一种基于音质评估的语音伪装通信新方法

研究一种语音伪装新方法,将保密语音替换成另外一种语音以便于在公网上安全传输。保密语音经2.4kb/低速率压缩编码后,依据设计的客观音质评估模型,将参数隐蔽地嵌入普通语音;检测时利用逆过程恢复保密语音。实验表明算法的信噪比较传统算法提高约3.5dB,并在受到压缩、滤波等攻击时具有较高的鲁棒性。     

电子束激发氧化锆马氏体相变的研究

用JEM-2000FX分析型透射电镜研究了以Al_2O_3为基体、ZrO_2为第二相的氧化锆增韧氧化铝(ZTA)陶瓷。发现马氏体条在ZrO_2/Al_2O_3界面上产生,长大极快,止于ZrO_2/Al_2O_3及ZrO_2/ZrO_2界面,薄膜表面或晶粒内其它马氏体表面上。增强电子束,马氏体条就可穿过ZrO_2/ZrO_2界面,使相邻晶粒中产生马氏体相变。含Y高的ZrO_2相变困难。少数t-ZrO_2,在强电子束照射下不发生相变。     

直通道磁元件磁场测量

为使重离子束从注入器（ＳＦＣ）不经主加速器（ＳＳＣ）直接传输到实验终端。最近在兰州重离子研究装置（ＨＩＲＦＬ）上新建了直通管道系统。在该系统中有３台偏转磁铁和３台四极透镜。本文叙述了它们的测磁内容和方法，给出了激磁曲线、径向和轴向场分布、磁场梯度、等效长度等结果。结果表明：全部符合原设计要求，并有一定的余量。     

Discussion: Competing theories of receptor excitation.

This discussion is mainly an examination of a theoretical idea suggested by Enoch and McConnell. They suggest that a single photoreceptor may be able to respond so that the output of the receptor is "tagged" according to the wavelength of the quantum absorbed. This idea stands contrary to the classical trichromatic scheme, according to which the probability of quantum absorption depends upon the energy of the incident quantum (inversely related to wavelength), but where once a quantum is absorbed all information pertaining to the wavelength associated with that quantum is forever lost. The trichromatic scheme is reviewed, together with the evidence which supports it. Difficulties raised by some of the suggestions of Enoch and McConnell are then evaluated in this context. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On Solving TM0n Modal Excitation in a Ka-Band Overmoded Circular Waveguide by the Conservation of Complex Power Technique

To measure the radiation properties of relativistic diffraction generator (RDG) in Ka-band, a TM0n modal excitation model is established, which consists of an overmoded circular waveguide and a coaxial line feeding probe. Using the transverse E-field mode matching and the conservation of complex power technique (CCPT), we deduce the scattering matrix at coaxial line to coaxial line and coaxial line to circular waveguide junctions. Then using the overall cascaded junction scattering matrix, the numerical results for the reflection coefficient of the coaxial line and the power distribution of TM0n multi-modal are presented. The numerical results are in agreement with HFSS simulation results and experimental results. The analysis shows that by choosing the appropriate position of coaxial line probe, the power proportion of the device operating mode excited in circular waveguide could be the largest.     

Multiple current peaks and spatial characteristics of atmospheric helium dielectric barrier discharges with repetitive unipolar narrow pulse excitation

Atmospheric dielectric barrier discharges driven by repetitive unipolar narrow pulse excitation are investigated numerically by using one-dimensional fluid models.The one-dimensional simulation focuses on the effects of applied voltage amplitude,pulse repetition frequency,gap width and γ coefficient on the multiple-current-pulse (MCP) discharge.The results indicate that the MCP behavior will lead to the stratification of electron density distribution in axial direction.Traditional MCP manipulating methods,such as reducing the applied voltage amplitude,increasing the applied voltage frequency,adjusting the gap width,cannot regulate MCPs exhibiting in this work.Further analyses reveal that the increasing electric field of the cathode fall region is the basis for the emergence of MCP behavior.     

Electron population properties with different energies in a helicon plasma source

The characteristics of electrons play a dominant role in determining the ionization and acceleration processes of plasmas. Compared with electrostatic diagnostics, the optical method is independent of the radio frequency(RF) noise, magnetic field, and electric field. In this paper, an optical emission spectroscope was used to determine the plasma emission spectra, electron excitation energy population distributions(EEEPDs), growth rates of low-energy and highenergy electrons, and their intensity jumps with input powers. The 56 emission lines with the highest signal-to-noise ratio and their corresponding electron excitation energy were used for the translation of the spectrum into EEEPD. One discrete EEEPD has two clear different regions,namely the low-energy electron excitation region(neutral lines with threshold energy of13–15 eV) and the high-energy electron excitation region(ionic lines with threshold energy?19 e V). The EEEPD variations with different diameters of discharge tubes(20 mm, 40 mm,and 60 mm) and different input RF powers(200–1800 W) were investigated. By normalized intensity comparison of the ionic and neutral lines, the growth rate of the ionic population was higher than the neutral one, especially when the tube diameter was less than 40 mm and the input power was higher than 1000 W. Moreover, we found that the intensities of low-energy electrons and high-energy electrons jump at different input powers from inductively coupled(H) mode to helicon(W) mode; therefore, the determination of W mode needs to be carefully considered.     

无刷直流电机的单片机监控系统的研制

分析了无刷直流电机的控制原理,详细介绍了其监控系统的硬件组成和软件设计。     

无刷直流电动机不导通相电流分析

分析了无刷直流电动机在三相六状态及不同的PWM方式下,绕组续流期间不导通相电流,并且指出各有不同。对常用的各种PWM方式通过原理分析及数学推导,得出不导通相电流存在的时段和幅值趋势。并通过实验测试,验证了分析结果。     

500kV变压器空投时涌流分析及保护误动预控措施

在构造由多条500 kV输电线路、多台600～1 000 MW发电机组电力系统组成的物理模型的基础上,探讨和分析了500 kV变压器空载合闸过程产生励磁涌流及和应涌流的原因;阐述了涌流的特点和可能由此带来的实际问题;最后从消除剩磁、抑制涌流、合理设置保护定值3个方面提出了几种目前现场可以采取的预控管理措施。