The soil masses of slopes were assumed to follow a nonlinear failure criterion and a nonassociated flow rule.The stability factors of slopes were calculated using vertical slice method based on limit analysis.The pote...The soil masses of slopes were assumed to follow a nonlinear failure criterion and a nonassociated flow rule.The stability factors of slopes were calculated using vertical slice method based on limit analysis.The potential sliding mass was divided into a series of vertical slices as well as the traditional slice technique.Equating the external work rate to the internal energy dissipation,the optimum solutions to stability factors were determined by the nonlinear programming algorithm.From the numerical results,it is found that the present solutions agree well with previous results when the nonlinear criterion reduces to the linear criterion,and the nonassociated flow rule reduces to the associated flow rule.The stability factors decrease by 39.7%with nonlinear parameter varying from 1.0 to 3.0.Dilation and nonlinearity have significant effects on the slope stability factors.展开更多
The half-dry cutting employs cryogenic compressed air cooled down to (10 to 40) and a micro-dosage of lubricating oil, called cryogenic cold air jet cutting was studied. On the basis of a comparative experiment on dr...The half-dry cutting employs cryogenic compressed air cooled down to (10 to 40) and a micro-dosage of lubricating oil, called cryogenic cold air jet cutting was studied. On the basis of a comparative experiment on dry and cryogenic cold air jet cuttings carried out for grade 45 steel, the effects of cryogenic cold air jet on the breaking of chips were discussed. The experimental results reveal that in the valid ranges of pressure and temperature, the cryogenic cold air jet widens the chip breaking areas effectively. When the cutting depth is not greater than 1 mm, the influence of chip breaking is much more significant. But different injecting angle of cold air has different influence on the chip-break. From the experiment, the optimized jet injecting angle, temperature effecting range and pressure working range of cold air are obtained. These results can offer a foundation for industrial manufacturing.展开更多
This paper aims to the research of the impact of fluid shear stress on the adhesion between vascular endothelial cells and leukocyte induced by tumor necrosis factor-α(TNF-α) by microfliudic chip technology.Microflu...This paper aims to the research of the impact of fluid shear stress on the adhesion between vascular endothelial cells and leukocyte induced by tumor necrosis factor-α(TNF-α) by microfliudic chip technology.Microfluidic chip was fabricated by soft lithograph; Endothelial microfluidic chip was constructed by optimizing types of the extracellular matrix proteins modified in the microchannel and cell incubation time;human umbilical vein endothelial cells EA.Hy926 lined in the microchannel were exposed to fluid shear stress of 1.68 dynes/cm^2 and 8.4 dynes/cm^2 respectively.Meanwhile,adhesion between EA.Hy926 cells and leukocyte was induced by TNF-αunder a flow condition.EA.Hy926 cell cultured in the static condition was used as control group.The numbers of fluorescently-labeled leukocyte in microchannel were counted to quantize the adhesion level between EA.Hy926 cells and leukocyte; cell immunofluorescence technique was used to detect the intercellular adhesion molecule(ICAM-1) expression.The constructed endothelial microfluidic chip can afford to the fluid shear stress and respond to exogenous stimulus of TNF-α; compared with the adhesion numbers of leukocyte in control group,adhesion between EA.Hy926 cells exposed to low fluid shear stress and leukocyte was reduced under the stimulus of TNF-α at a concentration of 10 ng/ml(P<0.05); leukocyte adhesion with EA.Hy926 cells exposed to high fluid shear stress was reduced significantly than EA.Hy926 cells in control group and EA.1Hy926 cells exposed to low fluid shear stress(P<0.01); the regulation mechanism of fluid shear stress to the adhesion between EA.Hy926 cells and leukocyte induced by TNF-αwas through the way of ICAM-1.The endothelial microfluidic chip fabricated in this paper could be used to study the functions of endothelial cell in vitro and provide a new technical platform for exploring the pathophysiology of the related cardiovascular system diseases under a flow environment.展开更多
基金Project(200550)supported by the Foundation for the Author of National Excellent Doctoral Dissertation of ChinaProject(200631878557)supported by West Traffic of Science and Technology of China
文摘The soil masses of slopes were assumed to follow a nonlinear failure criterion and a nonassociated flow rule.The stability factors of slopes were calculated using vertical slice method based on limit analysis.The potential sliding mass was divided into a series of vertical slices as well as the traditional slice technique.Equating the external work rate to the internal energy dissipation,the optimum solutions to stability factors were determined by the nonlinear programming algorithm.From the numerical results,it is found that the present solutions agree well with previous results when the nonlinear criterion reduces to the linear criterion,and the nonassociated flow rule reduces to the associated flow rule.The stability factors decrease by 39.7%with nonlinear parameter varying from 1.0 to 3.0.Dilation and nonlinearity have significant effects on the slope stability factors.
文摘The half-dry cutting employs cryogenic compressed air cooled down to (10 to 40) and a micro-dosage of lubricating oil, called cryogenic cold air jet cutting was studied. On the basis of a comparative experiment on dry and cryogenic cold air jet cuttings carried out for grade 45 steel, the effects of cryogenic cold air jet on the breaking of chips were discussed. The experimental results reveal that in the valid ranges of pressure and temperature, the cryogenic cold air jet widens the chip breaking areas effectively. When the cutting depth is not greater than 1 mm, the influence of chip breaking is much more significant. But different injecting angle of cold air has different influence on the chip-break. From the experiment, the optimized jet injecting angle, temperature effecting range and pressure working range of cold air are obtained. These results can offer a foundation for industrial manufacturing.
文摘This paper aims to the research of the impact of fluid shear stress on the adhesion between vascular endothelial cells and leukocyte induced by tumor necrosis factor-α(TNF-α) by microfliudic chip technology.Microfluidic chip was fabricated by soft lithograph; Endothelial microfluidic chip was constructed by optimizing types of the extracellular matrix proteins modified in the microchannel and cell incubation time;human umbilical vein endothelial cells EA.Hy926 lined in the microchannel were exposed to fluid shear stress of 1.68 dynes/cm^2 and 8.4 dynes/cm^2 respectively.Meanwhile,adhesion between EA.Hy926 cells and leukocyte was induced by TNF-αunder a flow condition.EA.Hy926 cell cultured in the static condition was used as control group.The numbers of fluorescently-labeled leukocyte in microchannel were counted to quantize the adhesion level between EA.Hy926 cells and leukocyte; cell immunofluorescence technique was used to detect the intercellular adhesion molecule(ICAM-1) expression.The constructed endothelial microfluidic chip can afford to the fluid shear stress and respond to exogenous stimulus of TNF-α; compared with the adhesion numbers of leukocyte in control group,adhesion between EA.Hy926 cells exposed to low fluid shear stress and leukocyte was reduced under the stimulus of TNF-α at a concentration of 10 ng/ml(P<0.05); leukocyte adhesion with EA.Hy926 cells exposed to high fluid shear stress was reduced significantly than EA.Hy926 cells in control group and EA.1Hy926 cells exposed to low fluid shear stress(P<0.01); the regulation mechanism of fluid shear stress to the adhesion between EA.Hy926 cells and leukocyte induced by TNF-αwas through the way of ICAM-1.The endothelial microfluidic chip fabricated in this paper could be used to study the functions of endothelial cell in vitro and provide a new technical platform for exploring the pathophysiology of the related cardiovascular system diseases under a flow environment.
