光学主被动复合导引头及关键技术

红外成像探测,激光成像测距的光学主被动复合导引头工作波长短,具有良好的空间分辨率和速度分辨率,可大幅度提高对RV的识别距离、末制导精度及杀伤概率。简要介绍了国外光学主被动复合导引头的研发动态,基本原理及关键技术达到的水平。提出了跟踪研究的基本思路,途径及建议。     

An optimization iterative algorithm based on nonnegative constraint with application to Allan variance analysis technique

It is well known that inertial integrated navigation systems can provide accurate navigation information. In these systems, inertial sensor random error often becomes the limiting factor to get a better performance. So it is imperative to have accurate characterization of the random error. Allan variance analysis technique has a good performance in analyzing inertial sensor random error, and it is always used to characterize various types of the random error terms. This paper proposes a new method named optimization iterative algorithm based on nonnegative constraint applied to Allan variance analysis technique to estimate parameters of the random error terms. The parameter estimates by this method are nonnegative and optimal, and the estimation process does not have matrix nearly singular issues. Testing with simulation data and the experimental data of a fiber optical gyro, the parameters estimated by the presented method are compared against other excellent methods with good agreement; moreover, the objective function has the minimum value.     

A Controllable and Observable Protein Cystallization Facility.

A Controllable and Observable Protein Crystallization Facility (ACOP) was developed in 1999 for space experiment in the Get Away Special canister of Space Shuttle. To regulate the vapor diffusion rate, in a crystallization chamber, five cells each containing precipitant solution of different concentrations, exposed to one protein cell in turn. Five layers of chambers were overlapped coaxially. The crystallization process was observed and recorded by digital cameras. Structure of facility and result of image sequence were given.     

Separation of the Magnetic Field into External and Internal Parts

The magnetic field of a planet or a planetary moon contains contributions from a variety of sources in the environment of the body (external sources) and its interior (internal sources). This chapter describes different methods that have been developed for the separation of external and internal source contributions, and their application to selected planets and one of Jupiter’s moons, Ganymede.     

Characterisation of residual ionospheric errors in bending angles using GNSS RO end-to-end simulations

Global Navigation Satellite System (GNSS) radio occultation (RO) is an innovative meteorological remote sensing technique for measuring atmospheric parameters such as refractivity, temperature, water vapour and pressure for the improvement of numerical weather prediction (NWP) and global climate monitoring (GCM). GNSS RO has many unique characteristics including global coverage, long-term stability of observations, as well as high accuracy and high vertical resolution of the derived atmospheric profiles. One of the main error sources in GNSS RO observations that significantly affect the accuracy of the derived atmospheric parameters in the stratosphere is the ionospheric error. In order to mitigate the effect of this error, the linear ionospheric correction approach for dual-frequency GNSS RO observations is commonly used. However, the residual ionospheric errors (RIEs) can be still significant, especially when large ionospheric disturbances occur and prevail such as during the periods of active space weather. In this study, the RIEs were investigated under different local time, propagation direction and solar activity conditions and their effects on RO bending angles are characterised using end-to-end simulations. A three-step simulation study was designed to investigate the characteristics of the RIEs through comparing the bending angles with and without the effects of the RIEs. This research forms an important step forward in improving the accuracy of the atmospheric profiles derived from the GNSS RO technique.     

GPS接收机干扰频率特性研究

针对直接序列扩频接收机的特点,研究了GPS接收机的解扩过程对干扰信号的影响,分析了干扰信号的频率与对接收机干扰效果的关系,从而解释了不同频率干扰的作用机理及干扰效率的差别。最后通过对GPS接收机的干扰实验验证了分析的正确性。     

基于STFT的Wigner-Ville分布交叉项抑制

对于多分量信号,Wigner—Ville分布（WVD）的时频能量集中但存在交叉项,而由短时傅里叶变换（STFT）模的平方得到的谱图无交叉项但时频聚集性较差。基于STFT谱图与WVD的联合算法,可以有效地抑制WVD中的交叉项干扰,同时保持了WVD的较高时频聚集性,是一种行之有效的WVD改进算法。     

Best linear unbiased filtering with nonlinear measurements for target tracking

In tracking applications, target dynamics are usually modeled in the Cartesian coordinates, while target measurements are directly available in the original sensor coordinates. Measurement conversion is widely used such that the Kalman filter can be applied in the Cartesian coordinates. A number of improved measurement-conversion techniques have been proposed recently. However, they have fundamental limitations, resulting in performance degradation, as pointed out in a recent survey conducted by the authors. A filter is proposed here that is theoretically optimal in the sense of minimizing the mean-square error among all linear unbiased filters in the Cartesian coordinates. The proposed filter is free of the fundamental limitations of the measurement-conversion approach. Results of an approximate, recursive implementation are compared with those obtained by two state-of-the-art conversion techniques. Simulation results are provided.     

Physics of ion acceleration in the solar flare on 2005 September 7 determines γ-ray and neutron production

Relativistic neutrons were observed by the neutron monitors at Mt. Chacaltaya and Mexico City and by the solar neutron telescopes at Chacaltaya and Mt. Sierra Negra in association with an X17.0 flare on 2005 September 7. The neutron signal continued for more than 20 min with high statistical significance. Intense emissions of γ-rays were also registered by INTEGRAL, and during the decay phase by RHESSI. We analyzed these data using the solar-flare magnetic-loop transport and interaction model of Hua et al. [Hua, X.-M., Kozlovsky, B., Lingenfelter, R.E. et al. Angular and energy-dependent neutron emission from solar flare magnetic loops, Astrophys. J. Suppl. Ser. 140, 563–579, 2002], and found that the model could successfully fit the data with intermediate values of loop magnetic convergence and pitch-angle scattering parameters. These results indicate that solar neutrons were produced at the same time as the γ-ray line emission and that ions were continuously accelerated at the emission site.