The motion characteristic of cavitation bubble is one of the major factors affecting acoustic cavitation. In this paper, a cavitation model coupled with acoustic pressure is established using lattice Boltzmann pseudopotential model. Aimed at demonstrating the feasibility of applying LB method in acoustic cavitation, the acoustic cavitation simulations are compared with the predictions of Keller equation. The comparison of theoretical prediction and numerical simulation shows that LB method is suitable for acoustic cavitation simulation.
This paper reports on a study of the propagation characteristics of visco-elastic, Rayleigh-like waves in stratified half-space structures. Beginning with the Kelvin model, the characterization equation and the normal displacement of visco-elastic Rayleigh waves in stratified half-space structures are derived and the influence of the visco-elastic modulus on dispersion and attenuation is discussed. Theoretical calculations show that the attenuation-frequency curves perfectly match the phase-frequency curves. The effect of visco-elasticity on the attenuation of the Rayleigh-like wave is larger than its effect on dispersion. For "weak viscosity," the attenuation is directly proportional to the viscosity modulus and the shear viscosity has a greater impact on the dispersion curves than does the bulk viscosity. The transient response of a visco-elastic Rayleigh wave is also simulated by means of Laplace and Hankel inversion transforms. The results are in good agreement with the theoretic predictions. It is believed the paper's results and conclusions will provide insights and guidance for estimating visco-elastic parameters and for assessing adhesive quality.
In the new era, reform of the audit management of Official Audit Organs need systems thinking. This paper focus on the guidance and supervision of internal audit, which is the important content of the audit management system. Through the analysis of the present situation from various perspectives, aiming at the outstanding problems that still need to be paid attention to under the new situation. It explores a feasible way to coordinate the development of internal audit guidance and internal audit institutions, and tries to exemplify the application section on the basis of empirical analysis. To quantify the relevance between internal audit guidance and internal audit institutions through scientific method, introducing Principal Component Analysis and Monte Carlo Method, also provides some reference ideas for practical application.
In order to distinguish underwater targets, the method of target depth resolution urgently need to be developed. Matched field processing (MFP) is a passive detection method and it can be used to distinguish two targets at different depth. In this paper single vertical array MFP simulation has been done for targets depth resolution while they have same distance and azimuth in ocean acoustic field and the results show that the resolution is basically correspond to theoretical value.
In wireless sensor networks (WSNs), wireless links are unreliable and sensor nodes may be in sleep mode. Thus, many applications which require reliable broadcast cannot work properly if they lost some packets. In order to make sure every sensor node in the network receives all packets completely and correctly, retransmission of lost packets is indispensable. Many retransmission methods with network coding have been proposed but they do not catch coding opportunity. In this paper, real-time retransmission algorithm based on network coding (NCRR) is proposed to make the average number of transmissions as less as possible. During the transmission of original packets, we detect whether a certain time slot is suitable for retransmitting a coded packet based on recovery ratio. We analyze the number of transmissions with traditional retransmission and with network coding. Compared with existing approaches, simulation results show that our algorithm can effectively reduce the average number of transmissions and improve the transmission efficiency.
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