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91.
From the principle of of the Domain Decomposition Method (DDM), we analyse the 2nd-order linear elliptic partial differential problems and link the Separated-Layers Algorithm (SLA) with DDM. The mathematical properties of SLA and numerical example are presented to obtain satisfactory computation results. For general linear differential ones, also are the structure of SLA and its characteristics discussed. 相似文献
92.
电容器介质吸收电流的测量和表征 总被引:6,自引:0,他引:6
在外电场作用下,电容器介质的吸收电流和漏电电流混杂而难以分开,但外电场除去后吸收电流对电容器放电总电荷所贡献的百分比具有确定值,吸收电流的释放遵从自由弛豫规律。可用响应时间r’表征。实验给出了一些常见介质的吸收电流表征参数。 相似文献
93.
用瞬态频率波动法诊断齿轮故障 总被引:4,自引:0,他引:4
利用瞬态频率波动法实现频率调制信号的解调,提取齿轮的局部裂纹信息,并通过黄河TN252型汽车变速器疲劳试验的信号分析来验证。 相似文献
94.
裂纹梁动态响应有限元分析中的线弹簧模型 总被引:5,自引:1,他引:4
本文提出了一种以线弹簧模型为基础来分析裂纹梁动态响应的新数值方法.应用能量原理和断裂力学理论首次建立了线弹簧模型的刚度矩阵,从而确立了一种能使二维裂纹问题转化为一维分析的梁的有限元模型.使用这个模型,研究了不同裂纹长度和裂纹位置对悬臂梁固有频率和振型的影响,并把计算所得到的数值结果与现有的实验数据作了比较.结果表明,当无量纲裂纹长度小于0.6时,两者吻合得非常好;反之,两者之间存在较大的误差.对这种误差产生的原因,本文也作了解释. 相似文献
95.
UV-Vis spectroscopy was used to directly determine the concentration of Eu(Ⅱ) during electroreduction of Eu(Ⅲ) in hydrochloric acid medium. Electroreduction was carried out in a flow type electrolyzer with glassy carbon cathode at the constant potential of -800 mV vs. Ag/AgCl. The effects of oxygen and concentration of hydrochloric acid on the system were investigated. For 0.01 mol·L-1 hydrochloric acid, calibration curves for Eu(Ⅱ) absorption bands at 248 and 320 nm were constructed. Molar absorption coefficients were estimated to be 2016 and 648 L·mol-1·cm-1, respectively. The absorbance strongly decreased with decrease in pH of the solution, whereas concentration of chloride had only a negligible effect. 相似文献
96.
In this note the stability of a second-order quasi-polynomial with a single delay is studied. Although there is a vast literature on this problem, most available solutions are limited to some particular cases. Moreover, some published results on this subject appear to contain imprecise, or even wrong, conditions. The purpose of this note is to show that by accurate application of known theories, a complete explicit characterization of stability regions can be derived in a most general case. As a byproduct of the proposed analysis, we show that in the high-order case the quasi-polynomial is delay-independent unstable whenever its delay-free version has an odd number of unstable roots (or, equivalently, a negative static gain). 相似文献
97.
研制成用LD泵浦的声光调Q的Nd:YVO4-KTP腔内倍频激光器,得到了TEM00模、频率高达100kHz的稳定的532um绿激光脉冲系列输出,阈值泵浦功率为27mW;在连续570mW的泵浦功率下,绿激光脉冲的峰值功率达1100W,脉宽为4.6us;输出功率稳定,在±5℃的工作温度变化下,输出功率变化小于±2%。此种器件可望得到广泛的应用。 相似文献
98.
W. Whaling W. H. C. Anderson M. T. Carle J. W. Brault H. A. Zarem 《Journal of research of the National Institute of Standards and Technology》2002,107(2):149-169
We report precision measurements by Fourier transform spectroscopy of the vacuum wavenumber, line width, and relative signal strength of 928 lines in the Ar I spectrum. Wavelength in air and classification of the transition are supplied for each line. A comparison of our results with other precision measurements illustrates the sensitivity of Ar I wavelengths to conditions in the light source. 相似文献
99.
Building a knowledge-based system is like developing a scientific theory. Although a knowledge base does not constitute a theory of some natural phenomenon, it does represent a theory of how a class of professionals approaches an application task. As when scientists develop a natural theory, builders of expert systems first must formulate a model of the behavior that they wish to understand and then must corroborate and extend that model with the aid of specific examples. Thus there are two interrelated phases of knowledge-base construction: (1) model building and (2) model extension. Computer-based tools can assist developers with both phases of the knowledge-acquisition process. Workers in the area of knowledge acquisition have developed computer-based tools that emphasize either the building of new models or the extension of existing models. The PROTÉGÉ knowledge-acquisition system addresses these two activities individually and facilitates the construction of expert systems when the same general model can be applied to a variety of application tasks. 相似文献
100.
R K Mandal Ch. Durga Prasad O M Parkash Devendra Kumar 《Bulletin of Materials Science》1987,9(4):255-262
Glasses with varying molar ratios of PbO/BaO in the system BaO-PbO-TiO2-B2O3-SiO2 were prepared keeping (BaO + PbO)/TiO2 ratio equal to one. The glasses were ceramized by two-stage heat treatment. X-ray diffraction indicates that PbTiO3 crystallizes in lead-rich glasses while BaTiO3 precipitates in barium-rich compositions. Solid solution (Ba, Pb)TiO3 does not seem to crystallize over the entire range of compositions. Simultaneous presence of PbO and BaO in the initial glass
composition reduces the yield of ferroelectric phase. Dielectric properties have been interpreted in terms of microstructural
features. 相似文献