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Calculation of Vibrational Relaxation Times in Multi-component Excitable Gases
Ke-Sheng Zhang,Weihua Ou,Xueqin Jiang,Fei Long,Mingzhe Hu 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.65 No.7
In the research field of acoustic propagation in excitable gases, one of the most critical parametersis the vibrational relaxation time, which determines the frequency of the acoustic dispersion stepor the absorption maximum. In this paper, the vibrational relaxation equations given by Tanczos[J. Chem. Phys. 25, 439 (1956)] have been applied to calculate the vibrational multi-relaxationtimes in multi-component gases. The eigenvalues of the energy-transition-rate matrix are provento be the reciprocals of the multi-relaxation times. Comparisons demonstrate that our relaxationfrequencies calculated for various gas compositions, including carbon dioxide, methane, chlorine,nitrogen, and oxygen, agree with the experimental data.
Performance analysis of two-dimensional DOA estimation for uniform circular array
Chen Liupeng,Mou Weihua,Lv Zhicheng,Zhang Yonghu,Hu Lizhi,Ou Gang 한국통신학회 2023 ICT Express Vol.9 No.5
Perturbation analysis of direction of arrival (DOA) estimation has been studied mostly on one-dimensional arrays rather than planar arrays, which remains room for exploration. For uniform circular arrays with various model errors, we establish the corresponding system model. Then a performance analysis of the two-dimensional MUSIC algorithm is proposed by first-order error analysis and verified by simulation. The results show that the root-mean-squared error of DOA estimation is proportional to the standard deviation of the model errors, including gain-phase errors, sensor position errors, and mutual coupling effect.