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21.
姚东大桥悬浇前支点挂篮施工技术 总被引:1,自引:0,他引:1
前支点挂篮施工工艺复杂,技术含量高。文章结合余姚姚东大桥施工实践,分析了前支点挂蓝的设计原理和技术难点,介绍了前支点挂篮在混凝土斜拉桥主梁悬浇施工中的工艺及注意事项。 相似文献
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Modelling the impact of weather conditions on active transportation travel behaviour 总被引:1,自引:0,他引:1
Sheyda Saneinejad Matthew J. RoordaChristopher Kennedy 《Transportation Research Part D: Transport and Environment》2012,17(2):129-137
Three weather sensitive models are used to explore the relationship between weather and home-based work trips within the City of Toronto, focusing on active modes of transportation. The data are restricted to non-captive commuters who have the option of selecting among five basic modes of auto driver, auto passenger, transit, bike and walk. Daily trip rates in various weather conditions are assessed. Overall, the results confirm that impact of weather on active modes of transportation is significant enough to deserve attention at the research, data collection and planning levels. 相似文献
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Combining the present situation and development trend of different tunnel support technologies at home and abroad, this paper analyzes the problems of rockburst in hard rock tunnels and large deformation in soft rock tunnels caused by high ground stress. It is concluded that: 1) regarding the rockburst problem, the current support technology is mainly influenced by the rock burst mechanism which is dominated by static factors, and so the used support components are generally of smaller deformation performance and "passive support" properties; 2) as the rockburst is the result of dynamic-static stress coupling, and only the anchor bolt has the "active support" attribute in the current "shotcrete+anchor bolt+wire net" support system, so the best support system should have the two functions of active support and energy release in terms of the rockburst problem, and the key focus of the research and development is anchorage members; 3) there are three main support types for large deformation in soft rock tunnels, e.g. the heavy support, layered support and yielding support. Among them, the heavy support system in underground cavern with large deformation is easy to induce excessive surrounding rock pressure, and so the applicable conditions are limited. The layered support system is still not the best choice due to its immature theoretical study, difficult determination of the thickness value and the installation time of each support layer and the interference to construction progress. With the characteristics of timely support and yielding while supporting, the yielding support system can give full play to the performance values of surrounding rocks and supporting materials, and make both of them reach the optimal state, so it is the best choice for supporting the soft rock tunnels with large deformations. © 2018, Editorial Office of "Modern Tunnelling Technology". All right reserved. 相似文献
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Municipalities play an important role in the planning and development of communities that support active transportation (AT), which refers to human-powered modes of travel, such as walking and cycling. Municipal-level stakeholders involved in land-use and transportation infrastructure planning consider multiple social, environmental and economic considerations to inform decision-making and investments in AT. Evidence around the fiscal benefits of AT investment for local governments has not been systematically identified. This scoping review sought to explore the existing evidence regarding investments in AT and opportunities for savings on municipal expenditures and revenue generation. In total, 7060 records were located and screened; of which 162 full-text articles were reviewed. Ultimately, 23 articles met our inclusion criteria and were included in this review. The available evidence focuses on potential economic benefits of AT in the areas of tax revenues, property values, consumer spending and employment, all of which are relevant sources of revenue generation in municipal operating budgets. An evidence gap was identified regarding AT infrastructure investments and benefits corresponding to municipal expenditures (e.g. maintenance cost savings). Notably, a large portion of literature was published after 2009, suggesting that municipal-level evidence on the fiscal benefits of AT investments may just be emerging. 相似文献
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基于知识点关联的网络教学平台的集成设计 总被引:1,自引:0,他引:1
丁振凡 《华东交通大学学报》2007,24(1):63-66
教学课件各种信息成分的组织与关联是网络教学系统集成设计中的重要问题,本文给出了基于知识点的课件内容关联设计的实现.该平台支持多种教学方式,提供了灵活的设置以满足教学中的动态管理. 相似文献
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An algorithm is described for oceanic front detection in chlorophyll (Chl) and sea surface temperature (SST) satellite imagery. The algorithm is based on a gradient approach: the main novelty is a shape-preserving, scale-sensitive, contextual median filter applied selectively and iteratively until convergence. This filter has been developed specifically for Chl since these fields have spatial patterns such as chlorophyll enhancement at thermohaline fronts and small- and meso-scale chlorophyll blooms that are not present in SST fields. Linear Chl enhancements and localized (point-wise) blooms are modeled as ridges and peaks respectively, whereas conventional fronts in Chl and SST fields are modeled as steps or ramps. Examples are presented of the algorithm performance using modeled (synthetic) images as well as synoptic Chl and SST imagery. After testing, the algorithm was used on > 6000 synoptic images, 1999–2007, to produce climatologies of Chl and SST fronts off the U.S. Northeast. 相似文献
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7自由度主动悬架整车模型最优控制的研究 总被引:1,自引:0,他引:1
应用汽车系统动力学理论,建立了七自由度主动悬架的动力学模型。根据线性二次型最优控制原理设计了主动悬架线性二次型(LQR)控制器,并构建了实现该控制策略的主动悬架控制仿真模型。仿真结果表明:对主动悬架进行最优控制,能够有效地降低车身垂直振动加速度、车身侧倾角加速度和俯仰角加速度。 相似文献