基于灰色关联分析的网络对抗技术能力评估

网络对抗技术体系是一个灰色系统。针对网络对抗技术能力的抽象性和难以度量性,采用灰色关联分析方法建立网络对抗技术能力评估模型,并结合实例验证了该方法的有效性,较好地解决了网络对抗技术能力评估问题。     

A visualizing application of line integral convolution techniques

The line integral convolution (LIC) technique, a texture synthesis technique, has served as a useful method for visualizing vector data. However, a number of shortcomings have been identified in the LIC technique, not the least of which are that the technique is computationally expensive and adopts a more or less brute force approach. This paper presents a modification of the original LIC method which addresses these shortcomings. Our method, although used for visualizing atmospheric vortical flows, is also applicable to other atmospheric phenomena. In our method we employ a particular colouring scheme to unambiguously identify the nature of the vortical flows irrespective of the hemisphere in which they occur.     

A Power Reflection Technique for Characterization of High Quality Varactor Diodes

High quality varactor diodes are currently characterized by either a "relative impedance" or a "transmission" technique. In view of the present limitations of these methods, a third method, a "reflection" technique, has been proposed. This method requires measuring the power reflected from a diode near its series resonant frequency. The diode is located as the termination of a low impedance coaxial line.The primary virtue of the power reflection technique is the possibility of accurate determination of the diode series resistance. Both the reflection method and the transmission method offer the advantage of microwave characterization near the diode series resonant frequency. The power reflection technique is presently limited to diodes that series resonante below 24 GHz. The accuracy of the technique is limited by possible impedance transformations due to the diode mount and diode package.     

电子课教学与逻辑思维能力的培养

介绍了如何通过电子课的教学培养学生的逻辑思维能力的方法,即在教学中充分利用归纳、演绎、类比等逻辑思维方法进行教学,进而激发学生的学习积极性和自觉性,提高教学质量。     

广义多极子技术在含有尖锐棱边的二维理想导电柱散射问题中的应用

本文探讨了广义多极子技术(GMT)不能处理理想导体尖锐棱边散射问题的根源,并引入有限差分技术,使之与GMT结合形成了可有效处理这类散射问题的混合分析技术,文中算例证明了所得方法的可靠性和有效性。     

通信对抗中的自适应滤波技术

自适应滤波是在维纳滤波和Kalman滤波等线性滤波基础上发展起来的一种最佳滤波方法,具有较强的适应性和较优的滤波性能。这里将自适应滤波技术应用于电子对抗领域,利用自适应滤波原理计算出一个数字滤波器,对各信道的增益失配与相移失配进行精确的通道均衡补偿;利用自适应滤波方法设计具有特定频率响应的FIR滤波器,可实现时域宽带波束形成技术,并实现了基于自适应滤波的同平台干扰抵消技术。     

脉冲噪声环境中基于clipping方法的鲁棒LPFT及其重排算法

为了更好地处理脉冲噪声环境中的时变信号,本文提出了基于clipping方法的鲁棒局部多项式傅里叶变换(LPFT)及其重排算法。首先利用clipping方法对信号中掺杂的脉冲噪声进行抑制,得到较好的信号时频分布表示,然后将重排算法与该鲁棒LPFT相结合,以提高信号的时频聚集性。通过实验仿真可以看出,与基于中值滤波器的鲁棒LPFT相比,基于clipping方法的鲁棒LPFT同样能对被脉冲噪声干扰的信号给出较好的时频表示,而且其瞬时频率估计的最小均方误差(MSE)较低,计算量较小。并且,本文在基于clipping方法的鲁棒LPFT对掺杂脉冲噪声的信号进行处理的基础上,利用重排算法与其结合,有效增强了信号的时频聚集性。因此基于clipping方法的鲁棒LPFT及其重排算法是一种高效的处理脉冲噪声干扰信号及提高信号时频聚集性的方法。     

杂波图CFAR平面技术在均匀背景中的性能

典型的杂波图恒虚警检测技术常被用于时域平稳、空域变化较剧烈的杂波环境。它在每个杂波图单元处都形成一个独立的检测阈值,于是被称为杂波图ＣＦＡＲ点技术。而沈福民提出了一种杂波图ＣＦＡＲ平面技术的构想。这是一种在时空两维变化都比较平稳的杂波环境情况下尤为适用的杂波图ＣＦＡＲ检测技术,我们将其称为面技术。本文具体推导了这种技术在时空两维都均匀的背景中的检测性能表达式,并同杂波图点技术的性能进行较细致的分析     

邻域相关处理技术调试方法研究

介绍了邻域相关处理技术和由此设计的激光报警装置调试方法，邻域相关处理技术在光电二极管数量不变的情况下，可使激光报警分辨率提高一倍。应用这种技术研制了一台激光报警装置。该装置的调试方法对邻域相关处理技术的实现有重要作用，为此设计了相应的调试方法，应用这种方法进行调试，通过激光报警装置的原理性接收实验，证明激光报警装置的分辨率较原来提高了一倍，邻域相关处理技术是可行的，调试方法是适用的。     

适于硬件实现的降OFDM峰均比的分段压扩法

降低信号的峰均功率比(PAPR)是正交频分复用(OFDM)技术的一个关键问题。μ律压扩法作为降低PAPR的一个重要方法,其非线性的特点难于在硬件上实现。在传统的μ律压扩方法基础上,介绍了一种分段线性压扩方法,并对其效果进行仿真评估,并提出一种新的硬件实现方法,在降低复杂度上有良好的效果。     

基于FPGA的视频图像滤波分割方法及实现

在视频监控和视频会议应用领域中都会使用图像滤波、图像分割等技术。该文首先提出了一种改进型图像分割滤波方法及其特点,然后阐述了对多画面图像分割拼接采用该滤波方法的FPGA实现以及关键技术点,最后对该实现技术方案的优点进行总结和展望。     

光纤光栅透射谱线的测量

在已有光纤光栅调谐技术的基础上,研究了一种由不同光谱特性的光纤光栅组成的光栅对,用于测量光纤光栅谱线结构。并给出了测试结果。     

Numerical calculation of the losses in optical resonators

A hybrid technique utilizing the method of successive iterations in conjunction with a variational technique is used to calculate the losses in optical resonators. The method is described and the rate of convergence, accuracy, and saving in computer time are illustrated for a typical problem.     

A novel spread spectrum-based synchronization and locationdetermination method for wireless system

A new spread-spcetrum-based synchronization and geolocation method is presented. The synchronization method is based on determining the round-trip time between nodes. By using a spread-spectrum technique, delays of processing handshaking messages and switching transceivers from receiving mode to sending mode do not incur any inaccuracy. The geolocation method integrates our synchronization technique with the triangulation method, which is commonplace in geolocation systems. This new synchronization and geolocation method provides a cheap, efficient, and effective way to synchronize nodes and render location information in a wireless environment     

On the generation of random numbers from heavy-tailed distributions

A method is described for the generation of random numbers using a modification of the rejection technique, which is useful when the inverse of the underlying probability distribution function is inexpressable or is expensive to compute. However, the rejection technique can also be expensive if the underlying distribution has heavy tails. The method proposed reduces this expense by computing the random variate from a subinterval of the range space which is chosen randomly. The method is illustrated for a set of parameterized density functions. This technique has proven to be effective for investigating the robust smoothing properties of a class of nonlinear digital filters by Monte Carlo simulation     

Current-sensing technique for current-mode controlled voltage regulator modules

This paper introduces an innovative current-sense technique for voltage regulator modules (VRMs). The proposed method is applied to a multiphase buck converter although the converter topology does not affect the accuracy or effectiveness of the proposed technique. A RC network is parallel connected with the buck converter low-side MOSFET and the voltage signal across the sense capacitor reconstructs the inductor current waveform. The RC technique benefits from all the advantages of the most popular current-sensing technique, the inductor DC resistance current-sense method, cutting off its main disadvantage. The sense network design is oriented to obtain high immunity to noise and a great dynamic in current-mode control by properly selecting the sense signal slop during Ton and Toff time slots. A laboratory prototype of a multiphase buck converter with current-mode control implementing the proposed current-sense method is described and experimental results are shown.     

单周期控制开关电容DC-DC变换器

传统的开关电容DC-DC变换器通常采用PWM控制方法，以输出电压或者开关管的电流作为反馈信号来调节占空比，然而占空比信号的变化不能即时跟随输入电压或负载的变化，因而PWM控制方法的动态调节响应较慢。单周期控制方法是一种非线性控制技术，该技术利用开关变换器的非线性特点，对开关变量平均值实现即时的动态控制，只需在一个开关周期之内就能使开关变量平均值达到稳态，因而具有较快的响应速度。本文介绍了单周期控制方法的基本原理，并将该方法应用于一个恒定频率的升压(5V／12V)开关电容DC-DC变换器的控制．仿真结果轰明该方法是可行的。     

Accurate and time efficient estimation of the probability of error in bursty channels

A method and a technique for the probability of error estimation in digital channels with memory are developed and demonstrated. The expressions for the mean and variance of a random variable, representing a block of bits transmission in a bursty channel (channel with memory), are derived. The influence of the memory is expressed by a parameter called the memory factor. It is shown that the traditional Monte Carlo method can be applied for the probability of error estimation. In order to control the accuracy and increase the time efficiency of estimation this method is modified and a new method, called the modified Monte Carlo method, is proposed. Based on this modified method a technique of estimation with controlled accuracy is developed and demonstrated using data obtained by simulation. According to this technique the sample size is adjusted in the course of estimating procedure to give an accurate estimate of the probability of error for a minimum required time of estimation. Copyright © 2003 John Wiley & Sons, Ltd.     

一种提高WPAN吞吐量的冲突避免自适应跳频技术

本文提出了将冲突避免和自适应跳频技术(CAAFH,collision avoidance adaptive frequency selecting)应用于无线个域网(WPAN,Wireless Personal Area Network)系统以提高吞吐量的方案.文章首先给出了冲突避免自适应跳频技术方案构想,然后对冲突避免和自适应跳频技术应用于WPAN系统进行了理论分析.最后以IEEE802.15.1(Bluetooth)系统为例,对传统的方案和冲突避免自适应跳频技术方案的吞吐量进行了定量的数值计算.结果表明,在有限干扰的环境下,采用冲突避免自适应跳频技术方案可以有效的提高WPAN系统的吞吐量.本文结论也可推广到使用跳频技术的其它WPAN系统.     

Map image segmentation based on thresholding and fuzzy rules

A technique for map image segmentation is presented. By combining a thresholding method which is fast and easy to implement and fuzzy rules which can deal with uncertain or ambiguous data, the technique presented outperforms the commonly used adaptive thresholding method.<>