共查询到20条相似文献,搜索用时 15 毫秒
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In this paper, a novel approach to texture segmentation based on the parametric active contour model (ACM) is proposed. At first, gray-level co-occurrence matrix and subsequently co-occurrence energy of the regions inside and outside of the dynamic contour are calculated. Difference of this energy corresponding to both the regions is used as the external energy of the proposed ACM. The contour stops and converges completely when this difference attains a maximum value. The proposed approach requires only initial contour selection and no object point selection like the other variants of parametric ACM used for texture segmentation. Experiments on a number of synthetic and real-world texture images show that in all cases, we are getting a better segmentation of the object although for few cases the execution time is bit more than that of other existing methods. 相似文献
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J.S. Leng Y.C. Lai W. Zhang J.A.R. Williams 《Photonics Technology Letters, IEEE》2006,18(16):1729-1731
A novel architecture for microwave/millimeter-wave signal generation and data modulation using a fiber-grating-based distributed feedback laser has been proposed in this letter. For demonstration, a 155.52-Mb/s data stream on a 16.9-GHz subcarrier has been transmitted and recovered successfully. It has been proved that this technology would be of benefit to future microwave data transmission systems. 相似文献
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文中针对不同应用领域需要不同特性正交信号的问题,采用罗列比较的方法,通过具体电路的设计、制作、测试、分析、对比,得出了4种典型的正交信号产生方法及各自的优缺点。正交信号产生有4种典型的设计方案:单片机数字合成法,FPGA直接数字式频率合成器法,DDS集成芯片AD9851合成法,RC—CR相移网络法。文中介绍了这4种正交信号产生方法的具体原理并对各方法在幅值调节,频率调节范围,正交性等方面做了详细的对比,以便在不同设计要求下选择相应的设计方案。 相似文献
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一种基于FGN和IDFT的自相似通信量生成算法 总被引:3,自引:0,他引:3
对网络模拟中必需的自相似通信量生成方法进行了研究,提出了一种基于分数高斯噪声(FGN,fractionalGaussiannoise)过程和逆离散傅立叶变换(IDFF,inversediscreteFouriertransform)的自相似通信量生成算法--FGN-IDFT算法,并通过仿真实验和比较分析的方法对该算法的精度和计算复杂度进行了大量的实验和分析。研究结果表明,利用FGN-IDFT算法生成的自相似通信量的精度和速度都令人满意,为实际网络模拟的进一步深入研究提供了基础。 相似文献
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This paper describes a method which uses “derangement” permutations as scrambling keys in a frequency-domain speech scrambling system. Subjective tests based on the number test confirm that such keys produce scrambled speech with virtually no residual intelligibility. A new derangement generation algorithm is introduced for key generation. This algorithm maps each integer g, in the range of 0⩽g<(n-1)!, to a distinct derangement of 2 elements, 相似文献
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为了实现对指纹识别速度上的需求,对指纹算法做了较深入的探讨和分析,提出一种新的指纹匹配算法,该算法将稀疏矩阵应用到指纹匹配当中,根据稀疏矩阵计算速度快和存储容量小的特点,使得指纹匹配速度在一定程度上得到了提升。通过实验结果表明,本文算法在指纹图像增强和匹配速度方面有很大的提高,同时也降低了计算机的内存消耗。 相似文献
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This paper proposes a new spatio-temporal equalization method, which simultaneously utilizes an adaptive antenna array and a decision feedback equalizer (DFE). For effective spatio-temporal equalization with less computational cost, how to split equalization functionality into spatial processing, and temporal processing is quite important. One of the answers which we have given is “incoming signals with larger time delays should be cancelled at the spatial equalization part.” The weights of both adaptive antenna array elements and taps of DFE are calculated only using the estimated channel impulse response, therefore, it requires no information on direction of arrival (DoA). We show the performance of the proposed system in multipath fading channels often encountered in indoor wireless environments and discuss the attainable bit error rate (BER), antenna patterns, and the computational complexity in comparison with other equalization methods such as spatial equalization and temporal equalization 相似文献
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A new FDTD algorithm based on alternating-direction implicit method 总被引:32,自引:0,他引:32
In this paper, a new finite-difference time-domain (FDTD) algorithm is proposed in order to eliminate the Courant-Friedrich-Levy (CFL) condition restraint. The new algorithm is based on an alternating-direction implicit method. It is shown that the new algorithm is quite stable both analytically and numerically even when the CFL condition is not satisfied. Therefore, if the minimum cell size in the computational domain is required to be much smaller than the wavelength, this new algorithm is more efficient than conventional FDTD schemes in terms of computer resources such as central-processing-unit time. Numerical formulations are presented and simulation results are compared to those using the conventional FDTD method 相似文献
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To fulfill the need for acquiring three-dimensional(3D) objects with more realistic textures and depth information, this study proposes a method based on near-infrared laser, combined with dual camera field of view center correction and binocular stereo calibration, to precisely capture the target surface texture. Furthermore, we constructed a verification system using standard industrial cameras and line lasers, achieving the generation of binocular line laser point cloud real textures. Experiments conducted within a 400 mm to 600 mm testing range achieved a reconstruction accuracy of 0.047 2 mm and reduced the texture mapping error to 0.323 4 pixel, proving the effectiveness of this method and providing a high-precision, low-cost solution for 3D point cloud model texture mapping. 相似文献
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Caleb Yu-Sheng Cho Ming-Jer Chen Jia-Han Lin Chiou-Feng Chen 《Electron Device Letters, IEEE》2002,23(7):422-424
Overestimation of capacitance coupling coefficients in flash memory cells is encountered in the subthreshold slope method. By means of a two-parameters subthreshold current model ID=I0 exp[q(VGB - nVSB)/nkT], a mathematical formulation of the subthreshold swing ratio in the subthreshold slope method is constructed to isolate the measurement errors caused by process variations from the errors traditionally caused by bulk capacitance coupling. To minimize the effect of process variations, a new method is developed based on the model. In this method, the control gate voltage shift due to weak body effect is measured in flash memory cells in subthreshold, while the corresponding slope factor n is adequately deduced from threshold voltage versus source-to-substrate bias measurement in dummy devices. The corrected capacitance coupling coefficients show large improvements compared to the design values, and the updated errors are found to be close to that caused solely by bulk capacitance coupling. The method is also fast since only a small source-to-substrate bias of 0.1 V is needed for implementation of weak body effect, and thereby it can be used as an in-line monitor of capacitance coupling coefficients 相似文献
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为进一步强化航道安全,解决海事CCTV人工值守、非自动化问题,提出了基于稀疏表示的船体检测方法。利用稀疏表示实现对船体的检测时,首先构建样本特征矩阵,然后利用K-SVD算法对样本特征矩阵进行学习,得到冗余字典,最后对测试样本进行重构,根据马氏距离判断测试样本属性。通过与传统方法的试验比较,实验结果表明,该算法实时性好、检测准确率高,可以很好地对CCTV视频监控的船体进行检测与跟踪,解决CCTV人工值守、非自动化问题,节省大量人力资源。 相似文献
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一种新的基于密钥的混沌数字水印方法 总被引:10,自引:2,他引:10
针对现有混沌水印的安全性差、易被破译的问题,提出一种基于密钥的混沌数字水印方法。该方法在现有的混沌数字水印系统基础上,增加一个混沌映射,并将其初值作为私有密钥来克服有限字长效应的影响和提高数字水印算法抵抗群举攻击的性能。嵌入水印时,将选择的图像分块DCT中频系数与混沌序列相加,进行取模运算后再嵌入混沌映射模型进行迭代。检测时,利用相应的混沌映射模型生成混沌水印序列,并进行相关检测。研究结果验证本文提出这种方法的安全性和有效性。 相似文献
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Joux提出的三方密钥协商方案虽然简洁、高效,但不能抵抗中间人攻击。基于无证书公钥密码体制,提出一种新的无证书可认证多方密钥协商方案,新方案将Joux的三方协议拓展至多方,并且具有认证功能。由于新方案中所用的签名为短签名,所以整个认证过程计算效率较高,另外,新方案还具有简单证书管理、无密钥托管的优点,新方案满足无密钥控制、抗中间人的主动攻击、前向安全性和抗密钥泄露伪装攻击等多种安全特性。 相似文献