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RISS 인기검색어
- 검색키워드
- 저자 : Nahvi, S. M. (검색결과 6 건)
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Multi-objective Bayesian optimization of super hydrophobic coatings on asphalt concrete surfaces
Ali Nahvi,Mohammad Kazem Sadoughi,Ali Arabzadeh,Alireza Sassani,Chao Hu,Halil Ceylan,Sunghwan Kim 한국CDE학회 2019 Journal of computational design and engineering Vol.6 No.4
Conventional snow removal strategies add direct and indirect expenses to the economy through profit lost due to passenger delays costs, pavement durability issues, contaminating the water runoff, and so on. The use of superhydrophobic (super-water-repellent) coating methods is an alternative to conven-tional snow and ice removal practices for alleviating snow removal operations issues. As an integrated experimental and analytical study, this work focused on optimizing superhydrophobicity and skid resis-tance of hydrophobic coatings on asphalt concrete surfaces. A layer-by-layer (LBL) method was utilized for spray depositing polytetrafluoroethylene (PTFE) on an asphalt concrete at different spray times and variable dosages of PTFE. Water contact angle and coefficient of friction at the microtexture level were measured to evaluate superhydrophobicity and skid resistance of the coated asphalt concrete. The opti-mum dosage and spay time that maximized hydrophobicity and skid resistance of flexible pavement while minimizing cost were estimated using a multi-objective Bayesian optimization (BO) method that replaced the more costly experimental procedure of pavement testing with a cheap-to-evaluate surrogate model constructed based on kriging. In this method, the surrogate model is iteratively updated with new experimental data measured at proper input settings. The result of proposed optimization method showed that the super water repellency and coefficient of friction were not uniformly increased for all the specimens by increasing spray time and dosage. In addition, use of the proposed multi-objective BO method resulted in hydrophobicity and skid resistance being maximally augmented by approximately 23% PTFE dosage at a spray time of 5.5 s.
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Simulation, analysis and optimal design of fuel tank of a locomotive
Yousefi, A. Karkhaneh,Nahvi, H.,Panahi, M. Shariat Techno-Press 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.50 No.2
In this paper, fuel tank of the locomotive ER 24 has been studied. Firstly the behavior of fuel and air during the braking time has been investigated by using a two-phase model. Then, the distribution of pressure on the surface of baffles caused by sloshing has been extracted. Also, the fuel tank has been modeled and analyzed using Finite Element Method (FEM) considering loading conditions suggested by the DIN EN 12663 standard and real boundary conditions. In each loading condition, high stressed areas have been identified. By comparing the distribution of pressure caused by sloshing phenomena and suggested loading conditions, optimization of the tank has been taken into consideration. Moreover, internal baffles have been investigated and by modifying their geometric properties, search of the design space has been done to reach the optimal tank. Then, in order to reduce the mass and manufacturing cost of the fuel tank, Non-dominated Sorting Genetic Algorithm (NSGA-II) and Artificial Neural Networks (ANNs) have been employed. It is shown that compared to the primary design, the optimized fuel tank not only provides the safety conditions, but also reduces mass and manufacturing cost by %39 and %73, respectively.
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Hossein Ghanavati,Iraj Nahvi,Rasoul Roghanian 한국생물공학회 2014 Biotechnology and Bioprocess Engineering Vol.19 No.3
Process monitoring is one of the most importantfactors affecting production efficiency at industrial scalebioprocesses. In the present work, Flow-cytometric analysishas been employed to monitor and determine neutral lipidcell droplets, granularity and size of the cells of the newoleaginous yeast, Cryptococcus aerius UIMC65. It hasbeen shown that, differences of fluorescent intensity aswell as side and forward scatter light properties have closecorrelations with the differences in lipid production bythese yeast cells. The lipid content-related fluorescentintensity versus forward scatter parameter has been used tomonitor and compare different subpopulations during growthphases on both glucose and xylose in batch cultures. Flowcytometric results have revealed that the observed differencesin the proportion of each subpopulation were related to thespecific growth phase and lipid content of the cells. Thehighest lipid content and lipid productivity were attained at82.62%, 4.47 g/L (at 72 h) and 78.41%, 6.21 g/L (at 60 h)on glucose and xylose growth cultures, respectively. Thehighest biomass, lipid yield and biomass yield were foundto be 7.92 g/L (on glucose culture, at 60 h), 20.92% (onglucose culture, at 48 h) and 50.71% (on glucose culture,at 24 h), respectively.
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Simulation, analysis and optimal design of fuel tank of a locomotive
A. Karkhaneh Yousefi,H. Nahvi,M. Shariat Panahi 국제구조공학회 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.50 No.2
In this paper, fuel tank of the locomotive ER 24 has been studied. Firstly the behavior of fuel and air during the braking time has been investigated by using a two-phase model. Then, the distribution of pressure on the surface of baffles caused by sloshing has been extracted. Also, the fuel tank has been modeled and analyzed using Finite Element Method (FEM) considering loading conditions suggested by the DIN EN 12663 standard and real boundary conditions. In each loading condition, high stressed areas havebeen identified. By comparing the distribution of pressure caused by sloshing phenomena and suggested loading conditions, optimization of the tank has been taken into consideration. Moreover, internal baffles have been investigated and by modifying their geometric properties, search of the design space has been done to reach the optimal tank. Then, in order to reduce the mass and manufacturing cost of the fuel tank, Non-dominated Sorting Genetic Algorithm (NSGA-II) and Artificial Neural Networks (ANNs) have been employed. It is shown that compared to the primary design, the optimized fuel tank not only provides the safety conditions, but also reduces mass and manufacturing cost by %39 and %73, respectively.
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