硅酸钾保护处理氧化锌填料的研究

为改善氧化锌的抗紫外辐照性能,用模数为2—3的硅酸钾对氧化锌进行包复处理,得到了软性填料PS-ZnO。其SiO_2含量大于9%,优于文献值(8%)。     

风云-3A卫星TOU臭氧总量地基对比验证分析

通过地基臭氧总量观测,对风云三号(FY-3A)气象卫星TOU(2009年7月至2013年12月)臭氧总量开展检验分析.结果显示,TOU臭氧总量与地基测值之间的线性相关系数达到0.95以上,相对差别(RD)为(-0.16+4.3)%.赤道地区RD随地基测值的上升明显,太阳天顶角(SZA)为70°以上时TOU臭氧总量明显下降,75°~85°有一4%~-10%不等的降幅.云量变化(0~100%)或云高变化(1~15 km)对RD的影响在±2%以内.RD随着吸收性气溶胶(AI为正值)有-2%~-5%的变化,在南半球中纬度地区明显.TOU与地基Dobson,Brewer及SAOZ光谱仪测值的RD分别为(0.6±0.17)%,(0.05±0.2)%,(0.04±0.01)%.当地基臭氧总量在200 DU以下时,TOU值低于Dobson或SAOZ测值;而在430~500 DU时,TOU高于SAOZ值2%~6%.TOU分别与Dobson,Brewer,SAOZ的RD对SZA(70°以下)、云量变化均不敏感,但TOU分别与Brewer,SAOZ的RD在云高5 km以上时或随AI的增加均出现一定的趋势特征.     

航空铝试块疲劳裂纹相控阵超声成像检测

表面疲劳裂纹扩展可导致结构失效,利用相控阵超声成像技术监测疲劳裂纹,获取结构完整性评价所需裂纹信息,可及时对结构失效提出安全预警。采用三点弯曲疲劳试验法在航空铝试块上生长疲劳裂纹,对裂纹开口面材料进行逐步切削来获得不同长度的疲劳裂纹,利用相控阵超声全矩阵采集(FMC)和全聚焦方法(TFM)获得的裂纹尖端和开口图像信息来监测裂纹扩展和测量裂纹长度,并测试了相控阵超声探头放置位置、裂纹张开/闭合、裂纹表面粗糙度对超声成像检测效果的影响。研究结果表明:相控阵超声探头从裂纹侧面入射检测能更好地对裂纹进行超声成像,并真实反映材料内部裂纹扩展前缘形貌。当疲劳裂纹长度大于3倍超声波长时,裂纹尖端和开口图像完全分离,相控阵超声全矩阵采集和全聚焦成像技术可有效测量裂纹长度,测量误差小于0.2 mm。相比裂纹张开时,疲劳裂纹闭合效应会使裂纹尖端超声图像信号减弱4.5 dB,长度测量值小0.6 mm。      

环氧共混树脂的光固化及其表面化学反应

研究了双酚A型环氧树脂与有机硅环氧树脂紫外光辐照共混改性的工艺条件,并采用扫描电镜和X射线光电子能谱等分析手段对树脂改性效果和表面的物理和化学变化进行了研究.结果表明,采用二苯基碘鎓六氟磷酸盐为光引发剂,当质量分数为5％时,随着E-44含量的增加,共混树脂体系的光固化速度加快.当两者质量比为1∶ 2时,经15min的紫外光辐照后,共混树脂体系的凝胶率可达93％.X射线光电子能谱分析结果表明,在光固化的同时,试样的表面被紫外光辐照时产生的臭氧和原子氧部分氧化,转化为一层含C的氧化硅(SiO _{x )膜.}      

小管径高精度超声波流量计设计

航天器推进剂在轨剩余量测量一直是航天器在轨管理所面临的一个难题.提出采用超声波流量计测量推进剂在轨剩余量的方法,并给出了超声波流量计的设计方案.设计的新型超声波流量计结构,通过改变超声换能器的安装方式,从而延长了超声波传播路径,减少了传播过程中超声波的衰减.通过以单片机和FPGA为主控制器、以高精度时间测量芯片作为数据采集模块的流量计软硬件系统实现了超声波流量计对液体流量的高精度测量.通过恒速测试、交变流速测试和总量测试表明,该系统测量精度达到了0.5%,可满足目前航天器推进系统推进剂剩余量的在轨测量要求.     

基于时延的高精度泄漏点超声定向检测方法

针对当前气体泄漏点检测定向精度低的情况,提出一种基于时延的高精度超声检测方法.该方法利用3个呈等边三角形分布的超声传感器接收由泄漏点产生的超声波,根据3路信号的相对时延值确定泄漏点的方向.为克服采样间隔对时延估计精度的限制,采用基于三次样条插值的时延估计算法估计信号时延值,并对不同核窗长度下的各100组实验数据的时延值进行误差统计,得到其均方差并与其Cramér-Rao下界比较,发现二者的变化趋势具有良好的一致性.在此基础上研究了时延值均方差,超声传感器间距和泄漏点距离对定向精度的影响.结果表明:定向误差随时延值均方差增大而增大,随超声传感器间距增大而减小,随泄漏点距离增大而增大；定向精度比单超声传感器检测方法提高7 ～10倍.     

基于时延的高精度泄漏点超声定向检测方法

针对当前气体泄漏点检测定向精度低的情况,提出一种基于时延的高精度超声检测方法.该方法利用3个呈等边三角形分布的超声传感器接收由泄漏点产生的超声波,根据3路信号的相对时延值确定泄漏点的方向.为克服采样间隔对时延估计精度的限制,采用基于三次样条插值的时延估计算法估计信号时延值,并对不同核窗长度下的各100组实验数据的时延值进行误差统计,得到其均方差并与其Cramér-Rao下界比较,发现二者的变化趋势具有良好的一致性.在此基础上研究了时延值均方差,超声传感器间距和泄漏点距离对定向精度的影响.结果表明:定向误差随时延值均方差增大而增大,随超声传感器间距增大而减小,随泄漏点距离增大而增大;定向精度比单超声传感器检测方法提高7～10倍.     

脉冲射流强化喷流混合的数值模拟

采用高振幅低流量射流射入亚音剪切层以强化喷流混合,对利用脉冲射流强化喷流混合的流场进行了数值模拟.利用有限体积法和重整化群(RNG)k-ε湍流模型求解N-S方程.分别进行了低亚音马赫数及中等亚音马赫数喷流混合的数值模拟.数值模拟结果显示,无论是对于低亚音速热喷流还是中等亚音速热喷流,脉冲激励引起喷流在与激励源平行的平面迅速扩展,在与之垂直的平面收缩,当脉冲射流激励的斯德鲁哈尔数在0.2时,可以得到较好混合,而且少量的射流流量(占主流流量的1%)可以极大地增加速度及温度的衰减率,随着流量的增加(占主流流量的3%),喷流混合得到进一步的加强.     

星载辐照剂量深度分布探测仪设计

空间带电粒子对在轨航天器会产生辐照剂量效应,严重时可导致星载设备及航天器等的性能衰减及寿命下降,因此采用了星内多点多方位的辐照总剂量探测技术.在中国首次采用深度剂量监测方案.每个探头设置5个剂量监测点,对应屏蔽厚度分别为0（开窗）,1mm,2.5mm,3.5mm,6mm的铝结构,探测剂量总量程为2×106rad （Si）,最高灵敏度为1rad （Si）.所设计的星载辐照剂量深度分布探测仪可以对卫星在轨遭受的辐照剂量进行实时监测和预警,其探测结果用于研究星内剂量深度分布,对卫星载荷在轨工作状态进行分析评估,并为后续卫星的抗辐照加固设计提供依据.      

武汉上空背景Na层长期变化和夜间变化特征的激光雷达观测研究

通过分析武汉大学激光雷达在2001年4月到2004年12月的观测数据,研究武汉(30.5°N,1144°E)上空背景Na层的长期(时间尺度大于1年)变化和夜间变化特征,并讨论了这种变化特征可能的产生原因.Na层长期变化的观测研究表明,背景Na层柱密度最大值出现在11月,大约是5月份最小值(1.6×109 cm-2)的2倍;质心高度最大出现在8月,比年平均高度91.5km高14km,最小值出现在5月,为91.2km;rms宽度平均值为4.5 km,最大值和最小值分别出现在12月和3月;月平均Na层质心高度和均方根宽度都具有准半年周期的变化,但两者变化的相位相反.除了长期变化外,背景Na层还呈现出明显的夜间变化特征:除凌晨短暂的时间外,Na层柱密度随夜间时间增加,于0530 LT达到最大值(2.9×109 cm-2);峰值对应的高度随时间下降;质心高度随时间缓慢增加但在凌晨迅速下降基本恢复到入夜时的高度;整夜背景Na层平均柱密度、峰值对应的高度、质心高度和rmS宽度起伏值分别为1.1×109cm-2,3 km,0.3 km和0.8 km.      

管路布局方式对载人航天器辐射器散热能力的影响分析

以采取双管路并联结构的载人航天器圆筒辐射器为研究对象,建立了辐射器散热能力数值分析模型,对比分析了不同参数下,并联支路工质相同流动方向和相反流动方向两类布局方式给辐射器散热能力带来的影响,选取的参数包括管路长度、管路进口工质温度和液体工质流量。计算结果表明,在辐射器面板面积和流体回路长度相同的前提下,两类管路布局方式对应的辐射器散热能力存在不可忽视的差别。随着管路长度的增加,入口工质温度的增加,工质流量的减小,工质流向相同的辐射器散热能力越来越高于工质流向相反的辐射器。在文章的参数设定下,工质流向相同的辐射器与工质流向相反的辐射器间最大散热能力差别可达到19.5%,最小散热能力差别可达到16.7%。     

UV disinfection system for cabin air

The air of indoor cabin environments is susceptible to contamination by airborne microbial pathogens. A number of air treatment processes are available for inactivation or removal of airborne pathogens; included among these processes is ultraviolet (UV) irradiation. The effectiveness of UV-based processes is known to be determined by the combined effects of UV dose delivery by the reactor and the UV dose–response behavior of the target microbe(s). To date, most UV system designs for air treatment have been based on empirical approaches, often involving crude representations of dose delivery and dose–response behavior. The objective of this research was to illustrate the development of a UV system for disinfection of cabin air based on well-defined methods of reactor and reaction characterization.     

Soviet-Indian research of cosmic radiation by high altitude balloons

The report presents some results on the cosmic radiation intensity research carried out with the high-altitude balloons for the period of 1977–1979. The intensity of gamma-radiation with the energy above 40 MeV was measured in two balloon flights at an altitude of 4–7 g/cm² of residual atmosphere in the vicinity of the geomagnetic equator. A temporal analysis of the intensity to discover fluctuations with periods in the range of 4–60 min was made. Quasi-periodic fluctuations of gamma-radiation intensity with 5 min periods, amplitude ～20% and duration of several hours were discovered. Possible mechanisms of such fluctuation appearance are discussed.The report gives the results of measuring downward, upward and horizontal electron fluxes in the vicinity of the equator. The obtained data and the data provided by satellites are compared. The report discusses the prospects of further joint Soviet-Indian research of cosmic gamma-radiation.     

热处理对纳米氧化锆热障涂层热物性的影响

采用大气等离子喷涂(APS)在GH33基体上制备了氧化锆纳米结构涂层,运用X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电镜(TEM)和拉曼光谱(RS)等分析手段对原料粉末和涂层的显微结构、相组成进行了观察和确定,分别利用激光脉冲技术测量了热处理前后涂层的热扩散率.实验结果表明,等离子喷涂氧化锆纳米涂层颗粒分布在65~110nm之间,大于原料粉末的40~70nm,涂层主要由亚稳四方相氧化锆组成.1050℃下热处理34h后,涂层的热扩散率从制备态的2.15×10-3~2.75×10-3cm2/s升高到2.65×10-3~3.25×10-3cm2/s.      

Growth of wheat under one tenth of the atmospheric pressure.

Wheat plants were grown in twin closed growth chambers under normal and reduced atmospheric pressures. For the first 22 days from sowing, the reduced pressure was maintained at 200 hPa, and at 100 hPa for the remaining 27 days until harvest. These pressures were obtained by evacuation of the chamber and adding oxygen (170 and 79 hPa respectively) and carbon dioxide (0.65 and 1.0 hPa respectively; about 2 and 3 times above the control). Eighty-seven per cent of the final dry mass was produce under 100 hPa treatment. Growth and development of wheat are not negatively affected by low pressure treatment. Compared to the control, final dry mass increased by 76%, leaf number by 133%, and ear number by 35%, probably due to elevation of CO2. Shortening of shoot parts and increases in chlorophyll and proteins content are not in accordance with a predicted CO2 effect and could be attributed to the N2 removal and the subsequent alteration in gas diffusion rate.     

Guidance and control of a balloon-borne X-ray telescope with onboard and ground based computers

The balloon payload HEXE ^A) is designed to observe cosmic X-ray sources in the energy range 20–250 keV. Its detectors are ‘Phoswich’ scintillators with a total sensitive area of 2300 cm² and a cooled Ge solid state detector with an area of 100 cm² [1]. The instrument was flown successfully in 1980 and 1981 from Palestine, Texas.Here we describe the control of the instrument and guidance of the telescope as well as the method of data retrieval and real time analysis. These tasks are performed by a ground based minicomputer (HP 1000) and onboard microprocessors (M 6800) which are linked together by data and command telemetry.     

Relativistic electrons high doses at International Space Station and Foton M2/M3 satellites

The paper presents observation of relativistic electrons. Data are collected by the Radiation Risk Radiometer-Dosimeters (R3D) B2/B3 modifications during the flights of Foton M2/M3 satellites in 2005 and 2007 as well as by the R3DE instrument at the European Technology Exposure Facility (EuTEF) on the Columbus External Payload Adaptor at the International Space Station (ISS) in the period February 20 – April 28, 2008. On the Foton M2/M3 satellites relativistic electrons are observed more frequently than on the ISS because of higher (62.8°) inclination of the orbit. At both Foton satellites the usual duration of the observations are a few minutes long. On the ISS the duration usually is about 1 min or less. The places of observations of high doses due to relativistic electrons are distributed mainly at latitudes above 50° geographic latitude in both hemispheres on Foton M2/M3 satellites. A very high maximum is found in the southern hemisphere at longitudinal range 0°–60°E. At the ISS the maximums are observed between 45° and 52° geographic latitude in both hemispheres mainly at longitudes equatorward from the magnetic poles. The measured absolute maximums of dose rates generated by relativistic electrons are found to be as follows: 304 μGy h⁻¹ behind 1.75 g cm⁻² shielding at Foton M2, 2314 μGy h⁻¹ behind 0.71 g cm⁻² shielding at Foton M3 and 19,195 μGy h⁻¹ (Flux is 8363 cm⁻² s⁻¹) behind les than 0.4 g cm⁻² shielding at ISS.     

Soil moisture mapping over the Chinese Loess Plateau using ENVISAT/ASAR data

In this paper, we used the available algorithm for soil moisture estimation over LOPEX05 (the Loess Plateau land surface process Experiment (2005)) area. The available algorithm used ENVISAT/ASAR AP mode VV polarization observational data at a low incidence angle and ground measured soil moistures. The ground measurements were performed in the summer of the 2005 during the LOPEX05 field campaign. The validated results indicate that an average difference between the soil moistures estimated from the microwave remote sensing and ground measurements is less than 0.02 cm³/cm³, with a RMS error of 2.0%, and a maximum less than 0.04 cm³/cm³. The algorithm was applied to the surface soil moisture mapping later. The results show that this algorithm is suitable for monitoring soil moisture information of the agricultural fields over the Chinese Loess Plateau, when ground land cover situation and the resolution of imagery data are taken into account. However, we also find that there are large differences over the steep slope region, the edge of mesa. The results are not acceptable for surface soil moisture estimation in these regions. Thus, the surface soil moisture retrieval in the steep slope region of the Loess Plateau need to be further investigated in the future.     

Hybrid simulations of the O ion escape from Venus: Influence of the solar wind density and the IMF x component

As an initial effort to study the evolution of the Venus atmosphere, the influence of the solar wind density and the interplanetary magnetic field (IMF) x component (the x-axis points from Venus towards the Sun) on the O⁺ ion escape rate from Venus is investigated using a three-dimensional quasi-neutral hybrid (HYB-Venus) model. The HYB-Venus model is first applied to a case of the high-density (100 cm⁻³) solar wind interaction with Venus selected from the Pioneer Venus Orbiter observations to demonstrate its capability for the study. Two sets of simulations with a wide range of solar wind densities and different IMF x components are then performed. It is found that the O⁺ ion escape rate increases with increasing solar wind density. The O⁺ ion escape rate saturates when the solar wind density becomes high (above 100 cm⁻³). The results also suggest that the IMF x component enhances the O⁺ ion escape rate, given a fixed IMF component perpendicular to the x-axis. Finally, the results imply a higher ion loss rate for early-Venus, when solar conditions were dramatically different.     

FIGARO: An experiment for pulsar and variable source studies in the MeV range

We present a large area, balloon borne, NaI(Tl) detector for low-energy gamma rays with temporal signature : FIGARO.The main detector is a mosaic of 12 NaI(Tl) tiles 22.5 × 15 × 5 cm, for a total geometric area of 4050 cm².In the energy band 140 keV - 6 MeV, the expected background counting rate at float altitude is in the range of two to three thousands counts per second.For pulsar analysis the expected 3δ sensitivity for 5 hours exposition time is 2.5 10^?4 ph/cm².s.MeV (150–500 keV) 1.5 10^?4 ph/cm².s.MeV (1–6 MeV). This performance, together with the large effective area and the relatively short duration of a balloon flight, make FIGARO particularly suitable for the identification of sources by means of temporal analysis.For objectives in the Northern sky, including the Crab pulsar, a transmediterranean flight is planned for the summer of 1982 ; a Southern mission is scheduled in Brazil for the fall of 1983 (Vela, PSR 1822-09).