Underground utility tunnels are widely used in urban areas throughout the world for lifeline networks due to their easy maintenance and environmental protection capabilities. However, knowledge about their seismic per...Underground utility tunnels are widely used in urban areas throughout the world for lifeline networks due to their easy maintenance and environmental protection capabilities. However, knowledge about their seismic performance is still quite limited and seismic design procedures are not included in current design codes. This paper describes a series of shaking table tests the authors performed on a scaled utility tunnel model to explore its performance under earthquake excitation. Details of the experimental setup are first presented focusing on aspects such as the design of the soil container, scaled structural model, sensor array arrangement and test procedure. The main observations from the test program, including structural response, soil response, soil-structure interaction and earth pressure, are summarized and discussed. Further, a finite element model （FEM） of the test utility tunnel is established where the nonlinear soil properties are modeled by the Drucker- Prager constitutive model; the master-slave surface mechanism is employed to simulate the soil-structure dynamic interaction; and the confining effect of the laminar shear box to soil is considered by proper boundary modeling. The results from the numerical model are compared with experiment measurements in terms of displacement, acceleration and amplification factor of the structural model and the soil. The comparison shows that the numerical results match the experimental measurements quite well. The validated numerical model can be adopted for further analysis.展开更多
Both necessary and sufficient maximum principles for optimal control of stochastic systemwith random jumps consisting of forward and backward state variables are proved.The control variableis allowed to enter both dif...Both necessary and sufficient maximum principles for optimal control of stochastic systemwith random jumps consisting of forward and backward state variables are proved.The control variableis allowed to enter both diffusion and jump coefficients.The result is applied to a mean-varianceportfolio selection mixed with a recursive utility functional optimization problem.Explicit expressionof the optimal portfolio selection strategy is obtained in the state feedback form.展开更多
在借鉴SMRM解说系统规划方法基础上,提出有别于以往研究的森林公园旅游解说系统构建效用因子组合。文章选取加拿大班夫国家公园(Banff National Park)和中国张家界国家森林公园为问卷调研地,以中西方森林游憩者为受访对象,实证分析解说...在借鉴SMRM解说系统规划方法基础上,提出有别于以往研究的森林公园旅游解说系统构建效用因子组合。文章选取加拿大班夫国家公园(Banff National Park)和中国张家界国家森林公园为问卷调研地,以中西方森林游憩者为受访对象,实证分析解说因子对森林公园旅游解说的重要性。结果表明:森林公园旅游解说系统构建效用因子为解说文本、解说媒介、解说序列;中西方森林游憩者关于解说效用因子对森林公园旅游解说重要性均存在显著影响,且系数均为正数,即解说效用因子对森林公园旅游解说重要性亦均存在显著正向影响。展开更多
基金Key Project in the National Science & Technology Pillar Program Under Grant No. 2006BAJ03B03Research Fund for Young Teacher Supported by State Key Laboratory for Disaster Reduction in Civil Engineering Under Grant No. SLDRCE08-C-03
文摘Underground utility tunnels are widely used in urban areas throughout the world for lifeline networks due to their easy maintenance and environmental protection capabilities. However, knowledge about their seismic performance is still quite limited and seismic design procedures are not included in current design codes. This paper describes a series of shaking table tests the authors performed on a scaled utility tunnel model to explore its performance under earthquake excitation. Details of the experimental setup are first presented focusing on aspects such as the design of the soil container, scaled structural model, sensor array arrangement and test procedure. The main observations from the test program, including structural response, soil response, soil-structure interaction and earth pressure, are summarized and discussed. Further, a finite element model （FEM） of the test utility tunnel is established where the nonlinear soil properties are modeled by the Drucker- Prager constitutive model; the master-slave surface mechanism is employed to simulate the soil-structure dynamic interaction; and the confining effect of the laminar shear box to soil is considered by proper boundary modeling. The results from the numerical model are compared with experiment measurements in terms of displacement, acceleration and amplification factor of the structural model and the soil. The comparison shows that the numerical results match the experimental measurements quite well. The validated numerical model can be adopted for further analysis.
基金supported by the National Basic Research Program of China (973 Program) under Grant No.2007CB814904the National Natural Science Foundations of China under Grant Nos.10921101 and 10701050the Natural Science Foundation of Shandong Province under Grant Nos.JQ200801 and 2008BS01024
文摘Both necessary and sufficient maximum principles for optimal control of stochastic systemwith random jumps consisting of forward and backward state variables are proved.The control variableis allowed to enter both diffusion and jump coefficients.The result is applied to a mean-varianceportfolio selection mixed with a recursive utility functional optimization problem.Explicit expressionof the optimal portfolio selection strategy is obtained in the state feedback form.
文摘在借鉴SMRM解说系统规划方法基础上,提出有别于以往研究的森林公园旅游解说系统构建效用因子组合。文章选取加拿大班夫国家公园(Banff National Park)和中国张家界国家森林公园为问卷调研地,以中西方森林游憩者为受访对象,实证分析解说因子对森林公园旅游解说的重要性。结果表明:森林公园旅游解说系统构建效用因子为解说文本、解说媒介、解说序列;中西方森林游憩者关于解说效用因子对森林公园旅游解说重要性均存在显著影响,且系数均为正数,即解说效用因子对森林公园旅游解说重要性亦均存在显著正向影响。
