In response to the dual threats of high-intensity earthquakes and seasonal frost heave faced by rural buildings in cold regions, conventional seismic isolation technologies currently suffer from material hardening and efficiency degradation at low temperatures. For this purpose, a composite seismic isolation system is proposed by studying the low rise masonry structure and connecting the base sand cushion layer and the ring beam sliding layer in series. By constructing a simplified dynamic model and considering the nonlinear constitutive relationship of materials with low-temperature characteristics, multi condition numerical simulation experiments were conducted using the Code_Aster platform for verification. Under Chi Chi wave conditions, the composite isolation system is less affected by long-period pulses, with an amplification factor controlled at 0.52 and an isolation rate maintained at 78.3%. Under the RH-1 wave condition, the isolation rate of the system reaches 82.2%, which is better than the 77.7% of a single sliding system. In the 8.5 degree 0.3 g working condition, when the friction coefficient is 0.3, the relative slip of the composite isolation system is only 32.6 mm, which is reduced by 10.9 mm compared to the ordinary system. The numerical simulation results show that the composite isolation system can effectively isolate earthquake energy and avoid frost heave risk, providing a potential numerical reference scheme for disaster prevention and reduction in cold regions.
Global climate change intensifies hydrological extremes, challenging inhabited floodplain landscapes where environmental regulation, socio-economic decline, and institutional ambiguity co-produce persistent development traps. Research on sandbar islands – dynamic, inhabited landforms in large river systems – has largely overlooked the integration of social and economic dimensions. Using Tianxingzhou, a mid-Yangtze sandbar, as a critical case, this study integrates socio-economic conditions, natural resource and environmental characteristics, infrastructure status, governmental planning and regulatory guidance, and field observations with iterative SWOT analysis. Findings reveal a self-reinforcing development trap driven by four interacting dimensions: deteriorating socio-economic conditions (aging, outmigration, economic monostructure); vulnerable natural assets (fertile but flood-exposed); stagnant infrastructure (minimal public services); and policy stasis (no detailed spatial planning document update since 2013). These dimensions lock the island into a state where neither abandonment nor revitalization can proceed smoothly. A three-pillar sustainability framework (environmental–social–economic) is proposed, translating SWOT-derived strategies into testable heuristics. The framework provides a realistic pathway from lock-in to adaptive coexistence, with transferable principles for climate-vulnerable riverine and deltaic settlements worldwide. The findings offer a paradigm for balancing environmental conservation, socio-cultural engagement, and economic sustainability in ecologically sensitive island environments.
This study made use of the MATLAB software; the gray-box model of the heat pump unit was constructed by using the nonlinear least squares algorithm. The energy consumption model of the chilled water pump was fitted by using the curve fitting toolbox, and the transfer function of the chilled water system was identified through the system identification toolbox. An energy consumption optimization method based on the genetic algorithm was proposed. According to the energy consumption data on August 22nd, the energy consumption, temperature difference, and flow rate before and after optimization are compared. The energy savings at the optimal moment amounted to 17.31%. Meanwhile, the particle swarm optimization (PSO) algorithm is adopted to tune the control parameters of the traditional proportional–integral–derivative (PID); its control effect is better than that of the traditional trial-and-error method. Two groups of temperature difference simulation experiments are designed to verify the PSO–PID-optimized control strategy for the chilled water system based on feedforward. After optimization, the adjustment times of the system are reduced by 76.63% and 75.43%, respectively, demonstrating characteristics of rapidity, accuracy, and stability. In practical applications, this strategy can improve the quality of cooling and heating supply of the ground-source heat pump system and reduce the operating energy consumption.
To realize multiphysics field coupling analysis of large football stadium frame structures, a three-dimensional modeling method based on trinocular stereo vision and ABAQUS is proposed. This method acquires positional data of the frame structure, calibrates the three-camera plane for trinocular stereo measurement, and constructs a trinocular stereo vision model. Using this model, positional data of the large football stadium frame structure are obtained. Three-dimensional modeling is then completed in ABAQUS through the steps of part creation, assembly, material property definition, and meshing. Taking a large football stadium as the experimental subject, 10 sets of experiments are conducted. Camera calibration in the trinocular stereo measurement process serves as the basis for measuring the stadium frame structure. Different measurement distances, various lighting conditions, and diverse load conditions are set. The results demonstrate that the proposed method effectively accomplishes three-camera calibration for trinocular stereo measurement and obtains nonlinear analysis results such as displacement and horizontal tensile stress, showing favorable application performance.
This study investigates the effects of fiber on the mechanical performance and stress-strain characteristics of metakaolin-based recycled aggregate concrete (RAC). Ten experimental groups were designed, comprising single-fiber systems (steel fiber (SF), polyvinyl alcohol fiber (PF), and basalt fiber (BF)) and hybrid fiber systems combining SF-PF or SF-BF at blending ratios of 8:2, 7:3, and 5:5. Mechanical property evaluations included compressive strength, splitting tensile strength, elastic modulus, and full-range stress-strain curve analysis under uniaxial compression. Some constants are proposed based on test results to predict the compressive strength, splitting tensile strength, and elastic modulus of RAC. Furthermore, nonlinear regression analysis was performed to characterize the ascending and descending branches of stress-strain curves by the existing constitutive equations. The results indicate that the inclusion of fibers can effectively improve the mechanical properties of RAC. Based on some existing equations for compressive stress-strain curves of concrete, the parameters for the calculation of fiber-reinforced metakaolin-based RAC stress-strain curves were determined. Progressive substitution of SF with PF or BF in hybrid systems inversely correlates with strength and elastic modulus, while positively influencing peak strain development. A bilinear constitutive model derived from Al-Hassani's equation demonstrates superior fitting accuracy for hybrid fiber-reinforced metakaolin-based RAC. These results provide critical insights into the design of sustainable fiber-reinforced concrete with tunable mechanical properties through metakaolin activation and recycled aggregate utilization.
