查询词典 sampling fraction

The two methods of model simplification are presented for large scale systems, they are the least square approximation and the rational fraction approximation.

本文针对大系统的频域模型简化提出了两种方法：最小二乘近似法和有理分式近似法。

Many researchers have devoted their work to the development of modal analysis extraction techniques in order to obtain more reliable identification of the modal parameters. There are many damping identification methods, but each one has different merit and defect. In order to find which one is the most reliable method with respect to certain characteristics, this thesis focus on how to identify structure's damping in time domain. The following works have been done in this thesis: 1. Investigate four modal analysis methods——the LSCE Method, the Ibrahim Time Domain Method, the Time Domain Collectivity Modal Parameter Method, the Rational Fraction Polynomial Method and improve on the ITD Method in arithmetic.

本文主要做了如下工作： 1、集中研究了四种常用的模态识别方法，即最小二乘复指数法、Ibrahim时域法、时域总体模态参数辨识法及有理分式多项式法，并对ITD法在算法上进行了一定的改进； 2、建立结构动力模型，利用这四种方法在具体条件下识别结构的阻尼，并绘制相应的图； 3、讨论不同的情况下，不同的识别方法对阻尼识别精确性的影响； 4、基于业已明确的阻尼识别的精确性，根据研究的需要，指出在实际的识别过程中，如何选择最佳的识别方法以及识别过程中需要注意的问题； 5、选择最为精确的阻尼识别方法，以导师李书进教授在日本京都大学防灾研究所强震反应实验室所做的一足尺木制结构房屋的动力测试实验为实测模型，识别其阻尼； 6、在本文的最后，尽作者所知，提出了一些需要改进的地方，并对未来的研究方向给出了作者的建议。

A bstract: This paper focus on virtual instrument design of modal parameters identification with curve fitting theory based on rational fraction orthogonal polynomials. Using Forsythe orthogonal polynomials solves the coefficient equation instead of normal power polynomials in order to decrease the morbidity of it, making the orders of coefficient equation reduce to half and increasing computing efficiency.

本文基于有理分式正交多项式曲线拟合理论对振动系统的模态参数辨识进行了虚拟仪器的设计，为了减少系数矩阵的病态，采用 Forsythe 正交多项式代替普通的幂多项式进行求解，使系数矩阵阶次降低近一半，提高了运算速度。

Padé approximation is an effective rational approximation.Using the first derivative of Gaussian function as basic wavelet,Pad conversion is used to obtain its rational fraction approximation.

采用高斯函数一阶导数作为基本小波，用Padé变换获得其有理分式逼近，利用开关电流技术实现小波滤波器可获得小波变换所需的基本小波及其膨胀小波。

The typical Arithmetic Coding does not map a single source to a word, but maps the whole input symbol sequence to a section of 0,1 on the real number axis, the width of which is equal to the probably of the sequence. A representative binary fraction in the section is chosen as real output to get efficient compressed codes.

典型的算术编码不是将单个的信源符号映射成一个码字，而是将整个输入符号序列映射成为实数轴上0，1区间内的一个小区间，其长度等于该序列的概率；在该小区间内选择一个代表性的二进制小数，作为实际的编码输出，从而达到了高效编码的目的。

Also introduced is a heuristic that bypasses a large fraction of this flow recomputation.

并且介绍的启发式绕过这流程重计算的一个大分数。

The results show that, with the increase of extrusion ratio, that is, the increase of deformation, the volume fraction of new grains is growing gradually during deformation, and under certain conditions, dynamic recrystallization can be repeated, thus the grain is significantly refined, which effectively improves the mechanical property of the alloy.

结果表明：随挤压比的增加，即变形量的增加，在变形过程中新晶粒所占体积分数越来越大，且在一定条件下动态再结晶可以重复进行，因此使晶粒得到明显细化，有效提高了合金综合性能。

With decreasing the grain size of austenite before the phase transformation, the transformed ferrite fraction is increased and the final grain size is refined.

在应变、过冷提供相变驱动力的条件下，相变前奥氏体晶粒尺寸对于铁素体微观结构的形成有着重要的影响。

Multiplicity showed that regular exercises were the independent factor of death and rehospitalization within 1 year of chronic heart failure patients with the exception of sex, age, cardiac functional grading, ejection fraction, complication and treatment.

多因素分析显示，排除性别、年龄、心功能分级、射血分数、有无合并症及治疗情况等干扰因素后，规律运动锻炼是预测慢性心力衰竭患者1年内死亡和再住院的独立因素。

With increasing the ceramic volume fraction,d_(33) increased until it reaches a saturation value the and relative permittivity constant rose linear.

压电常数d_(33)随着纤维体积含量的增加迅速增大，最后趋于饱和，介电常数随着纤维体积含量的增加几乎呈线性增加。

When this condition occurs, inbound replication with the source partner is stopped on the destination domain controller and event ID 2042 is logged in the Directory Services event log.

计算机密码学是研究计算机信息加密、解密及其变换的科学，是数学和计算机的交义学科，也是一门新兴的学科。

Instructions: click on the thumbnails to see a larger image, then use the left-right arrow keys to scroll through the slideshow.

使用说明：滑鼠点在小图上即可放大观赏。开启后键盘左右键可用来换照片。