Multi-objective optimal formation reconfiguration with scalarization and stochastic boundaries

A new method is proposed for multi-objective optimal control of satellite formation reconfiguration. First, necessary optimality conditions of single-objective fuel-optimal reconfiguration are studied. Problem of initial guess of the costate and control discontinuity are addressed by using a new developed stochastic based method. Terminal conditions of Two Point Boundary Value Problem (TPBVP) of the optimal control equations are relaxed using augmented Gaussian. Variances or bandwidths of the terminal conditions are set to decision variables to be optimized. Responses of varied initial costate are modeled and propagated using Riccati equation. Using quadratic convolution of relaxed terminal conditions, objective function of the fuel-optimal problem is reformulated into a quadratic equation, and a gradient based optimizer is used to search the optimal initial guess. In the second part of the paper, optimal control of format flying reconfiguration with two competitive objectives:fuel and time of flight (ToF) is studied. With Pascoletti-Serafini scalarization, the Multi-objective Optimal Control Problem (MOCP) is scalarized into a set of weighted Single-objective Optimal Control Problems (SOCP). Hamiltonian and switch function for the weighted SOCP are developed and constructed. New developed stochastic based approach is then used to search the optimal Pareto solutions. Verification and performances of proposed algorithms are demonstrated through numerical simulations of single-objective and multi-objective optimal control of low-thrust elliptical orbit formation reconfiguration. Potential applications of the algorithms to some other preliminary space mission designs are also discussed.     

Histogram-based ionogram displays and their application to autoscaling

A simple method is described for displaying and auto scaling the basic ionogram parameters foF2 and h’F2 as well as some additional layer parameters from digital ionograms. The technique employed is based on forming frequency and height histograms in each ionogram. This technique has now been applied specifically to ionograms produced by the IPS5D ionosonde developed and operated by the Australian Space Weather Service (SWS). The SWS ionograms are archived in a cleaned format and readily available from the SWS internet site. However, the method is applicable to any ionosonde which produces ionograms in a digital format at a useful signal-to-noise level. The most novel feature of the technique for autoscaling is its simplicity and the avoidance of the mathematical imaging and line fitting techniques often used. The program arose from the necessity to display many days of ionogram output to allow the location of specific types of ionospheric event such as ionospheric storms, travelling ionospheric disturbances and repetitive ionospheric height changes for further investigation and measurement. Examples and applications of the method are given including the removal of sporadic E and spread F.     

1553B总线监视器系统软件设计

1553B总线是一种集中式控制的串行总线型网络，其组成包括一个总线控制器、若干远置终端，还可以包括总线监视器。本文详细介绍了1553B总线监视器系统软件的设计，探讨了设计中需要注意的几个问题。     

校企合作共建民航特色实训基地的探索与实践

通过校企合作共建实训基地的优势分析,探讨利用合作办学资源、促进实训建设,校企合作共建实训基地需要解决的问题,总结我院实训基地建设的一些成功经验,以及阐明今后努力的方向。     

Time series modeling and analysis of trends of daily averaged ionospheric total electron content

A 10.7 cm solar radio flux F10.7, geomagnetic planetary equivalent amplitude (Ap index), and period variations were considered in this paper to construct a linear model for daily averaged ionospheric total electron content (TEC). The correlation coefficient of the modeled results and International GNSS Service (IGS) observables was approximately 0.97, which implied that the model could accurately reflect the realistic variation characteristics of the daily averaged TEC. The influences of the different factors on TEC and its characteristics at different latitudes were examined with this model. Results show that solar activity, annual and semiannual cycles are the three most important factors that affect daily averaged TEC. Solar activity is the primary determinant of TEC during periods with high solar activity, whereas periodic factors primarily contribute to TEC during periods with minimum solar activity. The extent of the influences of the different factors on TEC exhibits obvious differences at varying latitudes. The magnitude of the semiannual variation becomes less significant with the increase in latitude. Furthermore, a geomagnetic storm causes an increase in TEC at low latitudes and a decrease at high latitudes.     

卫星载荷1553B总线数据接口的设计与实现CSCD

卫星载荷总线数据流接口的实现对于卫星载荷数据流的传输体制能否正常工作起着关键性的作用,设计合理的数据流管理方案对于卫星载荷之间的正常通信至关重要。MIL-STD-1553B总线数据传输速率高,实时性好,具有合理的差错控制措施和特有的方式命令,适合星上大数据量的传输任务和特定环境的需求。本文使用龙芯配置卫星载荷1553B总线的工作模式,合理设计载荷数据流的传输形式,实现卫星载荷1553B总线的数据流接口。测试结果表明,数据接口可靠性高,实际应用效果好,满足卫星上的通信设计要求。     

FC-AE-1553数据总线的特点及在航天领域的应用

MIL-STD-1553B总线被广泛运用于许多嵌入式系统,例如飞机、轮船、导弹、卫星等。但是随着科学技术的发展,当前的航空航天系统,武器系统的互连子系统的数量和复杂性不断增加,系统对高带宽、低延时数据需求愈发迫切,而光纤天然具有的高带宽、低延时的特点能够很好解决上述需求。除此之外,用光纤搭建的通信网络还具有灵活的拓扑结构、较远的传输距离、高抗电磁干扰等优点。FC-AE-1553的通信介质采用光纤,其各个节点之间的通信协议与MIL-STD-1553B高度相似,因此采用FC-AE-1553通信协议的新设备能够较好地兼容MIL-STD-1553B协议的传统设备。     

基层服务型党组织建设的现实依据与根本路径

加强基层服务型党组织建设,有利于更好地履行党的根本宗旨和根本执政理念,是密切党群关系的根本保证;有利于提高基层社会的治理水平,其关键是要准确把握基层服务型党组织的理论和实践内涵、本质属性,以及找准基层服务型党组织建设的着力点。未来一段时期的基层服务型党组织建设,应重点围绕增强服务意识、做强服务队伍、创新服务载体、加大基层投入、提高治理能力五个方面来推进。     

中国行政垄断现象及法律规制研究

近年来,在我国由计划经济体制向市场经济体制转轨的过程中,长期存在的计划经济所产生的惯性使政府利用其公共权力限制市场竞争,在众多经济部门建立垄断企业,比如铁路、电信、石油、银行等部门,由此出现了行政垄断现象,并愈演愈烈.转型时期,以地方保护和市场分割为主要表现形式的行政垄断扭曲了市场良性竞争关系,降低了资源配置效率,不利于经济的发展.因此,在转型时期,行政垄断的治理、政府管制的改革以及法律制度的规制都成为社会各界普遍关注的问题.文章拟就转型时期的行政垄断现象及法律规制方面的对策进行较为全面的剖析,以期有利于我国在该领域改革实践的深入.     

直-X直升机旋翼动平衡检查调整方法研究

通过对几十架直-X直升机旋翼动平衡检查调整的总结,结合维护手册和实际经验,提出了该型直升机旋翼动平衡检查调整方法,并在实际应用中取得了很好的效果.