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[目的/意义]利用动态结构熵探究颠覆性技术知识网络扩散过程中的结构变化并识别网络结构变化过程中的突变状态，以此发现颠覆性技术知识网络扩散特征，为颠覆性技术的早期识别提供方法借鉴。[方法/过程]首先，构建颠覆性技术在基础研究、应用研究、产业应用创新过程环节中的3种动态知识子网络；其次，利用动态结构熵探究颠覆性技术知识网络扩散特征；之后，通过突变函数模型分析颠覆性技术知识网络扩散过程中的结构突变特征；最后，利用动态时间规整法探析颠覆性技术各知识子网络间扩散的相关性及其与渐进性技术扩散特征的差异性。[结果/结论 ]实证研究表明利用提出的动态结构熵开展颠覆性技术知识网络扩散特征识别，能够发现颠覆性技术分别在基础研究、应用研究、产业应用知识子网络的微观结构、介观结构、微观与介观结构关系与网络结构突变等方面知识网络扩散特征，并通过3种网络扩散特征的综合分析，解析出颠覆性技术显著区别于渐进性技术的网络扩散特征。 相似文献
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在大数据时代的今天，如何从海量的社交媒体中寻找信息扩散的源头，并且预测信息扩散的未来走势，已成为人们非常关心的热点问题，这就为数据挖掘在热点问题上的应用提出了新的挑战。最具影响力信息的挖掘方法有静态与动态之分。静态方法只是针对某个时间点，有其片面性。动态方法常用的有四种，均有其局限性，用的是最广的独立级联模型与线性阈值模型均需要将激活过程放置在一个个离散的轮回中，是非连续的。自主研究了一个基于连续时间马科夫过程的模型来模拟现实世界的信息扩散，并根据每个节点扩散信息的情况来预测它们在未来的信息扩散能力，从而达到判断未来走势的目的。 相似文献
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[目的/意义]调研分析国外图像特征研究的进展与发现,总结图像特征体系的特点以及相关用户使用行为,为改进和优化图像标引和检索提供参考借鉴。[方法/过程]系统回顾国外图像特征的相关研究,分析现有图像描述和著录规范、图像特征的分类与分层研究以及标引与检索情境下用户对图像特征的使用行为及影响因素等研究。[结果/结论]国外图像特征研究内容较为全面和系统,研究视角涵盖以图像为中心和以用户为中心,研究方法涉及日志研究和调查研究,研究对象有普通用户和专业人员,研究发现,图像类型、用户视觉经验、专业知识背景、任务类型、检索阶段等因素与图像特征使用行为有关。未来可在面向非专业用户的图像特征体系构建以及图像特征使用等方面开展更多研究。 相似文献
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文献计量法与内容分析法综合研究的关键是能否明确研究对象与分析单元、设计合理的方法体系和有效的方法应用流程.本文以文本信息为主论证了综合研究的分析对象和分析单元,阐述文本信息中可计量的分析单元的含义和不同分析单元组配的形式;分别设计从文献计量法出发的综合方法和从内容分析法出发的综合方法(SMoBC);最后,提出以特征单元、时空分布、内容层次为坐标的三维综合方法(SMoBC)的体系架构,将外部特征与内容特征、定量分析与定性分析、空间分析与时间分析等有机地综合在一起,构建三维SMoBC的基本流程,分析三维SMoBC的用途. 相似文献
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[目的/意义] 基于社交媒体,探索突发事件信息生命周期中不同利益相关者的动态分类及其关注主题的演变规律,为更精准的危机信息监测与动态决策提供依据。[方法/过程] 以特定危机事件的事实文本数据为来源,以利益相关者理论和动态主题模型为指导,构建三维动态主题演化模型以对社交媒体危机事件中不同利益相关者的分类与话题关注进行主题挖掘。其中包括时间粒度划分、利益相关者的定量评估、基于时间和主体的危机主题观点识别与刻画,并利用可视化工具对该动态趋势进行表征。[结果/结论] 基于三维动态主题演化模型,利益相关者的组成与分类在不同阶段中具有明显的差异性,同时其关注主题与行为特征也体现出不同的偏好性和动态差异性。危机主体的动态与危机主题的动态有效结合,能够更加全面地表达舆情传播的特点和规律。 相似文献
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[目的/意义]时间是信息行为中普遍存在的情境因素,然而将时间视为稀缺资源,探讨其对信息行为影响的研究较为零散。本研究梳理信息行为领域中对时间限制和时间压力影响的相关研究,总结时间限制与时间压力对信息行为的作用和影响,以加深对时间因素的理解,呼吁信息行为领域对时间的关注。[方法/过程]在阅读与筛选近10年相关领域研究的基础上,本研究系统性归纳与总结时间限制与时间压力对信息行为的影响,着重梳理时间限制与时间压力在不同类型的信息行为过程中的角色。[结果/结论]研究发现,时间限制与时间压力会对任务完成过程中的信息行为(包括搜索、浏览与撰写行为)、无明确任务下的信息偶遇行为和信息决策行为均产生影响。未来研究者应厘清时间限制、时间压力及其相关概念边界,明确时间压力测量标准,同时关注时间压力积极作用。 相似文献
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基于二元混合热力学原理,计算了二元磁性混合体系的自由能,并应用平均场理论中的Bragg-Williams理论,分析讨论了等组分体系的相变和相图。结果表明:1)不考虑摇摆(Staggered)效应,二元磁性混合体系存在二阶相变。2)考虑摇摆效应时,等组分二元磁性混合体系在不同类粒子间相互作用强度与同类粒子间相互作用强度J2/J1较小时,存在二阶相变。 相似文献
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在传受双方互动的传播过程中,辨听是一种多维度的动态接收行为.针对时空维度辨听的复杂性,按照维度划分方法,本文就口语传播时间维度辨听的过程与结果、空间维度辨听对象的能动特征和时空维度辨听面临的并置元素三方面进行研究,并提出了多维度辨听的接收方法. 相似文献
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从文本特征对文本分类结果的整体影响的角度出发,提出一种基于粒子群优化的文本特征选择方法(PSOTFS),使用粒子群算法来挖掘文本特征选择规则。PSOTFS首先使用开方检验对文本特征进行预选择,然后使用粒子群算法对预选择得到的文本特征进行精选。PSOTFS以一个粒子表示一条特征选择规则,特征选择规则集对应某个粒子群,采用分类准确率作为适应度函数,采用分组的方式对粒子的维度进行降维。实验结果表明,PSOTFS比开方检验、信息增益、文档频率和互信息方法能得到更好的分类效果。 相似文献
10.
李延瑞 《福建广播电视大学学报》2000,(4)
词汇是一个开放性的、处于不断调整变化中的动态系统。这种调整变化即使在其最核心的部分——基本词汇中也清晰可见。本文概括分析了汉语词汇系统随着社会发展调整变化的主要表现,并对词汇教学在把握词汇系统这一特征基础上,如何运用比较方法从纵横两方面考察其成员的古今流变及与左邻右舍关系等问题作了初步探讨。 相似文献
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This case study analyzed Twitter posts from the #JusticeForBradsWife campaign against the Cracker Barrel (CB) restaurant chain. Participants in the counterinstitutional movement employed diverse message strategies of humor and resistance in using social media as a site for discourse. Thematic analysis of the most influential users revealed humor strategies including: connecting to popular culture, political comic relief and using hyperbole. Participants’ resistance strategies included: making calls for action, critiquing CB products and business partners, attacking CB patrons, critiquing CB’s social media management, and offers of support from outside organizations. These strategies reflected collective trolling, where trolling behaviors created a hidden and public hybrid form of collective resistance from nontraditional stakeholders who had contradictory goals. Implications and directions for future research are discussed. 相似文献
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Jeremy Packer 《The Communication Review》2013,16(1):39-57
Struggles over CB radio use in the 1970s provide a unique historical precedent for conceptualizing current mobile communication technologies. Battles between truckers and the police were popularized in several movies, television shows, and the most memorably hit songs of the period. This essay approaches these texts as a popular how-to manual for the use of CB and compares them with the more utopian visions of CB use being spread by CB guidebooks and government officials from local police forces to the FCC. These two types of DB use came into direct conflict during the Wildcat Truckers Blockades of 1973 and 1974 that was organized via CB which spawned the popular culture representations of the truckers as American hero. This political protest made unique use of the mobile quality of CB and allowed for the unification of otherwise disparate loners which could provide a model for quick acting group resistance 相似文献
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目前科技期刊中误用“浓度”的现象十分常见.通过实例对常见的误用“浓度”现象进行分析,纠正其中的错误.认为科技期刊中在定量表达某组分的含量时,应正确使用质量分数、体积分数、摩尔分数、质量浓度、浓度、质量摩尔浓度等标准化量名称. 相似文献
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Italian soccer clubs in the first division have individually sold broadcasting rights for their home matches, until new laws imposed pooling and joint-selling those rights through the league and established a mandatory sharing rule to redistribute revenues in order to improve on-the-pitch competitive balance (CB). This article compares the two institutional designs. While reducing revenue inequality, the new regime distorts allocative efficiency and informational rent appropriation, opens up costly ex post renegotiations and antitrust litigations, and does not improve CB. 相似文献
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针对地学期刊论文不当使用"含量"一词而产生含义多解和误解的问题,列举实例进行分析,纠正了其中的错误,给出了使用"含量"一词定性描述与用质量分数、体积分数、质量浓度、量浓度、质量摩尔浓度等标准化量名称定量表述的原则,旨在引导作者和编辑正确、规范地表征物质的含量。 相似文献
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Salt crystallization is recognized as a major cause of damage to porous building materials, threatening the sustainable preservation of our valuable built heritage. Unfortunately, the crystallization behavior of the detected salt mixtures is complex and not fully understood. While the deliquescence points of single salts are well documented, this is not the case for salts in a mixture where one is confronted with the presence of different cations and anions. In this paper the salt content of the murals and the limestone tracery of the main entrance porch from the sixteenth century church of St. James in Liège, Belgium is investigated and related to the climatic conditions of its environment. Concerning the salt load, the research consists of hygroscopic moisture content measurements, quantitative ion analyses, and the prediction of phase equilibria using the thermodynamic model ECOS/RUNSALT. This model can predict the salt crystallization sequences of a particular ion mixture. The output is mathematically evaluated with collected temperature and relative humidity data, which enables the calculation of the number of salt crystallization–deliquescence cycles. The results show that even small amounts of salts can cause damage over a long period of time when the environment causes frequent cycles of crystallization–deliquescence over time. It is shown how a mixture of small amounts of (double) salts, including hygroscopic ones, can have a significant effect on the decay of historic building materials in the case of daily changing climatic conditions and periods of extreme drought. As a result, the crystallization of double salts and hygroscopic salts such as calcium nitrate cannot be ignored. The scientific method and the results are described. 相似文献
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The Freedom of Information Act (FOIA) has facilitated the release of large amounts of government information that has been of great value to researchers, journalists, and other interested parties. The fraction of this information released in electronic format has been growing as has its volume. While offering great potential for research, large amounts of data disgorged from government information systems can pose challenges to human interpretation and knowledge extraction. Using the Office of the Secretary of Defense/Joint Staff Freedom of Information Act (FOIA) Logs for 2007–2009, this research identifies (1) a process for finding relationships between the FOIA requests through keywords extracted from Wikipedia and (2) a technique for visualizing these relationships in order to provide context and improve understanding when working with born-digital government data. 相似文献
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This article presents the Δ-distance, a family of distances between images recursively decomposed into segments and represented by multi-level feature vectors. Such a structure is a quad, a quin or a nona-tree resulting from a fixed and arbitrary image partition or from an image segmentation process. It handles positional information of image features (e.g. color, texture or shape). Δ-distance is the generalized form of dissimilarity measures between multi-level feature vectors. Using different weights on tree nodes and different distances between nodes, distances between trees or visual similarity between images can be computed based on the general definition of Δ. In this article, we present three Δ-based distance families: two families of distances between tree structures, called
-distance( for Tree) and
-distance ( for Segment), and a family of visual distances between images, called ( for Visual). The -distance visually compares two images using their tree representation and the other two distances compare the tree structures resulting from image segmentation. Moreover, we show how existing distances between multi-level feature vectors appear to be particular cases of the Δ-distance 相似文献
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ABSTRACT Currently, there is a lack of research on the migration and distribution of soluble salt solutions in the pores of fragile silicate cultural relics, especially the thermodynamic changes during crystallization, and the forces causing the destruction of cultural relics. Thus, this paper used infrared thermal imaging analysis and extended depth-of-field microscopy to observe the changes in temperature, morphology, migration, and crystallization rate of Na2SO4 solution – the most typical solution that causes damages to cultural relics – in the crystallization process and in different capillary pores. The results show that the formation of soluble salt crystal nuclei and subsequent crystal growth mainly occurred in the liquid phase region below the ambient temperature, and then the salt crystals in the deliquescent state became more compact due to the attractive force generated from liquid-phase water evaporation. Additionally, three stages of migration and crystallization of the salt solution in different capillary pores were found. Large-area crystals appeared in the capillary pore with a large diameter, and bubbles were generated. This is likely because the surface tension of the Na2SO4 solution decreased with increasing concentration, and the solubility of the air dissolved at the solid–liquid interface of the mouth of the capillary pore and the pressure in the capillary pore decreased. A self-designed double-layer contact surface internal pressure method and extended depth-of-field microscopy were used to carry out real-time online observation of the force applied on the contact surface during the crystallization of the salt solution. It was found that the airflow determined the direction of capillary movement of the solution, and water migration determined the laminar flow in the capillary pore. Salt crystallization played a role in distortion and shape-fixation of pores. Small spikes in the mass indicated that the expansion–contraction force generated by the salt solution during the crystallization process was in a state of constant change, and the degree of expansion was always slightly more significant than the change caused by contraction. Expansion forces dominated the surface of the sample. In this paper, the change in crystallization and the forces of the soluble salt solution were analyzed. 相似文献