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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
Tue Jan 02 2018
Journal Name
Journal Of Educational And Psychological Researches
Family violence, its causes and effects on society (women and children)
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Summary of the research Family violence, its causes and effects on society (women and children). Search Goal: The current research aims to identify: 1. Causes of family and social violence (for children and women). 2. How to process. research importance : Domestic violence is a major and devastating problem that has a negative and direct impact on children in particular and women or mothers in general. The problem of domestic violence is linked to many factors and individual, social, economic, psychological and environmental variables, which makes one theory that claims to be inaccurate. It is difficult to understand the nature of family violence without linking it to some of the concepts related to it. The negative effects that may lead

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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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Publication Date
Mon Feb 04 2019
Journal Name
Iraqi Journal Of Physics
Temperatture esttiimattiion off EXDRA and SSUMI dwarff Nova systtems from spectroscopic data
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The seasonal behavior of the light curve for selected star SS UMI and EXDRA during outburst cycle is studied. This behavior describes maximum temperature of outburst in dwarf nova. The raw data has been mathematically modeled by fitting Gaussian function based on the full width of the half maximum and the maximum value of the Gaussian. The results of this modeling describe the value of temperature of the dwarf novae star system leading to identify the type of elements that each dwarf nova consisted of.

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Publication Date
Mon Jan 02 2017
Journal Name
Journal Of Educational And Psychological Researches
Frustration degree and guilt among drug addicts harmful to themselves
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This study aimed to identify the degree of frustration and guilt among addicts who hurt themselves with drug,  and to know the addicts perspective  who are in treatment clinics and rehabilitation centers  in Palestine, in order to achieve this goal aDeterminationThe study population has been identified , this study population consisted of ' (82) addict, the researcher used the descriptive analytical method which is appropriate for  this  study, so the researcher questioned the addicts who are in treatment clinics and rehabilitation centers  in Palestine and analyze their  responses  in light of some of the variables.

The study results showed that drug addicts who ar

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Publication Date
Mon Oct 10 2016
Journal Name
Iraqi Journal Of Science
Satellite image classification using KL-transformation and modified vector quantization
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In this work, satellite images classification for Al Chabaish marshes and the area surrounding district in (Dhi Qar) province for years 1990,2000 and 2015 using two software programming (MATLAB 7.11 and ERDAS imagine 2014) is presented. Proposed supervised classification method (Modified Vector Quantization) using MATLAB software and supervised classification method (Maximum likelihood Classifier) using ERDAS imagine have been used, in order to get most accurate results and compare these methods. The changes that taken place in year 2000 comparing with 1990 and in year 2015 comparing with 2000 are calculated. The results from classification indicated that water and vegetation are decreased, while barren land, alluvial soil and shallow water

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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 Jan 02 2018
Journal Name
Journal Of Educational And Psychological Researches
Self-organized learning strategies and self-competence among talented students
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Investigating the strength and the relationship between the Self-organized learning strategies and self-competence among talented students was the aim of this study. To do this, the researcher employed the correlation descriptive approach, whereby a sample of (120) male and female student were selected from various Iraqi cities for the academic year 2015-2016.  the researcher setup two scales based on the previous studies: one to measure  the Self-organized learning strategies which consist of (47) item and the other to measure the self-competence that composed of (50) item. Both of these scales were applied on the targeted sample to collect the required data

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Publication Date
Thu Dec 31 2015
Journal Name
Al-khwarizmi Engineering Journal
Hexapod Robot Static Stability Enhancement using Genetic Algorithm
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Abstract

Hexapod robot is a flexible mechanical robot with six legs. It has the ability to walk over terrain. The hexapod robot look likes the insect so it has the same gaits. These gaits are tripod, wave and ripple gaits. Hexapod robot needs to stay statically stable at all the times during each gait in order not to fall with three or more legs continuously contacts with the ground. The safety static stability walking is called (the stability margin). In this paper, the forward and inverse kinematics are derived for each hexapod’s leg in order to simulate the hexapod robot model walking using MATLAB R2010a for all gaits and the geometry in order to derive the equations of the sub-constraint workspaces for each

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Publication Date
Fri Dec 30 2022
Journal Name
College Of Islamic Sciences
جدلية جدليّة العقل والنّقل وعلاقتهما بالاستدلال مسائل الاعتقاد بين مدرستي أهل الحديث والأشاعرة: - عرض ومناقشة
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This research highlights one of the most important issues that have been controversial between Islamic schools, which is the duality of Intellect  and Revelation and the nature of their relationship, in two core points:

The first point: Could there be a real conflict between Intellect  and revelation? While the school of hadith view that this assumption is a rational assumption that does not real as long as the revelation is correct and the Intellect  is clear, and that what is claimed are due to other Intellect s, we find that the Ash’ari school adopts the saying that the real conflict may occur, but rather confirms its occurrence.

The second point: For whom is the priority, for the Intellect  or th

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Publication Date
Fri Jul 07 2017
Journal Name
International Journal Of Science And Research (ijsr)
Automatic brain tumor segmentation from MRI Images using superpixels based split and Merge algorithm
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RA Ali, LK Abood, Int J Sci Res, 2017 - Cited by 2

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