ATI-SAR平地相位去除的改进频移法

本文提出了一种改进的频移方法以去除ATI-SAR海洋表面运动探测中的平地相位。首先,介绍和比较两种常规的平地效应去除方法（即,频移方法和轨道参数方法）。然后,对频移方法提出了两项改进措施。第一,干涉相位图被分成几个子块,分别计算相位条纹空间频率。第二,基于在顺轨干涉相位图中陆地区域的相位趋于零的特点,拟合陆地区域的相位与其位置之间的函数关系,进一步校正残余平地相位。结果表明,改进后的频移法去除平地效应的效果得到了很大改善。改进方法的结果与轨道参数法一致性更好,精度趋于轨道参数法的精度水平。     

重复轨道模式InSAR测高中大气水汽影响研究

对流层大气水汽引起的信号延迟是影响重轨In SAR高程测量精度的主要因素之一。为了研究大气水汽对重轨In SAR测高精度的影响及基线估计的校正作用,仿真不同分布模式的水汽模型,对SAR主、辅数据进行干涉处理,反演受水汽影响高程并统计分析控制点高程误差。实验结果表明:在7km×7km的SAR数据成像范围内,当水汽含量分布均匀时,控制点测量精度与无水汽影响高程精度相当,当水汽含量分布在0.142~0.283cm和0~0.502cm时,控制点高程中误差分别为9.84m,21.01m,即在In SAR测高中,基线估计可以校正均匀水汽等系统噪声,但是当水汽分布不均匀时,基线估计不能很好抵消水汽影响,且水汽变化越大,测高误差越大,需要根据外部水汽数据消除水汽对In SAR测量的影响。     

基于自适应抗差最小二乘的DEM数据粗差剔除

数字高程模型(DEM)生产中最关键的环节是质量控制,而粗差是影响DEM质量的重要因素之一。简单介绍了自适应最小二乘估计的原理,并将其用于DEM趋势面拟合中,结果表明该方法具有良好的抗粗差的能力,用含粗差的数据拟合出的曲面与实际地形比较符合。     

长空间基线干涉对辅助的时序InSAR岛礁沉降监测

针对岛礁沉降监测中DEM现势性差、数据不完整等因素造成干涉处理困难的问题,设计了一种利用长空间基线干涉对生成DEM辅助时序InSAR处理的岛礁沉降监测方案。该方案选取空间基线较长且干涉质量良好的干涉对提取相对完整、精确的岛礁区域DEM,并利用该DEM仿真时序干涉处理中所需的地形相位,从而获取差分干涉图,实现精确、稳健的岛礁沉降监测。利用2020年04～09月覆盖某岛礁的12景TanDEM-X影像进行了沉降监测试验,在利用长空间基线像对获取DEM的基础上,得到了试验区沉降速率和沉降量分布图,验证了本方案的可行性和有效性。     

基于变异函数的多波束抽稀间距确定方法

在格网化抽稀方法中,抽稀间距的选取直接影响多波束测深数据抽稀结果和构建海底地形的表征能力。为了合理确定多波束测深数据抽稀间距,将地质统计学中的变异函数理论引入到多波束测深数据抽稀中,由水深变异函数估计海底DEM的精度,得出海底DEM精度与抽稀间距的关系。通过仿真计算表明:如果给定海底DEM的精度,再依据计算得到的拟合水深变异函数参数值,即可确定多波束测深数据抽稀网格间距的大小,该法适用于多波束测深数据抽稀的应用中。     

利用1∶50000高程数据进行ASTER DEM异常修复研究

覆盖近乎全球的30 m ASTER DEM已经对公众开放,为研究全球尺度问题提供了较好的数据基础,但其数据精度和质量在我国区域内存在较多不确定性。研究了利用全国1∶50000高程数据对ASTER DEM数据异常进行修补的技术路线,从而为实现利用多源DEM数据更新现有数据提供质量与可靠性保证,也为我国构建全球基础DEM数据库提供了一种有效的参考。     

基于Hough变换的DInSAR环状地表形变区自动提取

针对当前DInSAR地表形变区检测依赖于人工的现状,提出基于Hough变换的环状地表形变区自动提取方法。该方法在外部DEM的辅助下,由干涉数据获取去地形效应的差分干涉图,在对差分干涉图进行边缘提取的基础上,利用Hough变换实现环状地表形变区的自动提取。采用青海门源震区Sentinel-1A数据和山东济宁矿区ALOS PALSAR数据分别进行环状地表形变区自动提取实验,验证了本文方法的有效性。     

浅析合成孔径声纳与干涉合成孔径声纳

介绍了合成孔径声纳SAS和干涉合成孔径声纳INSAS的基本成像原理、用途以及SAS的自动聚焦算法和INSAS的配准、解缠，说明了它们相对于SAR与INSAR的不同之处和难点，并结合国内外最新的研究成果。指出了它们的发展方向。     

一种基于自适应窗口滤波的DEM获取算法

在分析了一种基于固定窗口滤波的DEM获取算法的基础上,提出了一种自适应窗口滤波的DEM获取算法,改变移动窗口的大小进行分块拟合来反演地面的高程值,获取DEM数据.利用海岸带区域IKONOS卫星影像匹配生成的三维坐标数据集进行了实验,实验证明了该算法的有效性.     

贝叶斯估计在水深格网节点信息估算中的应用

离散数据格网化是目前表达高程和地形方法的前期工作和基础,而格网化的关键是如何利用节点周围的水深值序列推估格网节点水深值及其不确定度值。为解决这一问题,提出了基于贝叶斯估计理论的估计格网节点水深值及水深不确定度的方法,该方法具有独特的估计优势,可以很好的运用测量值和专家经验,得到可靠性较高的节点水深值和水深不确定度,对海底地形显示及数据质量估计具有一定的参考意义。     

海洋地震资料相位控制处理——东海研究实例

为了满足定量解释的需要,地震资料处理必须是高分辨率、振幅保持和相位控制的.面向海洋地震资料的相位控制处理技术包括利用远场信号进行确定性零相位化、Q补偿、预测反褶积及剩余相位校正等.利用模拟远场信号求取确定性去气泡及零相位化算子.此文基于相位控制处理,讨论了海洋地震资料的相位和极性判别方法,探讨了大于24 ms算子长度的预测反褶积对于保持信号形状的必要性,介绍了东海三维地震资料相位控制流程.     

Differential phase estimation with the SeaMARCII bathymetricsidescan sonar system

A maximum-likelihood estimator is used to extract differential phase measurements from noisy seafloor echoes received at pairs of transducers mounted on either side of the SeaMARC II bathymetric sidescan sonar system. Carrier frequencies for each side are about 1 kHz apart, and echoes from a transmitted pulse 2 ms long are analyzed. For each side, phase difference sequences are derived from the full complex data consisting of base-banded and digitized quadrature components of the received echoes. With less bias and a lower variance, this method is shown to be more efficient than a uniform mean estimator. It also does not exhibit the angular or time ambiguities commonly found in the histogram method used in the SeaMARC II system. A figure for the estimation uncertainty of the phase difference is presented, and results are obtained for both real and simulated data. Based on this error estimate and an empirical verification derived through coherent ping stacking, a single filter length of 100 ms is chosen for data processing applications     

On estimating extremes in an evolving wave field

Observations of waves as a time series from a fixed or moored sensor are shown to underestimate the extreme waves occurring in the vicinity. The underestimate arises because of the difference in phase and envelope propagation of surface water waves so that the highest crest, for example, is recorded only when the crest coincides with the envelope maximum at the location of the wave recorder. In addition, the dispersive nature of water waves can lead to the coalescence of groups of waves as longer waves catch up to shorter slower waves, so that the group shape changes markedly as the waves propagate. Moored accelerometer buoys introduce another error that exacerbates the underestimate of the highest crest—the quasi-Lagrangian motion of the buoy leads to flattening of the crests and sharpening of the troughs so that apparent mean water level is raised and thus the height of crests above it is reduced. An analysis approach to correct these underestimates is outlined and tested with observed data against the predictions of extreme values based on narrow-banded random wave theory.     

An experimental implementation of interferometric techniques for sea level variation measurements and reflection coefficient phase determination

A remote interferometric method to measure sea level variations in coastal regions is discussed and results of numerous experimental tests are summarized. A bistatic scheme of measurements is employed with horizontal separation of transmitter-receiver terminals ranging from 400 m to 2700 m. To account for the impact of sea surface roughness, the method incorporates a reflection coefficient phase measuring procedure. The phase of the coherent reflection coefficient measured in the experiments is presented as a function of sea state. The experiments were performed with electronic distance measuring equipment operating at 10-cm wavelength. Preliminary estimates of the measurement accuracy show that errors in sea level variation determination were approximately between 3 cm and 9 cm. These observed errors exceed the theoretical predictions because of various causes, such as technical limitations of the instrumentation, effect of sea surface roughness, etc. More work needs to be done, especially in the area of signal processing, in order to sort out these various effects and reduce their impact on measurement accuracy.     

主能量脉冲反褶积

本文提出的主能量脉冲反褶积方法,旨在保持原反褶积相位特性的同时将有效频带拓宽为期望输出的主能量谱,以期获得更为可靠的地震分辨率。其首先根据地震波的有效频带范围设计出期望输出的主能量谱,然后通过主能量谱滤波获得主能量信号,并以其为输入求取初始的反褶积因子,再在保持初始反褶积因子相位特性的前提下以主能量谱为期望的振幅谱,求取1个优化的反褶积因子,最后即可通过褶积运算获得期望输出的地震信号。     

基于三维相空间法和稳健估算法的ADV流速数据后置处理效果研究

水流是影响藤壶、牡蛎、藻类等水生生物能否成功附着在渔业装备上的重要环境因素,水体流速的变化会改变藻类新陈代谢过程,制约藤壶与牡蛎幼虫大面积扩散。流速测量数据的准确性对研究渔业装备上附着生物的附着机制起到至关重要的作用。声学多普勒流速仪(ADV)是测量水体流速的重要设备。然而,水体中的气泡、大颗粒悬浮物等因素会影响ADV的相关系数和信噪比,从而导致流速数据中产生野点,降低了数据的准确性。本文基于国内外主流算法稳健估算法与三维相空间法,以ADV实际测量的流速数据为例,对比研究两种后置处理方法的检测效果。结果显示,稳健估算法平均检出率为4.95%,峰度系数平均下降77.71%,三维相空间法平均检出率为14.60%,峰度系数平均下降84.05%。综合分析,三维相空间法处理效果较好,其检测准确性高于稳健估算法,但存在过处理现象。建议在处理野点含量低于5%的数据时选用相空间法,而对于野点偏离样本平均值较远的数据时,可以选用稳健估算法。本文对减小流速数据误差,为准确定量研究水流对渔业装备附着生物的附着量与种类影响有着重要的意义。     

The cross-over mechanisms of integral buckle arrestors for offshore pipelines

Local buckling of submarine pipelines is unavoidable under extreme conditions and it can propagate along the pipeline. Thus, arrestors are installed in a periodic placement along the pipeline to limit the extent of catastrophic collapse between two adjacent arrestors. Generally, the integral buckle arrestors are crossed by two modes: the flattening mode and the flipping mode. This paper focuses on the cross-over mechanisms of arrestors by analyzing results from experiments and numerical simulations. Fifteen groups of full-scale and reduced-scale physical experiments are conducted to investigate the effect of local ovality of the downstream pipes on the arrestor performance. Furthermore, an extensive parametric study of cross-over modes of arrestors is performed by FE models to supplement the experimental results. It is found that the local ovality of the downstream pipes impacts the cross-over modes of integral buckle arrestors, which is more likely to deform by ovalization in the same sense as the local ovality. On the other hand, a new formula involving the major geometric and material characteristics of pipes and arrestors is proposed to estimate the flattening mode and the flipping mode of arrestors when the downstream pipes are intact. And the switch point of the two cross-over modes is 0.265.     

The Wheeler diagram,flattening theory,and time

Wheeler diagrams are excellent tools to represent time stratigraphy. These diagrams are produced by considering interpreted surfaces as snapshots of geologic times linked with transit cycles of the base level. The base level, defined in the nineteenth century, can be regarded as an ultimate ‘time’ reference for stratigraphic units. The application of the base level concept to deep marine settings is a more recent development, even though the same definition applies to all depositional environments. Flat timelines are also known as flattening theories can produce similar looking diagrams and have an edge that they operate in 3D. However, flattening of a dataset can be achieved with various techniques, which are reviewed and the optimum algorithm, which has a future application for hydrocarbon and research communities, is improved to honor geological constraints such as faults and horizons. A secondary aspect of the Wheeler diagrams is the dual nature of geological timelines. The diagrams are originally plotted on a relative geological time scale and no formal technique has yet been recommended for time calibration. In this paper, a nomogram approach is proposed to calibrate the timelines. The representation of unconformities that are parallel to bedding planes is another important idea presented in this paper.     

基于Visual C和PC的软件水声调制解调系统

介绍了一种DS/DBPSK调制解调技术方案,该方案采用了具有较强抗干扰、抗衰落和抗多径性能的扩频技术,并结合与信道适应性较好、不需载波恢复的差分相位调制技术,对浅海水声信道造成的干扰进行抑制.在此方法上,基于Visual C(VC)及PC平台设计了一个通用性好的软件水声调制解调系统,利用双缓冲邋和多线程技术机制实现算法实时处理,同时可通过串口通信提供上层应用接口.实验系统验证了扩频和差分调制技术在浅海水声通信中的性能,为水声组网提供了底层支持.海试实验结果表明了系统的有效性.