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将传统分类方法和加入地理控制界线分类方法进行比较,后者分类精度为94.73%,比传统分类方法提高了近3个百分点。这种方法对于解决卫星遥感中的同谱异类问题,提高分类精度,有较重要的意义和作用。本文以乌鲁木齐市为例,主要研究了同谱异类问题。 相似文献
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文本提出了一种基于模糊向量空间模型和径向基函数网络的分类方法。该方法在特征提取时充分考虑了特征项在文档中的位置信息,构造出模糊特征向量,使自动分类更接近手工分类方法。以中国期刊网全文数据库部分文档数据为例验证了该方法的有效性。 相似文献
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随着网络的飞速发展,网页数量急剧膨胀,近几年来更是以指数级进行增长,搜索引擎面临的挑战越来越严峻,很难从海量的网页中准确快捷地找到符合用户需求的网页。网页分类是解决这个问题的有效手段之一,基于网页主题分类和基于网页体裁分类是网页分类的两大主流,二者有效地提高了搜索引擎的检索效率。网页体裁分类是指按照网页的表现形式及其用途对网页进行分类。介绍了网页体裁的定义,网页体裁分类研究常用的分类特征,并且介绍了几种常用特征筛选方法、分类模型以及分类器的评估方法,为研究者提供了对网页体裁分类的概要性了解。 相似文献
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为了遥感解译基础性工作的发展和提高,本文综述了近年来国内外多种分类方法的研究和进展。在分析当前主要遥感影像分类方法的基础上。从传统的分类方法、基于智能的分类方法、其他新分类方法三个方面,对遥感分类方法研究进展进行了阐述,本研究还存在不足,今后还需进一步研究利用各种分类方法相互结合在盖遥感影像分类中的应用。 相似文献
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基于模糊向量空间的文本分类方法 总被引：1，自引：0，他引：1
本文针对文本自动分类问题，提出了一种基于模糊向量空间模型和径向基函数网络的分类方法。网络由输入层、隐层和输出层组成。输入层完成分类样本的输入，隐层提取输入样本所隐含的模式特征，将分类结果在输出层表现出来。该方法在特征提取时充分考虑了特征项在文档中的位置信息，构造出模糊特征向量，使自动分类更接近手工分类方法。以中国期刊网全文数据库部分文档数据为例验证了该方法的有效性。 相似文献
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自动文本分类方法是文本分类中非常重要的一种分类方法，本文着重从模型与方法的角度进行探讨。首先给出了一个自动文本分类的形式化定义，然后提出了自动文本分类的流程模型。接着，对流程中的四个部分进行具体讨论。自动文本分类的应用非常广泛，为了叙述方便，以商务数据为例进行讨论，并且选择实例作为典型案例对自动文本分类后的可视化进行分析和具体研究。 相似文献
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针对信息挖掘中的网页自动分类问题,提出了一种基于向量空间模型和并联BP网络的分类方法。该网络由并行连接的多个子网络组成,每个子网络负责一类模式特征的提取,多个子网并行处理所有模式,将分类结果在总输出层表现出来。以因特网上旅游网页分类为例验证了该方法的有效性。 相似文献
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澜沧江流域山区土地覆盖遥感监测分类组织与实施技术研究 总被引：3，自引：0，他引：3
对澜沧江流域山区典型试验样区遥感数据运用AHP递阶层次结构,将土地覆盖类别分成若干层次。结合特征选取与采用多种分类算法组合,先进行类间易于区别的大类别的分类信息提取处理,得到一层次的分类结果,再基此对各分类结果探索进一步的分类处理,获得第二层次的分类结果。如此进行,直至分出所有确定类别。试验结果表明,该分类组织较之传统基于一次特征选取所进行的单级分类技术组织实施,具有构思科学合理,操作简单可行。监测结果评价精度可满足澜沧江流域综合开发,达到获取反映山地生态主要覆盖类别的遥感监测技术要求。 相似文献
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"新浪爱问"和"百度知道"这类问答服务系统的主要任务之一是对问题进行分类,以便于组织用户产生的问题数据,并进行进一步的分析处理。问答服务系统的实际应用需求对问题分类算法在分类效果、计算复杂度以及对噪声数据敏感度等方面提出了较高的要求。基于信息检索思想,本文提出一种基于类文档排名的分类算法,并从语言模型的角度对该算法进行分析和改进。通过在一个大尺度的问题数据集合进行的一系列实验,表明本文提出的算法在问题分类任务中可以取得优于传统算法的分类效果;同时,该算法计算量较小,适用于处理大规模数据,可以很好的满足问答服务系统中对于问题分类算法的要求。 相似文献
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I propose an alternative approach to industry classification that reflects the way in which firms self-organize into industries and sectors. The systems-based approach to industry classification takes the sector as the primary unit of analysis, defines a sector on the basis of similarity in needs to which firms collectively respond, and disaggregates sectors into subsectors and industries on the basis of recursive hierarchical dependency. The result is an approach to industry classification that reflects industry structure, reduces egregious cases of between-class homogeneity and within-class heterogeneity, and accommodates changes in technology. The approach is illustrated in a communications equipment subsector application. 相似文献
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Text categorization is an important research area and has been receiving much attention due to the growth of the on-line information and of Internet. Automated text categorization is generally cast as a multi-class classification problem. Much of previous work focused on binary document classification problems. Support vector machines (SVMs) excel in binary classification, but the elegant theory behind large-margin hyperplane cannot be easily extended to multi-class text classification. In addition, the training time and scaling are also important concerns. On the other hand, other techniques naturally extensible to handle multi-class classification are generally not as accurate as SVM. This paper presents a simple and efficient solution to multi-class text categorization. Classification problems are first formulated as optimization via discriminant analysis. Text categorization is then cast as the problem of finding coordinate transformations that reflects the inherent similarity from the data. While most of the previous approaches decompose a multi-class classification problem into multiple independent binary classification tasks, the proposed approach enables direct multi-class classification. By using generalized singular value decomposition (GSVD), a coordinate transformation that reflects the inherent class structure indicated by the generalized singular values is identified. Extensive experiments demonstrate the efficiency and effectiveness of the proposed approach. 相似文献
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《Information processing & management》2020,57(1):102132
The research field of crisis informatics examines, amongst others, the potentials and barriers of social media use during disasters and emergencies. Social media allow emergency services to receive valuable information (e.g., eyewitness reports, pictures, or videos) from social media. However, the vast amount of data generated during large-scale incidents can lead to issue of information overload. Research indicates that supervised machine learning techniques are suitable for identifying relevant messages and filter out irrelevant messages, thus mitigating information overload. Still, they require a considerable amount of labeled data, clear criteria for relevance classification, a usable interface to facilitate the labeling process and a mechanism to rapidly deploy retrained classifiers. To overcome these issues, we present (1) a system for social media monitoring, analysis and relevance classification, (2) abstract and precise criteria for relevance classification in social media during disasters and emergencies, (3) the evaluation of a well-performing Random Forest algorithm for relevance classification incorporating metadata from social media into a batch learning approach (e.g., 91.28%/89.19% accuracy, 98.3%/89.6% precision and 80.4%/87.5% recall with a fast training time with feature subset selection on the European floods/BASF SE incident datasets), as well as (4) an approach and preliminary evaluation for relevance classification including active, incremental and online learning to reduce the amount of required labeled data and to correct misclassifications of the algorithm by feedback classification. Using the latter approach, we achieved a well-performing classifier based on the European floods dataset by only requiring a quarter of labeled data compared to the traditional batch learning approach. Despite a lesser effect on the BASF SE incident dataset, still a substantial improvement could be determined. 相似文献
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Due to a large variety of noisy information embedded in Web pages, Web-page classification is much more difficult than pure-text classification. In this paper, we propose to improve the Web-page classification performance by removing the noise through summarization techniques. We first give empirical evidence that ideal Web-page summaries generated by human editors can indeed improve the performance of Web-page classification algorithms. We then put forward a new Web-page summarization algorithm based on Web-page layout and evaluate it along with several other state-of-the-art text summarization algorithms on the LookSmart Web directory. Experimental results show that the classification algorithms (NB or SVM) augmented by any summarization approach can achieve an improvement by more than 5.0% as compared to pure-text-based classification algorithms. We further introduce an ensemble method to combine the different summarization algorithms. The ensemble summarization method achieves more than 12.0% improvement over pure-text based methods. 相似文献
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《Information processing & management》2005,41(2):313-330
The paper proposes a new approach to create a patent classification system to replace the IPC or UPC system for conducting patent analysis and management. The new approach is based on co-citation analysis of bibliometrics. The traditional approach for management of patents, which is based on either the IPC or UPC, is too general to meet the needs of specific industries. In addition, some patents are placed in incorrect categories, making it difficult for enterprises to carry out R&D planning, technology positioning, patent strategy-making and technology forecasting. Therefore, it is essential to develop a patent classification system that is adaptive to the characteristics of a specific industry. The analysis of this approach is divided into three phases. Phase I selects appropriate databases to conduct patent searches according to the subject and objective of this study and then select basic patents. Phase II uses the co-cited frequency of the basic patent pairs to assess their similarity. Phase III uses factor analysis to establish a classification system and assess the efficiency of the proposed approach. The main contribution of this approach is to develop a patent classification system based on patent similarities to assist patent manager in understanding the basic patents for a specific industry, the relationships among categories of technologies and the evolution of a technology category. 相似文献
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【目的/意义】文本情感分类是近年来情报学领域的研究热点之一。已有研究大多关注针对目标文本的单
一情感分类。本文旨在探索基于深度学习的电商评论信息多刻面情感分类方法。【方法/过程】提出一种基于Atten⁃
tion-BiGRU-CNN的多刻面情感分类模型,通过BiGRU和CNN获取上下文信息和局部特征,利用Attention机制
优化隐层权重,以深度挖掘文本内隐语义和有效刻画多刻面情感。【结果/结论】在中文电商评论信息语料上的实验
表明,相较于其他神经网络模型,本文方法可有效提高多刻面情感分类的准确度。【创新/局限】进一步丰富多刻面
情感分类的方法途径,为深度挖掘电商评论信息以及优化产品和营销策略提供参考。本文语料主要基于单一类别
电商评论信息,聚焦可归纳刻面的情感分类,进一步的研究可面向类别多元化、需通过深度学习提取刻面信息的更
大规模语料展开。 相似文献
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《Information processing & management》2023,60(2):103225
Deep Learning has reached human-level performance in several medical tasks including classification of histopathological images. Continuous effort has been made at finding effective strategies to interpret these types of models, among them saliency maps, which depict the weights of the pixels on the classification as an heatmap of intensity values, have been by far the most used for image classification. However, there is a lack of tools for the systematic evaluation of saliency maps, and existing works introduce non-natural noise such as random or uniform values. To address this issue, we propose an approach to evaluate the faithfulness of the saliency maps by introducing natural perturbations in the image, based on oppose-class substitution, and studying their impact on evaluation metrics adapted from saliency models. We validate the proposed approach on a breast cancer metastases detection dataset PatchCamelyon with 327,680 patches of histopathological images of sentinel lymph node sections. Results show that GradCAM, Guided-GradCAM and gradient-based saliency map methods are sensitive to natural perturbations and correlate to the presence of tumor evidence in the image. Overall, this approach proves to be a solution for the validation of saliency map methods without introducing confounding variables and shows potential for application on other medical imaging tasks. 相似文献