The main aim of the present paper is to study the electric breakdown in a uniform electric discharge system. The system consists of two spheres separated by a dielectric. The dielectric is dry air. Certain boundary conditions are taken into consideration as applied voltage, pressure, and domain. The formation of discharge types as Townsend and streamer under different distance gaps (1, 0.9,0.8, 0.6, 0.4, 0.2, 0.1) mm was sudied. The temperature effect on the breakdown voltages for the discharge process is also included. Seven different temperature steps are chosen in the study. Comsol Multiphysics software is used for the simulation model as a plasma model. Results show that as the gap distance increases the breakdown voltage increases for each of the discharges. For maximum electric field, as the distance increases the field also increases. For gap distance, the temperature effects are more apparent at the higher values of the pressure. The maximum electric field increases as the voltage increases with the temperature.
Low-pressure capacitively coupled RF discharge Ar plasma has been studied using Langmuir probe. The electron temperature, electron density and Debay length were calculated under different pressures and electrode gap. In this work the RF Langmuir probe is designed using 4MHz filter as compensation circuit and I-V probe characteristic have been investigated. The pressure varied from 0.07 mbar to 0.1 mbar while electrode gap varied from 2-5 cm. The plasma was generated using power supply at 4MHz frequency with power 300 W. The flowmeter is used to control Argon gas flow in the range of 600 standard cubic centimeters per minute (sccm). The electron temperature drops slowly with pressure and it's gradually decreased when expanding the electro
... Show MoreA mathematical model has been formulated to predict the influence of high outdoor air temperature on the performance of small scale air - conditioning system using R22 and alternative refrigerants R290, R407C, R410A. All refrigerants were investigated in the cooling mode operation. The mathematical model results have been validated with experimental data extracted from split type air conditioner of 2 TR capacity. This entailed the construction of an experimental test rig which consists of four main parts. They are, the refrigeration system, psychrometric test facility, measuring instrumentation, and auxiliary systems. The conditioned air was maintained at 25 0C dry bulb and 19 0C wet bulb for all tests. The outdoor ambient air temperatur
... Show MoreIraqi provinces suffer many of the environmental problems, appear explained these problems in the city of Basra, Basra, the largest province and is among Iraq's provinces in the annexation of oil fields, which is experiencing an oil production operations of large, it suffers from the burning of gas associated with oil extraction resulting in the emission severe gas process including toxic hydrogen sulfide gas (h2S) and oxides of carbon, sulfur and nitrogen in addition to the release of toxic metal elements such as mercury, arsenic, vanadium, which caused the man many serious diseases. , And perhaps one of the most important of these problems are worsening air quality and increasing cases of air pollution and the deterioration of the qual
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The prophet said that it anybody burdened any of the people or the book more than they could endure he would ben his opponent until the day of judgment.
-under the rightly guided caliphs the Christians had much freedom .this is shown by a letter attributed to ishu-yab III. The Nestorian catholics.
-The third caliph,Uthman favoured the Christians either because of the spcial skills or abilities which they possessed or through the imfluence of his Christian wife Na'ila.
-Under the early Umayyade,the christiansins the Isalamic umma had as much freedom as they had previously enjoyed under the best of their Christians governments because they restorted their churches and appointed many Christians to the
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The work of this paper is an investigation to improve the condenser performance of the automobile air conditioning system by enhancing the air-side heat transfer from the condenser through the use of an air guide net installed in front of the condenser face which is basically an aluminum plate having a circular entrance shape for the air passage. The A/C system was examined under two types of test. The first test was conducted the air guide net, while the second was done with the air guide net. The performances of the A/C system under these tests were compared. For the second type of test, the experiment was carried out with three different size of air guide net, three different circular diameters (2, 3 and 3.5 cm) a
... Show MoreThis paper investigated an Iraqi dataset from Korek Telecom Company as Call Detail Recorded (CDRs) for six months falling between Sep. 2020-Feb. 2021. This data covers 18 governorates, and it falls within the period of COVID-19. The Gravity algorithm was applied into two levels of abstraction in deriving the results as the macroscopic and mesoscopic levels respectively. The goal of this study was to reveal the strength and weakness of people migration in-between the Iraqi cities. Thus, it has been clear that the relationship between each city with the others is based on and of mobile people. However, the COVID-19 effects on the people’s migration needed to be explored. Whereas the main function of the gravity model is to
... Show Moreone of the most important consequences of climate change is the rise in sea levels, which leads to the drowning of some low-lying island states, which leads to them losing the elements of statehood and thus affecting their status as a state, this resulted in several proposals made by the jurisprudence of international law to solve this issue, perhaps the most important of which is the idea of the government in exile, and the proposal to continue recognition of submerged countries, in a way that makes it possible to talk about a new concept of states represented by deterritorialized states, all of which are ultimately proposals that contain great difficulties that hinder their implementation in reality.
This research examines the phonological adaptation of pure vowels in English loanwords in Iraqi Arabic (IA). Unlike previous small-scale studies, the present study collected 346 loanwords through document review and self-observation, and then analyzed them using quantitative content analysis to identify the patterns of pure vowel adaptation involved in incorporating English loanwords into IA. The content analysis findings showed that most pure vowel adaptations in English loanwords in IA follow systematic patterns and may thus be attributed to specific characteristics of both L1 and L2 phonological systems. Specifically, the findings suggest that the IA output forms typically preserve the features of the input pure vowel to the maxi
... Show MorePhase-change materials (PCMs) have a remarkable potential for use as efficient energy storage means. However, their poor response rates during energy storage and retrieval modes require the use of heat transfer enhancers to combat these limitations. This research marks the first attempt to explore the potential of dimple-shaped fins for the enhancement of PCM thermal response in a shell-and-tube casing. Fin arrays with different dimensions and diverse distribution patterns were designed and studied to assess the effect of modifying the fin geometric parameters and distribution patterns in various spatial zones of the physical domain. The results indicate that increasing the number of