Long-period structures(e.g.Isolated structures)tend to produce pseudo-resonance with low frequency compo-nents of long-period ground motions,resulting in the increase in damage.Stiffness mutation occurs due to the set...Long-period structures(e.g.Isolated structures)tend to produce pseudo-resonance with low frequency compo-nents of long-period ground motions,resulting in the increase in damage.Stiffness mutation occurs due to the set-back in the upper body of the large chassis structure.In the parts with stiffness mutation,the torsion effect caused by the tower is far greater than that of the chassis itself.In this study,a total of 273 ground motions are collected and then filtered into four types,including the near-field ordinary,near-field pulse,far-field ordinary,and far-field harmonic.An 8-degree(0.2 g)fortified large chassis base-isolated structure is established.Furthermore,ETABS program software is used to conduct nonlinear time history analysis on the isolation and seismic model under bi-directional earthquake ground motions.The comparison results show that the seismic isolation effect of the base-isolated structure under long-period ground motions is worse than that associated with ordinary ground motions when the seismic response reduction rate of the large base floor significantly decreases compared with that of the tower.When the inter-story displacement angle and the displacement of isolation layer of the chassis exceeds the limit of Code for Seismic Design of Buildings(GB 50011-2010),it is recommended to adopt composite seismic isolation technology or add limit devices.Under the condition of long-period ground motions,the base-isolated structure reduces the lateral-torsional coupling effect of the large chassis structure,while the torsion response of large chassis’top layer increases.Under long-period ground motions with the same acceleration peak,the response of the base-isolated structure increases much more than that of the seismic structure and the consideration of this impact is suggested to be added to the Code.展开更多
为解决铁路编组站工作人员难以快速查询生产数据和规章制度的问题,基于国产大模型DeepSeek-R1,设计了一套编组站智询系统。通过本地化私有部署DeepSeek-R1并将其与编组站综合自动化系统(CIPS,Computer Integrated Process System)安全集...为解决铁路编组站工作人员难以快速查询生产数据和规章制度的问题,基于国产大模型DeepSeek-R1,设计了一套编组站智询系统。通过本地化私有部署DeepSeek-R1并将其与编组站综合自动化系统(CIPS,Computer Integrated Process System)安全集成,结合分层智能体架构、混合检索及NL2SQL(Natural Language to Structured Query Language)技术,构建了自然语言交互式服务,支持工作人员实时获取列车状态、调车计划等生产数据及规章知识。应用表明,该系统能够准确回答用户提出的问题,为铁路货运智能化提供技术支撑。展开更多
Advances in positioning and wireless commu- nicating technologies make it possible to collect large volumes of trajectory data of moving vehicles in a fast and convenient fashion. These data can be applied to traffic ...Advances in positioning and wireless commu- nicating technologies make it possible to collect large volumes of trajectory data of moving vehicles in a fast and convenient fashion. These data can be applied to traffic studies. Behind this application, a methodological issue that still requires particular attention is the way these data should be spatially visualized. Trajectory data physically consists of a large number of positioning points. With the dramatic increase of data volume, it becomes a challenge to display and explore these data. Existing commercial software often employs vector-based indexing structures to facilitate the display of a large volume of points, but their performance downgrades quickly when the number of points is very large, for example, tens of millions. In this paper, a pyramid-based approach is proposed. A pyramid method initially is invented to facilitate the display of raster images through the tradeoff between storage space and display time. A pyramid is a set of images at different levels with different resolutions. In this paper, we convert vector-based point data into raster data, and build a grid- based indexing structure in a 2D plane. Then, an image pyramid is built. Moreover, at the same level of a pyramid, image is segmented into mosaics with respect to the requirements of data storage and management. Algorithms or procedures on grid-based indexing structure, image pyramid, image segmentation, and visualization operations are given in this paper. A case study with taxi trajectory data in Shanghai is conducted. Results demonstrate that the proposed method outperforms the existing commercial software.展开更多
基金This project is jointly sponsored by Yunnan Youth Earthquake Science Foundation(2020K06)the National Natural Science Foundation of China(51778149)Xiamen University Tan Kah College School-Enterprise Cooperation Foundation(JGH2020034).
文摘Long-period structures(e.g.Isolated structures)tend to produce pseudo-resonance with low frequency compo-nents of long-period ground motions,resulting in the increase in damage.Stiffness mutation occurs due to the set-back in the upper body of the large chassis structure.In the parts with stiffness mutation,the torsion effect caused by the tower is far greater than that of the chassis itself.In this study,a total of 273 ground motions are collected and then filtered into four types,including the near-field ordinary,near-field pulse,far-field ordinary,and far-field harmonic.An 8-degree(0.2 g)fortified large chassis base-isolated structure is established.Furthermore,ETABS program software is used to conduct nonlinear time history analysis on the isolation and seismic model under bi-directional earthquake ground motions.The comparison results show that the seismic isolation effect of the base-isolated structure under long-period ground motions is worse than that associated with ordinary ground motions when the seismic response reduction rate of the large base floor significantly decreases compared with that of the tower.When the inter-story displacement angle and the displacement of isolation layer of the chassis exceeds the limit of Code for Seismic Design of Buildings(GB 50011-2010),it is recommended to adopt composite seismic isolation technology or add limit devices.Under the condition of long-period ground motions,the base-isolated structure reduces the lateral-torsional coupling effect of the large chassis structure,while the torsion response of large chassis’top layer increases.Under long-period ground motions with the same acceleration peak,the response of the base-isolated structure increases much more than that of the seismic structure and the consideration of this impact is suggested to be added to the Code.
文摘为解决铁路编组站工作人员难以快速查询生产数据和规章制度的问题,基于国产大模型DeepSeek-R1,设计了一套编组站智询系统。通过本地化私有部署DeepSeek-R1并将其与编组站综合自动化系统(CIPS,Computer Integrated Process System)安全集成,结合分层智能体架构、混合检索及NL2SQL(Natural Language to Structured Query Language)技术,构建了自然语言交互式服务,支持工作人员实时获取列车状态、调车计划等生产数据及规章知识。应用表明,该系统能够准确回答用户提出的问题,为铁路货运智能化提供技术支撑。
文摘Advances in positioning and wireless commu- nicating technologies make it possible to collect large volumes of trajectory data of moving vehicles in a fast and convenient fashion. These data can be applied to traffic studies. Behind this application, a methodological issue that still requires particular attention is the way these data should be spatially visualized. Trajectory data physically consists of a large number of positioning points. With the dramatic increase of data volume, it becomes a challenge to display and explore these data. Existing commercial software often employs vector-based indexing structures to facilitate the display of a large volume of points, but their performance downgrades quickly when the number of points is very large, for example, tens of millions. In this paper, a pyramid-based approach is proposed. A pyramid method initially is invented to facilitate the display of raster images through the tradeoff between storage space and display time. A pyramid is a set of images at different levels with different resolutions. In this paper, we convert vector-based point data into raster data, and build a grid- based indexing structure in a 2D plane. Then, an image pyramid is built. Moreover, at the same level of a pyramid, image is segmented into mosaics with respect to the requirements of data storage and management. Algorithms or procedures on grid-based indexing structure, image pyramid, image segmentation, and visualization operations are given in this paper. A case study with taxi trajectory data in Shanghai is conducted. Results demonstrate that the proposed method outperforms the existing commercial software.
