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61.
介绍了黄河上游龙青段主要环境工程地质问题的分析思路,以达到抛砖引玉,交流和提高电工程地质勘测水平的目的。 相似文献
62.
63.
A nuclear microprobe with high spatial resolution and high analytical sensitivity was applied to analyze trace elements,especially lead,in vehicle exhaust of Shanghai city.The result shows that the chemical composition and its corresponding x-ray relative intensity are different among different vehicle exhausts.There are many kinds of metal elements in particles of vehicle exhaust.most are harmful to people,such as Ti,Cr,Mn,Pb,etc.We found that the lead concentration was 6820μg/g and the bromine concentration was 5300μg/g in the exhaust from Santana using leaded gasoline(SULG).which is higher than any other kinds of vehicle exhausts.We have also detected the minimum lead in the particles of unleaded gasoline and its content varies from one to another.Its mean concentration was 450μg/g and the highest reached 6210μg/g.The unleaded gasoline‘s Pb existed in the whole particle while the leaded gasoline‘s enriched in the surface of the particle and was more harmful to the human beings. 相似文献
64.
啤酒标签用铝箔力学性能研究 总被引:3,自引:2,他引:1
分析研究了连续铸轧坯料的合金成分,冶金组织和热处理工艺对啤酒标用铝箔力学性能的影响,选定成形性优良的合金系列,并优化铸轧工艺和热处理工艺是提高铝箔力学性能的关键。 相似文献
65.
LU Xili WU Ye CAI Wei TANG Wenjun 《武汉理工大学学报(材料科学英文版)》2005,20(B12):287-289
A series of random and block poly( L-lactide-co-e-caprolactone ) ( PCLA ) copolymers whh different composition are prepared using stannous octaoate as catalyst.The effects of the amount of initiator on the intrinsic viscosity have been investigated. The structure of the PCLA copolymers is characterized by means of nuclear magnetic resonance( NMR ), Fourier transform infrared spectrum ( FTIR ), differential scanning calorimetry ( DSC ) and X- ray diffraction ( XRD ) methods. It is shown that the synthesis condition and the composition of copolymers obrious influence on the structure of PCLA copolymers. Hydrolytic degradation of the copolymers in a PBS solution of pH 7.4 at 37.0℃ shows that the copolymers of different composhions degrade at different rates. 相似文献
66.
The bonding of β'-Al2O3 and pyrex glass to Al matrix composites by anodic bonding process is achieved. The microstructure of the bonded interface and the joining mechanisms are analyzed with scanning electron microscope (SEM), energy dispersive X-ray fluorescence spectrometer (EDX). It is observed that the bonding region across the interface consists of the metal layer, oxide transitional layer and the ceramic layer, with the transitional layer composed of surface region and sub-surface region. The bonding process can mainly be categorized into anodic bonding process and solid state diffusing process. The pile-up of the ions and its drift in the interface area are the main reasons for anode oxidation and joining of the interface. The temperature, voltage and the drift ions in the ceramic or glass during the bonding process are the essential conditions to solid state diffusing and oxide bonding at the interface. The voltages, temperature, pressure as well as the surface state are the main factors that influence the anodic bonding. 相似文献
67.
W. S. Walston I. M. Bernstein A. W. Thompson 《Metallurgical and Materials Transactions A》1991,22(6):1443-1451
The microstructure of a single-crystal nickel-base superalloy, PWA 1480, has been varied by heat treatment and hot isostatic
pressing in order to study the role of the γ/yγ′ eutectic and porosity on subsequent tensile behavior. The level of porosity
was found not to affect any of the tensile properties, while the γ/γ′ eutectic strongly influenced ductility. Eliminating
the γ/γ′ eutectic increased ductility which was attributed to the cleavage fracture of this constituent. It is proposed that
such cleavage of the γ/γ′ eutectic is initiated by the stress created from impinging slip bands, promoting shear localization,
and final fracture along {111} slip planes. The precise nature of this fracture process is discussed with emphasis on the
role of the γ/′ micro-structure. The deformation structure of PWA 1480 was also studied, and while different in some respects
from many other single-crystal superalloys, its fracture process appears to be similar.
Formerly Graduate Student, Department of Metallurgical Engineering and Materials Science, Carnegie Mellon University. 相似文献
68.
69.
Bismuth is a semimetal that has a relatively low lattice thermal conductivity. A positive energy gap can be created by alloying with antimony, leading to useful alloys for thermoelectric energy conversion. This paper gives an insight into the basic properties of BiSb alloys for thermoelectric applications. 相似文献
70.
阐述了仿真环境中的网络攻击模型的设计,建立了一个网络攻击仿真模型,用以产生网络攻击,以达到摧毁网络的机密性、完整性和可用性的目的;采用知识表达的方法来建立模型,该模型包含具有知识库和推理机的专家系统,通过随时间而变化的量,使模型具有基于仿真时钟的推理能力;在攻击模型的设计中,定义了它的基本状态和状态跃迁函数,说明了模型的行为,以及攻击策略的制定,最佳策略的选择,攻击选择原则等问题。 相似文献