周萧明
,
胡更开
复合材料学报
doi:10.3321/j.issn:1000-3851.2004.06.026
提出了预测复合材料非线性电位移和电场强度关系的一种解析方法,该方法基于各向材料的割线介电常数,将非线性问题转化成一系列线性问题来求解.该方法适用于任意各向异性复合材料和组分材料的非线性性质,而常用的Stroud和Hui的模型只适用于各向同性复合材料和组分材料的弱线性.证明了本文方法具有Ponte Castaneda提出的变分结构.计算结果表明,当基体非线性较小时,本文模型的预测与Stroud和Hui的模型一致,但当基体非线性系数增大时,本文模型能给出合理的预测结果,而Stroud和Hui的模型则会超出基体和夹杂的性能范围.
关键词:
复合材料
,
介电常数
,
非线性
,
割线方法
Acta Physica Sinica
Molecular dynamics (MD) simulation is performed to study the vacancy-interstitial annihilation in crystalline silicon. We choose the Stillinger-Weber potential, which is commonly used for silicon, to describe the interaction between atoms. The system is relaxed under 300K and 1400K respectively. We have found that < 111 > is the preferred recombination direction and propose the presence of an energy barrier in the < 110 > direction. From the calculated value of energy barrier along < 110 > we give a reasonable explanation for the difference between Tang's and Zawadzki's data.
关键词:
molecular dynamics;vacancy and interstitial;diffusion;point-defects;diffusion;mechanisms
Journal of Physics-Condensed Matter
This research purposes to investigate the atomic and electronic structures of the Al/TiC(001) interface with lattice misfit using the ab initio pseudopotential approach. A detailed analysis of the relaxed atomic structure reveals that the atoms over the initial unfavourable sites relax to the favourable sites along the lateral plane. The properties of the semicoherent interface can be taken as averages over the different coherent sites. In addition, the interface atoms in relatively favourable regions are dragged near to the interface, while those in unfavourable regions are pushed away from the interface. Therefore, a large war-ping near the interface is made perpendicular to the lateral plane. The calculated adhesions explain the different wetting results from the viewpoint of structural transition. The subsequent analysis of electronic properties demonstrates that adhesions dominate mainly via the strong Al-C covalent bond.
关键词:
first-principles;1st principles;adhesion;surfaces;misfit;1st-principles;wettability;al
X. Q. Yang
,
L. X. Huo
,
Y. F. Zhang and J. X. Yan (School of Material Science and Engineering
,
Tianjin University
,
Tianjin 300072
,
China)
金属学报(英文版)
The buckling formation and influence factors during welding thin - plated structures were investigated based on finite element methods, An engineering treatment method for prdicating the buckling distor- tion was proposed in here. It was used the equivalent applied thermal - load to simulate the welding residual stress,therefore the calculation of complex welding distoriton can be transformed into 3D elas- tic structural applied- load analyses, which can reduce the quantities of calculating works effectively. The validation of the method was verified by comparison of the numerical simulation and experimental results. The simulation of buckling distorition for side - walled structrues of paseenger train was per- formed and the calculation was in agreement with measuring results in general. It was shown that the main factors for producing the buckling were the intermittent fillet and ping the during welding the stiffened beams and columns to the panel.The existence of the free edge of panels would reduce the crit- ical buckling stress and enlarge the deflection obviously,but the continuous weld in closed frames didn' t degrade the buckling situation.
关键词:
welding buckling distortion
,
null
,
null
Z.L. Ding
,
Y.C. Fan
,
H.B. Qi
,
D.L. Ren
,
J.B. Guo and Z.Q. Jiang Shijiazhuang Railway Institute
,
Shijiazhuang 050043
,
China
金属学报(英文版)
The SiC_p/Al-alloy composite front broke rotors designed for SHANGHAI SANTANA cars were prepared by semi-solid stirring+liquid for ping process. The properties of the composite rotors were examined. The composite brake rotors were subjected to dynamometer tests on a SCHENCK broke testing system, referring to TLll0 standard of VOLKSWAGEN Company. The friction coefficient and thermal response during fade testing and the wear performance of the composite rotors were studied as the function of various parameters, such as braking pressures, initial speeds, initial temperatures, torque and decelerations, and compared with that of conventional cast iron rotors. The results showed that the properties of SiC_p,/Al-alloy composite rotors can achieve the requirements of commercial cast iron rotor.s. The results also suggested that the friction coefficients of composite rotors under different broking conditions are within the deviation band specified by the TLll0 standard, and the temperature rise of the composite rotors at the cud of each fade stop is lower than that of the cast iron rotors. The wear resistance of composite rotors was higher than that of cast iron rotors. The friction and wear mechanism are analyzed.
关键词:
SiC_p/Al-alloy composite
,
null
,
null
,
null
钱鹏
,
李兴华
量子电子学报
doi:10.3969/j.issn.1007-5461.2015.06.008
基于量子信道加密原理,结合Ping-Pong协议控制模式和信息模式的概念,提出了一个量子安全直接通信协议.在此协议中,发送者和接收者用n对Bell态作为量子信道,发送者用controlled-Not操作将单粒子纠缠入量子信道,接收者用controlled-Not操作将单粒子与量子信道解纠缠.通信双方依次执行控制模式和信息模式,控制模式检测窃听,信息模式发送秘密信息.控制模式和信息模式均不会对已建立的量子信道造成破坏,因此建立量子信道的过程仅需执行一次,此后通信双方可以反复进行控制模式和信息模式,从而不断进行窃听检测和秘密信息传输.
关键词:
量子光学
,
量子安全直接通信
,
信道加密
,
窃听检测
刘守平
,
周上祺
,
王佳眉
,
任勤
腐蚀学报（英文）
用金相显微镜、扫描电镜、X射线衍射仪和X射线能谱仪对天然气井油管悬挂器腐蚀失效进行了检测分析，并对天然气井油管悬挂器用35CrMo钢进行了盐雾试验，结果表明，天然气中的水和CO2是引起腐蚀的主要介质，腐蚀产物主要是FeCO3，高速天然气冲刷和钢中的非金属夹杂加剧了腐蚀的速度.
CORROSION FAILURE ANALYSIS OF AN OIL TUBE USED IN NATURAL GAS WELL
LIU Shou-ping,ZHOU Shang-qi,WANG Jia-mei,REN Qin
Chongqing University
A failed oil tube used in natural gas well was examined by optical microscope,scanning electron microscope ,X-ray diffractometer and X-ray spectrometer.Corrosion behavior of 35CrMo steel samples of the oil tube were investigated by means of salt spray tests in the laboratory.The results show that CO2 and H2O are primary factors in the corrosion of oil tube.The corrosion product is FeCO3,non-metallic inclusions in the steel and erosion of natural gas fluid played an important role in accelerating the corrosion.
oil tube;
natural gas well；
35CrMo steel；
failure analysis；
corrosion
关键词:
悬挂器
,
null
,
null
,
null
