全尺寸径向滑动轴承试验台上轴承油膜参数识别

首先,概述了以不改变全尺寸静待性实验台整体结构为前提。在原有实验台上添加激振装置和测试仪器。增加动特性功能的必要和可能性。其次,概述了脉冲激励、振动测量、数据采集主动特性识别的基本原理,最后将测量结果与理论计算作了比较,并讨论了可能产生误差的各种原因。     

Y3150E滚齿机的数控改造及应用

本文介绍采用数控法改造Y3150E滚齿机,减少并缩短了传动链的数量和长度,提高了滚齿机的加工精度,扩宽了加工范围,并且还可以用于特种圆锥齿轮加工。     

Moisture Effects on the Material Properties of a Jute/Epoxy Laminate: Impulse Excitation Technique Contribution

Natural fibers have enormous potential and offer many advantages. However, the lack of confidence in their structural performance has limited their wider adoption. Among concerns, include susceptibility to higher water absorption. The aim of this paper is to characterize the impact of the water absorption of jute/epoxy composite material using a new approach. This material has a potential to be used in automobile industries (door panels, dashboards, etc.) and in the civil engineering (skins of the sandwich panels in the building). The method of characterization used is original and based on the impulse excitation approach. The mechanical properties identified are correlated to those obtained by classical methods of characterization such as: three points bending and shear tests. Results show clearly that the rate of water absorption decreases physical (resonant frequency) and mechanical properties (Young’s modulus) of jute/epoxy laminate. At the mass saturation, we recorded a decrease in the proper frequency around 10%, and the Young’s modulus in this case loses 28% to 38% of its initial value. In addition, water bath temperature had an important impact on the coefficient of diffusion as well as on the degradation of mechanical properties.     

电容式电压互感器传递过电压试验研究

传递过电压试验是互感器检测试验中比较难以实现的试验,电容式电压互感器由于其主电容较大而使得其传递过电压试验难度很大。利用冲击试验电压发生器,通过对其试验回路的分析研究和计算,得到了满足标准要求的电容式电压互感器的A型传递过电压冲击波,并对电容式电压互感器的传递特性作了初步研究。     

冲动式与反动式汽轮机的优劣比较

文中就冲动式汽轮机和反动式汽轮机在结构特点、蒸汽流动特性以及运行效率上作了详细的分析比较。说明了两类汽轮机在技术及选型中相辅形成的辩证关系。     

Highly stable nonlinear behavior against impulse current of ZnO-Pr6O11-CoO-Cr2O3-Y2O3 varistors

The nonlinear electrical behavior against the impulse stress (400-1200 A) in the ZnO-Pr₆O₁₁-CoO-Cr₂O₃-Y₂O₃ varistors has been investigated with sintering time. The sintering time did have a significant effect on the clamp ratio, which exhibits a surge protection capability. The varistors sintered for 1 h exhibited the best clamp characteristics, in which the clamp voltage ratio was in the range of K = 1.61-1.92 at a lower impulse current region (5-50 A) and was in the range of K = 2.06-2.55 at a higher single impulse current region (400-1200 A). The best electrical stability against the multi-impulse aging stress of 1200 A was also obtained from the varistors sintered for 2 h, where %ΔE_{1 mA} =−1.6%, %Δα =1.3%, and %ΔJ_L =−4.9%.     

自适应滤波器在超宽带穿墙雷达中的应用研究

作为一种新型探测和定位墙后人体目标的方法,超宽带穿墙雷达在军事和民用多个领域得到了广泛的应用。由于目标信号经常被强背景噪声所淹没,为实现动目标检测,需寻求一种有效的背景相消方法以凸显动目标信号,提高动目标检测和定位的精度。在研究回波信号特点的基础上,考虑到无限冲击响应（IIR）滤波器和自适应滤波器的优点,提出采用基于IIR的自适应滤波器背景噪声相消的方法,抑制回波信号中的噪声。为验证方法的有效性,采用该方法对利用SIR20雷达收集的实测数据进行了相关处理。从结果看,该方法能有效抑制背景噪声,凸显目标信号,为目标的检测和定位奠定了良好的基础。     

一种自适应速率的UWB MAC协议

在超宽带（UWB）通信中,跳时冲激无线电（TH-IR）技术具有系统结构简单、成本低、功率小等优点,得到广泛的研究及应用探索。基于TH-IR UWB技术,提出了一种能够保证链路误码率及传输速率的自适应速率跳时（Rate-Adaptive Time Hopping,RATH）介质访问控制（MAC）协议,该协议利用跳时码管理多用户的信道访问,依据接收节点的信干比控制链路的建立,并采用自适应速率算法调节链路的传输速率。NS2平台下的仿真实验表明,与U-MAC等已有的固定速率协议相比较,RATH MAC协议能够使网络有效吞吐量和传输时延得到明显改善。     

基于加权空间离群点度量的随机脉冲噪声降噪算法

针对排序统计类降噪算法在随机脉冲噪声（RVIN）图像降噪过程中,对图像边缘和细节部分噪声识别不够准确以及恢复比较模糊的问题,提出了基于加权空间离群点度量（SLOM）的脉冲噪声降噪算法WSLOM-EPR。该算法以优化的空间距离差为基础,引入图像邻域均值和标准差,建立反映局部边缘细节特征的噪声检测方法,提高边缘细节处噪声的识别精度;然后以精确检测结果为基础,优化保边正则（EPR）函数,提高算法的执行效率,并增强算法保留边缘细节的能力。仿真结果显示,WSLOM-EPR算法在40%到60%噪声密度下对噪声点的误检和漏检综合表现优于对比算法,且能在两者之间保持一个较好的平衡;降噪后的峰值信噪比（PSNR）好于对比算法中的大多数情况,且边缘细节在视觉上更加清晰连续。结果表明WSLOM-EPR算法提高了噪声检测精度,有效地保持了恢复图像的边缘细节信息。     

Interactive relationships between crude oil prices,gold prices,and the NT–US dollar exchange rate—A Taiwan study

This investigation examines the correlations of oil prices, gold prices and the NT dollar versus U.S. dollar exchange rate during 2007/09/03–2011/12/28. Johansen co-integration test, VAR model, Granger causality test, impulse response analysis, and variance decomposition method were used to clarify the interactive relationships among the three variables. These tests and models show that the oil price, gold price and exchange rate remain considerably independent from one another, which implies policymakers should consider the separation of energy and financial policies.