具有自动误差补偿功能的智能磁航向系统

研制了一种具有三种误差补偿方法的智能磁航向系统(智能电子磁罗盘)。传统的给定基准法具有满意的补偿效果,但试验复杂。对水平情况,椭圆假设法把误差的形成过程假设为从圆到椭圆的变化过程;而对任意姿态的情况,椭球面假设则把该过程假设为从圆球面到椭球面的变化过程。其逆过程就是误差补偿过程。后两种方法试验非常方便,不需要高准确度的设备。试验结果表明,这两种方法可实现自动误差补偿和自动校准,补偿效果满意,成本低。还设计了一个包含上述三种方法的虚拟仪表用于计算误差补偿系数。用EEPROM永久保存这些系数,消除了类似电位计的可动部件。该系统体积小、成本低、可靠性高,可用于小型飞机、车辆、船舰等运载工具。     

一种磁阻式电子罗盘测试和标定方法研究

在分析了影响磁罗盘工作过程中可能存在的误差及其来源,针对罗差误差,提出一种椭圆假设补偿法与最小二乘法求补偿系数相结合的方法对电子罗盘进行标定。实验验证了最大误差达34.2°的电子罗盘系统经过标定补偿后误差降至3°以内,能基本满足一般导航系统的要求。该方法也适用于其他磁罗盘的标定。     

霍尔罗盘误差补偿算法及实验分析

研究了锑化铟(InSb)霍尔罗盘中的椭圆误差补偿问题.文中详细分析了基于椭圆假设的罗盘误差补偿算法,使罗盘具备了自动误差补偿和自动校准功能.实验结果表明.利用这种算法的霍尔罗盘精度达到了±2.46°,基本达到了实用要求.本文还详细分析了影响罗盘精度的原因和以后改进的措施.     

基于隧道磁阻传感器的三维电子罗盘设计

针对现有电子罗盘在地磁场检测时易受到外界磁场干扰而导致测量精度不高的问题,设计了基于隧道磁阻传感器( TMR)的三维电子罗盘并完成样机制作。研究了实际环境中电子罗盘的误差特性,经椭球拟合校正后,采用基于椭圆假设的椭圆拟合方法对误差进行补偿,补偿后其方位角精度可达0.85°,有效降低94.81%的方位角误差。实验结果验证了TMR传感器在电子罗盘应用的可行性。     

由椭球到圆球的磁传感器补偿技术

针对低成本电子罗盘在大倾角情况下航向角误差急剧增大这一问题,将误差的补偿假设为由椭球到圆球过程.研究了基于姿态误差矩阵补偿的校正算法,将电子罗盘的补偿技术由平面椭圆补偿拓展到空间椭球补偿.通过最小二乘法、牛顿法、最速下降法等手段求解得到了最终的姿态误差矩阵.通过实验可以证实:此方法可以有效减小电子罗盘在大倾角情况下的航向误差,并且具有成本低、简单和可靠性高等优点.     

一种数字磁罗盘全罗差自主优化补偿方法

为了进一步提高数字磁罗盘全姿态罗差补偿精度,提出了一种基于地磁场分量的罗差自主优化补偿方法.从罗差补偿模型出发,分析椭球拟合补偿方法的局限性,在对参数缺失和剩余误差分析的基础上,建立了包含缺失参数的优化补偿模型;针对非线性优化模型引入粒子群算法PSO(Particle Swarm Optimization)对模型参数进行估计,数值仿真结果证明了算法可有效估计缺失参数.实验结果表明,优化补偿过程无需借助外部辅助姿态信息,俯仰角-20°姿态下,优化补偿方法在椭球假设补偿基础上将其最大误差由4.8°降至1.9°,误差标准差由1.5°降至1.1°.     

三轴电子罗盘的磁航向角误差补偿研究

针对某水下运载器中罗盘的工作状态,提出了适合于水下工作的电子罗盘的误差补偿方法。通过分析误差产生的原因,结合实际情况,提出将补偿区间分段的方法,在各个区间分别进行最小二乘误差补偿。实验结果表明:采用分段补偿的方法可以有效补偿小区间误差,能够将最大误差降低到0.3°之内,提高其磁航角的精度,满足高精度导航系统要求。     

电子罗盘最佳椭圆误差补偿方法

摘要：电子罗盘的方位数据可作为导航系统的初始位置数据,然而,电子罗盘在实际使用中极易受到外界磁场环境的影响而产生罗差,有效的减少罗差是提高导航系统初始位置精度的一项技术措施。本文研究了电子罗盘的最佳椭圆误差补偿方法,并把该算法应用到实际SINS-GPS组合导航初始对中,给出了实施方案和罗差补偿数据。实验验证,最佳椭圆误差补偿算法有效的消除了罗差,该罗盘可以应用于普通导航初始位置对准及其它领域。     

基于椭圆旋转的磁传感器误差补偿算法

针对硬磁干扰和软磁干扰条件下的磁罗盘误差补偿问题,对传统的误差椭圆假设模型进行改进,提出一种基于椭圆旋转的磁传感器误差补偿算法。分析磁罗盘误差产生的因素,并建立椭圆旋转数学模型。采用非线性最小二乘拟合算法推导出误差补偿参数公式。利用Honeywell双轴磁阻传感器的测量值和椭圆旋转拟合的算法,对两轴磁传感器进行测试标定与误差补偿。实验结果表明,椭圆旋转算法能够有效补偿外部磁场产生的硬磁干扰和软磁干扰,与传统的椭圆模型补偿算法相比,该算法测得的航向角最大误差从2.0°减小到0.4°。     

无磁转台的电子罗盘误差分离标定方法

采用3个分立的磁感式磁传感器和三轴加速度传感器制作了全数字输出电子罗盘;基于自制三轴旋转无磁转台提出了一种电子罗盘标误差分离标定方法.通过无磁转台获取磁传感器敏感轴非正交或未对准的参数和磁传感器输出特性曲线,磁传感器的灵敏度系数因子和偏置量.分别评价偏置、灵敏度系数不一致以及非正交或未对准对电子罗盘方位角精度的影响.实验结果表明:经过校准后,电子罗盘水平面内误差不超过0.22°,而俯仰角和翻滚角在60°内时,方位角最大误差约为0.4°,说明了标定方法的有效性.     

Call for Papers The 6^th International Conference on Grid and Cooperative Computing

Recent years have seen rapid advances in various grid-related technologies, middleware, and applications. The GCC conference has become one of the largest scientific events worldwide in grid and cooperative computing. The 6th international conference on grid and cooperative computing (GCC2007) Sponsored by China Computer Federation (CCF),Institute of Computing Technology, Chinese Academy of Sciences (ICT) and Xinjiang University ,and in Cooperation with IEEE Computer Soceity ,is to be held from August 16 to 18, 2007 in Urumchi, Xinjiang, China.     

煤矿井下安全监控分站的设计及其仿真实现

为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值.     

法律信息库系统

本文分析了法律数据库的结构和特点，介绍了采用面向对象设计方法和超文本数据库技术开发和实现法律信息库系统将作为重要网络资源之一为不同用户进行法律咨询服务。     

View-based model-driven architecture for enhancing maintainability of data access services

In modern service-oriented architectures, database access is done by a special type of services, the so-called data access services (DAS). Though, particularly in data-intensive applications, using and developing DAS are very common today, the link between the DAS and their implementation, e.g. a layer of data access objects (DAOs) encapsulating the database queries, still is not sufficiently elaborated, yet. As a result, as the number of DAS grows, finding the desired DAS for reuse and/or associated documentation can become an impossible task. In this paper we focus on bridging this gap between the DAS and their implementation by presenting a view-based, model-driven data access architecture (VMDA) managing models of the DAS, DAOs and database queries in a queryable manner. Our models support tailored views of different stakeholders and are scalable with all types of DAS implementations. In this paper we show that our view-based and model driven architecture approach can enhance software development productivity and maintainability by improving DAS documentation. Moreover, our VMDA opens a wide range of applications such as evaluating DAS usage for DAS performance optimization. Furthermore, we provide tool support and illustrate the applicability of our VMDA in a large-scale case study. Finally, we quantitatively prove that our approach performs with acceptable response times.     

International Journal of Automation and Computing Table of Contents

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Information for authors

正SCIENCE CHINA Information Sciences(Sci China Inf Sci),cosponsored by the Chinese Academy of Sciences and the National Natural Science Foundation of China,and published by Science China Press,is committed to publishing highquality,original results of both basic and applied research in all areas of information sciences,including computer science and technology;systems science,control science and engineering(published in Issues with odd numbers);information and communication engineering;electronic science and technology(published in Issues with even numbers).Sci China Inf Sci is published monthly in both print and electronic forms.It is indexed by Academic OneFile,Astrophysics Data System(ADS),CSA,Cabells,Current Contents/Engineering,Computing and Technology,DBLP,Digital Mathematics Registry,Earthquake Engineering Abstracts,Engineering Index,Engineered Materials Abstracts,Gale,Google,INSPEC,Journal Citation Reports/Science Edition,Mathematical Reviews,OCLC,ProQuest,SCOPUS,Science Citation Index Expanded,Summon by Serial Solutions,VINITI,Zentralblatt MATH.     

Erratum to: Fast global kernel fuzzy c-means clustering algorithm for consonant/vowel segmentation of speech signal

正Erratum to:J Zhejiang Univ-Sci C(ComputElectron)2014 15(7):551-563doi:10.1631/jzus.C1300320The original version of this article unfortunately contained mistakes.Algorithm 6 should be as follows:Algorithm 6 FGKFCM-F clustering Input:(1)X={x_1,x_2,…,x_N},,x_iR~d,i=1,2,…,N,the dataset;(2)C,1C≤N,the number of clusters;(3)ε0,the stopping criterion;     

Journal of Zhejiang University-SCIENCE C (Computers & Electronics) Total contents

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A pragmatic multi-method investigation of discrepant technological events: Coping,attributions, and ‘accidental’ learning

Discrepant technological events or situations that entail a problem, a misunderstanding or a difficulty with the Information Technology (IT) being employed, are common in the workplace, and can lead to frustration and avoidance behaviors. Little is known, however, about how individuals cope with these events. This paper examines these events by using a multi-method pragmatic approach informed by coping theory. The results of two studies – a critical incident study and an experiment – serve to build and test, respectively, a theoretical model that posits that individuals use a variety of strategies when dealing with these events: they experience negative emotions, make external attributions, and adopt engagement coping strategies directed at solving the event, eventually switching to a disengagement coping strategy when they feel they have no control over the situation. Furthermore, users’ efforts may result in ‘accidental’ learning as they try to overcome the discrepant IT events through engagement coping. The paper ends with a discussion of the results in light of existing literature, future opportunities for research, and implications for practice.