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11.
利用微分方程的级数求解方法,分析了两端简支的有限长功能梯度圆筒的轴对称稳态热弹性问题,推导出了稳态温度场与应力场的解析解。分析中采用指数函数模型来描述FGM圆筒中材料性能在厚度方向的连续变化,同时忽略温度对材料性能的影响。另外,论文以金属钼和多铝红柱石制成的功能梯度圆筒为例,给出了稳态温度场和应力场的数值结果。 相似文献
13.
Dispersion Compensation in Externally Modulated Transmission System Using Chirped Fiber Grating 总被引:1,自引:0,他引:1
We present an externally modulated NTSC AM-VSB erbium-doped fiber amplifier (EDFA)-repeated system in the 1550 nm region which uses a chirped fiber grating (CFG) as a dispersion compensation device. In contrast to the conventional externally modulated fiber optical CATV systems, either with or without dispersion compensation fiber (DCF), good performances of carrier-to-noise ratio (CNR) ≥50 dB, composite second order (CSO) ≥74 dB, and composite triple beat (CTB) ≥65 dB were achieved for the full channel band after a 100-km single-mode fiber (SMF) transmission. 相似文献
14.
Summary Glass formation in nature and materials science is reviewed and the recent recognition of polymorphism within the glassy state,
polyamorphism, is discussed. The process by which the glassy state originates during the continuous cooling or viscous slowdown
process, is examined and the three canonical characteristics of relaxing liquids are correlated through the fragility. The
conversion of strong liquids to fragile liquids by pressure-induced coordination number increases is discussed, and then it
is shown that for the same type of system it is possible to have the same conversion accomplished via a first-order transition
within the liquid state. The systems in which this can happen are of the same type which exhibit polyamorphism, and the whole
phenomenology can be accounted for by a recent simple modification of the van der Waals model for tetrahedrally bonded liquids.
The concept of complex amorphous systems which can lose a significant number of degrees of freedom through weak first-order
transitions is then used to discuss the relation between native and denatured hydrated proteins, since the latter have much
in common with plasticized chain polymer systems. Finally, we close the circle by taking a short-time-scale phenomenon given
much attention by protein physicists,viz., the onset of an anomaly in the Debye-Waller factor with increasing temperature, and showing that for a wide variety of liquids,
including computer-simulated strong and fragile ionic liquids, this phenomenon is closely correlated with the experimental
glass transition temperature. This implies that the latter owes its origin to the onset of strong anharmonicity in certain
components of the vibrational density of states (evidently related to the boson peak) which then permits the system to gain
access to its configurational degrees of freedom. The more anharmonic these vibrational components, the closer to the Kauzmann
temperature will commence the exploration of configuration space and, for a given configurational microstate degeneracy, the
more fragile the liquid will be.
Paper presented at the I International Conference on Scaling Concepts and Complex Fluids, Copanello, Italy, July 4–8, 1994. 相似文献
15.
Optical properties and microstructure of Ag film on glass substrate with Cr intermediate layer were studied by using spectrophotometer and XRD. The spectra results showed that introducing Cr intermediate layer reduced the surface roughness and promoted the reflectivity of Ag film. The XRD analysis showed that the crystalline grains increased and the stress decreased. The adhesion was also improved by using the tape test method. 相似文献
16.
The effect of γ-ray irradiation on the magnetic properties of NdFeB and Fe–Cr–Co permanent magnets has been investigated. The magnetic flux loss of two kinds of magnets before and after irradiation was measured. Results show that the effect of γ-ray irradiation on the magnetic properties of sintered NdFeB is not so obvious as that on Fe–Cr–Co magnet. Irradiation-induced damage from γ-ray for the Fe–Cr–Co magnets was characterized for the first time. The decline of permanent magnetic properties of Fe–Cr–Co magnet induced by γ-ray irradiation is reversible except for the maximum energy product (BH)max. The difference of coercivity mechanism between these two kinds of permanent magnets is responsible for the different dependence of magnetic properties loss induced by γ-ray irradiation. 相似文献
17.
巯基乙酸锑配合物的合成与X射线粉末衍射数据指标化 总被引:2,自引:0,他引:2
一些锑和铋的配合物可以应用于医药研究[1,2 ] ,已合成了许多锑的有机配体配合物[3~ 7] ,但其中大多数没有生物活性。因此 ,研究锑或铋离子的配合物不仅对主族元素化学、生物无机化学而且对医药都有着非常重要的意义。我们用三氯化锑与巯基乙酸液相反应法合成的二巯基乙酸锑 (Ⅲ)配合物 ,其组成为HSb(SCH2 COO) 2 ,用X射线粉末多晶衍射数据指标化来研究配合物晶体结构[8] 。1 实验部分1 1 仪器与试剂EA - 1 1 0 6型元素分析仪 (意大利卡拉欧巴公司制造 ) ,D Max -YB型多晶X射线粉末衍射仪(日本理学 ,CuKα射线 ,… 相似文献
18.
Xuefeng Yue Xinliang Lu Yongyuan Song Zongshu Shao Daliang Sun Quanzhong Jiang Huanchu Chen 《Applied physics. B, Lasers and optics》1991,53(5-6):319-322
The use of Cu-doped (K0.5Na0.5)0.2(Sr0.61Ba0.39)0.9Nb2O6 as self-pumped phase conjugators using internal reflection is reported. Reflectivities as high as 63% at 5145.5 nm and 60% at 632.8 nm were realized. It was found that the photorefractive response changes significantly at different doping concentration. The responses of the crystals to the laser wavelength, incident angle and dopant concentration are studied. 相似文献
19.
Mooson Kwauk 《中国颗粒学报》2004,(1)
IntroductionInmaterialscience,differentmicrostructuresofthesamematerialsmayinducediversebehaviorsanddifferentcharacteristics.Westwood(1988)showed,asanexample,thatthetreatmentofaluminumsurfacewithcommercialphosphoricacidproducedmechanicallyinterlockedoxide搘hiskers?approximately10nmindiameterand400nminlength,whichmechanicallyinterlocked.Thismicro-structurecankeepsuchaconglomeratebondedoverconsiderablerangesofstressandtemperature.Inahumidatmosphere,especiallythatcontainingchlorine,however,suchox… 相似文献
20.
Al-Cu-Fe thin films were prepared by laser induced arc (laser-arc) method from a single source—Al63Cu25Fe12 alloy, which was proved to consist of quasicrystalline phase together with approximant phase. The composition of the deposited films meets the requirement for formation of icosahedral symmetry phase. Quasicrystalline phase was obtained after annealing the amorphous as-deposit film samples. The optical properties of the samples were investigated. Thin film samples of Al, Cu and Fe deposited under the same condition were employed for comparison. The results showed specific reflective properties of Al-Cu-Fe quasicrystal thin film in some wavelength range. The optical conductivity of the films exhibited a negative peak, centered about 440 nm in range of 190 to 800 nm. The Al-Cu-Fe quasicrystal thin films could absorb almost all the ray in the wavelength range from 420nm to 450 nm. The ratio of absorption was greater than 99%. 相似文献