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Prediction of Heat Transfer Coefficient and Pressure Drop in Wire Heat Exchanger Working with R-134a and R-600a
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An experimental and theoretical works were carried out to model the wire condenser in the domestic refrigerator by calculating the heat transfer coefficient and pressure drop and finding the optimum performance. The two methods were used for calculation, zone method, and an integral method. The work was conducted by using two wire condensers with equal length but different in tube diameters, two refrigerants, R-134a and R-600a, and two different compressors matching the refrigerant type. In the experimental work, the optimum charge was found for the refrigerator according to ASHRAE recommendation. Then, the tests were done at 32˚C ambient temperature in a closed room with dimension (2m*2m*3m). The results showed that the average heat transfer coefficient for the R-600a was higher than the R-134a, so the length of the wire tube was longer with R-134a than R-600a. The pressure drop for the smaller tube diameter was higher than the other tube. The second law thermodynamic efficiency was higher for R-600a, which reached 41%.  The entropy generation minimization analysis showed that the R-600a refrigerant type and smaller tube diameter are approached the optimum point.

 

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Publication Date
Wed Aug 29 2018
Journal Name
Biomedical And Pharmacology Journal
Comparison of Some Mechanical and Physical Properties of three Types of Impression Materials with Different Dental Implant Angulations
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Choosing an appropriate impression material is a challenge for many dentists, yet an essential component to provide an excellent clinical outcome and improve productivity and profit. The purpose of present study was to compare wettability, tear strength and dimensional accuracy of three elastomeric impression materials, with the same consistencies (light-body). Three commercially available light body consistency and regular set 3M ESPE Express polyvinylsiloxane (PVS), 3M ESPE Permadyne polyether (PE), and Identium (ID), impression materials were comparedTear strength test, contact angle test and linear dimensional accuracy were evaluated for three elastic impression material. Among the three experimental groups PE impression materia

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Publication Date
Sun Jul 23 2023
Journal Name
University Of Samarra
Synthesis, spectral characterization and thermal ‎study of complexes of ions of some metallic ‎elements with new cyclic ligands
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The purpose of my thesis is to prepare four new ligands (L1-L4) that have been ‎used to prepare a series of metal complexes by reacting them with metal ions:‎ ‎ M=(Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Hg(II) ‎ ‎ Where succinyl chloride was used as a raw material for the preparation of ‎bi-dented ligands (L1-L4) by reacting it with potassium thiocyanate as a first ‎step and then reacting with (2-aminobenzothiazole, Benzylamine, 4-‎aminoantipyrine, Sulfamethoxazole) respectively as a second step with the use ‎of dry acetone as a solvent, the chemical formula of the four ligands prepared in ‎succession:‎ N1,N4-bis(benzo[d]thiazol-2-ylcarbamothioyl)succinamide (L1)‎ N1,N4-bis(benzylcarbamothioyl)succinami

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Publication Date
Sat Jun 18 2022
Journal Name
Iraqi Journal Of Pharmaceutical Sciences ( P-issn 1683 - 3597 E-issn 2521 - 3512)
Evaluation of the Detrimental Effects of some Antiepileptic Drugs on the Height and Weight of Children with Epilepsy
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Growth is a multifactorial process influenced by genetic, nutritional, hormonal, psychosocial and other factors including the general health of a child. Epilepsy defined as a chronic condition characterized by recurrent clinical events or epileptic seizures, which occur in the absence of a metabolic or toxic disease the drugs that use in the treatment of this condition can affect patients growth due to their mechanisms of action. This study aimed to evaluate the effect of some antiepileptic drugs on growth (height and weight) in children with epilepsy. This work involved 51 newly diagnosed children with a different form of epilepsy (Generalized, absent and partial). Patients divided into three groups according to the treatment (group one

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Publication Date
Wed Sep 30 2015
Journal Name
Modern Sport
The administrative skills of the leaders of the faculties of sports education and their relations with administrative reform
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The research consists of five chapters and aims to explore the administrative skills of leaders in physical education colleges and their relationship with administrative reform. The study sample included (deans, vice deans, and heads of departments) from physical education colleges for the academic year 2012-2013, with a total of 61 individuals. They were selected using the purposive sampling method, and the researcher distributed questionnaires to them, collecting 60 valid responses and excluding one due to its invalidity. After defining the concepts of administrative skills and administrative reform and redownloading relevant literature and previous studies, as well as consulting with a group of experts in management and psychology, the r

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Publication Date
Sat Dec 15 2018
Journal Name
Journal Of The College Of Education For Women
Future Visions and its Relationship with Illegal Immigration among Next to Graduation Students
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The current study was concerned to address these gaps in literature by identifying: first level and type of future visions among the next graduation student, second level and type of future visions among the sample according to gender (Male- Female), third level of the illegal immigration among the sample, fourth level of the illegal immigration according to gender (Male, Female), and finally the relationship between future visions and illegal immigration. To achieve the aims of the current study, the researchers created a questionnaire for the future visions. The psychometric properties (e.g. face validity, structure validity, and reliability) were tested. Base on the current sample, results showed that the questionnaire had sound psych

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Publication Date
Tue Dec 29 2020
Journal Name
Journal Of Accounting And Financial Studies ( Jafs )
Personal tax exemptions "a comparative study with some Arab and European system legislations
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This research aims primarily to highlight personal tax exemptions A comparative study with some Arab and European regulations. And by conducting both theoretical comparative analyses. Most important findings of the study is the need to grant personal and family exemptions that differ according to the civil status of the taxpayer (single or married). In other words, the exemption increases as the number of family members depend on its social sense. Also taking into account some incomes that require a certain effort and looking at the tax rates, it is unreasonable for wages to be subject to the same rates applied to commercial profits.      

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Publication Date
Mon Mar 20 2023
Journal Name
2023 International Conference On Information Technology, Applied Mathematics And Statistics (icitams)
Hybrid Color Image Compression Using Signals Decomposition with Lossy and Lossless Coding Schemes
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Publication Date
Fri Sep 30 2022
Journal Name
Journal Of Economics And Administrative Sciences
Semi parametric Estimators for Quantile Model via LASSO and SCAD with Missing Data
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In this study, we made a comparison between LASSO & SCAD methods, which are two special methods for dealing with models in partial quantile regression. (Nadaraya & Watson Kernel) was used to estimate the non-parametric part ;in addition, the rule of thumb method was used to estimate the smoothing bandwidth (h). Penalty methods proved to be efficient in estimating the regression coefficients, but the SCAD method according to the mean squared error criterion (MSE) was the best after estimating the missing data using the mean imputation method

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Publication Date
Tue May 04 2021
Journal Name
International Journal Of Emerging Technologies In Learning (ijet)
Tactical thinking and its relationship with solving mathematical problems among mathematics department students
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This research aims to know the essence of the correlative relationship between tactical thinking and solving mathematical problems. The researchers followed the descriptive research method to analyze relations, as all students from the mathematics department in the morning study were part of the research group. The research sample of (100) male and female students has been chosen based on the arbitrators' views. The tools for studying the sample of research composed of (12) items of the multiple-choice test in its final form to measure tactical thinking and require establish-ing a test of (6) test-type paragraphs to solve mathematical problems. The findings showed that sample students' tactical thinking and their capacity to overcome mathem

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Publication Date
Wed Jan 01 2020
Journal Name
Iraqi Journal Of Science
Paper based glucose biosensor depending on SPCE modified with hemoglobin and silver nanoparticles
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The direct electron transfer behavior of hemoglobin that is immobilized onto screen-printed carbon electrode (SPCE) modified with silver nanoparticles (AgNPs) and chitosan (CS) was studied in this work. Cyclic voltametry and spectrophotometry were used to characterize the hemoglobin (Hb) bioconjunction with AgNPs and CS. Results of the modified electrode showed quasi-reversible redox peaks with a formal potential of (-0.245 V) versus Ag/AgCl in 0.1 M phosphate buffer solution (PBS), pH7, at a scan rate of 0.1 Vs-1. The charge transfer coefficient (α) was 0.48 and the apparent electron transfer rate constant (Ks) was 0.47 s-1. The electrode was used as a hydrogen peroxide biosensor with a linear response over 3 to 240 µM and a detection li

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