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Rare Metals 2022年第10期41卷 3560-3565页

作者： Ya-Bo Fu Yi-Ping Lu zhi-Jun Wang zhi-qiang cao Ai-Jiao Xu School of Physics and Electronic Engineering Taizhou UniversityTaizhou318000China School of Materials Science and Engineering Dalian University of TechnologyDalian116024China School of Materials Science and Engineering Northwestern Polytechnical UniversityXi’an710048China

Cu-36 wt%Zn alloy is widely used in valves of water and heating and auto parts,***,the structure is still coarse,and performances are much *** structure and performances of Cu-36 wt%Zn alloy were investigated by adding Al_(2)O_(3)nanoparticles and *** indicate that by Al_(2)O_(3)nanoparticles coupling electromagnetic stirring,the Cu-36 wt%Zn alloy with refined microstructure was successfully *** average grain size is refined by 99%compared with that without nanoparticles and *** tensile strength(R_m)and percentage elongation after fracture(A11.3)increase by 20.58%and 19.40%,respectively,compared with that without nanoparticles and *** increase heterogeneous nucleation rate by 50%compared with that without *** depth of dezincification layer decreases by 78.71%compared with that without nanoparticles and stirring,as protective layer(Cu-Al_(2)O_(3)-Zn)is completely formed around the grain boundaries.

关键词： Microstructural refinement Rotating electromagnetic field Mechanical performance Al_(2)O_(3)nanoparticles

A New Monocular Vision Measurement Method to Estimate 3D Positions of Objects on Floor

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International Journal of Automation and computing 2017年第2期14卷 159-168页

作者： Ling-Yi Xu zhi-qiang cao Peng Zhao Chao Zhou State Key Laboratory of Management and Control for Complex Systems Institute of AutomationChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 101408China

A new visual measurement method is proposed to estimate three-dimensional （3D） position of the object on the floor based on a single camera. The camera fixed on a robot is in an inclined position with respect to the floor. A measurement model with the camera＇s extrinsic parameters such as the height and pitch angle is described. Single image of a chessboard pattern placed on the floor is enough to calibrate the camera＇s extrinsic parameters after the camera＇s intrinsic parameters are calibrated. Then the position of object on the floor can be computed with the measurement model. Furthermore, the height of object can be calculated with the paired-points in the vertical line sharing the same position on the floor. Compared to the conventional method used to estimate the positions on the plane, this method can obtain the 3D positions. The indoor experiment testifies the accuracy and validity of the proposed method.

关键词： Visual measurement, calibration, localization, position estimation monocular vision.

A comprehensive review on microchannel heat sinks for electronics cooling

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International Journal of Extreme Manufacturing 2024年第2期6卷 133-162页

作者： zhi-qiang Yu Mo-Tong Li Bing-Yang cao Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Department of Engineering MechanicsTsinghua UniversityBeijing 100084People’s Republic of China

The heat generation of electronic devices is increasing dramatically,which causes a serious bottleneck in the thermal management of electronics,and overheating will result in performance deterioration and even device *** the development of micro-machining technologies,the microchannel heat sink(MCHS)has become one of the best ways to remove the considerable amount of heat generated by high-power *** has the advantages of large specific surface area,small size,coolant saving and high heat transfer *** paper comprehensively takes an overview of the research progress in MCHSs and generalizes the hotspots and bottlenecks of this *** heat transfer mechanisms and performances of different channel structures,coolants,channel materials and some other influencing factors are ***,this paper classifies the heat transfer enhancement technology and reviews the related studies on both the single-phase and phase-change flow and heat *** comprehensive review is expected to provide a theoretical reference and technical guidance for further research and application of MCHSs in the future.

关键词： microchannel heat sink thermal management of electronics microscale heat transfer heat transfer enhancement

Microstructure and wear resistance of AlCrFeNiMo_(0.5)Si_(x) high-entropy alloy coatings prepared by laser cladding

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China Foundry 2022年第6期19卷 473-480页

作者： Xiao-cong Li Hui Liang Yan-zhou Zhao Li Gao Li Jiang zhi-qiang cao Key Laboratory of Solidification Control and Digital Preparation Technology(Liaoning Province) School of Materials Science and EngineeringDalian University of TechnologyDalian 116024LiaoningChina School of Physics and Electronic Technology Liaoning Normal UniversityDalian 116029LiaoningChina

In recent years,the coating prepared by laser cladding has attracted much attention in the field of wear *** this work,AlCrFeNiMo_(0.5)Si_(x)(x=0,0.5,1.0,1.5,2.0)high-entropy alloy coatings were designed and prepared on Q235 steel by laser *** effect of Si content on microstructure,microhardness and wear resistance of the coatings was studied in *** results indicate that the AlCrFeNiMo_(0.5)Si_(x) highentropy alloy coatings show an excellent bonding between substrate and the cladding *** AlCrFeNiMo_(0.5)Si_(x) coatings are composed of nano-precipitated phase with BCC structure and matrix with ordered B2 *** the addition of Si,the white phase(Cr,Mo)_(3)Si with cubic structure appears in the interdendritic,and the morphology of the coating(x=2.0)transforms into lamellar eutectic-like *** addition of Si enhances the microhardness and significantly improves the wear resistance of the *** x increases from 0 to 2.0,the average hardness of the cladding zone increases from 632 HV to 835 HV,and the wear rate decreases from 1.64×10^(-5) mm^(3)·(N·m)^(-1) to 5.13×10^(-6) mm^(3)·(N·m)^(-1).When x≥1.5,the decreasing trend of the wear rate gradually slows *** wear rates of Si1.5 and Si2.0 coatings are 5.85×10^(-6) mm^(3)·(N·m)^(-1) and 5.13×10^(-6) mm^(3)·(N·m)^(-1),respectively,which is an order of magnitude lower than that of Q235 steel.

关键词： high-entropy alloy coatings laser cladding microstructure wear resistance

A Novel Series of Refractory High-Entropy Alloys Ti2ZrHf0.5VNbx with High Specific Yield Strength and Good Ductility

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Acta Metallurgica Sinica(English Letters) 2019年第8期32卷 925-931页

作者： Dong-Xu Qiao Hui Jiang Wen-Na Jiao Yi-Ping Lu zhi-qiang cao Ting-Ju Li Key Laboratory of Solidification Control and Digital Preparation Technology(Liaoning Province) School of Materials Science and EngineeringDalian University of TechnologyDalian 116024China College of Mechanical and Electronic Engineering Shandong University of Science and TechnologyQingdao 266590China

A series of Ti2ZrHf0.5VNbx( x = 0, 0.25, 0.5, 0.75 and 1.0) refractory high-entropy alloys were prepared to investigate the alloying effect of Nb on the microstructures and mechanical *** the alloys displayed a simple BCC *** microstructures of the alloys changed from the initial single-phase columnar structure( x = 0) to dendrite microstructure( x > 0).At room temperature, all the alloys exhibited high ductility(with the compressive strains of more than 50%).With the increase in Nb content, the yield strength slightly decreased from 1160 to 980 MPa and the hardness dropped from 338 to 310 ***, the alloys exhibited low density from 6.47 to 6.84 g/cm3 and high specific yield strength(SYS) from 143 to 179 kPa m3/*** comprehensive performance of ductility and SYS was superior to most of the reported highentropy *** yield strength of the alloys increased from 405 to 859 MPa and from 85 to 195 MPa with the addition of Nb element at 873 K and 1073 K, respectively.

关键词： Specific yield strength Refractory metals Structure Mechanical properties

Toughening mechanisms of a high-strength acicular ferrite steel heavy plate

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International Journal of Minerals,Metallurgy and Materials 2010年第5期17卷 567-572页

作者： zhi-qiang cao Yan-ping Bao Zheng-hai Xia Deng Luo Ai-min Guo Kai-ming Wu Engineering Research Institute University of Science and Technology Beijing Beijing 100083 China Research ＆ Development Center Xiangtan Iron and Steel Co. Ltd. Xiangtan 411101 China Hubei Province Key Laboratory for Systems Science on Metallurgical Processing Wuhan University of Science and Technology Wuhan 430081 China

An ultra-low carbon acicular ferrite steel heavy plate was obtained with an advanced thermo-mechanical control process-relaxed precipitation controlled transformation （TMCP-RPC） at Xiangtan Steel, Valin Group. The heavy plate has a tensile strength of approximately 600 MPa with a lower yield ratio. The impact toughness of the heavy plate achieves 280 J at ？40°C. The fine-grained mixed microstructures of the heavy plate mainly consist of acicular ferrite, granular bainite, and polygonal ferrite. The high strength and excellent toughness of the heavy plate are attributed to the formation of acicular ferrite microstructure. The prevention of blocks of martensite/retained austenite （M/A） and the higher cleanness are also responsible for the superior toughness.

关键词： high-strength steel microstructure mechanical properties acicular ferrite

An Online Q-Learning Method for Linear-Quadratic Nonzero-Sum Stochastic Differential Games with Completely Unknown Dynamics

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Journal of Systems Science & Complexity 2024年第5期37卷 1907-1922页

作者： ZHANG Bao-qiang WANG Bing-Chang cao Ying School of Control Science and Engineering Shandong University

In this paper, the authors design a reinforcement learning algorithm to solve the adaptive linear-quadratic stochastic n-players non-zero sum differential game with completely unknown dynamics. For each player, a critic network is used to estimate the Q-function, and an actor network is used to estimate the control input. A model-free online Q-learning algorithm is obtained for solving this kind of problems. It is proved that under some mild conditions the system state and weight estimation errors can be uniformly ultimately bounded. A simulation with five players is given to verify the effectiveness of the algorithm.

关键词： Actor-critic algorithm model-free adaptive control nonzero-sum stochastic game reinforcement learning

Tungsten-containing high-entropy alloys: a focused review of manufacturing routes, phase selection, mechanical properties, and irradiation resistance properties

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Tungsten 2021年第2期3卷 181-196页

作者： Tian-Xin Li Jun-Wei Miao En-Yu Guo He Huang Jun Wang Yi-Ping Lu Tong-Min Wang zhi-qiang cao Ting-Ju Li Key Laboratory of Solidifi cation Control and Digital Preparation Technology(Liaoning Province) School of Materials Science and EngineeringDalian University of TechnologyDalian 116024China Institute of Materials China Academy of Engineering PhysicsMianyang 621907China State Key Laboratory of Solidifi cation Processing Northwestern Polytechnical UniversityXi’an 710072China High Entropy Alloy Materials Engineering Research Center(Liaoning Province) School of Materials Science and EngineeringDalian University of TechnologyDalian 116024China

Alloying is one of the most effective means to confer superior properties to metal *** far too long,conventional W-based alloys were generally improved by the addition of minor *** exploitation of conventional W-based alloy is restricted to the corner of multielement phase diagrams with tiny compositional ***-entropy alloys(HEAs)are a novel kind of alloys consisting of multi-principal alloying elements(usually more than 4)and have attracted increasing attention,since they were first reported in *** emergence of HEAs filled the gap of the unexplored central region of multielement phase *** them,tungsten-containing HEAs(TCHEAs)exhibit excellent mechanical properties,especially at extraordinarily elevated ***,recent studies showed that TCHEAs had outstanding irradiation resistance *** might serve as a promising candidate for plasma-facing materials in the fusion *** characteristics of TCHEAs are different from other HEAs due to the addition of tungsten with ultrahigh-melting ***,this paper aimed to introduce the manufacturing routes of TCHEAs;review the phase selection,mechanical properties,and irradiation resistance properties of TCHEAs;and propose the future prospects of TCHEAs.

关键词： Tungsten-containing high-entropy alloys Irradiation resistance properties Mechanical properties Manufacturing routes Phase selection

Optimization design of wide face water slots for medium-thick slab casting mold

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China Foundry 2016年第5期13卷 327-334页

作者： Xue-lin Yin Li Wu Jun-jia Zhang Hui-jun Kang Zong-ning Chen Jin-song Chen zhi-qiang cao Ting-ju Li Tong-min Wang Key Laboratory of Solidification Control and Digital Preparation Technology (Liaoning Province) School of Materials Science and Engineering Dalian University of Technology Laboratory of Special Processing of Raw Materials Dalian University of Technology Dalian Dashan Heavy Machinery Co. Ltd.

A three-dimensional finite-element model has been established to investigate the thermal behavior of the medium-thick slab copper casting mold with different cooling water slot designs. The mold wall temperatures measured using thermocouples buried in different positions of the mold with the original designed cooling system were analyzed to determine the corresponding heat flux profile. This profile was then used for simulation to predict the temperature distribution and the thermal stress distribution of the molds. The predicted temperatures during operation matched the plant measurements. The results showed that the maximum temperature, about 635 K in the wide hot surface, was found about 60 mm below the meniscus and 226 mm from the center of the mold. For the mold with the type I modified design, there was an insignificant decrease in temperature of about 5 K, and for the mold with the type II modified design, the maximum temperature was decreased by about 15 K and the temperature of the hot surface was distributed more uniformly along the length of the mold. The corresponding maximum thermal stress at the hot surface of the mold was reduced from 408 MPa to 386 MPa with the type II modified design. The results indicated that the modified design II is beneficial to the increase of mold life and the quality of casting slabs.

关键词： medium-thick slab casting mold water slots design heat flux profile thermal behavior finiteelement analysis

Precise Asymptotics in Limit Theorems for a Supercritical Branching Process with Immigration in a Random Environment

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Acta Mathematica Sinica,English Series 2024年第8期40卷 1850-1874页

作者： Chun Mao HUANG Rui ZHANG zhi qiang GAO Department of Mathematics Harbin Institute of Technology(Weihai)Weihai 264209P.R.China School of Mathematical Sciences Beijing Normal UniversityBeijing 100875P.R.China

Let(Zn)be a supercritical branching process with immigration in an independent and identically distributed random *** necessary moment conditions,we show the exact convergence rate in the central limit theorem on log Zn and establish the corresponding local limit theorem by using the moments of the natural submartingale and the convergence rates of its *** similar approach and with the help of a change of measure,we also present the so-called integrolocal theorem and integral large deviation theorem to characterize the precise asymptotics of the upper large deviations.

关键词： Branching process with immigration random environment central limit theorem large deviation