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Adaptive output-feedback tracking for nonlinear systems with unknown control direction and generic inverse dynamics

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Science China(Information Sciences) 2022年第8期65卷 134-149页

作者： Yuan wang yungang LIU School of Control Science and Engineering Shandong University

This paper studies adaptive output-feedback tracking for a class of typical uncertain nonlinear systems. In the context of unknown control direction, a generic uncertainty encountered inevitably in practice is adequately taken into consideration, i.e., the ISpS(input-to-state practically stable) inverse dynamics acting as the dynamic differences between the real plants and the models. Besides, the systems in question also permit two critical ingredients, i.e., unmeasured-state dependent nonlinearities and arbitrary functionof-output growth on unknown system nonlinearities. The three ingredients together largely challenge the feasibility/availability of practical tracking by means of output feedback. Nevertheless, a new control strategy is proposed by flexibly integrating the dynamic compensation based on Nussbaum-type gain, backstepping design technique together with the refined pseudo-sign and pseudo-dead-zone functions that were introduced for the first time in our previous studies. The two refined functions, which are sufficiently smooth, can moderately avoid the use of smooth domination/treatment in control design and can potentially render the attained control strategy tighter and less conservative. Moreover, to keep the order of the closed-loop system at a low level, an n-dimensional filter with a dynamic high gain is delicately devised instead of a2 n-dimensional one used in the relevant literature. It turns out that the proposed adaptive output-feedback controller is capable of guaranteeing the global boundedness of all states of the resulting closed-loop system,while steering the system tracking error to enter, in finite time, a prescribed λ-neighborhood of the origin and keeping it inside thereafter. A simulation example is provided to demonstrate the proposed approach.

关键词： nonlinear systems ISpS inverse dynamics unknown control direction practical output tracking global output feedback adaptive compensation

Tomography of the dynamic stress coefficient for stress wave prediction in sedimentary rock layer under the mining additional stress

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International Journal of Mining Science and Technology 2021年第4期31卷 653-663页

作者： Wenlong Shen Guocang Shi Yungang Wang Jianbiao Bai Ruifeng Zhang Xiangyu wang Henan Key Laboratory for Green and Efficient Mining&Comprehensive Utilization of Mineral Resources School of Energy Science and EngineeringHenan Polytechnic UniversityJiaozuo 454000China Key Laboratory of Deep Coal Resource Mining Ministry of Education State Key Laboratory of Coal Resources and Safe MiningChina University of Mining and TechnologyXuzhou 221116China Collaborative Innovation Center of Coal Work Safety and Clean High Efficiency Utilization Jiaozuo 454000China

In this study,the tomography of dynamic stress coefficient(TDSC)was established based on a mechanical model of stress wave propagation in bedding planes and a mathematical model of the stress wave attenuation in rock masses.The reliability of the TDSC was verified by a linear bedding plane model and field monitoring.Generally,the TDSC in the dynamic stress propagation of bedding planes increases with the following conditions:(1)the increase of the normal stiffness of the bedding plane,(2)the increase of the incident angle of the stress wave,(3)the decrease of the incident frequency of the stress wave,or(4)the growth of three ratios(the ratios of rock densities,elastic moduli,and the Poisson’s ratios)of rocks on either side of bedding planes.The additional stress weakens TDSC linearly and slowly during the stress wave propagation in bedding planes,and the weakening effect increases with the growth of the three ratios.Besides,the TDSC decreases exponentially in the rock mass as propagation distance increases.In a field case,the TDSC decreases significantly as vertical and horizontal distances increase and its wave range increases as vertical distance increases in the sedimentary rock layers.

关键词： Tomography of the dynamic stress coefficient Stress wave attenuation Mining additional stress Sedimentary rock layer

Underwater Target Detection Based on Reinforcement Learning and Ant Colony Optimization

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Journal of Ocean University of China 2022年第2期21卷 323-330页

作者： wang Xinhua ZHU yungang LI Dayu ZHANG Guang School of Computer Science Northeast Electric Power UniversityJilin 132012China Key Laboratory of Symbolic Computation and Knowledge Engineering of Ministry of Education College of Computer Science and TechnologyJilin UniversityChangchun 130012China State Key Laboratory of Applied Optics Changchun Institute of OpticsFine Mechanics and PhysicsChinese Academy of SciencesChangchun 130033China

Underwater optical imaging produces images with high resolution and abundant information and hence has outstanding advantages in short-distance underwater target detection.However,low-light and high-noise scenarios pose great challenges in un-derwater image and video analyses.To improve the accuracy and anti-noise performance of underwater target image edge detection,an underwater target edge detection method based on ant colony optimization and reinforcement learning is proposed in this paper.First,the reinforcement learning concept is integrated into artificial ants’movements,and a variable radius sensing strategy is pro-posed to calculate the transition probability of each pixel.These methods aim to avoid undetection and misdetection of some pixels in image edges.Second,a double-population ant colony strategy is proposed,where the search process takes into account global search and local search abilities.Experimental results show that the algorithm can effectively extract the contour information of underwater targets and keep the image texture well and also has ideal anti-interference performance.

关键词： ant colony optimization reinforcement learning underwater target edge detection

Global adaptive output-feedback tracking with prescribed performance for uncertain nonlinear systems

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Science China(Information Sciences) 2024年第5期67卷 150-164页

作者： Yuan wang yungang LIU School of Control Science and Engineering Shandong University

At present, one typical control strategy for guaranteeing transient and steady-state performance is funnel control and prescribed performance control. The strategy features completely discarding the system nonlinearities, even if they are completely known and available. Such an intrinsic feature requires the controller to produce a larger control effect to eliminate the negative impact caused by the high nonlinearities, leading to a conservative controller. In this paper, we fully take advantage of known information on nonlinearities in control design, instead of completely discarding it as done in funnel control. Particularly, we leverage adaptive techniques(i.e., high-gain dynamic compensation) to deal with unknown system nonlinearities. Meanwhile, we integrate the tools of output feedback, tracking control, and the performance guarantee.As such, an adaptive output-feedback scheme is developed for global tracking with spatiotemporal performance specifications: arbitrarily given tracking accuracy and accuracy-ensured time. A simulation example supports the developed approach.

关键词： uncertain nonlinear systems output feedback prescribed performance unknown control direction dynamic high gain global tracking

Characteristics of Hydrogen-rich Coals in Southern China:Implications from Organic Geochemistry and Carbon Isotopic Compositions

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Acta Geologica Sinica(English Edition) 2022年第1期96卷 309-320页

作者： LIN Yuhan wang Shaoqing YANG Zongda ZHAO yungang YANG Yi College of Geoscience and Surveying Engineering China University of Mining and Technology(Beijing)Beijing 100083China Wanbao Mining Ltd. Beijing 100053China

The organic geochemical characteristics of hydrogen-rich coal in southern China were investigated synthetically through organic geochemistry and carbon isotope analyses.The results showed that the hydrogen contents of the test samples were more than 5.0% and the H/C atomic ratios were between 0.76-1.06.Samples were found to be composed mostly of Type Ⅱ-Ⅲ℃ kerogen,consistent with good hydrocarbon-generation potential.The R_(o)(0.54-1.10%)and T_(max)(430-453℃)values imply that the hydrogen-rich coals were in low maturity to mature stages.Stable carbon isotopic ratios(δ^(13)C_(org))of the samples used varied from −24.5‰ to −23.4‰,the barkinite content ranging from 13.9% to 83.3%,indicating a predominantly terrestrial origin with marine influence during coal formation.Some organic geochemical parameters showed corresponding changes as the hydrogen content increased from 5.0% to 7.0%,however,the source inputs changed significantly when hydrogen content was greater than 6.0%.Terrestrial higher plants gradually become predominant within the coal-forming materials,whereas this dominant position is not apparent at lower hydrogen contents,which is attributable to the strong seawater effect during the hydrogen-rich coal formation process.

关键词： hydrogen-rich coal carbon isotope geochemistry Rock-Eval GC GC-MS

How Unique is ′China Model′: A Review of Theoretical Perspectives on China′s Urbanization in Anglophone Literature

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Chinese Geographical Science 2015年第1期25卷 98-112页

作者： wang Fenglong LIU yungang School of Geography Sciences and Planning Guangdong Key Laboratory for Urbanization and Geo-simulation Sun Yat-sen University Department of Geography Hong Kong Baptist University

As a major aspect of the ′China Model′, urbanization in China is being heatedly discussed in the Anglophone literature in the last two decades. By considering China′s urbanization as a ′testing ground′ of ′western′ theories, these studies are important for the understanding of China′s ongoing urban restructuring and exchanging knowledge with ′western′ insights. Based on a survey of existing studies, this paper identifies various endogenous and exogenous concepts and explanations of China′s urbanization. It is suggested that China′s urbanization is mainly driven by a combination of political decentralization and neoliberalization with various forms of social stratification and mobility. However, it is argued that the distinctness of the ′China Model′, which is usually used to support the legitimacy of studies of China′s urbanization, has led to many controversial arguments and diminished the due contributions of Chinese scholars in the knowledge production of China′s urbanization. To consolidate the legitimacy of studies on China′s urbanization and enhance the roles of Chinese scholars, we suggest future studies to pay more attentions to the fundamental theories with looser constraints and ′true questions′ on China′s urbanization.

关键词：中国模式城市化文献综述英语型号知识生产中国学者城市改造

Improved Qualitative Trajectory Calculus for Pair-Activity Analysis

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Journal of Beijing Institute of Technology 2019年第2期28卷 318-326页

作者： Shengsheng wang Guangyao wang yungang Zhu Jingwen Shao College of Computer Science and Technology Jilin University

Trajectory provides the most robust feature for activity recognition in far-field surveillance videos,in which increasing attentions have been given to the use of qualitative methods with symbolic rather than real-value features.Qualitative trajectory calculus(QTC)showed a good performance in pair-activity from video.However,QTC and similar works are not good at dealing with noise,since they are all considering short-term features.To deal with the problems mentioned above,two types of long-term features,including sub-trajectory feature and point-trajectory feature,are designed.The sub-trajectory feature is a long-term feature in a coarse granularity,while the point-trajectory feature is a long-term feature in a relatively fine granularity.Using the sub-trajectory feature,a couple of trajectories are segmented into sub-trajectories and enveloping boxes are used to substitute the original sub-trajectory for capturing the major attributes.The point-trajectory feature describes the relationship between a single point in one trajectory and all parts of the other trajectory.The experiments on the human activity classification data demonstrated that our proposed methods are better than the original QTC and previous short-term features.

关键词： pair-activity analysis qualitative trajectory calculus sub-trajectory feature point-trajectory feature

Exosomes released by granulocytic myeloid-derived suppressor cells attenuate DSS-induced colitis in mice

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Exosomes released by granulocytic myeloid-derived suppressor...

第十届全国免疫学学术大会

作者： Yungang Wang Shengjun wang

Myeloid-derived suppressor cells(MDSC)have been described in inflammatory bowel disease(IBD),but their role in the disease remains controversial.In this study,we sought to define the role of granulocytic MDSC-derived exosomes(G-MDSC exo)in dextran sulphate sodium(DSS)-induced murine colitis.G-MDSC exo-treated mice showed greater resistance to DSS-induced colitis,as reflected by slower disease activity index,decreased inflammatory cell infiltration,and less colon tissue damage.Meanwhile,there are a decrease in the number of Th1 cells and an increase in the number of Tregs in mesenteric lymph nodes from G-MDSC exo-treated colitis mice.Moreover,lower serum levels of interferon(IFN)-g and tumor necrosis factor(TNF)-αwere detected in G-MDSC exo-treated colitis mice.Interestingly,inhibition of arginase(Arg)-1 activity in G-MDSC exo partially abrogated the spontaneous improvement of colitis.In addition,GMDSC exo could suppress CD4+T cell proliferation and IFN-g secretion in vitro and inhibit the delayed-type hypersensitivity(DTH)response,and these abilities were associated with Arg-1 activity.Moreover,G-MDSC exo promoted Treg expansion in vitro.In conclusion,G-MDSC exo can attenuate DSS-induced colitis and inflammation,suggesting that they could be a potential therapy for IBD.

关键词： Inflammatory bowel disease Exosomes Myeloid-derived suppressor cells Inflammation

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中国政治地理学研究进展评述

地理学报 2022年第6期77卷 1506-1517页

作者：刘云刚王韬中山大学地理科学与规划学院广州510275 华南师范大学地理科学学院亚洲地理研究中心广州510631

当前世界正面临“百年未有之大变局”,在此背景下政治地理学的发展日益受到关注。得益于得天独厚的发展环境和旺盛的学科需求,政治地理学在中国近年再度复兴,在本土化概念创新、多源研究数据和方法拓展等方面取得一系列显见的成果。另... 详细信息

当前世界正面临“百年未有之大变局”,在此背景下政治地理学的发展日益受到关注。得益于得天独厚的发展环境和旺盛的学科需求,政治地理学在中国近年再度复兴,在本土化概念创新、多源研究数据和方法拓展等方面取得一系列显见的成果。另一方面,学科发展亟待跨越的一些“门槛”也日益显现,如共识核心概念缺乏、学科范式不统一、多尺度研究视角不足等,制约了其学术研究与政策应用的深入互动。在此背景下,本文基于对中国政治地理学发展动态的梳理,探讨了制约学科发展的若干基本问题,指出目前的当务之急是加强多/跨尺度研究、政策研究、区域研究,加强东西方思想交流,以此推动知识导向的批判性研究、实证主义的学术研究和实用主义的政策研究相辅相成的知识生产格局形成,从而构建起求真务实、经世致用的东方政治地理学特色,为全球治理和国家长治久安做出更大贡献。

关键词：政治地理学人文地理学多尺度全球治理中国