离散化

Considering the [2] and barycentric subdivision method, chapter 3 imports some discrete objects-discrete parametric curves net.

第三章以离散化思想为指导，参考文献[2] ，并利用重心加细的方法，给出了一系列离散化的研究对象，如离散参数曲线网等。

Restricted by the assumption of low-order linear displacement approximation in each block, Discrete Element Methods often have to mesh many continuum parts of the problem domain into small discrete blocks when simulating crack propagation problems, and the result is very sensitive to the very way that divides the domain.

一般离散单元计算方法受离散块体低阶线性位移近似的限制，在模拟开裂过程时，需要将大部分实际上连续的区域离散化，离散方式对分析结果有显著影响。

For the diffractive optical element realizing beam shaping in the fractional Fourier transform domain,the transform matrix calculated by the discrete sampling points was compared with that calculated by the Fresnel integral,and the discretization error of the intensity distribution on the output plane was qualitatively obtained.

针对分数傅里叶变换衍射光学光束整形器件，比较了按离散点与按菲涅耳积分计算得到的变换矩阵间的差距，从中分析得出按离散点计算的变换矩阵引入的离散化误差与分数傅里叶变换系统参数的关系。

In this paper a discretization algorithm based on importance of cut point. Firstly, the paper gives some concept of rough set theory:decision table,indiscernible relation,information entropy and condition entropy.

粗糙集理论可以用在数据挖掘的各个阶段，该文研究了粗糙集理论在数据挖掘的数据离散化阶段的应用，并提出了一个新的决策表离散化算法。l 基本概念及离散化问题的描述定义1 。

For pratical reasons, the method of increasing the number of iteration m so as to enhance the security can only be used in the case that parameters can match exactly, like a digital encryption system.

本文对以上的离散实际混沌加密系统采用多精度自扰动的离散化策略，从而避免了传统的离散化方法所带来的缺陷，使这类数字混沌加密系统走向实用。

First, the problem of choosing sample time in the discretized variable structure control of continuous-time systems is analyzed, then direct design methods of variable structure for discrete-time systems are discussed.

首先研究了将连续系统的变结构控制理论离散化后应用在离散系统时采样时间选取的问题，接下来讨论了直接针对离散系统的变结构控制的设计。

The use of CAE on the analysis of motor rotor-bearing system, During the numeric model processes, the finite element method is used to build the discrete model and analytical theory of the rotor-bearing system. The entire system is divided into several dividable substructures, each of which develops individual systematic mathematic model. Finally, the motion equation of whole structures is combined by the integrity of the dynamic variables and force balances on connections of each substructure.

本文探讨马达转子-轴承-框架系统之结构动态特性，提供动态特性之关系设计过程中，其转子-轴承系统的动态设计考量方法，利用电脑辅助工程技术，以有限元素方法，先将马达转子-轴承-框架系统分离各个部位成为子结构，将子结构个别的数学模型加以离散化，最后以各子结构结合面上节点的动态参数一致性及力系平衡，连结离散化子结构成为整体结构的运动方程式。

Mass of methods of the discretization have not think over relativity between before discretization and discretizated.The discretization of attributes are accomplished independence.It can change indiscernibility relation in information system and induce illogicality and redundance dot.

针对大多数的离散化方法没有考虑不同连续属性离散化结果间的互补性和相关性，每个属性的离散化过程都是独立进行的，往往会改变信息系统不可分辩关系，容易产生不合理和冗余的离散化划分点。

Considering the technical requirements,the stability andthe steady performance,the quantitative requirement for sampling frequency is present indiscrete control system.Considering that there is a step delay in discrete control in grid on inverter with a Lfilter,the quantitative relationship between critical FCCR and sampling frequency isanalyzed,and the steady performance is analyzed.Considering the technical requirements,the stability and the steady performance,the quantitative requirement for samplingfrequency is present in discrete control system with a step delay.

在L型并电加热管网中，考虑到离散化控制存在滞后一拍的问题时，本文分析并获得了离散PI控制系统稳定范围时闭环根临界频率fnmax和采样频率fs之间的定量关系；针对存在滞后一拍可能引起系统稳态特性下降的问题，分析了PI控制滞后一拍对频域特性造成的影响，综合考虑并网指标、稳定性要求和离散化对稳态特性影响三个主要因素，推导了存在滞后一拍的离散化PI控制对最低采样频率的量化要求。

Traditionally, a surface is usually scatted in an array of 3D data points which are topologically connected by rows and columns to form a rectangular mesh. This method can't meet the requirement of description and measurement for some complex surfaces. On the basis of tracing border points, a new method is proposed to deliver 3D data points of surfaces, which are topologically constructed with optimum rectangular and triangular mesh. In order to measure surface efficiently and safely with NC machine, an optimization of measurement paths is proposed to avoid interference between the measuring tool and the surface with holes. The curve design is the basis of surface modeling.

数控测量技术的发展为测量自动化、集成化、智能化提供了可能，而对于复杂曲面的自动测量规划则是测量技术中的难点问题，平行截面等数目测点分布和四边拓扑测点分布规划方法，不论在测点分布的合理性上还是在网格结构的优化方面，均难以满足形状或边界较复杂曲面的离散化描述和曲面造型的要求，为了实现任意拓扑曲面的自动测量，本文对复杂曲面的合理离散化描述和自动测量问题进行了研究，提出了基于边界跟踪、优化网格的测点自动分布规划和四边、三角混合网格的生成方法：同时对具有孔洞或测量干涉凸台等非完整曲面的测量路径优化问题进行了研究，提出了路径优化方法。

According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.

曝气设备的动力效率在叶轮转速为120rpm～150rpm时取得最大值，此时氧利用率和充氧能力也具有较高值。

The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.

稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世，形体几无变化。