Human activities are constantly affecting ecological space, and the construction of ecological security patterns to ensure ecological security has become an issue that must be considered for sustainable development. At present, little attention has been paid to the ecological security of cities with a high number of nature reserves. In this study, we took Garze Tibetan Autonomous Prefecture in China, which has many nature reserves, as the research object to construct an ecological security pattern with nature reserves as ecological sources. Firstly, Fragstats 4.2 and ArcGIS 10.4 were used to obtain the ecological risk evaluation results of the study area landscape. Secondly, a “nature–society–landscape” resistance factor system and an ecological resistance surface were constructed using a minimum resistance model. Finally, the ecological safety zone of the nature reserve was divided, and the ecological safety pattern of the nature reserve was established. (1) The ecological risk of the study area shows a spatial distribution pattern of “low in the northwest and high in the southeast”, with low and moderate-low ecological risk dominating; (2) The study area has formed an ecological security pattern consisting of 9 ecological sources, 35 ecological nodes, 8 ecological corridors with a total length of 702.96 km and 4 ecological safety zones; (3) The ecological security pattern of nature reserves in the study area was divided into four categories: low, medium, high and moderate-high ecological safety zones, accounting for 20.62%, 27.34%, 24.48% and 27.55%, respectively. This study provides a new framework for the construction of urban ecological safety patterns and offers scientific guidance for the conservation and management of nature reserves and urban ecology.

Three-dimensional indoor models have wide applications in fields such as indoor navigation, civil engineering, virtual reality, and so on. With the development of LiDAR technology, automatic reconstruction of indoor models from point clouds has gained significant attention. We propose a new framework for generating indoor 3D digital models from point clouds. The proposed method first generates a room instance map of an indoor scene. Walls are detected and projected onto a horizontal plane to form line segments. These segments are extended, intersected, and, by solving an integer programming problem, line segments are selected to create room polygons. The polygons are converted into a raster image, and image connectivity detection is used to generate a room instance map. Then the roofs of the point cloud are extracted and used to perform an overlap analysis with the generated room instance map to segment the entire roof point cloud, obtaining the roof for each room. Room boundaries are defined by extracting and regularizing the roof point cloud boundaries. Finally, by detecting doors and windows in the scene in two steps, we generate the floor plans and 3D models separately. Experiments with the Giblayout dataset show that our method is robust to clutter and furniture point clouds, achieving high-accuracy models that match real scenes. The mean precision and recall for the floorplans are both 0.93, and the Point–Surface Distance (PSD) and standard deviation of the PSD for the 3D models are 0.044 m and 0.066 m, respectively.

The study of the regional ecological sensitivity evolution process can timely understand the regional ecological evolution law and propose ecological protection strategies. In this study, an ecological sensitivity index system is established to quantitatively analyze the interrelationships of ecological factors. The CA-MC model and center of gravity migration are used to investigate the spatial and temporal evolution of ecological sensitivity in the upper Minjiang River basin from 2000 to 2020 and to predict the ecological sensitivity in 2040. Then with the help of Geodetector to clarify the influence intensity of each factor, different types of ecological regions are identified. The results show that (i) the applicability and accuracy of the analytical framework are verified by categorizing the study area into five classes: insensitive, lightly sensitive, moderately sensitive, highly sensitive, and extremely sensitive. (ii) The ecological sensitivity of the study area from 2000 to 2020 is still dominated by moderately sensitive and highly sensitive. In this process, the environmental protection measures become more and more diversified, and the insensitive areas are increasing. (iii) There is a significant difference in the shift of the center of gravity of ecological sensitivity at all levels, with the overall shift of insensitive, lightly sensitive, and highly sensitive areas to the east. The moderately sensitive and extremely sensitive areas have shifted to the southeast as a whole. Among them, the insensitive area shifted the farthest distance from 2010 to 2020, which was 15.16 km. (iv) The CA-MC model deduced that the overall sensitivity level of the Sichuan-Tibet Railway showed a slow decreasing trend from 2000 to 2040. Through the results of ecological sensitivity evaluation and discussion, this study effectively reveals the differences in ecological sensitivity risks faced by the development of typical watershed areas in China and provides a basis for the government to formulate policies suitable for different environmental protection.

The damages such as cracking and bending deformation in the timber beam-column joints in traditional vernacular dwellings in the Xianshui River Basin of Garzê Tibetan Autonomous Prefecture， Sichuan Province， the normal use of the house is affected， posing safety risks such as fracture of the main joint. Based on the survey data of Diqingyi Village in the upper Xianshui River Basin， this study takes the typical beam-column joint of a timber-framed house in the village as the research object. A steel reinforcement component was designed to address these issues. Finite element analysis software was used to establish models of the joint and the steel component， analyzing the failure conditions of the joint before and after reinforcement. Three performance indicators of the joint—hysteresis curve， skeleton curve， and stiffness degradation curve—were compared to evaluate the effectiveness of the reinforcement. The results indicated a 69.19% reduction in maximum von Mises stress （from 6.127 MPa to 1.888 MPa） following reinforcement. The bearing capacity increased by 35.52% to -25.45 kN at -120 mm displacement and by 25.60% to 28.89 kN at +150 mm displacement. The reinforced joint demonstrated improved stability， enhanced energy dissipation capacity， and greater deformation resistance under cyclic loading， confirming the system's effectiveness in seismic risk mitigation.