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Time-history performance optimization of flapping wing motion using a deep learning based prediction model

Chinese Journal of Aeronautics 2024年第5期37卷 317-331页

作者： Tianqi WANG Liu LIU Jun LI Lifang ZENG School of Aeronautics and Astronautics Zhejiang UniversityHangzhou 310027China huanjiang laboratory Zhuji 311800China

Flapping Wing Micro Aerial Vehicles(FWMAVs)have caused great concern in various fields because of their high efficiency and *** wing motion is a very important factor that affects the performance of the aircraft,and previous works have always focused on the time-averaged performance ***,the time-history performance is equally important in the design of motion mechanism and flight control *** this paper,a time-history performance optimization framework based on deep learning and multi-island genetic algorithm is presented,which is designed in order to obtain the optimal two-dimensional flapping wing ***,the training dataset for deep learning neural network is constructed based on a validated computational fluid dynamics *** aerodynamic surrogate model for flapping wing is obtained after the convergence of *** surrogate model is tested and proved to be able to accurately and quickly predict the time-history curves of lift,thrust and ***,the optimization framework is used to optimize the flapping wing motion in two specific cases,in which the optimized propulsive efficiencies have been improved by over 40%compared with the ***,a dimensionless parameter C_(variation)is proposed to describe the variation of the time-history characteristics,and it is found that C_(variation)of lift varies significantly even under close time-averaged *** the importance of time-history performance in practical applications,the optimization that integrates the propulsion efficiency as well as C_(variation)is carried *** final optimal flapping wing motion balances good time-averaged and time-history performance.

关键词： FWMAV Flapping wing motion Deep learning Unsteady aerodynamic performance Optimization Time-history curve

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Analysis of Piezoelectric Semiconductor Structures Considering Both Physical and Geometric Nonlinearities

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Acta Mechanica Solida Sinica 2024年第1期37卷 72-81页

作者： Zhengguang Xiao Shuangpeng Li Chunli Zhang Key laboratory of Soft Machines and Smart Devices of Zhejiang Province Department of Engineering MechanicsZhejiang UniversityHangzhou 310027China huanjiang laboratory Zhuji 311816China

Piezoelectric semiconductors(PSs),such as ZnO and GaN,known as the third-generation semiconductors,have promising applications in electronic and optoelectronic devices due to the coexistence and interaction of piezoelectricity and semiconductor *** modeling of PS structures under external loads,such as thermal and mechanical loads,plays a crucial role in the design of PS *** this work,we propose a nonlinear fully coupling theoretical model and investigate the multi-field coupling behaviors of PS structures and PN junctions under thermal and mechanical loads,considering physical and geometric *** electromechanical and semiconducting behaviors of a PS rod-like structure with flexural deformations under different combinations of temperature changes and mechanical loads are *** tuning effect of temperature changes and mechanical loads on multi-field coupling behaviors of PSs is *** current–voltage characteristics of PS PN junctions are studied under different combinations of temperature changes and mechanical *** obtained results are helpful for the development of novel PS devices.

关键词： Piezoelectric semiconductor Nonlinearity Multi-field Coupling Tuning

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A feedback control method for phase signal demodulation in fber-optic hydrophones

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Applied Mathematics and Mechanics(English Edition) 2024年第3期45卷 515-528页

作者： Zhiqiang LIU Lei XIA Qiangfeng LYU Bin WU Ronghua HUAN Zhilong HUANG Department of Mechanics Key Laboratory of Soft Machines and Smart Devices of Zhejiang ProvinceZhejiang UniversityHangzhou 310000China huanjiang laboratory Zhuji 311899Zhejiang ProvinceChina Advanced Technology Research Institute Zhejiang UniversityHangzhou 310000China

In the realm of acoustic signal detection,the identification of weak signals,particularly in the presence of negative signal-to-noise ratios,poses a significant *** challenge is further heightened when signals are acquired through fiber-optic hydrophones,as these signals often lack physical significance and resist clear systematic *** processing methods,e.g.,low-pass filter(LPF),require a thorough understanding of the effective signal bandwidth for noise reduction,and may introduce undesirable time *** paper introduces an innovative feedback control method with dual Kalman filters for the demodulation of phase signals with noises in fiber-optic hydrophones.A mathematical model of the closed-loop system is established to guide the design of the feedback control,aiming to achieve a balance with the input phase *** dual Kalman filters are instrumental in mitigating the effects of signal noise,observation noise,and control execution noise,thereby enabling precise estimation for the input phase *** effectiveness of this feedback control method is demonstrated through examples,showcasing the restoration of low-noise signals,negative signal-to-noise ratio signals,and multi-frequency *** research contributes to the technical advancement of high-performance devices,including fiber-optic hydrophones and phase-locked amplifiers.

关键词： feedback control method fiber-optic hydrophone acoustic signal detection phase signal

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Towards Achieving Carbon Neutrality: The Role of Vegetation Restoration in Karst Regions of Southwest China

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Journal of Earth Science 2024年第3期35卷 1044-1048页

作者： Yuemin Yue Lu Wang Xinbao Zhang Kelin Wang Guangxi Key laboratory of Karst Ecological Processes and Services Institute of Subtropical AgricultureChinese Academy of SciencesChangsha 410125China huanjiang Observation and Research Station for Karst Ecosystem Chinese Academy of SciencesHuanjiang 547100China Chengdu Institute of Mountain Disasters and Environment Chinese Academy of Sciences&Ministry of Water ResourcesChengdu 610041China

Karst regions of Southwest China become a hotspot for global greening through large-scale vegetation restoration in recent two ***,the unique,fragile geological setting of carbonate rocks affects the sustainability of vegetation ***,we summarize and evaluate the impacts of the rock and soil compositions of karst landscapes on the types and quality of vegetation *** introduce the concept of“soil mass”and establish its relationship with aboveground vegetation biomass across varying degrees of rocky *** mineral nutrients and soil mass constrain the potential of vegetation carbon sequestration in karst *** enhance the sustainability of vegetation restoration and carbon sequestration under karst geological constraints,we suggest to push ecological intensification of tree plantations and optimize the zoning and classification of rocky desertification treatment,and these restoration initiatives will foster vegetation restoration to serve as a pivotal pathway towards carbon neutrality.

关键词： soil karst Restoration

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Soil properties and not plant factors affect both abundant and rare microbial taxa after thinning in a mixed stand of Cunninghamia lanceolata and Sassafras tzumu

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Journal of Forestry Research 2024年第2期35卷 81-94页

作者： Wanxia Peng Tongqing Song Hu Du Feng Wang Fuping Zeng Yang Wang Shulin Chen Yinzhu Chen Key laboratory of Agro‑Ecological Processes in Subtropical Region Institute of Subtropical AgricultureChinese Academy of SciencesChangsha 410125People’s Republic of China Guangxi Industrial Technology Research Institute for Karst Desertification Control Nanning 530001People’s Republic of China huanjiang Observation and Research Station for Karst Ecosystems Institute of Subtropical AgricultureChinese Academy of SciencesChangsha 410125People’s Republic of China Hubei Ecology Polytechnic College Wuhan 430200People’s Republic of China Hubei Tongshan Damushan State Forest Farm Tongshan 437652People’s Republic of China

Thinning is an effective management step for sustainable forest development,yet less attention is paid to the restoration of soil microbiota after *** this study,both abundant and rare soil microbial communities(i.e.,bacterial,fungal),were evaluated under various thinning treatments in a mixed stand of Cunninghamia lanceolata and Sassafras tzumu using Mi Seq *** did not significantly change either abundant or rare bacterial and fungal community composition,but affected their alpha *** Shannon–Wiener indexes of rare fungal taxa under medium thinning were significantly lower than in the light thinning(P<0.05 level).Xanthobacteraceae dominated the abundant bacterial taxa,and Saitozyma and Mortierlla the abundant fungal *** most common rare bacterial taxa varied;there was no prevalent rare fungal taxa under different *** addition,soil available nitrogen,total phosphorus,and p H had significant effects on rare bacterial ***,especially available phosphorus,but not nitrogen,affected abundant and rare soil *** results indicate that soil properties rather than plant factors affect abundant and rare microbial communities in soils of mixed ***,through mediating soil properties,influences both abundant and rare bacterial and fungal communities in the mixed *** and *** stand.

关键词： Diversity Abundant taxa Rare taxa Thinning Mixed stand

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Environmental and spatial contributions to tree community assembly across life stages and scales in evergreen-deciduous broadleaf karst forests,southwest China

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林业研究:英文版 2023年第5期34卷 1323-1331页

作者： Liang Su Hu Du Fuping Zeng Wanxia Peng Hua Wang Kelin Wang Menzhen Lu Tongqing Song Key laboratory of Agro-Ecological Processes in Subtropical Region Institute of Subtropical AgricultureChinese Academic of SciencesChangshaPeople’s Republic of China Guangxi Key laboratory of Karst Ecological Processes and Services Huanjiang Observation and Research Station of Karst EcosystemChinese Academic of SciencesHuanjiangPeople’s Republic of China College of Resources and Environment Hunan Agricultural UniversityChangshaPeople’s Republic of China

Spatial and environmental processes are two ecological processes that have attracted considerable attention in plant community assembly,depending on sampling scale and life ***,the processes that determine community assembly have not been studied in the karst region of southwest *** this study,a 25-ha(500 m×500 m)monitoring plot within the subtropical climax forest in the karst region was established and canonical correspondence analysis was used to reveal the effects of topography and soil on the spatial patterns of tree community *** study suggests that spatial processes dominate species composition and the combined effects of spatial and environmental processes play an important *** interpretation rate increases with enlarging the sampling ***,the pattern of variation partitioning was similar in different life *** variables significantly affected species composition at different sampling sizes and life histories and had a higher interpretation rate of species composition on larger s ampling *** wetness index was the most important variable to explain species composition of the environmental *** results suggest that it is necessary to consider the relative importance of environmental and spatial factors on community assembly to better understand,conserve,and manage subtropical karst forests.

关键词： Species composition Spatial distribution Variation partitioning Community assembly Karst ecosystems

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Methods for cleaning turbid nematode suspensions collected from different land-use types and soil types

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Soil Ecology Letters 2022年第4期4卷 429-434页

作者： Jie Zhao Kelin Wang Key laboratory of Agro-ecological Processes in Subtropical Region Institute of Subtropical AgricultureChinese Academy of SciencesChangsha 410125China huanjiang Observation and Research Station for Karst Ecosystems Chinese Academy of SciencesHuanjiang 547100China

Soil nematodes are useful ecological indicators and can be extracted from soil by a variety of *** the extracted nematode samples(suspensions)can be quite turbid(i.e.,they contain soil particles and organic particles in addition to nematodes),quantitative and taxonomic analyses of the nematodes by microscopy can be *** this study,the following three methods for cleaning turbid suspensions obtained from Baermann funnels were assessed:repeated centrifugation at 692.5´g for 1 min,repeated settling at low-temperature(4°C)for 24 h,and a combination of low-temperature settling and *** were extracted with Baermann funnels from soil samples collected from four land-use types(since land-use type can affect the turbidity of nematode suspensions),and the resulting suspensions were cleaned by the three methods before nematode abundance was *** a control,samples(i.e.,suspensions)were simply diluted with water,and nematodes were counted in the entire *** results showed that,within each land-use type,nematode abundance did not significantly differ between the control and the three cleaning *** across all land-use types,however,the nematode recovery rate was slightly higher with repeated centrifugation than with the other two cleaning ***,the proposed methods are sound for cleaning turbid nematode suspensions,and repeated centrifugation is the most efficient method.

关键词： Soil nematodes Purification method Centrifugation Low-temperature settlement Luvisols Acrisols

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Novel mode-coupling vibrations of AlN thin film bulk acoustic resonator operating with thickness-extensional mode

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Applied Mathematics and Mechanics(English Edition) 2023年第12期44卷 2187-2206页

作者： Zinan ZHAO Nian LI Yilin QU Weiqiu CHEN Key laboratory of Soft Machines and Smart Devices of Zhejiang Province and Department of Engineering Mechanics Zhejiang UniversityHangzhou 310027China huanjiang laboratory Zhuji 311816Zhejiang ProvinceChina Suzhou HunterSun Electronics Co. Ltd.Suzhou 215124Jiangsu ProvinceChina School of Marine Science and Technology Northwestern Polytechnical UniversityXi’an 710072China

The dispersion curves of bulk waves propagating in both AlN and ZnO film bulk acoustic resonators(FBARs)are presented to illustrate the mode flip of the thickness-extensional(TE)and 2nd thickness-shear(TSh2)*** frequency spectrum quantitative prediction(FSQP)method is used to solve the frequency spectra for predicting the coupling strength among the eigen-modes in AlN and ZnO *** results elaborate that the flip of the TE and TSh2 branches results in novel self-coupling vibration between the small-wavenumber TE and large-wavenumber TE modes,which has never been observed in the ZnO ***,the mode flip leads to the change in the relative positions of the frequency spectral curves about the TE cut-off *** obtained frequency spectra can be used to predict the mode-coupling behaviors of the vibration modes in the AlN *** conclusions drawn from the results can help to distinguish the desirable operation modes of the AlN FBAR with very weak coupling strength from all vibration modes.

关键词： AlN film mode flip frequency spectrum quantitative prediction(FSQP) dispersion curve mode-coupling vibration

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In-situ electrochemical study on the eff ects of Fe(Ⅲ)on kinetics of pyrite acidic pressure oxidation

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Acta Geochimica 2024年第4期43卷 814-825页

作者： Yu Zhang Can Cui Sen Lin Heping Li Lian Yang Yadian Xie Hailiang Hu Lingyun Zhou huanjiang Wang Chunyan Li School of Chemical Engineering Guizhou Minzu UniversityGuiyang 550025China Key laboratory of High-Temperature and High-Pressure Study of the Earth’s Interior Institute of GeochemistryChinese Academy of SciencesGuiyang 550081China

Fe(Ⅲ)has been proved to be a more eff ective oxidant than dissolved oxygen at ambient temperature,however,the role of Fe(Ⅲ)in pyrite acidic pressure oxidation was rarely discussed so *** this paper,in-situ electrochemical investigation was performed using a flow-through autoclave system in acidic pressure oxidation *** results illustrated that increasing Fe(Ⅲ)concentrations led to raising in redox potential of the solution,and decreased passivation of pyrite caused by deposition of elemental *** of Fe(Ⅲ)at pyrite surface was a fast reaction with low activation energy,it was only slightly promoted by rising ***,the oxidation rate of pyrite at all investigated Fe(Ⅲ)concentrations increased obviously with rising temperatures,the anodic reaction was the rate-limiting step in the overall *** energy of pyrite oxidation decreased from 47.74 to 28.79 kJ/mol when Fe(Ⅲ)concentration was increased from 0.05 to 0.50 g/L,showing that the reaction kinetics were limited by the rate of electrochemical reaction at low Fe(Ⅲ)concentrations,while,it gradually turned to be diffusion control with increasing Fe(Ⅲ)concentrations.

关键词： Pyrite Pressure oxidation Fe(Ⅲ) In-situ electrochemistry Hydrothermal experiment

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Responses of Spatial-temporal Variation of Karst Ecosystem Service Values to Landscape Pattern in Northwest of Guangxi,China

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Chinese Geographical Science 2011年第4期21卷 446-453页

作者： ZHANG Mingyang WANG Kelin LIU Huiyu ZHANG Chunhua Key laboratory for Agro-ecological Processes in Subtropical Region Institute of Subtropical AgricultureChinese Academy of SciencesHunan 410125China huanjiang Observation and Research Station for Karst Ecosystems Chinese Academy of SciencesHuanjiang 547100China College of Geography Science Nanjing Normal UniversityNanjing 210046China

The responses of spatiotemporal variation of ecosystem service values (ESVs) to landscape pattern from 1985 to 2005 in a typical Karst area of the northwest Guangxi Zhuang Autonomous Region,China,were examined us-ing remote sensing and geographic information system techniques in this *** total ecosystem service values de-clined significantly from 1985 to 1990,and then increased slowly from 1990 to 2005,almost equaled to the 1985 *** ecosystem service values tended to decline from the west to the east and from mountainous regions to peak-cluster depression areas in 1985,1990,2000 and 2005 *** the period from 1985 to 2005,the ecosystem ser-vice values have increased in the middle and eastern parts of the study *** pattern indices,such as total area,largest patch index,contagion,aggregative index,effective mesh and proportion of like adjacencies,are significantly correlated with ecosystem service *** suggests that ecosystem service values tend to increase with the growth of patch area and patch ***,there are negative correlations between ecosystem service values and landscape pattern indices,such as division index and patch *** indicates that ecosystem service values decrease with patch fragmentation and patch size *** ecosystem conditions in the typical Karst area have been improved because of the control measures of rocky *** is important to protect key landscape types,such as woodland,shrub and grassland,and to increase patch size and connectivity to avoid further ***,it is necessary to reduce disturbances to ensure the growth of ecosystem service values and to facilitate the sustainable development in this region.

关键词： landscape pattern ecosystem service values (ESVs) landscape indices Karst Guangxi

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