共查询到19条相似文献，搜索用时 415 毫秒
1.
For in -situ composite materials,the interaction between the second-phase particles and the solidification interface attracts more attentions of people,for concerning the final distribution of the particles on the matrix.With the conception of the local solidification time,a kinematics mechanism of particle pushing into the crystal boundary during the solidification process was assumed.Through the analysis of forces acted on the particle in front of the solid /liquid interface the critical velocity criterion for the particles pushing was given.The calculation results show when the growth rate of the interface V is less than or equals to the critical velocity Vc,the particles on the solid/liquid interface is pushed into the boundary region of cellular crystals,where they are distributed as a chain-like straight,which forms a particle-strengthened in-situ composite materials. 相似文献
2.
6-aminopenicillanic acid (6-APA) crystals obtained under different physical and chemical conditions of the solutions may present different habits. The habits of diamond-shaped plates are desirable compared with other habits of 6-APA crystals. To obtain ideal 6-APA crystals, the effects of the mixed solvents and additives on 6-APA crystal habits were investigated. Ethanol or acetone was used as the organic solvent, and impurities existing in the ,6-APA purification process were used as the additives. 6-APA growth habits were changed when the concentrations of ethanol, acetone or phenyl acetic acid were increased to exceed their critical concentration. The observed results show that the dominant face on 6-APA crystals was identified to be , {020}, but the overall habit was controlled by the relative growth rates of the : 101 and {002} faces. Crystal growth rates and habits can be appreciably changed by specific adsorption of additives on crystal faces. In some cases solvent molecules can act in a similar way and may be regarded as bulk additives. The effects of additives and organic solvents on 6-APA crystal habits were the results of adsorption effect,which fitted the experimental results quite well. 相似文献
3.
Numerical Derivation of Strain Rate Effects on Material Properties of Masonry with Solid Clay Bricks
In this paper, numerical method is used to study the strain rate effect on masonry materials. A typical unit of masonry is selected to serve as a representative volume element (RVE). Numerical model of RVE is established with detailed distinctive modeling of brick and mortar with their respective dynamic material properties obtained from laboratory tests. The behavior of brick and mortar are characterized by a dynamic damage model that accounts for rate-sensitive and pressuredependent properties of masonry materials. Dynamic loads of different loading rates are applied to RVE. The equivalent homogenized uniaxial compressive strength, threshold strain and elastic modulus in three directions of the masonry are derived from the simulated responses of the RVE. The strain rate effect on the masonry material with clay brick and mortar, such as the dynamic increase factor (DIF) of the ultimate strength and elastic modulus as a function of strain rate are derived from the numerical results. 相似文献
4.
Li Y Luo ZY Yu CJ Luo D Xu ZA Cen KF 《Journal of Zhejiang University. Science. B》2005,6(11):1124-1129
INTRODUCTION The solid oxide fuel cell (SOFC) has attracted much attention as a promising source of electrical power generation because of its high efficiency in converting chemical energy to electrical power. De- velopment of SOFC with operating temperature of less than 800 °C has been extensively studied. SOFC has the potential to have the cost of its materials, cell fabrication, and corrosion of its stack components dramatically reduced. Gadolinia-doped ceria with the chemical fo… 相似文献
5.
The soil-pile-bridge interaction of super-large pile groups is a very complex issue for the design of deep pile group foundations. In this paper, the load distribution on the pile top of a super large bridge foundation and its influential factors are analyzed comprehensively using a three-dimensional elasto-plastic finite element method. The adopted model and its input parameters are firstly verified by comparing the numerical results with the measured data of static loading tests of a single pile. Numerical analysis is then performed to investigate the load distribution and the load-settlement characteristics of super-large pile groups, and the models are verified using centrifuge laboratory model testing data. The mechanism of the interaction between pile groups and soil under different conditions is explored. 相似文献
6.
DHARMALINGAM K. RAMACHANDRAN K. SIVAGURUNATHAN P. 《浙江大学学报(A卷英文版)》2006,7(11):1928-1931
INTRODUCTION Hydrogen bonds constitute a very interesting class of intermolecular interactions, which are of extreme importance in many fields of chemistry and molecular biology. Acrylic esters are industrially important chemicals and precursors in the synthesis of polymers (Schildknecht, 1977). Alcohols play an important role in many chemical reactions due to the ability to undergo self-association with manifold internal structures and are in wide use in industry and science as reagents,… 相似文献
7.
Phosphorus in energy storage has received widespread attention in recent years. Both the high specific capacity and ion mobility of phosphorus may lead to a breakthrough in energy storage materials. Black phosphorus, an allotrope of phosphorus, has a sheet-like structure similar to graphite. In this review, we describe the structure and properties of black phosphorus and characteristics of the conductive electrode material, including theoretical calculation and analysis. The research progress in various ion batteries, including lithium-sulfur batteries, lithium–air batteries, and supercapacitors, is summarized according to the introduction of black phosphorus materials in different electrochemical applications. Among them, with the introduction of black phosphorus in lithium-ion batteries and sodium-ion batteries, the research on the properties of black phosphorus and carbon composite is introduced. Based on the summary, the future development trend and potential of black phosphorus materials in the field of electrochemistry are analyzed. 相似文献
8.
INTRODUCTION Polymer chains with one end attached to a sur- face by means of physical or chemical interaction have become one of the important polymer science subject, which are useful for many applications, such as polymer compatibilizers, copolymer microphases, colloid stabilization, polymeric surfactants (Milner, 1991). Grafting polymers can improve the power efficiency of electrorheological fluids, enhance pho- toluminescence of nano materials, and increase dis- persion stability. On … 相似文献
9.
There is a concern that the teaching of subjects is applied not only with support from a set of technological devices, but largely in the proper use of teaching and new technologies. Taking this idea, the authors develop a research and sustainable design that result in educational materials in solid content and technological innovation, also to have the benefit of learning process of a particular subject. The project is in its stage of development of educational materials, which indicates that only the experiment is missing. 相似文献
10.
The current situation and difficulties of the structural system reliability analysis are mentioned. Then on the basis of Monte Carlo method and computer simulation, a new analysis method reduced expanding load method (RELM) is presented, which can be used to solve structural reliability problems effectively and conveniently. In this method, the uncertainties of loads, structural material properties and dimensions can be fully considered. If the statistic parameters of stochastic variables are known, by using this method, the probability of failure can be estimated rather accurately. In contrast with traditional approaebes,RELM method gives a much better understanding of structural failure frequency and its reliability index β is more meaningful. To illustrate this new idea, a specific example is given. 相似文献
11.
THz频域层状一维光子晶体光纤的设计 总被引：1，自引：0，他引：1
黄艳月 《赣南师范学院学报》2008,29(3):61-65
针对传统金属微波波导和介质光波导难以解决飞秒激光脉冲作用于光电导天线或光整流晶体产生的0.1-4THz脉冲辐射传输中的群速色散问题,光子晶体光纤在色散设计方面具有很强优势.本文利用光在多层介质中传输的传输矩阵法对层状一维光子晶体光纤进行数值计算,并通过对THz频域材料特性的研究,设计出适合于传输0.1-1THz频段的层状一维光子晶体光纤. 相似文献
12.
提出了非线性液晶光信号放大器的原理、结构和系统,理论分析了光信号放大器的实验结果。研究表明,这种光信号放大器,由液晶光敏介质组成,这种光敏介质,能够接收已调制的信号光波和泵波,并能用于光传输系统。 相似文献
13.
配合物非线性光学性质与结构关系的研究 总被引：3，自引：0，他引：3
报导了无机物、有机物和配合物作为非线性光学材料的特点;阐述了二硫纶·二亚胺混配过渡金属配合物这一新型的具有潜在应用价值的非线性光学材料;对配合物非线性光学性质与结构的关系进行了较为系统的探讨． 相似文献
14.
乙酰丙酮、邻苯二胺与高氯酸以1∶1∶1的摩尔比在苯溶剂中反应,合成了标题化合物。通过红外以及X-衍射分析,确认了其化学结构。标题化合物的分子式为:C22H26N4C l2O8,Mr=545.37,晶体属单斜晶系,P2(1)c空间群,晶胞参数:a=7.4184(9),b=18.434(2),c=18.535(2),β=95.892(2)°,V=2521.2(5)3,Z=4,Dc=1.437Mg/m3,R1=0.0839,wR2=0.2488[I>2σ(I)]。 相似文献
15.
钱萍 《周口师范学院学报》2002,19(5):15-18,74
稀土永磁材料是以稀土金属元素与过渡族金属所形成的金属间化合物为基本的永磁材料，稀土永磁材料的磁性能与组成该永磁体的稀土化合物的晶体结构有密切关系，了解稀土永磁化合物的结构将为了解稀土永磁材料的性能和制造工艺打下基础，本文介绍了目前取得较大进展的新型稀土永磁材料的研究成果。 相似文献
16.
合成了一种新颖的配合物[Zn(H2O)(bpp)(Bript)2]n(其中,bpp=1,3-二(4-吡啶)丙烷,H2Bript=5-溴间苯二甲酸),并用X-射线单晶衍射仪测定了其结构.晶体数据表明,该配合物属单斜晶系,空间群P21/c,晶胞参数为:a=7.862(3),b=27.530(10),c=9.664(4),β=96.694(6)°,V=2077.6(13)3,Z=4,Dcalc=1.677 g·cm-3,μ=3.141 mm-1,F(000)=1056,R1=0.1119,wR2=0.2760.在配合物中,Zn原子被5-溴间苯二甲酸离子连接为一维链,这些一维链通过氢键和π…π相互作用连接在一起形成二维超分子化合物. 相似文献
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18.
高平安 《洛阳师范学院学报》2010,29(5):65-67
乙酰丙酮、邻苯二胺与高氯酸以1∶1∶1的摩尔比在苯溶剂中反应,合成了标题化合物.通过红外以及X-射线晶体测定,确认了标题化合物的化学结构和晶体结构.标题化合物的化学式为:C22H26N4Cl2O8,Mr=545.37,晶体属单斜晶系,P2(1)c空间群,晶胞参数:a=7.4184(9),b=18.434(2),c=18.535(2),β=95.892(2)°,V=2521.2(5)3,Z=4,Dc=1.437 Mg/m3.结构偏差因子R1=0.0839,wR2=0.2488. 相似文献
19.
邱学云 《楚雄师范学院学报》2014,29(6):12-16
选用非金属材料塑料和硅橡胶,组合成一维二元声子晶体匀直杆状结构。通过单一改变结构中非金属材料塑料的密度或者硅橡胶的密度,寻找单一材料密度变化与声子晶体杆禁带特性的关系。结果表明:当选取塑料密度为1190kg·m-3、硅橡胶密度为1300kg·m-3,晶格常数为0.3m,两种材料组份比相同时,一维二元非金属塑料/硅橡胶声子晶体存在低频禁带带隙,第1禁带起始频率为43.07Hz、禁带带宽为33.09Hz,第2禁带起始频率为99.84Hz,第2禁带带宽为52.49Hz;当单一改变塑料的密度,随着密度由小到大线性增加,结构第1带隙的起始频率由66.58Hz逐步减小到34.04Hz;第1带隙的截止频率为76.17Hz,保持不变,带隙宽度展宽;当单一改变材料硅橡胶的密度时,随着材料硅橡胶的密度由小到大线性增加,第1带隙的带宽由109.894HZ减小为18.3748Hz。对于一维二元非金属型声子晶体,选用密度更小的非金属材料与密度更大的非金属材料组合,更容易获得低频宽带带隙。另外,基于密度变化的同时还可以通过改变结构晶格常数的取值来获得更为理想的声子晶体禁带带隙。 相似文献