虚拟仪器在教学中的应用

主要介绍了Multisim2001中虚拟仪器库中函数发生器、示波器的使用方法及功能；并在Multisim2001环境中仿真单管放大电路、桥式整流滤波电路。由调试结果，分析了其在教学中应用的可行性。     

MOS RF reliability subject to dynamic voltage stress-modeling and analysis

Dynamic stress on MOSFETs with 900-MHz inverter-like waveforms as well as static (or dc) stress were evaluated experimentally. It showed that the degradation due to dynamic stress is less than that of dc stress for our test transistors. A compact model is used to evaluate the degradation in radio frequency performances, such as transconductance, cutoff frequency, linearity, and noise figure. A class-AB power amplifier is presented as an example to demonstrate the effect of dynamic stress on RF circuit performance.     

超宽带通信技术及其在军事通信方面的应用

本文给出了超宽带(Ultra-wide Bandwidth:UWB)系统的信号表示形式,分析了其具体含义、信号特点及UWB通信系统的性能,结合当前军事通信的特点及发展趋势,介绍了超宽带脉冲通信在军事通信领域的应用现状及前景。     

On the mechanism of phenol ozonolysis

The mechanisms of liquid-phase phenol ozonation are revised. A new mechanism in which a significant role is played by free-radical reactions is suggested for this process.     

Single-carrier frequency-domain equalization with decision-feedback processing for time-reversal space-time block-coded systems

In this letter, we propose to introduce frequency-domain equalization with decision-feedback processing (FD-DFE) for time-reversal space-time block-coded (TR-STBC) systems with multiple transmit antennas to effectively achieve both spatial diversity and multipath diversity over frequency-selective channels. This letter will also present a theoretical performance analysis result that relates the minimum mean-squared error (MMSE) to a new tight upper bound for the probability of error. It is shown that the new bound is not only valid for the TR-STBC systems, but also valid for single-input single-output, single-input multiple-output, and multiple-input multiple-output systems with MMSE equalization.     

视频转换编码的快速图标插入技术研究

数字视频转换编码技术为传输带宽匹配等问题提供解决方案,在许多具体应用中,要求在转换编码时在视频图像中加入图形标识,本文对转换编码中图标插入技术进行了分析和研究,给出了一种快速图标插入转换编码技术,提出了图标插入后运动矢量及宏块模式判别等问题的优化算法,实验结果表明,使用本算法进行图标插入的转换编码流质量良好.     

Submillimeter-wave large-orbit gyrotron

We develop a thermionic-emission electron-optical system forming a dense beam of electrons moving along helical trajectories round the axis of a gyrotron cavity. The maximum beam current is 4 A and the pitch-factor of electrons is 1.0 for a particle energy of 250 keV and a pulse duration of 10 µs. Using such a beam in a gyrotron operated at the third cyclotron harmonic, we obtain single-mode oscillation with a power of 10 µs in the TE_3,8 and TE_3,9 modes with frequencies 371 and 414 GHz, respectively.     

Molecular hydrodynamics of degenerate weakly nonideal bose gas. I. Generalized equations of two-fluid hydrodynamics

A degenerate weakly nonideal Bose gas is investigated at temperatures near zero. Relations connecting the irreducible Green's functions are used to obtain exact expressions for the two-time temperature-dependent Green's functions. In the case of weak nonideality an expression possessing interpolation properties with respect to the frequency and momentum is obtained for the density—density Green's function. At low frequencies, the results of two-fluid hydrodynamics are reproduced. At wavelengths less than the mean free path the energy of the elementary excitations and the damping obtained in the paper agree with the results of perturbation theory with respect to the coupling constant. An expression for the operator of the superfluid velocity is obtained.In memory of Nikolai Nikolaevich BogolyubovV. A. Steklov Mathematics Institute, Russian Academy of Sciences. Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 93, No. 3, pp. 412–465, December, 1992.     

Enhanced backscattering: the universal wave phenomenon

Backscattering enhancement is discussed as a universal wave phenomenon inherent to waves of whatever physical nature: electromagnetic, acoustic, spin, etc. This phenomenon arises due to multichannel wave propagation from a source to a scatterer and back and may be observed in the vicinity of the source because of mutual coherence of waves passing in opposite directions along identical (coherent) channels. Backscattering enhancement may be revealed when the wave field is scattered: by a system of chaotically distributed scatterers or by a system of inhomogeneities; by a body embedded in a turbulent medium; by a single body placed near an interface or within a waveguide (randomness of body position is assumed); by a body of complex form or a system of several scatterers randomly oriented in space; by a rough surface; and by many other physical systems. Possible practical applications of these effects are analyzed     

原伊鲁烷型倍半萜醇芳香酸酯的碳谱研究

作者自人工发酵得到的蜜环菌Armillaria mellea (Vahl.ex Fr.) Quel.菌丝体中分离出十七个原伊鲁烷型倍半萜醇芳香酸翻,在研究这些化合物的化学结构中,对其全去偶碳谱,偏共振谱或INEPT谱,C-H COSY谱和远程C-H COSY谱进行比较仔细地分析,指定了每个化合物各碳的归属,讨论了其碳谱的特征,并指出¹³C NMR谱是对新的该类型化合物结构测定的有效方法.