分支电路压电阻尼系统频域分析方法

首先通过定义具有一般特性的无量纲电阻抗，推导出了分支电路压电阻尼减振系统频域特性描述的一般表达式。然后．由该一般表达式分别得到了相应于电阻型、电感型、电阻／电感并联型和电阻／电感串连型分支电路压电阻尼系统的频响表达式。最后，进行了电阻／电感串连型分支电路压电阻尼系统频响特性的数值仿真，讨论了其减振的基本特性和系统最佳设计问题。     

Algebraic multigrid methods for dual mortar finite element formulations in contact mechanics

This paper proposes novel strategies to enable multigrid preconditioners within iterative solvers for linear systems arising from contact problems based on mortar finite element formulations. The so‐called dual mortar approach that is exclusively employed here allows for an easy condensation of the discrete Lagrange multipliers. Therefore, it has the advantage over standard mortar methods that linear systems with a saddle‐point structure are avoided, which generally require special preconditioning techniques. However, even with the dual mortar approach, the resulting linear systems turn out to be hard to solve using iterative linear solvers. A basic analysis of the mathematical properties of the linear operators reveals why the naive application of standard iterative solvers shows instabilities and provides new insights of how contact modeling affects the corresponding linear systems. This information is used to develop new strategies that make multigrid methods efficient preconditioners for the class of contact problems based on dual mortar methods. It is worth mentioning that these strategies primarily adapt the input of the multigrid preconditioners in a way that no contact‐specific enhancements are necessary in the multigrid algorithms. This makes the implementation comparably easy. With the proposed method, we are able to solve large contact problems, which is an important step toward the application of dual mortar–based contact formulations in the industry. Numerical results are presented illustrating the performance of the presented algebraic multigrid method.     

基于频率响应函数的动力学模型修正方法研究

概述了国内外动力学模型修正技术的研究状况，研究了近些年发展起来的基于频响函数的动力学模型修正方法；利用航天器振动试验测量所得的频响函数，从理论上介绍了频响函数残差法、设计参数型频响函数法和摄动型频响函数法三种基于频响函数的动力学模型修正方法，为动力学模型修正技术的发展提供参考。     

多项式拟合在接收机频响补偿方面的应用

通过介绍作者在工作中使用多项式拟合进行接收机频响补偿并取得的良好效果，说明多项式拟合是一种非常有用的工具。     

Practical Considerations for Estimating Road Vehicle Frequency Response Functions from Response Data

This paper describes the application of a practical method to estimate the dynamic characteristics (frequency response function) of road vehicles using only on‐the‐road vertical vibration response data measured during nominally constant operating speeds. While several methods exist to estimate these dynamic characteristics, they are generally either inexact or prohibitively resource intensive. A review of two analytical approaches for estimating the frequency response function of road vehicles using only on‐the‐road vibration response data is presented. The first approach is based on the assumption that the road elevation profile takes the form of a specified spectral function. The second approach is based on the random decrement technique. A practical, step‐by‐step guide to undertaking on‐the‐road vehicle vibration measurements is included and provides numerous useful tips and considerations that should be taken into account. An investigation was also undertaken into the minimum record length (i.e. fraction of road length) required to accurately estimate the dynamic characteristics of road vehicles using a Monte Carlo simulation. From the study, it was found that a minimum road length of 10 – 15 km is sufficient to obtain a reasonably accurate estimate. Copyright © 2017 John Wiley & Sons, Ltd.     

低相干函数频响函数的无偏差估计方法

本文详细分析了现有输入噪声模型和输出噪声模型的抗噪声原理,提出了一种能同时抑制输入噪声和输出噪声的无偏差估计模型,它利用二次互功率谱代替通常估计中的自功率谱。使得由于噪声引起的误差可以通过多次平均完全消除。新估计模型的精度与输入噪声和输出噪声的水平无关,仅与统计次数有关。在输入、输出噪声不相关条件下,即使相干函数很低仍能通过多次平均获得具有足够精度的频响函数值。文章最后给出了不同噪声干扰下的(?)估计值、(?)估计值以及本文模型的(?)估计值,并与没有噪声干扰下的H_o 值进行比较。     

LCH 色空间视觉彩色频率响应特性研究

在回顾视觉频率响应研究状况的基础上,以对比敏感度函数CSF为基础,在LCH色彩空间中,经过视觉观察实验,获取了人眼视觉系统对明度、彩度和色调角的频率响应(CSF函数)。研究结果对彩色视觉相关的图像处理、传播、压缩、图像质量评估等具有重要意义。     

基于频率响应灵敏度的车身结构的优化设计

针对车身优化的问题,采用频率响应灵敏度分析来降低车身结构的响应位移。在车身有限元模型的基础上计算频率响应,并求得驾驶员座椅支架处的响应位移曲线,从中找出某频率处的振动峰值;为了降低振动峰值,通过频率响应灵敏度分析选择合适的设计变量进行优化计算。优化后车身关键频率处的响应位移明显减小,提高乘坐的舒适性。     

基于频响函数求逆法的双层圆柱壳体速度场重构

从双层圆柱壳体结构水下噪声实时预报出发,基于在内壳体上布置大量传感器来监测壳体噪声的工程方法,提出了双层圆柱壳体表面速度场实时重构方法。先试验测量到不同工况下内、外壳振动频响函数,并用H4方法进行估计,再用频响函数求逆法得到内、外壳体响应间的振动传递率矩阵。实际应用时,根据内壳体上有限测点的信号实时重构出当前工况下的外壳体表面速度场,为水下噪声的实时计算提供输入。大型舱段模型试验验证表明该方法现实可行,重构出来的外壳体速度场能满足水下噪声实时预报要求。     

关于结构高频响应分析中有限元网格划分的细化标准

本文以周边简支方板在随机面分布力作用下振动加速度响应分析为例，用MSC/NASTRAN有限元软件研究了0-1000Hz和0-2000Hz频率范围内结构模态数和振动加速度响应均方根值随单元大小的变化规律，与解析法结合验证了由波动理论导出的单元细化标准。作为补充提出了结构模态数的单元细化标准。用相同方法对简支圆筒壳体在随机外压作用下1000-2000Hz频率范围内的加速度响应做了研究，本文提出的单元细化标准进一步得到验证。     

《钢弹簧浮置板轨道结构在不同频段的隔振效率》

建立了连续的三维钢弹簧浮置板轨道结构的动力传递特性有限元分析模型,针对不同设计参数和激振频率,研究了该轨道结构的动力传递特性和隔振效率。计算结果表明,所采用的方法可详细解剖浮置板相关设计参数对隔振效率的影响。     

一种液晶调制器相位响应特性线性化的方法

作为一种用途广泛的电光器件,研究并改善液晶调制器的调制特性具有重要意义.本丈通过构造一种对数型的驱动信号,实现了将液晶从0到π的非线性相位响应特性的线性化调制.同时,本文还在实验中发现了,相位响应的线性化程度会随着驱动频率的提高而降低.本文针对该现象,在应用该模型构造周期驱动信号的基础上,提出了将非线性响应映射为线性响应的方法.在不同频率的实验结果表明,从光强信号中获取O～π的线性相位响应是可行的.