CRS共反射面元叠加技术在加蓬地区的应用

CRS共反射面元叠加方法是一种基于非均匀介质,且不依赖于宏观速度模型,由反射面元的位置、倾角、曲率三参数代替叠加速度来刻画反射界面的成像方法。它利用相邻道集数据之间的相似性,尽可能地集中邻域道集的能量参与叠加,从而压制了随机噪声,增强了反射波同相轴的连续性,很好地提高了地震资料的信噪比。加蓬地区的构造复杂、地震采集资料信噪比低,通过CRS共反射面元叠加技术的应用,成像效果较常规地震资料处理方法的成像效果有显著的提高,说明该技术值得在类似复杂区域进行推广和应用。     

一种基于信噪比确定主元个数的方法

多段主元分析(MPCA)是针对间歇进行故障诊断一种行之有效的方法.在MPCA中主元个数的确定是模型的关键,关系到主元模型的可靠性、准确性、完备性.传统的累积方差贡献率(CPV)方法确定主元个数主观性较大并且没有考虑故障因素.为了提高检测性能,有效的提取主元,文中提出一种信噪比(SNR)与MPCA相结合选取间歇过程主元个数的方法,SNR表明的是故障诊断的灵敏度和主元个数的影响关系,在确保主元信息充分描述数据的基础上,该方法考虑了故障的信息对主元个数的影响来选取主元.将此方法应用于青霉素间歇发酵过程故障诊断中,仿真结果表明T2统计量和SPE统计量的响应曲线对故障更加敏感,有效地提高了故障诊断的准确率.     

复杂背景下弱小目标的检测*

复杂背景下低信噪比弱小目标的检测是当今目标捡测的一个热点课题。为了检测到弱小目标,首先对图像进行复杂背景抑制,以达到抑制背景、提高信噪比的目的,然后比较三种方法的背景抑制能力,最后对抑制效果好的图像进行图像分割来进行弱小目标检测。     

基于非理想打印机模型的半色调化图像质量评价方法研究

胶印工艺中印刷的内容需要半色调化成二值图像。为了评价半色调化算法和图像的质量,就要对输出图像的设备建模。现有的建模方法都基于理想打印机,假定输出图像的像素和输出设备的一个矩形区域的状态对应。然而理想打印机反映不了实际胶印工艺中的像素点重叠、极小网点丢失、网点扩大等基本现象。本研究的目标是建立一个面向胶印工艺的打印机模型,用于半色调化图像质量评价算法的研究。     

体导电信道分析与研究

为了降低植入器件的功耗和有效控制植入器件,提高通信效率,提出了一种基于体导电的低功耗数字通信模型。当体导电流的工作频率在kHz级,生物背景信号干扰是微不足道的,体导电信道可近似为加性高斯白噪声信道。从香农信息论出发,推导出二维凋制下的信道容量公式,从而得到推论：在极低信噪比时采用两电平调制就能相当有效地利用信道容量,在高信噪比时,为了充分利用信道容量必须采用多电平调制。利用SystemView对信道进行仿真,证明体导电数字通信的可行性,并得出采取调制方式的必要性,以及误码率和信噪比的关系。     

基于粗糙集理论的图像平滑算法研究

基于粗糙集理论,针对高斯噪声和脉冲噪声,分别采用高斯模板和中值滤波技术,提出了图像平滑算法.这两种算法在去噪的同时,都能够很好地保持图像细节,并且简单易行、处理速度快、使用范围广.通过实验,该算法对灰度图像和彩色图像的处理效果较之传统的处理方法,质量上有较大的提高.     

The research on channel estimation and signal-noise ratio estimation based on minimum error entropy kalman filter for single carrier frequency domain equalization system

In this paper, the channel estimation and signal-to-noise ratio (SNR) estimation technique of single-carrier frequency domain equalization (SC-FDE) system under low SNR in aeronautical multipath channel are studied, a SNR estimation algorithm which is easy to implement in engineering and an improved LS channel estimation algorithm based on Kalman filter using minimum error entropy (MEE-KF) are proposed. This paper first introduces the SC-FDE system and introduces the principle of MEE-KF, and then, the channel estimation flow based on MEE-KF is obtained by combining it with the traditional LS channel estimation algorithm, which makes the estimation results perform better. Simulation results show that after getting more accurate noise variance, the channel estimation results can better follow the changes of the channel after MEE-KF processing, so as to resist the doppler frequency offset effect and make the channel estimation results more accurate, that is the channel response results of the data part can be closer to the real situation, so that the communication performance of SC-FDE system has also been greatly improved.     

Speech Separation Methodology for Hearing Aid

In the design of hearing aids (HA), the real-time speech-enhancement is done. The digital hearing aids should provide high signal-to-noise ratio, gain improvement and should eliminate feedback. In generic hearing aids the performance towards different frequencies varies and non uniform. Existing noise cancellation and speech separation methods drops the voice magnitude under the noise environment. The performance of the HA for frequency response is non uniform. Existing noise suppression methods reduce the required signal strength also. So, the performance of uniform sub band analysis is poor when hearing aid is concern. In this paper, a speech separation method using Non-negative Matrix Factorization (NMF) algorithm is proposed for wavelet decomposition. The Proposed non-uniform filter-bank was validated by parameters like band power, Signal-to-noise ratio (SNR), Mean Square Error (MSE), Signal to Noise and Distortion Ratio (SINAD), Spurious-free dynamic range (SFDR), error and time. The speech recordings before and after separation was evaluated for quality using objective speech quality measures International Telecommunication Union -Telecommunication standard ITU-T P.862.     

一种改进小波收缩阈值的信号消噪算法

小波变换是一种时频分析的方法,在信号处理领域广泛应用.文章在经典的小波软、硬阈值消噪方法的基础上,提出了一种基于小波分析的改进阈值信号消噪方法.Matlab仿真结果表明,此法同时克服了软、硬阈值方法的缺点,其消噪效果较好.     

ADC系统性能测试及提高

本文简介了一种基于FPGA和DSP,对ADC系统进行性能分析并对其转换后的数字进行数据采集的方法。其中性能分析主要是针对ADC的信噪比和无杂散动态范围。同时,主要介绍了ADC系统中时钟、电源、模拟信号输入等方面性能改善的方法。并以此来提高SNR,实现对有效位数和整体性能的提高。