How does Internet information seeking help academic performance? – The moderating and mediating roles of academic self-efficacy

Although researchers tend to agree that Internet is a good source for learning and research, little empirical data has substantiated this claim by specifically linking time and effort spent on the Internet for school related information seeking to academic performances. This research investigates the relationship between vocational high school students’ information seeking activities on the Internet, academic self-efficacy, and academic performance. We propose that academic self-efficacy both mediates and moderates the relationship between Internet information seeking and academic performance. Using survey data from 295 vocational high school students in Taiwan, we found that the positive effect of Internet information seeking to students’ academic performance is mediated through academic self-efficacy. Academic self-efficacy, at the same time, moderates the relationship between Internet information seeking to academic performance such that students’ with low academic self-efficacy benefit more from Internet information seeking in regard to their academic performance. We discussed the implications of our findings and provided future directions for research.     

High sensitive and selective formaldehyde sensors based on nanoparticle-assembled ZnO micro-octahedrons synthesized by homogeneous precipitation method

Nanoparticle-assembled ZnO micro-octahedrons were synthesized by a facile homogeneous precipitation method. The ZnO micro-octahedrons are hexagonal wurtzite with high crystallinity. Abundant structure defects were confirmed on ZnO surface by photoluminescence. Gas sensors based on the ZnO micro-octahedrons exhibited high response, selectivity and stability to 1–1000 ppm formaldehyde at 400 °C. Especially, even 1 ppm formaldehyde could be detected with high response (S = 22.7). It is of interest to point out that formaldehyde could be easily distinguished from ethanol or acetaldehyde with a selectivity of about 3. The high formaldehyde response is mainly attributed to the synergistic effect of high contents of electron donor defects (Zn_i and V_O) and highly active oxygen species (O²⁻) on the ZnO surface.     

Study of land cover classification based on knowledge rules using high-resolution remote sensing images

This paper deals with the limitations of visual interpretation of high-resolution remote sensing images and of automatic computer classification completely dependent on spectral data. A knowledge-rule method is proposed, based on spectral features, texture features obtained from the gray-level co-occurrence matrix, and shape features. QuickBird remote sensing data were used for an experimental study of land-use classification in the combination zone between urban and suburban areas in Beijing. The results show that the deficiencies of methods where only spectral data are used for classification can be eliminated, the problem of similar spectra in multispectral images can be effectively solved for the classification of ground objects, and relatively high classification accuracy can be reached.     

基于维基百科的未登录词译文挖掘

未登录词(out of vocabulary,OOV)的查询翻译是影响跨语言信息检索(cross-language information retrieval,CLIR)性能的关键因素之一.它根据维基百科(Wikipedia)的数据结构和语言特性,将译文环境划分为目标存在环境和目标缺失环境.针对目标缺失环境下的译文挖掘难点,它采用频度变化信息和邻接信息实现候选单元抽取,并建立基于频度-距离模型、表层匹配模板和摘要得分模型的混合译文挖掘策略.实验将基于搜索引擎的未登录词挖掘技术作为baseline,并采用TOP1进行评测.实验验证基于维基百科的混合译文挖掘方法可达到0.6822的译文正确率,相对baseline取得6.98%的改进.     

H.264帧内预测模式选择快速算法的研究

提出一种适用于H.264帧内预测的快速算法,利用相邻像素间的梯度筛选预测模式来避免不必要的预测模式计算。实验结果表明:用全I帧编码,该算法在图像质量和输出码率基本不变的情况下,编码时间大约节省了60%。     

一种面向主题的关键词查询扩展方法

提出一种基于局部统计和语义扩展相结合,面向主题的关键词查询扩展方法。该方法通过对给定主题的初始关键词搜索反馈网页进行分析,采用TF*PSF语义加权方法计算主题候选词的权重来进一步筛选主题关键词。在此基础上,设计了面向Web的主题关键词迭代查询扩展算法,采用主题关键词的组合查询策略,迭代扩展出主题的关键词集合。实验证明该方法是有效的。     

基于SNMP的校园网ARP攻击检测方法研究

防范地址解析协议ARP(Address Resolution Protocol)欺骗攻击的难点是:攻击源可以隐藏在网段内任何一个主机中,即使发现了攻击的存在,也难以迅速定位攻击源。结合校园网络的特点,提出了一种新的ARP攻击检测方案:检测服务器通过SNMP协议定期读取核心交换机的ARP、VLAN等信息和接入交换机的MAC-PORT信息,利用综合检测算法,及时发现攻击现象,迅速定位攻击源,并根据网络实际情况采用不同的技术措施进行处理。实践证明,该方法能够有效保障校园网络安全。     

Improvement of Machine Translation Evaluation by Simple Linguistically Motivated Features

Adopting the regression SVM framework, this paper proposes a linguistically motivated feature engineering strategy to develop an MT evaluation metric with a better correlation with human assessments. In contrast to current practices of “greedy” combination of all available features, six features are suggested according to the human intuition for translation quality. Then the contribution of linguistic features is examined and analyzed via a hill-climbing strategy. Experiments indicate that, compared to either the SVM-ranking model or the previous attempts on exhaustive linguistic features, the regression SVM model with six linguistic information based features generalizes across different datasets better, and augmenting these linguistic features with proper non-linguistic metrics can achieve additional improvements.     

A 1-Local Asymptotic 13/9-Competitive Algorithm for Multicoloring Hexagonal Graphs

In the frequency allocation problem, we are given a mobile telephone network, whose geographical coverage area is divided into cells, wherein phone calls are serviced by assigning frequencies to them so that no two calls emanating from the same or neighboring cells are assigned the same frequency. The problem is to use the frequencies efficiently, i.e., minimize the span of frequencies used. The frequency allocation problem can be regarded as a multicoloring problem on a weighted hexagonal graph. In this paper, we give a 1-local asymptotic 4/3-competitive distributed algorithm for multicoloring a triangle-free hexagonal graph, which is a special case of hexagonal graph. Based on this result, we then propose a 1-local asymptotic13/9-competitive algorithm for multicoloring the (general-case) hexagonal graph, thereby improving the previous 1-local 3/2-competitive algorithm. A preliminary version of this paper appeared in the Proceedings of the 13th Annual International Computing and Combinatorics Conference (COCOON 2007), LNCS 4598, pp. 526–536. Y. Zhang research was supported by European Regional Development Fund (ERDF). F.Y.L. Chin research was supported by Hong Kong RGC Grant HKU-7113/07E. H. Zhu research was supported by National Natural Science Fund (grant #60496321).