – 25 years from Baghdad hospital and 20 healthy persons as control group. Anti-rubella IgG and IgM, anti-Chlamydia pneumonia IgG and IgM were measured by ELISA technique while anti-CMV antibody were measured by immunofluorescence technique. The aim of current study was to know the trigger factor for type-1 diabetes. There were significant differences (P<0.05) between studied groups according to parameters and the results lead to suggest that Chlamydia pneumonia, CMV and rubella virus may trigger type-1 diabetes mellitus in Iraqi pat
... Show MoreCoronavirus disease 2019 (COVID-19) is a flu-like infection caused by a novel virus known as Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2). After the widespread around the world, it was announced by the World Health Organization (WHO) as a global pandemic. The symptoms of COVID-19 may arise within 2 weeks and the severity ranged from mild with signs of respiratory infection to severe cases of organ failure and even death. Management of COVID-19 patients includes supportive treatment and pharmacological medications expected to be effective with no definitive cure of the disease. The aims of this study are highlighting the management protocol and supportive therapy especially vitamin D and manifesting the clinical symptoms b
... Show MoreBackground: Temporomandibular joint disorders refer to a group of heterogeneous pain and dysfunction conditions involving the masticatory system, reducing life quality of the sufferers. Arthrocentesis is simple and less invasive surgical procedure for the treatment of internal derangement than arthroscopy and better than other conservative procedures such as drugs, occlusal appliances and physiotherapy. The aim of the study was to evaluate the effect of arthrocentesis with injection of hyaluronic acid in the treatment of internal derangement of temporomandibular joint for the restoration of its function, reducing pain and preventing further deterioration of the temporomandibular joint dysfunction. Materials and methods: This study was perfo
... Show MoreRecently on the dermatological fields, the serum levels and the roles of Zn, Cu and Mg have been studied especially in acne vulgaris, but the results were controversial. The aim of the present study is to investigate a relationship between the severity of acne and the serum levels of zinc (Zn), copper (Cu) and magnesium (Mg) and to demonstrate the status of serum levels of zinc, copper, and magnesium in Iraqi male patients with acne vulgaris and to compare it with those of healthy controls.This case controlled study was conducted in the Department of Dermatology and Venerology and in the Poisoning Consultation Center of Baghdad Teaching Hospital between May 2009 to January 2010. Forty- five male patients with acne vulgaris, their a
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