差

Firstly,the differential equation with parameters is given,at the same time,in order to let the truncation error of differential equation reach O(Δt~2+Δx~4) as high as possible,the method of undetermined coefficent is used to appropriately select the expression of these parameters.Secondly,the stability condition of the scheme derived is given by using the Fourier method of stability analysi...

首先给出了含参变量的差分方程，并用待定系数法适当地选取了这些参数的表示式，以使差分方程的截断误差阶尽可能高地达到了O(Δt2+Δx4)；其次用稳定性分析的Fourier方法给出了所得格式的稳定性条件；然后给出了确定差分格式中参数的两种方法，得到了一个稳定性条件为r/3的分支稳定的高精度显式差分格式；最后给出了数值例子，数值结果表明了本文格式较现有同类格式的优越性和理论分析的正确性。

In the PFD, both the differentials and non-differential terms in the differential equation are discretized, and the coefficients of the power series are determined by means of eliminating the truncation error of the corresponding modified scheme, then the high accurate difference scheme is obtained.

摄动有限差分方法在微分方程的差分近似中，离散微商项的同时，也离散非微商项，把非微商项摄动展开成网格步长△x的幂级数，并通过提高差分格式相应修正微分方程误差阶的方法求出摄动幂级数系数，从而获得高精度差分格式。

Studied present measuring methods" advantages and disadvantages, and presented the necessity and importance of researching propellant transient heat transfer.2.according to 130 and aeronautic 90 rocket projectiles" structure, analysed and acquired physical and mathematical models for propellant transient heat transfer, also designed propellant temperature field simulation units for test.3.acquired discrete transient heat balance equation and temperature calculation program, and gave contrasting curves between experimental temperature values and program calculating temperature values as well as maximum errors and average square root errors between them.4.by programs based on the first class boundary condition, worked out temperature distribution in propellant temperature field simulation units at different time, analysed temperature field distribution law and main elements affecting heat transfer, acquired propellant mass weighted average temperature and one at the half position of propellant maximum thickness as well as maximum errors and average square root errors between them.5.established transient heat transfer mathematical model and temperature calculation program for the third class boundary condition, drew contrasting curves between temperature experimental values and calculation values and gave maximum errors and average square root errors between them, got temperature distribution in the simulation unit at different time and main elements affecting heat conduction, figured out propellant mass weighted average temperature and one at the half position of propellant maximum thickness as well as maximum errors and average square root errors between them.

分析了现有测试方法的优缺点，提出了研究推进剂瞬态导热的必要性和重要性。 2。根据130和航90两种火箭弹的结构，分析得到了推进剂传热的物理模型和数学模型，设计了推进剂温度场模拟实验装置。 3。得到了离散形式的瞬态热平衡方程和温度场计算程序，给出了实验温度与程序计算温度值的对比曲线及其最大偏差与均方差。 4。利用程序求出了第一类边界条件下、不同时刻推进剂温度场模拟装置中的温度分布，分析了温度场的分布规律和影响传热的主要因素，求出了推进剂质量加权平均温度和最大肉厚1／2处的温度时间曲线并给出了两者之间的最大偏差与均方差。 5。建立了第三类边界条件下的瞬态导热数学模型和温度计算程序，求出了温度实测值与计算值的对比曲线并给出了两者之间的最大偏差与均方差，得到了不同时刻温度场模拟装置的温度分布与影响导热的主要因素，求出了推进剂质量加权平均温度和最大肉厚1／2处温度及两者之间的最大偏差与均方差，讨论并确定了能代表130和航90推进剂温度的特征点的位置。

In this paper, based on an optimum difference operator for spatial differential given by Holberg, an optimum difference method of modeling crosswell elastic wavefield is put forward, which adopts the staggered-grid technique and calculates the wavefield at different grid points. When the half length of optimum difference operator is taken as four to six points, the required number of grid points per wavelength equals to three, crosshole elastic wavefield numerical modeling can attain satisfied accuracy.

本文以Holberg提出的一种空间微分的最佳差分算子为基础，采用交错网格技术，提出了一种模拟井间弹性波场的最佳差分法，该方法能在大空间网格点上得到精确的波场值，当最佳差分算子的半长度取4～6个点，每个波长只采3个样点时，井间弹性波场的模拟就可以得到满意的精度，其计算速度比常规有限差分法至少快一个数量级。

This article first discusses the significance of homogeneity of variance, then studies the general method of transformation for homogeneity of variance on the relation between the data mean and the variance when population distribution is known ,and it uses the Mathematica software to analyse the variety rules between the parameter and the variance in the corresponding transformation.

从方差非齐性数据处理中的变换的必要性入手，根据数据均值与方差之间的关系研究了总体分布已知时的方差齐性变换的一般方法，并利用Mathematica软件分析相应变换中参数与方差之间的图形规律，最后介绍了总体分布未知时的BoxCox变换的一般原理。

In the double difference equation, the ambiguity can be divided into 2 parts, the first part is the integer one, the second part is the bias part caused by frequency difference.

在双差观测值方程式中，双差模糊度可分解为两项，第一项为整周项，第二项为站间单差非整周项，是由两卫星的频率差引起的。

According to the mathematics principle, three kinds of Differential equations of carry phase are deduced. The paper studies the theories and the method of integer ambiguity solution, especially researches some important methods of OTF.

依据数学原理推导了利用载波相位观测量进行定位的单差、双差、三差的相对定位差分方程：简要分析了求解整周模糊度的一般方法的流程，系统地研究了整周模糊度的解算理论和方法；对目前在线解算整周模糊度的几种重要的方法进行了理论分析。

The algorithm consists of 3 criterions: Criterion 1 is the mean square value of the difference image, and indicates occurrence of availability change of parking space; Criterion 2 is the variance of difference image; Criterion 3 calculates ratios of foreground to background at first, and then gets the variance of ratios.

监控算法基于以下三种判据：判据一是差影的均方值，可反映车位占用状态变化事件的发生；判据二是差影的方差，判据三是前景与背景比值的方差，通过判据二、判据三可以排除干扰、确认车位状态变化。

So a Matlab p rogram is developed to op timize interval estimation on variance of normal distribution and p rovide arith2 metic of hypothesis testing on variance of normal distribution.

5统计工具箱没有优化正态总体方差的区间估计，且没有给出正态总体方差检验的问题，通过编写Matlab程序，优化统计工具箱对正态总体方差的区间估计，开发正态总体方差的假设检验算法。

On average, the SSC in winter is 2 times than that in summer; and the SSC in spring tide is 2.96 times than that in neap tide.(2) The correlation coefficient of the daily tidal range and SSC at a tide circle is 0.86, and it goes up to 0.96 and 0.93 with one day and two days lag of SSC. This reflects that there has a hysteresis of one or two days of SSC to the tidal range.

三年平均而言，冬季悬沙浓度为夏季的2.0倍，大潮悬沙浓度为小潮的2.8倍；(2)平均的大-小潮半月周期变化中日悬沙浓度与同日潮差之间的相关系数为0.86，(显著性水平0.01)，与提前1日潮差之间的相关系数为0.99(显著性水平0.01)，与提前2日潮差之间的相关系数为0.93(显著性水平0.01)，反映潮差变化对悬沙浓度的影响有1-2天的滞后效应；(3)芦潮港月均悬沙浓度与长江大通站的月均流量呈显著负相关，尤以流量滞后19天的相关性最好。

As she looked at Warrington's manly face, and dark, melancholy eyes, she had settled in her mind that he must have been the victim of an unhappy attachment.

每逢看到沃林顿那刚毅的脸，那乌黑、忧郁的眼睛，她便会相信，他一定作过不幸的爱情的受害者。

Maybe they'll disappear into a pothole.

也许他们将在壶穴里消失