The enhancement of heat exchanger performance was investigated using dimpled tubes tested at different Reynolds numbers, in the present work four types of dimpled tubes with a specified configuration manufactured, tested and then compared performance with the smooth tube and other passive techniques performance. Two dimpled arrangements along the tube were investigated, these are inline and staggered at constant pitch ratio X/d=4, the test results showed that Nusselts number (heat transfer) of the staggered array is higher than the inline array by 13%. The effect of different depths of the dimple (14.5 mm and 18.5 mm) has been also investigated; a tube with large dimple diameter enhanced the Nusselts number by about 25% for the range of Reynolds number between 4000- 20000. The overall enhancement ratio was used to differentiate the passive technique and comparison of different configurations for the technique itself, the result depicted that the 10 mm dimple diameter with a pitch ratio of X/d= 4 gives better performance than the static mixer and twisted tape techniques. The overall enhancement ratio of the 10 mm dimple diameter is varied from (1.21 to 1.65) that means good performance for a range of Reynolds numbers (4000-20000). This indicates that 21- 65 % of heat transfer area can be saved at the same pumping power compared with the smooth tube heat exchanger.
Social Aspects in the Kingdom of Mali Through Ibn Battuta's book Tuhfat Alnuddar in Garaeb Al Amsar Wa Ajaeb Al Asfar
Samuel Beckett’s Happy Days (1961) clearly portrays a lack of communication among the characters of the play which refers to the condition of modern man. This failure of communication led Samuel Beckett to use a lot of pauses and silences in all plays written instead of using words. To express the bewilderment of the modern man during the 20th century, Beckett adopts the use of no language strategy in the dramatic works. After World War II, people were without hope, religion, food, jobs, homes, or even countries. Beckett gave them a voice. He used a dramatic language out of everyday things, in which silence was part of the syntax as a poetic repetition. Language is no more important to the modern man; instead, he us
... Show MoreBackground: Dental implants act as infrastructure for fixed restoration to look like as a natural tooth. Osseointegration is a biological events and considered as a base for success of dental implant. The aim of this study is to evaluate the bond strength between bone and Ti implant coated with mixture of nano hydroxyapatite-chitosan-collagen compared with Ti implants coated with nano hydroxyapatite implanted in rabbit tibia, after different period of implantation time (two and six weeks) by torque removal test. Material and methods: 36 screws of commercially pure titanium; 8mm in length and 3mm diameter , 18 screws coated with mixture of nano hydroxyapatite-chitosan-collagen and18 screws coated with nano hydroxyapatite by dip coating. St
... Show MoreThe research aimed to determine the role of the agricultural extension in educating farmers about the legislation on the protection of the rural environment from pollution with chemical pesticides working in the Department of Agricultural Extension and Training and the Department of Agricultural Extension in the directorates of agriculture of Najaf and Qadisiyah, and to determine the role of the agricultural extension in the axis of farmers' use of the correct methods to protect the rural environment from pollution with chemical pesticides and the axis of the reasons that lead farmers to pollute the rural environment with chemical pesticides, and to achieve the objectives of this research prepared A questionnaire in the light of rev
... Show MoreThe study aimed at designing compound exercises using added weight on some skill abilities in youth soccer players aged (17 – 19) years old. The researcher sued the experimental method on (30) players aged (17 – 19) years old from Al Zawraa Sport Club. The subjects were divided into three groups and the training program was applied for (8) weeks with (3) training sessions per week. The data was collected and treated using proper statistical operations to conclude that compound exercises with weights between improved the subjects compared to the groups that did not use the added weights. Finally, the researchers recommended the necessity of using compound exercises using added weights during training sessions for youth soccer pla
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The paper exposes a discourse taxonomy of language clichéd units in English and Russian, and presents some definitions of what is a cliché as being a semioticform of perceiving language and discourse. Also, it deals with language clichés as being units of structure reflecting a scheme of stereotypical situations of dialogue, whether among individuals of one culture, or in relation to cross-cultural communication. The paper proposes a taxonomy of units in language clichés in English and Russian by tackling clichés of daily use, such as professional, cultural, artistic, and scientific clichés.
Аннотация
... Show MoreCommunities seek to achieve the economic growth through the optimal use of resources. The human resource is considered the most important of those resources where the insurance institutions take the larger role in the protection of this resource and reducing the impact caused by dangers realization that endures. The general Iraqi insurance company is considered the leading in the field of life insurance since it was founded, and until now.
This research is based on an analyzing the relation between premiums and compensations of life insurance, for individual and the group insurance, and a reality of the
... Show MoreBackground: Blood group system and the ability to taste phenylthiocarbamide (PTC) are the most studied traits in human genetics which have been extensively used in describing genetic variations among human populations around the world that may had an effect on dental caries. The aims of present study were to investigate the caries experience among students with different bitter taste threshold in relation to blood type. Materials and Methods: The sample of present study includes dental students female aged19-21 years. The diagnosis of dental caries was done according to the criteria of Manjia et al, 1989 recording decayed lesion by severity (D1-4) MFS. Furthermore, bitter taste sensitivity was measured according to PTC (phenylthiocarbamid
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