This work investigates the flow of a third grade fluid in a rotating frame of reference. The fluid is incompressible and magnetohydrodynamic （MHD）. The flow is bounded between two porous plates, the lower of which i...This work investigates the flow of a third grade fluid in a rotating frame of reference. The fluid is incompressible and magnetohydrodynamic （MHD）. The flow is bounded between two porous plates, the lower of which is shrinking linearly. Mathematical modelling of the considered flow leads to a nonlinear problem. The solution of this nonlinear problem is computed by the homotopy analysis method （HAM）. Graphs are presented to demonstrate the effect of several emerging parameters, which clearly describe the flow characteristics.展开更多
The present study aims to make a thermodynamic analysis of an ethylene cascade re-liquefaction system that consists of the following two subsystems: a liquefaction cycle using ethylene as the working fluid and a refri...The present study aims to make a thermodynamic analysis of an ethylene cascade re-liquefaction system that consists of the following two subsystems: a liquefaction cycle using ethylene as the working fluid and a refrigeration cycle operating with a hydrocarbon refrigerant. The hydrocarbon refrigerants considered are propane(R290), butane(R600), isobutane(R600a), and propylene(R1270). A computer program written in FORTRAN is developed to compute parameters for characteristic points of the cycles and the system's performance, which is determined and analyzed using numerical solutions for the refrigerant condensation temperature, temperature in tank, and temperature difference in the cascade condenser. Results show that R600 a gives the best performance, followed by(in order) R600, R290, and R1270. Furthermore, it is found that an increase in tank temperature improves system performance but that an increase in refrigerant condensation temperature causes deterioration. In addition, it is found that running the system at a low temperature difference in the cascade condenser is advantageous.展开更多
The recrystallization texture evolution in heavily cold-rolled （93%） FeCo-2V alloy with annealing temperature and time was investigated by X-ray diffraction and electron backscatter diffraction. It was found that th...The recrystallization texture evolution in heavily cold-rolled （93%） FeCo-2V alloy with annealing temperature and time was investigated by X-ray diffraction and electron backscatter diffraction. It was found that the orientation density of α-fiber texture component fluctuates with increasing annealing temperature and time. The transmission electron microscopy images show that abundant precipitates appear inside the recrystallized grains and around the grain boundaries. The amount and size of the precipitates also vary with annealing temperature and time. The enhancement of the α-fiber coincides well with the increase of number density of fine precipitates, indicating that the fine precipitates facilitate the development of α-fiber. The annealing texture evolution observed in the FeCo alloy could be attributed to the facilitating effect of the precipitates on the development of α-fiber and the ordering process.展开更多
The tribological behavior of the CoCr28Mo/CoCr28Mo pair was studied using pin-on-disc tribometer. Four bio-lubricants were re- tained including pure sesame oil, nigella oil, physiological solution （0.9% NaC1） and Hy...The tribological behavior of the CoCr28Mo/CoCr28Mo pair was studied using pin-on-disc tribometer. Four bio-lubricants were re- tained including pure sesame oil, nigella oil, physiological solution （0.9% NaC1） and Hyalgan. Hyalgan is a sodium hyaluronate （20 mg/2 mL） pharmaceutical intra-articular injection used, in this study, as a reference. The Coefficient of Friction （CoF） and wear rate （K） of CoCr28Mo were computed after tribological tests. The tribological efficiency of vegetable oils with regard to their chemical compo- sition and structure was compared to Hyalgan. It is found that, the use of vegetable oils enhanced significantly the tribological behavior of CoCr28Mo/CoCr28Mo pair. The obtained results were correlated to the chemical structure of vegetable oils namely the Unsaturations Number （UN） of fatty acids constituting the oil. Microscopic and chemical characterization of CoCr28Mo pins and discs were conducted and the wear mechanism was discussed.展开更多
In this study,an experimental analysis for determining the fatigue strength of HDPE-100 under cyclic loading is presented.The curve of cumulative fatigue damage versus number of cycles（D-N） was deduced from stiffnes...In this study,an experimental analysis for determining the fatigue strength of HDPE-100 under cyclic loading is presented.The curve of cumulative fatigue damage versus number of cycles（D-N） was deduced from stiffness degradation.Based on the three stage damage trend,the remaining fatigue life is numerically predicted by considering a double term power damage accumulation model.This model is found to be accurate,both in modeling the rapid damage growth in the early life and near the end of the fatigue life.Numerical results illustrate that the proposed model is capable of accurately fitting several different sets of experimental data.展开更多
In this paper,the tribological properties of cuttlebone(CB)-reinforced high density polyethylene(HDPE)and Red Coral(RC)-reinfbrced HDPE composites were investigated.The composite specimens were prepared with a hot com...In this paper,the tribological properties of cuttlebone(CB)-reinforced high density polyethylene(HDPE)and Red Coral(RC)-reinfbrced HDPE composites were investigated.The composite specimens were prepared with a hot compression molding machine using different weight proportions of fillers blended with HDPE.The tribological behavior of the composite disks was studied using pin-on-disk tribometer under dry condition against stainless steel M30NW pins.The coefficient of friction as well as wear rate were examined to study the effects of the two fillers on the tribological perfonnance of both composites.After wear tests,different composites were examined using a Scanning Electron Microscope(SEM).It was fbund that the use of cuttlebone(CB)and Red Coral(RC)as reinforcement improved the tribological properties of HDPE.展开更多
文摘This work investigates the flow of a third grade fluid in a rotating frame of reference. The fluid is incompressible and magnetohydrodynamic （MHD）. The flow is bounded between two porous plates, the lower of which is shrinking linearly. Mathematical modelling of the considered flow leads to a nonlinear problem. The solution of this nonlinear problem is computed by the homotopy analysis method （HAM）. Graphs are presented to demonstrate the effect of several emerging parameters, which clearly describe the flow characteristics.
文摘The present study aims to make a thermodynamic analysis of an ethylene cascade re-liquefaction system that consists of the following two subsystems: a liquefaction cycle using ethylene as the working fluid and a refrigeration cycle operating with a hydrocarbon refrigerant. The hydrocarbon refrigerants considered are propane(R290), butane(R600), isobutane(R600a), and propylene(R1270). A computer program written in FORTRAN is developed to compute parameters for characteristic points of the cycles and the system's performance, which is determined and analyzed using numerical solutions for the refrigerant condensation temperature, temperature in tank, and temperature difference in the cascade condenser. Results show that R600 a gives the best performance, followed by(in order) R600, R290, and R1270. Furthermore, it is found that an increase in tank temperature improves system performance but that an increase in refrigerant condensation temperature causes deterioration. In addition, it is found that running the system at a low temperature difference in the cascade condenser is advantageous.
基金support by the Na-tional Natural Science Foundation of China (Grant Nos.50471026 and 50725102) the Swedish Research Coun-cil in the frame of the SIDA project (Grant No. 348-2004-3475).
文摘The recrystallization texture evolution in heavily cold-rolled （93%） FeCo-2V alloy with annealing temperature and time was investigated by X-ray diffraction and electron backscatter diffraction. It was found that the orientation density of α-fiber texture component fluctuates with increasing annealing temperature and time. The transmission electron microscopy images show that abundant precipitates appear inside the recrystallized grains and around the grain boundaries. The amount and size of the precipitates also vary with annealing temperature and time. The enhancement of the α-fiber coincides well with the increase of number density of fine precipitates, indicating that the fine precipitates facilitate the development of α-fiber. The annealing texture evolution observed in the FeCo alloy could be attributed to the facilitating effect of the precipitates on the development of α-fiber and the ordering process.
文摘The tribological behavior of the CoCr28Mo/CoCr28Mo pair was studied using pin-on-disc tribometer. Four bio-lubricants were re- tained including pure sesame oil, nigella oil, physiological solution （0.9% NaC1） and Hyalgan. Hyalgan is a sodium hyaluronate （20 mg/2 mL） pharmaceutical intra-articular injection used, in this study, as a reference. The Coefficient of Friction （CoF） and wear rate （K） of CoCr28Mo were computed after tribological tests. The tribological efficiency of vegetable oils with regard to their chemical compo- sition and structure was compared to Hyalgan. It is found that, the use of vegetable oils enhanced significantly the tribological behavior of CoCr28Mo/CoCr28Mo pair. The obtained results were correlated to the chemical structure of vegetable oils namely the Unsaturations Number （UN） of fatty acids constituting the oil. Microscopic and chemical characterization of CoCr28Mo pins and discs were conducted and the wear mechanism was discussed.
文摘In this study,an experimental analysis for determining the fatigue strength of HDPE-100 under cyclic loading is presented.The curve of cumulative fatigue damage versus number of cycles（D-N） was deduced from stiffness degradation.Based on the three stage damage trend,the remaining fatigue life is numerically predicted by considering a double term power damage accumulation model.This model is found to be accurate,both in modeling the rapid damage growth in the early life and near the end of the fatigue life.Numerical results illustrate that the proposed model is capable of accurately fitting several different sets of experimental data.
文摘In this paper,the tribological properties of cuttlebone(CB)-reinforced high density polyethylene(HDPE)and Red Coral(RC)-reinfbrced HDPE composites were investigated.The composite specimens were prepared with a hot compression molding machine using different weight proportions of fillers blended with HDPE.The tribological behavior of the composite disks was studied using pin-on-disk tribometer under dry condition against stainless steel M30NW pins.The coefficient of friction as well as wear rate were examined to study the effects of the two fillers on the tribological perfonnance of both composites.After wear tests,different composites were examined using a Scanning Electron Microscope(SEM).It was fbund that the use of cuttlebone(CB)and Red Coral(RC)as reinforcement improved the tribological properties of HDPE.
