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| 1 | Bio-inspired polygonal skeleton structure for vibration isolation:Design,modelling,and experiment显示文摘Inspired by the safe landing of a cat falling from a high altitude,a bio-inspired polygonal skeleton(BIPS) structure is proposed,and its nonlinear characteristics are systematically studied to explore its potential application in the suppression of vibration. The polygon is formed by the skeleton structure of the cat’s entire body and the ground. The BIPS system consists of two symmetrical bionic legs with three robs(as skeleton) and four horizontal springs(as muscle). Two bionic legs are connected through the bearing platform(as spine),which could adjust the distance between the two bionic legs. A theoretical model is developed to characterize its stiffness nonlinearity through geometrical and mechanical analysis. Parameter analysis reveals that the BIPS structure has diverse stiffness,including nonlinear positive stiffness and negative stiffness. By imitating adjustment of leg posture and telescopic function of the spine(control the distance between legs),these flexible stiffness properties can be adjusted by structure parameters. In addition,the load capacity and working range can also be designed by the length of the bars,the initial angle,the mounting position,and the spring stiffness. The experimental setup is established,and the vibration isolation performance under various excitation is tested. The experimental results verify the accuracy of the dynamic model and also show that the proposed BIPS structure can suppress the vibration effectively under a variety of excitations. These peculiarities may provide potential possibility of an innovative approach to passive vibration control and isolation. | YAN Ge WANG Sen ZOU HongXiang ZHAO LinChuan GAO QiuHua ZHANG WenMing | 2020 | Science China(Technological Sciences)2020，63，12： | 5 |
| 2 | 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 |
| 3 | Nonlinear characterization and performance optimization for broadband bistable energy harvester显示文摘As two crucial indicators of bistable energy harvesting performance,band width and power amplitude are simultaneously investigated for obtaining the synergy effect.Toward this goal,a nonlinear electromechanical-coupled distributed-parameter model of the bistable piezoelectric energy harvester is established.Based on the electromechanical decoupled method,approximate higher-order analytical solutions of the beam displacement,harvested power and effective bandwidth are derived.The cubic-function discriminant of the analytical solution is introduced to determine the nonlinear excitation-frequency boundaries of multiple solutions and power peak.The stability of the multiple solutions is analyzed through Jacobi matrix of the modulation equation.Superharmonic resonance is notified.Upward and downward sweep experiments and numerical solutions of time history curves,phase portraits and power spectra confirm the analytical findings.To realize optimized broadband energy harvesting,the parametric study on the coefficients of the linear and cubic elastic external forces with the corresponding optimal load resistance is performed.For the nonlinear hardening case,more positive linear coefficient is preferred.For the nonlinear softening case,the cubic coefficient slightly larger than its optimal value is recommended at each given linear coefficient.By tuning the load resistance and linear and cubic coefficients of the external force,broadband bistable energy harvesting with optimized power is realized. | Ting Tan Zhimiao Yan Kejing Ma Fengrui Liu Linchuan Zhao Wenming Zhang | 2020 | Acta Mechanica Sinica2020，36，3： | 1 |
| 4 | Metabolism of hydrogen peroxide in univoltine and polyvoltine strains of silkworm ( Bombyx mori )显示文摘 | Linchuan Zhao Liangen Shi | 2009 | Comparative Biochemistry and Physiology Part B2009，，4： | 1 |
| 5 | Enhanced galloping energy harvester with cooperative mode of vibration and collision显示文摘The low power and narrow speed range remain bottlenecks that constrain the application of small-scale wind energy harvesting.This paper proposes a simple,lowcost,and reliable method to address these critical issues.A galloping energy harvester with the cooperative mode of vibration and collision(GEH-VC)is presented.A pair of curved boundaries attached with functional materials are introduced,which not only improve the performance of the vibration energy harvesting system,but also convert more mechanical energy into electrical energy during collision.The beam deforms and the piezoelectric energy harvester(PEH)generates electricity during the flow-induced vibration.In addition,the beam contacts and separates from the boundaries,and the triboelectric nanogenerator(TENG)generates electricity during the collision.In order to reduce the influence of the boundaries on the aerodynamic performance and the feasibility of increasing the working area of the TENG,a vertical structure is designed.When the wind speed is high,the curved boundaries maintain a stable amplitude of the vibration system and increase the frequency of the vibration system,thereby avoiding damage to the piezoelectric sheet and improving the electromechanical conversion efficiency,and the TENG works with the PEH to generate electricity.Since the boundaries can protect the PEH at high wind speeds,its stiffness can be designed to be low to start working at low wind speeds.The electromechanical coupling dynamic model is established according to the GEH-VC operating principle and is verified experimentally.The results show that the GEH-VC has a wide range of operating wind speeds,and the average power can be increased by 180%compared with the traditional galloping PEH.The GEH-VC prototype is demonstrated to power a commercial temperature sensor.This study provides a novel perspective on the design of hybrid electromechanical conversion mechanisms,that is,to combine and collaborate based on their respective characteristics. | Qiong WANG Zewen CHEN Linchuan ZHAO Meng LI Hongxiang ZOU Kexiang WEI Xizheng ZHANG Wenming ZHANG | 2022 | Applied Mathematics and Mechanics(English Edition)2022，43，7： | 0 |
| 6 | Promoting conservation or change? The UNESCO label of world heritage (re)shaping urban morphology in the Old Town of Lijiang, China显示文摘The UNESCO label of World Heritage can attract a high number of tourists to heritage properties for their Outstanding Universal Values(OUV).Although international studies have demonstrated the World Heritage system can contribute to stimulating cultural tourism and boosting the local economy,how this heritage-led development process promotes urban conservation and morphological changes in cities is yet to be explored adequately.This paper aims to explore the urban morphology of a historic Chinese city after its inscription on the UNESCO World Heritage List,taking the Old Town of Lijiang as case.The methods of spatial plan analysis and discourse analysis are used to analyse the data.The research findings have demonstrated that,theoretically,the Conzenian approach of urban morphology can be an effective framework for World Heritage OUV-monitoring.Methodologically,the analysis of spatial plans and multi-stakeholder interviews can reveal local urban morphology from macro to micro levels.Case-specifically in Lijiang,urban physical characteristics and building structures have been well maintained while traditional social fabric and neighbourhood networks have almost vanished.This research has incorporated the urban morphology approach into(world)heritage management in China,as well as worldwide,in order to maintain the balance between urban conservation and economic growth. | Ji Li Tianchen Dai Shengchen Yin Yiqing Zhao Deniz Ikiz Kaya Linchuan Yang | 2022 | Frontiers of Architectural Research2022，11，6： | 0 |
| 7 | Assessing Landsat-8 and Sentinel-2 spectral-temporal features for mapping tree species of northern plantation forests in Heilongjiang Province,China显示文摘Background:Accurate mapping of tree species is highly desired in the management and research of plantation forests,whose ecosystem services are currently under threats.Time-series multispectral satellite images,e.g.,from Landsat-8(L8)and Sentinel-2(S2),have been proven useful in mapping general forest types,yet we do not know quantitatively how their spectral features(e.g.,red-edge)and temporal frequency of data acquisitions(e.g.,16-day vs.5-day)contribute to plantation forest mapping to the species level.Moreover,it is unclear to what extent the fusion of L8 and S2 will result in improvements in tree species mapping of northern plantation forests in China.Methods:We designed three sets of classification experiments(i.e.,single-date,multi-date,and spectral-temporal)to evaluate the performances of L8 and S2 data for mapping keystone timber tree species in northern China.We first used seven pairs of L8 and S2 images to evaluate the performances of L8 and S2 key spectral features for separating these tree species across key growing stages.Then we extracted the spectral-temporal features from all available images of different temporal frequency of data acquisition(i.e.,L8 time series,S2 time series,and fusion of L8 and S2)to assess the contribution of image temporal frequency on the accuracy of tree species mapping in the study area.Results:1)S2 outperformed L8 images in all classification experiments,with or without the red edge bands(0.4%–3.4%and 0.2%–4.4%higher for overall accuracy and macro-F1,respectively);2)NDTI(the ratio of SWIR1 minus SWIR2 to SWIR1 plus SWIR2)and Tasseled Cap coefficients were most important features in all the classifications,and for time-series experiments,the spectral-temporal features of red band-related vegetation indices were most useful;3)increasing the temporal frequency of data acquisition can improve overall accuracy of tree species mapping for up to 3.2%(from 90.1%using single-date imagery to 93.3%using S2 time-series),yet similar overall accuracies were achieved using S2 time-series(93.3%)and the fusion of S2 and L8(93.2%).Conclusions:This study quantifies the contributions of L8 and S2 spectral and temporal features in mapping keystone tree species of northern plantation forests in China and suggests that for mapping tree species in China's northern plantation forests,the effects of increasing the temporal frequency of data acquisition could saturate quickly after using only two images from key phenological stages. | Mengyu Wang Yi Zheng Chengquan Huang Ran Meng Yong Pang Wen Jia Jie Zhou Zehua Huang Linchuan Fang Feng Zhao | 2022 | Forest Ecosystems2022，9，3： | 0 |
| 8 | Multi-blade rubbing characteristics of the shaft-disk-blade-casing system with large rotation显示文摘Blade rubbing faults cause detrimental impact on the operation of aeroengines. Most of the existing studies on blade rubbing in the shaft-disk-blade-casing(SDBC) system have overlooked the elastic deformation of the blade, while some only consider the whirl of the rotor, neglecting its spin. To address these limitations, this paper proposes a dynamic model with large rotation for the SDBC system. The model incorporates the spin and whirl of the rotor, enabling the realistic reproduction of multiblade rubbing faults. To verify the accuracy of the SDBC model with large rotation and demonstrate its capability to effectively consider the rotational effects such as the centrifugal stiffening and gyroscopic effects, the natural characteristics and dynamic responses of the proposed model are compared with those obtained from reported research and experimental results. Furthermore, the effects of the rotating speed, contact stiffness,and blade number on the dynamic characteristics of the SDBC system with multi-blade rubbing are investigated. The results indicate that the phase angle between the rotor deflection and the unbalance excitation force increases with the increasing rotating speed,which significantly influences the rubbing penetration of each blade. The natural frequency of the SDBC system with rubbing constrain can be observed in the acceleration response of the casing and the torsional response of the shaft, and the frequency is related to the contact stiffness. Moreover, the vibration amplitude increases significantly with the product of the blade number under rubbing, and the rotating frequency approaches the natural frequency of the SDBC system. The proposed model can provide valuable insight for the fault diagnosis of rubbing in bladed rotating machinery. | Zhiyuan WU Linchuan ZHAO Han YAN Ge YAN Ao CHEN Wenming ZHANG | 2024 | Applied Mathematics and Mechanics(English Edition)2024，45，1： | 0 |
| 9 | Enhanced triboelectric output of PDMS-based composite film with bi-material filling and surface patterning显示文摘Triboelectric nanogenerators(TENGs)are highly promising energy-harvesting devices that exhibit considerable potential for use in self-powered wearable electronics.Nano/microfillers and surface microstructure modification have been proposed to improve the triboelectric performance of TENGs.In this work,performance-enhanced flexible polydimethylsiloxane(PDMS)was developed through bi-material(reduced graphene oxide/fluorinated ethylene propylene,rGO/FEP)modification and filtrationmembrane-patterned surface microstructure.The rGO/FEP with high charge-inducing and-trapping capabilities can be used as the dielectric-enhanced filler for improving triboelectricity.Ordered micro-dents of 5–50μm are created on the modified PDMS surface with an increased contact area of TENG.Compared with the pure PDMS,the modified PDMS film-based TENG could deliver a substantial enhancement in power density(0.87 mW cm^(-2))by 28 times.Further,the versatility of this device is demonstrated in human activity monitoring and capacitor charging.This work provided a simple,high-tunability,and scalable approach for improving the output performance of TENGs for biomechanical energy-harvesting devices that can be integrated into self-powering wearable electronics. | LIU Sheng LIAO SiHua LIU Dan ZHAO Rong ZHOU Teng YAN WenYuan WEI KeXiang ZOU HongXiang ZHAO LinChuan | 2023 | Science China(Technological Sciences)2023，66，10： | 0 |
| 10 | Spatio-temporal characteristics of regional sustainable economic growth drivers of China显示文摘Intellectual capital(IC)has become a universal performance indicator for the socioeconomic development of countries and regions.Based on a review ofnational intellectualcapital(NIC)and regional intellectualcapital(RIC)evaluation literature,we used the regional intellectualcapitalindicator(RICI)as a model for China’s RIC evaluation to indirectly understand China’s potential economic growth drivers.Specifically,we collected statisticaldata of31 provinces(including municipalities and autonomous regions)in China from 2004 to 2016to measure RICI and analyze its dynamic characteristics from temporal and spatial perspectives.In this paper,Delphi analysis was used to construct RICI model,and cluster analysisand exploratory spatial data analysis were used to analyze the temporal and spatial characteristics of RICI in China.The results showedthat RICI,which represents China’s overall economic growth drivers,increases annuallyand is consistent with economic developmentlevelduring the study period.Regarding the geo-spatial space,RICI follows the trend of“high in the east and low in the west”,gradually decreasing from eastern to western China.ForRIC structure,the shape of the radar chart of IC structure located in the eastern coastal areas is usually biased towards strong external relational capital,while that in western China is generally biased towards structural capital.For spatial correlation,China’s RICI has dependence on geographical adjacent space and economic space.Our research can provide policy suggestions for the sustainable development of regional economy from an IC perspective. | WANG Linchuan WU Cisheng ZHAO Xuyang LIU Duanyong ZHANG Tao | 2021 | Regional Sustainability2021，2，3： | 0 |
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