等高仪光子计数观测资料的处理     

季凯帆 《天文学报》1994,35(2):138-142

在光子计数资料的处理方法设计不完善时，有可能会大大影响光电等高仪的观测结果。本文提出了一套从平滑，搜索到定中心的光子计数资料处理方法，通过与原方法进行了９天（含满月夜）的同步处理比较，新的处理方法得到的星数是原方法结果的１．４８倍，单星测定精度提高０″０２，并且基本克服了天光的影响。  相似文献   

Automatic detection of sub-km craters in high resolution planetary images   总被引：4，自引：0，他引：4  

Erik R. Urbach 《Planetary and Space Science》2009,57(7):880-74

Impact craters are among the most studied geomorphic planetary features because they yield information about the past geological processes and provide a tool for measuring relative ages of observed geologic formations. Surveying impact craters is an important task which traditionally has been achieved by means of visual inspection of images. The shear number of smaller craters present in high resolution images makes visual counting of such craters impractical. In this paper we present a method that brings together a novel, efficient crater identification algorithm with a data processing pipeline; together they enable a fully automatic detection of sub-km craters in large panchromatic images. The technical details of the method are described and its performance is evaluated using a large, 12.5 m/pixel image centered on the Nanedi Valles on Mars. The detection percentage of the method is ∼70%. The system detects over 35,000 craters in this image; average crater density is , but localized spots of much higher crater density are present. The method is designed to produce “million craters” global catalogs of sub-km craters on Mars and other planets wherever high resolution images are available. Such catalogs could be utilized for deriving high spatial resolution and high temporal precision stratigraphy on regional or even planetary scale.  相似文献   

Automated counting of sand‐sized particles in marine records     

《Sedimentology》2018,65(3):842-850

Content and fluxes of ice‐transported sand‐sized and gravel‐sized, lithic particles in marine sediment cores are a common tool used to reconstruct glacial variability. Ice‐rafted debris data sets are currently acquired in several different and often time‐consuming ways, and within various grain‐size fractions. This article proposes a novel workflow using an automated method to count ice‐rafted debris to reduce analysis time and subjectivity. The described method is based on the instrument ‘Morphologi G3’ from Malvern Instruments Limited and includes all pre‐processing and post‐processing steps. This particle characterization tool is an automated microscope combined with a proprietary software package. In this study, the analysis was performed on the 150 to 1000 μ m fraction. If desired, grain counts can be carried out on the entire sand and silt fractions. However, this would result in a considerably greater turnover time. A total of 350 sediment samples from core MD99‐2283, taken on the upper continental slope at the southern part of the north‐east Atlantic margin, were counted with this automated method. In addition, a total of 161 samples were counted manually as a control on the reliability of the scanning. The comparison of automated versus manually counted biogenic and lithic material shows a convincing correlation between the two methods. The turnover time per automatically counted sample is around 20 min, the method requiring less experience and skills than manual counting. The results yield a promising, time‐saving new technique to achieve high‐resolution ice‐rafted debris counting records with acceptable error margins.  相似文献   

MapInfo与ArcView GIS 软件在线体分形分析中的应用   总被引：9，自引：0，他引：9  

朱晓华  查勇 《测绘信息与工程》2002,27(5):4-5

对海岸线、断层系等线体的分形研究来说 ,网格法较为常用 ,但是传统的手工操作不仅费时费力 ,而且精度不高。结合该领域国际分形研究进展 ,系统介绍了 Map Info与 Arc View GIS软件在线体网格分形分析中的具体应用 ,通过分析比较指出该方法不仅简单易操作 ,而且其计算结果的精度更高  相似文献   

地下水^32Si年龄测定方法：液体闪烁计数法     

刘存富  王佩仪 《水文地质工程地质》1997,24(6):5-9

＾３２Ｓｉ是宇宙成因的放射性同位素，其半衰期约为２００ａ，应用＾３２Ｓｉ作为示踪剂测定地下水年龄的范围为５０－１０００ａ。本文介绍了应用Ｆ ｅ（ＯＨ）３共沉法从天然水中提取ＳｉＯ２的制备方法。  相似文献   

一种裂变径迹密度统计的新方法   总被引：1，自引：0，他引：1  

吴堑虹  R.Jonckheere 《大地构造与成矿学》2001,25(1):109-112

介绍了一种新的统计裂变径迹密度方法 ,比较和分析了新方法与传统标准方法的差异 ,得出新方法更为有效、准确的结论  相似文献   

综采放顶煤工作面采出煤量计算方法探讨—以大水头矿为例     

薛韬  王清源 《中国煤田地质》2002,14(2):22-23

综放开采包括综采和放顶煤两个过程,在放顶煤的过程中由于其开采空间,实际落煤损失难以确定,导致工作面采出煤量计算困难。本文以大水头煤矿为例,通过对水分、灰分校正后的统计产量的来代替采出煤量,总结出了校正公式。经生产实际检验,该方法是比较准确的。  相似文献   

多能谱X射线成像技术及其在CT中的应用   总被引：1，自引：0，他引：1  

郝佳  张丽  陈志强  邢宇翔  康克军 《CT理论与应用研究》2011,20(1):141-150

随着探测器技术的不断发展,具有能谱分辨能力的光子计数探测器成为人们研究的焦点,并在X射线成像领域开始得到应用.使用该种探测器,可以将具有较宽能谱分布的X射线分为不同的能区分别进行计数,获得详细的能谱信息及不同能量射线的衰减信息,由此引出了"多能谱成像"的概念.本义介绍了近些年来光子计数探测器技术的发展及其在X射线成像中...  相似文献   

基于三维计盒法的城市空间形态分维计算和分析   总被引：3，自引：1，他引：2  

秦静  方创琳  王洋  李秋颖  张永姣 《地理研究》2015,34(1):85-96

将城市形态分形维数的二维盒维数方法扩展到三维空间,提出了一种三维盒维数计算方法;并且针对以往城市分形研究中人工判定无尺度区不精确的问题,借鉴了二阶导数的方法进行分形无尺度区的自动识别;以扬州市中心城区2003年与2012年两期数据为例,详细介绍了城市三维空间形态分维计盒法的计算过程。实验结果显示,通过二阶导数方法能够有效的自动识别无尺度区;2003年与2012年数据无尺度区线性拟合确定系数R2均在0.996以上,扬州市三维空间形态具有明确的分形特征;2012年较2003年三维分维值的增加表明扬州市城市三维空间利用总体上趋于有效与紧凑。  相似文献   

Condensation particle counting below 2 nm seed particle diameter and the transition from heterogeneous to homogeneous nucleation     

Paul M. Winkler  Aron Vrtala  Paul E. Wagner 《Atmospheric Research》2008,90(2-4):125-ICNAA07

Particle detection by condensation particle counters (CPCs) is ultimately limited by the onset of homogeneous nucleation. At vapour supersaturations around the homogeneous nucleation limit the diameter of critical clusters is typically about 2 nm. It is widely assumed that only particles larger than critical clusters can be activated by vapour condensation and the general detection limit of CPCs is therefore currently accepted to be around 2 nm particle diameter. Using an expansion type CPC with n-propanol as working fluid we investigated the transition from heterogeneous to homogeneous nucleation, clearly showing that particles are activated much before the onset of homogeneous nucleation, even at particle diameters as small as 1.4 nm. For particle diameters below 2 nm we have usually found condensation particle counting to be influenced by the simultaneous presence of ions as generated in a bipolar diffusion charger. In this paper we illustrate how the presence of ions influences particle number concentration measurement and how ions can be removed in order to obtain accurate seed particle number concentrations for particle diameters down to 1 nm.  相似文献