Recently,near-ambient superconductivity was claimed in nitrogen-doped lutetium hydride(LuH_(3-δ)N_(ε)).Unfortunately,all follow-up research still cannot find superconductivity signs in successfully synthesized lutet...Recently,near-ambient superconductivity was claimed in nitrogen-doped lutetium hydride(LuH_(3-δ)N_(ε)).Unfortunately,all follow-up research still cannot find superconductivity signs in successfully synthesized lutetium dihydride(LuH_(2)) and N-doped LuH_(2±x)N_(y).However,a similar intriguing observation was the pressure-induced color changes(from blue to pink and subsequent red).The physical understanding of its origin and the correlation between the color,crystal structure,and chemical composition of Lu–H–N is still lacking.In this work,we systematically investigated the optical properties of LuH_(2) and LuH_(3),and the effects of hydrogen vacancies and nitrogen doping using the first-principles calculations by considering both interband and intraband contributions.Our results demonstrate that the evolution of reflectivity peaks near blue and red light,which is driven by changes in the band gap and Fermi velocity of free electrons,resulting in the blue-to-red color change under pressure.In contrast,LuH_(3) exhibits gray and no color change up to 50 GPa.Furthermore,we investigated the effects of hydrogen vacancies and nitrogen doping on its optical properties.Hydrogen vacancies can significantly decrease the pressure of blue-to-red color change in LuH_(2) but do not have a noticeable effect on the color of LuH_(3).The N-doped LuH_(2) with the substitution of a hydrogen atom at the tetrahedral position maintains the color change when the N-doping concentration is low.As the doping level increases,this trend becomes less obvious,while other N-doped structures do not show a blue-to-red color change.Our results can clarify the origin of the experimental observed blue-to-red color change in lutetium hydride and also provide a further understanding of the potential N-doped lutetium dihydride.展开更多
针对惯性传感器精度低下影响基于激光雷达/惯性信息融合的同时定位与建图(Simultaneous Localization and Mapping,SLAM)技术性能的问题,提出了一种旋转捷联惯导系统辅助下的多线激光雷达SLAM优化方案。该方案探讨了基于模糊自适应卡尔...针对惯性传感器精度低下影响基于激光雷达/惯性信息融合的同时定位与建图(Simultaneous Localization and Mapping,SLAM)技术性能的问题,提出了一种旋转捷联惯导系统辅助下的多线激光雷达SLAM优化方案。该方案探讨了基于模糊自适应卡尔曼滤波的旋转捷联惯导对准方法,在载体运动过程中完成载体姿态与惯性传感器误差的实时修正;在此基础上,将修正后的惯性传感器数据与激光雷达点云数据进行紧耦合模式下的信息融合,以提高载体在复杂场景中运动时定位与建图的精度和实时性。实验结果表明,基于旋转惯导与多线激光雷达信息融合的SLAM方案,在保证运算实时性的同时,有效提高了激光雷达/惯性里程计的定位性能,以及点云地图的准确性。展开更多
基金supported by the National Key Research and Development Program of China(Grant Nos.2022YFA1403203 and 2021YFA1600200)the National Natural Science Foundation of China(Grant Nos.U2032215 and 12241405)。
文摘Recently,near-ambient superconductivity was claimed in nitrogen-doped lutetium hydride(LuH_(3-δ)N_(ε)).Unfortunately,all follow-up research still cannot find superconductivity signs in successfully synthesized lutetium dihydride(LuH_(2)) and N-doped LuH_(2±x)N_(y).However,a similar intriguing observation was the pressure-induced color changes(from blue to pink and subsequent red).The physical understanding of its origin and the correlation between the color,crystal structure,and chemical composition of Lu–H–N is still lacking.In this work,we systematically investigated the optical properties of LuH_(2) and LuH_(3),and the effects of hydrogen vacancies and nitrogen doping using the first-principles calculations by considering both interband and intraband contributions.Our results demonstrate that the evolution of reflectivity peaks near blue and red light,which is driven by changes in the band gap and Fermi velocity of free electrons,resulting in the blue-to-red color change under pressure.In contrast,LuH_(3) exhibits gray and no color change up to 50 GPa.Furthermore,we investigated the effects of hydrogen vacancies and nitrogen doping on its optical properties.Hydrogen vacancies can significantly decrease the pressure of blue-to-red color change in LuH_(2) but do not have a noticeable effect on the color of LuH_(3).The N-doped LuH_(2) with the substitution of a hydrogen atom at the tetrahedral position maintains the color change when the N-doping concentration is low.As the doping level increases,this trend becomes less obvious,while other N-doped structures do not show a blue-to-red color change.Our results can clarify the origin of the experimental observed blue-to-red color change in lutetium hydride and also provide a further understanding of the potential N-doped lutetium dihydride.
文摘针对惯性传感器精度低下影响基于激光雷达/惯性信息融合的同时定位与建图(Simultaneous Localization and Mapping,SLAM)技术性能的问题,提出了一种旋转捷联惯导系统辅助下的多线激光雷达SLAM优化方案。该方案探讨了基于模糊自适应卡尔曼滤波的旋转捷联惯导对准方法,在载体运动过程中完成载体姿态与惯性传感器误差的实时修正;在此基础上,将修正后的惯性传感器数据与激光雷达点云数据进行紧耦合模式下的信息融合,以提高载体在复杂场景中运动时定位与建图的精度和实时性。实验结果表明,基于旋转惯导与多线激光雷达信息融合的SLAM方案,在保证运算实时性的同时,有效提高了激光雷达/惯性里程计的定位性能,以及点云地图的准确性。
