多波束.XTF数据结构与.ALL数据结构剖析

通过对SeaBat系列多波束.XTF数据结构和EM系列多波束.ALL数据结构进行剖析,对两种数据结构编码特点、数据记录特点、数据存储方式等进行了比较,明确了这两种多波束系统原始数据的编码规则以及各参数的含义,并成功利用Visual C++编程平台实现了对这两种原始数据的提取。     

C3D测深侧扫声纳探测系统综述

对C3D测深侧扫声纳系统的构成、工作原理、性能、优点、应用等进行了介绍,对基于C3D构建水下探测系统和工程实践进行了研究,对C3D数据处理工具和方法进行了探讨,对C3D的优势、不足和应用前景进行了总结。实测表明,C3D是一款性能优越能够满足多种水下工程需要的声纳探测系统。     

唐海—商都地震台阵剖面下方岩石圈结构

2006年10月到2009年9月,中国地震局地球物理研究所在华北地区布设了250个流动地震台站,本文选取其中一条从唐海经过唐山、三河、北京、张家口到商都的宽频带地震台阵剖面作为研究对象.利用该剖面49个宽频带台站记录的191个远震数据进行了S波接收函数的计算,通过共转换点叠加成像对剖面下方的岩石圈结构进行研究,获得了剖面下方的岩石圈精细结构.Moho界面和岩石圈-软流圈界面清晰可见,剖面下方地壳厚度从西到东逐渐减薄,从42 km逐渐减薄至30 km左右,西部陆块岩石圈厚度从100 km逐渐减薄至70 km,中部和东部陆块岩石圈厚度变化相对平稳,介于60~80 km,表明剖面下方岩石圈遭受了大规模的明显减薄.结合其他地球物理方法研究结果,我们认为剖面下方华北克拉通东部陆块岩石圈减薄主要是由于热侵蚀作用引起的.     

POISSON'S RATIO VARIATIONS OF CRUSTAL MEDIA BEFORE AND AFTER XINYUAN-HEJING MS6.6 EARTHQUAKE IN 2012

We analyzed the variation characteristics of Poisson's ratio in crustal media from January 2009 to December 2012 at 11 fixed seismic stations(for station SCH, it is from January 2006 to December 2012)within an epicenter distance of 200km of the Xinyuan-Hejing M_S6.6 earthquake in Xinjiang on June 30, 2012 using the methods of P wave receiver functions, H-κ stacking of receiver functions, and time sliding window, and obtained the following conclusions: (1)The crustal media's Poisson ratio of five stations in an epicenter distance less than 130km showed a significant and long-lasting decline about 2~3 years before Xinyuan-Hejing M_S6.6 earthquake. Taking the crustal Poisson ratio mean value as reference, the decrease ranges between 0.003 and 0.014, the decrease in 4 stations are more than twice the mean error. The variations of the Poisson's ratio in crust are characterized by "V" shape or "double V" shape. Earthquakes occur at the end of the formation of "V" shape. After the occurrence of earthquakes, the Poisson's ratio continues to rise. The earliest initial fall appeared in July 2009 at WUS station which has the minimum epicentral distance(77km). The Poisson ratio of the crustal media of 6 stations with epicentral distance more than 150km fluctuated up and down around the mean value, and there is no significant decline or persistent low value. (2)We analyzed the arrival-time variations of the quasi-repetitive receiver functions Ps converted wave(t_Ps)of the 3 stations WUS, SCH and XNY and found that the travel times of Ps converted waves became smaller in the crust before the earthquake and increased after the earthquake. (3)Through the comprehensive analysis on the descending process, decline ranges, variations process, duration of Poisson' ratio, the Ps converted waves arrival time variations, the original time of earthquake, and the number of stations, it is inferred that the cause for Poisson's ratio anomalous variations is the change of physical properties of crustal media in the process of earthquake preparation and occurrence. Since the variation characteristics of crustal media may be related to the earthquake magnitude, the size of seismogenic area, the medium properties under stations, and the focal distance, whether the medium variation characteristics exist before and after Xinyuan-Hejing M_S6.6 earthquake will need more earthquake cases analyses. (4)The H-κ stacking of receiver functions is used to calculate the velocity ratio. Because P-wave velocity is given, this method can only be applied when the Ps converted wave velocity of Moho surface of receiver functions changes before an earthquake. With the application of receiver functions to the analysis of more earthquake cases, we can gain more insights into the variation of crustal medium parameters during the seismogenic process. This observation indicates that the receiver function method may become a new approach to detect the Poisson's ratio change of the crustal media before strong earthquake under the condition of high seismic network density.     

一种有效的GNSS接收机载噪比估计方法

提出了一种I支路功率方差比方法(I branch power variance ratio,IBPVR),并详细推导了另外3种载噪比估计方法(NWPR、MM、SNV),比较了这4种方法在强信号和弱信号情况下的跟踪性能。实验结果显示,在载噪比超过50dBHz时,NWPR方法与SNV方法并未出现饱和现象,SNV方法在弱信号情况下会产生估计偏差,NWPR与IBPVR方法的估计性能比较好。     

多波束回声数据的统计与底质分类应用

利用声反向散射数据作海底沉积物分类,是海洋地质学家感兴趣的话题,也是目前多波束声纳应用的一个研究热点。结合胶州湾实际调查数据,探讨了贝叶斯分类方法在该领域的应用。研究结果表明,该方法可以对不同的底质类型进行分类,可以识别未知的底质类型以及对混合在一起的两种不同类型的目标进行分类。     

Wavefield features of teleseismic receiver function in laterally inhomogeneous media

IntroductionSince1980(s,theteleseismicreceiverfunctionhasbeenbroadlyappliedtoexploringthecrustalanduppermantlestructure.Thatthismethoddrawssomanyattentionsisnotonlybecauseitscheapercostandhighverticalresolution,butalsobecauseitcanbeusedforexploringthelateralvariationofthecrustalstructure.IntheUSnationalresearchprogramofthecontinentaldynamicsmuchemphasiswasgiventothereceiverfunctionmethod(Phinney,1989).Uptonow,the1-Dreceiverfunctioninversiontechniquehasbecomesophisticatedandmanypracticalresul…     

多波束数据融合方法研究

针对大型多波束地形调查中存在的多波束测量重叠区和接边区水深的不一致,研究了多波束测量重叠区和接边区的多波束数据的融合方法,分别采用反距离加权法、移动平均法和最小曲率法进行数据融合,比较3种方法的融合精度,认为最小曲率法是这3种方法中最适合用来进行重叠区多波束数据融合的方法.     

A generic swath‐mapping data format

There is a pressing need for standardization of data derived from bathy‐metric swath‐mapping systems. Currently several dozen multibeam and sidescan sonar data formats exist within the oceanographic community, and more can be expected as new systems are developed. Without some standardization of swath‐mapping data formats, the capability for use and integration of data from different systems will be severely compromised.

This paper presents a strategy for organizing swath bathymetry data in a logical modular fashion that will allow data from all current swath bathymetric sonar systems to be stored and accessed in a common fashion. We have chosen the approach of defining compact efficient modules for each logically independent portion of a data record and storing it in a manner that is portable between diverse computer architectures and operating systems. This approach is extensible to accommodate new types of data. Although specifically developed for swath bathymetry, this format is also capable of supporting digital sidescan data and other types of swath data.