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Review of PPP-RTK:achievements,challenges,and opportunities

Satellite Navigation 2022年第3期3卷 16-37,I0002页

作者： Xingxing Li Jiaxin Huang Xin Li Zhiheng Shen Junjie Han Linyang Li Bo wang School of Geodesy and Geomatics Wuhan University129 Luoyu RoadWuhan430079HubeiChina Technische Universitat Berlin(TUB) Straße Des 17.Juni10623BerlinGermany China Railway Siyuan Survey and Design Group Co. Ltd.WuhanChina

The PPP–RTK method,which combines the concepts of Precise of Point Positioning(PPP)and Real-Time Kinematic(RTK),is proposed to provide a centimeter-accuracy positioning service for an unlimited number of ***,the PPP–RTK technique is becoming a promising tool for emerging applications such as autonomous vehicles and unmanned logistics as it has several advantages including high precision,full flexibility,and good *** paper gives a detailed review of PPP–RTK focusing on its implementation methods,recent achievements as well as challenges and ***,the fundamental approach to implement PPP–RTK is described and an overview of the research on key techniques,such as Uncalibrated Phase Delay(UPD)estimation,precise atmospheric correction retrieval and modeling,and fast PPP ambiguity resolution,is ***,the recent efforts and progress are addressed,such as improving the performance of PPP–RTK by combining multi-GNSS and multi-frequency observations,single-frequency PPP–RTK for low-cost devices,and PPP–RTK for vehicle ***,the system construction and applications based on the PPP–RTK method are ***,the main issues that impact PPP–RTK performance are highlighted,including signal occlusion in complex urban areas and atmosphere modeling in extreme weather *** new opportunities brought by the rapid development of low-cost markets,multiple sensors,and new-generation Low Earth Orbit(leo)navigation constellation are also ***,the paper concludes with some comments and the prospects for future research.

关键词： PPP–RTK Ambiguity resolution Multi-GNSS Smart device Multi-sensor fusion

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Study on volt-ampere characteristics of solar array arcs in leo spacecraft

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Plasma Science and Technology 2019年第2期21卷 39-46页

作者： Liying ZHU Zhigang LIU Xiaofeng ZHANG Chao wang Xiaofei LI Institute of Spacecraft System Engineering CAST

The primary and secondary arcs volt-ampere characteristics of low earth orbit solar arrays are studied in this research. Using three gallium-arsenide solar cell samples, the gap lengths of the solar cell are set to 1, 2, and 3 mm. First, the primary arc voltage characteristics of a solar array are analyzed. It is found that two steps are involved in the primary arc voltages, which are 116 and 22 V according to our experiment and are independent of the electrostatic discharge current and the gap lengths. By comparing with the arc pattern, we determined that current chopping may be the reason for the stepped arc voltage. Then, the characteristics of the secondary arc of the solar array are demonstrated. The study shows that the secondary arc voltage values increase with the gap length. In the case of the same cell with a fixed gap length, the voltage of the secondary arc increases with the string current. Finally, the relationship between the secondary arc voltage and the gap length is obtained which helps the string voltage and the gap length selection for system design.

关键词： primary arc secondary arc solar array

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New dynamic routing algorithm based on MANET in the leo/MEO satellite network

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Frontiers of Electrical and Electronic Engineering in China 2006年第2期1卷 164-170页

作者： LI Zhe LI Dong-ni wang Guang-xing Research Center for Network and Communication of Northeastern University Shenyang 11004China

The features of low earth orbit/medium earth orbit(leo/MEO)satellite networks routing algorithm based on inter-satellite link are analyzed and the similarities between satellite networks and mobile Ad Hoc network(MANET)are pointed *** similar parts in MANET routing protocol are used in the satellite network for reference.A new dynamic routing algorithm based on MANET in leo/MEO satellite networks,which fits for the leo/MEO satellite communication system,is *** the same time,the model of the algorithm is simulated and features are *** is shown that the algorithm has strong *** can give the network high autonomy,perfect function,low system overhead and great compatibility.

关键词： Computer application technology leo/MEO satellite network MANET Inter-satellite link(ISL) Cluster

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基于深度学习的毫米波和亚毫米波成像仪的图像增强技术

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上海航天 2018年第2期35卷 13-19页

作者：胡伟东张文龙安大伟王璐陈实岳芬 LIGTHART leo P. 北京理工大学北京100081 国家卫星气象中心北京100142 代尔夫特理工大学

风云四号卫星毫米波和亚毫米波成像仪(MMSI)数据根据采样方式分为过采样和非过采样数据。由于采样方式的影响,非过采样数据在采样过程中会有一定的信息损失。为解决采用简单的线性插值方法做精细化处理时提升精度有限问题,采用基于深度... 详细信息

风云四号卫星毫米波和亚毫米波成像仪(MMSI)数据根据采样方式分为过采样和非过采样数据。由于采样方式的影响,非过采样数据在采样过程中会有一定的信息损失。为解决采用简单的线性插值方法做精细化处理时提升精度有限问题,采用基于深度学习的方法增强MMSI亮温图像,设计卷积神经网络重建风云四号卫星MMSI的亮温图像和风云三号卫星微波成像仪亮温图像。实验结果显示:相比传统的双三次插值方法,在风云三号卫星微波成像仪亮温图像样本上峰值信噪比提升了1.13dB,结构相似度提升了0.01。实验结果表明:对于非过采样亮温数据,采用基于深度学习的方法增强图像具有更高的精度,同时可在其他微波探测仪数据中使用,具有很强的普适性。

关键词：超分辨率卷积神经网络双三次插值毫米波和亚毫米波成像仪图像增强非过采样数据亮温图像

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低轨倾斜轨道卫星太阳电池阵防遮挡设计与分析

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航天器工程 2024年第1期33卷 36-41页

作者：苏宝法仇恒抗王凯宋园李沐昀丁丕满马聚沙曹程上海空间电源研究所上海200245 上海卫星工程研究所上海200245

低轨倾斜轨道卫星轨道面光照角周期变化,太阳电池阵受照情况复杂,其输出电流呈现波动。为此,文章分析卫星各种工况下的本体遮挡面积,结合太阳电池阵遮挡工作特性分析及阴影遮挡试验结果,开展太阳电池阵防阴影遮挡设计,并采用投影法进行... 详细信息

低轨倾斜轨道卫星轨道面光照角周期变化,太阳电池阵受照情况复杂,其输出电流呈现波动。为此,文章分析卫星各种工况下的本体遮挡面积,结合太阳电池阵遮挡工作特性分析及阴影遮挡试验结果,开展太阳电池阵防阴影遮挡设计,并采用投影法进行卫星本体遮挡影响分析。结果表明:卫星本体遮挡时,电流损失预计值与在轨遥测电流损失值基本一致,分析误差小于2%。上述分析结果可为卫星复杂遮挡工况下电源系统能量平衡设计提供参考。

关键词：低轨倾斜轨道卫星卫星本体遮挡太阳电池阵输出电流

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Dietary Litsea cubeba essential oil supplementation improves growth performance and intestinal health of weaned piglets

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Animal Nutrition 2023年第2期13卷 9-18页

作者： Zhe Yang Fang wang Yexin Yin Peng Huang Qian Jiang Zhimou Liu Yulong Yin Jiashun Chen Animal Nutritional Genome and Germplasm Innovation Research Center College of Animal Science and TechnologyHunan Agricultural UniversityChangshaHunan410128China CAS Key Laboratory of Agro Ecological Processes in Subtropical Region Institute of Subtropical AgricultureChangshaHunan410125China Hunan Nuoz Biological Technology Co. Ltd.YiyangHunan413056China

This paper was to determine the effects of dietary Litsea cubeba essential oil(leo)supplementation on growth performance,immune function,antioxidant level,intestinal morphology and microbial composition in weaned *** hundred and ninety-two piglets(Duroc×[Large White×Landrace])with 6.85±0.22 kg mean body weight weaned at 21 d of age were randomly assigned to 4 treatment groups with 8 replicates and were fed with a basal diet(CON)or CON diet containing 100(Lleo),200(Mleo)and 400(Hleo)mg/kg *** results revealed that Hleo supplementation(Pleo supplementation decreased(Pleo increased(Pleo and Hleo resulted in higher(Pleo increased(Pleo and Hleo decreased(Pleo group,and the villus height to crypt depth ratio in the jejunum was also improved(Pleo *** addition of leo increased(Pleo increased(Pleo supplementation improved growth performance and intestinal health in weaned piglets.

关键词： Litsea cubeba Growth performance Intestinal health Microbial composition Essential oil Weaned piglet

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低轨卫星短突发通信时频同步算法

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无线电工程 2024年第10期54卷 2488-2493页

作者：张庆业王力男贾慧燕李燕卢向雨中国电子科技集团公司第五十四研究所河北石家庄050081 航天系统部装备部军事代表局驻石家庄军事代表室河北石家庄050081 武警工程大学信息工程学院陕西西安710086

低轨卫星短突发通信具有多普勒频偏和多普勒变化率较大、突发符号较短和突发信号导频长度受限等特点,采用传统的时频同步算法在低信噪比条件下性能较差。为了提高时间同步和频偏估计性能,准确完成同步过程,基于时分多址(Time Division M... 详细信息

低轨卫星短突发通信具有多普勒频偏和多普勒变化率较大、突发符号较短和突发信号导频长度受限等特点,采用传统的时频同步算法在低信噪比条件下性能较差。为了提高时间同步和频偏估计性能,准确完成同步过程,基于时分多址(Time Division Multiple Access,TDMA)接入帧结构提出一种新的时频同步算法。该算法采用二维搜索算法进行整数倍的时延估计和粗频偏估计;在补偿大频偏和整数倍时延后,估计小数倍时延;采用结合低通滤波的快速傅里叶变换(Fast Fourier Transform,FFT)算法进行精频偏估计。仿真结果表明,每符号能量与噪声功率谱密度比值(Ratio of Symbol Energy to Noise Power Spectral Density,E_(s)/N_(0))为4.5 dB时,时延检测概率准确率达到99.99%,整体解调性能相较于M&M等算法有2 dB以上的性能提升。

关键词：低轨卫星短突发通信时分多址时频同步

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一种时延能耗感知的在轨边缘计算任务卸载调度方法

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计算机科学 2024年第S1期51卷 742-750页

作者：王众晓彭青蓝孙若骁徐锡峰郑万波夏云霓河南大学人工智能学院郑州475004 重庆大学计算机学院重庆400044 昆明理工大学理学院昆明650031

全球智能设备的迅速增长引发了对计算资源下沉至边缘的巨大需求,催生了边缘计算范式的出现。同时,计算资源稀缺的偏远地区用户对算力的需求又推动了在轨边缘计算(Orbit Edge Computing,OEC)概念的提出和发展。在OEC场景下,偏远地区用户... 详细信息

全球智能设备的迅速增长引发了对计算资源下沉至边缘的巨大需求,催生了边缘计算范式的出现。同时,计算资源稀缺的偏远地区用户对算力的需求又推动了在轨边缘计算(Orbit Edge Computing,OEC)概念的提出和发展。在OEC场景下,偏远地区用户可以通过星地和星间通信链路将计算任务卸载至部署在低轨卫星上的边缘服务器,以此突破地面计算通信基础设施的限制,为偏远地区的用户提供低时延和高可靠的服务。然而,OEC场景中卫星算力受有限载荷和太阳能转化效率约束,同时还存在低轨卫星绕地导致的高度动态的星地连接造成的可用时隙有限的限制,面临着计算资源稀缺和可用通信时间有限所带来的挑战。因此,需要高质高效的任务卸载决策算法来保证OEC系统的高效运行。然而,目前在OEC场景下任务卸载方法大多在处理任务时无法兼顾计算任务卸载时延与能耗,此外传统方法还缺少对任务多样性的考量。针对上述问题,提出了一种基于自适应大邻域搜索的在轨边缘计算任务卸载方法OEC-ALNS,该方法以任务类型加权的任务处理成本为优化目标,并针对性地提出了基于最小化时延的破坏算子和修复算子来进一步提升搜索效率和卸载调度质量。基于Walker Delta低轨卫星星座和真实计算任务数据的实验结果表明,与传统的OEC-TA(OEC Task Allocation)方法相比,提出的OEC-ALNS方法在多个任务集异构的OEC场景中最多能够减少42.22%的加权任务处理成本和降低42.46%的平均时延。

关键词：在轨边缘计算低轨卫星星座计算任务卸载自适应大邻域搜索

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A Lightweight Deep Learning-Based Algorithm for Array Imperfection Correction and DOA Estimation

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Journal of Communications and Information Networks 2022年第3期7卷 296-308页

作者： Wenwei Fang Zhihui Cao Dingke Yu Xin wang Zixian Ma Bing Lan Chunyi Song Zhiwei Xu Institute of Marine Electronic and Intelligent System Ocean CollegeZhejiang UniversityZhoushan 316021China Engineering Research Center of Oceanic Sensing Technology and Equipment Ministry of EducationZhoushan 316021China Donghai Lab Zhoushan 316021China

Array imperfections will lead to serious performance degradation of the deep neural network(DNN)based direction of arrival(DOA)estimation in the low earth orbit(leo)satellite communication by producing a mismatch between inference data and training *** this paper,we propose a lightweight deep learning-based algorithm for array imperfection correction and DOA *** preprocessing the covariance matrix of the array antenna outputs to the image,the array imperfection correction and DOA estimation problems are correspondingly converted into the image-to-image transformation task and image recognition ***,for the deployment of real-time DNN-based DOA estimation on the resource-constrained edge system,generative adversarial network(GAN)model compression is applied to obtain a lightweight student generator of Pix2Pix for array imperfection *** Mobilenet-V2 is then used to extract the DOA information from the covariance matrix *** results demonstrate that the DOA estimation performance is significantly improved through the array imperfection *** proposed algorithm also better satisfies the real-time demand with decreased inference time on the resource-constrained edge system.

关键词： deep learning array imperfection DOA estimation model compression edge-AI

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The status and development proposal of carbon sources and sinks monitoring satellite system

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碳中和(英文) 2022年第1期1卷 153-170页

作者： Guang Meng Yuan Wen Miaomiao Zhang Yilei Gu Wei Xiong Zijun wang Shengda Niu Shanghai Academy of Spaceflight Technology ShanghaiChina Shanghai Jiao Tong University ShanghaiChina Shanghai Institute of Satellite Engineering ShanghaiChina Anhui Institute of Optical Fine Mechanics HefeiChina

In order to mitigate global warming,the international communities actively explore low-carbon and green development *** to the Paris Agreement that came into effect in 2016,there will be a global stocktaking plan to carry out every 5 years from 2023 *** September 2020,China proposed a"double carbon"target of carbon peaking before 2030 and carbon neutrality before *** carbon peaking and carbon neutrality goals requires accurate carbon emissions and carbon ***’s existing carbon monitoring methods have insufficient detection accuracy,low spatial resolution,and narrow swath,which are difficult to meet the monitoring requirement of carbon sources and sinks *** order to meet the needs of carbon stocktaking and support the monitoring and supervision of carbon sources and sinks,it is recommended to make full use of the foundation of the existing satellites,improve the detection technical specifications of carbon sources and sinks monitoring measures,and build a multi-means and comprehensive,leo-GEO orbit carbon monitoring satellite system to achieve higher precision,higher resolution and multi-dimensional carbon *** this basis,it is recommended to strengthen international cooperation,improve data sharing policy,actively participate in the development of carbon retrieval algorithm and the setting of international carbon monitoring standards,establish an independent and controllable global carbon monitoring and evaluation system,and contribute China’s strength to the global realization of carbon peaking and carbon neutrality.

关键词： Carbon sources and sinks Greenhouse gases Carbon monitoring system Carbon neutrality Carbon stocktaking

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