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三维打印快速成型层面位图的生成算法 被引量:2
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作者 刘厚才 莫健华 储爱民 《工程图学学报》 CSCD 北大核心 2009年第5期63-68,共6页
提出了新的基于轮廓边的快速求交算法,实现了快速成型系统中层面位图数据的生成。该算法不仅简单、效率高,而且可以处理求交过程中遇到的各种奇点问题,特别是用经典求交方法难以判断和处理的当扫描线通过带水平轮廓边的凸拐点和凹拐点... 提出了新的基于轮廓边的快速求交算法,实现了快速成型系统中层面位图数据的生成。该算法不仅简单、效率高,而且可以处理求交过程中遇到的各种奇点问题,特别是用经典求交方法难以判断和处理的当扫描线通过带水平轮廓边的凸拐点和凹拐点带来的奇点问题。通过在自制的3DP快速成型样机上的试验运行,证明该算法有较好的鲁棒性。 展开更多
关键词 计算机应用 层面位图生成算法 快速成型 求交算法
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位图的转向算法及其实现
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作者 于永彦 赵建洋 《微型电脑应用》 2002年第2期41-42,26,共3页
多媒体编程中图形的操作占据着重要的地位 ,尤其是位图的平面旋转和立体翻转更是其中的主要部分 ,也更具复杂性和多样化。本文给出其中的一种算法 ,并经 Del-phi5 .0调试通过 。
关键词 多媒体编程 位图转向算法 计算机 WINDOWS
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位图运算与处理
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作者 赵亚林 《移动信息》 2016年第4期32-32,共1页
图形(或图像)在计算机里主要有矢量图和位图两种存储和表示方法。矢量图是使用点、直线或多边形等基于数学方程的几何对象来描述图形,位图则使用像素来描述图像,矢量图可以任意放缩,图形不会有任何改变。而位图一旦放大后会产生较为明... 图形(或图像)在计算机里主要有矢量图和位图两种存储和表示方法。矢量图是使用点、直线或多边形等基于数学方程的几何对象来描述图形,位图则使用像素来描述图像,矢量图可以任意放缩,图形不会有任何改变。而位图一旦放大后会产生较为明显的模糊,线条也会出现锯齿边缘等现象。因此基于“位图算法”来建立多种模型,来解决位图实际运用中的问题。 展开更多
关键词 位图算法 灰度提取 阈值 二值化 矢量化 三角函数逼近
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一种适时动画图像内存预叠加显示算法及其应用
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作者 刘虎 于长辉 王旺 《计算机与现代化》 2002年第5期14-15,共2页
介绍了一种内存位图叠加图像显示算法 ,比较了它和分层刷新显示算法在适时动画编程中的效率 ;给出了利用WindowsAPI函数编程实现以上算法的实例。
关键词 动画图像 内存预叠加显示算法 位图显示算法 计算机
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一种基于树状结构的无线传感网络低功耗算法
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作者 蔡晓宇 《信息化研究》 2012年第2期34-37,43,共5页
针对无线传感器网络(Wireless sensor networks,WSNs)的能耗问题,在保证低延迟率的前提下,通过降低空闲模式下的能量消耗,提出一种适用于大型树簇状无线传感器网络结构的位图辅助式低功耗算法(Bit-map assisted low power algorithm,BAL... 针对无线传感器网络(Wireless sensor networks,WSNs)的能耗问题,在保证低延迟率的前提下,通过降低空闲模式下的能量消耗,提出一种适用于大型树簇状无线传感器网络结构的位图辅助式低功耗算法(Bit-map assisted low power algorithm,BALPA),建立了能量模型。仿真结果表明:此算法和传统TDMA、低功耗TDMA(E-TDMA)算法相比,在相同参数下,最多能减少35%的能耗,显著降低能量开销和数据包延迟速度,延长系统的使用寿命。 展开更多
关键词 无线传感器网络 低功耗 位图辅助式低功耗算法
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基于Xen的虚拟机动态迁移技术研究及应用
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作者 赵冉 岳小冰 《河南科技》 2014年第3期7-7,共1页
基于Xen的虚拟机动态迁移技术用到的算法是pre—copy算法,这种算法在单一情景时会出现传输率低下的情况,严重阻碍了虚拟机技术的发展。在科学家的进一步研究下,提出了矩阵位图算法,这种算法对更改页面的传输效率比较高,下面我们就针对... 基于Xen的虚拟机动态迁移技术用到的算法是pre—copy算法,这种算法在单一情景时会出现传输率低下的情况,严重阻碍了虚拟机技术的发展。在科学家的进一步研究下,提出了矩阵位图算法,这种算法对更改页面的传输效率比较高,下面我们就针对两种算法,最具体的数值比较,从中验证我们所说的结论是否正确。 展开更多
关键词 Xen虚拟机技术 算法 矩阵位图算法
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一种新型纹织CAD/CAM电脑意匠系统
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作者 范福玲 王珊燕 +2 位作者 沈林 郭艳青 韩建勋 《成组技术与生产现代化》 2001年第4期20-22,共3页
介绍了一种新的电脑意匠系统 .论述了目前先进的图像处理技术如边缘检测、灰度自动分级和伪彩色处理在纹织CAD/CAM电脑意匠系统中的应用及其对系统改造和功能完善的实施方法 .通过高斯拉普拉斯组合算子的去噪处理 ,使原来的人工修图可... 介绍了一种新的电脑意匠系统 .论述了目前先进的图像处理技术如边缘检测、灰度自动分级和伪彩色处理在纹织CAD/CAM电脑意匠系统中的应用及其对系统改造和功能完善的实施方法 .通过高斯拉普拉斯组合算子的去噪处理 ,使原来的人工修图可以由计算机自动完成 .灰度自动分级使计算机可以预览产品的最后效果 .伪彩色处理可以获得良好的人机界面 . 展开更多
关键词 纹织CAD/CAM 图像处理 位图处理算法
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若干图像新技术在纹织CAD/CAM中的应用
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作者 王珊燕 沈霖 赵宪军 《现代机械》 2002年第3期4-6,共3页
本文论述了将目前先进的图像处理技术用于纹织CAD/CAM系统 ,使纹织CAD/CAM系统的智能化水平获得很大提高 。
关键词 纹织 CAD CAM 图像处理 位图处理算法
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封闭立方体反转索引查询优化技术
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作者 肖伟吉 奚建清 欧国华 《计算机应用研究》 CSCD 北大核心 2008年第10期2977-2981,共5页
处理用户复杂查询请求的速度是数据仓库关键性能之一。论述了在QC算法产生的聚集表上建立反转索引和查询并还原出立方体上界的方法,查询算法包括位图查询算法和反转列表查询算法。最后进行了性能测试,结果表明这两种算法均能够提高查询... 处理用户复杂查询请求的速度是数据仓库关键性能之一。论述了在QC算法产生的聚集表上建立反转索引和查询并还原出立方体上界的方法,查询算法包括位图查询算法和反转列表查询算法。最后进行了性能测试,结果表明这两种算法均能够提高查询的速度。 展开更多
关键词 封闭立方体 位图查询算法 反转列表查询算法
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Location algorithm for seal imprints on Chinese bank-checks based on region growing 被引量:5
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作者 CHEN Li-jiang LIU Tie-gen +3 位作者 CHEN Jia-Jia ZHU Jun-chao DENG Ji-Jie MA She-xiang 《Optoelectronics Letters》 EI 2006年第2期155-157,共3页
The paper focuses on location of seal imprints on Chinese bank-checks based on region growing.Region growing method can be applied to searching and locating connection region in an image.A seal imprint,however,is gene... The paper focuses on location of seal imprints on Chinese bank-checks based on region growing.Region growing method can be applied to searching and locating connection region in an image.A seal imprint,however,is generally composed of various connection regions which are unconnected to each other.In order to locate the seal imprint,these connection regions must be fused together.In the paper,an algorithm for locating seal imprints on Chinese bankchecks based on region growing is proposed, of which a fusion criterion for connection regions in a seal imprint is put forth based on the image feature of Chinese bankcheck,and a center-rays model is proposed to find the topological relationship between connection regions,for which externally-tangent rectangle of region is used as the mark of location of region.The location experiment is achieved with a false-acceptance rate of 7.1% and a false-rejection rate of 0% on Chinese bankcheck. 展开更多
关键词 定位算法 封装技术 图象识别 射线模式
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Decryption of pure-position permutation algorithms 被引量:3
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作者 赵晓宇 陈刚 +2 位作者 张亶 王肖虹 董光昌 《Journal of Zhejiang University Science》 EI CSCD 2004年第7期803-809,共7页
Pure position permutation image encryption algorithms, commonly used as image encryption investigated in this work are unfortunately frail under known-text attack. In view of the weakness of pure position permutation ... Pure position permutation image encryption algorithms, commonly used as image encryption investigated in this work are unfortunately frail under known-text attack. In view of the weakness of pure position permutation algorithm,we put forward an effective decryption algorithm for all pure-position permutation algorithms. First, a summary of the pure position permutation image encryption algorithms is given by introducing the concept of ergodic matrices. Then, by using probability theory and algebraic principles, the decryption probability of pure-position permutation algorithms is verified theoretically; and then, by defining the operation system of fuzzy ergodic matrices, we improve a specific decryption al-gorithm. Finally, some simulation results are shown. 展开更多
关键词 DECRYPTION Image encryption FUZZY Position permutation
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Analyzing the Interdependence Between Some Certain Gene Loci by Epistasis Measures in Fitness Landscapes of Schemata
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作者 李建武 李敏强 《Transactions of Tianjin University》 EI CAS 2003年第1期63-67,共5页
GA hardness and interdependence between genes in the chromosome are important questions in the study of genetic algorithms(GA). Traditional methods, which are used to measure the interaction between genes, can only re... GA hardness and interdependence between genes in the chromosome are important questions in the study of genetic algorithms(GA). Traditional methods, which are used to measure the interaction between genes, can only reflect the extent of epistasis between all genes in the chromosome. Therefore, the definition of the fitness landscape of schemata is proposed in this paper, and epistasis measures on this landscape of schemata are used to analyze the degree of interdependence between some certain gene loci in study. Some information between these sites can be reflected by some characters of the fitness landscape of schemata which are composed of these fixed sites. The stronger the interaction between these sites, the larger the variation of the fitness of schemata whose fixed sites correspond to those sites in study, and the more rugged the fitness landscape of these schemata. According to the degree of interaction between these given gene loci, building blocks of GA can be analyzed and determined, and further genetic operators and the structure of GA can be designed and adjusted to improve the performance of GA. At last, a lot of experiments including NK models are done, and results of empirical analysis show that this method is effective. 展开更多
关键词 EPISTASIS fitness landscapes GA hardness NK models schemata
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Subpixel Target Location Techniques for 3-D Coordinate Measuring System
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作者 YUZhi-jing MASu-ying 《Semiconductor Photonics and Technology》 CAS 2002年第2期111-115,共5页
the close photogrammetric 3-D coordinate measurement is a newmeasuring technology in the fields of the coordinate measurementmachine (CMM) in recent years. In this method, we usually place sometargets on the measured ... the close photogrammetric 3-D coordinate measurement is a newmeasuring technology in the fields of the coordinate measurementmachine (CMM) in recent years. In this method, we usually place sometargets on the measured object and take image of targets to determinethe object coordinate. The subpixel location of target image plays animportant role in high accuracy 3-D coordinate measuring procedure.In this paper, some subpixel location methods are reviewed and somefactors which affect location precision are analyzed. 展开更多
关键词 Subpixel precision target location centroid algorithm bilinearinterpolation
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InSAR Kalman Filter Phase Unwrapping Algorithm Based on SRTM DEM
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作者 Huadong Hao Guolin Liu +1 位作者 Xianlei Chen Zhentan Cao 《Journal of Earth Science and Engineering》 2012年第4期247-252,共6页
PU (phase unwrapping) is the key step and important problem in DEM (digital elevation model) extraction and the measurement of surface deformation of InSAR (Interferometric synthetic aperture radar). The CKFPUA ... PU (phase unwrapping) is the key step and important problem in DEM (digital elevation model) extraction and the measurement of surface deformation of InSAR (Interferometric synthetic aperture radar). The CKFPUA (conventional Kalman filter phase unwrapping algorithm) can obtain reliable results in the flat terrain areas, but it caused error transmission not making the accurate inversion of surface deformation information in the steep terrain. Considering this situation, so it needs to introduce topographic information for guiding phase unwrapping. Here the 90 m resolution DEM data have been used and it is obtained by SRTM (shuttle radar topography mission) measured jointly by NASA (National Aeronautics and Space Administration) and NIMA (National Imaging Mapping Agency) of U.S. Department of Defense. This paper presents a SD-KFPUA (Kalman filter phase unwrapping algorithm) based on SRTM DEM. With SRTM DEM directing InSAR image to implement phase unwrapping, the speed and accuracy are improved. By analyzing with the conventional Kalman filter phase unwrapping algorithms, it is shown that the proposed method can achieve good results in particular to improve unwrapping accuracy in the low coherence region. 展开更多
关键词 INSAR phase unwrapping Kalman filter topographic factors SRTM DEM.
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A fast automatic recognition and location algorithm for fetal genital organs in ultrasound images
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作者 Sheng TANG Si-ping CHEN 《Journal of Zhejiang University-Science B(Biomedicine & Biotechnology)》 SCIE CAS CSCD 2009年第9期648-658,共11页
Severe sex ratio imbalance at birth is now becoming an important issue in several Asian countries. Its leading immediate cause is prenatal sex-selective abortion following illegal sex identification by ultrasound scan... Severe sex ratio imbalance at birth is now becoming an important issue in several Asian countries. Its leading immediate cause is prenatal sex-selective abortion following illegal sex identification by ultrasound scanning. In this paper, a fast automatic recognition and location algorithm for fetal genital organs is proposed as an effective method to help prevent ultrasound technicians from unethically and illegally identifying the sex of the fetus. This automatic recognition algorithm can be divided into two stages. In the 'rough' stage, a few pixels in the image, which are likely to represent the genital organs, are automatically chosen as points of interest (POIs) according to certain salient characteristics of fetal genital organs. In the 'fine' stage, a specifically supervised learning framework, which fuses an effective feature data preprocessing mechanism into the multiple classifier architecture, is applied to every POI. The basic classifiers in the framework are selected from three widely used classifiers: radial basis function network, backpropagation network, and support vector machine. The classification results of all the POIs are then synthesized to determine whether the fetal genital organ is present in the image, and to locate the genital organ within the positive image. Experiments were designed and carried out based on an image dataset comprising 658 positive images (images with fetal genital organs) and 500 negative images (images without fetal genital organs). The experimental results showed true positive (TP) and true negative (TN) results from 80.5% (265 from 329) and 83.0% (415 from 500) of samples, respectively. The average computation time was 453 ms per image. 展开更多
关键词 Ultrasound image Fetal genital organ Point of interest (POI) Feature selection Feature extraction Class imbalance Multiple classifier architecture
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Constrained Submap Algorithm for Simultaneous Localization and Mapping
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作者 钱钧 王晨 +2 位作者 杨明 杨汝清 王春香 《Journal of Shanghai Jiaotong university(Science)》 EI 2009年第5期600-605,共6页
When solving the problem of simultaneous localization and mapping(SLAM) ,a standard extended Kalman filter(EKF) is subject to linearization errors and causes optimistic estimation.This paper proposes a submap algorith... When solving the problem of simultaneous localization and mapping(SLAM) ,a standard extended Kalman filter(EKF) is subject to linearization errors and causes optimistic estimation.This paper proposes a submap algorithm,which builds a weighted least squares(WLS) constraint between two adjacent submaps according to the different estimations of the common features and the relationship between the vehicle poses in the corresponding submaps.By establishing the constraint equation after loop closing,re-linearization is implemented and each submap's reference frame tends to its equilibrium position quickly.Experimental results demonstrate that the algorithm could get a globally consistent map and linearization errors are limited in local regions. 展开更多
关键词 simultaneous localization and mapping (SLAM) CONSISTENCY submap weighted least squares (WLS)
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Squint-mode InISAR imaging based on nonlinear least square and coordinates transform 被引量:5
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作者 LIU ChengLan HE Feng +2 位作者 GAO XunZhang LI Xiang SHEN RongJun 《Science China(Technological Sciences)》 SCIE EI CAS 2011年第12期3332-3340,共9页
Aiming at the interferometric inverse synthetic aperture radar (InlSAR) imaging in the presence of squint, we investigate the influence of squint on the InlSAR imaging. First, coupling of the squint additive phase a... Aiming at the interferometric inverse synthetic aperture radar (InlSAR) imaging in the presence of squint, we investigate the influence of squint on the InlSAR imaging. First, coupling of the squint additive phase and the target azimuth/altitude coordinates to be solved may make the solution more difficult. Second, the squint angle may lead to estimation error of the vertical coordinates and distortion of the ultimate image. Traditional InlSAR imaging algorithms can not solve the above two problems effectively, so we propose a new method which combines the nonlinear least square (NLS) and coordinates transform (CT) to estimate the target coordinates, and a three-dimensional (3-D) image consistent with the real target is obtained accordingly. Simulations show that the proposed method is effective for the squint-mode InlSAR imaging. 展开更多
关键词 interferometric inverse synthetic aperture radar (InlSAR) three dimensional (3-D) imaging squint mode nonlinear least square (NLS) coordinates transform (CT)
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