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Shekhar Aryal,Sailesh Chitrakar,Rajendra Shrestha,Ajay Kumar Jha 한국유체기계학회 2020 International journal of fluid machinery and syste Vol.13 No.4
The hydropower plants under Himalayan basins are mostly characterized by heavy sediment load due to geographical and metamorphic constraints. Run-off-river projects with limited size of the desilting basins allow suspended sediments to get carried into the turbine components causing wear due to sediment erosion. In the case of high head power plants consisting of Francis turbines, a large portion of the hydraulic energy is transformed into kinetic energy within the guide vanes. This causes various instabilities in the flow due to high acceleration and velocity. Some recent studies have shown that due to the combined effect of the secondary flow around the guide vanes and sediment carrying flow, the size of the clearance gap increases, which further aggravates the performance of the turbine. This study takes a reference of one of the power plants in Nepal containing high head Francis turbines. An in-depth analysis of the effect of the sediment in this power plant and sediment erosion in the turbine components has been performed. A CFD analysis of the guide vanes and runner blades corresponding to the same turbine has been conducted and the results are used to analyze the erosion pattern on the actual turbine. The detailed erosion analysis is made possible with a 3D scanner, such that the eroded regions can be captured and classified based on the flow behavior at those regions. Guide vanes and runner blades are found to be the predominant components affected by erosion. It has been seen that most of the erosion affected regions are originated from increasing clearance gaps between guide vane and facing plates caused due to continuous leakage flow within the two sides of the guide vanes.
Aryal Aayush,Garg Bhavuk,Mehta Nishank,Shekhar Shubhankar,Gupta Vivek 대한척추외과학회 2022 Asian Spine Journal Vol.16 No.5
Historically, osteoarticular tuberculosis (TB), including spinal TB, was treated with prolonged course of antitubercular therapy (ATT). Due to various challenges, there has been reluctance to explore the use of short-course ATT in spinal TB. However, with the success of short-course ATT being demonstrated in other forms of extrapulmonary TB, the subject is open for debate again. Therefore, we systematically reviewed various published literature to determine whether short-course treatment regimen (6 months) of ATT provides equivalent results in terms of disease healing as long-course treatment regimen (≥9 months) in the management of spinal TB. Five electronic databases (PubMed, MEDLINE, EMBASE, CENTRAL, and Web of Science) and their reference lists were searched to identify relevant randomized controlled trials with at least 1 year of follow-up that compared short-course with standard-course ATT for treatment of spinal TB. The methodological quality of included studies was assessed, and their data were extracted. A meta-analysis was used to calculate pooled effect sizes and 95% confidence interval (CI). The outcome measure was healed status of the disease at the final follow-up. Of 331 publications identified through literature search, eight publications describing six randomized studies were included. Moreover, 375 of 414 patients (90.58%) who received 6 months of ATT had healed status at their final follow-up compared to 404 of 463 patients (87.26%) who received ≥9 months of ATT. Overall, the healed status of spinal TB was equivalent in patients in both groups (pooled relative risk, 0.98; 95% CI, 0.92–1.04; <i>p</i> =0.439). However, there was considerable heterogeneity among the trials (I2=40.8%, <i>p</i> =0.149). The results suggest that the use of short-course (6 months) chemotherapy may be considered for the treatment of spinal TB in view of the similarity in the healing response achieved compared to treatment regimens of longer duration.