Applied Mechanics and Materials Vols. 405-408

Abstract: Multibeam sounding system can be used for the acquisition of high-precision digital seabed terrain model, it brings new opportunities for the development of 3D marine GIS (Geographic Information System). But its massive point cloud data poses great challenge for its storage and visualization. This paper proposes a new storage strategy and gives an optimized visualization method specifically for the storage strategy. First, we take advantage of the point cloud coordinates regularity to sort these points according to certain rules and efficiently organize it through multiple spatial index. Vertically, a multi-level pyramid index is established. We generate a number of levels data with different level of detail and different scale, namely the static level of detail (LOD) model, in this way, a trade-off between appropriate redundant storage space and efficient data retrieve is achieved. Horizontally, for all levels of the pyramid model, we establish a tiled quadtree index, and generate a cache image for each tile. Secondly, an optimized visualization method in accordance with the storage strategy is also designed. Based on the current area of interest and data dispatch algorithm, we calculate the corresponding tile location and directly load the cache image to lessen the workload of complex spatial data operation, reduce the rendering burden of spatial data. We can generate customized dynamic cache with specific area of interest and scale, to improve the visual effect, too.

Abstract: Article takes the tourist information service system based on 2D&3D intergration as an example, and shows the development method and process of WebGIS system based on the combination of the 2D GIS and 3D GIS; and emphasis on the data import, coordinate setting, format conversion, etc in the process of building 3D model.

Abstract: With the rapid development of tidal flat reclamation and construction of port in the Marine East of Jiangsu project, Xiaomiaohong creek nearby Lvsi port located at radial sand ridges sea area was selected as a typical area for understanding its topographic and morphological evolution, which is conductive to the construction of port. By using the Remote Sensing Axis Line method (RSAL), the Axis lines of Xiaomiaohong creek were extracted based on one MSS image and six TM images in the period of 1979, 1987, 1989, 1993, 1995, 2003 and 2009. The results showed that: (1) on the basis of overlaying generated axis line and DEM (digital elevation model) data both acquired in 2003, axis line can be the substitution of the thalweg line because of similar trend and minor deviation of above two kinds of lines, which is revealed that RSAL was serviceable and effective to understand dynamic evolution of tidal creeks quickly and accurately; (2) deviation between axis line and thalweg line is inevitable because of the slopes of both side is asymmetric. The biased distance depended on the slope degree of creeks. The much larger slope degree is, the further distance is shifted; (3) from 1979 to 2009, the front end of Xiaomiaohong creek were growing and its subordinate branches were eroding. Some new subordinate branches were turned out and developed in southern part caused by the strong hydrodynamic condition. Based on the comparison, the entire tidal creek was relatively stable.

Abstract: GIS application in petroleum industry is more and more attention, moving from ordinary data management into in-depth geographical analyses. The article briefly introduces the situation several previous studies about GIS applications in oil field ground construction, production forecast and management, geological thematic mapping, reservoirs modeling, ect. Propose the direction and trend of GIS applications in oil industry in the future.

Abstract: In this paper, based on the analysis of two types of semantic similarity algorithm: the concept of the amount of information algorithm and the concept of distance method, combined with geographic information services matching their own characteristics, one for geographic information services matching semantic similarity algorithm in enhance distinguishing ability of geographic information services at the same time, a substantial increase in the efficiency of service matching. The prototype system experiments prove the feasibility and effectiveness of the algorithm.

Abstract: In order to show the calculated results from numerical model of tidal current easily, the Mapinfo software may be help for the graphics display as its outstanding function, and its relation database also storages and manages the mass data from numerical model expediently. GIS technology would be applied by a square cell in map, and the combined application is discussed in the stage of modeling, computation and demonstration, including the original data in AutoCad document, computed data in numerical mode and graphic data in the table sheet of Mapinfo software. This method is tested in Shizi Yang channel, and the model results can be shown and inquired, which can improve the efficiency of mathematic model in modeling, debugging and after-managing.

Abstract: There were some reasons which cause the concrete cracks in monolithic concrete bed construction of high-speed railway. In this paper, combined with the specific situation of monolithic concrete bed construction of high-speed railway in northwest area of China, the states and causes of two kinds of cracks in monolithic concrete bed of high-speed railway were analyzed, the concrete cracking control measures were discussed from the concrete mixture ratio, construction technology and maintenance measures and other aspects, and the corresponding views were put forward. The study results had the important guiding significance on crack controls of concrete structure during the construction process of northwest area.

Abstract: The construction of integral hoisting of arch rib of concrete filled steel tube arch bridge has the advantages of simple process, easy quality control, small safety risk and not affecting the river navigation, etc. This paper introduces the construction method of arch rib assembly and arch rib large segment hoisting.

Abstract: For soil nailing armor for outdoor mold technology principle, construction technology of underground practice and the key parts operation are introduced. Through economic analysis, the author points out that this construction method is simple and easy to operate and the waterproof effect and quality can be assured.

Abstract: As an important component of modern wood frame system, the design and construction of node are also constantly developing. By taking Sino-Canadian Exchange Center for Low-carbon & Building Energy-saving housing project for example, this paper is to introduce the node connection technology of the wooden structure in three aspects:new joint connection technology of Wood components , connection of Wood - concrete structures and node details processing in the wood structure, which plays a positive reference role in the development and promotion of modern wooden architecture node technology.