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《Chinese Astronomy and Astrophysics》2021,45(4):559-586
Delingha 13.7 m telescope is one of the most important radio telescopes in China. Since installing the superconducting spectroscopic array receiver (SSAR) and adopting the On The Fly (OTF) observation mode, the telescope has operated for nearly 10 years. During this period, a large number of astronomical observation projects have been carried out and completed, a large amount of astronomical data have been accumulated, and a series of important scientific results have been achieved. This paper introduces the operating status of SSAR in astronomical observations, the problems in operations, as well as the fault phenomena and solutions. The performance test and performance analysis of SSAR are described in detail, including the receiver noise temperature and telescope system noise temperature, image rejection ratio (IRR), receiver stability, beam performance and so on. The updating and development of SSAR are listed, including the automatic adjustment of LO (Local Oscillator) power, the updating of pre-amplification circuits of the sideband separation superconducting mixer, and the optimization of control program, etc. This paper summarizes the experiences and rules, and connects the past with the future, for applying the experiences of the maintenance and operation of SSAR to the next-generation large-scale receiver system. 相似文献
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本文基于多波束测深和高分辨率多道反射地震数据研究了东沙海域深水巨型水下沙丘的特征.巨型水下沙丘发育在230~830m水深的上陆坡范围内,呈斑块状分布.NW-SE向的近海底流体运动不仅冲蚀地层,形成了三条与水下沙丘间隔分布的冲蚀带,为水下沙丘提供了沉积物来源,同时也为水下沙丘的形成提供了动力源.研究区水下沙丘波长(L)范围55~510m,波高(h)范围1.5~20m,二者呈指数关系分布.沙丘的波长随水深增大而增大,波高则在500~700m水深范围内最大.水下沙丘NE—SW向展布的脊线和几何参数关系是与现今水动力条件相平衡的结果. 相似文献
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EM1002S与GeoSwath多波束声纳系统测深精度比较分析 总被引：1，自引：0，他引：1
多波束勘测之前,为了保证多波束成果质量,需要对多波束声纳系统进行一系列设备安装校准和精度评估工作.基于在渤海湾开展的多波束海底地形地貌勘测项目,在项目勘测之前,对EM1002S与GeoSwath多波束声纳系统进行了安装校准,并对2套多波束声纳系统的测深精度进行了比较分析,通过计算得到两套系统之间的最大测深误差为-0.38 m,测深误差主要为0～0.2 m,无超限数据,结果分析显示2套多波束声纳系统的测深精度满足勘测技术要求,为我们调查工作的顺利开展奠定了良好的基础. 相似文献
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多波束测深系统的精度评估方法研究 总被引：2，自引：1，他引：2
在分析了多波束测深系统测量误差来源的基础上，讨论了多波柬测深系统静态精度、相对精度和绝对精度的系统精度评估方法。采用的静态精度评估方法就是在多波柬测深系统静止的条件下考核其对同一位置测量深度的误差；相对精度评估方法就是布设多条交叉重叠的测线，考核交叉重叠点的测深误差；绝对精度评估方法是在多波束测深的同时利用高精度的测深仪测量同一区域，用此参考地理模型来检验多波束测深的精度。根据误差理论，三种精度评估的方法分别从系统稳定性、自符合性和系统误差方面确定各误差源的综合误差，它们是检验多波束测深系统精度是否符合海道测量标准的有效方法。文中给出了系统试验数据的重要结果及设备验收的方法。 相似文献
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Jean-François Oehler Jean-François Lénat Philippe Labazuy 《Bulletin of Volcanology》2008,70(6):717-742
This work presents the first exhaustive study of the entire surface of the Reunion Island volcanic system. The focus is on
the submarine part, for which a compilation of all multibeam data collected during the last 20 years has been made. Different
types of submarine features have been identified: a coastal shelf, debris avalanches and sedimentary deposits, erosion canyons,
volcanic constructions near the coast, and seamounts offshore. Criteria have been defined to differentiate the types of surfaces
and to establish their relative chronology where possible. Debris avalanche deposits are by far the most extensive and voluminous
formations in the submarine domain. They have built four huge Submarine Bulges to the east, north, west, and south of the
island. They form fans 20–30 km wide at the coastline and 100–150 km wide at their ends, 70–80 km offshore. They were built
gradually by the superimposition and/or juxtaposition of products moved during landslide episodes, involving up to several
hundred cubic kilometers of material. About 50 individual events deposits can be recognized at the surface. The landslides
have recurrently dismantled Piton des Neiges, Les Alizés, and Piton de La Fournaise volcanoes since 2 Ma. About one third
are interpreted as secondary landslides, affecting previously emplaced debris avalanche deposits. On land, landslide deposits
are observed in the extensively eroded central area of Piton des Neiges and in its coastal areas. Analysis of the present-day
topography and of geology allows us to identify presumed faults and scars of previous large landslides. The Submarine Bulges
are dissected and bound by canyons up to 200 m deep and 40 km long, filled with coarse-grained sediments, and generally connected
to streams onshore. A large zone of sedimentary accumulation exists to the north–east of the island. It covers a zone 20 km
in width, extending up to 15 km offshore. Volcanic constructions are observed near the coast on both Piton des Neiges and
Piton de la Fournaise volcanoes and are continuations of subaerial structures. Individual seamounts are present on the submarine
flanks and the surrounding ocean floor. A few seem to be young volcanoes, but the majority are probably old, eroded seamounts.
This study suggests a larger scale and frequency of mass-wasting events on Reunion Island compared to similar islands. The
virtual absence of downward flexure of the lithosphere beneath the island probably contributes to this feature. The increased
number of known flank–failure events has to be taken into consideration when assessing hazards from future landslides, in
particular, the probability of landslide-generated tsunamis.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
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沙波形态影响水流结构、泥沙输移及动床阻力。本研究采用多波束测深系统首次精细测量了上荆江典型河段的床面地形,采用改进后的沙波形态量化算法统计了各类沙波形态参数,分析了不同水流强度下沙波形态的变化特征。计算结果表明:(1)测量河段小型与大型沙波的平均波高分别为0.16～0.81和0.96～2.31 m,波长分别为13～27和16～41m;沙波尺度相较于水深较小,小型与大型沙波的波高分别不超过水深的0.045和0.150倍;(2)沙波背流面坡度基本不超过14°,小于泥沙水下休止角,其与陡度之间的关系可以用线性方程描述;(3)中洪水流量对沙波形态尺度的塑造作用强于枯水流量,且对浅水区大型沙波形态尺度的塑造作用强于深水区。本研究量化了天然河流的沙波形态,较好地反映了沙波形态特征,能为大型冲积河流沙波形态的量化及特征参数的统计分析提供参考。 相似文献
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基于斐索干涉仪的直接探测多普勒测风激光雷达 总被引：5，自引：0，他引：5
提出结合多光束斐索(Fizeau)干涉仪和CCD探测器的条纹图像技术,测量地球边界层下的三维风场的直接探测多普勒激光雷达技术.在分析Fizeau干涉仪的物理特性和光谱特性以及影响测量多普勒频移的因数和改进方法的基础上,提出一套切合实际的直接探测多普勒激光雷达系统参数.并利用该参数进行性能评估分析,模拟不同干涉仪参数对风速精度的影响,得出一个优化的干涉仪物理参数.模拟结果显示,系统可以获得小于1 m s-1的水平风速精度.这些分析,为建立实际的激光雷达系统提供设计依据. 相似文献