Heliostats are sensitive to the wind load, thus as a key indicator, the study on the static and dynamic stability bearing capacity for heliostats is very important. In this work, a numerical wind tunnel was establishe...Heliostats are sensitive to the wind load, thus as a key indicator, the study on the static and dynamic stability bearing capacity for heliostats is very important. In this work, a numerical wind tunnel was established to calculate the wind load coefficients in various survival stow positions. In order to explore the best survival stow position for the heliostat under the strong wind, eigenvalue buckling analysis method was introduced to predict the critical wind load theoretically. Considering the impact of the nonlinearity and initial geometrical imperfection, the nonlinear post-buckling behaviors of the heliostat were investigated by load-displacement curves in the full equilibrium process. Eventually, combining B-R criterion with equivalent displacement principle the dynamic critical wind speed and load amplitude coefficient were evaluated. The results show that the determination for the best survival stow position is too hasty just by the wind load coefficients. The geometric nonlinearity has a great effect on the stability bearing capacity of the heliostat, while the effects of the material nonlinearity and initial geometrical imperfection are relatively small. And the heliostat is insensitive to the initial geometrical imperfection. In addition, the heliostat has the highest safety factor for wind-resistant performance in the stow position of 90-90 which can be taken as the best survival stow position. In this case, the extreme survival wind speeds for the static and dynamic stability are 150 m/s and 36 m/s, respectively.展开更多
From June to July of 2017, the approval rates of the Abe administration fell sharply, in stark contrast to the long-term stability since 2012. The stability of Abe＇ s approval rates originated from the people＇ s neg...From June to July of 2017, the approval rates of the Abe administration fell sharply, in stark contrast to the long-term stability since 2012. The stability of Abe＇ s approval rates originated from the people＇ s negative support for him and their opposition to the Security Laws and other important events as well as the scandals under his administration. The opposition and negative support originated from the people＇s ＂acquired helplessness＂, ＂Abenomics＂, the sharp drop in the opporttmity costs of voting and other conditions. The sudden fall of Abe＇ s approval rates was not due to the change in the aforementioned conditions, rather because of the collapse of his image including personality owing to Abe＇ s perceived arrogance and his estrangement with the people. In the context of the temporary stabilization of approval rates, Abe dissolved the House of Representatives ahead of schedule and held a general election, taking full advantage of the internal strife between the opposition parties, to achieve his goal of ruling until the 2020 Tokyo Olympics. His victory in the recent election does not accurately demonstrate that Abe is completely immune to negative impact, thus he will to use the Korean Peninsula crisis and other issues to demonstrate his ability of safeguarding Japan＇s security, seek reconstruction of his image, and further enhance his approval rate to stabilize his administration.展开更多
Sparse optimization has witnessed advancements in recent decades,and the step function finds extensive applications across various machine learning and signal processing domains.This paper integrates zero norm and the...Sparse optimization has witnessed advancements in recent decades,and the step function finds extensive applications across various machine learning and signal processing domains.This paper integrates zero norm and the step function to formulate a doublesparsity constrained optimization problem,wherein a linear equality constraint is also taken into consideration.By defining aτ-Lagrangian stationary point and a KKT point,we establish the first-order and second-order necessary and sufficient optimality conditions for the problem.Furthermore,we thoroughly elucidate their relationships to local and global optimal solutions.Finally,special cases and examples are presented to illustrate the obtained theorems.展开更多
基金Project(CYB14010)supported by Chongqing Graduate Student Research Innovation Project,ChinaProject(51405209)supported by the National Natural Science Foundation of China
文摘Heliostats are sensitive to the wind load, thus as a key indicator, the study on the static and dynamic stability bearing capacity for heliostats is very important. In this work, a numerical wind tunnel was established to calculate the wind load coefficients in various survival stow positions. In order to explore the best survival stow position for the heliostat under the strong wind, eigenvalue buckling analysis method was introduced to predict the critical wind load theoretically. Considering the impact of the nonlinearity and initial geometrical imperfection, the nonlinear post-buckling behaviors of the heliostat were investigated by load-displacement curves in the full equilibrium process. Eventually, combining B-R criterion with equivalent displacement principle the dynamic critical wind speed and load amplitude coefficient were evaluated. The results show that the determination for the best survival stow position is too hasty just by the wind load coefficients. The geometric nonlinearity has a great effect on the stability bearing capacity of the heliostat, while the effects of the material nonlinearity and initial geometrical imperfection are relatively small. And the heliostat is insensitive to the initial geometrical imperfection. In addition, the heliostat has the highest safety factor for wind-resistant performance in the stow position of 90-90 which can be taken as the best survival stow position. In this case, the extreme survival wind speeds for the static and dynamic stability are 150 m/s and 36 m/s, respectively.
文摘From June to July of 2017, the approval rates of the Abe administration fell sharply, in stark contrast to the long-term stability since 2012. The stability of Abe＇ s approval rates originated from the people＇ s negative support for him and their opposition to the Security Laws and other important events as well as the scandals under his administration. The opposition and negative support originated from the people＇s ＂acquired helplessness＂, ＂Abenomics＂, the sharp drop in the opporttmity costs of voting and other conditions. The sudden fall of Abe＇ s approval rates was not due to the change in the aforementioned conditions, rather because of the collapse of his image including personality owing to Abe＇ s perceived arrogance and his estrangement with the people. In the context of the temporary stabilization of approval rates, Abe dissolved the House of Representatives ahead of schedule and held a general election, taking full advantage of the internal strife between the opposition parties, to achieve his goal of ruling until the 2020 Tokyo Olympics. His victory in the recent election does not accurately demonstrate that Abe is completely immune to negative impact, thus he will to use the Korean Peninsula crisis and other issues to demonstrate his ability of safeguarding Japan＇s security, seek reconstruction of his image, and further enhance his approval rate to stabilize his administration.
基金Supported by the National Key R&D Program of China(No.2023YFA1011100)NSFC(No.12131004)。
文摘Sparse optimization has witnessed advancements in recent decades,and the step function finds extensive applications across various machine learning and signal processing domains.This paper integrates zero norm and the step function to formulate a doublesparsity constrained optimization problem,wherein a linear equality constraint is also taken into consideration.By defining aτ-Lagrangian stationary point and a KKT point,we establish the first-order and second-order necessary and sufficient optimality conditions for the problem.Furthermore,we thoroughly elucidate their relationships to local and global optimal solutions.Finally,special cases and examples are presented to illustrate the obtained theorems.
