应用ATA的对数周期馈源方案于FAST的可能性探讨     

吴盛殷  熊继衮  吕善伟  张江林  徐祥  南仁东  金乘进 《天文学进展》2004,22(2):179-187

介绍应用于美国凤凰计划的Allen望远镜阵(ATA)的对数周期馈源(LPA)概况，初步给出此种馈源的基本参数及性能，仿真估算了其驻波比和方向图，并结合正在进行中的我国500m孔径球面射电望远镜(FAST)计划，探讨了应用这种宽带馈源的可能性及其限制。  相似文献   

地震台阵滤波及子台分布对聚束效果的影响(Ⅱ)——子台分布及聚束效果的分析          下载免费PDF全文

刘旭  朱元清  佟玉霞 《地震工程学报》2003,25(4):293-297

本假设对于确定的相关系数及子台间距存在一个相干波长，将不同频率、震中距的相关性变化的原因归纳为视波长的变化．对近事件而言，几乎不存在相关系数十分理想的子台间距的区间范围．对非理想相关的台阵，应用S．Mykkeltveit等介绍的增益公式来预测台阵的增益，其效果与实际情况吻合的较好．论述了区域台阵与侦察远处事件的台阵有诸多不同之处．  相似文献   

The Application of ARGO Data to the Global Ocean Data Assimilation Operational System of NCC   总被引：11，自引：0，他引：11       下载免费PDF全文

LIU Yimin  ZHANG Renhe  YIN Yonghong  NIU Tao 《Acta Meteorologica Sinica》2005,19(3):355-365

1. Introduction It is well-known that the state of ocean plays very important role in the climate change. But there is a paucity of the ocean observation data. The data distri- bution in the space, time and different components is very inhomogeneous, even in some areas, there are no any observation data. Hence, it brings some diffcul- ties to the scientists to study many problems relevant to ocean. This situation has been being changed since ARGO (Array for Real-time Geostrophic Oceanogra-…  相似文献   

Crustal transit time monitoring using PKP     

Max Wyss  R. Kind 《Pure and Applied Geophysics》1983,121(2):269-285

The arrival time difference for the AB branch of PKP from deep Tonga earthquakes is constant over years with a standard deviation of ±0.05 seconds at seismographs located 10 to 50 km from each other. If published travel time curves are used to calculate the relative residuals of PKP the standard deviation from the constant mean is improved by approximately 0.01 seconds for AB branch data. For the BC branch, standard deviations of relative travel times of ±0.06 seconds are reduced to less than ±0.05 seconds by calculating relative residuals. We conclude that changes of crustal transit time forP-waves could be resolved, based on careful PKP arrival time measurement at two or more neighboring stations if the changes exceed 0.05 sec and last for more than one year. The conditions for achieving this result are that PKP from Tonga earthquakes is clearly recorded, and that time-keeping is accurate. The data on which these conclusions are based were obtained from the Graefenberg seismograph array, which is located in West Gemany and consists of 13 stations separated by distances of 10 km to 100 km. We propose that relative arrival times of PKP from Tonga could be used in the Mediterranean - Middle East area to search for precursory travel time changes before large earthquakes.  相似文献   

上海地震台阵对2004年12月26日印度洋地震的精确定位   总被引：1，自引：0，他引：1  

于海英  朱元清  王小平  宋治平 《地震地磁观测与研究》2005,26(2):8-13

通过对上海地震台网和上海地震台阵对2004年12月26日印度洋地震的定位结果与NEIC定位结果的比较，得出上海台阵定位结果比上海台网的定位结果更加精确。  相似文献   

河外射电源的结合阵数据的图像处理     

张福俊 Akuj.  CE 《天文学报》1995,36(3):245-251

不同类型的射电望远镜阵的分辨率差异甚大，用它们的数据进行图像处理后所得到的源结构的尺度也不一样。为了得到中间尺度的结构信息，有时我们需要把不同类型的射电望远镜阵的观测数据结合起来再进行图像处理。本文阐述我们把不同类型阵的数据结合时所用的方法；也给出我们使用的方法所获得的结果的实际例子。  相似文献   

数字滤波技术在射电天文测量中的应用     

项英  张秀忠 《天文学进展》2004,22(2):95-103

随着数字技术的发展，数字信号处理芯片的速度越来越快，这为高速数字滤波的实时实现提供了可能。简要阐述了数字滤波的原理，并对两种数字滤波的实现方法进行了分析；给出了数字滤波较模拟滤波的优势；介绍了数字滤波在射电天文测量中的各种应用。  相似文献   

红外焦平面探测器信息获取与预处理电路设计     

范文龙  董峰  傅雨田 《遥感学报》2014,18(Z1):30-34

针对中国科学院上海技术物理研究所研制的1500元红外线列焦平面探测器的输出特性,提出了以低噪声运放为核心的信息获取电路和以FPGA(Field Programmable Gate Array)为核心的数据预处理的设计方案,实现了驱动电路和探测器的良好匹配,较好地发挥了探测器高灵敏度的特性.测试结果表明,该方案不仅对系统获得优于50 mK噪声等效温差的高灵敏度成像起到了重要作用,足够宽的量化设计还保证了系统的动态范围和图像的丰富层次.该设计方案已成功应用在一些其他类型的红外焦平面探测器中.  相似文献   

The Atacama Large Millimeter/Submillimeter Array: overview & status     

Massimo Tarenghi 《Astrophysics and Space Science》2008,313(1-3):1-7

The Atacama Large Millimeter/Submillimeter Array (ALMA) is an international millimeter-wavelength radio telescope under construction in the Atacama Desert of northern Chile. ALMA will be situated on a high-altitude site at 5000 m elevation which provides excellent atmospheric transmission over the instrument wavelength range of 0.3 to 3 mm. ALMA will be comprised of two key observing components—a main array of up to sixty-four 12-m diameter antennas arranged in a multiple configurations ranging in size from 0.15 to ∼18 km, and a set of four 12-m and twelve 7-m antennas operating in a compact array ∼50 m in diameter (known as the Atacama Compact Array, or ACA), providing both interferometric and total-power astronomical information. High-sensitivity dual-polarization 8 GHz-bandwidth spectral-line and continuum measurements between all antennas will be available from two flexible digital correlators. At the shortest planned wavelength and largest configuration, the angular resolution of ALMA will be 0.005″. The instrument will use superconducting (SIS) mixers to provide the lowest possible receiver noise contribution, and special-purpose water vapor radiometers to assist in calibration of atmospheric phase distortions. A complex optical fiber network will transmit the digitized astronomical signals from the antennas to the correlators in the Array Operations Site Technical Building, and post-correlation to the lower-altitude Operations Support Facility where the array will be controlled, and initial construction and maintenance of the instrument will occur. ALMA Regional Centers in the US, Europe, Japan and Chile will provide the scientific portals for the use of ALMA; early science observations are expected in 2010, with full operations in 2012.  相似文献   

机载WIDAS数据的Landsat卫星反照率初步验证   总被引：1，自引：1，他引：0  

何丹丹  焦子锑  董亚冬  张小宁  丁安心  尹思阳  崔磊  常雅轩 《遥感学报》2019,23(1):53-61

随着精细化监测的需求,中高空间分辨率的地表反照率产品逐渐成为气候模型的主要输入。目前,中高空间分辨率反照率产品的验证主要基于地表站点的通量塔观测数据,区域机载飞行数据的验证依然相对较少。因此,本文基于区域机载数据验证Landsat反照率产品。针对内蒙古自治区根河森林试验区所获取的机载红外广角双模式成像仪(WIDAS)多角度反射率数据,应用BRDF原型反演算法估算其反照率,分析了应用机载数据验证中高空间分辨率反照率产品的潜力。2016年内蒙古根河森林试验区机载WIDAS飞行多角度观测的可用多角度范围为25°,以前的研究表明BRDF原型反照率反演算法表现出对小观测角度的反照率反演结果的鲁棒性。因此,机载WIDAS反照率在一定程度可用于星载反照率的验证。首先,基于核驱动模型和各向异性平整指数(AFX)提取了试验区4种MODIS二向性反射分布函数(BRDF)原型;然后,将其作为先验知识应用到根河森林WIDAS机载数据的反照率反演中;最后,用WIDAS反照率和单个地面通量塔观测的反照率对Landsat卫星数据的反照率进行初步验证。验证结果表明Landsat反照率与WIDAS反照率结果较为一致,但略有低估,总体均方根误差(RMSE)约为0.02,偏差为0.0057。在多角度观测范围较小时,BRDF原型的反照率反演算法可为星载地表反照率的验证提供了一种有效的验证手段。  相似文献