查询词典 approximation method

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。

By using of the elastic approximation model and scattering matrix method, we investigate the acoustic phonons transport and thermal conductance in a H-branch four-channel nanostructure.

利用弹性近似模型和散射矩阵方法，研究了低温下多通道量子结构中的弹性声学声子输运和热导的性质。

This thesis research is to develop a new method named "equivalent capacitance approximation" for studying the equivalent circuitry and system power of operating organic light-emitting devices.

中文摘要本论文研究是使用新发展的等效电容逼近法来探讨有机半导体发光元件的等效电路阻抗及负载功率的量化。

The new IRS algorithm has greatly improved the approximation performance of the original reduced set method by embedding a new distance metric called image Euclidean distance into the kernel function.

其中，所谓IRS算法是指在精简集算法的核函数中嵌入一种新的距离度量——图像欧式距离——来改善其迭代近似性能，IRS可以有效地生成新的、位于类别边界附近的虚拟样本以增强给定训练集。

On the basis of the previous studies on sound field separation techniques and based on the Euler formula and the finite difference approximation technique, a new theoretical formula of NAH using pressure and particle velocity measurements is given, and then an experiment is performed to validate the method.

随后通过实验检验了该方法在有背景源干扰情况下实现声场分离和重建的有效性。

It provides a way to find optimal lower dimensional approximations of the given data, and It enormously reduce the storage of the data which is needed when the physical processes is recurred. The physical process can be described in series expansion function that only is related to the time and space. It is optimal approximation of the given data in a certain least squares optimal sense. The most obvious advantage of the method is that it reduces the computation cost and computation time markedly.

它提供了一种描绘物理过程的有效方法，该物理过程可以写成一个只与时间相关的函数和一个只与空间相关的函数的展开式序列，且它们在均方意义上是最优的，在展开式中只需要少量的项数就可较准确地描述该物理过程，因此降低计算维数、减少计算量和节省计算时间是这个方法最明显的优点。

So, the saturation results of some operators including Baskakov operator can be obtained easily, hence laying a basis for studying the approximation transformation theoremof the mixed exponential type integral operators, and presenting a new method for studying the saturation problems.

这样，包含Baskakov型在内的相关积分算子的饱和结果便可以很容易得到，为研究混合指数型积分算子的逼近转化定理奠定了基础，也为研究算子的饱和问题提供了新的方法。

We establish mathematical models of optimal operation schema, and to solve them by feasible direction method and linear approximation.

在管网布局的基础上，以管网投资净现值为目标，建立了管网结构参数优化模型，并充分考虑了输气量、管径、输气压力、管长、增压比、压缩机数目之间的关系，采用混合变量优化方法进行求解。

On the aspect of error compensation, the system using the geometric average sound pressure instead of the arithmetic average sound pressure to get the sound pressure of the measurement point. This method not only reduces the high frequency error in the sound intensity measurement, which compensates the finite difference approximation error, but also greatly reduces the computation of the sound pressure spectrum.

误差补偿方面，课题采用几何平均声压代替通常的算术平均声压来计算双传声器法的声场声压值，这样不仅可以有效的减少声强测量中的高频误差，对有限差分误差起到了补偿作用，而且还大大减小了声压谱计算中的计算量。

Then an improved design method of resonant tank combining first harmonic approximation and simulation in time domain was proposed.

基于所提出的方法设计的参数建立一台220 W的样机，实验结果证实了所提出改进型设计方法的正确性和可行性。

It has been put forward that there exists single Ball point and double Ball points on the symmetrical connecting-rod curves of equilateral mechanisms.

从鲍尔点的形成原理出发，分析对称连杆曲线上鲍尔点的产生条件，提出等边机构的对称连杆曲线上有单鲍尔点和双鲍尔点。

The factory affiliated to the Group primarily manufactures multiple-purpose pincers, baking kits, knives, scissors, kitchenware, gardening tools and beauty care kits as well as other hardware tools, the annual production value of which reaches US$ 30 million dollars.

集团所属工厂主要生产多用钳、烤具、刀具、剪刀、厨具、花园工具、美容套等五金产品，年生产总值3000万美元，产品价廉物美、选料上乘、质量保证，深受国内外客户的青睐