Learning commutative deterministic finite state automata in polynomial time

We consider the problem of learning the commutative subclass of regular languages in the on-line model of predicting {0,1∼-valued functions from examples and reinforcements due to Littlestone [7,4]. We show that the entire class of commutative deterministic finite state automata (CDFAs) of an arbitrary alphabet sizek is predictable inO(s ^k) time with the worst case number of mistakes bounded above byO(s ^kk logs), wheres is the number of states in the target DFA. As a corollary, this result implies that the class of CDFAs is also PAC-learnable from random labeled examples in timeO(s ^k) with sample complexity, using a different class of representations. The mistake bound of our algorithm is within a polynomial, for a fixed alphabet size, of the lower boundO(s+k) we obtain by calculating the VC-dimension of the class. Our result also implies the predictability of the class of finite sets of commutative DFAs representing the finite unions of the languages accepted by the respective DFAs. Part of this work was supported by the Office of Naval Research under contract number N00014-87-K-0401 while the author was at the Department of Computer and Information Science, University of Pennsylvania, and N0014-86-K-0454 while at the Department of Computer and Information Sciences, U.C. Santa Cruz. The author’s email address is abe@IBL.CL.nec.co.jp     

Unsafe acts and unsafe outcomes in aircraft maintenance

Road safety studies using the Driver Behaviour Questionnaire (DBQ) have provided support for a three-way distinction between violations, skill-based errors and mistakes, and have indicated that a tendency to commit driving violations is associated with an increased risk of accident involvement. The aims of this study were to examine whether the three-way distinction of unsafe acts is applicable in the context of aircraft maintenance, and whether involvement in maintenance safety occurrences can be predicted on the basis of self-reported unsafe acts. A Maintenance Behaviour Questionnaire (MBQ) was developed to explore patterns of unsafe acts committed by aircraft maintenance mechanics. The MBQ was completed anonymously by over 1300 Australian aviation mechanics, who also provided information on their involvement in workplace accidents and incidents. Four factors were identified: routine violations, skill-based errors, mistakes and exceptional violations. Violations and mistakes were related significantly to the occurrence of incidents that jeopardized the quality of aircraft maintenance, but were not related to workplace injuries. Skill-based errors, while not related to work quality incidents, were related to workplace injuries. The results are consistent with the three-way typology of unsafe acts described by Reason et al. (1990) and with the DBQ research indicating an association between self-reported violations and accidents. The current findings suggest that interventions addressed at maintenance quality incidents should take into account the role of violations and mistakes, and the factors that promote them. In contrast, interventions directed at reducing workplace injury are likely to require a focus on skill-based errors.     

ISO/IEC 17025:2005《检测和校准实验室能力的通用要求》中存在的错误

本文就ISO/IEC17025《检测和校准实验室能力的通用要求》中存在的错误,提出看法。ISO/IEC17025:2005《检测和校准实验室能力的通用要求》对ISO/IEC17025:1999进行了修改和补充,使ISO/IEC17025进一步完善和提高,但笔者在学习过程中仍发现ISO/IEC17025标准中存在的一些错误,提出供实验室建立管理体系和实验室评审时参考。     

螺杆泵选型误区分析及对策

从工艺和电气设计的角度阐述正常螺杆泵设计选型的误区,并重点分析电机与螺杆泵启动力 矩的匹配机理及影响因素,提出解决问题的对策     

空调系统中冷却塔布置失误及改进措施

本文分析了空调系统中冷却塔布置设计和安装的常见错误,提出了相应的改进措施。     

基于复杂网络理论和遗传算法的分类方法

结合复杂网络研究的部分新理论成果和遗传算法的思想,提出一种新的分类方法。该方法将数据集按给定的相似度公式构造出具有社团结构的网络,在此网络的基础上用遗传算法的思想进行分类。算法引进社团模块度作为适应度函数,并且提出了节点归类错误率（NCM）对每次迭代产生的解进行纠错,提高了分类质量和速度。实验表明算法在分类精度和时间上都优于基于加权复杂网络特征的K—means聚类算法（WCNFC）。     

浅谈建筑电气施工图设计应注意的几个问题

本文从某工程建筑电气施工图设计的失误，分析其产生的原因，探索减少失误的思路与对策。     

列车管贯通状态检测的几个技术问题

列车管贯通状态是铁路安全行车的决定因素，但因为现场条件复杂难以准确检测，文章针对设计中存在的特殊问题，讨论了有利于提高测量准确性的基准参数设定，疏失误差判决处理，软件滤波和抗干扰等实现方法。     

浅析设备管理中故障预防性决策的误区

针对开展设备可靠性与维修性的设计 ,筹划设备的保障措施 ,就预防设备故障的有关方面提出在生产应用上的一些问题和见解     

多用户Foxbase＋错误陷井的应用实例浅析

本文总结了多用户Ｆｏｘｂａｓｅ＋数据系统中错误陷井的使用经验，给出了一组在多用户数据库系统中解决文件访问冲突及保护系统现场信息的例程