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Austenite Grain Refinement by Reverse α′→γ Transformation in Metastable Austenitic Manganese Steel

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Journal of Iron and Steel Research International 2015年第2期22卷 157-162页

作者： Jia-tao ZHANG yu-guang zhao Juan TAN Xiao-feng XU Key Laboratory of Automobile Materials of Ministry of Education Department of Materials Science and EngineeringJilin University

Microstructure of metastable austenitic manganese steel after reverse transformation treatment was investi gated using optical microscopy, X ray diffraction （XRD）, electrical resistivity and hardness testing. Austenite grain refinement was successfully achieved by a two-step heat treatment. First, martensite was produced by cooling the so- lution-treated samples to --196 ℃. Then, the deep cryogenic treated samples were heated to 850 ℃ upon slow or rapid heating. The mean size of original austenite grain was about 400 fire. But the mean size of equiaxed reversion austenite was refined to 50 μm. Microstructure evolution and electrical resistivity change showed that martensite plates underwent tempering action upon slow heating, and the residual austenite was decomposed, resulting in the formation of pearlite nodules at the austenite grains boundaries. The refinement mechanism upon slow heating is the diffusion-controlled nucleation and growth of austenite. However, the reverse transformation upon rapid heating was predominated by displacive manner. The residual austenite was not decomposed. The plate α-phase was carbon-super- saturated until the starting of reverse transformation. The reverse transformation was accompanied by surface effect, resulting in the formation of plate austenite with high density dislocations. The refinement mechanism upon rapid heating is the recrystallization of displacive reversed austenite.

关键词： grain refinement displacive reverse transformation recrystallization metastable austenitic manganese steel

Microstructure Refinement and Property Improvement of Metastable Austenitic Manganese Steel Induced by Electropulsing

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Journal of Iron and Steel Research International 2014年第7期21卷 685-689页

作者： yu-guang zhao Jia-tao ZHANG Juan TAN Bing-dong MA Key Laboratory of Automobile Materials of Ministry of Education Department of Materials Science and EngineeringJilin University

Grain refinement efficiency of electropulsing treatment （EPT） for metastable austenitic manganese steel was investigated. The mean grain size of original austenite is 300 ptm. However, after EPT, the microstructure ex hibits a bimodal grain size distribution, and nearly 70vol. % grains are less than 60 /Lm. The refined austenite results in ultrafine martensitic microstrncture. The tensile strengths of refined austenitic and martensitic microstructures were improved from 495 to 670, and 794 to 900 MPa respectively. The fine grained materials possess better fracture toughness. The work hardening capacity and wear resistance of the refined austenitic microstructure are improved. The reasonable mechanism of grain refinement is the combination of accelerating new phase nucleation and restraining the growth of neonatal austenitic grain during reverse transformation and rapid recrystallization induced by electropulsing.

关键词： eleetropulsing grain refinement metastable austenitic manganese steel

Applying Lambert problem to association of radar-measured orbit tracks of space objects

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Research in Astronomy and Astrophysics 2021年第12期21卷 337-350页

作者： Lei Liu Bin Li Jun-yu Chen Xiang-Xu Lei guang-yu zhao Ji-Zhang Sang School of Geodesy and Geomatics Wuhan UniversityWuhan 430079China Collaborative Innovation Center for Geospatial Technology Wuhan 430079China School of Civil and Architectural Engineering Shandong University of TechnologyZibo 255000China

Thousands of orbit tracks of space objects are collected by a radar each day,and many may be from uncatalogued *** such,it is an urgent demand to catalogue the uncatalogued objects,which requires to determine whether two or more un-correlated tracks(UCTs)are from the same *** paper proposes to apply the Lambert problem to associate two radar-measured orbit tracks of LEO and HEO objects.A novel method of position correction is proposed to correct the secular and short periodic effects caused by the J_2 perturbation,making the Lambert problem applicable to perturbed orbit *** that,an orbit selection method based on the characteristics of residuals solves the multiple-revolution Lambert *** experiments with simulated radar measurements of LEO and HEO objects are carried out to assess the performance of the proposed *** is shown that the semi-major axis can be determined with an error less than 200 m from two tracks separated by 4 *** true positive(TP)rates for associating two LEO tracks apart by less than 6 days are 94.2%.The TP rate is still at 73.1%even for two tracks apart by 8–9 *** results demonstrate the strong applicability of the proposed method to associate radar measurements of uncatalogued objects.

关键词： celestial mechanics methods:analytical techniques:miscellaneous surveys

A new preparation technology of structural- gradient materials without a brittle transition zone in a Mn-Si-Cr-B bainitic cast steel

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China Foundry 2018年第4期15卷 283-290页

作者： yu-guang zhao zhe wang xiao-feng xu ming-zhe zhang wen-qiang jiang key laboratory of automobile of ministry of Education ＆school of Materials Science and Engineering Nanling Campusjilin UniversityNO.5988 Renmin streetchangchun 130025china

In the present work, a unique gradient cooling heat treatment process(GCHT) for a Mn-Si-Cr-B bainitic cast steel was developed, and microstructure and mechanical properties were examined by OM, SEM, EBSD and a uniaxial tensile test. The results showed that the structural-gradient-material(SGM) with a gradient microstructure from granular bainite to martensite was successfully produced, and it exhibited a good ductility(~13.8%) at one end and an excellent ultimate strength(~1,720 MPa) at the other end. In between the bainite and martensite, a transition region with a superior combination of tensile strength and ductility(1,700 MPa and 11.1%) was obtained, which is different from the normal knowledge of a brittle transition region. Moreover, through changing the gradient of cooling rate, the optimized SGM with a new gradient microstructure from pearlite to martensite showed a more stable structural gradient and an improved ductility(22.8%) at one end. The microstructure variation in the sample was mainly related to the carbon diffusion rate during heat treatment, and the diffusion rate could be controlled by regulating the cooling velocity. Therefore, the SGMs with different gradient microstructures could be designed to meet the needs of different properties. As a result, this work provides a new approach for preparation of the gradient structured steel, which has potential for practical application for dual-property automobile parts.

关键词： bainitic cast steel gradient cooling heat treatment structural-gradient-materials

Generation and Characterization of a Nanobody Against SARS-CoV

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Virologica Sinica 2021年第6期36卷 1484-1491页

作者： Jiang-Fan Li Lei He Yong-Qiang Deng Shu-Hui Qi yue-Hong Chen Xiao-Lu Zhang Shi-Xiong Hu Rui-Wen Fan guang-yu zhao Cheng-Feng Qin State Key Laboratory of Pathogen and Biosecurity Beijing Institute of Microbiology and EpidemiologyAcademy of Military Medical Sciences(AMMS)Beijing 100071China College of Veterinary Medicine Shanxi Agriculture UniversityJinzhong 030801China Research Unit of Discovery and Tracing of Natural Focus Diseases Chinese Academy of Medical SciencesBeijing 100071China

The sudden emergence of severe acute respiratory syndrome coronavirus(SARS-CoV) has caused global panic in 2003,and the risk of SARS-CoV outbreak still exists. However, no specific antiviral drug or vaccine is available;thus, the development of therapeutic antibodies against SARS-CoV is needed. In this study, a nanobody phage-displayed library was constructed from peripheral blood mononuclear cells of alpacas immunized with the recombinant receptor-binding domain(RBD) of SARS-CoV. Four positive clones were selected after four rounds of bio-panning and subjected to recombinant expression in E. coli. Further biological identification demonstrated that one of the nanobodies, S14, showed high affinity to SARS-CoV RBD and potent neutralization activity at the picomole level against SARS-CoV pseudovirus. A competitive inhibition assay showed that S14 blocked the binding of SARS-CoV RBD to either soluble or cell-expressed angiotensinconverting enzyme 2(ACE2). In summary, we developed a novel nanobody targeting SARS-CoV RBD, which might be useful for the development of therapeutics against SARS.

关键词： Severe acute respiratory syndrome coronavirus(SARS-CoV) Receptor-binding domain(RBD) Nanobody Neutralizing antibody

Radiofrequency catheter ablation of idiopathic ventricular tachycardia and symptomatic premature ventricular contraction originating from valve annulus

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Chinese Medical Journal 2008年第22期121卷 2241-2245页

作者： WU Xiao-yu LIANG zhao-guang TAN Zhen GU Hong-yue ZHANG Shu LI Wei-min Department of Cardiology First Affiliated Hospital of Harbin Medical University Harbin Heilongjiangl50001 China

Background Radiofrequency catheter ablation （RFCA） has been established as an effective and curative therapy for ventricular tachycardia （VT） and severely symptomatic premature ventricular contraction （PVC） from the outflow tract in structurally normal hearts. This study aimed to investigate electrophysiologic characteristics and effects of RFCA for patients with idiopathic VT and symptomatic PVC originating from the valve annulus. Methods Characteristics of body surface electrocardiogram （ECG） and endocardiogram in a successful RFCA target were analyzed in 16 patients with idiopathic VT and symptomatic PVC originating from the valve annulus. Additionally, the ECG characteristics of VT or PVC were compared with those of manifest Wolff-Parkinson-White （WPW） syndrome originating from the same site of origin in 15 patients. Results Thirteen patients were successful, 2 recurrent and 1 failed. The recurrent cases underwent successful ablation the second time guided by the Ensite 3000 mapping system. In all patients with the WPW syndrome, the characteristics of QRS morphology were well matched with those of the VT and PVC that originated from corresponding sites of origin. Conclusions RFCA is an effective curative therapy for VT and There are specific characteristics in ECG and the ablation site accessory pathway＇s algorithm. symptomatic PVC originating from the valve annulus. could be located by means of the WPW syndrome

关键词： ventricular tachycardia valve annulus radiofrequency catheter ablation

A Novel Method for Flatness Pattern Recognition via Least Squares Support Vector Regression

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Journal of Iron and Steel Research International 2012年第3期19卷 25-30页

作者： ZHANG Xiu-ling, ZHANG Shao-yu, TAN guang-zhong, zhao Wen-bao (Key Laboratory of Industrial Computer Control Engineering of Hebei Province, National Engineering Research Center for Equipment and Technology of Cold Strip Rolling, Yanshan University, Qinhuangdao 066004, Hebei, China) Key Laboratory of Industrial Computer Control Engineering of Hebei Province National Engineering Research Center for Equipment and Technology of Cold Strip Rolling Yanshan University Qinhuangdao 066004 Hebei China

To adapt to the new requirement of the developing flatness control theory and technology, cubic patterns were introduced on the basis of the traditional linear, quadratic and quartic flatness basic patterns. Linear, quadratic, cubic and quartic Legendre orthogonal polynomials were adopted to express the flatness basic patterns. In order to over- come the defects live in the existent recognition methods based on fuzzy, neural network and support vector regres- sion （SVR） theory, a novel flatness pattern recognition method based on least squares support vector regression （LS-SVR） was proposed. On this basis, for the purpose of determining the hyper-parameters of LS-SVR effectively and enhan- cing the recognition accuracy and generalization performance of the model, particle swarm optimization algorithm with leave-one-out （LOO） error as fitness function was adopted. To overcome the disadvantage of high computational complexity of naive cross-validation algorithm, a novel fast cross-validation algorithm was introduced to calculate the LOO error of LDSVR. Results of experiments on flatness data calculated by theory and a 900HC cold-rolling mill practically measured flatness signals demonstrate that the proposed approach can distinguish the types and define the magnitudes of the flatness defects effectively with high accuracy, high speed and strong generalization ability.

关键词： flatness pattern recognition least squares support vector regression cross-validation

电动汽车电机驱动系统分布参数对传导电磁干扰影响研究

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北京理工大学学报 2016年第9期36卷 935-939页

作者：翟丽张新宇李广召北京理工大学机械与车辆学院北京100081

构建了电动汽车电机驱动系统传导电磁干扰测试平台,研究电动汽车电机驱动系统带载工况下分布参数对传导电磁干扰的影响.通过测试比较电机驱动系统带载工况下和空载工况下产生的传导电磁干扰,分析系统高低频差模干扰和共模干扰的传播路径... 详细信息

构建了电动汽车电机驱动系统传导电磁干扰测试平台,研究电动汽车电机驱动系统带载工况下分布参数对传导电磁干扰的影响.通过测试比较电机驱动系统带载工况下和空载工况下产生的传导电磁干扰,分析系统高低频差模干扰和共模干扰的传播路径,建立相应的等效电路,在频域内分析了传导电磁干扰产生的机理和分布参数对传导电磁干扰的影响.测试结果表明,适当增大电机控制器内部功率器件对地分布电容和直流动力线缆对地分布电容可减小系统产生的高频传导电磁干扰.

关键词：电动汽车电机驱动系统传导电磁干扰分布参数

Dynamic Regulation of Hydrogen Bonding Networks and Solvation Structures for Synergistic Solar‑Thermal Desalination of Seawater and Catalytic Degradation of Organic Pollutants

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Nano-Micro Letters 2025年第2期17卷 548-565页

作者： Ming‑yuan yu Jing Wu guang Yin Fan‑Zhen Jiao Zhong‑Zhen yu Jin Qu Beijing Key Laboratory of Advanced Functional Polymer Composites Beijing University of Chemical TechnologyBeijing 100029People’s Republic of China State Key Laboratory of Organic‑Inorganic Composites College of Materials Science and EngineeringBeijing University of Chemical TechnologyBeijing 100029People’s Republic of China

Although solar steam generation strategy is efficient in desalinating seawater,it is still challenging to achieve continuous solar-thermal desalination of seawater and catalytic degradation of organic ***,dynamic regulations of hydrogen bonding networks and solvation structures are realized by designing an asymmetric bilayer membrane consisting of a bacterial cellulose/carbon nanotube/Co_(2)(OH)_(2)CO_(3)nanorod top layer and a bacterial cellulose/Co_(2)(OH)_(2)CO_(3)nanorod(BCH)bottom ***,the hydrogen bonding networks inside the membrane can be tuned by the rich surface–OH groups of the bacterial cellulose and Co_(2)(OH)_(2)CO_(3)as well as the ions and radicals in situ generated during the catalysis ***,both SO_(4)^(2−)and HSO_(5)−can regulate the solvation structure of Na^(+)and be adsorbed more preferentially on the evaporation surface than Cl^(−),thus hindering the de-solvation of the solvated Na^(+)and subsequent nucleation/growth of ***,the heat generated by the solar-thermal energy conversion can accelerate the reaction kinetics and enhance the catalytic degradation *** work provides a flow-bed water purification system with an asymmetric solar-thermal and catalytic membrane for synergistic solar thermal desalination of seawater/brine and catalytic degradation of organic pollutants.

关键词： Solar steam generation Seawater desalination Catalytic degradation Bacterial cellulose Cobalt hydroxycarbonate nanorods