电机控制类水轮机调速器的研究与应用

本文作者认为,电机控制类水轮机调速器综合应用了电子计算机、自动控制、伺服驱动和新型机械结构等多方面的技术成果,可大幅度提高调速系统的可靠性,是水轮机调节行业的一次技术革命;同时,电机控制类电/机转换部件构成的系统已形成了具有我国自主知识产权的一类水轮机调速器,它不但具有我国特色,而且符合国情,已得到广泛推广和应用。     

舰用风冷式柴油机匹配电子调速器的试验与验证

某型艇的风冷柴油发电机组在试验时发现调速性能超差、达不到要求的精度。通过对风冷柴油机结构特点的分析论证,选用国产成熟的电子调速器进行匹配。试验验证表明,达到了机组成套技术要求的精度等级。     

复杂约束下的挠性航天器姿态参考管理控制

本文提出了一种基于显式参考管理与模态观测器的挠性航天器姿态机动控制方法. 首先, 采用改进的罗德里格斯参数建立了航天器的运动学和动力学模型, 分析了存在的控制约束和角速度约束. 在此基础上, 设计了基于显式参考管理的约束挠性航天器姿态重定向控制算法. 由于挠性模态不能直接测量, 内层设计了模态观测器, 并将观测器观测得到的模态坐标作为内层无约束控制器的输入. 随后, 外层导航模块根据所需满足的约束条件设计了相应的动态路径, 该路径可以根据当前状态以合适的速率收敛到最终状态, 通过跟踪该路径, 航天器姿态就可以在满足约束的情况下快速到达期望位置. 通过构造合适的李雅普诺夫函数, 严格证明了该挠性航天器显式参考管理姿态控制算法的稳定性. 最后, 仿真结果进一步验证所设计算法的约束处理效果与振动抑制能力.     

Risk governance during the COVID-19 pandemic: A quantitative content analysis of governors' narratives on twitter

The current study addresses the communication aspect of risk governance during the COVID-19 pandemic by examining whether governors' tweets differ by political party, gender and crisis phase. Drawing on the Centers for Disease Control and Prevention's Crisis Emergency Risk Communication (CERC) model and framing literature, we examined the salience of five CERC's communication objectives, namely acknowledge crisis with empathy, promote protective actions, describe preparedness/response efforts, address rumours and misunderstanding and segment audience. Using a deductive and inductive approach, we analysed 7000 Twitter messages sent by the 50 US state governors during the period of 13 March 2020 to 17 August 2020. Our findings suggest that governors' tweets aligned with CERC's communication objectives to a varying degree. We found main and interaction effects of political party, gender and crisis phase on governors' communication objectives. New emergent communication objectives included attention to mental health, call for social influencers and promoting hope. Implications are discussed.     

Independence,trust, and loyalty. The county governor's coordination of public and voluntary resources in crises in Norway

Collaboration and communication are crucial factors in handling crises, whether the crisis is a serious landslide requiring emergency response for several days or a pandemic lasting for months. This article describes and analyses the governmental relationship with the local communities in critical situations with the COVID-19 pandemic as a case. In the Norwegian administrative organisation, the county governors have a defined role in their emergency responsibilities, including being chairpersons of the County Emergency Council (CEC). The Norwegian emergency system is organised with samvirke (translated to English as coordinated cooperation) as a core constituency. In this system, voluntary organisations have a formalised role in taking an active part in crisis handling. The inclusion of voluntary organisations in the CEC, as seen by the county governors, is used as a case study. The challenges of collaboration can be analysed using the terms independence, trust, and loyalty. Data are collected from governing documents and interviews with the county governors. The main factor in successful coordination is the governors' ability to support the municipalities and the local communities. They must balance between wants of independence and state control. The art of this balancing act is the topic of this article.     

新型的极限调速器──CB01型超速保护卸油装置

本文介绍了一种新型极限调速器的工作原理和特性．它是在液压调速器原理基础上研制的，克服了机械式调速器笨重、正反车保护转速相差较大的缺点，具有本积小、重量轻、工作转速稳定可靠的特点．