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Microscratch of copper by a Rockwell C diamond indenter under a constant load

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Nanotechnology and Precision Engineering 2021年第3期4卷 20-44页

作者： ming liu School of Mechanical Engineering and Automation Fuzhou UniversityQishan CampusFuzhou 350116China

The scratch test is used for quality control mostly in phenomenological ways,and whether fracture toughness can be obtained from this test is still a matter of debate requiring further *** this paper,values of the fracture toughness of copper obtained by different scratch-based approaches are compared in order to examine the applicability of scratch-based methodologies to characterize the fracture toughness of soft *** scratch response of copper to a Rockwell C diamond indenter is studied under a constant normal load *** variations of penetration depth,residual depth,and residual scratch width with applied normal load are quantified from spherical to sphero-conical contact regimes by piecewise functions.A newly proposed size effect law is found to be the most suitable for scratch-based approaches to characterizing the fracture toughness of soft metallic materials with significant plasticity.A simple expression relating the nominal stress to the penetration depth is proposed for the spherical contact regime and gives almost the same value of fracture *** residual scratch width provides useful information on pile-up of material and on the spherical tip radius of the *** is found that the values of the fracture toughness obtained from the microscratch test are influenced by the data range for analysis.

关键词： Microscratching Rockwell C diamond probe Constant normal load Fracture toughness Residual scratch width

Adaptive fuzzy backstepping control for attitude stabilization of flexible spacecraft with signal quantization and actuator faults

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Science China(Information Sciences) 2021年第5期64卷 135-150页

作者： Qiuhong liu ming liu Guangren DUAN Research Institute of Intelligent Control Systems Harbin Institute of Technology Research Center of Satellite Technology Harbin Institute of Technology Center for Control Theory and Guidance Technology Harbin Institute of Technology

In this study, the fault-tolerant attitude control of flexible spacecraft is investigated over digital communication channels, where a uniform quantizer is considered with respect to the sensor signals and controller indexes. Further, an adaptive fuzzy backstepping control strategy has been developed for the considered attitude stabilization issue, where the adaptive fuzzy logic method is used to approximate the rigid-flexible coupled nonlinearity of the spacecraft. In this design, the online adjusting quantizer parameters are injected into the controller gains to simultaneously compensate for the quantization errors and timevarying actuator faults. In the proposed control method, the attitude stabilization task is achieved in the presence of external disturbances, time-varying actuator faults, and signal quantization. Finally, the practical examples are compared to demonstrate the effectiveness of the proposed control strategy.

关键词： fault-tolerant control attitude stabilization signal quantization adaptive fuzzy control back-stepping control

Micromechanical characterization of microwave dielectric ceramic BaO-Sm_(2)O_(3)-5TiO_(2),by indentation and scratch methods

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Journal of Advanced Ceramics 2023年第6期12卷 1136-1165页

作者： ming liu Zhitong Xu Fujian Provincial Key Laboratory of Terahertz Functional Devices and Intelligent Sensing School of Mechanical Engineering and AutomationFuzhou UniversityFuzhou 350108China

Mechanical characterization of dielectric ceramics,which have drawn extensive attention in wireless communication,remains *** micromechanical properties with the microstructures of dielectric ceramic BaO-Sm_(2)O_(3)-5TiO_(2)(BST)were assessed by nanoindentation,microhardness,and microscratch tests under different indenters,along with the X-ray diffraction(XRD),scanning electron microscopy(SEM),and Raman *** determination of elastic modulus(Err)(i.e.,260 GPa)and indentation hardness(Hrr)(i.e.,16.2 GPa)of brittle BST ceramic by the instrumented indentation technique requires low loads with little indentation-induced *** elastic modulus and indentation hardness were analyzed by different methodologies such as energy-based approach,displacement-based approach,and elastic recovery of Knoop *** values(about 3.1 MPa·m^(1/2))of fracture toughness(Kc)of BST ceramic were obtained by different methods such as the Vickers indenter-induced cracking method,energy-based nanoindentation approaches,and linear elastic fracture mechanics(LEFM)-based scratch approach with a spherical indenter,demonstrating successful applications of indentation and scratch methods in characterizing fracture properties of brittle *** deterioration of elastic modulus or indentation hardness with the increase in indentation load(F)is caused by indentation-induced damage and can be used to determine the fracture toughness of material by energy-based nanoindentation approaches,and the critical void volume fraction(f^(*))is 0.27(or 0.18)if elastic modulus(or indentation hardness)of the brittle BST ceramic is *** fracture work at the critical load corresponding to the initial decrease in elastic modulus or indentation hardness can also be used to assess the fracture toughness of brittle solids,opening new venues of the application of nanoindentation test as a means to characterize the fracture toughness of brittle ceramics.

关键词： brittle ceramics micromechanical properties instrumented indentation microscratch fracture toughness(K_(c)) grid nanoindentation

Research of Lead-free Na_(0.5)Bi_(0.5)TiO_(3)-BaTiO_(3)System Piezoelectric Ceramics

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Journal of Wuhan University of Technology(Materials Science) 2023年第2期38卷 325-329页

作者： ZHANG Weifeng liu ming School of Microelectronics Shenzhen Institute of Information TechnologyShenzhen518172China

To reduce the coercive field of Na_(0.5)Bi_(0.5)TiO_(3),Ba TiO_(3)were added as dopant *** the(1-x)Na_(0.5)Bi_(0.5)TiO_(3)-xBaTiO_(3)ceramic samples were produced in solid synthetic *** optimum preparation condition and piezoelectric properties of the samples were *** XRD results show that the fabric transites from rhombohedral to tetragonal gradually with the substitution of the Ba^(2+).The morphotropic phase boundaries(MPB)exists in the composition range of 0.06.

关键词： lead-free piezoelectric ceramic Na_(0.5)Bi_(0.5)TiO_(3) BaTiO_(3) piezoelectric performance

Error model identification of inertial navigation platform based on errors-in-variables model

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Journal of Systems Engineering and Electronics 2009年第2期20卷 388-393页

作者： liu ming liu Yu Su Baoku Space Control and Inertial Technology Research Center Harbin Inst. of Technology Harbin 150001 P. R. China

Because the real input acceleration cannot be obtained during the error model identification of inertial navigation platform, both the input and output data contain noises. In this case, the conventional regression model and the least squares （LS） method will result in bias. Based on the models of inertial navigation platform error and observation error, the errors-in-variables （EV） model and the total least squares （TLS） method axe proposed to identify the error model of the inertial navigation platform. The estimation precision is improved and the result is better than the conventional regression model based LS method. The simulation results illustrate the effectiveness of the proposed method.

关键词： errors-in-variables model total least squares method inertial navigation platform error model identification

The war between wheat and Fusarum: fighting with an alien weapon

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Science China(Life Sciences) 2020年第9期63卷 1425-1427页

作者： Chun-ming liu Institute of Crop Sciences Chinese Academy of Agricultural SciencesBeijing 100081China Key Laboratory of Plant Molecular Physiology Institute of BotanyChinese Academy of SciencesBeijing 100093China

Wheat, as one of the most important staple food crops in the world, has been domesticated and cultivated for over5,000 years. The flour of common wheat (Triticum aestivum L.) is used daily to make different types of foods in different regions, typically bread, pizza and pasta for western countries, and noodle, dumpling and steamed bread for Asian countries. Infections of Fusarium species cause impactful diseases for cereal crops including wheat, rice, maize and barley. Outbreaks of devastating infections by Fusarium species may lead to up to 50%yield loss in these crops and the contaminations of trichothecene mycotoxins. Therefore,it is an important issue for both food security and food safety.

关键词： crops Wheat cultivated

A survey of discourse parsing

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Frontiers of Computer Science 2022年第5期16卷 85-96页

作者： Jiaqi LI ming liu Bing QIN Ting liu School of Computer Science and Technology Harbin Institute of TechnologyHarbin 150001China Peng Cheng Laboratory Shenzhen 518052China

Discourse parsing is an important research area in natural language processing(NLP),which aims to parse the discourse structure of coherent *** this survey,we introduce several different kinds of discourse parsing tasks,mainly including RST-style discourse parsing,PDTB-style discourse parsing,and discourse parsing for multiparty *** these tasks,we introduce the classical and recent existing methods,especially neural network *** that,we describe the applications of discourse parsing for other NLP tasks,such as machine reading comprehension and sentiment ***,we discuss the future trends of the task.

关键词： discourse parsing discourse structure RST PDTB STAC

Recent advances and perspectives of metal/covalent-organic frameworks in metal-air batteries

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Journal of Energy Chemistry 2021年第12期30卷 113-129,I0003页

作者： ming Zhong ming liu Na Li Xian-He Bu School of Materials Science and Engineering Tianjin Key Laboratory of Metal and Molecule-Based Material ChemistryNankai UniversityTianjin 300350China State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals Lanzhou University of TechnologyLanzhou 730050GansuChina College of Chemistry Key Laboratory of Advanced Energy Materials Chemistry(Ministry of Education)Nankai UniversityTianjin 300071China

Metal-air batteries(MABs)have attracted considerable attention as a novel energy technology that can alleviate the severe energy crisis and environmental *** primary processes,including oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)occur on the air cathode and dominate the battery performance during battery charging and ***,metal-organic frameworks(MOFs)and covalent-organic frameworks(COFs)emerge as promising cathode catalysts due to their structure and composition *** unique characteristics of MOFs and COFs contribute to improved *** review mainly summarizes the recent applications of MOFs and COFs in a series of MABs,mainly including lithium-and zinc-air ***,some critical issues are emphasized regarding MOFs and COFs used in other MABs limited progress,their fabrication and alternatives to potential problems.

关键词： Metal-organic frameworks Covalent-organic frameworks Li-air batteries Zn-air batteries Active sites

Active Balance Control of Humanoid Locomotion Based on Foot Position Compensation

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Journal of Bionic Engineering 2020年第1期17卷 134-147页

作者： Chengju liu Tong Zhang ming liu Qijun Chen School of Electronics and Information Engineering Tongji UniversityShanghai 201804China School of Electronic and Computer Engineering Hong Kong University of Science and TechnologyHong Kong 999077China

A foot positioning compensator is developed in this paper for a full-body humanoid to retrieve its balance during continuous *** online Foot Position Compensator(FPC)is designed to improve the robustness of biped walking,which can modify predefined step position and step duration online with sensory *** placement parameters are learned by the FPC based on the Policy Gradient Reinforcement Learning(PGRL)***,the FPC assists the humanoid robot in rejecting external disturbances and recovering the walking position by re-planning the trajectories of walking pattern and the Center of Mass(CoM).An upper body pose control strategy is also presented to further enhance the performance of humanoid robots to overcome strong external *** advantages of this proposed method are that it neither requires prior information about the walking terrain conditions,nor relies on range sensor information for surface topology *** effectiveness of the proposed method is verified via Webots simulation and real experiments on a full-body humanoid NAO robot.

关键词： humanoid walking active balance Foot Positioning Compensation(FPC) Policy Gradient Reinforcement Learning(PGRL)