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Comparison and analysis of unmodelled errors in GPS and BeiDou signals

Geodesy and Geodynamics 2017年第1期8卷 41-48页

作者： zhetao zhang Bofeng Li Yunzhong Shen College of Surveying and Geo-lnformatics Tongji University Shanghai 200092 China

In Global Navigation Satellite Systems （GNSS） positioning, one often tries to establish a mathematic model to capture the systematic behaviors of observations as much as possible. However, the observation residuals still exhibit, to a great extent, as （somewhat systematic） signals. Nevertheless, those systematic variations are referred to as the unmodelled errors, which are difficult to be further modelled by setting up additional parameters. Different from the random errors, the unmodelled errors are colored and time correlated. In general, the larger the time correlations are, the more significant the unmodelled errors. Hence, understanding the time correlations of unmodelled errors is important to develop the theory for processing the unmodelled errors. In this study, we compare and analyze the time correlations caused by unmodelled errors of Global Positioning System （GPS） and BeiDou signals. The time correlations are estimated based on the residuals of double differenced observations on 11 baselines with different lengths. The results show that the time correlation patterns are different significantly between GPS and BeiDou observations. Besides, the code and phase data from the same satellite system are also not the same. Furthermore, the unmodelled errors are affected by not only the baseline length, but also some other factors. In addition, to make use of the time correlations with more efficiency, we propose to fit the time correlations by using exponent and quadratic models and the fitting coefficients are given. Finally, the sequential adjustment method considering the time correlations is implemented to compute the baseline solutions. The results show that the solutions considering the time correlations can objectively reflect the actual precisions of parameter estimates.

关键词： GPSBeiDouUnmodelled errorTime correlationPrecise positioning

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Properties of multi‑GNSS uncalibrated phase delays with considering satellite systems,receiver types,and network scales

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Satellite Navigation 2023年第3期4卷 92-106页

作者： Ping Zeng zhetao zhang Yuanlan Wen Xiufeng He Lina He Muzi Li Wu Chen School of Earth Sciences and Engineering Hohai UniversityNanjing 211100China Shanghai Aerospace Control Technology Institute Shanghai 201109China Department of Land Surveying and Geo‑Informatics The Hong Kong Polytechnic UniversityHong KongChina

The Wide-Lane(WL)and Narrow-Lane(NL)Uncalibrated Phase Delays(UPDs)are the prerequisites in the traditional Precise Point Positioning(PPP)Ambiguity Resolution(AR).As the generation mechanism of various biases becomes more complex,we systematically studied the impact factors of four satellite systems WL and NL UPDs from the perspective of parameter *** 100 stations in a global network are used to generate the *** results of different satellite systems show that the estimation method,update frequency,and solution mode need to be treated *** regional networks with different receiver types,JAVAD,and Trimble,are also *** results indicate that the receiver-dependent bias has an influence on UPD ***,the hardware delays can inhibit the satellite-side UPDs if these receiver-specific errors are not fully deployed or even ***,the temporal stability and residual distribution of NL UPDs are significantly enhanced by utilizing a regional network,with the improvements by over 68%and 40%,*** demonstrates that different network scales exhibit the different implication of unmodeled errors,and the unmodeled errors cannot be ignored and must be handled in UPD estimation.

关键词： WL UPD NL UPD Satellite system Receiver type Network scale

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“1+X”网格化模式在审方药师药学服务胜任力培养中的应用和实践

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安徽医药 2025年第1期29卷 200-205页

作者：马旖旎张哲弢邓晓媚张理想张瑾史天陆中国科学技术大学附属第一医院(安徽省立医院)药学部安徽合肥230001 中国科学技术大学附属第一医院(安徽省立医院)心血管内科安徽合肥230001 精准药物制剂与临床药学安徽省重点实验室安徽合肥230001

目的通过建立规范、系统、可行的培训方法和课程体系,探索以临床药师为核心的审方药师培养与实践新模式,为各级医疗机构处方审核药师培训考核机制建设提供参考。方法从专业、团队、工作三个层面构建“1+X”网格化处方审核药师培养模式,... 详细信息

目的通过建立规范、系统、可行的培训方法和课程体系,探索以临床药师为核心的审方药师培养与实践新模式,为各级医疗机构处方审核药师培训考核机制建设提供参考。方法从专业、团队、工作三个层面构建“1+X”网格化处方审核药师培养模式,利用合理用药分析软件,分析评价中国科学技术大学附属第一医院2022年1—10月“1+X”处方审核模式应用效果;并采用李克特量表,设定审方药师自我评价满意度水平,据此设计问卷调查表,进行审方药师培训前后药学服务胜任力的自我评定。结果经过“1+X”网格化模式培训后,审方药师已成功优化审方规则225条,药师每月审核处方比例从5.24%降至2.56%,药师每月干预处方比例从19.32%降至11.17%,医师修改处方数、药师干预有效的处方数、整体用药错误上报率等明显下降,审方工作效率提升;审方药师在个人素养、基本知识和技能、专业知识和技能、内驱力方面均得到了不同程度的提升(P<0.05)。结论“1+X”工作模式应用效果显著、易推广,可提高药师核心胜任力,保障用药安全,契合当前政策和实际工作的需要。

关键词：胜任力处方审核药师培养 “1+X”模式临床药师

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Several Kinematic Data Processing Methods for Time-Correlated Observations

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Journal of Geodesy and Geoinformation Science 2019年第4期2卷 1-9页

作者： Bofeng LI zhetao zhang College of Surveying and GeoInformatics Tongji UniversityShanghai 200092China School of Earth Sciences and Engineering Hohai UniversityNanjing 211100China

Time correlations always exist in modern geodetic data,and ignoring these time correlations will affect the precision and reliability of *** this paper,several methods for processing kinematic time-correlated observations are ***,the method for processing the time-correlated observations is expanded and *** on the theory of maximum a posteriori estimation,the third idea is proposed after the decorrelation transformation and differential *** types of situations with and without common parameters are both investigated by using the decorrelation transformation,differential transformation and maximum a posteriori estimation ***,the characteristics and equivalence of above three methods are ***,in order to balance the computational efficiency in real applications and meantime effectively capture the time correlations,the corresponding reduced forms based on the autocorrelation function are ***,with GPS real data,the correctness and practicability of derived formulae are evaluated.

关键词： time correlation kinematic solution decorrelation transformation differential transformation maximum a posteriori estimation

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Cav3.2 channel regulates cerebral ischemia/reperfusion injury:a promising target for intervention

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Neural Regeneration Research 2024年第11期19卷 2480-2487页

作者： Feibiao Dai Chengyun Hu Xue Li zhetao zhang Hongtao Wang Wanjun Zhou Jiawu Wang Qingtian Geng Yongfei Dong Chaoliang Tang Graduate School Wannan Medical CollegeWuhuAnhui ProvinceChina Department of Anesthesiology The First Affiliated Hospital of USTCDivision of Life Sciences and MedicineUniversity of Science and Technology of ChinaHefeiAnhui ProvinceChina Core Facility Center for Medical Sciences The First Affiliated Hospital of USTC(Anhui Provincial Hospital)HefeiAnhui ProvinceChina Department of Pharmacy The First Affiliated Hospital of USTCDivision of Life Sciences and MedicineUniversity of Science and Technology of ChinaHefeiAnhui ProvinceChina Department of Neurosurgery The First Affiliated Hospital of USTCDivision of Life Sciences and MedicineUniversity of Science and Technology of ChinaHefeiAnhui ProvinceChina

Calcium influx into neurons triggers neuronal death during cerebral ischemia/reperfusion *** calcium channels are involved in cerebral ischemia/reperfusion ***3.2 channel is a main subtype of T-type calcium channels.T-type calcium channel blockers,such as pimozide and mibefradil,have been shown to prevent cerebral ischemia/reperfusion injury-induced brain ***,the role of Cav3.2 channels in cerebral ischemia/reperfusion injury remains ***,in vitro and in vivo models of cerebral ischemia/reperfusion injury were established using middle cerebral artery occlusion in mice and high glucose hypoxia/reoxygenation exposure in primary hippocampal *** results showed that Cav3.2 expression was significantly upregulated in injured hippocampal tissue and primary hippocampal *** further established a Cav3.2 gene-knockout mouse model of cerebral ischemia/reperfusion ***3.2 knockout markedly reduced infarct volume and brain water content,and alleviated neurological dysfunction after cerebral ischemia/reperfusion ***,Cav3.2 knockout attenuated cerebral ischemia/reperfusion injury-induced oxidative stress,inflammatory response,and neuronal *** the hippocampus of Cav3.2-knockout mice,calcineurin overexpression offset the beneficial effect of Cav3.2 knockout after cerebral ischemia/reperfusion *** findings suggest that the neuroprotective function of Cav3.2 knockout is mediated by calcineurin/nuclear factor of activated T cells 3 *** from this study suggest that Cav3.2 could be a promising target for treatment of cerebral ischemia/reperfusion injury.

关键词： calcineurin Cav3.2 channel cerebral ischemia/reperfusion hippocampus hypoxia/reoxygenation inflammatory response nuclear factor of activated T cells 3 oxidative stress primary hippocampal neurons stroke

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时间相关观测的几种动态数据处理方法

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测绘学报 2018年第12期47卷 1563-1570页

作者：李博峰章浙涛同济大学测绘与地理信息学院上海200092

现代大地测量数据中往往存在时间相关性,忽略观测值时间相关性会影响参数估值的精度和可靠性。因此,本文研究了几种时间相关观测的动态数据处理方法。首先,对观测值时间相关性的处理方法进行了扩展和统一。利用极大验后估计原理,提出了... 详细信息

现代大地测量数据中往往存在时间相关性,忽略观测值时间相关性会影响参数估值的精度和可靠性。因此,本文研究了几种时间相关观测的动态数据处理方法。首先,对观测值时间相关性的处理方法进行了扩展和统一。利用极大验后估计原理,提出了第3种思路,并在无历元公用参数和有历元公用参数两类模型下,详细推导了去相关变换法、差分变换法和极大验后估计法这3种思路的动态解,并对它们的特点和等价性进行了论证。其次,为了平衡实际应用中的解算效率且同时有效顾及时间相关性,利用自相关函数表达时间相关性,导出了相应退化形式。最后,通过GPS实测数据验证了本文理论公式的正确性和实用性。

关键词：时间相关动态解去相关变换差分变换极大验后估计

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大坝变形变系数回归建模

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武汉大学学报（信息科学版） 2015年第1期40卷 139-142页

作者：卢骏戴吾蛟章浙涛中南大学测绘与国土信息工程系湖南长沙410083 湖南省精密工程测量与形变灾害监测重点实验室湖南长沙410083 湖南地科资源利用工程设计有限公司湖南长沙410007

在变形分析建模中常采用回归分析建模,但普通的回归模型是一种静态的模型,当变形体结构或物理性质发生变化时,普通线性回归所建立的静态模型将不再适用。变系数回归模型是一种动态模型,有着更强的灵活性和适应性,因此,将变系数回归引入... 详细信息

在变形分析建模中常采用回归分析建模,但普通的回归模型是一种静态的模型,当变形体结构或物理性质发生变化时,普通线性回归所建立的静态模型将不再适用。变系数回归模型是一种动态模型,有着更强的灵活性和适应性,因此,将变系数回归引入大坝变形分析建模中,采用局部线性估计的方法进行系数拟合。仿真和大坝变形建模实验表明,变系数回归得到的大坝变形模型优于普通的线性回归模型,预测精度更高。

关键词：变系数回归模型局部线性估计回归分析变形建模

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Combined Processing of Outlier and Multipath in GNSS Precise Point Positioning

Combined Processing of Outlier and Multipath in GNSS Precise...

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第十四届中国卫星导航年会

作者： Haijun Yuan Xiufeng He zhetao zhang Hohai University

The Global Navigation Satellite System(GNSS) precise point positioning(PPP) technology is inevitably affected by outlier and multipath,especially under complex environments. Based on the idea of robust estimation and multipath detection, a combined processing method considering the outlier and multipath simultaneously is proposed for GNSS PPP in this study. The GNSS observations in real complex environments were used to conduct the kinematic PPP experiment. Besides, the PPP positioning performance is carefully compared and analyzed among without the outlier and multipath processing, the traditional outlier processing, and the combined outlier and multipath processing. The results show that the proposed processing method can improve the positioning performance for GNSS PPP. Compared with the traditional outlier processing, the positioning accuracy of the proposed method is improved by 20.3%, 49.2% and 13.6% in E, N, and U directions,respectively. Hence, the proposed method considering both the outlier and multipath can effectively improve the PPP positioning performance, especially under complex environments.

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结合正态分布变换与线面ICP的弹性激光SLAM算法

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武汉大学学报（信息科学版） 2024年第4期49卷 672-680页

作者：王彬章浙涛何秀凤河海大学地球科学与工程学院江苏南京211100

激光雷达(light detection and ranging,LiDAR)同时定位与建图(simultaneous localization and mapping,SLAM)中的位姿估计依赖于高精度和高可靠性的扫描匹配算法。针对实时LiDAR里程计与建图(LiDAR odometry and mapping in real-time,LOAM)框架中的点到线和点到面的迭代最近点算法(iterative closest point,ICP)在非结构化场景中退化的问题,提出了用于识别非结构化场景的环境特征值(environmental feature values,EFV),并根据EFV弹性地选择用正态分布变换(normal distributions transform,NDT)进行粗配准,实现了一种基于扫描匹配的弹性实时激光SLAM算法NDT-LOAM。实验结果表明,EFV可以有效区分非结构化场景,并给出了EFV阈值的调试方法。定位与建图实验分析表明,所提算法相比LOAM等经典的纯激光SLAM算法,在精度以及可靠性上均有较大提升,室外定位精度可从米级提升至分米级,在面对手持数据时也不会建图失败,能够得到全局一致性地图。因此此算法具有很好的环境适应性,丰富和发展了面向复杂环境的SLAM方法。

关键词： LiDAR SLAM 扫描匹配 NDT 线面ICP 弹性系统

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交流电场下变压器油中贴壁气泡形变特性

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高电压技术 2024年第2期50卷 816-824页

作者：张哲滔张锐郭冲张乔根西安交通大学电工材料电气绝缘全国重点实验室西安710049

气泡是油纸绝缘系统的典型缺陷,会显著地降低变压器油的绝缘性能。为了明晰气泡对油纸绝缘系统的危害,搭建了油中贴壁气泡动力学观测平台,研究吸附于电极表面的气泡在交流电场中的形变特性及影响规律。结果发现:油中贴壁气泡沿电场方向... 详细信息

气泡是油纸绝缘系统的典型缺陷,会显著地降低变压器油的绝缘性能。为了明晰气泡对油纸绝缘系统的危害,搭建了油中贴壁气泡动力学观测平台,研究吸附于电极表面的气泡在交流电场中的形变特性及影响规律。结果发现:油中贴壁气泡沿电场方向拉伸并以100 Hz的频率进行脉动变形;随着电场强度、气泡半径和温度的增大,气泡的变形程度也逐渐增大。基于相场方法搭建了气液两相流仿真模型,仿真与实验结果相互验证,揭示了气泡变形的本质为电场力和表面张力作用的平衡。气泡会影响油隙电场分布,其内部场强随气泡沿电场方向的拉伸而降低。该文研究可为深入评估气泡对液体绝缘的危害和变压器的绝缘设计提供参考。

关键词：变压器油交流电场贴壁气泡形变特性相场方法

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