Orbital phase spectroscopy of X-ray pulsars to study the stellar wind of the companion

High Mass X-ray Binary Pulsars (HMXBP), in which the companion star is a source of supersonic stellar wind, provide a laboratory to probe the velocity and density profile of such winds. Here, we have measured the variation of the absorption column density along with other spectral parameters over the binary orbit for two HMXBP in elliptical orbits, as observed with the Rossi X-ray Timing Explorer (RXTE) and the BeppoSAX satellites. A spherically symmetric wind profile was used as a model to compare the observed column density variations. In 4U 1538-52, we find the model corroborating the observations; whereas in GX 301-2, the stellar wind appears to be very clumpy and a smooth symmetric wind model seems to be inadequate in explaining the variation in column density.     

两种实验室方法模拟舰载平台环境下航空电路板的腐蚀行为

为评价干湿交替酸性盐雾和盐雾/SO2复合 2种实验室环境对航空电路板在舰载平台下的腐蚀行为研究的适用性,通过对 2种航空电路板产品开展随舰暴露试验和 2种实验室环境加速试验,分析了舰载平台环境下电路板典型结构的腐蚀机制以及与 2种实验室试验结果的相似性。结果表明,由于舰载平台环境中存在盐雾和 SO2等燃油尾气,导致了电路板有机涂层防护薄弱部位的失效,引发了镀通孔和表面导线的腐蚀,也导致了塑封存储器的失效。对比 2种实验室加速试验方法,盐雾/SO2复合试验在环境效应、环境因素方面对舰载腐蚀环境效应的复现效果更好。     

涡轮叶栅端壁二次流动与换热的V2F模拟

针对低展弦比涡轮叶栅端壁区亚声速流动及换热,采用基于线性涡黏假设的V2F模型开展了数值模拟.结果表明：涡轮叶栅流动中存在马蹄涡、通道涡、压力侧角涡、吸力侧角涡等多种复杂涡系结构,其中马蹄涡与通道涡是涡轮叶栅二次损失的主要来源.端壁换热与马蹄涡及通道涡强度及位置直接相关,并呈现明显的分区特征.端壁极限流线结果显示,V2F模型模拟的端壁单马蹄涡分离线与实验结果吻合,优于SST （shear stress transport）k-ω模型模拟的端壁双马蹄涡分离线.V2F模型引入了新的湍流尺度,在马蹄涡及通道涡位置、端壁静压损失系数分布、叶栅出口总压损失分布及端壁Standon数分布等方面均与实验结果吻合较好,对叶栅气动损失及端壁换热有良好的预测能力.     

FY-2C星电源分系统及其在轨性能

介绍了风云二号(FY-2)C气象卫星电源分系统的组成、技术指标和工作原理,以及太阳电池阵、Cd-Ni蓄电池组和电源控制设备等主要部件的设计和改进.遥测数据分析结果显示,C星太阳电池阵功率裕度优于设计要求,采用BSFR太阳电池对方阵工作温度影响不明显,地影轨道72 min地影蓄电池最大放电深度减小,涓流态第三极电性能信号与A,B星-致.在轨运行结果表明,C星电源分系统各部件状态良好,能满足任务要求.国内首次用于地球静止轨道空间电源工程的BSFR太阳电池方阵性能稳定,蓄电池组容量增大,简化了地影期卫星地面管理,改善卫星地影期环境工作温度;解决了A,B星进出影电源分系统自主转电时全调节母线电压的负冲.     

FY-2C星辐射定标及其结果分析

介绍了风云二号(FY-2)C星发射前后红外与水汽波段的地面真空辐射定标、星上黑体定标和地面辐射校正场定标,以及可见光波段的地面太阳定标、积分球定标、地面辐射校正场定标和太阳像的原理与方法.给出了C星不同波段不同定标法的结果.分析表明,C星采用的定标方法均有效,并互为补充和验证.为进一步提高定标精度,还可对环境温度模拟、二次曲线拟合、减小积分球定标误差和光谱响应等作相应的改进.     

FY-2C星数传与云图广播转发器分系统

介绍了风云二号(FY-2)气象卫星数传与云图广播转发器分系统的功能、组成,以及频率配置、传输信号特性和增益与功率等主要技术指标.给出了C星分系统转发器的技术改进.阐明了采用的收发多工器、射电天文保护滤波器、固体功率放大器(SSPA)和功能转换开关等关键技术.测试结果和在轨运行状况表明,C星数传与云图广播转发器的性能符合设计任务书要求,在轨运行正常稳定.     

FY-2C星地面应用分系统工程建设

介绍了风云二号(FY-2)C气象卫星地面应用分系统的组成、主要任务及建设目标.说明了分系统建设中采用的建立健全两总系统、成立气象卫星工程建设部和建立两总联席会议制度等行政措施.阐明了在分系统建设中采用的软件工程管理开发、加强合同签定审批、不同设备的验收,以及严格选择基础施工单位与聘请施工监理等管理措施.建成的地面应用分系统在C星的业务运行中发挥了重要作用.     

共沉淀法制备ZrO2超细复合粉过程中团聚现象的研究

综合分析了共沉淀制备ZrO2超细复合粉过程中的团聚现象的形成过程及其影响因素，并提出了消除粉团聚的有效方法。     

GaN基白光LED电流加速老化特性研究

本文对三组Al2O3衬底上生长GaN基蓝光激发黄色荧光粉的白光LED进行了对比电流加速老化实验,老化电流分别是30 mA5、0 mA和70 mA。随着老化电流的增大,GaN基白光LED的光输出功率随时间的衰减速率相对较快;随老化时间的加长,30 mA电流驱动下,GaN基白光LED相对光谱中黄光比重先增加再减小。其原因归结为荧光粉受热降解导致转换量子效率降低和荧光粉本身对短波长的光散射共同作用的结果。最后计算出用于实验的白光LED寿命为457 h。     

Characterizing slope correction methods applied to satellite radar altimetry data: A case study around Dome Argus in East Antarctica

Slope correction is important to improve the accuracy of satellite radar elevation measurements by mitigating the slope-induced error (SE), especially over uneven ground surfaces. Although several slope correction methods have been proposed, guidance in the form of stepwise algorithm on how to implement these methods in processing radar altimetric data at the coding level, and the differences among these methods need to be presented and discussed systematically. In this paper, three existing types of slope correction methods—the direct method (DM), intermediate method (IM), and relocation method (RM, further divided into RM1 and RM2)—are described in detail. In addition, their main differences and features for various scientific applications are analyzed. We conduct a systematic experiment with CryoSat-2 Low Resolution Mode (LRM) data in a physically stable area around Dome Argus in East Antarctica, where in-situ measurements were available for comparison. The slope correction is implemented separately using the three methods, with the latest high-accuracy Reference Elevation Model of Antarctica (REMA) as the a-priori topography model. The bias and precision of the slope-corrected CryoSat-2 data results from the RM2 is ?0.18 ± 0.86 m based on the comparison with the field Global Navigation Satellite System (GNSS) data. The results from the RM2 indicate higher precision compared to those from the RM1. According to the correlation analysis of the slope-corrected CryoSat-2 data results (RM1 and RM2), the bias enlarges and the precision becomes worse when the surface slope increases from 0 to 0.85°. After a comprehensively comparative analysis, we find that the results from the RM1 and RM2 are superior in precision (0.93 m and 0.86 m) with respect to the GNSS data. The relatively low precision (1.22 m) from the IM is due to the potential error from the a-priori digital elevation model (DEM). The DM has the lowest precision (2.66 m). Another experiment over rough topography in West Antarctica is carried out for comparison, especially between the RM1 (precision of 15.27 m) and RM2 (precision of 16.25 m). In general, the RM is recommended for the SE elimination among the three methods. Moreover, the RM2 is firstly considered over smooth topography due to the superior performance in bias and precision, while the RM1 is more suggested over the rough topography because of the slightly smaller bias and better precision. The IM relies much on the accuracy of the a-prior DEM and is not usually recommended, because of the strict requirement in the sampling time between the radar altimetry data and the a-priori DEM to avoid any surface change over time.