ICESat-2 ATL08去噪算法实现及精度评价   总被引：1，自引：0，他引：1  

曹彬才  方勇  江振治  高力  胡海彦 《测绘通报》2020,(5):25-30

针对光子计数激光点云特点，研究实现了ICESat-2卫星ALT08技术文档点云去噪算法与精度评估。首先逐点计算目标点邻域范围内点的总数作为局部密度值，由于信号通常比噪声在空间分布上更集中，密度直方图常呈噪声在左、信号在右的双峰特点；然后通过峰值计算、距离判断等计算噪声与信号高斯函数初值，并采用高斯函数加期望方差最大算法拟合两个精确的波形位置；最后将双高斯函数交点位置作为去噪阈值，小于阈值的点标记为噪声，大于阈值的为信号。通过MABEL数据的试验结果表明：当信号噪声呈现典型双峰分布特征时，算法去噪效果优秀，精度优于98%，处理不符合双峰特征数据时效果变差。  相似文献   

Some results from phytoplankton counting intercalibrations   总被引：34，自引：0，他引：34  

Dr. Eugen Rott 《Aquatic Sciences - Research Across Boundaries》1981,43(1):34-62

Phytoplankton samples from 7 different lakes were processed in 2 intercalibration series using Utermöhl's sedimentation method. Total biomass volumes obtained by most of the investigators give reliable results in respect to the mean. Numbers of individuals and mean volumes of selected species obtained by the different participants were compared and show larger variations than the overall results. Therefore a certain delimitation of particular sources of errors was tried in the 2nd intercalibration series by giving recommendations for the different steps of the whole procedure.  相似文献   

浙江萤石矿床的空间分布   总被引：3，自引：2，他引：1  

麻土华  朱兴盛  李长江 《矿床地质》2000,19(3):281-288

本文应用单元递归法和分形丛集分析方法对浙江３个不同区域范围内６２９个萤石矿床（点）的空间及储量数据进行统计分析,提示了这些矿床在空间上遵循分形丛集分布,在０．５～１５ｋｍ尺度内具有较一致的分维数,分别为０．５３９、０．５５２和０．４０５,表明这些矿床尽管成矿地质环境及赋矿岩性没相同,但可能有着同一的成因机制;萤石矿床丛集分布形成的密集区的空间尺度为２５０ｋｍ＾２左右。在矿产勘查中可以依据这一尺度来  相似文献   

多源日志存储和分析在网络事件关联中的实际应用     

孙毅  赵泽宇  闫华 《中国海洋大学学报(自然科学版)》2008,(Z1)

网络管理要对网络事件有全面认知。目前网络管理的常用手段主要依靠对所有网络设备和网断的系统信息检测和读取信息,而网络信息庞杂且时刻变化,对信息存储和解读提出了很高的要求和挑战。为了解决上述问题,基于Loglog算法提出了1种全新的网络运行日志存储和恢复算法,并且结合实际运行环境给出1个应用模型,扩展网络管理和维护的时间跨度和空间维度。同时,算法结合网络日志的特点加之最大熵方法的过滤器,并在网络认知关联上有实际的应用,对网络信息挖掘有理论联系实际的意义。  相似文献   

Analysis of Ac in seawater by delayed coincidence counting     

Timothy J. Shaw  Willard S. Moore 《Marine Chemistry》2002,78(4)

The activity of ²²⁷Ac in seawater was determined using a delayed coincidence counting technique based on the measurement of the short-lived daughter ²²³Ra (half-life of 11 days). Two 180-l aliquots of Ac free seawater from surface waters of the California borderlands were spiked with Harwell Uraninite standard and the added Ac and Ra were extracted on Mn-fibers. The measured activities on the fibers agreed to within 5% of the equilibrium Ac activity of the spike addition, well within the 2σ counting error of 7% for the measurements. Thus, any recovery error was indistinguishable from counting error. Large volume samples were collected from the water column of the Eastern North Pacific in December of 1998 and processed through Mn-fiber columns. The ²²³Ra activities on the fibers were measured four or more times over a period of 2 months by the technique of [J. Geophys. Res. 101 (1996) 1321] to determine if the activity of ²²³Ra was wholly supported by ²²⁷Ac. In most cases, no significant differences in ²²³Ra activity were observed during repeated counting of the same sample, again implying that ²²³Ra was supported wholly by ²²⁷Ac. In samples where unsupported ²²³Ra were present, samples were counted beyond five half live of the ²²³Ra (>60 days). Two depth profiles of ²²⁷Ac in the Eastern North Pacific showed similar shape and activity to profiles in the Western and Central Pacific measured with alpha-spectrometry by [Nature 310 (1984) 486). Surface waters of the Southern Ocean were relatively enriched in ²²⁷Ac compared to Eastern North Pacific waters, possibly indicating export of the parent ²³¹Pa from Atlantic surface waters or upwelling.  相似文献   

Validation of acoustic echo counting for studies of zooplankton behavior     

de Robertis  Alex 《ICES Journal of Marine Science》2001,58(3):543-561

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Determination of dead-time in photon counting photometers by a polarimetric method     

David Clarke  Gerry Deighan  Gillian Fry  Susan Goodsir  Donald Macleod 《Astrophysics and Space Science》1996,239(2):229-235

Experiments are described which demonstrate that the dead-time constant associated with a photon counting stellar photometer/polarimeter is readily determinable by the application of the Malus law. It is also proposed that corrections for dead-time losses should be applied by an iteration technique to the exact equation rather than using the available approximation formulae.  相似文献   

OPTIMA: A Photon Counting High-Speed Photometer     

C. Straubmeier  G. Kanbach  F. Schrey 《Experimental Astronomy》2001,11(1):157-170

OPTIMA is a small, versatile high-speed photometer which is primarily intended for time resolved observations of young high energy pulsars at optical wavelengths. The detector system consists of eight fiber fed photon counters based on avalanche photodiodes, a GPS timing receiver, an integrating CCD camera to ensure the correct pointing of the telescope and a computerized control unit. Since January 1999 OPTIMA proves its scientific potential by measuring a very detailed light-curve of the Crab Pulsar as well as by observing cataclysmic variable stars on very short timescales. In this article we describe the design of the detector system focussing on the photon counting units and the software control which correlates the detected photons with the GPS timing signal. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

扇贝苗规格识别与计数统计装置的设计研究     

卢宏博  李明智  李尚远  孙天泽  曲春虎  曲文龙 《海洋科学》2021,45(2):59-67

本文针对目前底播扇贝苗种时,在海上规格识别与计数统计用工量大、劳动强度高、破损率高及统计误差大等问题,设计了扇贝苗规格识别与计数统计装置,该装置主要由初级分拣机构、差速排队传送装置和规格识别与计数统计系统3部分组成。为确定影响贝苗规格识别与计数统计装置准确性的因素,建立了5因素4水平的正交实验进行分析验证,并确定了扇贝苗规格识别与计数统计装置的最佳组合参数为:入料口尺寸为40×25 mm,传送带电机转速125 r·min^–1,姿态调节机构弧度20°,姿态调节机构距传送带末端距离40 mm,规格识别间隔为17 ms、25 ms。在验证性试验中,装置平均的识别计数准确率为94.4%,因此可见本装置稳定性较好,可为扇贝苗海上收购、底播一体化提供技术支撑。  相似文献   

珠江口沉积物210Pb分布特征及环境意义   总被引：2，自引：0，他引：2  

刘志勇  潘少明  程功弼  李向东 《沉积学报》2010,28(1):166-175

根据珠江口及其邻近海域中的14个沉积柱样的210Pb随深度分布的测量数据以及210Pb过剩衰减法的原理,建立了基于傅立叶级数的变沉积速率模型,对珠江河口近50年来河口沉积物的沉积序列进行了分析。分别对各柱样的210Pb数据使用变沉积速率模型进行计算,获得了柱样更切实的沉积速率变化过程并分析沉积速率、年代计算结果与同时期内沉积环境之间的关系,结果表明:珠江口不同站位的沉积速率差异很大,几个站位的整体平均沉积速率分别是,7.25 cm/a,5.36 cm/a,3.26 cm/a,3.03 cm/a,1.58 cm/a;沉积速率的变化与同时期发生在区域内的洪水、风暴潮、人类活动、河口演变等一系列综合因素有较好的对应关系,这说明使用基于傅立叶级数的变沉积速率模型得到的210Pb沉积速率变化的垂直分布能够解释其对应时段内的沉积环境,此模型亦可为其它河口区域的210Pb沉积速率计算提供借鉴。  相似文献