Robust stability bounds for nonclassically damped systems with multi-directional perturbations

This paper investigates the stability robustness of nonclassically damped systems with multidirectional perturbations. Bounds on uncertain parameters that maintain the stability of an asymptotically stable, linear multi-degree-of-freedom system with nonclassical damping are derived using specific Lyapunov functions. The explicit nature of the construction permits us to directly express the algebraic criteria in terms of physical parameters of the system. Numerical examples are given to illustrate the effect of the proposed approach.     

薄互层储层预测方法

针对松辽盆地葡萄花油层三角洲沉积薄互层储层的特点．研究不同微相的砂岩与测井特征、地震属性的关系．探讨利用沉积微相、波形特征定性预测砂岩储层发育带的技术。利用地震属性预测技术定量预测储层厚度结果表明，本区整个油层砂岩总厚度与地震属性有很高的相关度．厚砂层的颅测符合率较高。     

非饱和黄土的动剪模量与阻尼比

本文对陕西杨凌地区的非饱和黄土在不同湿度条件下进行动扭剪试验，测定了非饱和黄土的动剪切模量和阻尼比。结果表明，非饱和黄土的动剪切模量随动剪应变的增加而减小，但减小的幅度愈来愈小；在其它条件相同时，最大动剪切模量随含水率的减小而增大，随固结应力的增大而增大；非饱和黄土的动剪切模量与黄土的结构状态及密实状态有关。在相同含水率、固结应力比和固结应力条件下，原状黄土的最大动剪切模量比重塑黄土的稍大，重塑黄土最大动剪切模量随试样干密度的增大而增大；非饱和黄土的阻尼比受含水率、固结应力比、周围压力、干密度等因素的影响，可以反映在其与动剪应变的关系上，在半对数坐标系中动剪切模量与动剪应变具有较为良好的线性关系。     

全密封超薄碳纳米管玻璃平板字符显示器件制造工艺的初步探讨

利用自制的场助热丝化学气相沉积设备，在不锈钢电极的部分选取表面上，摸索出了直接生长碳纳米管（CNT’s）勿须涂敷催化剂的新方法。利用得到的高定向多壁碳纳米管薄膜，研究出一种制造大面积实用碳纳米管阵列场发射（CNT’s／FEA）阴极的新方法。经真空条件下的发射特性测量及SEM等检测手段肯定了这种CNT’s／FEA阴极的实用性。从工艺流程角度出发，初步探讨了静态工作制式下，采用碳纳米管做电极后，实现一种全密封超薄碳纳米管玻璃真空字符（或图像）显示器件的可能性。10多只封离管共显示过3种类型的字型（图像），全部管厚仅为2．7mm。实验结果不仅提供了一种碳纳米管阴极在玻璃真空平板型器件内应用的方法，也摸索出了一条实现小尺寸双色（或多色）字符（图像）静态（或动态）显示的廉价、节能途径。     

高阻尼贝氏体灰铸铁的内耗特征

通过热处理获得高阻尼贝氏体基灰铸铁，测试了其在不同工况（温度、振幅和频率）条件下的内耗特征，并在不同频率条件下与相同碳当量的铸态灰铸铁进行了内耗比较．     

Reverse driving character of 2-DOF closed chain haptic device

Reverse driving character plays an important role in evaluating the performance of a haptic device, and it is the primary rule in the mechanical design. This article mainly investigates the problem of 2-DOF haptic device design for improving reverse driving character. Firstly, a 2-DOF closed chain haptic device is designed in the paper and a physical prototype is produced in the factory; Based on the physical prototype, the 2-DOF haptic device is analyzed with the method of dynamics which is called Lagrangian equation, and the reverse driving character of the haptic device is evaluated by the Generalized Inertia Ellipsoid (GIE) which can be directly illustrated by a graph; With the help of changing the material of some components, the reverse driving character of the haptic device can be improved, so that an appropriate 2-DOF haptic device can be obtained in the design aftertime. __________ Translated from Journal of Beijing University of Aeronautics and Astronautics, 2005, 31(7) (in Chinese)     

Dynamic mechanical properties of particle‐reinforced EPDM composites

The dynamic mechanical property of particle‐reinforced ethylene–propylene–diene monomer (EPDM) matrix composites has been studied by using a dynamic mechanical thermal analyzer (DMTA). The individual composite has been reinforced with the various reinforcing particles as follows: silicon carbide particles (SiCps) of 60 μm in average diameter with various volume fractions (i.e., 10–40%); copper (Cu) and aluminum (Al) particles with 20 vol %; and SiCps with 6 and 36 μm in different average diameters with 20 vol % over the total composite volume. It is shown from the experimental results that the dynamic elastic modulus values increase and the composites with 40 vol % SiCps exhibit higher tan δ values through the entire rubbery phase after the glass transition region compared with the composites with lower particle volume percentages. This shows that the composites with 20 vol % Cu particles have the higher dynamic elastic modulus but the lower peak tan δ value than the composites with other particles of 20 vol % do. Scanning electron microscopy results show that the effective particle volume in the composite with Cu particles is higher than the other composites, although the same particle volume fraction of 20% has been used. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1595–1601, 2003     

基于小波和矩的图像字符特征提取方法研究

提取稳定而有代表性的特征是视频图像字符识别的核心问题之一。文章提出了一种基于小波和矩的图像字符特征向量提取方法。通过对字符图像的不同小波分解子图求取不同的矩特征，构造出字符的特征向量。该方法将小波对图像结构精细特征的把握能力强的优点与矩所具有的平移，缩放和旋转不变及抗噪性强的特性有机地结合起来，特征向量稳定、识别准确率高、算法快、抗噪性能强，且特征提取方法具有类人视觉特点。     

可调式线性油压减振器阻尼孔的精度设计研究

为了优化可调式线性油压减振器阻尼孔的设计，建立了各级阻尼孔的实际尺寸与相应典型工作点最大可调阻尼力之间的流体力学模型，分析了模型中参数之间的相互影响关系，研究了对各级阻尼孔进行加工精度要求设计的方法。算例设计与试验研究表明，对算例油减振器各级阻尼孔的加工精度要求并不很高，但却优化了阻尼孔的设计，保证了油压减振器既有足够的调节余量，又有良好的额定工作性能。     

粘弹性阻尼材料在柔性机械手振动控制中应用的实验研究

本文对一实验用柔性机械手进行了粘弹性约束阻尼处理,以减少柔性振动,改善控制系统的稳定性,提高定位精度.文中给出了测量机械手柔性振动的实验方法,对约束阻尼处理前和处理后的机械手进行了柔性振动、残余振动、重复定位精度等实验研究,并做了比较.