Time-dependent thermal X-ray afterglows from GRBS

Time-dependent thermal X-ray spectra are calculated from physically plausible conditions around GRB. It is shown that account for time-dependent ionization processes strongly affects the observed spectra of hot rarefied plasma. These calculations may provide an alternative explanation to the observed X-ray lines of early GRBs afterglows (such as GRB 011211). Our technique will allow one to obtain independent constraints on the GRB collimation angle and on the clumpiness of circumstellar matter.     

八丝热线探针制作及其应用

介绍了八丝热线探针的制作工艺,有效地消除了各热丝探头之间的电信号干扰和动力学干扰。实验中使用该探针检测到了湍流边界层内的大尺度旋涡,并测量了它们的强度和尺度。与此同时还获得了速度、湍流强度和功率谱等流场参数,结果与现有典型数据一致。说明本文所述的多丝热线探针具有很强的实用性。     

硼酸盐玻璃中稀土离子的发光研究

应用荧光光谱、红外振动光谱等研究了在可见光区发光的Ｐｒ（３＋），Ｓｍ（３＋），Ｅｕ（３＋），Ｔｂ（３＋），Ｄｙ（３＋），Ｅｒ（３＋）和Ｔｍ（３＋）等镧系稀土离子在硼酸盐玻璃中的发光行为，系统地分析了稀土离子在硼酸盐玻璃基质中的激发谱和发光谱特性。     

多重直扩信号的快速捕获

多重直扩信号的快速捕获得卫星定位及通信系统研制过程中遇到的一个主要课题，它的实现，不仅可以提高系统的多址能力，而且也是系统实现的必备条件，本文阐明了多重直扩信号的来源以及可被分离的理论依据，给出了多重直扩信号快速捕获的硬件实现方案及部分实验结果，得出了一些重要结论。     

小鹰-500飞机疲劳试验载荷谱的编制方法

针对小鹰500飞机的设计和使用特点，选用了FAA推荐的通用飞机实测载荷谱数据，按照民机的TWIST编谱原则编制出用重心过载表示的“飞-续-飞”随机疲劳试验载荷谱，用于小鹰-500飞机机翼疲劳试验，并参照国外文献中有关尾翼载荷谱的保守处理方法，采用了从重心载荷谱计算出配套平衡的平尾机动载荷，将其幅值放大1.2倍和频次放大3倍的做法，编制出了平尾疲劳试验载荷谱。     

Magnetar spectra and twisted magnetospheres

The huge potential drop between the footpoints of the closed field lines in the twisted magnetospheres of magnetars may accelerate electrons up to very high energies, γ ? 10⁶. On the other hand, the comparison between the observed spectra of magnetars and spectra obtained by accurate theoretical models seems to favor of a picture in which the magnetosphere is filled by “slow” electrons (v ? 0.8c), rather than by ultra-relativistic particles.     

Semi-stochastic modification of second-order radial derivative of Abel–Poisson’s formula for validating satellite gravity gradiometry data

The geoid can be used to validate the satellite gravity gradiometry data. Validation of such data is important prior to their downward continuation because of amplification of the data errors through this process. In this paper, the second-order radial derivative of Abel–Poisson’s formula is modified stochastically to reduce the effect of the far-zone geoid and generate the second-order radial derivative of geopotential at 250 km level. The numerical studies over Fennoscandia show that this method yields the gradients with an error of 10 mE and when the long wavelength of geoid is removed from the estimator and restored after the computations (remove–compute–restore) the error will be in 1 mE level. We name this method semi-stochastic modification. The best case scenario is found when the degree of modification of the integral formula is 200 and the long wavelength geoid to degree 100 is removed and restored. In this case the geoid should have a resolution of 15′ × 15′ and the integration should be performed over a cap size of 3°.     

The photometric study of light scattering from the surface of alumina powder and interpretations by Hapke formula

A laboratory experiment helps to understand the light scattering property of regolith like samples with known compositions and other physical parameters. The laboratory data so obtained can be compared with the existing in situ data on celestial objects like asteroids. Further, it may be analyzed with the help of various theoretical models to understand the light scattering processes from regolith more clearly. In this work we have performed laboratory based photometry of the light scattered from the surfaces of powdered alumina (Al₂O₃) at various tilt angles of the sample and at large phase angles, with the particles having diameter 0.3 μm. The wavelength of observation was 632.8 nm. These data have been fitted by a surface scattering model originally suggested by Hapke. Instead of using empirical Henyey–Greenstein phase function to fix the values of albedo and phase function to be used within Hapke formula, we have used Mie theory for the same. This approach helped us to determine the single particle properties such as particle diameter and complex refractive index from surface scattering phase curve alone. Mie theory depends only on the size parameter X(=2π(radius/wavelength)) and complex refractive index (n, k) of the material. Since the absorption coefficient (k) for alumina is known to be very low but not exactly zero, the best fit to the experimental data was obtained by least square technique with k as a free parameter, as the other parameters are known. Finally, we compare our results with other published results and discuss the scope of application of the method we adopted.     

Cosmic Ray Energetics And Mass for the International Space Station (ISS-CREAM)

The Cosmic Ray Energetics And Mass (CREAM) instrument is configured with a suite of particle detectors to measure TeV cosmic-ray elemental spectra from protons to iron nuclei over a wide energy range. The goal is to extend direct measurements of cosmic-ray composition to the highest energies practical, and thereby have enough overlap with ground based indirect measurements to answer questions on cosmic-ray origin, acceleration and propagation. The balloon-borne CREAM was flown successfully for about 161 days in six flights over Antarctica to measure elemental spectra of Z = 1–26 nuclei over the energy range 10¹⁰ to >10¹⁴ eV. Transforming the balloon instrument into ISS-CREAM involves identification and replacement of components that would be at risk in the International Space Station (ISS) environment, in addition to assessing safety and mission assurance concerns. The transformation process includes rigorous testing of components to reduce risks and increase survivability on the launch vehicle and operations on the ISS without negatively impacting the heritage of the successful CREAM design. The project status, including results from the ongoing analysis of existing data and, particularly, plans to increase the exposure factor by another order of magnitude utilizing the International Space Station are presented.     

低温辐射计吸收腔研制

针对高灵敏度低温辐射计研制需求,提出一种低温辐射计吸收腔.设计椭球面光阑的多次反射结构,同时采用扩散焊工艺,进而实现了椭球面光阑、斜口—斜底圆柱腔和斜底面三部分的焊接成形,以此形成有效光陷阱,使入射到吸收腔中的辐射被近似完全吸收.制备具备多孔结构的碳纳米管涂层,采用喷涂为主的工艺实现腔体内壁涂层的均匀性分布.基于积分球...