RESUMEN
Full-duplex (FD) and reconfigurable intelligent surface (RIS) are potential technologies for achieving wireless communication effectively. Therefore, in theory, the RIS-aided FD system is supposed to enhance spectral efficiency significantly for the ubiquitous Internet of Things devices in smart cities. However, this technology additionally induces the loop-interference (LI) of RIS on the residual self-interference (SI) of the FD base station, especially in complicated urban outdoor environments, which will somewhat counterbalance the performance benefit. Inspired by this, we first establish an objective and constraints considering the residual SI and LI in two typical urban outdoor scenarios. Then, we decompose the original problem into two subproblems according to the variable types and jointly design the beamforming matrices and phase shifts vector methods. Specifically, we propose a successive convex approximation algorithm and a soft actor-critic deep reinforcement learning-related scheme to solve the subproblems alternately. To prove the effectiveness of our proposal, we introduce benchmarks of RIS phase shifts design for comparison. The simulation results show that the performance of the low-complexity proposed algorithm is only slightly lower than the exhaustive search method and outperforms the fixed-point iteration scheme. Moreover, the proposal in scenario two is more outstanding, demonstrating the application predominance in urban outdoor environments.
RESUMEN
Bioaerosols are more likely to accumulate in the residential environment, and long-term inhalation may lead to a variety of diseases and allergies. Here, we studied the distribution, influencing factors and diffusion characteristics of indoor and outdoor microbiota pollution in six residential buildings in Guangzhou, southern China over a period of one year. The results showed that the particle sizes of bioaerosol were mainly in the range of inhalable particle size (<4.7 µm) with a small difference among four seasons (74.61 % ± 2.17 %). The microbial communities showed obvious seasonal differences with high abundance in summer, but no obvious geographical differences. Among them, the bacteria were more abundant than the fungi. The dominant microbes in indoor and outdoor environments were similar, with Anoxybacillu, Brevibacillus and Acinetobacter as the dominant bacteria, and Cladosporium, Penicillium and Alternaria as the dominant fungi. The airborne microbiomes were more sensitive to temperature and particulate matter (PM2.5, PM10) concentrations. Based on the Sloan neutral model, bacteria were more prone to random diffusion than fungi, and the airborne microbiome can be randomly distributed in indoor and outdoor environments and between the two environments in each season. Bioaerosol in indoor was mainly from outdoor. The health risk evaluation showed that the indoor inhalation risks were higher than those outdoor. The air purifier had a better removal efficiency on 1.1-4.7 µm microorganisms, and the removal efficiency on Gram-negative bacteria was better than that on Gram-positive bacteria. This study is of great significance for the risk assessment and control of residential indoor bioaerosol exposure.
RESUMEN
Getting lost could lead to frustration, anxiety, and even fatal accidents. Previous research primarily focused on disorientation in indoor or outdoor environments separately. The indoor-outdoor transition received little attention, yet it is in this complex transition that individuals often lose their way. Therefore, the effects of indoor-outdoor route alignment, visual access, and age on wayfinding performance and spatial cognition were examined. Twenty older adults (aged 18-25) and twenty young adults (aged 65-82) participated in an experiment through desktop Virtual Reality (VR). They traversed indoor-outdoor environments and were informed within a building to quickly navigate an item inside another building. They also drew the route map. Participants repeated tasks in four different environments. Their spatial cognition and wayfinding performance were analyzed. Four main findings were derived. Firstly, the accuracy of global representation of the routes in the indoor-outdoor route alignment environment was higher than that in the non-aligned environment. Secondly, in environments with higher visual access, the accuracy of global representation of the routes for older adults was higher than that with lower visual access. Thirdly, enhancing visual access attenuated the negative impact of the non-aligned route on global representation of the routes. This effect is particularly beneficial for older adults. Fourthly, the younger adults outperformed the older adults in both wayfinding performance and global representation of the routes in indoor-outdoor environments. This difference could potentially be attributed to variations in education level, mental rotation ability, and digital experience. These findings provide valuable implications for urban design and wayfinding strategies.