Combining Gaia Windows: The Method and Simulations     

Pasi?NurmiEmail author 《Astrophysics and Space Science》2005,298(4):559-575

During the 5-year-observational phase of Gaia several one-dimensional observations will be obtained from the same objects at different epochs and transit angles. Combining the information from all the transits to produce a single two-dimensional image is scientifically important as this will allow to detect much fainter stars in the vicinity of the main source than otherwise possible from single observations on-board the satellite or from individual transmitted patches. Most of the emerging objects will be physical companions, but some background/foreground objects will also be found. The combination procedure further increases the image resolution in the across scan-direction. The procedure consists of combining patches that are stretched back to 2-D windows, only possible since the centroid positions of the windows are known. The initial image window from which the patches originate is not square, but elongated along the scan-direction if the Astro AF11 field of view is used in the current calculations. Transit angles can take any value between 0^∘ and 360^∘. The window combining method is a simple mapping procedure that is fast and should handle all realistic complexities occurring during the Gaia data reduction. The method is not intended to be a perfect image restoration technique, but its purpose is to fulfill the scientific requirement of detecting faint neighboring sources existing in the close vicinity of the main targets. In this study we show examples of the combined windows and illustrate how faint companions around primary targets could be detected. We investigate the performances and limitations of the method and discuss possible complexities that might occur during the final data analysis.  相似文献   

采用最优频率匹配法实现信号的频段滤波处理   总被引：2，自引：0，他引：2  

吕苗荣  古德生 《物探化探计算技术》2005,27(2):166-170

介绍采用最优频率匹配法进行频段滤波的基本原理,通过实际声波的信号分离,考察分离后信号的声音效果,验证了最优频率匹配法的合理性与完整性,并将该方法成功地应用于某矿区井间声波成析成像信号的滤波处理。在此基础上,比较了该方法与常规滤波方法的异同;指出了它们之间的主要差别在于匹配滤波能够从整体上保持分离后信号的协调和各自的独立性,滤波后能够获得比较完整的频段信号和匹配滤波信号;匹配滤波与常规滤波的数值差异主要表现在滤波信号的两端。通过对声波CT信号的匹配滤波处理,实现了该矿区噪声信号的分类,提取了相应的特征参数。这些工作的开展为以后科学合理地进行信号分离,以及信号与噪声的定量化处理创造了条件。  相似文献   

转换波精确无迭代速度分析     

何兵寿  张会星  崔小芹 《物探与化探》2005,29(5):443-446

提出了一种随着速度比与转换点深度的变化而动态抽道的转换波速度分析方法,实现了扫描叠加速度、转换点深度与共转换点道集的一一对应,是一种真正意义上的共转换点无迭代速度分析技术,理论模型试算与实际地震资料处理都证明了此方法的正确性与有效性.  相似文献   

测氡数据软件的设计     

郭俊丽  杨浩 《物探与化探》2005,29(6):554-556

在论述了测氡法的基本原理、工作方法及数据处理的基础上,针对测氡数据放射性衰变的特点和在实际工作中受干扰因素较多等原因,对实测数据进行分析、校正与处理.从实际应用出发,设计开发了可视化和集成化的测氡数据处理软件系统,便于对实测数据进行预处理、校正与成图.  相似文献   

SBR、PAC-SBR反应器处理制药废水污泥变化特征     

李湘凌  周元祥  周娟 《矿产与地质》2005,19(5):565-567

探讨了SBR和PAC-SBR反应器处理盐酸林可霉素原料液生产废水过程中活性污泥特征的变化.随着废水投加量的增加,PAC-SBR反应器的污泥性能始终优于SBR反应器,但是由于盐酸林可霉素原料液生产废水对生物有较强的抑制作用,PAC-SBR反应器和SBR反应器中污泥的活性均发生恶化,COD去除率已明显下降,单独采用SBR或PAC-SBR法处理已难以达到排放标准,必须进行工艺的组合.PAC-SBR反应器较SBR反应器在污泥性质及处理效率上均有一定的改善,对处理盐酸林可霉素原料药生产废水有一定的优势.  相似文献   

基于栅格数据提取主骨架线的新算法     

杜世宏  杜道生  樊红  万幼川 《武汉大学学报(信息科学版)》2000,25(5):432-436

详细介绍了基于栅格数据的面状地物主骨架线的提取算法。该算法具有较快的处理速度和较强的适应性及内存需求少的优点 ,同时用该算法所提取的主骨架线为最优 (最长 )骨架线 ,可用于面状地物注记的自动配置。  相似文献   

数字制图中生僻汉字信息处理     

刘新贵  阚映红 《测绘与空间地理信息》2000,23(3):6-7,10

在 1:2 50 0 0 0地图数据库生僻汉字统计的基础上 ,通过生僻汉字的编码、字模的制作、代码的编制、输入法的生成以及矢量汉字的使用等 ,提出了在GBK的基础上进行再扩展的技术和方法 ,从而解决了数字制图中生僻汉字处理的问题。  相似文献   

GIS中数字化数据误差的分布检验与处理     

童小华  史文中  刘大杰 《武汉大学学报(信息科学版)》2000,25(1)

对ＧＩＳ中手工地图数字化中的数据误差进行了系统分析和各种分布检验,认为数字化数据误差可能服从ｐ≈１．６的ｐ－范分布。在此基础上,探讨了数字化数据误差处理的ｐ－范平差,并与最小二乘平差进行了比较。  相似文献   

The effect of clouds on aerosol growth in the rural atmosphere   总被引：1，自引：0，他引：1  

Colin D. O'Dowd  Jason A. Lowe  Michael H. Smith 《Atmospheric Research》2000,54(4):1331

Measurements of accumulation mode aerosol in the atmospheric boundary layer under cloudy and cloud-free conditions, and in the lower free troposphere under cloud-free conditions, were conducted over the rural northwest of England. Normalised size distributions in the cloud-free boundary layer (CFBL) and the cloud-free free troposphere (CFFT) exhibited almost identical spectral similarities with both size distributions possessing a concentration peak mode-radius of ≈0.05 μm or less. By comparison, aerosol distributions observed in cloudy air exhibited a distinctive log-normal distribution with mode-radii occurring at ≈0.1 μm concomitant with a local minimum at ≈0.05 μm. The consistent and noticeable difference in spectral features observed between cloudy and cloud-free conditions suggest that a greater amount of gas-to-particle conversion occurs on cloudy days, presumably through in-cloud aqueous phase oxidation processes, leading to larger sized accumulation mode particles. Apart from the distinct difference between cloudy and cloud-free aerosol spectra on cloudy days, aerosol concentration and mass were observed to be significantly enhanced above that of the ambient background in the vicinity of clouds. Volatility analysis during one case of cloud processing indicated an increase in the relative contribution of aerosol mass volatile at temperatures characteristic of sulphuric acid, along with a smaller fraction of more volatile material (possibly nitric acid and/or organic aerosol). Growth-law analysis of possible growth mechanisms point to aqueous phase oxidation of aerosol precursors in cloud droplets as being the only feasible mechanism capable of producing the observed growth. The effect of cloud processing is to alter the cloud condensation nuclei (CCN) supersaturation spectrum in a manner which increases the availability of CCN at lower cloud supersaturations.  相似文献   

探空资料质量控制及可视化处理系统(HBTK)的研究与应用   总被引：1，自引：0，他引：1  

张峻 《气象》2000,26(3):33-36

介绍了“探空资料质量控制及可视化处理系统 ( HBTK)”的基本功能、设计技术和应用效果 ,实践证明该系统不受测站个体差异的影响 ,具有很好的实用性。  相似文献