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Research on Robust Measurement Method of Heart Rate Using Remote Photoplethysmography Based on Adversarial Learning Network with High and Low Frequency Features

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IEEE Transactions on Circuits and systems for Video Technology 2025年

作者： Zhai, Dezhao Chen, Wei Ding, Yinghao Yu, Ming Li, Qinwei Wu, Hang Tianjin University of Technology Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering Tianjin300384 China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin University of Technology China People's Liberation Army Systems Engineering Institute Academy of Military Sciences Tianjin300161 China Civil Aviation University of China Tianjin Key Laboratory for Advanced Signal Processing Tianjin300300 China Nankai University School of Artificial Intelligence Tianjin300381 China

Remote Photoplethysmography (rPPG) is a non-contact method for measuring heart rate (HR) through facial video, breaking the constraints of contact measurements and offering broad application prospects. However, in real monitoring scenarios, the distance of subjects and facial illumination often vary. This leads to degradation of rPPG signals due to changes in facial resolution and light intensity. This paper presents the High and Low Frequency Feature Adversarial Learning Network (HLFF-AL), which utilizes feature space interpolation and composite feature capture to perform multi-band global and local signal extraction. By adopting an adversarial learning strategy, it enhances the capability to capture semantic information of rPPG under varying resolutions and lighting, bridging the differences in rPPG signal generation due to resolution changes. While maintaining accuracy in HR measuring, the robustness of the network is improved to achieve robust measurement of HR via rPPG. Even under high-resolution conditions, the Mean Absolute Error (MAE) for the three public datasets - unchanging lighting (COHFACE, UBFC-rPPG) and varying lighting (BUAA-MIHR) - reached 1.10 bpm, 1.64 bpm, and 4.41 bpm, respectively, with a mere 0.29 bpm difference in MAE between high and low resolutions on the BUAA-MIHR dataset. This demonstrates that HLFF-AL can predict more robust rPPG signals in various resolutions and lighting scenarios, achieving competitive results compared to state-of-the-art methods. © 1991-2012 IEEE.

关键词： Heart

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Development of an HCN dual laser for the interferometer on EAST

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Plasma Science and Technology 2017年第8期19卷 37-42页

作者：李根魏学朝刘海庆申俊杰揭银先连辉曾龙邹志勇张际波王守信 Tianjin Key Laboratory of the Design and Intelligent Control of the Advanced Mechatronical System Tianjin University of Technology Institute of Plasma Physics Chinese Academy of Sciences

A two-color continuous wave（CW） discharge-pumped far-infrared（FIR） hydrogen cyanide（HCN） laser was developed as the source of an interferometer for measuring the line-averaged electron density in the Experimental advanced Superconducting Tokamak（EAST）. The output power of the dual laser system was about 120 m W from each laser on the 337 μm（0.89 THz）line. The polarization of each output beam was fixed using thin tungsten filaments and oscillated in the EH11 mode. Different megahertz intermediate frequencies（IF） and a slight frequency offset（～1 MHz） were generated in this system to replace the traditional rotating grating with～10 k Hz IF, and this can improve the time resolution of the interferometer significantly. The experimental result showed that different IF signals were obtained by successfully adjusting the cavity length. In particular, the beat frequency was captured at ～1.3 MHz by a Schottky mixer when the length of the resonant cavities was changed by 5 μm by an automatic adjustment system. In order to study the character of IF, a long time record of the IF signal was carried out,and the IF signal could be stabilized for a few minutes in the range of 2 MHz to 3 MHz. A realtime IF stability control system was initially designed for long pulse discharge experiments on the EAST. The ～MHz frequency response and good phase sensitivity of the dual laser HCN interferometer will allow the system to track fast density profiles and resolve fast MHD events,such as tearing/neoclassical tearing, disruptions, etc.

关键词： EAST interferometer Schottky pumped mixer captured tungsten grating resonant rotating

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

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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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Experimental research on dynamic characteristics analysis of machine tool based on unit structure

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Revista de la Facultad de Ingenieria 2016年第4期31卷 70-84页

作者： Zhu, Peihao Zheng, Qingchun Hu, Yahui Wang, Bing Chao, Jiaqi Tu, Huan Sun, Ning Li, Jinxiang School of Mechanical Engineering Tianjin University of Technology Tianjin Key Laboratory of the Design and Intelligent Control of the Advanced Mechatronical System Tianjin300384 China

By the experiment modal research for unit structure, the natural frequency and mass of US by means of experimental modal analysis is explored. Experimental modal analysis on US was applied to achieve optimal US simultaneously to satisfy multiple conflicting performance requirements of mass and natural frequency of US. Then the structural parameters of US were optimized to increase natural frequencies and reduce mass. Experimental modal analysis is an efficient technique to accurately identify the dynamic behavior of a structure and provides modal parameters, such as natural frequencies and mode shapes.

关键词： Modal analysis

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Study on the High-Speed Penetration and Shear Failure Mechanism of Beach Sand

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Materials 2025年第9期18卷 1922-1922页

作者： Zhu, Jianzhong Li, Jiangquan Kong, Yun Dong, Mingming Li, Yuqiong Zou, Meng Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin300384 China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin University of Technology Tianjin300384 China Key Laboratory for Bionics Engineering of Education Ministry Jilin University Changchun130022 China School of Mechanical Engineering Beijing Institute of Technology Beijing100081 China Key Laboratory for Mechanics in Fluid Solid Coupling Systems Institute of Mechanics Chinese Academy of Sciences Beijing100190 China State Key Laboratory of Nonlinear Mechanics Institute of Mechanics Chinese Academy of Sciences Beijing100190 China Guangdong Aerospace Research Academy Nansha Guangzhou511458 China

In this paper, the contact parameters of beach sand are calibrated based on the discrete element method and the optimal design method, and the obtained parameters by calibration are used as input for the angle of repose simulation. The relative error between angle of repose simulation results and experimental results is 3.27%. Based on the penetration and shear tests, simulation models were constructed to study the pressure shear failure mechanism of beach sand under high-speed conditions. The high-speed penetration simulation shows that with the increase of the penetration rate, the influence area of the sinkage plate gradually increases, and the stress of sand particles also increases. When the penetration rate increased from 0.5 m/s to 8 m/s, the pressure on the plate increased 12.7 times, indicating that the bearing capacity of the sand increased significantly with the increase of the penetration rate. The high-speed shear simulation shows that in the stable shear stage, the average shear torque initially increases slightly with the increase of speed, and then decreases significantly when the speed exceeds 4 m/s. This is because as the shear rate increases, the disturbance of the soil by the shear plate increases, the velocity of soil particles increases, resulting in a decrease in the number of soil particles in contact with the shear plate, thereby reducing the shear torque. © 2025 by the authors.

关键词： Fracture mechanics

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Biomechanical Finite Element Methods Study of a Novel Internal Fixation system for Lumbar Spondylolysis

SSRN

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SSRN 2025年

作者： Li, Jingyuan Du, Chengfei Wang, Yulei Du, Di Liang, Jinlong Shao, Nengqi Feng, Fanzhe Xu, Wenhao Xu, Yongqing Cui, Yi Center for Joint Surgery Intelligent Manufacturing and Rehabilitation Engineering Center The First Affiliated Hospital of Army Medical University Chongqing400038 China Chongqing Municipal Science and Technology Bureau Key Laboratory of Precision Medicine in Joint Surgery Chongqing400038 China Chongqing Municipal Education Commission Key Laboratory of Joint Biology Chongqing400038 China Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of mechanical engineering Tianjin University of Technology Tianjin300384 China Department of Orthopaedic Surgery 920th Hospital of Joint Logistics Support Force Kunming650032 China Department of Orthopaedic Surgery 920th Hospital of Joint Logistics Support Force No. 212 of Da-Guan Road Xishan District Kunming650032 China

ObjectiveThis study aimed to verify the biomechanical efficacy of a novel internal fixation system for repairing lumbar spondylolysis (LS). Additionally, the changes in the mechanical performance of the novel internal fixation device during compression were *** healthy 25-year-old male volunteer was recruited for lumbar spine CT data acquisition to construct and validate a nonlinear finite element model of the L4-S1 spinal segment (A). Based on this, models were established for L5 spondylolysis (B), traditional internal fixation (C), and the pressurization process of the novel LS repair device fixation (D→E→F). For these six models, we constrained the lower surface of the S1 vertebral body while applying an axial compression force of 500 N and a moment load of 7.5 N·m on the upper surface of the L4 vertebral body to simulate six motions of the lumbar spine. The performance of each finite element model was evaluated by comparing the range of motion (ROM), maximum displacement, and maximum pressure experienced by the lumbar spine under different motion *** with Model C, Models D, E, and F exhibited a reduced ROM and maximum displacement (1%-38.5%, 12.8%-63.6%, and 32.8%-80.2%) compared with Model C during six different motions. Notably, compared with Model C, the novel internal fixation models consistently demonstrated a decreasing trend in the maximum stress on the intervertebral discs (IVD) and an increasing trend in the maximum stress on the articular cartilage and maximum stress and displacement of the bone graft. Moreover, the novel internal fixation model displayed larger ranges of evenly distributed stresses on the isthmus and reduced maximum stress on the internal fixation device across all six motions, with improved stiffness effects during the pressurization process of the novel internal fixation system (D→E→F).ConclusionsAccording to several mechanical comparisons, the novel internal fixation system had better biomechan

关键词： Axial compression

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On Simulation for Fuzzy control on Oxygen Concentration of the Mixed Air Supplied by Breathing Adjuster 34

On Simulation for Fuzzy Control on Oxygen Concentration of t...

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第三十四届中国控制会议

作者： SUN Hao WANG Shou-jun SUN Qing-lin Tianjin Key Laboratory of the Design and Intelligent Control of the Advanced Mechatronical System The College of Mechanical Engineering Tianjin University of Technology The College of Computer and Control Engineering Nankai University Tianjin Key Laboratory of Intelligent Robotics

ISBN: (纸本)9781467374439

The breathing adjuster is the core component of life support system of an aircraft and it is very important to control the valve to make the breathing adjuster supply the pilot the mixed air with the suitable oxygen concentration. In this paper the mathematical model, which describes the relation between the opening degree of the valve of the breathing adjuster and the flight altitude of the aircraft, is set up through analyzing requirement of aviation physiology and working principles of the breathing adjuster. Then a fuzzy controller is designed to control the opening degree of the valve in order to make the breathing adjuster supply to the pilot the mixed air with suitable oxygen concentration. Finally MATLAB Simulink is employed to verify the feasibility and validity of the fuzzy controlling approach. The results of simulating experiments show that the fuzzy control approach proposed in this paper can make the breathing adjuster supply the mixed air with suitable oxygen concentration to the pilot boarded on an aircraft.

关键词： Breathing adjuster,Oxygen concentration,the opening degree of the valve,Fuzzy control,Simulation

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Modelling and analysis of planar robotic arm dynamics based on an improved transfer matrix method for multi-body systems 14

Modelling and analysis of planar robotic arm dynamics based ...

引用

14th International Federation for the Promotion of Mechanism and Machine Science World Congress, IFToMM 2015

作者： Chen, W. Li, H. Zhang, X.Z. Tianjin Key Laboratory of the Design and Intelligent Control of the Advanced Mechatronical System Tianjin China Academy of Military Medical Sciences Tianjin China

ISBN: (纸本)9789860460988

An improved transfer matrix method for multi-rigid-body systems is presented based on the structural characteristics of the manipulator and the relations between motion transfer and force transfer. Thus, a new model applicable to serial robots is obtained by using of discrete time transfer matrix method. Based on the improved method, a unified model for a manipulator with n DOF is derived. This model contains both kinematic and dynamic characteristics of the system. According to the motion transformation relation between the joint space and the operational space of the manipulator, the solution and the procedure are developed for both forward and inverse kinematics of the unified model. The simulation results of a 2DOF planar manipulator show the rightness of the modelling method and exhibit its superiority to other methods.

关键词： Inverse kinematics

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An asymmetrically substituted dithieno[3,2-b:2',3'-d]pyrrole organic small-molecule hole-transporting material for high-performance perovskite solar cells

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Chinese Journal of Chemical Engineering 2022年第5期35卷 51-57页

作者： Jingwen Jia Yue Zhang Liangsheng Duan Quanping Wu Yu Chen Song Xue Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical EngineeringTianjin University of TechnologyTianjin 300384China Tianjin Key Laboratory of Organic Solar Cells and Photochemical Conversion Department of Applied ChemistryTianjin University of TechnologyTianjin 300384China

Hole-transporting materials play a vital role in terms of the performance of perovskite solar cells(PSCs).The dithieno[3,2-b:2’,3’-d]pyrrole(DTP),an S,N-heterocyclic building block,has been proved to be desirable for molecular design of hole-transporting materials in *** developed an asymmetrically substituted DTP small-molecule(JW12)and a reference compound(JW11).The asymmetrical structure of JW12 leads to different absorption properties and electron *** device in a planar n-i-p architecture using JW12 shows a much higher PCE(18.07%)than that based on JW11(15.46%),which is also better than the device based on spiro-OMe TAD(17.47%).We hope our research can provide a new perspective in molecular design of organic HTMs for perovskite solar cells.

关键词： Hole-transporting materials DTP Perovskite Photovoltaic performance

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Nonlinear vibration mechanism of elastic beam in large overall rotation with rotor eccentricity effect

Nonlinear vibration mechanism of elastic beam in large overa...

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2021 International Conference on Mechanical Engineering, intelligent Manufacturing and Automation Technology, MEMAT 2021

作者： Zhao, Lei Yan, Zhao-Fang Zhao, Xin-Hua Li, Bin Tianjin Key Laboratory of the Design and Intelligent Control of the Advanced Mechatronical System Tianjin China Tianjin China School of Mechanic Engineering Tianjin University of Technology Tianjin China

The eccentric effect of rotor has seriously affected on the stability and precision of the mechanism at high speed for light and flexible mechanism in industrial application. The analysis of nonlinear vibration mechanism must be completed to realize precision and stable control of elastic beam in a large overall rotation. Firstly, the slender flexible rod is assumed as Euler-Bernoulli beam. We apply the deformation theory of elastic beam to establish its kinematic constraint relationship. Its dynamic model is built with Galerkin method and Hamilton principle. Then the Lagrange method is used to establish the rotor dynamics model based on the Jeffcott rotor. The coupling part between the motor and the elastic beam is assumed to be rigidly connected, and the dynamic model of the motor-elastic beam system can be obtained. Lastly, we analyze the nonlinear vibration mechanism of the elastic beam with rotor eccentricity effect through applying the fourth-order Runge-Kutta method and the superposition principle of traveling wave. It provides an important theoretical basis for making an effective vibration suppression strategy for elastic beam. © Published under licence by IOP Publishing Ltd.

关键词： Dynamic models

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