SVD-based Preisach hysteresis identification and composite control of piezo actuators

In this paper, the singular value decomposition (SVD) based identification and compensation of the hysteretic phenomenon in piezo actuators are addressed using a Preisach model. First, this paper presents an SVD-based least squares algorithm and a revision approach of the identification through updating the SVD. With the identified parameters and a log of the memory curve, a Preisach-based inversion compensator is constructed which is complemented with a feedback controller to address the inevitable and residual modeling errors. Experimental results are furnished for both the identification and compensation approaches. The Preisach-based feedforward controller significantly improves the tracking performance and reduces the root-mean-square (RMS) tracking error of a PID controller by 76.7% and 89% at 1 Hz and 25 Hz, respectively. With the proposed composite controller, the percent-RMS errors at 1 Hz and 25 Hz are reduced to 0.035% and 0.31%, respectively.     

All-hexahedral mesh generation via inside-out advancing front based on harmonic fields

The generation of hexahedral meshes is an open problem that has undergone significant research. This paper deals with a novel inside-out advancing front method to generate unstructured all-hexahedral meshes for given volumes. Two orthogonal harmonic fields, principal and radial harmonic fields, are generated to guide the inside-out advancing front process based on a few user interactions. Starting from an initial hexahedral mesh inside the given volume, we advance the boundary quadrilateral mesh along the streamlines of radial field and construct layers of hexahedral elements. To ensure high quality and uniform size of the hexahedral mesh, quadrilateral elements are decomposed in such a way that no non-hexahedral element is produced. For complex volume with branch structures, we segment the complex volume into simple sub-volumes that are suitable for our method. Experimental results show that our method generates high quality all-hexahedral meshes for the given volumes.     

四川餐饮业信息化人才状况调查与分析

四川餐饮业发展迅猛,为了解餐饮企业信息化发展情况,尤其是餐饮业信息化人才状况,课题组对四川餐饮企业进行了信息化抽样调查。调查涵盖餐饮企业信息化实施总体情况,包括信息化水平、运用效果以及餐饮企业对信息化的认识,调查侧重于餐饮企业现有信息化人才结构状况和需求期待,并对调查数据进行了科学和客观分析,旨在为信息化人才标准和培养模式探索提供依据、奠定基础。     

Thermodynamic considerations of " solid state engines" based on thermoelastic martensitic transformations and the shape memory effect

Engine applications of the shape memory ("Marmem" ) effect associated with thermoelastic transformations are discussed. Such devices potentially enable the direct conversion of heat(i.e., solar energy or waste heat) into mechanical work. It is shown that efficiencies on the order of 20 pct may be expected and can be improved with alloys having certain transformation hysteresis loop characteristics. Formerly with the University of Illinois     

基于小波分析方法的装备价格指数变化研究

针对传统时间序列方法对物价指数的非平稳现象适应性较差的问题,提出运用小波分析方法,将原始数据分解成不同频率段的平稳信号,进而采用传统方法进行处理,从而提高了预测精度,获得令人满意的效果。     

血红素中卟啉Fe（Ⅱ）的简正模式分析

将血红素中卟啉Ｆｅ（Ⅱ）环作成一个Ｃ４ν群，并导出了其简正坐标与简正振动模式．     

A parametrization of all the unfalsified plant models for MIMOsystems

The results of the parametrization of all the unfalsified models for single-input/single-output systems are extended to multi-input/multi-output (MIMO) systems. In this parametrization, the assumed a priori plant and noise information are upper bounds of the H _∞-norm of the plant matrix-valued transfer function and the noise magnitude. The parametrization is on the basis of several series of plant time-domain identification experiment data. It is shown that for MIMO systems, all the unfalsified plant matrix-valued transfer functions can still be expressed by the linear fractional transformation of a fixed matrix-valued transfer function and an H_∞-norm bounded structure fixed, but uncertain matrix-valued transfer function. However, the high dimensions of the matrix-valued transfer functions involved in the parametrization hamper the direct application of these results to robust controller design. To overcome these difficulties, further efforts are needed     

周铣加工表面形貌仿真新算法

考虑主轴偏心，基于周铣过程中刀具切削刃上任意点与工件相对运动的轨迹方程和周铣过程几何特征，构造出可以求解周铣加工表面上任意一点形貌高度值的三维表面形貌仿真算法，并给出了相应的仿真算例。该算法无需对刀齿进行微段离散，并且不依赖于工件网格划分，加工表面上任意一点形貌高度值的计算次数等于刀具齿数，具有通用性好、运算速度快、结果准确度高的特点。     

汽油在线优化调合系统实践

为了保证汽油调合辛烷值的准确性,在减少辛烷值浪费的同时应避免因辛烷值低于标准值而造成质量事故。参考国内外汽油在线优化调合的各种技术方案,设计了一种适合中国国情的汽油在线优化调合控制系统。经中石化天津和洛阳炼油厂应用证明,系统很好地解决了调合过程中的辛烷值控制及优化问题,取得了较好的经济效益。     

太阳能热水器自动温度控制器设计

介绍了太阳能热水器的自动控制器的功能和组成，阐述了控制系统的工作原理，硬件和软件设计及相关技术问题，实际应用表明该系统可靠性高、操作简单，具有良好的经济和社会效益。