基于感知哈希的图像内容鉴别性能分析

感知哈希能有效地区分不同内容的图像,常用于检测盗版或重复的图像内容鉴别应用中.针对已有的对感知哈希的图像内容鉴别应用研究主要集中在算法设计上,缺少对其性能评价的理论方法的问题,提出从理论上评价内容鉴别性能的方法.该方法基于一类图像感知哈希算法的抗碰撞特性建立了内容鉴别的判定模型,并定义内容鉴别的性能公式,最后推导出统计学上的函数作为性能评价指标.实验结果表明,文中方法能很好地估计感知哈希在内容鉴别应用中的性能.     

一种基于单模型的网页净化方法

为了能够更好地获得和处理网页中的正文信息,本文提出基于改进的DOM树和BP神经网络的网页净化算法。该算法根据DOM树和网页内容的特征用HTMLParser把网页转换成一棵内容块树。因网页子内容块具有相当明显的数值特征,可以通过BP神经网络建立网页噪音信息过滤模型。这样使得网页净化更加模型化,也能够取得更加好的效果。     

硫酸盐含量对全固废材料固化盐渍土抗压强度的影响

为探讨硫酸盐含量对全固废材料固化盐渍土抗压强度及微观结构的影响,采用击实试验和无侧限抗压强度试验,并结合扫描电镜、EDS、X射线衍射和热重分析等微观测试结果,从固化盐渍土的火山灰反应产物及其数量等角度分析含盐量对固化盐渍土抗压强度变化的影响。结果表明:硫酸盐含量低于2.7%时,固化盐渍土抗压强度随含盐量的增加呈先增大后减小,抗压强度峰值对应的含盐量为1.8%;固化盐渍土的火山灰反应产物主要为C-S-H和AFt,硫酸盐含量从0.3%增至1.8%时,反应产物明显增多,致使固化土抗压强度增大;但当硫酸盐含量从1.8%增至2.7%时,膨胀性AFt将试件内部孔隙完全填充并产生胀裂破坏,造成抗压强度降低。研究成果为全固废材料固化硫酸盐渍土的工程应用奠定了基础,对环境保护也有积极贡献。     

Searching minimax game trees under memory space constraint

Games such as CHESS, GO and OTHELLO can be represented by minimax game trees. Among various search procedures to solve such game trees,- and SSS^* are perhaps most well known. Although it is proved that SSS^* explores only a subset of the nodes explored by-, - is commonly believed to be faster in real applications, since it requires very little memory space and hence its storage management cost is low. Contrary to this folklore, however, this paper reports, using the OTHELLO game as an example, that SSS^* is much faster than-. It is also demonstrated that SSS^* can be modified to make the required memory space controllable to some extent, while retaining the high efficiency of the original SSS^*.This research was partially supported by the Ministry of Education, Science and Culture of Japan, under a Scientific Grant-in-Aid.     

Consequences of the formation of Cooper-pairs near oxygen-deficient sites

In this investigation we consider the formation of Cooper pairs near the oxygen-deficient sites in Y-Ba-Cu-O ceramic superconductors which would give rise to an energy-dependent potential as seen by conduction charge carriers. It is shown that Cooper pairs could be formed under such conditions, resulting in a supercurrent. We use the Bogoliubov transformation technique to calculate the energy gap, the energy difference, and the transition temperature of the model superconductor using certain data obtained from previous experiments. Numerical analysis shows that the superconducting current can be explained by the presence of such oscillating Cooper pairs.     

多字体印刷藏文内容监测系统研究

针对藏文舆情分析中藏文印刷品和藏文图片内容无法自动监测的难题,文章在深入分析印刷藏文字符特征和藏文文本特点的基础上,提出支持多字体印刷藏文内容监测系统的实现方法,重点阐述藏文字符的特征提取、分类算法以及藏文文本内容监测方法。     

隐极无刷双馈电动机的研究

针对无刷双馈电动机的转子磁场转换效率决定了其工作效率的问题,提出了一种隐极无刷双馈电动机隐极转子结构的优化设计方案。对作用较小的隐极转子进行优化设计,即将它们的槽型更改为半开口槽,不断改变它们的长宽比;利用有限元软件ANSYS分析不同长宽比转子结构的隐极无刷双馈电动机,获得其功率绕组励磁与控制绕组励磁分布;利用Matlab软件分解转子磁动势,获得转子磁动势的谐波含量,从而确定最有效谐波含量。实验结果表明,在设定隐极转子的长宽比分别为10、13、15、17、20的情况下,隐极无刷电动机在15倍长宽比转子结构时的能量转换效果最好。     

A functional programming approach to the specification and verification of concurrent systems

Networks of communicating processes can be viewed as networks of stream transformers and programmed in a lazy functional language. Thus the correctness of concurrent systems can be reduced to the correctness of functional programs. In this paper such correctness is proved formally in the-calculus extended with recursion equations for functional programs. The-calculus is chosen since it allows the definition of properties by least fixed points (induction) as well as by greatest fixed points (coinduction), and since greatest fixed points are useful for formalising properties, such as fairness, of infinitely proceeding programs. Moreover, non-deterministic processes are represented as incompletely specified deterministic processes, that is, as properties of stream transformers. This method is illustrated by proving the correctness of the alternating bit protocol.     

Effect of 0.1 at.% zirconium on the cyclic oxidation resistance ofβ-NiAl

The effect of 0.1 at.% Zr (0.2 wt.% Zr) on the cyclic oxidation of hipped -NiAl was studied. Oxidation testing was performed in static air at 1100–1200 °C, using 1-hr exposure cycles for test times up to 3000 hr. The weight change versus time data were modeled with the COSP computer program to analyze and predict cyclic-oxidation behavior. Zr additions significantly change the nature of the scale-spalling process during cooling so that the oxide spalls near the oxide-air interface at a relatively low depth within the scale. Without Zr, the predominantly -Al₂O₃ scale tends to spall randomly to bare metal at relatively high effective-scale-loss rates, particularly at 1150°C and 1200°C. This leads to higher rates of Al consumption for the Zr-free aluminide and much earlier depletion of Al, leading to eventual breakaway (i.e., failure).