The main objective of this research is to analyze the monthly average daily of global (H), beams (B) and diffuses (D) solar irradiance on a horizontal surface at four selected sites (El-Kharga, Hurghada in Egypt and D...The main objective of this research is to analyze the monthly average daily of global (H), beams (B) and diffuses (D) solar irradiance on a horizontal surface at four selected sites (El-Kharga, Hurghada in Egypt and Dammam, Hail in Saudi Arabia) during the period time from 1980 to 2020. The empirical models between (H/H<sub>o</sub>) and meteorological parameters along with the values of (MBE), (RMSE), MPE, R<sup>2</sup> and the t-Test statics are discussed. The results in this study indicate good agreement between observed and calculated values of total solar energy and diffuse solar fraction. The results for south facing surfaces of the (RMSE) for different slope at different models in the present research are discussions. Nine different models between isotropic and anisotropic used to estimate the diffuse solar radiation on a tilted surface at selected sites in this study. The absolute relative values of RMSE for the south-facing surface ranges from 7 to 41.3 at El-Kharga and Hurghada sites, Egypt in the present study for Koronakis and Stevenand Unsworth (SU) models respectively. The values of (RMSE), for the south-facing surface ranges from 9.3 to 39.7 at Dammam and Hail sites, Saudi Arabia in the present research for Koronakis and Klucher models respectively. For west-facing surface the values of RMSE range from 11.2 to 47.3 for Badescu and Koronakis models at El-Kharga and Hurghada sites, Egypt respectively, while values of RMSE range from 6.5 to 38.5 for Klucher and Reindl et al. models at Dammam and Hail sites, Saudi Arabia. The models Koronakis, Klucher and Stevenand Unsworth (SU) models are given the most accurate estimate for the south-facing surface, and Badescu, Koronakis, Klucher and Reindl et al. models are good performs better estimated for the west-facing surface.展开更多
By building a tunnel model with a semi-circular crown, the asymmetric rock pressure applied to the shallow tunnel in strata with inclined ground surface is analyzed. Formulae, which not only include the parameters .re...By building a tunnel model with a semi-circular crown, the asymmetric rock pressure applied to the shallow tunnel in strata with inclined ground surface is analyzed. Formulae, which not only include the parameters .related to both tunnel structure and surrounding rock mass, but the overburden depth, are developed. The computation for four tunnel models show that the method presented is feasible and convenient. Furthermore, the influence of the overburden depth on the rock pressure is elaborated, and the criterion to identify the deep or shallow tunnels is formulated as well.展开更多
A wide range of technological and industrial domains,including heating processors,electrical systems,mechanical systems,and others,are facing issues as a result of the recent developments in heat transmission.Nanoflui...A wide range of technological and industrial domains,including heating processors,electrical systems,mechanical systems,and others,are facing issues as a result of the recent developments in heat transmission.Nanofluids are a novel type of heat transfer fluid that has the potential to provide solutions that will improve energy transfer.The current study investigates the effect of a magnetic field on the two-dimensional flow of Williamson nanofluid over an exponentially inclined stretched sheet.This investigation takes into account the presence of multi-slip effects.We also consider the influence of viscous dissipation,thermal radiation,chemical reactions,and suction on the fluid’s velocity.We convert the nonlinear governing partial differential equations(PDEs)of the fluid flow problem into dimensionless ordinary differential equations(ODEs)through the utilization of similarity variables.We then use the homotopy analysis method(HAM)to numerically solve the resulting ordinary differential equations(ODEs).We demonstrate the effects of numerous elements on a variety of profiles through graphical and tabular representations.We observe a drop in the velocity profile whenever we increase either the magnetic number or the suction parameter.Higher values of the Williamson parameter lead to an increase in the thermal profile,while the momentum of the flow displays a trend in the opposite direction.The potential applications of this unique model include chemical and biomolecule detection,environmental cleansing,and the initiation of radiation-induced chemical processes like polymerization,sterilization,and chemical synthesis.展开更多
Nowadays,the sleeper,railroad bed,welding technology and materials of the high-speed&heavy-load Continuous Welded Rail(CWR)have been improved greatly.However,the orientation relationship between welding surface an...Nowadays,the sleeper,railroad bed,welding technology and materials of the high-speed&heavy-load Continuous Welded Rail(CWR)have been improved greatly.However,the orientation relationship between welding surface and rail is still orientation structure,which appeared 185 years ago in UK,namely,the welding surface is normal to the longitudinal direction of the rail.Thus rail welds are subject to vertical pure shear stress,lateral pure shear stress and axial pure tensile stress.Pure shear stress and pure tensile stress are both dangerous stresses,which result in failure of welds under high-speed&heavy-load condition for a long time.When the wheels pass rail welds,it is difficult to avoid vertical bumping and lateral vibration.In order to solve these problems,in this paper we put forward the single inclined welding surface having dip angleαwith the lateral rail or dip angleβwith the vertical rail and analyze the position geometry and stress state.Thus the vertical bumping and lateral vibration are basically eliminated,then the bearing capacity of the welding surface is significantly improved,and the stress of axial pure tensile and lateral pure shear of the welding surface is reduced.展开更多
This article focuses on the effect of radiation on mixed convection in a nanofluid along an inclined wavy surface embedded in a non-Darcy porous medium.A coordinate transformation is employed to transform the complex ...This article focuses on the effect of radiation on mixed convection in a nanofluid along an inclined wavy surface embedded in a non-Darcy porous medium.A coordinate transformation is employed to transform the complex wavy surface to a smooth surface.The governing equations are transformed into a set of partial differential equations using the nonsimilarity transformation and then a local similarity and non-similarity method is applied to obtain coupled ordinary differential equations.These resulting equations are linearized using the successive linearization method and then solved by the Chebyshev spectral method.The effects of radiation,non-Darcy parameter,Brownian motion parameter,thermophoresis parameter,the amplitude of the wavy surface,angle of inclination of the wavy surface on the non-dimensional heat and nanoparticle mass transfer rates are studied and presented graphically.展开更多
文摘The main objective of this research is to analyze the monthly average daily of global (H), beams (B) and diffuses (D) solar irradiance on a horizontal surface at four selected sites (El-Kharga, Hurghada in Egypt and Dammam, Hail in Saudi Arabia) during the period time from 1980 to 2020. The empirical models between (H/H<sub>o</sub>) and meteorological parameters along with the values of (MBE), (RMSE), MPE, R<sup>2</sup> and the t-Test statics are discussed. The results in this study indicate good agreement between observed and calculated values of total solar energy and diffuse solar fraction. The results for south facing surfaces of the (RMSE) for different slope at different models in the present research are discussions. Nine different models between isotropic and anisotropic used to estimate the diffuse solar radiation on a tilted surface at selected sites in this study. The absolute relative values of RMSE for the south-facing surface ranges from 7 to 41.3 at El-Kharga and Hurghada sites, Egypt in the present study for Koronakis and Stevenand Unsworth (SU) models respectively. The values of (RMSE), for the south-facing surface ranges from 9.3 to 39.7 at Dammam and Hail sites, Saudi Arabia in the present research for Koronakis and Klucher models respectively. For west-facing surface the values of RMSE range from 11.2 to 47.3 for Badescu and Koronakis models at El-Kharga and Hurghada sites, Egypt respectively, while values of RMSE range from 6.5 to 38.5 for Klucher and Reindl et al. models at Dammam and Hail sites, Saudi Arabia. The models Koronakis, Klucher and Stevenand Unsworth (SU) models are given the most accurate estimate for the south-facing surface, and Badescu, Koronakis, Klucher and Reindl et al. models are good performs better estimated for the west-facing surface.
文摘By building a tunnel model with a semi-circular crown, the asymmetric rock pressure applied to the shallow tunnel in strata with inclined ground surface is analyzed. Formulae, which not only include the parameters .related to both tunnel structure and surrounding rock mass, but the overburden depth, are developed. The computation for four tunnel models show that the method presented is feasible and convenient. Furthermore, the influence of the overburden depth on the rock pressure is elaborated, and the criterion to identify the deep or shallow tunnels is formulated as well.
文摘A wide range of technological and industrial domains,including heating processors,electrical systems,mechanical systems,and others,are facing issues as a result of the recent developments in heat transmission.Nanofluids are a novel type of heat transfer fluid that has the potential to provide solutions that will improve energy transfer.The current study investigates the effect of a magnetic field on the two-dimensional flow of Williamson nanofluid over an exponentially inclined stretched sheet.This investigation takes into account the presence of multi-slip effects.We also consider the influence of viscous dissipation,thermal radiation,chemical reactions,and suction on the fluid’s velocity.We convert the nonlinear governing partial differential equations(PDEs)of the fluid flow problem into dimensionless ordinary differential equations(ODEs)through the utilization of similarity variables.We then use the homotopy analysis method(HAM)to numerically solve the resulting ordinary differential equations(ODEs).We demonstrate the effects of numerous elements on a variety of profiles through graphical and tabular representations.We observe a drop in the velocity profile whenever we increase either the magnetic number or the suction parameter.Higher values of the Williamson parameter lead to an increase in the thermal profile,while the momentum of the flow displays a trend in the opposite direction.The potential applications of this unique model include chemical and biomolecule detection,environmental cleansing,and the initiation of radiation-induced chemical processes like polymerization,sterilization,and chemical synthesis.
基金supported by Ministry of Railway of China(Grant No.2010G006-H)
文摘Nowadays,the sleeper,railroad bed,welding technology and materials of the high-speed&heavy-load Continuous Welded Rail(CWR)have been improved greatly.However,the orientation relationship between welding surface and rail is still orientation structure,which appeared 185 years ago in UK,namely,the welding surface is normal to the longitudinal direction of the rail.Thus rail welds are subject to vertical pure shear stress,lateral pure shear stress and axial pure tensile stress.Pure shear stress and pure tensile stress are both dangerous stresses,which result in failure of welds under high-speed&heavy-load condition for a long time.When the wheels pass rail welds,it is difficult to avoid vertical bumping and lateral vibration.In order to solve these problems,in this paper we put forward the single inclined welding surface having dip angleαwith the lateral rail or dip angleβwith the vertical rail and analyze the position geometry and stress state.Thus the vertical bumping and lateral vibration are basically eliminated,then the bearing capacity of the welding surface is significantly improved,and the stress of axial pure tensile and lateral pure shear of the welding surface is reduced.
文摘This article focuses on the effect of radiation on mixed convection in a nanofluid along an inclined wavy surface embedded in a non-Darcy porous medium.A coordinate transformation is employed to transform the complex wavy surface to a smooth surface.The governing equations are transformed into a set of partial differential equations using the nonsimilarity transformation and then a local similarity and non-similarity method is applied to obtain coupled ordinary differential equations.These resulting equations are linearized using the successive linearization method and then solved by the Chebyshev spectral method.The effects of radiation,non-Darcy parameter,Brownian motion parameter,thermophoresis parameter,the amplitude of the wavy surface,angle of inclination of the wavy surface on the non-dimensional heat and nanoparticle mass transfer rates are studied and presented graphically.
