一种有效的证据理论合成公式

D-S证据理论是一种有用的不确定性推理方法,由于证据合成公式存在不足,影响了证据理论的应用。本文提出了一种有效的合成公式,即把支持证据冲突的概率按各个命题的平均支持程度加权进行分配。新的合成公式提高了合成结果的可靠性与合理性,即使对于高度冲突的证据,也能够取得理想的合成结果。     

一种基于证据理论的数据融合算法

针对传感器测量值存在系统误差的情况,基于证据理论的思想,提出一种新的数据融合算法。该算法首先将所有测量值根据其与真值的偏差进行分组,并分配不同的基本信任;然后将其构成的集合视为辨识框架,进而将各个测量值转换为相应的证据并进行证据组合,所得合成证据的Mass函数即为各个测量值的权值分配函数;最后对所得分组融合测量值进行加权求和,即得融合结果。仿真结果验证了该算法的有效性。     

Credit card fraud detection: A fusion approach using Dempster–Shafer theory and Bayesian learning

We propose a novel approach for credit card fraud detection, which combines evidences from current as well as past behavior. The fraud detection system (FDS) consists of four components, namely, rule-based filter, Dempster–Shafer adder, transaction history database and Bayesian learner. In the rule-based component, we determine the suspicion level of each incoming transaction based on the extent of its deviation from good pattern. Dempster–Shafer’s theory is used to combine multiple such evidences and an initial belief is computed. The transaction is classified as normal, abnormal or suspicious depending on this initial belief. Once a transaction is found to be suspicious, belief is further strengthened or weakened according to its similarity with fraudulent or genuine transaction history using Bayesian learning. Extensive simulation with stochastic models shows that fusion of different evidences has a very high positive impact on the performance of a credit card fraud detection system as compared to other methods.     

基于样本差异度的基本概率指派生成方法

提出一种基于样本差异度的基本概率指派(BPA) 生成方法. 建立三角模糊数模型, 根据所提出的差异度函数计算模型和待测样本的差异度, 生成初始BPA. 为了消除干扰影响, 对初始BPA进行冲突阈值判别并进行相应的冲突消解, 使得传感器在受到干扰等情况下也可输出合理的BPA. 鸢尾花分类实验表明, 所提出的方法简单实用, 具有较强的干扰消除能力.     

新的基于加权均值模型的证据融合方法

针对D-S证据理论难以处理证据冲突的问题,提出了一种将Murphy平均融合方法和证据权方法相结合的证据融合方法.该方法将显著偏差证据的判别引入融合流程,实现对证据权重的区分量化,建立了加权的基本概率分配均值模型.仿真结果表明:该方法能有效区分证据的重要程度,提高了证据融合的准确性与收敛速度,较好地解决了冲突证据融合的问题.     

证据理论在有序命题类问题中的基本概率分配

针对证据理论在有序命题类问题中的应用构造基本概率分配函数。有序命题类问题作为一种常见的分类问题,是证据理论应用的一个活跃领域,其基本概率分配存在显著的特点,在分析其特征的基础上,采用基于典型样本的方法,利用实测值与典型值之间的距离构造正态分布曲线的密度函数,进而构造基本概率分配函数。将该方法应用于海上溢油事故等级的评定,通过数据模拟分析其存在的不足,并通过弹性拉大实测值与典型值之间的距离、将“不知道”概率赋值等方法进行改进。实验结果表明改进的基于典型样本的方法能够有效地进行基本概率分配,满足应用的特点和需要。     

基于正态云模型的基本概率指派生成方法及应用

基本概率指派（Basic probability assignment, BPA）生成是应用D S证据理论的关键环节和第一步,而如何生成BPA仍然是一个有待解决的问题。本文提出一种基于云模型的BPA生成方法,首先,采用逆向云发生器生成每类样本在某属性下的正态云模型。其次,利用前件云发生器得到待测样本在该属性下对每类样本的确定度期望。再次,给出一种正态云模型交叠度计算方法,用确定度最大类的正态云模型与其他种类的最大交叠度作为对全集的信任度。最后,对确定度进行归一化得到待测样本的BPA。实验结果验证了该方法的有效性,此外,在样本数据较少情况下也能有效生成BPA。     

An Evidential Spam-Filtering Framework

Spam, also known as unsolicited bulk e-mail (UBE), has recently become a serious threat that negatively impacts the usability of legitimate mails. In this article, an evidential spam-filtering framework is proposed. As a useful tool to handle uncertainty, the Dempster–Shafer theory of evidence (D–S theory) is integrated into the proposed approach. Five representative features from an e-mail header are analyzed. With a machine-learning algorithm, e-mail headers with known classifications are used to train the framework. When using the framework for a given e-mail header, its representative features are quantified. Although in classical probability theory, possibilities are forcedly assigned even when information is not adequate, in our approach, for every word in an e-mail subject, basic probability assignments (BPA) are assigned in a more flexible way, thus providing a more reasonable result. Finally, BPAs are combined and transformed into pignistic probabilities for decision-making. Empirical trials on real-world datasets show the efficiency of the proposed framework.     

支持向量机与证据理论在信息融合中的结合

在多传感器信息融合中,DS证据理论是一种重要方法,但是它的基石基本概率分配(BPA)一般不易确定,从而使它的优势难以得到发挥。支持向量机(SVM)是建立在统计学习理论之上的一种新型学习算法,但SVM的硬判决输出却不便于进行多传感器信息融合。为便于信息融合,本文提出了一种具有BPA输出的二类SVM,通过分析Platt概率输出模型的实质与不足提出利用SVM精度下限对其进行加权处理来得到证据理论的BPA方法,实现了SVM与DS证据理论在信息融合中的结合。仿真结果表明通过本文方法可以实现多传感器的信息融合并大大降低了融合识别的误差率。     

On combination rule in Dempster–Shafer theory using OWA-based soft likelihood functions and its applications in environmental impact assessment

Dempster–Shafer theory (DST) was presented as an effective mathematical tool to represent uncertainty. Its significant innovation is to allow the allocation of the belief of mass to sets or intervals, and it becomes a valuable method in the field of decision making and evaluation when accurate information is not available or when knowledge is expressed subjectively by humans. A crucial research issue in DST is the combination of multi-sources of evidence. In this paper, a novel combination rule for Dempster–Shafer structures is developed based on ordered weighted average (OWA)-based soft likelihood functions proposed by Yager. First, the belief intervals, including the belief measures and plausibility measures, of all the hypotheses in the frame of discernment (FOD) are calculated. Second, the representative value of belief interval is defined based on golden rule introduced by Yager. Third, the soft likelihood value of each hypothesis is calculated based on the proposed OWA-based soft likelihood function for belief interval, which can be considered as the combined evidence. The final evaluation results can be employed for practical applications, such as decision making and evaluation. In addition, the improved evidence combination rule is presented which takes into account the weight of evidence. Several illustrative examples are conducted to manifest the use of the developed methods. Finally, an application for environmental impact assessment is given to demonstrate the usefulness of the developed combination rule in DST.     

Credibility decay model in temporal evidence combination

Data fusion in time domain is sequential and dynamic. Methods to deal with evidence conflict in spatial domain may not suitable in temporal domain. It is significant to determine the dynamic credibility of evidence in time domain. The Markovian requirement of time domain fusion is analyzed based on Dempster's combination rule and evidence discount theory. And the credibility decay model is presented to get the dynamic evidence credibility. Then the evidence is discounted by dynamic discount factor. It's illustrated that such model can satisfied the requirement of data fusion in time domain. Proper and solid decision can be made by this approach.     

A novel fuzzy evidential reasoning paradigm for data fusion with applications in image processing

This paper presents a novel data fusion paradigm based on fuzzy evidential reasoning. A new fuzzy evidence structure model is first introduced to formulate probabilistic evidence and fuzzy evidence in a unified framework. A generalized Dempster’s rule is then utilized to combine fuzzy evidence structures associated with multiple information sources. Finally, an effective decision rule is developed to take into account uncertainty, quantified by Shannon entropy and fuzzy entropy, of probabilistic evidence and fuzzy evidence, to deal with conflict and to achieve robust decisions. To demonstrate the effectiveness of the proposed paradigm, we apply it to classifying synthetic images and segmenting multi-modality human brain MR images. It is concluded that the proposed paradigm outperforms both the traditional Dempster–Shafer evidence theory based approach and the fuzzy reasoning based approach     

D-S证据理论在目标识别中的应用

D-S证据理论的应用过程与事件密切相关,针对目标识别这一特定领城,研究了证据理论中基本概率赋值的获取、组合规则及决策规则等问题.识别实例中,利用灰关联分析法来处理基本概率赋值的问题,对多传感器基本概率赋值进行组合后,最终通过决策完成对2种车型的类型识别,经计算仿真表明,D-S证据理论在目标识别中具有一定的有效性和优越性.