离散数学

These math operations involve not only the simple plus, minus, and multiplication operation but also the function of signal analysis such as Fast Fourier Transform and Discrete Cosine Transform.

这些数学运算从简单的加减法和乘法到复杂滤波以及信号分析功能如快速傅立叶变换和离散余弦变换都具有显著的优势。

Because of rigorous theory is lack, method that metal plastic stream is supposed through geometric proportion condensation, makes that cell quantity of the partition complex special-shaped product and disperse dots of die surface are many, reduce regression precision of streamline die design, sometimes can't be built mathematics module and its optimization.

由于缺乏严密的理论支持，仍假设金属流动按等比压缩方式研究，致使复杂拔挤异型材划分等比率单元过细及描述模腔曲面的离散点过多，降低了流线模设计的回归精度，甚至无法建立模腔数学模型及其优化。

The paper approaches the inapplicability of analysis method to the two above-mentioned mathematical models by using dispersed demoted numerical virtue method.

针对两个数学模型难以用解析法求解的情况，采用离散化数值求解方法进行。

ABSTRACT Aiming at problems of trans-vector controller in a vehicle-carried induction motor such as variable rotor and stator resistance following motor temperature, and their inductance varying with flux saturation degrees. Firstly, CSI and VSI are introduced, for CSI, it can hold the advantages both FOC and DTC using stator flux directional, PI parameter and simulation are also introduced. Secondly, equations of IM in the synchronous rotary frame and its static counterpart, as figuring in the saturation condition of magnetic field, are dealt in this paper and the simulation results are presented. Thereafter, the parameter designing of PI trans-vector controller is processed, which features the non-linear model. In practical realization, as neglecting the dynamical change of motor inductance, this paper employs online modification of inductance parameters, according to the flux saturation, then transforms the non-linear equations into linear ones, and so compacts the structure of controller. Thirdly, in view of the maximum torque output is extraordinary requisite when Electrical Vehicle start up, accelerate, and overtake, this paper issues the maximum torque when both inverter and battery capacity is corporeally definite. Fourthly, on-line differentiating and analyzing both rotor's time constants and its flux by using the expanding order reduction and discrete Kalman filter equation are fathomed, in order to realize high-performance trans-vector algorithm, and also the simulation results are presented. Fifthly, the close-loop regenerative brake system, when the EV's torque is set constant, is deduced; at the same time, unification of electric drive model and brake model is executed. Combined with maximum charge current demands, the mathematical model for online yielding torque as a demand.

本论文针对车载异步电机在矢量控制器所遇到的问题：定转子电阻随温度变化及随电机饱和程度变化的转子电感及定子电感而影响电机调速性能提出一套完整的解决方案：分析了电流型逆变器和电压型逆变器在实现矢量控制时控制器参数的计算，分析出对于电流型逆变器在采用定子磁场定向时，其性能同时具有矢量控制和直接转矩控制两者的优势，并对电压型逆变器在转子磁场定向下的模型进行了仿真研究；建立异步电机非线性模型，推导出考虑磁饱和时异步电机在同步旋转坐标系及静止坐标系下的方程，并做出了仿真结果，建立异步电机在非线性模型下的矢量控制调节器的PI参数设计，在实际应用中，若忽略电机电感的动态变化，可以根据当前的磁路饱和状态而在线修正电感参数，从而将非线性方程线性化，降低控制器的复杂度；考虑到电动汽车在起动和加速超车时需要电机有最大转矩输出，本文讨论在逆变器容量一定和电池供电能力有限的情况下电机最大转矩输出问题；推导了异步电机扩展降阶、离散卡尔曼滤波方程在线辨识转子时间常数和转子磁通，用于实现高性能的矢量控制算法，并给出了仿真结果；推导出了电动汽车恒转矩给定的闭环回馈制动系统，实现了电动控制模型和制动模型的统一，而且结合铅酸电池最大充电电流的要求，为制动转矩在线给定建立了数学模型；设计了基于双DSP系统的高性能矢量控制器软硬件框图，并以大量实验数据说明矢量控制在电动汽车应用的实际应用状况。

Boundary element method is a kind of numerical algorithm on boundary; it is based on the boundary integral equation and employs the element discretization technique.

边界元属于边界型的数值方法，它是以边界积分方程为数学基础，同时采用了有限元法的单元离散技术。

At first, this paper surveys nonlinear control and the applications of neural networks in control respectively. Then it studies definitions, mathematical descriptions and conditions of invertibility for nonlinear systems, which are used to analyze the feasibility of inverse system control method. Conclusions about the feasibility of inverse control and the realizability of αth-order inverse systems in engineering are achieved. Furthermore, this paper discusses the feasibility, structure and identification of neural network αth-order inverse system for general single-input single-output continuous or discrete nonlinear systems and various composite control methods based on the αth-order inverse. At last, as a part work of an actual project, this paper focuses on the design of neural network αth-order inverse control method for thyristor controlled series compensation in power systems and its effect in improving the stability of power systems.

本文首先分别概述非线性系统的控制与人工神经网络在控制中的应用；然后研究非线性系统各种可逆性的定义、数学描述及可逆性条件，并用于分析逆系统控制方法的可行性，得出有关逆系统控制方法可行性的结论，阐明一般情况下α阶逆系统才工程可实现；接着本文针对一般单输入单输出连续、离散非线性系统，研究神经网络α阶逆系统的可行性、结构与辨识以及基于神经网络α阶逆系统的各种复合控制方法，并给出应用例子；最后本文结合实际项目，针对采用可控串补的电力系统，设计神经网络α阶逆系统控制方法，研究其对提高电力系统稳定性的作用。

Then we summarize three basic mathematical-mechanical models of granular flow dynamics: kinetic theory model, friction-plasticity model and discrete element simulation model.

首先叙述了颗粒流研究的背景和基本概念，接着概述了颗粒流动力学研究的三种基本数学力学模型：颗粒动理论模型、摩擦塑性模型和离散元模拟模型。

Chapter two gives mathematical methods of controlled objects: state space method,dispersing method of dynamic equation about controlled objects, and solution and propertiesof linear difference equation.

第二章：介绍了受控对象的数学描述方法状态空间法、受控对象动态方程的离散化方法、线性差分方程的解及其性质。

The neural networks correction method combining the local map with radial based function networks and the global map with linear transform was applied to calculate the deformation resistance of the strip and the friction coefficient in the rolling deforming region.

采用径向基函数的局部映射和全局线性映射相结合的神经网络校正模型求解带钢变形抗力和轧制变形区的摩擦因数；并采用轧制变形区离散化方法分析轧制变形区内张力、摩擦力及金属变形抗力等在带钢轧制方向上的分布规律，从而建立轧制力在线计算数学模型。

Many mathematical models in physics, mechanics, biology and astronomy are given in such forms.

大量的物理、力学、生物学以及天文学问题的数学模型都是有连续的和离散的迭代过程描述的。

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。