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.
The problem of the research is that there is a weakness in speed endurance, which has a direct impact on achievement, as it leads to early fatigue, lack of concentration, and a low level of effectiveness of performance, which made the researchers interested in this problem and finding solutions to it. Hence the importance of the research is evident: preparing cardiorespiratory fitness training to develop speed endurance and rate adaptation. The heartbeat that occurs in runners is a continuous result of training and the use of a type of training that suits the requirements of the 1500-meter running competition. The researchers used the experimental approach with pre- and post-testing for the experimental and control groups. The resea
... Show MoreThis study aims to assess the removal efficiency andestablish the BOD5 and COD statisticalcorrelation of the sewage flowing in Al-Diwaniyah wastewater treatment plant in Iraq during the study period (2005-2016). The strength of the influent wastewater entering the plant varied from medium to high in strength. High concentrations of BOD5 and COD in the effluent were obtained due to the poor performance of the plant. This was observed from the BOD5 /COD ratios that did not confirm with the typical ratios for the treated sewage. To improve the performance of this plant, regression equations for BOD5 and COD removal percentages were suggested which can be used to facilitate evaluation of liquid waste and optimal control process. The equations
... Show MoreThe Video Assistant Referee (VAR) is a technology designed to review on- eld decisions through video footage in order to correct clear and critical refereeing errors. It enables the replay of key moments in slow motion to determine the correct naldecision,withcommunicationbetweenthevideoof cialsandtherefereeconductedviaheadset.Thesystem operates under the principle of "minimal interference, maximum bene t," intervening only in essential situations. This study aimedtoassessthecurrent implementationofVARintheIraqStarsFootballLeagueduringthe2023–2024season. To achieve this objective, the researchers employed a descriptive survey method involving a sample of 220 participants, including referees, coaches, players, assessors, academics, a
... Show MoreThe research aims to measure the relationship and the impact of knowledge management processes to achieve the performance of insurance service, as well as analysis of the reality of the National Insurance Company to identify the level of overall performance, and to achieve this goal, it has been the selection of knowledge management processes according to the survey prepared a supplement to the study (Qubaisi, 2002), and of the four operations (knowledge generation, and storage of knowledge, and the distribution of knowledge, and application of knowledge), which represented the independent variable, and the performance has been the use of quantitative and qualitative measures, (sales growth, customer satisfaction), which represented the
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were determine the problem of current research to answer the question on the consciousness of the Ministry of Agriculture to adopt Staffing strategy and identify the shortcomings as the independent variable, represented by the three dimensions (recruitment , selection, placement) and its impact on high performance, as dependent variable is described in four dimensions (leadership, strategy, structure and processes, culture), in this research were Used analytical descriptive style . This research aims to identify the correlation and impact of Staffing strategy at high-performance in Ministry of Agriculture , To clarify the relationship between
... Show MoreCefixime is an antibiotic useful for treating a variety ofmicroorganism infections. In the present work, tworapid, specific, inexpensive and nontoxic methods wereproposed for cefixime determination. Area under curvespectrophotometric and HPLC methods were depictedfor the micro quantification of Cefixime in highly pureand local market formulation. The area under curve(first technique) used in calculation of the cefiximepeak using a UV-visible spectrophotometer.The HPLC (2nd technique) was depended on thepurification of Cefixime by a C18 separating column250mm (length of column) × 4.6 mm (diameter)andusing methanol 50% (organic modifier) and deionizedwater 50% as a mobile phase. The isocratic flow withrate of 1 mL/min was applied, the temper
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