This work presents the results of the Radon (220Rn and 222Rn) measurements made with 486 chips of CR-39 (Allyl Dyglicol Poly Carbonate) MASL? bared detectors, in a reticular mode distribution, inside of a cellar with ...This work presents the results of the Radon (220Rn and 222Rn) measurements made with 486 chips of CR-39 (Allyl Dyglicol Poly Carbonate) MASL? bared detectors, in a reticular mode distribution, inside of a cellar with average indoor radon concentration 862 ± 49 Bq/m3. The exposure time was 3 months, in microclimate condition of constant temperature, humidity, barometric pressure and no airflow. After these 3 months, all the detectors were chemically etched in KOH 6.25 M solution at 60°C ± 1°C for 18 hours, following a very well established protocol for indoor radon survey by the Dosimetry Applications Laboratory of the Physics Institute of the National Autonomous University of Mexico, and later read automatically by CADIS (Counting Automatically Digital Image System). The results show that each one of the nine measured planes is not homogeneous presenting important differences of indoor radon concentration values. Specifically, the Radon (220Rn and 222Rn) concentration levels vary for each measured point within the cellar. It is a very important observation to consider for the calculation of dose and radiological risk.展开更多
为全面分析常导高速磁浮线路轨道系统的研究进展,通过Web of Science、EI、中国知网与万方数据核心数据库检索获取1987~2023年321篇中英文相关文献,涵盖16个国家与地区和59个国内机构;首次利用文献计量方法并借助CiteSpace工具构建科学...为全面分析常导高速磁浮线路轨道系统的研究进展,通过Web of Science、EI、中国知网与万方数据核心数据库检索获取1987~2023年321篇中英文相关文献,涵盖16个国家与地区和59个国内机构;首次利用文献计量方法并借助CiteSpace工具构建科学知识图谱梳理常导高速磁浮线路轨道系统研究进展;基于文献时空分布特点,关键词共现、突现与聚类分析,对领域发展脉络、研究力量、研究主题与热点进行分析总结并可视化展示。研究结果表明:常导高速磁浮线路轨道系统研究经历了发展起步阶段、初步发展阶段,目前正处于高速发展阶段;领域研究热度与重要工程建设和政策支持呈正相关;中国是领域研究的中坚力量,所发表英文研究成果占总体的83.82%;研究核心机构以高校为主,与企业有紧密联系;研究主题主要围绕线路设计优化,轨道梁结构设计,轨道制造和安装技术研究,轨道静力学与动力学性能分析,环境荷载响应分析,系统耦合动力学响应分析,轨道结构检测、监测与维护等7个方向展开;从研究热点上看,以车轨耦合效应、轨道结构检测与监测为主,设计、制造和维护等方面的研究还略显不足。上述计量分析成果表明常导高速磁浮线路轨道系统研究还存在较大提升空间,中国新一代时速600 km高速磁浮交通发展将是提升该领域研究水平的良好契机。展开更多
The integration of Global Navigation Satellite System(GNSS)technology into railway train control systems is a crucial step toward achieving the vision of a digital railway.Traditional train control systems undergo ext...The integration of Global Navigation Satellite System(GNSS)technology into railway train control systems is a crucial step toward achieving the vision of a digital railway.Traditional train control systems undergo extensive in-house tests and prolonged field tests for certification and approval before operational deployment,leading to high costs,delays,and operational disruptions.This paper introduces a GNSS-based train control localization framework which eliminates the need for on-site testing by leveraging train movement dynamics and 3D environment modeling to create a zero on-site testing platform.The proposed framework simulates train movement and the surrounding 3D environment using collected railway line location data and environmental attributes to generate realistic multipath signals and obscuration effects.This approach enables comprehensive laboratory-based case studies for train localization,reducing the huge amount test of needed for physical field trials.The framework is established in house,using the data collected at the Test Base of China Academy of Railway Sciences(Circular Railway).Results from the open area and cutting environment tests demonstrate high localization accuracy repeatability within the simulated environment,validating the feasibility and effectiveness of zero on-site testing for GNSS-based train control systems.This research highlights the potential of GNSS simulation platforms in enhancing cost efficiency,operational safety,and accuracy for future digital railways.展开更多
光伏阵列在局部阴影条件下P-U曲线会出现多个峰值,传统的粒子群优化PSO(particle swarm optimization)算法无法快速精确地搜寻到最大功率点。针对这种情况,本文提出1种基于混沌映射和高斯扰动的改进粒子群优化算法最大功率点跟踪MPPT(ma...光伏阵列在局部阴影条件下P-U曲线会出现多个峰值,传统的粒子群优化PSO(particle swarm optimization)算法无法快速精确地搜寻到最大功率点。针对这种情况,本文提出1种基于混沌映射和高斯扰动的改进粒子群优化算法最大功率点跟踪MPPT(maximum power point tracking)控制策略。首先引入混沌Sine映射构造1种非线性随机递增惯性权重,并在粒子群的“个体认知”部分引入高斯扰动,同时利用对数函数构造学习因子,形成基于混沌映射和高斯扰动的改进粒子群算法;通过对6种典型单峰、多峰函数的测试,证明该算法收敛速度更快,不易陷入局部最优;将算法应用于MPPT控制中,并进一步通过不同算法MPPT控制进行对比仿真研究。对比仿真结果表明:在均匀光照强度、局部静态遮荫和动态遮荫3种情况下,基于混沌映射和高斯扰动的改进粒子群优化算法MPPT控制策略均具有更快的收敛速度和更小的搜索振荡幅度,能准确地搜寻到最大功率点,具有更高的寻优精度,从而提高了MPPT系统的发电效率。展开更多
针对局部遮阴条件下光伏阵列多峰值特性引起的最大功率点跟踪(maximum power point tracking,MPPT)算法容易陷入局部最优等问题,提出基于混沌改进灰狼优化算法与扰动观测法的MPPT算法(CGWO-P&O)。引入混沌映射策略对灰狼种群进行初...针对局部遮阴条件下光伏阵列多峰值特性引起的最大功率点跟踪(maximum power point tracking,MPPT)算法容易陷入局部最优等问题,提出基于混沌改进灰狼优化算法与扰动观测法的MPPT算法(CGWO-P&O)。引入混沌映射策略对灰狼种群进行初始化,增加种群多样性与分布均匀性,均衡灰狼优化算法的全局搜索和局部搜索能力,避免陷入局部最优;利用扰动观测法克服灰狼优化算法搜索速度慢等问题,提高后期对最大功率点的逼近速度。仿真结果表明:CGWO-P&O算法显著提高了对光伏系统最大功率点的跟踪速度和跟踪精度,有效解决了复杂遮阴条件下功率多峰值带来的局部最优等问题。展开更多
文摘This work presents the results of the Radon (220Rn and 222Rn) measurements made with 486 chips of CR-39 (Allyl Dyglicol Poly Carbonate) MASL? bared detectors, in a reticular mode distribution, inside of a cellar with average indoor radon concentration 862 ± 49 Bq/m3. The exposure time was 3 months, in microclimate condition of constant temperature, humidity, barometric pressure and no airflow. After these 3 months, all the detectors were chemically etched in KOH 6.25 M solution at 60°C ± 1°C for 18 hours, following a very well established protocol for indoor radon survey by the Dosimetry Applications Laboratory of the Physics Institute of the National Autonomous University of Mexico, and later read automatically by CADIS (Counting Automatically Digital Image System). The results show that each one of the nine measured planes is not homogeneous presenting important differences of indoor radon concentration values. Specifically, the Radon (220Rn and 222Rn) concentration levels vary for each measured point within the cellar. It is a very important observation to consider for the calculation of dose and radiological risk.
文摘为全面分析常导高速磁浮线路轨道系统的研究进展,通过Web of Science、EI、中国知网与万方数据核心数据库检索获取1987~2023年321篇中英文相关文献,涵盖16个国家与地区和59个国内机构;首次利用文献计量方法并借助CiteSpace工具构建科学知识图谱梳理常导高速磁浮线路轨道系统研究进展;基于文献时空分布特点,关键词共现、突现与聚类分析,对领域发展脉络、研究力量、研究主题与热点进行分析总结并可视化展示。研究结果表明:常导高速磁浮线路轨道系统研究经历了发展起步阶段、初步发展阶段,目前正处于高速发展阶段;领域研究热度与重要工程建设和政策支持呈正相关;中国是领域研究的中坚力量,所发表英文研究成果占总体的83.82%;研究核心机构以高校为主,与企业有紧密联系;研究主题主要围绕线路设计优化,轨道梁结构设计,轨道制造和安装技术研究,轨道静力学与动力学性能分析,环境荷载响应分析,系统耦合动力学响应分析,轨道结构检测、监测与维护等7个方向展开;从研究热点上看,以车轨耦合效应、轨道结构检测与监测为主,设计、制造和维护等方面的研究还略显不足。上述计量分析成果表明常导高速磁浮线路轨道系统研究还存在较大提升空间,中国新一代时速600 km高速磁浮交通发展将是提升该领域研究水平的良好契机。
基金supported by the National Natural Science Foundation of China(62027809,U2268206,T2222015,U2468202).
文摘The integration of Global Navigation Satellite System(GNSS)technology into railway train control systems is a crucial step toward achieving the vision of a digital railway.Traditional train control systems undergo extensive in-house tests and prolonged field tests for certification and approval before operational deployment,leading to high costs,delays,and operational disruptions.This paper introduces a GNSS-based train control localization framework which eliminates the need for on-site testing by leveraging train movement dynamics and 3D environment modeling to create a zero on-site testing platform.The proposed framework simulates train movement and the surrounding 3D environment using collected railway line location data and environmental attributes to generate realistic multipath signals and obscuration effects.This approach enables comprehensive laboratory-based case studies for train localization,reducing the huge amount test of needed for physical field trials.The framework is established in house,using the data collected at the Test Base of China Academy of Railway Sciences(Circular Railway).Results from the open area and cutting environment tests demonstrate high localization accuracy repeatability within the simulated environment,validating the feasibility and effectiveness of zero on-site testing for GNSS-based train control systems.This research highlights the potential of GNSS simulation platforms in enhancing cost efficiency,operational safety,and accuracy for future digital railways.
文摘光伏阵列在局部阴影条件下P-U曲线会出现多个峰值,传统的粒子群优化PSO(particle swarm optimization)算法无法快速精确地搜寻到最大功率点。针对这种情况,本文提出1种基于混沌映射和高斯扰动的改进粒子群优化算法最大功率点跟踪MPPT(maximum power point tracking)控制策略。首先引入混沌Sine映射构造1种非线性随机递增惯性权重,并在粒子群的“个体认知”部分引入高斯扰动,同时利用对数函数构造学习因子,形成基于混沌映射和高斯扰动的改进粒子群算法;通过对6种典型单峰、多峰函数的测试,证明该算法收敛速度更快,不易陷入局部最优;将算法应用于MPPT控制中,并进一步通过不同算法MPPT控制进行对比仿真研究。对比仿真结果表明:在均匀光照强度、局部静态遮荫和动态遮荫3种情况下,基于混沌映射和高斯扰动的改进粒子群优化算法MPPT控制策略均具有更快的收敛速度和更小的搜索振荡幅度,能准确地搜寻到最大功率点,具有更高的寻优精度,从而提高了MPPT系统的发电效率。
文摘针对局部遮阴条件下光伏阵列多峰值特性引起的最大功率点跟踪(maximum power point tracking,MPPT)算法容易陷入局部最优等问题,提出基于混沌改进灰狼优化算法与扰动观测法的MPPT算法(CGWO-P&O)。引入混沌映射策略对灰狼种群进行初始化,增加种群多样性与分布均匀性,均衡灰狼优化算法的全局搜索和局部搜索能力,避免陷入局部最优;利用扰动观测法克服灰狼优化算法搜索速度慢等问题,提高后期对最大功率点的逼近速度。仿真结果表明:CGWO-P&O算法显著提高了对光伏系统最大功率点的跟踪速度和跟踪精度,有效解决了复杂遮阴条件下功率多峰值带来的局部最优等问题。
文摘针对传统SLAM算法特征跟踪匹配时效过低,光流与特征点融合算法跟踪精度较差以及机器人曲线运动时易选取到图像质量较差的关键帧导致系统定位精度较低等问题,提出一种曲线运动下基于关键帧补偿决策的快速SLAM算法(Fast Simultaneous Localization and Mapping,FA-SLAM)。该算法将LK光流与ORB特征点进行融合,通过在光流跟踪中实行双阈值约束自适应特征匹配策略,减少计算冗余,快速计算相机位姿,提高了系统实时性与跟踪精度。与此同时,为避免机器人曲线运动时易选取到图像质量较差的关键帧,导致系统定位精度不足,提出一种重新定义图像质量的关键帧补偿决策,通过判定当前帧活跃特征点的数量选取高质量的图像作为活跃关键帧,提高机器人的定位精度。将该算法在TUM公开数据集上进行测试,结果表明该算法相比ORB-SLAM2运行时间减少了43.1%,绝对轨迹误差缩小了31.8%。
