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Effects of laser heat treatment on the fracture morphologies of X80 pipeline steel welded joints by stress corrosion

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International Journal of Minerals,Metallurgy and Materials 2014年第9期21卷 898-905页

作者： De-jun Kong Cun-dong ye College of Mechanical Engineering Changzhou University

The surfaces of X80 pipeline steel welded joints were processed with a CO2 laser, and the effects of laser heat treatment （LHT） on H2S stress corrosion in the National Association of Corrosion Engineers （NACE） solution were analyzed by a slow strain rate test. The fracture morphologies and chemical components of corrosive products before and after LHT were analyzed by scanning electron microscopy and energy-dispersive spectroscopy, respectively, and the mechanism of LHT on stress corrosion cracking was discussed. Results showed that the fracture for welded joints was brittle in its original state, while it was transformed to a ductile fracture after LHT. The tendencies of hydrogen-induced corrosion were reduced, and the stress corrosion sensitivity index decreased from 35.2% to 25.3%, indicating that the stress corrosion resistance of X80 pipeline steel welded joints has been improved by LHT.

关键词： pipeline steel welded joints laser heating stress corrosion fracture morphology

Distributed online mission planning for multi-player space pursuit and evasion

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Chinese Journal of Aeronautics 2016年第6期29卷 1709-1720页

作者： Liu Yuan ye dong Hao Yong College of Automation Harbin Engineering University Research Center of Satellite Technology Harbin Institute of Technology

There are three important roles in evasion conflict: pursuer, target and defender. Pursuers’ mission is to access targets; targets’ mission is to escape from pursuers’ capture; defenders’ mission is to intercept pursuers who are potentially dangerous to targets. In this paper, a distributed online mission plan(DOMP) algorithm for pursuers is proposed based on fuzzy evaluation and Nash equilibrium. First, an integrated effectiveness evaluation model is given. Then, the details of collaborative mission planning which includes the co-optimization of task distributing, trajectory and corresponding maneuvering scheme are presented. Finally, the convergence and steadiness of DOMP are discussed with simulation results. Compared with centralized mission planning, DOMP is more robust and can greatly improve the effectiveness of pursuing. It can be applied to dynamic scenario due to its distributed architecture.

关键词： Evaluation Nash equilibrium solution Pursuit-evasion strategy Planning Space

Satellite proximate interception vector guidance based on differential games

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Chinese Journal of Aeronautics 2018年第6期31卷 1352-1361页

作者： dong ye Mingming SHI Zhaowei SUN Research Center of Satellite Technology Harbin Institute of Technology Harbin Institute of Technology Faculty of Science and Engineering University of Groningen

This paper studies the proximate satellite interception guidance strategies where both the interceptor and target can perform orbital maneuvers with magnitude limited thrusts. This problem is regarded as a pursuit-evasion game since satellites in both sides will try their best to capture or escape. In this game, the distance of these two players is small enough so that the highly nonlinear earth-centered gravitational dynamics can be reduced to the linear Clohessy-Wiltshire（CW） equations. The system is then simplified by introducing the zero effort miss variables. Saddle solution is formulated for the pursuit-evasion game and time-to-go is estimated similarly as that for the exoatmospheric interception. Then a vector guidance is derived to ensure that the interception can be achieved in the optimal time. The proposed guidance law is validated by numerical simulations.

关键词： Differential games Saddle solution Satellite interception Time-to-go estimation Zero effort miss trajectory

Recent Development of Chaos Theory in Topological Dynamics

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Acta Mathematica Sinica,English Series 2016年第1期32卷 83-114页

作者： Jian LI Xiang dong ye Department of Mathematics Shantou University Wu Wen-Tsun Key Laboratory of Mathematics USTC Chinese Academy of Sciences and School of Mathematics University of Science and Technology of China

We give a summary on the recent development of chaos theory in topological dynamics, focusing on Li-Yorke chaos, Devaney chaos, distributional chaos, positive topological entropy, weakly mixing sets and so on, and the... 详细信息

关键词： Li-Yorke chaos Devaney chaos sensitive dependence on initial conditions distributionalchaos weak mixing topological entropy Furstenberg family

Development of a non-cable whole tectorial membrane micro-robot for an endoscope

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第8期9卷 1141-1149页

作者： dong-dong ye Guo-zheng YAN Kun-dong WANG Guan-ying MA Department of Instrument Shanghai Jiao Tong University Shanghai 200240 China

A novel non-cable whole tectorial membrane micro-robot for an endoscope is developed. The micro-robot we have fabricated and tested can propel itself in the intestine tract of a pig in an autonomous manner by earthworm-like locomotion. The silicone of bellow shape is laid over the outer surface of the micro-robot to reduce the affection of the viscoelastic properties of the intestine. Wireless power transfer and communication systems are employed to realize the non-cable locomotion of the mi-cro-robot. The prototype of the micro-robot is 13.5 mm in diameter and 108 mm in length. The experimental results show that the towing force for the micro-robot is about 0.8 N, which is much smaller than the maximum driving force 2.55 N of the linear actuator. The supplying power of the wireless power transfer system fulfills the needs of the micro-robot system and the mi-cro-robot can creep reliably in the large intestine of a pig and other contact environments.

关键词： Micro-robot Endoscope Intestine tract Silicone of bellow shape Linear actuator Wireless power

Study on magnetic memory signals of medium carbon steel specimens with surface crack precut during loading process

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Rare Metals 2006年第Z1期25卷 431-435页

作者： dong Lihong XU Binshi dong Shiyun ye Minghui CHEN Qunzhi Basic Department Ordnance Engineering College Shijiazhuang 050003 China National Key Laboratory for Remanufacturing of Armored Force Engineering Institute Beijing 100072 China National Key Laboratory for Remanufacturing of Armored Force Engineering Institute Beijing 100072 China National Key Laboratory for Remanufacturing of Armored Force Engineering Institute Beijing 100072 China Basic Department Ordnance Engineering College Shijiazhuang 050003 China Beijing Aeronautical Technology Research Center Beijing 100076 China

Static tensile test and tensile-tensile fatigue test of medium carbon steel sheet specimens with surface crack precut were performed on MTS810 hydraulic testing machine to clear the meaning of the point of Hp(y) value zero. Magnetic memory signals were measured during the test process. The results show that only one point of Hp(y) zero value exists in all measured magnetic signal curves during the loading process, which should be a sign of intersection of positive-negative magnetic poles after magnetic ordered state appears and does not indicate the position of surface crack precut. The analysis shows that the surface crack precut can not interrupt the magnetic ordered state occurred during the test completely, hence its Hp(y) value is not zero. However, the crack extending to a penetrated defect at the instant of specimen′s fracture leads to the discontinuance of magnetic ordered state.

关键词： metal magnetic memory ferromagnetic materials surface crack precut Hp(y) zero value magnetic ordered state

Non-Contact Physiological Measurement System for Wearing Masks During the Epidemic

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Computers, Materials & Continua 2023年第5期75卷 2509-2526页

作者： Shu-Yin Chiang dong-ye Wu Department of Information and Telecommunications Engineering Ming Chuan UniversityNo.5 De Ming Rd.Gui Shan DistrictTaoyuan City333Taiwan

Physiological signals indicate a person’s physical and mental state at any given ***,many studies extract physiological signals from the human body with non-contact methods,and most of them require facial feature ***,under COVID-19,wearing a mask has become a must in many places,so how non-contact physiological information measurements can still be performed correctly even when a mask covers the facial information has become a focus of *** this study,RGB and thermal infrared cameras were used to execute non-contact physiological information measurement systems for heart rate,blood pressure,respiratory rate,and forehead temperature for peoplewearing masks due to the *** the green(G)minus red(R)signal in the RGB image,the region of interest(ROI)is established in the forehead and nose bridge *** photoplethysmography(PPG)waveforms of the two regions are obtained after the acquired PPG signal is subjected to the optical flow method,baseline drift calibration,normalization,and bandpass *** relevant parameters in Deep Neural Networks(DNN)for the regression model can correctly predict the heartbeat and blood *** addition,the temperature change in the ROI of the mask after thermal image processing and filtering can be used to correctly determine the number of ***,the thermal image can be used to read the temperature average of the ROI of the forehead,and the forehead temperature can be obtained *** experimental results show that the above-mentioned physiological signals of a subject can be obtained in 6-s images with the error for both heart rate and blood pressure within 2%∼3%and the error of forehead temperature within±0.5°C.

关键词： PPG DNN heart rate blood pressure prediction face mask

Effect of Na^(+)and Sr^(2+)Substitution on the Formation of the Oxygen Vacancies in Y_(3)Al_(2)Ga_(3)O_(12):Ce^(3+)Phosphor

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Journal of Wuhan University of Technology(Materials Science) 2023年第5期38卷 1221-1230页

作者： YANG Ting JIANG Hongyi dong ye GAO Shuai LIU Shuning School of Materials Science and Engineering Wuhan University of TechnologyWuhan 430070China

The low-valence cations Na^(+)and Sr^(2+)were selected as the co-dopants to increase the vacancies concentration in the Y_(2.982)Ce_(0.018)Al_(2)Ga_(3)O_(12)*** successful incorporation of Na^(+)and Sr^(2+)was confirmed by the X-Ray Difiraction(XRD)*** the samples show 5d-4f green persistent luminescence of Ce^(3+)after 450 nm *** decay curves demonstrate that the persistent luminescence is efiectively enhanced with Na+and Sr2+*** thermoluminescence glow curves also show not only does the trap concentration increase,but also the distribution of trap depths is *** addition,the air-and H_(2)/Ar-annealing treatments were conducted on every as-made *** experimental results prove that the increased traps after the Na^(+)/Sr^(2+)doping are mainly attributed to the oxygen vacancies,and the traps have a continuous and broad distribution of trap *** hope this work could give new inspiration for designing a high-performance persistent phosphor.

关键词： persistent luminescence YAGG Na^(+) Sr^(2+) oxygen vacancy charge compensation solidstate reaction

Theoretical and experimental study of 2D conformability of stretchable electronics laminated onto skin

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Science China(Technological Sciences) 2017年第9期60卷 1415-1422页

作者： dong WenTao XIAO Lin ZHU Chen ye dong WANG ShuoDao HUANG YongAn YIN ZhouPing State Key Laboratory of Digital Manufacturing Equipment and Technology Huazhong University of Science and Technology Wuhan 430074 China Flexible Electronics Research Center Huazhong University of Science and Technology Wuhan 430074 China School of Mechanical and Aerospace Engineering Oklahoma State University Stillwater OK 74078 USA

Smoothly attaching the stretchable epidermal electronic devices(EEDs) onto the skin surface is highly desired to improve the measurement accuracy of electrophysiological *** paper presents an analytical approach to study interfacial mechanics of the 2D planar EEDs on the checkerboard buckling patterns of human *** variation method is proposed to determine a criterion whether EEDs laminate conformally onto the skin surface under undeformed and stretched *** with low bending stiffness(thin,soft devices/backing layer),smooth and soft skin,and strong adhesion promote conformal ***,the adhesion energy at the EED/skin interface is measured by the homemade peeling experiment platform with different substrate thicknesses and areal *** upper limit of the areal coverage for EED conformal contact with the skin is proposed with given EED/skin *** of EEDs are validated by experiments with different substrate thickness,areal coverage and external *** provides a design guideline for EED to conformally contact with the skin surface for more accurate biological signal monitoring.

关键词： interfacial mechanics epidermal electronics areal coverage conformability E-skin