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Radiofrequency ablation (RFA) is a minimally invasive technology for the treatment of liver malignancies and is used as an adjuvant therapy in patients with colorectal liver metastasis (CLM). This study enrolled a total of 49 CLM patients who underwent RFA treatment. Univariate and multivariate analyses were performed using the log-rank test and Cox proportional hazard model, respectively. Univariate analysis showed that OS was closely correlated with tumor size, frequency of RFA treatment, resection of the liver lesion, and CEA levels before RFA (p p

For 3-d laser scanning point clouds of an expressway tunnel, a method of automatically extracting complete contours of cross-sections from them is proposed. By taking advantage of abundant normal vectors embedded in point clouds, this method can accurately compute the central axis of the tunnel and build a reference cylinder surface coaxial with the tunnel. To rebuild the surface model for tunnels, a cylindrical projection is used to map all point clouds into a 2-d space firstly, and an improved 2-d Delaunay algorithm which can deal with the border-less circumferential angles is subsequently employed to construct the triangulated mesh from projection points in this two-dimensional space. Following the one-to-one mapping from the original point cloud to the projection point set, a corresponding 3-d triangulated mesh of the original point cloud is finally constructed in accordance with the 2-d triangulation result. By intersecting 3-d triangular mesh of tunnel with cross sections perpendicular to the tangential direction of axis, a series of contours are generated at the specified locations. For the curved tunnel, this method can adjust the direction of sections finely to make them always suitable for the constant change of tunnel direction. At the end of this paper, the experimental result demonstrate the effectiveness and high efficiency of this method by the use of the point clouds acquired from a real highway tunnel.

The dominating measurement error of Terrestrial Laser Scanner comes from laser ranging, which is also the major cause of "tailing points" appearing at the edge of targets scanned by coaxial laser scanner. Since the existence of such abnormal points, general least squares sphere fitting method cannot correctly position spherical targets or determine the dimension of geometries. Base on the working mechanism of coaxial laser scanner, a surface fitting model is designed in this paper for the spherical targets, and utilize robust least squares method to get model parameters from scanning data with obvious edge noise, then conclude the sphere radius and centre point coordinate. In the end, this paper accomplishes two experiments separately for really scanning data and synthesized data subjecting to scanner's error distribution. The result demonstrates that proposed fitting method can weaken the impact of abnormal points on the edge of spherical targets effectively, get geometric parameters of spherical targets accurately, and exactly locate the spherical targets.

This paper firstly suggested that multi-scale map data updating is based on the updating of larger scale map data, and the other smaller scale map data are updated step by step. Nowadays, there have been quite a few technical means to update the larger scale data, including field surveying, digital photogrammetry, remote sensing, LiDAR and digitization from the existing topographic maps, etc. Secondly, an updating method for incremental generalization cascade updating was provided according to the demands for map data at intermediate and small scale in china. The matching association table was established based on the determination of the matching relation and similar values through the method of the matching of multi-scale spatial features. The incremental information was then acquired through variation detection considering cartographic generalization impact. It was used to realize the incremental updating of map data. Furthermore, the cascade updating of multi-scale data were realized by the next matching association table, which making sure of uniformity of multi-scale data.

In recent years, the study of 3D spatial models has been developed rapidly, but most of the models are applied to 3D visualization or orebody modeling. They can only provide limited functionality and operations of spatial analysis. To solve this problem, this paper firstly analyzes the characteristics of 3D entities and their demands of modeling, and proposes the method of modeling the exterior surfaces instead of the solid entities themselves using regular volume elements, hence it has offered a new way of modeling 3D entities, which is based on raster technique, in order to make promising preparations for 3D spatial analyses, such as the sunlight analysis. Through preliminary visualization experiments taking the entities with common geometric shapes, simpler and complexer buildings as examples, the feasibility of this modeling method has been proved.

This paper suggests a method of calculating the elevation and the volume change of the terrain based on the multitemporal digital elevation model (DEM) data sets for the same area. Two methods for calculating the surface change are introduced: One is based on the regular square grids (RSG), another uses the triangulated irregular network (TIN) generalized from the original source data by the 3D Douglas-Peucker algorithm so that not only the accuracy of generalization using 3D Douglas-Peucker is verified, but also the kinds of data formats of DEM for this purpose have been expanded. Finally, the formulae used by these two methods are introduced, and the experimental results calculated from the same original DEM data acquired in 1971 and 2000 respectively form the area of Bayanbulak in Xinjiang are compared. The experiments have shown that the results of the two methods are relatively identical even if under the great generalization degree of DEM for the second method. Therefore, it shows that the second method can greatly heighten the efficiency of the calculation while insuring its accuracy.