Steady state speed distribution analysis for a combined cellular automaton traffic model

Cellular Automaton （CA） based traffic flow models have been extensively studied due to their effectiveness and simplicity in recent years. This paper develops a discrete time Markov chain （DTMC） analytical framework for a Nagel-Schreckenberg and Fukui Ishibashi combined CA model （W^2H traffic flow model） from microscopic point of view to capture the macroscopic steady state speed distributions. The inter-vehicle spacing Maxkov chain and the steady state speed Markov chain are proved to be irreducible and ergodic. The theoretical speed probability distributions depending on the traffic density and stochastic delay probability are in good accordance with numerical simulations. The derived fundamental diagram of the average speed from theoretical speed distributions is equivalent to the results in the previous work.     

四基元宽频带恒定束宽声基阵

本文详细介绍由四个具有余弦规律变化指向性图的基元所组成的声基阵结构,其各个基元的声轴俟个相互错开90°,从而实现波束全方位覆盖,并利用振幅法测向原理达到对入射声信号的方位检测。基阵后挡是特殊成分的反声泡沫橡胶。实践证明,合适的后档尺寸可以在频率为8:1倍率范围内获得束宽恒定。本文还对于基阵结构作了数学模拟,理论计算与实测数据吻合比较好。     

权重抑制扇形多基元柱面基阵旁瓣

本文给出了多基元扇形柱面基阵指向性函数,分析了其比较复杂的相位特征。详细阐述了通过合理选取基元数目、加后挡以及振幅权重等方法有效的抑制旁瓣,以实现对声信号方位跟踪及目标定位。     

离散多基元声基阵指向性函数计算

本文从任意分布的离散多基元点阵的指向性函数,引出线列阵、圆弧阵、平面阵、圆柱阵以及球面阵、共形阵的指向性函数。并且进一步阐述了它们的波束形成和波束空间复盖方案设计。