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.
enjoyed the process of the development of higher education institutions attention of most countries of the world and to reconsider its objectives and programs and administrative and organizational structures, and it was the most important development of the application of Quality Assurance and Accreditation Standards (QAAS) tools, as the aim of these tools to the application of advanced with a far-reaching impact on all of the disciplines in the organization methods education that contribute, and plays a performance audit an important role in verifying the extent to which carried out these institutions activities or programs effectively and efficiently, economic, There are a number of objectives for the search of the most important attem
... Show MoreThe services provided by the municipal institutions of the basic things needed by the man in his daily life and the evolution of cities basically depends on these services and therefore has paid most of the world's attention to this vital facility and give him the biggest concern for the welfare of the citizens, as is the research problem that there is no program scrutiny to evaluate the performance of municipal institutions contribute to measuring the efficiency and effectiveness of the services provided and was based on research on the premise that the preparation of the existence of audit program to evaluate the performance of municipal institutions contribute to measuring the efficiency and effectiveness of services provided has reac
... Show MoreIn this study some generic commercial products of Atorvastatin tablets were evaluated by dissolution test in acid medium by comparing with that of parent drug Lipitor of Pfizer Company. Some of solubilizing agents were studied in formulation of Atorvastatin tablet including; surface active agent and PEG 6000 .The most effective factor was the use of PEG6000 in formulation of Atorvastatin tablet which improved the dissolution and the results of dissolution profile of formulated tablet in this work was bioequivalent to that of Lipitor .The quantitative analysis of this work was performed by using reversed phase liquid chromatography and a proper mixture of  
... Show MoreA fast laser texturing technique has been utilized to produce micro/nano surface textures in Silicon by means of UV femtosecond laser. We have prepared good absorber surface for photovoltaic cells. The textured Silicon surface absorbs the incident light greater than the non-textured surface. The results show a photovoltaic current increase about 21.3% for photovoltaic cell with two-dimensional pattern as compared to the same cell without texturing.
An experimental and computational study is conducted to analyze the thermal performance of heat sinks and to pick up more profound information in this imperative field in the electronic cooling. One important approach to improve the heat transfer on the air-side of the heat exchanger is to adjust the fin geometry. Experiments are conducted to explore the impact of the changing of diverse operational and geometrical parameters on the heat sink thermal
performance. The working fluid used is air. Operational parameters includes: air Reynolds number (from 23597 to 3848.9) and heat flux (from 3954 to 38357 W/m
2 ). Conformational parameters includes: change the direction of air flow and the area of conduct
This research aimed at studying the role of calculated knowledge an its efficiency in improving the performance especially most of the organizations are living within knowledge era which concentrate on new technology investment in different fields of modern live . Under the scientific trends towards the economy of calculated knowledge which depend basically on new computer program in order to utilize the knowledge to raise the level of work performance exploiting different resources in the best way that helps the organizations to achieve their objectives because the information technology and computer programs became a means of survival and indispensible instrument within the developed world which depend on prosperity . progress
... Show MoreAfter the internal audit as a tool of internal control in any organization, and helps in the evaluation of all internal control activities, as a tool to ensure compliance with the plans and policies to achieve the goals of the institution as much as possible of the efficiency, effectiveness, and should have the Internal Audit full independence and is linked to senior management, and aims to get the credibility and accuracy of information and data, and keep abreast of modern developments.
The practical side includes the preparation of the questionnaire, which included a set of questions that fit the hypothesis of the research, was Tozeiha the research sample consisting of employees of the Internal Audit Department an
... Show MoreThis study was conducted in the Department of Employment and Loans at the Ministry of Labor and Social Affairs to indicate the importance and impact of both the empowerment and the functional flexibility in evaluating the performance of the employees. To achieve the objectives of the study, the data was collected through a questionnaire form designed for this purpose based on previous studies. Data obtained for a significant evaluation of the relationship between the components of both the empowerment and the functional flexibility with the components of the evaluation and determining the degree of importance of each component of both the empowerment and functional flexibility for the components of the evaluation by the extractio
... Show More: Sound forecasts are essential elements of planning, especially for dealing with seasonality, sudden changes in demand levels, strikes, large fluctuations in the economy, and price-cutting manoeuvres for competition. Forecasting can help decision maker to manage these problems by identifying which technologies are appropriate for their needs. The proposal forecasting model is utilized to extract the trend and cyclical component individually through developing the Hodrick–Prescott filter technique. Then, the fit models of these two real components are estimated to predict the future behaviour of electricity peak load. Accordingly, the optimal model obtained to fit the periodic component is estimated using spectrum analysis and Fourier mod
... Show MorePhotonic Crystal Fiber Interferometers (PCFIs) are widely used for sensing applications. This work presents the fabrication and the characterization of a relative humidity sensor based on a polymer-coated photonic crystal fiber that operates in a Mach- Zehnder Interferometer (MZI) transmission mode. The fabrication of the sensor involved splicing a short (1 cm) length of Photonic Crystal Fiber (PCF) between two single-mode fibers (SMF). It was then coated with a layer of agarose solution. Experimental results showed that a high humidity sensitivity of 29.37 pm/%RH was achieved within a measurement range of 27–95%RH. The sensor also showed good repeatability, small size, measurement accuracy and wide humidity range. The RH sensitivity o
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