查询词典 backward difference

An improved derivative estimation algorithm with a low-pass filter that can suppress the influence of high-frequency noise is suggested to remove potential drawbacks of the backward difference that was applied in neural network inversion dynamic compensation method, such as large estimation error in the presence of noise and price increase of hardware realization when high estimation accuracy is required.

针对神经网络逆动态补偿策略中基于向后差分的微分估计算法在噪声环境下存在较大的微分估计误差，且提高估计精度会增加硬件成本等缺陷，提出了改进的微分估计算法，并以加速度传感器为例，设计了动态补偿实验装置，给出了基于改进的微分估计算法的动态补偿算法的实现步骤。

The control volume integration was applied to deduce the discrete expressions of the convection-diffusion equations. The staggered grid and SIMPLE algorithm were introduced to deal with coupling between pressure and velocity, and then the numerical computation expressions of such variables as fluid flow velocity and pressure were deduced. Using the backward difference method and incremental theory to discretize the governing equations for fields of chemical reaction, material structure and chemorheology, the numerical computation expressions of variables such as the monomer conversion, average molecular weight and fluid viscosity were constructed.

应用控制容积积分法导出了对流—扩散方程的离散表达式，引入交错网格技术与SIMPLE算法，实现了耦合的压力场与速度场的分离式求解，推导得到了流体的流动速度、压力等物理量的数值计算式；采用向后差分方法和增量方法，实现了化学反应场、材料结构场、化学流变场控制方程的离散，获得了反应转化率、聚合物平均相对分子质量、流体黏度等物理量的数值计算式。

Those equations are dispersed in space by iso-parameter elementmethod and in time by using backward difference. A numerical simulator is established byFortran, the ideas of high part make the of structure program clear, maintain easy, calculationeffective.

在此基础上利用Fortran语言编制了有限元方法的油藏模拟器，采用等参元对渗流方程在空间上离散，采用向后差分在时间上离散，线性方程组的求解采用变带宽高斯消去法，该方法充分利用刚度矩阵呈条带状和其对称性的特点，大大减少了所需存储空间。

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。

In this paper, a novel feature MFCC_FWD_BWD, which is based on forward-backward difference dynamic parameters, is presented to satisfy the requirement that the feature construction matrix is invertible for PMC.

本文首先提出了一种基于前后向差分动态参数的特征MFCC_FWD_BWD，该特征满足PMC对特征构造矩阵可逆的要求。

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。

In conclusion, the results of multilevel model analysis showed that the GERD score of resident in Wuhan was relatively higher and had significant difference with that in Guangzhou, however, that in Shanghai, Beijing and Xi\'an had no significant difference compared with that in Guangzhou. That is to say, the prevalence of GERD in Wuhan was relatively higher compared with the other four survey sites; the residents'health status more worse, the GERD score more higher, and the influence of health status on GERD score was also effected by the region difference between Wuhan and Guangzhou; residents lived in rural region with lower education level, worse spirit status were more likely to suffer from GERD; Moreover, those residents who had family history of GI tumors or other GI diseases, some anamneses (such as dyspepsia, gastritis, rheumatic arthritis), and some diseases (such as irritable bowel syndrome and aerophagia) were also more likely to report GERD. However, no significant association was found between GERD and some other factors in this survey, such as sex, age, etc.

总之，多水平模型分析结果显示，与广州相比，上海、北京和西安居民的GERD总评分没有明显的差异，而武汉居民的GERD总评分则相对较高，即表示武汉的GERD发病率在5个调查城市中相对较高；居民的总体健康状况越差，其GERD总评分越高，且其对GERD总评分的影响受到武汉与广州之间地域差异的影响；农村居民、文化程度越低、精神状况越差者更容易患GERD；另外，那些有胃肠道疾病或肿瘤家族史，既往患有胃炎、消化不良、风湿性关节炎，现患有肠易激综合征、吞气症的人，患GERD的可能性更大，而性别、年龄等因素，本研究未发现其与GERD有显著的关系。

The scattering properties of particles with different shape parameters are simulated respectively in the modes of reflection and refraction. Both in the modes of reflection and refraction, the phase difference of non-spherical particle's PDA signal is the unbiased estimate of the corresponding phase difference of ideal spherical particle, and the standard deviation of angle roughness scale on particle surface impacts little on the distribution of phase difference.

本文通过物理光学的方法分析了非理想球形粒子的散射特性，利用物理光学中的稳相点理论，导出了非理想球形粒子散射光的相位表达形式，分析了非理想球形粒子的形状对PDA信号相位及相位差的影响，建立了非理想球形粒子的尺寸分布与PDA信号相位差分布之间的关系。

A strange and mysterious deep sea creature.

一种奇异、神秘的深海生物。

It's a yellow rectangle .

这是黄色的长方形。