数学近似法

Homotopy perturbation method; MOL method; nonlinear partial differential equation; approximate solution

基础科学，数学，数学分析同伦摄动法；直线法；非线性偏微分方程；近似解

According to the definition of the minimum zone method, the mathematical model is presented for evaluating flatness error and establishing datum plane equation.

分析了常用的近似评定法(三点法、对角线法、最小二乘法等)存在的局限性，根据最小区域法的定义，给出了基准平面方程及平面度误差评定目标函数数学模型的建立方法，并举例说明了采用Matlab进行平面度误差的计算。

Among used machine learning methods, the gradient descent method is widely used to train various classifiers, such as Back-propagation neural network and linear text classifier. However, the gradient descent method is easily trapped into a local minimum and slowly converges. Thus, this study presents a gradient forecasting search method based on prediction methods to enhance the performance of the gradient descent method in order to develop a more efficient and precise machine learning method for Web mining.However, a prediction method with few sample data items and precise forecasting ability is a key issue to the gradient forecasting search method. Applying statistic-based prediction methods to implement GFSM is unsuitable because they require a large number of data items to model a prediction model. In the contrast with statistic-based prediction methods, GM(1,1) grey prediction model does not need a large number of data items to build a prediction model, and it has low computational load. However, the original GM(1,1) grey prediction model uses a mathematical hypothesis and approximation to transform a continuous differential equation into a discrete difference equation in order to model a forecasting model.

其中梯度法是一个最常被使用来实现机器学习的方法之一，然而梯度法具有学习速度慢以及容易陷入局部最佳解的缺点，因此，本研究提出一个梯度预测搜寻法则(gradient forecasting search method， GFSM)来改善传统梯度法的缺点，用来提升一些以梯度学习法则为基础的分类器在资讯探勘上的效率与正确性；而一个所需资料量少、计算复杂度低且精确的预测模型是梯度预测搜寻法能否有效进行最佳解搜寻之关键因素，传统统计为基础之预测方法的缺点是需要较大量的数据进行预测，因此计算复杂度高，灰色预测模型具有建模资料少且计算复杂度低等优点，然而灰色预测理论以连续之微分方程式为基础，并且透过一些数学上的假设与近似，将连续之微分方程式转换成离散之差分方程式来对离散型资料进行建模及预测，这样的作法不尽合理，且缺乏数学理论上的完备性，因为在转换过程中已经造成建模上的误差，且建模过程仅考虑相邻的两个资料点关系，无法正确反应数列未来的变化趋势。

This makes more and more people pay more attention to studies and applications of numerical simulation in thermal recovery. In this research, we have developed a reliable mathematical model for thermal recovery, which takes a full consideration of the effect of viscos, gravitical and capillary forces on the three-phase flow of gas, water and oil, the effect of the temperature on the medium characteristics of liquid and solid, the phase equilibrium of gas-liquid in each component, heat transportation including connection, conduction and radiation as well as heat losses in both the overburn and underlying strata. In the space discreation of the mathematical model, we have proposed a new method based on the improvement of the conventional nine-points difference approximation, which has a higher difference accurancy.

本项研究以热力采油的主要机理为基础，充分考虑在粘性力、重力和毛管力作用下油水气三相流动，考虑温度对各种流体和固体介质物性的影响，考虑每一组分中汽液两相的相平衡，考虑热在地层中的传导、对流和辐射以及上下盖层的热损失，利用热力学第一定律、质量守恒定律和流体迁移定律，建立了正确可靠的注蒸汽数学模型；在对数学模型进行空间离散时，利用控制有限体积积分法，对以往的九点差分近似作了合理的改进，使其具有较高的差分近似精度：结果表明，该公式的近似精度要比以往文献中所给的九点差分近似精度高，可以认为，在油藏数值模拟中，如果遇到非均质情况，使用这种九点差分近似更合理。

The paper analyses material transportation problem and give the solvable methods; analyses delivery vehicle route problem, and then construct its corresponding mathematical model and present a heuristic algorithm based on C—W algorithm; analyses the optimum scheduling problem of trucks, and then construct its corresponding mathematical model and put forward a new algorithm; analyses the Postal Transportation Problem which will perhaps be used in supply chain of manufacturing system, and then construct its corresponding mathematical model and present an approximation algorithm.

分析了制造系统供应链中供需平衡、供需不平衡、有转运等各种情况下的物资调运问题，给出了求解方法；分析了制造系统供应链配送作业中的配送车辆路线问题，建立了相应的数学模型，提出了一种基于C-W算法的启发式算法，该算法较好地解决了有时间约束的配送问题；分析了制造系统供应链中的货运卡车优化调度问题，建立了相应的数学模型，提出了一种基于表上作业法的求解算法；分析了制造系统供应链中有潜在利用价值的邮政运输方式问题，在详细描述了该问题的基础上，建立了相应的数学模型，提出了一种近似求解算法，该算法较好地解决了邮政运输方式这样的多种物流、多种运输方式，有严格时限和众多外部约束的特大型、复杂、并行的交连系统的计划调度问题。

At first, an approximated mathematical model is presented. Then, the system manager can compute the optimal control policy via the method of successive approximation. Based on the above-mentioned algorithm, we design an intelligent system with feedback control to regulate the allocation of limited channels of trunk circuit. This system will continuously detect the status of whole cellular network. Once the system parameters cross the predefined threshold, the recomputing mechanism will be activated.

首先针对系统的近似数学模型先將其定义出来，然后就可以用连续逼近法將最佳控管决策计算出来，这样的最佳决策演算法我们把它设计在一个有迴授机制的智慧型决策系统裹，此决策系统將不断地侦测行动通讯网路运作的情形，一旦网路参数变化超过某个预定的临界值时，整个最佳决策演算法將被启动，系统的近似数学模型將依新的参数重新定义，接下来同样地写出最佳方程式並用连续逼近法计算出新的最佳控管决策。

In this paper, the stray light and ghost image caused by multi-reflection in high power infrared optical systems are analyzed and discussed, and the comprehensive method incorporating paraxial approximation and real ray trace is presented; the data structure of binary tree is used in the storage of interdata so that the storage problem of huge-size data is resolved.

本文主要研究了大功率红外光学系统中光学表面多重反射而形成的杂散光及其数学模型与计算方法，提出了将近轴近似法和有限光线追迹法相结合的综合分析方法；同时在数据存储方式上采用二叉树这种数据结构，巧妙地解决了鬼像分析中海量的中间数据存储的问题。

In chapter 4, some vector mathematical definitions are first given to position tolerance zones; second, the principle of variation geometry is introduced, and the mathematical foundation of automatic generation of a approximate linear equation of tolerance design function by variation geometry is first proven; tangent method and two-point slope method based variation geometry are main studied.

第四章首先对一些位置公差带给出了矢量化的数学定义；然后介绍了变动几何的原理，首次论证了变动几何能产生近似线性公差设计函数的数学依据，并着重研究了基于变动几何的切线法和二点斜率法。

The approximation solution of the biomathematical model of muscular blood vessel under the condition of the nonresonant case is obtained. The expansion method for two variables of perturbation theory is used and the approximation solutions are given to the biomathematical model of muscular blood vessel under two cases.

求得了具有小阻尼、硬外激励的肌型血管生物数学模型在非共振情形下的一次近似解，并利用两变量展开法，经方程演化，求得了具有小阻尼、弱外激励的肌型血管生物数学模型在非共振和共振两种情况下的首次渐近解。

This paper reviews and summarizes the progress in this field as follows: the mathematical model and the difficulty of the analytical solutions is introduced; discusses the latest progress of the numerical solutions is discussed; the finite difference method, the Godunov method, the Boltzmann method, and the KFVS method of one-dimensional dam-break problem are introduced; the TVD method, the discontinuous finite element method, the finite volume method and characteristic method of two-dimensional dam-break problem are discussed; the applicability, the advantage and the disadvantage of each method are analyzed; and the progress in the numerical calculations of flow of fluid with free surface are presented.

回顾和总结了国内外对溃坝水流演进问题的研究进展：介绍了溃坝水流的数学模型及解析解法存在的困难，进而讨论了数值解法的最新进展；论述了求解溃坝水流一维问题的有限差分法、近似黎曼解的Godunov格式法、Boltzmann法、KFVS法和二维问题的TVD格式法、间断有限元法、有限体积法、特征线法，并分析了各种方法的适用范围和优缺点，及讨论了限制函数的使用；介绍了利用自由水面追踪方法计算溃坝水流的研究进展，并根据目前存在的不足和实际工程的需要，提出了进一步研究的方向和发展趋势。

The split between the two groups can hardly be papered over.

这两个团体间的分歧难以掩饰。

This approach not only encourages a greater number of responses, but minimizes the likelihood of stale groupthink.

这种做法不仅鼓励了更多的反应，而且减少跟风的可能性。