在三维地理信息系统(Geography Information System,GIS)中,高效、逼真地模拟现实场景是研究的重要内容之一。因此如何获得精确的场景数据和逼真的场景显示是研究的关键问题。该文对三维地理信息系统中模型的数据采集和构建方法进行了研...在三维地理信息系统(Geography Information System,GIS)中,高效、逼真地模拟现实场景是研究的重要内容之一。因此如何获得精确的场景数据和逼真的场景显示是研究的关键问题。该文对三维地理信息系统中模型的数据采集和构建方法进行了研究,采用OPENGL三维图形技术和基于四叉树的区域分层显示技术,实现了一个可针对具体模型操作和查询分析的高逼真度三维地理信息系统。并在系统中完成了虚拟校园一角的设计。实践证明,该系统所采用的方法和技术能够精确高效的虚拟真实场景,满足虚拟校园或虚拟小区规划的要求。展开更多
Anti-ram bollards used in perimeter protection are tested to meet performance requirements of established standards such as the US Department of State Specification SD-STD-02.01. Under these standards, tests are condu...Anti-ram bollards used in perimeter protection are tested to meet performance requirements of established standards such as the US Department of State Specification SD-STD-02.01. Under these standards, tests are conducted in prescribed conditions that should be representative of the service installation. In actual project, conditions encountered on site may vary from the test environment and it would be expensive and time consuming to validate each deviation with a physical test. High-fidelity physics-based (HFPB) finite element modeling can provide precise simulations of the behavior of anti-ram bollards. This paper presents the use of HFPB finite element modeling, using LS-DYNA, in an actual project to evaluate the performance of an anti-ram bollard design subjected to various boundary conditions representing the physical conditions encountered on site. The study shows that boundary conditions can have a significant influence on the performance of the anti-ram bollards. This suggests that anti-ram bollards must be designed and engineered according to actual conditions that are found on site. It also shows that HFPB modeling can be an effective tool that supplements physical testing of anti-ram bollards.展开更多
文摘在三维地理信息系统(Geography Information System,GIS)中,高效、逼真地模拟现实场景是研究的重要内容之一。因此如何获得精确的场景数据和逼真的场景显示是研究的关键问题。该文对三维地理信息系统中模型的数据采集和构建方法进行了研究,采用OPENGL三维图形技术和基于四叉树的区域分层显示技术,实现了一个可针对具体模型操作和查询分析的高逼真度三维地理信息系统。并在系统中完成了虚拟校园一角的设计。实践证明,该系统所采用的方法和技术能够精确高效的虚拟真实场景,满足虚拟校园或虚拟小区规划的要求。
文摘Anti-ram bollards used in perimeter protection are tested to meet performance requirements of established standards such as the US Department of State Specification SD-STD-02.01. Under these standards, tests are conducted in prescribed conditions that should be representative of the service installation. In actual project, conditions encountered on site may vary from the test environment and it would be expensive and time consuming to validate each deviation with a physical test. High-fidelity physics-based (HFPB) finite element modeling can provide precise simulations of the behavior of anti-ram bollards. This paper presents the use of HFPB finite element modeling, using LS-DYNA, in an actual project to evaluate the performance of an anti-ram bollard design subjected to various boundary conditions representing the physical conditions encountered on site. The study shows that boundary conditions can have a significant influence on the performance of the anti-ram bollards. This suggests that anti-ram bollards must be designed and engineered according to actual conditions that are found on site. It also shows that HFPB modeling can be an effective tool that supplements physical testing of anti-ram bollards.