Tests for quasi-independence of embedded markov chains     

Jinsheng Yu 《Mathematical Geology》1984,16(3):267-282

This paper introduces the concept of quasi-independence into embedded Markov chains and identifies the maximum likelihood frequency estimates to be used with ² tests of the null hypothesis of quasi-independence within an embedded Markov chain.  相似文献   

丽江7.0级地震前形变场动态演化与孕震信息提取研究   总被引：1，自引：0，他引：1  

王双绪  江在森 《中国地震》1997,13(4):338-348

本文用分段速率整体动态平差法，处理了滇西水准监测网８０年代以来的水准复测资料，并进行了形变速率多面函数拟合和垂直形变场信息分离。研究了１９９６年２月３日发生于滇西水准监测网北部的丽江７０级地震前，形变场动态演化和信息分离得到的垂直形变剪切变形、扩张变形、体积变化及准加速度等信息指标分布变化特征。结果表明：８０年代中前期，在滇西的丽江、永胜及其附近地区出现的大规模形变速率高梯度带和信息指标高值分布所反映的剧烈垂直差异运动，是丽江７０级地震前１０余年孕震应变能开始快速积累的显示；而１９８５～１９９２年形变场趋势转折与垂直差异运动显著减弱，可能意味着孕震能量积累到一定程度后，孕震区处于相对闭锁阶段。在此基础上，结合丽江７０级地震前区域地震活动分析和不同地区强震孕震形变对比，进一步研究了强震前形变场非均匀态特征和孕震信息的识别提取，得出了一些用大地形变进行强震中期预测的有益结果。  相似文献   

共和地区四次5.5级以上地震前后的Y值变化   总被引：2，自引：0，他引：2  

李佐唐 《高原地震》1997,(4)

研究了青海共和7．0级地震前后孕震区域加卸载响应比的时间变化特征。Y值在7．0级主震之前异常明显。主震之后Y值的异常变化可用来预报近期强余震。  相似文献   

丽江7.0级地震的烈度分布   总被引：7，自引：1，他引：7  

韩新民  周瑞琦 《地震研究》1997,20(1):35-46

本综合丽江地震宏观考察资料、系统介绍了整个震区和丽江县城（大研镇）的烈度分布及各烈度区的震害特征，并对一些主要烈度异常点（区）产生的原因进行了初步分析。  相似文献   

丽江7.0级地震震源环境及其破裂过程讨论   总被引：14，自引：1，他引：14  

苏有锦  刘祖荫 《地震研究》1997,20(1):66-71

本通过对丽江Ｍｓ７．０地震发生环境和破裂过程的分析讨论，得到以下认识：丽江地震发生在滇西北裂陷区北部块体内，这是一个由三组深断裂切割包围的三角形断块，断块内发育有裂陷盆地（大具－丽江裂陷盆地）；该区除了水平应力作用外，还有很强的来自地幔物质上隆引起的垂直应力作用；主余震分布在地壳一个由相对低速区包围的高速区内。地壳介质结构横向非均匀性－地壳高速块体的存在，可能是丽江地震震源成核的重要成因。丽江７  相似文献   

武定6.5级地震序列震源机制   总被引：5，自引：2，他引：5  

宋文  黄毓珍 《地震研究》1997,20(3):265-272

由地震Ｐ波初动符号资料，求解得到１９９５年１０月２４日武定６．５级地震序主震及２１外强余震的震源机制解。主震的两个节面走向分别为北西西向，倾向ＮＮＥ，倾角７０°；另一个节面走向为北北东，倾向Ｗ，倾角７７°；等效释放应力场主压力力方位为３２４°，仰角２４°。表明与区域应力场基本一致的主要震震源应力场及发震断裂控制着整个序列的地震活动。  相似文献   

云南鸡街碱性超基性岩杂岩体岩浆过程模拟     

黄智龙 《大地构造与成矿学》1997,21(1):24-31

在已有云南鸡街碱性超基性杂岩体地质、地球化学资料基础上，本文利用岩石学混合计算等方法对杂岩体源区成分、结晶分异过程进行模拟。结果表明，鸡街杂岩体来源于亏损地幔；岩体中相对早期碱性超基性岩（主体岩石：霞霓纳辉岩、霓霞岩和磷霞岩）为很少或没有受到上部地壳物质污染的幔源岩浆结晶分异作用产物；晚期碱性中性岩（脉岩：钠霞正长岩和霓辉钠长斑岩）为幔源岩浆（与碱性超基性岩同源）演化过程中发生岩浆液态不混淆作用产物。  相似文献   

An analysis of a zooplankton sampling-gear change in the CalCOFI long-term monitoring program, with implications for copepod population abundance trends     

Ginger A. Rebstock   《Progress in Oceanography》2002,53(2-4)

The California Cooperative Oceanic Fisheries Investigations (CalCOFI) program has been systematically sampling zooplankton off the west coast of North America since 1949. In 1978, the 1-m diameter ring net used by the program was replaced with a bongo net, which consists of two 0.71-m diameter nets on a single frame. This study compares paired zooplankton samples taken with a ring net and a 0.71-m or 0.6-m bongo net to determine the relative performances of the two net types for catching calanoid copepods. Thirty-one species and stages were enumerated, along with the category ‘total female calanoids’. Twenty-one categories of calanoid copepods were abundant enough to test for effects of changes in net type. No significant differences between the nets were found after correcting for multiple testing. Statistical power was then estimated for a range of potential net effects equivalent to ratios of copepod densities between the nets of 1.1–3.0. The probability of detecting differences greater than a factor of 1.5–3.0 was high (≥80%) for total female calanoids, Metridia pacifica, Pleuromamma abdominalis edentata, P. borealis, Calanus pacificus, Eucalanus californicus and Rhincalanus nasutus. For these categories of copepods, any population changes greater than a factor of 1.5–3.0 that might be found from the CalCOFI data set can be assumed to be the result of factors other than the change in net type.  相似文献   

3≈6 Months Variation of Sea Surface Height in the South China Sea and Its Adjacent Ocean     

Jianyu Hu  Hiroshi Kawamura  Huasheng Hong  Fumiaki Kobashi  Dongxiao Wang 《Journal of Oceanography》2001,57(1):69-78

Sea surface height (SSH) variations with a period of 36 months (SSH36 variations) in the South China Sea (SCS) and its adjacent ocean are intensively investigated using six years of TOPEX/POSEIDON-derived SSH data. The results show that there appears higher energy of SSH36 variations in the east of the Luzon Strait and in some areas of the SCS, both of which are correlated with each other. The SSH36 variations usually propagate westward in the subtropical region of the northern Pacific Ocean and turn northward in the east of the Luzon Strait while they sometimes propagate into the SCS through the Luzon Strait with the phase speed of about 11–12 cm/s, which may be considered as Rossby waves. It can be inferred that the SSH36 variations are strongly associated with current structures and eddies in the SCS because of their significant intensiveness. The SSH variations with the period of 6 months are more dominant than those with the other periods in the SCS.  相似文献   

海洋污染对毛蚶超氧化物歧化酶影响的研究   总被引：17，自引：0，他引：17       下载免费PDF全文

赵元凤  吕景才  李丹彤  刘长发  常亚青  侯美艳  潘德建  宋晓阳  孙静 《海洋学报》2003,25(3):77-82

采用体内、体外染毒实验,研究了海洋中常见污染物0＃柴油、二甲苯以及重金属镉离子(Cd2+)对毛蚶(Scapharca subcrenata)肌肉超氧化物歧化酶(SOD)活性的影响.结果表明,在实验剂量范围内,3种污染物对毛蚶肌肉中SOD均表现出不同程度诱导作用;0＃柴油和二甲苯体内、体外染毒对毛蚶SOD活性影响规律基本一致,这两种污染物对毛蚶SOD活性变化的剂量-效应曲线均为抛物线型;Cd2+在体内、体外染毒对毛蚶肌肉SOD活性诱导曲线均不呈抛物线型,低浓度Cd2+对毛蚶SOD活性表现为显著诱导,随后曲线迅速下降,表明毛蚶对Cd2+污染反应十分敏感,也表明Cd2+对毛蚶毒性作用较强,3种毒物对毛蚶的毒性强弱次序为,Cd2+,0＃柴油、二甲苯.  相似文献