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21.
A novel and accurate method is proposed to extract the intrinsic elements of the GaN high-electron-mobility transistor(HEMT) switch.The new extraction method is verified by comparing the simulated S-parameters with the measured data over the 5-40 GHz frequency range.The percentage errors E_(ij) within 3.83% show the great agreement between the simulated S-parameters and the measured data. 相似文献
22.
用Matlab软件对麦克斯韦速度及速率分布函数进行了编程,绘制了相应的分布曲线,讨论了不同温度和不同分子质量时麦克斯韦速率分布曲线的变化,并用Matlab的符号计算功能计算了分布在三个典型速率区间的分子数占总分子数的百分比,所有变化规律均符合热学理论中的分子运动规律,为教学提供了参考。 相似文献
23.
The present paper investigates the tensile properties of post-irradiation annealed Cu–Ni alloy. The specimens were irradiated with a 15 MeV electron beam at room temperature and the post-irradiation annealing (PIA) of the specimens was carried out under vacuum at 450 °C for 15–120 min. The yield stress (YS), ultimate tensile stress (UTS), percentage elongation, stress relaxation rate and activation volume of both as-irradiated and post-irradiation annealed specimens were examined at room temperature using a universal testing machine. The results show that PIA of the specimen at 450 °C for 15 min decreases its YS and UTS, whereas the percentage elongation is increased. The changes in the tensile parameters become more pronounced with increases in annealing time. Effects of PIA on the stress relaxation rate and activation volume indicate that the relaxation rate of post-irradiation annealed specimens increases, and the activation volume decreases, with an increase in annealing time. 相似文献
24.
高密度钢纤维混凝土疲劳裂纹扩展的分形描述 总被引:3,自引:0,他引:3
在对局部高密度钢纤维混凝土疲劳裂纹扩展规律的研究中发现,裂纹并非是由一条主裂纹循序渐进地发展,而是随着循环次数的增加,呈多条短裂纹陆续出现,弥散式发展的趋势;纤维掺量越大,临近破坏前试表面裂纹越密集、弯曲、本阐述了用分形语言描述表面裂纹演化的必要性并且探讨了描述方法,借助分形语言对试验结果分析后发现,纤维混凝土裂纹失稳扩展前的临界分维值Dc随着纤维掺量的增加而增加。 相似文献
25.
Ebtesam M. Al-Olayan 《Journal of Saudi Chemical Society》2013,17(1):97-100
The virulence of five fungal strains, Acremonium cephalosporium, Aspergillus niger, Penicillium chrysogenum, Trichoderma viride, and Verticillum albo-atrum by application of 108 conidia mL?1 to larvae and adults of house flies, Musca domestica was determined. A. niger produced the highest percentage of mortality to larvae, 85.1 ± 1.60, and adults, 98.2 ± 3.10, of house flies. Topical application of the fungal strains to larvae showed concentration-dependent response and caused mortality ranged between 41% and 83% with LT50 values varying between 5.22 and 7.81 days. The highest percentage of mortality, 83.9 ± 3.52, was produced by 107 conidia mL?1 of A. niger with LT50 5.22. The lowest mortality percentage, 41.2 ± 3.00 with LT50 7.81, was produced by 105 conidia mL?1 of V. alboatrum. On the other hand, the highest percentage of mortality to adults of house flies, 97.3 ± 3.52, was produced by 107 conidia mL?1 of A. niger with LT50 3.49. While the lowest mortality percentage, 59.1 ± 2.38 with LT50 6.91, was produced by 105 conidia mL?1 of V. albo-atrum. 相似文献
26.
为研究影响再生混凝土力学性能的因素,将建筑结构中使用最为广泛的C30与C40两种强度等级的废混凝土破碎成再生粗骨料RCA(recycled coarse aggregate),根据实测RCA吸水率调整了配合比。以RCA来源和RCA取代率为变量,设计了9组再生混凝土试件,进行立方体抗压强度及棱柱体单轴受压试验。基于试验数据,得到了两种不同来源RCA的再生混凝土弹性模量、峰值应变等重要力学性能参数,绘制了再生混凝土应力-应变曲线。结果表明,随着RCA取代率的增加,两种不同来源RCA再生混凝土弹性模量和立方体抗压强度均表现为下降,RCA强度对再生混凝土各项力学性能均有影响。 相似文献
27.
L. D. Kock M. D. S. Lekgoathi E. Snyders J. B. Wagener J. T. Nel J. L. Havenga 《Journal of Raman spectroscopy : JRS》2012,43(6):769-773
Raman spectroscopy and multivariate calibration techniques are used to determine the percentage conversion of zircon (ZrSiO4) to plasma‐dissociated zircon, ZrO2.SiO2 (PDZ). The integrated area of a consistent ZrO2 (monoclinic) Raman band at 477 cm–1 assigned to the Ag symmetry type from different conversion percentages of the PDZ spectra is used in a multivariate analysis scheme (partial least squares) to develop a predictive model for the subsequent determination of percentage dissociation of zircon to PDZ. In contrast to wet chemical methods, this approach eliminates the use of corrosive acids, e.g. hydrofluoric acid, thus leading to significant reductions in analysis time and material wastage, and it is a quick method that can be used online in a PDZ production facility. These results show best correlation with determination coefficient (R2) values in the range between 99.45 and 99.99% for zircon percentage dissociation in cross‐validation tests. This illustrates not only the versatility of the Raman technique in industrial applications but also the importance of noninvasive testing in the study of zircon and related materials. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
28.
29.
PEI Liang YAO Bing-hua WANG Li-ming MA Zhan-ying . Faculty of Water Resources Hydraulic Power Xi’an University of Technology Xi’an P. R. China . Key Laboratory of Water Cycle Related L Surface Processes Institute of Geographic Sciences Natural Resource Research Chinese Academy of Sciences Beijing 《高等学校化学研究》2011,27(1):132-139
The transport of Tb(III) in dispersion supported liquid membrane(DSLM) with polyvinylidene fluoride membrane(PVDF) as the support and dispersion solution including HCl solution as the stripping solution and di(2-ethylhexyl) phosphoric acid(D2EHPA) dissolved in kerosene as the membrane solution, has been studied. The effects of pH value, initial concentration of Tb(III) and different ionic strength in the feed phase, volume ratio of membrane solution to stripping solution, concentration of HCl solution, conc... 相似文献
30.
1. IntroductionA Kolmogorov-Smirnov type test for linearity in autoregressive models has been con-sidered by An and Chengl']. They showed that the asymptotic null di8tribution of the teststati8tic is related to the supremum of the 8tandard Brownian motion. Their simulationshowed that the test was easy to conduct and more powerful than the tests of Hinich[2],Keenanl3j, Tasyl4] and Chan and TOngl5]. However, the percentage points of the null dis-tribution of the test have not been tabulated… 相似文献