A study on dual quaternion based cooperative relative navigation of multiple UAVs with monocular vision-inertial integration

This paper addresses a cooperative relative navigation problem for multiple aerial agents,relying on visual tracking information between vehicles.The research aims to investigate a sensor fusion architecture and algorithm that leverages partially available absolute navigation knowledge while exploiting collaborative visual interaction between vehicles in mission flight areas,where satellite navigation-denied regions are irregularly located.To achieve this,the paper introduces a new approach to defining the relative poses of cameras and develops a corresponding process to secure the relative pose information.This contrasts with previous research,which simply linearized the relative pose information of aircraft cameras into navigation states defined in an absolute coordinate system.Specifically,the target pose in relative navigation is defined,and the pose of the camera and feature points are directly derived using dual quaternion representation,which compactly represents both translation and rotation.Furthermore,a mathematical model for the relative pose of the camera is derived through the dual quaternion framework,enabling an explicit pose formulation of relative navigation.The study investigates navigation performance in typical mission flight scenarios using an in-house high-fidelity simulator and quantitatively highlights the contributions of the proposed scheme by comparing the navigation error performance.Consequently,the proposed method demonstrates to have navigation accuracy in decimeter level even in GNSS-denied environments and an improved 3D Root Mean Square(RMS)error by30%smaller than the conventional absolute navigation framework.

Submerged arc plasma system combined with ozone oxidation for the treatment of wastewater containing non-degradable organic compounds

Submerged arc plasma technology was assessed for the removal of phenols from wastewater.The OH radicals generated from the boundary between the plasma and waste solution were considered as a significant factor on the degradation reaction.In this study,the effects of highly energetic electrons released from the submerged arc plasma were mainly studied.The highly energetic electrons directly broke the strong chemical bond and locally increased the reaction temperatures in solution.The effects of the submerged-arc plasma on the decomposition of phenol are discussed in terms of the input energy and initial concentration.The single use of submerged arc plasma easily decomposed the phenol but did not increase the mineralization efficiency.Therefore,the submerged arc plasma,coupled with the ozone injection,was investigated.The submerged arc plasma combined with ozone injection had a synergic effect,which led to significant improvements in mineralization with only a small increase in input energy.The decomposition mechanism of phenol by the submerged arc plasma with the ozone was analyzed.