分布

During the postgenomics era the information about genomic sequence and gene functions provides a new foundation for evolutionary biology and ecology As the first whole-genome sequenced plant Arabidopsis thaliana and its wild relatives have played a critical role in understanding the evolution of genomics and speciation Both A halleri and A lyrata are closely related to the model species A thaliana A halleri ssp gemmifera occurs in northeastern China Japan and Taiwan; while its sister A halleri ssp halleri is mainly distributed in Europe Geographical barriers such as Tienshan Mountain Range isolate these intraspecific sisters Likewise A lyrata ssp kamchatica and ssp lyrata occur in East Asia and North America respectively Such distribution patterns seem to be consistent with allopartic speciation The comparison between ancestral and extant polymorphism by multilocus can be informative about the population genetics of speciation In this study we collected and analyzed DNA sequences of 98 genes from four wild relatives of A thaliana A halleri ssp gemmifera A halleri ssp halleri A lyrata ssp kamchatica and A lyrata ssp lyrata The ancestral states of these four species were compared to each other in terms of level of genetic variation However the ancestral species at the time of speciation were substantially more polymorphic than the extant geographical populations The observations are not fully compatible with speciation by strict allopatry At some species pairs parapatric speciation seems more reasonable in speciation of Arabidopsis The 98 gene sequences are also used for the congruence test between gene genealogy and species phylogeny Only 28 genes support the species phylogeny but there are 23 genes supports another major genealogy { lyrata} thaliana Based on the phylogenetic position change of A lyrata ssp kamchatica and Ks value for each species pair suggested the recent directional gene flow between A halleri ssp gemmifera and A lyrata ssp kamchatica

阿拉伯芥是第一个完成基因体定序的开花植物，其基因体资讯提供植物学研究的重要依据；在解析阿拉伯芥属物种的亲缘关系以及种化机制等重要的演化议题时，阿拉伯芥近缘的野生物种自然成了不可或缺的关键；跟阿拉伯芥近缘的物种包括A halleri及A lyrata，其中A halleri ssp gemmifera主要分布於中国东北、日本以及台湾，与近缘的A halleri ssp halleri其分布於欧洲隔著天山及大陆的障蔽，而A lyrata ssp kamchatica主要分布於东北亚及台湾，与分布於北美五大湖的A lyrata ssp lyrata被北极圈所分隔，这样的分布模式暗示异域种化的可能。藉由多基因分析比较祖先物种与现生物种遗传歧异度的相关可提供讯息探讨种化时期的族群遗传结构，本研究针对A halleri ssp gemmifera、A halleri ssp halleri及A lyrata ssp kamchatica、A lyrata ssp lyrata四个物种，两对互为亚种的姊妹群，以阿拉伯芥为外群进行研究，在四个物种完成98个同源基因的分子序列，利用套装软体MCMCcoal来估算祖先物种的遗传变异，亦估算现生物种的核苷酸歧异度，观察到？多物种配对中祖先物种遗传多型性大於现生物种DNA歧异度，显示异域种化模型并无法完全解释阿拉伯芥属物种的种化模式，在某些物种配对间邻域种化模式应比异域种化更为可能；在基因树与物种树的比较，98个基因片段的亲缘模式只有28个是与已知物种树一致的，有23个基因其树状图支持{ lyrata} thaliana的型式，藉由kamchatica位置的变化以及估算各物种配对间的平均同义置换率，推测在A halleri ssp gemmifera与A lyrata ssp kamchatica间具有近代的单方向基因交流。

We choose the arid land of northwestern China as our study area because of its extensive area, specific geographical location, dry climate, varied topography, vulnerable ecosystems and long-term human disturbance, as well as the existence of current conflicts between economic development and environmental protection. Based on the literature, we choose ten desert species with clear and relatively accurate geographical distribution ranges to model their distributions:Anabasis brevifolia, Atraphaxis frutescens, Calligonum mon-golicum, Ephedra przewalskii, Gymnocarpos przewalskii, Haloxylon ammodendron, Haloxylon persicum, Ka-lidium cuspidatum, Salsola laricifolia, and Sympegma regelii.

：选择面积广阔、地理位置特殊、气候干旱、地形地貌多样、生态系统脆弱以及人类活动长期干扰，而且目前面临着西部大开发和环境保护双重矛盾的西北干旱区作为研究区域，通过收集西北干旱区多种优势种和常见种的地理分布资料，选取10种分布范围相对明确、资料相对齐备的荒漠植物种：短叶假木贼、木蓼(A- traphaxis frutescens)、沙拐枣、膜果麻黄、裸果木、梭梭柴、白梭梭、尖叶盐爪爪、松叶猪毛菜(Salsola lar- icifolia)和合头草，定量分析其地理分布与气候因子的关系，并据此估测其潜在中心分布区和潜在最大分布范围，与实际分布范围进行比较。

To summarize two-dimensional non-normal joint distribution in use, such as Bivariate Weibull Distribution, Bivariate Log-normal Distribution, Bivariate Gumbel Distribution, and Bivariate Gamma Distribution.

归纳总结了已经出现的非正态二维联合概率分布模型，如二维威布尔分布、二维对数正态分布、二维冈贝尔分布及二维伽玛分布等。

Only in cauchy distribution are expected value and variance non-exist. By sas programming with SQL and MACRO we solve the fit of frequency distributions of data with these distributions. Meanwhile good-of-fit test is actualized so that the bound of parameters of distribution function is dwindling until the desired accuracy is arrived. The process is executed by the circle of macro.

利用SAS的SQL和MACRO等语句编写了大量的程序，以拟合优度检验结果为标准，不断地变换八种分布的参数变化范围，通过宏程序的不断循环，逐步缩小参数的范围，最后达到预先设定的标准，从而可以发现八种分布中哪几种分布能比较好地拟合给定的实际频数资料，我们再根据拟合优度检验的结果判断出哪种分布拟合实际频数资料最好，最终获得该频数资料的最佳的理论分布函数形式。

Therefore, in this article,we first discussed the compound negative binomial, it able to simultaneously fitthe claim size and the claim number. At the same time, we studied the sum of themutually independent compound negative binomial and the sum of the mutuallyindependent compound negative binomial with discount factor and the sum of themaximal compound negative binomial; Next, for the claim data to be better fitted, this article has establishedthe superposition distributed model about the weighted average of the discreterandom and has discussed the estimation method of the parameters of thesuperposition distribution; Once more, we in detail elaborated the NCD which based on the claim numberand the NCD which based on the claim size and the claim number. Besides, weestablished an applied NCD model which also based on the claim size and the claimnumber; At last, we introduced the rewards and punishment coefficient of automobiletravel region into the applied NCD model, availably consummated the present NCD.

因此，本文首先讨论了能拟合索赔额大小和索赔次数的复合负二项分布，并对相互独立的复合负二项分布的和、带有折现因子的相互独立的复合负二项分布的和以及最大复合负二项分布进行了研究；其次，为了更好地拟合索赔数据，本文建立了离散随机变量加权平均的叠加分布模型，并讨论了其中的权数的估计方法；再次，本文详细阐述了基于索赔次数的无赔款优待系统、考虑索赔次数和索赔额大小的无赔款优待系统以及应用型的同时考虑索赔次数和索赔大小的无赔款优待系统；最后，本文在无赔款优待系统中引入了汽车行驶区域奖惩系数，对现行的无赔款优待系统进行了完善。

In addition,we show that the transformed conditional distribution function is of the same family as that of the original one as long as the moment generating function of the original distribution function exists,which is illustrated by two special cases:Normal distribution and Normal Inverse Gaussiandistribution.

此外，本文还通过两个特殊情况(正态分布和正态逆高斯分布)说明了：只要初始分布函数的母函数存在，转化后的条件分布函数保持原有的分布类型。

In view of the peaked and fat-tailed characteristics of financial return data distribution and its effect of clustering fluctuation and especially the "leverage effect" of fluctuation on VaR estimates and some efficiencies when estimating VaR with various assumptions of return data distribution,a semi-parameter approach based on EGARCH-VaR model is developed.

在综合考虑了金融收益数据分布的尖峰厚尾特征及其波动集群性，尤其是其波动的&杠杆效应&对VaR估计的影响以及各种假定收益率分布在计算风险价值时存在不足的基础上，提出了基于EGARCH-VaR的半参数方法，并且与正态分布和t分布假设下的GARCH模型的VaR计量方法进行比较，通过实证分析，并利用后验测试，表明基于EGARCH-VaR的半参数方法对风险价值的测度优于正态分布和t分布假设下GARCH模型的VaR计量方法。

The simulation results of the cylinder-block model were given in the article, consistent with that of Middlemen"s. It was shown that the block part could improve the uniformity of the flow distribution. The analysis of the flow field of some materials with different power-law factor in the die designed by Mckelvey was close to that of Mckelvey"s. It was shown that the flow distribution was uniform in the die that can producesheets with 1200mm in width. During the analysis the flow channel was divided into several parts to get the details about the fluid flow in each area. A conclusion was drawn after analyzing the influence of the die pressure on the flow distribution, that the higher pressure is good for the output and bad for the uniformity of the distribution. Simulation of the die applying the cylindrical main runner showed the fact that when the cylinder replaced the cone the change of uniformity was trivial. The uniformity of the non-block flow channel was so poor that the block in the proper position of the die channel was necessary. The project of the die for the wider sheet was put forth, and the analysis of the fluid flow in the die was shown.

本文模拟了圆柱管缝隙流模型的三维流动场，得到了与Middlemen结论一致的流动均匀性，并通过模拟直观地展示了采用阻尼块可以改善挤出均匀性的现象；分析了多种幂率指数的流体在Mckelvey等人设计的流道模型中的流动分布，得到了与Mckelvey的分析结果接近的压力降和流量偏差；本文建立了1200mm幅宽机头流道的三维有限元模型，并逐个分析各个区域和多个截面的流动分布状况，由此揭示了1200mm幅宽L-型机头流道内的流北京化工大学硕士学位论文动分布基本均匀，并在分析了机头压力对于挤出流动分布的影响后得出结论：较高的机头压力可以获得较大的产量，但是不利于物料均匀分布；模拟了采用圆柱管主流道时机头流道内的流动分布，得出结论：主流道由圆锥管改为圆柱管时对流动均匀性影响不大，通过设置适当的阻尼仍然可以达到挤出平衡；模拟了两端进料式圆柱管无阻尼流道的流动均匀性后得到结论：两端进料式无阻尼结构的流动均匀性较差，宽机头中仍然有必要设置阻尼块；确定宽幅机头流道的基本方案，并设计了一种宽幅防水卷材挤出机头流道的结构，通过流动模拟表明该种结构的流动均匀性较好；考察了宽幅机头对于不同厚度片材的挤出适应性，得到结论：当生产不同厚度的片材时，阻尼块高度需要调整。

The experiment proved that the horizortal distribution of root system could reach 4.08 m,which is 0.96 time as the highth oras the crowrt,and the vertical distribution may be spreaded out soil layer.

mm根集中分布在树体周围0.58 m附近，垂直分布在20~40 cm范围。5~10 mm的根水平分布集中在0.58 m处，垂直分布集中在60~80cm范围。2~5 mm的根水平分布集中在0.58 m处，垂直分布集中在40~60 cm范围。

The following conclusions are drawn. 1 The orbit parameters that have relatively greater influence on the number and latitudinal distribution of annual occultation events are orbit inclination, orbit height, Right Ascension of Ascending Node and Argument of Perigee in turn. All four parameters have little impact on the longitudinal distribution of annual occultation events. 2 The orbit inclination of Transmitting Satellite and Receiving Satellite impacts both LEO－LEO occultation events number and their latitudinal distribution most. The number of occultation events reaches the maximum as the sum of the two inclination angles nears 180 degrees. The one that far away from 90 degrees of the two inclination angles determines the latitude range of the occultation events. 3 LEO－LEO occultation events number reaches a maximum when the heights of TS and RS are the same, and it reaches the maximum when the heights of TS and RS are 600 km . 4 The RAAN of TS and RS has a great influence on the LEO－LEO occultation number, but has little influence on occultation distribution.

结果指出：1对一年掩星事件数量及其纬度分布影响大的轨道参数依次是轨道倾角、轨道高度、升交点赤经和近地点角距；而这些参数对一年掩星事件的经度分布影响都不大；2发射卫星和接收卫星倾角之间的相互关系对掩星事件数量和纬度分布影响最大，两卫星倾角接近互补时掩星事件最多，两颗LEO卫星中与90°相差较大的倾角决定了LEO－LEO掩星事件的纬度分布范围；3发射卫星和接收卫星处于同一轨道高度时，LEO－LEO掩星事件数取得极大值，发射卫星和接收卫星都采用600 km的轨道高度，一年LEO－LEO掩星事件数最多；4 发射卫星和接收卫星升交点赤经的相互关系对LEO－LEO掩星事件数量影响很大，发射卫星和接收卫星升交点赤经之差为120°或240°时掩星事件数量最多，RAAN对掩星事件纬度和经度分布影响不大；5近地点角距对掩星事件数量和分布影响都不大。

However, as the name（read－only memory）implies, CD disks cannot be written onorchanged in any way.

然而，正如其名字所指出的那样，CD盘不能写，也不能用任何方式改变其内容。

Galvanizes steel pallet is mainly export which suits standard packing of European Union, the North America. galvanizes steel pallet is suitable to heavy rack. Pallet surface can design plate type, corrugated and the gap form, satisfies the different requirements.

镀锌钢托盘多用于出口，替代木托盘，免薰蒸，符合欧盟、北美各国对出口货物包装材料的法令要求；喷涂钢托盘适用于重载上货架之用，托盘表面根据需要制作成平板状、波纹状及间隔形式，满足不同的使用要求。