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joe-2070
Evaluation of Convective Heat Transfer and Natural Circulation in an Evacuated Tube Solar Collector
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The evacuated tube solar collector ETC is studied intensively and extensively by experimental and
theoretical works, in order to investigate its performance and enhancement of heat transfer, for Baghdad climate
from April 2011 till the end of March 2012. Experimental work is carried out on a well instrumented collector
consists of 16 evacuated tubes of aspect ratio 38.6 and thermally insulated tank of volume 112L. The relation
between convective heat transfer and natural circulation inside the tube is estimated, collector efficiency, effect of
tube tilt angles, incidence angle modifier, The solar heating system is investigated under different loads pattern (i.e
closed and open flow) to evaluate the heat loss coefficient from tank and tubes, test the collector with various
aspect ratios (32.9 and 27.2). The enhancement in collector performance is studied by using two reflectors (Flat
Plate and Curved Plate) and nanofluid (Water-AL2O3).Theoretical work is run by software (Fluent 6.3), to compute
the velocity and temperature profiles within the tube, for different tube diameters, effect of tube junction angle and
stagnant region in the bottom of the evacuated tube. The experimental results shows that the heat loss coefficient
for tube is W/m2.K and for tank is W/m2.K, the maximum collector temperature is 79°C in winter and
99°C in summer, while that belong to nanofluid collector is 99°C in winter. The best tilted angle (optimum) of
evacuated tube is 41° annually. The collector efficiency increased when using nanofluid of (1, 0.6, 0.3)% volume
fraction as(28.4, 6.8, 0.6)% respectively. The efficiency decreases as (33, 62)% when decreasing tube aspect ratio
from 38.6% to 32.9% and 27.2% respectively. An increase of (16.9 and 7.08)% in collector efficiency is obtained
when using curved and flat plate reflectors respectively. From simulation the best junction angle of the tank is
22.5°. The stagnant region is influenced with changing heat flux, tilted angle and aspect ratio.

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Publication Date
Tue Oct 01 2024
Journal Name
Journal Of Physics: Conference Series
A comparative Analytical Investigation of Different Geomagnetic Storms During Solar Cycles 23 and 24
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Abstract<p>In this work, the geomagnetic storms that occurred during solar cycles 23 and 24 were classified based on the value of the Disturbance Storm Time index (Dst), which was considered an indicator of the strength of geomagnetic conditions. The special criterion of Dst >-50 nT was adopted in the classification process of the geomagnetic storms based on the minimum daily value of the Dst-index. The number of geomagnetic storms that occurred during the study period was counted according to the adopted criteria, including moderate storms with (Dst >-50 nT), strong storms with (Dst >-100 nT), severe storms with (Dst >-200 nT), and great storms with (Dst >-350 nT). The statistica</p> ... Show More
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Publication Date
Sun Oct 01 2023
Journal Name
Journal Of Ovonic Research
Composite nanostructured growth of (CdS)0.75 (PbS)0.25/Si solar cell and its characterization
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By using vacuum evaporation, thin films of the (CdS)0.75-(PbS)0.25 alloy have been deposited to form a nanocrystalline composite. Investigations were made into the morphology, electrical, optical and I-V characteristics of (CdS)0.75-(PbS)0.25 films asdeposited and after annealing at various temperatures. According to AFM measurements, the values of grain sizes rise as annealing temperatures rise, showing that the films' crystallinity has been increased through heat treatment. In addition, heat treatment results in an increase in surface roughness values, suggesting rougher films that could be employed in more applications. The prepared films have direct energy band gaps, and these band gaps increase with the increase in the degrees

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Publication Date
Thu Apr 01 2021
Journal Name
Iop Conference Series: Earth And Environmental Science
Effect of Metals ( Au, Ag, and Ni) as Cathode Electrode on Perovskite Solar Cells
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Abstract<p>Gold, silver and nickel used as electrodes in the fabrication of perovskite solar cell by using thermal evaporation deposition method with direct structure FTO\ TiO<sub>2</sub>\ MAPbI<sub>3</sub>\ spiro-MeOTAD\ metal electrode. The cell efficiency was compared between the electrodes material as a function of time to explaining the effect of these metals electrode on cell performance, X-ray diffraction pattern showed that the samples that contain gold and nickel do not contain a compound indicating the interaction of the metal with the components of the cell or the formation of a new compound, while in the cell containing silver it was found that silver iodide is fo</p> ... Show More
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Publication Date
Fri Sep 15 2023
Journal Name
Journal Of Baghdad College Of Dentistry
Evaluation of alpha amylase and peroxidase in saliva of pregnant women
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Background: Pregnancy is a natural physiological state that involves several biochemical modifications. Saliva is consisted of many types of proteins such as salivary alpha amylase and salivary peroxidase that might be affected by pregnancy. The former enzyme is considered one of the most prevalent proteins that is released by highly differentiated epithelial acinar cells and has been shown to have enzymatic activities while the latter has been approved that it  has a significant role in oral health. The purpose of this study was to the evaluate the salivary levels of alpha-amylase and peroxidase in pregnant and non-pregnant women. Materials and Methods: Sixty pregnant women were grouped according to the pregnancy trimesters. The first

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Publication Date
Tue Aug 05 2014
Journal Name
International Journal Of Pharmacy And Pharmaceutical Sciences
FORMULATION AND EVALUATION OF FLOATING ORAL IN-SITU GEL OF METRONIDAZOLE
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Publication Date
Sun Jan 13 2019
Journal Name
Iraqi Journal Of Physics
Investigation of the Natural Occurring Radioactive Material (NORM) in the cyprinus carpio fishes breeding in artificial lakes of Baghdad governorate
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The steady consumption of fish led many researchers to study it preferences over other foods, especially for radioactivity content. The specific activity concentration (S.A) of natural occurring radioactive materials (NORM) have been measured for Cyprinus carpio fishes collected from several industrial fishes' lakes located in Baghdad governorate using gamma spectroscopy doped with high purity germanium coaxial detector (HPGe). Thirteen fishes' samples were collected from industrial lakes, three samples were collected from cages, and two samples were collected from Trigger River. The last two types of samples were collected in order to compare the results with it. The measured overall averages of S.A for Ra-226, Th-232, and K-40 were 58.

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Publication Date
Mon Feb 04 2019
Journal Name
Iraqi Journal Of Physics
Rapid thermal oxidation of copper nanostructure thin film for solar cell fabrication
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In the present work is the deposition of copper oxide using the pulsed laser deposition technique using Reactive Pulsed Laser as a Deposition technique (RPLD), 1.064μm, 7 nsec Q-switch Nd-YAG laser with 400 mJ/cm2 laser energy’s has been used to ablated high purity cupper target and deposited on the porous silicon substrates recorded and study the effect of rapid thermal annealing on the structural characteristics, morphological, electrical characteristics and properties of the solar cell. Results of AFM likelihood of improved absorption, thereby reducing the reflection compared with crystalline silicon surface. The results showed the characteristics of the solar cell and a clear improvement in the efficiency of the solar cell in the

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Publication Date
Fri Jan 01 2021
Journal Name
Journal Of Mechanical Engineering Research And Developments
Numerical investigation for Natural Convection in a square Enclosure with partially active thermal sides' wall
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Three-dimensional cavity was investigated numerical in the current study filled with porous medium from a saturated fluid. The problem configuration consists of two insulated bottom and right wall and left vertical wall maintained at constant temperatures at variable locations, using two discretized heaters. The porous cavity fluid motion was represented by the momentum equation generalized model. The present investigation thermophysical parameters included the local thermal equilibrium condition. The isotherms and streamlines was used to examine energy transport and momentum. The meaning of changing parameters on the established average Nusselt number, temperature and velocity distribution are highlighted and discussed.

Scopus
Publication Date
Fri Jan 01 2021
Journal Name
دراسات قانونية
The Legal Nature of the Build-Operate- transfer-Ownership Contract (B.O.T.)
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The legal nature of the Build-Operate-Transfer-Ownership Contract (B.O.T) The Build, Operate, and Transfer of Ownership Contract (BOT) has emerged as the most successful and safest method for involving the private sector in public sector services. The major infrastructure projects that are built through the BOT contract are no longer financed by the state and its budget, but the private sector has played a major role in financing These projects, especially developing countries that need to establish infrastructure or modernize their existing infrastructure, especially in the areas of transport, communications, services, electricity, water ..... and other public utilities.

Publication Date
Wed Aug 19 2020
Journal Name
Revista De Chimie
Synthesis, Characterization and Biological Evaluation of Cr(III), Fe(III), Co(II), Ni(II), Zn(II) and Cd(II) Complexes Using an Azo Dye as Ligand
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Azo ligand 11-(4-methoxyphenyl azo)-6-oxo-5,6-dihydro-benzo[4,5] imidazo[1,2-c] quinazoline-9-carboixylic acid was derived from 4-methoxyaniline and 6-oxo-5,6-dihydro-benzo[4,5]imidazo[1,2-c]quinazoline-9-carboxylic acid. The presence of azo dye was identified by elemental analysis and spectroscopic methods (FT-IR and UV-Vis). The compounds formed have been identified by using atomic absorption in flame, FT.IR, UV-Vis spectrometry magnetic susceptibility and conductivity. In order to evaluate the antibacterial efficiency of ligand and its complexes used in this study three species of bacteria were also examined. Ligand and its complexes showed good bacterial efficiencies. From the obtained data, an octahedral geometry was proposed for all p

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