数学模型

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。

In this thesis a mathematical model referring to the relationship between the case depth and carbon distribution by using a nonlinear regression. The electromagnetic characteristics in carburized materials were discussed. Results show that inductivity and magnetic inductivity depend on the carbon concentration in carburized layer. A relationship model between the electric, magnetic inductivity and carbon concentration was built.

结合渗碳材料的碳浓度和组织状态对电导率和磁导率的影响规律，建立了渗碳材料电导率和磁导率与碳浓度的关系模型，利用该模型及渗碳层深度和碳浓度分布关系的数学模型，建立了渗碳层深度与渗层电磁性能的关系，为实现对渗碳层深度的无损检测提供了可靠的理论与实验基础。

Meanwhile, it is also an important and difficult issue of automatic system of the ironmaking process.

高炉炉温预测模型是炼铁过程自动控制的核心数学模型之一，提高炉温预测精度是模型开发的关键难题。

Using LaGrange theorem on base of analyzing the elastic prop model tension system of band saw machine, the dynamics model of elastic prop tension system of band saw machine has been established and converted to mathematics model applying the modern control theory.

本文以MJ317型木工杠杆压砣张紧系统的带锯机改造成弹性挺杆张紧系统的带锯机为研究对象，通过对带锯机弹性挺杆式张紧系统的弹性动力学分析，运用拉格朗日定理建立了张紧系统的动力学模型，并应用现代控制理论将模型转换成数学模型。

A new mathematical model is built based on the laminar flow model and coalescence and redispersion model.

在层状扩散模型和聚并分散模型的基础上，建立了一个新的数学模型，以1—萘酚与对氨基苯磺酸重氮盐这一竞争串联偶氮化合反应体系为例，计算了反映微观混合状态的离集指数。

As far as reason for deficiency, the fault expert database is built for helping administrators determine the reason for deficiency;. As for failure prediction,the mathematic models,the logarithmic normal distribution model of network software faults and the exponential distribution model of network hardware faults,are established.

对于故障原因，建立了故障专家库以帮助管理人员确定故障原因；对于故障预测，建立了数学模型——网络软件故障率的对数正态分布模型和网络硬件故障率的指数分布模型。

Based on the properties of miniature PSA oxygen production and a linear driving force approximation, a mathematical model for PSA processes of a Special Miniature Oxygen Concentrator is developed in this paper. The boundary and initial conditions for the model are analyzed and determined, and the finite difference method is applied to solve the partial differential equations.

基于微型变压吸附氧氮分离过程的特点和线性推动力模型，建立了描述该过程的数学模型，给出了求解的边界条件和初始条件，采用有限差分法对模型进行了求解。

The mathematical model of the linear induction motor is built in the way of motor science, and then the control model of the linear motor feed system is proposed, and the relations between the parameters in the model and the system dynamic performances are studied, using the Simulink Module in MATLAB.

从电机学的角度建立了直线感应电机的数学模型，然后又建立了直线电机进给系统的控制模型，通过MATLAB的Simulink功能模块仿真分析模型中各参数和系统动态稳定性的关系。

Based on basal mathematical model of induction motor, affine nonlinear model, Euler-Lagrange and port-controlled Hamiltonian dissipation model, are obtained.

根据感应电动机的基本动态数学模型，得到仿射非线性模型、欧拉－拉格朗日及端口受控的哈密顿耗散模型。

The mathematics model , physics model and geometrical model for numerical simulation about microbus temperature field is built based on the microbus s thermal translating and substance translating theory .

结合微型面包车的传热与传质机理以及SC6350车型，建立了温度场仿真的数学模型、物理模型和几何模型。

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％。