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731.
732.
摩托车标准最初是依托汽车标准体系起步的,从最初的摩托车整车产品,过渡到发动机产品、零部件产品,逐渐形成具有自身特色的摩托车产品标准体系,有效支撑了我国摩托车产业的建立与发展,促进了产品质量及技术水平的不断提升。 相似文献
733.
信号周期是交通控制的主要参数之一,也是影响交叉口公交车辆延误的主要因素.本文提出考虑在线优先需求的离线信号周期优化结构模型,其最优周期由离线基本周期和在线增量两部分构成.离线基本模型以加权车均延误为目标,探讨公交权重的影响因素及其与公交运行效益、社会车流运行效益的关系;在线增量计算以在线优先策略提供可实施空间为目标.分析一个四相位信号控制交叉口,对所提模型进行仿真验证.结果表明,公交车均延误最小的最优周期和社会车流车均延误最小的最优周期并不重叠,在一定的公交权重下,模型能够求得二者加权最优解.适当的在线增量引入,能够进一步降低公交车辆延误,且不会对非优先车流产生较大影响. 相似文献
734.
Sustainability Development Goals (SDGs) are a comprehensive agenda agreed upon globally that aims to stimulate actions towards economic, environmental and social sustainability. Being one of the key stakeholders, the international maritime industry plays an important role in contributing to global sustainability. By applying the concept of social entrepreneurship (SE), this study aims to examine (1) the basic and extended responsibilities (SDG 1–SDG 16) and (2) the potential collaborations within the value chain (SDG 17) concerning SDG implementation in maritime industry. To achieve these, we conduct a content analysis of sustainability reports published by container shipping liners and terminal operators from 2016 to 2019. More specifically, manual text classification is adopted to categorise the text content of sustainability reports based on 17 SDGs, and automatic text mining is employed to further identify the key roles of maritime industry related to each SDG. A unified framework is proposed, which points to varied motives and levels of comprehensiveness of the sustainability efforts by the maritime industry. This framework reveals the theoretic process of maritime industry's transitional involvement in sustainability from the SE perspective. It also creates managerial implications regarding the resource allocation strategies by maritime industry in meeting SDGs. 相似文献
735.
736.
There are various technical challenges faced by the super-long mountainous tunnelling at great depth,and new requirements are arising in terms of the geological investigation, construction period, special geological condi-tions (high ground stress, high geothermal temperature and high-pressure groundwater), disaster prevention & evacua-tion, and social development. Based on an analysis of above mentioned technical challenges, this paper presents tech-nical views on solutions to those challenges and specifies the objectives of related technical development in the fu-ture. To improve the validity and accuracy of the geophysical prospecting, it is necessary to not only increase the accu-racy of ground geophysical exploration at great depth, but also carry out research on the application of such tech-niques to tunnel investigation as airborne geophysical prospecting and HDD combined with borehole geophysical ex-ploration. To maximize the benefits of tunnel projects, it is of importance that more attention should be paid to thoseissues relating to the tunnel design concept, such as the multiple functions of tunnel projects, energy saving andemission reduction, and environmental protection. As for tunnel support theories, in addition to optimizing the currenttheories, some unconventionally new lining theories need to be studied to make the tunnel structure more durable andeconomical. It is also suggested that, in terms of construction, sustained efforts should be put into the development ofinnovative tunnelling techniques for a better, faster and more economical tunnelling, as well as the realization of intel-ligent mechanized tunnelling. When it comes to operation, it is obvious that there will be a trend towards intelligent maintenance in the future. © 2018, Editorial Office of "Modern Tunnelling Technology". All right reserved. 相似文献
737.
针对膨胀土边坡坍滑多呈浅层性,取广西百色膨胀土为对象,设计并开展经干湿循环作用含低围压条件的重塑土饱和三轴固结排水试验,着重分析橡皮膜约束对围压的影响并做出校正,对比分析校正前、后的实测抗剪强度参数,探究不同干湿循环次数及试验围压下的强度及应力-应变关系。结果表明:经干湿循环作用,各级围压下试件的应力-应变均呈应变硬化特征;围压越大,初始模量越大,主应力差也越大;干湿循环作用下,橡皮膜约束等效围压σ3e均随试验围压σ3增大而减小;0次干湿循环下,σ3由5 kPa增至200 kPa时,σ3e从9.1 kPa减少至6.7 kPa,σ3e/σ3由181.8%减少至3.4%,橡皮膜约束对低围压的测试结果影响显著,须进行校正;干湿循环由0次增至6次,校正前低、高和全围压段的黏聚力分别衰减34.7%、27.7%和28.3%,校正后衰减达77.1%、31.9%和35.6%,但摩擦角变化小;橡皮膜约束影响后,经6次干湿循环作用,低围压段的黏聚力仅为0.8 kPa,趋于0,摩擦角为18.5°;膨胀土边坡稳定性分析时,宜采用低、高围压两段拟合校正围压应力圆的强度参数,以获得与实际坍滑破坏较吻合的计算结果。 相似文献
738.
739.
西部陆海新通道货运量预测研究 总被引:1,自引:0,他引:1
西部陆海新通道在区域协调发展格局中具有战略地位,对我国深化陆海双向开放、推进西部大开发形成新格局等具有重要意义.在分析西部陆海新通道总体规划及铁路网规划的基础上,结合西部陆海新通道功能定位,分析货运量影响因素,从区域间货运量、对外贸易货运量、分流沿江通道货运量3个方面进行运量预测.针对每部分货运量,在分析历年货运量的基... 相似文献
740.