基于视情维修的电子装备PHM体系结构分析

为推行自主式保障理念,提高电子装备的综合保障能力,提出了一种基于视情维修的电子装备预测与健康管理(Prognostics and Health Management,PHM)构建方案。在分析PHM内涵和功能的基础上,从数据信息维、模型维和生命周期维3个维度研究了PHM系统结构,采用开放式PHM架构方式,建立了基于视情维修的电子装备PHM体系结构,并对其系统实现技术进行了探讨。通过对某型装备模拟训练与仿真测试系统PHM策略的设计,验证了所提方案的有效性。     

PHM仿真试验系统设计与应用

PHM系统是保障机载设备稳定安全运行的重要工具。通过构建PHM仿真试验系统,可以对系统架构、总线接口、数据处理、分区存储等系统功能进行仿真验证,以便尽早发现PHM系统设计初期存在的各种问题,及时对方案进行改进和优化,降低系统研制的风险。对PHM仿真试验系统的设计进行了研究,提出了一种PHM仿真试验系统设计与应用方法,从总体层次、软硬件设计等方面介绍仿真试验系统的组成和功能设计。搭建飞机级及各区域级的仿真设备,构建基于总线通讯的交联仿真网,支持数据、模型、流程等功能的仿真,并在最后给出了仿真试验的主要流程。实际应用表明,本方法能够较好地支撑仿真验证试验,从而缩短试验周期,提高研制效率,为系统设计工作提供支撑从PHM系统功能验证的角度为PHM系统研制提供支撑。     

基于知识图谱的航空发动机PHM仿真验证平台设计

针对航空发动机PHM系统功能、性能验证要求高、验证内容多、验证业务复杂等实际问题,分析了国外先进航空发动机PHM系统开发验证情况及经验,提出了一种基于知识图谱技术的PHM仿真验证平台设计方法。该方法利用了知识图谱在具有的半结构化、高效性、直观等特点,实现了发动机PHM验证涉及到的故障模式、故障特征、算法模型及专家知识等大量信息知识的有效组织与管理。在此基础上,进一步面向发动机PHM验证数据量大、计算需求高等需求,采用大数据、数据挖掘、机器学习、云服务等技术,搭建了基于知识图谱的航空发动机PHM仿真验证平台,实现了数据挖掘与信息提取、专家知识获取、多层级融合诊断智能导向型推理等应用。最后,以某型发动机为对象,介绍了发动机PHM仿真验证情况。经实际验证结果分析,该文提出的PHM仿真验证平台能够有效解决航空发动机PHM系统可验证的历史故障样本少、验证功能单一等问题。     

基于OSA-CBM的PHM系统设计

结合PHM系统的使用目标和飞机各运行场景下PHM实现场景,提出PHM系统主要实现的功能;对OSA-CBM开展研究,将PHM系统按照OSA-CBM的分层定义,并且以某型号的PHM系统设计为背景,提出了基于OSA-CBM的PHM系统设计框架;介绍了该PHM系统按照开放式体系架构要求开展的功能定义、层次划分,以及对每个层级的输入输出定义;以Rational ROSE软件为模型开发工具,建立了各层级间的数据流动关系以及同层级之间的数据传递关系,对端口、算法、时序、配置等信息以UML语言进行了规定;分别采用Visual C#2010和Matlab软件开发平台实现了不同层级的功能,最终共同搭建了PHM系统的演示平台,实现了数据采集层、数据采集层、状态监测层及健康评估层、表示层等层级功能,为后续PHM系统的多用户协同开发设计奠定了技术基础。     

PHM模型的工程化验证方法研究

模型验证技术在故障预测与健康管理(PHM)系统研制中受到高度重视,特别是如何将验证方法在具体的工程应用中体现规范性、系统性、通用性和实用性,已成为亟待解决的技术问题;在分析国内外相关研究现状的基础上,对PHM模型验证方法进行了系统深入的研究,阐述了故障数据获取方法和故障诊断和预测性能指标体系,并以机载诊断模型为例,对PHM模型验证流程作了详细介绍;最后,将此方法应用到了PHM验证平台的设计、开发和具体实现中,充分体现了PHM模型验证方法的工程化特点。     

机载PHM系统软件设计与验证

针对现有PHM系统软件开发中存在的软件模块规范性差、复用率低和鲁棒性弱等问题,提出了一种基于OSA-CBM标准的构件化机载PHM系统软件设计方法,描述了机载PHM系统软件的构件化模型定义、功能框架、分层体系结构和软件控制流程;设计了机载PHM系统的构件接口和核心功能构件;实现了符合OSA-CBM规范接口的构件化软件。通过原型系统软件验证了构件化机载PHM系统软件设计和开发方法的正确性,表明了该方法能够提升软件的规范性、复用率、鲁棒性和可扩展性。     

面向复杂装备PHM数据体系架构的研究

故障诊断与健康管理(PHM)利用装备产生的数据,经过数据处理等手段,能够实现对复杂装备的健康状态进行监测、故障诊断、预测和智能决策;在PHM的整个阶段会产生大量的数据,目前已有部分国内外机构针对PHM数据体系进行了研究与构建,然而大部分的数据仅仅是针对PHM数据的管理维护方面做了探讨,并不能清晰地、深入地梳理出现役装备的设计数据、使用数据及验证数据之间的逻辑关系,所以构建一套完整的PHM数据体系架构成为当前极为重要的工作;文章以装备PHM技术为背景,贯穿装备生产制造全寿命周期时间线,基于PHM系统的设备级、区域级、平台级数据的构建、融合为主线,补全PHM数据管理维护数据,形成一套具有装备特色的PHM数据体系架构,完善PHM不同数据要素之间的逻辑关系。     

装甲装备故障预测与健康管理系统技术研究

预测和健康状态管理(PHM)技术是一种先进测试、维修技术;从视情维修保障的背景出发,介绍了装甲装备PHM系统的内涵,进行了装甲装备故障模式影响和危害分析,明确了PHM系统具备的功能,初步构建了基于开放体系的装甲装备PHM系统的技术框架,并对其中的关健技术进行了深入研究,对炮控系统进行故障预测分析,结果和实际应用一致。     

动态数据驱动的交通仿真框架研究与实现

针对现有交通仿真中事先建立的理论模型难以准确预测交通状态发展趋势的问题,提出一种基于动态数据驱动应用系统范型的交通仿真框架。首先在微观仿真模型的基础上建立状态空间模型进行先验状态估计;继而将实测交通数据引入模型以调整和评估状态空间模型;基于交通状态非线性非高斯的特性,选用粒子滤波器,提出并实现了数据同化模型和相关算法,提炼传统粒子滤波器的关键步骤并对其进行改进,以提高状态估计的能力;最后基于微型交通仿真软件MovSim实现了上述框架。实验表明:基于该框架的交通状态预测精度得到明显提高,受测量误差和环境噪声的影响小,具有较强的预测稳定性和可靠性。     

故障预测与健康管理系统建模技术研究

简要介绍了PHM系统建模的主要方法,并依据飞机特征,给出飞机PHM系统分层体系模型,提出了基于数据的飞机典型部件液压泵PHM系统的建模方法,通过试验对该方法进行了验证.     

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。     

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.     

Editorial: Special issue on recent advances in hybrid control theory and applications

正The demands of a rapidly advancing technology for faster and more accurate controllers have always had a strong influence on the progress of automatic control theory.In recent years control problems have been arising with increasing frequency in widely different areas,which cannot be addressed using conventional control techniques.The principal reason for this is the fact that a highly competitive economy is forcing systems to operate in regimes where     

Information for Authors

正Aim The Journals of Zhejiang University-SCIENCE(A/B/C)areedited by the international board of distinguished Chinese andforeign scientists,and are aimed to present the latest devel-opments and achievements in scientific research in China andoverseas to the world’s scientific circles,especially to stimulateand promote academic exchange between Chinese and for-eign scientists everywhere.     

Enhancing a leaf radiative transfer model to estimate concentrations and in vivo specific absorption coefficients of total carotenoids and chlorophylls a and b from single-needle reflectance and transmittance

The relative concentrations of different pigments within a leaf have significant physiological and spectral consequences. Photosynthesis, light use efficiency, mass and energy exchange, and stress response are dependent on relationships among an ensemble of pigments. This ensemble also determines the visible characteristics of a leaf, which can be measured remotely and used to quantify leaf biochemistry and structure. But current remote sensing approaches are limited in their ability to resolve individual pigments. This paper focuses on the incorporation of three pigments—chlorophyll a, chlorophyll b, and total carotenoids—into the LIBERTY leaf radiative transfer model to better understand relationships between leaf biochemical, biophysical, and spectral properties.Pinus ponderosa and Pinus jeffreyi needles were collected from three sites in the California Sierra Nevada. Hemispheric single-leaf visible reflectance and transmittance and concentrations of chlorophylls a and b and total carotenoids of fresh needles were measured. These data were input to the enhanced LIBERTY model to estimate optical and biochemical properties of pine needles. The enhanced model successfully estimated reflectance (RMSE = 0.0255, BIAS = 0.00477, RMS%E = 16.7%), had variable success estimating transmittance (RMSE = 0.0442, BIAS = 0.0294, RMS%E = 181%), and generated very good estimates of carotenoid concentrations (RMSE = 2.48 µg/cm², BIAS = 0.143 µg/cm², RMS%E = 20.4%), good estimates of chlorophyll a concentrations (RMSE = 10.7 µg/cm², BIAS = − 0.992 µg/cm², RMS%E = 21.1%), and fair estimates of chlorophyll b concentrations (RMSE = 7.49 µg/cm², BIAS = − 2.12 µg/cm², RMS%E = 43.7%). Overall root mean squared errors of reflectance, transmittance, and pigment concentration estimates were lower for the three-pigment model than for the single-pigment model. The algorithm to estimate three in vivo specific absorption coefficients is robust, although estimated values are distorted by inconsistencies in model biophysics. The capacity to invert the model from single-leaf reflectance and transmittance was added to the model so it could be coupled with vegetation canopy models to estimate canopy biochemistry from remotely sensed data.     

Mr. Twinn’s bombes

This article discusses the history and design of the special versions of the bombe key-finding machines used by Britain’s Government Code & Cypher School (GC&CS) during World War II to attack the Enigma traffic of the Abwehr (the German military intelligence service). These special bombes were based on the design of their more numerous counterparts used against the traffic of the German armed services, but differed from them in important ways that highlight the adaptability of the British bombe design, and the power and flexibility of the diagonal board. Also discussed are the changes in the Abwehr indicating system that drove the development of these machines, the ingenious ways in which they were used, and some related developments involving the bombes used by the U.S. Navy’s cryptanalytic unit (OP-20-G).