粒子滤波在高动态GPS定位中的应用     

田世君  陈俊  皮亦鸣 《测绘学报》2007,36(3):274-278

针对高动态GPS定位系统的特点,引入了一种基于粒子滤波的高动态GPS定位系统滤波算法。借助于移动目标的速度矢量模型建立了系统状态方程,论文给出了标准的卡尔曼滤波算法模型,重点讨论了粒子滤波算法在高动态GPS定位中的应用,详细描述了算法的推导过程。对算法进行仿真,结果表明当GPS接收机作大范围机动或GPS信号受到干扰时,粒子滤波要优于标准的卡尔曼滤波。  相似文献   

基于X波段双偏振雷达的贵州威宁一次冰雹过程水成物粒子识别研究          下载免费PDF全文

曾勇 《中低纬山地气象》2023,47(1):54-62

利用贵州威宁雪山X波段双偏振天气雷达一次冰雹过程观测资料,基于MATLAB软件对雷达观测数据进行数据质量控制基础上利用模糊逻辑算法对冰雹云中水成物粒子进行识别分类,主要结论如下：（1）采用综合小波去噪能够有效去除差分传播相位（ФDP）存才的脉动和毛刺,保证ФDP的连续性和平滑度,保留有效ФDP值,其用于雷达反射率因子衰减订正具有较好的效果。（2）冰雹形成与低密度霰（LDG）、高密度霰（HDG）以及过冷水（SCW）的增减演变较为对应,霰粒子是冰雹形成的关键粒子。（3）从霰粒子出现到识别出冰雹时间为26 min,约4个体扫时间,从识别出冰雹到地面观测到降雹32 min,约5个体扫时间。（4）冰雹识别结果与地面观测总体一致,所构建的识别参量阈值基本合理,研究所构建的粒子相态识别方法在贵州威宁具有普适性,可为冰雹早起识别、预警和人工防雹作业提供技术和理论支撑。  相似文献   

三维动态地形中瀑布的设计与实现     

胡新荣  李德华 《CT理论与应用研究》2004,13(1):38-42

目的文中了说明三维地形的模拟是进行室外可视化系统开发的一个必不可少的工作.方法文中提出了一个利用粒子系统的方法来模拟三维地形中瀑布的运动和汹涌直下.结果通过粒子作用范围及浓度的变化模拟瀑布的运动,介绍了粒子的表示和粒子系统的一般原理.结论给出了一种基于粒子系统的快速绘制三维地形中瀑布的方法.  相似文献   

基于形态学和DNA分子鉴定的珠江口浮游动物群落结构比较研究     

尹天齐  王庆  杨宇峰  岑竞仪 《热带海洋学报》2022,41(3):172-185

于2019年12月使用4种不同型号网具采集了珠江口浮游动物, 进行形态学鉴定和DNA分子鉴定, 分析珠江口浮游动物的群落结构特征, 并比较不同调查方法对浮游动物丰度和生物量结果的影响。形态学镜检鉴定浮游动物36种(类), 其中浮游幼虫6类。浅水I型浮游生物网采集的浮游动物平均丰度为115±96ind.·m^-3, 平均生物量为0.21±0.14g·m^-3; 浅水Ⅱ型浮游生物网采集的浮游动物平均丰度为3536±2444ind.·m^-3, 平均生物量为0.56±0.33g·m^-3; 浅水Ⅲ型浮游生物网采集的浮游动物平均丰度为4314±4172ind.·m^-3, 平均生物量为0.50±0.25g·m^-3; 25^#浮游生物网采集的浮游动物平均丰度为6741±3826ind.·m^-3, 平均生物量为4.33±3.42g·m^-3。研究结果表明网具孔径大小对浮游动物研究结果具有重要影响, 三个站点水体DNA样品注释出15种浮游动物; 使用浅水Ⅱ型网采集的DNA样品注释出19种浮游动物; 镜检样品鉴定浮游动物17种。水体DNA样品能检测出更多的微型浮游动物如原生动物等; 网采样品能过滤更多的水样, 有利于采集更多的大中型浮游动物, 更能充分反映优势类群如桡足类的种类和数量。研究结果表明, 水体DNA可检出浮游幼虫和原生动物等较难镜检鉴别的种类, 采用不同型号网具采集浮游动物可以更全面地反映研究海域浮游动物的群落结构特征。多种调查方法的结合有助于全面了解研究海域的生态环境状况。  相似文献   

能谱仪PPA分析方法的实验研究: 以山西大同新生代玄武岩样品为例          下载免费PDF全文

张素新  张毅  何德涛 《地球科学》2014,39(9):1301-1308

以山西大同新生代玄武岩样品为例, 利用Quanta 200扫描电镜、GENESIS能谱仪对能谱仪PPA分析方法进行了实验研究, 该方法为粒度和物相自动分析方法.笔者首次把能谱仪PPA分析方法应用到地质学领域的岩石光薄片研究中, 快速得出了一系列不同物相的形态学数据及化学成分分析结果: 物相种类、每一种物相的颗粒数、每一个颗粒的平均直径、面积、周长、圆度、长宽比及化学成分等, 并得出了不同物相在该视域所占的面积百分比及每种物相颗粒的平均直径, 克服了传统光薄片粒度分析方法的所有缺点, 为矿物学、岩石学及矿床学研究提供了一套非常有意义的数据.   相似文献   

Inter‐instrument comparison of particle‐size analysers     

Sam Roberson  Gert Jan Weltje 《Sedimentology》2014,61(4):1157-1174

This paper presents a methodological framework for inter‐instrument comparison of different particle‐size analysers. The framework consists of: (i) quantifying the difference between complete particle‐size distributions; (ii) identifying the best regression model for homogenizing data sets of particle‐size distributions measured by different instruments; (iii) quantifying the precision of a range of particle‐size analysers; and (iv) identifying the most appropriate instrument for analysing a given set of samples. The log‐ratio transform is applied to particle‐size distributions throughout this study to avoid the pitfalls of analysing percentage‐frequency data in ‘closed‐space’. A Normalized Distance statistic is used to quantify the difference between particle‐size distributions and assess the performance of log‐ratio regression models. Forty‐six different regression models are applied to sediment samples measured by both sieve‐pipette and laser analysis. Interactive quadratic regression models offer the best means of homogenizing data sets of particle‐size distributions measured by different instruments into a comparable format. However, quadratic interactive log‐ratio regression models require a large number of training samples (n > 80) to achieve optimal performance compared to linear regression models (n = 50). The precision of ten particle‐size analysis instruments was assessed using a data set of ten replicate measurements made of four previously published silty sediment samples. Instrument precision is quantified as the median Normalized Difference measured between the ten replicate measurements made for each sediment sample. The Differentiation Power statistic is introduced to assess the ability of each instrument to detect differences between the four sediment samples. Differentiation Power scores show that instruments based on laser diffraction principles are able to differentiate most effectively between the samples of silty sediment at a 95% confidence level. Instruments applying the principles of sedimentation offer the next most precise approach.  相似文献   

青岛市环胶州湾各河流输沙特征分析          下载免费PDF全文

盛茂刚  崔峻岭  时青  李磊  耿尧 《水文》2014,34(3):92-96

通过对青岛市环胶州湾各河流上的水文站历年含沙量、输沙量资料分析计算,推求出各河流的入海输沙量,并对输沙特征进行分析评价,最后得出以下以下结论:(1)从空间分布来看,胶州湾河流输沙主要来自胶州湾西北部和东北部。(2)河流属中沙河流。河道上游多年平均含沙量和输沙模数均大于河道中下游。(3)输沙量年际变化较大,最大年输沙量是最小年输沙量的518.7倍,且年降水量较大时,年入海水量也较大,年输沙量也较大。(4)河流悬移质颗粒特征为河流从源头到河口,泥沙粒径是不断减小。  相似文献   

Seasonal variations of number size distributions and mass concentrations of atmospheric particles in Beijing   总被引：1，自引：1，他引：0  

YU Jianhu  Benjamin GUINOT  YU Tong  WANG Xin  LIU Wenqing 《大气科学进展》2005,22(3):401-407

Particle number and mass concentrations were measured in Beijing during the winter and summer periods in 2003, together with some other parameters including black carbon (BC) and meteorological conditions. Particle mass concentrations exhibited low seasonality, and the ratio of PM2.5/PM10 in winter was higher than that in summer. Particle number size distribution (PSD) was characterized by four modes and exhibited low seasonality. BC was well correlated with the number and mass concentrations of accumulation and coarse particles, indicating these size particles are related to anthropogenic activities.Particle mass and number concentrations (except ultra-fine and nucleation particles) followed well the trends of 13C concentration for the majority of the day, indicating that most particles were associated with primary emissions. The diurnal number distributions of accumulation and coarse mode particles were characterized by two peaks.  相似文献   

南极中山站电离层的极区特征   总被引：9，自引：1，他引：8       下载免费PDF全文

沈长寿  资民筠  王劲松  刘顺林  徐寄遥 《地球物理学报》2005,48(1):1-6

本文利用1996年的电离层数字测高仪DPS-4所测的f0F2、f0E以及美国NOAA和DMSP卫星观测估算的半球功率指数和午夜极光区赤道侧边界纬度等资料,考察中山站电离层的极区特征。结果表明,在太阳和地磁宁静环境下,冬季极夜磁正午中山站处于极隙区中心时,电离层内的电离密度达全天的最大值;上、下午各有数小时间隔位极光带内时,高能粒子的电离作用也很重要;夜间进入极差区后,电子密度则很低。夏季极昼时,太阳EUV辐射的电离效应使电离层电离密度比冬季值大许多,而且,日变化的最大值时间也提前了1~2h,强磁扰时,极隙区和极光带均向低纬侧移动;中山站上空的电子密度会大幅度下降。在中等扰动环境下情况要加复杂：磁正午前后极隙区内软粒子沉降的电离强度有所减小,而上、下午极光区的高能粒子电离则有较大增加。  相似文献   

Characteristics of modern atmospheric dust deposition in snow in the Mt. Yulong region,southeastern Tibetan Plateau     

《Journal of Asian Earth Sciences》2014

We evaluated the concentration, size and distribution, and temporal variation of insoluble dust micro-particles in the snow, rainfall and water taken from the areas surrounding the Mt. Yulong to define the characteristics of modern atmospheric dust deposition and the contributions of different dust sources. The mean mass concentration (4511 μg kg⁻¹) of micro-particles with 0.57 < d < 26 μm, and the diameter (11.5 μm) of dust contained in the water bodies of the Mt. Yulong are roughly similar to those observed in other sites, implying that dust is primarily supplied through short-range transport from proximal source regions (several or hundreds of km distances). The mean mass concentrations of micro-particles with 0.57 < d < 26 μm is lower in the rainfall than in the snow and the river water, suggesting the rain water is an ideal source/carrier for detecting the characteristics of modern atmospheric micro-particles. Volume size distributions of micro-particles in the snow and water showed single modal structures having volume median diameters from 3 to 26 μm. Number concentrations of micro-particles in the snow were higher than that in the rainfall, the river water contains the least amount of micro-particles. Vertical profiles of the snowpits show that there is a strong lateral correlation among the dust peaks, indicating a regional uniformity of dust deposition and suitability of snow analysis for dust deposition. In addition, the bare rock of snow-free terrain in the Mt. Yulong region and the mineral particles from local rock weathering are also important sources for the dust deposition.  相似文献