Critical review of the trailing edge condition in steady and unsteady flow. Blade flutter in compressors and fans: Numerical simulation of the aerodynamic loading

Existing interpretations of the trailing edge condition, addressing both theoretical and experimental works in steady, as well as unsteady flows are critically reviewed. The work of Kutta and Joukowski on the trailing edge condition in steady flow is reviewed. It is shown that for most practical airfoils and blades (as in the case of most turbomachine blades), this condition is violated due to rounded trailing edges and high frequency effects, the flow dynamics in the trailing edge region being dominated by viscous forces; therefore, any meaningful modelling must include viscous effects. The question of to what extent the trailing edge condition affects acoustic radiation from the edge is raised; it is found that violation of the trailing edge condition leads to significant sound diffraction at the tailing edge, which is related to the problem of noise generation. Finally, various trailing edge conditions in unsteady flow are discussed, with emphasis on high reduced frequencies

Impact of Draw Solution Concentration on Forward Osmosis Process: A Simulation Study

In this study, a simulation model was used to evaluate the performance of forward osmosis process. A solution of low salinity was used as the feed solution in forward osmosis to dilute saline solution (i.e. draw solution) for further desalination. The paper evaluated the effect of the draw solution concentration on the recovery rate and energy consumption in forward osmosis. It was found that increasing the concentration of draw solution increased the recovery rate. Also, while increasing concentration of draw solution, energy consumption decreased. The maximum recovery rate of 33% was achieved using (0.5M NaCl) draw solution and a flow rate of 40000 m3/day. The specific power consumption was 0.21 kWh/m3.This research is made possible by Graduate Sponsorship Research Award (GSRA6-1- 0509-19021) from Qatar National Research Fund (QNRF). The statements made herein are solely the responsibility of the authors

Simulation of Demographic Change in Palestinian Territories

Mortality, birth rates and retirement play a major role in demographic changes. In most cases, mortality rates decreased in the past century without noticeable decrease in fertility rates, this leads to a significant increase in population growth. In many poor countries like Palestinian territories the number of births has fallen and the life expectancy increased. In this article we concentrate on measuring, analyzing and extrapolating the age structure in Palestine a few decades ago into future. A Fortran program has been designed and used for the simulation and analysis of our statistical data. This study of demographic change in Palestine has shown that Palestinians will have in future problems as the strongest age cohorts are the above-60-year olds. We therefore recommend the increase of both the retirement age and women employment.Comment: For Int. J. Mod. Phys. C 18, issue 11; 9 pages including figures and progra

Gravity observations at Sinai Peninsula and its geophysical and geodetic applications

AbstractSouth Sinai is an interesting region from both tectonic and seismological settings. Tectonically, Sinai Peninsula is strongly dominated by its active boundaries due to its location at the triple junction among the Gulf of Suez rift, the Aqaba–Levant transform fault and the Red Sea Rift. Moreover, reported seismological activities along the three tectonic boundaries indicate its continuous activities.It is thus of great interest to delineate the subsurface geological structure responsible of its tectonic settings and its relation to the seismological activity. Therefore, terrestrial gravity observation has been carried out to figure out the sub-surface structure representing its tectonic settings.On the other hand, the location of Sinai Peninsula between Gulf of Suez, Gulf of Aqepa and Red Sea has made the satellite altimetry data an optimum tool to determine the Gravity sources on the marine regions bounding the Sinai region. Finally, temporal gravity variation of the GRACE satellite mission, launched in 2003 gives the opportunity to monitor its temporal gravity variation on regional scale. Temporal gravity variation from GRACE demonstrates any possible mass redistribution along the pounding tectonic settings and its relation to seismicity.Observed gravity map shows significant gravity anomalies attributed to tectonic and seismicity. Satellite altimetry and gravity data are considered to be a valuable source of data to determine the offshore subsurface structure. Temporal gravity variations from GRACE shows important zones of mass redistribution attributed to its new tectonics and its relation to the seismological activities. Integrating all available data sheds more light on the geodynamic behavior of the selected region and its relation to the seismic activities

ANTIDIABETIC, HYPOLIPIDEMIC AND ANTIOXIDANT ACTIVITIES AND PROTECTIVE EFFECTS OF PUNICA GRANATUM PEELS POWDER AGAINST PANCREATIC AND HEPATIC TISSUES INJURIES IN STREPTOZOTOCIN INDUCED IDDM IN RATS

Objective: There is a growing interest in traditional medicinal plants since they contain medicinally active products to remedy many diseases. Punica granatum (PG) has many medicinal applications. The aim of this study was to investigate the antidiabetic, hypolipidemic, antioxidant and hepato-pancreatic protective effects of PG peel powder (PGPP) on streptozotocin (STZ) induced diabetic rats.Methods: Male Swiss albino rats became diabetic with insulin-dependent diabetes mellitus (IDDM) after a single intravenous injection of STZ (50 mg/kg). IDDM-rats received either a daily oral dose of PGPP (200 mg/kg), or insulin for 20 days. On day 21, rats were sacrificed and levels of fasting blood glucose (FBG), aspartate aminotransferase (AST), alanine aminotransferase (ALT), albumin, lipid profile, lipid peroxidation (LPO), nitric oxide (NO), superoxide dismutase (SOD), and total antioxidant capacity (TAC) were estimated. Histopathological studies of liver and pancreas were performed.Results: There was a significant elevation in FBG, AST, ALT activities, NO and LPO levels for induced IDDM. In contrast, albumin level, SOD activity, and TAC exhibited the significant decline. In addition, there was marked lipid profile disturbances, and histopathological changes of liver and pancreas. Following PGPP supplementation, the levels of all the above-mentioned factors were back to normal. Also, liver architecture and the size of an islets of Langerhans of the pancreas were almost back to normal. The effect of PGPP was more pronounced when compared with insulin.Conclusion: PGPP is an effective alternative for the treatment of IDDM through the regeneration of β cells of pancreas and via its strong antioxidant properties.Â

Influencia del calentamiento en microonda sobre la estabilidad de elaborado de "samn"

Butter was converted to samn by microwave and conventional heating. The quality of the processed samn by the two methods was followed by determining the acid, peroxide and TBA values over a period of six weeks at 60°C. The fatty acid composition of samn samples was determined by gas-liquid chromatographic technique. The data show that butter conversion to samn by microwave heating was accomplished in about one half of the time that conventional heating requires. Microwave heating obviously increased the development of samn rancidity compared with the conventional heating. The parameters used for measuring lipid rancidity indicated that the main cause of samn rancidity under the present conditions is an oxidation mechanism.Mantequilla fue transformada en samn por calentamiento en microonda y convencional. La calidad del elaborado de samn por los dos métodos fue seguida mediante determinación de los índices de acidez, peróxido y TBA durante un período de seis semanas a 60°C. La composición en ácidos grasos de muestras de samn fue determinada por técnica cromatográfica gas-líquido. Los datos mostraron que la conversión de mantequilla a samn por calentamiento en microonda fue realizada en aproximadamente una vez y media el tiempo que exige el calentamiento convencional. El calentamiento en microonda, evidentemente, aumentó el desarrollo de la rancidez del samn comparado con el calentamiento convencional. Los parámetros usados para la medida de la rancidez lipídica indicaron que la causa principal de la rancidez del samn bajo las condiciones presentes es un mecanismo de oxidación