检索结果-南通市图书馆

在线全文

学校读者我要写书评

暂无评论

感知哈希综述

电子学报 2008年第7期36卷 1405-1411页

作者：牛夏牧焦玉华哈尔滨工业大学信息对抗技术研究所黑龙江哈尔滨150001

感知哈希(Perceptual Hashing),是多媒体数据集到感知摘要集的一类单向映射,即将具有相同感知内容的多媒体数字表示唯一地映射为一段数字摘要,并满足感知鲁棒性和安全性.感知哈希为多媒体内容识别、检索、认证等信息服务方式提供安全可... 详细信息

感知哈希(Perceptual Hashing),是多媒体数据集到感知摘要集的一类单向映射,即将具有相同感知内容的多媒体数字表示唯一地映射为一段数字摘要,并满足感知鲁棒性和安全性.感知哈希为多媒体内容识别、检索、认证等信息服务方式提供安全可靠的技术支撑.本文在人类感知模型(Human Perceptual Model)的基础上,明确了感知哈希的定义、性质和一般性描述.并对目前感知哈希的典型算法、应用模式以及评测基准等进行了综述,指出了感知哈希未来的研究方向.

关键词：感知哈希多媒体内容多媒体安全

Content-based facial image authentication via statistic features

在线全文

学校读者我要写书评

暂无评论

通讯和计算机（中英文版） 2009年第2期6卷 16-20页

作者： HAN Qi LI Qiong niu xia-mu School of Computer Science and Technology Harbin Institute of Technology Harbin l 50001 China

A statistic approach for facial image authentication is proposed. The typical model of digital signature generation and facial image authenticating is discussed firstly. Then the interesting region of facial image is extracted by a set of haar-like features. To prepare enough training samples, a sample enlarging method based power low transformation (PLT) is proposed. The statistic feature of a facial image is extracted by calculating the coefficients of it s projection onto a subspace trained offline by the enlarged sample set. The experimental results demonstrated the capability to distinguish the content-preserving operations and the malicious operations.

关键词：人脸图像图像识别计算机技术图像处理

Content-based facial image retrieval using common vector

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

通讯和计算机（中英文版） 2008年第9期5卷 5-11,50页

作者： WANG Zhi-fang SONG Chen niu xia-mu Christoph Busch Harbin Institute of Technology Harbin 150001 China NISlab Gjcvik University College Norway N-2802 Norway

Facial image retrieval is an essential application of content-based image retrieval. Based on the analysis of the practical application background, this paper proposes a new facial image retrieval scheme. In this scheme, the input query image is firstly transformed by four different methods to generate virtual samples and enlarge the training set. Moreover common vector method is applied to span the feature space for the training set whose images just belong to one class. To prove the feasibility of the scheme, a series of experiments are performed on the ORL face database.

关键词：面部形象图象处理矢量计算机技术

High-Order Two-Scale Asymptotic Paradigm for the Elastodynamic Homogenization of Periodic Composites

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Mechanica Solida Sinica 2024年第1期37卷 124-138页

作者： Wei-Zhi Luo mu He Liang xia Qi-Chang He State Key Laboratory of Intelligent Manufacturing Equipment and Technology Huazhong University of Science and TechnologyWuhan 430074China Laboratoire Modélisation et Simulation multi-Echelle MSME UMR 8208 CNRSUniversite Gustave Eiffel77454 Marne-la-ValléeFrance

The classical two-scale asymptotic paradigm provides macroscopic and microscopic analyses for the elastodynamic homogenization of periodic composites based on the spatial or/and temporal variable,which offers an approximate framework for the asymptotic homogenization analysis of the motion ***,in this framework,the growing complexity of the homogenization formulation gradually becomes an obstacle as the asymptotic order *** such a context,a compact,fast,and accurate asymptotic paradigm is *** work reviews the high-order spatial two-scale asymptotic paradigm with the effective displacement field representation and optimizes the implementation by symmetrizing the tensor to be ***,the modified implementation gets rid of the excessive memory consumption required for computing the high-order tensor,which is demonstrated by representative one-and two-dimensional *** numerical results show that(1)the contrast of the material parameters between media in composites directly affects the convergence rate of the asymptotic results for the homogenization of periodic composites,(2)the convergence error of the asymptotic results mainly comes from the truncation error of the modified asymptotic homogenized motion equation,and(3)the excessive norm of the normalized wavenumber vector in the two-dimensional inclusion case may lead to a non-convergence of the asymptotic results.

关键词： Composites Homogenization Asymptotic analysis Dynamics Dispersion

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

基于视觉阈值的结构相似度图像质量评价算法

深圳大学学报（理工版） 2010年第2期27卷 185-191页

作者：胡媛媛牛夏牧哈尔滨工业大学深圳研究生院深圳518055 深圳大学信息工程学院深圳518060

针对空间域结构相似度测量(image measure of structural similarity,SSIM)没有考虑人类视觉系统亮度掩蔽和对比度掩蔽对视觉感知的影响,提出基于人类视觉阈值理论的结构相似度图像质量评价算法(visibility threshold SSIM,VTSSIM).通... 详细信息

针对空间域结构相似度测量(image measure of structural similarity,SSIM)没有考虑人类视觉系统亮度掩蔽和对比度掩蔽对视觉感知的影响,提出基于人类视觉阈值理论的结构相似度图像质量评价算法(visibility threshold SSIM,VTSSIM).通过计算局部标准方差,将图像分为平坦区域、细节区域和一般区域;基于图像视觉阈值的临界可视误差分布,确定平坦区域中的亮度掩蔽极端区域和细节区域中的对比度掩蔽极端区域;分别对这两个极端区域及其他区域进行视觉阈值加权处理,得到整幅图像的质量评价.结果表明,VTSSIM比SSIM更符合人眼视觉特性,尤其适合评价失真较小的图像.

关键词：图像处理图像质量评价结构相似度测量人类视觉系统亮度掩蔽对比度掩蔽

Carbon fiber reinforced liquid crystalline elastomer composites:a dual exploration in strength augmentation and transformation flexibility through 4D printing

在线全文

学校读者我要写书评

暂无评论

International Journal of Smart and Nano Materials 2024年第2期15卷 312-329页

作者： Yuliang xia Tong mu Yanju Liu Jinsong Leng Centre for Composite Materials and Structures Harbin Institute of Technology(HIT)HarbinPeople's Republic of China Department of Astronautical Science and Mechanics Harbin Institute of Technology(HIT)HarbinPeople's Republic of China

Liquid Crystal Elastomers(LCEs)are renowned for their reversible deformation ***,enhancing their mechanical strength while retaining such flexibility has posed a considerable *** overcome this,we utilized 4D printing to develop an innovative composite of LCE with carbon fiber fabric(LCEC).This approach has notably increased the tensile strength of LCE by eightfold,all the while maintaining its exceptional capacity for reversible *** adjusting the alignment angle between carbon fiber and the LCE printing direction from 0°to 90°,the LCEC demonstrates an array of new deformation patterns,including bending,twisting,wrapping,and S-shaped transformations,which are distinct from pure LCE *** study unveils that LCE composites exhibit deformation processes markedly different from their pure material counterparts,with the ability of pure LCE to sustain tensile strains exceeding 1900%.These findings,previously undocumented and unexplored,represent a substantial contribution to the field of smart *** finite element analysis,we explored the carbon fiber and LcE matrix dynamics,revealing bending mechanics in *** combined experimental and simulation approach yields crucial insights for crafting durable,high-strength LCECs with diverse deformational properties,advancing smart material technology.

关键词： Liquid crystal elastomer composites 4D printing Smart materials

Heteroepitaxial growth of Au@Pd core–shell nanocrystals with intrinsic chiral surfaces for enantiomeric recognition

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Rare Metals 2024年第1期43卷 225-235页

作者： Feng-xia Wu Feng-Hua Li xia-Li Lv Qi-xian Zhang Guo-Bao Xu Wen-Xin niu State Key Laboratory of Electroanalytical Chemistry Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China Shaoxing Institute of Technology Shanghai UniversityShaoxing 312000China University of Science and Technology of China Hefei 230026China School of Materials Science and Engineering Shanghai UniversityShanghai 200436China Zhejiang Institute of Advanced Materials Shanghai UniversityJiashan 314113China University of Chinese Academy of Sciences Beijing 100039China

Noble metal surfaces with intrinsic chirality serve as an ideal candidate for investigating enantioselective chemistry due to their superior chemical durability and high catalytic ***,significant advance has been made in synthesizing metal nanocrystals with intrinsic ***,the majority reports are limited to ***,through a heteroepitaxial growth strategy,the synthesis of metal nanocrystals with intrinsic chirality to palladium was extended for the first time and their application in enantioselective recognition was *** heteroepitaxial growth strategy allows for transferring the chirality of homochiral Au nanocrystals to Au@Pd core–shell *** employing the chiral Au@Pd nanocrystals as enantiomeric recognizing elements,a series of electrochemical sensors for chiral discrimination were *** optimal conditions,the peak potential between D-dihydroxyphenylalanine(D-DOPA)and L-dihydroxyphenylalanine(L-DOPA)is about 80 m V,and the peak current of D-DOPA is 2 times as much as that of L-DOPA,which enables the determination of the enantiomeric excess(EE,%)of ***,this report not only introduces a heteroepitaxial growth strategy to synthesize metal nanocrystals with intrinsic chirality,but also demonstrates the superior capability of integrating intrinsic chirality and catalytic properties into metal nanocrystals for chiral recognition.

关键词： Core–shell nanostructures Chirality transfer Electrochemical sensors Chiral recognition Chiroplasmonics

在线全文

学校读者我要写书评

暂无评论

一种基于秘密共享的量子强盲签名协议

电子学报 2010年第3期38卷 720-724页

作者：温晓军田原牛夏牧哈尔滨工业大学信息对抗研究所黑龙江哈尔滨150001 中国科学院研究生院信息安全国家重点实验室北京100049 北京交通大学网络舆情安全研究中心北京100044

提出了一种基于秘密共享原理的量子强盲签名协议.每一组GHZ(Greenberger-Home-Zeilinger)中的三个光子依次分发给消息拥有者Alice、签名者Trent及验证者Bob,Alice测量自己的光子将消息盲化,Trent测量自己的光子对盲消息进行签名,而Bob... 详细信息

提出了一种基于秘密共享原理的量子强盲签名协议.每一组GHZ(Greenberger-Home-Zeilinger)中的三个光子依次分发给消息拥有者Alice、签名者Trent及验证者Bob,Alice测量自己的光子将消息盲化,Trent测量自己的光子对盲消息进行签名,而Bob根据手中光子的测量结果及量子态的关联性验证签名,但其行为受到量子指纹及审计程序的约束.本协议实现了签名的盲性以及消息拥有者无法被追踪,其安全性不受攻击者所拥有的计算资源的影响.

关键词：强盲签名秘密共享量子密码

Energy Efficiency Maximization in Mobile Edge Computing Networks via IRS assisted UAV Communications

在线全文

学校读者我要写书评

暂无评论

Computer Modeling in Engineering & Sciences 2024年第2期138卷 1865-1884页

作者： Ying Zhang Weiming niu Supu Xiu Guangchen mu School of Electronic Information Engineering Henan Institute of TechnologyXinxiang453003China Houde College Henan Institute of TechnologyXinxiang453003China Department of Science Henan Institute of TechnologyXinxiang453003China

In this paper,we investigate the energy efficiency maximization for mobile edge computing(MEC)in intelligent reflecting surface(IRS)assisted unmanned aerial vehicle(UAV)*** particular,UAVcan collect the computing tasks of the terrestrial users and transmit the results back to them after *** jointly optimize the users’transmitted beamforming and uploading ratios,the phase shift matrix of IRS,and the UAV trajectory to improve the energy *** formulated optimization problem is highly non-convex and difficult to be solved ***,we decompose the original problem into three *** first propose the successive convex approximation(SCA)based method to design the beamforming of the users and the phase shift matrix of IRS,and apply the Lagrange dual method to obtain a closed-form expression of the uploading *** the trajectory optimization,we propose a block coordinate descent(BCD)based method to obtain a local optimal ***,we propose the alternating optimization(AO)based overall algorithmand analyzed its complexity to be equivalent or lower than existing *** results show the superiority of the proposedmethod compared with existing schemes in energy efficiency.

关键词： Mobile edge computing(MEC) unmanned aerial vehicle(UAV) intelligent reflecting surface(IRS) energy efficiency