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101.
Asymptotic deformation and stress fields at the tip of a sharp notch in an elastic-plastic material 总被引:2,自引:0,他引:2
The singular elastic-plastic stress, strain and the displacement fields at the tip of a sharp notch for both plane stress and plane strain conditions are investigated analytically. The material is assumed to be governed by the deformation theory of plasticity with linear strain hardening characteristic. Since the elastic strain is retained in the analysis, the final strain and displacement fields can be separated into the elastic and the plastic parts. In the case with zero notch angle, the results reduce to the classical crack problem. The relationship of the amplitude of the near crack tip elastic-plastic field to the elastic far field is obtained. Both mode I and mode II cases are investigated. The mixed mode case is also discussed. 相似文献
102.
103.
瑞典Laholm沼气厂的运行实践 总被引:1,自引:0,他引:1
瑞典沼气的总产量约为1400GW·h,约有60%产自200多家市政污水处理厂的污泥消化池,垃圾填埋场的产量占30%,剩余的10%主要来源于工业废水处理厂和混合消化厂。一般情况下,沼气用作热源和发电,也可以作为汽车燃料。有机废物转化成沼气的同时还产生了消化残余物,可用作生物肥料。在瑞典有机废物填埋要课以重税,并且自2005年开始该国已严禁有机物的填埋处理,所以人们逐渐开始了对有机物混合消化的重视和研究。目前瑞典约有10家沼气厂利用厌氧消化处理收集来的各种有机废料,总处理能力>20×104t/a。多数沼气厂将牲畜粪便作为主要原料,再辅以其他… 相似文献
104.
105.
Yourong XU Deying WANG Qi JIN Yijian ZHOU Shanghai University of Science Technology Shanghai ChinaFan HU Chao LIU Iron Steel Research Institute of Baoshan Iron Steel Complex Shanghai China 《材料科学技术学报》1993,9(4):279-282
By means of electron probe(EPMA),scanning electron microscope(SEM),and optical microscope(QM),the diffusion behaviour on the Fe-Cu interface of copper brazed double-wall steel tubes andthe microstructure of the diffusion layer have been investigated.There are three kinds of metallurgicalbonds between copper plating layer and steel substrate: (1)the Cu diffusing into steel substratealong grain boundary of ferrite;(2)the Cu diffusion into grain bulk of ferrite: (3)the Fe diffusing intoCu layer.The copper brazed double-wall steel tubes are formed by the combination of the diffusionsmentioned above and this is the reason for excellent mechanical and technological properties of thecopper brazed double-wall steel tubes. 相似文献
106.
Gao Chao 《电子科学学刊(英文版)》2005,22(5):558-563
This letter puts forward a method of modeling for the steady-state and small signal dynamic analysis on PWM, quasi-resonant and series/(parallel) resonant switching converters based on pulse-waveform integral approach. As an example, PWM and quasi-resonant converters are used to discuss the principle of the approach. The results are compared with those in the relative literatures. Computer aided analysis are made to confirm the correctness. 相似文献
107.
An efficient approach for calculating the dispersions of photonic-crystal fibers: design of the nearly zero ultra-flattened dispersion 总被引:1,自引:0,他引:1
Tzong-Lin Wu Chia-Hsin Chao 《Lightwave Technology, Journal of》2005,23(6):2055-2061
A novel and efficient approach is proposed to calculate the dispersions of the guided modes of the photonic-crystal fibers (PCFs). Based on the vector boundary-element method (VBEM), the surface integral equations for the first and second derivatives of the propagation constants with respect to the wavelength are explicitly derived. Compared with the three-point finite-difference approach, which needs to solve and search three effective indexes near the interested wavelength, this approach can determine the dispersions of the PCFs by only solving one effective index at this wavelength based on the derived formulations. This novel approach saves over 60% computing time without losing the accuracy. Based on this approach, a novel four-ring PCF is designed by optimizing only three geometrical parameters to achieve the nearly zero ultra-flattened dispersion property. Compared with previously presented dispersion-flattened PCFs, the design procedure for the four-ring structure could be more efficient and easier because relatively lesser parameters need to be optimized. 相似文献
108.
109.
Heterogeneous precipitation method was used to prepared surface coating on self-made BaMgAl10O17:Eu phosphor. Results illustrate that the coating film can be silicon dioxide in amorphous state with 50 nm in thickness. Photoluminescence results indicate that the coating layer presents an observable improved effect on the enhancement of thermal stability. When baked at 600 ℃ for 1 h, the luminance of coated BAM keeps at 92% higher than that of uncoated BAM by 23%. This protective effect can be attributed to the high compact degree and uniformity of this amorphous SiO2 coating film which is served as a diffusion block layer to inbreak oxygen atom, thus releases the oxidation extent of Eu2 effectively. 相似文献
110.
Hexagonal AlN films have been obtained by arc ion plating at different negative biases ,X-ray diffraction and scanning electron microscopy results show that AlN films with smooth surfaces and (002) preferred orientation are obtained at low biases ,whereas those with coarse surfaces and (100) preferred orientation are obtained at high biases,The formation mechanism of AlN is analyzed and the experiment results are discussed,The effect of bias on adhesion strength has also been examined. 相似文献