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An Analytical Solution for the Maximum Tensile Stress and Stress Concentration Factor Investigations for Standard, Asymmetric fillets, Asymmetric Pressure Angle and Profile Shifted Helical and Spur Gears

This research introduces a developed analytical method to determine the nominal and maximum tensile stress and investigate the stress concentration factor. The required tooth fillets parametric equations and gears dimensions have been reformulated to take into account the asymmetric fillets radiuses, asymmetric pressure angle, and profile shifting non-standard modifications. An analytical technique has been developed for the determination of tooth weakest section location for standard, asymmetric fillet radiuses, asymmetric pressure angle and profile shifted involute helical and spur gears. Moreover, an analytical equation to evaluate gear tooth-loading angle at any radial distance on the involute profile of spur and helical gears, (taking into account the effect of profile shift factor) has been derived. In addition, numerical solution for the evaluation of the maximum fillet tensile stress and the combined tensile stress concentration factor for the verification of the analytical method using computer-aided engineering software (ANSYS Version 18.1). The analytical and FE result have been compared and found to be very close. The most effective method for reducing the stress concentration factor have been found by applying negative profile shifting on asymmetric tooth with lower unloaded pressure angle and high loaded pressure angle and fillet radius, which can lead to an enhancement percentage of (20%) when using a (35o/20o) asymmetric spur gear of a (24) teeth number with a shift factor of (-0.3mo) compared with standard (20o) one.

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Publication Date
Wed Jan 01 2014
Journal Name
Advances In Mechanical Engineering
Experimental and Numerical Investigations of Heat Transfer Characteristics for Impinging Swirl Flow

This paper reports experimental and computational fluid dynamics (CFD) modelling studies to investigate the effect of the swirl intensity on the heat transfer characteristics of conventional and swirl impingement air jets at a constant nozzle-to-plate distance ( L = 2 D). The experiments were performed using classical twisted tape inserts in a nozzle jet with three twist ratios ( y = 2.93, 3.91, and 4.89) and Reynolds numbers that varied from 4000 to 16000. The results indicate that the radial uniformity of Nusselt number (Nu) of swirl impingement air jets (SIJ) depended on the values of the swirl intensity and the air Reynolds number. The results also revealed that the SIJ that was fitted with an insert of y = 4.89, which correspo

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Publication Date
Mon Jun 19 2023
Journal Name
Journal Of Engineering
EXPERIMENTAL AND THEORETICAL INVESTIGATIONS FOR BEHAVIOR OF PRECAST CONCRETE GIRDERS WITH CONNECTIONS

This research presents experimental and theoretical investigation of 15 reinforced concrete spliced and nonspliced girder models. Splices of hooked dowels and cast in place joints, with or without strengthening steel plates were used. Post-tensioning had been used to enhance the splice strength for some spliced girders. The ANSYS computer program was used for analyzing the spliced and non-spliced girders. A nonlinear three dimensional element was used to represent all test girders. The experimental results have shown that for a single span girder using steel plate connectors in the splice zone has given a sufficient continuity to resist flexural stresses in this region. The experimental results have shown that the deflection of hooked do

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Publication Date
Thu Dec 30 2021
Journal Name
Iraqi Journal Of Science
Gompertz Fréchet stress-strength Reliability Estimation

In this paper, the reliability of the stress-strength model is derived for probability P(Y<X) of a component having its strength X exposed to one independent stress Y, when X and Y are following Gompertz Fréchet distribution with unknown shape parameters and known parameters . Different methods were used to estimate reliability R and Gompertz Fréchet distribution parameters, which are maximum likelihood, least square, weighted least square, regression, and ranked set sampling. Also, a comparison of these estimators was made by a simulation study based on mean square error (MSE) criteria. The comparison confirms that the performance of the maximum likelihood estimator is better than that of the other estimators.

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Publication Date
Mon Jan 01 2024
Journal Name
Ieee Access
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Publication Date
Fri Jan 01 2021
Journal Name
Journal Of Economics And Administrative Sciences
Comparison Between Maximum Likelihood and Bayesian Methods For Estimating The Gamma Regression With Practical Application

In this paper, we will illustrate a gamma regression model assuming that the dependent variable (Y) is a gamma distribution and that it's mean ( ) is related through a linear predictor with link function which is identity link function g(μ) = μ. It also contains the shape parameter which is not constant and depends on the linear predictor and with link function which is the log link and we will estimate the parameters of gamma regression by using two estimation methods which are The Maximum Likelihood and the Bayesian and a comparison between these methods by using the standard comparison of average squares of error (MSE), where the two methods were applied to real da

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Publication Date
Sun Sep 29 2019
Journal Name
Iraqi Journal Of Science
Association Between Systemic and Local Oxidative Stress of Infertile Women Undergoing Ivf/Icsi

     Oxidative stress (OS) may affect in vitro fertilization (IVF) outcomes in infertile women undergoing in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI). The aim of this study is to explore the possible relationships between OS parameters in serum and follicular fluid (FF) from infertile women with male cause infertility (n=40), women with polycystic ovary syndrome (PCOS) (n=40), and women with unexplained infertility (UI)(n=45) undergoing IVF/ICSI. The collection of blood and FF samples was done at the day of oocyte aspiration. Total peroxide (TPX) level, total antioxidant capacity (TAC), and malondialdehyde (MDA) level were measured in serum and FF; whereas, glutathione-s-transf

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Publication Date
Wed Aug 16 2017
Journal Name
Ibn Al-haitham Journal For Pure And Applied Sciences
Serum Oxidative Stress and Creatine Kinase Activity Related to Hoffman's Syndrome

Several symptoms of hypothyroidism characterized by low

FT3 and FT4 were classified into hypothyroidism and Hoffman's syndrome .It was accepted that free radical generation and lipid peroxidation are associated with  many diseases. Creatine kinase in serum is affected by thyroid hormones. This study was undertaken to investigate the relationship between  malondialdehyde  as a general lipid peroxidation marker and CK activity in patients with primary hypothyroidism and Hoffman's syndrome which indicatees hypothyroidism with undetectable FT3 and FT4 in serum with elevated values of  TSH.

The study revealed that MDA is within the normal range, while CK activities in sera of Hoffman's syndrome were increas

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Publication Date
Sat Jul 31 2021
Journal Name
Iraqi Journal Of Science
Effects of Caper (Capparis Spinosa) and Acetic Acid on Lipid Profile and Protein Concentration in the Serum of Albino Mice

     This study aimed to determine the effects of alcoholic and aqueous extracts of caper (Capparis Spinosa) and acetic acid on serum lipid profile and proteins levels in mice.  Sixty adult mice with an average weight of 24±4 g grams were divided into four groups (15 mice for each). The first group (G1) was administrated daily with an oral dose of caper alcoholic extract (200 mg/kg) for 28 days. The second group (G2) was administrated daily with an oral dose of caper aqueous extract (200 mg/kg) for 28 days. The third group (G3) was administrated with a daily dose of 10 % acetic acid  (2 ml/kg) for 28 days. The fourth Group (G4) was administrated daily with distilled water for 28 days, as a control

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Publication Date
Sun Apr 02 2006
Journal Name
Journal Of The Faculty Of Medicine Baghdad
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Publication Date
Wed Jul 31 2024
Journal Name
Iraqi Geological Journal
Correlating Capillary Pressure and Resistivity Index for Carbonate Reservoir

Capillary pressure is a significant parameter in characterizing and modeling petroleum reservoirs. However, costly laboratory measurements may not be sufficiently available in some cases. The problem amplifies for carbonate reservoirs because relatively enormous capillary pressure curves are required for reservoir study due to heterogeneity. In this work, the laboratory measurements of capillary pressure and formation resistivity index were correlated as both parameters are functions of saturation. Forty-one core samples from an Iraqi carbonate reservoir were used to develop the correlation according to the hydraulic flow units concept. Flow zone indicator (FZI) and Pore Geometry and Structure (PGS) approaches were used to identify

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