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Dynamic Mechanical Behaviour of Ultra-high Performance Fiber Reinforced Concretes

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Journal of Wuhan university of technology(Materials science) 2008年第6期23卷 938-945页

作者：赖建中 Department of Materials science & Engineering Nanjing University of Science & Technology

Ultra-high performance fiber reinforced concretes （UHPFRC） were prepared by replacing 60% of cement with ultra-fine industrial waste powder. The dynamic mechanical behaviour of UHPFRC with different fiber volume fraction was researched on repeated compressive impact in four kinds of impact modes through split Hopkinson pressure bar （SHPB）. The experimental results show that the peak stress and elastic modulus decrease and the strain rate and peak strain increase gradually with the increasing of impact times. The initial material damage increases and the peak stress of the specimen decreases from the second impact with the increasing of the initial incident wave. Standard strength on repeated impact is defined to compare the ability of resistance against repeated impact among different materials. The rate of reduction of standard strength is decreased by fiber reinforcement under repeated impact. The material damage is reduced and the ability of repeated impact resistance of UHPFRC is improved with the increasing of fiber volume fraction.

关键词： ultra-high performance fiber reinforced concretes split Hopkinson pressurebar dynamic repeated impact

Variational construction of unbounded orbits in Lagrangian systems

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science china Mathematics 2010年第3期53卷 617-624页

作者： CHENG Chong-Qing 1, & LI Xia 2 1 Department of Mathematics, nanjing university, nanjing 210093, china 2 Department of Mathematics, Suzhou university of science and technology, Suzhou 215001, china Department of Mathematics Nanjing University Nanjing China Department of Mathematics Suzhou University of Science and Technology Suzhou China

We show the existence of unbounded orbits in perturbations of generic geodesic flow in T2 by a generic periodic potential. Different from previous work such as in Mather (1997), the initial values of the orbits obtain... 详细信息

关键词： positive definite Lagrangian variational method unbounded orbit

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science china Chemistry 2004年第6期47卷 466-479页

作者： SONG Huajie1,2, XIAO Heming1 & DONG Haishan2 1. Department of Chemistry, nanjing university of science and technology, nanjing 210094, china 2. institute of Chemical Materials, china Academy of Engineering Physics, Mianyang 621900, china Department of Chemistry Nanjing University of Science and Technology Nanjing China institute of Chemical Materials China Academy of Engineering Physics Mianyang China

The symmetry-adapted perturbation theory (SAPT) that has the ability in decompo- sition of the total interaction energy into physically meaningful components is used to provide a more fundamental understanding of intermolecular forces. This work was motivated by the diffi- culty of standard SAPT in computing the intermolecular interactions for large energetic dimer systems. SAPT based on Kohn-Sham orbitals (SAPT(DFT)) proves computationally efficient for these large systems, but has been shown to perform poorly for interaction energy components. The deficiencies of SAPT(DFT) result from wrong asymptotical behaviors of commonly used exchange-correlation potentials. To remove the deficiencies, two asymptotic corrections by means of van Leeuwen and Baerends (LB) model potential and Fermi-Amaldi (FA) type potential were applied into three small test systems comprising He2, HF2 and (N2)2 and a set of larger ni- tramide dimers at several separations. The results showed that when utilizing newly developed frequency-dependent density susceptibilities (FDDS) technique for computing dispersion energy, the FA asymptotic correction is very effective to circumvent these deficiencies in SAPT(DFT) and yields a good accuracy over the LB correction. The FA corrected SAPT(DFT) approach is capa- ble of correctly predicting all the quantitative trends in binding energies for all test cases and substantially reduces computational cost as compared with the standard SAPT calculations. The successful application of the approach to nitramide dimer demonstrates that it potentially pro- vides a good means to calculate accurately intermolecular forces in larger system such as en- ergetic systems.

关键词： intermolecular interaction, density functional theory (DFT), symmetry adapted perturbation theory (SAPT), asymptotic correction, frequency-dependent density susceptibilities (FDDS).

Global Convergence of the Conjugate Descent Method Under a kind of Inexact Line Search Conditions

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Systems science and Systems Engineering 2002年第1期11卷 1-5页

作者： XU Ze-shui institute of sciences, pla university of science and technology, nanjing 210016, china institute of sciences PLA University of Science and Technology Nanjing 210016 China

The conjugate descent (CD) was introduced by Fletcher. This paper proves that a kind of inexact line search conditions can ensure the global convergence of the CD method.

关键词： the conjugate descent (CD) line search

A new smoothing scheme for mathematical programs with complementarity constraints

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science china Mathematics 2010年第7期53卷 1881-1890页

作者： YAN TaoDepartment of Information and Computational sciences, College of science, nanjing university of science and technology, nanjing 210094, china Department of Information and Computational sciences College of Science Nanjing University of Science and Technology Nanjing China

In this paper, we consider a mathematical program with complementarity constraints (MPCC). We present a new smoothing scheme for this problem, which makes the primal structure of the complementarity part unchanged mostly. For the new smoothing problem, we show that the linear independence constraint qualification (LICQ) holds under some conditions. We also analyze the convergence behavior of the smoothing problem, and get some sufficient conditions such that an accumulation point of stationary points of the smoothing problems is C (M, B)-stationarity respectively. Based on the smoothing problem, we establish an algorithm to solve the primal MPCC problem. Some numerical experiments are given in the paper.

关键词： mathematical program with complementarity constrains MPEC-LICQ B-stationarity C-stationarity M-stationarity

Seasonal variation of global stratosphere-troposphere mass exchange

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Progress in Natural science:Materials International 2007年第12期17卷 1466-1475页

作者： Guo Dong1,2, Lu Daren2 and Sun Zhaobo1(1. institute of Atmospheric sciences, nanjing university of Information science and technology, nanjing 210044, china 2. LAGEO, institute of Atmospheric Physics, Chinese Academy of sciences, Beijing 100029, china) institute of Atmospheric sciences Nanjing University of Information Science and Technology Nanjing 210044 China LAGEO Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China

By Wei formula in pressure coordinate, the stratosphere-troposphere mass exchange (STME) is diagnosed globally for 44 years from 1958 to 2001 using the European Center for Medium-Range Weather Forecasts (ECMWF) reanalysis datasets. Regions of mass flux into the stratosphere are found over Indonesia, bay of Bangladesh and the mid-west coast of South Africa. Compensating mass outflow from the stratosphere appears mainly over mid-latitudes near large-scale troughs. Upward and downward transport of mass at the middle and high latitudes accompany with each other. Mass flux into troposphere is stronger in autumn and winter than in spring and summer. Strong downward mass flux into the troposphere occurs in eastern Asia the whole year with nearly stable sites. Although the area of eastern Asia accounts for only 5.6% of that of the northern hemisphere (NH), its net mass exchange reaches 15.83% of that of the NH, which means that research on STME of eastern Asia is greatly important to that of the NH and even the global areas. Air across the tropopause enters more from stratosphere to troposphere than that from troposphere to stratosphere, which is possibly related with systematic bias of the assimilated datasets and with persistent rise of the tropopause height. Contributions of the mass exchange and the mass flux exchange in the NH and southern hemisphere (SH) on their latitudes increase from equator to pole, with larger contributions in the NH. Mass exchange and mass flux exchange per areas at high latitudes are larger than that at low latitudes, which means greater mass exchange efficiency at high latitudes.

关键词： stratosphere troposphere mass exchange seasonal variation.

Nitrogen isotopic geochemical characteristics of crude oils in several basins of china

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science china Earth sciences 2005年第8期48卷 1211-1219页

作者： CHEN Chuanping1,2, MEI Bowen1 & CAO Yacheng3 1. Jianghan Petroleum university, Jingzhou 434100, china 2. Huazhong university of science and technology, Wuhan 430047, china 3. nanjing institute of Soil science, Chinese Academy of sciences, nanjing 210008, china Jianghan Petroleum university Jingzhou China Huazhong university of science and technology Wuhan China nanjing institute of Soil science Chinese Academy of Sciences Nanjing China

Nitrogen isotopic ratios of crude oils with different physical and chemical properties in several basins of china have been measured and their geochemistry has been studied ele-mentally combined with molecular organic geochemistry methods. The data indicate that δ 15N is in the range of ?6‰-20‰. They vary with the oils in different sedimentary types of basins. The oils forming in the limnic environment have lower δ 15N with the value of about 1‰-5‰ whereas the oils in saline or semi-saline environment have higher δ 15N, with most samples being above 10‰ and some exceeding 17‰. The average nitrogen isotopic ratio of oils from the Ordovician formation in the Tarim Basin is the lowest, with most samples having δ 15N below zero, which reflects possibly the characteristic of the oils originating mainly from the organic matter formed in marine carbonate sedimentary environment. The δ 15N distribution can be altered by fractionation. It increases obviously because of biodegradation and decreases during hydrocarbon migration. However, the effect of nitrogen isotopic fractionation in the short distance migration is uncon-spicuous.

关键词： nitrogen isotope, crude oil, sedimentary environment, isotopic fractionation, china.

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 Engineering,nanjing university,nanjing 210093,china)Yang Jun(Jiangsu Metallurgy institute.nanjing 210007,china)

The genotoxicity of 22 substituted nitrobenzenes were evaluated by the chromosome aberrations test in in vitro human peripheral lymphocytes.18 of 22 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.

Influences of low-Ti substitution for La and Mg on the electrochemical and kinetic characteristics of AB_3-type hydrogen storage alloy electrodes

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science china(Technological sciences) 2010年第1期53卷 242-247页

作者： DONG ZhenWei1,2,WU YaoMing1,MA LiQun2,SHEN XiaoDong2 & WANG LiMin1 1 State Key Laboratory of Rare Earth Resource Utilization,Changchun institute of Applied Chemistry,Chinese Academy of sciences,C hangchun 130022,china 2 College of Material science and Engineering,nanjing university of technology,nanjing 210009,china State Key Laboratory of Rare Earth Resource Utilization Changchun Institute of Applied Chemistry Chinese Academy of Sciences Changchun China College of Material science and Engineering Nanjing University of Technology Nanjing China

The(La0.67Mg0.33)1-xTixNi2.75Co0.25(x = 0,0.05,0.10,0.15 and 0.20,at%) alloys were synthesized by arc melting and subsequent heat solid-liquid diffusing *** structure,electrochemical properties and kinetic characteristics of the alloys were investigated *** results showed that all the alloys mainly consisted of the(La,Mg)Ni3,LaNi5 phases,and the lattice parameters and the cell volumes of the(La,Mg)Ni3 and LaNi5 phases decreased with increasing Ti *** alloy electrodes could be activated to reach their maximum discharge capacity within five *** cycle life after 100 charge/discharge cycles(C100/Cmax) and the high-rate dischargeability at a discharge current density of 1200 mA/g first increased and then *** the results showed that low-Ti content in AB3-type hydrogen storage alloys was beneficial to improvements of the overall electrochemical properties,and the optimum overall electrochemical performance of the alloy electrodes was obtained when x = 0.05.

关键词： AB3-type alloy metal hydride electrode microstructure electrochemical property kinetic characteristic