查询词典 backward difference

The problem gives a practicable methods to solve the existence and multiplicity of periodic and subharmonic solutions of second order forward and backward functional difference equations.

论文研究的问题和所得的结论具有比较重要的理论价值和应用价值。论文思路清晰，逻辑性强，推理严密，结论具有创新性。

We found that it is the effect of odd-order term of f which describe the total energy collocation between forward wave and backward wave that causes the difference of modulation instability between normal dispersion region and abnormal dispersion region.

第三，根据增益谱的比较，我们从色散关系式中看到了产生这种变化的原因。正是由于存在f奇次项的影响而导致了这种在正常色散区和反常色散区变化趋势的不同。

Look from historical condition,; of economic technology instability looks from external environment, the infrastructure such as traffic, communication, irrigation works is backward, invest good environment difference, return rate is low.

从历史条件看，经济技术基础薄弱；从客观环境看，交通、通讯、水利等基础设施落后，投资硬环境差，回报率低。

While using three—points backward finite difference to imitate the radiation condition, we accept Raven's〓 idea to shift collocation points upstream a short distance.

在用三点向后差分格式模拟辐射条件时，接受了Raven〓的建议，将单元控制点向后移动了一段距离。

All sorts of inland river that have at that time from Guangdong carry shipping to look, because scientific guiding and management are lacked on boat type development, let things drift, so although have a few better ships type, but quite all sorts of one part is major even carriage shipping is dated and backward, line difference, draft is late, boat engine paddle does not match, speek of a ship or plane is small, cost can be high, economic benefits is poor, hang ship of paddle motor vessel especially.

从广东当时所拥有的各种内河运输船舶来看，由于在船型机型发展上缺乏科学的引导和治理，放任自流，所以虽有一些较好的船型机型，但相当一部分甚至大部分各种运输船舶都陈旧落后，线型差，吃水深，船机桨不匹配，航速低，耗能高，经济效益差，非凡是挂桨机船舶。

This thesis is divided into six parts. The first chapter is preface, the current status of research in the inverse problems for parabolic partial differential equations is reported; the second chapter is "regularization methods for numerical differentiation and their applications ", in this chapter we investigate many regularization methods from a viewpoint of regularization theory and algorithm, some applications in the inverse problems for parabolic partial differential equations are given; the third chapter is "spectral regularization methods". Based on Fourier analysis, within the framework of regularization theory, we apply the spectral methods to some ill-posed problems. Many numerical experiments are done in order to show the validity of the methods; the fourth chapter is devoted to wavelet dual least squares method and a revised wavelet method; in the fifth chapter,we combine finite difference method with method of lines and apply it to the backward heat conduction problem in time; in the sixth chapter "identification problems for unknown source ", the essence and the degree of two problems related to source identification are pointed out, at the same time, some numerical methods are reported.

本文分为六个部分，第一章前言简要分析了国内外抛物型偏微分方程反问题的研究现状；第二章数值微分的正则化及其应用从正则化理论和算法的角度出发，考察了许多正则化方法，还给出了数值微分在抛物型偏微分方程反问题的一些应用；第三章谱正则化方法是在Fourier分析的基础上，在一般正则化理论的框架下，给出了这种方法在各种不适定问题中的应用，数值实验表明谱方法是有效的；第四章研究了小波对偶最小二乘方法和改进的小波方法；第五章主要研究了有限差分方法结合线方法在时间反向热传导问题中的应用；第六章是未知源识别问题，主要指出了两类未知源问题的不适定程度和不适定本质，同时报告了一些数值方法。

Accordingly, region of relatively backward ministry of Chinese and Western is fostering region economy new point of growth, contractible region economy grows difference.

因此，相对落后的中西部地带在培育区域经济新增长点，缩小地区经济发展差距。。。

The difference for the convective and pressure terms is based on the flux vector splitting method developed by Van Leer, and the alternating forward/backward vertical line Gauss-Siedel relaxation algorithm is employed to solve the differenced equations.

对通量项和压力项用Van Leer发展的迎风方法进行矢通量分裂，对离散方程采用交替方向的垂直线Gauss-Seidel方法迭代求解。

Breath, muscle contraction of the buttocks; arch body, as far as possible to hold his head, right leg straight towards the ceiling (peg-leg knee in order to avoid muscle tension).

呼气，收缩臀部肌肉；拱起身体，尽量抬起头来，右腿伸直朝向天花板（膝微屈，以避免肌肉紧张）。

The cost of moving grain food products was unchanged from May, but year over year are up 8%.

粮食产品的运输费用与5月份相比没有变化，但却比去年同期高8％。