45 research outputs found
Multi-level decision framework collision avoidance algorithm in emergency scenarios
With the rapid development of autonomous driving, the attention of academia
has increasingly focused on the development of anti-collision systems in
emergency scenarios, which have a crucial impact on driving safety. While
numerous anti-collision strategies have emerged in recent years, most of them
only consider steering or braking. The dynamic and complex nature of the
driving environment presents a challenge to developing robust collision
avoidance algorithms in emergency scenarios. To address the complex, dynamic
obstacle scene and improve lateral maneuverability, this paper establishes a
multi-level decision-making obstacle avoidance framework that employs the safe
distance model and integrates emergency steering and emergency braking to
complete the obstacle avoidance process. This approach helps avoid the
high-risk situation of vehicle instability that can result from the separation
of steering and braking actions. In the emergency steering algorithm, we define
the collision hazard moment and propose a multi-constraint dynamic collision
avoidance planning method that considers the driving area. Simulation results
demonstrate that the decision-making collision avoidance logic can be applied
to dynamic collision avoidance scenarios in complex traffic situations,
effectively completing the obstacle avoidance task in emergency scenarios and
improving the safety of autonomous driving
Magnetic Borophenes from an Evolutionary Search
A computational methodology based on ab initio evolutionary algorithms and spin-polarized density functional theory was developed to predict two-dimensional magnetic materials. Its application to a model system borophene reveals an unexpected rich magnetism and polymorphism. A metastable borophene with nonzero thickness is an antiferromagnetic semiconductor from first-principles calculations, and can be further tuned into a half-metal by finite electron doping. In this borophene, the buckling and coupling among three atomic layers are not only responsible for magnetism, but also result in an out-of-plane negative Poisson\u27s ratio under uniaxial tension, making it the first elemental material possessing auxetic and magnetic properties simultaneously
The Phosphate Transporter PHT4;1 is a Salicylic Acid Regulator Likely Controlled By the Circadian Clock Protein CCA1
The small phenolic compound salicylic acid (SA) plays a critical role in plant defense against broad-spectrum of pathogens. The phosphate transporter gene PHT4;1 was previously shown to affect SA-mediated defense and its expression is regulated by the circadian clock. To further understand how PHT4;1 affects SA accumulation, here we analyzed the genetic interactions between the gain-of-function mutant pht4;1-1 and several known SA mutants, including sid2-1, ald1-1, eds5-3, and pad4-1. The genetic analysis was conducted in the acd6-1 background since the change of acd6-1 dwarfism can be used as a convenient readout for the change of defense levels caused by impairments in some SA genes. We found that compared with the corresponding double mutants, the triple mutants acd6-1pht4;1-1ald1-1, acd6-1pht4;1-1eds5-3, and acd6-1pht4;1-1pad4-1 accumulated reduced SA and lower PR1 expression, suggesting that PHT4;1 contributes to acd6-1-conferred defense phenotypes independently of these known SA regulators. Although some triple mutants had wild type-like levels of SA and PR1 transcripts, these plants were smaller than wt and display minor cell death, suggesting that additional regulatory pathways contribute to acd6-1-conferred dwarfism and cell death. Our data further showed that circadian expression of PHT4;1 was dependent on CCA1, a central oscillator component of Arabidopsis circadian clock. Recombinant CCA1 protein was demonstrated to bind to the PHT4;1 promoter in electrophoretic mobility shift assays, suggesting a direct transcriptional regulation of PHT4;1 by CCA1. Together these results indicate that PHT4;1 is an SA regulator acting independently of several known SA genes and they also implicate a role of the circadian clock mediated by CCA1 in regulating phosphate transport and/or plant innate immunity