Dynamic calibration for multi-beam bathymetric system based on characteristic data processing
The geometric installation error of the multi-beam bathymetric system will affect measure accuracy of the depth and location, which must be faced and resolved in the engineering survey urgently. The most important three kinds of the installation error are roll error, pitch error and yaw error. Through quantitative analysis of impact of installation error to the measure result, a dynamic calibration method has been proposed in the paper. In the method, installation errors can be obtained by analyzing bathymetric result from the characteristic terrain seafloor and the errors will be used as the parameters to calibrate other bathymetric result. Validity of the method has been proved by processing the measure data from Songhua Lake test.
Shallow Water High Resolution Multi-Beam Echo Sounder
This paper presents a Shallow water High Resolution Multi-Beam Echo Sounder (SHMBES), which will be used widely in modern ocean exploration and underwater engineering. It is highly synthesized and developed on the basis of many new techniques such as theories of underwater acoustic and modern signal processing, Very Large Scale Integration (VLSI), DSP array processing, etc. It is mainly composed of sonar deck unit (including multi-channels receiver and A/D conversion, real-time digital signal processing system, host computer and interface, etc.) and sonar watertight housing (including transducer, signal generation and control phased transmitter, etc.), as well as real-time and postprocessing software. Five parts are discussed in the paper: Section I is system structure and technical specification. Section II is the theory analysis of split sub-array phase detection and multiple sub- array detection methods. In this section the improved multiple sub- array detection method is presented. Section III is precision evaluation experiment. Three sub-array configurations are chose to process the experimental data obtained at sea based on theoretical analysis. It has shown that, with optimized parameters, the multiple sub-array detection method not only realizes the wide coverage, but also improves the detection performance. Section IV lists Songhua Lake and Mogan Lake measurement results of underwater terrain. The instrument validity of hardware and software is tested by these lake experiments. Section V are the conclusions of the paper.
An anionic shell shields a cationic core allowing for uptake and release of polyelectrolytes within core-shell responsive microgels.
To realize carriers for drug delivery, cationic containers are required for anionic guests. Nevertheless, the toxicity of cationic carriers limits their practical use. In this study, we investigate a model system of polyampholyte N-isopropylacrylamide (NIPAM)-based microgels with a cationic core and an anionic shell to study whether the presence of a negative shell allows the cationic core to be shielded while still enabling the uptake and release of the anionic guest polyelectrolytes. These microgels are loaded with polystyrene sulfonate of different molecular weights to investigate the influence of their chain length on the uptake and release process. By means of small-angle neutron scattering, we evaluate the spatial distribution of polystyrene sulfonate within the microgels. The guest molecules are located in different parts of the core-shell microgels depending on their size. By combining these scattering results with UV-vis spectroscopy, electrophoretic mobility and potentiometric titrations we gain complementary results to investigate the uptake and release process of polyelectrolytes in polyampholyte core-shell microgels. Moreover, Brownian molecular dynamic simulations are performed to compare the experimental and theoretical results of this model. Our findings demonstrate that the presence of a shell still enables efficient uptake of guest molecules into the cationic core. These anionic guest molecules can be released through an anionic shell. Furthermore, the presence of a shell enhances the stability of the microgel-polyelectrolyte complexes with respect to the cationic precursor microgel alone.