系数问题

In chapter four, the coefficient which is not large for nonsymmetric and indefinite elliptic boundary value problems is considered.

本文主要考虑低阶项的系数不是很大的情况下的非对称不定椭圆边值问题。

This paper investigates the problem of the best weighted simultaneous approximation to totally bounded sequence s from a set G of generalized polynomials with restricted coefficients in complex normed linear spaces X.

在复赋范线性空间X中考察了具限制系数的广义多项式集G对全有界序列的加权同时逼近问题。

At the same time, combining with the actual condition of delivery pipeline of our country and some prevalent leak detection and location methods, this paper raised a method, which is based on wavelet analysis and negative- pressure-wave to detect and locate the leakage. Jobs in the paper are as follows:As affected by gas density, pressure, specific heat and pipe material, the velocity of negative-pressure-wave improved depending on the energy conservation. At one time, taking the affection of velocity of gas flow, the location formula was modified in some degree.When locating the leaks with location formula, the iterative approach algorithm was adopted as a new method to increase the location accuracy level of system.Multi-scale decomposition and reconstruction of wavelet transform is utilized to filter the noise of negative-pressure-wave, which was brought by leakage. With the capacity to detect the signal singularity fast and accurately, wavelet transform was used to catch the break point of pressure signal. The work improved the accuracy of At in location formula, accordingly improved the location accuracy.Wavelet is a suitable tool for signal analysis. The distinct character is that the mother-wavelet is of optional. That means choosing different mother-wavelet will get different analysis result. So we studied how to choose mother-wavelet and its scale for signal singularity detection. The method is to choose a wavelet by regularities of the wavelet and the signal.Finally, a plan, which bases on SCADA system for inspection and detection of natural gas leakage, is proposed in the article.

其中，主要进行了以下几方面的工作：针对泄漏产生的负压波在管道中的传播速度受媒介的密度、压力、比热及材质等因素的影响，而非声波在空气中传播的速度，本文利用能量守恒原理，对其进行了修正；考虑到管内气体流速对压力波速的影响，对原始的负压波定位公式进行了一定程度的改进，并在利用定位公式进行泄漏点定位时采用逐步迭代逼近算法，提高了系统的定位精度；利用小波变换的多分辨率分解和重构技术，对采集到的管道发生泄漏时产生的负压波信号进行了降噪处理；并利用小波变换技术对信号奇异点的快速、准确的识别能力，对经上述消噪后的负压波信号进行了奇异点捕捉，精确捕捉的结果提高了定位公式中上下游站点采集到的负压波奇异点的时间差△t的精度，从而进一步提高了定位的精度；考虑到小波变换是一种基波可变的信号分析工具，也就是说，不同的小波基波对信号分析的结果将有很大差别，这势必影响最终的处理结果，因此，我们又对比分析了本课题中小波基及尺度的选择问题，依据规则性系数相似性原理对母小波的选择进行了探索性研究；最后，还提出了基于SCADA的泄漏检测与定位系统的软件开发构想及系统的嵌入方案。

A direct method is implemented for computing the free-term coefficient and the Cauchy principal value integral in the higher-order boundary element method for potential flow.

采用直接数值计算方法计算了势流问题高阶边界元方法中的自由项系数和柯西主值积分，建立了波浪与结构物作用的一种高阶边界元方法。

In Chapter 3,we discuss the Cauchy problem for reaction-diffusion system of Fujita'stype with singular coefficients.

第三章讨论具有奇异系数的Fujita型反应扩散方程组的Cauchy问题。

Therefore,the complicated problem is simplified into asolving procedure of a group of infinite dimensional algebra equations.In thefact,not only is a general solution of the problem obtained,but also a method tocompute the dynamic thermal stress distribution at the surface of the cavity afterthe definition of the coefficient of the dynamic thermal stress distribution isgiven.

事实上，不但得到了单连通区域或复连通区域型二维孔洞表面的动态热应力分布问题的一个一般的解析解，而且，在定义了非耦合和耦合无量纲化动态热应力分布系数后，推导出计算单连通区域或复连通区域型二维孔洞表面的动态热应力分布的方法。

As for the diffusive term, it is shifted to undetermined time level to be discretized by divided central difference. The shifting error will be small for weak diffusion problems.

对于弱扩散问题，由于扩散系数比较小，这种转移引起的误差也比较小，从而可以期望得到更精确的数值结果。

Scene data indicate that in the process of actual making the casing into the Horizontal Well ,people used to reduce friction coefficient between the stratum and the Casing, Change the friction type between the casing and the wall,use special casing and centralizer with oriented ring, even join the slurry in the internal casing in order to increase self-casing, etc.

现场资料表明，在实际套管下入过程中，人们往往采用的是减小套管与井壁之间的摩擦系数、改变套管与井壁间的摩擦类型，使用带有导向环的套管和扶正器，甚至在套管内部加入泥浆，以增加套管自重等方法，但这些方法并没有改变套管下入驱动力减少的现实，不能从根本上解决套管下入困难的问题。

Double channel bandpass sampling method for wide band IF signal is presented to settle the problem of blind zone,which exchanges one more sampling channel for simplification of clock circuit and band pass filter.As a practical reconnaissance receiver, real-time processing performance must be considered.Digital channelizing method lays the base of parallel processing by multi DSP chips and discarding of the redundant data resulting from double channel bandpass sampling.

针对带通采样存在着频率覆盖盲区的问题，提出了宽带中频信号双通道带通采样的方法，通过增加一个采样通道既解决了传统处理盲区方法中设计复杂采样时钟电路、高矩形系数滤波器的困难，还缓解了后续DSP处理压力。

In terms of the theory of algebraic geometry, the problem of characteristic polynomial assignment of the closed-loop systems is transferr.

以代数几何方法为工具，将此闭环系统的特征多项式配置问题转化为判别有理映射是否为到上的，推导出多输入的 2 D广义系统Roe sser模型由状态反馈几乎任意配置特征多项式系数的充分条件。

The split between the two groups can hardly be papered over.

这两个团体间的分歧难以掩饰。

This approach not only encourages a greater number of responses, but minimizes the likelihood of stale groupthink.

这种做法不仅鼓励了更多的反应，而且减少跟风的可能性。