地铁隧道地震动力响应模拟试验研究

为研究地震荷载作用下隧道结构的动力响应,以指导隧道修建施工和衬砌支护,提高地铁隧道的整体抗震能力,采用理论分析、数值模拟和室内试验相结合的方法,对地铁隧道地震动力响应进行研究。选取沈阳地铁2号线某段隧道为工程背景,在理论分析地铁隧道地震动力响应的前提下,运用FLAC~(3D)数值软件模拟地铁隧道地震动力响应情况,地铁隧道两帮壁正负45°区域剪应力、主应力和位移最显著,监测点加速度变化趋势与输入地震波加速度时程曲线较为一致。在室内振动台试验中,地基土体表面峰值加速度明显比地基土体深部大,隧道两帮壁正负45°位置附近应变最大,振动停止后应变并未归零。数值模拟与室内试验研究结果较为吻合表明,由于人工波的地震烈度较现场波大,地铁隧道的地震扰动强烈;地铁隧道两帮壁正负45°区域地震动力响应剧烈,极易发生破坏。可根据这一现象有针对性地采取抗震措施,保证地铁隧道的安全、稳定。     

Contribution of individual components of a job cycle on overall severity of whole-body vibration exposure: a study in Indian mines

Drivers of earth-moving machines are exposed to whole-body vibration (WBV). In mining operations there can be a combination of relatively high magnitudes of vibration and long exposure times. Effective risk mitigation requires understanding of the main aspects of a task that pose a hazard to health. There are very few published studies of WBV exposure from India. This paper reports on a study that considered the contribution of the component phases of dumper operations, on the overall vibration exposure of the drivers. It shows that vibration magnitudes are relatively high, and that haulage tasks are the main contributor to the exposure. It is recommended that driver speed, haul road surfaces and vehicle maintenance/selection are optimized to ensure minimization of vibration. If this is not sufficient, operation times might need to be reduced in order to ensure that the health guidance caution zone from Standard No. ISO 2631-1:1997 is not exceeded.     

基于信号流循环的振动试验控制回路分析研究

目的总结分析振动试验信号循环全过程的数学模型及传递关系。方法根据信号传递过程中的作用,将振动设备划分为五类关键设备,并且将信号流在信号转换、信号可测及运动可控等方面的传递关系进行分析汇总,最后给出以控制仪为回路节点的两类开环故障的影响分析。结果通过对信号流循环过程的分析研究,总结了闭环反馈控制过程各环节中的信号传递关系,分析了各关键设备性能对振动试验信号传递的影响,以便于试验人员更好地开展振动试验。结论信号流循环的正常运转是振动试验顺利开展的基础,深入了解信号传递关系和影响因素,可以高质量地开展振动试验。     

舰船设备振动试验方法的探讨

目的探讨舰船设备振动试验中的几个问题并提出解决方法。方法分析GJB 150.16A,GJB4.7—83和MIL-STD-167-1A等振动试验标准,找出其中存在的缺点。阐述实验室模拟与实际环境的差异,提出改进建议。结果 GJB 150.16A中没有明确说明随机部分和正弦部分是单独试验还是叠加试验,GJB 4.7—83和MIL-STD-167-1A中没有给出随机振动的条件,只有正弦振动部分。结论对于标准中存在的缺点,在每个轴向,首先进行一半的功能试验,再进行随机叠加正弦/随机振动,最后进行另一半功能试验。对于实验室模拟与实际环境存在差异的问题,通过采用力谱控制、采用模拟舰船结构的夹具、规定安装方式、对环境条件进行反复迭代等方法改进。     

公路桥面伸缩装置及其对桥梁静动力性能影响综述∗

桥梁伸缩装置(以下简称伸缩缝)使用环境恶劣、受荷形式复杂,易出现多种病害。伸缩缝病害会造成桥梁耐久性降低,车致桥梁动力响应加重等不利现象。因此,伸缩缝病害机理及其处置方法和考虑伸缩缝参数影响的车-桥耦合动力响应规律研究受到了广泛关注。本文综述了桥梁伸缩缝力学性能,常见病害及其影响,病害机理及其处置方法等的发展现状;重点讨论了考虑伸缩缝参数及其变化影响的桥梁动力响应的研究进展及存在的问题;展望了未来桥梁伸缩缝研究中有待解决的关键问题。     

模糊综合评价方法在舰船机舱消防安全管理中的应用

舰船机舱消防安全管理在舰船安全管理中占有极重要的地位。该文根据模糊数学的思想和方法,建立了舰船机舱消防安全模糊综合评价方法,用层次分析法全面分析了影响舰船机舱消防安全的各种因素,结合实例说明利用专家经验、观点与统计数字对模糊因素加以量化处理的过程和方法。结果表明,模糊综合评价方法适用于舰船机舱消防安全的综合评价,并使机舱消防安全管理更加科学,有助于提高机舱消防安全管理水平。     

电动汽车用电机及其控制器振动试验方法的探讨

振动试验是汽车产品设计验证和质量检验重要试验方法。本文主要从试验标准、试验条件、振动试验中主要参数的计算推导及应用、试验工装的设计、试验中应注意的问题等方面对电动汽车电机及其控制器的振动试验进行介绍。     

青岛秋冬季PM1中金属元素污染特征及健康风险评估

于2018年11月1日至2019年1月31日（OP_2018-2019）和2019年11月1日至2020年1月20日（OP_2019-2020）在青岛对PM₁进行了连续两年秋冬季逐日采集.将观测期划分为4个空气质量等级（Ⅰ级、Ⅱ级、Ⅲ级和Ⅳ级）,分析了PM₁中金属元素浓度特征及来源,评估了不同人群的非致癌风险（Zn、Pb、Mn、Cu和V）和致癌风险（As、Cr、Ni、Cd和Co）.结果表明,与OP_2018-2019相比,OP_2019-2020期间不同空气质量等级下金属元素总浓度变化与Ca、K和Al浓度变化有关,受扬尘源和生物质燃烧源影响较大.与OP_2018-2019相比,OP_2019-2020期间不同空气质量等级下V浓度分别下降19.0%、60.5%、82.7%和77.5%.推测与船舶国内排放控制区域（DECA）政策实施有关,青岛周边海域船舶改换燃油品质,导致V浓度大幅降低.由富集因子、比值法和气流后向轨迹结果进一步表明V浓度变化主要受DECA政策影响.然而,实施DECA政策后,V/Ni值作为判断区域内受船舶源影响的限值,需进一步探究.由健康风险评估结果表明,OP_2018-2019和OP_2019-2020期间非致癌元素Mn的危险系数范围为0.07~1.22,建议加强管控含Mn污染源的排放.OP_2018-2019和OP_2019-2020期间不同空气质量下As、Cd的终生致癌风险概率（ILCR）值低于10^-4,但高于10^-6,表明存在致癌概率,但仍可接受.OP_2018-2019期间空气质量为Ⅳ级时,Cr的ILCR值高于10^-4,存在致癌风险.     

橡胶隔振器寿命预测及加速试验研究进展

介绍了橡胶材料的疲劳失效形式及影响橡胶材料抗疲劳性能的因素,总结了基于撕裂能和基于S-N曲线的橡胶材料疲劳寿命预测方法,阐明了橡胶隔振器加速试验研究的现状,展望了未来值得研究的方向。     

The honey bee shaking signal: function and design of a modulatory communication signal

This study explores the meaning and functional design of a modulatory communication signal, the honey bee shaking signal, by addressing five questions: (I) who shakes, (II) when do they shake, (III) where do they shake, (IV) how do receivers respond to shaking, and (V) what conditions trigger shaking. Several results confirm the work of Schneider (1987) and Schneider et al. (1986a): (I) most shakers were foragers (at least 83%); (II) shaking exhibited a consistent temporal pattern with bees producing the most signals in the morning (0810–1150 hours) just prior to a peak in waggle dancing activity; and (IV) bees moved faster (by 75%) after receiving a shaking signal. However, this study differs from previous work by providing a long-term, temporal, spatial, and vector analysis of individual shaker behavior. (III) Bees producing shaking signals walked and delivered signals in all areas of the hive, but produced the most shaking signals directly above the waggle dance floor. (IV) Bees responded to the signal by changing their direction of movement. Prior to receiving a signal, bees selected from the waggle dance floor moved, on average, towards the hive exit. After receiving a signal, some bees continued moving towards the exit but others moved directly away from the exit. During equivalent observation periods, non-shaken bees exhibited a strong tendency to move towards the hive exit. (V) Renewed foraging activity after food dearth triggered shaking signals, and, the level of shaking is positively correlated with the duration of food dearth. However, shaking signal levels also increased in the morning before foraging had begun and in the late afternoon after foraging had ceased. This spontaneous afternoon peak has not previously been reported. The shaking signal consequently appears to convey the general message “reallocate labor to different activities” with receiver context specifying a more precise meaning. In the context of foraging, the shaking signal appears to activate (and perhaps deactivate) colony foraging preparations. The generally weak response elicited by modulatory signals such as the shaking signal may result from a high receiver response threshold which allows the receiver to integrate multiple sources of information and which thereby increases the probability that receiver actions will be appropriate to colony needs. Received: 21 March 1997 / Accepted after revision: 30 August 1997