The unique features of jointed post-tensioned wall systems, which include minimum structural damage and re-centering capability when subjected to earthquake lateral loads, are the result of using unbonded post-tension...The unique features of jointed post-tensioned wall systems, which include minimum structural damage and re-centering capability when subjected to earthquake lateral loads, are the result of using unbonded post-tensioning to attach the walls to the foundation, along with employing energy dissipating shear connectors between the walls. Using acceptance criteria defined in terms of inter-story drift, residual drift, and floor acceleration, this study presents a multiplelevel performance-based seismic evaluation of two five-story unbonded post-tensioned jointed precast wall systems. The design and analysis of these two wall systems, established as the direct displacement-based and force-based solutions for a prototype building used in the PREcast Seismic Structural Systems （PRESSS） program, were performed at 60% scale so that the analysis model could be validated using the PRESSS test data. Both buildings satisfied the performance criteria at four levels of earthquake motions although the design base shear of the direct displacement-based jointed wall system was 50% of that demanded by the force-based design method. The study also investigated the feasibility of controlling the maximum transient inter-story drift in a jointed wall system by increasing the number of energy dissipating shear connectors between the walls but without significantly affecting its re-centering capability.展开更多
X-Code is one of the most important redundant array of independent disk （RAID）-6 codes which are capable of tolerating double disk failures. However, the code length of X-Code is restricted to be a prime number, and...X-Code is one of the most important redundant array of independent disk （RAID）-6 codes which are capable of tolerating double disk failures. However, the code length of X-Code is restricted to be a prime number, and such code length restriction of X-Code limits its usage in the real storage systems. Moreover, as a vertical RAID-6 code, X-Code can not be extended easily to an arbitrary code length like horizontal RAID-6 codes. In this paper, a novel and efficient code shortening algorithm for X-Code is proposed to extend X-Code to an arbitrary length. It can be further proved that the code shortening algorithm maintains the maximum-distance-separable （MDS） property of X-Code, and namely, the shortened X-Code is still MDS code with the optimal space efficiency. In the context of the shortening algorithm for X-Code, an in-depth performance analysis on X-Code at consecutive code lengths is conducted, and the impacts of the code shortening algorithm on the performance of X-Code in various performance metrics are revealed.展开更多
通过对美国基于性能的抗震设计规范的简介,其中重点介绍了美国西岸城市洛杉矶和旧金山最近颁布的基于性能的高层建筑抗震设计规范"An alternative procedure for seismic analysis and design oftall buildings located in the los...通过对美国基于性能的抗震设计规范的简介,其中重点介绍了美国西岸城市洛杉矶和旧金山最近颁布的基于性能的高层建筑抗震设计规范"An alternative procedure for seismic analysis and design oftall buildings located in the los angeles region(2005 Edition)"和"Recommended administrative bulletin onthe seismic design&reviewof tall buildings using non-prescriptive procedures",总结了高层建筑结构基于性能的结构抗震设计要点,为我国相应规范的修订提供参考。展开更多
文摘The unique features of jointed post-tensioned wall systems, which include minimum structural damage and re-centering capability when subjected to earthquake lateral loads, are the result of using unbonded post-tensioning to attach the walls to the foundation, along with employing energy dissipating shear connectors between the walls. Using acceptance criteria defined in terms of inter-story drift, residual drift, and floor acceleration, this study presents a multiplelevel performance-based seismic evaluation of two five-story unbonded post-tensioned jointed precast wall systems. The design and analysis of these two wall systems, established as the direct displacement-based and force-based solutions for a prototype building used in the PREcast Seismic Structural Systems （PRESSS） program, were performed at 60% scale so that the analysis model could be validated using the PRESSS test data. Both buildings satisfied the performance criteria at four levels of earthquake motions although the design base shear of the direct displacement-based jointed wall system was 50% of that demanded by the force-based design method. The study also investigated the feasibility of controlling the maximum transient inter-story drift in a jointed wall system by increasing the number of energy dissipating shear connectors between the walls but without significantly affecting its re-centering capability.
基金supported by the National Basic Research Program of China (Grant Nos.2011CB302300, 2011CB302301)the National High-Technology Research and Development Program of China (Grant Nos.2009AA01A401,2009AA01A402)+1 种基金the National Natural Science Foundation of China (Grant Nos.60873028, 60933002, 61025008)the Changjiang Innovation Group of Education of China (Grant No.IRT0725)
文摘X-Code is one of the most important redundant array of independent disk （RAID）-6 codes which are capable of tolerating double disk failures. However, the code length of X-Code is restricted to be a prime number, and such code length restriction of X-Code limits its usage in the real storage systems. Moreover, as a vertical RAID-6 code, X-Code can not be extended easily to an arbitrary code length like horizontal RAID-6 codes. In this paper, a novel and efficient code shortening algorithm for X-Code is proposed to extend X-Code to an arbitrary length. It can be further proved that the code shortening algorithm maintains the maximum-distance-separable （MDS） property of X-Code, and namely, the shortened X-Code is still MDS code with the optimal space efficiency. In the context of the shortening algorithm for X-Code, an in-depth performance analysis on X-Code at consecutive code lengths is conducted, and the impacts of the code shortening algorithm on the performance of X-Code in various performance metrics are revealed.
文摘目的:研究基于循证的医疗设备维护管理方法,提供一个客观的、标准化的方法来支持医疗设备管理工作。方法:循证维护基于证据(故障历史),首先使用一组故障类型代码对维护工作单进行分类,通过分析医疗设备的检测、预防性维护(inspection and preventive maintenance,IPM)及维修维护(corrective maintenance,CM)事件工作单,识别出现频率异常高的故障代码;然后运用一组关键绩效指标评估医疗设备的维护性能。以手术室和ICU内监护仪和注射泵为例,通过对其2015—2018年维护性能进行监测,验证基于循证的医疗设备维护管理方法的可靠性。结果:根据循证依据采取各项有针对性的预防性维护措施,包括增加更高频率的定期维护并关注更容易出现故障的配件等可减少监护仪的故障;根据循证依据采取培训措施能降低由于不正确使用及管理引起的注射泵故障。结论:基于循证的维护可以全方位监测医疗设备的维护性能,并通过改进维护策略改善其维护有效性,进而提高临床工程人员和患者的安全。
文摘通过对美国基于性能的抗震设计规范的简介,其中重点介绍了美国西岸城市洛杉矶和旧金山最近颁布的基于性能的高层建筑抗震设计规范"An alternative procedure for seismic analysis and design oftall buildings located in the los angeles region(2005 Edition)"和"Recommended administrative bulletin onthe seismic design&reviewof tall buildings using non-prescriptive procedures",总结了高层建筑结构基于性能的结构抗震设计要点,为我国相应规范的修订提供参考。
