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协同过滤算法作为推荐系统中应用最广泛的算法之一,在大数据环境下面临严重的数据稀疏问题,使得近邻选择的效果不佳,直接影响了算法的推荐性能.为了解决这一问题,本文提出了一种基于用户部分特征的协同过滤算法(UPCF),该算法首先基于评分偏差和项目流行度进行矩阵缺失值填充,随后利用初始聚类中心优化的K-means算法对该填充矩阵进行项目聚类,并利用用户在项目分类下的局部特征进行近邻集合构建,最终采用基于用户的协同过滤算法获得推荐.我们采用流行的MAE指标对算法在MovieLens数据集上进行评测.实验表明,与目前流行的协同过滤算法相比,提出的UPCF算法在没有增加算法复杂性的前提下,性能有近10%的提升. 相似文献
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序列数据一类重要的数据类型,在文本、Web访问日志文件、生物数据库等应用中普遍存在,对其进行相似性查询是一种获取有用信息的重要手段.在大型序列数据库中进行高效相似性查询的关键因素之一就是查询算法的过滤能力,即设计能快速过滤与查询序列不相关序列集的过滤器十分重要.提出了结合序列距离的度量性质和序列自身特征的多重过滤算法SSQ_MF,SSQ_MF使用了长度过滤器、前缀过滤器和基于参考集的过滤器,使得算法过滤能力较基于单一过滤器算法进一步增强.此外,设计了有关数据结构对查询数据库的一些统计信息进行了预计算和保存,有效估计了各过滤器的过滤集大小,并构建了一个由过滤集大小确定的最优过滤顺序模型,使得算法的过滤代价最低.实验结果表明,算法SSQ_MF的查询性能优于单一过滤器算法和随机过滤顺序的多过滤器算法. 相似文献
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近似串匹配是生物信息学、文本检索、信号处理等领域的一个基础问题,如何提高近似串匹配的速度一直都是研究的关键问题。提出一种新的在大文本库中快速查找近似匹配的无损过滤算法。为保证在大文本库中的匹配速度,本算法使用了查询速度较快的q-gram索引。为通过提高过滤算法的过滤效率达到提升算法整体性能的目的,详细分析了含有匹配串的文本区域,提取了一些基于尾匹配q-gram特征的新过滤条件,然后用这些特征优化了过滤算法的过滤标准。实验数据表明,新过滤条件有效地提高了算法的过滤效率,提升了算法的整体性能。结果显示新算法适合各种匹配错误率下的近似匹配,算法的通用性较强。 相似文献
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为了解决协同过滤推荐系统中所存在的可扩展性、稀疏性和冷启动等问题带来的推荐性能底下,提出新的基于领域本体的协同过滤推荐算法,该算法综合考虑了项目的语义相似性和评分相似性的影响,改善基于项目的协同过滤算法性能。实验结果表明,基于领域本体的协同过滤算法不仅能很好的解决基于项目的协同过滤算法带来的问题,而且还提高了推荐系统的推荐质量。 相似文献
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为了解决稀疏性问题和可扩展性问题,提高推荐的质量,在传统协同过滤算法的基础上,引入产品分类技术与Web使用挖掘技术.在详细阐述算法的基础上,通过实验数据验证该算法的推荐性能.实验结果表明,引入产品分类和Web使用挖掘技术后,协同过滤算法的性能有了显著的提高,很好地改善了其稀疏性问题和可扩展性问题. 相似文献
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提出一种基于新闻时效性的协同过滤推荐算法. 首先对新闻的时效性进行了特征分析, 建立了新闻时效性模型, 然后结合新闻时效性改进了基于用户的协同过滤算法. 最后进行了仿真实验, 实验结果表明, 该方法可以有效提高推荐算法的性能, 改善新闻推荐准确度和召回率. 相似文献
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并行工程环境下设计任务调度原理与实现方法的研究 总被引:16,自引:0,他引:16
并行工程CE环境下,设计任务被分解为若干子任务,然后进行协同求解,因此各子任务的调度是实现产 品并行设计的关键.该文提出了设计任务调度的“均衡一适度”法,分析了其调度策略,研究了其算法实现,最后给出 了应用实例。 相似文献
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A better understanding of high rate anodic dissolution processes is urgently required for electrochemical micromachining (EMM) to become a widely employed manufacturing process in the electronic and precision manufacturing industries particularly in the micromanufacturing domain. A successful attempt has been made to develop an EMM setup for carrying out in depth independent research for achieving satisfactory control of electrochemical machining process parameters to meet the micromachining requirements. The developed EMM setup mainly consists of various sub-components and systems, e.g., mechanical machining unit, microtooling system, electrical power and controlling system and controlled electrolyte flow system, etc. All these system components are integrated in such a way that the developed EMM system setup will be capable of performing basic and fundamental research in the area of EMM fulfilling the requirements of micromachining objectives. 相似文献
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Expanding a multilingual media monitoring and information extraction tool to a new language: Swahili
Ralf Steinberger Sylvia Ombuya Mijail Kabadjov Bruno Pouliquen Leo Della Rocca Jenya Belyaeva Monica de Paola Camelia Ignat Erik van der Goot 《Language Resources and Evaluation》2011,45(3):311-330
The Europe Media Monitor (EMM) family of applications is a set of multilingual tools that gather, cluster and classify news in currently fifty languages and that extract named entities and quotations (reported speech) from twenty languages. In this paper, we describe the recent effort of adding the African Bantu language Swahili to EMM. EMM is designed in an entirely modular way, allowing plugging in a new language by providing the language-specific resources for that language. We thus describe the type of language-specific resources needed, the effort involved, and ways of boot-strapping the generation of these resources in order to keep the effort of adding a new language to a minimum. The text analysis applications pursued in our efforts include clustering, classification, recognition and disambiguation of named entities (persons, organisations and locations), recognition and normalisation of date expressions, as well as the identification of reported speech quotations by and about people. 相似文献
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Exceptional Model Mining strives to find coherent subgroups of the dataset where multiple target attributes interact in an unusual way. One instance of such an investigated form of interaction is Pearson’s correlation coefficient between two targets. EMM then finds subgroups with an exceptionally linear relation between the targets. In this paper, we enrich the EMM toolbox by developing the more general rank correlation model class. We find subgroups with an exceptionally monotone relation between the targets. Apart from catering for this richer set of relations, the rank correlation model class does not necessarily require the assumption of target normality, which is implicitly invoked in the Pearson’s correlation model class. Furthermore, it is less sensitive to outliers. We provide pseudocode for the employed algorithm and analyze its computational complexity, and experimentally illustrate what the rank correlation model class for EMM can find for you on six datasets from an eclectic variety of domains. 相似文献
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基于Epanechnikov混合模型提出了一种新的模糊模型——具有多维隶属度函数的规则中心化模糊模型.它容易设计:任何一个Epanechnikov混合模型都唯一对应着一个规则中心化的模糊模型,Epanechnikov混合模型的条件期望输出是规则中心化的模糊模型的去模糊化输出;它具有高度的可解释性:其规则后件恰好是其输出在规则中心的一阶Taylor级数展开;它采用了多维隶属度函数,考虑了输入数据各个分量之间的相关性,更符合实际问题.对两个典型实例的仿真实验表明,由Epanechnikov混合模型设计的规则中心化的模糊模型比其他模糊模型速度快、精度高、鲁棒性好. 相似文献
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In this paper, we analyse physicians’ and nurses’ practices of prescribing and administering medication through the use of
paper-based, and digitalized medication plans. Our point of departure is an ethnographic study of the implications of upgrading
an electronic medication module (EMM) that is part of an electronic health record (EHR), carried out at an endocrinology department.
The upgrade led to a temporary breakdown of the EMM, and a return to paper-based medication plans. The breakdown made visible
and noticeable the taken-for-granted capabilities of medication plans in their paper-based and digital versions, and the distribution
of functionalities between medication plans and clinicians. We see the case as an opportunity to analyse infrastructuring
in health care, the process by which medical practices and artefacts become parts of social and technological networks with
longer reaches and more channels through which coordination among distributed actors is enabled and formed. In this case,
infrastructuring means an extended scope and intensity of the coordinative capabilities of medication plans, and an increased
vulnerability to, and dependency on events outside the immediate loci of interaction. We particularly note the capacity of
the EMM to facilitate different kinds of ordering of information and practices, and propose the conceptualizing of such digitalized
artefacts as ‘ordering devices’. Ordering devices order information, stipulate action, and coordinate interaction across and
within social worlds, and achieve this through the flexible support of different kinds of ordering. 相似文献
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文中讨论了80286以上微机扩充内存的管理及使用方法,并通过对EMM386正EXEE的调用,实现了多幅图象的快速存储. 相似文献
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采用遗传算法和蚁群算法相结合的融合算法,继承了遗传算法和蚁群算法的优点,在求精解效率上优于遗传算法,在时间效率上优于蚁群算法,能很好地实现多约束条件的最优路径计算,测试证明融合算法优化性能和时间性能都取得了很好的效果。 相似文献