Novel model reference adaptive control laws for improved transient dynamics and guaranteed saturation constraints     

Robert B. Anderson  Julius A. Marshall  Andrea L’Afflitto 《Journal of The Franklin Institute》2021,358(12):6281-6308

In classical model reference adaptive control (MRAC), the adaptive rates must be tuned to meet multiple competing objectives. Large adaptive rates guarantee rapid convergence of the trajectory tracking error to zero. However, large adaptive rates may also induce saturation of the actuators and excessive overshoots of the closed-loop system’s trajectory tracking error. Conversely, low adaptive rates may produce unsatisfactory trajectory tracking performances. To overcome these limitations, in the classical MRAC framework, the adaptive rates must be tuned through an iterative process. Alternative approaches require to modify the plant’s reference model or the reference command input. This paper presents the first MRAC laws for nonlinear dynamical systems affected by matched and parametric uncertainties that constrain both the closed-loop system’s trajectory tracking error and the control input at all times within user-defined bounds, and enforce a user-defined rate of convergence on the trajectory tracking error. By applying the proposed MRAC laws, the adaptive rates can be set arbitrarily large and both the plant’s reference model and the reference command input can be chosen arbitrarily. The user-defined rate of convergence of the closed-loop plant’s trajectory is enforced by introducing a user-defined auxiliary reference model, which converges to the trajectory tracking error obtained by applying the classical MRAC laws before its transient dynamics has decayed, and steering the trajectory tracking error to the auxiliary reference model at a rate of convergence that is higher than the rate of convergence of the plant’s reference model. The ability of the proposed MRAC laws to prescribe the performance of the closed-loop system’s trajectory tracking error and control input is guaranteed by barrier Lyapunov functions. Numerical simulations illustrate both the applicability of our theoretical results and their effectiveness compared to other techniques such as prescribed performance control, which allows to constrain both the rate of convergence and the maximum overshoot on the trajectory tracking error of uncertain systems.  相似文献   

National Institutes of Health public access policy and the University of Michigan Libraries' role in assisting with depositing to PubMed Central     

Merle Rosenzweig  Anna Ercoli Schnitzer  Jean Song  Scott Martin  Jim Ottaviani 《Journal of the Medical Library Association》2011,99(1):97-99

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基于LMDI的南京市工业经济能源消费碳排放实证分析   总被引：5，自引：2，他引：3  

史安娜  李淼 《资源科学》2011,33(10):1890-1896

工业经济的能源消费是碳排放的主要来源,研究城市工业经济能耗碳排放的特征和影响城市工业经济能耗碳排放的因素具有很强的代表性。本文以南京市为例,首先从碳排放总量和碳排放强度等指标分析了2000年-2009年南京市工业经济碳排放现状和特征,然后运用LMDI方法构建了南京市工业经济能耗碳排放因素分解模型,定量分析了2000年-2009年间产业规模、能源强度、能源结构和能源排放强度四个影响因素对南京市工业经济碳排放的影响。研究结果表明,产业规模效益是南京市工业经济碳排放增长的主要促进因素,能源强度效应是南京市工业经济碳排放增长的主要抑制因素,能源结构效应和能源排放强度效应对南京市工业能源结构效应没有明显变化。在此基础上,提出了减排的相关政策建议。  相似文献   

Chinese Culture Year Celebrated in Australia     

Zi Yue’er 《中外文化交流(英文版)》2011,(8):4-9

During Chinese Vice Premier Li Keqiang’s official visit to Australia in October 2009, Chinese and Australian leaderships reached a consensus of hosting cultural years in each other’s country. From June 2010 to June 2011, "Experience Australia"—the Year of Australian Culture was successfully held in China. From June 2011 to June 2012, "Experience China"—the Year of Chinese Culture (YCCiA) is celebrated in Australia, featuring nearly 100 cultural events ranging from performing arts projects to visual art exhibitions to film festivals.  相似文献   

Euro-Asia Economic Forum Highlights Public Cultural Service     

Zi Yue’er 《中外文化交流(英文版)》2011,(11):4-7

Public cultural ser vice has gained increasing attention worldwide in recent years. It has become ever y government’s top priority to build a well-developed public cultural service system, provide diverse cultural products and promote cultural consumption by the public. In one-day disccusions of the Cultural Session, participants shared each other’s experience in public cultural service, in particular, concepts and practices of Xi’an City. Participants reached a consensus of increasing exchanges and cooperation in the sector of public culture in the future.  相似文献   

Positive functions of emotions in achievement sports     

Puig N  Vilanova A 《Research quarterly for exercise and sport》2011,82(2):334-344

This article presents the results of two research projects on the emotions of men engaged in achievement outdoor sports. The conditions were analyzed under which emotions carry out positive functions. The question strikes us as a fundamental one, because it is of crucial importance when it comes to increasing sportspeople's success. The theoretical framework applied was that of microfunctionalism. The method, of a qualitative nature, was based on in-depth interviews, each lasting between 1.5 and 2 hr with a total of 14 sportspersons. The results show that in order for emotions to fulfill positive functions, three conditions must be met: (a) existence of passion, which, with its dialectical character of pleasure and suffering underlies all the other emotions and acts as a motor that pushes the sportsperson forward, despite all the contretemps he might meet on the way; (b) intense emotion work, which may be conducted only if accompanied by knowledge and experience of the natural environment acquired over the years; and (c) conciliation between emotion work and the feeling rules characteristic of each sport subculture. For those individuals who pursue achievement in outdoor sports, these results will provide more concrete indications regarding how to carry out the emotional preparation required for these sports.  相似文献   

新时代背景下的数学类专业新理科人才培养协同系统构建研究     

刘建刚  赵军产  廖云华 《科教文汇》2021,(9)

该文在新时代背景下,基于系统论、控制论、协同论的视角,探讨聚焦如何培养数学类专业新理科人才。结合大数据、人工智能、5G等新技术、新业态、新变革,分别从人才培养方案、课程体系、师资队伍建设、实践环节等方面,探寻新时代背景下数学与应用数学、信息与计算科学、金融数学等与数据科学和大数据技术专业人才培养协同机制,努力构建数学类新理科专业人才培养协同系统。  相似文献   

长沙市民间自办公共阅读空间发展研究——以雨花区“和+共享图书馆”为例     

戴艳清  郑童 《图书情报工作》2021,65(20):42-49

[目的/意义] 针对"和+共享图书馆"的建设现状进行分析,反映长沙市民间自办公共阅读空间的一般性问题,为长沙市民间自办公共阅读空间可持续发展提出优化建议。[方法/过程] 通过现场观察、问卷调查、访谈法等方法对"和+共享图书馆"建设现状和特点进行剖析,认为存在专业人员短缺、空间利用率偏低、营销形式单一等问题。[结果/结论] 提出优化建议包括：构建运营管理机制;加强专业人员培养;增强公共阅读空间服务的可及性和丰富服务营销形式等,以促进长沙市民办公共阅读空间的良性发展。  相似文献   

Public libraries embrace citizen science: Strengths and challenges     

Anna Cigarini  Isabelle Bonhoure  Julián Vicens  Josep Perelló 《Library & information science research》2021,43(2):101090

Can public libraries become hubs for citizen science? In line with the principles of citizen science, this question was answered collaboratively with librarians from the Barcelona Network of Public Libraries who performed two hands-on activities. One activity was a training course taken by 30 librarians from 24 different libraries which enabled them to envisage citizen science implementation at each library. The other activity consisted of co-creating a citizen social science project and involved 40 library users, seven librarians from three different cities, and professional scientists. The analysis considers the perspectives of both librarians and users, through participant observation, surveys, and a focus group to identify strengths and challenges. The overall results suggest that public libraries can offer leadership in the promotion of citizen science and contribute to the mission of public libraries to act as local community hubs. The main challenges identified were related to the complexity of collaboration, uncertainty regarding research co-creation, and participant retention strategies.  相似文献   

A Study on Human-Computer Interaction Mechanism in an Intelligent Tutoring System     

GAO Hongli  YANG Lei  XU Sheng  LONG Zhou  LIU Kai  HU Xiang’en 《Frontiers of Education in China》2022,17(1):100

Discussion is a common and important learning process. Involvement of a virtual agent can provide adaptive support for the discussion process. Argumentative knowledge construction is beneficial to learners’ acquisition of knowledge,but the effectiveness of argumentative scaffolding in existing studies is not consistent. Based on an intelligent discussion system, a total of 47 undergraduate students took part in the experiment and they were assigned to three different conditions: content-related plus content-independent scaffolding condition, content-related scaffolding condition, and the control condition. Under the content-related and content-independent scaffolding condition, the computer agent provided an idea from semantically different categories (content-related scaffolding) according to the automatic categorization of the current contributions, and further inquired the participants about their attitudes and reasons (content-independent scaffolding). Under the condition of content-related scaffolding condition, the virtual agent only provided semantically different viewpoints. Under the control condition, the subjects expressed their opinion independently without the participation of the virtual agent. Findings revealed that compared with the control group, when the virtual agent provided semantically different ideas (content-related scaffolding), the discussion breadth (number of categories) was improved and the subjects felt that they had a more comprehensive understanding of the problem. Compared with the content-related scaffolding condition, when the virtual agent provided semantically different ideas and further asked about the attitudes and reasons, the subjects expressed more agreement with these views, but mentioned fewer categories during the discussion. This study suggests that the content-related scaffolding can facilitate the cognitive processing effect relevant to the topic of discussion. When the content independent scaffolding is added, it can promote the argumentative processing, but may have a negative effect on the cognitive processing related to the topic discussed.  相似文献