共查询到20条相似文献,搜索用时 78 毫秒
1.
将基于POD的降阶模型应用于风力机翼型的气动研究。首先应用CFD数值模拟得到一系列快照结果;应用基于本征正交分解(POD)的方法得到流场的一组基模态,认为对于所研究的问题,任一流场可以由这些基模态通过线性表达得到;对控制方程进行Galerkin投影,得到降阶模型,将离散求解N-S方程的问题转化为一组只有十几个自由度的常微分方程,从而减少计算时间,提高计算效率。并对二维翼型的绕流的定常和非定常问题进行了分析,计算结果表明,降阶模型可以较好地捕捉流动的特征,与直接CFD模拟相比计算精度相当,但大幅有效地提高了计算效率。 相似文献
2.
G. Busse 《Optics & Laser Technology》1980,12(3):149-154
Optoacoustic imaging is a new technique with unusual features. It allows not only optical imaging, but also imaging of thermal structures on and in the sample. With optical radiation, images are produced from sample depths exceeding the optical penetration depth by several orders of magnitude. The resolution of, at present, about 7μm reveals microscopic structures. With simple image processing techniques information can be obtained from certain sample layers, and background structure can be suppressed. 相似文献
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D. G. Han Y. G. Zeng H. Guo W. Chen H. Lu C. Huang 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,42(3):489-493
Driven by one upper level coupling field, a three-level
V-type atomic system with a pair of upper levels is studied. With
one strong coupling field and one weak probe field, it is found
that, due to the effects of the upper level coupling field, the
quantum coherence between the two upper levels can be induced, and
the absorption of the probing field is very sensitive to the
relative phase of the probe, the pumping and the upper level
coupling fields. With proper parameters, lasing without inversion
(LWI) can be realized. 相似文献
5.
The choice of a star product realization for non-commutative field theory can be regarded as a gauge choice in the space of all equivalent star products. With the goal of having a gauge invariant treatment, we develop tools, such as integration measures and covariant derivatives on this space. The covariant derivative can be expressed in terms of connections in the usual way giving rise to new degrees of freedom for non-commutative theories. 相似文献
6.
热线法可以测定气体热导率,以干燥空气为例进行了测量。实验中测量的物理量较多,人工处理数据比较繁琐,且容易出错,因此使用Matlab软件处理数据。把测量的实验数据输入Excel表格中,然后把Excel文件引入到Matlab软件中,运行相关程序后可以直接得到气体的热导率和测量的百分差,处理过程快捷精确。Matlab软件处理数据时,对部分实验数据进行了最小二乘法处理,可以由线性外推法求出ΔQ/Δt。 相似文献
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The weak field approximation of a model of de Sitter gauge theory of gravity is studied in two cases. Without torsion and spin current, the model cannot give the right non-relativistic approximation unless the density is a constant. With small torsion, a satisfactory Newtonian approximation can be obtained. 相似文献
9.
静态抑制荧光法和流动注射抑制荧光法测定微量甲醛的研究 总被引:6,自引:0,他引:6
利用甲醛在中性或弱酸性条件下对亚硫酸盐-邻苯二甲醛-铵盐体系具有抑制作用,建立了测定甲醛的静态抑制荧光法和流动注射抑制荧光法。研究了测定甲醛的最佳条件。在最佳条件下,静态抑制荧光法测定甲醛的线性范围为0.10~1.60 μg·mL-1, 检测限为0.046 μg·mL-1;流动注射抑制荧光法测定甲醛的线性范围为0.10~2.00 μg·mL-1,检测限为0.085 μg·mL-1。用于河水中甲醛测定,与乙酰丙酮分光光度法(GB13197—91)比较,误差分别为0.83%和1.25%。 相似文献
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E. V. Safonova R. A. Konchakov Yu. P. Mitrofanov N. P. Kobelev A. Yu. Vinogradov V. A. Khonik 《JETP Letters》2016,103(12):765-768
With the use of experimental data on the temperature dependence of the concentration of interstitial atoms, it has been shown within the interstitial theory that the premelting nonlinear increase in the heat capacity of aluminum can be caused by the intense generation of interstitial defects in a dumbbell configuration. 相似文献
12.
It is shown that strong coupling of Bose–Einstein condensates to an optical cavity can be realized experimentally. With an additional driven microwave field, we show that a highly nonlinear coupling among atoms in a Bose–Einstein condensate can be induced with the assistance of the cavity mode. With such interaction, we can investigate the generation of many body entangled states. In particularly, we show that multipartite entangled GHZ states can be obtained in such architecture with current available techniques. 相似文献
13.
Thomas-Fermi model can be applied to describe state of electrons for mixtures. A method to solve the mixture Thomas-Fermi equation is proposed. With the proper initial test solution and step length, this method searches the solution in a way that reduces the steps by half, which can get solutions with various densities and temperatures fast. 相似文献
14.
光学综合孔径成像中的傅里叶相位研究 总被引:7,自引:5,他引:2
傅里叶相位是光学综合孔径成像的重要信息,观测目标的傅里叶相位包含于干涉条纹中。从像平面干涉条纹形成原理出发,推导出大气扰动、星光方向与基线方向不垂直和望远镜系统机械误差等因素是影响干涉条纹初始相位的主要因素。利用条纹原点值和峰值位移从条纹中提取初始相位,采用闭合相位法从条纹初始相位中去除其它因素的影响,从而最终获取目标傅里叶相位:结合计算机模拟对噪声给条纹峰值位置的影响进行分析,模拟结果表明在频域中对条纹能量谱进行阈值处理有较好的去噪效果。最后结合目标重构迭代法阐述了闭合相位在像重构中的作用。 相似文献
15.
Daniel R. Boone 《Journal of voice》1997,11(2):161-164
With years of training and performance, the mature vocal performer experiences less vocal changes with aging than does his/her age peer who is not a performer. We have considered, some physical problems that may adversely influence the voice of the older performer. With some awareness and effective management of these possible problems, the negative effects on the older performer's voice can be minimized. 相似文献
16.
The difference of Grassmanian even-odd and degree even-odd of (super-) conformal ghosts is stressed. With some modifications in the BRST charges and the commutation relations, it can be shown that the first quantization of RNS strings allows the BRST cohomology analysis. 相似文献
17.
在真空环境中,利用传输线测量装置,开展微波等离子体喷流对反射电磁波衰减的实验研究.实验结果表明,采用传输线测量方法能够有效地获得等离子体对反射电磁波的衰减;在5GHz附近,以氩气为工质,流量为52.5mg/s时,52W微波功率在真空环境中产生的等离子体喷流能对反射电磁波产生最大的衰减;增加微波功率、降低真空环境压强可以提高等离子体对反射电磁波的衰减;要使等离子体能够对反射电磁波产生最大的衰减,必须选取合适的发生器参数.
关键词:
电磁波在等离子体中的传输
等离子体基本过程
电磁波 相似文献
18.
L. C. Wang J. Shen X. X. Yi 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,56(3):435-440
We study the effect of feedback control on the entanglement evolution of two spins
in a dissipative cavity governed by the Lindblad master equation.
By numerically solving the master equation, we show that the
entanglement can be controlled by the feedback
based on the quantum jumps of the field in a leaking cavity.
With the feedback added to the spins,
the stable states with high degree of entanglement
can be obtained in absence of the spontaneous decay of the spins,
and the entanglement can also be generated for a period
in presence of spontaneous decay of the spins.
All the controlled entangled states are closely related to the initial states. 相似文献
19.
Xiang-fei Chen Sai Hu Yi Luo 《International Journal of Infrared and Millimeter Waves》2000,21(6):939-944
There are multiple passbands in a chirped Bragg grating based on acousto-optic superlattice. The structure can be regarded as an acousto-induced super Moiré grating (AI-SMG). The analysis shows that the passbands of the AI-SMG are produced by several pairs of neighboring chirped gratings. With suitable structure parameters selected, the passbands can be non-larenzian-shape, narrow flat-top, with ripple less than 0.5dB and steep slope. The devices can be used as tunable narrow-band multichannel transmission filters. This analysis is useful for the designs and applications of the devices. 相似文献