Attitude control for part actuator failure of agile small satellite

The stability and singularity problem of agile small satellite （ASS） with actuator failure is discussed in this paper. Firstly, the three-axis stabilized controller of an ASS is designed, where micro control moment gyros （MCMG＇s） in pyramid configuration （PC） is used as the actuator. By using the same controller and steering law, the control results before and after one gyro fails are compared by simulation. The variation of singular momentum envelope before and after one gyro fails is also compared. The simulation results show that the failure intensively decreases the capacity of output torque, which leads to the emergence of more singular points and the rapid saturation of MCMG＇s. Finally, the parameters of system controller are changed to compare the control effect.

Impact of Bovine Skeletal Muscle Satellite Cell Differentiation by Small Interfering RNA Targeting Myogenin Gene

To examine the effect of myogenin gene on the differentiation of bovine skeletal muscle satellite cell, we constructed small interfering RNA plasmid vector to obtain myogenin knockdown bovine skeletal muscle cells, then used cell transfection, real time RCR and Western Blot to detect the influence of myogenin to cell differentiation. Results showed that the knockdown of myogenin significantly decreased its expression and other muscle-specific genes. Compared to the control, it could differentiate into few myotubes when challenged by low serum in the medium. These findings provided an important theoretical basis for further explore of the genetic mechanism in adult skeletal muscle, the remedy of muscle injuries and the cultivation of high-yield transgenic cattle.

Information acquisition technology for small hydropower stations in remote areas based on high-and low-orbit satellites

With a lack of coverage in private and public power communication networks,especially for collection of information from hydropower stations in remote areas,communication coverage is a significant issue.Satellite communication provides a large coverage area suitable for a variety of services and is less affected by geographical factors;moreover,the costs are independent of the communication distance.This study investigates information acquisition technology for small hydropower stations in remote areas using high-and low-orbit satellites.The information collection needs of small hydropower stations in remote areas are analyzed,and an information acquisition system is designed using high-and low-orbit satellites.For network security protection,network anomaly detection technology based on a support vector machine algorithm is proposed.The effectiveness of information collection was evaluated and verified for small hydropower plants in remote areas.The system provides technical support for“full coverage,full collection,and full monitoring”of the measurement automation information acquisition system.

Service Function Chain in Small Satellite-Based Software Defined Satellite Networks

Software Defined Satellite Networks(SDSN) are proposed to solve the problems in traditional satellite networks, such as time-consuming configuration and inflexible traffic scheduling. The emerging application of small satellite and research of SDSN make it possible for satellite networks to provide flexible network services. Service Function Chain(SFC) can satisfy this need. In this paper, we are motivated to investigate applying SFC in the small satellite-based SDSN for service delivery. We introduce the structure of the multi-layer constellation-based SDSN. Then, we describe two deployment patterns of SFC in SDSN, the Multi-Domain(MD) pattern and the Satellite Formation(SF) pattern. We propose two algorithms, SFP-MD, and SFP-SF, to calculate the Service Function Path(SFP). We implement the algorithms and conduct contrast experiments in our prototype. Finally, we summarize the applicable conditions of two deployment patterns according to the experimental results in terms of hops, delay, and packet loss rate.

A Swarm Intelligence Networking Framework for Small Satellite Systems

Recent development of technologies and methodologies on distributed spacecraft systems enable the small satellite network systems by supporting integrated navigation, communications and control tasks. The distributed sensing data can be communicated and processed autonomously among the network systems. Due to the size, density and dynamic factors of small satellite networks, the traditional network communication framework is not well suited for distributed small satellites. The paper proposes a novel swarm intelligence based networking framework by using Ant colony optimization. The proposed network framework enables self-adaptive routing, communications and network reconstructions among small satellites. The simulation results show our framework is suitable for dynamic factors in distributed small satellite systems. The proposed schemes are adaptive and scalable to network topology and achieve good performance in different network scenarios.

Fusion and Classification of Beijing-1 Small Satellite Remote Sensing Image for Land Cover Monitoring in Mining Area

In order to promote the application of Beijing-1 small satellite(BJ-1) remote sensing data,the multispectral and panchromatic images captured by BJ-1 were used for land cover classification in Pangzhuang Coal Mining.An improved Intensity-Hue-Saturation(IHS) fusion algorithm is proposed to fuse panchromatic and multispectral images,in which intensity component and panchromatic image are combined using the weights determined by edge pixels in the panchromatic image identified by grey absolute correlation degree.This improved IHS fusion algorithm outper-forms traditional IHS fusion method to a certain extent,evidenced by its ability in preserving spectral information and enhancing spatial details.Dempster-Shafer(D-S) evidence theory was adopted to combine the outputs of three member classifiers to generate the final classification map with higher accuracy than that by any individual classifier.Based on this study,we conclude that Beijing-1 small satellite remote sensing images are useful to monitor and analyze land cover change and ecological environment degradation in mining areas,and the proposed fusion algorithms at data and decision levels can integrate the advantages of multi-resolution images and multiple classifiers,improve the overall accuracy and produce a more reliable land cover map.

Active magnetic control algorithm for small satellite

Small satellites often tumble as a result of disturbance during the initial orbit period, and it is therefore very important to capture it promptly with finite magnetic torque. Because of the coupling of dynamics and control, the control system for small satellites is a nonlinear system with restrictive conditions. Considering the restrictive conditions of magnetic torque, two algorithms are proposed: the energy algorithm which uses the Lyapunov energy depletion theory and takes the Hamilton function as a cost function to determine the magnetic torque, and the variable structure control theory which is used to deal with the magnetic torque.

Reflection on Small Satellite Constellation Operations from the Commercial Space Perspective

With the advances of small satellite technology in commercial space sector,using small satellite networks to form a satellite constellation and conduct commercial operational services has entered into a vigorous phase of development.As small satellite technology develops,problems in the operations of small satellite constellations are also gradually emerging.These include ground measurement and operational control systems for small satellite constellations,the commercial operational mode,support and the guarantee of laws and regulations related to small satellites.This report discusses the development of commercial space small satellite operation industrialization,explores the small satellite operational modes and technological innovation,proposes the commercial space industry chain to build the industry ecology.At the same time,it looks forward to the integration of space and terrestrial communication.It also calls on relevant organizations of China to speed up the process of space legislation,formulate the relevant policies to encourage the operations of small satellites in commercial space sector,and push China’s commercial space to a new level.

Technology and Market Prospect Analysis of Low Cost Small-lift Launch Vehicles for Small Satellites

The technological development status of new generation low cost small-lift launch vehicles applied to small satellite launch is investigated in this paper. The development trends are summarized, including low cost and rapid response capability, utilization of mature rocket and missile technology, the development of mobile launch technology adopting air-based platforms and use of innovative technology. Moreover, the external power and internal demand of the small-lift launch vehicle are analyzed and the market prospect is forecasted. Finally, proposals for the development of small-lift launch vehicles are put forward, including exploration of the potential of existing rocket and missile technology, development of multi-platform mobile launch technology and further application of innovative technology and ideas.

Expression and Assembly Mechanism of the Capsid Proteins of a Satellite Virus (XSV) Associated with Macrobrachium rosenbergii Nodavirus

The extra small virus （XSV） is a satellite virus associated with Macrobrachium rosenbergii nodavirus （MrNV） and its genome consists of two overlapping ORFs, CP17 and CP16. Here we demonstrate that CP16 is expressed from the second AUG of the CP17 gene and is not a proteinase cleavage result of CP17. We further expressed CP17 and several truncated CP17s （in which the N-or C-terminus or both was deleted）, respectively, in Escherichia coli. Except for the recombinant plasmid CP17^AC10, all recombinant plasmids expressed soluble protein which assembled into virus-like particles （VLPs）, suggesting that the C-terminus is important for VLP formation.

接入网关在smallcell卫星通讯网络中的作用和优势

为了解决偏远地区通讯设备过少、通讯成本过高和网络部署复杂的难题,满足石油勘探等日益增长的用户需求,本文基于现阶段偏远地区广泛部署的卫星通讯网络,结合无线通讯中的small cell网络架构,提出了一个以接入网关AG为核心的small cell网络与卫星通讯相融合的系统,该系统相比纯卫星通讯、无线通讯宏网架构以及WLAN等各种通讯系统而言,有着成本和便捷上的重大优势,本文重点用实际商用性能测试,包括用户容量、信令冲击、数据吞吐量等数据证明了AG网关强大的处理能力和在系统中所起的关键作用,在容量上,对家庭基站AP的接入可达十万,对UE用户的接入可达上百万,UE的信令冲击可达10000caps,数据吞吐量可达50Gbps,在实际商用环境中可以做到对AP和UE的无限扩容,体现了以AG网关为核心的small cell与卫星通讯融合系统的广泛而重大的应用前景。

Localization of Small Mobile Robot by Low-Cost GPS Receiver

This article deals with a problem of the robot localization in the outdoor environment by using the GPS （global positioning system） data. In order to navigate the robot, it is necessary to transform the global position into the local map in the form of two-dimensional Cartesian coordinate system. The transformation is based on the model of the Earth-WGS 84 reference ellipsoid. The aim of this article is to experimentally evaluate a set of low-cost GPS receivers applicable as position sensors for small outdoor mobile robots. The evaluation is based on series of measurements executed in different times and places. The measured data is processed by given procedure and acquired positions are transformed into the local coordinate system. Accordingly the accuracy of the measured positions is statistically evaluated. The evaluation of used GPS receivers is done by comparison with data acquired by high-end geodetic GPS system Leica 1200, which is used as a reference GPS system.

High-Level Accumulation of Exogenous Small RNAs Not Affecting Endogenous Small RNA Biogenesis and Function in Plants

RNA silencing is a fundamental plant defence and gene control mechanism in plants that are directed by 20-24 nucleotide （nt） small interfering RNA （siRNA） and microRNA （miRNA）. Infection of plants with viral pathogens or transformation of plants with RNA interference （RNAi） constructs is usually associated with high levels of exogenous siRNAs, but it is unclear if these siRNAs interfere with endogenous small RNA pathways and hence affect plant development. Here we provide evidence that viral satellite RNA （satRNA） infection does not affect siRNA and miRNA biogenesis or plant growth despite the extremely high level of satRNA-derived siRNAs. We generated transgenic Nicotiana benthamiana plants that no longer develop the specific yellowing symptoms generally associated with infection by Cucumber mosaic virus （CMV） Y-satellite RNA （Y-Sat）. We then used these plants to show that CMV Y-Sat infection did not cause any visible phenotypic changes in comparison to uninfected plants, despite the presence of high-level Y-Sat siRNAs. Furthermore, we showed that the accumulation of hairpin RNA （hpRNA）-derived siRNAs or miRNAs, and the level of siRNA-directed transgene silencing, are not significantly affected by CMV Y-Sat infection. Taken together, our results suggest that the high levels of exogenous siRNAs associated with viral infection or RNAi-inducing transgenes do not saturate the endogenous RNA silencing machineries and have no significant impact on normal plant development.

小卫星智能化技术发展展望

随着人工智能、大数据、云计算、物联网等技术在各领域应用日趋深入,航天技术也取得了迅猛发展,基于复杂任务的体系智能化、星座智能化发展成为航天新趋势。未来小卫星将向“新、小、快、灵、智、多、省、好”等方向发展,通过人工智能、数字孪生等技术实现智能化,以适应小卫星星座化、体系化发展需求。文章为应对未来小卫星快速发展需求,提出了星座化、体系化发展下小卫星特点与智能化需求,探讨了新形式下小卫星智能化发展转型,并给出了小卫星智能化发展建议。

小卫星空间用频现状和问题研究

针对小卫星无线电通信频率资源日趋紧缺的问题,文章对国内外空间用频现状进行了梳理,从频率协调、频率兼容、用频安全等3个方面分析了小卫星用频面临的难题和挑战,并重点针对小卫星频率资源紧张且协调困难、空间用频限制造成自兼容设计困难、应急环境下频率使用安全等问题,提出了规范频谱协调管理、优化频率分配、提高抗干扰能力的建议和措施。可为小卫星空间频率使用提供参考。

一种广角相机视频小卫星姿态跟踪方法

针对传统目标跟踪方法需要目标的先验位置信息、不适用于非合作目标跟踪的问题,提出了一种基于广角相机图像误差的视频小卫星目标跟踪方法。该方法首先建立了广角相机成像模型,然后计算目标在相机图像平面中的投影位置和期望位置之差,通过图像误差确定目标与视频小卫星的相对误差角速度和姿态误差,将其作为反馈项设计非线性控制器,最后利用Barbalat引理证明了系统的稳定性。仿真结果表明,在广角相机大范围视场下,该方法可以有效地将目标控制到图像平面中期望的位置,并且利用天拓二号卫星在轨验证了该方法的有效性。

小卫星空间用频现状和问题研究

小卫星在轨依赖电磁波完成所需的各种无线电通信功能.近年来,随着在轨卫星数量的几何级数增加,卫星无线电通信频率资源日趋紧缺,空间用频问题逐渐暴露.为了给当前小卫星用频设计提供参考,对国内外空间用频现状进行了总结和梳理.在此基础上,从频率协调、频率兼容和用频安全等三方面分析了小卫星用频面临的难题和挑战.重点针对小卫星频率资源紧张且协调困难、空间用频限制造成自兼容设计困难及应急环境下频率使用安全等问题,提出了规范频谱协调管理、优化频率分配及提高抗干扰能力等建议和措施.最后给出了几点结论,并指出其对小卫星工程实际的借鉴和参考价值.

小卫星技术与应用发展研究

近年来,随着航天技术的不断突破,进入空间、利用空间的门槛逐步降低.伴随着“互联网+航天”、人工智能、大数据等要素的不断加持,在国家政策、商业资本等的多重促动下,航天的商业价值愈发凸显,商业小卫星迎来了高速发展期.为了进一步明晰小卫星的作用,研究了小卫星的分类,统计了近年来全球卫星发射数据,调研了小卫星的应用情况,给出了近年来小卫星的总体发展态势,并分析了小卫星发展的核心能力.最后,提出了小卫星未来的发展趋势与展望,期望有助于加快推动中国大规模小卫星星座的规划部署和健康有序发展.

小卫星星座AIT过程进度风险管控探索与实践

针对小卫星星座项目在卫星总装、测试与试验(AIT)过程中进度拖延的问题,识别出一系列影响卫星生产进度的风险,结合星座项目的特点,提出了小卫星大批量AIT进度风险管控措施,在产品交付、总装与测试过程、资源分配等方面根据关键要素,制定了流程优化方案,经在某小卫星星座AIT过程中实践,结果表明:上述措施有效的将AIT过程进度风险降至可控范围,实现了小卫星星座项目在规定期限内高质量的完成研制任务,可以为今后大规模小卫星星座研制提供参考。

可见红外一体化敏捷小卫星微振动抑制方法

随着光学遥感小卫星高分辨率、高集成度、高敏捷等需求提升,部分卫星同时配置可见红外一体化相机与控制力矩陀螺(control moment gyroscope,CMG),兼顾轻小型化与全天时、多目标、多模式成像要求。针对此类卫星存在CMG、红外相机制冷机等多个扰振源,且对于相机成像质量影响大、抑制难等挑战,对基于上述扰振源的微振动综合抑制方法进行了研究,包括设计、安装CMG隔振器、将红外相机制冷机压缩机与相机光机主体隔振安装,设计、安装阻尼桁架实现相机主体与卫星平台舱结构之间的隔振等。通过综合应用上述扰源减振、终端隔离等措施,经分析计算与整星微振动及在轨实际测试与验证,能够有效降低微振动对图像质量的影响,即使对于可见红外一体化相机,分辨率为亚米级的可见光通道在轨动态调制传递函数(modulation transfer function,MTF)也能够达到0.1,微振动对可见相机MTF的影响因子可控制到0.991。