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In this paper, a high order accuracy difference method is presented for solving unsteady convection diffusion equation by using Implicit Perturbation Finite Difference scheme. Firstly, we use the steady convection diffusion equation, the constant coefficients of this equation are expanded to power series of grid-spacings, then the high-order Perturbation Finite Difference scheme is obtained by determining the coefficients of the power series. Put this scheme on unsteady convection diffusion equations and modified it, the IPFD scheme is constructed.

本文利用摄动差分思想，对定常对流扩散方程中的空间微商系数进行摄动展开，展开幂级数系数通过消去摄动格式修正微分方程的截断误差项求出，由此获得方程的隐式摄动差分格式，将此方法应用于非定常对流扩散方程，并加以修正，得到该方程的修正隐式摄动差分格式。

We eat in order to live , but not live in order to eat .

吃是为了生活，但生活不是为了吃。

They are religious in the full sense of the word, and participate in all the graces and privileges of the order, except that they have neither active nor passive voice in the management of the affairs of the order.

他们是宗教在充分意义上的字，并参加所有的青睐和特权的命令，但他们既不积极，也不被动语态的管理事务的秩序。

In order to overcome the technological difficulties encountered in the course of insulation fault diagnosis on the base of dissolved gases analysis, several kinds of mathematic models and actualized methods are brought forward to improve the reliability and veracity of fault diagnosis of transformers. The research works are shown mainly as followings:1 A modified fuzzy multi-criteria method is brought forward for insulation fault diagnosis of transformer. Furthermore, a new method for insulation fault diagnosis is proposed on the base of fuzzy multi-criteria together with rule reasoning. With fuzzy diagnosis in the method, fault reasons are filtrated and then the reasons in low probability are prohibited, Moreover, the left reasons are testified by using rule reasoning and then final concludes are drawn in much less misjudge probability and better results.2 On the base of geometry characteristics of C- partition to sample set of DGA data of transformer, a method is put forward to compute effective radius of neighbor field of a sample, number of clusters and values of initial centers. Moreover, the fuzzy C- means cluster model with adaptive weight is brought forward in the first time and then the fault classifier is designed for insulation fault diagnosis of transformer.3 According to the weakness of the degree of gray of gray incidence, a new formula to compute DGI is put forward and then incidence order criterion is ascertained. Moreover, a new DGI model for fault diagnosis is proposed according to the further analysis to relationship between fault reason and content of oil dissolved gases of transformer.

为解决在应用油中溶解气体分析方法（Dissolved Gases Analysis，简称DGA）诊断变压器内部绝缘故障时所遇到的主要技术难题，论文提出了用于提高变压器故障诊断准确性和可靠性的数学模型及实现方法，主要研究工作如下：1）提出了一种改进的变压器绝缘故障诊断模糊综合评判方法；进一步提出了将模糊综合诊断与规则推理相结合进行绝缘故障诊断的方法，该方法采用模糊推理对故障原因进行"过滤"，滤掉可能性极小的原因，然后进一步利用规则推理验证剩下的可能原因，得出最终结论，大大减少了误判比率，获得了较好的效果。2）根据以变压器DGA数据为特征量的样本空间的c-划分几何特性出发，提出了一种求取样本有效邻域半径和聚类数及聚类中心初值的方法，在此基础上，首次提出了一种自适应加权的变压器绝缘故障诊断的模糊c-均值聚类模型，并设计出故障分类器。3）针对常用灰色关联度的不足，提出了一新的灰色关联度计算公式及确定关联序的准则；并在此基础上，通过深入分析变压器发生绝缘故障时的原因与油中溶解特征气体含量的关系，建立了一种新的故障诊断灰色关联模型；通过实例分析证明，该方法能有效地诊断出变压器绝缘故障及故障部位，大大提高了诊断的准确性。

However, most of the existing projection methods are only first order or incompletely second order accuracy in time.

目前，绝大多数不可压缩数值方法，在时间方向上都仅仅停留在一阶或不完全的二阶精度。

As competitions between people have been intensified significantly over time, people's pressure has been increased dramatically. In order to release the pressure, people would like to do outdoor exercises on holiday. People get used to the life with water and electricity supply and rely on electronic products. Therefore, it is really inconvenient to exercise outdoor without the electricity supply. In order to solve such inconveniency, an innovational product is invented, and the name is called "Inverter."

随著人与人之间竞争越越激，人们的生活压与日俱增，平时工作压大，到假日就想走向户外，藉由各种的休闲活动舒解生活压，然而平时过惯有水有电的生活，对生活家电已是相当依赖，而家电用的是市电，当假日到郊外，没市电，就会产生许多困扰，为消弭远城市所产生的种种，於是就产生一种电子产品-----Inverter，Inverter其主要作用即是将直电转换成交电，其用意乃是运用、船或飞机上之蓄电池

In chapter 4, we first discussed the existence of multiple positive solutions of the second order nonsingular Dirichlet boundary value problem for impulsive differential equations by using the fixed point index theorem in cones . Next, we presented some new existence results for singular boundary value problems for second order impulsive differential equations by using fixed point theorem in cones and Leray-Schauder nonlinear alternative theorem.

第四章我们首先利用锥不动点定理讨论了非奇异二阶脉冲微分方程狄利克莱边值问题多个正解的存在性；其次我们用锥不动点定理和Leray-Schauder型非线性抉择定理，讨论了奇异二阶脉冲微分方程狄利克莱边值问题一个及多个正解的存在性。

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。

The article remarks that in order to modernize our country's agriculture,it is necessary to set things to market,then to industrialise and,in modern logical order,to promote step by step from lower levels to higher ones.

要从根本上解决我国的农业问题，最基本的途径是实现农业现代化。认真地研究和探索我国农业现代化发展中存在的矛盾和问题，对于加速实现我国农业现代化，无疑具有十分重要的意义。

Synthetic biologists plan to move lots of genes and to industrialise the process in a way that will let people order biological parts as routinely as they order electrical components.

最终人们将会象订购电器部件一样订购生理部件。

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％。