查询词典 lag covariance

Five ways on comparing covariance matrix are applied to the Shanghai 50 Indexes Stock Exchange, which are sample covariance matrix, scalar matrix, two-parameter covariance matrix, single index matrix, constant correlation matrix. We adopt principal components method and Markowitz portfolio method to measure stock market risk using VaR, getting the effect of measuring market risk. The result shows that sample covariance matrix and two-parameter covariance matrix could measure market risk more effectively.

本文以上证50指数数据为样本，采用样本协方差矩阵、数量矩阵、两参数模型矩阵、单指数模型矩阵、常量相关矩阵作为与股票相关的协方差矩阵，结合投资策略选择的主成分方法和Markowitz最优投资组合方法，计算VaR以度量市场风险，并比较了五种协方差矩阵度量市场风险的效果，结果表明，在主成分方法中，样本协方差矩阵和两参数矩阵方法能有效的度量市场风险。

The instructive conclusion was: 1 under the vertical loading, the shear-lag effect was produced badly, more severer under concentrated loading than under uniform loading .2 the longitudinal bending deformation of the beam flange was true of the imitating plane assumption of deformation . 3 the width length ratio was confirmed as the first factor working on the shear-lag effect among all the geometric parameters;4 the shear-lag coefficient of simple-supported box-girder was severer than the continuous box-girder, the shear-lag effect in the inner supported section of continuous beam was much more severer, we need paying more attention for it in designing. 5 the non-liner characteristics of material deformation have littlie influence on shear-lag effect in BGCW. 6 the experiential calculating formulation and calculating diagram for the effective flange width was raised with the only factor of the width-span ratio., but the primary location of axis of bending moments should not be changed while calculating the inertial moment .

研究认为：1室内模型试验和空间有限元分析结果均表明波形钢腹板组合箱梁在竖向荷载作用下，翼板出现了典型的纵向应力剪滞效应。2在竖向荷载作用下，截面高度上各点纵向正应变分布认为可符合"拟平截面假定"，以此作为波形钢腹板组合箱梁抗弯计算的基本假定。3箱梁宽跨比是影响波形钢腹板组合箱梁翼板剪滞效应的主要因素。4连续波形钢腹板组合箱梁的翼板剪滞系数大于简支梁，且连续箱梁内支点截面翼板剪滞效应相当严重，对此需十分重视。5当混凝土翼板受力由弹性阶段进入弹塑性阶段时，材料的非线性特性对翼板的剪滞效应影响甚微。6提出了根据组合箱梁的宽跨比参数来计算翼板有效宽度比的经验公式和计算图表，但箱梁截面抗弯惯性矩的计算不应改变原先的截面中和轴位置。

1Niche construction can lead to stable coexistence of diverse genotypes in spatially structured population, which supports a stable polymorphism even without heterozygote superiority.(2)With habitat deterioration, niche construction accelerates the formation of steady polymorphism and hence impedes the harmful influences of environment on the population, which might embody a life-history strategy of organism under the unfavorable environment.(3)Niche construction results in the coexistence with alternative polymorphism through genotype-environment feedback and limited gene flow.(4)The niche-constructing organism is an active force to alter its environment and hence the direction of natural selection in order to better survival.(5)Spatial dynamics and distribution pattern of metapopulation are profoundly influenced by time-lagged niche construction.(6)Metapopulation size can reach a fixed level in the recency effect and equal weighting of time lag but is statistical stability in primacy effect, which implies the primacy effect is most remarkable.(7)The increment in the relative weightingof each generation\' niche construction and the length of time lag are significant factors for system destabilization.(8)Moderate capacity of positive niche construction benefits the metapopulation persistence.(9)The narrowing of niche breadth can decrease the metapopulation size and thereby increase the extinction risk.(10)The coupled function of time lag and niche construction make the system oscillation and generate the spiral wave, spiral-broken and circular wave in heterogeneous habitat.The spatial distributions of metapopulation and resource content are complementary due to a phase lag of their both frequencies.(12)Metapopulation persistence with niche construction depends not only on the balance between colonization and extinction, but also on the balance between the ability of niche construction and natural dissipation of habitat.(13)Metapopula-tion can survive under certain condition when the percent of suitable patches in habitat is lower than the ration of extinction to colonization.(14)Two thresholds exist in the process of transition of habitat quality dynamics from unsuitable to suitable, which include the intensity of niche construction and the initial condition of system.(15)Metapopulation size is positive correlated with the ability of positive niche construction, which means that organism or population who has strongly positive influences on their environment plays an important role to maintain the available habitat.

通过上述几个方面的研究，主要得出以下15条结论：(1)生态位构建可使空间结构种群，甚至是在没有杂合子优势的条件下，形成多种可能的稳定基因型分布模式；(2)随着环境的破坏与恶化，种群的生态位构建作用加速其较早形成稳定多态以阻碍环境对种群的不利影响，解释了有机体在不利环境下的一种生活史对策；(3)生态位构建作用通过基因型—环境反馈机制及有限的基因交流导致基因型多态的稳定共存；(4)有机体的生态位构建作用是一种积极的动力改变环境进而改变其自然选择的方向；(5)生态位构建的时滞作用对集合种群动态和空间分布产生深刻影响；(6)集合种群大小在时滞的崭新效应和等权重效应下达到一固定值，而在首位效应下达到统计稳定，表明首位效应的影响最显著；(7)首位效应下生态位构建相对权重的增量和时滞的长度是影响系统不稳定性动态的关键因素；(8)适中的生态位构建强度有利于集合种群的续存；(9)生态位宽度变窄会减少集合种群的数量从而增加其灭绝风险；(10)时滞和生态位构建的双重作用使系统产生周期振荡，并在异质性环境中产生稳定的螺旋波，破碎的螺旋波和环形波三种分布模式；(11)集合种群与资源含量的空间分布因为相滞而互补；(12)具有生态位构建的集合种群续存不仅取决于侵占率与灭绝率之间的平衡，而且依赖于生态位构建能力同其生境的自然消耗速率之间的妥协；(13)当生境中适合侵占的斑块比例小于其侵占率与灭绝率之比时，生态位构建作用促使集合种群在一定条件下续存：(14)生境斑块的状态从不适合到适合转变过程中存在生态位构建强度和系统初始条件这两个阈值；(15)集合种群的大小同正生态位构建能力正相关，意味着对环境具有较强正作用的有机体对维持有效生境起积极作用。

The RRs of symptoms decreased gradually after the accident day（lag 1~5d）. The RRs of breathe hard, ocular acerbity, lachrymation and temper oppression returned to normal level on the lag 3d; the RRs of cough, phlegm, throat desiccation and nonnasality saline and sternutation returned to normal level on the lag 4d; the RR of snivel returned to normal on the lag 5d.

沙尘暴过后虽然各种症状RR均有所下降，但下降速度不同：在滞后1~2d，气短、眼睛干涩、流泪和心情压抑等4种症状RR仍显著高于沙尘暴前，直到滞后3d才恢复到正常水平；而咳嗽、咯痰、咽干口苦和打喷嚏等4种症状RR在滞后4d才恢复正常；流涕症状RR在滞后5d才基本恢复正常。

The invention discloses a method and device for acquiring environment data collecting in honeycomb traveling carriage localizing system and GPS, A-GPS, the collecting device comprises collecting unit with time lag distribution power which connects with honeycomb traveling carriage receiver and GPS receiver, power time lag distribution pretreating unit, environment data extraction unit and managing unit; the method includes: determining the type of input data, gathered power time lag distribution, power time lag distribution pretreating, environment data extracting and synthesizing.

本发明公开了一种适用于蜂窝移动台定位系统和GPS、A-GPS系统的获取环境数据的装置和方法，该环境数据采集装置包括与蜂窝移动台接收机和GPS接收机相连的功率时延分布采集单元、功率时延分布预处理单元、环境数据提取单元和管理单元；本发明所述环境数据采集方法包括确定输入数据的种类、采集功率时延分布、功率时延分布预处理、环境数据提取和环境数据综合。

Studying the positive definitiveness of the covariance matrix from discrete data is important to design the sampling plan and provides the base for the data analysis.However, there have been few outcomes about the positive definitiveness of covariance matrix, most of which have been restricted to the Covariance-matrix of continuous sample.

研究离散型样本协方差矩阵的正定性有助于判断是否可以降低样本的维数，有利于优化抽样个数，为抽样调查的优化设计方案提供一定的理论基础；为基于特征根的多元统计分析提供理论指导。

In order to reduce calculation error, the frequency distribution of average values is used to compute the mixed distribution's digital features of each component distribution, thereinto, the number of the component distribution is determined by AIC, choose the number that meets the minimum value of AIC as the component number of mixed distribution, and the other parameters are estimated by EM algorithm; Secondly, because each component distribution is corresponding to a kind of major gene genotype, according to the values of the average and variance of the each component distribution, we can use the limit error of the normal distribution to plot each individual into the correspondent component distribution, namely into correspondent major gene genotype. Then we regard each major gene genotype as a treatment level of one-way analysis of variances, and the one-way multivariate analysis of variance is carried out to calculate the covariance matrix of major gene effect, covariance matrix of polygene effect, covariance matrix of environment effect and so on; At last, combining the weights of the each component distribution of mixed distribution, we can calculate the variance of major gene effect, the variance of polygene effect, environmental variance and the genetic gain of the quantitative trait.

为减小计算误差，本研究采用均值的频数分布来计算各成分分布的数字特征，其中成分分布个数根据AIC准则，选择使AIC值达到最小的成分分布个数作为混合分布的成分分布数，分布中其它参数的确定利用EM算法来估计；其次，每个成分分布对应一种主基因基因型，根据各个成分分布的均值和方差，利用正态分布的极限误差将每个个体划分到相应的成分分布中，即相应的主基因基因型中，将每种主基因型作为单因素方差分析的一个处理水平，对其进行单因素的多元方差分析，分别计算主基因效应协方差阵、多基因效应协方差阵、环境协方差阵等参数；最后结合混合分布中各成分分布的权重即各主基因基因型的分离比例，计算主基因效应方差，多基因效应方差和环境方差，以及遗传力等参数，进而计算该数量性状的遗传进展。

Ects, the covariance matrix of observation vector has special structure,and using the linear transformation for original model by idempotent matricesin the spectral decomposition of the covariance matrix, the problem of estima-tion of the covariance matrix becomes simultaneous estimation of all the distincteigenvalues of it.

在带有随机回归系数的一般线性模型中，首次提出了随机回归系数和参数的Minimax估计问题，分别在齐次线性估计类和一切估计类中研究了一个线性估计的Minimax性。

Moreover in carrier phase difference localization application, this paper introduces the basic principles of both the integer least square method and the LAMBDA method for resolving the integer ambiguity solution. Through a short baseline example and compared with the unlimited least square method, the results show that, LAMBDA method considers the ambiguity's integer characteristic and also decorrelates ambiguity's covariance, so it meliorates the covariance field of ambiguity, avoid the covariance's discontinuity.

另外在载波相位差分定位的应用中则详细讨论研究了整周模糊度解算中的基于整数最小二乘法及其降相关平差方法解算原理，通过一个短基线的实例计算分析其定位效果表明：较于未加限制的最小二乘搜索算法，LAMBDA方法能使相应的定位精度明显提高，具有较高的应用价值。

The past works on coupling eddy covariance technique and remote sensing technology are summarized. The following three aspects were focused:①Cross validation on the carbon flux estimation between eddy covariance and remote sensing technology;②Eddy covariance provides ground parameters for remote sensing inversion;③Remote sensing based eddy footprint analysis.

总结过去耦合涡度协方差技术与遥感技术的工作，主要在以下3个层面展开：①涡度协方差技术与遥感技术对碳通量估算的相互验证；②涡度协方差技术为遥感反演提供地面参数；③遥感观测解译辅助分析通量贡献区。

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？