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A theoretical model of collision between soft-spheres with Hertz elastic loading and nonlinear plastic unloading

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Theoretical & Applied Mechanics Letters 2011年第4期1卷 34-39页

作者： Youhe Zhou 1,2.a) 1) key laboratory of Mechanics on Disaster and Environment in Western {2.,the ministry of education of {2. 2.Department of Mechanics and Engineering Science,College of Civil Engineering and Mechanics,Lanzhou University,Lanzhou 730000,{2. key laboratory of Mechanics on Disaster and Environment in Western {2. the Ministry of Education of China China Department of Mechanics and Engineering Science College of Civil Engineering and Mechanics Lanzhou University Lanzhou 730000 China

This paper presents a theoretical model on the normal(head-on) collision between soft-spheres on the basis of elastic loading of the Hertz contact for compression process and a nonlinear plastic unloading for restitution one,in which the parameters all are determined in terms of the material and geometric ones of the spheres,and the behaviors of perfect elastic,inelastic,and perfect plastic collisions appeared in the classical mechanics are fully described once a value of coefficient of restitution is specified in the region of 0 ≤ ε ≤ *** an empirical formula of the coefficient of restitution dependent on the impact velocity is suggested to fit the existing experimental measurements by means of the least square method,the predictions of the dependency and the collision duration are in well quantitative agreement with their experimental *** is found that the measurable quantities are dependent on both the impact velocity and the parameters of *** this model,finally,an approach to determine the spring coefficient in the linear viscoelastic model of the collision is also *** results obtained here will be significantly beneficial for the applications where a collision model is requested in the simulations of relevant grain flows and impact dynamics etc..

关键词： normal collision of soft-spheres theoretical model residual displacement restitution coefficient collision duration

Eu^(3+)-doped LaPO_4 and LaAlO_3 nanosystems and their luminescence properties

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Science china Chemistry 2009年第8期52卷 1104-1112页

作者： WAN Qiang,HE YuPing,DAI Ning & ZOU BingSuo State key laboratory of State key laboratory of Chemo/Biosensing and Chemometrics and key laboratory for Micro-Nano Opto-Electronic Devices of ministry of education,Hunan University,Changsha 410082.china State key laboratory of State key laboratory of Chemo/Biosensing and Chemometrics and key laboratory for Micro-Nano Opto-Electronic Devices of ministry of education Hunan University Changsha China

Eu3+ ion-doped LaPO4 nanowires or nanorods have been successfully synthesized by a simple hydrothermal *** influence of varying the hydrothermal and subsequent sintering conditions on the morphology and structure of the LaPO4 host has been investigated by scanning electron microscopy(SEM) and X-ray diffraction(XRD).For comparison,the Eu3+ ions were also doped into monoclinic monazite LaPO4 nanoparticles and perovskite LaAlO3 *** relative intensities of the emission lines of the LaPO4:Eu3+ nanosystems were essentially independent of their *** optimal doping concentrations in the monoclinic LaPO4 and perovskite LaAlO3 nanosystems were determined to be about 5.0 and 3.5 mol%,*** appropriate UV-radiation,the red light emitted from LaAlO3:Eu3+(3.5 mol%) was brighter than that from LaPO4:Eu3+(5.0 mol%) nanomaterial,resulting from differences in their spin-orbit couplings and covalence,which indicates that the nanoscale LaAlO3 is a promising host material for rare earth ions.

关键词： doping synthesis luminescence nanosystem

Mechanical Characteristics of Typical Plant Leaves

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Journal of Bionic Engineering 2010年第3期7卷 294-300页

作者： Shujie Wang, Luquan Ren, Yan Liu, Zhiwu Han, Yue Yang The key laboratory of Bionic Engineering ({2. of education, china), Jilin University, Changchun 13002., P. R. china The key laboratory of Bionic Engineering ({2. of education China) Jilin University Changchun P. R. China

Plant leaf is a natural composite biomaterial, and its strength is closely related to the microstructure. In this paper, themechanical characteristics of eight species of plant leaves were investigated and analyzed. The ultimate strength of leaves andthe hardness of leaf surfaces were measured by using universal testing machine and nanoindenter tester, respectively. The tensilestrength of the parallel microstructure was investigated based on its cross-sectional mechanical model. The results of tensiontests indicate that the ultimate strength of a leaf is related to the material composition and structure. The coriaceous leavesusually exhibit higher tensile strength. For example, the Phyllostachys pubescens leaf can achieve the maximum ultimatestrength of 5.9091 N·mm. It is concluded from the results of hardness tests that material components of leaf surface caninfluence the surface hardness evidently. The leaf surface composed of more lignin and cellulose materials shows a highersurface hardness than that composed of more carbohydrates materials.

关键词： bionics plant leaf hardness tensile strength

A Modified Integrated Model of the Internal Structure of Chinese Cultured Pearls

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Journal of Wuhan University of Technology(materials Science) 2011年第3期26卷 510-513页

作者：马红艳 key laboratory of Nonferrous Metals and New {2. Processing Technology Ministry of EducationCollege of Materials Science and EngineeringGuangxi University

Optical and micro-infrared microscope were used to observe the internal structure and mineral composition of high and low quality Chinese seawater and freshwater cultured *** clearly reveal that aragonite and calcite are found in seawater cultured pearls,but vaterite is not *** contrast,vaterite and aragonite are found in freshwater cultured pearls,but calcite is not *** on our analysis and observations of the internal structure of high and low quality cultured pearls,a modified integrated model of the internal structure of Chinese cultured pearls was *** revisions to the previous model focus on significant differences within the prismatic layer of Chinese cultured pearls.

关键词： cultured pearls aragonite vaterite calcite integrated model

Study on transmittance spectra of ITO thin films by ellipsometric method

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Science china(Technological Sciences) 2010年第7期53卷 1893-1896页

作者： SUN ZhaoQi1, CAO ChunBin12., CAI Qi1 & SONG XuePing1 1 School of Physics and material Science, Anhui University, Hefei 2.0039, china 2.School of Sciences, Anhui Agricultural University, Hefei 2.0036, china 3 key laboratory of Opto-electronic Information Acquisition and Manipulation, ministry of education, Hefei 2.0036, china School of Physics and material Science Anhui University Hefei China School of Sciences Anhui Agricultural University Hefei China key laboratory of Opto-electronic Information Acquisition and Manipulation Ministry of Education Hefei China

ITO films with thicknesses (134+8) nm, grown on glass substrates by sputtering method, were post-annealed at the temperatures of 100, 2.0, 300 and 400°C for 1 h, respectively. The as-deposited ITO film was amorphous, but crystallized with annealing at elevated temperatures, as demonstrated by X-ray diffraction. The transmittance spectra of all samples were obtained and subsequently simulated by means of spectroscopic ellipsometry. The optical constants n and k of the films were extracted. With the annealing temperature increasing, the optical constants n and k of the films firstly decreased then increased in the whole investigated wavelength range. The optical band gaps of all films were evaluated and they varied between 3.74 and 3.93 eV.

关键词： ITO films optical constants transmittance spectra spectroscopic ellipsometry analysis

A New Secure Password Authentication Scheme Using Smart Cards

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Wuhan University Journal of Natural Sciences 2008年第6期13卷 739-743页

作者： WANG Bangju1,2. WANG Yuhua3, ZHANG Huanguo1 1. School of Computer, Wuhan University/key laboratory of Aerospace Information Security and Trust Computing of{2., Wuhan 430072. Hubei, china 2. School of Science, Huazhong Agricultural University, Wuhan 430070, Hubei, china 3. College of Information Science and Engineering, Henan University of Technology zhengzhou 450001, Henan, china School of Computer Wuhan University/Key Laboratory of Aerospace Information Security and Trust Computing of Ministry of Education Wuhan China School of Science Huazhong Agricultural University Wuhan China College of Information Science and Engineering Henan University of Technology Zhengzhou China

Thirteen security requirements for an ideal password authentication scheme using smart cards are listed and a new smart card based password authentication scheme with identity anonymity is proposed. The new scheme can satisfy all the listed ideal security requirements and has the following merits：（1） it can resist all the attacks listed in introduction; （2. less storage memory requirement due to no verification table stored in server; （3） low computational cost due to hash functions based operations; （4） even if the smart card is lost, the new system is still secure; （5） As user identity is anonymous, this scheme is more practical. The new proposed scheme can be applied in source constraint networks.

关键词： password password authentication hash function attack smart card

Internal Curing Using Water-releasing material for High Strength Micro-expansive Concrete

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Journal of Wuhan University of Technology(materials Science) 2009年第3期24卷 510-513页

作者：吕林女 School of Science Wuhan University of Technology

Due to its low water content, it is difficult for expansive agent to have an effective expansive effect on high strength concrete to compensate its extensive shrinkage and form a certain expansion. To solve this problem, water-releasing material with water storage and releasing characteristics was incorporated into high strength micro-expansive concrete to provide internal curing, and expansive effect of expansive agent was improved. Migration of water from initially saturated water-releasing material to the surrounding hydrating cement paste was investigated. Based on a given efficient diffusion distance of water stored in water-releasing material, the mass and real water-cement ratio of cured cement paste were estimated. At the same time, the effect of internal curing of water-releasing material on the volume deformation of high strength micro-expansive concrete was investigated.

关键词： water-releasing material high strength concrete expansive internal curing

Geochemistry of high-Mg andesites from the early Cretaceous Yixian Formation, western Liaoning: Implications for lower crustal delamination and Sr/Y variations

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Science china Earth Sciences 2006年第9期49卷 904-914页

作者： WANG Xiaorui1, GAO Shan1,2. LIU Xiaoming1, YUAN Honglin1, HU Zhaochu1, ZHANG Hong1,3 & WANG Xuance4 1. State key laboratory of Continental Dynamics, Department of Geology, Northwest University, Xi`an 710069, {2. 2. State key laboratory of Geological Processes and Mineral Resources, {2. University of Geosciences, Wuhan 430074, {2. 3. Shenyang Institute of Geology and Mineral Resources, Shenyang 110032. {2. 4. Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, {2. State key laboratory of Continental Dynamics Department of Geology Northwest University Xi’an China State key laboratory of Geological Processes and Mineral Resources China University of Geosciences Wuhan China Shenyang Institute of Geology and Mineral Resources Shenyang China Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou China

85 volcanic rocks of the Yixian Formation from the Sihetun type section werecollected and analyzed for geochemical and isotopic compositions. Major element compositionsindicate that the Sihetun volcanic rocks are high magnesium andesites with some basalts occurring atthe bottom of section. The Sihetun high magnesium andesites (SiO_2.= 52.82.59.31 wt%, Al_2._3=14.15-16.35wt%) show many characteristics of adakites such as depletion in heavy rare-earth elements(HREE; Yb = 1.03-1.88 μg/g) and Y(12.2. μg/g) and high Sr (62.-132. μg/g) and Sr/Y(32.88), withhigh La_N/Yb_N ratio (10-2.). They share similar major and trace element characteristics to volcanicrocks from the Xinglonggou Formation except their lower Nd isotope ratios (^(143)Nd/^(144)Nd(130Ma) = 0.5118-0.5119, ε_(Nd) (130Ma) = -11.6-13.8, ^(87)Sr/^(86)Sr (130 Ma) = *** were interpreted in a way that eclogite that formed at the base of thickened Archean lowercrust of the North china craton foundered into the convecting mantle and subsequently melted andinteracted with peridotite. However, compared to the Xinglonggou volcanic rocks, the source of theSihetun magma contained more ancient continental crustal material in order to explain its evolved Ndisotopes. The age of the Sihetun Formation was 12. to 130 Ma, and this indicates that delaminationlasted to the early Cretaceous period. The Sr contents and Sr/Y ratios of the Sihetun high-Mgandesites show significant negative correlations with SiO_2.for samples with SiO_2.> 56%. Thesesuggest that the Sr and Sr/Y values were reduced due to fractional crystallization of ***, the effect of crystallization on volcanic Sr and Sr/Y ratio has to be taken intoaccount.

关键词： High-Mg andesite, Adakite, Yixian Formation, North china Craton, delamination.

Change of Electrochemical Property of Reinforced Concrete after Electrochemical Chloride Extraction

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Journal of Wuhan University of Technology(materials Science) 2007年第4期22卷 764-769页

作者：王新祥 key laboratory of Specially Functional {2.s of the ministry of education South China University of Technology Guangdong Academy of Construction and Architecture Science Guangzhou 510500China

The half cell potential （HCP） and corrosion current of reinforced concrete specimens doped with sodium chloride were determined after electrochemical chloride extraction （ECE）. The experimental results show that when ECE treatment is removed, HCP becomes more negative and corrosion current becomes larger in comparison to those before ECE treatment, then HCP shifts positively and corrosion current decreases with time. After 30 days ECE treatment, the HCP of cored specimens turn to about -100 mV due to the existence of sufficient oxygen around the exposed steel bars, but for un-cored specimens, longer time, about two months, is to be taken. The non-homogeneous HCP distribution at different layers of the same specimen after ECE treatment might induce secondary corrosion of steels.

关键词： reinforced concrete corrosion electrochemical chloride extraction half-cell potential corrosion current