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Carbon nanotubes and hexagonal boron nitride nanosheets co-filled ethylene propylene diene monomer composites: Improved electrical property for cable accessory applications

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HIGH VOLTAGE 2024年第3期9卷 546-555页

作者： zhang, Tiandong Xu, Huiduo Dai, Chuanxian zhang, Changhai zhang, Yongquan Chi, Qingguo Harbin Univ Sci & Technol Sch Elect & Elect Engn Harbin 150080 Peoples R China

Rubber-based composites based on ethylene propylene diene monomer (EPDM) with excellent non-linear electrical conductivity are preferred to serve as reinforced insulation in cable accessories, which can self-adaptively regulate electric field distribution and avoid electric field concentration due to the non-linear conductivity. The conductive carbon nanotubes (CNT) are filled into EPDM to improve the non-linear conductivity, while the insulating hexagonal boron nitride nanosheets (h-BN) are used to reconcile the electric breakdown strength. The results show that with the increase of CNT loading content, the non-linear conductivity of CNT/h-BN/EPDM composites becomes more prominent, accompanying the decrease of threshold field strength and increase of non-linear coefficient. However, the electric breakdown strength of CNT/h-BN/EPDM composites seriously deteriorates due to the increase of CNT content and temperature. By incorporating 10 wt.% h-BN into the composites, the reduction percentage of breakdown strength can be significantly lowered, which is 19.95% of neat EPDM and 13.74% of CNT/h-BN/EPDM composites at 70 & DEG;C, respectively. The COMSOL Multiphysics simulation results demonstrate that using the CNT/h-BN/EPDM composite as the reinforced insulation can eliminate the electric field concentration of the cable accessory as well as enable the cable accessory with good lightning shock resistance.

关键词： NONLINEAR CONDUCTIVITY

Elliptical encirclement control capable of reinforcing performances for UAVs around a dynamic target

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Defence Technology（防务技术） 2024年第2期32卷 104-119页

作者： Fei zhang Xingling Shao Yi Xia Wendong zhang National Key Laboratory for Electronic Measurement Technology School of Instrument and ElectronicsNorth University of ChinaTaiyuan030051China

Most researches associated with target encircling control are focused on moving along a circular orbit under an ideal environment free from external ***,elliptical encirclement with a time-varying observation radius,may permit a more flexible and high-efficacy enclosing solution,whilst the non-orthogonal property between axial and tangential speed components,non-ignorable environmental perturbations,and strict assignment requirements empower elliptical encircling control to be more challenging,and the relevant investigations are still *** this line,an appointed-time elliptical encircling control rule capable of reinforcing circumnavigation performances is developed to enable Unmanned Aerial Vehicles(UAVs)to move along a specified elliptical path within a predetermined reaching *** remarkable merits of the designed strategy are that the relative distance controlling error can be guaranteed to evolve within specified regions with a designer-specified convergence ***,wind perturbations can be online counteracted based on an unknown system dynamics estimator(USDE)with only one regulating parameter and high computational *** tool demonstrates that all involved error variables are ultimately limited,and simulations are implemented to confirm the usability of the suggested control algorithm.

关键词： Elliptical encirclement Reinforced performances Wind perturbations UAVs

Distributed dynamic task allocation for unmanned aerial vehicle swarm systems:A networked evolutionary game-theoretic approach

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Chinese Journal of Aeronautics 2024年第6期37卷 182-204页

作者： Zhe zhang Ju JIANG Haiyan XU Wen-An zhang College of Automation Engineering Nanjing University of Aeronautics and AstronauticsNanjing 211106China College of Economics and Management Nanjing University of Aeronautics and AstronauticsNanjing 211106China College of Information Engineering Zhejiang University of TechnologyHangzhou 310023China

Task allocation is a key aspect of Unmanned Aerial Vehicle(UAV)swarm collaborative *** an continuous increase of UAVs’scale and the complexity and uncertainty of tasks,existing methods have poor performance in computing efficiency,robustness,and realtime allocation,and there is a lack of theoretical analysis on the convergence and optimality of the *** paper presents a novel intelligent framework for distributed decision-making based on the evolutionary game theory to address task allocation for a UAV swarm system in uncertain scenarios.A task allocation model is designed with the local utility of an individual and the global utility of the ***,the paper analytically derives a potential function in the networked evolutionary potential game and proves that the optimal solution of the task allocation problem is a pure strategy Nash equilibrium of a finite strategy ***,a PayOff-based Time-Variant Log-linear Learning Algorithm(POTVLLA)is proposed,which includes a novel learning strategy based on payoffs for an individual and a time-dependent Boltzmann *** former aims to reduce the system’s computational burden and enhance the individual’s effectiveness,while the latter can ensure that the POTVLLA converges to the optimal Nash equilibrium with a probability of *** simulation results show that the approach is optimal,robust,scalable,and fast adaptable to environmental changes,even in some realistic situations where some UAVs or tasks are likely to be lost and increased,further validating the effectiveness and superiority of the proposed framework and algorithm.

关键词： Task allocation Unmanned Aerial Vehicles(UAV) Game theory Log-linear learning Distributed optimization algorithm

Distributed adaptive prescribed-time orbit containment control for satellite cluster flight

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Chinese Journal of Aeronautics 2024年第8期37卷 342-357页

作者： Tingting zhang Shijie zhang Huayi LI Xiangtian ZHAO Research Center of Satellite Technology Harbin Institute of TechnologyHarbin 150080China State Key Laboratory of Networking and Switching Technology Beijing University of Posts and TelecommunicationsBeijing 100876China

The distributed prescribed-time orbit containment control for the satellite cluster flight with multiple dynamic leaders is *** directed information communication topology between followers is taken into account in the overall *** the satellite mass is assumed to be constant,a distributed prescribed-time orbit containment controller is,firstly,presented to drive the followers into the dynamic convex hull produced by multiple ***,the parameter uncertainty is considered,and a prescribed-time sliding mode estimator is introduced to estimate the desired velocity of each *** on the estimated state,a novel distributed adaptive prescribed-time orbit containment control scheme is *** Lyapunov stability theory is utilized to prove the prescribed-time stability of the closed-loop ***,several numerical simulations and comparison of different control methods are provided to verify the effectiveness and superiority of the proposed control method.

关键词： Satellite cluster Orbit containment control Prescribed-time control Parameter uncertainty Directed communication graph

Coupled simulation of fluid-particle interaction for large complex granules:A resolved CFD-DEM method for modelling the airflow in a vertical fixed bed of irregular sinter particles

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Particuology 2024年第7期90卷 292-306页

作者： Chengzhi Li Yu zhang Jiahe Shen Wei zhang The State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and TechnologyWuhan 430081China Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education Wuhan University of Science and TechnologyWuhan 430081China School of Transportation and Logistics Engineering Wuhan University of TechnologyWuhan 430063China Centre for Bulk Solids and Particulate Technologies The University of NewcastleCallaghan NSW 2308Australia

A resolved CFD-DEM method is proposed to simulate the fluid-particle interaction for large complex *** airflow in a vertical sinter fixed bed is numerically studied using this *** multi-sphere clumped method is used to create irregular sinter particles in *** immersed boundary method and dynamic cell refinement are applied to describe the fluid flow around particles with higher resolution,by which the fluid-particle interaction can be simulated more *** simulation results presented the packing voidage distributions and the airflow fields in the sinter beds of different single and mixed particle size *** bed pressure drops were simulated and the results were compared with the corresponding experimental *** good agreement indicated that the proposed resolved CFD-DEM method is an effective tool to model the fluid-particle interaction for irregular large granules in the gas-solid multi-phase systems.

关键词： Resolved CFD-DEM method Irregular sinter particles Multi-sphere clumped method Immersed boundary method Dynamic cell refinement

Deep reinforcement learning based active surge control for aeroengine compressors

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Chinese Journal of Aeronautics 2024年第7期37卷 418-438页

作者： Xinglong zhang Zhonglin LIN Runmin JI Tianhong zhang College of Energy and Power Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China School of Mechanical Engineering and Automation Fuzhou UniversityFuzhou 350108China

This study proposes an active surge control method based on deep reinforcement learning to ensure the stability of compressors when adhering to the pressure rise command across the wide operating range of an ***,the study establishes the compressor dynamic model with uncertainties,disturbances,and Close-Coupled Valve(CCV)actuator *** upon this foundation,a Partially Observable Markov Decision Process(POMDP)is defined to facilitate active surge *** address the issue of unobservability,a nonlinear state observer is designed using a finite-time high-order sliding ***,an Improved Soft Actor-Critic(ISAC)algorithm is developed,incorporating prioritized experience replay and adaptive temperature parameter techniques,to strike a balance between exploration and convergence during *** addition,reasonable observation variables,error-segmented reward functions,and random initialization of model parameters are employed to enhance the robustness and generalization ***,to assess the effectiveness of the proposed method,numerical simulations are conducted,and it is compared with the fuzzy adaptive backstepping method and Second-Order Sliding Mode Control(SOSMC)*** simulation results demonstrate that the deep reinforcement learning based controller outperforms other methods in both tracking accuracy and ***,the proposed active surge controller can effectively ensure stable operation of compressors in the high-pressure-ratio and high-efficiency region.

关键词： Aeroengine surge Active surge control Moore-Greitzer model Deep reinforcement learning Soft actor-critic Nonlinear observer

Polystyrene microplastics disrupted physical barriers, microbiota composition and immune responses in the cecum of developmental Japanese quails

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Journal of Environmental Sciences 2024年第10期144卷 225-235页

作者： Lingyang Jing Yuxin zhang Qingyu zhang Hongfeng Zhao College of Life Sciences Shaanxi Normal UniversityXi’an 710119China

Microplastics,a new type of emerging pollutant,is ubiquitous in terrestrial and water *** have become a growing concern due to their impacts on the environment,animal,and human *** also suffer from microplastics *** this study,we examined the toxic effects of polystyrene microplastics(PS-MPs)exposure on physical barrier,microbial community,and immune function in the cecum of a model bird species—Japanese quail(Coturnix japonica).The one-week-old birds were fed on environmentally relevant concentrations of 20μg/kg,400μg/kg,and 8 mg/kg PS-MPs in the diet for 5 *** results showed that microplastics could cause microstructural damages characterized by lamina propria damage and epithelial cell vacuolation and ultrastructural injuries including microvilli breakage and disarrangement aswell asmitochondrial vacuolation in the cecum of *** particular,blurry tight junctions,wider desmosomes spacing,and gene expression alteration indicated cecal tight junction ***,mucous layer breakdown andmucin decrease indicated that chemical barrier was disturbed by ***-MPs also changed cecal microbial *** addition,structural deformation of cecal tonsils and increasing proinflammatory cytokines suggested cecal immune disorder and inflammation responses by PS-MPs *** results suggested that microplastics negatively affected digestive system and might pose great health risks to terrestrial birds.

关键词： Microplastics Gut barrier Histology Inflammation Immunity Oxidative stress

Multi-circular formation control with reinforced transient profiles for nonholonomic vehicles:A path-following framework

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Defence Technology（防务技术） 2024年第1期31卷 278-287页

作者： Jintao zhang Xingling Shao Wendong zhang Zongyu Zuo School of Instrument and Electronics North University of ChinaTaiyuan 030051China State Key Laboratory of Dynamic Measurement Technology North University of ChinaTaiyuan 030051China Seventh Research Division School of Automation Science and Electrical EngineeringBeihang UniversityBeijing 100191China

This article investigates a multi-circular path-following formation control with reinforced transient profiles for nonholonomic vehicles connected by a digraph.A multi-circular formation controller endowed with the feature of spatial-temporal decoupling is devised for a group of vehicles guided by a virtual leader evolving along an implicit path,which allows for a circumnavigation on multiple circles with an anticipant angular *** addition,notice that it typically imposes a stringent time constraint on time-sensitive enclosing scenarios,hence an improved prescribed performance control(IPPC)using novel tighter behavior boundaries is presented to enhance transient capabilities with an ensured appointed-time convergence free from any *** significant merits are that coordinated circumnavigation along different circles can be realized via executing geometric and dynamic assignments independently with modified transient ***,all variables existing in the entire system are analyzed to be *** and experimental results are provided to validate the utility of suggested solution.

关键词： Multi-circular formation Reinforced transient profiles Nonholonomic vehicles Path following

Accumulated-state-error-based event-triggered sampling scheme and its application to H∞ control of sampled-data systems

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Science China(Information Sciences) 2024年第6期67卷 328-341页

作者： Xian-Ming zhang Qing-Long HAN Bao-Lin zhang Xiaohua GE Dawei zhang School of Science Computingand Engineering TechnologiesSwinburne University of Technology College of Automation and Electronic Engineering Qingdao University of Science & Technology School of Mathematics Shandong University

This paper is concerned with event-triggered H∞control of sampled-data systems. Its novelties lie in three aspects:（i） A novel accumulated-state-error-based event-triggered scheme is introduced by comparing the integral of the state error from tk to t with the system state sampled at tk. This condition works well due to the fact that the so-called Zeno behaviour does not occur.（ii） A novel Lyapunov functional is constructed to establish a criterion to ensure some certain H∞performance of the closed-loop system. This Lyapunov functional is dependent on the integral of the state error involved in the event-triggered scheme.（iii） Under the event-triggered sampling scheme, suitable state-feedback controllers can be designed rather than be given a priori. Moreover, a self-triggered implementation of the proposed event-triggered sampling scheme is presented as well. Finally, a batch reactor model and an inverted pendulum system are given to demonstrate the effectiveness of the proposed method.

关键词： event-triggered sampling self-triggered implementation $H_\infty$ control looped-functional