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Concurrent generation and amplification of longitudinal and bending waves using defective phononic crystals

Applied Mathematics and Mechanics(English Edition) 2025年第2期46卷 269-288页

作者： S.H.JO Department of Mechanical Roboticsand Energy EngineeringDongguk UniversitySeoul 04620Republic of Korea

Defective phononic crystals(PnCs)have enabled spatial localization and quantitative amplification of elastic wave *** previous research has focused on applications such as narrow-bandpass filters,ultrasonic sensors,and piezoelectric energy harvesters,typically operating under the assumption of an external elastic wave ***,a novel approach that uses defective PnCs as ultrasonic actuators to generate amplified waves has ***,the existing studies are limited to the generation of either longitudinal or bending waves,with no research addressing the concurrent generation of ***,this paper proposes a straightforward methodology for the concurrent generation and amplification of both wave types utilizing defect modes at independent defect-band *** piezoelectric elements are attached to the defect,with each element connected to independent external voltage *** precisely adjusting the magnitude and temporal phase differences between the voltage sources,concurrently amplified wave generation is *** paper highlights the advantages of the proposed analytical *** model is both computationally time-efficient and accurate,in comparison with the COMSOL simulation *** instance,in case studies,the analytical model reduces the computational time from one hour to mere seconds,while maintaining acceptable error rates of 1%in peak *** concurrent wave-generation methodology opens new avenues for applications in rotating machinery fault diagnosis,structural health monitoring,and medical imaging.

关键词： phononic crystal(PnC) defect concurrent generation piezoelectric ultrasonic actuator

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Swelling of Spherical Polyelectrolyte Gels

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Chinese Journal of Polymer Science 2024年第9期42卷 1386-1392,I0009页

作者： Ming-Yu Duan Jia-Dong Chen Yi-Ming Liu Zhao-Feng Peng Guang Chen Department of Advanced Manufacturing and Robotics College of EngineeringPeking UniversityBeijing 100871China

Polyelectrolyte(PE)gels,distinguished by their unique stimuli-responsive swelling behavior,serve as the basis of broad applications,such as artificial muscles and drug *** this work,we present a theoretical model to analyze the electrostatics and its contribution to the swelling behavior of PE gels in salt *** minimizing the free energy of PE gels,we obtain two distinct scaling regimes for the swelling ratio at equilibrium with respect to the salt *** compare our predictions for the swelling ratio with experimental measurements,which show excellent *** addition,we employ a finite element method to assess the applicability range of our theoretical model and *** anticipate that our model will also provide valuable insights into drug adsorption and release,deformation of red blood cells,4D printing and soft robotics,where the underlying mechanism of swelling remains enigmatic.

关键词： Gels Polyelectrolytes Swelling Stimuli-responsive Electrostatic interaction Cell model

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Mathematical modeling and simulations of stress mitigation by coating polycrystalline particles in lithium-ion batteries

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Applied Mathematics and Mechanics(English Edition) 2024年第6期45卷 947-962页

作者： N.IQBAL J.CHOI S.F.SHAH C.LEE S.LEE Department of Mechanical Roboticsand Energy EngineeringDongguk University-SeoulSeoul 04620Republic of Korea

A chemo-mechanical model is developed to investigate the effects on the stress development of the coating of polycrystalline Ni-rich LiNixMnyCo_(z)O_(2)(x≥0.8)(NMC)particles with poly(3,4-ethylenedioxythiophene)(PEDOT).The simulation results show that the coating of primary NMC particles significantly reduces the stress generation by efficiently accommodating the volume change associated with the lithium diffusion,and the coating layer plays roles both as a cushion against the volume change and a channel for the lithium transport,promoting the lithium distribution across the secondary particles more ***,the lower stiffness,higher ionic conductivity,and larger thickness of the coating layer improve the stress *** paper provides a mathematical framework for calculating the chemo-mechanical responses of anisotropic electrode materials and fundamental insights into how the coating of NMC active particles mitigates stress levels.

关键词： lithium-ion battery(LIB) polycrystalline particle coating finite element simulation Ni-rich LiNixMnyCo_(z)O_(2)(x>0.8)(NMC)

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Disordered hyperuniformity and thermal transport in monolayer amorphous carbon

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Science China(Physics,Mechanics & Astronomy) 2025年第2期68卷 145-152页

作者： Nianjie Liang Yuxi Wang Bai Song Department of Energy and Resources Engineering Peking UniversityBeijing 100871China Department of Advanced Manufacturing and Robotics Peking UniversityBeijing 100871China

Disordered hyperuniformity(DHU)is a recently discovered novel state of amorphous systems characterized by strongly suppressed density fluctuations at large length scales as in crystalline materials,which offers great potential for achieving unusual mechanical,electronic,and photonic ***,despite the fundamental and technological importance of thermal transport in amorphous solids,the effect of DHU remains largely ***,we theoretically study thermal transport in a class of two-dimensional DHU materials—monolayer amorphous carbon(MAC).Beginning with a perfect graphene lattice,we continuously apply Stone-Wales transformations to generate a series of MAC models with varied degrees of disorder and defects,which are quantified through comprehensive structural analysis including the so-called hyperuniformity index(H),where a smaller H indicates a higher degree of ***,we conduct molecular dynamics simulations to obtain the thermal conductivity(κ).A significant correlation between the thermal transport behavior and degree of hyperuniformity is observed,with the room-temperatureκdecreasing from 26.3 to 5.3 W m^(-1)K^(-1)while H is tuned from 0.0004 to ***,two distinct transport regimes are identified,including a nearly-DHU regime at small H(<0.005)whereκdrops sharply and a non-DHU region at larger H whereκbecomes relatively ***-resolved analysis reveals longer lifetime and higher participation ratio for the heat carriers in nearly-DHU MAC,implying that the hidden long-range correlations could support extended modes that enhance *** work highlights the impact of DHU on the thermal properties of amorphous materials and represents a conceptual advancement that is worthy of future exploration.

关键词： disordered hyperuniformity thermal transport amorphous material two-dimensional monolayer amorphous carbon

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Novel Acceleration Estimation for Improving Stability and Performance in Impedance Control

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Journal of Institute of Control, robotics and Systems 2024年第11期30卷 1260-1265页

作者： Lee, Hyunwook Cheon, Dasol Oh, Sehoon Department of Mechatronics Engineering Gyeongsang National University Korea Republic of Department of Robotics and Mechatronics Engineering DGIST Korea Republic of

This article presents a novel approach to enhancing the stability and performance of impedance control in robotic systems through improved acceleration estimation. The focus is on Series Elastic Actuators (SEAs), which are vital for achieving precise force control and ensuring safe and efficient human-robot collaboration. Traditional cascade impedance control is limited by the passive nature of the system, particularly when rendering high stiffness values. To address these limitations, we introduce Elastic Structure Preserving (ESP) control, which retains the inherent elastic structure of the SEA while enabling high-performance impedance rendering. A key aspect of ESP is the accurate estimation of load-side acceleration, which is crucial for ensuring stability and maintaining control performance. To achieve this, we propose a new acceleration estimation technique that enhances impedance rendering. Experimental results demonstrate the effectiveness of the proposed method, which shows improved stability and precise impedance control. This approach offers a robust solution for advanced robotic applications requiring high stiffness and precise force control. © ICROS 2024.

关键词： Robot applications

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Neural Network Algorithm Based on LVQ for Myocardial Infarction Detection and Localization Using Multi-Lead ECG Data

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Computers, Materials & Continua 2025年第3期82卷 5257-5284页

作者： Kassymbek Ozhikenov Zhadyra Alimbayeva Chingiz Alimbayev Aiman Ozhikenova Yeldos Altay Department of Robotics and Engineering Tools of Automation Satbayev UniversityAlmaty050010Kazakhstan Joldasbekov Institute of Mechanics and Engineering Almaty050010Kazakhstan

Myocardial infarction(MI)is one of the leading causes of death globally among cardiovascular diseases,necessitating modern and accurate diagnostics for cardiac patient *** the available functional diagnostic methods,electrocardiography(ECG)is particularly well-known for its ability to detect ***,confirming its accuracy—particularly in identifying the localization of myocardial damage—often presents challenges in *** study,therefore,proposes a new approach based on machine learning models for the analysis of 12-lead ECG data to accurately identify the localization of *** particular,the learning vector quantization(LVQ)algorithm was applied,considering the contribution of each ECG lead in the 12-channel system,which obtained an accuracy of 87%in localizing damaged *** developed model was tested on verified data from the PTB database,including 445 ECG recordings from both healthy individuals and MI-diagnosed *** results demonstrated that the 12-lead ECG system allows for a comprehensive understanding of cardiac activities in myocardial infarction patients,serving as an essential tool for the diagnosis of myocardial conditions and localizing their damage.A comprehensive comparison was performed,including CNN,SVM,and Logistic Regression,to evaluate the proposed LVQ *** results demonstrate that the LVQ model achieves competitive performance in diagnostic tasks while maintaining computational efficiency,making it suitable for resource-constrained *** study also applies a carefully designed data pre-processing flow,including class balancing and noise removal,which improves the reliability and reproducibility of the *** aspects highlight the potential application of the LVQ model in cardiac diagnostics,opening up prospects for its use along with more complex neural network architectures.

关键词： Electrocardiography 12-lead electrocardiogram myocardial infarction heart disease learning vector quantization algorithm machine learning

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Development of a User's Ankle RoM Customized Calf Muscle Stimulation System for Lower Limb Blood Circulation Improvement

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Journal of Institute of Control, robotics and Systems 2023年第2期29卷 113-119页

作者： Kim, Hyeoncheol Kwon, Donghyun Choi, Jungsu Department of Robotics Engineering Yeungnam University Korea Republic of

People spend too much time sitting because of a sedentary lifestyle. This lifestyle causes a deterioration of lower limb blood circulation and is responsible for various health problems (e.g., diabetes, deep vein thrombosis, and cardiac arrhythmia). Therefore, several devices have been developed to promote lower limb blood circulation by stimulating calf muscles even in a sitting position. However, in existing devices, the effect of blood circulation is poor, and the devices are too bulky and heavy to use daily. In this paper, a new type of calf stimulation device, called Healthy-CAL, is proposed. By applying a Semi-Auto-Locking linkage mechanism, the size of Healthy-CAL was reduced while the blood circulation effect of lower limbs was maximized. Furthermore, the limit angle recognition algorithm was applied to the device, which recognized the angle of the user’s ankle joint and exercised it by itself. With the use of the Healthy-CAL device in a sitting position, the blood circulation effect was three times greater than sitting with nothing done. © ICROS 2023.

关键词： Deterioration

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Signal Processing Method of Gyro Sensor for Improving the Performance of Recognizing Assist Phase of Gait Assist Wearable Robot

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Journal of Institute of Control, robotics and Systems 2023年第2期29卷 98-106页

作者： Seo, Wonjeong Choi, Jungsu Department of Robotics Engineering Yeungnam University Korea Republic of

Wearable robots have been developed to aid or substitute the gait locomotion of humans. To assist gait locomotion based on the intention of a wearer, a gait pattern analysis is required with a wearable sensor by measuring body information, i.e., a joint angular velocity. However, measuring a precise joint angular velocity is difficult because the attachment position of a sensor has a curvature and an anatomical joint axis which is invisible. Therefore, a sensor calibration algorithm, which aligns a sensor axis into an anatomical joint axis, is required to provide an apposite assist for a wearer. Hence, in this paper, a new and simple sensor calibration algorithm is proposed with a one sensor which contributes to simplifying and lightening the robot system. Since a wearer shakes the body or collides with the ground when walking, the attachment position of a sensor may be changed. Thus, a continuous sensor compensation algorithm is also proposed. The effectiveness of this new algorithm is demonstrated by gait locomotion experiments on various paths. © ICROS 2023.

关键词： Wearable sensors

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Effects of Viscous Dissipation and Periodic Heat Flux on MHD Free Convection Channel Flow with Heat Generation

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Frontiers in Heat and Mass Transfer 2024年第1期22卷 141-156页

作者： Mustafa Abdullah Robotics and Artificial Intelligence Engineering Department Faculty of EngineeringAl-Ahliyya Amman UniversityAmman19328Jordan

This study investigates the influence of periodic heat flux and viscous dissipation on magnetohydrodynamic(MHD)flow through a vertical channel with heat generation.A theoretical approach is *** channel is exposed to a perpendicular magnetic field,while one side experiences a periodic heat flow,and the other side undergoes a periodic temperature *** solutions for the governing partial differential equations are obtained using a finite difference approach,complemented by an eigenfunction expansion method for analytical *** and discussions illustrate how different variables affect the flow velocity and temperature *** offers comprehensive insights into MHD flow behavior and its interactions with the magnetic field,heat flux,viscous dissipation,and heat *** findings hold significance for engineering applications concerning fluid dynamics and heat transfer,offering valuable knowledge in this *** study concludes that the transient velocity and temperature profiles exhibit periodic patterns under periodic heat flow conditions.A temperature reduction is observed with an increase in the wall temperature phase *** contrast,an increase in the heat flux phase angle values raises the temperature values.

关键词： Magnetohydrodynamics(MHD) heat generation viscous dissipation periodic heat flux vertical channel

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A trajectory-level robot skill learning method based on fuzzy systems

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Science China(Information Sciences) 2025年第5期68卷 38-52页

作者： Chao ZENG Zhen DENG Boyang TI Yongsheng GAO Department of Computer Science University of Liverpool School of Mechanical Engineering and Automation Fuzhou University State Key Laboratory of Robotics Shenyang Institute of Automation Chinese Academy of Sciences Institutes for Robotics and Intelligent Manufacturing Chinese Academy of Sciences State Key Laboratory of Robotics and System Harbin Institute of Technology

Learning from demonstration(LfD) allows for the effective transfer of human manipulation skills to a robot by building a model that represents these skills based on a limited number of demonstrated ***,a skilllearning model that can comprehensively satisfy multiple requirements,such as computational complexity,modeling accuracy,trajectory smoothness,and robustness,is still ***,this work aims to provide such a model by employing fuzzy ***,we introduce an LfD model named Takagi-Sugeno-Kang fuzzy system-based movement primitives(TSKFMPs),which exploits the advantages of the fuzzy theory for effective robotic imitation learning of human *** work formulates the TSK fuzzy system and gradient descent(GD) as imitation learning models,leveraging recent advancements in GD-based optimization for fuzzy *** study takes a two-step strategy.(ⅰ) The input-output relationships of the model are established using TSK fuzzy systems based on demonstration *** this way,the skill is encoded by the model parameter in the latent space.(ⅱ) GD is used to optimize the model parameter to increase the modeling accuracy and trajectory *** further explain how learned trajectories are adapted to new task scenarios through local *** conduct multiple tests using an open dataset to validate our method,and the results demonstrate performance comparable with those of other ***,we implement it in a real-world case study.

关键词： robot skill learning movement primitives TSK fuzzy systems gradient descent robotics

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