共查询到20条相似文献，搜索用时 29 毫秒
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A. Quirin O. Cordón J. Santamaría B. Vargas-Quesada F. Moya-Anegón 《Information processing & management》2008
In the last few years, there is an increasing interest to generate visual representations of very large scientific domains. A methodology based on the combined use of ISI–JCR category cocitation and social networks analysis through the use of the Pathfinder algorithm has demonstrated its ability to achieve high quality, schematic visualizations for these kinds of domains. Now, the next step would be to generate these scientograms in an on-line fashion. To do so, there is a need to significantly decrease the run time of the latter pruning technique when working with category cocitation matrices of a large dimension like the ones handled in these large domains (Pathfinder has a time complexity order of O(n4), with n being the number of categories in the cocitation matrix, i.e., the number of nodes in the network). 相似文献
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互联网的发展逐渐改变了人们的生活方式,电子邮件因其方便、快捷的特点已受到人们的青睐。但许多垃圾邮件同时也在网络中蔓延,占据了邮件服务器的大量存储空间,用户往往需要花费大量的时间去删除这些垃圾邮件。因此,研究邮件的自动过滤具有重要意义。邮件的自动过滤主要有基于规则和基于统计两种方式。而目前基于统计的过滤器中,常用的贝叶斯方法等是建立在经验风险最小化的基础之上,过滤器推广性能较差。支持向量机(SVM)是在统计学习理论的基础上发展而来的一种新的模式识别方法,在解决有限样本、非线性及高维模式识别问题中表现出许多特有的优势。它不仅考虑了对推广能力的要求,而且追求在有限信息的条件下得到最优结果。因此,本文将支持向量机应用于邮件过滤,实验证明过滤效果较好。 相似文献
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提出基于差别矩阵的改进启发式粗糙集属性约简算法,降低算法的时间复杂度及空间复杂度。针对相关实际案例数据。以学生考试成绩为分析对象,应用改进后的约简算法,设计相应的评价指标,分析学生成绩的潜在影响因素,再次验证了本文提出算法的可行性和高效性。 相似文献
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探讨动态规划法的本质及在计算机程序设计中的应用。提出求解Fibonacci序列的3种算法,即递归法、自底向上和自顶向下动态规划法,证明将动态规划法用于程序设计,能降低算法的时间复杂度和空间复杂度。 相似文献
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研究了无线传感器网络中的数据汇聚节点放置问题. 通过将无限的搜索空间划分为有限的"通讯交集",在量级上降低了问题的复杂度. 基于这样的理念,建立了基于网格的线性优化模型,并由仿真试验验证了此方案的有效性. 相似文献
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一种基于视频的无损信息隐藏方法 总被引：2，自引：0，他引：2
描述了一种基于MPEG-Ⅱ彩色视频中的无损信息隐藏方法，该方法在Alattar算法的基础上，使宿主矢量类型的判别由四个不等式，减小到两个不等式，降低了算法的时间复杂度。数据嵌入过程中采用简单数据链路SDL成帧。在局域网上进行了隐秘传输模拟实验，从嵌入信息的视频中正确提取出所嵌入汉字或二值指纹图像后，原宿主视频可无损恢复。该方法较适用于视频中的隐秘传输及产权保护等领域。 相似文献
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对识别后的语音文档进行了向量空间模型的建立,针对得到的高维稀疏矩阵提出了基于局部敏感哈希的语音文档分类算法,算法能够直接在高维稀疏矩阵上进行分类,无需降维。此外,在构建局部敏感哈希函数的时候结合了稳定分布。实验证明,局部敏感哈希算法能够对语音文档进行合理有效的分类,同时获得了较小的时间复杂度。 相似文献
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A self-organization algorithm for image compression and the associated VLSI architecture are presented. A frequency upper-threshold is effectively used in the centroid learning method. Performances of the self-organization networks and traditional nonself-organization algorithms for vector quantization are compared. This new algorithm is quite efficient and can achieve near-optimal results. A trainable VLSI neuroprocessor based upon this new self-organization network has been developed for high-speed and high-ratio image compression applications. This neural-based vector quantization design includes a fully parallel vector quantizer and a pipelined codebook generator which obtains a time complexity O (1) for each quantization vector. A 5 × 5-dimensional vector quantizer prototype chip has been designed and fabricated. It contains 64 inner-product neural units and an extendable winner-take-all block. This mixed-signal chip occupies a compact silicon area of 4.6 × 6.8 mm2 in a 2.0-μm scalable CMOS technology. It provides a computing capability as high as 3.33 billion connections per second. It can achieve a speedup factor of 110 compared with a SUN-4/75 workstation for a compression ratio of 33. Real-time adaptive VQ on industrial 1024 × 1024 pixel images is feasible using multiple neuroprocessor chips. An industrial-level design to achieve 104 billion connections per second for the 1024-codevector vector quantizer can be fabricated in a 125 mm2 chip through a 1 μm CMOS technology. 相似文献
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指出了文《R-循环分块矩阵求逆的快速傅里叶算法》中的一个错误,并证明了n阶r-循环矩阵的m次方根矩阵中仍为r-循环矩阵的矩阵个数为m^n,进一步给出了求n阶r-循环矩阵的m次方根矩阵中仍为r-循环矩阵的矩阵的快速算法,若用FFT计算一个m次方根矩阵,其时间复杂性为O（nlog2n）;计算全部平方根矩阵的时间复杂性为O（nm^n）。同时,本文还给出了求r-循环矩阵主平方根矩阵的算法。 相似文献
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With the development of information technology and economic growth, the Internet of Things (IoT) industry has also entered the fast lane of development. The IoT industry system has also gradually improved, forming a complete industrial foundation, including chips, electronic components, equipment, software, integrated systems, IoT services, and telecom operators. In the event of selective forwarding attacks, virus damage, malicious virus intrusion, etc., the losses caused by such security problems are more serious than those of traditional networks, which are not only network information materials, but also physical objects. The limitations of sensor node resources in the Internet of Things, the complexity of networking, and the open wireless broadcast communication characteristics make it vulnerable to attacks. Intrusion Detection System (IDS) helps identify anomalies in the network and takes the necessary countermeasures to ensure the safe and reliable operation of IoT applications. This paper proposes an IoT feature extraction and intrusion detection algorithm for intelligent city based on deep migration learning model, which combines deep learning model with intrusion detection technology. According to the existing literature and algorithms, this paper introduces the modeling scheme of migration learning model and data feature extraction. In the experimental part, KDD CUP 99 was selected as the experimental data set, and 10% of the data was used as training data. At the same time, the proposed algorithm is compared with the existing algorithms. The experimental results show that the proposed algorithm has shorter detection time and higher detection efficiency. 相似文献
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由于现代密码学正是建立在整数分解理论和计算复杂性理论的基础之上,因此素性测试问题对现代密码学的影响引起了人们的关注.本文将主要讨论现代密码学中的素性测试问题及其算法实现.然后再介绍几种素性测试算法及其实现. 相似文献
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基于有限差分时域有限差分方法的递归算法的时间和空间来设置完全匹配层(PML)的吸收效应的推导和分析。试验结果证实,PML在多层介质中具备优异的吸声性能。最后,在FDTD算法的PML吸收层是用来模拟在两层和三层介质模拟区。PML的有效性的验证。 相似文献
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基于变长Turbo码的联合信源信道译码通过构造联合译码平面网格图,具有比比特级译码更好的性能.但平面网格图复杂,使变长Turbo码译码复杂度高.基于此,构造了一个空间网格图,提出基于变长Turbo码的低复杂度联合信源信道译码方法.仿真结果表明,该算法比平面网格图计算复杂度减少约3.8%,在SER(symbol error ratio)为10-4时,获得Eb/N0增益约为0.2dB. 相似文献
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Dandan Yue Zhi-Hong Guan Juan Li Feng Liu Jiang-Wen Xiao Guang Ling 《Journal of The Franklin Institute》2019,356(5):2847-2869
In this paper, we study the local stability and bifurcation of a delay-coupled genetic regulatory networks consisting of two modes with the hub structure. By analyzing the equilibrium equation, the number of the positive equilibria is discussed in both the cases that there are inhibition coupling and activation coupling in the networks. It is revealed that multiple equilibria could exist in the developed genetic networks and the number of the equilibria could be distinct under the two cases of delayed-coupling. For the equilibrium, the conditions of the coupling-delay-independent stability and the saddle-node bifurcation are derived with respect to the biochemical parameters. The coupling-delay-dependent stability and the Hopf bifurcation criteria on the biological parameters and the coupling delay are also given. Moreover, the complexity of the algorithm used in this paper is analyzed. The numerical simulations are made to certify the obtained results. The multistability of the developed genetic regulatory networks is displayed. The different effects of the coupling delay on the stability of the genetic networks under different biochemical parameters are shown. 相似文献
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T. Radhakrishnan 《Information processing & management》1978,14(2):97-106
In this paper a simple algorithm is used for selection of a set of codeable substrings that occur at the front or rear of the words in a textual data base. Since the words are assumed to be non-repeating, the technique is useful for data compression of dictionaries. The time complexity of the algorithm is governed by the associated sorting algorithm and hence is 0 (n log n). It has been applied to three sample data bases, consisting of words selected from street names, authors names, or general written English text. The results show that the substrings at the rear of the words, yield better compression than those at the front. By application of results of an earlier study in compression coding, efficient encoding and decoding procedures are presented for use in on-line transmission of data. 相似文献