聚类分析在X波段双偏振雷达相态识别中的应用     

李宗飞  李祥海  陈凯华  冯亮 《气象科技》2021,49(3):315-321

X波段双偏振雷达在降水相态识别方面有较大优势,目前较为常用的方法为模糊逻辑算法,具有较好的识别能力,该方法主要依赖于水凝物的成员函数,但是对于不同雷达的系统老化问题,需要调整相对应的成员函数。针对此问题,本文提出采用聚类分析的方法进行降水相态识别,在完成相态识别后,可以统计不同水凝物雷达参数的分布特征,重新构建适合该雷达的成员函数。聚类分析方法在相态识别实验中表现良好,但仍存在一定的问题,在不引入温度的情况下部分水凝物无法识别。  相似文献   

风暴的自动识别,跟踪与预报   总被引：17，自引：2，他引：15  

肖艳姣  蒋义芳 《南京气象学院学报》1998,21(2):223-229

利用多普勒雷达体扫描资料对风暴进行实时地自动识别、跟踪、结构分析和临近预报,风暴的识别基于其个连续区域的体积和雷达反射率大于给定的体积阈值和反射率阈值;用矩心跟踪法匹配相邻两时刻的风暴,对风暴的合并与分裂进行了处理;根据风暴在过去各个时刻的中心位置和体积,利用最小二乘法进行线性外推来预报其在下一时刻的位置和面积。结果表明本方法能较好地识别、跟踪和警戒强对流性天气。  相似文献   

Estimation of Cloud Motion Using Cross-Correlation   总被引：6，自引：0，他引：6  

Li Zhenjun 《大气科学进展》1998,15(2):277-282

ＥｓｔｉｍａｔｉｏｎｏｆＣｌｏｕｄＭｏｔｉｏｎＵｓｉｎｇＣｒｏｓ－ＣｏｒｅｌａｔｉｏｎＬｉＺｈｅｎｊｕｎ（李振军）ＡｉｒＦｏｒｃｅＣｅｎｔｅｒｏｆＭｅｔｅｏｒｏｌｏｇｙ,Ｂｅｉｊｉｎｇ１００８４３ＲｅｃｅｉｖｅｄＡｕｇｕｓｔ２５,１９９７;ｒｅｖｉｓ...  相似文献   

A probabilistic approach to structural model updating   总被引：3，自引：0，他引：3  

Lambros S. Katafygiotis  Costas Papadimitriou  Heung-Fai Lam 《Soil Dynamics and Earthquake Engineering》1998,17(7-8):495-507

The problem of updating a structural model and its associated uncertainties by utilizing measured dynamic response data is addressed. A Bayesian probabilistic formulation is followed to obtain the posterior probability density function (PDF) of the uncertain model parameters for given measured data. The present paper discusses the issue of identifiability of the model parameters and reviews existing asymptotic approximations for identifiable cases. The focus of the paper is on the treatment of the general unidentifiable case where the earlier approximations are not applicable. In this case the posterior PDF of the parameters is found to be concentrated in the neighborhood of an extended and extremely complex manifold in the parameter space. The computational difficulties associated with calculating the posterior PDF in such cases are discussed and an algorithm for an efficient approximate representation of the above manifold and the posterior PDF is presented. Numerical examples involving noisy data are presented to demonstrate the concepts and the proposed method.  相似文献   

钻探微机智能监测系统的研制与应用   总被引：2，自引：0，他引：2       下载免费PDF全文

鄢泰宁  龚元明  姚爱国  吴翔 《探矿工程》1998,(4):26-27,29

钻探微机智能监测系统是检测技术、识别算法、计算机技术与钻探工艺相结合的高科技成果。它可方便快捷地安装于野外钻进现场,自动生成钻进参数的约束条件,对孔内工况进行智能识别,从而提高钻探效率,降低事故率,还可跟踪钻孔轨迹,进行中靶预测,建立钻探生产数据库。  相似文献   

应用模糊评判法预测新疆东准噶尔地区金成矿有利区   总被引：1，自引：0，他引：1  

韩春明  汪立今 《物探化探计算技术》1998,20(2):142-145

应用模糊综合评判原理,在对新疆东准噶尔地区金成矿地质基本特征分析基础上,选取地质、地球化学参数,利用各参数的权重分配进行调整,确定最佳权重分配方案,对新疆东准噶尔地区金的含矿性进行综合评判,其结果预测了该地区金矿成矿有利区。  相似文献   

和田玉   总被引：1，自引：0，他引：1  

蒋壬华 《上海国土资源》1998,(2):49-58

通过对和田玉的矿物成分、矿床成因类型、产状序列特征比较系统地介绍,总结了当前市场上和田玉与相似软玉的肉眼鉴定要点。  相似文献   

On the rotation–activity correlation for active binary stars     

Gunn  Mitrou  & Doyle 《Monthly notices of the Royal Astronomical Society》1998,296(1):150-164

We present an investigation of rotation–activity correlations using International Ultraviolet Explorer ( IUE ) SWP measurements of the C  iv emission line at 1550Å for 72 active binary systems. We use a standard stellar evolution code to derive non-empirical Rossby numbers, R ₀, for each star in our sample and compare the resulting C  iv rotation–activity correlation to that found for empirically derived values of the Rossby number and that based on rotation alone. For dwarf stars our values of R ₀ do not differ greatly from empirical ones and we find a corresponding lack of improvement in correlation. Only a marginal improvement in correlation is found for evolved components in our sample. We discuss possible additional factors, other than rotation or convection, that may influence the activity levels in active binaries. Our observational data imply, in contrast to the theoretical predictions of convective motions, that activity is only weakly related to mass in evolved stars. We conclude that current dynamo theory is limited in its application to the study of active stars because of the uncertainty in the angular velocity-depth profile in stellar interiors and the unknown effects of binarity and surface gravity.  相似文献   

Use of rapd for detecting and identifyingPorphyra (Bangiales, Rhodophyta)     

Song Lin-sheng  Duan De-lin  Li Xiao-hong  Li Chen-xi 《中国海洋湖沼学报》1998,16(3):237-242

Randomly amplified polymorphic DNA (RAPD) technique was applied to assess the genetic variations and phylogenetic relationships in 4 species ofPorphyra. The samples were collected from the coast of Canada, Vietnam, Zhoushan, Fujian and Qingdao in China. Amplifications with 20 primers were carried out under predetermined optimal reaction conditions (samples were first heated at 94°C for 5 min. and followed by 45 cycles of 1 min at 94°C, 1 min at 36°C, and 2 min at 72°C, then held at 72°C for 10 min). The amplified products were scored as present (1) or absent (0) for each DNA sample and an index of genetic similarity (F) was calculated by using Nei & Li’s matching coefficient method (1979). The value of (1−F) was used to quantify the genetic distances between species and construct a phylogenetic tree. The relationship indicated by the UPGMA and NJ cluster analysis on the values of the genetic distance is in good overall agreement with classical taxonomy. The obvious differences between natural and cultivated population ofP. haitanensi suggest that variation or hybridization with other species occurred during the culture. Contribution No. 100 from the Experimental Marine Biology Laboratory, IOCAS. Contribution No. 3289 from the Institute of Oceanology, Chinese Academy of Sciences. The research supported by the Foundation of the Chinese Academy of Sciences.  相似文献   

运用神经网络识别注射过金属离子溶液树冠的实验研究   总被引：1，自引：0，他引：1  

杨旭东  吴继友  张福军  田文新  解立业 《遥感学报》1998,2(3):176-179

本文运用神经网络ＢＰ算法对高分辨率航空多光谱图像进行了模式识别研究,成功地识别出注射过金属离子溶液树冠,并与最大似然法在分类结果进行比较。得出在分类精度上,神经网络模式识别比传统的最大似然分类方法具有优势的结论。  相似文献