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| 1 | Design,modeling and experimental investigation of a magnetically modulated rotational energy harvester for low frequency and irregular vibration显示文摘Vibration energy harvesting is a promising approach for sustainable energy generation from ambience to meet the development of self-powered systems.Here,we propose a novel compact non-resonant magnetically modulated rotational energy harvester(MMR-EH)for low frequency and irregular vibration.Through the rational arrangement of multiple magnetic fields in space,a ring route with low potential energy is established.A movable magnet can be non-contact modulated by the magnetic force to move along the ring route under irregular vibration,which is instrumental in electromechanical energy conversion.A dynamic model of the MMR-EH is developed based on the energy method and verified experimentally.The effects of key parameters on the magnetically modulated route are analysed.The simulation and experimental results demonstrate that the MMR-EH can effectively harvest the energy from ultra-low frequency(3 Hz)and irregular vibration.At a reciprocating vibration frequency of 10 Hz and an amplitude of 20 mm,the harvester can produce an average power of 0.29 mW. | ZHAO LinChuan ZOU HongXiang GAO QiuHua YAN Ge WU ZhiYuan LIU FengRui WEI KeXiang YANG Bin ZHANG WenMing | 2020 | Science China(Technological Sciences)2020，63，10： | 5 |
| 2 | Bending vibration control of pipes conveying fluids by nonlinear torsional absorbers at the boundary显示文摘A nonlinear torsional absorber,which can overcome the influence of the fluid velocity on the natural frequency,is employed at the boundary to restrain the bending vibration of a pipe for the first time.By using the rotating angle at the end of the pipe,the bending vibration energy is pumped to the boundary absorber.The nonlinearly coupled pipe-absorber governing equations are obtained by the generalized Hamilton’s principle.Steady-state responses subjected to a basement excitation are discussed by the modal-correction-harmonic-balance-method.According to this method,the boundaries of the pipe are treated as the generalized governing equations.In this way,those nonlinearities and time-dependent terms in the boundary are involved in the response completely.A direct simulation method,called the differential quadrature element method(DQEM),is used to verify these analytical results.The investigation indicates that the nonlinear boundary absorber owns two outstanding advantages.The first one is that the natural characters remain the same and the absorber can capture the resonance of the pipe automatically.The second one is that the absorber works at all natural modes.Especially,by using the nonlinear damping,the absorber will not worsen the weak vibration in the non-resonance region.The parameters of the absorber are investigated to optimize the efficiency in detail.The result finds that good efficiency can be achieved with a tiny mass.Meanwhile,the efficiency becomes better as the damping increases.With the help of these investigations,the work provides a new strategy to protect pipes conveying fluids from being destroyed by the vibration. | MAO XiaoYe DING Hu CHEN LiQun | 2021 | Science China(Technological Sciences)2021，64，8： | 2 |
| 3 | Stability analysis of a pipe conveying fluid with a nonlinear energy sink显示文摘This paper considers the global stability problem of the system comprising a pipe conveying fluid and a nonlinear energy sink(PCF-NES)system.First,a quadratic form model containing a gradient term of a convex function is obtained from a high-order partial-differential-equation model of the PCF-NES system using the Galerkin approximation approach.Energy and disturbance functionals are then established based on this model.Second,a Lyapunov function is constructed based on the first-order characteristic of the convexity and energy disturbance technique to prove the global exponential stability of the approximated PCF-NES system.Finally,theoretical results are verified using numerical simulations and the positive effect of the NES on the vibration control of the entire PCF is discussed. | Nan DUAN Sida LIN Yuhu WU Xi-Ming SUN Chongquan ZHONG | 2021 | Science China(Information Sciences)2021，64，5： | 2 |
| 4 | Dynamics Analysis of Active Variable Stiffness Vibration Isolator for Whole-Spacecraft Systems Based on Nonlinear Output Frequency Response Functions显示文摘In order to improve the harsh dynamic environment experienced by heavy rockets during different external excitations,this study presents a novel active variable stiffness vibration isolator(AVS-VI)used as the vibration isolation device to reduce excessive vibration of the whole-spacecraft isolation system.The AVS-VI is composed of horizontal stiffness spring,positive stiffness spring,parallelogram linkage mechanism,piezoelectric actuator,acceleration sensor,viscoelastic damping,and PID active controller.Based on the AVS-VI,the generalized vibration transmissibility determined by the nonlinear output frequency response functions and the energy absorption rate is applied to analyze the isolation performance of the whole-spacecraft system with AVS-VI.The AVS-VI can conduct adaptive vibration suppression with variable stiffness to the whole-spacecraft system,and the analysis results indicate that the AVS-VI is efTective in reducing the extravagant vibration of the whole-spacecraft system,where the vibration isolation is decreased up to above 65%under different acceleration excitations.Finally,different parameters of AVS-VI are considered to optimize the whole-spacecraft system based on the generalized vibration transmissibility and the energy absorption rate. | Kefan Xu Yewei Zhang Yunpeng Zhu Jian Zang Liqun Chen | 2020 | Acta Mechanica Solida Sinica2020，33，6： | 1 |
| 5 | Design of an all-day electrical power generator based on thermoradiative devices显示文摘Energy harvesting from sun and outer space using thermoradiative devices(TRDs),despite being promising renewable energy sources,is limited only to daytime and nighttime period,respectively.Such a system with 24-hour continuous electric power generation remains an open question thus far.Here,a TRD-based power generator that harvests solar energy via concentrated solar irradiation during daytime and via thermal infrared emission towards the outer space at nighttime is proposed,thus achieving the much sought-after 24-hour electrical power generation.Correspondingly,a rigorous thermodynamical model is developed to investigate the all-day performance characteristics,parametric optimum design,and the role of various energy loss mechanisms.The calculated results predict that the daytime TRD-based system yields a peak efficiency of 12.6%under 10 suns,thus sig-nificantly outperforming the state-of-art record-setting solar thermoelectric generator.This work reveals the potential of TRD towards 24-hour electricity generation and future renewable energy technology. | ZHANG Xin YANG GuoFeng YAN MengQi ANG Lay Kee ANG Yee Sin CHEN JinCan | 2021 | Science China(Technological Sciences)2021，64，10： | 1 |
| 6 | 基于等效线性化方法的非线性振动能量采集器功率分析显示文摘输出功率分析是振动能量采集器结构设计、参数选择的重要依据。有鉴于传统功率分析方法比较复杂,以一类电磁式振动能量采集器为对象,提出了一种新的非线性振动能量采集器功率分析方法,其核心是将非线性振动方程进行等效线性化处理,并借助传递函数开展功率优化分析。首先,考虑非线性磁力以及基尔霍夫电流定律,建立了通用化的采集器1.5自由度七次非线性机电耦合模型;其次,将动态频率法用于求解该系统控制方程,采用高阶谐波成分替代方程中的非线性项,实现了原有系统控制方程的等效线性化;最后,利用传递函数推导了输出功率表达式,分析等效线性化系统负载,机电耦合系数等因素对于输出功率的影响。研究结果表明:以等效线性化为基础的功率分析,可以有效地克服传统非线性能量采集器系统功率分析方法复杂的问题,具有良好的适用性。 | 李佳诚 王志霞 王炜 王辰 | 2022 | 振动与冲击2022，41，1： | 1 |
| 7 | Finite-time adaptive formation control for multi-agent systems with uncertainties under collision avoidance and connectivity maintenance显示文摘In this paper,the problem of adaptive finite time formation control is investigated for double integrator multi-agent systems with uncertainties.Firstly,considering the multi-agent systems with uncertain dynamic reference and external bounded disturbance,a distributed adaptive estimator control algorithm is designed to realize formation tracking control in finite-time.It is important that the collision avoidance and maintaining connectivity of the multi-agent systems are realized by constructing an effective potential function based on distance constraints.On the other hand,the problem of formation production control for the double integrator systems is discussed with desired formation shape in finite-time.Achieving four control objectives is the main contributions in all the phases,including the estimation of uncertainties,collision avoidance,connectivity maintenance,and finite-time convergence.Finally,an application example of the formation production control is presented to verify accuracy of the proposed theoretical method. | HE XiaoYan WANG QingYun HAO YuQing | 2020 | Science China(Technological Sciences)2020，63，11： | 1 |
| 8 | 正弦激励下分段线性刚度能量阱的振动抑制研究显示文摘分段线性刚度能量阱是非线性能量阱的一种,属于被动减振装置。该文主要研究正弦激励下分段线性刚度能量阱的结构参数对振动抑制效果的影响。建立耦合分段线性刚度NES系统动力学模型,分析分段线性刚度能量阱结构参数对系统振动抑制效果的影响。针对某卫星敏感部件,综合上述分析结果选取分段线性刚度NES的参数,通过数值仿真方法计算得到主结构加速度响应幅值降低了47%。 | 崔泰毓 张雷 贾学志 魏磊 | 2020 | 现代电子技术2020，43，24： | 0 |
| 9 | A Supersonic Aerodynamic Energy Harvester:A Functionally Graded Material Beam with a Giant Magnetostrictive Thin Film显示文摘In this study,a simply supported functionally graded material beam with a giant magnetostrictive thin film(GMF)was selected as an energy harvester.Based on the theory of large deformation and the Villari effect of GMF,piston theory was used to simulate the dynamic equation of the whole structure under supersonic aerodynamic pressure and in a thermal environment by using Hamilton^principle,and the energy harvesting effect of GMF was simulated by using a Runge-Kutta algorithm.Below the critical flutter velocity,the maximum voltage output and energy harvesting results were discussed as they were affected by external factors such as the geometric model of structure parameters,slenderness ratio,gradient index,number of turns of an electromagnetic coil,airflow velocity,and temperature.The electromechanical coupling coefficient/C33 was 71%.The results show that this proposed harvester can achieve an optimal harvesting effect by adjusting the parameters appropriately,and collect energy in thermal and supersonic environments using the GMF,which provides power to sensors of the health monitoring system of the aircraft’s own structure. | Zhengqi Qin Weijiao Chen Jian Zang Yewei Zhang | 2022 | Acta Mechanica Solida Sinica2022，35，1： | 0 |
| 10 | 冲击载荷下分段线性刚度能量阱的优化研究显示文摘分段线性刚度能量阱是非线性能量阱的一种,属于被动减振装置,它可以通过能量定向转移现象快速耗散主结构的振动能量。对冲击载荷下分段线性刚度能量阱能量耗散效率进行了优化研究,通过复变平均法推导了耦合分段线性刚度能量阱的二自由度系统在冲击载荷下的慢变方程,使用多项式近似的方法得到了慢不变流形不稳定点的近似表达式,以此建了以能量阱能量耗散效率为目标的优化模型,并对该模型的有效性进行了实验验证。结果表明,该研究优化模型建立较为合理,实验结果证明了优化参数的有效性,分段线性刚度能量阱有效提升了系统的能量耗散速率。 | 崔泰毓 张雷 贾学志 魏磊 | 2021 | 振动与冲击2021，40，10： | 0 |
| 11 | Numerical and Experimental Investigation on Heat Transfer Performance of a Solar Single Storage Tank显示文摘The single-tank latent heat thermal energy storage(LHTES)of solar energy mainly consists of two modules:the first one is the phase change material(PCM)module heated by solar energy;the second is a module of heat transfer between melted PCM and the user’s low-temperature water.This paper mainly focuses on the former one.To investigate the heat transfer performance of the paraffin-based solar single storage tank and find a more suitable experimental configuration,as basic research work,we established a single-tank thermal storage platform and then conducted a numerical simulation on the heat transfer process with Fluent.The result of numerical simulation shows that the test situation was basically reflected and the data agreed well with the experiment results.The numerical simulation analysis is accurate and the method is reliable.To obtain the heat transfer performance of paraffin in a single tank and strengthen heat transfer,the aspect ratio,the melting temperature of paraffin,and the heating power of the electric heater were analyzed based on simulation.The results show that the heat transfer gets more uniform when the aspect ratio is lower.This results in an increase in the liquid fraction of 61.83%to 76.47%one hour after heating when the aspect ratio of the tank reduced from 2.8 to 1.1.The higher the melting temperature of paraffin,the longer it takes for PCM to reach a stable state.And the curvature of liquid heating is greater than that of solid heating at the bottom layer.Under the constant total work,the heating power has little effect on the heat transfer performance of the paraffin.This study will provide some reference value for the optimization design of single-tank LHTES systems in the future. | MAO Qianjun LI Ying ZHANG Yamei ZHANG Chunzhi | 2021 | Journal of Thermal Science2021，30，5： | 0 |
| 12 | Suppressing nonlinear aeroelastic response of laminated composite panels in supersonic airflows using a nonlinear energy sink显示文摘This paper proposes using a Nonlinear Energy Sink(NES) to suppress the nonlinear aeroelastic response of laminated composite panels in supersonic airflows. Relevant aeroelastic equations are established using Hamilton’s principle and a finite element approach, drawing upon Von Karman’s large deflection theory and first order piston theory. The idea of the NES suppression region is proposed and the effects of NES parameters on the NES suppression region are studied in detail. The results show that the nonlinear aeroelastic responses of the panel can be completely suppressed by the Transient Resonance Capture(TRC);the appropriate NES parameter values can increase the critical dynamic pressure for flutter and suppress the nonlinear aeroelastic response effectively. Increasing the mass ratio of the NES can improve the NES suppression region;the nonlinear stiffness coefficient and damping of the NES within a specific range can suppress the nonlinear aeroelastic response. The most effective installation position for a NES is in a specific region behind the center-line of the panel in the direction of the airflow. | Jian ZHOU Minglong XU Zhichun YANG Yingsong GU | 2021 | Chinese Journal of Aeronautics2021，34，2： | 0 |
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