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

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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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Adaptive Discrete-Time Sliding Mode Control Applied to the Pitch Motion of a Micro Air Vehicle with Flapping Wings

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Journal of Bionic engineering 2025年第2期22卷 585-595页

作者： Joshua Hill Farbod Fahimi Chang-kwon Kang Hikaru Aono Department of Mechanical&Aerospace Engineering University of Alabama in HuntsvilleHuntsvilleAL35899USA Department of Mechanical Engineering and Robotics Shinshu University3-15-1 Tokida3868567UedaNaganoJapan

A robust Adaptive Discrete-time Sliding Mode Controller (ADSMC) is formulated, and is applied to control the pitch motion of a simulated Flapping-Wing Micro Air Vehicle (FWMAV). There is great potential for FWMAVs to be used as aerial tools to assist with gathering data and surveying environments. Thanks to modern manufacturing and technology, along with an increased comprehension behind the aerodynamics of wing flaps, these vehicles are now a reality, though not without limitations. Given their diminutive size, FWMAVs are susceptible to real-world disturbances, such as wind gusts, and are sensitive to particular variations in their build quality. While external forces such as wind gusts can be reasonably bounded, the unknown variations in the state may be difficult to characterize or bound without affecting performance. To address these problems, an ADSMC is developed. First, the FWMAV model is converted from continuous-time to discrete-time. Second, an ADSMC for the newly discretized FWMAV model is developed. Using this controller, the trajectory tracking performance of the FWMAV is assessed against a traditional discrete sliding mode controller, and is found to have a decreased chattering frequency and decreased control effort for the same task. Therefore, the ADSMC is assessed as the superior controller, despite being completely unaware of the model parameters or wind gust.

关键词： Discrete-time sliding-mode control Adaptive sliding-mode control Flapping-wing micro air vehicles Wind gust

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Flexural-wave-generation using a phononic crystal with a piezoelectric defect

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Applied Mathematics and Mechanics(English Edition) 2023年第8期44卷 1241-1262页

作者： S.H.JO D.LEE Department of Mechanical Roboticsand Energy EngineeringDongguk UniversitySeoul 04620Republic of Korea Department of Mechanical Engineering Seoul National UniversitySeoul 08826Republic of Korea

This paper proposes a method to amplify the performance of a flexural-wave-generation system by utilizing the energy-localization characteristics of a phononic crystal(PnC)with a piezoelectric defect and an analytical approach that accelerates the predictions of such wave-generation *** proposed analytical model is based on the Euler-Bernoulli beam *** proposed analytical approach,inspired by the transfer matrix and S-parameter methods,is used to perform band-structure and time-harmonic analyses.A comparison of the results of the proposed approach with those of the finite element method validates the high predictive capability and time efficiency of the proposed model.A case study is explored;the results demonstrate an almost ten-fold amplification of the velocity amplitudes of flexural waves leaving at a defect-band frequency,compared with a system without the ***,design guidelines for piezoelectric-defect-introduced PnCs are provided by analyzing the changes in wave-generation performance that arise depending on the defect location.

关键词： phononic crystal(PnC) defect wave-generation fexural wave analytical model

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Generalized polynomial chaos expansion by reanalysis using static condensation based on substructuring

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Applied Mathematics and Mechanics(English Edition) 2024年第5期45卷 819-836页

作者： D.LEE S.CHANG J.LEE Department of Automotive Engineering Hanyang UniversitySeoul 04763Republic of Korea School of Mechanical Engineering Chungnam National UniversityDaejeon 34134Republic of Korea Department of Mechanical Robotics and Energy EngineeringDongguk UniversitySeoul 04620Republic of Korea

This paper presents a new computational method for forward uncertainty quantification(UQ)analyses on large-scale structural systems in the presence of arbitrary and dependent random *** method consists of a generalized polynomial chaos expansion(GPCE)for statistical moment and reliability analyses associated with the stochastic output and a static reanalysis method to generate the input-output data *** the reanalysis,we employ substructuring for a structure to isolate its local regions that vary due to random *** allows for avoiding repeated computations of invariant substructures while generating the input-output data *** substructuring with static condensation further improves the computational efficiency of the reanalysis without losing ***,the GPCE with the static reanalysis method can achieve significant computational saving,thus mitigating the curse of dimensionality to some degree for UQ under high-dimensional *** numerical results obtained from a simple structure indicate that the proposed method for UQ produces accurate solutions more efficiently than the GPCE using full finite element analyses(FEAs).We also demonstrate the efficiency and scalability of the proposed method by executing UQ for a large-scale wing-box structure under ten-dimensional(all-dependent)random inputs.

关键词： forward uncertainty quantification(UQ) generalized polynomial chaos expansion(GPCE) static reanalysis method static condensation substructuring

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Continuous sign language recognition using intra-inter gloss attention

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Multimedia Tools and Applications 2025年 1-19页

作者： Ranjbar, Hossein Taheri, Alireza Social and Cognitive Robotics Lab. Mechanical Engineering Department Sharif University of Technology Tehran Iran

Many continuous sign language recognition (CSLR) studies adopt transformer-based architectures for sequence modeling due to their powerful capacity for capturing global contexts. Nevertheless, vanilla self-attention, which serves as the core module of the transformer, performs context-aware weighted aggregation over all time steps. Therefore, the local temporal semantics of sign videos may not be fully exploited. This study introduces a novel module for sign language recognition, the intra-inter gloss attention module, designed to leverage relationships among frames within glosses and to capture the semantic and grammatical dependencies between glosses in the video. In the intra-gloss attention module, the video is divided into equally sized chunks, and a self-attention mechanism is applied within each chunk. This localized self-attention significantly reduces complexity and eliminates noise introduced by considering non-relative frames, and achieves a 0.6 improvement in WER based on the baseline model while increasing inference speed by 20%. In the inter-gloss attention module, the chunk-level features within each gloss chunk are initially aggregated by average pooling along the temporal dimension, which leads to a 0.7 improvement in WER. Subsequently, multi-head self-attention is applied to all chunk-level features. Given the non-significance of the signer-environment interaction, we utilize segmentation module to remove the background of the videos. This enables the proposed model to direct its focus toward the signer and achieve an additional 1.5 improvement in WER. Experimental results on the PHOENIX-2014 benchmark dataset demonstrate that our method can effectively extract sign language features in an end-to-end manner without any prior knowledge, improve the accuracy of CSLR, and achieve the word error rate (WER) of 20.4 on the test set which is a competitive result compare to the state-of-the-art which uses additional supervisions. © The Author(s), under exc

关键词： Semantics

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Smart Rear Underrun Safety Shield (Sruss) for Hybrid Vehicles to Prevent Collisions with the Rear of Heavy Trailers

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Journal of engineering Science and Technology Review 2024年第4期17卷 83-98页

作者： Patil, Rajesh V. Department of Mechanical – Robotics & Automation Engineering MIT World Peace University Maharashtra Pune India

The deadliest accident ratio for cars and trucks on highways occurs when vehicles are running underneath trucks, causing serious and even fatal injuries to the occupants of the vehicle. When heavyweight trucks collide with automobiles, passengers in the car are not shielded from potentially deadly injuries by the back safety shield's improper geometry. A Smart Rear Underrun Safety Shield (SRUSS) for rear impact and rear underrunning of hybrid passenger cars and heavyduty trailers was created because of this work. According to testing conducted by the Vehicle Research and Development Establishment (VRDE), the current safety shield has higher distortion. Finite element analysis was used to model and test the cleverly adapted safety shield under Indian Standard 14812-2005 regulatory circumstances. Additionally, it was produced and tested internally with the same regulatory requirements. A certified testing setup was used to effectively confirm the safety shield. Through accreditation from the Automobile Research Association of India (ARAI) and real-world verification testing at VRDE, the performance of a proposed Smart Rear Underrun Safety Shield (SRUSS) for hybrid vehicles was examined. The results obtained have satisfied the road transport safety standards of the Indian Standard 14812-2005. © 2024 School of Science, DUTH. All rights reserved.

关键词： Trucks

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Control of a Two-wheeled Self-balancing Robot With a Sliding Mechanism

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Journal of Institute of Control, robotics and Systems 2025年第1期31卷 37-43页

作者： Kim, David Kim, Hyun Seok Choi, Dongil Department of Mechanical Engineering Myongji University Korea Republic of Smart Robotics Team Hyundai Rotem Korea Republic of

Two-wheeled self-balancing robot maintains balance and performs driving functions using two wheels, featuring excellent mobility due to its simple structure and wheel-driven system. However, when a long longitudinal structure is applied to increase space efficiency, challenges may arise in balance control and slope entry. In this study, a sliding mechanism and Model Predictive Control (MPC) were applied to achieve balance and driving control for a robot with a long longitudinal body. The system dynamics were analyzed using the Lagrangian method, and a reference for the sliding mechanism was generated to support balance control. Through Gazebo simulations, the performance of the MPC algorithm was verified, confirming that the robot could reach a stable balance state through Swing-up motion and maintain balance consistently. Additionally, stable driving performance was demonstrated in slope driving tests. We conducted experiments by applying the same algorithm to the actual robot, confirming that it successfully performed stable balance control and slope driving control in real-world environments. © ICROS 2025.

关键词： Model predictive control

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How Sure is the Driver? Modelling Drivers’ Confidence in Left-Turn Gap Acceptance Decisions

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Computational Brain and Behavior 2024年第3期7卷 437-456页

作者： Bontje, Floor Zgonnikov, Arkady Department of Cognitive Robotics Faculty of Mechanical Engineering Delft University of Technology

When a person makes a decision, it is automatically accompanied by a subjective probability judgment of the decision being correct, in other words, a confidence judgment. A better understanding of the mechanisms responsible for these confidence judgments could provide novel insights into human behavior. However, so far confidence judgments have been mostly studied in simplistic laboratory tasks while little is known about confidence in naturalistic dynamic tasks such as driving. In this study, we made a first attempt of connecting fundamental research on confidence with naturalistic driver behavior. We investigated the confidence of drivers in left-turn gap acceptance decisions in a driver simulator experiment (N = 17). We found that confidence in these decisions depends on the size of the gap to the oncoming vehicle. Specifically, confidence increased with the gap size for trials in which the gap was accepted, and decreased with the gap size for rejected gaps. Similarly to more basic tasks, confidence was negatively related to the response times and correlated with action dynamics during decision execution. Finally, we found that confidence judgments can be captured with an extended dynamic drift–diffusion model. In the model, the drift rate of the evidence accumulator as well as the decision boundaries are functions of the gap size. Furthermore, we demonstrated that allowing for post-decision evidence accumulation in the model increases its ability to describe confidence judgments in rejected gap decisions. Overall, our study confirmed that principles known from fundamental confidence research extend to confidence judgments in dynamic decisions during a naturalistic task. © The Author(s) 2024.

关键词： Confidence Decision making Driver behavior Evidence accumulation Metacognition

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Exploring the role of graphene filler on mechanical properties of cotton/viscose hybrid composites

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Interactions 2024年第1期245卷 1-9页

作者： K, Arunkumar S, Seenivasan M S, Sureshkumar C, Chanakyan Bordoloi, Namrata P, Ramkumar Department of Mechanical Engineering MVJ College of Engineering College Bangalore560067 India Department of Mechanical Engineering Rathinam Technical Campus Coimbatore641021 India Department of Robotics and Automation Sri Ramakrishna Engineering College Coimbatore641022 India Department of Mechanical Engineering.Kalasalingam Academey of Research and Education Virudhunagar India

The work intends to prepare a cotton/viscose fabric-reinforced hybrid composite (CVFRHC) using a compression moulding process using graphene as a filler material and investigate the mechanical characteristics of the composite, including its tensile strength, flexural strength, impact strength, and hardness. The graphene filler was combined with the matrix material in several proportions: 1 weight% (wt%), 2 wt%, and 3 wt%. It was found that the mechanical characteristics of the composite were enhanced by the filler addition. With an increased tensile strength of 70.9 MPa and flexural strength of 384 MPa, the hybrid composite containing 3-weight% graphene was shown to be effective. The addition of 3 wt% resulted in improvements of 10.6% in tensile strength and 9.6% in flexural strength. The graphene as a nano filler used to enhance the mechanical properties of the polymer matrix compisites. This is due to the proper dispersion of graphene filler with the polymer matrix which leads to enhance the interfacial bonding between the hybrid matrix and the hybrid fibres. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2024.

关键词： Hybrid composites

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