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Microstructural Evolution of a Hypoeutectoid Pearlite Steel under Rolling-sliding Contact Loading

Journal of Iron and Steel Research International 2016年第10期23卷 1054-1060页

作者： Qiu-han LI Chi ZHANG Hu chen hao chen Zhi-gang YANG Key Laboratory of Advanced Materials of Ministry of Education School of Materials Science and EngineeringTsinghua University

To study the microstructural evolution of pearlite steel subjected to pure rolling and rolling-sliding contact loading,a hypoeutectoid pearlite steel with composition and microstructure similar to BS11 was designed and twindisc tests of this pearlite steel were performed to simulate the wheel/rail *** a series of twin-disc tests,optical microscope（OM）observation,scanning electron microscope（SEM）observation,X-ray diffraction（XRD）,and micro-hardness tests were conducted to characterize the *** the pure rolling contact condition,a large amount of reticular cracks emerged within 60μm below the contact surface of the samples after 120 000 *** largest deformation was approximately 200μm below the contact *** the rolling-sliding contact condition,the nodularization of pearlite within 100μm below the contact surface was *** microstructure and stress-strain distribution of the area within 2mm below the contact surface were *** distribution of micro-hardness under the contact surface varied with contact *** element method（FEM）was used to simulate the stress-strain *** results of SEM,FEM,and micro-hardness tests indicated that under the pure rolling contact condition,the maximum plastic strain was approximately 200-400μm below the contact ***,under the rolling-sliding contact condition,the maximum plastic strain emerged on the contact *** the pure rolling contact condition,the distribution of micro-hardness was almost identical to that of the equivalent plastic *** the rolling-sliding contact condition,the distribution of micro-hardness was affected by the equivalent plastic strain and tangential stress.

关键词： twin-disc test rail micro-hardness plastic strain finite element method hypoeutectoid pearlite steel rolling-sliding contact

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Rheological and mechanical properties of aluminosilicious cementitious materials as refractory castable binders

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Journal of Iron and Steel Research International 2022年第7期29卷 1145-1151页

作者： Zhong-feng Xia Chang-hao chen Wen-hao Chi Zhou-fu Wang hao Liu Yan Ma Xi-tang Wang The State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and TechnologyWuhan 430081HubeiChina

Metakaolin(MK)is an important refractory raw material,which has been used as a cementitious *** order to improve the bonding strength of MK,the composite cementitious materials were prepared by MK mixed with hydrat-able alumina(HA)and microsilica(MS),*** silane coupling agent(SCA)was introduced as a modifying *** rheological properties of MK-based composite cementitious slurries were *** mechanical properties of corundum castables bonded with the composite cementitious materials and calcium aluminate cement(CAC)were comparatively *** results show that SCA improves the rheological properties of MK-based composite cementitious *** slurry of MK–MS mixture flows in a plastic manner,while the slurry of MK–HA mixture presents pseudoplastic *** addition of SCA reduces the yield stress value of the MK–HA *** bonding strength of castables bonded with MK-based composite cementitious materials is lower than that of CAC bonding *** room temperature strength of MK–MS composite bonding castable remains the highest after being treated either at 1100 or 1550°C,and its high temperature modulus of rupture is higher than that of CAC bonding castables with microsilica added.

关键词： Metakaolin Hydratable alumina Microsilica Silane coupling agent Corundum castable Calcium aluminate cement

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Folding beam-type piezoelectric phononic crystal with low-frequency and broad band gap

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Applied Mathematics and Mechanics(English Edition) 2017年第3期38卷 411-422页

作者： Shan JIANG Longxiang DAI hao chen Hongping HU Wei JIANG Xuedong chen Department of Mechanics Huazhong University of Science and Technology Wuhan 430074 China Hubei Key Laboratory of Engineering Structural Analysis and Safety Assessment Huazhong University of Science and Technology Wuhan 430074 China State Key Laboratory of Digital Manufacturing Equipment and Technology Huazhong University of Science and Technology Wuhan 430074 China

A folding beam-type piezoelectric phononic crystal model is proposed to isolate vibration. Two piezoelectric bimorphs are joined by two masses as a folding structure to comprise each unit cell of the piezoelectric phononic crystal. Each bimorph is connected independently by a resistive-inductive resonant shunting circuit. The folding structure extends the propagation path of elastic waves, while its structure size remains quite small. Propagation of coupled extension-flexural elastic waves is studied by the classical laminated beam theory and transfer matrix method. The theoretical model is further verified with the finite element method(FEM). The effects of geometrical and circuit parameters on the band gaps are analyzed. With only 4 unit cells, the folding beam-type piezoelectric phononic crystal generates two Bragg band gaps of 369 Hz to1 687 Hz and 2 127 Hz to 4 000 Hz. In addition, between these two Bragg band gaps, a locally resonant band gap is induced by resonant shunting circuits. Appropriate circuit parameters are used to join these two Bragg band gaps by the locally resonant band ***, a low-frequency and broad band gap of 369 Hz to 4 000 Hz is obtained.

关键词： folding beam-type structure phononic crystal band gap wave propagation piezoelectric

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Modeling of sensor function for piezoelectric bender elements

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第1期9卷 1-7页

作者： Yan-guo ZHOU Yun-min chen hao-jiang DING Wei-qiu chen Key Laboratory of Soft Soils and Geoenvironmental Engineering Ministry of Education Zhejiang University Hangzhou 310027 China

An analytical sandwich beam model for piezoelectric bender elements is derived based on the first-order shear deformation theory (FSDT), which assumes a single rotation angle for the whole cross-section and a quadratic distribution for coupled electric potential in piezoelectric layers. Shear coefficient is introduced to correct the effect of transverse shear strain on shear force and the electric displacement integration. Static and free vibration analyses of simply-supported bender elements are carried out for the sensor function. The results illustrate the high accuracy of the present model compared with the exact 2D solutions.

关键词： Bender elements Piezoelectric Sensor Sandwich beam Shear coefficient

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GP Algorithm-Based Fourier Transform Infrared Spectrum Trend Term Removal Model

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Journal of Beijing Institute of Technology 2023年第1期32卷 41-51页

作者： Bo Yan Shuaihui Li hao chen School of Engineering Science University of Chinese Academy of SciencesBeijing 100049China State Key Laboratory of High Temperature Gas Dynamics Institute of MechanicsChinese Academy of SciencesBeijing 100190China

Trend term removal is a key step in Fourier transform infrared spectroscopy(FTIR)data *** most commonly used least squares(LS)method,although satisfying the real-time requirement,has many problems such as highly correlated initial values of the expression parameters,the need to pre-estimate the trend term shape,and poor fitting accuracy at low signal-to-noise *** order to achieve real-time and robust trend term removal,a new trend term removal method using genetic programming(GP)in symbolic regression is constructed in this paper,and the FTIR simulation interference results and experimental measurement data for common volatile organic compounds(VOCs)gases are *** results show that the genetic programming algorithm can both reduce the initial value requirement and greatly improve the trend term accuracy by 20%-30% in three evaluation indicators,which is suitable for gas FTIR detection in complex scenarios.

关键词： Fourier transform infrared spectroscopy(FTIR) genetic programming(GP) trend term removal

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A Note on Irregularity of Two Dimensional Simple Hyperbolic Singularities

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Acta Mathematica Sinica,English Series 1994年第4期10卷 396-400页

作者： chen hao (1) 1. Computing Center Academia Sinica 100080 Beijing China

Deformation theory is an important aspect of the study about isolated singularities. The invariant called irregularity is very useful in the study on the deformation of isolated singu- *** this note we give an optimal upper bound for a class of surface singularities by the computation of *** a sufficient condition is given for the positivity of irreg- ularity of some simple hyperbolic surface *** a class of surface singularities with non-rigid deformation is constructed.

关键词： HO A Note on Irregularity of Two Dimensional Simple Hyperbolic Singularities Ho

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Effects of Cd(Ⅱ) and Cu(Ⅱ) on microbial characteristics in 2-chlorophenol-degradation anaerobic bioreactors

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Journal of Environmental Sciences 2008年第6期20卷 745-752页

作者： HUANG Aiqun chen hao chen Ling DAI Yalei Zhao Jianfu State Key Laboratory of Pollution Control and Resource Reuse College of Environmental Science and Engineering Tongji University Shanghai 200092 China Department of Immunology School of Basic Medical Science Tongji University Shanghai 200092 China

The effects of Cd^2＋ and Cu^2＋ at 300 mg/L on anaerobic microbial communities that degrade 2-cholorophenol （2-CP） were examined. Based on the polymerase chain reaction （PCR） of 16S rDNA, bacterial community diversity and archaeal community structure were analyzed with denaturing gradient gel electrophoresis （DGGE） and cloning, respectively. Degradation capabilities of the anaerobic microbial community were drastically abated and the degradation efficiency of 2-CP was reduced to 60% after shock by Cu^2＋ and Cd^2＋, respectively. The bacterial community structure was disturbed and the biodiversity was reduced after shock by Cu^2＋ and Cd^2＋ for 3 d. Some new metal-resistant microbes which could cope with the new condition appeared. The sequence analysis showed that there existed common Archaea species in control sludge and systems when treated with Cu^2＋ and Cd^2＋, such as Methanothrix soehngenii, Methanosaeta concilii, uncultured euryarchaeote, and so on. Both the abundance and diversity of archaeal species were altered with addition of Cd^2＋ and Cu^2＋ at high concentration. Although the abundance of the predominant archaeal species decreased with Cd^2＋ and Cu^2＋ addition for 3 d, they recovered to some extent after 10 d. The diversity of archaeal species was remarkably reduced after recovery for 10 d and the shift in archaeal composition seemed to be irreversible. The 2-CP-degradation anaerobic system was more sensitive to Cu^2＋ than Cd^2＋.

关键词： 2-cholorophenol (2-CP) Cd^2+ Cu^2+ microbial community diversity Bacteria Archaea DGGE cloning

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Synthesis and electrochemical performances of LiCoO_2 recycled from the incisors bound of Li-ion batteries

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Rare Metals 2009年第4期28卷 328-332页

作者： LI Jinhui ZHONG Shengwen XIONG Daoling chen hao School of Materials and Chemical Engineering Jiangxi University of Science and Technology Ganzhou 341009 China

A new LiCoO2 recovery technology for Li-ion batteries was studied in this paper. LiCoO2 was peeled from the Al foil with dimethyl acetamide （DMAC）, and then polyvinylidene fluoride （PVDF） and carbon powders in the active material were eliminated by high temperature calcining. Subsequently, Li2CO3, LiOH-H20 and LiAc-2H2O were added into the recycled powders to adjust the Li/Co molar ratio to 1.00. The new LiCoO2 was obtained by calcining the mixture at 850℃ for 12 h in air. The structure and morphology of the recycled powders and resulting samples were studied by XRD and SEM techniques, respectively. The layered structure of LiCoO2 synthesized by adding Li2CO3 is the best, and it is found to have the best characteristics as a cathode material in terms of charge-discharge capacity and cycling performance. The first discharge capacity is 160 mAh·g^-1 between 3.0-4.3 V. The discharge capacity after cycling for 50 times is still 145.2 mAh·g^-1.

关键词： LiCoO2 Li-ion batteries discharge performance cycling performance

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Compression method based on training dataset of SVM

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Journal of Systems Engineering and Electronics 2008年第1期19卷 198-201页

作者： Ban Xiaojuan Shen Qilong chen hao Tu Xuyan School of Information Engineering University of Science & Technology Beijing Beijing 100083 P. R. China Beijing Institute of Radio Metrology & Measurements Beijing 100854 P. R. China

The method to compress the training dataset of Support Vector Machine （SVM） based on the character of the Support Vector Machine is proposed. First, the distance between the unit in two training datasets, and then the samples that keep away from hyper-plane are discarded in order to compress the training dataset. The time spent in training SVM with the training dataset compressed by the method is shortened obviously. The result of the experiment shows that the algorithm is effective.

关键词： statistical learning theory support vector machine compression method classification

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Vulnerable Public Keys in NTRU Cryptosystem

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Chinese Annals of Mathematics,Series B 2020年第5期41卷 657-664页

作者： Liqing XU hao chen Chao LI Longjiang QU The College of Information Science and Technology/College of Cyber Security Jinan UniversityGuangzhou 510632China The College of Liberal Arts and Science National University of Defence TechnologyChangsha 410073China

In this paper the authors give an efficient bounded distance decoding(BDD for short)algorithm for NTRU lattices under some conditions about the modulus number q and the public key *** then use this algorithm to give plain-text recovery attack to NTRUEncrypt and forgery attack on *** particular the authors figure out a weak domain of public keys such that the recent transcript secure version of NTRU signature scheme NTRUMLS with public keys in this domain can be forged.

关键词： Lattice CVP NTRU Lattice

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