Given the background of a transmission tower erected on a particular mining subsidence area,we used finite element modeling to analyze the anti-deformation performance of transmission towers under a number of differen...Given the background of a transmission tower erected on a particular mining subsidence area,we used finite element modeling to analyze the anti-deformation performance of transmission towers under a number of different load conditions,including horizontal foundation displacement,uneven vertical downward displacement,wind loads and icing conditions.The results show that the failure in stability of a single steel angle iron represents the limit of the tower given ground deformation.We calculated the corresponding limits of foundation displacements.The results indicate that compression displacement of the foundation is more dangerous than tension displacement.Under complex foundation displacement conditions,horizontal foundation displacement is a key factor leading to failure in the stability of towers.Under conditions of compression or tension displacement of the foundation,wind load becomes the key factor.Towers do not fail when foundation displacements are smaller than 1% (under tension) or 0.5% (under horizontal compression or single foundation subsidence) of the distance between two supports.展开更多
The theoretical relationship between water injection multiple(i.e.injected pore volume)and water saturation is inferred from theoretical concepts of reservoir engineering.A mathematical model based on core displacemen...The theoretical relationship between water injection multiple(i.e.injected pore volume)and water saturation is inferred from theoretical concepts of reservoir engineering.A mathematical model based on core displacement tests is established for the entire injection process that satisfies both initial displacement and extreme displacement,simultaneously.The results show that prior to the flooding,the water injection multiple has a linear relationship with the water saturation,and the utilization rate of the injected water is the highest.As water breakthrough at the production end,the water-cut increases,and the injection multiple increases exponentially while the utilization efficiency of the injected water gradually decreases.When the injection multiple approaches infinity,the utilization efficiency of the injected water gradually decreases to 0,by which time the water-cut at the production end is always 1.At this time,the water saturation no longer changes,and the water flooding recovery rate reaches its limit.Based on the experimental test data,a mathematical model of the entire process of injection multiple and water saturation is established,which has high fitting accuracy that can predict the injection multiple in the different stages of development of a mature oil reservoir.The dynamically changing index of the injection water utilization efficiency in reservoir development by reactive water flooding can be obtained through reasonable transformation of the mathematical model.This is of great significance in guiding evaluations of the effects of reservoir development and formulating countermeasures.展开更多
Coarse-grained(CG) metals strengthened by nanotwinned(NT) regions possess high strength and good ductility. As such, they are very suitable for applications in bullet-proof targets. Here, a numerical model based o...Coarse-grained(CG) metals strengthened by nanotwinned(NT) regions possess high strength and good ductility. As such, they are very suitable for applications in bullet-proof targets. Here, a numerical model based on the conventional theory of strain gradient plasticity and the Johnson–Cook failure criterion is employed to study the influences of volume fraction of NT regions on their ballistic performance.The results show that in general a relatively small twin spacing(4–10 nm) and a moderate volume fraction(7%–20%) will lead to excellent limit velocity and that the influences of volume fraction on limit displacement change with the category of impact processes.展开更多
基金National Natural Science Foundation of China(No.50004008)Xuzhou Power Supply Company and the Fundamental Research Funds for the Central Universities(No.2011QNB18) for their financial and technical support for this work
文摘Given the background of a transmission tower erected on a particular mining subsidence area,we used finite element modeling to analyze the anti-deformation performance of transmission towers under a number of different load conditions,including horizontal foundation displacement,uneven vertical downward displacement,wind loads and icing conditions.The results show that the failure in stability of a single steel angle iron represents the limit of the tower given ground deformation.We calculated the corresponding limits of foundation displacements.The results indicate that compression displacement of the foundation is more dangerous than tension displacement.Under complex foundation displacement conditions,horizontal foundation displacement is a key factor leading to failure in the stability of towers.Under conditions of compression or tension displacement of the foundation,wind load becomes the key factor.Towers do not fail when foundation displacements are smaller than 1% (under tension) or 0.5% (under horizontal compression or single foundation subsidence) of the distance between two supports.
文摘The theoretical relationship between water injection multiple(i.e.injected pore volume)and water saturation is inferred from theoretical concepts of reservoir engineering.A mathematical model based on core displacement tests is established for the entire injection process that satisfies both initial displacement and extreme displacement,simultaneously.The results show that prior to the flooding,the water injection multiple has a linear relationship with the water saturation,and the utilization rate of the injected water is the highest.As water breakthrough at the production end,the water-cut increases,and the injection multiple increases exponentially while the utilization efficiency of the injected water gradually decreases.When the injection multiple approaches infinity,the utilization efficiency of the injected water gradually decreases to 0,by which time the water-cut at the production end is always 1.At this time,the water saturation no longer changes,and the water flooding recovery rate reaches its limit.Based on the experimental test data,a mathematical model of the entire process of injection multiple and water saturation is established,which has high fitting accuracy that can predict the injection multiple in the different stages of development of a mature oil reservoir.The dynamically changing index of the injection water utilization efficiency in reservoir development by reactive water flooding can be obtained through reasonable transformation of the mathematical model.This is of great significance in guiding evaluations of the effects of reservoir development and formulating countermeasures.
基金supported by the National Natural Science Foundation of China(11372214)the opening project of State Key Laboratory of Explosion Science and Technology(Beijing Institute of Technology)(KFJJ17-10M)+1 种基金the support of the NSF Mechanics of Materials Program under CMMI-1162431the support from the Advanced Engineering Programme and School of Engineering,Monash University Malaysia
文摘Coarse-grained(CG) metals strengthened by nanotwinned(NT) regions possess high strength and good ductility. As such, they are very suitable for applications in bullet-proof targets. Here, a numerical model based on the conventional theory of strain gradient plasticity and the Johnson–Cook failure criterion is employed to study the influences of volume fraction of NT regions on their ballistic performance.The results show that in general a relatively small twin spacing(4–10 nm) and a moderate volume fraction(7%–20%) will lead to excellent limit velocity and that the influences of volume fraction on limit displacement change with the category of impact processes.