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Non-reciprocity of energy transfer derived from cubic stiffness-induced nonlinear phenomena

Results in Physics 2025年 73卷

作者： Kong, Na Sun, Min Chen, Jianen Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin 300384 China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin University of Technology Tianjin 300384 China School of Science Tianjin Chengjian University Tianjin 300384 China

Introducing purely nonlinear elastic elements can induce rich dynamic behaviors, such as bifurcations, jumps and isolated resonance curves, to linear systems. Therefore, these elements are suitable for constructing strong non-reciprocity of vibration energy transfer. First, the energy transfer along reciprocal directions in a three-degree-of-freedom system is investigated, where three oscillators are connected by cubic springs. The semi-analytical solutions of the system are obtained using the complexification-averaging method and the least squares method. The results are compared against numerical solutions obtained by the Runge-Kutta method. The excitation amplitude range that produces strong non-reciprocity of vibration energy is analyzed. The jump phenomenon under combined excitation is investigated, and a trigger method for constructing non-reciprocity using an impulse is proposed. Then, an oscillator chain with cubic stiffness and scaling parameters is embedded into a multi-degree-of-freedom linear oscillator system to further explore the effect of cubic stiffness. Energy transfer along two directions is compared by exciting the leftmost oscillator and the rightmost oscillator. Moreover, the trigger effect of the impulse on non-reciprocity is demonstrated. The results show significant differences in vibration energy transfer within three distinct frequency bands. The critical points between reciprocal and non-reciprocal states are obtained, and the three stages of reciprocity related to excitation amplitude are analyzed. Lastly, the modulation effect of the cubic stiffness on non-reciprocity is conducted by comparing the energy of the output oscillator. © 2025 The Authors

关键词： Cubic stiffness Energy transfer Jump phenomenon Non-reciprocity

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Compression and thermal conduction performance of bioinspired sandwich structures fabricated by laser powder bed fusion

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Additive Manufacturing Frontiers 2025年第1期4卷

作者： Lin, Kaijie Hu, Kaiming Gu, Dongdong Yang, Jiankai Zhou, Mingdong Xiong, Yi College of Materials Science and Technology Nanjing University of Aeronautics and Astronautics Nanjing 210016 China Jiangsu Provincial Research Center for Laser Additive Manufacturing of High-Performance Components Nanjing University of Aeronautics and Astronautics Nanjing 210016 China Shanghai Aircraft Manufacturing Co. Ltd. Shanghai 201324 China School of Mechanical Engineering University of Shanghai for Science and Technology Shanghai 200093 China Shanghai Key Laboratory of Digital Manufacture for Thin-walled Structures School of Mechanical Engineering Shanghai Jiao Tong University Shanghai 200240 China School of System Design and Intelligent Manufacturing Southern University of Science and Technology Shenzhen 518055 China

After millions of years of natural evolution, horsetails have evolved unique stem structures that enable survival in harsh environments. Inspired by the cross-sectional characteristics of horsetail stems, a series of bioinspired sandwich structures were designed and fabricated using the laser powder bed fusion (LPBF) process. By combining experimental and finite element simulation methods, the formability, mechanical properties, deformation behavior, and thermal conduction performance of these structures were determined. Results show that the surface morphology of the bioinspired sandwich structures was smooth, with no cracks observed. The bioinspired sandwich structure with an inner tube diameter of 1.9 mm (D_1.9) exhibited optimal comprehensive mechanical properties, with a specific strength of 64.2 MPa/(g/cm³), and specific energy absorption of 3.3 J/g. Stress distribution results revealed that the D_1.9 structures had the most uniform stress distribution. Furthermore, increasing the internal conduction paths improved heat transfer;therefore, the thermal conductivities of the D_1.4, D_1.9, and D_2.4 structures were higher than that of the D₀ structure. This study demonstrates that a bioinspired design approach, combined with additive manufacturing technology, enables the development of high-performance structures with both load-bearing and thermally insulating capabilities. © 2025

关键词： Additive manufacturing Bioinspired Laser powder bed fusion Mechanical properties Thermal conduction

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Global Dynamics and Optimal design of a New Highly Efficient Nonlinear Energy Sink Based on Magnetic-Elastic Impacts with Negative Stiffness

Research Square

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Research Square 2021年

作者： Li, Shuangbao Wang, Tingting Chen, Jianen Research Institute of Science and Technology Innovation Civil Aviation University of China Tianjin300300 China College of Science Civil Aviation University of China Tianjin300300 China Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin300384 China

A new highly efficient elastic-impact bistable nonlinear energy sink (EI-BNES) based on magnetic-elastic impacts with negative stiffness and bistability is proposed and optimized through global dynamical analysis. The EI-BNES has better robustness and higher energy dissipation rates with nearly more than 96.5% for broadband impulsive excitations than the traditional cubic NESs and single bistable NESs. The structure of negative stiffness impacts is realized by reasonable layout of permanent ring magnets and springs. A two-degree-of-freedom (two-DOF) elastic-impact system is established to describe the coupled nonlinear interaction between the main structure and the attached EI-BNES. A global Melnikov reduction analysis (GMRA) is proposed to study global dynamics and homoclinic bifurcations of the reduced two-dimensional subsystem, which is used to explain the mechanism of nonlinear targeted energy transfer (TET) and detect the threshold of impulsive amplitudes of EI-BNES for in-well and compound motions between in-well and cross-well resonance responses. A special type of saddle-center equilibrium points is also found in the non-smooth system of the EI-BNES and can be used to effectively increase the energy dissipation rates. The optimal design criterion of the tuned EI-BNES for better dissipation performance is also first discussed based on the GMRA and numerical techniques for calculating the Melnikov function of the non-smooth systems. The effectiveness of the analytical GMRA is also verified by numerical simulations. © 2021, CC BY.

关键词： Stiffness

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Characterization and Evaluation of A Cable-Actuated Flexible Hand Exoskeleton*

Characterization and Evaluation of A Cable-Actuated Flexible...

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International Conference on Ubiquitous Robots and Ambient Intelligence (URAI)

作者： Hu Huang Aibin Zhu Jiyuan Song Yao Tu Xiaojun Shi Zhifu Guo Institute of Robotics & Intelligent Systems Xi'an Jiaotong University Shaanxi Key Laboratory of Intelligent Robots Xi'an China Key Laboratory of Education Ministry for Modern Design and Rotor-Bearing System Xi’an China Taiyuan Institute Co.Ltd. of China Coal Technology and Engineering Group Taiyuan China

ISBN: (数字)9781728157153

ISBN: (纸本)9781728157160

Flexible hand exoskeleton robots are more and more used in medical rehabilitation. This is due to the fact that these exoskeletons have strong compatibility with hands, can realize continuous deformation, and can apply force according to the motion trajectory. This paper proposes a cable-actuated flexible hand exoskeleton. Firstly, a motion model of one finger is established. Then a hand exoskeleton for rehabilitation is designed and constructed based on it. The exoskeleton is remotely actuated by motor and the force is transmitted through cables to achieve the bidirectional drive of the fingers. In addition, a tensioning mechanism of pulley block is designed to pre-tension the wire slack in the process of wire transmission. Finally, the experiment results show that the exoskeleton can bend the three joints of the index finger (DIP, PIP, and MCP) to 57 degrees, 35 degrees, and 31 degrees respectively. Under the load of 2.5N per finger, the exoskeleton can still drive the fingers to flex. The experimental results verify that the exoskeleton is a feasible solution that can meet the requirements of hand rehabilitation and can enable patients to recover and improve finger function in daily activities.

关键词： Thumb Exoskeletons Force Joints Robots Wires

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design and test of ceramic knife-edge seal for in-situ heating system of extracting volatile matter from lunar soil

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Advances in Space Research 2025年

作者： Yinchao Wang Yuanling Sun Jianbo Zhou Bowei Wang Junyue Tang Zixiao Lu Huazhi Chen Bo Wang Xiaobo Su Shengyuan Jiang School of Mechatronics and Engineering Shenyang Aerospace University Shenyang 110136 China Key Laboratory of Rapid Development & Manufacturing Technology for Aircraft (Shenyang Aerospace University) Ministry of Education Shenyang 110136 China State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin 150001 China Nanometer Intelligent Sensor Lab National Center for Nanoscience and Technology Beijing 100190 China China Academy of Space Technology Beijing 100190 China Sichuan boffins robotic and robotizatian Co. LTD Chengdu 610052 China

In the pursuit of accurate lunar soil volatile exploration, in-situ deep space sampling analysis offers unparalleled preservation of sample integrity. A critical challenge lies in ensuring a secure sealing environment. This paper introduces an innovative sealing method utilising a ceramic blade to compress a non-metallic seal. Initially, following a comprehensive multidimensional evaluation of sealing configurations, the ceramic knife-edge compression non-metallic sealing ring solution was determined to be optimal. This approach involves positioning the sealing ring within a grooved cylindrical heating furnace body, where radial compression is achieved through an annular ceramic knife-edge interface, thereby ensuring hermetic integrity. Subsequently, a sealing leakage model grounded in Roth theory was developed to elucidate micro-leakage mechanisms. ANSYS simulation software was utilised to investigate the influence of blade tip radius and temperature, revealing correlations with average stress and contact width, as well as the impact of temperature extremes on sealing efficacy. These findings provided the theoretical underpinning for subsequent ground tests. A dedicated test platform was established, adhering to the industry standard QJ3089A-2018, to evaluate the sealing performance of various seal and blade tip radius combinations under diverse conditions. Results indicated that, under a force of 500N, PTFE seals compressed by an R0.5mm blade and PVMQ seals compressed by an R0.6mm blade achieved leakage rates on the order of 10 -8 Pa·m 3 ·s -1 , aligning with theoretical predictions and demonstrating repeatable sealing capability. This study presents a novel and reliable sealing solution for the precise exploration of lunar soil volatiles, offering a technical breakthrough and robust sealing strategy for future deep space missions.

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Prechamber pressure and heat release characteristics controlled by active prechamber structure parameterization

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Applied Thermal Engineering 2025年 278卷

作者： Wenze Wei Run Chen Tie Li Qiang Wei Xinpeng Guo Zehao Wu Shuai Huang Shiyan Li State Key Laboratory of Ocean Engineering Shanghai Jiao Tong University Shanghai 200240 PR China Joint Laboratory for Green and Intelligent Marine Power System Shanghai Jiao Tong University Shanghai 200240 PR China Institute of Power Plants and Automation Shanghai Jiao Tong University Shanghai 200240 PR China China Ship Development and Design Center Wuhan 430064 PR China

The turbulent jet ignition (TJI) system is an effective approach to improve the thermal efficiency of lean-burn natural gas engines. However, understanding of the mechanism by which the prechamber structure controls hot turbulent jet ejection remains limited. In this study, the effects of active prechamber hole diameter ( D ) and volume ( V ) on hot turbulent jet development, prechamber pressure and heat release characteristics are investigated. The prechamber fueled with the premixed methane/air mixture is employed. The results show that hole diameter and volume exert minimal effect on jet penetration, but significantly affect the start of ejection timing of the hot jet. The jet projected area increases with larger prechamber hole diameter, due to broader jet expansion in the radial direction. In contrast, prechamber volume exerts less influence on jet projected area. Furthermore, the combined effect of prechamber hole diameter and volume on prechamber pressure is quantified. A novel linear correlation is established between prechamber structure ( D −1 V −2/3 ) and pressure. Additionally, linear correlations are identified between the ratio of prechamber volume to hole cross-sectional area ( V/A ) and three characteristic points: prechamber peak pressure, receding point, and start of hot jet ejection. Finally, the effect of prechamber structural parameters on prechamber heat balance is presented. As prechamber hole diameter increases and volume decreases, cold jet loss increases, resulting in a significant reduction in prechamber thermal efficiency.

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A regular-vine copula-based evidence theory model for structural reliability analysis involving multidimensional parameter correlation

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Computer Methods in Applied Mechanics and Engineering 2025年 444卷

作者： Dequan Zhang Xinjue Xie Zhijie Hao Weipeng Liu Xu Han Qing Li State Key Laboratory of Intelligent Power Distribution Equipment and System School of Mechanical Engineering Hebei University of Technology Tianjin 300401 PR China College of Architecture and Art Design Hebei University of Technology Tianjin 300401 PR China School of Aerospace Mechanical and Mechatronic Engineering The University of Sydney Sydney 2006 New South Wales Australia

The structural reliability analysis subject to epistemic uncertainty and multidimensional correlations among input variables signifies a crucial and demanding task. To address this challenge, a new evidence theory model capable of quantifying complex multidimensional correlations is proposed in this study; and further, an efficient reliability analysis method is developed. To start with, the multidimensional correlations are investigated through the proposed regular-vine copula-based evidence theory (VCET) model by leveraging finite number of samples and the marginal distributions of evidence variables. A joint basic probability assignment reconstruction method is then developed which integrates the copula function with multidimensional correlated evidence variables using a full-factorial numerical integration approach, thereby addressing parameter correlations. Further, the proposed model is employed in reliability analysis, and an enhanced focus element reduction (EFER) technique is developed. EFER synchronously constructs multiple auxiliary regions within the frame of discernment, where the classes of joint focus elements are directly determined, bypassing the high-cost extreme value analysis. Finally, the probability interval consisting of belief and plausibility measures is derived for structures affected by parameter correlations. In this study, three numerical benchmark problems and an engineering case study on the reliability analysis of the array antenna’s maximum gain are presented to demonstrate the effectiveness of the proposed method.

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When to preprocess? Keeping information fresh for computing enable internet of things

arXiv

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arXiv 2021年

作者： Wang, Xijun Fang, Minghao Xu, Chao Yang, Howard H. Sun, Xinghua Chen, Xiang Quek, Tony Q.S. School of Electronics and Information Technology Sun Yat-sen University Guangzhou510006 China Key Laboratory of Wireless Sensor Network & Communication Shanghai Institute of Microsystem and Information Technology Chinese Academy of Sciences 865 Changning Road Shanghai200050 China School of Electronics and Communication Engineering Sun Yat-sen University Guangzhou China School of Information Engineering Northwest A&F University Shaanxi Yangling China Key Laboratory of Agricultural Internet of Things Ministry of Agriculture and Rural Affairs Shaanxi Yangling China Shaanxi Key Laboratory of Agricultural Information Perception and Intelligent Service Shaanxi Yangling China Zhejiang University/University of Illinois at Urbana-Champaign Institute Zhejiang University Haining314400 China Information System Technology and Design Pillar Singapore University of Technology and Design Singapore487372 Singapore

Age of information (AoI), a notion that measures the information freshness, is an essential performance measure for time-critical applications in Internet of Things (IoT). With the surge of computing resources at the IoT devices, it is possible to preprocess the information packets that contain the status update before sending them to the destination so as to alleviate the transmission burden. However, the additional time and energy expenditure induced by computing also make the optimal updating a non-trivial problem. In this paper, we consider a time-critical IoT system, where the IoT device is capable of preprocessing the status update before the transmission. Particularly, we aim to jointly design the preprocessing and transmission so that the weighted sum of the average AoI of the destination and the energy consumption of the IoT device is minimized. Due to the heterogeneity in transmission and computation capacities, the durations of distinct actions of the IoT device are nonuniform. Therefore, we formulate the status updating problem as an infinite horizon average cost semi-Markov decision process (SMDP) and then transform it into a discrete-time Markov decision process. We demonstrate that the optimal policy is of threshold type with respect to the AoI. Equipped with this, a structure-aware relative policy iteration algorithm is proposed to obtain the optimal policy of the SMDP. Our analysis shows that preprocessing is more beneficial in regimes of high AoIs, given it can reduce the time required for updates. We further prove the switching structure of the optimal policy in a special scenario, where the status updates are transmitted over a reliable channel, and derive the optimal threshold. Finally, simulation results demonstrate the efficacy of preprocessing and show that the proposed policy outperforms two baseline policies. © 2021, CC BY.

关键词： Internet of things

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A Second-order C-bandpass Frequency Selective Surface

A Second-order C-bandpass Frequency Selective Surface

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International Conference on Microwave and Millimeter Wave Technology Proceedings

作者： Shenbing Wu Mingsheng Chen Meng Kong Liang Zhang Key Lab of Intelligent Computing & Signal Processing Ministry of Education Anhui University School of Electronic Engineering Huainan Normal University AnHui Province Key Laboratory of Simulation and Design for Electronic Information System Hefei Normal University

ISBN: (数字)9781728157337

ISBN: (纸本)9781728157344

A novel C-bandpass frequency selective surface(FSS) exhibiting miniaturized periodic parts is developed in this study. Such FSS acts as a bandpass filter at 4.03--7.87GHz. The proposed FSS exhibits miniaturization characteristics with the unit-cell dimension 0.12λ*0.12λ and the total thickness less than λ/28. Meantime, the simulation results reveal that the second-order FSS exhibits better stability under a variety of incident directions and polarization modes.

关键词： Frequency selective surfaces Microwave technology Surface waves Simulation Millimeter wave technology Stability analysis Periodic structures

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Traffic Control Task Scheduling Optimization Approach of Urban Road Intersection Based on Edge Computing

Traffic Control Task Scheduling Optimization Approach of Urb...

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Artificial Intelligence, Networking and Information Technology (AINIT), International Seminar on

作者： Xiang Fu Fei Wang Nan Ji Yilong Ren School of Transportation Science and Engineering Beihang University BUAA Beijing China Key Laboratory of Space Utilization Technology and Engineering Center for Space Utilization Chinese Academy of Sciences Beijing China Intelligent Transport System (ITS) R & D Center Shanghai Urban Construction Design and Research Institute (Group) Co. Ltd. Shanghai China

ISBN: (纸本)9781665412971

With the development of Connected Automated Vehicles (CAV), there will be a long period of mixed driving, which causes the traffic control task at intersections becomes much more complicated. The control tasks would include not only the traffic signal timing optimization but also the computing tasks for different levels of vehicles. Current control task management methods are proved to be inferior to solve this problem. In this paper, we propose an intersection control task scheduling optimization approach based on edge computing. Firstly, the traffic control edge computing system for intersections is constructed. Then, different types of control tasks are listed. Criticality and timeliness are introduced to calculate the control task's dynamic priority. The control task scheduling optimization model, which considering these two parameters is proposed. At last, the improved Hungarian algorithm is applied to solve the proposed task scheduling optimization model. Simulation results show that our proposed methods can effectively reduce task processing costs and ensure the critical tasks execute firstly.

关键词： Processor scheduling Computational modeling Heuristic algorithms Traffic control Scheduling Timing Task analysis

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