The development of a Russian communication satellite of small class, operating in the geostationary and high-elliptical orbits

In 1994-1995 Lavochkin Association (Russia) together with the other enterprises in accordance with technical requirements of the Russian Space agency, developed a new Russian communication satellite of a small class that will operate in both the geostationary (GSO) and high-elliptical (HEO) orbits. This satellite may be injected into operational orbits using a SOYUZ-2 launch vehicle (LV) and a FREGAT upper stage (US) from Plesetsk and Baykonur space launch sites (SLS).The main reason for creating such a satellite was to decrease the cost of the support and development of the Russian communication geostationary satellites group.Russian satellites Horizont, Express, Ekran and Gals, which operate in GSO, are the basis of the space segment for communications, radio and TV broadcasting. All of these satellites are injected into GSO by the PROTON LV. PROTON is a launch vehicle of a heavy class. The use of a middle class LV instead of a heavy class will allow to reduce considerably the launch cost. The change of a heavy class LV to a LV of middle class determined one economic reason for this project. Besides, the opportunity to launch S/C into GSO from Russian Plesetsk SLS increases the independence of Russia in the domain of space communications, despite the presence of the contract with Kazachstan about the rent of Baykonur SLS. Finally, use of small satellites with a rather small number of transponders is more effective than the use of big satellites. It will allow also to increase a satellite group (by the launch of additional satellites) precisely in accordance to the development of the ground segment.     

Earth observation from space – The issue of environmental sustainability

Remote sensing scientists work under assumptions that should not be taken for granted and should, therefore, be challenged. These assumptions include the following:1. Space, especially Low Earth Orbit (LEO), will always be available to governmental and commercial space entities that launch Earth remote sensing missions.2. Space launches are benign with respect to environmental impacts.3. Minimization of Type 1 error, which provides increased confidence in the experimental outcome, is the best way to assess the significance of environmental change.4. Large-area remote sensing investigations, i.e. national, continental, global studies, are best done from space.5. National space missions should trump international, cooperative space missions to ensure national control and distribution of the data products.At best, all of these points are arguable, and in some cases, they're wrong. Development of observational space systems that are compatible with sustainability principles should be a primary concern when Earth remote sensing space systems are envisioned, designed, and launched. The discussion is based on the hypothesis that reducing the environmental impacts of the data acquisition step, which is at the very beginning of the information stream leading to decision and action, will enhance coherence in the information stream and strengthen the capacity of measurement processes to meet their stated functional goal, i.e. sustainable management of Earth resources. We suggest that unconventional points of view should be adopted and when appropriate, remedial measures considered that could help to reduce the environmental footprint of space remote sensing and of Earth observation and monitoring systems in general. This article discusses these five assumptions in the context of sustainable management of Earth's resources. Taking each assumption in turn, we find the following:(1) Space debris may limit access to Low Earth Orbit over the next decades.(2) Relatively speaking, given that they're rare event, space launches may be benign, but study is merited on upper stratospheric and exospheric layers given the chemical activity associated with rocket combustion by-products.(3) Minimization of Type II error should be considered in situations where minimization of Type I error greatly hampers or precludes our ability to correct the environmental condition being studied.(4) In certain situations, airborne collects may be less expensive and more environmentally benign, and comparative studies should be done to determine which path is wisest.(5) International cooperation and data sharing will reduce instrument and launch costs and mission redundancy. Given fiscal concerns of most of the major space agencies – e.g. NASA, ESA, CNES – it seems prudent to combine resources.     

Solar cycle variation of “killer” electrons at geosynchronous orbit and electron flux correlation with the solar wind parameters and ULF waves intensity

To construct models for hazard prediction from radiation belt particles to satellite electronics, one should know temporal behavior of the particle fluxes. We analyzed 11-year variation in relativistic electron flux (E>2 MeV) at geosynchronous orbit using measurements made by GOES satellites during the 23rd sunspot cycle. As it is believed that electron flux enhancements are connected with the high-speed solar wind streams and ULF or/and VLF activity in the magnetosphere, we studied also solar cycle changes in rank order cross-correlation of the outer radiation belt electron flux with the solar wind speed and both interplanetary and on-ground wave intensity. Data from magnetometers and plasma sensors onboard the spacecraft ACE and WIND, as well as magnetic measurements at two mid-latitude diametrically opposite INTERMAGNET observatories were used. Results obtained show that average value of relativistic electron flux at the decay and minimum phases of solar activity is one order higher than the flux during maximum sunspot activity. Of all solar wind parameters, only solar wind speed variation has significant correlation with changes in relativistic electron flux, taking the lead over the latter by 2 days. Variations in ULF amplitude advance changes in electron flux by 3 days. Results of the above study may be of interest for model makers developing forecast algorithms.     

涡轮基组合循环发动机分布式控制系统通信网络混合拓扑结构优化方法

涡轮机组合循环(Turbine based combined cycle,TBCC)发动机控制系统通信网络拓扑结构是其分布式控制系统方案设计的重要部分,优化网络拓扑结构可提高发动机推重比和控制系统可靠性。本文基于智能优化算法提出TBCC分布式控制系统网络拓扑结构优化方法。基于图论建立TBCC几何模型和网格模型,以重量和可靠性为优化性能指标,同时考虑发动机表面高温区域以及控制节点的工作可靠性,分别采用粒子群算法和遗传算法优化星形结构中智能中央节点位置、中央节点的环形拓扑结构,获得星形-环形混合拓扑结构。仿真实例表明,基于本文方法优化所得的混合拓扑结构相较于星形集中式控制结构,系统重量降低了51.9%。     

航空发动机一维数值仿真

分析了航空发动机一维气动热力数值仿真模型,此模型能够用于航空发动机整机数值仿真.进行了整机性能数值仿真,求解过程考虑了粘性效应以及气体流动损失对于整机性能的影响;采用了具有TVD性质的高阶精度Godunov格式,此格式具有良好的数值稳定性和激波捕捉能力;应用了时间推进法,交替使用显/隐格式.计算了某型带加力的混排涡扇发动机的速度特性以及节流特性并且与设计数据进行了比较分析,数值仿真结果与设计数据比较吻合.分析了典型工作点的计算过程,模型收敛速度较快.     

依托ERP实现固定资产全寿命周期管理

固定资产是企业的重要劳动资料,是实现资产保值增值的重要工具。现有的固定资产管理模式已经无法应对当前电网企业对固定资产管理新形势的要求。资产全寿命周期管理是以资产的整体目标出发,统筹考虑资产的整个生命周期,在满足安全、效能的前提下追求资产全寿命周期成本最优的管理模式。本文提出通过运用ERP系统在固定资产生命周期内构建出一套完整的固定资产管理新模式,并通过在某地市级供电公司的实际运用,得出了运用此种新模式可以实现固定资产使用效率提高、全寿命周期成本降低的管理新要求。     

基于GIS面向LCA的产品材料信息管理系统建构

为解决传统生命周期评价(Life cycle assessment,LCA)空间位置数据缺失的问题,论文通过引入地理信息系统(Geographic information system,GIS)系统实现了空间位置数据的获取。论述了将空间位置数据引入LCA的必要性与可能性,提出了全新的产品材料管理信息系统功能结构与数据库框架。提出了空间位置数据的获取和有效管理的新方法,对产品材料数据库的进一步完善,以及LCA方法的进一步改进,具有非常重要的意义。     

Temporal and spatial variation of equatorial ionization anomaly by using multistation ionosonde data for the 19th solar cycle over the Indian region

The paper deals with the study of temporal and spatial variation of equatorial ionization anomaly (EIA) phenomenon along with its dependence on solar activity and season during the 19th solar cycle by using seven Indian ionosonde stations. Present study is an attempt to carry out the comprehensive study of EIA by using the limited number of ground based instruments. This has been achieved by performing the Gaussian fitting over the latitudinal distribution of F2-region critical frequency (foF2) data. Results reveal that the phenomenon of EIA has a strong dependence on solar activity and seasons. The EIA crest exhibits the feature of latitudinal shifting and expansion with increasing solar activity. It is found out that the effect of solar cycle and seasons on EIA is local time dependent. The observations were also compared with the IRI-2001 model predictions and results reveal that the model values are in general agreement with the observed values with some discrepancies, particularly during the high solar activity period and morning sector. The results have been discussed in the light of relative contribution from transequatorial interhemispheric neutral wind and strength of equatorial fountain process during different local time, season and solar activity levels. Furthermore, an attempt is made to parameterize the location and foF2 of the EIA crest by using the regression analysis. These results can be used to predict the latitudinal position and foF2 of the EIA crest for any given 12-month running average sunspot number (R12).     

利用相似周方法预测第24活动周开始时间

利用相似周方法对第24活动周的开始时间与第23活动周下降相后期的太阳黑子数进行了预报.根据第23周已经出现的特征参量和下降相的形态特征,选取9,10,11,15,17和20等六个太阳活动周作为第23周下降相的相似周,对第24周开始时间进行预报.预报结果显示,第24活动周的开始时间为2007年5±1月,黑子数平滑月均极小值为7.1±2.6,第23太阳活动周长度为11.1年.与其他研究者的预报结果相比较,本文给出的结果与文献[11]和[12]及MSFC的结果比较一致.通过对相似周方法在下降相预测太阳活动周结束时间的研究讨论,及对第23周上升阶段的太阳黑子数和F10.7平滑月均值预报结果的评估,可以看出,相似周预报方法在太阳活动周长期预报中是很有应用价值的.     

多孔介质隔热材料中的辐射热传递分析

新型的多孔材料以其重量轻、强度高备受航天工程设计人员的亲睐,尤其是作为隔热材料使用,可以说是航天工程热防护系统的热门材料.多孔介质在辐射热传递方面具有吸收发射和散射的功能,这些功能在其接受外来热流的作用下,于内部达到热能量平衡,求解这一平衡方程就可以求出辐射热流在材料中的分布.由于求解这一方程的困难,许多学者对材料特性...