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991.
The various oblique shock wave reflection patterns generated by a moving incident shock on a planar wedge using an ideal quantum
gas model are numerically studied using a novel high resolution quantum kinetic flux splitting scheme. With different incident
shock Mach numbers and wedge angles as flow parameters, four different types of reflection patterns, namely, the regular reflection,
simple Mach reflection, complex Mach reflection and the double Mach reflection as in the classical gas can be classified and
observed. Both Bose–Einstein and Fermi–Dirac gases are considered.
相似文献
992.
This paper presents the development of a code, called GEBTAero, dedicated to very flexible aircraft (VFA) aeroelasticity and especially the evaluation of aeroelastic tailoring effect on critical speeds. GEBTAero is an open source code consisting in a tightly coupling between a geometrically exact beam theory -and a finite state induced flow unsteady aerodynamic model, including an homogenisation tool. This model has been implemented in Fortran using GEBT code and optimised open source libraries with particular focus on computation speed. Besides a non linear transient dynamic simulation capacity, a particular focus is put on the fast critical speed computation strategy using a non-iterative modal approach about the geometrically non linear deformed shape of the wing with the computation of only a few aeroelastic modes. Computation speed and accuracy of this implementation is assessed using widely used aeroelastic test cases and compared successfully to other aeroelastic codes. Configurations using aeroelastic tailoring, which are the core target of this solver, are then evaluated numerically on a representative high aspect ratio anisotropic composite wing and a simple 2-ply composite laminates with both variable ply orientations. It illustrates the strong correlation between the structural bending/twisting coupling of an unbalanced composite laminates and its critical aeroelastic speed. It also shows the high sensitivity of ply orientation on the aeroelastic behaviour. 相似文献
993.
目前直接电光取样技术是在片检测砷化镓高速集成电路内部动态特性的最好方法。我们建立了半导体激光器电光取样系统,测试了梳状信号发生器输出的43.7ps的电脉冲信号以及频率5GHz的微波信号,并测试了频率3GHz的微波信号的位相移动或时间延迟以及铁氧体微波移相器的静态特性曲线,这个系统将被应用于砷化镓高速集成电路内部动态特性在片检测。 相似文献
994.
Koji Yamada Noboru Miura Chihiro Hamaguchi Norihiko Kamata 《Solid-state electronics》1989,32(12):1113-1117
Hot carrier magnetophonon resonances of n-type Si, short channel InP and p-type InSb were investigated in pulsed high magnetic fields up to 40 T. Using a recently developed high resolution technique in pulsed high fields, many new features of the hot carrier-phonon interactions in high magnetic fields were found. 相似文献
995.
富溪双连拱隧道出口高边坡岩体风化、卸荷严重,在施工开挖前边坡中上部已经发生较为明显的倾倒变形,整个变形体处于极限平衡状态。本文在现场调查和岩体结构分析基础上,建立了边坡变形破坏机理的概念模型,利用FLAC3D模拟研究了开挖后坡体变形特征。在变形分析基础上,提出了对倾倒变形体采用锚管注浆处理的边坡治理措施,支护效果模拟计算表明,注浆后边坡稳定性较好,同时监测资料也显示支护措施实施后,边坡的稳定性较好,可以保障公路的施工和长期营运的安全。 相似文献
996.
997.
In this paper, we investigate theoretically and experimentally dynamics of a buckled beam under high-frequency excitation.
It is theoretically predicted from linear analysis that the high-frequency excitation shifts the pitchfork bifurcation point
and increases the buckling force. The shifting amount increases as the excitation amplitude or frequency increases. Namely,
under the compressive force exceeding the buckling one, high-frequency excitation can stabilize the beam to the straight position.
Some experiments are performed to investigate effects of the high-frequency excitation on the buckled beam. The dependency
of the buckling force on the amounts of excitation amplitude and frequency is compared with theoretical results. The transient
state is observed in which the beam is recovered from the buckled position to the straight position due to the excitation.
Furthermore, the bifurcation diagrams are measured in the cases with and without high-frequency excitation. It is experimentally
clarified that the high-frequency excitation changes the nonlinear property of the bifurcation from supercritical pitchfork
bifurcation to subcritical pitchfork bifurcation and then the stable steady state of the beam exhibits hysteresis as the compressive
force is reversed.
This work was partially supported by the Japanese Ministry of Education, Culture, Sports, Science, and Technology, under Grants-in-Aid
for Scientific Research 16560377. 相似文献
998.
Pressure drop and cut size measurements are reported for a full scale cyclone operating within a 58 MWth CFB-combustor unit at 775℃.The paper reviews the vast number of equations to calculate the pressure drop and separation efficiency of cyclones, generally for operation at ambient temperature and at low Cs[0.5]. None of the literature correlations predicts the pressure drop with a fair accuracy within the range of experimental operating conditions. The cut size d50 can be estimated using direct empirical methods or using the Stokes number, Stk50. Both methods were used to compare measured and predicted values of d50. With the exception of Muschelknautz and Krambrock, none of the equations made accurate predictions.Finally, an alternative method to determine the friction factor of the pressure drop equation (Euler number, Eu) and of the cut size is proposed. The Eu number is determined from the geometry of common cyclones, and the derived value of Stk50 defines more accurate cut sizes. The remaining discrepancy of less than 5%, when compared with the measured values, is tentatively explained in terms of a reduced cyclone diameter due to the solids layer formed near its wall. Further measurements, mostly using positron emission particle tracking, elucidate the particle motion in the cyclone and both tracking results and the influence of the particle movement on Eu and Stk50 will be discussed in a follow-up paper. 相似文献
999.
1000.