Study on Dune Morphology in Computer Mapping Based on 3S Technology

Take the parabolic dune of Hobq desert in Inner Mongolia as research object. Based on the GIS platform by using differential GPS data and spatial interpolation to generate DEM, then using Multi-periods high resolution images to acquire the environmental background, at the same time combine with regional wind regime and vegetation condition to measure and analyze the morphology of the parabolic dune. The result shows that the parabolic dune showed U shape in plane, and dune arms point to the west which was also wind direction. The windward slope of longitudinal profile is gentler, while leeward slope is steeper. And cross section wasn’t symmetric. The dune’s average moving speed is 11.76 m/yr. Desert ridge line’s medial axis direction is WNW-ESE, in accord with the direction of prevailing wind and resultant drift potential. Artemisia Ordosicas mainly distribute on leeward slope, two arms, and the plane ground between them, and the annual average vegetation coverage decreased 0.95%. In the long-term effect of resultant wind, the dune keeps moving forward and Artemisia Ordosica between two arms show gradual natural stage recovery which presented zonal distribution. 3S technology has already become important research method in modern Aeolian sand morphology.

Feasibility of resection and plication “RAP” technique for management of medically refractory GERD in patients with altered gastric anatomy

Background and study aims Gastroesophageal reflux disease (GERD) is common, especially in patients after gastric surgery. Medical management of GERD is ineffective in up to 30 % patients and revisional gastric surgery for management of GERD is associated with higher morbidity. We aimed to assess the safety, feasibility, and efficacy of a novel endoscopic resection and plication (RAP) anti-reflux procedure for management of medically refractory GERD in patients with altered gastric anatomy. Patients and methods The RAP procedure involves endoscopic mucosal resection and full-thickness plication over the right posterior-medial axis extending 15 mm above and 20 to 30 mm below the squamocolumnar junction. Adverse events, technical feasibility, GERD health-related quality-of-life (GERD-HRQL) scores, and medication use were prospectively recorded. Results Twenty consecutive patients with previous gastric surgery underwent RAP between September 2018 and August 2020 with a median follow-up of 5.7 months. The median procedure duration was 66 minutes (IQR 53.8–89.5). RAP was technically successful in 19 patients. One patient developed gastric hemorrhage from suture dehiscence, which was managed endoscopically, and four patients developed esophageal stricture requiring endoscopic dilation. Following the RAP procedure, significant improvement in GERD-HRQL score was observed (mean 26.9, 95 %CI 23.36–30.55, P < 0.01). Fourteen of 19 patients reported > 50 % improvement in GERD-HRQL scores. Sixteen of 18 patients reported reduction in requirement for or cessation of antacid therapy. Conclusions Patients with refractory GERD after gastric surgery have limited therapeutic options. We have demonstrated that the RAP procedure is feasible, safe, and clinically effective at short-term follow-up. It provides a potential alternative to revisional surgery in patients with altered gastric anatomy.

3D Reconstruction of Bridges from Airborne Laser Scanning Data and Cadastral Footprints

The given paper describes a method for automatic 3D reconstruction of bridges from cadastral footprints and airborne laser scanning point clouds. The reconstructed bridges are used to enrich 3D city models. Unlike roofs, decks of bridges are typically smooth without ridge lines or step edges. Therefore, established methods for roof reconstruction are not suitable for bridges. The standard description language for semantic city models is CityGML. This specification of the Open Geospatial Consortium assumes that surfaces are composed of planar polygons. The approximation of smooth decks by planar polygons is achieved by using a medial axis tree. Instead of the medial axis of the footprint, a modified medial axis is computed that does not consider counter bearing edges. The resulting tree represents centerline connections between all counter bearing edges and, in conjunction with filtered height values of a point cloud, serves as the basis for approximation with polygons. In addition to modeling decks, superstructures such as pylons and cables are also derived from the point cloud. For this purpose, planes carrying many superstructure points are detected using the Random Sampling Consensus Algorithm (RANSAC). Images are generated by projecting points onto these planes. Then, image processing methods are used to find connected contours that are extruded to form 3D objects. The presented method was successfully applied to all bridges of two German cities as well as to large bridges built over the Rhine River.

Computerized image understanding system for reliable estimation of spinal curvature in idiopathic scoliosis

Analysis of scoliosis requires thorough radiographic evaluation by spinal curvature estimation to completely assess the spinal deformity. Spinal curvature estimation gives orthopaedic surgeons an idea of severity of spinal deformity for therapeutic purposes. Manual intervention has always been an issue to ensure accuracy and repeatability. Computer assisted systems are semi-automatic and is still influenced by surgeon’s expertise. Spinal curvature estimation completely relies on accurate identification of required end vertebrae like superior end-vertebra, inferior end-vertebra and apical vertebra. In the present work, automatic extraction of spinal information central sacral line and medial axis by computerized image understanding system has been proposed. The inter-observer variability in the anatomical landmark identification is quantified using Kappa statistic. The resultant Kappa value computed between proposed algorithm and observer lies in the range 0.7 and 0.9, which shows good accuracy. Identification of the required end vertebra is automated by the extracted spinal information. Difference in inter and intra-observer variability for the state of the art computer assisted and proposed system are quantified in terms of mean absolute difference for the various types (Type-I, Type-II, Type-III, Type-IV, and Type-V) of scoliosis.