基于BSS的含噪声机械振动信号分离研究

水下航行器的噪声源识别面临的两个问题(:1)无法获得振源信号(,2)测得振动信号有环境噪声影响且振源之间相互耦合。将环境噪声作为一个独立的噪声源,给出瞬时混合信号的盲源分离(BSS)数学模型;利用基于二阶统计特性的两次去相关盲源分离算法,对机械振动加白噪声的混合信号和水池试验实测混合信号进行分离;通过试验验证两次去相关盲源分离方法可以用来解决上述问题。     

基于子频带加权的语音活动检测算法

为了降低噪声及决策导向(DD)参数估计算法的帧延迟特性对语音活动检测（VAD）算法鲁棒性的影响,首先采用两步降噪(TSNR)技术估计算法提高语音瞬变时刻参数估计准确性,并针对语音噪声的频率选择性,通过频带分割,将噪声污染限制到孤立子频带中,构建了由子频带特征与可靠性因子结合提供判别结果的子频带加权VAD算法。实验表明,此子频带加权算法优于Sohn算法、Cho算法以及G.729B等全频带算法。     

生产油管找漏技术在海上油田的应用研究

针对于海上油田的电潜泵油井在生产油管出现破损泄漏而导致产液量急剧下降或关停现象,本文通过一系列研究分析,引入噪声辅助流量的测井作业方式,可实现在生产油井的油管破损泄漏点精确定位;并通过海上某油田现场实际应用,成功实现了破损点位置确定,为该井的下步方案提供了措施方向。     

Region-based Anisotropic Diffusion with Soft Shock Filter for Adaptive Image Enhancement

A region-based anisotropic diffusion with soft shock filter is presented for image noise removal and edge sharpening. Two image processing steps are performed successively： smoothing and sharpening. An image is divided into different regions according to image features： edges, textures and details, and fiat areas. For edges, a shocktype backward diffusion is performed in the gradient direction to the isophote line （edge）, incorporating a forward diffusion in the isophote line direction; while for textures and details, a soft backward diffusion is done to enhance image features preserving a natural transition. Experiments on real images show that this method produces better visual results of the enhanced images than some relevant equations.     

近傍噪声的抑制

由于电子设备的普及和高性能化,设备内部的意外寄生的电磁场噪声干扰问题的处理就变得十分重要。为此开发了一些专门处理此类问题的近傍噪声抑制器,灵活运用它们能很大程度上解决此类电磁干扰。文中着重介绍近傍噪声抑制器的作用、抑制原理、应用方法的注意点及一些产品及应用的事例。     

10kV干式变压器配电房防噪问题的探讨

目前10kV配电房因噪音过大而导致用户投诉的现象日益增多,利用配电房噪音专项摸查结果,分析变压器噪音产生的根源,针对干式变压器噪音问题进行逐一分析并探讨降低噪音的主要途径和措施。     

耦合电容器和电容分压器的噪声与高次谐波

分析了谐波对耦合电容器和电容分压器噪声的影响。结合实际案例,揭示了耦合电容器和电容分压器异常声响与高次谐波的关系,分析了噪声的产生原因并介绍了抑制方法。     

一种新颖的低电源噪声电荷泵

本文提出一种新颖的低电源噪声电荷泵DC-DC变换器。该电路采用电流模控制方式来调整电荷泵充放电电流,并运用差动运放大信号输入时的电流开关特性,使得电荷泵充放电电流不受输入电源电压影响,在稳定状态下和升压过程中都基本维持恒定,有效地减小了输入电流的变化幅度,达到了减小电源噪声的目的。基于Hynix0.5μmCMOS工艺,利用HSPICE对电荷泵整体电路进行仿真验证。结果显示,在2倍模式下电荷泵输入电流仅变化3mA。     

耦合电容器和电容分压器的噪声与高次谐波

分析了谐波对耦合电容器和电容分压器噪声的影响。结合实际案例,揭示了耦合电容器和电容分压器异常声响与高次谐波的关系,分析了噪声的产生原因并介绍了抑制方法。     

Identification of a Distribution of Stiffness Reduction in Reinforced Concrete Slab Bridges Subjected to Moving Loads

The method for identifying arbitrary stiffness reduction in damaged reinforced concrete slab bridges under moving loads is proposed and dynamic signals measured at several points are used as response data to reflect the properties of the moving loads sensitivity. In particular, the change in stiffness in each element before and after damage, based on the system identification method, is described and discussed by using a modified bivariate Gaussian distribution function. The proposed method in this work is more feasible than the conventional element-based damage detection method from the computational efficiency because the procedure of finite-element analysis coupled with microgenetic algorithm using six unknown parameters irrespective of the number of elements are considered. The validity of the technique is numerically verified using a set of dynamic data obtained from a simulation of the actual bridge modeled with a three-dimensional solid element. The numerical calculations show that the proposed technique is a feasible and practical method that can prove the exact location of a damaged region as well as inspect the complex distribution of deteriorated stiffness, although there is a modeling error between actual bridge results and numerical model results as well as a measurement error like uncertain noise in the response data.