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Effect of electric field,stress and environment on delayed fracture of a PZT-5.ferroelectric ceramic

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Science china(Physics,Mechanics & Astronomy) 2005年第1期48卷 89-100页

作者： WANG Yi, SU Yanjing, CHU Wuyang & QIAO Lijie department of Material Physics, university of Science and Technology beijing, beijing 100083, china School of Mechanic and Electric Control Engineering, beijing Jiaotong university, beijing 100044, china 1. department of Material Physics University of Science and Technology Beijing 100083 Beijing China 2. School of Mechanic and Electric Control Engineering Beijing Jiaotong University 100044 Beijing China

The combined effect of electric and mechanical loading on fracture of a PZT-5.ferroelectric ceramic in silicone oil has been investigated using a single edge notched specimen. The results show that the fracture toughness and the threshold stress intensity factor of delayed fracture in silicone oil, i.e. stress corrosion cracking, decrease linearly with the increasing applied electric field, either positive or negative. For the PZT-5.ferroelectric ceramics, delayed fracture in silicone oil under sustained positive or negative field can occur, and the threshold field for delayed fracture under sustained positive or negative field decreases linearly with applied stress intensity factor. The combined effect of electric and mechanical loading on delayed fracture in silicone oil includes fieldenhancing delayed fracture under sustained load and stress-enhancing delayed fracture in silicone oil under sustained field.

关键词： PZT-5 ferroelectric ceramics, fracture toughness, delayed fracture under sustained load, delayedfracture under sustained electric field.

A Scheme of the Hierarchy for Sequence Stratigraphy

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Journal of Earth Science 1996年第1期15卷 1-12页

作者： Wang Hongzhen Shi Xiaoying (department of geology and Mineral Resources, china university of Geosciences, beijing 100083)

Depositional sequences may be distinguished into six ranks of units as giga-, mega-, meso-, ortho-, sub- and micro-sequence, and are interpreted to be formed during the eustatic cycles with time-intervals of 5.0-6000 Ma, 60-120 Ma, 30-40 Ma, 2-5.Ma, 0.1-0.4 Ma and 0.02-0.04 Ma respectively. All of them are thought to be essentially related to cosmological cycles, except the megasequence which may be caused by the long-term geothermal cycles on cratons. We deem that the depositional sequences, though often influenced variably by local tectonics and other factors, are primarily global and periodic in nature. We also hold that as one of the planets within the Galaxy, the earth must have been affected in various ways by other asteroids, and that the depositional sequences are merely the responses of the hydrosphere to the cosmological cycles in sedimentation.

关键词： hierarchy sequence stratigraphy,eustatic cycle cosmological cycle.

Crystallization Kinetics of NiTi Films with Different Ni Contents

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Journal of Materials Science & Technology 2001年第4期17卷 421-424页

作者： Xunyong JIANG, Huibin XU and Shengkai GONG department of Materials Science and Engineering, beijing university of Aeronautics and Astronautics, beijing 100083, china beijing Univ Aeronaut & Astronaut Dept Mat Sci & Engn Beijing 100083 Peoples R China

Three kinds of NiTi films with different Ni contents were prepared by DC magnetron sputtering. The crystallization kinetics of amorphous films was determined by using non-isothermal single- scan techniques. The results show that the activation energy of crystallization of Ni-rich NiTi film(Ni 5..10 at. pct, Ti 48.90 at. pct) is 715.kJ/mol; while that of Ti-rich films are similar: one is 445.kJ/mol (Ni 46.74 at. pct. Ti 5..26 at. pct), the other is 418 kJ/mol (Ni 43.21 at. pct, Ti 5..7g at. pct), which i5.lower than Ni-rich film. The Avrami parameter n of different films are 0.92 and 0.74 for Ni-rich film and Ti-rich films, respectively. The difference of kinetic parameters for NiTi films with various Ni contents implies that the crystallization behaviors of these films are distinct, which is confirmed by the calculated isothermal kinetics at different temperatures. The thorough research on this phenomenon is in progress.

关键词： NiTi Crystallization Kinetics of NiTi Films with Different Ni Contents

fMRI time series analysis based on stationary wavelet and spectrum analysis

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Progress in Natural Science:Materials International 2006年第11期16卷 1171-1176页

作者： ZHI Lianhe~ 1,2,3 , ZHAO Xia~4, SHAN Baoci~1**, PENG Silong~5. YAN Qiang~1, YUAN Xiuli~1 and TANG Xiaowei~ 1,6 (1. Key Laboratory of Nuclear Analysis Techniques, Institute of High Energy Physics, Chinese Academy of Sciences, beijing 100049, china 2. Graduate School of Chinese Academy of Sciences, beijing 100049, china 3. department of Physics, Zhoukou Normal {5., Zhoukou 466100, china 4. Research Imaging Center, {5. of Texas Health Science Center, San Antonio, Texas 78229, USA 5. National ASIC Design and Engineering Center, Institute of Automation, Chinese Academy of Sciences, beijing 100049, china 6. department of Physics, Zhejiang {5., Hangzhou 310027, china) [a]Key Laboratory of Nuclear Analysis Techniques Institute of High Energy Physics Chinese Academy of Sciences Beijing China [b]Graduate School of Chinese Academy of Sciences Beijing China [c]department of Physics Zhoukou Normal University Zhoukou China [d]Research Imaging Center University of Texas Health Science Center San Antonio Texas USA [e]National ASIC Design and Engineering Center Institute of Automation Chinese Academy of Sciences Beijing China [f]department of Physics Zhejiang University Hangzhou China

The low signal to noise ratio (SNR) of functional MRI (fMRI) prefers more sensitive data analysis methods. Based on stationary wavelet transform and spectrum analysis, a new method with high detective sensitivity was developed for analyzing fMRI time series, which does not require any prior assumption of the characteristics of noises. In the proposed method, every component of fMRI time series in the different time-frequency scales of stationary wavelet transform was discerned by the spectrum analysis, then the components from noises were removed using the stationary wavelet transform, finally the components of real brain activation were detected by cross-correlation analysis. The results obtained from both simulated and in vivo visual experiments illustrated that the proposed method has much higher sensitivity than the traditional cross-correlation method.

关键词： fMRI stationary wavelet transform spectrum analysis data analysis.

Synthesis by Solution Polymerization of Polybehenyl Acrylate as Pour Point Depressant for Crude Oil

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china petroleum Processing & Petrochemical Technology 2004年第4期6卷 37-40页

作者： Song Zhaozheng1 Ge Jijiang2(1 State Key Laboratory of Heavy Oil for Processing, university of petroleum, beijing 102249 2 petroleum Engineering department, university of petroleum,Dongying Shandong, 25.061) Stt. Key Lab. of Heavy Oil for Proc. University of Petroleum Beijing 102249 China petroleum Engineering department University of Petroleum Dongying Shandong 257061 China

Behenyl acrylate is a kind of highly efficient pour point depressants. In order to promote theapplication of the pour pint depressant in transportation of crude oils, polybehenyl acrylate was synthesizedby solution polymerization. These conclusions can be drawn from the experimental results that the sequenceof chain transfer constants of four solvents is arranged in the following decreasing order: carbon tetrachloride(6.010-5.>chloroform (2.810-5.>methylbenzene (2.5.0-5.>tetrachloroethane (1.610-5.. The average molecu-lar weight of polybehenyl acrylate mainly depends on the chain transfer constant of the solvents. However, ifthe monomer conversion was higher than 35., an abnormal phenomenon occurred, resulting in higher aver-age molecular weight of polybehenyl acrylate obtained in methylbenzene solution compared to that obtainedin tetrachloroethane solution. It was attributed to the influence of gelation on the average molecular weight ofpolybehenyl acrylate, which was stronger than the impact of chain transfer in methylbenzene.

关键词： polybehenyl acrylate solution polymerization chain transfer

Compactness in fuzzy logic

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Chinese Science Bulletin 1998年第14期43卷 1166-1171页

作者： YING Mingsheng department of Computer Science and Technology, Tsinghua university, beijing 100084, china department of Computer Science and Technology Tsinghua University Beijing China

Compactness in Pavelka’s fuzzy logic for some compact lattices of truth values is shown, and the concept of gradual compactness is introduced to establish some corresponding results in a more general setting.

关键词： fuzzy logic compactness gradual compactness.

SUPERSATURATED DESIGN WITH MORE THAN TWO LEVELS

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Chinese Annals of Mathematics,Series B 2001年第2期22卷 183-194页

作者： LU XUAN SUN YIZHOU department of Mathematical Science, Tsinghua university, beijing 100084, china. department of Mathematical Science Tsinghua Univeristy Beijing 100084 China

Supersaturated designs are useful in screening experiments. This paper discusses the topic of multi-level supersaturated design. Two quantities, E(d2) and Df, are proposed to evaluate the optimality of supersaturated designs. A lower bound of E(d2) is obtained with a necessary condition for achieving it. Some E(d2)-optimal supersaturated designs of 3, 4, and 5.levels are given.

关键词： D-efficiency Screening experiment Fractional factorial design Orthogonality

Some Results on Entire Functions of Finite Lower Order

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Acta Mathematica Sinica,English Series 1994年第2期10卷 168-178页

作者： Wu Shengjian department of Mathematics Peking university beijing, 100871 china 1. department of Mathematics Peking University 100871 Beijing China

Let f（z） be an entire function of order λ and of finite lower order μ. If the zeros of f（z） accumulate in the vicinity of a finite number of rays, then （a） λ is finite; （b） for every arbitrary number k1>1, there exists k2>1 such that T（k1r, f）≤k2T（r, f） for all r≥r0. Applying the above results, we prove that if f（z） is extremal for Yang’s inequality p=g/2, then （c） every deficient value of f（z） is also its asymptotic value; （d） every asymptotic value of f（z） is also its deficient value; （e） λ=μ; （f） ∑a≠∞δ5.a, f）≤1-k（μ）.

关键词： Some Results on Entire Functions of Finite Lower Order

Formulae of type Ankeny-Artin-Chowla for class numbers of general cyclic sextic fields

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Chinese Science Bulletin 1998年第10期43卷 824-826页

作者： LIU Tong department of Applied Mathematics, Tsinghua university, beijing 100084, china department of Applied Mathematics Tsinghua University Beijing China

Let K 6 be a real cyclic sextic number fields, and K 2, K 3 be its quadratic and cubic subfields. Let h(L) denote the ideal class number of field L. Seven congruences for h -=h(K 6)/h(K 2)h(K 3) are obtained. In particular, when conductor f\-6 of K 6 is prime p, then Ch -≡B p-16B 5.p-1)6 (mod p), where C is an explicitly given constant, and B n is the Bernoulli number. These results for real cyclic sextic fields are an extension of results for quadratic and cyclic quartic fields obtained by Ankeny_Artin_Chowla, Kiselev, Carlitz, Lu Hongwen, Zhang Xianke from 1948 to 1988.

关键词： real cyclic sextic number fields class number fundamental relative unit.