In China,gravity retaining walls are widely used as protection structures against rockfalls,debris flows and debris avalanches along the roads in mountainous areas.In this paper,the Discrete Element Method(DEM) has be...In China,gravity retaining walls are widely used as protection structures against rockfalls,debris flows and debris avalanches along the roads in mountainous areas.In this paper,the Discrete Element Method(DEM) has been used to investigate the impact of granular avalanches and debris flows on retaining walls.The debris is modeled as two dimensional circular disks that interact through frictional sliding contacts.The basic equations that control the deformation and motion of the particles are introduced.A series of numerical experiments were conducted on an idealized debris slide impacting a retaining wall.The parametric study has been performed to examine the influences of slope geometry,travel distance of the sliding mass,wall position,and surface friction on the impact force exerted on the wall.Results show that:1) the force achieves its maximum value when slope angle is equal to 60°,as it varies from 30° to 75°;2) an approximate linear relationship between the impact force and the storage area length is determined.展开更多
Fog computing is a new paradigm supporting the stringent requirements of mobility applications by bridging cloud computing and smart devices. Since the smart devices may be deployed in dynamic areas where are out of s...Fog computing is a new paradigm supporting the stringent requirements of mobility applications by bridging cloud computing and smart devices. Since the smart devices may be deployed in dynamic areas where are out of strict monitoring and protection, fog computing requires security protections to ensure confidentiality and integrity. In this article, to deal with security requirements and considering the distinctive features, a key management based on hypergraph schemed is designed. Firstly, based on the key hypergraph, the three hierarchy architecture of fog computing is divided into two subnetworks. Furthermore, each key management process of both two subnetworks is designed to satisfy the operational and security requirements of fog computing. Finally, the performance evaluation and numerical simulation have been provided to validate the proposed scheme.展开更多
This paper mainly uses the method of numerical simulation, and study thermal insulation and energy saving characteristics on the exterior walls of the building and analyze the optimal layout scheme of building exterio...This paper mainly uses the method of numerical simulation, and study thermal insulation and energy saving characteristics on the exterior walls of the building and analyze the optimal layout scheme of building exterior wall and thermal insulation system. Finally, the paper study optimal thickness of insulation materials. The paper elaborate scheme of the existing building energy-saving for exterior wall and the scope of application, the system structure and the construction technology. The results showed that： extruded benzene board that can be used for exterior insulation, frame structure filled with wall preferred ceramsite hollow block. The paper can provides reference selection of insulation for building external wall energy-saving transformation scheme.展开更多
基金support from the 973 Program of China (Grant No. 2008CB425803)the West Light Foundation of the CAS (Grant No. 09R2200200)
文摘In China,gravity retaining walls are widely used as protection structures against rockfalls,debris flows and debris avalanches along the roads in mountainous areas.In this paper,the Discrete Element Method(DEM) has been used to investigate the impact of granular avalanches and debris flows on retaining walls.The debris is modeled as two dimensional circular disks that interact through frictional sliding contacts.The basic equations that control the deformation and motion of the particles are introduced.A series of numerical experiments were conducted on an idealized debris slide impacting a retaining wall.The parametric study has been performed to examine the influences of slope geometry,travel distance of the sliding mass,wall position,and surface friction on the impact force exerted on the wall.Results show that:1) the force achieves its maximum value when slope angle is equal to 60°,as it varies from 30° to 75°;2) an approximate linear relationship between the impact force and the storage area length is determined.
文摘Fog computing is a new paradigm supporting the stringent requirements of mobility applications by bridging cloud computing and smart devices. Since the smart devices may be deployed in dynamic areas where are out of strict monitoring and protection, fog computing requires security protections to ensure confidentiality and integrity. In this article, to deal with security requirements and considering the distinctive features, a key management based on hypergraph schemed is designed. Firstly, based on the key hypergraph, the three hierarchy architecture of fog computing is divided into two subnetworks. Furthermore, each key management process of both two subnetworks is designed to satisfy the operational and security requirements of fog computing. Finally, the performance evaluation and numerical simulation have been provided to validate the proposed scheme.
文摘This paper mainly uses the method of numerical simulation, and study thermal insulation and energy saving characteristics on the exterior walls of the building and analyze the optimal layout scheme of building exterior wall and thermal insulation system. Finally, the paper study optimal thickness of insulation materials. The paper elaborate scheme of the existing building energy-saving for exterior wall and the scope of application, the system structure and the construction technology. The results showed that： extruded benzene board that can be used for exterior insulation, frame structure filled with wall preferred ceramsite hollow block. The paper can provides reference selection of insulation for building external wall energy-saving transformation scheme.
