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991.
Ioannis G. Tigelis Jean-Yves Raguin Zisis C. Ioannidis George P. Latsas Angelos J. Amditis 《International Journal of Infrared and Millimeter Waves》2008,29(4):432-442
The dispersion characteristics of a circular cylindrical waveguide with periodic surface corrugations consisting of rectangular
grooves with smoothing are examined using the Space Harmonic Method (SHM). The whole structure is divided into two regions,
one describing the propagation volume and one inside the grooves. In the first region, the Floquet theorem is applicable and
the field distribution is expressed as a summation of spatial Bloch components, whereas in the second one an appropriate Fourier
expansion of standing waves is used. Applying the boundary conditions an infinite system of equations is obtained, which is
solved numerically by truncation. Several cases are considered, including the limiting cases of a sinusoidal and a rectangular
corrugation profile, to check the accuracy of the method proposed as well as its dependence on the corrugation profile. Numerical
results are presented only for transverse magnetic modes, although the formalism can be easily extended to include all kinds
of waves that can in principle propagate in such a structure. 相似文献
992.
It is difficult to eliminate the effect of vessel walls and impurities in practical studies of boiling-up of strongly superheated
liquids. Therefore, some doubts are always cast upon validity of experiments and their agreement with the classical theory
of homogeneous stationary nucleation, impairing the verification of theoretical considerations. This paper reports main results
of the theory of homogeneous nucleation and presents formulas for calculating the work of formation of a critical nucleus
by an incline of the accessible superheating boundary on isobars and isotherms. Matching of experimental and theoretical values
of the work of formation was considered as the homogeneous boiling-up criterion. Calculations by isobars and isotherms were
made for some liquids. The theoretical values of the work of formation of a critical nucleus were 1.23–4.5 times higher than
the corresponding empirical values for all the liquids, i.e., they were much higher than the calculation error. Thus, boiling-up
of the studied liquids was not homogeneous and, hence, it did not correspond to the classical theory of nucleation.
The work was financially supported by the President of the Russian Federation (No. NSh-4429.2006.8) and the Russian Foundation
for Basic Research (Grant No. 07-08-00575-a). 相似文献
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基于元胞自动机对对向行人交通流进行仿真研究. 模型利用四个动态参数反映行人移动区域和其视野范围内的实际情况,从而决定行人的行为选择,行人可以根据自身周围的情况选择前进、后退、等待、左右移动、交换位置等行为. 仿真研究不同方向比例与不同系统规模的对向行人流的速度-密度、流量-密度关系. 研究结果表明,系统存在相位转换和临界密度,方向比例和系统规模对行人流的速度-密度、流量-密度关系曲线的形状和系统临界密度值有一定的影响.
关键词:
元胞自动机
对向行人流
动态参数
临界密度 相似文献
996.
以单环后向Rayleigh散射式光纤转动传感器原理为基础,提出了一种三环形腔并联Rayleigh后向散射式光纤转动传感器新结构.利用三个2×2单模光纤耦合器,建立了并联三环形腔Rayleigh后向散射式光纤转动传感器的理论模型,给出了用光时域反射计(OTDR)探测到的信号强度表达式.通过计算机仿真优化了参量,选择三环的长度分别为1 500 m、1 078 m和680 m.三个2×2光纤耦合器的耦合系数分别为95.23%、94.88%和95.26%构建了测试系统,对不同转速所探测到的后向Rayleigh散射信号进行测量,得到与理论相一致的实验结果.三环的采用,增加了测试的有效数据,使其更有利于识别,提高了测量转速的准确度. 相似文献
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Dr. Stuart J. Beardsworth 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(8):1698-1702
The ability to communicate is fundamental to life as we know it and the key to success in many cases is based on having good communication skills. Be it written, spoken, visual, auditory or otherwise, effective communication can open many doors to hidden knowledge that can benefit the world. Science as an entity, which itself stems from the Latin word Scientia, (Engl. “knowledge”), has a tradition of not being particularly well communicated, with long words, vast and confusing concepts, and information overloads. However, as good as communication between scientists has generally become, there is still room for improvement. This article hopes to inform and inspire scientists to lead by example, to educate and advise in the best ways that we can, not just for non-experts, but for the interest of everyone. 相似文献