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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
Mon Nov 11 2024
Journal Name
Jurnal Teknologi (sciences & Engineering)
THE EXTERNAL DRAFT TUBE GASLIFT BIOREACTOR: HYDRODYNAMIC CHARACTERISTICS AND PARAMETRIC OPTIMIZATION
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Gaslift reactors are employed in several bioapplications due to their characteristics of cost-effectiveness and high efficiency. However, the nutrient and thermal gradient is one of the obstacles that stand in the way of its widespread use in biological applications. The diagnosis, analysis, and tracking of fluid paths in external draft tube gaslift bioreactor-type are the main topics of the current study. Several parameters were considered to assess the mixing efficiency such as downcomer-to-rizer diameter ratio (Ded/Dr), the position of the diffuser to the height of bioreactor ratio (Pd/Lr), and gas bubble size (Db). The multiple regression of liquid velocity indicates the optimal setting: Ded/Dr is (0.5), Pd/Lr is (0.02), and Db

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Publication Date
Mon Nov 11 2024
Journal Name
Jurnal Teknologi (sciences & Engineering)
THE EXTERNAL DRAFT TUBE GASLIFT BIOREACTOR: HYDRODYNAMIC CHARACTERISTICS AND PARAMETRIC OPTIMIZATION
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Gaslift reactors are employed in several bioapplications due to their characteristics of cost-effectiveness and high efficiency. However, the nutrient and thermal gradient is one of the obstacles that stand in the way of its widespread use in biological applications. The diagnosis, analysis, and tracking of fluid paths in external draft tube gaslift bioreactor-type are the main topics of the current study. Several parameters were considered to assess the mixing efficiency such as downcomer-to-rizer diameter ratio (Ded/Dr), the position of the diffuser to the height of bioreactor ratio (Pd/Lr), and gas bubble size (Db). The multiple regression of liquid velocity indicates the optimal setting: Ded/Dr is (0.5), Pd/Lr is (0.02), and Db

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Publication Date
Sat Jan 24 2026
Journal Name
Journal Of Economics And Administrative Sciences
The effect of creating knowledge according to the model (Nonaka & Takeuchi, 1995) on organizational ambidexterity: A study on a sample of Iraqi private banks
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Purpose - This study relies on the descriptive and analytical approach through collecting and analyzing the necessary data, as this approach focuses on polling the opinions of the research sample and its directions, and aims to develop a model that studies the relationship between knowledge creation and organizational ambidexterity in Iraqi private banks and verifying its validity experimentally. Design / Methodology / Introduction - A survey was conducted through a questionnaire form to collect data from a sample of (113) managers in private commercial banks. In addition, this study used the AMOS program and the ready-to-use statistical program package (SPSS V.25) to test the proposed hypotheses of the theoretical model experimentally. Res

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Publication Date
Sat Jan 24 2026
Journal Name
Al–bahith Al–a'alami
The role of Iraqi newspapers in instilling political culture among the public after 2003, a field study on the audience of the city of Baghdad
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The role of Iraqi newspapers in instilling political culture among the public after 2003, a field study on the audience of the city of Baghdad, University of Baghdad, College of Information, Department of Journalism, 2019,
The problem of research is to investigate the role of Iraqi newspapers in instilling the political culture of individuals after 2003, and monitor this role Through the contents and messages provided by the Iraqi newspapers to the public. the research is classified within descriptive research, it adopts the survey methodology and used the questionnaire tool. In fact, the questionnaire was distributed to a sample of 400 individuals that was selected according to the method of multi-stage cluster sample of those who re

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Publication Date
Sat Jan 01 2011
Journal Name
Iraqi Journal Of Physics
Natural radioactivity survey in Al-Jabal Al-Gharbi Mountain Region Libya
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The measurement of natural radioactivity in a given region or country is essential to provide a reference base-line map to follow up a possible variation in future. In order to perform such measurement, the natural radioactivity was measured in different locations. The locations (50 sites) were distributed over Al-Jabal Al-Gharbi Mountain, starting from the city Al-Azeeziah in the eastern part to Wazen on the Tunisian border in the west. The measurements showed obvious variation from one site to another. The levels were fluctuating from (12.8 counts/minute) in Bir-Ayad to (45.7 counts/minute) in Gherian.
In order to investigate the cause for such variation, samples were collected from (27) sites for detailed study. The levels of natur

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Publication Date
Sun Apr 01 2018
Journal Name
Journal Of Educational And Psychological Researches
EMDR impact on a sample of Displaced persons
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Abstract [email protected] Background: Acute Traumatic Stress Disorder (ATSD) might be complicated by Post Traumatic Stress Disorder (PTSD). Psychological First Aid (PFA) said to be helpful to reduce the possibility of reduction of ASD and PTSD symptoms. PFA is simple procedure to deliver help & support to victims, may be by some one close to him, quietly and professionally. Iraq has and is still experiencing, continuous traumatic stresses. ATSD is especially seen in war such as during the Gulf War, Embargo and nowadays under the current American occupation. With the extreme shortage of recourses and the given late priority to psychological problems and intervention have disastrous consequences on the psycho-social wellbeing of peop

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Publication Date
Sat Oct 28 2023
Journal Name
Baghdad Science Journal
Effect of Green-biosynthesis Aluminum Nanoparticles (Al NPs) on Salmonella enterica Isolated from Baghdad City
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This study is aimed to Green-synthesize and characterize Al NPs from Clove (Syzygium aromaticum
L.) buds plant extract and to investigate their effect on isolated and characterized Salmonella enterica growth.
S. aromaticum buds aqueous extract was prepared from local market clove, then mixed with Aluminum nitrate
Al(NO3)3. 9 H2O, 99.9% in ¼ ratio for green-synthesizing of Al NPs. Color change was a primary confirmation
of Al NPs biosynthesis. The biosynthesized nanoparticles were identified and characterized by AFM, SEM,
EDX and UV–Visible spectrophotometer. AFM data recorded 122nm particles size and the surface roughness
RMs) of the pure S. aromaticum buds aqueous extract recorded 17.5nm particles s

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Publication Date
Sun Aug 30 2020
Journal Name
Journal Of Economics And Administrative Sciences
Effect of leadership patterns on the phenomenon of jop burnout among employees at Baghdad College of Economic Sciences University
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This study deals with the impact of leadership styles in its three main dimensions (democratic, autocratic, lenient) as an independent variable of the dimensions of functional combustion (emotional stress, inhumanity, personal achievement). The research sought to achieve a set of goals, the most prominent of which are: studying the reality of the researched organization to identify the leadership patterns used in its management and its impact on the phenomenon of functional combustion, Moreover, knowing the extent of support for these established patterns and their contribution to mitigating the phenomenon of functional combustion in the organization's environment, and testing the impact of these leadership patte

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Crossref
Publication Date
Wed Dec 30 2009
Journal Name
Iraqi Journal Of Physics
Study the Effect of annealing temperature on the Structure of a-Se and Electrical Properties of a-Se/c-Si Heterojunction
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In this work Study effect of annealing temperature on the Structure
of a-Se and electrical properties of a-Se/c-Si hetrojunction have been
studied.The hetrojunction fabricated by deposition of a-Se film on c-
Si using thermal evaporation.
Electrical properties of a-Se/ c-Si heterojunction include I-V
characteristics, in dark at different annealing temperature and C-V
characteristics are considered in the present work.
C-V characteristics suggested that the fabricated diode was
abrupt type, built in potential determined by extrapolation from
1/C2-V curve. The built - in potential (Vbi) for the Se/ Si System
was found to be increase from 1.21 to 1.62eV with increasing of
annealing temperature

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Publication Date
Tue Dec 29 2020
Journal Name
Journal Of Accounting And Financial Studies ( Jafs )
The role of the external auditor in assessing the security of information technology systems in light of (ISO/IEC 27001): (Applied research on a sample of private banks)
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This research aims to shed light on the necessity of establishing an information security management system through which banking security risks are managed in the light of the ISO (IEC 27001) standard, through which bank departments seek to demonstrate the management of their security systems and their controls in accordance with the specifications of the standard to obtain an internationally recognized security certificate And the need for senior management in banks to an independent person with scientific and practical qualification and who has accredited certificates in the field of information technology for the purpose of helping them to verify the level of compatibility between the policies and procedures applied and the p

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