一种高功率宽带光源的研制

报道一种新型的高功率宽带光源 ,它利用 1480nm激光器对掺铒光纤进行抽运 ,经啁啾光纤光栅反射后二次放大输出 ,其功率高达 1 41mW ,线宽为 10nm。该光源工作的线性区间对应的电流为 375～ 6 45mA。     

Perfect difference codes for synchronous fiber-optic CDMAcommunication systems

In this paper, we introduce the perfect difference sets and propose a synchronous fiber-optic code-division multiple-access system (CDMA) using these sets to generate the signature codes. Two interesting properties of these codes are discussed: (1) any two different codes are cyclic-shifted with each other; and (2) the cross correlation between any two different codes is exactly one. Thus, we may treat these codes as quasi-orthogonal codes. Using the first property of these codes, we can simplify design of the transmitter. In the receiver, we can use the second property to effectively eliminate the multiple-user interference (MUI) without reducing the number of usable codes. Based on the proposed transmitter and receiver, the system performance is derived. The numerical examples reveal that the proposed system can provide reliable communication even under heavy load. We believe that the proposed system using perfect difference codes outperforms any other synchronous fiber-optic CDMA systems     

Analysis of low frequency scattering from penetrable scatterers

A method is presented for solving the surface integral equation using the method of moments (MoM) at very low frequencies, which finds applications in geoscience. The nature of the Helmholtz decomposition leads the authors to choose loop-tree basis functions to represent the surface current. Careful analysis of the frequency scaling property of each operator allows them to introduce a frequency normalization scheme to reduce the condition number of the MoM matrix. After frequency normalization, the MoM matrix can be solved using LU decomposition. The poor spectral properties of the matrix, however, makes it ill-suited for an iterative solver. A basis rearrangement is used to improve this property of the MoM matrix. The basis function rearrangement (BFR), which involves inverting the connection matrix, can be viewed as a pre-conditioner. The complexity of BFR is reduced to O(N), allowing this method to be combined with iterative solvers. Both rectilinear and curvilinear patches have been used in the simulations. The use of curvilinear patches reduces the number of unknowns significantly, thereby making the algorithm more efficient. This method is capable of solving Maxwell's equations from quasistatic to electrodynamic frequency range. This capability is of great importance in geophysical applications because the sizes of the simulated objects can range from a small fraction of a wavelength to several wavelengths     

60km车载瑞利测风激光雷达研制

目前我国尚缺乏25~60 km大气风场实时探测手段,为此研制了60 km车载瑞利测风激光雷达。介绍了系统总体结构,对分系统的研制做了详细描述。为提高风场反演的精度,设计了标准具通过率函数校准系统。提出了标准具通过率函数校准方法,并开展实验对标准具通过率函数进行了校准。校准结果表明,接收机性能稳定,各参数测量标准差均小于0.06。该系统在德令哈地区对15~60 km大气风场进行了观测,获得了水平风场的测量结果,并与当地探空气球的探测结果进行了比对,30 km以下一致性较好。对风速、风向测量误差进行了计算,40 km以下,风速测量误差4 m/s,风向测量误差6,40 km以上,风速测量误差8 m/s,风向测量误差18。该系统设计合理,性能稳定,能够实时探测10~60 km大气风场。     

合肥近地面折射率结构常数C_n~2分布特征及分析

本文通过对合肥郊区中科院安光所气象观测场1995年1～3月近地面层折射率结构常数C2n的统计分析，得到了C2n的日变化特征、概率分布等，同时对C2n和近地面气象要素的关系作了讨论。     

一种宽带低损耗声表面波滤波器

阐述了一种利用纵向耦合双模制作宽带低损耗声表面波滤波器的方法，给出了理论计算方法和计算机模拟结果，最后给出了制作中心频率为４５３ＭＨｚ的声表面波滤波器实验结果，插入损耗为１．９ｄＢ，１ｄＢ带宽为６．６６ＭＨｚ，远端带外抑制大于４５ｄＢ。     

用火花电阻计算高压毫微秒脉冲放电参量

本文用火花电阻公式研究了高压毫微秒脉冲参量（脉冲幅值、前沿、宽度）与储能电容的关系。结果表明，用火花电阻等效亚纳秒脉冲放电管击穿后的状态是合适的。     

湍流两相流内弹道模型

采用双流体两相流模型,推导有粘的两相流内弹道基本方程,并且建立了两相相互作用的气固两相湍流数学模型。     

一种新型发射技术-冲压加速原理

介绍一种新型发射技术──冲压加速原理，它在仅仅利用化学能的条件下，可将弹丸加速到超过２ｋｍ／ｓ的非常规初速，加速效率很高，弹迫效率可高达３０％，是一种很有发展前途的超高速发射技术。     

大口径尾翼稳定脱壳穿甲弹全弹道优化设计

研究了应用现代最优化理论对弹炮系统进行多目标优化设计的基本方法和步骤。选用了约束变尺度法对高膛压滑炮配备尾翼稳定脱壳穿甲弹的装药结构和弹形结构参数进行多目标优化设计，得出了较满意的结果。