查询词典 moment of distribution

We use the approximate distribution comes from probability generating function of CreditRisk+ to value the CDO under the single sector factor and multi-sector factors scenarios. For single sector factor model, we discuss the sensitive analysis of CDO fair spread by different default probability, default correlation and loss given default. For multi-sector factors model, we exam the CDO fair spread based on different sector correlation assumption, such as Gamma distribution in moment match method, multivariate Gamma distribution and compound Gamma distribution.

本文在信用风险加成模型之下，利用机率产生函数的近似分配评价抵押债务债券，并考虑单一部门因子与多个部门因子，单一部门因子中，在不同违约机率、违约相关系数和违约损失率下，探讨抵押债务债券公平价差之敏感度分析；多个部门因子中，在不同相关性部门因子分配假设下，如动差配适法的伽玛分配、多维伽玛分配、复合伽玛分配，探讨抵押债务债券公平价差之方法结果比较。

M. translational distribution, angular distribution, and the branching ratios for different possible product channels by measuring the angle-resolved time of flight spectra of photofragments. Information about photodissociation processes such as dissociative lifetime of parent molecule, the orientation of transition dipole moment, and the symmetry change of the highly excited states can be deduced from the translational energy distribution and angular distribution.

碎片平动能谱方法是在无碰撞条件下研究光解动力学的一种理想方法，它通过测量光致碎片在不同角度的时间飞渡谱(Time of Flight，简称TOF)，可以得到光解碎片质心系的平动能分布、角分布和不同解离通道之间的分支比等，由此可以推知母分子的解离寿命、跃迁偶极距的取向以及激发态分子的对称性变化等过渡态的动力学信息。

Photofragment translational spectroscopy is an ideal tool to investigate photodissociation dynamics under collision-free conditions through which one can obtain the total center of mass translational distribution, angular distribution, and the branching ratios for different possible product channels by measuring the angle-resolved time of flight spectra of photofragments. Information about photodissociation processes such as dissociative lifetime of parent molecule, the orientation of transition dipole moment, and the symmetry change of the highly excited states can be deduced from the translational energy distribution and angular distribution.

碎片平动能谱方法是在无碰撞条件下研究光解动力学的一种理想方法，它通过测量光致碎片在不同角度的时间飞渡谱(Time of Flight，简称TOF)，可以得到光解碎片质心系的平动能分布、角分布和不同解离通道之间的分支比等，由此可以推知母分子的解离寿命、跃迁偶极距的取向以及激发态分子的对称性变化等过渡态的动力学信息。

This problem is also important and valuable in Nonlinear Optics. It will be very helpful to understand how the aberrations affect the course of three- wave mixing, such as the change of conversion efficiency, the distribution of intensity and phase.Small signal solution of aberrated second harmonic generation is deduced from three-dimension three wave coupling functions. The numerical work gives out lot of results of different aberrations. The effects of the fundamental waves aberrations, which will change the conversion efficiency, distribution of intensity and phase in the frequency conversion, is analyzed. It shows that when walk-off and diffraction effects could be ignored approximately estimation of the phase distribution of second-harmonic wave could be done. The far field divergent angle and second moment radius of harmonic wave will vary with the aberration of fundamental wave, but the far field divergent angle will be obviously smaller than that of fundamental wave. The phase distribution of both fundamental and harmonic wave is measured using Hartmann-Shack wave front sensor in the experiment with 1064nm and 790nm lasers, respectively. Results are given.

首次从三维三波相互作用方程组推导得到了位相畸变光束倍频的小信号解；通过建立国防科学技术人学研究生院学位论文三维数值模型，编写相应仿真程序，首次得到了位相畸变光束倍频过程的大量计算结果，深入细致地研究了位相畸变光束经非线性光学频率变换后谐波的转换效率、光强分布、位相分布以及影响它们的各种因素；得出谐波的远场发散角和光斑二阶矩的变化规律会因为基波像差的不同而不同，但谐波的远场发散角明显地比相应基波的小的结论；得到了在走离效应和衍射效应等影响许多因素可以忽略的情况下，位相畸变传递到二次谐波的估算式；举例分析了KDP三倍频方案中，基波位相畸变对二次谐波和三次谐波的影响；实验工作中，用哈特曼一夏克传感器分别对IO64nm倍频过程和790飞秒超短脉冲倍频过程中的基波和谐波的位相分布进行了测量，给出了相应结果。

Abnormal distribution is not rare in practical measurement. Beta distribution contains not only central distribution but also non-central distribution. It is a good method to simplify the research of practical measurement distribution.

为了解决实际测量中的非正态分布的表示问题，本文采用含有两个参数的Beta分布来统示表示多种类型分布，并且解决了该分布的参数、特征值的计算。

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。

The main topics include probability space, discrete distribution, continuous distribution, multivariable distribution conditional distribution and the sampling distribution theory.

课程方要课题含机率空间、离散分布、连续分布、多变量分布及抽样分布等的简介。

Climatic gradients were based on data sets from 841 meteorological stations throughout China. Definitions for floristic distributional patterns were based upon the work of Prof. Z. Y. Wu. Most of these floristic distributional patterns were strongly correlated with the geographic gradients in climate, except for cosmopolitan, cultivated and invasive genera. Tropical genera form a large fraction of the total genera (ranging from 0.84% to 94.38% in the regional floras) with the highest proportion in southern Yunnan and Hainan Island. Tropical genera occur predominantly in southern China of 0° N latitude and decreased with increasing latitude, as would be expected. Interestingly, the disjunct Tropical Asia and Tropical America distribution were not restricted to southern latitudes. Temperate genera account for 5.1% to 98.83% of the total genera in regional floras with the highest proportion in the province of Xinjiang. Most of these genera followed geographic gradients in climate as expected (temperate genera conspicuously dominate the landscape at higher latitudes), except the East Asian and North American disjunct distribution, Eastern Asian distribution and Chinese endemic distribution. Generally, most plant genera demonstrated some correlation with climatic and geographic gradients. The most important gradients were those of annual air temperature and precipitation. A small fraction did not demonstrate significantly particular pattern:"Cosmopolitan","East Asian and North American disjunct","Eastern Asian" and "Chinese endemic" distributions. The North Temperate distribution had the highest correlation with mean annual air temperature and precipitation.

结果如下：(1)除世界分布、栽培和入侵成分外，大部分中国种子植物属的地理成分的分布与地理相关密切；(2)热带分布属（泛热带分布、热带亚洲至热带美洲间断分布、旧世界热带分布、热带亚洲至热带大洋洲分布、热带亚洲至热带非洲分布及热带亚洲分布合计）占各地方植物区系的0.84%到94.38%，其最低值出现在中国西北部的新疆和青海地区，最高值出现在中国云南南部和海南；(3)热带分布属在＜北纬30°的地区占优势，除热带亚洲至热带美洲间断分布外，其它热带成分随纬度增加迅速减少；(4)温带分布属（北温带分布、东亚和北美间断分布、旧世界温带分布、温带亚洲分布、地中海区、西亚到中亚分布、中亚分布和东亚分布合计）占各地方植物区系的5.1%至98.83%，其最高值出现在中国西北部的新疆地区，最低值出现在中国云南南部和海南；(5)除东亚和北美间断分布、东亚分布和中国特有分布外，其它温带成分随纬度增加迅速增加；(6)在温带成分中，东亚和北美间断分布及东亚分布属主要出现在中国亚热带到暖温带地区，北温带分布、旧世界温带分布和温带亚洲分布属在中国北部占优势，而地中海区、西亚到中亚分布和中亚分布属则在中国西北部占优势；(7)除世界分布、东亚和北美间断分布、东亚分布和中国特有分布外，所有其他成分都显示了与气候因素密切相关，其中，北温带分布属与年均温和年降雨量最为密切相关。

The main research work of this paper are focused on following areas:(1) Based on review of the theory and methods on measurements of particle fields, a new idea for obtaining particle size and velocity distribution within a spray through imaging the particle field with a laser light sheet was put forward;(2) A DPIV (Digital Particle Image Velocimetry) system, is fit for velocity measurements of low speed flows, was developed and expended to particle size distribution measurement;(3) An arithmetic for particle velocity field reconstruction was developed, and the velocity distribution of water mist was also obtained;(4) A software system for particle analysis, which based on image geometry emend, de-noise and image partition was developed, the parameters such as particle size distribution, mean diameter, number of particles, minimum and maximum diameter can be got with this system;(5) A water mist system was developed and its characteristics, such as droplet velocity, size distribution, number of droplets and spray cone angle under different conditions were obtained from experiments with PIVS;(6) The measurement results of water mist characteristics with PIVS were compared and analyzed with the simply simulated results, and in addition, in order to verify the accuracy of PIVS, some experiments were conducted with the standard particles, such as glass-ball with known mean diameter of 50μm and 115μm, metallic coated tracing particle with mean diameter of 12μm;(7) Some experimental studies on interaction of water mist with liquid pool fires were conducted.

本论文的主要工作包括以下几个方面：（1）在对粒子场测量的相关理论和具体方法进行综述分析的基础上，提出了通过采用激光片光对粒子场进行成像以获取其粒径和速度等参数分布的新思路；（2）研制了适宜于低速流动速度场测量的DPIV(Digital Particle Image Velocimetry)系统，并使其实现了对粒子场粒径分布的测量功能；（3）研制了基于粒子运动轨迹的速度场重建算法，获取了细水雾雾场的速度分布；（4）研制了基于几何校正、去噪、图象分割等图象处理方法的"粒度分析软件系统"，该系统既可分析给出粒子场的粒径分布直方图和平均粒径，还可给出粒子的数目以及最大、最小粒径等信息；（5）建立了一细水雾发生系统，并应用上述方法对不同压力条件下细水雾系统的雾场特性（如速度分布、雾滴粒径分布、雾滴的数目、喷雾张角以及雾化长度等）进行了实验测量研究；（6）对细水雾特性参数的PIVS测量结果与计算机简单模拟计算结果进行了定性比较分析，并利用平均粒径为50μm和115μm的玻璃球以及12μm的标准示踪粒子对PIVS系统的粒径和速度测量结果进行了实验验证，同时对其局限性进行了分析讨论；（7）对不同工况条件下细水雾与油池火相互作用的过程进行了模拟实验研究。

This dissertation investigates the construction of pseudo-random sequences (pseudo-random numbers) from elliptic curves and mainly analyzes their cryptographic properties by using exponential sums over rational points along elliptic curves. The main results are as follows:(1) The uniform distribution of the elliptic curve linear congruential generator is discussed and the lower bound of its nonlinear complexity is given.(2) Two large families of binary sequences are constructed from elliptic curves. The well distribution measure and the correlation measure of order k of the resulting sequences are studied. The results indicate that they are "good" binary sequences which give a positive answer to a conjecture proposed by Goubin et al.(3) A kind of binary sequences from an elliptic curve and its twisted curves over a prime field F_p. The length of the sequences is 4p. The "1" and "0" occur almost the same times. The linear complexity is at least one-fourth the period.(4) The exponential sums over rational points along elliptic curves over ring Z_ are estimated and are used to estimate the well distribution measure and the correlation measure of order k of a family of binary sequences from elliptic curves over ring Z_.(5) The correlation of the elliptic curve power number generator is given. It is proved that the sequences produced by the elliptic curve quadratic generator are asymptotically uniformly distributed.(6) The uniform distribution of the elliptic curve subset sum generator is considered.(7) We apply the linear feedback shift register over elliptic curves to produce sequences with long periods. The distribution and the linear complexity of the resulting sequences are also considered.

本文研究利用椭圆曲线构造的伪随机序列，主要利用有限域上椭圆曲线有理点群的指数和估计讨论椭圆曲线序列的密码性质——分布、相关性、线性复杂度等，得到如下主要结果：(1)系统讨论椭圆曲线-线性同余序列的一致分布性质，即该类序列是渐近一致分布的，并给出了它的非线性复杂度下界；(2)讨论两类由椭圆曲线构造的二元序列的"良性"分布与高阶相关性(correlation of order κ)，这两类序列具有"优"的密码性质，也正面回答了Goubin等提出的公开问题；(3)利用椭圆曲线及其挠曲线构造一类二元序列，其周期为4p(其中椭圆曲线定义在有限域F_p上)，0-1分布基本平衡，线性复杂度至少为周期的四分之一；(4)讨论了剩余类环Z_上的椭圆曲线的有理点的分布估计，并用于分析一类由剩余类环Z_上椭圆曲线构造的二元序列的伪随机性；(5)讨论椭圆曲线-幂生成器序列的相关性及椭圆曲线-二次生成器序列的一致分布；(6)讨论椭圆曲线-子集和序列的一致分布；(7)讨论椭圆曲线上的线性反馈移位寄存器序列的分布，线性复杂度等性质。

More direct, directer ; most direct, directest

径直的，笔直的

Do you know how to use a chain saw?

你知道如何使用链锯吗？