减震缓冲器的设计构想     

范雷彪  丛陪历 《震灾防御技术》2009,4(3):347-354

应用隔震原理可以起到减轻地震作用力的效果。在实际应用中将隔震原理转化为隔震技术,需要解决好相应的技术问题。为此,本文在这方面做了一些探索,设计了一种专用装置——减震缓冲器。该装置是通过设置核心部件——弹力钢球,使其与隔震支座配合作用,既较好地起到了化解、缓冲部分地震波的作用,同时也解决了在单独使用隔震支座时可能遇到的问题。  相似文献   

海湾型城市建设用地扩展的时空动态特征及驱动力研究——以厦门市为例   总被引：3，自引：0，他引：3  

陈松林  刘诗苑 《地理科学》2009,29(3)

解译了厦门市1986~2007年6个时间点的遥感影像,提取建设用地斑块,借助ArcG IS9.0空间分析模块和空间统计功能,进行缓冲区分析。通过绘制建设用地类型扩展量曲线图,分析波峰-波谷时空变化,结合同期自然和人文因素的变化,揭示建设用地扩展的驱动力。结果表明:①自然因素和人文背景影响城镇用地扩展的基本格局;②社会经济实力积累推动建设用地空间分布的演变;③城市化和工业化相互作用快速推动建设用地的扩展;④政策因素多层次地影响建设用地的时空变化。  相似文献   

农用地分等省级汇总中单元制图综合方法     

罗广祥  弓晓敏  韩英英  卢国梁 《干旱区地理》2009,32(4)

根据农用地分等省级汇总的要求,提出了四种带有顺序性的分等单元制图综合方法,第一按地类、自然等、利用等、经济等相同合并邻接单元;第二在构建位于分等单元之外约束性Delauney 三角网的基础上,用边长作控制合并邻近地类、自然等、利用等、经济等相同的单元;第三删除零星单元,将面积归并到乡内地类、自然等、利用等、经济等相同的单元中;第四扩充零星单元.对提出的方法进行了编程实现,并在农用地分等省级汇总项目中得到了应用.理论分析及实验结果表明,所提方法具有严密的数学逻辑性,同时对地图制图综合这一前沿学术研究议题也具有一定借鉴与参考价值.  相似文献   

A buffered impact damper for multi‐degree‐of‐freedom structural control     

Kuinian Li  Antony P. Darby 《地震工程与结构动力学》2008,37(13):1491-1510

The results of an experimental investigation into the use of a buffered impact damper for controlling the dynamic response of an MDOF (multi‐degree‐of‐freedom) structure are presented in this paper. Free and forced vibration tests of a three‐DOF test structure equipped with a buffered impact damper are performed to evaluate the resulting damping effect and impact characteristics. The effect of damper parameters, such as clearance, and excitation type on the performance of the impact damper is also investigated. The performance of the buffered impact damper is compared with that of an equivalent conventional rigid impact damper. It is found that the buffered impact damper not only significantly reduces the peak contact force and the associated accelerations and noise generated by collisions but can also substantially enhance the damping effect over a wide range of frequencies, encompassing the natural frequencies of the test structure. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

高压实膨润土热湿耦合效应实验室模拟   总被引：2，自引：1，他引：1  

沈珍瑶  李书绅 《水文地质工程地质》1999,26(1):11-13

本文研究了作为高放废物深地质处置库最后一道人工屏障－缓冲层在热湿耦合艇下的宏观表现,通过自行设计的实验,得到了一些有益的启示,初步认为在本研究涉及的时间范围内,水势场对高压实膨润土中温度场分布影响较小,而温度场对其中水分运移有一定影响。文中介绍了有关实验设计、实验步骤,实验结果与分析,对多孔介质中传热传质研究及高放废物深地质处理有一定参考价值。．  相似文献   

Analysis of positional uncertainty of road networks in volunteered geographic information with a statistically defined buffer-zone method     

Wen-Bin Zhang  Jiang-Hong Ma 《International journal of geographical information science》2019,33(9):1807-1828

Volunteered geographic information (VGI) is crowdsourced information that can enrich and enhance research and applications based on geo-referenced data. However, the quality of VGI is of great concern, and positional accuracy is a fundamental basis for the VGI quality assurance. A buffer-zone method can be used for its assessment, but the buffer radius in this technique is subjectively specified; as result, different selections of the buffer radius lead to different positional accuracies. To solve this problem, a statistically defined buffer zone for the positional accuracy assessment in VGI is proposed in this study. To facilitate practical applications, we have also developed an iterative method to obtain a theoretically defined buffer zone. In addition to the positional accuracy assessment, we have derived a measure of positional quality, which comprises the assessment of positional accuracy and the level of confidence in such assessment determined with respect to a statistically defined buffer zone. To illustrate and substantiate the theoretical arguments, both numerical simulations and real-life experiments are performed using OpenStreetMap. The experimental results confirm the high significance of the proposed statistical approach to the buffer zone-based assessment of the positional uncertainty in VGI.  相似文献   

城市公共交通覆盖度空间统计分析研究     

孟庆伟 《测绘与空间地理信息》2020,(3):141-145

为了合理分析城市公共交通发展现状并对其发展提供可参考的依据,本文利用地理信息系统空间分析和统计方法,在确立多个评价指标的基础上,对城市公共交通覆盖度情况进行不同角度、不同方面的评价。以沈阳市内部分区域为研究对象,提取研究区域基础地理数据,结合人口数据以及公共交通线网缓冲区,选取城市主次干道为边界划分分析单元,将人口密度与道路数据相结合,将评价体系与数据进行对比分析。根据评价指标,得到研究范围内城市公交资源的分布状况。实验结果表明,该方法能够较好地分析城市公共交通分布特征,为城市交通规划设计提供思路。  相似文献   

温度对POP Rb原子钟性能影响的研究     

薛文祥  陈江  杜志静  张首刚 《时间频率学报》2012,35(3):129-136

从温度对缓冲气体碰撞频移和弛豫率的影响出发,对充有Ar和N2这2种缓冲气体的POP(pulsed optically pumped,脉冲激光抽运)汽泡式铷原子钟的温度特性进行了理论和实验研究。研究表明,Ar与N2的气压比为1.6时,60℃的线性温度系数为0;不同温度时,布居数差弛豫率1和相干弛豫率2各不相同,若1 2,则POP铷原子钟Ramsey条纹包络在微波场与原子跃迁失谐为0附近为凹陷,信噪比较差,反之,为凸起,信噪比较高。研究结果对设计POP原子钟的缓冲气体气压比和工作温度,以及提高POP原子钟的中长期稳定度有一定借鉴作用。  相似文献   

基于弹塑性修正Hertz接触理论的落石冲击力计算方法   总被引：1，自引：0，他引：1  

刘茂 《中国地质灾害与防治学报》2012,23(3):21-27

本文以弹塑性修正的Hertz接触理论为基础,考虑落石冲击缓冲层过程的复杂性和缓冲层厚度的影响,结合路基规范方法的落石冲击深度公式,得出落石最大冲击力计算方法。以日本道路公团方法计算结果上浮40%为基准值,引入参数影响系数ζ,拟合出参数影响系数ζ多项式函数,采用S.Kawahara等教授的试验结果,对杨其新方法进行修正,拟合出其高值(h=0.5m)与低值(h=3.0m)比值的多项式函数。本文方法与陈氏方法进行比较得知:陈氏方法的最大冲击力低值稍高于本文方法,其范围为1.05～1.02(H=5～30m)。运用布西涅斯克解,推导出了落石冲击荷载作用于拦石墙背部的附加应力计算公式,为拦石墙构筑物的结构设计打下了理论基础。  相似文献   

Modelling flow and sediment trapping upstream and within grass buffer strips          下载免费PDF全文

Sina Akram  Bofu Yu  Hossein Ghadiri 《水文研究》2015,29(14):3179-3192

Grass buffer strips impact the hydrology of flow and consequently the fate of sediment. A complex process‐based model is developed to predict flow characteristics as well as sediment deposition and transport upstream, and within grass strips. The model is capable of estimating the proportion and amount of different sediment particle size classes in the outflow. The modified Green–Ampt equation was used to simulate infiltration. Gradually varied flow and kinematic wave approximation were used to model flow characteristics upstream and within grass strips. The GUEST model approach has been modified in order to use its basic approaches in sediment transport module in grass strips. Model predictions agree well with the results of two sets of controlled experiments. The bias, coefficient of model efficiency and the root mean squared error of the modelled efficiency of grass strips in reducing sediment concentration were 0.93–0.99, 0.58–0.99 and 8.9–12.7, respectively. The sensitivity analysis showed that the initial soil moisture and flow rate are the most sensitive parameters in predicting runoff loss. Increasing the slope steepness and flow rate dramatically decreases the efficiency of grass strips in reducing sediment concentration and mass. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献