A general initial water penetration(seepage) fracture criterion for concrete is proposed to predict whether or not harmful water penetration(hydraulic fracturing),other than microcracking,will occur in concrete struct...A general initial water penetration(seepage) fracture criterion for concrete is proposed to predict whether or not harmful water penetration(hydraulic fracturing),other than microcracking,will occur in concrete structures in a severe high water pressure environment.The final regression,of the different macroscopic failure types in concrete to microscopic ModeⅠ c racking,allows the use of only one universal criterion to indicate the damage.Thus,a general initial water penetration fracture criterion is approximately defined as a strain magnitude of 1000×10-6,based on the concept of tensile strain derived from experimental results in the relevant literature.Then,the locations of harmful water penetration fracture(hydraulic fracture) in the high arch dam mass of the Jinping first class hydropower project are analyzed using the nonlinear finite element method(FEM) according to the proposed criterion.The proposed criterion also holds promise for other concrete structures in high water pressure environments.展开更多
In this study, the structure and quality controlled growth of InAs nanowires using Au catalysts in a molecular beam epitaxy reactor is presented. By tuning the indium concentration in the catalyst, defect-free wurtzit...In this study, the structure and quality controlled growth of InAs nanowires using Au catalysts in a molecular beam epitaxy reactor is presented. By tuning the indium concentration in the catalyst, defect-free wurtzite structure and defect-free zinc blende structure InAs nanowires can be induced. It is found that these defect-free zinc blende structure InAs nanowires grow along 〈110〉 directions with four low-energy {111} and two {110} side-wall facets and adopt the （111） catalyst/nanowire interface. Our structural and chemical characterization and calculations identify the existence of a catalyst supersaturation threshold for the InAs nanowire growth. When the In concentration in the catalyst is sufficiently high, defect-free zinc blende structure InAs nanowires can be induced. This study provides an insight into the manipulation of crystal structure and structure quality of III-V semiconductor nanowires through catalyst engineering.展开更多
基金supported by the National Basic Research Program of China ("973" Program) (Grant No 2007CB714104)the National Natural Science Foundation of China (Grant Nos 51079045, 50779009 and 51008114)
文摘A general initial water penetration(seepage) fracture criterion for concrete is proposed to predict whether or not harmful water penetration(hydraulic fracturing),other than microcracking,will occur in concrete structures in a severe high water pressure environment.The final regression,of the different macroscopic failure types in concrete to microscopic ModeⅠ c racking,allows the use of only one universal criterion to indicate the damage.Thus,a general initial water penetration fracture criterion is approximately defined as a strain magnitude of 1000×10-6,based on the concept of tensile strain derived from experimental results in the relevant literature.Then,the locations of harmful water penetration fracture(hydraulic fracture) in the high arch dam mass of the Jinping first class hydropower project are analyzed using the nonlinear finite element method(FEM) according to the proposed criterion.The proposed criterion also holds promise for other concrete structures in high water pressure environments.
文摘In this study, the structure and quality controlled growth of InAs nanowires using Au catalysts in a molecular beam epitaxy reactor is presented. By tuning the indium concentration in the catalyst, defect-free wurtzite structure and defect-free zinc blende structure InAs nanowires can be induced. It is found that these defect-free zinc blende structure InAs nanowires grow along 〈110〉 directions with four low-energy {111} and two {110} side-wall facets and adopt the （111） catalyst/nanowire interface. Our structural and chemical characterization and calculations identify the existence of a catalyst supersaturation threshold for the InAs nanowire growth. When the In concentration in the catalyst is sufficiently high, defect-free zinc blende structure InAs nanowires can be induced. This study provides an insight into the manipulation of crystal structure and structure quality of III-V semiconductor nanowires through catalyst engineering.
