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Control Theory and Technology 2023年第3期21卷 414-424页

作者： Xinfei Wu Xiao Yu Weiyao Lan Department of Automation Xiamen UniversityXiamen 361005FujianChina Key Laboratory of Control and Navigation(Xiamen University) Fujian Province UniversityXiamen 361005FujianChina

This paper investigates the cooperative output regulation problem of linear multi-agent systems with a linear exogenous system(exo-system).The network topology is described by a directed graph which contains a directed spanning tree with the exo-system as the root.Aiming at improving the transient performance of the multi-agent systems,a dynamic control law is developed by the composite nonlinear feedback(CNF)control technique.In particular,a distributed dynamic compensator independent of the interaction on the compensator states of agents among the network,is adopted.The solvability condition for the cooperative output regulation problem is obtained using the small-gain theory,which will not be destroyed by adding the nonlinear feedback part of the CNF control law.It is also shown that in the case with the exo-system not diverging exponentially,the small-gain condition can be guaranteed using the low-gain design.Finally,simulation results illustrate that the proposed CNF control law improves the transient performance for the cooperative output regulation of linear multi-agent systems.

关键词： Cooperative output regulation-Distributed dynamic compensator Composite nonlinear feedback Small-gain condition

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中国应急语言研究二十年回顾与展望

语言战略研究 2022年第2期7卷 62-73页

作者：肖俊敏张瑜华中师范大学文学院湖北武汉430079

以新冠疫情暴发为分水岭,中国的应急语言研究可分为两个阶段。第一阶段,应急语言实践积累了一定经验,相关理论探索平缓起步,政策规划逐渐重视,但应用研究相对滞后,应急语言尚未形成独立的研究领域。第二阶段,应急语言研究成果井喷式涌现... 详细信息

以新冠疫情暴发为分水岭,中国的应急语言研究可分为两个阶段。第一阶段,应急语言实践积累了一定经验,相关理论探索平缓起步,政策规划逐渐重视,但应用研究相对滞后,应急语言尚未形成独立的研究领域。第二阶段,应急语言研究成果井喷式涌现,“应急语言”概念的内涵表述日臻完善,理论视角进一步丰富,应用研究在总结国外应急语言实践,厘清相关术语,探讨应急语言产品研发、应急语言技术革新、应急语言服务团建设、应急语言人才培养、应急话语分析等方面全面开花。宏观思辨和个案研究成为最常见的研究范式。但当前研究在理论视角、研究范式、覆盖领域等方面仍存在不足,应不断丰富应急语言研究的视角和主题,深耕应急语言分支领域,实现研究范式上的宏观思辨与微观实证互补。

关键词：中国应急语言研究应急管理语言服务回顾与展望

Pt–C interactions in carbon-supported Pt-based electrocatalysts

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Frontiers of Chemical Science and Engineering 2023年第11期17卷 1677-1697页

作者： yu-Xuan xiao Jie Ying Hong-Wei Liu xiao-yu Yang School of Chemical Engineering and Technology Sun Yat-sen UniversityZhuhai 519082China State Key Laboratory of Advanced Technology for Materials Synthesis and Processing&Shenzhen Research Institute&Joint Laboratory for Marine Advanced Materials in Pilot National Laboratory for Marine Science and Technology(Qingdao) Wuhan University of TechnologyWuhan 430070China

Carbon-supported Pt-based materials are highly promising electrocatalysts.The carbon support plays an important role in the Pt-based catalysts by remarkably influencing the growth,particle size,morphology,dispersion,electronic structure,physiochemical property and function of Pt.This review summarizes recent progress made in the development of carbon-supported Pt-based catalysts,with special emphasis being given to how activity and stability enhancements are related to Pt–C interactions in various carbon supports,including porous carbon,heteroatom doped carbon,carbon-based binary support,and their corresponding electrocatalytic applications.Finally,the current challenges and future prospects in the development of carbon-supported Pt-based catalysts are discussed.

关键词： Pt-C interactions Pt-based materials carbon support electrocatalysis

Research on head way control of a guided transport system based on intersection condition evaluation

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Transportation Safety and Environment 2023年第4期5卷 29-35页

作者： Xiao Yu yuan Cao Yongkui Sun Signal and Communication Research Institute China Academy of Railway Sciences Corporation LimitedBeijing 100081China State Key Laboratory of Rail Traffic Control and Safety Beijing Jiaotong UniversityBeijing 100044China National Engineering Research Center of Rail Transportation Operation and Control System Beijing Jiaotong UniversityBeijing 100044China

ln order to ensure the safety and efficiency of the section tracking operation of a guided transport system,a safety headway control method of section tracking based on intersection conditions is proposed in this paper.Considering the difference of signal phase,the evaluation model of road conditions was established based on a fuzzy comprehensive evaluation method,FAGT.Based on the artificial potential field method,the time-varying hybrid artificial potential field(TH-APF)method was proposed,and the tracking headway control algorithm was designed to realize the dynamic control of the tracking headway of the guide transport vehicle.The simulation results verified the effectiveness and applicability of the evaluation model of intersection road conditions;the tracking headway can be maintained at about 120 s.The tracking headway control algorithm of guided transport vehicles can respond to the road conditions and avoid the local optimum of the artificial potential field method,thus improving the operating efficiency.

关键词： guided transport system intersection condition evaluation artificial potential field method tracking headway control

Data-driven cooperative optimal output regulation for linear discrete-time multi-agent systems by online distributed adaptive internal model approach

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Science China(Information Sciences) 2023年第7期66卷 30-45页

作者： Kedi XIE Yi JIANG Xiao Yu Weiyao LAN Department of Automation Xiamen University Department of Electrical Engineering City University of Hong Kong Key Laboratory of Control and Navigation(Xiamen University) Fujian Province University

In this study, a data-driven learning algorithm was developed to estimate the optimal distributed cooperative control policy, which solves the cooperative optimal output regulation problem for linear discretetime multi-agent systems. Notably, the dynamics of all the agent systems and exo-system is completely unknown. By combining adaptive dynamic programming with an internal model, a model-free off-policy learning method is proposed to estimate the optimal control gain and the distributed adaptive internal model by only accessing the measurable data of multi-agent systems. Moreover, different from the traditional cooperative adaptive controller design method, a distributed internal model is approximated online. Convergence and stability analyses show that the estimate controller generated by the proposed data-driven learning algorithm converges to the optimal distributed controller. Finally, simulation results verify the effectiveness of the proposed method.

关键词： adaptive dynamic programming cooperative control distributed adaptive internal model multi-agent systems optimal output regulation

Effects of tetrakis (hydroxymethyl) phosphonium sulfate pretreatment on characteristics of sewage sludge

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Journal of Environmental Sciences 2019年第4期31卷 174-182页

作者： yunping Han Wenzhe Zhang Xiao Yu Panfen yu Benyi xiao Hao Yi Research Center for Eco-Environmental Sciences Chinese Academy of Sciences University of Chinese Academy of Sciences College of Textiles and Clothing Qingdao University South China Institute of Environmental Sciences Ministry of Environmental Protection

Recently, tetrakis(hydroxymethyl)phosphonium sulfate(THPS) was found to play an important role in the sludge pretreatment process. However, the effects of THPS pretreatment on the characteristics of sewage sludge are still insufficiently understood.The properties of sludge after pretreatment with different concentrations of THPS were investigated in this study. The results showed that pH, dewatering ability, and particle size of sludge decreased with increase in THPS concentration. The volatile suspended solids(VSS) and total suspended solids(TSS) of sludge also decreased slightly with increase in THPS concentration. The specific oxygen uptake rate(SOUR) results suggested that lower THPS concentrations(≤ 1.87 mg/g VSS) enhanced the activity of sludge, but higher concentrations(≥ 1.87 mg/g VSS) inhibited it. Gram-negative bacteria with peritrichous flagellation(such as Pseudomonas, Escherichia, and Faecalibacterium) were extremely sensitive to THPS. The decrease in specific most probable numbers(MPNs) of pathogens(total coliforms and Escherichia coli) with the increase in THPS concentration also proved the sterilization ability of THPS in the sludge pretreatment process. Pretreatment of sludge with concentrations of THPS higher than 37.41 mg/g VSS would meet the pathogen requirements for land application of Class A biosolids.

关键词： Sewage sludge Tetrakis(hydroxymerhyl) phosphonium sulfate Physicochemical properties Microbial community Pathogens

Numerical study on the case effect of a bomb air explosion

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Defence Technology（防务技术） 2021年第4期17卷 1461-1470页

作者： Guo-qiang Deng Xiao Yu Institute of Defense Engineering AMSPLABeijing100850China

When considering the bomb explosion damage effect,the air shock wave and high-speed fragments of the bomb case are two major threats.In experiments,the air shock wave was studied by the bare explosives superseding the real cased bomb;in contrast,the bomb case influence was ignored to reduce risk.The air explosion simulations of the MK84 warhead with and without the case were conducted.The numerical simulation results showed that the bomb case significantly influenced the shock wave generated by the bomb:the spatial distribution of shock wave in the near field changed,and the peak value of shock wave was reduced.Breakage of the case and kinetic energy of the fragmentation consumed 3 and 38% of the explosion energy,respectively.The increasing factors of the peak overpressure induced by the bare explosive on the ground and in the air were 1.43-3.04 and 1.37-1.57,respectively.Four typical stages of case breakage were defined.The mass distribution of the fragments follows the Mott distribution.The initial velocity distribution of the fragments agreed well with the Gurney equation.

关键词： Explosion Cased bomb Bare explosive Numerical simulation MK84

Early-Awareness Collision Avoidance in Optimal Multi-Agent Path Planning With Temporal Logic Specifications

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IEEE/CAA Journal of Automatica Sinica 2023年第5期10卷 1346-1348页

作者： Yiwei Zheng Aiwen Lai Xiao Yu Weiyao Lan the Department of Automation Xiamen UniversityXiamen 361005 the Key Laboratory of Control and Navigation(Xiamen University) Fujian Province UniversityXiamen 361005China the Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province(IKKEM) Xiamen 361005China

Dear Editor,This letter investigates a multi-agent path planning problem in a road network with the requirement of avoiding collisions among all agents in the partitioned environment.We first abstract the agents to a set of transition systems,and construct a team transition system from these individual systems.A mechanism is designed for the team transition system to detect all collisions within the synthesized run.

关键词： agent Temporal individual

Improve Robustness and Accuracy of Deep Neural Network with L_(2,∞) Normalization

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Journal of Systems Science & Complexity 2023年第1期36卷 3-28页

作者： yu Lijia GAO xiao-Shan Academy of Mathematics and Systems Science Chinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China

In this paper,the L_(2,∞)normalization of the weight matrices is used to enhance the robustness and accuracy of the deep neural network(DNN)with Relu as activation functions.It is shown that the L_(2,∞)normalization leads to large dihedral angles between two adjacent faces of the DNN function graph and hence smoother DNN functions,which reduces over-fitting of the DNN.A global measure is proposed for the robustness of a classification DNN,which is the average radius of the maximal robust spheres with the training samples as centers.A lower bound for the robustness measure in terms of the L_(2,∞)norm is given.Finally,an upper bound for the Rademacher complexity of DNNs with L_(2,∞)normalization is given.An algorithm is given to train DNNs with the L_(2,∞)normalization and numerical experimental results are used to show that the L_(2,∞)normalization is effective in terms of improving the robustness and accuracy.

关键词： Deep neural network global robustness measure L_(2,∞)normalization over-fitting Rademacher complexity smooth DNN

A novel multi-level model for quasi-brittle cracking analysis with complex microstructure

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2022年第2期23卷 118-139页

作者： xiao-xiao SUN Xiang-yu CHEN xiao-ming GUO Jiangsu Key Laboratory of Engineering Mechanics Department of Engineering MechanicsSoutheast UniversityNanjing 210096China School of Civil Engineering Southeast UniversityNanjing 210096China

The paper presents a novel multi-level model for quasi-brittle cracking analysis.Based on the partition of unity and information transmission technology,it provides a new non-re-meshing way to describe the cracking phenomenon in structures constructed from materials with complex microstructures.In the global model,the concept of the material particle is defined and the basic unknowns are the boundary displacements of these particles,which is different from the concept of the traditional displacement field.A series of enrichment functions with continuous steps is proposed,describing the boundary displacement affected by crack bands and allowing the intersections of crack bands with particle boundaries a priori unknown.Simultaneously,additional equations are introduced to determine element status and make the degrees of freedom of the global model remain at a stable level.Compared with previous research by our group,where the local description is equal to the global description on the boundary of a material particle,the introduced enrichment functions enable more accurate capture of the characteristics of the crack band.The model avoids the complex and dynamic model adjustments due to the activation and exit of representative volume elements(RVEs)and the accuracy of the description of the crack pattern can be ensured.The RVEs are activated at first,but then many of them exit the computation due to the unloading which reduces many of the degrees of freedom.Two examples of concrete specimens are analyzed,and the concrete fracture experiment and the digital image correlation(DIC)test are conducted.Compared with the reference solutions and the experimental data,even though the microstructure of concrete is very complex,the cracking process and crack pattern can be obtained accurately.

关键词： Multi-level model Concrete Enrichment function Quasi-brittle cracking Damage evolution Digital image correlation(DIC)test