可编程序列脉冲检测器的设计

用一片ispLSll032设计了一种能检测任意序列的脉冲检测器。该检测电路能够准确地检测出规定序列的脉冲，适用于数字通信、雷达、遥测等领域精度高的数控系统。     

高精密航天器多余物检测算法研究

高精密航天器中内部活动多余物的存在是降低航天器可靠性的重要因素。针对现有多余物检测算法在较强环境噪声下难以有效检测出多余物信号脉冲并排除可动组件干扰的问题,提出了一种基于谱减法去噪、两级脉冲提取和脉冲发生序列周期性分析的高精密航天器多余物检测算法。利用谱减法实现对环境噪声的有效抑制;采用两级脉冲提取法对多余物信号与可动组件信号进行脉冲提取;通过对脉冲发生序列进行周期性分析,以周期信号相似度作为区分多余物信号和可动组件信号的判别依据,从而实现对多余物有无的检测。试验验证表明,该算法能有效检测航天器内多余物与可动组件的存在情况,识别准确率可达96%。     

红外热波脉冲位相法无损检测缺陷深度方法研究

针对目前缺陷深度定量无损检测的需求,利用脉冲式红外热波无损检测脉冲激励的特点,对平底洞试件进行脉冲式红外检测实验,在VC 中通过傅里叶变换处理得到位相热图序列,分析不同深度缺陷的盲频,进而得到缺陷深度.两种材料的深度校正曲线和误差表明,脉冲位相法为缺陷深度检测提供了有效手段.     

基于符号编码的雷达脉冲重复间隔调制识别

为了有效地实现在小数据脉冲样本和高脉冲丢失的环境下对雷达脉冲重复间隔(Pulse Repetition Interval,PRI)调制类型的准确识别,采用符号编码理论对雷达脉冲PRI序列进行符号化处理,对得到的编码序列进行修正以及特征码序列的选取、搜索和统计,最后依据相应的判决规则得到最终的识别结果。仿真实验表明,与传统的方法相比,采用的方法有效地克服了小数据脉冲样本和高脉冲丢失环境对雷达PRI序列的特征提取和调制类型的识别所带来的不利影响,为解决这一问题提供了一种新的思路。     

中国超宽带频率自适应检测避让技术研究

针对中国超宽带的4.2~4.8 GHz频段干扰抑制问题,采用组合高斯高阶导脉冲作为超宽带(UWB)原始脉冲,设计了直接序列扩频-载波调制算法,提出一种UWB频率自适应检测避让实现方案. 仿真结果表明,该方案满足中国UWB频率规划,保证了稳定的UWB正常发射功率,具有较高的传输效率,能够有效解决4.2~4.8 GHz频段检测避让(DAA)的问题.      

基于简化脉冲耦合神经网络的噪声人脸识别

利用简化脉冲耦合神经网络(S-PCNN),提出一种处理椒盐噪声污染的人脸识别新方法.首先采用S-PCNN的相似群神经元同步发放脉冲特性对原图像进行噪声检测,然后结合数学形态学实现对噪声点的消除,最后使用S-PCNN的时间序列(OTS)和欧氏距离进行人脸识别.通过计算机仿真实验表明所提算法是有效的.     

脉冲热源激励金属板材缺陷的红外热波检测

以含有盲孔缺陷的金属板材试件为研究对象,在闪光灯脉冲热源激励下对试件内部热流的传递过程进行了有限元仿真。在检测参数和分析参数给定条件下,利用脉冲红外热波检测系统测得试件表面最大对比度原始热图,应用FFT变换方法分析了原始热图序列的幅值图和相位图。结果表明,试件表面的最大温差越大,缺陷越容易检测,幅值图的信噪比较大而相位图的探测深度较深。该方法提高了脉冲红外热波检测技术的探测能力。     

互补码在电离层探测中的应用

电离层探测仪一般采用m序列或Barker码序列调制的二相编码脉冲。但是这两种码元序列产生的编码脉冲信号经脉冲压缩后都存在较高的旁瓣。为降低脉冲压缩后信号的旁瓣,提出了在多普勒频移较低的电离层区域应用互补码作为二相编码脉冲的调制码元序列。互补码具有非常好的自相关特性,A序列和B码序自相关后相加,自相关和只有主瓣,不存在任何旁瓣。但是由于A,B相位编码脉冲并不同时发射,多普勒频移会降低互补码的脉冲压缩性能。仿真结果表明,当多普勒频移较低时,互补码相位编码脉冲回波脉压性能优越;但是当多普勒频移较高时,多普勒频移给A,B相位编码脉冲回波带来很大的相位差,使互补码脉冲压缩后指标严重恶化。     

基于m序列的可控震源编码脉冲信号研究

地震勘探技术需要可控震源提供具有高度自相关函数的激发地震波, 为此, 提出了一种基于m序列调制脉冲信号实现可控震源信号的方法。首先使用Matlab产生m序列和脉冲信号, 通过m序列调制脉冲信号生成编码信号, 最终通过硬件电路系统实现了编码信号。实际测试中使用GEIST型地震仪进行数据采集后, 经Matlab自相关分析的结果表明, 地震子波信号主瓣突出, 旁瓣受到压制, 信噪比明显提高。     

一种基于扩时的直接序列扩频系统抗脉冲干扰方法

为了提高直接序列扩频系统在脉冲干扰条件下的误码性能,提出了一种基于扩时技术的抗脉冲干扰新方法.对基于扩时技术的直接序列扩频（DSSS）系统模型及其脉冲抑制能力进行了分析,并提出了一种抗脉冲性能优越的扩时码方案.仿真结果表明,在误码率要求为10^-6时,该方法和理想交织加纠错的方法相比,抗脉冲干扰能力提高了4 dB,并且不会降低信息传输速率,硬件实现容易.     

磁光盘原始误码特性的测试

介绍了测试磁光盘原始误码特性的基本原理,提出了特征误码脉冲宽度硬件判读和误码个数硬件统计方法,具体阐述了测试模块的设计思想．研制的测试模块兼有测试盘片漏码和突发码的功能,并可实现阈值电平、填充信号频率等参数的自动调节．     

智能化电度采集板的设计及与微机远动分站的通讯

设计了一种用于电力变电站的智能抄表装置 .该装置对变电站内所有电度表的输出脉冲进行计数 ,然后通过RS2 32接口传送给站内远动分站 ,并由远动分站上传主站 .该装置采集得到的电度数据准确、可靠     

Numerical modeling and analysis of the mechanism of a novel shock wave regulator for impact test

Based on the concept of hydraulic dissipation of kinetic energy, a novel shock wave regulator, which is composed of a damper and an extemally triggered valve, is presented with thorough analyses on its working mechanism. By establishing motion equations of each component of the regulator and simulating the dynamic behavior of the whole system, the shock wave regulator is demonstrated numerically to be able to change the width and amplitude of shock pulses. Prompt and easy adjustment can be achieved by changing the equivalent flow area of damping orifices and consequently the closing velocity of the flow area of a valve, which makes it applicable to different impact testing.     

PCC步进式水轮机调速器

提出了一种PCC步进式双调节水轮,机调速器，它直接产生正反转脉冲控制步进电机，用PLC内部高速计数器测频，在PLC调速器中实现性能测试功能，用高级语言开发实时多任务调控软件，具有PLC的高可靠性，C编程的灵活性和IPC的实时性。     

测量飞秒光参量产生器输出光脉冲脉宽的自相关仪的设计

设计出一台只用一块非线性晶体就能够测量宽波长范围的飞秒激光脉冲脉宽的单次脉冲自相关仪,适用于测量由光参量产生获得的可调谐飞秒激光脉冲的脉宽.     

Gamma暴光变曲线主峰特征参量的相关性分析

γ暴被认为由一系列脉冲所组成，其光变曲线中的峰对应看不同时刻网个相对论火球党层相互作用过程．光变曲线中的主峰对应着最强烈的作用过程，所受背景噪音的污染相对来说最小．因此光变曲线的主峰最适合于用以研究脉冲特性．本文对美国康普顿γ射线天文台观测卫星上BATSE仪器观测到的γ暴的光变曲线主峰数据进行统计分析，研究脉冲特征参量间的相关性．光变曲线的主峰按其形状分类，分为单峰结构峰和多峰结构峰．通过分析、比较两类峰特征的相关性发现：单峰结构的主峰其各种特征量的分布比多峰结构更为集中，这分明是由于多峰结构中存在着多个脉冲基元的随机叠加．因此，对于研究脉冲形态，采用单峰结构的主峰比采用多峰结构更为合理。     

Nanosecond radio bursts from strong plasma turbulence in the Crab pulsar

The Crab pulsar was discovered by the occasional exceptionally bright radio pulses it emits, subsequently dubbed 'giant' pulses. Only two other pulsars are known to emit giant pulses. There is no satisfactory explanation for the occurrence of giant pulses, nor is there a complete theory of the pulsar emission mechanism in general. Competing models for the radio emission mechanism can be distinguished by the temporal structure of their coherent emission. Here we report the discovery of isolated, highly polarized, two-nanosecond subpulses within the giant radio pulses from the Crab pulsar. The plasma structures responsible for these emissions must be smaller than one metre in size, making them by far the smallest objects ever detected and resolved outside the Solar System, and the brightest transient radio sources in the sky. Only one of the current models--the collapse of plasma-turbulent wave packets in the pulsar magnetosphere--can account for the nanopulses we observe.     

Direct observation of attosecond light bunching

Temporal probing of a number of fundamental dynamical processes requires intense pulses at femtosecond or even attosecond (1 as = 10(-18) s) timescales. A frequency 'comb' of extreme-ultraviolet odd harmonics can easily be generated in the interaction of subpicosecond laser pulses with rare gases: if the spectral components within this comb possess an appropriate phase relationship to one another, their Fourier synthesis results in an attosecond pulse train. Laser pulses spanning many optical cycles have been used for the production of such light bunching, but in the limit of few-cycle pulses the same process produces isolated attosecond bursts. If these bursts are intense enough to induce a nonlinear process in a target system, they can be used for subfemtosecond pump-probe studies of ultrafast processes. To date, all methods for the quantitative investigation of attosecond light localization and ultrafast dynamics rely on modelling of the cross-correlation process between the extreme-ultraviolet pulses and the fundamental laser field used in their generation. Here we report the direct determination of the temporal characteristics of pulses in the subfemtosecond regime, by measuring the second-order autocorrelation trace of a train of attosecond pulses. The method exhibits distinct capabilities for the characterization and utilization of attosecond pulses for a host of applications in attoscience.     

拉锥光纤与超连续谱的产生

目的研究超连续谱的形成与拉锥光纤及超短脉冲参数之间的关系。方法实验结果与理论分析相结合。结果在不同群速度色散和非线性光学效应的共同作用下,实验和理论上较为一致地得到不同程度展宽的超连续谱脉冲。结论拉锥光纤及超短脉冲参数对超连续谱宽度产生极大的影响。     

Direct observation of electron dynamics in the attosecond domain

Dynamical processes are commonly investigated using laser pump-probe experiments, with a pump pulse exciting the system of interest and a second probe pulse tracking its temporal evolution as a function of the delay between the pulses. Because the time resolution attainable in such experiments depends on the temporal definition of the laser pulses, pulse compression to 200 attoseconds (1 as = 10(-18) s) is a promising recent development. These ultrafast pulses have been fully characterized, and used to directly measure light waves and electronic relaxation in free atoms. But attosecond pulses can only be realized in the extreme ultraviolet and X-ray regime; in contrast, the optical laser pulses typically used for experiments on complex systems last several femtoseconds (1 fs = 10(-15) s). Here we monitor the dynamics of ultrafast electron transfer--a process important in photo- and electrochemistry and used in solid-state solar cells, molecular electronics and single-electron devices--on attosecond timescales using core-hole spectroscopy. We push the method, which uses the lifetime of a core electron hole as an internal reference clock for following dynamic processes, into the attosecond regime by focusing on short-lived holes with initial and final states in the same electronic shell. This allows us to show that electron transfer from an adsorbed sulphur atom to a ruthenium surface proceeds in about 320 as.