一种改进图像标注的新方法

社会媒体共享网站允许用户上传图片的同时,也鼓励用户对上传图片内容加以标注.不过要对网站中所有图片进行内容标注,将是一项非常费时的任务;而如对同一类型图片统一进行标注则会大大降低内容标注的准确性.因此,文中提出了一个内容标注的新方法.首先,采用仿射传播聚类算法,从同一类型图片中获取一组具有代表性的图像;然后,利用图像内容的视觉信息和语义信息,对能够表示代表性图像内容标签的相关值进行估计,并依据随机游走算法改进标签的相关值;最后,通过半监督学习方法自动为同一类型的其它图片分配标签.基于Flickr图片集的实验结果表明所提方案的有效性.     

反应物转动激发对F+H2→HF+H体系反应动力学的影响

利用高分辨的交叉分子束装置研究了F+H₂(v=0,j=0, 1)反应在碰撞能1.27 kcal/mol下的动力学行为, 获得了产物HF(v′=1,2,3)转动态分辨的微分散射截面．当反应物H₂ 处于不同转动量子态j=0和1时,产物HF(v′=2)的散射角分布都主要表现为后向散射,但HF(v′=2)的转动态布居与反应物的转动量子态密切相关,转动激发的H₂分子将产生转动“更热”的HF(v′=2) 产物．另外,对于HF(v′=3)产物通道,由于slow-down机理的影响,当H₂布居于j=0时前向散射表现更显著．     

拉曼激发激光诱导电子荧光流场测量系统中标记过程的研究

研制了一套拉曼激光发激光诱导电子荧光空气流场测速系统,利用Nd:YAG激光器的二次谐波及其抽运的氧气受激拉曼散射作为标记光源,以ArF准分子激光作为荧光再现光源,并用像增强CCD摄像机（ICCD）记录荧光图像,成功地获得了纯氧及空气中的标记线的荧光图像,并进行了氧气喷流速度测量的初步研究。     

神经网络与规则相结合的词类标注方法

词类标注是自然语言理解中的的一个关键问题，是句法分析和语义分析的基础．本文分析了汉语的多类词现象．提出了在基于神经网络的词类标注方法的基础上，根据汉语的语法结构增加了规则的排歧处理阶段，增加了上下文词类信息的处理能力．实验表明：在原有神经网络方法的基础上，利用规则的方法进行修正，可以提高词性标注的正确率．     

Synthesis of fluorous acetal derivatives of aldehydes and ketones

The formation of acetals (and ketals) from polyfluoroalkylated 1,3-alkanediols and aldehydes and ketones is demonstrated for the first time. Four sets of reaction conditions are examined and the degree of conversion is shown to depend upon reaction conditions and the structure of the carbonyl substrate. Excellent yields are obtained, and wherever possible, diastereomeric products are observed.     

植物分子生物学中的双元系统

现代植物分子生物学理论研究和实际应用,发展了许多双因子系统即双元系统,其中具有代表性的有双元载体系统和双元标签系统.双元载体系统的构建是基于T-DNA的转移机制,由两种质粒组成,一种为穿梭载体,另一种为辅助载体.双元标签系统是以Ac转座子和Ds转座子构建的.Ac/Ds转座系统在高等植物基因的识别、克隆和对植物发育过程的基因表达中广泛应用.     

协同标签系统的应用研究

协同标签系统在帮助用户管理标签的同时,也为用户的导航和检索提供了便利.本文在分析了协同标签系统现状的基础上,提出了一种建立分类标签树的算法,将混乱的标签进行整理,转换成为有序的、层次的、分类的标签树,使标签提供的信息能被用于检索、导航,使用户更好的协同组织管理和利用网上资源,最后对算法进行了测试.     

Empirical reconstruction of learning progressions based on teachers’ tagging of didactic metadata

In their enactment of the curriculum, teachers have a substantial role as instructional designers. Accordingly, any evaluation of the progression of students’ learning should first be concerned with the pedagogical intentions of the teacher. In this article we present a method for reconstructing teachers’ implicit and tacit considerations in their selection, sequencing and enactment of tasks. Two 11^th grade teachers tagged all of the tasks that comprised a 5-week learning progression. Tagging consisted of assigning values to prescribed categories of metadata. Visual representations of the metadata revealed patterns in the tagged progressions, and allowed the teachers to reflect upon these patterns. Both teachers, though guided by very different didactical considerations, validated that many of their explicit and implicit intentions were revealed in the representations of the progressions. Furthermore, both teachers had the opportunity to reflect on tacit aspects of their instructional design that they were not previously aware of.     

Flow tagging velocimetry in a superorbital expansion tube

Abstract. A non-intrusive laser-based method for direct velocity measurements has been demonstrated in a superorbital flow facility. The method is based upon laser enhanced ionisation velocimetry in which a tagged region is created by two step excitation of sodium and subsequent collisional ionisation. The achieved depletion of neutral atoms is then interrogated by planar laser induced fluorescence. The velocities were measured in the freestream at a superorbital condition yielding km/s. These results compare favourably with the measured shock speeds in the facility. Received 15 March 1999 / Accepted 2 March 2000     

基于德语语料库词性标注和统计方法的研究

建立了一种德语语料词性标注方法以及基于词性标注的统计方法．初步实验证明了上述方法对德语语料标注和标注后的语料进行单词、词类、短语结构和句子的统计是正确和有效的．