共查询到20条相似文献,搜索用时 15 毫秒
1.
学习向量量化神经网络在多波束底质分类中的应用研究 总被引:5,自引:1,他引:5
利用多波束测深系统获取的反向散射强度数据,应用学习向量量化(learning vector quantization,LVQ)神经网络分类方法实现了对海底砂、砾石和基岩等底质类型的快速、有效的识别。通过比较,证明了该方法能较好地区分出不同海底底质类型。 相似文献
2.
全球导航卫星系统(global navigation satellite system,GNSS)‐声学海底定位是面向海底俯冲带板块形变监测需求提出的一种定位技术,也是建设海洋时空基准网的一种重要技术,有着广阔的应用前景。虽然目前GNSS‐声学海底定位技术的研究成果还不能满足海洋时空基准网的建设需求,但其数据处理方法尤其是声速误差精细处理方法,对海洋时空基准网海底部分(海底大地基准)的建设具有重要借鉴意义。介绍了GNSS‐声学海底定位技术的起源,并将其分为静态测量和动态测量两类,同时将声速误差处理方法作为该技术的发展脉络进行梳理,提炼了该技术的3个发展阶段:仅假设海洋声速垂向分层、考虑声速的时域变化、考虑声速的水平梯度。对于仅假设海洋声速垂向分层的阶段,国外学者采用几何结构对称的方式来削弱声速误差的影响;国内学者则主要对声速以外误差源(杆臂矢量误差、时标偏差、姿态角误差等)进行了研究,并用优化随机模型的方式削弱系统误差对定位的影响。对于考虑声速时域变化的阶段,国外学者利用拟合方法(多项式拟合或三次样条拟合)结合参数平滑约束来解算声速的时域变化量,提高定位的稳定性;国内学者基于此细化了参数拟合的方法(考虑参数长周期项的变化特征),并创新性地提出了水下差分定位算法。对于考虑声速水平梯度的阶段,国内外学者在GNSS‐声学海底定位中解算了声速水平梯度参数,提高了水平方向定位的稳定性,并利用海洋数值模型验证了结果的可靠性。展望了将GNSS‐声学海底定位高精度数据处理方法应用于海底大地基准建设的前景,并引入了小时空尺度声速层析的概念(基于海洋时空基准网的声速误差处理方法),以期解决数值预报模型不能提供小时空尺度产品的问题,进而为水下潜器提供更高精度的声速误差改正服务。 相似文献
3.
4.
5.
Seafloor classification using echo-waveforms: a method employing hybrid neural network architecture 总被引:2,自引:0,他引:2
Chakraborty B. Mahale V. de Sousa C. Das P. 《Geoscience and Remote Sensing Letters, IEEE》2004,1(3):196-200
This letter presents seafloor classification study results of a hybrid artificial neural network architecture known as learning vector quantization. Single beam echo-sounding backscatter waveform data from three different seafloors of the western continental shelf of India are utilized. In this letter, an analysis is presented to establish the hybrid network as an efficient alternative for real-time seafloor classification of the acoustic backscatter data. 相似文献
6.
Volker Janssen 《GPS Solutions》2001,4(3):41-46
Deformation monitoring using GPS is usually carried out by installing and operating a local network of GPS receivers mounted
on the deforming body, e. g., the flanks of a volcano. For continuous monitoring applications a near-real-time, epoch-by-epoch
solution obtained from multi-baseline processing is desired in order to take into account between-baseline correlations and
to detect movements over as short a period of time as possible. In the case of the volcano monitoring application, the sides
of the volcano will block out part of the sky, hence the receivers are not likely to track a lot of satellites that are visible
from all receiver stations at the same time. If the usual base-station/base-satellite approach is used in the baseline processing,
only the common satellites are considered, resulting in the number of possible double-differenced observables being comparatively
low; hence a ot of valuable information may be lost. The proposed method, based on the work by Saalfeld (1999), considers
satellites that are visible from a small number of network stations only. Thus the number of independent double-differenced
observables can be maximized in order to obtain a better solution. A numerical example is given that verifies the improved
solutions that can be obtained using this data processing approach. ? 2001 John Wiley & Sons, Inc. 相似文献
7.
The Global Geodetic Observing System (GGOS) proposes 30–40 geodetic observatories as global infrastructure for the most accurate reference frame to monitor the global change. To reach this goal, several geodetic observatories have upgrade plans to become GGOS stations. Most initiatives are driven by national institutions following national interests. From a global perspective, the site distribution remains incomplete and the initiatives to improve this are up until now insufficient. This article is a contribution to answer the question on where to install new GGOS observatories and where to add observation techniques to existing observatories. It introduces the iterative most remote point (MRP) method for filling in the largest gaps in existing technique-specific networks. A spherical version of the Voronoi-diagram is used to pick the optimal location of the new observatory, but practical concerns determine its realistic location. Once chosen, the process is iterated. A quality and a homogeneity parameter of global networks measure the progress of improving the homogeneity of the global site distribution. This method is applied to the global networks of VGOS, and VGOS co-located with SLR to derive some clues about where additional observatory sites or additional observation techniques at existing observatories will improve the GGOS network configuration. With only six additional VGOS-stations, the homogeneity of the global VGOS-network could be significantly improved by more than \(45\,\%\) . From the presented analysis, 25 known or new co-located VGOS and SLR sites are proposed as the future GGOS backbone: Colombo, Easter Island, Fairbanks, Fortaleza, Galapagos, GGAO, Hartebeesthoek, Honiara, Ibadan, Kokee Park, La Plata, Mauritius, McMurdo, Metsahövi, Ny Alesund, Riyadh, San Diego, Santa Maria, Shanghai, Syowa, Tahiti, Tristan de Cunha, Warkworth, Wettzell, and Yarragadee. 相似文献
8.
Hasanuddin Z. Abidin H. Andreas M. Gamal Ony K. Suganda Irwan Meilano M. Hendrasto M. A. Kusuma D. Darmawan M. A. Purbawinata A. D. Wirakusumah F. Kimata 《GPS Solutions》2006,10(2):75-84
Papandayan is an A-type active volcano located in the southern part of Garut Regency, about 70 km southeast of Bandung, Indonesia. Its earliest recorded eruption, and the most violent and devastating outburst, occurred in 1772. The latest eruptions occurred in the period from 11 November–8 December 2002, and consisted of phreatic, freatomagmatic, and magmatic types of eruption. During the latest eruption period, GPS surveys were conducted at several points inside and around the crater in a radial mode, using the reference point located at the Papandayan observatory, about 10 km from the crater. At the points closest to the erupting craters, GPS displacements up to a few decimeters were detected, whereas at the points outside the crater, the displacements were at the centimeter level. The magnitude of displacements observed at each point also showed a temporal variation according to the eruption characteristics. The results show that deformation during eruption tends to be local, e.g. just around the crater. The pressure source is difficult to be properly modeled from GPS results, due to the limited GPS data available and differences in topography, geological structure, and/or rheology related to each GPS station. 相似文献
9.
Absolute seafloor vertical positioning using combined pressure gauge and kinematic GPS data 总被引:1,自引:0,他引:1
Valérie Ballu Marie-Noelle Bouin Stéphane Calmant Eric Folcher Jean-Michel Bore Jérome Ammann Olivier Pot Michel Diament Bernard Pelletier 《Journal of Geodesy》2010,84(1):65-77
Knowledge of the position and motion of points on the seafloor can be critically important in both fundamental research (for
example, global geodesy and plate tectonics) and for more practical applications such as seismic risk evaluation, off-shore
construction and pipeline monitoring. In the Vanuatu subduction zone, for example, measuring deformation underwater could
provide valuable information for modeling deformation and understanding the seismic cycle. We report a shallow water experiment
in Vanuatu to measure the relative and absolute depth of seafloor points. The experiment differs from previous efforts mainly
in that it uses the height of the sea surface determined by kinematic GPS, allowing us to locate the points in a global reference
frame. The ITRF2005 ellipsoidal height of a seafloor benchmark was determined with a 1-sigma uncertainty of 0.7–2.1 cm. The
estimated ellipsoidal height differs only by a few tenths of a centimeter between measurements made in 2004 and another set
made in 2006. These results are encouraging and open new perspectives for vertical underwater deformation monitoring in shallow
water areas. Sea-surface GPS measurements can also help to reduce the uncertainty in depth difference determination for relative
measurements. 相似文献
10.
11.
近年来,城市地表形变造成的损失备受关注。而基于点的传统大地测量监测技术,在区域性的地表形变监测方面存在局限性。本文提出利用空间大地测量技术监测城市地表形变。联合时序InSAR和全球导航卫星系统(GNSS)技术对深圳和香港海岸线的地表形变场进行监测,同时生成香港网络参考站三维变化的时间序列。由结果可知,位于填海区的地铁建筑区和地基较浅的建筑物,存在明显的沉降现象。 相似文献
12.
13.
2015年尼泊尔地震对珠穆朗玛峰高程的影响,近年一直受到全世界关注。2020年珠穆朗玛峰高程测量在珠穆朗玛峰及周边地区布设了高精度的全球导航卫星系统(global navigation satellite system, GNSS)形变监测网,收集了1999—2020年跨喜马拉雅山脉的32个连续运行参考站(continuously operating reference stations, CORS)的GNSS连续观测数据。利用GNSS数据监测了珠穆朗玛峰周边地区地壳三维形变特征,定量获取了2015年尼泊尔强震对珠穆朗玛峰周边CORS同震位移,以及地震对区域地壳三维形变长期趋势的影响,特别是对该地区垂直形变的影响。研究结果表明,该区域地壳垂直形变由南至北跨喜马拉雅山脉呈明显的阶梯型分布特征;震后印度板块与欧亚板块存在加速汇聚趋势,导致震后地壳隆升速率同步增大。 相似文献
14.
矿区开采致使山体发生形变,由微小形变逐渐演变为大梯度形变,变形量值逐渐增加,导致传统的差分干涉技术无法监测到大梯度形变,针对此问题本文利用多时相合成孔径雷达干涉测量(Multi-temporal Interferometric Synthetic Aperture Radar,MT-InSAR)技术对大梯度形变研究区进行滑坡体形变监测。本文详细阐述了合成孔径差分雷达技术、小基线集以及像素偏移量追踪技术的原理以及适用范围,并使用2017年4月至2019年1月的10景ALOS PALSAR-2数据采用三种方法应用在贵州省兴仁县发耳镇发耳村某矿区的滑坡监测中,充分验证了三种方法相结合的方式可有效监测到由山体蠕动而导致的山体滑坡。 相似文献
15.
从海底控制网设计、布设、测量、数据处理和海洋声速场构建几个方面介绍了海底控制网建设的现状。结合国家海洋战略需求和海洋大地测量技术发展,分析了现阶段海底控制网建设面临的问题:认为目前的海底网规模小,缺乏信息共享,功能单一;设计与布设原则未与控制网等级关联,多为定性描述,缺乏操作性;声速场精度和分辨率偏低;测量和数据处理仅考虑了海底控制点的定位问题,难以满足大区域、高精度海洋PNT(positioning,navigation,and timing)基准网建设需求。据此,利用海洋声道的远程通讯和测距定位能力,提出了建设联合北斗/GNSS(global navigation satellite system)定位和通信导航功能的通导遥一体化深远海PNT基准及服务网络的构想,针对该网络的功能和布放设计、高精度、高分辨率海洋声速场模型的构建、各类PNT基准点的测量和整体网平差处理、海底PNT基准点的自校准和自维护、覆盖水域的位置增强服务、目标和环境的遥测和感知服务等几个关键技术问题,提出了实施方法和设想,以期解决当前海洋控制网大区域建设面临的缺乏通讯、布网原则和测量方法不完善、功能单一等问题,为... 相似文献
16.
针对目前平朔整个矿区的安全状况,本文研究露井联采矿区地表变形宏观监控及预报,建立平朔生产矿区的形变场模型、建构筑物沉降监测和预警预报系统,确保平朔矿区矿山的安全生产。本预警系统通过GPRS移动通信与所有GPS基准站和监测站接收机相连,用户可以利用徕卡GeoMoS软件全天候不间断地监测传感器的控制管理和数据集成,实现可视化和数字分析,通过SMS短消息、E-mail等方式自动报警或者启动计算机程序及其他应急设备,实现地表形变监测预警预报系统的现代化。 相似文献
17.
本文对宝钢引水库大坝的水平位移监测网的布设方案,采用灵敏度和可靠性准则进行了网的优化设计计算,从监测网的质量准则出发,对布网方案作了若干探讨。从二十五期观测资料中选出十三期进行了水平位移计算和变形的几何分析。指出,在变形分析中正确选取基准的重要意义和据多期位移值进行变形预报的一些方法,并定性地讨论了该大坝变形的物理解释。本文所作的工作对类似大坝的水平位移监测和成果处理具有实际意义。 相似文献
18.
生物多样性是生物及其与环境形成的生态复合体以及与此相关的各种生态过程的总和。由于气候变化、人类活动的加剧,生物多样性正在经受前所未有的快速变化,各国政府和相关国际组织已经积极投入到生物多样性监测和保护中。为了解生物多样性的现状和变化规律,全球性、区域性及国家性生物多样性监测网络陆续建立。地球观测组织—生物多样性监测网络(GEO BON)作为全球性网络,目的是建立和完善生物多样性监测核心指标EBV(Essential Biodiversity Variables),推动监测指标的标准化和全球化,为数据共享和大尺度生物多样性变化评估奠定基础。在区域尺度上,欧盟成立了EU BON,亚太地区成立了AP-BON。在国家尺度上,瑞士、英国、日本等均建立了监测网络。中国科学院在"十二五"期间成立了中国生物多样性监测与研究网络(Sino BON),对中国生物多样性的变化开展长期的监测与研究。生物多样性监测依赖于传统调查方法与先进技术结合,如红外相机、基因技术、无人机技术等。遥感能够提供大范围、全覆盖的生物多样性信息,是未来大尺度生物多样性监测的重要手段之一。为此,GEO BON成立了"生态系统结构"组主要研究如何建立基于遥感数据的EBV。Sino BON也引入了无人机近地面遥感技术探讨更大区域的生物多样性监测。未来随着中国综合地球观测系统的完善,Sino BON的地面观测将更好地与卫星数据结合,实现生物多样性天地一体化监测,服务于中国生物多样性保护与评估。 相似文献
19.
为满足新建射电望远镜在单站或多站联合进行的深空探测或射电天文观测对中心坐标精确测定的要求,提出一种利用已知精确中心坐标的望远镜作为参照物,测量地平式射电望远镜中心点坐标的方法和测量数据处理方法。这一方法对场地和设备的要求较低,能够得到毫米级或亚毫米级的位置精度。尤其适合对天线阵列的中心位置进行测量。对国家天文台密云观测站的40 m射电望远镜进行了中心坐标测量,位置均方根误差为2.312 mm,满足了后续的观测工作对其位置的需求。 相似文献
20.
Christophe Vigny 《Journal of Geodesy》1996,70(5):300-306
In june 1990, NASA's Crustal Dynamics Project (CDP) has established a geodetic footprint for the Satellite Laser Ranging (SLR) and Very Long Baseline Interferometry (VLBI) systems located near Fort Davis, Texas using GPS measurements. The purpose of such a footprint is to assess both the tectonic and physical stability of the main observing monuments. Included in the survey were four new monuments forming a 20 to 30 km quadrilateral, as well as four existing monuments near the McDonald Laser Ranging System (MLRS), the Harvard Radio Astronomy (HRA) 85' antenna, and the new 85' antenna of the Very Long Baseline Array (VLBA).This network was partly reoccupied by the University of Texas Austin in may 1992. Three additional sites not observed in 1990 were occupied, two of them being old monuments in the observatory area (Harvard-RM4 and VLBA-SLR), and a new monument 80 km away across the closest active fault near Valentine, Texas.Thanks to existing ties between nearby monuments in the observatory area, the comparison between the two epochs was made possible. Significant motion of more than 1 cm of any of the implied sites over a two year period can be ruled out. Despite this quite reassuring results, smaller displacements cannot be detected mainly because of the poor quality of the 1990 data. Therefore it is strongly advised that a third occupation of the footprint sites takes place in the close future. Such a survey, occuring five years after the first one and three years after the second one, should definitely answer the questions on the Fort Davis area stability at the millimeter per year level. 相似文献