Flow behaviors of spray forming low solvus high refractory (LSHR) alloy were investigated using hot compression tests performed on a Gleeble?3500 thermal mechanical simulator at temperatures of 1020?1150 °C and s...Flow behaviors of spray forming low solvus high refractory (LSHR) alloy were investigated using hot compression tests performed on a Gleeble?3500 thermal mechanical simulator at temperatures of 1020?1150 °C and strain rates of 0.0003?1.0 s?1. The constitutive equation was established, power dissipation (η) maps and hot processing maps were plotted. The microstructure evolution and dislocation distribution of domains with different values of η in power dissipation maps were also observed. The results show that the flow stress increases with decreasing temperature and increasing strain rate. The activation energy of the spray forming LSHR alloy is 1243.86 kJ/mol. When the value of η is 0.36 at the strain of 0.5, the domain in the processing map shows characteristics of typical dynamic recrystallization (DRX) and low dislocation density. According to the microstructure evolution and processing maps, the optimum processing condition for good hot workability of spray forming LSHR alloy can be summed up as:temperature range 1110?1150 °C; strain rate range 0.01?0.3 s?1.展开更多
The optimization of micro milling electrical discharge machining（EDM） process parameters of Inconel 718 alloy to achieve multiple performance characteristics such as low electrode wear,high material removal rate and...The optimization of micro milling electrical discharge machining（EDM） process parameters of Inconel 718 alloy to achieve multiple performance characteristics such as low electrode wear,high material removal rate and low working gap was investigated by the Grey-Taguchi method.The influences of peak current,pulse on-time,pulse off-time and spark gap on electrode wear（EW）,material removal rate（MRR） and working gap（WG） in the micro milling electrical discharge machining of Inconel 718 were analyzed.The experimental results show that the electrode wear decreases from 5.6×10-9 to 5.2×10-9 mm3/min,the material removal rate increases from 0.47×10-8 to 1.68×10-8 mm3/min,and the working gap decreases from 1.27 to 1.19 μm under optimal micro milling electrical discharge machining process parameters.Hence,it is clearly shown that multiple performance characteristics can be improved by using the Grey-Taguchi method.展开更多
This exploration examines unsteady magnetohydrodynamic(MHD) three-dimensional flow of viscous material between rotating plates subject to radiation,Joule heating and chemical reaction.The non-linear partial differenti...This exploration examines unsteady magnetohydrodynamic(MHD) three-dimensional flow of viscous material between rotating plates subject to radiation,Joule heating and chemical reaction.The non-linear partial differential system is re-structured into the ordinary differential expressions by the implication of appropriate transformations.The developed differential equations are computed by homotopy analysis technique.Numerical consequences have been accomplished by various values of emerging parameters.Coefficients of skin friction and heat and mass transfer rates have been scrutinized.Irreversibility analysis is carried out.Influence of various prominent variables on entropy generation is presented.Moreover,the temperature increases for higher Dufour number and concentration distribution reduces against Soret number.Higher squeezing parameter enhances velocity while concentration reduces with an increment in squeezing parameter.Both entropy rate and Bejan number increase against higher diffusion parameter.展开更多
The influences of soil dilatancy angle on three-dimensional （3D） seismic stability of locally-loaded slopes in nonassociated flow rule materials were investigated using a new rotational collapse mechanism and quasi-...The influences of soil dilatancy angle on three-dimensional （3D） seismic stability of locally-loaded slopes in nonassociated flow rule materials were investigated using a new rotational collapse mechanism and quasi-static coefficient concept. Extended Bishop method and Boussinesq theorem were employed to establish the stress distribution along the rupture surfaces that are required to obtain the rate of internal energy dissipation for the nonassociated flow rule materials in rotational collapse mechanisms. Good agreement was observed by comparing the current results with those obtained using the translational or rotational mechanisms and numerical finite difference method. The results indicate that the seismic stability of slopes reduces by decreasing the dilatancy angle for nonassociated flow rule materials. The amount of the mentioned decrease is more significant in the case of mild slopes in frictional soils. A nearly infinite slope under local loading, whether its critical failure surface is 2D or 3D, not only depends on the magnitude of the external load, but also depends on the dilataney angle of soil and the coefficient of seismic load.展开更多
Hilly or mountainous terrain occupies around 12% of the area of Bangladesh.Natural resources associated with Bangladesh's hill are forest resources,biodiversity,minerals,and agricultural crops.Natural resources ha...Hilly or mountainous terrain occupies around 12% of the area of Bangladesh.Natural resources associated with Bangladesh's hill are forest resources,biodiversity,minerals,and agricultural crops.Natural resources have been exploited in the recent four decades due to excessive clearing of hill forest cover,resulting in loss of species richness, impacts related to increased water flow variability, increased hill slope erosion and flooding intensity, and a gradual decrease in the extent of hill area in Bangladesh.This review explores the major causes and effects of depletion of natural resources by linking drivers,pressures and the related impacts.A review has been conducted to structure the effects on the hilly areas and describe the responses to minimize them in the associated DPSIR framework.Population growth has been identified as a major driver contributing to high deforestation rates.This may negatively effect agricultural productivity and increase the frequency of serious flooding.Slash and burn cultivation also impacts the regeneration of evergreen forests,which may accelerate soil erosion. Due to this and other factors,local people are facing a deficits of natural resources(food,fodder,fuel wood and water),which exacerbates the effects of poverty. Future research should try to facilitate decision making for sustainable utilization of natural resources management in the hilly areas of Bangladesh. Additional conservation measures should be developed to increase the resilience of ecosystems at national and regional levels.展开更多
The present article has been fine-tuned with the investigation of mixed convection Darcy-Forchheimer flow of ZnO-SAE50 oil nanolubricant over an inclined rotating disk under the influence of uniform applied magnetic f...The present article has been fine-tuned with the investigation of mixed convection Darcy-Forchheimer flow of ZnO-SAE50 oil nanolubricant over an inclined rotating disk under the influence of uniform applied magnetic field applied to various industries.The current study has been enriched with additional consideration of slip flow,thermal radiation,viscous dissipation,Joulian dissipation and internal heating.In view of augmentation of thermal conductivity of nanolubricant,a new micro-nano-convection model namely Patel model has been invoked.The specialty of this model involves the effects of specific surface area and nano-convection due to Brownian motion of nanoparticles,kinetic theory based micro-convection,liquid layering and particle concentration.Suitably transformed governing equations have been solved numerically by using Runge-Kutta-Fehlberg scheme.An analysis of the present study has shown that applied magnetic field,porosity of the medium,velocity slip and inertia coefficient account for the slowing down of radial as well as tangential flow of ZnO-SAE50 oil nanolubricant,thereby leading to an improvement in velocity and thermal boundary layers.展开更多
An induction motor with its speed modulated by frequency features wide transfer speed range, high systematie efficiency, simple structure and long life, and it therefore becomes one of the best driving motors used in ...An induction motor with its speed modulated by frequency features wide transfer speed range, high systematie efficiency, simple structure and long life, and it therefore becomes one of the best driving motors used in electrical vehicles. The present research trend of it is high power, high speed, high efficiency and long life. How to meet the above requirements by using the electromagnetic design, structure design and beat design, becomes a matter that needs to be resolved now. In this paper, the characters of the motor in operation are analyzed, all kinds of factors that relate to life are laid out, its heating and loss are discussed and analyzed. The key reasons affecting the motor life are presented, and different characters of a high induction motor are compared with these of a general induction motor. A design idea is described, that is : we should consider how to improve the efficiency and reliability as well as bow to reduce the heating by changing the electromagnet, structure, dissipation and operation of the motor. How to reduce its losses and to improve its dissipation has been presented in the paper.展开更多
基金Project(51301143)supported by the National Natural Science Foundation of ChinaProject(2014M560727)supported by the National Postdoctoral Foundation of China+1 种基金Project(2015GZ0228)supported by the Sichuan Province Science-Technology Support Plan,ChinaProject(2682014CX001)supported by the Science and Technology Innovation Project of SWJTU University,China
文摘Flow behaviors of spray forming low solvus high refractory (LSHR) alloy were investigated using hot compression tests performed on a Gleeble?3500 thermal mechanical simulator at temperatures of 1020?1150 °C and strain rates of 0.0003?1.0 s?1. The constitutive equation was established, power dissipation (η) maps and hot processing maps were plotted. The microstructure evolution and dislocation distribution of domains with different values of η in power dissipation maps were also observed. The results show that the flow stress increases with decreasing temperature and increasing strain rate. The activation energy of the spray forming LSHR alloy is 1243.86 kJ/mol. When the value of η is 0.36 at the strain of 0.5, the domain in the processing map shows characteristics of typical dynamic recrystallization (DRX) and low dislocation density. According to the microstructure evolution and processing maps, the optimum processing condition for good hot workability of spray forming LSHR alloy can be summed up as:temperature range 1110?1150 °C; strain rate range 0.01?0.3 s?1.
文摘The optimization of micro milling electrical discharge machining（EDM） process parameters of Inconel 718 alloy to achieve multiple performance characteristics such as low electrode wear,high material removal rate and low working gap was investigated by the Grey-Taguchi method.The influences of peak current,pulse on-time,pulse off-time and spark gap on electrode wear（EW）,material removal rate（MRR） and working gap（WG） in the micro milling electrical discharge machining of Inconel 718 were analyzed.The experimental results show that the electrode wear decreases from 5.6×10-9 to 5.2×10-9 mm3/min,the material removal rate increases from 0.47×10-8 to 1.68×10-8 mm3/min,and the working gap decreases from 1.27 to 1.19 μm under optimal micro milling electrical discharge machining process parameters.Hence,it is clearly shown that multiple performance characteristics can be improved by using the Grey-Taguchi method.
文摘This exploration examines unsteady magnetohydrodynamic(MHD) three-dimensional flow of viscous material between rotating plates subject to radiation,Joule heating and chemical reaction.The non-linear partial differential system is re-structured into the ordinary differential expressions by the implication of appropriate transformations.The developed differential equations are computed by homotopy analysis technique.Numerical consequences have been accomplished by various values of emerging parameters.Coefficients of skin friction and heat and mass transfer rates have been scrutinized.Irreversibility analysis is carried out.Influence of various prominent variables on entropy generation is presented.Moreover,the temperature increases for higher Dufour number and concentration distribution reduces against Soret number.Higher squeezing parameter enhances velocity while concentration reduces with an increment in squeezing parameter.Both entropy rate and Bejan number increase against higher diffusion parameter.
文摘The influences of soil dilatancy angle on three-dimensional （3D） seismic stability of locally-loaded slopes in nonassociated flow rule materials were investigated using a new rotational collapse mechanism and quasi-static coefficient concept. Extended Bishop method and Boussinesq theorem were employed to establish the stress distribution along the rupture surfaces that are required to obtain the rate of internal energy dissipation for the nonassociated flow rule materials in rotational collapse mechanisms. Good agreement was observed by comparing the current results with those obtained using the translational or rotational mechanisms and numerical finite difference method. The results indicate that the seismic stability of slopes reduces by decreasing the dilatancy angle for nonassociated flow rule materials. The amount of the mentioned decrease is more significant in the case of mild slopes in frictional soils. A nearly infinite slope under local loading, whether its critical failure surface is 2D or 3D, not only depends on the magnitude of the external load, but also depends on the dilataney angle of soil and the coefficient of seismic load.
文摘Hilly or mountainous terrain occupies around 12% of the area of Bangladesh.Natural resources associated with Bangladesh's hill are forest resources,biodiversity,minerals,and agricultural crops.Natural resources have been exploited in the recent four decades due to excessive clearing of hill forest cover,resulting in loss of species richness, impacts related to increased water flow variability, increased hill slope erosion and flooding intensity, and a gradual decrease in the extent of hill area in Bangladesh.This review explores the major causes and effects of depletion of natural resources by linking drivers,pressures and the related impacts.A review has been conducted to structure the effects on the hilly areas and describe the responses to minimize them in the associated DPSIR framework.Population growth has been identified as a major driver contributing to high deforestation rates.This may negatively effect agricultural productivity and increase the frequency of serious flooding.Slash and burn cultivation also impacts the regeneration of evergreen forests,which may accelerate soil erosion. Due to this and other factors,local people are facing a deficits of natural resources(food,fodder,fuel wood and water),which exacerbates the effects of poverty. Future research should try to facilitate decision making for sustainable utilization of natural resources management in the hilly areas of Bangladesh. Additional conservation measures should be developed to increase the resilience of ecosystems at national and regional levels.
文摘The present article has been fine-tuned with the investigation of mixed convection Darcy-Forchheimer flow of ZnO-SAE50 oil nanolubricant over an inclined rotating disk under the influence of uniform applied magnetic field applied to various industries.The current study has been enriched with additional consideration of slip flow,thermal radiation,viscous dissipation,Joulian dissipation and internal heating.In view of augmentation of thermal conductivity of nanolubricant,a new micro-nano-convection model namely Patel model has been invoked.The specialty of this model involves the effects of specific surface area and nano-convection due to Brownian motion of nanoparticles,kinetic theory based micro-convection,liquid layering and particle concentration.Suitably transformed governing equations have been solved numerically by using Runge-Kutta-Fehlberg scheme.An analysis of the present study has shown that applied magnetic field,porosity of the medium,velocity slip and inertia coefficient account for the slowing down of radial as well as tangential flow of ZnO-SAE50 oil nanolubricant,thereby leading to an improvement in velocity and thermal boundary layers.
文摘An induction motor with its speed modulated by frequency features wide transfer speed range, high systematie efficiency, simple structure and long life, and it therefore becomes one of the best driving motors used in electrical vehicles. The present research trend of it is high power, high speed, high efficiency and long life. How to meet the above requirements by using the electromagnetic design, structure design and beat design, becomes a matter that needs to be resolved now. In this paper, the characters of the motor in operation are analyzed, all kinds of factors that relate to life are laid out, its heating and loss are discussed and analyzed. The key reasons affecting the motor life are presented, and different characters of a high induction motor are compared with these of a general induction motor. A design idea is described, that is : we should consider how to improve the efficiency and reliability as well as bow to reduce the heating by changing the electromagnet, structure, dissipation and operation of the motor. How to reduce its losses and to improve its dissipation has been presented in the paper.
