Real‐time force control for servo‐hydraulic actuator systems using adaptive time series compensator and compliance springs     

《地震工程与结构动力学》2018,47(4):854-871

Servo‐hydraulic actuators have been widely used for experimental studies in engineering. They can be controlled in either displacement or force control mode depending on the purpose of a test. It is necessary to control the actuators in real time when the rate‐dependency effect of a test specimen needs to be accounted for under dynamic loads. Real‐time hybrid simulation (RTHS) and effective force testing (EFT) method, which can consider the rate‐dependency effect, have been known as viable alternatives to the shake table testing method. Due to the lack of knowledge in real‐time force control, however, the structures that can be tested with RTHS and EFT are fairly limited. For instance, satisfying the force boundary condition for axially stiff members is a challenging task in RTHS, while EFT has a difficulty to be implemented for nonlinear structures. In order to resolve these issues, this paper introduces new real‐time force control methods utilizing the adaptive time series (ATS) compensator and compliance springs. Unlike existing methods, the proposed force control methods do not require the structural modeling of a test structure, making it easy to be implemented especially for nonlinear structures. The force tracking performance of the proposed methods is evaluated for a small‐scale steel mass block system with a magneto‐rheological damper subjected to various target forces. Accuracy, time delay, and resonance response of these methods are discussed along with their force control performance for an axially stiff member. Overall, a satisfactory force tracking performance was observed by using the proposed force control methods.  相似文献   

各向异性介质的矢量波场分离与应用          下载免费PDF全文

芦俊  石瑛  杨春颖 《地球物理学报》2018,61(8):3310-3323

针对裂缝各向异性介质，本文提出一种非正交假设下的矢量波场分离方法.本文首先对多分量地震勘探中常见的波型泄漏现象进行了数学描述，提出在纵、横波波场分离的同时应该考虑恢复纵、横波的矢量振幅.为了对裂缝方位角与各向异性系数进行定量预测，本文将矢量波场分离拆分成三个步骤来实施：第一步，用Z、R两分量的仿射坐标系变换分离ZR平面内的P波投影与SV波；第二步，用ZR平面内的P波投影与T分量的仿射坐标系变换分离P波与SH波；第三步，用纯净的SV波与SH波的成像剖面分离快慢横波，并预测裂缝发育参数.模型数据与实际数据的试验结果表明，本文提出的纵、横波波场分离方法能够获得完整的矢量振幅信息，并提供裂缝预测的精度.  相似文献   

C-RESPONSE OF GEOMAGNETIC DEPTH SOUNDING ON A 1D THIN SHELL MODEL     

LI Shi-wen  WENG Ai-hua  TANG Yu  ZHANG Yan-hui  LI Jian-ping  YANG Yue 《地震地质》2018,40(2):337-348

This paper tries to formulate the C-response of geomagnetic depth sounding(GDS)on an Earth model with finite electrical conductivity. The computation is performed in a spherical coordinate system. The Earth is divided into a series of thin spherical shells. The source is approximated by a single spherical harmonic P₁⁰ due to the spatial structure of electrical currents in the magnetosphere. The whole solution space is separated into inner and external parts by the Earth surface. Omitting displacement current, the magnetic field in the external space obeys Laplacian equation, while in the inner part, due to the finite conductivity, the electromagnetic fields obey Helmholtz equation. To connect the magnetic fields in the inner and external space, the continuity condition of magnetic fields is used on the Earth surface. The external magnetic fields are expressed by the inner and external source coefficients, from which a new parameter called C-response is computed from the inner coefficient divided by the external coefficient, thus normalizing the actual source strength. The inner magnetic fields in each layer can be recursively derived by the continuity boundary condition of both normal and tangential components of the magnetic field from the initial boundary condition at core-mantle-boundary. The consistency of our C-responses with that from a typical 1-D global model validates the accuracy of the proposed algorithm. Numerical results also show that the C-response estimated from the geomagnetic transfer function method will deviate exceeding 5%from the actual response at longer periods than about 10⁶s, which means that ignoring the curvature of the Earth at extreme long periods will make inversion result unreliable. Therefore, an accurate C-response should be computed in order to lay a solid foundation for reliable inversion.  相似文献   

A simple strategy for dynamic substructuring: I. Concept and development     

Aikaterini Stefanaki  M. V. Sivaselvan 《地震工程与结构动力学》2018,47(9):1801-1822

Dynamic substructuring refers to physical testing with computational models in the loop. This paper presents a new strategy for such testing. The key feature of this strategy is that it decouples the substructuring controller from the physical subsystem. Unlike conventional approaches, it does not explicitly include a tracking controller. Consequently, the design and implementation of the substructuring controls are greatly simplified. This paper motivates the strategy and discusses the main concept along with details of the substructuring control design. The focus is on configurations that use shake tables and active mass drivers. An extensive experimental assessment of the new strategy is presented in a companion paper, where the influence of various factors such as virtual subsystem dynamics, control gains, and nonlinearities is investigated, and it is shown that robustly stable and accurate substructuring is achieved.  相似文献   

光照、温度对黑鲷(♀)×真鲷(♂)杂交子代受精卵孵化效果的影响     

刘海林  张志勇  张志伟  许津  陈淑吟  贾超峰  祝斐  孟乾 《海洋科学》2018,42(5):108-115

为了研究不同光照强度、温度对黑鲷(Acantho pagrusschlegelii)(♀)×真鲷(Pagrosomus major)(♂)杂交F1代受精卵孵化效果及仔鱼存活的影响,作者采用试验生态学的方法比较不同温度(16、18、20、22、24、26℃)下杂交鲷受精卵的孵化率、畸形率、孵化时间、7日龄仔鱼的存活率;比较不同光照强度下(10、100、300、800、1500、4 000、10 000 lx)受精卵孵化率、畸形率、孵化时间;比较不同光照强度下(200、1 000、2 000、5 000、10 000、15 000、20 000 lx)7日龄仔鱼的存活率。结果表明:在盐度为22条件下,受精卵最高孵化率(34.00%)和最低畸形率(16.65%)的孵化温度为20℃;在16～26℃范围内,温度与孵化时间呈负相关,与7日龄仔鱼存活率也呈负相关。不同的光照强度对受精卵孵化率和孵化时间的影响不显著,孵化率为65.88%～71.88%;但大于800lx的光照会令畸形率上升(大于15.21%);另外,5000～10000lx的光照强度更适宜仔鱼生存,7日龄仔鱼存活率达到38%～40.75%。黑鲷(♀)×真鲷(♂)杂交子代最佳孵化温度为20℃,最适光照强度为5 000～10 000 lx。  相似文献   

磁流变阻尼器的半主动控制及实时混合模拟试验研究          下载免费PDF全文

李歆  吕西林  Shirley Dyke 《世界地震工程》2018,34(4):130-135

磁流变阻尼器作为一种比较典型的半主动控制元件，具有构造简单、响应速度快、耐久性好、阻尼力大且连续可调等优点。即使地震中能源中断，磁流变阻尼器仍可以作为被动耗能装置继续工作发挥作用，可靠性高。设计合理有效的磁流变阻尼器半主动控制方法，对于整体结构的减震效果尤其重要。提出一种改进的磁流变阻尼器的半主动控制策略-改进的Bang-Bang控制策略，对装有磁流变阻尼器的减震控制3层框架结构进行了一系列的实时混合模拟试验，对多种半主动控制方法下的振动控制效果进行试验分析。试验结果表明:磁流变阻尼器对框架结构的减震效果显著，并验证了提出的磁流变阻尼器半主动控制策略的有效性。  相似文献   

非连续变形分析中块体大转动问题研究     

巩师林  凌道盛  胡成宝  钮家军 《岩土力学》2020,41(11):3810-3822

原有非连续变形分析（DDA）采用一阶近似后的位移增量表达式更新块体构形，推导相关子矩阵，且对不同时步计算出的应变增量直接叠加，当模拟的块体发生大转动时往往会产生较大误差。为考虑块体转动与变形的耦合作用，引入先变形、后转动的块体位移增量表达式。重新推导了惯性力子矩阵，将块体转动时的离心力与科氏力加到荷载矩阵中。计算时对应变分量及其相关变量进行坐标变换与修正，并采用新引入的位移增量表达式计算块体顶点位移，进行后接触修正与更新块体构形。数值算例表明，改进后的程序能够消除转动带来的误差，自动考虑了块体转动时离心力和科氏力引起的变形，应变计算精度更高。改进方法克服了块体体积自由膨胀、应变场畸变等问题，给出了合理的块体应变。  相似文献   

建筑抗震实时混合试验时滞补偿方法研究综述          下载免费PDF全文

刘洪波  刘洁 《地震工程学报》2020,42(6):1361-1368

时滞补偿是建筑抗震实时混合试验的重要问题。文章对时滞补偿方法的研究进行总结，将时滞补偿方法分为基于时间的位移预测时滞补偿方法、基于反馈力的位移预测时滞补偿方法、基于加载系统模型求逆的时滞补偿方法、基于控制理论的时滞补偿方法和基于集成理念的综合补偿方法。  相似文献   

加权总体最小二乘的效率优化算法     

倪福泽  王建民 《测绘通报》2020,(11):90

加权总体最小二乘法是理论上估计EIV模型参数相对严密的方法，其迭代过程中涉及的矩阵运算较为耗时，在处理大量级数据时尤其明显。PEIV模型有助于提高加权总体最小二乘法的计算效率。本文基于PEIV模型和经典最小二乘准则给出了一种加权总体最小二乘法算法，算法的推导过程简洁，易于理解，迭代过程中无需重构矩阵，减少了矩阵运算量。最后通过仿真试验验证了算法的可靠性。试验结果表明，本文算法可以取得与现有算法相同的参数估计精度且计算效率更高。  相似文献   

近场地震下竖向刚度不同的混合结构动力性能分析   总被引：1，自引：0，他引：1       下载免费PDF全文

马肖彤  包超  张立新  徐芳泽  陆华 《地震工程学报》2019,41(4):860-865

近场地震的动力特性明显不同于远场地震,因此有必要对结构在近场地震作用下的动力性能展开研究。以上部钢结构-下部混凝土结构这类竖向刚度不同的加层混合结构为研究对象,对其在近场脉冲型地震、近场无脉冲型地震及远场地震作用下的动力响应进行研究。结果表明:在多遇、设防、罕遇地震作用下,近场脉冲型地震会使结构的层间位移角、层间剪力、加速度等动力响应均放大并出现超限的情况,而且都比罕遇地震作用下结构的响应增大更明显;在进行近场区加层混合框架结构的设计和建设时,近场脉冲效应会使结构存在不满足规范的情况,有必要对竖向刚度不同的加层混合结构在近场区的适用性进行深入研究。  相似文献