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基于AutoCAD的上海市地形图管理系统设计
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作者 王龙浩 《工程技术研究》 2023年第4期190-192,共3页
地形图通常以分幅的dwg格式存储,使用时需根据工程项目范围找出对应的若干张地形图并拼接成一块整图。如果工程范围较大或需要查找指定年份的历史地形图,查图和拼图的效率较低。因此,文章结合地形图分幅及编号规则分析,设计了一套基于Au... 地形图通常以分幅的dwg格式存储,使用时需根据工程项目范围找出对应的若干张地形图并拼接成一块整图。如果工程范围较大或需要查找指定年份的历史地形图,查图和拼图的效率较低。因此,文章结合地形图分幅及编号规则分析,设计了一套基于AutoCAD的上海市地形图管理系统,系统借助AutoCAD ObjectArx.NET二次开发技术,可在AutoCAD软件中自动插入指定位置的地形图,具有多种调图功能,支持路网及接图表的叠加,以及插入指定年份或最新地形图,有效地提高了地形图查图和拼图的工作效率。 展开更多
关键词 Auto CAD Object Arx.NET 地形 调图算法
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Accelerating SAGE algorithm in PET image reconstruction by rescaled block-iterative method 被引量:1
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作者 朱宏擎 舒华忠 +1 位作者 周健 罗立民 《Journal of Southeast University(English Edition)》 EI CAS 2005年第2期207-210,共4页
A new method to accelerate the convergent rate of the space-alternatinggeneralized expectation-maximization (SAGE) algorithm is proposed. The new rescaled block-iterativeSAGE (RBI-SAGE) algorithm combines the RBI algo... A new method to accelerate the convergent rate of the space-alternatinggeneralized expectation-maximization (SAGE) algorithm is proposed. The new rescaled block-iterativeSAGE (RBI-SAGE) algorithm combines the RBI algorithm with the SAGE algorithm for PET imagereconstruction. In the new approach, the projection data is partitioned into disjoint blocks; eachiteration step involves only one of these blocks. SAGE updates the parameters sequentially in eachblock. In experiments, the RBI-SAGE algorithm and classical SAGE algorithm are compared in theapplication on positron emission tomography (PET) image reconstruction. Simulation results show thatRBI-SAGE has better performance than SAGE in both convergence and image quality. 展开更多
关键词 positron emission tomography space-alternating generalizedexpectation-maximization image reconstruction rescaled block-iterative maximum likelihood
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QIM digital watermarkingbased on LDPC code and messagepassingunder scalingattacks
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作者 崔鑫 颜斌 +1 位作者 贾霞 王亚菲 《Journal of Measurement Science and Instrumentation》 CAS 2014年第1期37-40,共4页
Watermarking system based on quantization index modulation (QIM) is increasingly popular in high payload applications,but it is inherently fragile against amplitude scaling attacks.In order to resist desynchronizati... Watermarking system based on quantization index modulation (QIM) is increasingly popular in high payload applications,but it is inherently fragile against amplitude scaling attacks.In order to resist desynchronization attacks of QIM digital watermarking,a low density parity check (LDPC) code-aided QIM watermarking algorithm is proposed,and the performance of QIM watermarking system can be improved by incorporating LDPC code with message passing estimation/detection framework.Using the theory of iterative estimation and decoding,the watermark signal is decoded by the proposed algorithm through iterative estimation of amplitude scaling parameters and decoding of watermark.The performance of the proposed algorithm is closer to the dirty paper Shannon limit than that of repetition code aided algorithm when the algorithm is attacked by the additive white Gaussian noise.For constant amplitude scaling attacks,the proposed algorithm can obtain the accurate estimation of amplitude scaling parameters.The simulation result shows that the algorithm can obtain similar performance compared to the algorithm without desynchronization. 展开更多
关键词 digital watermarking quantization index modulation (QIM) message passing algorithm based on factor graph low density parity check (LDPC) code amplitude scaling attack
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A Heuristic Approach to Fast NOVCA (Near Optimal Vertex Cover Algorithm)
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作者 Sanj aya Gajurel Roger Bielefeld 《Computer Technology and Application》 2014年第2期83-90,共8页
This paper describes an extremely fast polynomial time algorithm, the NOVCA (Near Optimal Vertex Cover Algorithm) that produces an optimal or near optimal vertex cover for any known undirected graph G (V, E). NOVC... This paper describes an extremely fast polynomial time algorithm, the NOVCA (Near Optimal Vertex Cover Algorithm) that produces an optimal or near optimal vertex cover for any known undirected graph G (V, E). NOVCA is based on the idea of(l) including the vertex having maximum degree in the vertex cover and (2) rendering the degree of a vertex to zero by including all its adjacent vertices. The three versions of algorithm, NOVCA-I, NOVCA-II, and NOVCA-random, have been developed. The results identifying bounds on the size of the minimum vertex cover as well as polynomial complexity of algorithm are given with experimental verification. Future research efforts will be directed at tuning the algorithm and providing proof for better approximation ratio with NOVCA compared to any available vertex cover algorithms. 展开更多
关键词 Vertex cover problem combinatorial problem NP-complete problem approximation algorithm OPTIMIZATION algorithms.
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Research on General Permutation Encryption Module Based on Chaos Theory
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作者 Sun Wenjie 《International Journal of Technology Management》 2014年第7期58-61,共4页
Replacement and substitution encryption are two basic types of encryption historically. The classical encryption algorithm has been compromised now, but they still can play special role for modem cryptnlogy. For examp... Replacement and substitution encryption are two basic types of encryption historically. The classical encryption algorithm has been compromised now, but they still can play special role for modem cryptnlogy. For example, in digital image encryption system, substitution can disrupt the original order of the images and eliminate the correlation of image information which not only can realize security of images, but also can resist intentional attack and destruction of clipping and noise. And transposition transformation is introduced into the design of block ciphers. The substitution has the feature of high efficiency and resistance, which makes it meet the specific requirements of encryption. So substitution cypher can be applied to modern encryption system. 展开更多
关键词 chaos theory general substitution encryption.
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A color image tracking method based on target characteristic hue decision
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作者 Xu Yiming Liu Xiaoli Liu Yixin 《Engineering Sciences》 EI 2010年第4期70-73,共4页
Conventional correlation matching algorithms waste great time in invalid area search. This paper proposes a color tracking method based on correlation search area optimization on target characteristic hue decision. By... Conventional correlation matching algorithms waste great time in invalid area search. This paper proposes a color tracking method based on correlation search area optimization on target characteristic hue decision. By quantifying and reducing dimensions of HSV( hue saturation value) color space, a one-dimensional hue space is constructed. In the space, the target characteristic hue granule set is constructed, which contains attributes such as value, area and average distance between pixels and aiming center. By using granular computing method, the similarity between target and search blocks is obtained and the invalid search areas can be removed. The color tracking experiment has proved that the algorithm can improve real time performance for conventional matching algorithms without precision lost. 展开更多
关键词 color image tracking correlation matching characteristic hue granular computing
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AN ADAPTIVE DIGITAL IMAGE WATERMARK ALGORITHM BASED ON GRAY-SCALE MORPHOLOGY 被引量:2
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作者 Tong Ming Hu Jia Ji Hongbing 《Journal of Electronics(China)》 2009年第3期417-422,共6页
An adaptive digital image watermark algorithm with strong robustness based on gray-scale morphology is proposed in this paper.The embedded strategies include:The algorithm seeks and extracts adaptively the image stron... An adaptive digital image watermark algorithm with strong robustness based on gray-scale morphology is proposed in this paper.The embedded strategies include:The algorithm seeks and extracts adaptively the image strong texture regions.The algorithm maps the image strong texture region to the wavelet tree structures, and embeds adaptively watermark into the wavelet coefficients corresponding to the image's strong texture regions.According to the visual masking features, the algorithm adjusts adaptively the watermark-embedding intensity.Experimental results show the algorithm is robust to compression, filtering, noise as well as strong shear attacks.The algorithm is blind watermark scheme.The image strong texture region extraction method based on morphology in this algorithm is simple and effective and adaptive to various images. 展开更多
关键词 Gray-scale morphology Strong texture region Adaptive control Image watermark
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Evolution of downsized crescent-shaped dune in wind tunnel experiment 被引量:1
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作者 ZHANG Yang WANG Yuan JIA Pan 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS 2014年第1期143-151,共9页
The migration of a downsized crescent-shaped dune was investigated in a wind tunnel experiment.Quantified upwind influx and vertical oscillation of the sand bed were introduced to modulate the saturation level of the ... The migration of a downsized crescent-shaped dune was investigated in a wind tunnel experiment.Quantified upwind influx and vertical oscillation of the sand bed were introduced to modulate the saturation level of the sand flux above the dune surface to affect dune evolution.The evolution was recorded by top-view photography and then abstracted as the evolution of self-defined characteristic quantities using a digital image processing algorithm.The results showed that,in contrast to the case for spanwise quantities,the evolution of streamwise quantities corresponds to a linear increase in the modulation magnitude more positively and in a monotonic and convergent manner.In contrast with quantities on the windward face,the changes in quantities with respect to the horns were nonmonotonic with time and almost uncorrelated with the variation in modulation strength,which reveals the distinctiveness of leeside evolution. 展开更多
关键词 crescent-shaped dune wind tunnel experiment saturation level of sand flux digital image processing dune evolution
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