To address the casualties caused by hypothermia in cold environments, this study designed a solar-powered rewarming sleeping bag for casualties under extremely cold conditions using the phase change materials ODE@ CaF₂ MPCMs and Cu₂O@ n-C₂₀, which release heat during phase change at low temperatures. Hot-water simulations and human experiments were also conducted. The results of hot-water simulations at 0 ℃,4 ℃, and 8 ℃, with an initial phase-change-material temperature of 40 ℃, showed that warm water with an initial temperature of 37 ℃ could be maintained at approximately 36 ℃ for 3600 s, and the bilateral distribution of phase-change materials had a higher heating rate than that of a unilateral distribution. In human experiments, under -5 ℃,0 ℃, and 5 ℃ temperature conditions, the average temperature could be maintained at approximately 35 ℃ for 3600 s, and the unilateral distribution of phase-change materials had better insulation than the bilateral distribution, with an average temperature increase of 2 ℃. At -15 ℃, the average temperature could be maintained above 32 ℃ for 540 min. A temperature-distribution uniformity analysis showed that the maximum coefficient of variation for the unilateral distribution was 0.036 and that for the bilateral distribution was 0.053, indicating a relatively uniform temperature distribution inside the sleeping bag, with the unilateral distribution being more uniform than the bilateral distribution. Comprehensive performance assessments showed that the sleeping bag had excellent insulation but requires optimization for convenience; after 30 repetitions of an experiment at -5 ℃, the temperature effect remained almost unchanged, with only a 0.05 ℃ decrease in the average human body temperature after 30 uses. Moreover, the cost of the sleeping bag is only approximately 400 RMB, and a single heating to 40 ℃ consumes approximately 0.24 kW·h, which is low and shows good economic benefits.

This study first delves into computational methods, radiation characteristics, and underlying mechanisms of ultraviolet radiation emitted by hypersonic vehicles, the study of which holds immense significance for ensuring safe flight. Based on the principles of hypersonic non-equilibrium flows and the transition mechanisms of ultraviolet radiation, a comprehensive analysis is provided on the computational procedures for determining parameters like the spectral absorption coefficient and molecular number density. Furthermore, the study explores the application scenarios of the line-by-line calculation method and the radiative transfer equation. Numerical and experimental investigations using collision-radiation models on the ultraviolet spectral and radiation characteristics of NO and OH molecules are summarized . The current status of ultraviolet radiation transmission modeling is also presented, focusing on the influence of geometry configuration, observation angle, flight altitude, and flight speed on the ultraviolet radiation. The deficiencies of these models are identified by comparing simulation results with those obtained by recent ground and flight experiments. Future research should prioritize the development of an integrated radiation model and advanced ultraviolet testing and non-equilibrium diagnostic techniques to meet practical needs such as target characteristic detection and thermal protection system optimization.

The U-type ground heat exchanger is a significant component of the ground source heat pump (GSHP) system, transferring heat from the soil for the air conditioning requirements. Heat accumulation becomes a common problem for the practical application of such systems in southern China. Moreover, the buried pipes containing heat exchangers are constructed in a group form, making the heat accumulation situation more severe and complex. A 3-dimensional simulation model of a 9-well buried pipe group was established and validated by a thermal response test conducted in Nanjing, China. On the basis of this model, the influence of underground seepage water temperature and flow rate on thermal distribution was investigated. Subsequently, the heat transfer capacity of single-well depth in a heat exchanger under varying conditions was calculated. It is concluded that a serious heat accumulation occurs without groundwater seepage. With seepage flow, the heat accumulation can be dissipated. Lower seepage temperature has a modestly beneficial effect on the heat dissipation. The heat accumulation can be better dissipated and the heat transfer capacity per well depth can be improved with greater seepage flow rate.