基于PXI总线的导弹角速度编码器组合测试系统设计

针对某型导弹角速度编码器组合测试快速化、模块化、自动化的要求,通过对角速度编码器组合进行分析,结合角速度编码器组合输入信号的模拟、输出信号的采集、测试系统功能和性能要求,设计了基于PXI总线的导弹角速度编码器组合测试系统;介绍了测试系统的测试原理、硬件结构和软件组成、主要设计思想;实验表明,该测试系统工作性能稳定,能有效地进行组合测试和分组件测试并运用层次故障树分析法定位故障,提高了武器系统检测维修保障能力.     

基于神经网络观测器的飞控传感器在线故障诊断

为提高无人机飞行安全可靠性,针对飞行控制系统中常出现的传感器故障以及非线性气动力模型参数难以确定的问题,提出了基于BP神经网络观测器估计的故障诊断方法;引用LM改进算法对网络参数进行调整,构造了神经网络观测器模型逼近非线性系统,并运用于飞行控制系统进行在线数字仿真,对垂直陀螺输出卡死故障、恒偏差故障和恒增益故障分别进行仿真分析;仿真结果表明,所设计神经网络观测器可以有效估计系统输出,在线诊断传感器故障。     

基于Shannon熵的飞机交流发电机振动分析

飞机交流发电机是飞机关键部件之一,监测其健康状况具有重要意义。通过设计实验数据获取平台采集交流发电机在转速上升(从6000转/分到8500转/分)、平稳运行(7500转/分)及转速下降(8500转/分到6000转/分)三个阶段的振动信号,利用符号序列Shannon熵的计算方法以及符号化方法设定合适参数对振动信号进行了处理,得出了交流发电机在三个阶段的振动信号的Shannon熵;通过初步的分析表明,交流发电机在正常状态下三个阶段的Shannon熵都比较有规律的在一定范围内变化,一旦发生振动异常将会引起Shannon熵突变;经过分析讨论,Shannon熵的突变与否是可以用来反映交流发电机在机械方面是否存在故障隐患的。     

Do different reputation systems provide consistent signals of seller quality: a canonical correlation investigation of Chinese C2C marketplaces

In recent years, consumer-to-consumer (C2C) marketplaces such as eBay and Taobao have adopted a component rating system, and run it simultaneously with but independent of a binary rating system. This paper investigates the extent to which binary rating and component rating systems are able to provide consistent signals of sellers?? quality, focusing on the reputation system design under the Chinese context. Using field data from Taobao, we performed canonical correlation analyses and found that the reputation signals of the two systems are generally correlated. As expected, negative and neutral ratings accurately reveal buyer dissatisfaction. Our results, however, show that positive ratings exhibit negative correlations with the three component ratings (i.e., item-as-described, customer service, and on-time delivery), suggesting that large numbers of positive ratings on Taobao may encourage trust in the platform but do not help to choose credible sellers. Our results elucidate the role of cultural difference in explaining the negative relationship in China and provide important implications for the design of reputation systems.     

基于互触发的Oracle细粒度数据保护和恢复的研究及实现

本系统的主要思路是利用Oracle的触发器、Flash Recovery Area等技术,结合J2EE技术,实现一套基于B/S架构的Oracle数据保护和恢复系统,包括权限管理、数据恢复、系统管理三大模块,旨在解决以下问题:(1)建立新的权限控制。Oracle自带的权限控制不够安全,本系统拟创建一套新的权限体系,作为对Oracle的权限的补充,使业务系统的数据使用起来更加安全;(2)建立新的数据恢复。用软件实现Oracle的数据实时恢复,在真正执行危险操作以后,对数据进行针对性地、迅速恢复;(3)实现互触发保护,避免"通过人为的方式直接去drop触发器"之类操作的实现。     

Evaluation of contrast metrics for liquid‐crystal displays under different viewing conditions

Abstract— A psychophysical experiment was carried out to assess the perceptual contrast on a large‐sized liquid‐crystal display (LCD) under nine phases of viewing conditions. Based on the results, six contrast models employing different color attributes or the index of just‐noticeable difference (JND) were developed. Their performances were also tested by the visual data of the nine phases, which indicated that the model C_Q employing CIECAM02 brightness gives the best performance in predicting visual data under different viewing conditions among those models. A preprocessing step was also proposed to utilize the contrast model C_Q conveniently in the practical contrast evaluation of LCDs.     

Ambiguity-free edge-bundling for interactive graph visualization

Graph visualization has been widely used to understand and present both global structural and local adjacency information in relational data sets (e.g., transportation networks, citation networks, or social networks). Graphs with dense edges, however, are difficult to visualize because fast layout and good clarity are not always easily achieved. When the number of edges is large, edge bundling can be used to improve the clarity, but in many cases, the edges could be still too cluttered to permit correct interpretation of the relations between nodes. In this paper, we present an ambiguity-free edge-bundling method especially for improving local detailed view of a complex graph. Our method makes more efficient use of display space and supports detail-on-demand viewing through an interactive interface. We demonstrate the effectiveness of our method with public coauthorship network data.     

基于STM32的逆变弧焊电源控制器设计

数字化是弧焊电源的发展趋势,其关键在于控制器的数字化。目前市场上的大多数数字化产品价格相对高昂,采用STM32系列单片机进行经济型数字化弧焊电源控制器的设计和实现。该控制器采用数字式PI方法进行输出电流控制,并具有按键操作、液晶显示、过流保护、过热保护等功能。该控制器还具有良好的扩展I}生,可以通过修改程序增强系统功能。     

探索物联网人才培养模式

物联网在众多领域有着广泛的应用,产业空间巨大。物联网人才的培养变的尤为重要。根据国家和东莞经济结构的调整及发展战略,本着服务地方经济的理念,调整高等院校的专业方向和专业结构;根据社会经济的需要和安排,制订高等院校的专业人才培养方案和课程标准;根据地方经济环境,建设物联网专业,培养企业需求的人才。     

WC15Ni磁合金的质量控制

在WC15Ni无磁硬质合金生产过程中,选用粒度分布范围较窄的优质WC以及添加适量的Cr3C2,促进了抗弯强度的提高。