一种文本图像水印的算法研究

该文提出了一种文本图像水印的新算法。首先将文本中选定嵌入水印的区域视为一个彩色图像,对其进行离散余弦变换（DCT）,并将变换系数进行加密排序之后,则经典的乘性水印算法转变为加性算法。将排序之后的DCT系数视为分叉噪声,而水印信号为弱信号,那么利用加性噪声中弱信号榆测理论推导出一种水印检测器来检测水印信号,并对其检测性能进行了理论和实验分析。实验表明这种检测器对于高斯加性噪声、中值滤波、乘性噪音以及低通滤波等多种攻击手段都具有较好的抗攻击能力。     

New text indexing functionalities of the compressed suffix arrays

New text indexing functionalities of the compressed suffix arrays are proposed. The compressed suffix array proposed by Grossi and Vitter is a space-efficient data structure for text indexing. It occupies only O(n) bits for a text of length n; however it also uses the text itself that occupies bits for the alphabet . In this paper we modify the data structure so that pattern matching can be done without any access to the text. In addition to the original functions of the compressed suffix array, we add new operations search, decompress and inverse to the compressed suffix arrays. We show that the new index can find occ occurrences of any substring P of the text in O(|P|logn+occlog^εn) time for any fixed 1ε>0 without access to the text. The index also can decompress a part of the text of length m in O(m+log^εn) time. For a text of length n on an alphabet such that , our new index occupies only bits where is the order-0 entropy of the text. Especially for ε=1 the size is bits. Therefore the index will be smaller than the text, which means we can perform fast queries from compressed texts.     

Relevant and rich interactivity under uncertainty: Guest reviews,host responses,and guest purchase intention on Airbnb

Online commerce, increasingly running on digital platforms, is subject to higher uncertainty and risk in transactions (e.g., fraud, opportunism) than offline commerce. To cope with this challenge, online commerce companies often use information systems to promote interactive communication between sellers and buyers. This study examines how such seller-buyer interactivity affects buyers’ purchase intention in an online commerce context of accommodation sharing. In particular, we use text mining techniques to analyze guest reviews and host responses on Airbnb. Our analysis suggests that not only the quantity but also the quality of the response messages matter: potential guests’ purchase intention increases with the relevance and richness of the host’s responses as well as their volume. Further, we find a notable nonlinearity in the quantity effect that the volume of host responses significantly affects guest purchase intention only when it is large enough. Making sufficient responses, the hosts could enjoy complementarity between the quantity and quality effects of their responses; otherwise, the relative richness of their responses becomes more important.     

Grammar compressed sequences with rank/select support

Sequence representations supporting not only direct access to their symbols, but also rank/select operations, are a fundamental building block in many compressed data structures. Several recent applications need to represent highly repetitive sequences, and classical statistical compression proves ineffective. We introduce, instead, grammar-based representations for repetitive sequences, which use up to 6% of the space needed by statistically compressed representations, and support direct access and rank/select operations within tens of microseconds. We demonstrate the impact of our structures in text indexing applications.     

基于支持向量机的Web文本分类方法

Web文本分类技术是数据挖掘中一个研究热点领域，而支持向量机又是一种高效的分类识别方法，在解决高维模式识别问题中表现出许多特有的优势。文章通过分析Web文本的特点，研究了向量空间模型（VSM）的分类方法和核函数的选取，在此基础上结合决策树方法提出了一种基于决策树支持向量机的Web文本分类模型。并给出具体的算法。通过实验测试表明，该方法训练数据规模大大减少，训练效率较高，同时具有较好的精确率（90．11％）和召回率（89．38％）。     

脱机手写维吾尔文本行字符粘连区定位及分割

在大篇幅的手写维吾尔文文本图像中,往往会出现粘连字符这一现象。这一现象会对文本行分析和笔迹鉴别等研究工作造成影响,同时所处环境为大篇幅手写图像,在对粘连字符切分时会受到其余非粘连字符的较大干扰。针对上述问题,本文提出了对手写文本图像定位线的正确提取方案,以连通域特性为基础,通过定位线与文本图像融合,使行间粘连字符所在文本行为同一连通域想法,可自动提取出粘连文本行,再根据粘连字符所占宽度和高度大于非粘连字符,从而自动提取出粘连字符。对提取出的粘连字符通过定位线可确定出粘连区域,对粘连点所处位置进行统计分析后在该位置处添加一条与背景同色细线从而达到分割效果,最后对分割后的粘连文本行通过着色方法逐行提取。实验表明,上述问题通过我们的方法得到了很好的解决。在实验结果分析中,本文给出了每个算法的性能指标数据,并与其它文献进行了对比分析,论证了本文研究方法的可行性及存在的一些主要问题。     

A frown emoji can be worth a thousand words: Perceptions of emoji use in text messages exchanged between romantic partners

Computer-mediated communication (CMC) can facilitate the expression of affection between romantic partners and promote relationship quality. Text messaging is nowadays an important means of expressing affection and to feel close to one’s partner. However, it is unclear if adding emoji to text messages influences perceptions about the relationship. In two experiments (combined N = 451), participants evaluated the relationship interest of a romantic partner, based on the messages exchanged. Study 1 compared positive and negative replies varying in emotional cues (without vs. text vs. emoji). Results showed that positive replies signaled the greatest interest, regardless of cue. In contrast, negative replies with (vs. without) cues signaled greater interest in the relationship and this was especially evident for messages with emoji. This benefit occurred because these messages were perceived as more positive (vs. negative messages without cue). Study 2 compared negative replies varying in the seriousness of the issue. Results showed that, for more serious replies, emotional text signaled greater interest by increasing message positivity. In contrast, emoji signaled less interest by increasing message negativity. Together, findings showed how CMC between romantic partners can benefit and be harmed by including emoji.     

Examining user behavioral response to SMS ads: Implications for the evolution of the mobile phone as a bona-fide medium

The mobile phone has emerged as the newest medium of interactive marketing and advertising. Undoubtedly, users of a personal medium like the mobile phone play a decisive role in commercializing the mobile phone. By examining the major influences on mobile phone users’ behavioral responses to SMS (Short Message Service) ads, this study seeks to shed light on the evolution of the mobile telephony as a bona-fide medium. Results of a survey of 407 mobile phone users in Singapore show that receiving SMS ads has become widespread, although the number of SMS ads received remains small. Furthermore, the instrumental and diversion motivations, prior consent, and privacy concerns directly affect the likelihood for users to pass the ads to others. Finally, when the users respond positively to SMS ads, the ads can be highly effective in triggering a purchase. Theoretical and practical implications of these findings are discussed.