Search Results (7)

Autonomous UAV landing on dynamic unmanned surface vessel platforms is affected by deck motion and degraded visual observations, which may lead to unsafe final descent decisions. This paper proposes a fully decentralized reliability-enhanced predictive landing method that combines probabilistic perception, visual quality assessment, and model predictive control. Target posterior probability, perception uncertainty, and task-oriented image quality are fused into an online observation reliability index, which is used to adapt observation noise, constrain phase switching, and penalize unreliable descent opportunities. FFT-based dominant-mode identification and Kalman correction are also used to predict deck roll and pitch for landing-window selection. Simulation results show that the proposed method achieves a 90% small-angle landing success rate and keeps the touchdown attitude angle within 5°. Compared with standard MPC, landings within a 15° deck inclination increase from 24% to 82%, and the 80th-percentile touchdown inclination decreases by 9°. Compared with SHMPC, the average solution time decreases from 913 ms to approximately 104 ms per iteration. These results indicate that the proposed reliability-aware framework can reduce unsafe descent decisions and improve landing robustness while maintaining real-time feasibility under degraded maritime visual conditions. Full article

Traditional village residents’ emotional perception is a mapping of the man–land relationship in rural areas, which leads to the attitudes and behaviors of the residents. Against the background of previous studies focusing on technical rationality but neglecting the exploration of “human” emotional factors, it is crucial to carry out research on the traditional village residents’ emotional perception to promote people-centered rural development of high quality. The paper selected 123 residents from 14 traditional villages in Guanzhong region and constructs an evaluation index system which includes three dimensions based on the logical framework of “spiritual attachment-functional dependence-developmental cognition”. Next, the questionnaire method was used to collect data and the empirical analysis was conducted using the obstacle degree model and the network analysis model. The research shows that: (1) the overall level of the traditional village residents’ emotional perception is in the middle-upper class and there are significant differences, and there is a non-equilibrium in different evaluation dimensions. (2) The main obstacle to the improvement of the level of traditional village residents’ emotional perception is perception of development, followed by the sense of belonging, and the sense of happiness has a greater supportive role. (3) “Sustainable development of the village” (D-07) is the central node of the network analysis model of traditional village residents’ emotional perception. Meanwhile, the nodes “willingness to live” (G-02) and “basic rights are guaranteed” (X-10) are the central nodes of the sub-networks of sense of belonging and sense of happiness. (4) The residents’ education level and the frequency of community participation have a significant positive effect on their emotional perception level. Finally, the paper explores the dynamic compensation mechanism of traditional village residents’ emotional perception. Our results provide policy guidance for achieving sustainable development of traditional villages. Full article

Changes in the spatial pattern of land use are inextricably linked to the ecosystem environment, and the assessment of regional eco-environment quality can help provide sustainable and healthy development strategies for heritage management organizations. In this study, based on RS and GIS technologies, we quantitatively analyzed the characteristics of land use changes in the Shibing Karst World Natural Heritage site from 2000 to 2020, and introduced the regional eco-environment quality assessment index for quantitative factor analysis. The results show that: (1) The heritage site is mainly dominated by forest and shrub, with more aggregated cropland, and impervious surfaces in the buffer zone. The area of shrub has increased during the 20-year period, occupying 12.63% of the total transferred area. Cropland has been basically converted to forest, accounting for more than 60% of the total transferred area, followed by shrubs, which have been basically transferred to ecologically better land types. (2) By analyzing the attitude of motivation, forest, shrub, and water have positive values, while cropland, grassland, and impervious surfaces have negative values. Grassland has the largest absolute value of kinetic attitude, and the smallest is for water. The integrated dynamic attitude is basically maintained at 24%, showing a state of rapid and then stable land category conversion. (3) Over the past 20 years, the regional eco-environment quality index has been stable between 0.68 and 0.71, and shows a trend of rapid growth and stabilization, which is consistent with the comprehensive attitude. The conversion between cropland, forest, and shrubs is the main cause of ecological improvement and deterioration. Overall, the relevant conservation measures at the site and China’s corresponding responses to global climate change have led to a stabilization and increase in the regional ecological quality of the site. The management measures of the relevant authorities have begun to bear fruit, but further promotion of the sustainable development of the site is needed to provide a scientific model for the conservation of other karst heritage sites. Full article

Ecological sensitivity measures an ecosystem’s reaction and restoration difficulty to exogenous disturbances. Regional ecological and environmental challenges can be identified using ecological sensitivity evaluation. The regional characteristics and environmental challenges of plateau lakes were quantified to create four assessment indexes: landform, natural conditions, human activities, and ecological security. Eleven ecologically sensitive characteristics were chosen. We evaluated the landscape ecological sensitivity of the Erhai Lake Basin, China, using ArcGIS and the analytical hierarchy process (AHP). The results showed that the Erhai Lake Basin was mostly forest from 1990 to 2020 and that the dynamic land-use attitude increased and then reduced. The cultivated land became mostly woods and grassland. The largest building area was tied to reverting farms to woods and urban construction. The highest weight was from single-factor ecologically sensitive vegetation covering, followed by river systems and roadways, and lowest was from landslides and collapses. The ecologically sensitive areas with more vegetation and a greater distance from roads and woodland are harder to recover from harm. According to the thorough sensitivity analysis, the study region’s high sensitivity area is 1102.36 km² (26.16%) and the higher sensitivity area is 1177.10 km² (27.93%). The ecological sensitivity increases from neighborhoods to nature reserves. High-sensitivity areas were in hilly woods and grasslands with few people. The low-sensitivity area was around water and homes. The dynamic stability of the area ecological environment influenced ecological sensitivity. This study aims to provide sustainable land use solutions for the Erhai Lake Basin and a scientific basis for managing and protecting ecologically vulnerable areas. Full article

This paper assesses the sustainability impacts in the middle and lower reaches of the Yellow River in China after the Xiaolangdi Dam was constructed. Based on land use data interpreted from Landsat remote sensing images, covering the time period from 2000 to 2020 at 5-year intervals, this research uses a land dynamic attitude index and comprehensive index of land use degree to reveal the degree of land use type change in the study area and analyze the relationship between land use and social economy. The results show that urban and rural construction land is the land use type with the largest annual change rate, and the increase is most obvious from 2005 to 2010, growing by nearly 900 km². The six types of land use in the research area changed sharply from 2000 to 2010, with grassland and unused land showing the most significant change. On the whole, the dynamic attitude of comprehensive land use tends to be stable. The comprehensive index analysis of land use degree indicates that the study area has developed in the direction of urban settlement. Population and GDP are the main driving factors affecting the constant change in land use types in this region, in which population growth and rapid economic development are the main factors leading to the decline of grassland area, and are also the main driving factors for the expansion of construction land. The research results provide a scientific basis for sustainable land use and development in the middle and lower reaches of the Yellow River Basin. Full article

The purpose of this paper is to establish a transition strategy for tilt-rotor vertical takeoff and landing (VTOL) unmanned aerial vehicles (UAVs) based on an optimal design method. Firstly, The flyable transition corridor was calculated based on both the UAV’s dynamic equations and its aerodynamic and dynamic characteristics. The dynamic equations of the UAV were organized into state equation forms. The initial and final value constraints of the control and state variables in the transition process were recorded, as were the constraints of the transition process. The transition strategy design problem was transformed into an optimal control problem with constraints, while the Gauss pseudospectral method (GPM) was employed to transform and solve the problem. In addition, performance indicators were designed based on the transition quality requirements for transition time, attitude stability, and control continuity. Sensitivity was analyzed according to different index terms with different dimensions and effects. Finally, the rationality of the transition strategy designed in this paper was verified according to different simulation scenarios. Full article

At the intersection of the Qinghai–Tibet Plateau and Loess Plateau, topographic factors often profoundly affect the evolution of the regional land use pattern and ecological risk. This paper takes the Lanzhou–Xining urban agglomeration as the research area, divides the topographic gradient based on the topographic index, analyzes the characteristics of the land use pattern using the land use transfer matrix model, dynamic attitude and state degree model, and analyzes the influence of topographic factors on the land use pattern using the distribution model. At the same time, an ecological risk evaluation index system is constructed, the spatial principal component method is used to evaluate the ecological risk, and the influence of topography on the regional ecological risk is discussed. The results show that from 1990 to 2020, the area of construction land in the study area increased by 1045.807 km² and the area of ecological land increased by 587.41 km², with the most significant changes occurring in the attitude and state of construction land and unused land. It is found that cultivated land, water area and construction land are dominant in low terrain, while woodland, grassland and unused land are mainly distributed in middle and high terrain. During the study period, the ecological risk in the midwest and southeast of the Lanzhou–Xining urban agglomeration decreased, while the ecological risk in the northeast increased first and then decreased, although generally there was an increasing trend. Moran’s I varied from 0.942 to 0.955 from 1990 to 2020, indicating that the ecological risk index in the study area was highly positively correlated in space, while the spatial aggregation effect of the ecological risk was obvious. Low and moderately low risk areas are mainly distributed in high terrain, while high and moderately high risk areas are dominant in low terrain. The research results of this paper can make a lot of sense for ecological protection, land resource utilization and sustainable development of the Lanzhou–Xining urban agglomeration. Full article