基于多层前向神经网络的模拟电路故障诊断

文中提出把一个神经网络应用到电路故障诊断的故障字典法中,以提高故障诊断的适应能力。这样,就使得字典法不仅适用于电路的故障情况,还提高了故障诊断的有效性。模拟结果显示这种方法是有效的。     

机械手的神经网络自适应滑动模控制器设计

 针对多关节机械手的鲁棒跟随控制器设计问题，提出了一种新的机械手神经网络自适应滑动模控制器设计方法，机械手的动力学非线性假设是完全未知的。在提出的控制结构中，高斯径向基函数神经网络用于在线补偿机械手的动力学非线性，参数学习律由稳定性理论得到。给出了系统稳定性和参数收敛性的证明。最后提出方法的可行性通过仿真得到验证。     

Forecasting of DST variations from polar cap indices using neural networks

The 15-min averaged polar cap (PC) index was used as an input parameter for the Dst variation forecasting. The PC index is known to describe well the principal features of the solar wind as well as the total energy input to the magnetosphere. This allowed us to design a neural network able to forecast the Dst variations from 1 to 4 h ahead. 1998 PC and Dst data sets were used for training and testing and 1997 data sets was used for validation proposes. From the 15 moderate and strong geomagnetic storms observed during 1997, nine were successfully forecasted. In three cases the observed minimum Dst value was less than the predicted one, and only in three cases the neural network was not able to reproduce the features of the geomagnetic storm.     

异质网上互操作—从数据交换到程序交换

对分布式计算和软件集成中的互操作性问题进行了讨论，叙述了遵循特定的标准解决互操作性的办法，比较几种常见的互操作标准，包括ＳＴＥＰ／ＳＤＡＩ，ＣＯＲＢＡ和Ｊａｖａ，描述了Ｊａｖａ语言出现后程序交换的新特点，并对互操作标准的现状作了评述。     

模拟电路故障诊断技术研究

介绍了模拟电路故障诊断的现状及特点,对基于网络撕裂法的故障诊断方法进行了研究,探讨了基于BP神经网络的故障诊断方法及其在模拟电路上的应用,并指出了故障诊断技术的发展趋势。     

基于旋转矩阵的预设时间航天器编队姿态协同控制

由多个航天器组成的编队系统对复杂的环境往往具有较高的适应性和容错性,能更高效率地完成单航天器难以完成的任务。因此主要针对多航天器系统的姿态协同控制问题,提出一种基于旋转矩阵的预设时间控制算法。首先,为了避免航天器姿态建模的奇异性和模糊性问题,采用旋转矩阵对航天器的姿态进行统一描述,同时结合有向的通信拓扑对航天器姿态协同控制系统进行建模。其次,为赋予系统可控的收敛速度,提出一种基于滑模的预设时间控制算法。该算法的引入使得航天器编队系统的收敛时间可以在合理的范围内任意给定。此外,为了实现系统对参数摄动和外部干扰的鲁棒性,采用神经网络和自适应算法对不确定性进行在线估计与补偿。最后,通过理论分析和数值仿真验证了所提预设时间控制算法的有效性。     

Regression model for civil aero-engine gas path parameter deviation based on deep domain-adaptation with Res-BP neural network

The variations in gas path parameter deviations can fully reflect the healthy state of aero-engine gas path components and units; therefore, airlines usually take them as key parameters for monitoring the aero-engine gas path performance state and conducting fault diagnosis. In the past, the airlines could not obtain deviations autonomously. At present, a data-driven method based on an aero-engine dataset with a large sample size can be utilized to obtain the deviations. However, it is still difficult to utilize aero-engine datasets with small sample sizes to establish regression models for deviations based on deep neural networks. To obtain monitoring autonomy of each aero-engine model, it is crucial to transfer and reuse the relevant knowledge of deviation modelling learned from different aero-engine models. This paper adopts the Residual-Back Propagation Neural Network (Res-BPNN) to deeply extract high-level features and stacks multi-layer Multi-Kernel Maximum Mean Discrepancy (MK-MMD) adaptation layers to map the extracted high-level features to the Reproduce Kernel Hilbert Space (RKHS) for discrepancy measurement. To further reduce the distribution discrepancy of each aero-engine model, the method of maximizing domain-confusion loss based on an adversarial mechanism is introduced to make the features learned from different domains as close as possible, and then the learned features can be confused. Through the above methods, domain-invariant features can be extracted, and the optimal adaptation effect can be achieved. Finally, the effectiveness of the proposed method is verified by using cruise data from different civil aero-engine models and compared with other transfer learning algorithms.     

用BP神经网络预报太阳活动第23周的黑子数

本文设计、训练和利用BP神经网络,对1750年以来的各太阳活动周上升段和下降段太阳黑子数的变化数据进行了分类和模式识别,得到各太阳活动周上升周期及其上升期间太阳黑子数平滑月均值相当好的模拟结果;在此基础上获得较好的太阳活动第22周上升周期及太阳黑子数的最大平滑月均值预报结果;还作出太阳活动第23周的上升周期及太阳黑子数的最大平滑月均值的预报结果.      

故障诊断的神经网络多重模型自适应方法

将神经网络与故障诊断的多重模型自适应方法相结合,提出了故障诊断的神经网络多重模型自适应方法,并对某型航空发动机控制系统传感器故障进行诊断仿真。仿真表明,该方法能够用来解决具有模型不确定性系统的故障诊断问题,同时,对未知的故障模态具有自学习能力     

基于递推平方根法的神经网络模型辨识

提出一种基于递推平方根法的神经网络模型辨识方法,对Davidon最小二乘法和阻尼最小二乘法进行了改进,既保持了二者简单易行、收敛性的优点,又能提高精度,减少计算量,适合于应用在非线性系统的辨识和自适应控制中。与常规的Davidon最小二乘法和阻尼最小二乘法进行仿真比较,体现出了这种方法的有效性,尤其是在输入及隐含节点个数较多的情况,其优点比较明显。