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粘结剂处理的铁基混合粉的温压特性

粉末冶金技术 2005年第3期23卷 195-198页

作者：王尚林倪东惠陈维平潘国如李元元金属新材料制备与成形广东省重点试验室华南理工大学机械工程学院广州510640

研究的目标是结合粉末粘结技术和温压技术以制备高质量、高性能的粉末冶金材料。预粘结粉末的一大优点是能有效地降低成分偏析,因此在混粉过程中应尽量避免偏聚。本文采用两种混粉工艺制备预粘结铁基混合粉,通过不同的压制压力、不同的... 详细信息

研究的目标是结合粉末粘结技术和温压技术以制备高质量、高性能的粉末冶金材料。预粘结粉末的一大优点是能有效地降低成分偏析,因此在混粉过程中应尽量避免偏聚。本文采用两种混粉工艺制备预粘结铁基混合粉,通过不同的压制压力、不同的粘结剂含量以常温压制和温压压制制备出铁基粉末冶金材料,测量其压坯密度并进行比较分析。研究结果表明,不同预粘结工艺、压制温度和粘结剂含量对压坯密度影响很大。在一定的粘结剂含量范围内,生坯密度随粘结剂含量增加而呈线性减少。不同的预粘结工艺对生坯密度的影响随着粘结剂含量的增加而增大。

关键词：铁基混合粉粘结剂铁基粉末冶金材料压坯密度粘结工艺生坯密度温压技术粘结技术成分偏析压制压力比较分析研究结果压制温度含量范围制备混粉

An optimal design of the broadcast ephemeris for leo navigation augmentation systems

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Geo-Spatial Information Science 2022年第1期25卷 34-46页

作者： Xueli Guo Lei wang Wenju Fu Yingbo Suo Ruizhi Chen Hongxing Sun State Key Laboratory of Information Engineering in Surveying Mapping and Remote SensingWuhan UniversityWuhanChina Collaborative Innovation Center for Geospatial Technology WuhanChina

As the deployment of large Low Earth Orbiters(leo)communication constellations,navigation from the leo satellites becomes an emerging opportunity to enhance the existing satellite navigation *** leo navigation augmentation(leo-NA)systems require a centimeter to decimeter accuracy broadcast ephemeris to support high accuracy positioning ***,how to design the broadcast ephemeris becomes the key issue for the leo-NA *** this paper,the temporal variation characteristics of the leo orbit elements were analyzed via a spectrum analysis.A non-singular element set for orbit fitting was introduced to overcome the potential singularity problem of the leo *** on the orbit characteristics,a few new parameters were introduced into the classical 16 parameter ephemeris set to improve the leo orbit fitting *** order to identify the optimal parameter set,different parameter sets were tested and compared and the 21 parameters data set was recommended to make an optimal balance between the orbit accuracy and the bandwidth *** the real-time broadcast ephemeris generation procedure,the performance of the leo ephemeris based on the predicted orbit is also *** performance of the proposed ephemeris set was evaluated with four in-orbit leo satellites and the results indicate the proposed 21 parameter schemes improve the fitting accuracy by 87.4%subject to the 16 parameters *** accuracy for the predicted leo ephemeris is strongly dependent on the orbit *** these leo satellites operating higher than 500 km,10 cm signal-in-space ranging error(SISRE)is achievable for over 20 min prediction.

关键词： leo broadcast ephemeris orbit fitting leo navigation augmentation orbit prediction

Packet routing algorithm for polar orbit leo satellite constellation network

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Science in China(Series F) 2006年第1期49卷 103-127页

作者： wang Kaidong YI Kechu TIAN Bin WU Chengke National Key Laboratory of Integrated Service Networks Xidian University Xi'an 710071 China School of Computer Science Xidian University Xi'an 710071 China

Broadband satellite networks are capable of providing global coverage and support various services. The networks constructed by Low Earth Orbit （leo） satellite constellations have attracted great interests because of their short round-trip delays and wide bandwidths. A challenging problem is to develop a simple and efficient packet routing algorithm for the leo satellite constellation network. This paper presents a SpiderWeb Topological Network （SWTN） and a distributed packet routing algorithm for the leo satellite constellation network based on the SWTN. The algorithm gives the minimum propagation delay paths with low computational complexity and requires no routing tables, which is practical for on-board processing. The performance of the algorithm is demon- strated through simulations.

关键词： packet routing leo satellite constellation satellite networks SWTN.

Determining origins of satellite breakup events in leo region

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Astrodynamics 2023年第4期7卷 465-476页

作者： Yongjie Liu Yu Jiang Hengnian Li Zongbo Huyan Hongchao wang State Key Laboratory of Astronautic Dynamics Xi'an Satellite Control CenterXi'an 710043China

Currently,a surge in the number of spacecraft and fragments is observed,leading to more frequent breakup events in low Earth orbits(leos).The causes of these events are being identified,and specific triggers,such as collisions or explosions,are being examined for their importance to space traffic *** propagation methods were employed to trace the origins of these types of breakup *** were conducted using the NASA standard breakup model,and satellite Hitomi’s breakup was ***-Leibler(KL)divergences,Euclidean 2-norms,and Jensen-Shannon(JS)divergences were computed to deduce potential types of breakups and the associated fragmentation *** the simulated case,a discrepancy of 22.12 s between the estimated and actual time was ***,the breakup of the Hitomi satellite was estimated to have occurred around UTC 1:49:26.4 on March 26,*** contrasts with the epoch provided by the Joint Space Operation Center,which was estimated to be at 1:42 UTC±11 *** the findings,it was suggested that the techniques introduced in the study can be effectively used to trace the origins of short-term breakup events and to deduce the types of collisions and fragmentation masses under certain conditions.

关键词： breakup collision explosion Kullback-Leibler(KL)divergence Jensen-Shannon(JS)divergence

Joint multi-QoS and energy saving routing for leo satellite network

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The Journal of China Universities of Posts and Telecommunications 2019年第3期26卷 25-34页

作者： Gao Yang Zhang Yong Li Kun Teng Yinglei wang Jinxiong School of Telecommunication Engineering Beijing University of Posts and Telecommunications Beijing 100876 China China Academy of Railway Sciences Corporation Limited Standards and Metrology Research Institute Beijing 100876 China Department of Information and Communication Technology State Grid Corporation of China Beijing 100031 China

Low earth orbit(leo) satellite network provides global coverage and supports a wide range of services. However, due to the rapid changes and energy-limitation of satellites, how to meet the demand of the quality of service(QoS) from ground traffic and prolong the lifetime of leo satellite network is the research emphasis of the investigator. Hence, a routing algorithm which takes into account the multi-QoS requirements and satellite energy consumption(QER) of leo satellite network is proposed. Firstly, the satellite intimacy degree(SID) and the path health degree(PHD) are introduced to obtain the path evaluation function according to the energy consumption and queue state of the satellite. Then, the distributed routing QER is established through the path evaluation function and the idea of genetic algorithm(GA), which enables each satellite to adjust traffic and realizes the network load balancing. Simulation results show that QER performs well in terms of end-to-end delay, delay jitter, and system throughput.

关键词： leo satellite network routing multi-QoS energy

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面向星地融合的5G网络增强及关键技术研究

电信科学 2024年第6期40卷 38-48页

作者：张剑寅尼凌飞王汉白谷尚铭刘昱刘景磊中国移动通信有限公司研究院北京100053

卫星在覆盖范围、可靠性和灵活性等方面与地面5G网络具有融合互补的优势,尤其是低轨卫星和5G网络的融合已成为业界研究热点之一。重点面向星地融合领域介绍了5G网络增强架构及融合关键技术。首先,分析了星地融合领域发展趋势并列举重点... 详细信息

卫星在覆盖范围、可靠性和灵活性等方面与地面5G网络具有融合互补的优势,尤其是低轨卫星和5G网络的融合已成为业界研究热点之一。重点面向星地融合领域介绍了5G网络增强架构及融合关键技术。首先,分析了星地融合领域发展趋势并列举重点应用场景;其次,介绍了5G网络增强架构,涉及基于透明转发卫星和基于可再生卫星的两种组网架构;最后,重点围绕星地融合通信业务需求分析了相关关键技术并进行了简要总结,为5G星地融合的应用落地提供有益参考。

关键词：星地融合 5G网络增强架构融合关键技术

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低轨卫星L频段中继通信载荷技术研究

电讯技术 2024年第1期64卷 43-50页

作者：刘冕赵晖胡一皓刘才瑞薛晟王晋阳梁显锋中国科学院国家空间科学中心北京100190 中国科学院大学北京100049

针对深远海和陆基间高速率实时数据通信需求,完成了一种应用于低轨卫星的高集成度、低成本、低功耗L频段中继通信载荷的设计和实现。该中继通信载荷将通信天线、射频前端、信号处理单元、电源变换单元和接口单元等集成化设计。接收前端... 详细信息

针对深远海和陆基间高速率实时数据通信需求,完成了一种应用于低轨卫星的高集成度、低成本、低功耗L频段中继通信载荷的设计和实现。该中继通信载荷将通信天线、射频前端、信号处理单元、电源变换单元和接口单元等集成化设计。接收前端采用有源相控阵天线设计,发射前端设计了GaN功率放大器以提高接收单元G/T值和发射单元等效全向辐射功率(Effective Isotropic Radiated Power,EIRP)。信号处理单元集成了零中频接收结构和直接射频调制结构,可完成反向链路8Mb/s载荷数据接收解调及前向链路数据处理转发的功能。载荷单机和装星后的环境模拟测试以及星地通信回路模拟测试结果表明,装星载荷可实现L频段卫星通信。整机质量为12.87 kg,在工作温度-25℃~+55℃范围内,发射端功率放大器输出大于30 W时,最大功耗为91.2 W(3.04 A/30 V)。

关键词：低轨卫星 L频段中继通信相控阵天线

新疆15种猪毛菜属植物花粉扫描电镜图像数据集

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中国科学数据（中英文网络版） 2024年第2期9卷 202-208页

作者：李全胜王晓丽刘婷婷胡林曹姗姗新疆农业大学计算机与信息工程学院乌鲁木齐830052 中国农业科学院农业信息研究所北京100081 国家农业科学数据中心北京100081

本研究对2007年盛花末期在新疆北部地区采集的粗枝猪毛菜(Salsola subcrassa)、东方猪毛菜(S. orientalis)、短柱猪毛菜(S. lanata)等15种猪毛菜进行花果对照鉴定分类,然后用leo-1430VP型扫描电子显微镜对这些花粉进行多角度拍摄、观察... 详细信息

本研究对2007年盛花末期在新疆北部地区采集的粗枝猪毛菜(Salsola subcrassa)、东方猪毛菜(S. orientalis)、短柱猪毛菜(S. lanata)等15种猪毛菜进行花果对照鉴定分类,然后用leo-1430VP型扫描电子显微镜对这些花粉进行多角度拍摄、观察分析,最大放大倍率20000倍,图像分辨率达1023×766像素,共收录84张图像。数据集中的猪毛菜由藜科植物分类学专家二次鉴定,并由专业人员操作扫描电镜观察花粉性状。读者可以根据猪毛菜种名在本数据集中查阅相应的花粉扫描电镜图像。本数据集的发布,为深入研究新疆乃至中亚地区猪毛菜属植物花粉的典型特征提供了便利,进一步补充和完善了根据猪毛菜属植物的形态特征建立的分组系统,为猪毛菜属植物类群的孢粉学、分类学、生态学等方面的研究提供重要参考。

关键词：猪毛菜属花粉扫描电镜孢粉学

LoS MIMO Transmission for leo Satellite Communication Systems

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China Communications 2022年第10期19卷 180-193页

作者： Lingxuan Li Tingting Chen Wenjin wang Xiaohang Song Li You Xiqi Gao National Mobile Communications Research Laboratory Southeast UniversityNanjing 210096China Vodafone Chair Mobile Communications Systems Technische Universität Dresden01062 DresdenGermany

To provide global service with low latency, the broadband low earth orbits (leo) satellite constellation based communication systems have become one of the focuses in academic and industry. To allow for wideband access for user links, the feeder link of leo satellite is correspondingly required to support high throughput data communications. To this end, we propose to apply line-of-sight (LoS) multiple-input multiple-output (MIMO) transmission for the feeder link to achieve spatial multiplexing by optimizing the antenna arrangement. Unlike the LoS MIMO applications for static scenarios, the movement of leo satellites make it impractical to adjust the optimal antenna separation for all possible satellite positions. To address this issue, we propose to design the antenna placement to maximize the ergodic channel capacity during the visible region of the ground station. We first derive the closed-form probability distribution of the satellite trajectory in visible region. Based on which the ergodic channel capacity can be then calculated numerically. The antenna placement can be further optimized to maximize the ergodic channel capacity. Numerical results verify the derived probability distribution of the satellite trajectory, and show that the proposed LoS MIMO scheme can significantly increase the ergodic channel capacity compared with the existing SISO one.

关键词： LoS MIMO leo satellite ergodic channel capacity Beyond 5G