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Targets capture by distributed active swarms via bio-inspired reinforcement learning

Science China(Physics,Mechanics & Astronomy) 2025年第1期Mechanics & Astronomy) .卷 210-221页

作者： Kun Xu Yue Li Jun Sun Shuyuan Du Xinpeng Di Yuguang Yang Bo Li Institute of Biomechanics and Medical Engineering Applied Mechanics Laboratory Department of Engineering MechanicsTsinghua University Institute of Nuclear and New Energy Technology Tsinghua University Shanghai aerospace Control Technology Institute Shanghai Key Laboratory of aerospace Intelligent Control Technology College of Automation Engineering Nanjing University of Aeronautics and Astronautics

Natural swarms arranged from cells to herds are usually decentralized but display intriguing collective intelligence in coordinating individuals across large scales to efficiently achieve their common goals. Learning from nature may provide new strategies for controlling collective dynamics of synthetic swarms to accomplish specific functions. Here, we present a bioinspired computational framework that steers distributed active swarms to collectively capture and merge targets via reinforcement learning. We exploit collective milling structures of natural herds to cage the targets, and adopt a switching control policy inspired by sperms' chiral dynamics to optimize the trajectories of individuals, through which the active swarms can selforganize to enclose single or multiple distant targets in a dynamical, adaptive and scalable manner. There exists a critical swarm size, beyond which the excessive competition between agents would generate large mechanical forces, leading to capture instability but enabling the transition from short-distance to long-distance merging capture of multiple targets. This work provides physical insights into distributed active swarms and could offer a multilevel, decentralized strategy toward controlling swarm robotics in wide applications such as bio-medical devices, machine immunity, and target clearance.

关键词： swarm intelligence robotics multi-tasks artificial intelligence bionics

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Revealing and predicting the long-term biomechanical response of orthokeratology by developing a patient-specific computational model

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Science China(Physics,Mechanics & Astronomy) 2025年第1期Mechanics & Astronomy) .卷 156-168页

作者： Yifeng Li Zhuoran Yang Ziming Yan Huibin Shi Zhanli Liu Kaijie Wang department of Engineering Mechanics School of Aerospace Engineering Tsinghua University Beijing Tongren Eye Center Beijing Tongren Hospital Capital Medical University Beijing Ophthalmology & Visual Sciences Key Lab

Orthokeratology(OK) is widely used for effective myopia correction and control. However, the incomplete understanding of its biomechanical mechanisms makes OK lens fitting rely heavily on clinician judgment, complicating accurate predictions of treatment outcomes. In this paper, we performed clinical experiments and numerical analysis to study corneal deformation modes and long-term changes in central corneal thickness. Clinical experiments were conducted on 194 Chinese myopic patients under OK treatment for 3 months. Based on the experimental data, a patient-specific computational biomechanical model for OK was established and validated. Specifically, the anisotropic mechanical properties of the cornea were incorporated into the model to describe the significant difference between its shear modulus(29.5 kPa) and tensile modulus(768.4 kPa). Additionally, a viscohyperelastic material model with a prolonged corneal relaxation time of 5.6 h was developed to capture the long-term deformation response. The results show that corneal thickness reduction in OK is primarily due to out-of-plane shear deformation,influenced by the cornea's low shear resistance. Modeling the extended corneal relaxation time is crucial for predicting long-term biomechanical responses. The computational model effectively captures long-term changes in central corneal thickness, potentially improving OK lens fitting accuracy.

关键词： orthokeratology computational biomechanical model long-term viscoelasticity myopia correction

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A three-dimensional numerical study on the effect of geometric asymmetry on arcjet thruster performance

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Plasma Science and Technology 2023年第5期25卷 131-146页

作者： Hari Prasad NANDYALA Amit KUMAR Jayachandran THANKAPPAN department of aerospace engg Indian Institute of Technology Madras

In an arcjet thruster,the cathode and constrictor degrade with time,and the electrical arc discharge may become *** this work,a three-dimensional numerical model of a hydrogen plasma arcjet is developed and validated to study the effect of unsymmetrical electric arc discharge on thruster *** unsymmetrical arc discharge is realized by introducing a radial shift of the cathode so that the cathode tip offset is 80μm(25%of the constrictor radius).Simulations are conducted for both axially centered cathode(coaxial)and off-centered cathode(non-coaxial)configurations with identical propellant flow rates and input *** show asymmetrical arc discharge in the non-coaxial cathode configuration,resulting in azimuthally asymmetric Joule heating,species concentrations,and velocity *** asymmetry continues as the plasma expands in the divergent section of the ***,species concentrations,and axial velocity exhibit asymmetric radial distribution at the nozzle *** computed Joule heating was found to reduce with cathode shift,and consequently,the thrust and specific impulse of the thruster was decreased by about 6.6%.In the case of the non-coaxial cathode,geometric asymmetry also induces a small side thrust.

关键词： arcjet geometric asymmetry 3D numerical modelling space electric propulsion hydrogen

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Müller cells are activated in response to retinal outer nuclear layer degeneration in rats subjected to simulated weightlessness conditions

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Neural Regeneration Research 2025年第7期20卷 2116-2128页

作者： Yuxue Mu Ning Zhang Dongyu Wei Guoqing Yang Lilingxuan Yao Xinyue Xu Yang Li Junhui Xue Zuoming Zhang Tao Chen aerospace Clinical Medical Center School of Aerospace MedicineAir Force Medical UniversityXi’anShaanxi ProvinceChina department of Aviation Medicine Xijing HospitalAir Force Medical UniversityXi’anShaanxi ProvinceChina department of Emergency Medicine Wuhan No.1 HospitalWuhanHubei ProvinceChina Third Regiment School of Basic MedicineAir Force Medical UniversityXi’anShaanxi ProvinceChina Fourth Regiment School of Basic MedicineAir Force Medical UniversityXi’anShaanxi ProvinceChina

A microgravity environment has been shown to cause ocular damage and affect visual acuity,but the underlying mechanisms remain ***,we established an animal model of weightlessness via tail suspension to examine the pathological changes and molecular mechanisms of retinal damage under *** 4 weeks of tail suspension,there were no notable alterations in retinal function and morphology,while after 8 weeks of tail suspension,significant reductions in retinal function were observed,and the outer nuclear layer was thinner,with abundant apoptotic *** investigate the mechanism underlying the degenerative changes that occurred in the outer nuclear layer of the retina,proteomics was used to analyze differentially expressed proteins in rat retinas after 8 weeks of tail *** results showed that the expression levels of fibroblast growth factor 2(also known as basic fibroblast growth factor)and glial fibrillary acidic protein,which are closely related to Müller cell activation,were significantly *** addition,Müller cell regeneration and Müller cell gliosis were observed after 4 and 8 weeks,respectively,of simulated *** findings indicate that Müller cells play an important regulatory role in retinal outer nuclear layer degeneration during weightlessness.

关键词： glial fibrous acidic protein gliosis Müller cells nerve growth factor neural differentiation neurodegeneration proteomic retinal degeneration retinal outer nuclear layer simulated weightlessness

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Numerical simulation of hydrogen arcjet thruster with coupled sheath model

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Plasma Science and Technology 2022年第2期24卷 145-161页

作者： Deepak AKHARE Hari Prasad NANDYALA Jayachandran THANKAPPAN Amit KUMAR department of aerospace engg Indian Institute of Technology MadrasChennai 600036India

In the present work,a complete 2D chemical and thermal non-equilibrium numerical model coupled with a relatively simple sheath model is developed for hydrogen arcjet *** heat transfer in the anode wall is also included in the *** operating voltages predicted by the model are compared with those in the literature and are found to be in close *** distributions for the various operating conditions are obtained,anode radiation loss primarily determines the thruster *** thruster efficiency was found to be associated with longer arc *** cathode ion diffusion contribution dominates except at low input current where thermo-field electron current is dominant.

关键词： arcjet hydrogen numerical modeling plasma sheath space electric propulsion

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Metal-organic frameworks (MOFs) in aqueous batteries (ABs):unlocking potential through innovative materials design

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Science China Chemistry 2025年

作者： Bo Han Erhai Hu Bei-Er Jia Ziyang Liu Shuen Tso Afriyanti Sumboja Ivandini T.Anggraningrum Anne Zulfia Syahrial Qingyu Yan SCARCE Laboratory Energy Research Institute NTU (ERIN) Nanyang Technological University School of Materials Science and Engineering Nanyang Technological University Material Science and Engineering Research Group Faculty of Mechanical and Aerospace Engineering Institut Teknologi Bandung department of Chemistry University of Indonesia Metallurgical & Materials Engineering department Fakultas Teknik Universitas Indonesia

Metal-organic frameworks (MOFs) represent a revolutionary class of materials in the field of energy storage,particularly for aqueous batteries (ABs).Distinguished by their large surface area,tuneable porosity,and adaptable chemical activity,MOFs offer significant advantages over conventional materials in battery *** article provides a thorough analysis of the crucial role that MOFs play in improving the efficiency of *** includes a concise review of the current research progress,emphasizing the fundamental processes by which MOFs enhance electrochemical ***,the review examines the synthesis and design strategies for the structure of MOFs to maximize ion transport,improve conductivity,and enhance *** structural advantages,chemical versatility,stability,durability and functionalization potential of MOFs are comprehensively ***,we explore the distinct advantages of MOFs in overcoming common challenges encountered in ABs,such as declining capacity,inadequate cycling stability,and limited energy *** paper also highlights the future research directions needed to fully harness their *** goal is to develop a fundamental understanding and stimulate further progress in the use of MOFs for advanced energy storage solutions.

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Stochastic structural optimization using particle swarm optimization, surrogate models and Bayesian statistics

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Chinese Journal of Aeronautics 2013年第1期26卷 112-121页

作者： Jongbin Im Jungsun Park Korea aerospace Research Institute department of aerospace and Mechanical Engineering Korea Aerospace University

This paper focuses on a method to solve structural optimization problems using particle swarm optimization （PSO）, surrogate models and Bayesian statistics. PSO is a random/stochastic search algorithm designed to find the global optimum. However, PSO needs many evaluations compared to gradient-based optimization. This means PSO increases the analysis costs of structural optimization. One of the methods to reduce computing costs in stochastic optimization is to use approximation techniques. In this work, surrogate models are used, including the response surface method （RSM） and Kriging. When surrogate models are used, there are some errors between exact values and approximated values. These errors decrease the reliability of the optimum values and discard the realistic approximation of using surrogate models. In this paper, Bayesian statistics is used to obtain more reliable results. To verify and confirm the efficiency of the proposed method using surrogate models and Bayesian statistics for stochastic structural optimization, two numerical examples are optimized, and the optimization of a hub sleeve is demonstrated as a practical problem.

关键词： Bayesian statistics Kriging Particle swarm optimization (PSO) Response surface method (RSM)

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Flexible Strain Sensors with Ultra‑High Sensitivity and Wide Range Enabled by Crack‑Modulated Electrical Pathways

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Nano-Micro Letters 2025年第3期17卷 246-264页

作者： Yunzhao Bai Yunlei Zhou Xuanyu Wu Mengfei Yin Liting Yin Shiyuan Qu Fan Zhang Kan Li YongAn Huang State Key Laboratory of Intelligent Manufacturing Equipment and Technology Huazhong University of Science and TechnologyWuhan 430074People’s Republic of China Flexible Electronics Research Center Huazhong University of Science and TechnologyWuhan 430074People’s Republic of China Hangzhou Institute of Technology Xidian UniversityHangzhou 311200People’s Republic of China School of Mechano‑Electronic Engineering Xidian UniversityXi’an 710071People’s Republic of China department of aerospace and Mechanical Engineering University of Southern CaliforniaLos AngelesCA 90089USA

This study presents a breakthrough in flexible strain sensor technology with the development of an ultrahigh sensitivity and wide-range sensor,addressing the critical challenge of reconciling sensitivity with measurement *** by the structure of bamboo slips,we introduce a novel approach that utilises liquid metal to modulate the electrical pathways within a cracked platinum fabric *** resulting sensor demonstrates a gauge factor greater than 108 and a strain measurement capability exceeding 100%.The integration of patterned liquid metal enables customisable tuning of the sensor’s response,while the porous fabric structure ensures superior comfort and air permeability for the *** design not only optimises the sensor’s performance but also enhances the electrical stability that is essential for practical *** systematic investigation,we reveal the intrinsic mechanisms governing the sensor’s response,offering valuable insights for the design of wearable strain *** sensor’s exceptional performance across a spectrum of applications,from micro-strain to large-strain detection,highlights its potential for a wide range of real-world uses,demonstrating a significant advancement in the field of flexible electronics.

关键词： Flexible strain sensor Fabric Crack Response regulation Epidermal device

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Effect of Pressure Level on the Performance of an Auto-Initiated Pulsed Plasma Thruster

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Plasma Science and Technology 2010年第4期12卷 466-472页

作者： Kelvin LOH Abhijit KUSHARI department of aerospace Engineering Nanyang Technological University department of aerospace Engineering Indian Institute of Technology

Pulsed plasma thrusters （PPT） are micro-propulsion devices used in satellites for station keeping. Conventionally the plasma discharge in a PPT is initiated by a spark plug. The primary objective of the present work was to develop and characterize a PPT that does not need a spark plug to initiate the plasma discharge. If the spark plug is eliminated, the size of the thrusters can be reduced and arrays of such thrusters can be manufactured using micro electro mechanical systems （MEMS） techniques, which can provide tremendous control authority over the satellite positioning. A parallel rail thruster was built and its performances were characterized inside a vacuum chamber to elucidate the effect of vacuum level on the performance. The electrical performance of the thruster was quantified by measuring the voltage output from a Rogowski coil, and the thrust produced by the developed thruster was estimated by measuring the force exerted by the plume on a light weight pendulum, whose deflection was measured using a laser displacement sensor. It was observed that the thruster can operate without a spark plug. In general, the performance parameters such as thrust, mass ablation, impulse bit, and specific impulse per discharge, would increase with the increase in pressure up to an optimum level due to the increase in discharge energy as well as the decrease in the total impedance of the plasma discharge. The thrust efficiency is found to be affected by the discharge energy.

关键词： plasma thruster auto-initiation solid propellant micro-thruster

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Availability Analysis of Application Servers Using Software Rejuvenation and Virtualization

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Journal of Computer Science & Technology 2009年第2期24卷 339-346页

作者： Thandar Thein Jong Sou Park department Korea Aerospace University

Demands on software reliability and availability have increased tremendously due to the nature of present day applications. We focus on the aspect of software for the high availability of application servers since the unavailability of servers more often originates from software faults rather than hardware faults. The software rejuvenation technique has been widely used to avoid the occurrence of unplanned failures, mainly due to the phenomena of software aging or caused by transient failures. In this paper, first we present a new way of using the virtual machine based software rejuvenation named VMSR to offer high availability for application server systems. Second we model a single physical server which is used to host multiple virtual machines （VMs） with the VMSR framework using stochastic modeling and evaluate it through both numerical analysis and SHARPE （Symbolic Hierarchical Automated Reliability and Performance Evaluator） tool simulation. This VMSR model is very general and can capture application server characteristics, failure behavior, and performability measures. Our results demonstrate that VMSR approach is a practical way to ensure uninterrupted availability and to optimize performance for aging applications.

关键词： availability modeling software aging software rejuvenation virtual machine

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