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Effect of receiver geometry on the optical and thermal performance of a parabolic trough collector
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Abstract<p>In this study, the optical and thermal performance of a Parabolic Trough Collector PTC system is investigated theoretically. A series of numerical simulations and theoretical analysis has been conducted to investigate the effect of the receiver geometry and location relative to the focal line on its optical performance. The examined receiver geometries are circular, square, triangular, elliptical and a new design of circular‐ square named as channel receiver. The thermal performance of PTC is studied for different flow rates from (0.27 to 0.6 lpm) theoretically. Results showed that the best optical design is the channel receiver with an optical efficiency of 84% while the worst is the elliptical receiver with an optical efficiency of 70%. Thermally the best design is the elliptical receiver with a thermal efficiency of 85% while the worst is the circular receiver with a thermal efficiency of 82%.</p>
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Publication Date
Sat Dec 01 2012
Journal Name
Journal Of Economics And Administrative Sciences
The use of two indicators of market value-added and return on capital invested in measuring the performance of the Iraqi banking sector
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For a long time, the intensification of profit represented a major goal for the company management ,but this goal confirmed a series of restrictions such the constriction on short period, the time rather than on long and medium strategic goal, the relationships with customers ,the supplies, employees , This goal is replaced by another one (intensification of the company's value) ,and the fortune of the share holders itself ,for the purpose  of creating value, the company must generate  great outcomes to cover the operating expense and to insure the a suitable compensation to the invested capital (the market value added) is  the indication used to estimate the company ability to create value –added the development

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Publication Date
Fri Dec 22 2023
Journal Name
Eastern-european Journal Of Enterprise Technologies
Evaluating the impact of structure parameters on the acoustic performance of an exhaust muffler with shells
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Recently, environmental noise has arisen from various sources, such as those from exhaust mufflers of combustion engines found in cars, trucks, or power generators, which produce significant noise during their operation. Controlling the radiated noise from these mufflers is a major factor in improving acoustic comfort and minimizing the impact on the surrounding communities. Numerous research has been presented for this reason by modification of the internal structure of the exhaust muffler. The main objective of this work is to reduce the noise level emitted from exhaust mufflers. This can be achieved by adjusting structure parameters to attenuate the surrounding environment's radiated noise. Analysis of pressure-wave propagation h

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Publication Date
Sat Jul 01 2023
Journal Name
Journal Of Accounting And Financial Studies ( Jafs )
The impact of the practice of professional doubt on the quality of the auditor's performance in Iraq: بحث استطلاعي
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              Due to the increasing interest in the quality of auditing by writers, researchers and regulators of the auditing profession. The matter necessitated a statement of the extent to which the auditor practices professional skepticism, because of its significant impact in discovering errors and material misrepresentations contained in the financial statements in order to give the financial community confidence in them and the success of the audit process. The research aims to clarify the concept and importance of the practice of professional skepticism and its effect on the quality of the auditor's performance in Iraq. To achieve the research objectives, the two re

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Publication Date
Fri Sep 15 2023
Journal Name
Journal Of Optics
Studying of the structural and optical properties of titanium dioxide nanoparticles prepared by chemical method
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Publication Date
Sat Jan 01 2022
Journal Name
International Journal Of Hydrogen Energy
Optimisation of operating parameters on the performance characteristics of a free piston engine linear generator fuelled by CNG–H2 blends using the response surface methodology (RSM)
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The free piston engine linear generator (FPELG) is a simple engine structure with few components, making it a promising power generation system. However, because the engine works without a crankshaft, the handling of the piston motion control (PMC) is the main challenge influencing the stability and performance of FPELGs. In this article, the optimal operating parameters of FPELG for maximising engine performance and reducing exhaust gas emissions were studied. Moreover, the influence of adding hydrogen (H2) to compressed natural gas (CNG) fuel on FPELG performance was investigated. The influence of operating parameters on in-cylinder pressure was also analysed. The single-piston FPELG fuelled by CNG blended with H2 was used to run the expe

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Publication Date
Wed Jan 17 2018
Journal Name
Journal Of Engineering And Applied Sciences
PREPARATION, CHARACTERIZATION AND THERMAL ANALYSIS OF POLYMERIC BLEND NANOCOMPOSITES BASED ON PVA-PVPPEGDOPED WITH ZINC OXIDE NANOPARTICLES
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Publication Date
Mon Dec 31 2012
Journal Name
Al-khwarizmi Engineering Journal
The Effect of Doppler Phenomenon on the Speed of Blood Flow
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This research studying the phenomenon of Doppler (frequency Doppler) as a method through which the direction and speed of the blood cells flows in blood vessels wear measured. This Doppler frequency is relied upon in medicine for measuring the speed of blood flow, because the blood flow is an important concept from the concepts of medicine. It represents the function and efficient of the heart and blood vessels in the body so any defect in this function will appear as a change in the speed of blood flow from the normal value assumed. As this speed changes alot in cases of  disease and morbidity  of the heart, so in order to identify the effect of changing the Doppler frequency on the speed of blood flow and the relationship of

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Publication Date
Mon Jun 01 2015
Journal Name
Int. J. Adv. Appl. Math. Andmech.
The effect of external source of disease on the epidemic model
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Publication Date
Sun Mar 30 2008
Journal Name
Iraqi Journal Of Chemical And Petroleum Engineering
Effect of Promoters on the Catalytic Activity of the Iosmerization Catalyst
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The crystalline zeolite, namely faujasite type Y with SiO2/Al2O3 mole ratio of 5 was used as raw material for preparation of isomerization catalysts. A 0.5 wt % Pt/HY-zeolite catalyst was prepared by impregnation of the decationized HY-zeolite with chloroplatinic acid. The dectionized HY-zeolite was treated with HCl, HNO3 and HI promoters using different normalities and with different concentrations of Sn, Ni and Ti promoters by impregnation method to obtain acidic and metallic promoters' catalysts, respectively. A 0.5 wt% of Pt was added to above catalysts using impregnation method. Isomerization of n-hexane was carried out at different prepared catalysts. The isomerization temperature varied from 250–325° C over weight hourly space

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Publication Date
Mon Oct 12 2026
Journal Name
Baghdad Science Journal
Study the effect of position on the time of astronomical twilight
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Twilight is that light appear on the horizon before sunrise and after sunset, Astronomically it is known that sunrise and sunset are effected by high above sea level, but the effect of high above sea level on the time of astronomical twilight still not decided and controversy among astronomers, in This research we studies the effect of high above sea level on the time of astronomical twilight, through adding the equation correct high above sea level to equation computation of twilight and then calculate of changing in the time of twilight for different highest (0-10000) meters above sea level , and the ratio of increase for time with high between (15.45-20.5) minutes. It was found that there was an increase in the time of the twilight along

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