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Numerical Simulation of 3D- Flow Structure and Heat Transfer for Longitudinal Riblet Upstream of Leading Edge Endwall Junction of Nozzle Guide Vane
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The simulation have been made for  3D flow structure and heat  transfer with and without

longitudinal riblet upstream of leading edge vane endwall junction of first stage nozzle guide vane .The research explores concept of weakening the secondary flows and reducing their harmful effects.Numerical investigation involved examination of the secondary flows ,velocity and heat transfer rates by solving the governing equations (continuity, Navier -stokes and energy equations ) using the known package FLUENT version (12.1).The governing equations were solved for three dimentional, turbulent flowe, incompressible with an appropriate turbulent model (k-ω,SST) .The numerical solution was carried out for 25 models of V-groove riblet with wide ranges of height (h) and space (s). The results indicated that, the riblet endwall junction was a powerful tool for controlling the flow structure, reducing secondary flow formation,and elimination the effect of heat transfer at leading edg and passage . The drag reduction produced by riblet was proportional with their height and space. V-groove riblet with dimension of (h=1.35mm and s=2.26mm) was found to be the most effective in reduction of drag (2.7%) and heat transfer (21%) so it was selected as an optimum dimension of riblet model. The results also showed that the drag reduction produced by riblet was proportional to their size. The riblet model had a great effect in elimination spanwise ,pitchwise velocities ,but strength the streamwise velocity .At leading edge ,the effect of secondary flow was extended up to 23% from span height and 35% upstream leading edge .The riblet model caused an increase in momentom at a region very close to leading edge and to move stagnation point very close to the leading edge.

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Publication Date
Sun Jun 01 2014
Journal Name
Journal Of Water Resource And Hydraulic Engineering (jwrhe)
Large Scale Field Physical Model Simulation of Roseires Dam-Break, Sudan
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Physically based modeling approach has been widely developed in recent years for the simulation of dam failure process due to the lack of field data. This paper provides and describes a physically-based model depending on dimensional analysis and hydraulic simulation methods for estimating the maximum water level and the wave propagation time from breaching of field test dams. The field physical model has been constructed in Dabbah city to represent the collapse of the Roseires dam in Sudan. Five cases of a dam failure were studied to simulate water flood conditions by changing initial water height in the reservoir (0.8, 1.0, 1.2, 1.4 and 1.5 m respectively).The physical model working under five cases, case 5 had the greatest influence of t

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Publication Date
Sun Oct 01 2017
Journal Name
International Journal Of Science And Research (ij
Simulation of Chlorine Decay in Al-Gukook WaterDistribution Networks Using EPANET
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The approach of the research is to simulate residual chlorine decay through potable water distribution networks of Gukookcity. EPANET software was used for estimating and predicting chlorine concentration at different water network points . Data requiredas program inputs (pipe properties) were taken from the Baghdad Municipality, factors that affect residual chlorine concentrationincluding (pH ,Temperature, pressure ,flow rate) were measured .Twenty five samples were tested from November 2016 to July 2017.The residual chlorine values varied between ( 0.2-2mg/L) , and pH values varied between (7.6 -8.2) and the pressure was very weak inthis region. Statistical analyses were used to evaluated errors. The calculated concentrations by the calib

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Publication Date
Sun Aug 01 2021
Journal Name
International Journal Of Electrical And Computer Engineering (ijece)
Simulation based comparison of routing protocols in wireless multihop adhoc networks
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Routing protocols are responsible for providing reliable communication between the source and destination nodes. The performance of these protocols in the ad hoc network family is influenced by several factors such as mobility model, traffic load, transmission range, and the number of mobile nodes which represents a great issue. Several simulation studies have explored routing protocol with performance parameters, but few relate to various protocols concerning routing and Quality of Service (QoS) metrics. This paper presents a simulation-based comparison of proactive, reactive, and multipath routing protocols in mobile ad hoc networks (MANETs). Specifically, the performance of AODV, DSDV, and AOMDV protocols are evaluated and analyz

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Publication Date
Sat Dec 01 2012
Journal Name
Journal Of Engineering
Numerical and experimental investigation on the performance of the capillary tube using R-134a and R-600a
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In this paper, isobutane (R-600a) is used as a suitable substitute for (R-134a) when changing the length of capillary tube. And the experimental data on capillary tube are obtained under different conditions such as (subcooling and ambient temperatures) on domestic refrigerator (9ft3 size), this data shows that (R-600a) a suitable substitute for (R134a) .The test presented a model for a steady state, two-phase flow in capillary tube for vapour compression system .The numerical model depends on conservation equations (mass, energy and momentum) as wall as the equation of state for refrigerant. The solution methodology was implemented by using finite difference techniques. The system results indicate that it is possible to change the refri

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Publication Date
Sun Apr 15 2018
Journal Name
Strojniški Vestnik - Journal Of Mechanical Engineering
Comparative Experimental and Numerical Investigation on Electrical Discharge Drilling of AISI 304 using Circular and Elliptical Electrodes
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This work introduces a new electrode geometry for making holes with high aspect ratios on AISI 304 using an electrical discharge drilling (EDD) process. In addition to commercially available cylindrical hollow electrodes, an elliptical electrode geometry has been designed, manufactured, and implemented. The principal aim was to improve the removal of debris formed during the erosion process that adversely affects the aspect ratio, dimensional accuracy, and surface integrity. The results were compared and discussed to evaluate the effectiveness of electrode geometry on the machining performance of EDD process with respect to the material removal rate (MRR,) the electrode wear rate (EWR), and the tool wear ratio (TWR). Dimensional features an

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Publication Date
Wed Jan 01 2025
Journal Name
Ieee Access
Design and Comprehensive Study of a New Soft Electromagnetic Actuator: Mathematical Modeling, Numerical Analysis, and Experimental Evaluation
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Soft robotics offers a flexible alternative to rigid systems, enabling safe and adaptive interaction in biomedical, wearable, and unstructured environments. Among available actuation methods, soft electromagnetic actuators are notable for their fast response, low operating voltage, and ease of integration. However, some designs require pre-stretching mechanism, which produces an external force to maintain the separation between the coil and permanent magnets. Additionally, there is a mechanical complexity and difficulty in calibrating the spring parameters precisely. Furthermore, the pre-stretching mechanism increases the electromagnetic force required to counteract the opposing spring force, leading to a significant increase in power consu

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Publication Date
Tue Jun 01 2010
Journal Name
Al-khwarizmi Engineering Journal
Vibration Characteristics Oblate Shell "With and Without Framed Structure"
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This paper presents the results of investigating the vibrational characteristics of oblate dish with and without framed structure . A finite element method, was applied to the dynamic analysis of oblate spheroidal shell. Different types of elements were considered in one dimension and two dimensions. It was found that the natural frequencies of oblate shells had two types of behavior against increasing the shell thickness and eccentricity, which are the membrane mode and bending mode –Since – the membrane modes natural frequencies tend to increase with the increasing the eccentricity of oblate, while the bending modes natural frequencies decrease with the increasing the eccentricity till reach the optimum eccentricity.

 

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Publication Date
Thu Jan 21 2010
Journal Name
Iraqi Journal Of Veterinary Medicine
Production and Partial Purification of Heat-Stable Enterotoxin (A) Produced by Enterotoxigenic Escherichia coli
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A total of (25) stool samples were collected from children and adults (2- 4) years old suffering from diarrhea to isolate E. coli strains that produce heat-stable enterotoxin a (STa), and after performing microscopic examination, cultural characterization and biochemical identification only (11) isolates showed positive E. coli. STa activity was estimated by using suckling mouse assay (SMA) and from these (11) isolates only (5) showed STa activity and the one with the highest STa activity was selected for large scale production of STa, which was followed by partial purification using ion-exchange chromatography (normal phase) using DEAE sephadex A-50 column. After purification and determination of protein concentration by using the standard

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Publication Date
Sat Nov 09 2019
Journal Name
Biochem. Cell. Arch.
EFFECT OF HEAT EXPOSURE AND GINSENG EXTRACT ON BLOOD CELLS COUNT IN BROILER CHIKS
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The current study was conducted on 504(Ros-308) broiler chicks reared in Animal farms belong to College of Agriculture, University of Baghdad during the period 28/9/2017- 9/11/2018 to determine the effect of ginseng additive on the performance of chicks. Results of study showed a significant effect (p≤0.05) of exposure period an Red blood cells, 3.56×106ml3 of blood was in bird, which exposure to 2hr at heat shock. In 42 day at age 106 ×38 ml3 of blood can noticed in the blood at birds, which exposure to 2hr in 21-42 days at 3 days of age. No significant effect at ginseng on blood cells. The results showed a significant effect (p≤0.05) of interaction on red blood cells at 21 and 42 days of age and the average cells between these ages

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Publication Date
Mon Mar 08 2021
Journal Name
Baghdad Science Journal
The Effect of Heat Treatment on the Magnetic and Mechanical properties offe - Ni alloys.
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The aim of this work is studying the binary system ??'??? Ni?)with two ratios (y=36,80) by using casting method for preparing the samples.Magnetic and Mechanical properties have been studidt different httrea^nttem^rature.All the alloys were found a ferromagnetic behavior and sensitive to the heat treatment. Best properties were found at the heat treatment 1100 C°.A significant different results were found above 1100C° for lower magnetic and mechanical values. This is possibly due to the change on the degree of magnetic moment orders, in which most of the moments are started to remove from coupled ferromagnetically.?

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