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A transfer learning enhanced physics-informed neural network for parameter identification in soft materials

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Applied Mathematics and Mechanics(English Edition) 2024年第10期45卷 1685-1704页

作者： Jing'ang ZHU Yiheng XUE Zishun LIU International Center for Applied Mechanics State Key Laboratory for Strength and Vibration of Mechanical Structures School of Aerospace EngineeringXi'an Jiaotong University

Soft materials, with the sensitivity to various external stimuli, exhibit high flexibility and stretchability. Accurate prediction of their mechanical behaviors requires advanced hyperelastic constitutive models incorporating multiple parameters. However,identifying multiple parameters under complex deformations remains a challenge, especially with limited observed data. In this study, we develop a physics-informed neural network(PINN) framework to identify material parameters and predict mechanical fields,focusing on compressible Neo-Hookean materials and hydrogels. To improve accuracy, we utilize scaling techniques to normalize network outputs and material parameters. This framework effectively solves forward and inverse problems, extrapolating continuous mechanical fields from sparse boundary data and identifying unknown mechanical *** explore different approaches for imposing boundary conditions(BCs) to assess their impacts on accuracy. To enhance efficiency and generalization, we propose a transfer learning enhanced PINN(TL-PINN), allowing pre-trained networks to quickly adapt to new scenarios. The TL-PINN significantly reduces computational costs while maintaining accuracy. This work holds promise in addressing practical challenges in soft material science, and provides insights into soft material mechanics with state-of-the-art experimental methods.

关键词： 35Q74 74A20 74B20 74G75 inverse problem O242 O343 parameter identification physics-informed neural network (PINN) soft material transfer learning

First record of abnormal body coloration in a rockfish Sebastes koreanus(Scorpaenoidei:Sebastidae)from coastal water of China based on morphological characteristics and DNA barcoding

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Journal of Oceanology and Limnology 2024年第2期42卷 640-646页

作者： ang LI Huan Wang Changting AN Shufang LIU Yellow Sea Fisheries Research Institute Chinese Academy of Fishery SciencesQingdao 266071China Laboratory for Marine Fisheries Science and Food Production Processes Laoshan LaboratoryQingdao 266071China

The first record of abnormal body coloration in Sebastes koreanus Kim and Lee,1994,from the Yellow Sea of China,was documented based on morphological characteristics and DNA *** two rockfish specimens were collected from the coastal waters of Qingdao,China,and the whole body and all fins of them were *** the two red-colored rockfish,there were tiny deep red spots on each fin,2 red radial stripes behind and below the eyes and 1 large deep red blotch on the opercula,while the similar stripe and spot patterns are also present in the *** specimens with normal body *** countable characteristics of the two specimens are in the range of the morphometry of *** further clarify the species identity and taxonomic status of the two specimens,DNA barcode analysis was carried *** genetic distance between the red-colored rockfish and *** was 0,and the minimum net genetic distances between the red-colored rockfish and other Sebastes species except for *** were 3.0%,which exceeds the threshold of species *** phylogenetic analysis showed that the DNA barcoding sequences of the two red-colored rockfish clustered with the *** *** above results of DNA barcode analysis also support that the two red-colored rockfish could be identified as the species of *** mechanism of color variation in *** is desirable for further research and the species could be an ideal model to study the color-driven speciation of the rockfishes.

关键词： abnormal body coloration Sebastes koreanus coastal water of China Yellow Sea morphological characteristics DNA barcoding

Influence of laser parameters on the microstructures and surface properties in laser surface modification of biomedical magnesium alloys

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Journal of Magnesium and Alloys 2024年第1期12卷 72-97页

作者： Chee Ying Tan Cuie Wen Hua Qian ang School of Engineering RMIT UniversityMelbourneVictoria 3001Australia

Biodegradable implants from magnesium(Mg)alloys have emerged in the biomedical field especially in the orthopedic and cardiovascular stent applications owing to their low density,high specific strength,excellent machinability,good biocompatibility,and *** primary shortcoming of Mg-based implants is their low corrosion resistance in the physiological environment,which results in premature mechanical integrity loss before adequate healing and the production of excessive hydrogen gas,which is harmful to the body tissues and negatively affects the biocompatibility of the *** surface modification has recently received attention because it can improve the surface properties such as surface chemistry,roughness,topography,corrosion resistance,wear resistance,hydrophilicity,and thus cell response to the surface of the *** composition and microstructures including textures and phases of laser-treated surfaces depend largely on the laser processing parameters(input laser power,laser scan velocity,frequency,pulse duration,pressure,gas circulation,working time,spot size,beam focal position,and laser track overlap)and the thermophysical properties of the substrate(solubility,melting point,and boiling point).This review investigates the impacts of various laser surface modification techniques including laser surface melting,laser surface alloying,laser cladding,laser surface texturing,and laser shock peening,and highlights their significance in improving the surface properties of biodegradable Mg alloys for implant ***,we explore how different laser process parameters affect its composition,microstructure,and surface properties in each laser surface modification technique.

关键词： Biocompatibility Biodegradability Corrosion Implant applications Laser surface modification Magnesium alloys

Secure state estimation for cyber-physical systems with unknown input sliding mode observer

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Control Theory and Technology 2024年第2期22卷 244-253页

作者： Panpan Zhang Yuwei Ren Yixian Fang ang Liu School of Information Science and Engineering Shandong Normal UniversityJinan250358ShandongChina School of Information Engineering Shandong Management UniversityJinan250357ShandongChina

In recent years, cyber attacks have posed great challenges to the development of cyber-physical systems. It is of great significance to study secure state estimation methods to ensure the safe and stable operation of the system. This paper proposes a secure state estimation for multi-input and multi-output continuous-time linear cyber-physical systems with sparse actuator and sensor attacks. First, for sparse sensor attacks, we propose an adaptive switching mechanism to mitigate the impact of sparse sensor attacks by filtering out their attack modes. Second, an unknown input sliding mode observer is designed to not only observe the system states, sensor attack signals, and measurement noise present in the system but also counteract the effects of sparse actuator attacks through an unknown input matrix. Finally, for the design of an unknown input sliding mode state observer, the feasibility of the observing system is demonstrated by means of Lyapunov functions. Additionally, simulation experiments are conducted to show the effectiveness of this method.

关键词： Sparse attacks Cyber-physical systems Unknown input sliding mode Secure state estimation Adaptive switching mechanism

Recent Advances in In-Memory Computing:Exploring Memristor and Memtransistor Arrays with 2D Materials

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Nano-Micro Letters 2024年第7期16卷 1-30页

作者： Hangbo Zhou Sifan Li Kah-Wee ang Yong-Wei Zhang Institute of High Performance Computing(IHPC) Agency for ScienceTechnology and Research(A*STAR)1 Fusionopolis Way#16-16 ConnexisSingapore 138632Republic of Singapore Department of Electrical and Computer Engineering National University of Singapore4 Engineering Drive 3Singapore 117583Republic of Singapore Institute of Materials Research and Engineering Agency for ScienceTechnology and Research(A*STAR)2 Fusionopolis WaySingapore 138634Republic of Singapore

The conventional computing architecture faces substantial chal-lenges,including high latency and energy consumption between memory and processing *** response,in-memory computing has emerged as a promising alternative architecture,enabling computing operations within memory arrays to overcome these *** devices have gained significant attention as key components for in-memory computing due to their high-density arrays,rapid response times,and ability to emulate biological *** these devices,two-dimensional(2D)material-based memristor and memtransistor arrays have emerged as particularly promising candidates for next-generation in-memory computing,thanks to their exceptional performance driven by the unique properties of 2D materials,such as layered structures,mechanical flexibility,and the capability to form *** review delves into the state-of-the-art research on 2D material-based memristive arrays,encompassing critical aspects such as material selection,device perfor-mance metrics,array structures,and potential ***,it provides a comprehensive overview of the current challenges and limitations associated with these arrays,along with potential *** primary objective of this review is to serve as a significant milestone in realizing next-generation in-memory computing utilizing 2D materials and bridge the gap from single-device characterization to array-level and system-level implementations of neuromorphic computing,leveraging the potential of 2D material-based memristive devices.

关键词： 2D materials Memristors Memtransistors Crossbar array In-memory computing

Experimental Study on the Effect of Increased Downstroke Duration for an FWAV with Morphing-coupled Wing Flapping Configuration

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Journal of Bionic Engineering 2024年第1期21卷 192-208页

作者： ang Chen Bifeng Song ZhiheWang Kang Liu Dong Xue Xiaojun Yang School of Aeronautics Northwestern Polytechnical UniversityXi'an 710072China Harbin Institute of Technology Shenzhen 518055China

This paper is based on a previously developed bio-inspired Flapping Wing Aerial Vehicle(FWAV),RoboFalcon,which can fly with a morphing-coupled flapping *** this paper,a simple flapping stroke control system based on Hall effect sensors is designed and applied,which is capable of assigning different up-and down-stroke speeds for the RoboFalcon platform to achieve an adjustable downstroke *** aerodynamic and power characteristics of the morphing-coupled flapping pattern and the conventional flapping pattern with varying downstroke ratios are measured through a wind tunnel experiment,and the corresponding aerodynamic models are developed and analyzed by the nonlinear least squares *** relatively low power consumption of the slow-downstroke mode of this vehicle is verified through outdoor flight *** results of wind tunnel experiments and flight tests indicate that increased downstroke duration can improve aerodynamic and power performance for the RoboFalcon platform.

关键词： Flapping wing aerial vehicle(FWAV) Downstroke ratio Bio-inspired design Morphing-coupled flapping

Status and trends of carbon emissions research at the county level in China

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Advances in Climate Change Research 2024年第2期15卷 338-352页

作者： ang-Zu CAI Ru GUO Yu-Hao ZHang Jiang WU College of Environmental Science and Engineering Institute of Environmental Planning and ManagementTongji UniversityShanghai 200092China Institute of Carbon Neutrality Tongji UniversityShanghai 200092China Shanghai Institute of Pollution Control and Ecological Security Shanghai 200092China College of Architecture and Urban Planning Tongji UniversityShanghai 200092China Megacity Elaborated Urban Governance Institute Tongji UniversityShanghai 200092China

This study provides a comprehensive overview of the challenges to achieving carbon neutrality at the county level in China and offers targeted recommendations,laying the groundwork for future specialized research in this area.A total of 283 relevant studies(2004-2023)were analyzed to assess county-level carbon emissions through three phases:bibliometric analysis,frontier analysis,and future *** findings reveal that publication trends were largely influenced by domestic and foreign *** cluster discerns ten primary themes,ranging from conceptual frameworks to research *** frontier analysis of the literature highlights the leading research areas,which include carbon neutrality pathway,driving factors,spatiotemporal variation of carbon emissions,the co-effects of pollutants and carbon reduction,and carbon emissions in China's rural *** from the results of bibliometric and frontier analyses,this study elucidates the recommendations for achieving carbon neutrality at the county level from three perspectives:effective regional policy guidance,emphasis on ecological conservation,and the deployment of advanced carbon reduction and sequestration *** study enriches the body of knowledge on carbon emissions at the county level and holds significant implications for China's comprehensive push towards achieving its carbon neutrality objectives.

关键词： Carbon emissions Emission reduction County Carbon neutrality Sustainability

Effects of dynamical spanwise retraction and stretch on flapping-wing forward flights

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Chinese Journal of Aeronautics 2024年第4期37卷 181-202页

作者： Kang LIU Bifeng SONG ang CHEN Zhihe Wang Dong XUE Wenqing Yang School of Aeronautics Northwestern Polytechnical UniversityXi’an 710072China Intelligent Aircraft Research Center Chengdu Technological UniversityChengdu 610031China Research&Development Institute of Northwestern Polytechnical University in Shenzhen Shenzhen 518057China Harbin Institute of Technology Shenzhen 518055China

Birds and bats retract and stretch their wings dynamically during each flap in level flights, implying intriguing mechanisms for the aerodynamic performance improvement of flapping wings. A numerical investigation into the aerodynamic effects of such bio-inspired concept in forward flights has been performed based on a three-dimensional wing in plunging motion and a twosection wing in flapping motion. The currently considered Reynolds number and Strouhal number are Re=1.5×10^(5) and St=0.3, respectively. During the research, the mean angle of attack is varied in relatively wide ranges to achieve lift-thrust interconversion for the wings. The conclusive results show that dynamical spanwise retraction and stretch has induced three absolutely desirable scenarios for the oscillating wings in forward flights, namely producing more lift and consuming less power for a given thrust generation, producing more thrust and consuming less power for a given lift generation, and producing more lift and more thrust while consuming less power. Furthermore,the morphing wings have alleviated periodical aerodynamic load fluctuations compared with the non-morphing baseline. The mechanism of the aerodynamic effects of the bionic morphing mode is analyzed with the aid of field visualization. The current article is the first to reveal the absolute advantages of the bionic spanwise morphing. Hopefully, it may help comprehend the behaviors of natural fliers and provide inspirations for performance enhancement of micro artificial flappingwing vehicles.

关键词： Flapping wing Morphing wing Bionic Aerodynamics Vortex Flight

Lightweight and high-security laser-based cotton tip pruning robot

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International Journal of Agricultural and Biological Engineering 2024年第4期17卷 98-108页

作者： Xuan'ang Guo Ziyang Mao Zedong Shi Wei Lu School of Artificial Intelligence Nanjing Agricultural UniversityNanjing 210031China

Considering the current environmental pollution caused by chemical topping,plant damage caused by mechanical topping,and the high cost of manual topping,a laser-based cotton-tip pruning robot for field cotton was designed in this *** main advantages of this robot include its safety,light weight,low cost,and environmental ***,the structural design,measurement,and corresponding control system design of the robot were ***,a precise laser control method based on Yolov5 cotton top identification and the inverse kinematic solution of parallel robot rapid positioning were ***,the optimal laser irradiation wavelength and duration were ***,a laser-topping experiment was conducted,and the overall accuracy and recall rates for cotton identification were 98.3%and 99.3%,*** AP and mAP at the threshold value of 0.5 reached 99.3%and 78.8%,*** maximum positioning error of the jacking system is 2.6 mm,and the repeated positioning error is within±1.2 cm,which meets the accuracy requirements of laser ***-purple laser irradiation at 15 W and 405 nm for 22 s was the best topping *** the effects of cotton topping with and without manual topping,it can be seen that laser topping significantly improved the yield and *** with the photothermal response of the cotton topping,the feasibility of laser topping was verified both theoretically and *** laser-topping scheme proposed in this study exhibits high efficiency,environmental protection,and safety,as well as good application prospects.

关键词： laser topping parallel manipulator photothermal response object detection