The hydrodynamics of a co-current down flow bubble column has been investigated with air – water system. A Perspex bubble column of 5cm in diameter and 1.5m height is used as a test contactor using nozzles of 7, 8 and 9 mm diameter for air-water distributing. The column is provided with three electro-resistivity needle probes for bubble detection.
Experimental work is carried out with air flow rates from 0.09 to 0.45 m3/hr and liquid flow rates from 0.65 to 1.1m3/hr in order to study the effects of superficial gas velocity, nozzle diameter and liquid flow rate on the characteristics of hydrodynamic interactions viz. gas hold up, bubble diameter and bubble velocity by using two technical methods, direct height measurements for air-water mixture in the column and resistivity probe techniques.
Gas hold up is found to be progressively increased with increasing superficial gas velocity and with decreasing liquid flow rate. Lower gas hold up is obtained with smaller nozzle diameter. However, gas hold up in two-phase zone is considerably higher than the corresponding value in mixing zone.
The mean bubble velocity is increased with increasing superficial gas velocity, liquid flow rate and nozzle diameter for both mixing and two phase zones. Experimental data are found to be fairly fitted with the Drift Flux model of Zuber and Findly.
The bubble diameter is considerably increased with increasing superficial gas velocity and with decreasing liquid flow rate, whereas it is slightly influenced by nozzle diameter. However, the bubbles in two-phase zone are relatively bigger than those observed in mixing zone. Finally, mathematical correlations have been developed from the experimental data to describe the gas hold up and bubble velocity in the uniform two-phase zone.
Background: Mitral regurgitation (MR) is the most commonly encountered valve lesion in modern clinical practice. Severe mitral regurgitation may cause systolic dysfunction. Left ventricular ejection fraction may not be an accurate measurement of LV function in patients with mitral insufficiency. Myocardial performance index (MPI) is a simple non invasive measure of myocardial function. Methods: The study involved 50 patients with valvular mitral regurgitation and 50 healthy subjects as a control group. Transthoracic echocardiography was carried out for all patients and control group. The echocardiographic measurements included left ventricular end diastolic and end systolic dimensions, left atrial diameter, ejection fraction (EF), and myoca
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Abstract
The research stems from the problem that focuses on a number of questions. They are as follows: What is the extent of interest in the topic of efficiency by the banks and their role in raising the efficiency of the banking business and its development? Is the banking efficiency used in Iraqi banks clear and specific for the Iraqi banking sector? How the banking sector efficiency is measured and what are the approaches adopted in determining the banking inputs and outputs? What is the level of efficiency in the research sample of the banks and what are the causes of its decline or rise in private banks individually and in the Iraqi banking sector in general?
The re
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The research aims to identify the administrative skills and their role in institutional performance, and used the descriptive approach in a survey style and correlational relations to suit the nature of the problem to be studied.The research community was identified with the directors of sports activity in the Iraqi universities in a deliberate manner, and their number is (134) directors, where two scales (administrative skills and institutional performance) were used and the two scales were distributed to the above-mentioned sample in order to obtain answers that meet the required and representative sample of the community on the day 3/12/2021. The answers to all the statements were completed and after processing the results statistically
... Show MoreThe research aims to shed light on the role of artificial intelligence in achieving Ambidexterity performance, as banks work to take advantage of modern technologies, artificial intelligence is an innovation that is expected to have a long-term impact, as well as banks can improve the quality of their services and analyze data to ensure that customers' future needs are understood. . The Bank of Baghdad and the Middle East Bank were chosen as a community for the study because they had a role in the economic development of the country as well as their active role in the banking market. A sample of department managers was highlighted in collecting data and extracting results based on the checklist, which is the main tool for the stu
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Abstract :
The research aims to study the basic concepts of banking productivity and discuss different approaches to study what ends to identify the most important possible standards applied to measured within the Iraqi banking environment as well as research into the causes of low and high Iraqi banking productivity and identify possible treatments to curb those reasons as to ensure the rise. And in line with the research problem, which states what is the level of productivity and what are the causes of decline and the rise in private banking research sample individually. And what the Iraqi private banks and what is the relationship between performance and the impact of productivity change in the perform
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The research Reviews the sides of highlight importance of the Nano-Accounting which doing the accounting performance functions fully computerized without the intervention of an accountant, to solve the problem of not keeping up the rationalization of recording and accounting systems, with the rationalization of production which fully computerized.(be invisible and hidden accounting), resulting by linking or interaction of the accounting, additive production system represented three-dimensional printers, open source and recycling. That which result the rationalizing the facilities of production, organization and self-control which derived nanotechnology idea, which aims to minimize materials and change it properties, then view the a
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This study has came as a result to discover on the references of the educational theories which leads the professors in the educational art departments in the Iraqi universities through knowing these ideological references indeed in an important slice of the society. This slice is: the members of professoriate. The study goal knows the ideological references to these theories for the professors in these departments.
In order to approve the research's goals. The researcher has selected a sample contains (50) professoriate members in these departments in the Iraqi universities which they have the educational art profession among the next scientific degrees (assistant teacher. teacher. assistant professor & professor).
The resea