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针对现有隐含因子模型存在的新用户和项目的冷启动问题,提出基于用户分类的隐含因子模型,将用户分类信息融入到隐含因子的矩阵分解当中,先在原评分矩阵和用户分类信息的基础上使用指示函数和数据归一化等方法构建一个分类评分矩阵,再将分类评分矩阵融入到隐含因子模型的评分预测中。通过与传统隐含因子模型等方法在多个不同隐含因子个数上的实验比较分析,实验结果表明,改进模型能够不仅能解决新用户和项目的冷启动问题,还能有效降低预测评分的均方根误差,并提高预测推荐的准确度。 相似文献
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模型确认试验是一种新的试验,其目的在于度量仿真模型的可信度.为了得到低成本、高可信度的模型确认试验方案,提出一种随机不确定性模型确认试验设计方法.首先,基于面积确认度量指标提出一种新的无量纲的模型确认度量指标(面积确认度量指标因子),并且在其基础上发展了基于专家系统的仿真模型准确性定性评判准则;然后,建立随机不确定性模型确认试验优化设计模型,提出该优化模型的求解方法;最后,通过两个数值算例对提出的模型确认试验设计方法进行验证.结果表明,小样本情况下,试验方案的随机性会影响模型评判结果的可信度;面积度量指标因子随试验样本数量的增加而收敛;随机不确定性模型确认试验设计方法能够避免试验方案对模型确认结果的影响. 相似文献
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信息物理系统被广泛应用于众多关键领域,例如工业控制与智能制造.作为部署在这些关键领域中的系统,其系统质量尤为重要.然而,由于信息物理系统自身的复杂性以及系统中存在的不确定性(例如系统通过传感器感知环境时的偏差),信息物理系统的质量保障面临巨大挑战.验证是保障系统质量的有效途径之一,基于系统模型与规约它可以证明系统是否满足要求的性质.现有一些信息物理系统的验证工作也取得了显著进展,例如模型检验技术就被已用工作用于验证系统在不确定性影响下的行为是否满足性质规约,并在性质违反的情况给出具体的反例.这些验证工作的一个重要输入就是不确定性模型,它描述了系统中不确定性的具体情况.而实际中要对系统中不确定性精确建模却并非易事,因此验证中使用的不确定性模型很可能与实际不完全相符,这将导致验证结果不准确并与现实偏离.针对这一问题,本文提出了一种基于反例确认的不确定性模型校准方法,来进一步精化验证结果以提高其准确度.首先通过确认反例在系统的执行中能否被触发来判断验证使用的不确定性模型是否精确.对于不精确的模型再利用遗传算法进行校准,并根据反例确认的结果来构造遗传算法的适应度函数以指导搜索,最后结合假设检验来帮助决定是否接受校准后的结果.在代表案例上的实验结果表明了我们提出的不确定性模型校准方法的有效性. 相似文献
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文章针对统一背景模型与群模型两种反模型进行了分析,在基于统一背景模型与群模型的改进说话人确认模型的基础上,将贝叶斯自适应算法引入到基于高斯混合统一背景模型的说话人确认系统,解决了说话人确认中存在的模型不匹配问题,通过文本无关的测试语音库进行的实验和分析显示,改进算法具有更好的识别效果。 相似文献
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Procedures are described for the representation of results in analyses that involve both aleatory uncertainty and epistemic uncertainty, with aleatory uncertainty deriving from an inherent randomness in the behaviour of the system under study and epistemic uncertainty deriving from a lack of knowledge about the appropriate values to use for quantities that are assumed to have fixed but poorly known values in the context of a specific study. Aleatory uncertainty is usually represented with probability and leads to cumulative distribution functions (CDFs) or complementary CDFs (CCDFs) for analysis results of interest. Several mathematical structures are available for the representation of epistemic uncertainty, including interval analysis, possibility theory, evidence theory and probability theory. In the presence of epistemic uncertainty, there is not a single CDF or CCDF for a given analysis result. Rather, there is a family of CDFs and a corresponding family of CCDFs that derive from epistemic uncertainty and have an uncertainty structure that derives from the particular uncertainty structure (e.g. interval analysis, possibility theory, evidence theory or probability theory) used to represent epistemic uncertainty. Graphical formats for the representation of epistemic uncertainty in families of CDFs and CCDFs are investigated and presented for the indicated characterisations of epistemic uncertainty. 相似文献
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虚拟维修模型的校验方法研究 总被引:1,自引:0,他引:1
介绍了虚拟雏修与建模仿真的关系,分析了虚拟维修模型校验的特点,研究了虚拟维修模型校验的方法,分别应用置信区间法、假设检验法、Bayes法、TIC法、频谱分析法从静态性能和动态性能两个方面对模型实施校验,从而为虚拟维修模型准确性、实时性提供了较为可靠的验证方法.为虚拟维修模型的校验提供一套系统的理论和方法,有利于虚拟维修模型得到更好应用. 相似文献
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针对模型确认中的确认度量问题,构造实验观测数据经验概率分布的置信包络。通过计算其与模型响应概率分布之间距离的上/下确界,给出基于概率分布距离确认度量的置信区间。通过构造与实验观测数据有关的协方差矩阵,给出基于概率分布距离的多响应模型确认度量及其置信区间的求解方式。该度量利用了模型输出与实验观测的完整概率分布信息,并且考虑了各模型响应间的相关性。算例仿真结果表明其确认错误率低于现有的其他两种确认度量。 相似文献
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对供应链计划建立了考虑不确定性的战略层模型和运作层模型。以一啤酒厂进行了实例研究,对所建模型和确定性的供应链计划模型进行了比较,并对柔性参数进行了灵敏度分析。结果表明,该模型能帮助设计具有柔性的供应链系统,通过灵敏度分析,可以更好地理解供应链的特性。 相似文献
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Tong ZhouAuthor Vitae Ling Wang Author VitaeZhengshun Sun Author Vitae 《Automatica》2002,38(9):1449-1461
This paper deals with probabilistic model set validation. It is assumed that the dynamics of a multi-input multi-output (MIMO) plant is described by a model set with unstructured uncertainties, and identification experiments are performed in closed loop. A necessary and sufficient condition has been derived for the consistency of the model set with both the stabilizing controller and closed-loop frequency domain experimental data (FDED). In this condition, only the Euclidean norm of a complex vector is involved, and this complex vector depends linearly on both the disturbances and the measurement errors. Based on this condition, an analytic formula has been derived for the sample unfalsified probability (SUP) of the model set. Some of the asymptotic statistical properties of the SUP have also been briefly discussed. A numerical example is included to illustrate the efficiency of the suggested method in model set quality evaluation. 相似文献
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Two new approaches to estimate Bayes factors in a finite mixture model context are proposed. Specifically, two algorithms to estimate them and their errors are derived by decomposing the resulting marginal densities. Then, through Bayes factor comparisons, the appropriate number of components for the mixture model is obtained. The approaches are based on simple theory (Monte Carlo methods and cluster sampling), what makes them appealing tools in this context. The performance of both algorithms is studied for different situations and the procedures are illustrated with some previously published data sets. 相似文献
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In the standard prediction error framework of system identification, statistical properties of estimated models are typically derived under the assumption that the true system is in the model class. The standard model structure validation test for plant models is the sample cross-correlation test between the residuals of the model and the input. It turns out that the standard test itself is valid only under exactly those assumptions it is meant to verify, i.e. the system is in the model class. It is shown that for reliable results of the validation test a vector-valued test is required and that accurate noise modelling is indispensable for reliable model structure validation. This shows the limitation of separate validation of plant and noise model structures. Improvements of the test are presented, and it is motivated by the fact that reserving data only to be used for model validation is not efficient. 相似文献
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不确定海量数据存储与记录的广泛应用及其在XML上的扩展,使XML的关联事件概率的数据模型研究成为研究热点,以描述复杂事件的概率数据模型为目标,在当前已有概率模型的基础上,提出了多维不确定概率模型空间的概念,基于多个概率模型进行统一建模,并把单维XML概率节点引申到多维空间,进而定义了统一的空间查询方式,为复杂概率数据建模和查询优化提供了一种新颖的理论方法。 相似文献
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在文本分类预处理过程中,运用贝叶斯方法构造计算文本关键词的条件概率模型,通过计算文本关键词的出现概率将文本映射为关键词的概率向量。在这个过程中贝叶斯方法用于计算条件概率而非分类。 相似文献