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Journal of Environmental Sciences 2007年第11期19卷 1311-1317页

作者： ZHANG Zhong-chun QIU bao-sheng College of Life Sciences Huazhong Normal University Wuhan 430079 China

Sedum alfredii Hance, a newly discovered hyperaccumulator, could serve as a good material for phytoremediation of Cd polluted sites. Malondialdehyde （MDA）, reactive oxygen species （ROS） and antioxidases （catalase （CAT）; superoxide dismutase （SOD）; peroxidase （POD）） in the leaf were determined when S. alfredii was treated for 15 d with various CdC12 concentrations ranging from 0 to 800 μmol/L. The results showed that the production rate of 2＇,7＇-dichlorofluorescein （DCF）, which is an indicator of ROS level, reached up to the maximum at 400 μmol/L CdCl2 and then declined with the increase of CdCl2 concentration, while MDA accumulation tended to increase. CAT activity was significantly inhibited at all tested CdCl2 concentrations and SOD activity was sharply suppressed at 800 μmol/L CdCl2. However, the enhancement of POD activity was observed when CdCl2 concentration was higher than 400 μmol/L. In addition, its activity increased when treated with 600 μmol/L CdCl2 for more than 5 d. When sodium benzoate, a free radical scavenger, was added, S. alfredii was a little more sensitive to Cd toxicity than that exposed to Cd alone, and the Cd accumulation tended to decline with the increase of sodium benzoate concentration. It came to the conclusions that POD played an important role during Cd hyperaccumulation, and the accumulation of ROS induced by Cd treatment might be involved in Cd hyperaccumulation.

关键词： cadmium hyperaccumulation reactive oxygen species Sedum alfredii

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

Two-order Hermite vector-interpolating subdivision schemes

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2006年第9期7卷 1566-1571页

作者： FAN Min KANG bao-sheng ZHAO Hua Beijing Institute of Tracking and Telecommunication Technology Beijing 100094 China Department of Computer Sctence Northwest University Xi＇an 710069 China

A family of two-order Hermite vector-interpolating subdivision schemes is proposed and its convergence and con- tinuity are analyzed. The iterative level can be estimated for given error. The sufficient conditions of C2 continuity are proved. Geometric features of subdivision curves, such as line segments, cusps and inflection points, are obtained by appending some conditions to initial vectorial Hermite sequence. An algorithm is presented for generating geometric features. For an initial se- quence of two-order Hermite elements from unit circle, the numerical error of the 4th subdivided level is O(10?4).

关键词： Two-order vectorial Hermite element Hermite-interpolating subdivision schemes Geometric features

Characterization of Stress Concentration by Tangential Component Hp(x) of Metal Magnetic Memory Signals

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Journal of Wuhan University of Technology(Materials Science) 2018年第6期33卷 1486-1490页

作者： FU Meili bao sheng Institute of Structural Engineering Zhejiang University Seazen Holding Co. Ltd

The correlation between the stress concentration and the spontaneous magnetic signals of metal magnetic memory(MMM) was investigated via tensile tests. Sheet specimens of the Q235 steel were machined into standard bars with rectangular holes to obtain various stress concentration factors. The tangential component Hp(x) of MMM signals and its related magnetic characteristic parameters throughout the loading process were presented and analyzed. It is found that the tangential component Hp(x) is sensitive to the abnormal magnetic changes caused by the local stress concentration in the defect area. The minimum magnetic field is positively correlated to the magnitude of the load and the distance from the notch. The tangential magnetic stress concentration factor presents good numerical stability during the entire loading process, and can be used to evaluate the stress concentration factor. The results obtained will be a complement to the MMM technique.

关键词： metal magnetic memory tangential component stress concentration tensile test

Microstructural evolution and mechanical properties of a new Ni-based heat-resistant alloy during aging at 750℃

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Journal of Iron and Steel Research International 2017年第5期24卷 513-519页

作者： Zhong-liang Tian Sen-bao Jiang Zheng-zong Chen Han-sheng bao Zheng-dong Liu Institute for Special Steels Central Iron and Steel Research Institute College of Material Science & Engineering Taiyuan Science & Technology University

Microstructural evolution and mechanical properties of a new candidate Ni-based heat-resistant alloy for advanced ultra-supercritical （A-USC） steam turbine rotors were investigated during aging at 750℃ up to 10000 h. The evolutions of γ＇ particles inside austenitic grain and M_23 C_6 carbides along grain boundaries were characterized according to their morphologies, distributions, and growth kinetics. Mean radius of the γ＇ spherical particles grew from 20.3 to 90.0 nm after aging for 10000 h, and;the corresponding coarse- ning behavior was conformed to the law of Lifschitz-Slyosovd-Wagner （LSW）. The weight fraction of γ＇ particles slightly increased from 10.0 to 12.0 wt. % after aging of long duration at 750 ℃.The Cr-rich M_23C_6 carbides discontinuously precipitated along grain boundaries, while other detrimental phases were not formed during the aging treatment, and hence the strength of grain boundary was enhanced by these discontinuously distributed carbides. The critical size of γ＇ had a direct influence on the maximum hardness of this alloy. Moreover, this alloy presented a good impact toughness for the safety after long time aging at high temperature.

关键词： Aging Precipitation Microstruetural evolution Mechanical property Heat-resistant alloy

Learning from regularized regression algorithms with p-order Markov chain sampling

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Applied Mathematics(A Journal of Chinese Universities) 2011年第3期26卷 295-306页

作者： ZHANG Jing WANG Jian-li sheng bao-huai Department of Mathematics Shaoxing College of Arts and Sciences Shaoxing 312000 China.

Evaluation for the performance of learning algorithm has been the main thread of theoretical research of machine learning. The performance of the regularized regression algorithm based on independent and identically distributed（i.i.d.） samples has been researched by a large number of references. In the present paper we provide the convergence rates for the performance of regularized regression based on the inputs of p-order Markov chains.

关键词： p-order Markov chain uniformly ergodic learning rate.

Forecasting of China's natural gas production and its policy implications

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Petroleum Science 2016年第3期13卷 592-603页

作者： Shi-Qun Li bao-sheng Zhang Xu Tang School of Business Administration China University of Petroleum

With the vigorous promotion of energy conservation and implementation of clean energy strategies,China＇s natural gas industry has entered a rapid development phase,and natural gas is playing an increasingly important role in China＇s energy *** paper uses a Generalized Weng model to forecast Chinese regional natural gas production,where accuracy and reasonableness compared with other predictions are enhanced by taking remaining estimated recoverable resources as a *** forecast shows that China＇s natural gas production will maintain a rapid growth with peak gas of 323 billion cubic meters a year coming in 2036;in 2020,natural gas production will surpass that of oil to become a more important source of *** gas will play an important role in optimizing China＇s energy consumption structure and will be a strategic replacement of *** will require that exploration and development of conventional natural gas is highly valued and its industrial development to be reasonably *** well,full use should be made of domestic and international *** should also be taken in the exploration and development of unconventional and deepwater gas,which shall form a complement to the development of China＇s conventional natural gas industry.

关键词： Natural gas Production forecast Generalized Weng model Energy structure Policy implication

Effect of tempering temperature on strain hardening exponent and flow stress curve of 1000MPa grade steel for construction machinery

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Journal of Iron and Steel Research International 2017年第9期24卷 950-956页

作者： Yang Yun Qing-wu Cai bao-sheng Xie Shuang Li National Engineering Research Center of Advanced Rolling University of Science and Technology BeijingBeijing 100083China Collaborative Innovation Center of Steel Technology University of Science and Technology BeijingBeijing 100083China

To study the effect of tempering temperature on strain hardening exponent and flow stress curve,one kind of 1000 MPa grade low carbon bainitic steel for construction machinery was designed,and the standard uniaxial tensile tests were conducted at room temperature.A new flow stress model,which could predict the flow behavior of the tested steels at different tempering temperatures more efficiently,was *** relationship between mobile dislocation density and strain hardening exponent was discussed based on the dislocation-stress *** equation and an inverse proportional function were adopted to describe the mobile dislocation,and two mathematical models were established to describe the relationship between tempering temperature and strain hardening *** regression analysis was applied to the Arrhenius type model,hence,the activation energy was determined to be 37.6kJ/***,the square of correlation coefficient was 0.985,which indicated a high reliability between the fitted curve and experimental *** comparison with the Arrhenius type curve,the general trend of the inverse proportional fitting curve was coincided with the experimental data points except of some fitting ***,the Arrhenius type model can be adopted to predict the strain hardening exponent at different tempering temperatures.

关键词： Tempering temperature Flow stress curve Strain hardening exponent Microscopic mechanism Mathematical model

Two-parameter characterization of low cycle,hysteretic fatigue data

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2010年第6期11卷 449-454页

作者： sheng bao Wei—liang JIN Sidney A. GURALNICK Thomas ERBER Institute of Structural Engineering Zhejiang University Hangzhou 310058 China Department of Civil Engineering Illino& Institute of Technology Chicago IL 60616 USA Department of Physics lllino& Institute of Technology Chicago IL 60616 USA Department of Applied Mathematics Illinois Institute of Technology Chicago IL 60616 USA

The aim of this research is to characterize the development of fatigue damage by means of stress-strain *** were conducted on 14 specimens made of cold-finished unannealed AISI 1018 *** demonstrate that the mechanical hysteresis loop areas,when plotted as a function of the number of loading cycles,show significant variations and demonstrate the three principal stages concerning the progress of the fatigue failure—initial accommodation,accretion of damage and terminal *** three stages of fatigue are marked by the transitions at cycles N2 and *** results show that although fatigue life Nf ranges from 2644 cycles to 108 992 cycles,the ratios of N2/Nf and N3/Nf tend to be stable:N2/Nf=10.7%,N3/Nf=91.3%.

关键词： Hysteresis loss Fatigue life Fatigue damage

Effect of W on formation and properties of precipitates in Ni-based superalloys

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Journal of Iron and Steel Research International 2021年第7期28卷 910-919页

作者： Zhi-hua Gong Yuan-yuan Ma Han-sheng bao Gang Yang Inner Mongolia University of Science and Technology Baotou 014010Inner MongoliaChina Institute for Special Steels Central Iron and Steel Research InstituteBeijing 100081China

The formation and properties of precipitates in wrought Ni-based superalloys with different W contents during long-term exposure to high temperatures were *** scanning electron microscope,transmission electron microscope,and chemical phase analysis were used to investigate the formation and properties of *** is found that with increasing W content,the quantity and thermal stability of MC carbide in Ni-based superalloys increased,while the quantity of M_(23)C_(6)carbides *** the results show,W has a higher partition coefficient in γ'-and γ-matrix,and the addition of W promotes the precipitation of γ'phase.W content has no significant effect on the morphology,size,crystal structure,and coarsening rate of γ'*** influence of W content on high-temperature tensile and creep properties of the alloys was *** results showed that W content has no obvious influence on the high-temperature yield strength,but the elongation and area reduction decreased significantly when the addition of W was more than 4 wt.%.Because of the similar volume fractions of γ'phase,the creep fracture strengths in the tested alloys with lower W concentrations were not significantly different after long-term exposure at 700℃.

关键词： Ni-based superalloy W content Waspaloy alloy Heat resistance MC carbide