The printed circuit heat exchanger is a plate type heat exchanger with a high performance and compact size. Heat exchangers such as this need a unique form of bonding and other techniques to be used in their construction. In this study, the process of joining plates, diffusion bonding, was performed and studied. A special furnace was manufactured for bonding purposes. The bonding process of copper metal was carried out under specific conditions of a high temperature up to 700 oC, high pressure of 3.45 MPa, and in an inert environment (Argon gas) to make tensile samples. The tensile samples are cylindrical shapes containing groves representing the flow channels in the printed circuit heat exchanger and checking their tensile strength in addition to the standard shape of the tensile specimen to check the yield and ultimate strength of the copper. A higher tensile strength was obtained for diffusion bonded specimens than the yield strength of copper, up to 1.35 times the copper yield strength. The tensile strength decreases with the increase in the number of groves and the decrease in the distance between one grove and another. This is because the stress is concentrated in the sharp corners. A prototype heat exchanger of two plates and a header to be tested for its compressive strength was also manufactured. The results showed that the bond bears an air pressure of up to 8 bar without fail. It was also found to withstand a hydraulic pressure of up to 60 bar until it reached failure.
Different factors have been examined to be related with the prevalence of Girdiasis in the north of Baghdad in human beings which were (gender, age , occupation ,family size,faecal status and presence of domestic animals) during the period from the beginning of April 2009 till the end of March 2010. This study revealed that the total rate of infection in human being was 11.66% , and no significant differences (p?0.05) were noticed between male and female as their rates of infection were 52.32% and 47.68% respectively , as well as no significant relation was observed between faecal status and the rate of infection, the percentage of positive cases in diarrheal patients was higher than the non diarrheal patients who were 74.41 and 25.59 respe
... Show MoreStudies and scientific research conducted in the field of communication have shown that broadcasting has a clear impact on the ideas, attitudes and behavior of the masses if it is better used in making the media message studied.
The role of this means is not only to present opinions and ideas, but also to influence trends by supporting or changing them. This is of course a matter for the nature of the content in terms of its formulation and the way it is prepared and presented. The power and appeal of a radio message is not complete by simply creating content without creating a distinctive design; and to what extent this content depends on the logic and psychology of persuasion.
The conviction of the cont
... Show MoreBackground: One of the most common problems that encountered is postburn contracture which has both functional and aesthetic impact on the patients. Various surgical methods had being proposed to treat such problem. Aim: To evaluate the effectiveness of square flap in management of postburn contracture in several part of the body. Patients and methods: From April 2019 to June 2020 a total number of 20 patients who had postburn contracture in various parts of their body were subjected to scar contracture release using square flap. The follow up period was ranging between 6 months to 12 months. Results: All of our patients had achieved complete release of their band with maximum postoperative motion together with accepted aesthetic outcome. A
... Show MoreThe recent study was conducted to measure some heavy metal content in potato and corn chips in Baghdad markets. Samples were analyzed by Atomic Absorption Spectrophotometer (AAS). Four metals, Cobalt (Co), Cadmium (Cd), Cupper (Cu) and Lead (Pb) were determined. Two types belonging to two manufacturer resources and two trademarks for each resource were tested in this work. Generally, the study recorded that the potato chips were containing metals less than the corn chips. According to Iraqi criteria, all tested types of potato chips were under the allowed levels. The mean of accumulation trend for both types was: Cu>Co>Pb>Cd. The mean of accumulation trend for the corn types of chips was: Baz>Pufack> Fantasia > Snack. T
... Show MoreMandali Basin is located between latitudes (33◦ 39' 00" and 33◦
54' 55") to the north and longitudes (45ο 11' 00" and 45ο 40' 00") to the
east; to the east of Diyala province at the Iraqi-Iranian border; the
basin area is approximately 491 km2.
From the study of climate reality of the basin between 1990-
2013and assessment of the basic climate transactions, it was found
that the annual rate of rainfall is 253.02 mm, the relative humidity
(44.4%), the temperature (21.3 ◦C), wind speed (2.08 m /sec.),
sunshine (8.27 h/day) and evaporation of the basin class (a) (271.98
mm) and corrected potential evapotranspiration (80.03 mm). The
results of the data analysis show that, there are
The aim of the research is to identify the problems of teaching computer material concerning fourth grade students’ point of view in the computer department in the College of Education for Women by identifying the statistically significant differences between the answers of female students to problems in the field of school administration and in the field of teaching computer subject included the sample of research On (39) of (50) students and (78%) From the fourth grade students in the department of computer who had achieved the theoretical part in the first semester and the assembly application in the second semester in the schools of Baghdad city for the aca
... Show MoreThe research aims to apply a modified SERVQUAL model to evaluate the quality of the educational services via conducting exploratory research for students from the College of Administration and Economics- Department of Business Administration- Evening studies at the University of Baghdad. Questionnaire of two parts was distributed to a sample of (72) students out of (720) students of the 2nd.,3rd. and 4th. year in the beginning of the second semester of the year 2008-2009 to measure the expectations and perceptions to the quality of the educational services. Five major dimensions were analyzed to see the gaps for (22) variables. The study concluded that there were (13) variables confirmed that the
... Show MoreIs the subject of the financial structure of the most important topics for which she received the interests of scientific research in the field of financial management , as it emerged several theories about choosing a financial structure appropriate for the facility and behavior change funding them , and in spite of that there is no agreement on a specific theory answer various questions in this regard , and a special issue of the financial structure optimization.
The objective of the research was to identify the most important theories of the structure of modern financial theory has been to focus on the capture of financial firms in two different stages of their life cycle , so-called growth and ma
... Show MoreThe increasing efficiency of the telecommunications network in the city contributes to the increase in spatial interaction between activities (to influence and mutual influence) This study is based on the idea that the upgrading of telephone services provided to citizens are done exclusively through the growth and development of all levels of the service using advanced technologies to know the problems and appropriate solutions in short time and less cost. Thus, crystallized the objectives of the study which was built for the importance of GIS in the planning of services in general, and infrastructure services, in particular, including telephone services, which is represent a point of contact between individuals on the one hand a
... Show MoreA study were conducted to examinate the effect of organic and aqueous (Hot, Cold) Extracts from leaves of Duranta repens on the growth and activities of the following types of Bacteria:- Staphylococcus aureus,Streptococcus pyogens ,Escherichia coli,Klebsilla pneumonia, in addition to the yeast Candida albicans and the fungi Aspergullis niger ,Aspergulls flavus.The result showed that gram Positive Bacteria is more sensitive to the extracts than gram negative bacteria with Minimum inhibitory concentration (MIC) value (50,25,50,100)% and Minimum Bactericidal Concentration (MBC) value (100,50,200,100)% for all types Bacteria respectively . The most active extract against A.niger ,A,flavus was cold and hot aqueous extract from the leaves with d
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