调节对象参数和运动特性随工况变化的分析

水轮机调节对象的许多参数都是随运行工况变化的。以调节对象线性化模型为基础，从1个实例计算人手，计算了不同工况下水轮机传递系数和发电机6个参数的变化情况，进而计算这些参数变化对捌节对象特征根的影响。通过汁算表明，其水力振荡衰减速度与出力有关．而系统的其他运动特性随工况变化较小。     

非饱和土壤水分运动数值模拟研究综述

土壤水是地表水和地下水联系的纽带，在水循环过程中起着重要作用，它和农业、水文、环境等领域有着密切关系。本文从土壤水分运动机理出发，评述了国内外水力参数取值方法和数值模拟的研究动态，对非饱和土壤水分运动数值模拟传统的有限元和有限差分研究方法进行了综合分析，并讨论了两种改进的数值计算方法——有限元质量集中法和有限体积法。本文认为非饱和土壤水分运动的数值模拟虽然取得了一些进展，但对土壤水分运动较为复杂的情况仍然手段有限，该领域的研究工作有待继续深化。     

施工系统中混凝土拌和工厂位置选择综合评价模型

在大型水利水电工程施工系统中，混凝土拌和工厂位置选择涉及大量不确定性因素，本文用可能性－满意度来描述决策者对不确定性估计的主观性和管观性，论述了可能性与模糊集，满意度与信任度的对应关系，给出了可靠性－满意度的计算方法。以系统分析的层次性原理为基础，建立了厂址选择的综合评价模型，通过一个实例分析，得到几点结论。     

基于NURBS的PDE曲面构造法研究及应用

由非均匀有理Ｂ样条曲线曲面给定边界条件，用偏微分方程来构造曲面，以参数“ａ”控制其整体形状，本文分析其思路原理及过程，并列举了在ＣＡＤ上的应用，最后分析了优缺点。     

34CrMoV结构钢动态再结晶行为研究

应用Gleeble-1500热模拟实验机进行等温压缩试验,研究了变形工艺参数对34CrMoV结构钢动态再结晶行为的影响.结果表明,其流变应力随变形温度升高而降低,随应变速率提高而增大;随着应变速率的降低,应变量的增加和变形温度的升高,动态再结晶速度加快且奥氏体晶粒得到细化.     

Service Reliability Assessment of Weld Repaired CrMoV Steel Rotors

This research deals with the service evaluation of a retired CrMoV steel rotor that has been repaired using deep groove multi‐pass submerged arc welding (SAW) and gas tungsten arc welding (GTAW). Accelerated creep tests were conducted at several elevated temperatures and extrapolated to the service temperatures. The coalescence of carbides and cavity growth during creep were evaluated. For the CrMoV‐GTAW samples, it was found that the creep life depended on the location of the crossweld in the welded specimen. The service lives of the weldments were extrapolated.     

Robust control of polytopic systems by convex optimization

Robust control synthesis of linear time-invariant SISO polytopic systems is investigated using the polynomial approach. A convex set of all stabilizing controllers for a polytopic system is given over an infinite-dimensional space. A finite-dimensional approximation of this set is obtained using the orthonormal basis functions and represented by a set of LMIs thanks to the KYP lemma. Then, an LMI based convex optimization problem for robust pole placement with sensitivity function shaping in two- and infinity-norm is proposed. The simulation results show the effectiveness of the proposed method.     

基于模糊匹配的平面连杆机构反求设计研究

对平面连杆机构曲线进行了分析,提出了用一组特征参数来描述连杆曲线,建立了连杆曲线图谱库,并将模糊论应用于连杆机构的曲线匹配,从而获取所求的机构参数.最后给出了应用实例,证实了该方法的可行性与有效性.     

Nonlinear black-box modeling in system identification: a unified overview

A nonlinear black-box structure for a dynamical system is a model structure that is prepared to describe virtually any nonlinear dynamics. There has been considerable recent interest in this area, with structures based on neural networks, radial basis networks, wavelet networks and hinging hyperplanes, as well as wavelet-transform-based methods and models based on fuzzy sets and fuzzy rules. This paper describes all these approaches in a common framework, from a user's perspective. It focuses on what are the common features in the different approaches, the choices that have to be made and what considerations are relevant for a successful system-identification application of these techniques. It is pointed out that the nonlinear structures can be seen as a concatenation of a mapping form observed data to a regression vector and a nonlinear mapping from the regressor space to the output space. These mappings are discussed separately. The latter mapping is usually formed as a basis function expansion. The basis functions are typically formed from one simple scalar function, which is modified in terms of scale and location. The expansion from the scalar argument to the regressor space is achieved by a radial- or a ridge-type approach. Basic techniques for estimating the parameters in the structures are criterion minimization, as well as two-step procedures, where first the relevant basis functions are determined, using data, and then a linear least-squares step to determine the coordinates of the function approximation. A particular problem is to deal with the large number of potentially necessary parameters. This is handled by making the number of ‘used’ parameters considerably less than the number of ‘offered’ parameters, by regularization, shrinking, pruning or regressor selection.     

圆柱形螺旋弹簧的简捷计算

将圆柱形螺旋弹簧设计中的部分常用公式组合成一组仅与弹簧指数Ｃ有关的公式，并将Ｃ＝４～１４代入计算而获得一套参数表，由此，可提高圆柱形螺旋弹簧的设计效率。