Plenty of dams in China are in danger while there are few effective methods for underwater dam inspections of hidden problems such as conduits,cracks and inanitions.The dam safety inspection remotely operated vehicle(...Plenty of dams in China are in danger while there are few effective methods for underwater dam inspections of hidden problems such as conduits,cracks and inanitions.The dam safety inspection remotely operated vehicle(DSIROV) is designed to solve these problems which can be equipped with many advanced sensors such as acoustical,optical and electrical sensors for underwater dam inspection.A least-square parameter estimation method is utilized to estimate the hydrodynamic coefficients of DSIROV,and a four degree-of-freedom(DOF) simulation system is constructed.The architecture of DSIROV's motion control system is introduced,which includes hardware and software structures.The hardware based on PC104 BUS,uses AMD ELAN520 as the controller's embedded CPU and all control modules work in VxWorks real-time operating system.Information flow of the motion system of DSIROV,automatic control of dam scanning and dead-reckoning algorithm for navigation are also discussed.The reliability of DSIROV's control system can be verified and the control system can fulfill the motion control mission because embankment checking can be demonstrated by the lake trials.展开更多
It is common to assume that structures are designed in view of 50 year life cycle as per Euro-Code 2 and other codes. In special cases, structures are designed in view of longer life cycle, such as bridges, important ...It is common to assume that structures are designed in view of 50 year life cycle as per Euro-Code 2 and other codes. In special cases, structures are designed in view of longer life cycle, such as bridges, important infrastructure facilities, important religious structures or in case of extended returning period of seismic event or floods. Beside issues of durability and maintenance aspects, this involves also the need to cover the probability of exceeding characteristic design live loads during the extended period, while keeping the same levels of the accepted risk that were assumed by the various codes, as good enough for the standard 50 year life cycle. Bearing in mind that design procedures, formulations, materials characteristic strengths and partial safety factors are used for these structures as per the existing codes, scaling of partial safety factors, or alternatively an additional ＂compensating＂ factor is required. A simplified approach and procedure to arrive at a reasonable calibration of the code safety factors based on 50 years to compensate for an extended life cycle, based upon structural reliability considerations, is proposed.展开更多
基金Project(20100480964) supported by China Postdoctoral Science FoundationProjects(2002AA420090,2008AA092301) supported by the National High Technology Research and Development Program of China
文摘Plenty of dams in China are in danger while there are few effective methods for underwater dam inspections of hidden problems such as conduits,cracks and inanitions.The dam safety inspection remotely operated vehicle(DSIROV) is designed to solve these problems which can be equipped with many advanced sensors such as acoustical,optical and electrical sensors for underwater dam inspection.A least-square parameter estimation method is utilized to estimate the hydrodynamic coefficients of DSIROV,and a four degree-of-freedom(DOF) simulation system is constructed.The architecture of DSIROV's motion control system is introduced,which includes hardware and software structures.The hardware based on PC104 BUS,uses AMD ELAN520 as the controller's embedded CPU and all control modules work in VxWorks real-time operating system.Information flow of the motion system of DSIROV,automatic control of dam scanning and dead-reckoning algorithm for navigation are also discussed.The reliability of DSIROV's control system can be verified and the control system can fulfill the motion control mission because embankment checking can be demonstrated by the lake trials.
文摘It is common to assume that structures are designed in view of 50 year life cycle as per Euro-Code 2 and other codes. In special cases, structures are designed in view of longer life cycle, such as bridges, important infrastructure facilities, important religious structures or in case of extended returning period of seismic event or floods. Beside issues of durability and maintenance aspects, this involves also the need to cover the probability of exceeding characteristic design live loads during the extended period, while keeping the same levels of the accepted risk that were assumed by the various codes, as good enough for the standard 50 year life cycle. Bearing in mind that design procedures, formulations, materials characteristic strengths and partial safety factors are used for these structures as per the existing codes, scaling of partial safety factors, or alternatively an additional ＂compensating＂ factor is required. A simplified approach and procedure to arrive at a reasonable calibration of the code safety factors based on 50 years to compensate for an extended life cycle, based upon structural reliability considerations, is proposed.
