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991.
E. K. Naumenko 《Journal of Applied Spectroscopy》1998,65(3):434-441
The spectral dependences of the optical characteristics governing radiation transfer in scattering media are analyzed within
the wavelength range of 0.4–14 μm for three types of aerosols. The wavelength ranges where approximate methods of calculation
of frequency-contrast characteristics are applicable are established; the corresponding limitting masses of aerosol particles
in a layer per unit of surface area are determined for which approximate methods provide acceptable accuracy.
B. I. Stepanov Institute of Physics, National Academy of Sciences of Belarus, 70 F. Skorina Ave., Minsk, 220072, Belarus.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 3, pp. 419–425 May–June, 1998. 相似文献
992.
S. V. Shlychkov 《Mechanics of Composite Materials》2007,43(3):269-276
The paper presents results of numerical and experimental investigations into the vibrations of thin-walled structures, considering
such their features as the complexity of geometry, the laminated structure of walls, the anisotropy of materials, the presence
of stiffeners, and the initial stresses. The object of the study is the sounding board of an acoustic guitar, the main structural
material of which is a three-layer birch veneer. Based on the finite-element method, a corresponding calculation model is
created, and the steady-state regimes of forced vibrations of the sounding board are investigated. A good correspondence between
calculation results and experimental data is found to exist.
__________
Translated from Mekhanika Kompozitnykh Materialov, Vol. 43, No. 3, pp. 399–410, May–June, 2007. 相似文献
993.
994.
The arbitrarily open trapezoidal-groove guide is analyzed with the conformal mapping technique. A new formula is given for
the evaluation of one fundamental parameter associated with the technique. The relationship between the cut-off wavelength
for the dominant mode and the geometry of the guide structure is studied; dispersion characteristic of the groove guide is
also given. Some numerical results are shown to be in good agreement with both experimental data and the results of the finite
element method (FEM). Moreover, it is testified that dispersion of the trapezoidal-groove guide is low. The obtained results
are significant for the design and application of the open trapezoidal-groove guide for millimeter waves. 相似文献
995.
I. N. Katz H. Mukai H. Schättler M. Zhang M. Xu 《Journal of Optimization Theory and Applications》2005,125(1):113-135
In this paper, we describe a zero-sum differential game formulation for the control of military air operations. The model consists of a system of nonlinear ordinary differential equations for the dynamics of the operations and a suitably chosen quadratic payoff function. The control variables are the engagement intensities and velocities, and there are constraints on the controls. The method of characteristics (based on the Pontryagin maximum principle) is used to solve the associated Hamilton-Jacobi equation. In this nonlinear formulation, the Hamiltonian can be optimized explicity with respect to the controls. Numerical simulations study the enforcement of constraints (a) by means of penalties in the payoff function or (b) explicitly. The numerical results show robustness with respect to various parameters.Effort sponsored by the Defense Advanced Research
Projects Agency (DARPA) and Air Force Research Laboratory, Air Force
Material Command, USAF, under Agreement F30602-99-2-0551. A shorter version of this paper appeared in the Proceedings of the 2001 American Control Conference, pp. 168--175, 2001. 相似文献
996.
In the framework of the specified‐time‐interval scheme, the accuracy of the characteristic method is greatly related to the form of the interpolation. The linear interpolation was commonly used to couple the characteristics method (LI method) in open channel flow computation. The LI method is easy to implement, but it leads to an inevitable smoothing of the solution. The characteristics method with the Hermite cubic interpolation (HP method, originally developed by Holly and Preissmann, 1977) was then proposed to largely reduce the error induced by the LI method. In this paper, the cubic‐spline interpolation on the space line or on the time line is employed to integrate with characteristics method (CS method) for unsteady flow computation in open channel. Two hypothetical examples, including gradually and rapidly varied flows, are used to examine the applicability of the CS method as compared with the LI method, the HP method, and the analytical solutions. The simulated results show that the CS method is comparable to the HP method and more accurate than the LI method. Without tackling the additional equations for spatial or temporal derivatives, the CS method is easier to implement and more efficient than the HP method. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
997.
CSP方案的中止规则[R] 总被引:5,自引:5,他引:0
本文引入中止概率的概念,讨论适用于各类连续抽样方案的中止规则[R]的统计特性。结果表明,规则[R]的添加不改变方案原有的基本统计特性,而且全面优于另一类已被广泛采用的规则[S]. 相似文献
998.
用庞加莱球法测量二阶偏振模色散 总被引:5,自引:2,他引:3
用庞加莱球法测量单模光纤中的二阶偏振模色散,并对二阶偏振模色散的各个分量的统计特性及其影响进行了分析。对75km的G.652普通单模光纤的二阶偏振模色散进行了测量,并对二阶偏振模色散的平行分量、垂直分量、偏振相关色散和消偏振项进行了详细的分析.得到了二阶偏振模色散随波长的分布情况、统计特性以及偏振主态随波长的变化情况。从统计结果可以得到.与偏振相关色散项相比,消偏振项在二阶偏振模色散中起主要作用。该研究对二阶偏振模色散的补偿有一定的指导意义。 相似文献
999.
本文把转移概率流向图和转移概率母函数的方法引入到对MIL-STD-1916中连续抽样方案的讨论中,给出了抽样方案的平均检出质量函数AOQ,抽查特性函数L(p)和平均检查比率函数AFI全部3项指标的理论推导,为进一步探讨带有停止检查的MIL-STD-1916中连续抽样方案及相应的动态检出质量提供了理论基础。 相似文献
1000.
将任意形状槽的连续轮廓近似用一系列相连的矩形阶梯近似,利用各阶梯面上导纳的匹配,以及槽与互作用区边界场的连续与匹配条件,获得了具有任意槽的矩形波导栅慢波结构的色散方程和耦合阻抗的表达式,并进行理论上的验证.加工制作了矩形槽波导栅模型,冷测表明理论值与测量值相吻合.分别求解几种特殊槽形矩形波导栅慢波结构的色散特性及耦合阻抗,其中,三角形结构的色散和耦合阻抗均最弱,而倒梯形结构色散最强,耦合阻抗最大.
关键词:
矩形波导栅
任意槽
色散特性
慢波结构 相似文献