5,443 research outputs found
Extracting -wave scattering lengths from cusp effect in heavy quarkonium dipion transitions
Charge-exchange rescattering leads to a cusp
effect in the invariant mass spectrum of processes with
in the final state which can be used to measure -wave
scattering lengths. Employing a non-relativistic effective field theory, we
discuss the possibility of extracting the scattering lengths in heavy
quarkonium transitions. The transition
is studied in details. We discuss the
precision that can be reached in such an extraction for a certain number of
events.Comment: 15 pages, 7 figures, 1 tabl
Implementation of UAV Coordination Based on a Hierarchical Multi-UAV Simulation Platform
In this paper, a hierarchical multi-UAV simulation platform,called XTDrone,
is designed for UAV swarms, which is completely open-source 4 . There are six
layers in XTDrone: communication, simulator,low-level control, high-level
control, coordination, and human interac-tion layers. XTDrone has three
advantages. Firstly, the simulation speedcan be adjusted to match the computer
performance, based on the lock-step mode. Thus, the simulations can be
conducted on a work stationor on a personal laptop, for different purposes.
Secondly, a simplifiedsimulator is also developed which enables quick algorithm
designing sothat the approximated behavior of UAV swarms can be observed
inadvance. Thirdly, XTDrone is based on ROS, Gazebo, and PX4, andhence the
codes in simulations can be easily transplanted to embeddedsystems. Note that
XTDrone can support various types of multi-UAVmissions, and we provide two
important demos in this paper: one is aground-station-based multi-UAV
cooperative search, and the other is adistributed UAV formation flight,
including consensus-based formationcontrol, task assignment, and obstacle
avoidance.Comment: 12 pages, 10 figures. And for the, see
https://gitee.com/robin_shaun/XTDron
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