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1.
PREPARATION AND CHARACTERISTICS OF NEW TYPE NANOCOMPOSITE POWDER   总被引:4,自引:0,他引:4  
INTRODUCTIONTheauthor’spastresearchesshowedthatelectroless platedmetal ceramiccompositepow dercouldretardceramicgaingrowthduringthesinterprocess,evenlydispersethemetallicphaseontheceramicmatrixand ,therefore ,in creasethefracturestrength ,toughnessandwear…  相似文献   

2.
Buckling and multiple equilibrium states of viscoelastic rectangular plates   总被引:1,自引:0,他引:1  
1 Introduction Thedevelopmentofscienceandtechnologypromotestheapplicationsofviscoelasticstructures.Sinceanintegraltypeconstitutiverelationcanbeusedtosimulatethemechanicsbehaviorofaviscoelasticmaterialbetter,itiswidelyapplied.However,ifweapplyaninte…  相似文献   

3.
INTRODUCTIONCommunicativecompetence ,anotionprop osedbyHymes(1 972 )andothersasachallengetoChomsky s (1 965)conceptoflinguisticcom petence,hasnowbecomeaprimarytheoreticalconstructinsociolinguisticsandanumberofre lateddisciplines,especiallyforresearchingintothere…  相似文献   

4.
1 Introduction UltrafineparticlesofmagneticmaterialssuchasFe,Co,Niandtheiralloyshavethepotentialapplicationsinmagneticrecording,ferrofluids,medicaldiagnosticetc..Themagneticpropertiesoffineparticlesdiffermagnificentlyfromthoseoflargeparticles,andtherelat…  相似文献   

5.
Zirconiumalloyspossessingverylowabsorptionforthermalneutrons,goodcorrosionresistanceinhightemperaturewater ,andreasonablemechanicalprop ertiesareimportantmaterialsfornuclearindustry ,andhavebeenemployedasnuclearfuelcladdingandasstructurematerialsinlight…  相似文献   

6.
1 Introduction Theimagelosslesscompressioncodingisanimportantpartofthedigitalimagecompressionresearch .Medicalimages,satelliteimagesandseismicdatademandloss lesscoding .Thebasicideaofcompressionistoexploitthecorrelationstructurepresentedinmostreallifeim …  相似文献   

7.
INTRODUCTIONThequantumstateisanimportantconceptinquantummechanicsandotherrelatedfieldsin cludingquantumoptics,atomoptics,andthephysicsoftrappedparticles.Inrecentyears,peopledevotedmuchtimetoproducevariousquantumstates,andpaidmuchattentiontotheproblemofh…  相似文献   

8.
Colourwordsarewordsusedtodescribethecoloursofdifferentthings.Besidesindicatingtheirspecificcolours,suchasred ,yellow ,blackandwhite ,theyalsoreflectthedifferentculturalconnota tionsindifferentlanguages.Forexample,Chinesegirlslikewearingreddressesontheirwe…  相似文献   

9.
1 Introduction Itisknownthattheprotectionefficiencyofzincispartiallyasaresultofformingaprotectivefilmonabasemetal,suchassteel.Althoughpurezinccoatingprovidessomedegreeofprotectionforthesubstrate ,zincisconsumedrapidlyinaseverecorrosionenvi ronment.Conse…  相似文献   

10.
1 Introduction Inordertodetecttoxicgasleakageandtopreventspontaneouscombustionandexplosionofcombustiblegasesandorganicreagent,varioussortsofgassensorshavebeendeveloped,thedevicesthatwerespeciallyusedtodetecttraceoftoxicgasalsohavebeenresearched.Theb…  相似文献   

11.
提出了一种性能良好的图像水印算法,该算法在嵌入水印时先对水印信息进行奇偶编码再嵌入到图像中,在提取水印时对恢复出的水印信息进行奇偶解码,实验结果表明,该算法比未采用奇偶编码的同一水印算法具有更好的不可见性和稳健性。  相似文献   

12.
提出了在一种离散小波变换域内实现图像水印的方法。这种算法充分利用小波变换的特点,把原始图像及水印图像塔式分解,在多分辨率分解后的相同的频段来嵌入水印信息。该方法也利用了人眼视觉特性,算法简单而有效。实验证明,该算法较好地解决了水印不可见性与鲁棒性之间的矛盾,对常见的水印攻击都有较强的鲁棒性。  相似文献   

13.
陈宁  朱杰 《东南大学学报》2007,23(2):206-210
为了使数字水印实现多种功能,提出了一种能在同一音频信号中同时嵌入多个水印的新方法.首先,载体音频信号被分隔成指定长度的帧,并且所有成员水印被编码成一个混合水印.然后,利用回声隐藏技术将混合水印中的二进制比特嵌入到音频信号帧中.水印提取不需要原始音频信号.为了提高水印算法的提取正确率和抵御常规信号处理的鲁棒性,功率倒谱的自相关被用于检测携带水印的音频信号帧中的回声延时以提取出混合水印,并且相应的解码算法被用于分离成员水印.计算机仿真结果表明所提出的水印算法对常规的信号处理,如Mp3压缩、重采样、重量化、低通滤波以及白噪声具有很强的鲁棒性.  相似文献   

14.
Attribute reduction is necessary in decision making system. Selecting right attribute reduction method is more important. This paper studies the reduction effects of principal components analysis (PCA) and system reconstruction analysis , SRA) on coronary heart disease data. The data set contains 1723 records, and 71 attributes in each record. PCA and SRA are used to reduce attributes number (less than 71 ) in the data set. And then decision tree algorithms. C4.5, classification and regression tree ( CART), and chi-square automatic interaction detector ( CHAID ), are adopted to analyze the raw data and attribute reduced data. The parameters of decision tree algorithms, including internal node number, maximum tree depth, leaves number, and correction rate are analyzed. The result indicates that. PCA and SRA data can complete attribute reduction work. and the decision-making rate on the reduced data is quicker than that on the raw data: the reduction effect of PCA is better than that of SRA. while the attribute assertion of SRA is better than that of PCA. PCA and SRA methods exhibit good performance in selecting and reducing attributes.  相似文献   

15.
1 Introduction Watermarkisadigitalcodeembeddedimperceptiblyandrobustlyintothehostdataandtypicallycontainsinformationabouttheowner ,origin ,status ,and/ordestinationofthedata[1,2 ] .Inthemeantime ,varioustypesofattacksattemptingtoinvalidatetheembeddedwatermark…  相似文献   

16.
The eigenface method that uses principal component analysis (PCA) has been the standard and popular method used in face recognition. This paper presents a PCA - memetic algorithm (PCA-MA) approach for feature selection. PCA has been extended by MAs where the former was used for feature extraction/dimensionality reduction and the latter exploited for feature selection. Simulations were performed over ORL and YaleB face databases using Euclidean norm as the classifier. It was found that as far as the recognition rate is concerned, PCA-MA completely outperforms the eigenface method. We compared the performance of PCA extended with genetic algorithm (PCA-GA) with our proposed PCA-MA method. The results also clearly established the supremacy of the PCA-MA method over the PCA-GA method. We further extended linear discriminant analysis (LDA) and kernel principal component analysis (KPCA) approaches with the MA and observed significant improvement in recognition rate with fewer features. This paper also compares the performance of PCA-MA, LDA-MA and KPCA-MA approaches.  相似文献   

17.
利用小波变换多分辨率特性和人眼视觉特征,提出了一种新的彩色图像水印算法。算法先将不同强度的签名水印扩频到彩色图像不同色块的小波域,然后进行逆小波变换生成水印图像。为增强水印的鲁棒性,在添加水印之前对水印进行预处理。实验结果表明,该算法对常见的图像处理方法和压缩具有很强的鲁棒性。  相似文献   

18.
本文主要采用主分量分析方法和二次判别分析(QDA)有监督分类的方法来对基因芯片(微阵列)数据进行分析.PCA是一种提取海量的数据有效特征的有效方法.可以获得与原来基因芯片数据更为接近的成分的提取特征的效果.实验表明采用PCA方法事先对数据处理不可以提高基因芯片数据分析的准确性.得出结论可为工业应用提供科学依据.  相似文献   

19.
This article explores the concept and utility of digital watermarks. It takes a look at the techniques used to embed and detect a watermark on digital data.  相似文献   

20.
本文主要采用两种降维的方法和k-近邻法(KNN)有监督分类的方法来对基因芯片(微阵列)数据进行分析。PCA,PLS是一种提取海量的数据有效特征的有效方法,可以获得与原来基因芯片数据更为接近的成分的提取特征的效果。比较PCA降维方法和PLS降维方法对KNN统计判别分类的效果。  相似文献   

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