In order to figure out how changes in equipment and environment impact the imaging result and find out a best imaging condition, in this paper, microbubbles with micron diameter is detected and imaged through a simulated supercavity layer in laboratory. After the image processing, the result shows the changes in distance of bubble region affect the imaging little. When the detection angle is 90 degrees, the bubbles have the clearest imaging. And the growth of bubble number in imaging is increasing with current and reaching saturation at a constant value, and the smaller the diameter of bubble is, the higher sensitivity towards current has.
In this paper, we investigate adaptive resource allocation strategy for downlink multi-input-multi-output (MIMO) orthogonal frequency division multiplexing (OFDM) system. We design a transmit scheme as a concatenation of dynamic sub-carriers and bit assignment, adaptive modulation and beam-forming. Our adaptive goal is margin adaptive optimization, which minimize the total transmission power subject to a target BER performance constraint on each sub-carrier, while meeting a constant bit rate. By use of Rayleigh fading model assumption, we introduce a new concept: the channel feedback coefficient, so as to compensate the error inducted by feedback channel. Simulation results show that the proposed resource allocation scheme outperforms the multi-user MIMO-OFDM with static allocation technique, and can lessen the performance loss caused by channel state information feedback error.