前馈功放线性化技术的研究

将前馈功放线性化的过补偿方法与传统方法相比,过补偿前馈方法不但缩小了电路的尺寸,降低了成本, 而且提高了整个功放系统的效率,是一种较具吸引力的方法。仿真结果表明,它对三阶交调失真的抑制也比传统方法提 高9dB以上。     

格型滤波器和ARMA模型的格型辨识法

本文介绍了ARMA模型,总结了格型滤波器的三种算法及格型滤波器的特性,然后把格型滤波器应用到ARA模型的辨识中去,详细推导了ARMA模型的格型迭代辨识法。     

信息融合方法在组网数据处理中的应用

在实际应用中往往采用多测向站来测定位置信息。对多个测向站测量数据的综合处理,关系到如何正确应用所得测向数据信息的重要问题。针对多个测向站的冗余方案,给出了数据融合的应用方法。     

Observations of 1–30 MeV gamma rays from the galactic center

Preliminary results are reported for gamma ray observations of the galactic center region made during a 15 hour balloon flight from Alice Springs, Australia on April 18, 1979. The observations were carried out with the UCR double-scatter gamma-ray telescope at energies of 1 to 30 MeV. The observations are compatible with a galactic source of approximately equal brightness along the region 300°<ℓII<60°. The energy distribution joins smoothly to previous spark chamber results at energies above 30 MeV and to scintillator results below 1 MeV. It appears to be a combination of nuclear gamma ray lines superimposed on a bremsstrahlung spectrum with a power law (1.3±.7) × 10⁻³ E⁻(^1.7±.2). The ¹²C* line at 4.4 MeV appears to be present with a significance of about 16σ. The flux in the line is (6±3) × 10⁻⁴photons cm⁻²s⁻¹rad⁻¹. The oxygen line at 6.1 MeV does not seem to appear significantly above background.     

一种以垂直弹轴方向出伞的回收系统

文中介绍一种新型的回收系统及其试验结果,这种回收系统的减速伞(系统)的弹出方向是沿着垂直弹轴方向的。     

高能推进剂主要组分对燃烧效率影响研究

利用燃烧残渣中活性铝含量分析、真空爆热特性和发动机试验手段，研究了高能推进剂中主要组分对推进剂燃烧效率的影响。实验结果表明，增塑剂的种类和含量是影响燃烧效率的主要因素，ＡＰ含量及固体组分的粒度级配也有明显的影响。ＢＳＦХ７５发动机试车结果表明，铝粉粒度级配的改变，可以使高能推进剂比冲效率由０．８８提高到０．９２。     

速率捷联制导系统工具误差分析方法

本文首先介绍速率捷联制导系统工具误差分析的主要内容,接着使用一种新的方法建立了数学模型,并通过一个范例进行了数学仿直.仿真结果证明,本文提出的算法是可信的.     

GPS total electron content and surface latent heat flux variations before the 11 March 2011 M9.0 Sendai earthquake

The present paper describes the variations of the GPS total electron content (TEC) from the International GNSS service network and surface latent heat flux (SLHF) from the Scientific Computing Division of the National Center for Atmospheric Research (NCAR) before the 11 March 2011 M9.0 Sendai earthquake, respectively. The analysis shows pronounced enhancements in the GPS TEC and SLHF a few days prior to the earthquake event. The maximum increase in the GPS TEC was about 30 TECu with an extended spatial distribution on a geomagnetically quiet day (Dst ? −20 nT, between two moderate geomagnetic storms), 8 March, 3 days prior to the earthquake. This giant positive disturbance was possibly associated with the impending disastrous earthquake and contributed from the enhanced solar radiation. Moreover, there were several anomalous regions of SLHF on the global map, but an area of enhanced SLHF very close to the epicenter. The purpose of this paper is to report the existence of the changes in surface and ionosphere, and show the potential application of multi-source data to identify seismic precursors.     

CFCC的几种声学参量表征方法比较

化学气相渗透(CVI)制备的CFCC的质量控制非常困难。研究该材料质量的无损检测方法对材料使用及性能表征等都具有重要意义。针对声衰减严重的问题,采用穿透法测量各声学参量,用声速、衰减、非线性等相关参量评价材料的均匀性,同时用金相法进行对比测试。结果表明:声速、衰减、非线性等参量可准确地评价材料均匀性,其中声速评价是最成熟的表征方法。     

Anomalous enhancement of electric field derived from ionosonde data before the great Wenchuan earthquake

The seismo-ionospheric coupling is a hot topic of modern scientific research. One of the most reasonable mechanisms is the hypothesis of quasistatic electric field. With a preliminary analytical method, electric field in F2-region before Wenchuan earthquake was derived from the five lower latitude ground-based ionosondes: Lhasa (29.63°N, 91.17°E), Chongqing (29.50°N, 106.40°E), Kunming (25.00°N, 102.70°E), Guangzhou (23.15°N, 113.35°E) and Haikou (23.15°N, 110.35°E). The results show that there was an anomalous enhancement of electric field in F2-region close to the epicenter with maximal amplitude ∼2 mV/m (about 10 times of the background) at 15:00 LT on 9 May, which is in line with the amplitudes of anomalous electric field related to some previous earthquakes observed by satellites.