抵偿任意带高斯投影平面坐标系选择的研究

根据最小二乘法原理,在使长度综合变形Vs平方之和为最小的条件下直接求得长度变形抵偿值△S1′和相应的抵偿投影面高程Hm′,抵偿零点Y0以及用于测边控制网实量边直接进行抵偿投影改正Vs′的计算公式.另在每千米抵偿投影长度变形小于2.5 cm的条件下明确了抵偿任意带的分带宽度限值为110 km.     

大型对称变带宽方程组的Cholesky分解法

作者针对地球物理数值模拟中常碰到的大型稀疏变带宽方程组的求解问题,介绍了 大型稀疏变带宽矩阵的存储方法及Ｃｈｏｌｅｓｋｙ分解法,该方法的特点是用二个一维数组,其中一个输入时存储对称稀疏矩阵变带宽内的元素,输出时存储Ｃｈｌｏｅｓｋｙ下三角短阵带宽内的元素;另一个存储对称变带宽矩阵对角线元素在前一维数组中的位置,大大节约了所占的计算内存空间。     

旋转多基线摄影光束法平差法方程矩阵带宽优化

提出了一种对近景旋转多基线摄影影像进行重新排序编号从而优化光束法区域网平差法方程系数矩阵带宽的方法。首先,根据影像间的相互联系及其地面覆盖范围,计算每张影像的等效摄站位置;然后根据等效摄站间的坐标关系对其进行重新排序编号,得到各影像的逻辑顺序;最后借助影像的逻辑顺序求解平差法方程系数矩阵实际带宽值。试验结果表明,通过上述方法求出的带宽相对于按照影像原始摄影编号计算出的带宽值有很大改进,一定程度上提升了近景旋转多基线摄影实际应用中计算机的运算效率,减少了平差运算对计算机内存的消耗。     

Numerical Simulation of Bragg Reflection Based on Linear Waves Propagation over A Series of Rectangular Seabed

A numerical model, Evolution Equation of Mild-Slope Equation （EEMSE） developed by Hsu et al. （2003）, was applied to study the Bragg reflection of water waves over a series of rectangular seabed. Three key parameters of the Bragg reflection including the peak coefficient of primary Bragg reflection, its corresponding relative wavelength, and the bandwidth, have shown to be effective in describing the characteristics of the primary Bragg reflection. The characteristics of the Bragg reflection were investigated under the various conditions comprising number, height, and spacing interval of a series of rectangular seabed. The results reveal that the peak of Bragg reflection increases with the increase of rectangular seabed height and number, the bandwidth and the shift value of the Bragg reflection depend on the increase of the rectangular seabed height as well as the decrease of rectangular seabed number, and the relative rectangular seabed spacing in the rang of 3 and 4 could produce higher Bragg reflection. Finally, a correlative and regressive analysis is performed by use of the calculated data. Based on the results of the analysis, empirical equations were established. Our study results can provide an appropriate choice of a series of rectangular seabed field for a practical design.     

短偏移瞬变电磁探测系统研究

短偏移距瞬变电磁法是近年来发展出的新方法,具有信号强、带宽大的特点,现有国际主流装备是面向传统大收发距模式设计开发的窄带系统,研发小收发距模式下的大电流宽带系统,对于推广应用新方法具有重要意义.为此,本文提出大电流快关断发射、低噪声宽频带接收设计方案,攻克超高压恒压钳位技术,自适应可变阻尼技术等核心技术.在同等条件下有效发射功率提升约2.5倍,关断时间压缩近4倍;系统时域噪声水平0.1 nT/s,工作带宽25 kHz.装备系统在增大发射电流和降低噪声的同时,拓展了系统带宽,实现了装备系统与新方法的强匹配.新装备的研发将为我国3000 m以浅矿产资源精细探测做出贡献.

     

测震传输网络带宽需求临界值分析

主要从Miniseed格式以及Steim算法的相关原理出发,分析单台1 s理论最大和最小数据量。根据福建台网数据,对各种仪器取样,然后取平均,得出实际每个包数据量的一般值和最大值。根据现有数据传输方式,除去传输中的理论损耗,计算相关带宽对应的最大数据传输量。在得出地震数据单台1 s数据临界值和带宽最大传输量的情况下,总结计算结果,得出测震传输网络传输带宽临界值。     

Suppressing random noise to broaden the useful bandwidth of seismic reflection data

The signal-to-noise ratio （SNR） of seismic reflection data in many areas is rather poor and conventional two-dimensional filters designed to suppress noise with different moveout from the signal tend to generate artifacts. We have extended a method of multichannel filtering, based on the hypothesis that signals on adjacent channels are similar, for enhancing the SNR on stacked sections. Using only the mid-range frequencies where the SNR is highest, the event trend is found for overlapping windows on the section and the average signal vector is calculated. Then the data from the full bandwidth section are projected onto the spatially varying unit similarity vectors and the results are merged for the overlapping windows. Application of the method to synthetic data containing steeply dipping events and to a stacked section for a marine 2D line has produced good results. The modifications we have introduced carry a small overhead in computing time but they should enable the method to be used effectively even on sections containing steep dips.     

基于光纤麦克尔逊干涉仪的激光稳频研究1

光纤不等臂干涉仪是光纤稳频式激光器的重要部分,它使激光频率的波动反映为干涉仪输出的相位扰动,从而利用干涉仪作为参考可以对激光的频率噪声进行抑制。通过对实验中采用的麦克尔逊光纤干涉仪进行研究,经过理论推导和实验测量,结果表明：采用光纤不等臂干涉仪的方法对激光进行稳频,可以使激光低频处的频率噪声得到较大的抑制,并且激光稳频过程中反馈环路的控制带宽主要受限于光纤不等臂干涉仪的时间延迟之差。     

扩频通信技术及其在地震台网中的应用试验

扩频通信技术是基于信息容量和信息传输差错概率理论而建立的先进的无线通讯方式，多次野外实地证实它具有抗干扰性强、可实现码分多址等优点。通过分析传输试验数据，我们有理由相信扩频通信技术在遥测地震台网中具有较高的应用和广阔的发展前景。     

集成改进Mean Shift和区域合并两种算法的图像分割

Mean Shift算法分割图像时,带宽的大小直接影响分割效果。带宽分为空间带宽和值域带宽。本文根据待分割遥感图像的空间分辨率参考选定空间带宽,基于渐近积分均方差最小原则计算每一波段值域带宽;针对MS算法分割图像时存在过分割问题,提出基于区域面积加权的区域相似度准则和基于区域熵的合并停止准则来合并分割后区域。MATLAB软件3组实验结果表明:本文方法相比EDISON软件能得到更好的分割效果,且能在一定程度上提高遥感影像分割的自动化。