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IEEE/CAA Journal of Automatica Sinica 2020年第6期7卷 1575-1584页

作者： Tinghua Li qinghua yang Xiaowei Tu Bin Ren School of Mechatronic Engineering and Automation Shanghai UniversityShanghai 200444China

In this paper,we propose an improved torque sensorless speed control method for electric assisted bicycle,this method considers the coordinate conversion.A low-pass filter is designed in disturbance observer to estimate and compensate the variable disturbance during cycling.A DC motor provides assisted power driving,the assistance method is based on the realtime wheel angular velocity and coordinate system *** effect of observer is proved,and the proposed method guarantees stability under *** is also compared to the existing methods and their performances are illustrated through *** proposed method improves the performance both in rapidity and stability.

关键词： Coordinate conversion disturbance observer electric assisted power inertial measurement unit speed control

Wintertime Arctic Sea-Ice Decline Related to Multi-Year La Niña Events

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Advances in Atmospheric Sciences 2024年第9期41卷 1680-1690页

作者： Wenxiu ZHONG Qian SHI qinghua yang Jiping LIU Song yang School of Atmospheric Sciences Sun Yat-sen Universityand Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)Zhuhai 519082China State Key Laboratory of Satellite Ocean Environment Dynamics Second Institute of OceanographyMinistry of Natural ResourcesHangzhou 310012China Guangdong Province Key Laboratory for Climate Change and Natural Disaster Studies Sun Yat-sen UniversityGuangzhou 510275China

Arctic sea ice has undergone a significant decline in the Barents-Kara Sea(BKS)since the late *** studies have shown that the decrease in sea ice caused by increased poleward moisture transport is modulated by tropical sea temperature changes(mainly referring to La Niña events).The occurrence of multi-year La Niña(MYLA)events has increased significantly in recent decades,and their impact on Arctic sea ice needs to be further *** this study,we investigate the relationship between sea-ice variation and different atmospheric diagnostics during MYLA and other La Niña(OTLA)*** decline in BKS sea ice during MYLA winters is significantly stronger than that during OTLA *** is because MYLA events tend to be accompanied by a warm Arctic-cold continent pattern with a barotropic high pressure blocked over the Urals ***,more frequent northward atmospheric rivers intrude into the BKS,intensifying longwave radiation downward to the underlying surface and melting the BKS sea ***,in the early winter of OTLA years,a negative North Atlantic Oscillation presents in the high latitudes of the Northern Hemisphere,which obstructs the atmospheric rivers to the south of *** infer that such a different response of BKS sea-ice decline to different La Niña events is related to stratospheric *** the rapid climate changes in the past,more frequent MYLA events may account for the substantial Arctic sea-ice loss in recent decades.

关键词： Arctic sea ice multi-year ENSO Ural blocking atmospheric river Barents-Kara Sea

Evaluation of Arctic Sea-ice Cover and Thickness Simulated by MITgcm

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Advances in Atmospheric Sciences 2021年第1期38卷 29-48页

作者： Fei ZHENG Yue SUN qinghua yang Longjiang MU International Center for Climate and Environment Science Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science and TechnologyNanjing 210044China University of Chinese Academy of Sciences Beijing 100049China School of Atmospheric Sciences Sun Yat-sen Universityand Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)Zhuhai 519082China Alfred Wegener Institute Helmholtz Centre for Polar and Marine ResearchBremerhaven 27515Germany

A regional Arctic Ocean configuration of the Massachusetts Institute of Technology General Circulation Model(MITgcm)is applied to simulate the Arctic sea ice from 1991 to *** simulations are evaluated by comparing them with observations from different *** results show that MITgcm can reproduce the interannual and seasonal variability of the sea-ice extent,but underestimates the trend in sea-ice extent,especially in *** ice concentration and thickness distributions are comparable to those from the observations,with most deviations within the observational uncertainties and less than 0.5 m,*** simulated sea-ice extents are better correlated with observations in September,with a correlation coefficient of 0.95,than in March,with a correlation coefficient of ***,the distributions of sea-ice concentration are better simulated in March,with higher pattern correlation coefficients(0.98)than in *** the model underestimates the atmospheric influence on the sea-ice evolution in March,deviations in the sea-ice concentration arise at the ice edges and are higher than those in *** contrast,when the model underestimates the oceanic boundaries’influence on the September sea-ice evolution,disagreements in the distribution of the sea-ice concentration and its trend are found over most marginal seas in the Arctic *** uncertainties of the model,whereby it fails to incorporate the atmospheric information in March and oceanic information in September,contribute to varying model errors with the seasons.

关键词： Arctic sea ice MITgcm simulation and evaluation sources of model error

Influence of Surface Types on the Seasonality and Inter-Model Spread of Arctic Amplification in CMIP6

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Advances in Atmospheric Sciences 2023年第12期40卷 2288-2301页

作者： Yanchi LIU Yunqi KONG qinghua yang Xiaoming HU School of Atmospheric Sciences Sun Yat-sen University and Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)Zhuhai 519000China Guangdong Province Key Laboratory for Climate Change and Natural Disaster Studies Zhuhai 519000China

A robust phenomenon termed the Arctic Amplification(AA)refers to the stronger warming taking place over the Arctic compared to the global *** AA can be confirmed through observations and reproduced in climate model simulations and shows significant seasonality and inter-model *** study focuses on the influence of surface type on the seasonality of AA and its inter-model spread by dividing the Arctic region into four surface types:ice-covered,ice-retreat,ice-free,and *** magnitude and inter-model spread of Arctic surface warming are calculated from the difference between the abrupt-4×CO_(2)and pre-industrial experiments of 17 CMIP6 *** change of effective thermal inertia(ETI)in response to the quadrupling of CO_(2) forcing is the leading mechanism for the seasonal energy transfer mechanism,which acts to store heat temporarily in summer and then release it in *** ETI change is strongest over the ice-retreat region,which is also responsible for the strongest AA among the four surface *** lack of ETI change explains the nearly uniform warming pattern across seasons over the ice-free(ocean)*** to other regions,the ice-covered region shows the maximum inter-model spread in JFM,resulting from a stronger inter-model spread in the oceanic heat storage ***,the weaker upward surface turbulent sensible and latent heat fluxes tend to suppress the inter-model *** relatively small inter-model spread during summer is caused by the cancellation of the inter-model spread in ice-albedo feedback with that in the oceanic heat storage term.

关键词： Arctic amplification surface type dependence seasonal energy transfer effective thermal inertia

Effects of Load on Dry Sliding Wear Behavior of Mg–Gd–Zn–Zr Alloys

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Journal of Materials Science & Technology 2017年第7期33卷 645-651页

作者： Jie Zhang Xiaobo Zhang qinghua Liu Shujie yang Zhangzhong Wang School of Materials Science and Engineering Nanjing Institute of TechnologYNanjing 211167China Jiangsu-Key Laboratory of Advanced Structural Materials and APplication Technology Nanjing 211167China

Dry sliding wear tests on as-cast and T6-treated Mg-3Gd-1Zn-0.4Zr（wt%, GZ31K） and Mg-6Gd-1Zn-0.4Zr（wt%, GZ61K） alloys were performed using a ball-on-disk configuration at room temperature. Friction coefficient and wear rate of the alloys were measured under three different applied loads（50 N, 100 N, and 200 N, respectively）. Worn surface morphologies were analyzed using a scanning electron microscope（SEM） coupled with an energy dispersive spectrometer（EDS）. It is found that the friction coefficient of the alloys decreases with increasing load, except the as-cast GZ61 K. The wear rates of the as-cast Mg-Gd-Zn-Zr alloys increase with the increase of the load. However, the wear rates of the T6-treated Mg-Gd-Zn-Zr alloys first increase because of the participation of a large amount of needle-like precipitates, but then decline due to obvious work hardening. The wear mechanisms of abrasion, plastic deformation, oxidation, adhesion and delamination are detected. Abrasion dominates the wear mechanism under the low load; whereas, adhesion is the main wear mechanism under intermediate load, and plastic deformation has great effect on the wear rate under high applied load.

关键词： Magnesium alloys Applied load Wear and friction Wear mechanism

Charge Storage Properties of Aqueous Halide Supercapatteries with Activated Carbon and Graphene Nanoplatelets as Active Electrode Materials

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Energy & Environmental Materials 2021年第3期4卷 481-491页

作者： Bamidele Akinwolemiwa Chaohui Wei qinghua yang George Z.Chen International Doctoral Innovation Centre Faculty of Science and EngineeringThe University of Nottingham Ningbo ChinaNingbo 315100China Department of Chemical and Environmental Engineering Faculty of Science and EngineeringThe University of Nottingham Ningbo ChinaNingbo 315100China Department of Chemical and Environmental Engineering and Advanced Materials Research GroupFaculty of EngineeringThe University of NottinghamNottingham NG72RDUK

Device level performance of aqueous halide supercapatteries fabricated with equal electrode mass of activated carbon or graphene nanoplatelets has been *** was revealed that the surface oxygen groups in the graphitic structures of the nanoplatelets contributed toward a more enhanced charge storage capacity in bromide containing redox ***,the rate performance of the devices could be linked to the effect of the pore size of the carbons on the dynamics of the inactive alkali metal counterion of the redox halide ***,the charge storage performance of aqueous halide supercapatteries with graphene nanoplatelets as the electrode material may be attributed to the combined effect of the porous structure on the dynamics of the non-active cations and a possible interaction of the Br^(-)/(Br_(2)+Br^(-)_(3))redox triple with the surface oxygen groups within the graphitic layer of the ***,it has been shown that the surface groups and microstructure of electrode materials must be critically correlated with the redox electrolytes in the ongoing efforts to commercialize these devices.

关键词： carbon materials device engineering energy efficiency redox electrolyte supercapattery

Basic Characteristics of a New Flexible Pneumatic Bending Joint

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Chinese Journal of Mechanical Engineering 2014年第6期27卷 1143-1149页

作者： SHAO Tiefeng ZHANG Libin BAO Guanjun LUO Xinyuan yang qinghua Key Laboratory of E&M Ministry of Education & Zhejiang Province Zhejiang University of Technology Engineering Training Center China Jiliang University

Several typical flexible pneumatic actuators （FPA） and different mechanical models describing their behaviors have been proposed, however, it is difficult to balance compliance and load capacity in conventional designs, and these models still have limitations in predicting behavior of FPAs. A new flexible pneumatic bending joint （FPBJ） with special anisotropic rigidity structure is proposed. The FPBJ is developed as an improvement with regard to existing types of FPA, and its principal characteristic is derived from the special anisotropic rigidity structure. With this structure, the load capacity in the direction perpendicular to bending plane is strengthened. The structure of the new FPBJ is explained and a mathematical model is derived based on Euler-Bernoulli beam model and Hook’s law. To obtain optimum design and usage, some key structure parameters and input-output characteristics are simulated. The simulation results reveal that the relationship between the structure parameters and FPBJ’s bending angle is nonlinear. At last, according to the simulation results, the FPBJ is manufactured with optional parameters and tested. The experimental results show that the joint’s statics characteristics are reflected by the mathematical model accurately when the FPBJ is deflated. The maximum relative error between simulation and experimental results is less than 6%. However, the model still has limitations. When the joint is inflated, the maximum relative error reaches 20%. This paper proposes a new flexible pneumatic bending joint which has sufficient load capacity and compliance, and the mathematical model provides theoretical guidance for the FPBJ’s structure design.

关键词： flexible pneumatic bending joint Euler-Bernoulli model Hook's law mathematical model

A Parameterization Scheme for Wind Wave Modules that Includes the Sea Ice Thickness in the Marginal Ice Zone

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Advances in Atmospheric Sciences 2023年第12期40卷 2279-2287页

作者： Dongang LIU qinghua yang Andrei TSARAU Yongtao HUANG Xuewei LI Navigation College Dalian Maritime UniversityDalian 116026China School of Atmospheric Sciences Sun Yat-sen Universityand Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)Zhuhai 519082China SINTEF Ocean Brattørkaia 17C7010 TrondheimNorway Norwegian University of Science and Technology 7491 TrondheimNorway

The global wave model WAVEWATCH III®works well in open *** simulate the propagation and attenuation of waves through ice-covered water,existing simulations have considered the influence of sea ice by adding the sea ice concentration in the wind wave module;however,they simply suppose that the wind cannot penetrate the ice layer and ignore the possibility of wind forcing waves below the ice *** improve the simulation performance of wind wave modules in the marginal ice zone(MIZ),this study proposes a parameterization scheme by directly including the sea ice *** of scaling the wind input with the fraction of open water,this new scheme allows partial wind input in ice-covered areas based on the ice *** with observations in the Barents Sea in 2016,the new scheme appears to improve the modeled waves in the high-frequency *** experiments with and without wind wave modules show that wind waves can play an important role in areas with low sea ice concentration in the MIZ.

关键词： wind wave IMU wave PSD wave attenuation Barents Sea

Detection of egg stains based on local texture feature clustering

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International Journal of Agricultural and Biological Engineering 2018年第1期11卷 199-205页

作者： qinghua yang Mimi Jia Yi Xun Guanjun Bao Key Laboratory of E&M Ministry of Education&Zhejiang ProvinceZhejiang University of TechnologyHangzhou 310032China

The quality of egg is mainly influenced by the dirt adhering to its *** with good farm-management practices and careful handling,a small percentage of dirty eggs will be *** purpose of this research was to detect the egg stains by using image processing *** to the color values,the local texture was found to be much more adept at accurately segmenting of the complex and miscellaneous dirt stains on the egg ***,the global threshold of the image was obtained by two-peak *** irrelevant background was removed by using the global threshold and the interested region was *** local texture information extracted from the interested region was taken as the input of fuzzy C-means clustering for segmentation of the dirt *** to the principle of projection,the area of dirt stains on the curved egg surface was accurately *** validation experimental results showed that the proposed method for classifying eggs in terms of stain has the specificity of 91.4%for white eggs and 89.5%for brown eggs.

关键词： eggs eggshell dirt stains computer vision local texture feature FCM egg classifying

Superpixel-based segmentation algorithm for mature citrus

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International Journal of Agricultural and Biological Engineering 2020年第4期13卷 166-171,I0001页

作者： qinghua yang Yiqin Chen Yi Xun Guanjun Bao Key Laboratory of E&M Ministry of Education&Zhejiang ProvinceZhejiang University of TechnologyHangzhou 310023China

With the decrease of agricultural labors and the increase in production costs,harvesting robots have become a research hotspot in recent *** guide harvesting robots to pick mature citrus more precisely under variable illumination conditions,an image segmentation algorithm based on superpixel was *** simple linear iterative clustering(SLIC)algorithm which takes similarity of adjacent pixels into account was adopted to segment the images captured under variable illumination conditions into *** color and texture features of these superpixels were extracted and fused into feature vectors as descriptors to train backpropagation neural networks(BPNN)classifier in the next *** adjacency information of superpixels was considered by calculating the global-local binary pattern(LBP)in R component images when extracting texture *** accelerate the classification process,the mean of Cr-Cb image was utilized to find superpixels of interest which were regarded as candidates of citrus *** candidates were then classified by a pre-trained BPNN model with superpixel-level accuracy of 98.77%and pixel-level accuracy of 94.96%,while the average time to segment one image was 0.4778 ***,the results indicated that a superpixel-based segmentation algorithm toward citrus images had decent light robustness as well as high accuracy that could guide harvesting robot to pick mature citrus efficiently.

关键词： superpixel image segmentation BPNN variable illumination mature citrus