首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 125 毫秒
1.
1.IntroductionSqueezedstates0fradiati0nficlds[1avebeenstudicdc0nsiderablyinrecentyears.Besidesthen0rma1lsqueezing,itisals0possibletodefinehigl1pr-ordersqueezings.HongandMan-de1[1Jdefinedthe'2Nth-ordersqueezing,andHillery[2]intr0ducedtheamp1itudesquared.squeezing.Morerecently,Zhangclal.[3JsuggcstedtheamplitudeNth-p0wersqueezingwhichincludosthenorma1squeezingandtheamplitude-squaredsqueezingassPecialcases.Allthese:higher-ordersqueezingshavebeensho`\)ntobeindependentnonclassica1features0f.radi…  相似文献   

2.
1.IntroductionRecently,thcrehasbecnintcrcstinthephot0resp0nse0fhigh-7'.oxidcsuperconductingfilms,espcciallywithregardtdthedctailsofthephysics0ftheph0toresponse['~'J.Fr0mtheviewpointoftheapplicationinthesuperconductingclectr0nics,thecharacteristicsofphotore-sponcse0fJosephsonjuncti0nfabricated\viththcsehigh-T.0xidcsupercondictorsandthepho-toinducedn0ncquilibriumproPerties0fthesematerialsmustbecxaminedandeva1uatcdforthedeve1opmcntofnQveIsL1pcrc0n(luctingdcviccsandJ0scphsoncbnjuncti0n.Itisf0un…  相似文献   

3.
1Intr0duCtionItisarathertroubesomproblemtoreceiveweakandnarrowband0Pticalsignal0nthebackgudn0se.Becausethenose0fbackgrOUnbringsaboUtgreatdisturbance,itiscriticaltoenhanethereceivingtwnoiserati0anddecreasethepeakvaluepowrreqchemntfOrlaserbotterinthesystem.ThinterferenceoPticalfilterisnocometenforthiswor.Typicallyat0ndcresonancefi1ter(ARF)[']isusedtoobtainultranarrowbandoPticalfi1tering,achievingpaSSbandofaPProkimate1y1Gth.An0terdevicetheFaradaydispersdrioPticalfilt..["'1,hasbeenusedt0at…  相似文献   

4.
Reccntly,thec]9ctrol13:lgrlcticProPcl'ticsinn0nIinearpcriodicstructurchavebcenexten-sively8tudiedW.ChenandD.L.A/[illsdeIn0nstratedthecxisting0fs0-cal1cdgaps0litoninnon1inearpcri0dicstructure[1J,thcsegapsolit0nsarespatiaIs0lit0ns.'Latterstudiesshowedthatthegaps0litonis0nlyakind0fspecialcflsc0fBraggs0Iiton\\'hichcanm0vewithanyve-locitybelox\'t[1egroLlpvcI0city[2,3j.Thcse.solit0nscxistinthcresonantcase,i-e-,thestr0ngcouplingbctxvcentt1cfor\\':lI'<1112odcanLIthcback\\'ardm0dc.Inthiscasc,the…  相似文献   

5.
SupportedbytheNationalNaturalScienceFoundationofChina.1.IntrodtlctionInourprcviOLISbaper[1J,x\'ehavcstLldicdthepropagati0n0ff1attencdHermite}Gaussbeams(FGHlls)infreespace,bytakingthcmasc0hercntsuperimpositi0nofHermite-Gaussbcamsofevcndrder.Inpracticaluse,suchbcamsareusualIyf0cuscdbyalens.'Sincetrans-formation0fhighordcrHermite-Gaussbcamsbythin]enscanbestudicdana1yticalIy,wecandcscribetheficlddistributions0fFGHllsafterathinlensalongpropagati0naxikexp1icitly,andwriteouttheirbeamspotsiz…  相似文献   

6.
1.IntroductionLasersystemshavebccnkno`"ntounderg0stabiIitychangesunderccrtainconditi0ns.Inthesingle-m0de1asers,forexampIc,thereisasecondthresh0Idvalueabovewhichafurtherinstability,namely,sclf-pulsing,sctsin[1'2J.H0\\'cver,inthccaseof0nc-ph0tonlasersoftheclassB,n0self-pulsinginstabilityoccursf0rthefrcc-runningandatresonance.Instabili-tiesin'tx"o-ph0t0nlasersystc112shavcals0bceninvcstigatcdthe0rctically.Inrecentyears,two-phQtonlaser0scillationhasbccnobscrvedinaFabry-Per0tcavityfil1edx"ithrub…  相似文献   

7.
傅里叶变换红外光谱固体制样技术   总被引:2,自引:1,他引:1  
通过对溴化钾与纳米固体超强酸样品的比例进行了探讨 ,得出制样时溴化钾与样品比例范围为1∶ 0 .0 0 1— 1∶ 0 .0 2 9,其最佳比例范围为 1∶ 0 .0 0 98— 1∶ 0 .0 1 5 ,并且应用于其他固体样品的测定 ,结果基本一致。同时得出 ,固体样品的最少检测量为 2 .0× 1 0 -5g  相似文献   

8.
I.IntroductionThetemperature,salinityandstaticprcssureofscawaterchangewithdepth,whichformsthcsoundvelocityvertica1distributioninthesea.Duringsummcrscason,thercaren0n-uniformthermoclinelaycrsinthedepths0fshallowseaal0ngChinacoast.Wearenowabletodeducctheimpedanccproflle(pc)byechoesofacousticwavesfr0mvarioustherm0c1ine1ayers.Thewaterdcnsityvaricsonlyslight1y,hencetheac0usticve1ocityde-Pendsmainlyonthetemperatureofseawatcr,andthercfore,itispossiblctorecordthcdepthofthermoclinelaycrsbyusingacoust…  相似文献   

9.
1IntroductionC1ustersareanimportantstate0fmatter.One0fthebasicg0alsofcfusterstudiesistogainaninSghtintothevariahonofthestructuresandthepY0PertiesofclusterswithitSsize.Inthepastdecade,avarietyofexPerimentaltecndqugyhavebeendeveloPedtoproduceandanalyzecarboclusters.Them0bilityisameasureofhowraPidlyandrimovesthIQUghabuffergasundertheinfluenceofanelectricfi.ld['].Foragivenc1ustersizeacomPactthree-dimensdrialclusteri0nwillhavealargerm0bilitythanalesscomactge0metry,Injectedionsdrifttubetechniq…  相似文献   

10.
1.IntrodLIctionOx`ingtoarcfraGtiveincIexoflessthanunityatinfrarcdwaveIength(n.r1)andasmallextinctioncocficicnt(k)thatiscIcIlaandcdfortotalintcrnaI1.efe1ction,thecicularhollowfibcrofGe02a9)SiO2b:lschas\vidclybccnLlsedtotransmittheC02lasercnergy-However,in0rdertohavcastab1coutPtlt,itisreqL1cstedtofindoutthctransmittingcharacteristicforthiskind0f0pticalfibcrs.Obvi0LISly,thccnergylossisoneofthcimportantparametcrsanditdependsn0t0n1yonthc1nodcsofthcopcrativc0pticalx"ave,butalsoonthercflcctive…  相似文献   

11.
李凯彦  赵兴群  孙小菡  万遂人 《物理学报》2015,64(5):54304-054304
相位光时域反射链路监测系统是一种利用光纤作为传感介质的传感系统, 能够监测、定位、识别入侵信号.模式识别模块是其重要组成部分, 实时智能区分安全扰动和危险入侵.本文提出一种用于光纤链路振动信号模式识别的复合特征提取方法.利用改进的双门限方法确定有效信号段的起止位置, 结合最大能量与最高信噪比挑选出采样周期内主要入侵扰动的特征段.综合利用特征段时域持续时间和小波包能量谱提取复合特征向量, 使用支持向量机进行模式识别.实验表明, 基于本文提出的规整化特征提取方法的模式识别准确率有了显著提高.  相似文献   

12.
董玉龙  姜威 《光学技术》2012,38(5):579-582
提出一种基于提升小波和Fisher线性判别法(FLD)相结合的人脸表情特征提取方法。提升小波是完全基于时空域的变换,具有多分辨率的特征,更有利于表情细节信息的提取,并且运算时间短,便于实现。图像经过提升小波变换后,取其低频分量和高频分量相结合作为整体特征,实验证明保存了绝大部分的表情分量,然后用Fisher线性判别法(FLD)进行特征提取,采用K-近邻法进行分类。在JAFFE数据库中,分辨率达到94.3%,识别时间为2.9s,证明了方法的有效性。  相似文献   

13.
褚钰  李田港  叶硕  叶光明 《应用声学》2020,39(2):223-230
为了解决传统卷积神经网络在识别中文语音时预测错误率较高、泛化性能弱的问题,首先以深度卷积神经网络(DCNN)-连接时序分类(CTC)为研究对象,深入分析了不同卷积层、池化层以及全连接层的组合对其性能的影响;其次,在上述模型的基础上,提出了多路卷积神经网络(MCNN)-连接时序分类(CTC),并联合SENet提出了深度SE-MCNN-CTC声学模型,该模型融合了MCNN与SENet的优势,既能加强卷积神经网络的深层信息的传递、避免梯度问题,又可以对提取的特征图进行自适应重标定。最终实验结果表明:SE-MCNN-CTC相较于DCNN-CTC错误率相对降低13.51%,模型最终的错误率达22.21%;算法改进后的声学模型可以有效地提升泛化性能。  相似文献   

14.
Face recognition is an important research hotspot. More and more new methods have been proposed in recent years. In this paper, we propose a novel face recognition method which is based on PCA and logistic regression. PCA is one of the most important methods in pattern recognition. Therefore, in our method, PCA is used to extract feature and reduce the dimensions of process data. Afterwards, we present a novel classification algorithm and use logistic regression as the classifier for face recognition. The experimental results on two different face databases are presented to illustrate the efficacy of our proposed method.  相似文献   

15.
针对复杂情况下海上舰船目标单波段特征识别能力不足的问题,研究可见光、中波红外和长波红外三波段特征图像融合技术,重点解决图像融合方法中存在的算法耗时和融合策略选择的问题,提出了一种新的基于区域协方差矩阵的多波段特征级融合方法,针对可见光图像和红外图像分别设计11维和5维特征向量,协方差矩阵可以将多个特征进行融合,既保证了不同目标之间的区别性,同时又减小计算量。该方法首先利用显著性检测,快速定位图像中的目标区域,然后,针对不同波段图像设计的特征向量定义协方差阵的距离计算公式并进行匹配,通过对图像的一次遍历操作获得积分图像,在协方差计算时达到快速计算的目的,最后利用k-阶最近邻算法对多种舰船目标进行分类识别。利用实拍的3 400余张三波段舰船目标图像作为测试数据。实验主要分为两部分,首先对比单波段和三波段融合识别的识别率,验证所提出的融合方法具有更广的应用范围;然后,在计算效率上对比多种传统的像素级方法,验证采用的特征级融合在计算时间上的优势。实验结果表明,该方法可达到95.1%的识别率,单帧计算耗时约为0.5s,在实时性和检测率方面都有明显提高。  相似文献   

16.
尺度不变特征与几何特征融合的人耳识别方法   总被引:3,自引:1,他引:2  
田莹  苑玮琦 《光学学报》2008,28(8):1485-1491
要提高人耳的识别率,关键是特征的提取与表达.尺度不变特征变换(SIFT)技术是局部点特征提取算法,在尺度空间寻找极值点,提取对图像的尺度和旋转变化具有不变性,对光照变化和图像变形具有较强的适应性的特征向量.尝试用SIFT技术来提取外耳图像的结构特征点以形成稳定的特征描述子,为了克服一幅图像中有多个局部描述子相似的问题,在SIFT特征描述子中融入一个耳廓几何特征.最后采用特征向量的欧氏距离作为两幅图像相似性度量标准进行人耳识别.在耳图像库七进行实验.结果表明,该方法不仅可以有效地提取人耳特征,通过少量特征可获得较高的识别率,而且对耳图像刚体变化具有较强的稳健性.  相似文献   

17.
In this paper, we propose a palmprint recognition method based on the representation in the feature space. The proposed method seeks to represent the test sample as a linear combination of all the training samples in the feature space and then exploits the obtained linear combination to perform palmprint recognition. We can implement the mapping from the original space to the feature space by using the kernel functions such as radial basis function (RBF). In this method, the selection of the parameter of the kernel function is important. We propose an automatic algorithm for selecting the parameter. The basic idea of the algorithm is to optimize the feature space such that the samples from the same class are well clustered while the samples from different classes are pushed far away. The proposed criterion measures the goodness of a feature space, and the optimal kernel parameter is obtained by minimizing this criterion. Experimental results on multispectral palmprint database show that the proposed method is more effective than 2DPCA, 2DLDA, AANNC, CRC_RLS, nearest neighbor method (NN) and competitive coding method in terms of the correct recognition rate.  相似文献   

18.
Automatic detection and classification of short and nonstationary events in noisy signals is widely considered to be a difficult task for traditional frequency domain and even time–frequency domain approaches. A novel method for audio signal classification is introduced. It is based on statistical properties of the temporal fine structure of audio events. Artificially generated random signals and unvoiced stop consonants of speech are used to evaluate the method. The results show improved recognition accuracy in comparison to traditional approaches.  相似文献   

19.
基于Gabor小波纹理特征的目标识别新方法   总被引:7,自引:2,他引:5  
张敏  许廷发 《物理实验》2004,24(4):12-15
给出了一种基于Gabor小波纹理特征的目标识别新方法.主要是利用Gabor小波设计了一种多通道小波滤波器。对图像目标直接进行小波变换,用Gabor小波变换系数的模的平均值和其标准方差来表示抽取的图像目标的特征,把获得的小波特征归一化后输入到改进的BP神经网络分类器进行分类识别.最后。进行了一系列的仿真实验,结果表明,这种特征提取方法能有效提取图像目标纹理特征,并且对噪音和形状的变化具有鲁棒性.在应用于目标识别时,神经网络的训练时间减少到lOmin,识别率达到94%.  相似文献   

20.
According to the essential characters of the image topology, a new hand vein recognition algorithm based on the connection lines of reference point and feature points is proposed. In this method, the intersection points and the endpoints of the vein image are used as feature points. After the intersection points and the endpoints selected as feature points, the reference point for image matching are extracted from these points. The relative distances between the reference point and the feature points and the angles between the adjacent connections of the reference point and feature points are calculated and used as recognition features. Finally these two features are combined for hand vein recognition. This method can effectively overcome the influence on the recognition results caused by image translation and rotation. Experimental results show that the proposed algorithm is able to achieve hand vein recognition reliably and quickly.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号