Experimental Investigation of Water-Entry Phenomenon

In order to investigate the cavity shape and velocity attenuation of steel spheres after high-speed water entry, the high-speed water entry of different water entry angles were performed. The cavity shapes were recorded using high-speed photo recorder, and the velocities after water entry were measured. The diameters of equivalent disk of steel spheres after water entry were obtained from the processing of cavity images. Based on the steady and uncompressing flow assumption, a theoretical model for velocity attenuation of steel spheres with cavity was proposed and calculated results were in good agreement with the experimental results. The second cavity breaking off phenomenon, which has not been reported before, was discovered. The established theoretical model provides a reference for other relative researches.

Development of in-situ Marine Sediment Geo-Acoustic Measurement System with Real-Time and Multi Frequencies (the Second Generation)

Compared with the laboratory acoustic measurement of sediment samples, the in-situ acoustic measurement in marine sediment is considered more accurate and rehable, because it covers all of the surrounding environment factors and avoids the disturbance during the course of sampling and transporting of sediment samples. A new multi-frequency in-situ geoacoustic measurement system （MFIS^AMS） has been developed. The system can provide acoustic vdocity （compressional wave） and attenuation profiles of the uppermost 4 - 8 m sediment in the seafloor. It consists of 8 channels with 12 frequencies （multi-frequencies） and 0.5 - 2 MHz sampling rates. The data collected can be transmiuted in real-time. Associated with inclinometer and altimeter, it can provide the data for depth emendation. Acoustic velocity and attenuation data have been obtained from two in-situ experiments conducted in the Hangzhou Bay.

Research on propagation properties of elastic waves in two-phase anisotropic media

With the development of seismic engineering and seismic exploration of energy, the underground media that westudy are more and more complicated. Conventional anisotropy theory or two-phase isotropy theory is difficult todescribe anisotropic media containing fluid, such as fractures containing gas, shales containing water Based onBlot theory about two-phase anisotropy, with the use of elastic plane wave equations, we get Christoffel equations.We calculate and analyze the effects of frequency on phase velocity, attenuation, amplitude ratio and polarizationdirection of elastic waves of two-phase, transversely isotropic media. Results show that frequency affects slow Pwave the greatest among the four kinds of waves, i.e., fast P wave, slow P wave, fast S wave and slow S wave.Fluid phase amplitude to solid phase amplitude ratio of fast P wave, fast S wave and slow S wave approaches unitfor large dissipation coefficients. Polarization analysis shows that polarization direction of fluid phase displacement is different from, not parallel to or reverse to, that of solid phase displacement in two-phase anisotropic media.

Propagation of plane waves in poroviscoelastic anisotropic media

This study discusses wave propagation in perhaps the most general model of a poroelastic medium. The medium is considered as a viscoelastic, anisotropic and porous solid frame such that its pores of anisotropic permeability are filled with a viscous fluid. The anisotropy considered is of general type, and the attenuating waves in the medium are treated as the inhomogeneous waves. The complex slowness vector is resolved to define the phase velocity, homogeneous attenuation, inhomogeneous attenuation, and angle of attenuation for each of the four attenuating waves in the medium. A non-dimensional parameter measures the deviation of an inhomogeneous wave from its homogeneous version. An numerical model of a North-Sea sandstone is used to analyze the effects of the propagation direction, inhomogeneity parameter, frequency regime, anisotropy symmetry, anelasticity of the frame, and viscosity of the pore-fluid on the propagation characteristics of waves in such a medium.

Measurement errors of ultrasonic velocity and attenuation due to nonparallelness of specimen faces

The measurement errors due to nonparallelness of specimen faces in the ultrasonic velocity and attenuation coefficient measured by the pulse reflection method in VHF range have been investigated theoretically, and the theoretical expressions for estimating these measurement errors are given. It has also been shown that, the attenuation coefficient error is depending on both the nonparallelness angle of specimen faces and the ultrasonic frequency, but the velocity error is only depending on the former. Furthermore, for pure silica glass specimen it is estimated that, in VHF range in order to insure that the attenuation coefficient and velocity errors due to nonparallelness of specimen faces are less than 10% and 0.01%, respectively, the nonparallelness angle of specimen faces must be less than 10 s and 40 s correspondingly.

Improving mathematical model of burden distribution and correcting chute angle to cope with fluctuation of stock line

Accurate evaluations of the burden distribution are of critical importance to stabilize the operation of blast furnace.The mathematical model and discrete element method(DEM)are two attractive methods for predicting burden distribution.Based on DEM,the initial velocities of the pellet,sinter,and coke were calculated,and the velocity attenuations of the above three particles between the burden and the chute were analyzed.The initial velocity and velocity attenuation were applied to a mathematical model for improving the accuracy.Additionally,based on the improved model,a scheme for rectifying the chute angles was proposed to address the fluctuation of the stock line and maintain a stable burden distribution.The validity of the scheme was confirmed via a stable burden distribution under different stock lines.The mathematical model has been successfully applied to evaluate the online burden distribution and cope with the fluctuation of the stock line.