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Erosion corrosion of low-alloy wear-resistant steels in alkaline slurry

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Journal of Iron and Steel Research International 2017年第10期24卷 1065-1072页

作者： feng-ming Song Lin-xiu Du State Key Laboratory of Rolling Technology and Automation Northeastern UniversityShenyang 110004LiaoningChina

Erosion corrosion causes significant problems in various industrial environments through a synergistic effect which results in much greater weight loss than the sum of the weight losses in the individual *** erosion-corrosion behavior of three low-alloy steels was investigated in a simulated concrete slurry using the rotation *** key influencing factors and mechanism of material degradation were *** experimental results indicate that the weight loss increases with the linear velocity according to a nearly exponential relationship（W =KV^n）,where nis *** weight loss is mainly caused by erosion in the alkaline slurry,and steels with higher tensile strengths show higher erosion-corrosion *** formation of many platelets and ring cracks and their removal from the sample surface during erosion corrosion in the slurry are thought to constitute the mechanism responsible for this weight *** platelets and ring cracks are formed by solid particles striking the sample *** are initially produced and subsequently disappear as they grow and come in contact with each *** craters were observed on the surfaces of samples that exhibited higher weight *** surface of the material became work-hardened because of the effect of the particles striking and scratching,and a deformed layer was produced on the surface for steels of lower strengths,leading to deeper and more abundant gouges.

关键词： Erosion Corrosion Slurry Synergy Steel

INFLUENCE OF MOLECULAR STRUCTURES OF SECONDARY AMINE TERMINATED POLY(ESTER-AMINE)S ON THE CURING PERFORMANCE WITH EPOXY RESIN

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Chinese Journal of Polymer Science 2007年第6期25卷 545-553页

作者： Li-ming Tang Ji feng Yu Wang Advanced Materials Laboratory Department of Chemical Engineering Tsinghua University Beijing 100084 China

Five secondary amine terminated poly（ester-amine）s （defined as PEA） with controlled molecular structures were synthesized through reacting excessive piperazine with phthalicdiglycol diacrylate （PDDA） and 1,1,1-trimethylolpropane triacrylate （TMPTA） at a constant secondary amine/acrylate group ratio of 1.5/1 and at different PDDA/TMPTA molar ratios. Both IR and ^1H-NMR spectra indicated that all acrylate groups were consumed in the reaction, based on which the structural parameters were calculated from the ^1H-NMR spectra. With decreasing PDDA/TMPTA ratio, the content of secondary amine, degree of branching, molecular weight, Tg and Td increased accordingly. These polymers were further used as both crosslinkers and flexibilizers for a linear epoxy resin E51 to form cured films under ambient condition. The gel content, relative hardness and Tg of the resulting films increased as PEA molecules changed from linear to highly branching structures. Due to the flexibility of PEA molecules, all the films possessed excellent mechanical performance.

关键词： Poly(ester-amine) Molecular structure Epoxy resin Cured film.

Analytical Solution for an Ultracold Trapped Ion at the Node of the Standing Wave Laser Without Rotating Wave Approximation

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Communications in Theoretical Physics 2001年第11期36卷 597-600页

作者： FANG Xi-ming feng Mang Department of Physics Hunan Normal UniversityChangsha 410081China Laboratory of Magnetic Resonance and Atomic and Molecular PhysicsWuhan Institute of PhysicsAcademia SinicaWuhan 430071China

A method of solving an ultracold trapped ion at the node of the standing wave laser without rotating wave approximation is proposed and the analytical forms of the eigenfunctions and eigenenergies of the system are pr... 详细信息

关键词： ultracold trapped ion,analytical solution,rotating wave approximation

Recent advances in statistical methodologies in evaluating program for high-dimensional data

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Applied Mathematics(A Journal of Chinese Universities) 2022年第1期37卷 131-146页

作者： ZHAN ming-feng CAI Zong-wu FANG Ying LIN ming Wang Yanan Institute for Studies in Economics and Fujian Key Laboratory of Statistical Sciences Xiamen UniversityXiamen 361005China Department of Economics University of KansasLawrenceKS 66045USA Department of Statistics and Data Science Xiamen UniversityXiamen 361005China

The era of big data brings opportunities and challenges to developing new statistical methods and models to evaluate social programs or economic policies or interventions. This paper provides a comprehensive review on some recent advances in statistical methodologies and models to evaluate programs with high-dimensional data. In particular, four kinds of methods for making valid statistical inferences for treatment effects in high dimensions are addressed. The first one is the so-called doubly robust type estimation, which models the outcome regression and propensity score functions simultaneously. The second one is the covariate balance method to construct the treatment effect estimators. The third one is the sufficient dimension reduction approach for causal inferences. The last one is the machine learning procedure directly or indirectly to make statistical inferences to treatment effect. In such a way, some of these methods and models are closely related to the de-biased Lasso type methods for the regression model with high dimensions in the statistical literature. Finally, some future research topics are also discussed.

关键词： causal inference covariate balance de-biased Lasso dimension reduction doubly robust high dimensions machine learning treatment effect

On Holomorphic Sections in Teichmiiller Spaces

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Acta Mathematica Sinica,English Series 2009年第12期25卷 2023-2034页

作者： ming feng SUN Yu Liang SHEN Department of Mathematics Soochow University Suzhou 215006 P. R. China

It is proved that, for any elementary torsion free Fuchsian group F, the natural projection from the Teichmiiller curve V（F） to the Teichmiiller space T（F） has no holomorphic section.

关键词： Teichmuller space Bers fiber space Teichmiiller curve holomorphic section punctureforgetting mapping

Oxidation behavior of in-situ Al_2O_3/TiAl composites at 900°C in static air

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International Journal of Minerals,Metallurgy and Materials 2009年第3期16卷 339-344页

作者： Tao-tao Ai Fen Wang Xiao-ming feng Department of Materials Science and Engineering Shaanxi University of Technology Hanzhong 723003 China School of Materials Science and Engineering Shaanxi University of Science and Technology Xi＇an 710021 China

In-situ Al2O3/TiAl composites were successfully synthesized from the starting powders of Ti, Al, TiO2 and Nb2O5. The oxidation behavior of the composites at 900℃ in static air was investigated. The results indicate that the composite samples present a much lower oxidation mass gain. Under long-time intensive oxidation exposure, the formed oxide scale is multi-layer. The formation of the outer TiO2 layer is fine and dense, the internal Al2O3 scale has good adhesiveness with the outer TiO2 scale, and the TiO2＋Al2O3 mixed layer forming the protective oxide scale is favorable for the improvement of oxidation resistance. It is believed that the incorporation of Al2O3 particulates into the metal matrix decreases the coefficient of thermal expansion of the substrate, and forms a local three-dimensional network structure that can hold the oxide scale. The formation of the oxide scale with finer particle size, stronger adherence, less micro-defects and slower growth rate can contribute to the improvement of oxidation resistance. Nb element plays an important role in reducing the internal oxidation action of the materials, restraining the growth of TiO2 crystals and promoting the stable formation of the Al2O3-riched layer, which is beneficial to improve the oxidation properties.

关键词： intermetallic matrix composites alumina oxidation resistance scale spallation high temperature

Mechanical and magnetic hysteresis as indicators of the origin and inception of fatigue damage in steel

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2010年第8期11卷 580-586页

作者： Sheng BAO Wei-liang JIN ming-feng HUANG Institute of Structural Engineering Zhejiang University Hangzhou 310058 China

N2 and N3 are known as the transition points of the three principal stages of fatigue: initial accommodation, accretion of damage and terminal fatigue. Many experiments show that the ratios of N2/Nf and N3/Nf tend to be stable even though the specific N2 and N3 values may fluctuate widely. The primary goal of this research is to study the piezomagnetic field surrounding AISI 1018 steel specimen under repeated loads and to find the ratio values of N2/Nf and N3/Nf by analyzing 11 sets of low-cycle fatigue data. An MTS-810 testing system with a peak capacity of 222 kN was used to obtain the data which consisted of stress, strain, and piezomagnetic field. A computer program was constructed to track the evolution of the piezomagnetic field and re- gression analysis was carried out to determine N2 and N3 values. It was observed that there exists a consistent relationship between N2 and Nf. The apparent invariance of the ratio N2/Nf implies that N2 may be identified as an index of performance in the early loading response of a specimen that forecasts its fatigue life, Nf. It has been demonstrated that measurements of the magnetic and mechanical hysteresis can yield significant insights into the various stages of the development of a fatigue critical microstructure which culminates in complete rupture of the material.

关键词： Piezomagnetic effects. Fatigue damage. Mechanical hvsteresis. Magnetic hysteresis

Analysis of seasonal signals and long-term trends in the height time series of IGS sites in China

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Science China Earth Sciences 2016年第6期59卷 1283-1291页

作者： ming feng YANG YuanXi ZENG AnMin JING YiFan Institute of Geospatial Information Information Engineering University National Key Laboratory of Geo-information Engineering Xi'an Institute of Surveying and Mapping Institute of Navigation and Aerospace Engineering Information Engineering University

The seasonal signal and long-term trend in the height time series of 10 IGS sites in China are investigated in this paper. The offset detection and outlier removal as well as the removal of common mode error are performed on the raw GPS time-series data developed by the Scripps Orbit and Permanent Array Center(SOPAC). The seasonal-trend decomposition procedure based on LOESS(STL) is utilized to extract precise seasonal signals, followed by an estimation of the long-term trend with the application of maximum likelihood estimation(MLE) to the seasonally adjusted time series. The Up-compo- nents of all sites are featured by obvious seasonal variations, with significant phase and amplitude modulation on some sites. After Kendall's tau test, a significant trend(99% confidence interval) for all sites is achieved. Furthermore, the trends at sites TCMS and TNML have significant changes at epochs 2009.5384 and 2009.1493(95% confidence interval), respectively, using the Breaks For Additive Seasonal and Trend test. Finally, the velocities and their uncertainties for all sites are estimated using MLE with the white noise plus flicker noise model. And the results are analyzed and compared with those announced by SOPAC. The results obtained in this paper have a higher precision than the SOPAC results.

关键词： GPS Height time series Seasonal signal Long-term trend STL filter Colored noise

2D/2D heterojunction interface:Engineering of 1T/2H MoS_(2) coupled with Ti_(3)C_(2)Tx heterostructured electrocatalysts for pH-universal hydrogen evolution

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Journal of Materials Science & Technology 2024年第12期179卷 86-97页

作者： Jian Yiing Loh feng ming Yap Wee-Jun Ong School of Energy and Chemical Engineering Xiamen University MalaysiaSepangSelangor Darul Ehsan 43900Malaysia Center of Excellence for NaNo Energy&Catalysis Technology(CONNECT) Xiamen University MalaysiaSepangSelangor Darul Ehsan 43900Malaysia State Key Laboratory of Physical Chemistry of Solid Surfaces College of Chemistry and Chemical EngineeringXiamen UniversityXiamen 361005China Gulei Innovation Institute Xiamen UniversityZhangzhou 363200China Shenzhen Research Institute of Xiamen University Shenzhen 518057China

Two-dimensional(2D)materials have come to light due to their unique thickness that owns abundant exposed edges with enhanced electrocatalytic properties.2D molybdenum disulfide(MoS_(2))nanosheet has aroused considerable attention due to its tunable surface chemistry and high electrochemical sur-face ***,several shortcomings associated with MoS_(2),such as its naturally existing semi-conducting 2H phase,which has limited active sites due to the inert basal plane,restrict its application in water *** into account the benefits of the 1T/2H phase of MoS_(2),as well as the importance of engineering 2D/2D heterojunction interface for boosted electrocatalysis,metallic Ti_(3)C_(2)Tx was integrated with 1T/2H MoS_(2) to develop 2D/2D 1T/2H MoS_(2)/Ti_(3)C_(2)Tx heterostructured ***,with only 25%of the intercalating agent,1T/2H MoS_(2) with the highest 1T phase content of~82%was successfully *** was further incorporated with 1 wt%of Ti_(3)C_(2)Tx through a com-bination of ultrasonication and mechanical stirring *** 1T/2H MoS_(2)(25D)/Ti_(3)C_(2)Tx-1(MTC-1)manifested outstanding electrocatalytic performance with an overpotential and Tafel slope of 280 mV(83.80 mV dec^(-1))and 300 mV(117.2 mV dec^(-1)),for catalyzing acidic and alkaline medium HER,***,the as-prepared catalysts also illustrated long-term stability for more than 40 *** coupling method for the 2D nanosheets is crucial to suppress the oxidation of Ti_(3)C_(2)Tx and the restack-ing issue of 2D *** superior HER activity is ascribed to the synergistic effect between the heterostructure,enhancing the electronic structure and charge separation *** intrinsic prop-erty of the catalyst further confirms by turnover frequency(TOF)*** such,this research paves the way for designing high-efficiency 2D electrocatalysts and sheds light on the further advancement of tunable 2D electrocatalysts for robust wa

关键词： 2D/2D electrocatalysts Phase engineering pH universal Molybdenum disulfide Ti_(3)C_(2)Tx