检索结果-南通市图书馆

A Cryptograph Domain Image Retrieval Method Based on Paillier Homomorphic Block Encryption

在线全文

学校读者我要写书评

暂无评论

Computers, Materials & Continua 2018年第5期55卷 285-295页

作者： Wenjia Xu shijun xiang Vasily Sachnev School of Information Science and Technology Jinan UniversityNo.601West Huangpu AvenueGuangzhou and 510632China Department of Information Communications and Electronic EngineeringThe Catholic University of KoreaSeoul and 02841South Korea

With the rapid development of information network,the computing resources and storage capacity of ordinary users cannot meet their needs of data *** emergence of cloud computing solves this problem but brings data security *** to manage and retrieve ciphertext data effectively becomes a challenging *** these problems,a new image retrieval method in ciphertext domain by block image encrypting based on Paillier homomophic cryptosystem is proposed in this *** can be described as follows:According to the Paillier encryption technology,the image owner encrypts the original image in blocks,obtains the image in ciphertext domain,then passes it to the third party *** server calculates the difference histogram of the image in ciphertext domain according to the public key and establishes the index *** user passes the retrieved image to the *** server computes the differential histogram of the retrieved image by public ***,compares the similarity of it with the histogram in index database and selects larger similarity images in ciphertext and send them to the *** user obtains the target image with the private *** experimental results show that the method is feasible and simple.

关键词： Paillier cryptosystem homomorphic encryption image retrieval feature extraction difference histogram

Fragile Audio Watermarking with Perfect Restoration Capacity Based on an Adapted Integer Transform

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Wuhan University Journal of Natural Sciences 2014年第6期19卷 497-504页

作者： LUO Xinrong xiang shijun School of Information Science and Technology Jinan University

We propose a novel audio watermarking scheme which can recover the original audio carrier perfectly if the watermarked audio is modified. Besides, we can adjust the maximum tampered rate allowed and the quality of watermarked audio flexibly as required. In the scheme, an efficient generalized integer transform is improved to embed watermark data which are composed of least significant bits（LSBs） of averages in each patch, reference-bits and check-bits. LSBs are needed in the inverse transform. Then, by comparing the extracted check-bits and calculated ones, the modified area can be localized. Finally, reliable reference-bits and samples data help us reconstruct the original audio without errors. The efficiency of the proposed method is theoretically and experimentally verified.

关键词： error-free restoration integer transform fragile audio watermarking

Modeling cavitation flow of cryogenic fluids with thermodynamic phase-change theory

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2013年第4期58卷 567-574页

作者： ZHANG XiaoBin WU Zhao xiang shijun QIU LiMin Institute of Refrigeration and Cryogenic Engineering Zhejiang University

Cavitation is the formation of vapor bubbles within a liquid where the flow dynamics causes the local static pressure to drop below the vapor pressure. The so-called full cavitation model (FCM) developed by Singhal has been widely used in numerical modeling of the cavitation flow for thermosensible and non-thermosensible fluids. Within the FCM, the bubble size is taken to be equivalent to the maximum possible value to forego the calculation of bubble number density. We developed a new cavitation model by recalculating the bubble radius in FCM to account for the effects of local pressure. The new model was obtained by combining the thermodynamic phase-change theory and the Young-Laplace equation with the assumption of thermodynamic equilibrium during the cavitation process. The cavitation calculations were performed based on the mathematical framework of the homogeneous equilibrium flow model and the transport-equation-based model for vapor phase mass fraction. The model was validated by modeling the cavitating flow of liquid nitrogen and liquid hydrogen through NASA hydrofoil and Ogive with consideration of the phase-change thermal effects. The temperature and pressure distributions with the new model are found to agree well with data from existing experimental studies, as well as the simulations with the FCM.

关键词：空化流动热力学理论相变理论低温液体建模热力学平衡空化模型气泡半径

Effects of surface tension on bubble growth in an extensive uniformly superheated liquid

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2011年第30期56卷 3191-3198页

作者： ZHANG XiaoBin xiang shijun CAO XiaoLi QIU LiMin Institute of Refrigeration and Cryogenics Zhejiang University Hangzhou 310027 China

The study of bubble growth in an extensive pool of liquid provides considerable insight into the mechanisms that play a role in bubble growth near a heated surface and in the cavitation phenomenon. This work focuses on analyzing the effects of surface tension on the growth rate for the thermally controlled stage of a single bubble in such a liquid. The conservation of energy equations, including the internal energy term for the bubble and that within boundary layer around it, are numerically solved. The complete temporal variations of the bubble in water and liquid nitrogen are investigated based on the assumption that the bubble growth is controlled only in sequence by inertia and heat. Thus, the two stages are subject to the continuity of the bubble growth, while the inertia-controlled stage is only formulated by the well-known Rayleigh solution. The thickness of the boundary layer around the bubble is also determined. The results are comparable with the Plesset-Zwick models and Forster-Zuber models, as well as available experimental data. It is found that the influence of internal energy on the rate of bubble growth is small enough to be ignored; however, the accumulative effects of the surface tension are significant and increase with a decrease in the degree of superheat.

关键词：表面张力气泡生长过热度液体均匀能量方程惯性控制泡沫层

Reversible Audio Watermarking Algorithm Using Non-Causal Prediction

在线全文

学校读者我要写书评

暂无评论

Wuhan University Journal of Natural Sciences 2013年第5期18卷 455-460页

作者： HUO Yongjin xiang shijun LIU Shangyi LUO Xinrong BAI Zhongliang School of Information Science and Technology Jinan University

Reversible watermarking technique enables to extract embedded information without any loss of the host signal. For the reduction of the embedding distortion, a desirable reversible watermarking approach should exploit efficient prediction way to generate prediction errors with a smaller magnitude for expansion embedding. In this paper, we present a reversible audio watermarking scheme based on a new non-causal prediction method and embedding strategy. The proposed non-causal prediction method provides non-integer prediction errors and the proposed expansion embedding strategy can proceed them for a lower embedding distortion. Experimental results have shown that the proposed reversible technique has a lower embedding distortion for the same embedding payload in comparison with the existing state-of-the-art works.

关键词： audio reversible watermarking non-causal prediction expansion embedding

在线全文

学校读者我要写书评

暂无评论

明文图像可逆信息隐藏综述

中国图象图形学报 2022年第1期27卷 111-124页

作者：欧博殷赵霞项世军湖南大学长沙410082 安徽大学合肥230601 暨南大学广州510632

图像可逆信息隐藏作为信息隐藏的重要分支,发展至今已近三十年,因其独有的图像无损恢复能力,一直备受医学、司法、军事等重点领域的青睐。然而现有可逆信息隐藏研究成果繁多,迁移知识广泛,本文简要梳理可逆信息隐藏的发展脉络,在回顾经... 详细信息

图像可逆信息隐藏作为信息隐藏的重要分支,发展至今已近三十年,因其独有的图像无损恢复能力,一直备受医学、司法、军事等重点领域的青睐。然而现有可逆信息隐藏研究成果繁多,迁移知识广泛,本文简要梳理可逆信息隐藏的发展脉络,在回顾经典算法的基础上,加以简化、注释,总结成功经验,展望潜在应用,以期为研究者提供一个按图索骥的探索路径。本文主要包括3个部分,分别为位图(Bitmap,BMP)图像的可逆信息隐藏(适用于空域嵌入操作)、JPEG(Joint Photographic Experts Group)图像的可逆信息隐藏(适用于频域和编码域嵌入操作)和鲁棒可逆水印(适用于扩展性研究)。通过近百篇高影响力文献的梳理可知,可逆研究的受众广泛、基础深厚,其严谨的数学定义和简明的机理论证是深受研究者推崇和坚持的重要原因。“干净、简明”的特点也是其能够与现实应用有效结合的强力抓手。增加可逆算法对于载体多样性的普适性研究,引入新的评价指标来导引算法与现实应用的融合,将是未来可开拓的方向。可逆信息隐藏技术能够恢复图像初始状态,其独特之处在于图像本身就是一个复杂语义的信息表达。这既要求可逆嵌入操作所施加的影响不能改变图像所表达的主要语义,又要求该操作是可消除的,保留溯源能力,将内容的信息表达权始终交由图像本身。这一特点不仅为敏感领域信息处理所亟需,也是其他常见领域并不排斥的。严格来说,一定程度上的复原本就是事物发展到一定阶段后的必然追求。据此,本文认为推广可逆研究与多学科融合解决更难、更广泛的问题,实现长远发展,是完全必要且可行的。

关键词：可逆信息隐藏综述空域可逆嵌入频域可逆嵌入鲁样可逆

在线全文

学校读者我要写书评

暂无评论

利用可逆网络的音频藏图算法

西安电子科技大学学报 2024年第4期51卷 226-238页

作者：张晓虹项世军黄红斌暨南大学信息科学技术学院广东广州510632

可逆网络因其具有天然可逆的结构,非常适用于信息隐藏领域。图像能以生动直观、有层次的方式传递信息,而音频是一种广泛传播和使用的媒体文件,具有较大的嵌入容量,因此在音频中隐藏图像具有较高的研究和应用价值。在音频藏图任务中,如... 详细信息

可逆网络因其具有天然可逆的结构,非常适用于信息隐藏领域。图像能以生动直观、有层次的方式传递信息,而音频是一种广泛传播和使用的媒体文件,具有较大的嵌入容量,因此在音频中隐藏图像具有较高的研究和应用价值。在音频藏图任务中,如何表征音频和图像数据以及如何在减少音频失真的同时提高重建图像的质量是两个重要的问题。针对这两个问题,提出了一种基于可逆网络的音频藏图算法。对于数据特征表示,受到JPEG图像压缩中数据处理方法的启发,提出了图像特征提取与表示模块,该模块对彩色图像依次进行分块离散余弦变换、锯齿扫描和高低频分离操作,提取出图像的频域特征并得到其一维表示。此外,为了减少音频失真并提高重建图像的质量,利用小波变换分离音频的高低频分量并引入可逆网络将秘密图像嵌入到载体音频的高频区域中。实验结果表明,所提出的算法在实现高嵌入率的同时,能生成质量更高的隐写音频以及重建出更加还原的彩色图像,且算法具有较高的安全性。

关键词：隐写图像隐藏可逆网络小波变换离散余弦变换

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

加密域可逆水印综述

暨南大学学报（自然科学与医学版） 2013年第5期34卷 548-555页

作者：项世军刘尚翼暨南大学信息科学技术学院中国广州510632

加密技术和可逆水印是保护多媒体信息安全的两种重要手段.加密技术将多媒体明文转变成不可理解的密文,对多媒体数据的内容进行保护.可逆水印作为另外一种信息安全手段,能从发送端到接收端密切监视多媒体数据的传播与内容篡改,不仅能对... 详细信息

加密技术和可逆水印是保护多媒体信息安全的两种重要手段.加密技术将多媒体明文转变成不可理解的密文,对多媒体数据的内容进行保护.可逆水印作为另外一种信息安全手段,能从发送端到接收端密切监视多媒体数据的传播与内容篡改,不仅能对多媒体数据的版权进行保护,还能对其完整性进行认证和失真修复等.加密技术与可逆水印具有不同的功能,通过结合起来可以构建更为安全可靠的数字版权系统.近年来,在加密域设计可逆水印成为了多媒体信息安全研究中的一个新的分支,已经引起了科研工作者的极大重视.本研究对加密域可逆水印的研究背景、应用领域、已经提出的相关算法进行了简要的阐述,并在此基础上指出了其存在的不足以及未来的研究前景.

关键词：加密可逆水印数字版权多媒体

在线全文

学校读者我要写书评

暂无评论

用VOF方法数值计算液滴燃烧

化工学报 2011年第3期62卷 692-698页

作者：张小斌项世军曹潇丽张学军浙江大学制冷与低温研究所浙江杭州310027

引言液体燃料通过喷射进入内燃机的汽缸或喷气发动机的透平中燃烧产生热能。近年来能源危机加剧及减排CO2以保护环境意识提高,促使研究者们采用新的技术提高化石燃料的燃烧效率,其中对单个液滴燃烧物理过程的深刻了解是改进喷射燃烧为... 详细信息

引言液体燃料通过喷射进入内燃机的汽缸或喷气发动机的透平中燃烧产生热能。近年来能源危机加剧及减排CO2以保护环境意识提高,促使研究者们采用新的技术提高化石燃料的燃烧效率,其中对单个液滴燃烧物理过程的深刻了解是改进喷射燃烧为特征的内燃机械能量利用效率的基本。对液滴燃烧过程的数值及实验研究已经有几十年。

关键词：液滴燃烧两相传质数值模拟 VOF