商用扫描仪在天文底片数字化中的测试     

于涌  赵建海  唐正宏  廖石龙 《天文研究与技术》2013,(3):288-292

我国的天文底片数字化工作已正式启动,选取高精度的扫描仪是该工作首要和基本的任务。对Epson公司的V750 Pro和10000XL,以及Phase One公司的PowerPhase FX+扫描仪开展了测试,结果表明,PowerPhase FX+具有较高的扫描精度,一方面,该扫描仪扫描方向的稳定性与线阵CCD方向相当,均优于0.5μm;另一方面,通过UCAC3参考星归算结果显示,尽管PowerPhase FX+的照相式扫描会带来像场畸变,但考虑3阶底片模型后,扫描星像的位置精度较高。对于上海天文台佘山40 cm折射望远镜1987年拍摄的M79底片,扫描星像的位置精度优于0.1″。  相似文献   

Geochronology of the Limu W–Sn–Nb–Ta‐Bearing Granite Pluton in South China     

Zuohai Feng  Zhiqiang Kang  Feng Yang  Jiafei Liao  Chunzeng Wang 《Resource Geology》2013,63(3):320-329

Limu W–Sn–Nb–Ta mining district is located in the Nanling Range W–Sn poly‐metallic mineralization belt in south China. The district includes a number of Sn–Nb–Ta and W–Sn ore occurrences; all of them are spatially associated with granite stocks of a largely‐unexposed pluton, the Limu granitic pluton. A granite sample collected from the Sn–Nb–Ta‐bearing Jinzhuyuan granite stock yields a zircon SHRIMP U–Pb age of 218.3 ± 2.4 Ma, a muscovite ⁴⁰Ar/³⁹Ar plateau age of 212.4 ± 1.4 Ma, and a muscovite ⁴⁰Ar/³⁹Ar isochron age of 213.2 ± 2.2 Ma. Another granite sample collected from the W–Sn‐bearing Sangehuangniu granite stock yields a zircon SHRIMP U–Pb age of 214 ± 5 Ma. The geochronological data provide new constraints on the age of the Limu granite pluton and the timing of the associated W–Sn–Nb–Ta mineralization—at least it sets a reasonable upper age limit for the mineralization of the W–Sn–Nb–Ta ores. The reported ages suggest an active Late Triassic granitic magmatism in Limu area which is part of a regional magmatic event near the end of the Indosinian orogeny in south China.  相似文献   

A new magnetostratigraphic framework for the Lower Miocene (Burdigalian/Ottnangian, Karpatian) in the North Alpine Foreland Basin     

Bettina Reichenbacher  Wout Krijgsman  Yannick Lataster  Martina Pippèrr  Christiaan G. C. Van Baak  Liao Chang  Daniel Kälin  Jürg Jost  Gerhard Doppler  Dietmar Jung  Jérôme Prieto  Hayfaa Abdul Aziz  Madelaine Böhme  Jennifer Garnish  Uwe Kirscher  Valerian Bachtadse 《Swiss Journal of Geoscience》2013,106(2):309-334

Oligocene–Miocene chronostratigraphic correlations within the Paratethys domain are still highly controversial. This study focuses on the late Early Miocene of the Swiss and S-German Molasse Basin (Late Burdigalian, Ottnangian–Karpatian). Previous studies have published different chronologies for this time interval that is represented by the biostratigraphically well constrained Upper Marine Molasse (OMM, lower and middle Ottnangian), Upper Brackish Molasse (OBM, Grimmelfingen and Kirchberg Formations, middle and upper Ottnangian to lower Karpatian, MN 4a–MN 4b) and Upper Freshwater Molasse (OSM, Karpatian–Badenian, MN 5). Here, we suggest a new chronostratigraphic framework, based on integrated magneto-litho-biostratigraphic studies on four sections and three boreholes. Our data indicate that the OBM comprises chrons 5D.1r and 5Dn (Grimmelfingen Fm), chron 5Cr (lower Kirchberg Fm) and the oldest part of chron 5Cn.3n (upper Kirchberg Fm). The OSM begins during chron 5Cn.3n, continues through 5Cn, and includes a long reversed segment that can be correlated to chron 5Br. The OMM-OSM transition was completed at 16.0 Ma in the Swiss Molasse Basin, while the OBM-OSM changeover ended at 16.6 Ma in the S-German Molasse Basin. As the lower Kirchberg Fm represents a facies of the Ottnangian, our data suggest that the Ottnangian–Karpatian boundary in the Molasse Basin is approximately at 16.8 Ma, close to the 5Cr–5Cn.3n magnetic reversal, and thus 0.4 Myr younger than the inferred age of 17.2 Ma used in recent Paratethys time scales. Notably, this would not be problematic for the Paratethys stratigraphy, because chron 5Cr is mainly represented by a sedimentation gap in the Central Paratethys. We also realise, however, that additional data is still required to definitely solve the age debate concerning this intriguing time interval in the North Alpine Foreland Basin. We dedicate this work to our dear friend and colleague Jean-Pierre Berger (8 July 1956–18 January 2012).  相似文献   

Mapping the dynamic degree of aeolian desertification in the Shiyang River Basin from 1975 to 2010     

Jie Liao  Tao Wang  ShaoXiu Ma  Jian Guo 《寒旱区科学》2020,12(3):144-153

The Shiyang River Basin is an area of China that is severly affected by aeolian desertification. Thus, we established an aeolian desertified land classification system for visual interpretation, which classified the Aeolian Desertified Land(ADL)into Slight(SL), Moderate(M), Severe(S) and Extremely Severe(ES) according to the severity. Imagery of Landsat series(acquired in 1975, 1990, 2000 and 2010) were employed to monitor the status, trend and spatial pattern of aeolian desertification, especially to map the overall spatial pattern of ADL dynamics by proposing a new Dynamic Index(DI) in the Shiyang River Basin from 1975 to 2010. The results show a generally decreasing trend from 1975 to 2010. However, the ES ADL kept increasing throughout the whole study period. Moreover, the area of ADLs with different severity increased with increasing severity, this S and ES ADLs dominated characteristics of aeolian desertification was contrary to those sandy lands in eastern China where was dominated by SL and M ADLs. Among the three sub-periods of 1975-1990, 1990-2000 and 2000-2010, the first two were the restoration stage, while the last one was the expansion stage of aeolian desertification. Moreover, all these new ADLs occurred in Minqin County during 2000-2010, indicating a detrimental increase of aeolian desertification in Minqin, and the concentration of ADLs toward the lower reaches of the Shiyang River Basin.The DI works well to identify areas with desertification changes no matter the sub-periods. Moreover, DI results disclosed a stable status of aeolian desertification, and the DI decreased with increasing ADL severity. These results indicate that it will be difficult to control the expansion of aeolian desertification in Minqin County over an extended period of time.Thus, we suggest effective and long-lasting aeolian desertification control programs in the Shiyang River Basin, especially in Minqin, and SL and M ADLs should have priority in facilitating a quick reversal of aeolian desertification.  相似文献   

用激光测距小网的观测资料研究鲜水河断裂带的活动特征     

朱智勤  廖华  李建中 《大地测量与地球动力学》2001,21(2):77-82

利用跨鲜水河断裂带的两个激光测距小网 1985～ 1997年的重复观测资料 ,分析研究了鲜水河断裂带的活动特征。通过对观测资料的数据处理 ,获得了测区较客观的位移场和应变场。形变分析结果表明 ,鲜水河断裂带北段处于蠕动状态 ,南段则处于应变积累的闭锁状态。  相似文献   

基于OpenSSH实现Windows与Linux平台间的安全文件传输     

文自勇  廖亮 《成都信息工程学院学报》2005,20(4):469-474

OpenSSH是一种典型的C/S构架,是一种很实用的网络安全解决方案.这里分析讨论OpenSSH的原理、认证方法及无人值守系统的实现,通过实例说明OpenSSH如何实现Windows与Linux平台间的安全文件传输.  相似文献   

A New Solution Assessment Approach and Its Application to Space Geodesy Data Analysis     

X. Hu  C. Huang  X. Liao 《Celestial Mechanics and Dynamical Astronomy》2001,81(4):265-278

The statistics of the residuals are used in this paper to perform a quality assessment of the solutions from space geodesy data analysis. With the stochastic estimation and the relatively arbitrary empirical parameters being employed to absorb unmodelled errors, it has long been noticed that different estimate combinations or analysis strategies may achieve the same level of fitting yet result in significantly different solutions. Based on the postulate that no conceivable signals should remain in the residuals, solutions of the same level of root mean square error (RMS) and variance–covariance may be differentiated in the sense that for reasonable solutions, the residuals are virtually identical with noise. While it is possible to develop complex noise models, the Gaussian white noise model simplifies the solution interpretation and implies the unmodelled errors have been smoothed out. Statistical moments of the residuals as well as the Pearson chi-square are computed in this paper to measure the discrepancies between the residuals and Gaussian white noise. Applying to both satellite laser ranging (SLR) and global positioning system (GPS) data analysis, we evaluate different parameter estimate combinations and/or different strategies that would be hardly discriminated by the level of fitting. Unlike most solution assessment methods broadly termed as external comparison, no information independent of the data analyzed is required. This makes the immediate solution assessment possible and easy to carry out. While the external comparison is the best and most convincing quality assessment of the solution, the statistics of the residuals provide important information on the solutions and, in some cases as discussed in this paper, can be supported with external comparison.  相似文献   

关于数值求解天体运动方程的几个问题   总被引：4，自引：0，他引：4  

刘林  廖新浩 《天文学报》1997,38(1):75-85

本文讨论三个问题：1.在采用各种非辛（Symplectic）的数值积分器积分天体运动方程时，截断误差将引起人为的能量耗散，这一问题是不能用简单地在相应的力模型中加进一个人为的阻力因子而得以解决的，被歪曲的能量（或数值轨道）必须在积分过程的每一步用能量关系来进行校正，此即能量控制方法．2.当摄动加速度涉及到坐标轴的旋转时，如何在各种积分器中采用能量控制方法．3.对于大偏心率轨道，用数值方法求解相应运动方程时，积分步长必须随运动天体与中心天体之间的距离变化而改变，显然，这对所有积分器都是不方便的，特别是多步积分器．本义给出了一种步长均匀化的处理，可以使上述大偏心率轨道积分问题按定步长计算．  相似文献   

考虑后牛顿效应的二体问题的解和星历计算     

刘林  廖新浩 《紫金山天文台台刊》1997,16(3):156-163

本文给出考虑后牛顿(PN)效应的二体问题解所对应的基本关系式,并仿照开普勒(Kepler)运动,给出星历表计算方法和相应的计算公式以及适用于数值研究中的简单形式。  相似文献   

GPS应用于地球动力学研究的进展   总被引：8，自引：0，他引：8  

宋淑丽  朱文耀  廖新浩 《天文学进展》2003,21(2):95-112

介绍了GPS卫星系统的现代化以及IGS(International GPS Service)的最新研究成果；重点介绍了GPS技术在地球动力学研究中，包括国际地球参考架的建立与维护，固体地球形变和海平面变化的监测，科学卫星轨道的确定以及全球和中国地壳运动、地球定向参数的监测，GPS在大气研究和气象预报中的最新进展；评述了GPS技术目前存在的问题，包括与SLR测量之间存在的系统偏差、GPS技术本身可能存在的周年变化和GPS卫星天线相位中心的变化。  相似文献