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RISS 인기검색어
- 검색키워드
- 저자 : Nasser Talebbeydokhti (검색결과 4 건)
- 무료
- 기관 내 무료
- 유료
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Development of a New Flow-dependent Scheme for Calculating Grain and Form Roughness Coefficients
Majid Niazkar,Nasser Talebbeydokhti,Seied Hosein Afzali 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.5
Estimating channel roughness is crucial for whatever engineering plans that have been in mind for any reach under consideration. Not only is resistance coefficient not a measurable quantity, but also various factors affecting on its value make its estimation a challenge. Despite of numerous methods available for roughness estimation, the complexity of some of available iterative schemes particularly with no mechanism for modifying initial guess in each iteration restrain numerical modelers to apply merely outdated resistance equations in practice. In order to improve the estimation of hydraulic resistance, a new straightforward flow-dependent scheme, which is capable of estimating Manning’s coefficient due to grain and form roughness, is introduced. A large data is utilized to calibrate and testify the new scheme. The results of comparing the new scheme with that of different models available in the literature show that it achieves the best estimation results and yields to more than 0.87 and 0.67 for R2, 0.15 and 0.17 for mean absolute relative error for estimating grain and form Manning’s coefficients, respectively. This comparison demonstrates that the results achieved by the new scheme are acceptably accurate in favor of roughness estimation.
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Modeling of Non-Breaking and Breaking Solitary Wave Run-Up Using Shock-Capturing TVD-WAF Scheme
Ali Mahdavi,Nasser Talebbeydokhti 대한토목학회 2011 KSCE JOURNAL OF CIVIL ENGINEERING Vol.15 No.6
A numerical model based on the Non-Linear Shallow Water (NLSW) equations is developed to study the propagation and run-up of non-breaking and breaking solitary waves. The Total Variation Diminishing version of Weighted Average Flux (TVD-WAF)explicit method in conjugation with the Harten-Lax-van Leer (HLL) approximate Riemann solver estimates the numerical flux in the governing equations. This approach permits an exact evaluation of wave speeds in the presence of dry bed situations. The bed topography and friction source terms are treated in a fully implicit way. The accuracy of the model is verified by recourse to the classical test problems with known analytical solutions as well as experimental data. The computed run-up heights show satisfactory agreement with existing run-up laws.
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Bakhshi Roghaye,Talebbeydokhti Nasser,Salari Marjan 한국화학공학회 2024 Korean Journal of Chemical Engineering Vol.41 No.3
In practice, various waste streams may be available to drive biocatalyzed electrolysis systems (BESs) for azo dyes decolorization, which can aff ect how BES is employed to achieve superior performance. This work examined the performance of BES and coupling it with an anaerobic sequencing batch reactor (ASBR-BES) in operation with ideal synthetic wastewater (SW) and domestic wastewater (DW) to remove acid orange 7 (AO7). Within 10 h, ASBR-BES-SW showed an acceptable AO7 removal effi ciency (94% ± 0.6%) higher than BES-SW. However, in applying DW, BES achieved 5.3% higher decolorization effi ciency compared to ASBR-BES (79.3% ± 0.7%) in 26 h, which was enhanced to 95.5% ± 0.4% by reducing the electrode spacing to 1 cm. Higher reductant usage ratio and more residual chemical oxygen demand were achieved in SW than DW. Coulombic effi ciencies on AO7 reduction and COD oxidation were evaluated to investigate the contribution of removal processes. Also, variations of electrical conductivity, temperature, pH, and current density during a cycle were examined.
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Saman Baharvand,Reza Rezaei,Nasser Talebbeydokhti,Roohollah Nasiri,Seyed Mehrab Amiri 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.12
In the present study a physical model of a stepped vertical overfall (SVO) spillway is proposed and designed as a novel combination of a free overfall spillway with horizontal steps. First, the hydraulic design characteristics of the proposed spillway were discussed using a laboratory-scaled model. Effective parameters on the energy dissipation rate were defined as the relative critical depth, Froude number, number of steps, and dimensionless steps’ geometry parameter using dimensional analysis. The energy dissipation rate of the stepped vertical overfall spillway is measured using a waterwheel laboratory setup. Different geometry and hydraulic scenarios were used to assess the energy dissipation rate variation of the proposed spillway. Furthermore, Support Vector Regression and Random Forest Regression methods were used to estimate the energy dissipation of the proposed structure. Investigating the energy dissipation rate of 27 geometry scenarios with the available range of discharge revealed that the energy dissipation rate against the water’s relative depth inside the SVO spillway follows a gradually increasing trend ranging between 88.53% to 98.06%. Also, random forest regression algorithm showed more accurate prediction performance than support vector regression approach with RMSE = 0.128 and R2 = 0.99 in training stage and RMSE = 0.115 and R2 = 0.99 in testing stage. The support vector regression model estimated the proposed spillway’s energy dissipation rate with an accuracy of RMSE = 0.67 and R2 = 0.88 in training stage and RMSE = 0.61 and R2 = 0.9 in testing stage.
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