A stepwise method for determining the number of component distributions in a mixture     

Yu-Sheng Hsu  Joseph J. Walker  David E. Ogren 《Mathematical Geology》1986,18(2):153-160

This paper considers the problem of estimatingm, the number of components in a finite mixture of distributions from a parametric family. A step-up procedure using the bootstrap method is proposed. Some properties of the procedure are illustrated with simulation studies. An example of the method, applied to orientation of beach clasts, is given.  相似文献   

5个新发现的X选BL Lac天体   总被引：1，自引：0，他引：1  

谢光中  茶光伟  白金明  张雄  Ｗ．Ｂｒｉｎｋｍａｎｎ 《中国天文和天体物理学报》1997,(3)

利用ＲＯＳＡＴＶＬＡ方法筛选，从ＲＯＳＡＴＸ射线源中选出了一批新的ＢＬＬａｃ天体和类星体的候选体．１９９６年１２月８日至１７日，利用北京天文台２．１６ｍ望远镜和新从美国引进的ＯＭＲ摄谱仪，对这批新候选体进行了光谱认证．经ＳＵＮ工作站处理，又发现了５个新的Ｘ选ＢＬＬａｃ天体．此外，还对去年作者在ＯＭＲ引进之前发现的ＢＬＬａｃ天体进行了检验，结果发现，去年发现的７个ＢＬＬａｃ天体中，２３２２＋３４３的ＣａＩＩＨ＆Ｋ“Ｂｒｅａｋｓｔｒｅｎｇｔｈ”为２６．９％，稍大于判据２５％，因此，２３２２＋３４３到底是ＢＬＬａｃ天体还是射电星系还有待于进一步测光及偏振观测的验证．  相似文献   

MORPHOLOGICAL AND FUNCTIONAL STUDIES ON THE EPIDERMAL CELLS OF AMPHIOXUS (BRANCHIOSTOMA BELCHERI TSINGTAUENSE) AT DIFFERENT DEVELOPMENTAL STAGES     

毛炳宇  孙晓阳  张红卫  张士璀  吴贤汉 《中国海洋湖沼学报》1997,(3)

ImODUcrroNTheVertchrateepidennisisinintirnatecontaCtwiththeenvironmentandre~environmentaladaptions.TheepidermisofterreStrialanbolsiskeratinedwhilethatofamPhibiousandaquaticfonnsisrelataltomucus-produCti0n.Theepidennisadsasafi-nalbatherbetweentheorganismanditsenvironmentandoneofitSrnainfunCtionsistoproteCttheorganismagainstextemalpathogens.lnadditiontoIneCanicalproedonofthebody,theepidertnisofamPhibiansandfishescansededinsandotherantibacterialpeptidesthathelpinthebonedefenSeoftheanhal(Su…  相似文献   

MERLIN Images of Five Compact Symmetric Object Candidates at 1.6 GHz     

Hai－YanZhang  XiangLiu 《中国天文和天体物理学报》2001,1(2):129-132

1 INTRODUCTIONCompact Symmetric Objects (CSOs) are powerful and compact sources (overall size <1 bpc) with lobe emission on both sides of the central engine. The small size of these sourcesis almost certainly to be attributed to the youth of the sources themselves (ages < 104 yr) andnot due to a dense coallning medium (Readhead 1996). The unification scenario assumes thatCSOs evolve into compact steep spectrum (CSS) sotirces and then into Fanaroff-Riley type 11objects (Fanti 1995). …  相似文献   

太阳线性无力场评注和快速傅氏分析法的应用   总被引：1，自引：0，他引：1  

宋慕陶  张延安 《天文学报》2004,45(4):361-380

首先对30年来用无力场计算太阳活动区磁场方法作了一些评注，特别研究了线性无力场解中的几个误区，提出了准线性无力场方法并探讨了快速傅氏变换在线性无力场计算中的应用，以2000年9月15日NOAA 9165活动区磁场为例，应用3种不同的方法计算出磁力线走向，然后同紫金山天文台赣榆观测站观测的精细Hα图形对比。  相似文献   

Study on numerical simulation to water lowering in an open coal mine digging     

Yanjun ZHANG Fenglong ZHANG Full QI Fuquan NI 《东北亚地学研究》2006,9(2):199-203

In view of the situation of excavation of open coal mine for the underground water disaster,we should carry out simulation studies for the numerical value of the water lowering project and improve the accuracy and the level of the water lowering project.On the basis of the hydrological geological conditions of certain open mine digging,a more reasonable seepage numerical model was built according to MODFLOW.It was simulated in advance that the process of the confined water level descending with the time,and combining with the actual observations to test the correctness of the model.The calculation showed that the results coincided well with the results of actual measurement.Based on this,different water lowering numerical simulations were built for the open coal mine digging.It could be simulated and forecast that the changes of the groundwater level in drainage process within and outside the mine pit,and it was quantitatively assessed that the possible water lowering result of the opencast water drainage process,which provide an important basis for the actual water lowering project and the possible project disposal.  相似文献   

石英砂扫描电镜在漓江“泥砾”成因中的应用     

吴枝坦  王壬林  姚若飞 《南方国土资源》1992,(4)

本文根据扫描电镜对从漓江河谷钻孔中的泥砾层取得的481粒石英砂表面形态特证研究结果:石英砂多数颗粒保持棱角状外形并遭受不同程度的磨蚀,具阶状贝壳断口,平直或弧形刮削面和多向擦痕,沿解理面破碎呈“V”字形沟和撞击碟形坑,以及微溶蚀孔、隙、蜂窝状溶孔群和SiO_2再沉积等表面形态结构特征。认为它是在第四纪古地理湿热气候条件下泥石流沉积的产物,物源可能来自境内或周边的泥盆系砂岩和境外的花岗岩。  相似文献   

Speciation of trace metals in sediments of a tropical estuary     

C. K. Nair  A. N. Balchand 《Environmental Geology》1993,21(1-2):96-102

Axial surveys were performed in the two river tributaries of the Cochin estuary, SW India during November 1988. Surficial sediments were subjected to sequential chemical extractions to delineate five metal fractions, namely, exchangeable, carbonate bound, easily reducible, organic/sulfide bound, and residual. The results indicated selective accumulation of Mn and Ni in carbonate bound and organic/sulfide forms, along with marginal amounts of Co in the exchangeable fraction. Large portions of Fe and Cr occurred in the residual fraction, whereas composite fractionation of Zn species was noticed. The exchangeable fractions of Fe and Cr as well as of easily reducible cobalt were below detection limits. The levels of Cr and Zn indicate anthropogenic inputs in this estuary, whereas Co and Ni show regional contamination exceeding natural levels. The analytical speciation procedure helps to deduce the sedimental diagenetic processes in the estuarine environment.  相似文献   

黑洞吸积盘的演化及温度分布的热不稳定性     

汪定雄  杨兰田  陆烨 《中国天文和天体物理学报》1994,(4)

本文在Ｔｈｏｒｎｅ工作的基础上讨论了吸积盘中黑洞的有关参量的演化，以及由Ｓｃｈｗａｒｚｓｃｈｉｌｄ黑洞吸积盘向Ｋｅｒｒ黑洞吸积盘演化过程中对吸积盘辐射通量的影响，最后针对几个典型的辐射过程，分别讨论了黑洞吸积盘在牛顿框架中的温度分布方程与广义相对论的温度分布方程的热不稳定性，并给出此类问题的热不稳定性的判据。  相似文献   

泰安市地下水污染现状与成因分析          下载免费PDF全文

马振民  石冰  高宗军 《山东国土资源》2002,18(2):24-28

采用参数分级评分叠加型指数法对泰安市地下水污染现状进行的评价结果显示 ,泰安地下水已遭受严重污染。地下水污染以地下水中宏量组分、NO-3 、硬度、TDS的迅速上升高以及地下水遭受人为环境物质的污染为主要标志 ;地下水污染主要受地下水系统水文地质结构、纳污河流、污水灌溉及地下水开采控制和影响 ,地下水污染是人类活动影响的结果。  相似文献