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Flexible and electrically robust graphene-based nanocomposite paper with hierarchical microstructures for multifunctional wearable devices

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Nano Materials Science 2023年第3期5卷 319-328页

作者： Zhen-Hua Tang Wei-Bin Zhu Jun-Zhang Chen Yuan-Qing Li Pei Huang Kin Liao Shao-Yun Fu College of Aerospace Engineering Chongqing UniversityChongqing400044China State Key Laboratory of Power Transmission Equipment&System Security and New Technology Chongqing UniversityChongqing400044China Aerospace Engineering Khalifa UniversityAbu Dhabi127788United Arab Emirates

Multifunctional and flexible wearable devices play a crucial role in a wide range of applications,such as heath monitoring,intelligent skins,and human-machine *** flexible and conductive materials for multifunctional wearable devices with low-cost and high efficiency methods are highly ***,a conductive graphene/microsphere/bamboo fiber(GMB)nanocomposite paper with hierarchical surface microstructures is successfully fabricated through a simple vacuum-assisted filtration followed by thermo-foaming *** as-prepared microstructured GMB nanocomposite paper exhibits not only a high volume electrical conductivity of~45 S/m but also an excellent electrical stability(i.e.,relative changes in resistance are less than 3%under stretching,folding,and compressing loadings)due to its unique structure *** this microstructured nanocomposite paper as active sensing layer,microstructured pressure sensors with a high sensitivity(-4 kPa^(-1)),a wide sensing range(0–5 kPa),and a rapid response time(about 140 ms)are *** addition,benefitting from the outstanding electrical stability and mechanical flexibility,the microstructured nanocomposite paper is further demonstrated as a low-voltage Joule heating *** surface temperature of the microstructured nanocomposite paper rapidly reaches over 80℃ when applying a relatively low voltage of 7 V,indicating its potential in human thermotherapy and thermal management.

关键词： Graphene Bamboo fibers Microspheres Pressure sensors Joule heating devices

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Phenomenological Modeling of Deformation-Induced Martensite Transformation Kinetics in Austenitic Stainless Steels

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Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science 2024年第1期55卷 73-92页

作者： Zhang, Wen Zheng, Qide Gu, Nan Zhuang, Xincun Zhao, Zhen Institute of Forming Technology and Equipment School of Materials Science and Engineering Shanghai Jiao Tong University Shanghai200030 China State Key Laboratory of Mechanical System and Vibration Shanghai Key Laboratory of Digital Manufacture for Thin-walled Structures Shanghai Jiao Tong University Shanghai200240 China National Engineering Research Center of Die & Mold CAD Shanghai Jiao Tong University Shanghai200030 China

The aim of this study is to predict the kinetics of deformation-induced martensite transformation (DIMT) by proposing a novel model considering the effects of three loading characteristics: temperature, strain rate, and stress state. Experiments including hot compression, tension, notched tension, and shear tests using 304 stainless steel plate were carried out to investigate the transformation kinetics. After a decoupling analysis was conducted on the effects of the three characteristics, particularly the temperature and strain rate effects under high strain rate loading conditions, three kinetic sub-models were established individually for each effect, and the proposed model was developed by multiplying the three kinetic sub-models. A stepwise fitting method was proposed for the calibration of material constants to replace complex iterative optimization algorithms and improve the certainty of the values of the material constants. The proposed model was further validated using the experimental data of various austenitic stainless steels obtained from previous studies. Result shows the model revealed satisfactory accuracy in predicting the DIMT behavior in material experiment. After compiling the model into a USDFLD subroutine, simulation of a heat-assisted fine-blanking process was conducted in ABAQUS, giving a reasonable prediction of martensite content of the blanking parts. © 2023, The Minerals, Metals & Materials Society and ASM International.

关键词： Austenitic stainless steel

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The Optimal Duty Cycle Model-Predictive Control of PMSM Used for Satellite Payload 1

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17th Annual Conference of China Electrotechnical Society, CES 2022

作者： Li, Jialin Chen, Zhen Hu, Hengzai Liu, Xiangdong Bao, Liang School of Automatic Beijing Institute of Technology Beijing100081 China Key Laboratory of Drive and Control of Servo Motion System Ministry of Industry and Information Technology Beijing100081 China State Key Laboratory of Intelligent Control and Decision for Complex System Beijing100081 China Beijing Aerospace Automatic Control Institute Beijing100854 China

ISBN: (数字)9789819904082

ISBN: (纸本)9789819904075

Model-predictive control is emerging as an advanced control strategy for its feature that the state variables can be predicted according to the math model of the control system. In the PMSM drive application, conventional model-predictive control strategy induces current ripple due to the fact that the optimal voltage vector always acts on the system for the whole control period. In order to restrain the current ripple, the idea of duty cycle control is taken into MPC by inserting a zero vector into the optimal non-zero vector and regulating the duty cycle of non-zero vector. In this paper, the optimal duty cycle FSC-MPC strategy based on two different principles is investigated. Principle A is that the estimation is equal to the reference at the end of control cycle, and principle B is that the area under trace of the estimation is equal to that of reference. The calculation of duty based on the two different principles and the flow chart of the strategy are introduced in detail. Finally, the effectiveness of the optimal duty cycle FSC-MPC is firstly verified by the simulation, and then verified by the experimental results, which is implemented on the PMSM driver of the DQ-1 satellite payload. © 2023, Beijing Paike Culture Commu. Co., Ltd.

关键词： Model predictive control

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Neural Network technology Applied in Fault Detection and Simulation of Power systems 8

Neural Network Technology Applied in Fault Detection and Sim...

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8th International Conference on Electrical, Mechanical and Computer Engineering, ICEMCE 2024

作者： Hong, Zeqi Huang, Libin Hu, Yufeng Guo, Haiping Lu, Yuanhong Hu, Binjiang Zhang, Jingyue Luo, Hui Electric Power Research Institute China Southern Power Grid State Key Laboratory of Hvdc Guangzhou China National Energy Power Grid Technology R and D Centre Guangzhou China Guangdong Provincial Key Laboratory of Intelligent Operation and Control for New Energy Power System Guangzhou China Institute China Southern Power Grid Csg Key Laboratory for Power System Simulation Electric Power Research Guangzhou China

ISBN: (纸本)9798331506230

With the escalating demand for power inspection and equipment maintenance, developing effective algorithms for power system fault detection is crucial for ensuring the safety and stability of power systems. This paper leveragesthe Trellis network, enhanced with an attention module, to significantly improve the Trellis network's capability in recognizing power fault images, thus better addressing fault identification tasks within power systems. Through testing on a self-constructed dataset and comparative experiments with models such as DCNN, RCNN, and DenseNet, the proposed attention mechanismenhanced Trellis network algorithm has demonstrated its effectiveness and superiority in fault detection. © 2024 IEEE.

关键词： Power distribution faults

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Creep life assessment of aero-engine recuperator based on continuum damage mechanics approach

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Frontiers of Mechanical Engineering 2022年第4期17卷 273-284页

作者： Pengpeng LIAO Yucai ZHANG Guoyan ZHOU Xiancheng ZHANG Wenchun JIANG Shantung TU Key Laboratory of Pressurized System and Safety MOESchool of Mechanical and Power EngineeringEast China University of Science and TechnologyShanghai 200237China State Key Laboratory of Heavy Oil Processing College of Chemical EngineeringChina University of Petroleum(East China)Qingdao 266555China

The creep life of an aeroengine recuperator is investigated in terms of continuum damage mechanics by using finite element *** effects of the manifold wall thickness and creep properties of brazing filler metal on the operating life of the recuperator are *** show that the crack initiates from the brazing filler metal located on the outer surface of the manifold with the wall thickness of 2 mm and propagates throughout the whole region of the brazing filler metal when the creep time reaches 34900 *** creep life of the recuperator meets the requirement of 40000 h continuous operation when the wall thickness increases to 3.5 mm,but its total weight increases by 15%.Decreasing the minimum creep strain rate with the enhancement of the creep strength of the brazing filler metal presents an obvious effect on the creep life of the *** the same stress level,the creep rupture time of the recuperator is enhanced by 13 times if the mismatch between the minimum creep rate of the filler and base metal is reduced by 20%.

关键词： creep life assessment brazed joint continuum damage mechanics aeroengine recuperator

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A Trajectory Planning Algorithm of Spray Robot for Workpieces with Complex Geometric Features based on 3D Point Cloud 5

A Trajectory Planning Algorithm of Spray Robot for Workpiece...

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5th IEEE Information technology, Networking, Electronic and Automation Control Conference, ITNEC 2021

作者： Kong, Minxiu Li, Ang Gao, Feng Harbin Institute of Technology School of Mechatronics Engineering Harbin China State Key Laboratory of Robotics and System Harbin China

ISBN: (纸本)9781665415989

Trajectory planning of spray robot for workpieces with complex geometric features is always a challenging problem. Combined with the actual process requirements of surface spraying and edge spraying, a new spraying path design method based on 3D point cloud is proposed in this paper. During surface spraying, the automatic segmentation algorithm of spraying area based on the determination of hole ratio and Euclidean clustering is studied. For the area with dense features, the point cloud slicing algorithm is used to generate the spray path. For the narrow area, the flexible midline extraction algorithm is proposed. We also discussed the edge extraction algorithm to generate the edge spray path. According to the simulation results of coating thickness, this method can not only ensure the uniformity of coating thickness, but also ensure high spraying efficiency with low paint waste. © 2021 IEEE.

关键词： Clustering algorithms

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Research progress on the water vapor channel within the Yarlung Zsangbo Grand Canyon, China

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Atmospheric and Oceanic Science Letters 2024年第5期17卷 10-15页

作者： Xuelong Chen Yajing Liu Yaoming Ma Xiangde Xu Xin Xu Luhan Li Dianbin Cao Qiang Zhang Gaili Wang Maoshan Li Siqiong Luo Xin Wang Land–Atmosphere Interaction and its Climatic Effects Group State Key Laboratory of Tibetan Plateau Earth SystemEnvironment and Resources(TPESER)Institute of Tibetan Plateau ResearchChinese Academy of SciencesBeijingChina State Key Laboratory of Disastrous Weather China Academy of Meteorological SciencesBeijingChina The Key Laboratory of Land Surface Process and Climate Change in Cold and Arid Regions Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhouChina College of Atmospheric Sciences Plateau Atmosphere and Environment Key Laboratory of Sichuan ProvinceChengdu University of Information TechnologyChengduChina

The Second Tibetan Plateau Scientific Expedition and Research Program tasked a research team with the“Investigation of the water vapor channel of the Yarlung Zsangbo Grand Canyon(INVC)”in the southeastern Tibetan Plateau(TP).This paper summarizes the scientific achievements obtained from the data collected by the INVC observation network and highlights the progress in investigating the development of heavy rainfall events associated with water vapor *** rain gauge network of the INVC can represent the impacts of the Yarlung Zsangbo Grand Canyon(YGC)topography on precipitation at the hourly *** microphysical characteristics of the precipitation in the YGC are different than those in the lowland *** GPM-IMERG(Integrated MultisatellitE Retrievals for Global Precipitation Measurement)satellite precipitation data for the YGC region should be calibrated before they are *** meridional water vapor flux through the YGC is more important than the zonal flux for the precipitation over the southeastern *** decreased precipitation around the YGC region is partly due to the decreased meridional water vapor flux passing through the ***-resolution numerical models can benefit precipitation forecasting in this region by using a combination of specific schemes that capture the valley wind and water vapor flux along the valley floor.

关键词： Water vapor channel Land-air interaction Mountian meteorology Extreme rainfall Observation network

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Experimental and molecular level analysis of natural ester delaying degradation of cellulose insulation polymer

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High Voltage 2022年第5期7卷 1001-1015页

作者： Jian Hao Wenyu Ye Chenyu Gao Mengzhao Zhu Lijun Yang Ruijin Liao State Key Laboratory of Power Transmission Equipment&System Security and New Technology Chongqing UniversityChongqingChina State Grid Shandong Electric Power Co. Shandong Electric Power Research InstituteJinanChina

Developing green insulation materials has become an important direction for future *** a new environmental insulation liquid,natural ester can effectively delay cellulose insulation polymer *** the mechanism of natural ester delaying the cellulose ageing could promote its application in power *** this study,based on the accelerated thermal ageing of pressboard immersed in natural ester and 25#mineral oil at 120°C for 221 days,the thermal ageing rate and the levelling off degree of polymerisation(LODP)for two kinds of oil-impregnated pressboards were *** molecular level mechanism of natural ester delaying cellulose degradation and keeping higher LODP value was proposed using molecular dynamics *** the early stage of thermal ageing,cellulose with a higher degree of polymerisation(DP)can form many hydrogen bonds with hydronium ions,and their binding energy is stronger,which can accelerate the acid hydrolysis of cellulose,causing the DP of pressboard immersed in natural ester and mineral oil to decrease *** the breaking of the cellulose molecular chain,the number of hydrogen bonds and binding energy between cellulose and hydronium ions becomes smaller and the thermal ageing rate decreases *** the end stage of ageing,it is difficult for the hydronium ions to enter the crystalline cellulose,acid hydrolysis of crystalline cellulose is hard to conduct,leading to the occurrence of the LODP *** degradation rate of cellulose in natural ester is only 50%of that in mineral *** cellulose LODP value in natural ester is over 200 larger than that in mineral *** with the mineral oil-cellulose system,natural ester can form hydrogen bonds with hydronium ions and lead to fewer hydronium ions in cellulose,fewer hydrogen bonds and smaller binding energy between cellulose and hydronium ions,which can reduce the acid hydrolysis reaction of *** study provides a theoretical explanation for

关键词： insulation delay cellulose

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Application of the Conditional Nonlinear Local Lyapunov Exponent to Second-Kind Predictability

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Advances in Atmospheric Sciences 2024年第9期41卷 1769-1786页

作者： Ming ZHANG Ruiqiang DING Quanjia ZHONG Jianping LI Deyu LU State Key Laboratory of Earth Surface Processes and Resource Ecology(ESPRE)/Key Laboratory of Environmental Change and Natural Disasters of Chinese Ministry of EducationBeijing Normal UniversityBeijing 100875China Department of Ocean Science Hong Kong University of Science and TechnologyHong KongChina College of Oceanic and Atmospheric Sciences/Frontiers Science Center for Deep Ocean Multispheres and Earth System(DOMES)/Key Laboratory of Physical Oceanography Ministry of Education/Academy of the Future Ocean/Center for Ocean Carbon NeutralityOcean University of ChinaQingdao 266100China Laoshan Laboratory Qingdao 266237China State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics(LASG) Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China College of Earth Science University of Chinese Academy of SciencesBeijing 100049China

In order to quantify the influence of external forcings on the predictability limit using observational data,the author introduced an algorithm of the conditional nonlinear local Lyapunov exponent(CNLLE)*** effectiveness of this algorithm is validated and compared with the nonlinear local Lyapunov exponent(NLLE)and signal-to-noise ratio methods using a coupled Lorenz *** results show that the CNLLE method is able to capture the slow error growth constrained by external forcings,therefore,it can quantify the predictability limit induced by the external *** this basis,a preliminary attempt was made to apply this method to measure the influence of ENSO on the predictability limit for both atmospheric and oceanic variable *** spatial distribution of the predictability limit induced by ENSO is similar to that arising from the initial conditions calculated by the NLLE *** similarity supports ENSO as the major predictable signal for weather and climate *** addition,a ratio of predictability limit(RPL)calculated by the CNLLE method to that calculated by the NLLE method was *** RPL larger than 1 indicates that the external forcings can significantly benefit the long-term predictability *** instance,ENSO can effectively extend the predictability limit arising from the initial conditions of sea surface temperature over the tropical Indian Ocean by approximately four months,as well as the predictability limit of sea level pressure over the eastern and western Pacific ***,the impact of ENSO on the geopotential height predictability limit is primarily confined to the troposphere.

关键词： conditional nonlinear local Lyapunov exponent second-kind predictability coupled Lorenz model ENSO

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Flexible linear clock-based distributed self-triggered active power-sharing secondary control of AC microgrids

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Global Energy Interconnection 2024年第6期7卷 786-797页

作者： Yulin Chen Xing Huang Guangxin Zhi Shaohua Yang Hongxun Hui Donglian Qi Yunfeng Yan Fengkai Gao Key Laboratory of Modern Power System Simulation and Control&Renewable Energy Technology Ministry of Education(Northeast Electric Power University)Jilin132012P.R.China Hainan Institute Zhejiang UniversitySanya572000P.R.China College of Electrical Engineering Zhejiang UniversityHangzhou310027P.R.China State Key Laboratory of Internet of Things for Smart City University of MacaoMacao999078P.R.China

Traditional active power sharing in microgrids,achieved by the distributed average consensus,requires each controller to continuously trigger and communicate with each other,which is a wasteful use of the limited computation and communication resources of the secondary *** enhance the efficiency of secondary control,we developed a novel distributed self-triggered active power-sharing control strategy by introducing the signum function and a flexible linear *** continuous communication–based controllers,the proposed self-triggered distributed controller prompts distributed generators to perform control actions and share information with their neighbors only at specific time instants monitored by the linear ***,this approach results in a significant reduction in both the computation and communication ***,this design naturally avoids Zeno ***,a modified triggering condition was established to achieve further reductions in computation and *** simulation results confirmed that the proposed control scheme achieves distributed active power sharing with very few controller triggers,thereby substantially enhancing the efficacy of secondary control in MGs.

关键词： Active power sharing Distributed secondary control Self-triggered mechanism AC microgrid Control efficiency

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