Optimal residual generation for fault detection in linear discrete time-varying systems with uncertain observations

This work deals with the problem of optimal residual generation for fault detection (FD) in linear discrete time-varying (LDTV) systems subject to uncertain observations. By introducing a generalized fault detection filter (FDF) with four parameter matrices as the residual generator, a novel FDF design scheme is formulated as two bi-objective optimization problems such that the sensitivity of residual to fault is enhanced and the robustness of residual to unknown input is simultaneously strengthened. A generalized operator based optimization approach is proposed to deduce solutions to the corresponding optimization problems in operator forms, where the related H_∞/H_∞ or $H_{?}/H_{\infty }$ FD performance index is maximized. With the aid of the addressed methods, the connections among the derived solutions are explicitly announced. The parameter matrices of the FDF are analytically derived via solving simple matrix equations recursively. It is revealed that our proposed results establish an operator-based framework of optimal residual generation for some kinds of linear discrete-time systems. Illustrative examples are given to show the applicability and effectiveness of the proposed methods.     

Fractional-order follower observer design for tracking consensus in second-order leader multi-agent systems: Periodic sampled-based event-triggered control

This paper investigates the tracking consensus problem for the second-order leader systems by designing fractional-order observer, where a periodic sampled-based data event-triggered control is employed. In order to track the position information of leader, observers for followers are designed by fractional-order system, where only the relative position information is available. Furthermore, in the process of observers design, a sampled-based event-triggered strategy is proposed so that observers use the event-triggered sampled-data, to reduce the overall load of the network. In our proposed event-triggered strategy, the event detection only works at every sampling time instant which determines whether the sampled-data should be discarded or used. Under this control strategy, the Zeno-behavior is absolutely excluded since the minimum of inter-event times is inherently lower bounded by one sampling period. It is found that the followers can track state of the leader if fractional-order observers are appropriately designed and relevant parameters are properly selected. By using the generalized Nyquist stability criterion, a necessary and sufficient condition for the observer tracking consensus of the second-order leader systems is derived. The results show that the real and imaginary parts of the eigenvalues of the augmented Laplacian matrix, and fractional-order α of observer play a vital role in reaching consensus.     

A decentralized control method for frequency restoration and accurate reactive power sharing in islanded microgrids

To achieve the frequency restoration (FR) and accurate reactive power sharing (RPS) in islanded microgrids (MGs), an improved P-f droop control is proposed. Firstly, the inverter impedance, whose value is set by the virtual impedance method, is used to minimize the impact of line resistance on powers coupling and RPS. Then, in order to restore the frequency of distributed generations (DGs) to the rated value, the reference is changed for compensating the frequency deviation (FD) caused by loads change. And the fast FR rate is achieved under a large constant k. Besides, in order to eliminate the inaccuracy of RPS caused by voltages difference (VD), the line voltage drop (LVD) is used to compensate the voltage droop characteristics. The use of voltage feedback ensures that the obtained voltage is desired after the LVD compensation. Finally, the simulation in RT-LAB indicates the effectiveness of proposed method in an islanded MG model.     

高中生职业生涯选择能力培养对策研究

新高考改革抓住了选择性和多样性两个核心概念,赋予了学生更多的自主选择权,给学生提供了一系列选科、选课、选考、选学校、选专业以及选未来职业等选择机会,是实现个人能力和加速自主发展的好契机.新高考改革要求培养高中生自主选择能力,包括对职业生涯选择能力培养也提出了更高的要求,这让很多普通高中学校和家长、学生在短期内都感到不适.在诸多选择面前,如何培养高中生选择能力越来越引发各界关注.只有以新高考制度推行为载体,通过分析新高考政策中的选择元素,培养高中生科学的职业生涯选择能力,才能有效帮助高中生选择最理想的职业.     

创新研究群体典型项目的合作网络特征

运用社会网络分析方法,对国家自然科学基金委员会(NSFC)设立的创新研究群体科学基金资助的10个典型创新研究群体,从结构特征、负责人影响力和演化特征三方面进行研究发现:创新研究群体合作网络在结构上具有高连通性,但群体紧密程度差异明显,合作网络的集权程度也存在较大差异,大多数群体负责人在群体中具有较大影响力,但也有少数影响力相对较弱;合作网络中子群的演化路径可以分为汇聚和分离两类。总体来说,在创新研究群体项目的支持下,群体的规模、合作紧密程度都得到了持续稳定的发展。NSFC的创新研究群体项目切实促进了创新研究群体的建设,资助绩效显著。     

基于出版转制的学术生态链信息流转效率研究

【目的/意义】针对出版转制对学术生态链信息流转效率的影响,提出基于出版转制的学术生态链信息流转 效率提升策略,对出版转制环境下提升学术生态链信息流转效率,优化学术生态环境具有一定的指导作用。【方法/ 过程】在界定学术生态链概念基础上,构建了学术生态链概念模型和基于出版的学术生态链信息流转模型,分析出 版转制对学术生态链信息流转效率的影响,从政府、出版机构、作者和用户四个方面提出基于出版转制的学术生态 链信息流转效率提升策略。【结果/结论】学术生态链是指学术信息人为实现学术信息流转而形成的链式依存关 系。出版转制使学术信息流转内容多样,部分质量下降,速度变快,广度缩小。为了提高学术生态链信息流转效 率,应发挥政府部门的引导监督与支持作用、提升出版机构的经营理念和竞争能力、强化作者的自律意识和创新精 神、改进信息用户的消费观念和择优方法。     

大数据时代合作模式下的图书馆数字资源长期保存模型分析

本文在分析大数据环境下图书馆采用合作保存必要性的基础上,探讨了国际主流的数字资源保存合作模式,进而提出目前我国图书馆应采用的数字保存合作模式和资源存储方式,最后设计了图书馆基于OAIS的数字资源长期保存协作保存平台模型,并对该模型构成、运行模式以及主要功能进行了深入的描述和分析。相信本研究将对合作模式下图书馆数字资源长期保存系统的建设起到抛砖引玉的作用。     

普通高校篮球课异质分组合作教学评价方法实验研究

运用文献法、调查法、教学实验法和数理统计法,在普通高校篮球专项教学中进行了异质分组合作教学组织形式和常规教学组织形式的实验研究,将每班学生分成若干个异质学习小组,充分利用合作学习的优势。实验结果表明在异质分组合作教学组织形式下,采用修改因子法进行过程性评价,将过程性评价与终结性评价结合可以促进高校篮球教学效果的提高,学生获得较强的内部动机水平。     

解读萨特存在主义哲学视域下的《小城畸人》

从萨特存在主义哲学中的＂自为存在＂概念入手,指出＂自为存在＂可由＂表世界＂和＂里世界＂二者共同构成。运用这一理论深入剖析《小城畸人》中＂畸人＂＂存在＂的本质,并援引萨特＂自欺＂理论解读＂畸人＂的解脱方式：通过＂自欺＂逃避自我,通过＂欺他＂强迫他我,从而揭示＂畸人＂并不＂畸＂,而是入世者真实存在的心理写照。     

北京广播电视大学文化局工作站的发展历程

通过研究,本文将北京广播电视大学文化局工作站的事业发展分为图书馆专业教育时期（1985—1994）、专业教育向特色教育转型时期（1994—2000）、开展现代远程开放教育,迎来新的发展时期（2001年至今）三个历史时期。文章最后指出,只有根据首都经济建设和文化建设的需要,解放思想,充分利用自己所有的教育资源,积极采用多种办学形式,行业电大才能为社会培养更多的＂留得住、用得上、信得过＂的专业人才。