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MEASUREMENT OF NUMBER AVERAGE MOLECULAR WEIGHT OF STYRENE OLIGOMER BY ^(13)C-NMR METHOD

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Chinese Journal of Polymer science 1999年第2期17卷 135-140页

作者： Song Wang Xiao-hu Yan Rong-shi Cheng department of Polymer science and {2., nanjing university, nanjing 2.0093, china department of Polymer science and {2. Nanjing University Nanjing 210093 China

^(13)C-NMR ~1H-decoupled spectra of styrene polymers were assigned by comparison with modelcompounds, then used in measurements of number average molecular weights. The higher limit of an exactdetermination of the end group signal is less than a molecular weight of 10~4. For polymer samples withM_n<10~3, the results obtained from ^(13)C-NMR spectra of saturated carbon region are in excellent agreementwith the values determined by ~1H-NMR, SEC, and VPO methods, while the results from ^(13)C-NMR spectra ofphenyl C-1 carbon region are somewhat higher than the values determined by other methods.

关键词： Molecular weight measurement Styrene oligomer ^(13)C-NMR spectra

Discrete Element Modeling of Asphalt Concrete Cracking Using a User-def ined Three-dimensional Micromechanical Approach

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Journal of Wuhan university of Technology(Materials science) 2011年第6期26卷 1215-1221页

作者：陈俊 College of Civil and Transportation engineering Hohai University

We established a user-defined micromechanical model using discrete element method （DEM） to investigate the cracking behavior of asphalt concrete （AC）. Using the ＂Fish＂ language provided in the particle flow code in 3-Demensions （PFC3D）, the air voids and mastics in asphalt concrete were realistically built as two distinct phases. With the irregular shape of individual aggregate particles modeled using a clump of spheres of different sizes, the three-dimensional （3D） discrete element model was able to account for aggregate gradation and fraction. Laboratory uniaxial complex modulus test and indirect tensile strength test were performed to obtain input material parameters for the numerical simulation. A set of the indirect tensile test were simulated to study the cracking behavior of AC at two levels of temperature, i e, -10 ℃ and 15 ℃. The predicted results of the numerical simulation were compared with laboratory experimental measurements. Results show that the 3D DEM model is able to predict accurately the fracture pattern of different asphalt mixtures. Based on the DEM model, the effects of air void content and aggregate volumetric fraction on the cracking behavior of asphalt concrete were evaluated.

关键词： discrete element method asphalt concrete cracking behavior three-dimensional simulation micromechanics

Asymptotic SEP of MIMO beamforming in two-hop AF relaying systems

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science china(Information sciences) 2012年第2期55卷 377-383页

作者： FU YouHua1,HAN YuJie2.YANG LvXi2.ZHU WeiPing3 & LIU Chen1 1School of Electronic science and engineering,{2. university of Posts and Telecommunications,{2. 2.0003,china 2.chool of Information science and engineering,southeast university,{2. 2.0096,china 3department of Electrical and computer engineering,Concordia university,Montreal H3G 1M8,Canada 1. School of Electronic science and engineering Nanjing University of Posts and Telecommunications Nanjing 210003 China2. School of Information Science and Engineering Southeast University Nanjing 210096 China3. Department of Electrical and Computer Engineering Concordia University Montreal H3G 1M8 Canada

This paper derives an asymptotic average symbol error probability(SEP)expression for multiple-input multiple-output(MIMO)two-hop amplify-and-forward(AF)relay systems with optimal *** analysis at high signal-to-noise ratio(SNR)quantifies the diversity order and array gain,which are valid for any antenna numbers of the terminals and arbitrary channel fading *** is also proved that the system performance is dominated by the relatively degraded one of the two-hop *** results based on the simple expressions provide valuable insights into the performance and practical design considerations of MIMO AF networks.

关键词： MIMO relay networks optimal beamforming symbol error probability(SEP) diversity order

Genotoxicity　of　substituted　nitrobenzenes　and　the　quantitative　structure－activity　relationship

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Journal of Environmental sciences 1996年第1期8卷 103-109页

作者： Huang Qingguo Liu Yongbin Wang Liansheng Han Shuokui(department of Environmental science and {2.,nanjing university,nanjing 2.0093,china)Yang Jun(jiangsu Metallurgy Institute.nanjing 2.0007,china)

The genotoxicity of 2. substituted nitrobenzenes were evaluated by the chromosome aberrations test in in vitro human peripheral lymphocytes.18 of 2. compounds exhibit genotoxic *** structure-activity relationship model was established to correlate the genotoxicity of substituted nitrobenzenes with the characteristics of the substituents on benzene ring.

关键词： quantitative structure-activity relationship(QSAR) substituted nitrobenzenes genotoxicity.

Mining and Integrating Reliable Decision Rules for Imbalanced Cancer Gene Expression Data Sets

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Tsinghua science and Technology 2012年第6期17卷 666-673页

作者： Hualong Yu 1 , Jun Ni 2., Yuanyuan Dan 3 , Sen Xu 4 1. School of computer science and {2., jiangsu university of science and Technology, Zhenjiang 2.2.03, china 2. department of Radiology, Carver College of Medicine, The university of Iowa, Iowa City, IA 52.42. USA 3. School of Biology and Chemical {2., jiangsu university of science and Technology, Zhenjiang 2.2.03, china 4. School of Information {2., Yancheng Institute of Technology, Yancheng 2.4051, china School of computer science and {2. Jiangsu University of Science and Technology Zhenjiang 212003 China|c|

There have been many skewed cancer gene expression datasets in the post-genomic era. Extraction of differential expression genes or construction of decision rules using these skewed datasets by traditional algorithms will seriously underestimate the performance of the minority class, leading to inaccurate diagnosis in clinical trails. This paper presents a skewed gene selection algorithm that introduces a weighted metric into the gene selection procedure. The extracted genes are paired as decision rules to distinguish both classes, with these decision rules then integrated into an ensemble learning framework by majority voting to recognize test examples; thus avoiding tedious data normalization and classifier construction. The mining and integrating of a few reliable decision rules gave higher or at least comparable classification performance than many traditional class imbalance learning algorithms on four benchmark imbalanced cancer gene expression datasets.

关键词： cancer gene expression data class imbalance paired differential expression genes decision ruleensemble learning majority voting

TENSILE STRENGTH AND CREEP RESISTANCE OF Mg-9Al-1Zn BASED ALLOYS WITH CALCIUM ADDITION

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Acta Metallurgica Sinica(English Letters) 2001年第5期14卷 330-334页

作者： Y.S. Sun, W.M. Zhang and X.G. Mm department of Materials science and {2., southeast university, nanjing 2.0096, china Dept. of Mat. Sci. and Eng. Southeast Univ. Nanjing 210096 China

Small amount of calcium addition to the Mg-9Al-0.8Zn-0.2.n (AZ91) alloy resulted in obvious influence on mechanical properties. The yield strength of the alloys increased with the increase of Ca addition and the maximum strength was obtained from the alloy containing 0.15% of Ca. The creep resistance at the temperatures between 150-2.0°C was also significantly increased with Ca addition. The creep rate (at 2.0°C, 50 MPa) of the alloy with 0.15% Ca addition was one order of magnitude lower than that of the base alloy (AZ91). Microstructural observations revealed that the addition of calcium refined the microstructure and enhanced the thermal stability of the β precipitates, which accounted for the improvement of creep resistance at high temperatures.

关键词： Additives Aluminum alloys Calcium Creep Tensile strength

Wavelet estimation of the diffusion coefficient in time dependent diffusion models

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science china Mathematics 2007年第11期50卷 1597-1610页

作者： Ping CHEN~(1,2.) Jin-de WANG~1 1 department of Mathematics,nanjing {2.,nanjing 2.0093,china 2.School of science,nanjing {2. of science and Technology,nanjing 2.0094,china department of Mathematics Nanjing University Nanjing 210093 China School of science Nanjing University of Science Technology Nanjing 210094 China

The estimation problem for diffusion coefficients in diffusion processes has been studied in many papers,where the diffusion coefficient function is assumed to be a 1-dimensional bounded Lipschitzian function of the state or the time *** is no previous work for the nonparametric estimation of time-dependent diffusion models where the diffusion coefficient depends on both the state and the *** paper introduces and studies a wavelet estimation of the time-dependent diffusion coefficient under a more general assumption that the diffusion coefficient is a linear growth Lipschitz *** the properties of martingale,we translate the problems in diffusion into the nonparametric regression setting and give the Lr convergence rate.A strong consistency of the estimate is *** this result one can estimate the time-dependent diffusion coefficient using the same structure of the wavelet estimators under any equivalent probability *** example,in finance,the wavelet estimator is strongly consistent under the market probability measure as well as the risk neutral probability measure.

关键词： wavelet estimation time-dependent diffusion coefficient linear growth condition strong consistency

Thermal Insulation and Strength of Autoclaved Light Concrete

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Journal of Wuhan university of Technology(Materials science) 2011年第1期26卷 132-136页

作者：杨若冲吴智深 School of Transportation Southeast University Institute of Urban engineering science & Technology Southeast University

The primary objective of this study was to develop an autoclaved light concrete （ALC） material with ultra-thermal insulation property and to investigate the relationship between its physical characteristics and mechanical properties. Through tests of dry bulk density and compressive strength, relationship of physical characteristics and mechanical properties of samples were studied, resulting in a material with ultra-thermal insulation property. Scanning electron microscope （SEM） and energy-dispersive X-ray spectroscopy （EDX） were applied to analyze the micro-morphology and elemental composition of samples. To identify the product phases, X-ray diffraction （XRD） was engaged. The test results showed that compressive strength and thermal coefficient were reduced with the increasing of aluminum powder within the mixtures. As a result the optimal thermal coefficient and compressive strength of samples were improved to 0.061 W/（m·k） and 1.2.MPa, respectively. SEM, EDX and XRD analyses showed that calcium silicate hydrate and tobermorite crystal were main resultant phases.

关键词： autoclaved light concrete ultra-thermal insulation microscopic appearance and phase analysis tobermorite crystal

The low-mass X-ray binary-millisecond radio pulsar birthrate problem revisited

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science china(Physics,Mechanics & Astronomy) 2010年第S1期53卷 125-129页

作者： DAI HaiLang1,2.& LI XiangDong2.1 Faculty of science,jiangsu {2.,Zhenjiang 2.2.13,china 2.department of Astronomy,nanjing {2.,nanjing 2.0093,china 1. Faculty of science Jiangsu University Zhenjiang 212013 China 2. department of Astronomy Nanjing University Nanjing 210093 China

We investigate the birthrate problem for low-mass X-ray binaries(LMXBs) and millisecond radio pulsars(MRPs) in this *** consider intermediate-mass and low-mass X-ray binaries(I/LMXBs) to be the progenitors of MRPs,and calculate their evolutionary response to the cosmic star formation rate(SFR) both semi-analytically and *** a typical value(1 Gyr) of the LMXB lifetime,one may expect comparable birthrates of LMXBs and MRPs,but the calculated number of LMXBs is an order of magnitude higher than that observed in the ***,we suggest that the birthrate problem could be solved if most MRPs have evolved from faint to rather than bright *** former may have a population of-104 in the Galaxy.

关键词： close binaries general pulsars star formation X-ray stars