Multidegrees‐of‐freedom effective force testing: a feasibility study and robust stability assessment

This paper presents a feasibility study of multidegrees‐of‐freedom effective force testing (MDOF‐EFT). The study is intended to facilitate the development of a force feedback controller and investigation of performance as well as robustness of MDOF‐EFT. First, the dynamics of MDOF‐EFT systems are analytically investigated. Analytical transfer functions of the control plant, the valve‐to‐force relations, showed that the plant is dynamically coupled and the natural frequencies of test structures are the transmission zeros of the plant. Using a set of model parameters from a previous study, a case study that includes controller design, numerical simulations and robust stability assessment is performed. A decoupling loop shaping (DLS) controller consisting of a pseudo inverse of the plant and second‐order loop shaping controllers is adopted as the force feedback controller. It is shown that the DLS controller provides a stable control system while successfully decoupling the control loops and compensating the control‐structure interaction. Numerical simulations demonstrate that the DLS controller enables tracking of static and dynamic forces for multiple actuators. Robust stability of MDOF‐EFT with the DLS controller is assessed using Monte Carlo simulation. The stochastic simulation results show that the DLS controller is stable and robust, providing sufficient stability margins for uncertain models with maximum 50% errors in the estimated system parameters. This paper demonstrates that MDOF‐EFT is feasible with the DLS controller and can be implemented in experimental laboratories. Copyright © 2013 John Wiley & Sons, Ltd.     

Generalised formulation of composite filters and their application to earthquake engineering test systems

This paper addresses the problem of generating unmeasured kinetic data—and/or providing improvements in existing data—for the enhancement of performance characteristics of earthquake engineering test systems, such as shaking tables, reaction walls and other custom‐made test rigs. The approach relies upon the use of composite filters (CF), a method of data fusion that was originally conceived via transfer function formulation. The current work generalises the CF concept and extends its formulation into the state‐space domain, thereby providing a wider basis for application to test systems and their controllers, including those of a multivariable (coupled, multi‐axis) nature. Comparative simulation studies of shaking table control are presented that demonstrate the design techniques for state‐space CF and also their effectiveness for signal synthesis, noise suppression and performance improvement. Specific examples include the use of CF for displacement demand signal generation, velocity feedback generation and acceleration control. In each case, the essential principles behind CF—output signals with zero bias and zero drift—are consistently upheld. Copyright © 2017 John Wiley & Sons, Ltd.     

Q/Y-D-Ⅰ型气液比检测仪的研制

在泡沫导电机理及其电性试验研究基础上，确定了泡沫气液比在线检测的量化模型，据此设计，研制出适应生产现场使用的在线气液比检测仪；同时，对该型仪器的技术性能参数和广泛的适应性作了深入的分析。     

基桩低应变法三维干扰最小点位置的影响因素及确定方法

通过工程实测信号和数值模拟分析,证明了瞬态集中荷载敲击下,桩顶三维干扰速度信号的强度沿径向先递减后递增,存在干扰最小点,并对比了不同学者提出的干扰最小点位置处的信号。参数分析表明,三维干扰最小点的位置与桩径、桩长、荷载脉宽、桩身混凝土弹性模量、土层剪切波速及土层泊松比等桩、土参数几乎无关,但与桩身混凝土泊松比密切相关,且泊松比越大,干扰最小点的位置越靠近桩中心。给出了干扰最小点位置与桩身混凝土泊松比之间的函数表达式,可方便应用于实际工程。     

一种基于知识的航空影像中道路半自动提取方法

利用线特征算子和多种线状地物跟踪方法建立了一种基于知识的航空影像中道路半自动提取方法。该算法计算量小 ,判断速度快 ,准确率较高 ,并且有较好的适应性。试验表明这是一种良好的道路提取方法。     

Design,simulation, and large‐scale testing of an innovative vibration mitigation device employing essentially nonlinear elastomeric springs

This study proposes an innovative passive vibration mitigation device employing essentially nonlinear elastomeric springs as its most critical component. Essential nonlinearity denotes the absence (or near absence) of a linear component in the stiffness characteristics of these elastomeric springs. These devices were implemented and tested on a large‐scale nine‐story model building structure. The main focus of these devices is to mitigate structural response under impulse‐like and seismic loading when the structure remains elastic. During the design process of the device, numerical simulations, optimizations, and parametric studies of the structure‐device system were performed to obtain stiffness parameters for the devices so that they can maximize the apparent damping of the fundamental mode of the structure. Pyramidal elastomeric springs were employed to physically realize the optimized essentially nonlinear spring components. Component‐level finite element analyses and experiments were conducted to design the nonlinear springs. Finally, shake table tests using impulse‐like and seismic excitation with different loading levels were performed to experimentally evaluate the performance of the device. Experimental results demonstrate that the properly designed devices can mitigate structural vibration responses, including floor acceleration, displacement, and column strain in an effective, rapid, and robust fashion. Comparison between numerical and experimental results verified the computational model of the nonlinear system and provided a comprehensive verification for the proposed device. Copyright © 2014 John Wiley & Sons, Ltd.     

多种勘探测试方法在隧道水文地质勘察中的应用研究以云南省宜良至石林高速公路山冲箐隧道为例

当拟建隧道从地表水体底部穿越时,隧道建设对地表水体的疏干和地表水体渗漏对隧道的施工、运行的影响是建设者特别关注的问题。本次水文地质勘察工作采用了水文地质测绘、水文地质钻探、抽水试验、压水试验、现场多参数水质分析仪测试、室内水质全分析试验、钻孔波速测试等工作手段。通过多种勘探测试方法,查明了隧道区洞身段青草凹水库、清水沟水库的水文地质条件。青草凹水库、清水沟水库地表水与钻孔内地下水水力联系不明显。隧道开挖对青草凹水库、清水沟水库影响小,地表水体对隧道涌水量影响小。采用多种勘探测试方法能较好地查清地下工程与地表水体的相互影响关系。在类似项目的地下水含水介质研究及相关的勘察中具有较大的推广和应用价值。     

The First James K. Mitchell Lecture In situ soil testing: from mechanics to interpretation†

The current use of fundamental mechanics in developing rational interpretation methods for deriving soil properties from in situ test results is reviewed and evaluated. The focus is on some of the most widely used in situ test devices including cone penetrometers with and without pore pressure measurements (CPTU and CPT), self-boring and cone pressuremeters (SBPMT and CPMT), and flat dilatometers (DMT). In situ tests in both cohesive and frictional soils for measuring strength and stiffness properties, in situ state parameters, consolidation coefficients, stress history, and in situ stresses are considered in detail.     

新近沉积粉细砂层地基的试验与评价

通过对邯郸市某车间地基的勘察．分析和探讨了新近沉积粉细砂地层的勘察手段、其物理力学性质，及其利用载荷试验确定承载力的标准取得了较为满意的结果，提出的一些分析方法，对新近沉积的粉细砂地层的勘察具有一定的借鉴作用。     

GPS接收机内噪声水平的评价与检测方法

论文结合某品牌GPS接收机检测实例,提出了GPS接收机内噪声水平分布统计的评价方法,以及在超短基线场内GPS接收机内噪声水平的全新检测方法———多时段旋转检测台法。实例测试,按本方法得到的被测试GPS接收机内噪声水平标准差为0.38mm。由测试实例得到如下结论:本文的GPS接收机内噪声水平评价方法以及检测方法更加合理、可信;在超短基线场内多时段测得的同一基线长度互差应小于2mm;GPS接收机系统软件的抗噪性能对内噪声水平有着非常重要的影响。