Effects of periodically modulated coupling on amplitude death in nonidentical oscillators

The effects of periodically modulated coupling on amplitude death in two coupled nonidentical oscillators are explored. The AD domain could be significantly influenced by tuning the modulation amplitude and the modulation frequency of the modulated coupling strength. There is an optimal value of modulation amplitude for the modulated coupling with which the largest AD domain is observed in the parameter space. The AD domain is enlarged with the decrease of the modulation frequency for a given small modulation amplitude, while is shrunk with decrease of the modulation frequency for a given large modulation amplitude. The mechanism of AD in the presence of periodic modulation in the coupling is investigated via the local condition Lyapunov exponent of the coupled system. The stability of AD state can be well characterized by conditional Lyapunov exponent. The coupled system experiencing from the oscillatory state to AD is clearly indicated by the observation that the conditional Lyapunov exponent transits from positive to negative. Our results are helpful to many potential applications for the research of neuroscience and dynamical control in engineering.Comment: 11 figures, 8 page

Optical Properties and Radiative Forcing of Aged BC due to Hygroscopic Growth: Effects of the Aggregate Structure

Black carbon (BC) particles become hydrophilic after mixing with soluble matter in the atmosphere, and their optical and radiative properties can be significantly modified accordingly. This study investigates the impact of aggregate structure on optical and radiative properties of aged BC, that is, BC coated by sulfate or organic aerosols, especially during hygroscopic growth. A more realistic BC morphology based on fractal aggregates is considered, and inhomogeneous mixtures of BC aggregates are treated more realistically (with respect to particle geometries) in the multiple sphere T‐matrix method for optical property simulations. As relative humidity increases, BC extinction is significantly enhanced due to an increase in scattering, and the enhancement depends on the amount and hydrophilicity of the coating. The absorption exhibits less variation during hygroscopic growth because the coating of aerosols already leads to BC absorption close to the maximum. Furthermore, hygroscopic growth not only results in negative radiative forcing (RF) at the top of the atmosphere but also slightly weakens the absorption in the atmosphere (inducing a negative RF in the atmosphere). Compared to the more realistic model with BC as aggregates, the currently popular core‐shell model reasonably approximates the top of the atmosphere RF but underestimates the atmospheric RF due to hygroscopic growth by up to 40%. Furthermore, for the RF caused by internal mixing, the core‐shell model overestimates the RFs at the surface and in the atmosphere by ~10%

Optical Properties and Radiative Forcing of Aged BC due to Hygroscopic Growth: Effects of the Aggregate Structure

Black carbon (BC) particles become hydrophilic after mixing with soluble matter in the atmosphere, and their optical and radiative properties can be significantly modified accordingly. This study investigates the impact of aggregate structure on optical and radiative properties of aged BC, that is, BC coated by sulfate or organic aerosols, especially during hygroscopic growth. A more realistic BC morphology based on fractal aggregates is considered, and inhomogeneous mixtures of BC aggregates are treated more realistically (with respect to particle geometries) in the multiple sphere T‐matrix method for optical property simulations. As relative humidity increases, BC extinction is significantly enhanced due to an increase in scattering, and the enhancement depends on the amount and hydrophilicity of the coating. The absorption exhibits less variation during hygroscopic growth because the coating of aerosols already leads to BC absorption close to the maximum. Furthermore, hygroscopic growth not only results in negative radiative forcing (RF) at the top of the atmosphere but also slightly weakens the absorption in the atmosphere (inducing a negative RF in the atmosphere). Compared to the more realistic model with BC as aggregates, the currently popular core‐shell model reasonably approximates the top of the atmosphere RF but underestimates the atmospheric RF due to hygroscopic growth by up to 40%. Furthermore, for the RF caused by internal mixing, the core‐shell model overestimates the RFs at the surface and in the atmosphere by ~10%

Research on grid based fire warning algorithm with YOLOv5s for palace buildings

In response to the early warning requirements of fire security technology in the Imperial Palace & large Ming and Qing ancient architectural complexes in China, a grid based fire warning algorithm is proposed by combining neural network YOLOv5s smoke detection technology. In this algorithm, the inverse proportional gridding algorithm based on building density is used to optimize the grid of buildings, and compared with the results of the equidistant grid algorithm, the risk distribution division is more detailed and reasonable. The smoke detection part uses YOLOv5s based smoke detection technology to detect the distribution of fire smoke in various areas, and the positioning of this area in the overall grid realized by the remote transmission module. With detection experiments on relevant datasets, the results show that its accuracy and mAP both reach 0.99. By utilizing the collaborative effect of inverse proportional gridding algorithm and smoke detection technology, a grid based visualization of smoke warning is achieved