活塞式压缩机吸排气管道的振动与控制

阐述了活塞式压缩机吸、排气管道强烈振动的危害，分析了产生共振的原因，介绍了现场消减管道振动的有效措施。     

Application of Wavelet Packet De-noising in Time-Frequency Analysis of the Local Wave Method

The local wave method is a very good time-frequency method for nonstationary vibration signal analysis. But the interfering noise has a big influence on the accuracy of time-frequency analysis. The wavelet packet de-noising method can eliminate the interference of noise and improve the signal-noise-ratio. This paper uses the local wave method to decompose the de-noising signal and perform a time-frequency analysis. We can get better characteristics. Finally, an example of waveletpacket denoising and a local wave time-frequency spectrum application of diesel engine surface vibration signal is put forward.     

瞬时吸收率检测与高频噪声的剔除

在高分辨率处理过程中，由于地震数据记录中存在着一类并不被人们十分注意的，但影响却十分严重的高频噪声，使得高分辨率处理结果陷入一种“混沌”状态。为此，本文仔细分析和研究了这类噪声产生的物理机制和原因，并提出瞬时吸收率检测与高频噪声剔除的方法。     

光外差系统噪声等效功率的一种测量方法

本文介绍了利用工作于Bragg衍射的Ge晶体声光调制器作为外差系统中的频移器来测量外差系统的噪声等效功率(NEP)的方法。该方法具有测试系统简单、信号光功率、偏频可调的优点。实验测试与理论分析吻合。     

Flood frequency and routing processes at a confluence of the middle Yellow River in China

Floods cause environmental hazards and influence on socio‐economic activities. In this study, we evaluated the historic flood frequency at a confluence in the middle Yellow River, China. A non‐parametric, multivariate, empirical, orthogonal function matrix model, which consists of time correlation coefficients of flood discharge at different gauge stations and flood events was used for the analysis of flood frequency. The model addresses the characteristics of confluent floods such as frequency and the probability in multiple tributary rivers. Flood frequency analysis is often coupled with studies of hydrological routing processes that reduce the flood capacity of the rivers. Flood routing to the confluence were simulated using kinematic wave theory. Results of this flood frequency analysis showed that flooding frequency has intensified in the past 500 years, especially during the 19th century. Flooding in streams above the confluence was more frequent than in streams below the confluence. Over the last 2000 years, concurrent flooding in multiple tributary rivers accounted for 67.5% of the total flooding in the middle Yellow River. Simulation of flood routing processes shows that the decreased flooding capacity and elevated river bed of the shrunken main channel leads to an increased flood wave propagation time (24–52.3 h) in the study area after 1995. The model indicates that human activities, such as constructions of the Sanmenxia Dam, have changed flood routing boundary conditions and have contributed to the increased flood frequency at the confluence. Copyright © 2007 John Wiley & Sons, Ltd.     

AVO反演预处理中的检波器非径向接收能量补偿.

 在地震勘探中，当炮检距非零时，检波器接收方向与反射波传播方向的夹角是非零的（即非径向接收），这一非零夹角必将产生能量损失，进而对AVO反演产生显著影响。为此本文根据Snell定律导出非径向损失补偿公式，以模型实例讨论了非径向接收对反射系数的影响，并提出了一种简单而有效的非径向能量损失补偿方法。对比用该方法做非径向损失补偿前后的AVO反演结果，其差异显著，说明本文方法能够明显改善AVO反演的质量。     

扩频通信系统相位的捕获与跟踪技术

本文讨论扩展频谱通信系统中有关相位的捕获与跟踪技术问题，道德在扩频通信系统原理的基础上结合实际系统中的应用条件，详细分析了捕获的方法、性能特点，给出了比较适用的2种捕获与跟踪原理图。理论分析与实验结果表明，所采用的分析方法和捕获方案是可行的。     

串扰耦合的低频分析有效性及阻抗特性研究

从传输线模型出发，分析了二平行直导线间串扰的低频模型有效性，得出允许3dB误差的条件下，低频模型在工程计算串扰中的电学短线和频率足够小的具体限值；同时分析了端接阻抗大小对串扰耦合的影响。对电磁兼容性中的串扰耦合的工程应用有实际指导和参考意义。     

垂直腔激光器中弛豫振荡频率的优化控制

从垂直腔面发射的半导体激光器（VCSELs）的结构出发，利用增益与载流子密度的广义对数关系，借助小信号分析法，推出了直接调制情形下驰豫振荡频率的严格解析关系。分析指出，量子阱器件的光子寿命并非越短越好，欲提高VCSELs的驰豫振荡频率，除了增加注入电流，提高微分增益等基本途径外，控制器件的结构参数可使驰豫振荡频率达到极大值。同时，自发辐射因子的可控性，以及降低稳态载流子密度，也都是提高VCSELs驰豫振荡频率和拓宽调制带宽的有效措施。