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Machine learning-based multi-objective optimization and thermal assessment of supercritical CO_(2) Rankine cycles for gas turbine waste heat recovery

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Energy and AI 2024年第2期16卷 363-384页

作者： Asif Iqbal Turja Ishtiak Ahmed Khan Sabbir Rahman ashraf mustakim Mohammad Ishraq Hossain M Monjurul Ehsan Yasin Khan Department of Mechanical and Production Engineering(MPE) Islamic University of Technology(IUT)Board BazarGazipur1704Bangladesh

Technologies for utilizing waste heat for power generation have attracted significant attention in recent years due to their potential to enhance energy efficiency and reduce greenhouse gas *** research focuses on the comparative and optimization analysis of three supercritical carbon dioxide(sCO_(2))Rankine cycles(simple,cascade,and split)for gas turbine waste heat *** study begins with parametric analysis,investigating the significant effects of key variables,including turbine inlet temperature,condenser inlet temperature,and pinch point temperature,on the thermal performance of advanced sCO_(2) power *** identify the most efficient cycle configuration,a multi-objective optimization approach is *** approach combines a Genetic Algorithm with machine learning regression models(Random Forest,XGBoost,Artificial Neural Network,Ridge Regression,and K-Nearest Neighbors)to predict cycle performance using a dataset extracted from cycle *** decision-making process for determining the optimal cycle configuration is facilitated by the TOPSIS(technique for order of preference by similarity to the ideal solution)*** study's major findings reveal that the split cycle outperforms the simple and cascade configurations in terms of power generation across various operating *** optimized split cycle not only demonstrates superior power output but also exhibits enhanced net power output,heat recovery,system and exergy efficiency of 7.99 MW,76.17%,26.86%and 57.96%,respectively,making it a promising choice for waste heat recovery *** research has the potential to contribute to the advancement and widespread adoption of waste heat recovery in energy technologies boosting system efficiency and economic *** provides a new perspective for future research,contributing to the improvement of energy generation infrastructure.

关键词： Supercritical co2 Rankine cycle Waste heat recovery Gas turbine Thermodynamic analysis Machine Learning Optimization

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Miniaturized Argon Plasma: Neutral Gas Characteristics in Dielectric Barrier Discharge

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Plasma Science and Technology 2015年第10期17卷 853-861页

作者： ashraf FARAHAT Department of Prep Year Physics College of Applied and Supporting StudiesKing Fahd University of Petroleum and Minerals(KFUPM) Department of Physics Faculty of Science Moharam Beek Alexandria University

Plasma-neutral gas dynamics is computationally investigated in a miniaturized mi- crothruster~ that encloses Ar and contains dielectric material sandwiched between two metal plates using a two-dimensional plasma mode. Spatial and temporal plasma properties are investigated by solving the Poisson equation with the conservation equations of charged and excited neutral plasma species using the COMSOL Multiphysics 4.2b. The microthruster property is found to depend on the secondary electron emission coefficient. The electrohydrodynamic force （EHD） is calculated and found to be significant in the sheath area near the dielectric layer and is found to affect gas flow dynamics including the Ar excimer formation and density. The effects of pressure and secondary emission coefficient are discussed. The plasma characteristics are affected by small changes in the secondary electron emission coefficient, which could result from the dielec- tric erosion and aging, and is found to affect the electrohydrodynamic force produced when the microthruster is used to produce thrust for a small spacecraft.

关键词： plasma modeling plasma species dielectric barrier discharge

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Hydraulic jump basins with wedge-shaped baffles

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2012年第7期13卷 519-525页

作者： ashraf Fathy ELLAYN Institute of Port Coastal and Offshore Engineering Zhejiang University

This laboratory study deals with the hydraulic jump properties for an artificially roughened bed with wedge-shaped baffle blocks. The experiments were conducted for both smooth and rough beds with a Froude number in the range of 3.06≤F1≤10.95 and a relative bed roughness ranging 0.22≤KR≤1.4. The data from this study were compared with those of rectangular baffle blocks. New experimental formulae were developed for determining the sequent depth ratio and the hydraulic jump length in terms of the inflow Froude number and relative bed roughness. Bélanger's jump equation of a rectangular channel was extended to account for the implications of the bed shear stress coefficient attributable to channel bed roughness. It was found that, in comparison with the smooth bed, the wedge-shaped bed roughness reduced the sequent depth of the hydraulic jump by approximately 16.5% to 30% and the hydraulic jump length by approximately 30% to 53%.

关键词： Energy dissipater Hydraulic jump Stilling basins Wedge-shaped bed roughness

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MHD stagnation point flow of a micropolar fluid towards a heated surface

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Applied Mathematics and Mechanics(English Edition) 2011年第1期32卷 45-54页

作者： M.ashraf M.M.ashraf Centre for Advanced Studies in Pure and Applied Mathematics Bahauddin Zakariya University

The problem of two dimensional stagnation point flow of an electrically conducting micropolar fluid impinging normally on a heated surface in the presence of a uniform transverse magnetic field is analyzed. The governing continuity, momentum, angular momentum, and heat equations together with the associated boundary conditions are reduced to dimensionless form using suitable similarity transformations. The reduced self similar non-linear equations are then solved numerically by an algorithm based on the finite difference discretization. The results are further refined by Richardson＇s extrapolation. The effects of the magnetic parameter, the micropolar parameters, and the Prandtl number on the flow and temperature fields are predicted in tabular and graphical forms to show the important features of the solution. The study shows that the velocity and thermal boundary layers become thinner as the magnetic parameter is increased. The micropolar fluids display more reduction in shear stress as well as heat transfer rate than that exhibited by Newtonian fluids, which is beneficial in the flow and thermal control of polymeric processing.

关键词： magnetohydrodynamics (MHD) stagnation flow micropolar fluids finitedifferences similarity transformations boundary layer

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Employing adaptive fuzzy computing for RCP intelligent control and fault diagnosis

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Nuclear Science and Techniques 2023年第9期34卷 82-93页

作者： ashraf Aboshosha Hisham A.Hamad Rad.Eng.Department NCRRTEgyptian Atomic Energy Authority(EAEA)CairoEgypt Electronics Technology Department Faculty of Technology and EducationHelwan UniversityCairoEgypt

Loss of coolant accident(LOCA),loss of fluid accident(LOFA),and loss of vacuum accident(LOVA)are the most severe accidents that can occur in nuclear power reactors(NPRs).These accidents occur when the reactor loses its cooling media,leading to uncontrolled chain reactions akin to a nuclear *** article is focused on exploring methods to prevent such accidents and ensure that the reactor cooling system remains fully *** reactor coolant pump(RCP)has a pivotal role in facilitating heat exchange between the primary cycle,which is connected to the reactor core,and the secondary cycle associated with the steam ***,the RCP is integral to preventing catastrophic events such as LOCA,LOFA,and LOVA *** this study,we discuss the most critical aspects related to the RCP,specifically focusing on RCP control and RCP fault *** AI-based adaptive fuzzy method is used to regulate the RCP’s speed and torque,whereas the neural fault diagnosis system(NFDS)is implemented for alarm signaling and fault diagnosis in nuclear *** address the limitations of linguistic and statistical intelligence approaches,an integration of the statistical approach with fuzzy logic has been *** integrated system leverages the strengths of both *** fuzzy control was applied to the VVER 1200 NPR-RCP induction motor,and the NFDS was implemented on the Kori-2 NPR-RCP.

关键词： Nuclear power plant(NPP) Reactor coolant pump Fault diagnosis Reactor passive safety Neural network Adaptive fuzzy

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First PPMXL photometric analysis of open cluster Ruprecht 15

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Research in Astronomy and Astrophysics 2012年第2期12卷 158-166页

作者： ashraf Latif Tadross National Research Institute of Astronomy & Geophysics

We present the first in a series studying the astrophysical parameters of open clusters using the PPMXL＊ database whose data are applied to study Ruprecht 15. The astrophysical parameters of Ruprecht 15 have been est... 详细信息

关键词： open clusters and associations (individual: Ruprecht 15) -- astrometry-- stars -- astronomical databases: catalogs

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The simplest way to get a cluster's parameters in the Gaia era(Dolidze 41)

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Research in Astronomy and Astrophysics 2018年第12期18卷 137-142页

作者： ashraf Latif Tadross National Research Institute of Astronomy&Geophysics 11421-HelwanCairoEgypt

The astro-photometric parameters of the open star cluster Dolidze 41, which is located in the constellation Cygnus, have been investigated using the Gaia DR2 large survey that is merged with the near infrared Two Micron All Sky Survey(2 MASS) *** radial density distribution(limited,core and tidal radii), color-magnitude diagrams, galactocentric coordinates, distances, color excess and age of Dolidze 41 are *** Gaia DR2 astrometry helped us to define the membership of the cluster stars *** luminosity and mass functions, the entire luminosity and mass, and the relaxation time of the cluster have been estimated as well.

关键词： (Galaxy:) open clusters and associations:individual(Dolidze 41) photometry:Color-Magnitude Diagram astrometry stars:luminosity function mass function astronomical data bases:miscellaneous

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Production of carbide-free thin ductile iron castings

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Journal of University of Science and Technology Beijing 2008年第5期15卷 552-555页

作者： M. ashraf Sheikh Department of Industrial and Manufacturing Engineering Rachna College of Engineering and Technology

The fast cooling rate of thin ductile iron castings requires special consideration to produce carbide-free castings. Extraordinary care was taken to select the charge to produce castings of 100-mm long round bars with 16-mm diameter. The castings show the presence of carbides in the bars. Seven melts were made with different temperatures and with different compositions to get rid of carbides. After chemical analyses,it was found that the extra purity of the charge with less than 0.008wt% sulfur in the castings was the cause of carbides. To remove the carbides from the castings,sulfur should be added to the charge.

关键词： casting ductile iron carbides fluidity

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Evaluation of soil loss severity and ecological restoration approach for sustainable agriculture in the Hindu Kush, Karakoram and Himalaya region

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Journal of Mountain Science 2024年第5期21卷 1509-1521页

作者： Arshad ashraf Imran AHMAD Climate Energy and Water Research InstituteNational Agricultural Research Centre(NARC)Islamabad 44000Pakistan

Soil erosion has resulted in removal of the topsoils containing fine soil particles and plant nutrients, causing decrease in soil fertility in the Hindu Kush, Karakoram and Himalaya(HKH) region. The existing production of cereal crop grains has been reduced to one third of the potential crop grains production owing to land degradation and poor farming practices. It is necessary to assess risk of soil loss and identify appropriate controlling measures to address issues of low agriculture productivity and water insecurity in the region. In the present study, severity of soil loss was predicted using Revised Universal Loss Equation(RUSLE) and ecological measures were identified for sustainable mountain agriculture in the HKH region of Upper Indus Basin, Pakistan. Overall 62.6% area was found to have very low risk of soil loss, i.e., 100 t/(ha·yr) in about 6.8% and 7.4% areas respectively. The mean rate of soil loss was about 41.9 t/(ha·yr) in the Hindu Kush, 31.1 t/(ha·yr) in the Himalayas, 18.8 t/(ha·yr) in the Karakoram and overall 29.7 t/(ha·yr) in the three HKH ranges. As such no considerable measures have been adopted by the communities for restoration of the degraded areas except raising fruit/farm trees and supporting limited social forestry for their livelihoods. The slopes cleared for cultivation and susceptible to erosion may be stabilized through sowing/planting of multi-purpose plant species and formation of proper bench terraces. The conservation of forest ecosystem and pastures at higher elevations would help in reducing overland water flow, risk of flash flood hazard and minimizing sediment loads in the downstream. It is essential to adopt site-specific resource conservation techniques and restore possible ecosystem health for sustainable agriculture and economic developm

关键词： Climate change Erodibility Indus basin Land degradation Slope stabilization

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Structural behavior of intermediate length cold-formed steel rack columns with C-stitches

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Frontiers of Structural and Civil Engineering 2019年第4期13卷 937-949页

作者： M. ANBARASU Mahmud ashraf Department of Civil Engineering Government College of Engineering Salem 636011 India School of Engineering Deakin University Geelong VIC 3216 Australia

This article presents an experimental and numerical investigation on the strength and performance of intermediate length rack column sections with C-stitches under axial compression. The test program consisted of 10 axial concentric compression tests on columns with and without C-stitches under pin end conditions for two different geometric lengths. Finite element (FE) models were developed using commercial FE package ABAQUS considering material and geometric nonlinearities as well as initial geometric imperfections. The elastic buckling properties of the section were calculated using readily available linear elastic buckling analysis tools based on Generalized Beam Theory (GBT) and Finite Strip Method (FSM). Obtained FE results were compared with those obtained experimentally, and once verified the developed FE modeling technique was used to carry out a parametric study to examine changes in structural response due to variations in length, depth and spacing of C-stitches. Observed influences of C-stitches on the behavior and resistance of the considered columns were carefully analyzed, and key design aspects are presented herein.

关键词： cold-formed steel columns C-stitches intermediate length columns distortional buckling

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