While many radio technologies are available for mobile devices, none of them are designed to deal with asymmetric available energy. Battery capacities of mobile devices vary by up to three orders of magnitude between laptops and wearables, and our inability to deal with such asymmetry has limited the lifetime of constrained portable devices. This paper presents a radically new design for low-power radios --- one that is capable of dynamically splitting the power burden of communication between the transmitter and receiver in proportion to the available energy on the two devices. We achieve this with a novel carrier offload method that dynamically moves carrier generation across end points. While such a design might raise the specter of a high-power, large form-factor radio, we show that this integration can be achieved with no more than a BLE-style active radio augmented with a few additional components. Our design, Braidio is a low-power, tightly integrated, low-cost radio capable of operating as an active and passive transceiver. When these modes operate in an interleaved (braided) manner, the end result is a power-proportional low-power radio that is able to achieve 1:2546 to 3546:1 power consumption ratios between a transmitter and a receiver, all while operating at low power.

Understanding the evolution of air flow fields and leakage patterns in large-scale goaf areas is crucial for preventing spontaneous combustion of residual coal and ensuring mining safety. Current understanding of air leakage evolution in interconnected goaf areas remains insufficient for effective hazard control. This study aims to investigate the characteristics of air flow fields and establish prevention strategies for large-scale goaf areas. Fast Lagrangian analysis of continua in 3 dimensions (FLAC3D) numerical simulations were employed to analyze the fracturing and stress distribution of overlying strata, establishing a three-dimensional porosity model. The spatiotemporal evolution of air leakage flow fields was then simulated using FLUENT computational fluid dynamics software. Results indicated that stress distribution in the large goaf area was concentrated in the central region, exhibiting a “saddle-shaped” fracture pattern with a maximum stress of 35.4 MPa. The void ratio distribution displayed an elliptical pattern, with the lowest value of 0.097 in the compacted central goaf area, increasing to 0.34 at the boundary. Measurements of the air leakage field revealed inlet and outlet flow rates of 242.63 and 232.62 m3/min, respectively. The coupled hazardous zones were primarily concentrated around air leakage sources and their adjacent goaf areas, extending 336.42 m horizontally and 224.21 m vertically, encompassing a total area of 17 433.04 m2. Based on these findings, a three-zone prevention strategy was developed, providing new insights into spontaneous combustion control for large-scale goaf areas.