The prototype of the hybrid projector has a size of 88 mm in outside diameter and 316 mm in length, with an underwater resonant frequency of 1.30 kHz, Q factor of 1.43 for -3 dB bandwidth, and transmitting voltage response level of 135.1 dB at the resonant frequency.
This paper analyses the kinematic characteristic of underwater EFP by using finite element analysis software ANSYS/LS-DYNA,and studies preliminarily the variation of the EFP′s velocity gradient and shape in water with time.
It is significant theoretically and practically to study the influence of the fluid characteristics on the underwater structural vibration and that of the fluid boundary conditions on the vibro-acoustic characteristics of underwater structures, because underwater vibro-acoustic characteristics differ greatly from air vibro-acoustic characteristics mainly due to the loading effect of the surrounding heavy fluid.
The nonlinear finite element numerical simulation software named ANSYS/LS-DYNA was adopted by dynamic simulation of blast and impact on shielding structure underwater, to analyze effects of different shielding structure to shockwave underwater.
The practice of the underwater blasting is rare in the former engineering and the blasting elements is too more such as drilling technique, water proof index, rock constitute, sea weather restrict the development of the underwater blasting.
This paper introduces a method which utilizes underwater robot carrying scan sonar and orient sonar to survey submerged structure of pier,The feasibility of the method has been verified the sruvey of Guangzhou Province Enping bridge pier.
The experimental results show that the method can compress the dynamic range of returned signals more than one order, restrain the laser backscattering largely, and haven′t influence too much on detecting laser returned signals from the underwater.
With the development of communication and digital signal processing ,remote control have entered into the appliing ages. Underwater,digital remote control system have developed rapidly along with the needing of ocean exploitation and weapon underwater. It will have the capacious using foreground in underwater communication remote measuring controlling of underwater aircraft.
Implementation of an OFDM underwater acoustic communication system on an underwater vehicle with multiprocessor structure
Aimed at the real-time processing requirement of the OFDM algorithm, an underwater acoustic communication system with real-time processing capability is carried out.
An improved hypothesis-feedback equalization algorithm for multicode direct-sequence spread-spectrum underwater communications
In underwater acoustic communication, because the available bandwidth of the channel is severely limited, the direct-sequence spread-spectrum scheme can only be realized at low bit rates.
However, in this case, due to the rapid time-variability of the underwater channel, and the influence of inter-symbol interference (ISI) and inter-channel interference (ICI), the conventional rake receiver may fail to function.