This paper discusses the H∞ control problem for a class of linear stochastic systems driven by both Brownian motion and Poisson jumps. The authors give the basic theory about stabilities for such systems, including i...This paper discusses the H∞ control problem for a class of linear stochastic systems driven by both Brownian motion and Poisson jumps. The authors give the basic theory about stabilities for such systems, including internal stability and external stability, which enables to prove the bounded real lemma for the systems. By means of Riccati equations, infinite horizon linear stochastic state-feedback H∞ control design is also extended to such systems.展开更多
Bridges are the most useful part in the transportation network.Any disruption of the bridge structures may hamper the whole transportation system.In the last recent tsunamis,numerous number of bridges were structurall...Bridges are the most useful part in the transportation network.Any disruption of the bridge structures may hamper the whole transportation system.In the last recent tsunamis,numerous number of bridges were structurally damaged by the tsunami waves.Lack of proper provisions of tsunami forces in the design guidelines also contributes to the augmentations of the damage level.Therefore,proper evaluation of the tsunami forces on the bridge girder should be introduced in the design promptly.In this study,laboratory experiments were carried out to reveal the damage mechanism of the bridge girder by assessing the exerted tsunami forces.Both broken and unbroken waves were considered for the analysis.The results showed that measured forces were larger for broken waves than those of unbroken waves.Maximum force of the broken waves was 4.59 times as large as the hydrostatic pressure.Also,waves reached the peak value more rapidly for larger wave heights than those of smaller ones.Additionally,a girder that is placed at a higher position is much vulnerable to tsunami hazard.展开更多
In this work,we develop a new many-body potential for alpha-hafnium(α-Hf)based on the second moment approximation of tight-binding(TB-SMA)theory by introducing an additional Heaviside step function into the potential...In this work,we develop a new many-body potential for alpha-hafnium(α-Hf)based on the second moment approximation of tight-binding(TB-SMA)theory by introducing an additional Heaviside step function into the potential model and a new analytical scheme of density function.All the parameters of the new potential have been systematically evaluated by fitting to ground-state properties including cohesive energy,lattice constants,elastic constants,vacancy formation energy,structure stability and equation of state.By using the present model,the melting point,melt heat,thermal expansion coefficient,point defects,and low-index surface energies ofα-Hf were calculated through molecular dynamics simulations.Comparing with experiment observations from others,it is shown that these properties can be reproduced reasonably by the present model,some results being more consistent to the experimental data than those by previous suggested models.This indicates that this work is sutiable in TB-SMA potential for hexagonal close packed metals.展开更多
基金supported by the National Natural Science Foundation of China under Grant Nos.60874032 and 70971079
文摘This paper discusses the H∞ control problem for a class of linear stochastic systems driven by both Brownian motion and Poisson jumps. The authors give the basic theory about stabilities for such systems, including internal stability and external stability, which enables to prove the bounded real lemma for the systems. By means of Riccati equations, infinite horizon linear stochastic state-feedback H∞ control design is also extended to such systems.
基金supported by the University of Malaya and Ministry of Education,PPP fund(Grant No.PG 029-2012B)the High Impact Research Fund(Grant Nos.H-16001-00-D000061,J-16002-00-7383000-000000)
文摘Bridges are the most useful part in the transportation network.Any disruption of the bridge structures may hamper the whole transportation system.In the last recent tsunamis,numerous number of bridges were structurally damaged by the tsunami waves.Lack of proper provisions of tsunami forces in the design guidelines also contributes to the augmentations of the damage level.Therefore,proper evaluation of the tsunami forces on the bridge girder should be introduced in the design promptly.In this study,laboratory experiments were carried out to reveal the damage mechanism of the bridge girder by assessing the exerted tsunami forces.Both broken and unbroken waves were considered for the analysis.The results showed that measured forces were larger for broken waves than those of unbroken waves.Maximum force of the broken waves was 4.59 times as large as the hydrostatic pressure.Also,waves reached the peak value more rapidly for larger wave heights than those of smaller ones.Additionally,a girder that is placed at a higher position is much vulnerable to tsunami hazard.
基金supported by the National Natural Science Foundation of China(Grant Nos.51071018 and 51271018)
文摘In this work,we develop a new many-body potential for alpha-hafnium(α-Hf)based on the second moment approximation of tight-binding(TB-SMA)theory by introducing an additional Heaviside step function into the potential model and a new analytical scheme of density function.All the parameters of the new potential have been systematically evaluated by fitting to ground-state properties including cohesive energy,lattice constants,elastic constants,vacancy formation energy,structure stability and equation of state.By using the present model,the melting point,melt heat,thermal expansion coefficient,point defects,and low-index surface energies ofα-Hf were calculated through molecular dynamics simulations.Comparing with experiment observations from others,it is shown that these properties can be reproduced reasonably by the present model,some results being more consistent to the experimental data than those by previous suggested models.This indicates that this work is sutiable in TB-SMA potential for hexagonal close packed metals.
