一种航空发动机传感器故障诊断方法

为了对航空发动机传感器故障作出准确快速的诊断,在Simulink中设计了基于卡尔曼滤波器的残差检验的故障诊断模块,实现发动机传感器恒偏差、恒增益、卡死故障等硬故障的诊断。针对传统卡尔曼滤波器残差检验法检测缓变故障时存在较大延时的缺点,采用改进卡尔曼滤波器的残差检验法来检测故障,并与传统卡尔曼滤波器法进行比较。仿真结果表明,传统卡尔曼滤波器的残差检验法能有效地诊断航空发动机传感器的几种典型硬故障,但对于缓变故障却不敏感。改进卡尔曼滤波器的残差检验法能在一定程度上加快检测速度,取得较好的效果。     

基于专用卡尔曼滤波器思想的陀螺故障诊断

本文针对卫星姿态确定系统,提出了一种基于专用卡尔曼滤波器思想的陀螺故障诊断方法.利用卫星姿态运动方程设计了一种加性卡尔曼滤波器,用于生成作为故障征兆信号的残差.结合专用观测器思想和卡尔曼滤波器,提出了利用卡尔曼滤波器组的故障检测与分离律.另外,给出了一种基于3-σ的阈值计算方法,用于设计故障诊断中所用的检测阈值.仿真结果验证了所提出方法的有效性.     

基于一组卡尔曼滤波器信息融合的故障诊断

为了能及时准确地诊断发动机的传感器和执行机构故障,文章提出了基于一组卡尔曼滤波器信息融合的方法进行故障诊断;首先根据传感器特性设计了一组滤波器用于传感器故障诊断、隔离,每个滤波器针对一个传感器进行设计;其次根据执行机构故障特性设计了一组卡尔曼滤波器进行执行机构偏差估计,从而对执行机构进行故障诊断、隔离;接着给出了传感器、执行机构信息融合的诊断方案;最后分别给传感器、执行机构添加故障进行方案验证,仿真结果得出在传感器或者执行机构任意部件出故障的情况下,该融合方法可以有效地诊断并隔离出有故障的传感器或者执行机构。     

复数型扩展卡尔曼滤波算法在感应电机直接转矩控制系统中的应用

针对传统算法中存在的数字信号处理器(DSP)运算速度要求高因而容易产生较大的延迟的问题.提出一种复数型扩展卡尔曼滤波观测器(ECKF)对感应电机进行状态估计,将得到的定子磁链和电机转速应用于直接转矩控制系统中,实现感应电机的无速度传感器控制.采用感应电机复数模型进行滤波器设计可以简化感应电机状态方程的维数并有效减少滤波算法计算量.由于复数型扩展卡尔曼滤波器在实现过程中没有矩阵求逆的运算,并且与常规扩展卡尔曼滤波器相比具有更低的维数,因此DSP的运算时间得到了有效的降低,提高了滤波器状态估计的快速性.仿真和实验结果验证了所提出的复数型扩展卡尔曼滤波器有效性和可行性.     

双余度传感器缓变故障检测的改进残差检验法

分析了基于卡尔曼滤波器的残差检验法对传感器缓变故障检测的不敏感性原因.针对双余度传感器缓变故障检测,采取了先故障判断后故障定位的故障检测策略,并提出了一种基于移动伪正常状态的残差构造方法.数学仿真验证了改进方法比传统方法更能够及时准确地识别双余度传感器缓变故障.     

非线性系统传感器偏差故障的UKF递推检测方法

针对传统的推广卡尔曼滤波器方法(EKF)的不足,为检测非线性系统传感器的偏差型故障,提出了一种新的基于unscented卡尔曼滤波(UKF)的实时递推检测算法,该方法应用UKF作为传感器故障残差发生器,并利用残差加权平方和检测策略进行故障的检测.仿真结果表明,与基于EKF的传感器故障检测方法相比,该方法有更好的故障预示能力,并提高了故障检测的准确率.     

改进粒子群算法优化扩展卡尔曼滤波器电机转速估计

针对感应电机扩展卡尔曼滤波器转速估计中难以取得卡尔曼滤波器系统噪声矩阵和测量噪声矩阵最优值的问题, 提出了一种基于改进粒子群算法优化的扩展卡尔曼滤波器转速估计方法。算法通过融合遗传算法和粒子群算法的优点, 采用可调整的算法模型对粒子群算法进行改进, 将改进的粒子群算法对扩展卡尔曼滤波器中的系统噪声矩阵和测量噪声矩阵进行优化处理, 将优化后的卡尔曼滤波器应用于感应电机转速估计。仿真实验表明, 与试探法、标准粒子群算法及遗传算法比较, 改进粒子群算法优化的扩展卡尔曼滤波器能够有效提高转速估计的精度, 从而提高无速度传感器矢量控制系统的控制性能。     

基于模型的曲轴位置传感器故障诊断研究

为了对汽车发动机转速传感器作出快速准确的诊断,结合曲轴信号处理原理,在MATLAB/simulink中设计基于卡尔曼滤波器残差检验的OBD诊断模块,实现了曲轴位置传感器无信号、信号错误等故障诊断功能。针对卡尔曼滤波器法无法排除掉非故障性信号输入的缺点,在卡尔曼滤波法基础上加入逻辑诊断,通过条件判断以启动诊断,加入决策逻辑以确定故障状态。验证结果表明,卡尔曼滤波器法能够准确快速识别两种传感器故障,但在非故障性信号时无法准确判断故障。加入诊断逻辑的改进卡尔曼滤波法能够准确排除非故障性输入,保证诊断的准确性。     

基于分层多模自适应滤波算法的无人机多重传感器故障诊断

应用标准的多模自适应滤波算法能够在较短的时间内检测出系统的单一故障,但是当把它用于检测系统的双重或多重故障时,这一算法需要建立所有可能出现的故障模型,而每一个模型都要对应一个卡尔曼滤波器,需要大量的滤波器并行运算,大大增加了系统的故障诊断时间,为了简化算法并减少算法计算时间,本文提出了一种用于复杂系统的多重故障诊断的分层多重模型滤波技术,在确定某一单个故障发生后,则可以启用一组基于上一单个故障的新滤波器来检测系统的第二重故障,这样减少了并行运算的滤波器数量,从而减少计算量和故障诊断时间.本文将此算法应用于某无人机多重传感器的故障诊断,仿真结果验证了该方法的有效性.     

基于碰撞检测的护理型操作臂的安全性设计与实现

针对与人近距离交互的护理型操作臂的安全性问题,提出并实现了一种基于碰撞检测的安全性设计方法,它根据由动力学模型计算获得的参考输出力矩与力矩传感器测得的实际输出力矩间的偏差实现碰撞检测.在关节力矩传感器设计中,采用有限元分析方法来优化应变片的位置布置,并开发了高抗干扰能力的信号处理电路.根据护理型操作臂的低速特点,提出了...     

Only connect: teaching, technology and telesis

Abstract This paper describes an approach to the design of interactive multimedia materials being developed in a European Community project. The developmental process is seen as a dialogue between technologists and teachers. This dialogue is often problematic because of the differences in training, experience and culture between them. Conditions needed for fruitful dialogue are described and the generic model for learning design used in the project is explained.     

European Community policy and the market

Abstract This paper starts with some reflections on the policy considerations and priorities which are shaping European Commission (EC) research programmes. Then it attempts to position the current projects which seek to capitalise on information and communications technologies for learning in relation to these priorities and the apparent realities of the marketplace. It concludes that while there are grounds to be optimistic about the contribution EC programmes can make to the efficiency and standard of education and training, they are still too technology driven.     

一种自适应子融合集成多分类器方法

融合集成方法已经广泛应用在模式识别领域,然而一些基分类器实时性能稳定性较差,导致多分类器融合性能差,针对上述问题本文提出了一种新的基于多分类器的子融合集成分类器系统。该方法考虑在度量层融合层次之上通过对各类基多分类器进行动态选择,票数最多的类别作为融合系统中对特征向量识别的类别,构成一种新的自适应子融合集成分类器方法。实验表明,该方法比传统的分类器以及分类融合方法识别准确率明显更高,具有更好的鲁棒性。     

Avoiding semantic and temporal gaps in developing software intensive systems

Development of software intensive systems (systems) in practice involves a series of self-contained phases for the lifecycle of a system. Semantic and temporal gaps, which occur among phases and among developer disciplines within and across phases, hinder the ongoing development of a system because of the interdependencies among phases and among disciplines. Such gaps are magnified among systems that are developed at different times by different development teams, which may limit reuse of artifacts of systems development and interoperability among the systems. This article discusses such gaps and a systems development process for avoiding them.     

Designing economic np control charts: A programmed simulation approach

This paper presents control charts models and the necessary simulation software for the location of economic values of the control parameters. The simulation program is written in FORTRAN, requires only 10K of main storage, and can run on most mini and micro computers. Two models are presented - one describes the process when it is operating at full capacity and the other when the process is operating under capacity. The models allow the product quality to deteriorate to a further level before an existing out-of-control state is detected, and they can also be used in situations where no prior knowledge exists of the out-of-control causes and the resulting proportion defectives.     

The development of robot art

Going through a few examples of robot artists who are recognized worldwide, we try to analyze the deepest meaning of what is called “robot art” and the related art field definition. We also try to highlight its well-marked borders, such as kinetic sculptures, kinetic art, cyber art, and cyberpunk. A brief excursion into the importance of the context, the message, and its semiotics is also provided, case by case, together with a few hints on the history of this discipline in the light of an artistic perspective. Therefore, the aim of this article is to try to summarize the main characteristics that might classify robot art as a unique and innovative discipline, and to track down some of the principles by which a robotic artifact can or cannot be considered an art piece in terms of social, cultural, and strictly artistic interest. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

Explanation and prediction: an architecture for default and abductive reasoning

Although there are many arguments that logic is an appropriate tool for artificial intelligence, there has been a perceived problem with the monotonicity of classical logic. This paper elaborates on the idea that reasoning should be viewed as theory formation where logic tells us the consequences of our assumptions. The two activities of predicting what is expected to be true and explaining observations are considered in a simple theory formation framework. Properties of each activity are discussed, along with a number of proposals as to what should be predicted or accepted as reasonable explanations. An architecture is proposed to combine explanation and prediction into one coherent framework. Algorithms used to implement the system as well as examples from a running implementation are given.     

Three Process Perspectives: Organizations, Teams, and People

This paper provides the author's personal views and perspectives on software process improvement. Starting with his first work on technology assessment in IBM over 20 years ago, Watts Humphrey describes the process improvement work he has been directly involved in. This includes the development of the early process assessment methods, the original design of the CMM, and the introduction of the Personal Software Process (PSP)^SM and Team Software Process (TSP){^SM}. In addition to describing the original motivation for this work, the author also reviews many of the problems he and his associates encountered and why they solved them the way they did. He also comments on the outstanding issues and likely directions for future work. Finally, this work has built on the experiences and contributions of many people. Mr. Humphrey only describes work that he was personally involved in and he names many of the key contributors. However, so many people have been involved in this work that a full list of the important participants would be impractical.     

基于复小波噪声方差显著修正的SAR图像去噪

提出了一种基于复小波域统计建模与噪声方差估计显著性修正相结合的合成孔径雷达(Synthetic Aperture Radar,SAR)图像斑点噪声滤波方法。该方法首先通过对数变换将乘性噪声模型转化为加性噪声模型,然后对变换后的图像进行双树复小波变换(Dualtree Complex Wavelet Transform,DCWT),并对复数小波系数的统计分布进行建模。在此先验分布的基础上,通过运用贝叶斯估计方法从含噪系数中恢复原始系数,达到滤除噪声的目的。实验结果表明该方法在去除噪声的同时保留了图像的细节信息,取得了很好的降噪效果。     

How do children do mathematics with LOGO?

Abstract  This paper considers some results of a study designed to investigate the kinds of mathematical activity undertaken by children (aged between 8 and 11) as they learned to program in LOGO. A model of learning modes is proposed, which attempts to describe the ways in which children used and acquired understanding of the programming/mathematical concepts involved. The remainder of the paper is concerned with discussing the validity and limitations of the model, and its implications for further research and curriculum development.