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Numerical investigation on heat transfer enhancement and turbulent flow characteristics in a high aspect ratio rectangular duct roughened by intersecting ribs with inclined ribs
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In this study, the effect of intersecting ribs with inclined ribs on the heat transfer and flow characteristics of a high aspect ratio duct has been numerically investigated. The Relative roughness pitch (P/e) is 10 and the Reynolds number range from 35,700 to 72,800. ANSYS (Fluent-Workbench 18.0) software has been utilized to solve the Reynolds averaged Navier-Stokes (RANS) equations with the Standard k-ε turbulence model. Three ribbed models have been used in this study. Model 1 which is a just inclined ribs, Model 2 which has a single longitudinal rib at the center with inclined ribs and Model 3 which has two longitudinal ribs at the sides. The results showed that the heat transfer rate has been enhanced when the intersecting ribs are used. Model 3 has achieved the highest overall thermal performance. The increasing in Nusselt number ratio (Nu /Nus ) for Model 3 and 2, relative to Model 1, are 13.19% and 7.03%, respectively. Consequently, the hybridizing by intersecting ribs with inclined ribs is considered as an advantageous technique to enhance the heat transfer.

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Publication Date
Mon Jul 01 2013
Journal Name
International Journal Of Computer Applications
Mixed Convection in a Square Cavity Filled with Porous Medium with Heated Bottom Wall
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Two-dimensional unsteady mixed convection in a porous cavity with heated bottom wall is numerically studied in the present paper. The forced flow conditions are imposed by providing a hydrostatic pressure head at the inlet port that is located at the bottom of one of the vertical side walls and an open vent at the top of the other vertical side wall. The Darcy model is adopted to model the fluid flow in the porous medium and the combination effects of hydrostatic pressure head and the heat flux quantity parameters are carefully investigated. These governing parameters are varied over wide ranges and their effect on the heat transfer characteristics is studied in detail. It is found that the time required to reach a desired temperature at th

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Publication Date
Thu Feb 07 2019
Journal Name
Iraqi Journal Of Laser
Design High Efficient Reflectivity of Distributed Bragg Reflectors
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Bragg Reflectors consist of periodic dielectric layers having an optical path length of quarter wavelength for each layer giving them important properties and makes them suitable for optoelectronics applications. The reflectivity can be increased by increasing the number of layers of the mirror to get the required value. For example for an 8 layers Bragg mirror (two layers for each dielectric pair), the contrast of the refractive index has to be equal to 0.275 for reaching reflectivity > 99%. Doubling the number of layers results in a reflectivity of 99.99%. The high reflectivity is purely caused by multiple-interference effects. It can be analyzed by using different matrix methods such as the transfer matrix method (TMM) which is the

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Publication Date
Mon Jan 28 2019
Journal Name
Journal Of The College Of Education For Women
Preparation Scale father control when junior high students
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The family found itself confused any of the methods of dealing (Control - democracy) follow to reach the best level in education, what was favorite yesterday about a father dealing with his children control which showed generations characterized by high levels of self-esteem and decision-making, today rejected and opposed it. As some believe that a sense of control generates a negative represented by fear and frustration.
Find the goal of preparing the current scale of the father control when junior high students.
To achieve this goal, has been preparing a tool to measure the father control after that, the researcher extract the validity and reliability of the scale, and then applied to a sample of 500 students from junior high sch

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Publication Date
Fri Sep 03 2021
Journal Name
Entropy
Reliable Recurrence Algorithm for High-Order Krawtchouk Polynomials
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Krawtchouk polynomials (KPs) and their moments are promising techniques for applications of information theory, coding theory, and signal processing. This is due to the special capabilities of KPs in feature extraction and classification processes. The main challenge in existing KPs recurrence algorithms is that of numerical errors, which occur during the computation of the coefficients in large polynomial sizes, particularly when the KP parameter (p) values deviate away from 0.5 to 0 and 1. To this end, this paper proposes a new recurrence relation in order to compute the coefficients of KPs in high orders. In particular, this paper discusses the development of a new algorithm and presents a new mathematical model for computing the

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Publication Date
Thu Dec 20 2018
Journal Name
Advanced Electronic Materials
Scaling of High‐Performance Organic Permeable Base Transistors
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Organic permeable‐base transistors (OPBTs) show potential for high‐speed, flexible electronics. Scaling laws of OPBTs are discussed and it is shown that OPBT performance can be increased by reducing their effective device area. Comparing the performance of optimized OPBTs with state‐of‐the‐art organic field‐effect transistors (OFETs), it is shown that OPBTs have a higher potential for an increased transit frequency. Not only do OPBTs reach higher transconductance values without the need for sophisticated structuring techniques, but they are also less sensitive to parasitic contact resistances. With the help of a 2D numerical model, the reduced contact resistances of OPBTs are explained by a homogeneous injection of current acros

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Publication Date
Thu Dec 31 2020
Journal Name
College Of Islamic Sciences
Ministry of Education / Baghdad College High School - Adhamiya
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This research is based on the study of common praise in Mutanabbi and Ibn Hani Al-Andalusi as the main purpose in poetry poets, and balance between them;

  The research was divided into two topics, presented by introductory introduction for the purpose of praise, and the concept of budget in Arab criticism, and then presented a brief overview of the lives of poets.

  In the first section, I dealt with the common objectivity of the poets, such as the subject of sincerity in praise, hyperbole in the person of Mamdouh, and self-esteem when asked, in addition to the most common characteristics in t

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Publication Date
Sat Oct 31 2020
Journal Name
International Journal Of Integrated Engineering
Behavior of High Strength Hybrid Reinforcement Concrete Beams
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Six proposed simply supported high strength-steel fiber reinforced concrete (HS-SFRC) beams reinforced with FRP (fiber reinforced polymer) rebars were numerically tested by finite element method using ABAQUS software to investigate their behavior under the flexural failure. The beams were divided into two groups depending on their cross sectional shape. Group A consisted of four trapezoidal beams with dimensions of (height 200 mm, top width 250 mm, and bottom width 125 mm), while group B consisted of two rectangular beams with dimensions of (125 ×200) mm. All specimens have same total length of 1500 mm, and they were also considered to be made of same high strength concrete designed material with 1% volume fraction of steel fiber.

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Publication Date
Sat Sep 01 2012
Journal Name
Journal Of Economics And Administrative Sciences
Four antibiotics to prevent expansion corruption high fever
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The research aims to highlight on the reasons of financial & managerial corruption phenomena and to suggest systems & methods that promote controlling and developing the mechanism to combat corruption it also highlights on the ways that should available to enable the three regulatory agencies to reduce this phenomenon. The research depends on the following hypothesis "the governance of state institutions and the application of electronic government with depending on a correct mechanism to crossing auditing and the equilibrium performance model well help to reduce corruption phenomenon in Iraq" the two researchers have been concluded some conclusions the main one is that so many reasons of corruption starting from the bad

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Publication Date
Sun Jan 01 2023
Journal Name
Desalination And Water Treatment
Optimization of chemical oxygen demand removal from petroleum refinery wastewater by electrocoagulation using tubular electrochemical reactor with a novel design
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Publication Date
Wed Sep 14 2016
Journal Name
Journal Of Baghdad College Of Dentistry
Assessment of Alkaline Phosphatase, Salivary Flow Rate and Salivary Potential of Hydrogen in Relation to Severity of Chronic Periodontitis
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Background: The cells of periodontium contain many intracellular enzymes like (alkaline phosphatase ALP) that are released outside into the saliva and gingival crevicular fluid (GCF) after destruction of periodontal tissue. The aim of study was to determine the activity of this enzyme in saliva and its relation to the salivary flow rate, PH and clinical periodontal parameters in patients with chronic periodontitis. Subject, Materials and methods: Sample population consist of 75 individuals ;divided into four groups , the first group (15):control subject, the second group (20):mild chronic periodontitis, the third group(20) moderate chronic periodontitis and the fourth group (20) sever chronic periodontitis, Measurements of plaque index (PL

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