Dam and powerhouse operation sustainability is a major concern from the hydraulic engineering perspective. Powerhouse operation is one of the main sources of vibrations in the dam structure and hydropower plant; thus, the evaluation of turbine performance at different water pressures is important for determining the sustainability of the dam body. Draft tube turbines run under high pressure and suffer from connection problems, such as vibrations and pressure fluctuation. Reducing the pressure fluctuation and minimizing the principal stress caused by undesired components of water in the draft tube turbine are ongoing problems that must be resolved. Here, we conducted a comprehensive review of studies performed on dams, powerhouses, and turbine vibration, focusing on the vibration of two turbine units: Kaplan and Francis turbine units. The survey covered several aspects of dam types (e.g., rock and concrete dams), powerhouse analysis, turbine vibrations, and the relationship between dam and hydropower plant sustainability and operation. The current review covers the related research on the fluid mechanism in turbine units of hydropower plants, providing a perspective on better control of vibrations. Thus, the risks and failures can be better managed and reduced, which in turn will reduce hydropower plant operation costs and simultaneously increase the economical sustainability. Several research gaps were found, and the literature was assessed to provide more insightful details on the studies surveyed. Numerous future research directions are recommended.
The aim of this study to investigate the tongue morphology and histology in house gecko Hemidactylus flaviviridis using light and scanning electron –microscopy (SEM ) technique.The morphology result revealed the presence of three parts : apex , body and lingual root .The light microscopy result showed that the tongue is covered with mucous membrane composed of non keratinized stratified squamous epithelium based on lamina propria which contain bundles of striated muscles its fibers in different directions including connective tissue , blood vessels and nerves. The lingual mucosa of the dorsal surface is covered with different pattern of lingual papillae which are widely distributed all over the dorsal surface except the apex. Noticed on t
... Show MoreThe removal of cadmium ions from simulated groundwater by zeolite permeable reactive barrier was investigated. Batch tests have been performed to characterize the equilibrium sorption properties of the zeolite in cadmium-containing aqueous solutions. Many operating parameters such as contact time, initial pH of solution, initial concentration, resin dosage and agitation speed were investigated. The best values of these parameters that will achieved removal efficiency of cadmium (=99.5%) were 60 min, 6.5, 50 mg/L, 0.25 g/100 ml and 270 rpm respectively. A 1D explicit finite difference model has been developed to describe pollutant transport within a groundwater taking the pollutant sorption on the permeable reactive barrier (PRB), which i
... Show MoreThis study was designed to evaluate the effect of anesthesia on thyroid hormones (T3, T4, rT3), thyrotropin(TSH), and cortisol levels in patients undergoing major urological surgery. The study included fifty patients scheduled for elective major urological surgery where 70% of the patients underwent general anesthesia, while30% underwent regional anesthesia. All patients were in stable control general conditions. The study showed that the thyroid hormones, thyrotropin and cortisol levels were affected with general anesthesia more than regional. The levels of these hormones responded to anesthetics and surgical stresses. This response was thought to be mainly mediated by afferent neurogenic impulses from the area of injury. Therefore, ab
... Show MoreCeramics type Yttrium oxide with Silicon carbide. were selected to investigate its sintered density, microstructure and electrical properties, after adding V2O5, of 100 nm grain size. Different weight percentages ranging from (0.01,0.02,0.03 and 0.04) were used. Dry milling applied for twelve hours. The pelletized samples were sintered at atmospheric of static air and at sintering temperature 1400 ˚C, for three hours. The crustal structure test shoes the phase which is yttrium silicon carbide Scanning electron microscopy, scan sintered microstructure. Samples after sintering were electrically investigated by measuring its capacitance, dielectric constant and their results showed increasing after added V2O5 particles at the combinat
... Show MoreIn this time, most researchers toward about preparation of compounds according to green chemistry. This research describes the preparation of 2-fluoro-5-(substituted benzylideneamino) benzonitrile under reflux and microwave methods. Six azomethine compounds (B1-6) were synthesized by two methods under reflux and assisted microwave with the comparison between the two methods. Reflux method was prepared of azomethine (B1-6) by reaction of 5-amino-2-fluorobenzonitrile with some aldehyde derivatives with (50–100) mL of absolute ethanol and some quantity of GAA and time is limited between (2–5) hours with a yield between (60–70) percent with recrystallization for appropriate solvents. But the microwave-assisted method was synthesized of co
... Show MoreHypothyroidism is a frequent disorder in the general population, especially among women, is defined as adeficiency of thyroid activity that results from insufficient production or action of thyroid hormones leading to a totaldecrease of metabolic. Human leukocyte antigen is the most polymorphic genetic system in man. Genes of this regioninfluence susceptibility to certain diseases.Objectives: The purpose of the present study is to investigate the role of HLA-DRB1 genotyping in hypothyroidpatients with and without periodontitis. Sixty hypothyroid patients 30 of patients were with periodontitis and 30without periodontitis compare with 30 healthy subjects as control enrolled in this study. DNA was extracted fromblood samples, then HLA- genotyp
... Show MoreNews are considered the most press arts that supply the target audiences with daily information and events happened inside and outside society since it is formed by depending on its resources which have a deep relation with formal corporations to gain their satisfaction in order to support their authority and spreading their domination by using mass media in editing their viewpoints and achieving wide acceptance among public opinion. In the field of technological development and changing in the fields of politics, society, culture, economics etc. inside Iraqi society and democratic transition help to convert news agenda from independent variation to a fellow variation while in the past the variation of mass media was the independent one
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