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A theoretical approach is proposed to investigate blast-induced ground vibration by considering the body force. On the basis of the principle of momentum conservation at the wavefronts, we derived the reflected body waves along the ground surface and the interaction of the body wavefront and ground surface inducing the secondary surface wave that transfers outward onto the ground. Subsequently, the particle velocity on the ground surface was derived, and a parametric investigation was conducted with regard to the effects of horizontal distance from the blast source, embedded depth of the blast source, and material damping onto the ground vibration. Finally, the effect of gravity on the ground vibration was also investigated.

A micro-electromechanical system (MEMS) scanning mirror accelerates the raster scanning of optical-resolution photoacoustic microscopy (OR-PAM). However, the nonlinear tilt angular-voltage characteristic of a MEMS mirror introduces distortion into the maximum back-projection image. Moreover, the size of the airy disk, ultrasonic sensor properties, and thermal effects decrease the resolution. Thus, in this study, we proposed a spatial weight matrix (SWM) with a dimensionality reduction for image reconstruction. The three-layer SWM contains the invariable information of the system, which includes a spatial dependent distortion correction and 3D deconvolution. We employed an ordinal-valued Markov random field and the Harris Stephen algorithm, as well as a modified delay-and-sum method during a time reversal. The results from the experiments and a quantitative analysis demonstrate that images can be effectively reconstructed using an SWM; this is also true for severely distorted images. The index of the mutual information between the reference images and registered images was 70.33 times higher than the initial index, on average. Moreover, the peak signal-to-noise ratio was increased by 17.08% after 3D deconvolution. This accomplishment offers a practical approach to image reconstruction and a promising method to achieve a real-time distortion correction for MEMS-based OR-PAM.

Based on the Biot’s model for saturated porous media and functionally graded materials (FGMs), the isolation effect of saturated porous FG wave impeding block (WIB) on reducing vibration induced by a moving load in a saturated foundation is studied. The dynamic governing equations for saturated foundations under a moving load are obtained by using the coordinate transformation, and the expression of displacement and stress is derived based on the Fourier transform and the reverberation-ray matrix method. Via numerical examples, the isolation effect of saturated porous FG WIB under a moving load is analyzed. The results show that the saturated porous FG WIB can effectively reduce the vibration amplitude and has more advantages and effective under a moving load.