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Acta Metallurgica Sinica(English Letters) 2022年第3期35卷 501-516页

作者： Xiaodong Wang Chaoyue Chen Ruixin Zhao longtao Liu Sansan Shuai Tao Hu Jiang Wang Zhongming Ren State Key Laboratory of Advanced Special Steels School of Materials Science and EngineeringShanghai UniversityShanghai 200444.China

In this work,the microstructural evolution,micro-crack formation,and mechanical anisotropy of the selective laser melted(SLM)carbon-free Mar-M509 Co-based superalloy were systematically studied under different linear energy densities(LED).Observation shows that the SLM Mar-M509 superalloy possesses a fully dense structure,whereas some microcracks exist along the building *** electron backscatter diffraction results reveal that dominant columnar grains tend to elongate along the building direction parallel to the XZ ***,both anear fiber texture and a{100}near sheet texture are observed in different *** the specimen with fiber texture,a high misorientation angle exists among different columnar grains,which aggravated the generation of micro-cracks under thermal *** LED results in higher micro-crack density in the SLM specimen due to higher thermal ***-M509 specimen fabricated under lower LED exhibits higher tensile strength due to more significant grain *** prominent anisotropy of tensile performance was found in the high LED specimen,which can be attributed to the higher density of micro-cracks and crystallographic ***,the SLM Mar-M509 superalloy exhibits better mechanical properties than the traditional cast *** summary,this work can contribute to the development and the future application of SLM-fabricated Co-based superalloy.

关键词： Selective laser melting Mar-M509 Co-based superalloy Linear energy density Anisotropy Mechanical properties

Design and simulation of an integrated end-effector for picking kiwifruit by robot

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Information Processing in Agriculture 2020年第1期7卷 58-71页

作者： longtao Mu Gongpei Cui Yadong Liu Yongjie Cui Longsheng Fu Yoshinori Gejima College of Mechanical and Electronic Engineering Northwest A&F UniversityYanglingShaanxi 712100China China Aviation Lithium Battery Research Institute Co. LtdChangzhouJiangsu 213200China Key Laboratory of Agricultural Internet of Things Ministry of Agriculture and Rural AffairsYanglingShaanxi 712100China Shaanxi Key Laboratory of Agricultural Information Perception and Intelligent Service YanglingShaanxi 712100China Faculty of Agriculture University of MiyazakiMiyazaki 8892192Japan

The harvesting of fresh kiwifruit is a labor-intensive operation that accounts for more than 25%of annual production *** harvesting technologies are thus being developed to reduce labor requirements for harvesting *** improve the efficiency of a harvesting robot for picking kiwifruit,we designed an end-effector,which we report herein along with the results of tests to verify its *** using the established method of automated picking discussed in the literature and which is based on the characteristics of kiwifruit,we propose an automated method to pick kiwifruit that consists of separating the fruit from its stem on the *** method is experimentally verified by using it to pick clustered kiwifruit in a scaffolding canopy *** the experiment,the end-effector approaches a fruit from below and then envelops and grabs it with two bionic *** fingers are then bent to separate the fruit from its *** grabbing,picking,and unloading processes are integrated,with automated picking and unloading performed using a connecting rod linkage following a trajectory *** trajectory was analyzed and validated by using a simulation implemented in the software Automatic Dynamic Analysis of Mechanical Systems(ADAMS).In addition,a prototype of an end-effector was constructed,and its bionic fingers were equipped with fiber sensors to detect the best position for grabbing the kiwifruit and pressure sensors to ensure that the damage threshold was respected while *** for size and shape were incorporated by following a trajectory groove from grabbing and picking to *** end-effector separates clustered kiwifruit and automatically grabs individual *** takes on average 4–5 s to pick a single fruit,with a successful picking rate of 94.2%in an orchard test featuring 240 *** study shows the grabbing–picking–unloading robotic end-effector has significant potential to facilitate the harvesting of kiwif

关键词： Kiwifruit End-effector Harvesting robot Trajectory model Simulation analysis

Microstructure and Mechanical Properties of 45 vol.%SiC_p/7075Al Composite

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Journal of Materials Science & Technology 2015年第9期31卷 930-934页

作者： Ziyang Xiu Wenshu Yang Ronghua Dong Murid Hussain longtao Jiang YongXing Liu Gaohui Wu State Key Laboratory of Advanced Welding and Joining Harbin Institute of Technology Department of Material Science and Engineering Harbin Institute of Technology Department of Chemical Engineering COMSATS Institute of Information Technology

Microstructure and mechanical behavior of high volume content SiCp/7xxxAl composites have not been explored yet. Therefore, in the present work, 45 vol.% SiCp/7075Al composite has been prepared by pres- sure infiltration method. High density dislocations were found around SiC/Al interface in SiCp/7075Al composite after water-quenching and aging treatment. Fine dispersed nano-η＇ phases were observed after the aging treatment. Adverse to other SiCp/Al composites prepared by the pressure infiltration method, an interface layer was observed between SiC particles and AI matrix. Furthermore, high-resolution trans- mission electron microscopy （HRTEM） observation indicated that this interface layer was coherent/semi- coherent with that of the SiC particles. 45 vol.% SiCp/7075Al composite demonstrated high tensile strength （630 MPa） and micro-ductility. Compared to aged SiCp/2024Al composite, the aged SiCp/7075Al com- posite showed an increase of about 200% in the tensile strain and 90% in the tensile strength, respectively. It is speculated that nano-η＇ phases in the Al matrix significantly contributed to the strengthening effect while the interface layer between SiC and AI matrix might be beneficial to the strength and plasticity of SiCp/7075Al composite.

关键词： Metal matrix composite7075Al InterfaceNano precipitationMechanical properties

Low-temperature selective synthesis of metastableα-MoC with electrochemical properties:Electrochemical co-reduction of CO_(2)and MoO_(3)in molten salts

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Chinese Chemical Letters 2024年第1期35卷 310-315页

作者： longtao Zhu Yinan Zhao Wenhao Yang Hsien-Yi Hsu Ping Peng Fang-Fang Li School of Materials Science and Engineering Huazhong University of Science and TechnologyWuhan 430074China School of Energy and Environment&Department of Materials Science and Engineering City University of Hong KongHong Kong 999077China

Metastable molybdenum carbide(α-MoC),as a catalyst and an excellent support for metal catalysts,has been widely used in thermo/electro-catalytic ***,the selective synthesis ofα-MoC remains a great ***,a simple one-pot synthetic strategy for the selective preparation of metastableα-MoC is proposed by electrochemical co-reduction of CO_(2)and MoO_(3)in a low-temperature eutectic molten *** synthesizedα-MoC shows a reed flower-like *** controlling the electrolysis time and monitoring the phase and morphology of the obtained products,the growth process ofα-MoC is revealed,where the carbon matrix is deposited first followed by the growth ofα-MoC from the carbon ***,by analyzing the composition of the electrolytic products,the formation mechanism forα-MoC is *** addition,through this one-pot synthetic strategy,S-dopedα-MoC is successfully *** functional theory(DFT)calculations reveal that S doping enhanced the HER performance ofα-MoC by facilitating water absorption and dissociation and weakening the bond energy of Mo-H to accelerate H *** present work not only highlights the valuable utilization of CO_(2) but also offers a new perspective on the design and controllable synthesis of metal carbides and their derivatives.

关键词： α-MoC CO_(2)electroreduction Molten salt Sulfur doping Hydrogen evolution reaction

Numerical and experimental investigation on dynamic performance of bump foil journal bearing based on journal orbit

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Chinese Journal of Aeronautics 2021年第2期34卷 586-600页

作者： Yu ZHOU longtao SHAO Can ZHANG Fenzhu JI Jiang LIU Guo LI Shuiting DING Qi ZHANG Farong DU School of Transportation Science and Engineering Beijing Key Laboratory for High-efficient Power Transmission and System Control of New Energy Resource VehicleBeihang UniversityBeijing 100083China School of Energy ami Pow er Engineering Aircraft/Engine Integrated System Safety Beijing Key LaboratoryBeihang UniversityBeijing 100083China

Widespread usage of bump-type foil journal bearing(BFJB) in oil-free microturbomachinery requires accurate predictions of dynamic performance characteristics, although it remains a challenging issue because BFJB reflects nonlinear both structurally and *** paper presented a simple experimental method to semi-directly obtain the minimum film thickness and dynamic stiffness of BFJB using the journal orbit. Numerical calculations and simulations are conducted to validate the experimental method. The micro-deformation and interaction of various foils are taken into consideration to improve the model precision. The results from the numerical model regarding the BFJB dynamic characteristics are compared with the experimental results coming from a dedicated test rig, which shows that the experimental results fluctuate obviously and agree not well with the numerical results at the start stage due to the presence of dry friction at that time, nevertheless, they show fantastic agreement as soon as a gas film is gradually generated to separate the shaft from the top foil. Therefore, the proposed experimental method is effective to predict film thickness and dynamic characteristics during the period from the lift-off time to the land-off time. The dynamic characteristics, along with the journal orbits also can be used to rapidly predict the dynamics behavior of rotor-bearing systems.

关键词： Bump-type foil journal bearing Dynamic performance Experimental method Journal orbit Numerical calculation

Quantitative study of dimensional stability mechanism and microstructure evolution during precipitation process of 2024Al alloy

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Journal of Materials Science & Technology 2021年第31期90卷 85-94页

作者： Youfang Cao longtao Jiang Deng Gong Guoqin Chen Ziyang Xiu Yangming Cheng Xiufang Wang Gaohui Wua School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China State Key Laboratory of Advanced Welding Production Technology Harbin Institute of TechnologyHarbin 150001China Shanghai Institute of Microsystem and Information Technology Chinese Academy of SciencesShanghai 200050China

In this paper,we were devoted to quantitatively analyzing the dimensional change of 2024 Al alloy during the aging *** of precipitates have been defined and the corresponding volume fraction has been measured with Transmission Electron Microscopy(TEM)and Three-Dimensional Atom Probe Tomography(3 D-APT).Guinier-Preston-Bagaryatsky(GPB)zone(0.86 vol.%)was found after aging for 8 *** zone(0.17 vol.%)and S'phase(1.02 vol.%)was found after aging for 24 *** reduced dimensional change was attributed to the reduction of matrix lattice *** to the initial supersaturated solid solution state,the lattice strain of-2.79×10^(-5)and-5.16×10^(-5)was produced after 8 h and 24 h aging *** difference of the lattice parameters between the precipitates and matrix was also considered.A model was established to quantitatively describe the relationship between the precipitation process and dimensional change of 2024 Al alloy.

关键词： Aluminum alloy Aging Atom probe tomography(APT) Dimensional stability Precipitate

Transformation power or development pressure:economic growth targets and urban carbon productivity

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Chinese Journal of Population,Resources and Environment 2024年第2期22卷 176-184页

作者： longtao Chen Yi Zheng Xianfeng Han Juan Liu School of Management and Economics Kunming University of Science and TechnologyKunming 650500China School of Foreign Languages and Literatures Chongqing Normal UniversityChongqing 401331China

Maintaining moderate economic growth targets(EGTs)is the key for local governments to effectively implement the“carbon peak and carbon neutrality”goals under the refreshed development *** panel data of 276 prefecture-level cities in China's Mainland from 2010 to 2020,and employing methods such as intermediary and threshold models,this study empirically analyzes the internal mechanism of EGT’s impact on urban carbon productivity(UCP).Our findings demonstrate that:①The overall EGT during the analyzed period is not conducive to improving *** conclusion remains valid after a series of robustness *** effect is more pronounced in the central region and resource-based cities than in the east-west region and non resource-based cities.②EGT not only directly suppresses UCP but also exerts indirect negative impacts on UCP from three aspects:delaying the digital economy(DE),constraining financial expansion(FE),and hindering green technology innovation(GTI).This negative indirect effect is similar to or even surpasses the direct effect,suggesting that the internal relationship between EGT and“dual-carbon”goals should be re-evaluated from a new compound perspective.③EGT not only has a simple linear impact on UCP but also significantly exhibits a dynamic evolution pattern in inverted“U”*** is,as EGT continuously upgrades,a nonlinear impact on UCP emerges in the form of“promoting first,suppressing later”.This indicates that surpassing the“degree”limit for EGT will be detrimental to the improvement of *** study broadens the scope of carbon productivity analysis by introducing a new perspective centered on *** insights gleaned from this research offer valuable guidance for local governments to effectively manage economic growth expectations and promote the synchronized achievement of dual-carbon objectives.

关键词： Economic growth target Urban carbon productivity Mediating effects Dynamic evolution

Effect of substrate cooling on the epitaxial growth of Ni-based single-crystal superalloy fabricated by direct energy deposition

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Journal of Materials Science & Technology 2021年第3期62卷 148-161页

作者： Jianwen Nie Chaoyue Chen longtao Liu Xiaodong Wang Ruixin Zhao Sansan Shuai Jiang Wang Zhongming Ren State Key Laboratory of Advanced Special Steels School of Materials Science and EngineeringShanghai UniversityShanghai 200444China

The columnar-to-equiaxed transition(CET)or the formation of stray grains in the laser melting deposition is the least desirable for the repair of single-crystal *** this work,the forced water-cooling was conducted on a single-crystal Rene N5 substrate during the direct energy deposition(DED).The single track remelting,one-layer,two-layer,and eight-layer depositions were investigated to explore the grain growth *** solidification conditions of the DED process,including temperature field,temperature gradient,and solidification speed,were numerically analyzed by a finite element *** single-track remelting results showed that the fraction of columnar crystal regions increases from55.81%in the air-cooled sample to 77.14%in the water-cooled *** single-track deposits of one-and two-layer have the same trend,where the proportion of columnar crystal height was higher under the forced water-cooled *** electron backscattered diffraction(EBSD)grain-structure maps of an eight-layer deposit show that the epitaxial growth height increases from 1 mm in the air-cooling sample to 1.5 mm in the water-cooling *** numerical results showed that the tempe rature gradient in[0011 direction was significantly increased by using forced *** conclusion,the in-situ substrate cooling can become a potential method to promote epitaxial growth during DED via the influence on CET occurrence.

关键词： Direct energy deposition Epitaxial growth Columnar-to-equiaxed transition(CET) Temperature gradient

Effects of drying on the quality characteristics and release of umami substances of Flammulina velutipes

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Food Bioscience 2023年第1期51卷 1046-1056页

作者： Jipeng Wang Songying Jiang Song Miao longtao Zhang Kaibo Deng Baodong Zheng College of Food Science Fujian Agriculture and Forestry UniversityFuzhou350002China China-Ireland International Cooperation Centre for Food Material Science and Structural Design Fuzhou350002China Teagasc Food Research Centre MooreparkFermoyP61C996Co.CorkIreland

The aim of this research was to study the effects of drying methods on the flavor substances of Flammulina velutipes,a common commercial edible *** electron microscopy,high performance liquid chromatography,amino acid analysis,and electronic tongue analysis were used to evaluate the quality characteristics and the release pattern of umami components from *** under hot air drying(HAD),vacuum drying(VD),and vacuum freeze-drying(VFD).Additionally,taste activity value,equivalent umami concentration value,and principal component analysis were *** results indicate each of the drying methods exhibited respective *** under VFD had better micro-spatial structure and high rehydration capacity,followed by *** VD treatment,dried *** had the highest levels of free amino acids and organic acids,especially the umami amino acids Glu and Asp were significantly retained and *** with other methods,the content of umami 5′-nucleotides(5′-IMP,5′-GMP)in *** was the highest under HAD and at 50℃ had the highest level of equivalent umami concentration(EUC)*** results showed that the mutual regulation of flavor substances in *** was related to the drying method,and HAD at 50℃ was the optimal method to preserve flavor substances and quality characteristics in *** results can provide a method reference for the production of dried Flammulina velutipes with good flavor.

关键词： Flammulina velutipes Drying methods Quality characteristics Umami components

Technologies and studies of gas exchange in two-stroke aircraft piston engine:A review

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Chinese Journal of Aeronautics 2024年第1期37卷 24-50页

作者： Yu ZHOU Xueyu LI Shuiting DING Shuai ZHAO Kun ZHU longtao SHAO Farong DU Gerui WANG Zheng XU Research Institute of Aero-Engine Beihang UniversityBeijing 100191China Aircraft/Engine Integrated System Safety Beijing Key Laboratory Beijing 100191China School of Transportation Science and Engineering Beihang UniversityBeijing 100191China Civil Aviation University of China Tianjin 300300China Aero Engine Academy of China Beijing 101304China School of Energy and Power Engineering Beihang UniversityBeijing 100191China Beihang Hangzhou Innovation Institute Yuhang Hangzhou 310052China

The in-cylinder gas exchange process is crucial to the power performance of two-stroke aircraft piston engines,which is easily influenced by complex factors such as high-altitude performance variation and in-cylinder flow *** paper reviews the development history and characteristics of gas exchange types,as well as the current state of theory and the validation methods of gas exchange technology,while also discusses the trends of cutting-edge technologies in the *** paper provides a theoretical foundation for the optimization and engineering design of gas exchange systems and,more importantly,points out that the innovation of gas exchange types,the modification of theoretical models,and the technology of variable airflow organization are the key future research directions in this field.

关键词： Aircraft piston engine Aircraft power systems Gas exchange High-altitude performance In-cylinder flow Two-stroke Unmanned Aerial Vehicles(UAVs)