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Despite the increasing frequency in spot ignition by embers in wildfires, research on the multiple physicochemical processes intrinsic to ember combustion is limited. In this study, a two-dimensional computational model was proposed to study the glowing combustion of a wooden ember. A global char oxidation reaction was used to represent the glowing combustion of the ember. A parametric study showed that the porosity, heat of reaction, and oxygen concentration were the most influential parameters on the ember combustion. Then, the model was compared to a series of bench-scale experiments in terms of glowing time and thermal response of a non-reacting substrate when exposed to a hot ember. The simulation results showed that ember combustion was mostly diffusion-controlled rather than kinetic-controlled. Thus, given the ember diversities in spotting fire, modelers should pay more attention to the difference in the physical properties instead of the kinetics between ember species. [ABSTRACT FROM AUTHOR]

Twist phase is a nontrivial second-order phase that only exists in a partially coherent beam. Such twist phase endows the partially coherent beam with orbital angular momentum (OAM) and has unique applications such as in super-resolution imaging. However, the manipulation and the detection of the twist phase are still far from easy tasks in experiment. In this work, we present a flexible approach to generate a famous class of twisted Gaussian Schell-model (TGSM) beam with controllable twist phase by the superposition of the complex field realizations using a single phase-only spatial light modulator. The precise control of the amplitude and phase of the field realizations allows one to manipulate the strength of the twist phase easily. In addition, we show that the twist factor, a key factor that determines the strength of twist phase and the amount of OAM, can be measured by extracting the real part of the complex degree of coherence of the TGSM beam. The experiment is carried out with the help of the generalized Hanbury Brown and Twiss experiment as the generated TGSM beam obeys Gaussian statistics. The flexible control and detection of the twist phase are expected to find applications in coherence and OAM-based ghost imaging.

In this letter, we conducted a detailed investigation of the statistical properties, such as spectral density, spectral degree of coherence (SDOC), orbital angular momentum (OAM) flux density, and propagation factor M2, of a twisted Gaussian Schell-model (TGSM) beam carrying the cross phase in a turbulent atmosphere. Our findings revealed that atmospheric turbulence induces degeneration of the intensity distribution and spectral degree of coherence of a Gaussian Schell-model beam with the cross phase during propagation, while the twist phase acts as an antidote to degradation. Furthermore, we observed that the z-component of the time-averaged angular momentum flux is determined by the twist phase, whereas the cross phase influences the distribution of the OAM flux density in the beam. Additionally, we explored the variations in the propagation factor M2 of a TGSM beam with the cross phase in a turbulent atmosphere. Notably, we discovered that the deleterious effects of the atmospheric conditions can be mitigated by modulating both the twist and the cross phases. This work contributes valuable insights for information transfer and optical manipulations. [ABSTRACT FROM AUTHOR]

Focusing on the battery-charging problem that is brought to the electric automobile users, this paper integrated the “automobile-network-path” multi-source information and presented the multi-level user experience index system which combined charging prices, driving distances, degrees of traffic congestion and other factors. The recommended algorithm and model for charging strategy was built up to improve the user experience. Meanwhile, it invoked map Application Programming Interface (API) to plan multiple paths. Consolidated by the status of charging piles, the distance between the automobile and the piles, the charging prices along with more real-time information, the multi-level user oriented experience index system was set up to recommend an optimal navigation route to the charging station for the automobile owners. Validated by the application results, the proposed algorithm that helped navigate to the charging stations or piles can effectively solve the practical problems1 such as difficulty in orienting the charging piles, waiting in lines, and high charging fees.