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The Experimental Assessment of R134a and Its Lower GWP Alternative R1234yf in an Automobile Air Conditioning System
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Reducing global warming potential (GWP) of refrigerants is needed to the decrease of ozone-depleting of refrigeration systems leakages. Refrigerant R1234yf is now used to substitute R134a inside mobile air conditioning systems. Thermodynamic properties of R1234yf are similar to R134a. Also, it has a very low GWP of 4, compared to 1430 for R134a, making it a proper choice for future automobile refrigerants. The purpose of this research is to represent the main operating and performance differences between R1234yf and R134a. Experimental analysis was carried out on the automotive air conditioning system (AACS) with 3 kW nominal capacity, to test and compare the performance of R134a with R1234yf. Experiments were accomplished for both refrigerants in almost the same working conditions and procedure with a range of ambient temperature varied from 26oC to 50oC. Parameters studied were ambient temperature, type of refrigerant in the system at compressor speed 1450 rpm, and internal thermal loads of passenger room. The performance characteristics of the system, including COP and cooling capacity, were studied by changing different parameters. The results show that COP of R134a is higher than R1234yf by 12.6%, while the refrigeration effect of R134a is higher than R1234yf by 25%. This shows that R1234yf is a suitable and good candidate for drop-in replacement of R134a in AACS.

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Publication Date
Mon Jul 14 2025
Journal Name
Journal Of Baghdad College Of Dentistry
Histological and mechanical evaluation of the osseointegration of titanium implants by the modifications of thread design and/or coating with flaxseed (An experimental study on rabbits)
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Background: Dental implant surface technologies have been evolving rapidly to enhance a more rapid bone formation on their surface and improve implant therapy.Implant threads should be designed to increase surface contact areathat induced better stability. In addition, implant surface coating with Flaxseed was used to enhance bone formation at the bone-implant interface. Materials and methods: Ninety-six commercially pure titanium (CpTi) screws were implanted in rabbits' tibiae and divided into three groups as dual-threaded group, flaxseed-coated group and control group. All groups were evaluated mechanically, histologically and radiographically after each healing periods (2, 4, 6 and 8) weeks and the resulting data were statistically analy

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Publication Date
Fri Apr 30 2021
Journal Name
Al-kindy College Medical Journal
Introduction of an Appointment System in Primary Health Care Setting in Baghdad: Views of Patients and Health Care Providers
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Background: The appointment system is a common practice in primary health care clinics in developed countries. The patients and health care providers in the primary health care setting perceived the appointment system as an indicator of good quality service.

Objective: The aim of this study was to survey patients’ and health care providers’ attitudes towards the introduction of an appointment system and their satisfaction with the existing ‘walk-in’ system in the primary health care setting.

Subjects and Methods: A questionnaire survey was conducted included a convenient sample of 234 patients as well as 76 health care providers from two primary health care center

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Publication Date
Sun Jan 01 2023
Journal Name
Dental Hypotheses
Assessment of Salivary Levels of the RANKL and RANK in Patients with Healthy Gingiva on Reduced Periodontium Versus Periodontitis: An Analytical Cross-Sectional Study
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Publication Date
Tue Sep 15 2020
Journal Name
Arab World English Journal
A Cognitive-Semantic Analysis of Preposition on: An Experimental Study at University of Baghdad
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Publication Date
Wed Sep 15 2021
Journal Name
Al-academy
Contemporary experimental currents and its impact on the structure of the contemporary Iraqi theatrical text "The epic theater as a model": هيثم حمزة سلمان الحمداني
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  In this research study, I tried to trace the epic effect to learn how it was understood and how it was used. Following the descriptive and analytical approach in the research, the first chapter dealt with a presentation of the methodological framework of the problem, the goal, the limits of the research, the importance and the need for it and the definition of terms, as well as the theoretical framework which consisted of two topics, including the impact of the epic theater on the world theater and the second the effect of the epic theater on the Arab theater, This came by tracing the epic impact on the world stage of the Greeks, the Middle Ages, the Renaissance, and the Arab theater of the twentieth century.
As for the second

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Publication Date
Thu Nov 21 2019
Journal Name
Journal Of Engineering
Assessment of Observed Building Structure Setback of Shops along an Arterial Road and Noise Intrusion Level
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Roads irrespective of the type have specific standard horizontal distance measured at 90 degrees from a lot boundary to a development known as a setback. Non-observance of the recommended setbacks accommodated in any urban center’s master plan creates noise hazard to the public health and safety as the movement of vehicular traffic is not without the attendant noise. This study assessed noise intrusion level in shops along a section of Ibadan-Abeokuta road with due consideration to compliance with the recommended building structure setback. Analysis of noise descriptors evaluated in this study gave A-weighted equivalent sound pressure level average of 91.3 dBA, the daytime average sound level (LD) 92.27 dBA,

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Publication Date
Thu Feb 29 2024
Journal Name
International Journal Of Design & Nature And Ecodynamics
Artificial Neural Network Assessment of Groundwater Quality for Agricultural Use in Babylon City: An Evaluation of Salinity and Ionic Composition
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Publication Date
Tue Mar 30 2021
Journal Name
Journal Of Economics And Administrative Sciences
Designing a Quality System using the Goals Programming Method -An Applied Research
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Due to the continuous development in society and the multiplicity of customers' desires and their keeping pace with this development and their search for the quality and durability of the commodity that provides them with the best performance and that meets their needs and desires, all this has led to the consideration of quality as one of the competitive advantages that many industrial companies compete for and which are of interest to customers and are looking for. The research problem showed that the Diyala State Company for Electrical Industries relies on some simple methods and personal experience to monitor the quality of products and does not adopt scientific methods and modern programs. The aim of this research is to desi

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Publication Date
Thu Nov 02 2023
Journal Name
Journal Of Engineering
Numerical Simulation of the Thermal Performance of a Tubular Solar Air Heater
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In this work, a flat-plate solar air heater (FSAH) and a tubular solar air heater (TSAH) were designed and tested numerically. The work investigates the effect of increasing the contact area between the flowing air and the absorber surface of each heater and predicts the expected results before the fabrication of the experimental rig. Three-dimensional two models were designed and simulated by the ANSYS-FLUENT 16 Program. The solar irradiation and ambient air temperature were measured experimentally on December 1st 2022, at the weather conditions of Baghdad City- Iraq, at three air mass flow rates, 0.012 kg/s, 0.032 kg/s, and 0.052 kg/s. The numerical results showed the advantage in the thermal performance of

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Publication Date
Mon Jan 01 2018
Journal Name
The Journal Of Contemporary Dental Practice
Assessment of Ions released from Three Types of Orthodontic Brackets immersed in Different Mouthwashes: An in vitro Study
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