残余V元素对1Cr18Ni9Ti钢板组织与性能的影响

通过试验详细论述了1Cr18Ni9Ti钢中不同残余V含量对材料固溶状态的组织及400℃、500℃长期时效后对组织、晶间腐蚀和室温、高温性能的影响。从而得出结论适量V的存在对1Cr18Ni9Ti钢板组织影响不大,对抗晶间腐蚀性能稍有提高,对室温、高温抗拉强度、屈服强度稍有提高,塑性稍有降低。     

Change in refractivity of the atmosphere and large variation in TEC associated with some earthquakes,observed from GPS receiver

The present study reports the analysis of GPS based TEC for our station Surat (21.16°N, 72.78°E) located at the northern crest of equatorial anomaly region in India at times close to some earthquake events (M ? 5) during the year 2009 in India and its neighbouring regions. The TEC data used in the study are obtained from GPS Ionospheric Scintillation and TEC Monitoring (GISTM) system. The TEC data has been analysed corresponding to 11 earthquakes in low solar activity period and quiet geomagnetic condition. We found that, out of 11 cases of earthquakes (M > 5) there were seven cases in which enhancement in TEC occurred on earthquake day and in other four cases there was depletion in TEC on earthquake day. The variation in refractivity prior to earthquake was significant for the cases in which the epicentre lied within a distance of 600 km from the receiving station. By looking into the features on temporal enhancement and depletion of TEC a prediction was made 3–2 days prior to an earthquake (on 28 October 2009 in Bhuj – India). The paper includes a brief discussion on the method of potentially identifying an impending earthquake from ionospheric data.     

空气循环制冷游离水与空气分离方法的探讨与研究

本文分析了空气循环制冷技术的原理以及技术应用于地面设备的特点，针对外界高温、高湿的大气条件下制冷过程中游离水与空气的分离问题给出了新的有效的解决办法。     

适用于微纳卫星的微型电离层光学探测器

文章介绍了质量小、体积小的微型电离层光学探测器技术,给出了探测器的探测原理和设计方案,通过探测原子氧远紫外夜气辉(136.5 nm)辐射强度,反演电离层总电子含量(TEC)。采用轻量化铝反射镜、抗干扰电荷前放设计,实现反射镜、工业级远紫外探测器、电子学的一体化和小型化,研制出适用于微纳卫星的1 kg量级微型空间电离层光学探测器。该型探测器能够利用微纳星群多种轨道搭载,可获得丰富数据的优势,获取全球电离层高时空分辨率总电子含量分布,为未来实现卫星编队探测提供载荷研制基础。     

针对星载SAR法拉第旋转估计的NeQuick-2模型精度分析

P波段星载合成孔径雷达(SAR)凭借其较强的穿透能力,在对森林、沙地等观测方面具有较强的优势,但易受法拉第旋转等电离层干扰的影响,其图像质量严重下降。本文针对现有电离层模型的精度开展分析,以基于GPS的CODE GIM全球电离层实测数据为参考,对比评估NeQuick-2模型的电离层总电子量表征能力。在分析CODE GIM实测数据特点的基础上,讨论其在星载SAR领域的局限性;在解析NeQuick-2模型和方法的基础上,研究其表征精度的影响因素;通过对比该模型生成的电离层数据与CODE GIM数据,验证NeQuick-2模型的估计精度。结果表明:NeQuick-2模型可满足P波段星载SAR的法拉第旋转角估计和校正的需求。     

Comparison of GPS-TEC measurements with NeQuick2 and IRI model predictions in the low latitude East African region during varying solar activity period (1998 and 2008–2015)

This paper examines the performances of NeQuick2, the latest available IRI-2016, IRI-2012 and IRI-2007 models in describing the monthly and seasonal mean total electron content (TEC) over the East African region. This is to gain insight into the success of the various model types and versions at characterizing the ionosphere within the equatorial ionization anomaly. TEC derived from five Global Positioning System (GPS) receivers installed at Addis Ababa (ADD, 5.33°N, 111.99°E Geog.), Asab (ASAB, 8.67°N, 116.44°E Geog.), Ambo (ABOO, 5.43°N, 111.05°E Geog.), Nairobi (RCMN, ?4.48°N, 108.46°E Geog.) and Nazret (NAZR, 4.78°N, 112.43°E Geog.), are compared with the corresponding values computed using those models during varying solar activity period (1998 and 2008–2015). We found that different models describe the equatorial and anomaly region ionosphere best depending on solar cycle, season and geomagnetic activity levels. Our results show that IRI-2016 is the best model (compared to others in terms of discrepancy range) in estimating the monthly mean GPS-TEC at NAZR, ADD and RCMN stations except at ADD during 2008 and 2012. It is also found that IRI-2012 is the best model in estimating the monthly mean TEC at ABOO station in 2014. IRI show better agreement with observations during June solstice for all the years studied at ADD except in 2012 where NeQuick2 better performs. At NAZR, NeQuick2 better performs in estimating seasonal mean GPS-TEC during 2011, while IRI models are best during 2008–2009. Both NeQuick2 and IRI models underestimate measured TEC for all the seasons at ADD in 2010 but overestimate at NAZR in 2009 and RCMN in 2008. The periodic variations of experimental and modeled TEC have been compared with solar and geomagnetic indices at ABOO and ASAB in 2014 and results indicate that the F10.7 and sunspot number as indices of solar activity seriously affects the TEC variations with periods of 16–32?days followed by the geomagnetic activity on shorter timescales (roughly periods of less than 16?days). In this case, NeQuick2 derived TEC shows better agreement with a long term period variations of GPS-TEC, while IRI-2016 and IRI-2007 show better agreement with observations during short term periodic variations. This indicates that the dependence of NeQuick2 derived TEC on F10.7 is seasonal. Hence, we suggest that representation of geomagnetic activity indices is required for better performance over the low latitude region.     

体系结构驱动的AFDX网络内容数据库研究

采用SAE AADL语言,建立AFDX网络互连综合化处理任务和通信任务的模型,对通信任务的数据内容、格式、性质进行定义;按照体系结构模型驱动的方式,建立内容管理数据库,完成AFDX网络中数据接口格式与内容的描述与建模,并进行数据库管理下的自动配置与部署。     

800℃以上服役涡轮盘用难变形镍基高温合金研究进展

大推重比航空发动机涡轮盘需在更高温度下服役,为满足更高温度服役航空发动机涡轮盘材料的需求,在新合金的发展过程中合金化程度和γ′相含量逐渐提高。其中GH4151、GH4175和GH4975合金是800℃以上服役变形高温合金的典型代表。对难变形高温合金国内外的发展趋势、3种典型合金的特征和发展过程进行了概述,并对难变形高温合金制备过程中开坯工艺和超塑性等问题进行了探讨。为充分发挥800℃以上服役高相含量难变形高温合金的优势和作用,需对合金成分设计特点、组织特性、热变形和超塑性变形过程中相的作用机制等方面开展相应的理论研究工作。     

复合材料热气防冰系统试验研究

为了进行复合材料热气防冰性能的研究,结合冲击射流和微通道强化换热,针对复合材料导向叶片提出了一种热气防冰系统。对给出的复合材料热气防冰系统进行了简易的冰风洞试验,在同一气流速度、防冰热气流量、平均水滴有效直径条件下,对不同防冰热气温度、外流冷气温度和液态水含量状态下的蒙皮外表面温度进行了测量。结果表明：给出的复合材料热气防冰系统性能正常,能够满足防冰要求;比较了液态水含量、防冰热气温度和冷气温度对蒙皮外表面温度的影响,说明在本实验范围内液态水含量是影响蒙皮外表面温度的最大因素。     

An investigation of ionospheric disturbances over South Africa during the magnetic storm on 15 May 2005

The effects of the 15 May 2005 severe geomagnetic storm on the South African ionosphere are studied using ground-based and satellite observations. Ionospheric disturbances have less frequently been investigated over mid-latitude regions. Recently, a number of studies investigated their evolution and generation over these regions. This paper reports on the first investigation of travelling ionospheric disturbances (TIDs) over mid-latitude South Africa. Using global positioning system (GPS)-derived total electron content (TEC) variations from the South African network of dual frequency GPS receivers, we were able to examine the effects of the disturbance on the TEC. During this storm, two TEC enhancements were observed at low- and mid-latitudes: the first enhancement was observed between 30–45°S geomagnetic latitudes associated with equatorward neutral winds and the passage of a TID, while the second TEC enhancement is associated with a second TID. In addition, the F-region critical frequency (foF2) values observed at two ionosonde stations show response features that differ from those of the TEC during the disturbance period. The dissimilarity between the TEC and the foF2 suggests that two competing drivers may have existed, i.e., the westward electric field and equatorward neutral wind effects.