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The Effect of Restriction Shape On Laminar Natural Convection Heat Transfer In A Vertical Circular Tube
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Natural convection heat transfer is experimentally investigated for laminar air flow in a vertical circular tube by using the boundary condition of constant wall heat flux in the ranges of (RaL) from (1.1*109) to (4.7*109). The experimental set-up was designed for determining the effect of different types of restrictions placed at entry of heated tube in bottom position, on the surface temperature distribution and on the local and average heat transfer coefficients. The apparatus was made with an electrically heated cylinder of a length (900mm) and diameter (30mm). The entry restrictions were included a circular tube of same diameter as the heated cylinder but with lengths of (60cm, 120cm), sharp-edge and bell-mouth. The surface temperature along the cylinder surface for same heat flux would be higher values for circular restriction with length of (120cm) and would be smaller values for bell-mouth restriction. The results show that the local Nusselt number (Nux) and average Nusselt numberare higher for bell-mouth restriction and smaller values for (120cm) restriction. For all entry shape restrictions, the results show that the Nusselt number values increases as the heat flux increases. From the present work an empirical correlations were obtained in a form of (Log) versus (Log) for each case investigated and obtained a general correlation for all cases which reveals the effect of restriction existence on the natural convection heat transfer process in a vertical circular tube.

 

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Publication Date
Tue Dec 22 2020
Journal Name
Journal Of Accounting And Financial Studies ( Jafs )
The effect of insider trading in accounting information on the investors decisions: An Applied Study In a sample of corporation listed in Iraq Securities Exchange
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This research aims to discuss an important issue because of its role in increasing the efficiency of financial markets and boost investor confidence by a insider trading, which arises as a result of leaking secret information to some investors and reliable in the process of trading shares in the Iraq Stock Exchange And thus obtain abnormal profits at the expense of other investors. Research was based on the assumption that " Where shortcomings in local regulations relating to disclosure and insider trading in accounting information leads to the activate the phenomenon of insider trading in accounting information in the Iraq Stock Exchange and including a negative impact on investors' decisions ". and Because of the difficulty the discove

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Publication Date
Fri Jan 01 2021
Journal Name
International Journal Of Thermal Sciences
Experimental and numerical investigations of heat transfer enhancement in shell and helically microtube heat exchanger using nanofluids
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Publication Date
Mon Dec 20 2021
Journal Name
Baghdad Science Journal
Temperature Stress on Physiological and Morphological Traits in Rhizophora apiculata
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Global warming has had considerable effects on vital ecosystems, which has also been caused by increased temperatures and CO2 that follow changes in different abiotic factors, which poses threats to mangrove forests environment. This research was conducted to examine the physiological and morphological characteristics of the Rhizophora apiculata mangrove regarding higher air temperature for the variety of tree species that respond to climate change. Seedlings were cultivated for three months in regulated growth chambers with three varying temperatures of 38°C, 21°C under CO2 at 450 ppm, and ambient CO2 concentration i.e., 450 ± 20 ppm under average temperature at 28°C as the control condition

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Publication Date
Thu Feb 01 2024
Journal Name
International Communications In Heat And Mass Transfer
A comparative study of twisted and straight fins in enhancing the melting and solidifying rates of PCM in horizontal double-tube heat exchangers
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Publication Date
Thu Oct 03 2024
Journal Name
Dentistry 3000
The Combined Effect of Two Natural Extracts on Enamel Remineralization (in vitro Study)
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Objective: Dental caries is a chronic infectious disease that is prevalent worldwide in all age groups. Numerous attempts have been made to develop conservative approaches to halt caries progression and restore enamel defects. This study aimed to investigate the effect of applying grape seed extract and chicken eggshell extract on the microhardness of demineralized enamel in permanent teeth. Methods: Forty-eight sound upper first premolars were used. Following demineralization with the demineralizing solution for 96 hours, they were distributed into four groups consistent with the treatment agent used: group A was treated with casein phosphopeptide amorphous calcium phosphate (as a control group), group B was treated with grape se

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Publication Date
Fri Feb 08 2019
Journal Name
Iraqi Journal Of Laser
Writing of a Bragg Grating on a D-shaped Optical Fiber Using the KrF Excimer Laser
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Fiber Bragg Grating has many advantages where it can be used as a temperature sensor, pressure sensor or even as a refractive index sensor. Designing each of this fiber Bragg grating sensors should include some requirements. Fiber Bragg grating refractive index sensor is a very important application. In order to increase the sensing ability of fiber Bragg gratings, many methods were followed. In our proposed work, the fiber Bragg grating was written in a D-shaped optical fiber by using a phase mask method with KrFexcimer. The resultant fiber Bragg grating has a high reflectivity 99.99% with a Bragg wavelength of 1551.2 nm as a best result obtained from a phase mask with a grating period of 1057 nm. In this work it was found that the rota

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Publication Date
Wed Sep 01 2010
Journal Name
Al-khwarizmi Engineering Journal
A Study of the Effect of Kaolin as a Fuel Oil Additive on the Corrosion Inhibition of Fireside Superheater Boiler Tubes
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The objective of the present study is to determine the effect of Kaolin as a fuel oil additive to minimize the fireside corrosion of superheater boiler tubes of ASTM designation (A213-T22) by increasing the melting point of the formed slag on the outside tubes surface, through the formation of new compounds with protective properties to the metal surface. The study included measuring corrosion rates at different temperatures with and without additive use with various periods of time, through crucible test method and weight loss technique.

      A mathematical model represents the relation between corrosion rate and the studied variables, is obtained using statistical regression analysis. Using this model,

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Publication Date
Sun Mar 20 2016
Journal Name
Al-academy
Mechanisms for Development of Scenography Galleries Iraq Natural History Museum: وعد عدنان محمود
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This paper deals with the problem of the mechanics of the operation of cinematography in the development of museum exhibition halls. In the first chapter, the researcher dealt with the problem and presented it to reach the goals and purpose of the research, which was represented in using and developing the methods and mechanisms of the presentation to keep pace with what is happening in the world of technology and access to the presented model to new formula and vision declares aesthetical and cognitive measure, thus the search constitutes an importance in absorbing Scenography dimensions in the theater and moved to the idea of the museum and the development of the display models and using them in drawing and representation of perception

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Publication Date
Sun Jul 09 2023
Journal Name
Journal Of Engineering
Study the Effect of Face Sheets Material on Strength of Sandwich Plates with Circular Hole
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This study aims to investigate the effect of changing skins material on the strength of sandwich plates with circular hole when subjected to mechanical loads. Theoretical, numerical and experimental analyses are done for sandwich plates with hole and with two face sheet materials. Theoretical analysis is performed by using sandwich plate theory which depends on the first order shear deformation theory for plates subjected to tension and bending separately. Finite element method was used to analyse numerically all cases by ANSYS program.

The sandwich plates were investigated experimentally under bending and buckling load separately. The relationship between stresses and the ratio of hole diameter to plate width (d/b) are built, by

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Publication Date
Mon Aug 01 2011
Journal Name
Journal Of Engineering
EFFECT OF STEEL FIBERS ADDITION ON THE BEHAVIOR OF HIGH STRENGTH CONCRETE CIRCULAR SHORT COLUMNS
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loaded reinforced concrete circular short columns. An experimental investigation into the behavior
of 24 short reinforced concrete columns with and without steel fibers was carried out. The columns
had a circular section (200 mm diameter and 900 mm long). Test variables include concrete
strength, spacing of spiral reinforcement, and inclusion of steel fibers. The axial stress and axial
strains were obtained and used to evaluate the effects of the presence of steel fibers. It was found
that the addition of steel fibers slightly improves the load carrying capacity of the tested columns
whereas it significantly enhances the ductility of these specimens. Test results also indicated that for
the same confinement parameter

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