小波变换在地质雷达干扰波压制中的应用

小波变换方法是近年来发展起来的一种新的数学方法,具有强大的时频分析能力,并广泛地应用到信号处理的各个领域。本文首先简要地介绍了小波变换原理及去噪方法,然后通过阻尼震荡信号、一维地质雷达合成记录和二维地质雷达合成剖面等模型,用db4小波进行了三阶分解,然后根据干扰波的特征进行了小波去噪和干扰波压制,结果表明,小波多尺度分解后,随机噪声主要集中在较低阶的小波细节之中,用小波变换去噪方法,可有效去噪和压制干扰波。对实测的地质雷达资料也进行了处理,取得了较好效果。     

基于高阶谱的混凝土材料断裂声发射特征提取

针对混凝土受载时声发射信号的非高斯特性,提出了一种基于高阶谱技术的声发射信号特征提取的新方法。通过对声发射信号的双谱分析,提取了不同载荷阶段下信号的非高斯特征。以信号双谱幅值的平均值作为特征值,对不同载荷下信号偏离高斯分布的程度进行了定量分析,并讨论了不同载荷强度的混凝土声发射信号的双谱特性及非高斯特征。实验结果表明,提取的特征值反映了信号偏离高斯分布的程度,据此可以作为混凝土受载时断裂临界点的判据。通过与声发射事件等常规参数的比较,可以发现高阶谱参数具有更好的敏感性。     

Study of electromagnetic and acoustic emission in creep experiments of water-containing rock samples

Based on biaxial shear creep tests conducted on rock samples with different water contents, we present the results of our study on the regularities of electromagnetic and acoustic emission during the process of creep experiments in which we have ana-lyzed the contribution of water to the occurrence of electromagnetic radiation. The result shows that in the creep-fracturing course of rock samples, when the water content increases, the initial frequency and amplitude of electromagnetic and acoustic emission also increases, but at a decreasing growth rate caused by loading stress. This can be used as a criterion for the long-term stability of rock masses under conditions of repeated inundation and discharge of water.     

弦乐合弦声信号时频特征的小波包分析

利用小波包分析技术对弦乐合弦声信号进行时频分析，并采用Hilbert变换对小波分解系数时域重构信号进行包络线检波，得到了合弦声信号幅值的时频等高线相平面图．与传统傅里叶谱分析技术相比较，小波变换的时频相平面图能同时反映合弦声信号的构成频率成分及其时域特征．     

短波通信中的数字调制信号识别

针对目前没有有效的方法对短波通信中的调制信号进行识别的问题,提出一种基于小波包变换、高阶累积量和支持向量机的数字调制信号识别新方法.该方法提取信号经小波包变换后各频段的能量值和累积量作为特征向量,利用以支持向量机为基础的多级分类器对其进行调制识别.此分级调制识别方法与其他非分级调制识别方法相比具有较高的识别率.实验表明,针对FSK、PSK等10种调制信号在低信噪比下具有较高的识别能力,该算法在短波通信中的调制信号识别领域有较好的应用.     

Dynamic destabilization analysis based on AE experiment of deep-seated, steep-inclined and extra-thick coal seam

No. 5 coal seam in Huating Coal Mine is a deep-seated, steep-inclined extra-thick coal seam where excavation disturbance is quite frequent. The maximum and minimum principal stresses differ widely. During mining, dynamical destabilization happens frequently and induce tragedies. Based on the comparison between the acoustic emission （AE） experiment on dynamical destabilization of coal rock and the related in situ testing results, this article provides comprehensive analysis on the regular quantificational AE patterns （energy rate, total events） of coal rock destabilization in complex-variable environment. The comparison parameters include dynamic tension energy rate, deformation resistance to compression, and shear stress.     

基于人工智能方法的岩爆预测系统

通过理论分析预测法和现场实测法,建立了一套长期预测和短期预测相结合的岩爆预测系统.长期预测模型是基于神经网络思想,运用国内外相关工程的岩爆资料作为训练样本,建立了小波神经网络预测模型,对工程范围内岩爆发生趋势进行了预测.短期预测模型首先针对监测到的声发射建立小波神经网络模型,对声发射时间序列进行拟合预测;再运用突变理论对预测的声发射建立了岩爆突变预测模型,进而对监测点附近岩爆发生情况进行准确的预测.两种预测模型都运用到了目前人工智能方法中比较新颖的小波神经网络理论,提高了收敛速度,容错能力,保证了预测的效果.通过工程实际运用,建立的岩爆预测系统预测精度高,预测结果与现场情况一致.两套预测模型可以适用于不同的工程阶段,互相验证,具有很好的工程实用性.     

塌陷区岩体断裂失稳声发射信号分析

利用裂隙演化的非平衡统计理论对岩体断裂的非线性动力学问题进行简单描述，借助统计理论和扫描电镜（SEM）手段，对塌陷区围岩断裂失稳的声发射信号的特征参数进行系统分析，为塌陷区失稳位置的反演和准确推断提供了依据。     

Theoretical and experimental analysis on the mechanism of the Kaiser effect of acoustic emission in brittle rocks

The Kaiser effect is formally described as the absence of detectable acoustic emission （AE） events until the load imposed on the material exceeds the previous applied level and is usually used to estimate geostress. By focusing on the heterogeneity of rock material, the mechanism of the Kaiser effect under cyclic loading is analyzed based on statistic damage mechanics. Two groups of granite specimens have been cyclically loaded with two different loading paths to verify the theoretical results. The heterogeneity of rock is the real reason that causes irrecoverable damage on the Kaiser effect of acoustic emission in cyclic loading. The Kaiser effect reflects the damaged state in rocks rather than the previous stress imposed on it. Applications for using the Kaiser effect to estimate geostress were discussed here. It is shown that the commonly used uniaxial loading method for estimating geostress is not in accor- dance with the theoretical and experimental results. The analysis is of importance to use the Kaiser effect correctly for estimating geostress or in other fields. 2008 University of Science and Technology Beijing. All rights reserved.     

应用小波分析研究信号消噪

噪声的去除一直是信号处理中较为关键的技术之一。小波变换在时、频两域都具有表征信号局部特征的能力 ,突破了传统 Fourier分析的局限性 ,很适合检测信号的奇异现象。用 Daubechies小波分别对信号本身的奇异性、噪声的奇异性进行分析 ,结果表明 ,二者具有较大的不同。因而 ,将小波用于信号消噪具有重要的参考价值。     

煤田火区扩散机理与煤岩裂隙发育规律研究进展

煤田火是煤炭开采过程中遇到的主要灾害之一,也是世界性灾害之一.但煤田火区扩散机理及相关影响因素的研究则仍未完善,其中近地表煤岩裂隙的产生和发育为煤田火的燃烧和扩散提供了持续可靠的的供氧通道.国内外学者对煤田火区的燃烧机理、燃烧气体在裂隙中的运移特征与煤田火燃烧特性之间的关系,以及煤岩裂隙发育特征等方面的分析与研究,对于煤田火燃烧的认识存在不足之处,通过分析煤田火区扩散的相关影响因素为煤田火区的治理提供了依据.     

K-ICA算法的舰船直扩通信信号检测

根据舰船通信系统的多天线阵结构,提出一种适合舰船通信的新的非合作直扩信号检测方法,与传统多信号检测方法不同,新方法在预处理部分引入了核独立分量分析技术,克服了多个信号频段重叠、频谱交叉时信号难以分离的难题,提高了后续部分直扩信号的检测与识别准确率,通过仿真分析,验证了该检测方法的有效性.如对决策参数做适当调整,该检测方法同样适用于其他通信信号的检测.     

Characteristics of transmitting channel wave in a coal seam

An embedded underground coal seam carries channel waves of low seismic velocity along a stratigraphic rock-coal-rock sequence. In a homogeneous and isotropic seam, seismic waves propagate as trapped waves within the seam, which leads to propagation of channel waves. We describe how to set up a field test for transmission in order to acquire channel waves in a coal seam. Because channel wave signals are non-stationary in their frequencies and amplitudes, a necessary velocity spectrum and wavelet transformation analysis are applied to interpret the characteristics of channel waves. The advantage of using a wavelet transformation is that different resolutions can be obtained at different times and different frequencies. According to analysis of the seismic signals acquired in the S7 sensor hole, it was clearly shown that the characteristics of channel waves are lower frequencies and attenuation which can guide an effective wave for detecting voids, boundaries and faults in coal seams with strong roofs and floors.     

水煤浆燃烧可吸入颗粒物分布及排放规律

采用冲击式尘粒分级仪对水煤浆锅炉电除尘器前后的细灰粒径分布进行研究.发现除尘器前细灰粒径分布基本上完全符合对数正态分布,相关系数大于0.999;而除尘器后粒径分布更接近罗辛 拉姆勒分布,相关系数约为0.989.由于电除尘器对粗颗粒的除尘效率高于对细颗粒的除尘效率,导致除尘器后PM1、PM2.5和PM10的质量分数均有很大幅度的提高.烟气中细颗粒的质量分数与锅炉负荷有关,负荷降低将导致烟气中细颗粒的质量分数增大.水煤浆锅炉由于燃料中存在的水分,以及燃烧时雾化和结团的影响,PM2.5和PM10的质量分数低于一般煤粉炉     

DSP技术的特点及应用

介绍了DSP技术(器件)的主要特点．总结了DSP在家电、办公设备、控制和通信领域的主要应用及其发展趋势。     

基于小波包变换的直接序列扩频通信窄带干扰抑制技术

为了进一步提高直接扩频通信系统抑制大功率窄带干扰的能力,分别利用多进制小波包和复小波包分解将信号与干扰分离,然后再对滤波处理后的分解结果进行小波包合成.试验结果证明,这两项技术的误比特率性能优于二进制小波包噪声抑制技术     

Wavelet analysis method of harmonics and electromagnetic interference in coal mines

In this study we propose an analytical method based on orthogonal wavelet transforms for detecting harmonic noise and Electromagnetic Interference(EMI)from power supply systems and equipment in coal mines. The method will separate interference from signals through wavelet packet decomposition and then accomplish wavelet packet synthesis towards decomposition results after filtering, to remove harmonic noise and electromagnetic interference. Detailed simulation experiments are presented to study, power harmonics and Electrical Fast Transient Burst(EFT/B)interference and to validate the effectiveness of our proposed method. The experimental results show that the proposed method, suitable for mutant and non-stationary signal detection, can accurately analyze harmonic interference and EMI in coal mines, as well as establish EMI source models and perform underground Electromagnetic Compatibility(EMC)prediction analyses.     

宽带信号匹配滤波的GPU实现及性能优化

从宽带相关的角度推导了基于小波变换的匹配滤波算法及基于快速傅里叶变换(FFT)算法,并分析了算法复杂度,提出了基于图形处理器(GPU)的可配置宽带匹配滤波的软件实现和理论预测与函数实测结合的优化方法.通过优化线程块的维度、绑定纹理寄存器来改进内核函数性能,再使用计算统一设备架构(CUDA)库来降低FFT与极值搜索的时延,并进行了性能优化设计.在性能测试中,文中方法在GPU平台的实现相比8核CPU平台的实现具有3.3倍加速比,其处理时延能够满足宽带匹配滤波的实时性需求.     

低阶烟煤热解特征指数的解析与应用

为评价低阶烟煤的热解反应活性,基于烟煤热重分析提出了一个简单、定量的参数———热解特征指数P.采用热重分析仪对集贤气煤和东荣长焰煤在升温速度为5,15和30℃/min下进行热解,对比了P与其他煤热重分析结果对煤热解反应活性的表征效果.结果表明:TG,DTG曲线和最大失重Wmax不随变质程度或升温速度呈规律性变化,通过TG,DTG曲线和Wmax的变化规律来判断煤种和升温速度对热解反应活性的影响并不合适;当升温速度为30℃/min时,集贤气煤的最大反应速度(dW/dt)max和热解产物释放特性指数R挥发均大于东荣长焰煤,这与煤化学基本理论相悖,所以利用(dW/dt)max和R挥发比较不同煤种的热解反应活性也缺乏准确性;热解特征指数P随升温速度的提高而明显增大,在5,15和30℃/min下,东荣长焰煤的P均略大于集贤气煤,所以P能准确、定量地反映煤种、升温速度对低阶烟煤热解反应活性的影响规律,可用于评价低阶烟煤在整个热解过程中的反应活性.     

水焦浆/水煤浆燃烧特性对比研究

采用热重分析仪研究了水焦浆的着火、燃烧特性,并与兖州烟煤水煤浆、贵州无烟煤水煤浆进行了对比;通过TG-DTG法确定燃烧特征温度;采用Flynn-Wall—Ozawa法进行反应动力学分析．结果表明,水焦浆的着火和燃尽温度界于烟煤水煤浆和无烟煤水煤浆之间;随升温速率的升高,各样品的着火、燃尽温度升高,说明燃烧反应向高温区转移;可燃性指数随升温速率升高,表明燃烧特性提高;由动力学分析知,在同一转化率下,水焦浆的活化能低于烟煤水煤浆和无烟煤水煤浆;水焦浆具有着火难,但一旦着火,燃烧反应剧烈的特点．