共查询到18条相似文献，搜索用时 187 毫秒
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为了弥补传统朴素贝叶斯分类器在实际应用中代价不敏感的缺点,基于最小风险准则构建朴素贝叶斯模型和树增强朴素贝叶斯网模型,通过预先设置损失矩阵,分类器可以区分各种误判情形产生的代价,利用1 000条德国信用卡样本数据进行实验。研究发现,在以损失最小为导向的用户信用评估方面,基于最小风险准则构建分类器产生的总损失更小,综合性能更好;在分类性能上,简单的朴素贝叶斯模型可与复杂的基于爬山算法建立的贝叶斯网络模型相媲美;从整体经济效益看,朴素贝叶斯模型更胜一筹。 相似文献
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软件需求风险评估是软件开发成败的关键。本文探讨了基于贝叶斯网络的软件系统需求风险评估模型设计,对风险发生的概率及产生的影响进行量化,以便有效地进行风险管理。 相似文献
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贝叶斯网络是一种基于概率推理的图形化网络。随着越来越多的人参与贝叶斯网络的研究,贝叶斯网络将事物间的因果关系推到了极致,更使其自身在更多的领域内得到了广泛的应用。本文利用贝叶斯网络的知识对学生成绩评价系统进行建模,并对其中各个因素的影响进行分析并总结。 相似文献
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基于贝叶斯网络理论,把领域知识按知识项进行划分,然后在这些知识项之间建立组合依赖关系以确定贝叶斯网络的因果推理关系,最后确定变量的概率参数,建立了基于知识关系的覆盖型贝叶斯网络学习评估模型。并实现了基于贝叶斯网络学习评估模型的E-learning原型系统,系统能够对学生的知识掌握水平进行评估,并根据学生的评估结果,为学生提供个性化的导学建议。 相似文献
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网络交互质量是影响网络教学效果的重要因素。已有的网络交互教学成效评价系统缺乏对学习过程的监控和对学习者的良好建模,评价大多凭借专家经验,评估的主观随意性大,评价结果与实际值存在一定的误差。贝叶斯网络有很强大的解决不确定问题的处理水平,是目前基于概率的不确定表达和智能推理方面最有效的理论模型之一。基于贝叶斯网络的网络交互教学成效评价系统,基于领域知识关系构建贝叶斯网络学生模型,并引入模糊数学变换方法对学生认知水平进行评估。能减少不正常因素的干扰,提高对学生认知能力评价的精确度．实现对网络教学交互的质量评估和个性化导学。 相似文献
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张长坤 《常熟理工学院学报》2009,23(8):104-107
分析了贝叶斯网络的拓扑结构,给出了发动机怠速不良的故障树图．然后根据故障树到贝叶斯网络的转化算法,建立了贝叶斯网络模型．借助故障模拟试验数据确定了发动机怠速不良时电控汽油喷射系统贝叶斯网络故障诊断中各节点的先验概率值,然后通过贝叶斯网络找出了发动机怠速不良时电控汽油喷射系统各部件的故障发生概率． 相似文献
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E Millán J M Agosta & J L Pérez de la Cruz 《British journal of educational technology : journal of the Council for Educational Technology》2001,32(2):171-181
In this paper, the application of Bayesian networks to student modeling is discussed. A review of related work is made, and then the structural model is defined. Two of the most commonly cited reasons for not using Bayesian networks in student modeling are the computational complexity of the algorithms and the difficulty of the knowledge acquisition process . We propose an approach to simplify knowledge acquisition. Our approach applies causal independence to factor the conditional probabilities and decrease the parameters required for each question to a number linear in the number of concepts. This also provides the new parameters with an intuitive meaning that makes their specification easier. Finally, we present an example to illustrate the use of our approach. 相似文献
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Background
Antithrombotic therapy using new oral anticoagulants (NOACs) in patients with atrial fibrillation (AF) has been generally shown to have a favorable risk-benefit profile. Since there has been dispute about the risks of gastrointestinal bleeding (GIB) and intracranial hemorrhage (ICH), we sought to conduct a systematic review and network meta-analysis using Bayesian inference to analyze the risks of GIB and ICH in AF patients taking NOACs.Methods
We analyzed data from 20 randomized controlled trials of 91 671 AF patients receiving anticoagulants, antiplatelet drugs, or placebo. Bayesian network meta-analysis of two different evidence networks was performed using a binomial likelihood model, based on a network in which different agents (and doses) were treated as separate nodes. Odds ratios (ORs) and 95% confidence intervals (CIs) were modeled using Markov chain Monte Carlo methods.Results
Indirect comparisons with the Bayesian model confirmed that aspirin+clopidogrel significantly increased the risk of GIB in AF patients compared to the placebo (OR 0.33, 95% CI 0.01–0.92). Warfarin was identified as greatly increasing the risk of ICH compared to edoxaban 30 mg (OR 3.42, 95% CI 1.22–7.24) and dabigatran 110 mg (OR 3.56, 95% CI 1.10–8.45). We further ranked the NOACs for the lowest risk of GIB (apixaban 5 mg) and ICH (apixaban 5 mg, dabigatran 110 mg, and edoxaban 30 mg).Conclusion
Bayesian network meta-analysis of treatment of nonvalvular AF patients with anticoagulants suggested that NOACs do not increase risks of GIB and/or ICH, compared to each other.13.
This paper presents a quantitative method for automatic identification of human pulse signals. The idea is to start with the extraction of characteristic parameters and then to construct the recognition model based on Bayesian networks. To identify depth, frequency and rhythm, several parameters are proposed. To distinguish the strength and shape, which cannot be represented by one or several parameters and are hard to recognize, the main time-domain feature parameters are computed based on the feature points of the pulse signal. Then the extracted parameters are taken as the input and five models for automatic pulse signal identification are constructed based on Bayesian networks. Experimental results demonstrate that the method is feasible and effective in recognizing depth, frequency, rhythm, strength and shape of pulse signals, which can be expected to facilitate the modernization of pulse diagnosis. 相似文献
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针对工业生产过程中的时变性问题,提出贝叶斯网络框架下的自适应质量变量预测建模方法。采用改进的即时学习策略,将数据库分成若干局部数据子集,快速选择与待测样本相似度较高的一组数据作为训练样本, 再利用主成分分析对训练样本过程变量进行特征提取,借此作为网络模型输入变量。利用基于改进Figueiredo-Jain算法的EM算法估计高斯混合模型参数,构建高斯混合模型逼近贝叶斯网络联合概率密度,训练得到贝叶斯网络下的自适应质量变量预测模型。基于田纳西伊斯曼（TE）仿真过程获得的数据,利用该方法对成分XG进行预测并与传统PCA-BN模型对比。结果证实该方法最大误差下降14.4%,均方根误差下降7.5%,相对误差下降8.3%,验证了该方法解决时变性问题的有效性。 相似文献
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黄雅宁 《重庆职业技术学院学报》2011,20(4):21-24
20世纪90年代以来．国内证券公司相继发生操作风险而导致重大损失事件．一些证券公司被迫关闭或被接管。证券行业与监管当局高度重视操作风险,将操作风险与市场风险、信用风险并列作为内部控制的重点。国内逐步开发金融市场．证券公司面临着巨大挑战。控制和管理操作风险的水平是反映证券公司竞争力的重要内容。该文以2001－2009年国内证券公司导致重大损失事件的数据为依据．采用贝叶斯网络法建立简单模型．得出操作风险的损失发生概率。通过实证分析表明．贝叶斯网络模型适用于我国证券公司操作风险管理．并可用于假设分析。能够更有效地降低证券公司的操作风险。 相似文献
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Modeling Diagnostic Assessments with Bayesian Networks 总被引：1，自引：0，他引：1
Russell G. Almond Louis V. DiBello Brad Moulder Juan-Diego Zapata-Rivera 《Journal of Educational Measurement》2007,44(4):341-359
This paper defines Bayesian network models and examines their applications to IRT-based cognitive diagnostic modeling. These models are especially suited to building inference engines designed to be synchronous with the finer grained student models that arise in skills diagnostic assessment. Aspects of the theory and use of Bayesian network models are reviewed, as they affect applications to diagnostic assessment. The paper discusses how Bayesian network models are set up with expert information, improved and calibrated from data, and deployed as evidence-based inference engines. Aimed at a general educational measurement audience, the paper illustrates the flexibility and capabilities of Bayesian networks through a series of concrete examples, and without extensive technical detail. Examples are provided of proficiency spaces with direct dependencies among proficiency nodes, and of customized evidence models for complex tasks. This paper is intended to motivate educational measurement practitioners to learn more about Bayesian networks from the research literature, to acquire readily available Bayesian network software, to perform studies with real and simulated data sets, and to look for opportunities in educational settings that may benefit from diagnostic assessment fueled by Bayesian network modeling. 相似文献
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Bayesian mapping of neural tube defects prevalence in Heshun County, Shanxi Province, China during 1998-2001 总被引：1，自引：0，他引：1
Objective： To estimate the prevalence rates of neural tube defects （NTDs） in Heshun County, Shanxi Province, China by Bayesian smoothing technique. Methods： A total of 80 infants in the study area who were diagnosed with NTDs were analyzed. Two mapping techniques were then used. Firstly, the GIS software ArcGIS was used to map the crude prevalence rates. Secondly, the data were smoothed by the method of empirical Bayes estimation. Results： The classical statistical approach produced an extremely dishomogeneous map, while the Bayesian map was much smoother and more interpretable. The maps produced by the Bayesian technique indicate the tendency of villages in the southeastern region to produce higher prevalence or risk values. Conclusions： The Bayesian smoothing technique addresses the issue of heterogeneity in the population at risk and it is therefore recommended for use in explorative mapping of birth defects. This approach provides procedures to identify spatial health risk levels and assists in generating hypothesis that will be investigated in further detail. 相似文献
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政府网络是在物理通信网络连接的基础上,采用符合Internet技术标准的面向政府机关服务的网络,分为政务内网、外网、WEB网站。政府网络信息安全告警体系建设是具有战略性意义的项目,它的实施对政府机构转变管理职能和工作方式,提高服务管理水平,打造24小时服务型政府、建设高效规范的工作机制产生重要的影响。地方政府网络信息安全告警结合等级保护制度,采用人工神经网络计算模型及建立贝叶斯网络,并运用大规模并行处理和自学习自组织非线性动力学方法,探索出一套统一归一化的、具备五级告警机制的、可量化分析的政府网络信息安全告警体系。 相似文献