Spatial indexing technology is widely used in Geographic Information Systems (GIS) and spatial databases. As a data retrieval technology, spatial indexing is becoming increasingly important in the big-data age. The purpose of this study is to propose a unified indexing strategy for the mixed data of a future marine GIS. First, data organisation of the system is described. Second, the display condition of each type of data is introduced. These conditions are the basis for the construction of a unified indexing structure. Third, a unified indexing structure for mixed data is presented. The construction process and the search method of the indexing structure are described. Finally, we implement the indexing strategy in our system “Automotive Intelligent Chart Three-dimensional Electronic Chart Display and Information Systems” (AIC 3D ECDIS). Our strategy can provide fast and integrated data retrieval. The spatial indexing strategy we propose breaks through the limitation of data types in our system. It can also be applied in other GIS systems. With the advent of the big-data age, mixed data indexing will become more and more important.

In the present study, the surface properties and the corrosion behavior of a nanocrystalline surface layer fabricated on 45 steel by electropulsing-ultrasonic surface treatment (EUST) were investigated. EUST offered the specimen a smooth (R a < 0.33 µm) surface layer with nanoscale grains and compressive stress by the synergistic effect of high-energy electropulsing processing and ultrasonic impact. Open-circuit potential, potentiodynamic polarization, and electrochemical impedance spectroscopy studies indicated that EUST-induced surface nanocrystallization decreased the corrosion susceptibility of 45 steel in 3.5 wt% NaCl aqueous solution, leading to a decrease in corrosion current density (i corr) by 55% and an increase in charge transfer resistance (R ct) by 36%. The enhancement in surface comprehensive mechanical properties and corrosion resistance can be explained in terms of the decrease in surface roughness, the extent of grain refinement and the change of stress state, which were closely related to the introduction of high-energy electropulsing processing.

The effect of electropulsing assisted ultrasonic surface modification (EUSM) on microstructure and surface properties of S50C steel welded components is investigated. Compared with conventional ultrasonic surface modification (USM) process, EUSM process achieves significant improvements in microstructure, including deeper strengthened layers and gradient microstructure on the surface. The EUSM-induced microstructure results in higher levels of surface compressive residual stress and greater surface microhardness and its effective depth. Conventional USM process is inevitably accompanied by some plastic damages, such as pit and crack defects. The damages, however, can be eliminated to some extent during the EUSM process. These enhancements may be attributed to the thermal and athermal effects caused by electropulsing treatment, which accelerates the mobility of dislocations in the dynamic recrystallization process.

Electropulsing treatment (EPT) provided a promising technology to improve the microstructure and plasticity of the cold-rolled Ti–6Al–4V noticeably while only affecting the strength mildly. Thus, titanium alloy of high plasticity and good comprehensive property can be obtained by this high efficient processing method. The research found that the tensile ductility could be improved largely with the increasing frequency. In the low frequency, the maximum ductility (32.5%) could be obtained at 293 Hz-EPT. Under high-frequency EPT, plasticity has a slight decrease but the tensile strength increases in the contrary. With the help of multi-characterization, abstracting phenomena are explained and therefore the conclusion has been drawn that the whole process of increasing frequency EPT can be divided roughly into two periods: (a) recrystallization period in the low frequency, at this period athermal effect of the EPT played a leading role and (b) phase change period in the high frequency, at this period the other important factor of the EPT thermal effect was predominant. As a comparison, furnace heat treatment is conducted to prove the preferential phase transition instead of complete recrystallization under the single heating effect. The mechanism of the results can be discussed by the competitive mechanism of recrystallization process and phase change in the EPT processing.

Excimer laser ablation rates of Si (111) and AlN films grown on Si (111) and r-plane sapphire substrates were determined. Linear dependence of ablation rate of Si (111) substrate, sapphire and AlN thin films were observed. Excimer laser micromachining of the AlN thin films on silicon (111) and SiC substrates were micromachined to fabricate a waveguide structure and a pixilated structure. This technique resulted in clean precise machining of AlN with high aspect ratios and straight walls.

Excimer laser ablation rates of Si (111) and AlN films grown on Si (111) and r-plane sapphire substrates were determined. Linear dependence of ablation rate of Si (111) substrate, sapphire and AlN thin films were observed. Excimer laser micromachining of the AlN thin films on silicon (111) and SiC substrates were micromachined to fabricate a waveguide structure and a pixilated structure. This technique resulted in clean precise machining of AlN with high aspect ratios and straight walls.