密集群目标跟踪的研究进展

随着“无人机蜂群”作战理念的提出,密集群目标成为各国测控、军事专家研究的热点领域。首先给出了群目标的定义并解释了其内涵,同时界定了密集群目标的范畴。通过分析密集群目标跟踪的流程和关键环节,总结并对比分析了密集群目标的分群技术、空间外形估计算法、分离与合并检测模型和目标状态滤波技术的相关研究。最后,结合目前密集群目标跟踪的研究热点,展望了未来密集群目标跟踪的研究方向。

Coupled 3D discrete-continuum numerical modeling of pile penetration in sand

A coupled discrete-continuum simulation incorporating a 3D aspect and non-circular particles was performed to analyze soil-pile interactions during pile penetration in sand.A self-developed non-circular particle numerical simulation program was used which considered sand near the pile as interacted particles using a discrete element method;the sand away from the pile was simulated as a continuous medium exhibiting linear elastic behaviors.The domain analyzed was divided into two zones.Contact forces at the interface between the two zones were obtained from a discrete zone and applied to the continuum boundaries as nodal forces,while the interface velocities were obtained from the continuum zone and applied to the discrete boundaries.We show that the coupled discrete-continuum simulation can give a microscopic description of the pile penetration process without losing the discrete nature of the zone concerned,and may significantly improve computational efficiency.