查询词典 mathematical approximation

The spread paths of common mode and differential mode noises in an SMPS under electrical fast transient/burst are studied and discussed. Hereby for single transient pulse, the vector fitting method is adopted combining rational function approximation according to the tested waveform to construct the a mathematical modeling of frequency, then a pole-residue representation is obtained by partial fraction expansion, and the last step are to draw a state space description and equivalent circuit.

在分析开关电源进行电快速瞬变脉冲群骚扰试验时共模和差模噪声的传播途径的基础上，对于单个脉冲，根据试验数据采用矢量匹配法结合有理函数逼近构造得到频域下的数学模型，通过部分分式展开得到零极点表达式，并最终得到相应的状态空间方程以及等效电路。

At the early 1980s, is an effective mathematic tool to deal with the uncertain or fuzzy knowledge. Rough rule theory has been widely used in information retrieval, digital library, software engineering and knowledge discovery. Its main idea includes acquisition of rough decision rules by reduction of data under the condition of keeping an invariability of classification capacity. And it basically represents a concept by a pair of approximation sets according to the partition on the given data based on the indiscernibility relation. Rough sets theory is well suited to deal with inconsistency of the rough approximations. So it is a new mathematical tool dealing with vagueness and uncertainty, and has found its applications in many areas such as AI, KDD, pattern recognition and classification and fault diagnosis.

主要完成了以下几个方面的工作：(1)对于高速移动机器人车道线跟踪问题中的规则知识获取，首先阐述了模糊逻辑系统的基本特点、工作原理和基本作法，分析了模糊规则知识获取过于依赖专家经验知识、对于每一个细节几乎都需要人工主观经验的参与、难以处理大数据集样本等方面的不足，进而阐述了粗糙集合理论的基本特点、基于粗糙集合理论的规则获取的关键技术和工作原理，为后续章节中经典粗糙集合模型的扩展及粗糙决策规则集的性能分析做好基础；(2)在经典粗糙集理论及其一般扩展的可变精度粗糙集VPRS的基础上，提出了非均匀可变精度粗糙集模型k-VPRS。

In this paper, mathematical model of optimal operation of natural gas gathering and distributing pipeline network system was formed according to analyzing influencing factors on this system, and linear approximation method and complex method were adopted to resolve it.

通过分析影响天然气输配气管网系统运行的各种因素，建立了天然气输配气管网系统运行优化数学模型，并分别采用线性逼近法和复合形法进行模型求解。

Objective To investigate the effects of interleukin-1 β converting enzyme gene on the biologic characteristics of ovarian cancer cells.

目的 探讨白细胞介素-1 β转换酶的表达，对卵巢癌细胞生物学特性的影响。

Campylobacter: This illness is the most commonly identified cause of diarrheal illness in the world.

弯曲：这种病是最常见的原因查明腹泻病，在世界上。