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Investigation of phase change characteristics for refrigerant R-134a flow in a double pipe heat exchanger with the use of thermal non-equilibrium model
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Almost all thermal systems utilize some type of heat exchanger. In a lot of cases, evaporators are important for systems like organic Rankine cycle systems. Evaporators give a share in a large portion of the capital cost, and their cost is significantly attached to their size or transfer area. Open-cell metal foams with high porosity are taken into consideration to enhance thermal performance without increase the size of heat exchangers. Numerous researchers have tried to find a representation of the temperature distribution closer to reality due to the different properties between the liquid and solid phases. Evaporation heat transfer in an annular pipe of double pipe heat exchanger (DPHEX) filled with cooper foam is investigated numerically with utilizing the local thermal non-equilibrium (LTNE) model. Warm water with constant inlet conditions flows in the inner pipe while R143a is used as cooling fluid in the annular pipe. The effects of pores per inch (PPI), mass flux of R134a and copper foam porosity on solid and fluid temperatures, liquid saturation and heat transfer coefficient are analysed and illustrated. Forchheimer-extended Darcy flow model is utilized with the adopting of the two-phase mixture model (TPMM). The governing equations in two-dimensional steady state regime were written in LTNE model. These equations were discretized using the finite volume method and a MATLAB program was built to solve these equations with its initial and boundary conditions. The obtained data illustrates that LTNE effect in metal foam is important for lower porosity, lower pore density and higher mass flux. The ratio of liquid will arrive its lowest value at the outlet, and it decreases with PPI increase and it increases with porosity and mass flux increase. The mean heat transfer coefficient approximately doubled when PPI increased from 10 to 50 and it increased by 70% when porosity decreased from 0.95 to 0.85.

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Publication Date
Sun Jun 12 2011
Journal Name
Baghdad Science Journal
Hybrid(Luminescent and Fresnel ) Concentrators to Improve Solar Panel Conversion Efficiency
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The spectral response of the Si solar cell does not coincidence with the sun irradiance spectrum, so the efficiency of the Si solar cell is not high. To improve the Si solar cell one try to make use of most region of the sun spectrum by using dyes which absorb un useful wavelengths and radiate at useful region of spectrum (by stock shift). Fluorescence's dye is used as luminescent concentrator to increase the efficiency of the solar cell. The results show that the performance efficiency and out power for crystalline silicon solar cells are improved.

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Publication Date
Sun Jul 01 2012
Journal Name
Journal Of Educational And Psychological Researches
Arabic Calligraphy quality standards and teaching methods
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Arabic calligraphy is one of the ancient arts rooted in history, And that he grew up conflicting views and writings addressed as a, communication tool for the linguistic The teaching calligraphy note an art and science because it depends on the fixed assets and precise rules in his art because centered Beauty It targets teach Arabic calligraphy speed as the education and recitation helps to write fast Which have great interest in the field of education and in life both Also accompanied Arabic calligraphy and scientific renaissance significant knowledge in the Ara

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Publication Date
Sat Apr 13 2024
Journal Name
مجلة واسط للعلوم الریاضیة
تمرينات تنافسية لتطوير التوافق والتوازن وتأثيرها في مهارة التصويب السلمي للاعبات كرة السلة دون (18) سنة
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Shooting skill in basketball is one of the most important offensive skills and the final stage of the team's attack and the culmination of all skills in which points are scored, including the skill of peaceful shooting. The research aims to prepare competitive exercises and understand the impact of competitive exercises on developing coordination and balance for basketball players under 18 years old. The researcher used the experimental method with the single experimental group approach, including the research community of female athletes in the public directorates of education in Baghdad, totaling (6) directorates and (72) players. The research sample was selected intentionally, consisting of female athletes in the sports activity of the D

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Publication Date
Sun Jun 12 2011
Journal Name
Baghdad Science Journal
Parabola Dish and Cassegrain Concentrators to Improve Solar Cell Conversion Efficiency
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New designs of solar using ray tracing program, have been presented for improved the performance and the out put power of the silicon solar cell, as well as reducing the cost of system working by solar energy. Two dimensional solar concentrator (Fresnel lenses) and three dimensional concentrators (parabola dish and cassegrain) were used as concentrator for photovoltaic applications (CPV). The results show that the performance efficiency and out power for crystalline silicon solar cells are improved.

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Publication Date
Thu Jul 21 2022
Journal Name
Neuro Quantology
Astronomical Observation between Diffraction Limited Coherent and Incoherent Imaging Systems
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Numerical simulations are carried out to evaluate the coherence concept’s effect on the performance regarding the optical system, when observing and imaging the planet’s surface. In numerous optical approaches, the coherence qualities of light sources play an important role. This paper provides an overview about the mathematical formulation of temporal and spatial coherence and incoherence properties of light sources. The circular aperture was used to describe the optical system like a telescope. The simulation results show that diffraction-limited for incoherent imaging system certainly improves the image. Yet, the quality of the image is degraded by the light source's highly spatial and temporal coherence properties, resulting in a

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Publication Date
Thu Jul 16 2020
Journal Name
مجلة حمورابي
انعكاسات تطور القوة المعلوماتية الامريكية في البيئة الداخلية
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The global globalization the world is experiencing has enabled international actors—states, international governmental and non-governmental organizations, such as liberation movements, international social movements, and even terrorist organizations—to use cyber power to achieve their goals. Therefore, this study discusses the impact of information power on the domestic environment of the United States.

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Publication Date
Tue Jul 11 2023
Journal Name
Journal Of Educational And Psychological Researches
Psychological stability and its relationship to Integration University and spiritual intelligence among University students
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The current research aimed to identify psychological stability and its relationship to university integration and spiritual intelligence among university students. The research sample consisted of (158) students from the College of Education - Al-Mustansiriya University.

A scale was applied: psychological stability, university integration, and spiritual intelligence,   and by using the (Pearson) correlation coefficient, and the t-test, the results showed: the sample members enjoy psychological stability, university integration, and spiritual intelligence, and there is a positive, statistically significant correlation between the research variables, and the results resulted in some recommendations and proposals.

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Publication Date
Sun Jan 01 2023
Journal Name
International Conference Of Computational Methods In Sciences And Engineering Iccmse 2021
Fibrewise totally topological spaces
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Publication Date
Fri Jan 31 2025
Journal Name
Joiv : International Journal On Informatics Visualization
RC5 Performance Enhancement Based on Parallel Computing
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This study aims to enhance the RC5 algorithm to improve encryption and decryption speeds in devices with limited power and memory resources. These resource-constrained applications, which range in size from wearables and smart cards to microscopic sensors, frequently function in settings where traditional cryptographic techniques because of their high computational overhead and memory requirements are impracticable. The Enhanced RC5 (ERC5) algorithm integrates the PKCS#7 padding method to effectively adapt to various data sizes. Empirical investigation reveals significant improvements in encryption speed with ERC5, ranging from 50.90% to 64.18% for audio files and 46.97% to 56.84% for image files, depending on file size. A substanti

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Publication Date
Tue Feb 01 2022
Journal Name
Baghdad Science Journal
Securing Text Messages Using Graph Theory and Steganography
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      Data security is an important component of data communication and transmission systems. Its main role is to keep sensitive information safe and integrated from the sender to the receiver. The proposed system aims to secure text messages through two security principles encryption and steganography. The system produced a novel method for encryption using graph theory properties; it formed a graph from a password to generate an encryption key as a weight matrix of that graph and invested the Least Significant Bit (LSB) method for hiding the encrypted message in a colored image within a green component. Practical experiments of (perceptibility, capacity, and robustness) were calculated using similarity measures like PSNR, MSE, and

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