基于ADO数据构形的VB动态分层报表

利用ADO数据构形技术可以对多表进行联合查询，生成具有清晰层次结构的分层记录集，为多种可视化控件和分层报表提供数据源。概述了数据构形技术的主要功能，通过简单的示例介绍了如何构建SHAPE命令生成动态分层记录集．讨论了采用多种方法生成动态分层报表的关键技术。     

基于ADO数据构形的VB动态分层报表

利用ADO数据构形技术可以对多表进行联合查询,生成具有清晰层次结构的分层记录集,为多种可视化控件和分层报表提供数据源。概述了数据构形技术的主要功能,通过简单的示例介绍了如何构建SHAPE命令并生成动态分层记录集,讨论了采用多种方法生成动态分层报表的关键技术。     

The Galerkin element method applied to the vibration of rectangular damped sandwich plates

The Galerkin element method (GEM), which combines Galerkin orthogonal functions with the traditional finite element formulation, has previously been applied successfully to the vibration analysis of damped sandwich beams, and an improved iteration method was developed for its eigen solution. In the current paper, this promising method is extended to the vibration of damped sandwich plates. A quite different model is formulated which has both nodal coordinates and edge coordinates, while in the case of beams, there are only nodal coordinates. Displacement compatibility over the interfaces between the damping layer and the elastic layers is taken account of in order to ensure a conforming element and thereby guarantee good accuracy. The seed matrix method is proposed for simplifying the building of the element mass, stiffness and damping matrices. Numerical examples show that the application of the GEM to sandwich plate structures is computationally very efficient, while providing accurate estimates of natural frequencies and modal damping over a wide frequency range.     

Designing feedforward command shapers with multi-objective genetic optimisation for vibration control of a single-link flexible manipulator

This paper presents investigations into the design of a command-shaping technique using multi-objective genetic optimisation process for vibration control of a single-link flexible manipulator. Conventional design of a command shaper requires a priori knowledge of natural frequencies and associated damping ratios of the system, which may not be available for complex flexible systems. Moreover, command shaping in principle causes delay in system's response while it reduces system vibration and in this manner the amount of vibration reduction and the rise time conflict one another. Furthermore, system performance objectives, such as, reduced overshoot, rise time, settling time, and end-point vibration are found in conflict with one another due to the construction and mode of operation of a flexible manipulator. Conventional methods can hardly provide a solution, for a designer-oriented formulation, satisfying several objectives and associated goals as demanded by a practical application due to the competing nature of those objectives. In such cases, multi-objective optimisation can provide a wide range of solutions, which trade-off these conflicting objectives so as to satisfy associated goals. A multi-modal command shaper consists of impulses of different amplitudes at different time locations, which are convolved with one another and then with the desired reference and then used as reference (for closed loop) or applied to system (for open loop) with the view to reduce vibration of the system, mainly at dominant modes. Multi-objective optimisation technique is used to determine a set of solutions for the amplitudes and corresponding time locations of impulses of a multi-modal command shaper. The effectiveness of the proposed technique is assessed both in the time domain and the frequency domain. Moreover, a comparative assessment of the performance of the technique with the system response with unshaped bang–bang input is presented.     

振动信号的特征参数在柴油机故障诊断中的应用

本文用试验的方法,测取柴油机在几个常见故障及不同故障程度下的振动信号,分析并得出了对各故障变化最敏感的振动信号参数,即特征参数,为柴油机的故障诊断提供了很多有用的信息。     

搜索路网空间中时空相似轨迹

为了分析移动对象行为特征,需要一种度量轨迹间相似性的方法,虽然在欧氏空间检索移动对象相似轨迹的研究较多,但在路网空间这种研究还不多见。在实际应用方面,大多数移动对象位于路网空间而不是欧氏空间。本文研究了路网空间相似轨迹的特性,并提出了一种在路网空间搜索相似轨迹的度量方法。实验结果表明该方法不仅是搜索相似轨迹的实用技术,也是一种较好的轨迹聚类方法     

Discrete time-optimal command shaping

Finite impulse-response “input shapers” may be used to prefilter inputs to eliminate or minimize residual vibration when maneuvering flexible structures. Vibration is reduced at the expense of adding a delay equal to the length of the shaper. This paper first presents results that aid in the design of “single-input shapers” in the discrete domain. Next, MIMO shaping is considered. Given certain a priori information about the inputs, shorter shapers (which introduce less delay) can be derived. A time-optimal scheme is developed here, and existence of solutions is proved for both SISO and MIMO cases. The method is direct, general, easy to implement, and allows for the addition of derivative constraints to improve robustness. Finally, traditional optimal control and input shaping are compared, and it is shown that under certain conditions optimal discrete-time input shaping and discrete time-optimal control are equivalent.     

基于改进SOM神经网络的数控机床振动故障自动检测系统设计

数控机床是制造业中的关键设备,其稳定运行对于提高生产效率至关重要。由于数控机床信号在传输线上传播时,会产生线路的阻抗不匹配现象,导致信号的衰减问题,降低信号强度,难以准确检测出振动信号。故设计一种基于改进SOM神经网络的数控机床振动故障自动检测系统。采用RS6103型号振动传感器实时采集数控机床的振动信号,改进振动信号调理电路,将传感器输出的衰减电流信号转换为稳定的电压信号,去除噪声干扰,提高振动信号的准确性,并将EP4CE10型号FPGA芯片作为核心控制器,完成硬件部分的设计。软件部分采用免疫遗传算法对SOM神经网络进行改进,优化连接权重寻优过程,提高神经网络的训练速度和振动故障检测精度。从采集的振动信号中提取特征向量,包括均值、峰峰值、峰值因子等,将提取的特征向量输入改进后的SOM神经网络中,通过竞争学习原理实现振动故障检测。实验结果显示:设计系统应用后振动信号调理结果信噪比更高,整体质量更好,提取的振动信号偏度特征与实际特征趋于一致,振动故障检测效果较好。     

Command-induced vibration analysis using input shaping principles

Input shaping is a well-established technique used for reducing the vibratory response of dynamic systems. Analytical tools are available for systems utilizing input shaping. These tools aid in performance analysis by providing intuitive and computationally simple methods for determining key system attributes, such as the residual vibration in response to a command. This paper describes methods whereby arbitrary reference commands may be interpreted as input-shaped commands. This capability allows input shaping analysis tools to be used on systems without input shapers. Experimental results obtained from an industrial 10-ton bridge crane validate the theoretical developments.     

Acoustic signal separation of mechanical devices using ICA with band-pass filters

We propose a method of separating the acoustic signals of motors and the gears of mechanical devices by using independent component analysis (ICA) with band-pass filters. The frequency distribution of a recorded acoustic signal from the operating mechanical device can be divided into three fields, the low-frequency field, which corresponds to the frequency characteristics of the gear, the medium-frequency field, which is mixed with the frequency characteristics of the gear and the motor, and the high-frequency field, which corresponds to the frequency characteristics of the motor. Since only the medium-frequency components are a mixture of the acoustic signals of gears and motors, ICA with band-pass filters is expected to separate the acoustic signals of motors and gears more accurately than conventional ICA. The simulation and experimental results show that the proposed method can separate the acoustic signals of motors and gears of mechanical devices successfully.This work was presented, in part, at the 9th International Symposium on Artificial Life and Robotics, Oita, Japan, January 28–30, 2004     

遥测振动测量数据的处理方法研究

文中总结并分析了遥测数据中振动信号的处理方法。振动信号在遥测数据中属于速变参数,按照周期成分划分可以将振动信号分为随机振动信号和周期振动信号,针对两种形式上的振动信号,处理方法也略有不同,研究两种形式振动信号的处理方法对振动信号的处理具有实际指导意义。     

An adaptive coherence filter

This paper derives an adaptive coherence filter for canceling interference from a signal of interest whose power spectral density is symmetric. A basic property of the Fourier transform of real signals is that their spectra are Hermitian symmetric. This property is exploited to determine which part of a spectrum is interference and which part is the signal of interest. An unconstrained Wiener filter is derived that exploits the frequency domain symmetry of the signal of interest. While the adaptive coherence filter is based on the Fourier transform property of real signals, an extension of the algorithm is provided so the filter can be used on any signal that displays spectral symmetry. A practical method for implementing the filter is provided. The filter has application in the area of telecommunications, but is applicable in wireless communication applications where a signal, that displays spectral symmetry, is corrupted by interfering signals within the signal of interest's bandwidth.     

一种高端数据产品命令行接口的设计

命令行接口是高端数据产品，如路由器中一个十分重要的功能模块，通过它，后台可发送命令来对前台的资源进行查询、设置其工作模式、进行系统控制等。文章描述了命令行接口的工作原理、总体设计、关键模块的流程图及重要数据结构，并介绍了命令行接口设计中一些关键算法的实现。     

Precompensated Second Order Repetitive Control of an Active Filter Under Varying Network Frequency

Network frequency variations cause a dramatic performance decay in repetitive controller‐based shunt active power filters. This problem may be solved by adapting the sampling period in order to keep the ratio between the network period and the sampling period at a constant value. However, these changes may yield closed‐loop instability. The introduction of a precompensator that forces the plant to remain invariant despite sampling rate changes allows the use of standard LTI methods in control design and stability analysis as well. Moreover, in order to improve robustness in the face of network frequency estimation uncertainty and sampling time quantization, the regular repetitive controller is replaced by a high order one. Experimental results show the validity of the proposal.