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基于数学期望的非紧致保正性数值格式
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作者 任杰 徐浩然 岳兴业 《中国科学:数学》 CSCD 北大核心 2024年第3期515-528,共14页
常用的有限差分法、有限元方法和有限体积法等在数值求解偏微分方程时已经非常成功,但在处理各向异性问题时数值格式的保正性还存在一些问题.基于Feynman-Kac公式,可以将抛物方程的解表示为一个条件数学期望,涉及的随机扩散过程对应于... 常用的有限差分法、有限元方法和有限体积法等在数值求解偏微分方程时已经非常成功,但在处理各向异性问题时数值格式的保正性还存在一些问题.基于Feynman-Kac公式,可以将抛物方程的解表示为一个条件数学期望,涉及的随机扩散过程对应于抛物方程中的扩散项.不同于常用的紧致Markov链近似,本文用有限个连续分支路径逼近原来的随机过程,在满足相容性精度的条件下计算每个分支的停时(stopping time)、停时发生的概率和停时收益,从而可以逼近条件期望.这样基于数学期望的保正性,对任意的线性抛物型方程设计了一个全新的保正性的线性相容的数值格式,这是一个大时间步长、非紧致的、稳定的显式格式.由于有底层系统的理论支撑,本文的算法能够自适应地区分及处理边界的信息,避免现有算法(如半Lagrange方法)在边界附近精度缺失的问题. 展开更多
关键词 基于期望数值格式 Feynman-Kac公式 保正性
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基于小波神经网络的锂离子移动电源故障检测方法 被引量:1
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作者 胡翼 《内蒙古民族大学学报(自然科学版)》 2023年第1期32-38,共7页
针对检测环境中噪声影响因素过多、故障特征难捕捉问题,提出一种基于小波神经网络的锂离子移动电源故障检测方法。针对锂离子移动电源组之间的实际运行数据,构建电压及温度变化的数据检测矩阵,提取二者的故障特征参数,分析其在时间关系... 针对检测环境中噪声影响因素过多、故障特征难捕捉问题,提出一种基于小波神经网络的锂离子移动电源故障检测方法。针对锂离子移动电源组之间的实际运行数据,构建电压及温度变化的数据检测矩阵,提取二者的故障特征参数,分析其在时间关系下极差值、最大值以及最小值的实时变化情况。建立小波神经变换神经网络模型,将特征参数做为模型的输入数据,输出故障检测的实际数值和期望数值,利用修正函数将二者不断逼近,迭代计算得出最为逼近的实际故障检测数值。仿真实验证明,所提方法对移动电源的线路故障检测精准度高、误差较小,去噪性能较强,具有很强的实用价值。 展开更多
关键词 小波神经网络 极差值 修正函数 期望数值 故障点
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Mapping of quantitative trait loci using the skew-normal distribution 被引量:3
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作者 FERNANDES Elisabete PACHECO António PENHA-GONALVES Carlos 《Journal of Zhejiang University-Science B(Biomedicine & Biotechnology)》 SCIE CAS CSCD 2007年第11期792-801,共10页
In standard interval mapping (IM) of quantitative trait loci (QTL), the QTL effect is described by a normal mixture model. When this assumption of normality is violated, the most commonly adopted strategy is to use th... In standard interval mapping (IM) of quantitative trait loci (QTL), the QTL effect is described by a normal mixture model. When this assumption of normality is violated, the most commonly adopted strategy is to use the previous model after data transformation. However, an appropriate transformation may not exist or may be difficult to find. Also this approach can raise interpretation issues. An interesting alternative is to consider a skew-normal mixture model in standard IM, and the resulting method is here denoted as skew-normal IM. This flexible model that includes the usual symmetric normal distribution as a special case is important, allowing continuous variation from normality to non-normality. In this paper we briefly introduce the main peculiarities of the skew-normal distribution. The maximum likelihood estimates of parameters of the skew-normal distribution are obtained by the expectation-maximization (EM) algorithm. The proposed model is illustrated with real data from an intercross experiment that shows a significant departure from the normality assumption. The performance of the skew-normal IM is assessed via stochastic simulation. The results indicate that the skew-normal IM has higher power for QTL detection and better precision of QTL location as compared to standard IM and nonparametric IM. 展开更多
关键词 Interval mapping (IM) Quantitative trait loci (QTL) Skew-normal distribution Expectation-maximization (EM)algorithm
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An Approach to Resolving Two Paradoxes in Probability Theory
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作者 刘道建 黄天民 陈亚波 《Journal of Shanghai Jiaotong university(Science)》 EI 2008年第3期362-365,共4页
A new mathematical expectation formula with some hypotheses, notions and propositions was given to get rid of the challenge of St. Petersburg paradox and Pascal's wager. Relevant results show that it is very effec... A new mathematical expectation formula with some hypotheses, notions and propositions was given to get rid of the challenge of St. Petersburg paradox and Pascal's wager. Relevant results show that it is very effective to apply the model to solve the expected revenue problems containing random events with low proba-bility but high revenue. This work also provides the probability theory with a more widely applied perspective in group decision-making. 展开更多
关键词 conservative probability function conservation degree conservative mathematical expectation St. Petersburg paradox and Pascal's wager convergence group decision-making
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Numerical Characteristics of Fuzzy Numbers Based on Credibility Measure
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作者 曾玲 《Journal of Donghua University(English Edition)》 EI CAS 2007年第2期240-243,247,共5页
The numerical characteristics of fuzzy numbers include the optimistic value, pessimistic value, expected value, and the variance. We mainly provide the calculation formulae of several numerical characteristics of fuzz... The numerical characteristics of fuzzy numbers include the optimistic value, pessimistic value, expected value, and the variance. We mainly provide the calculation formulae of several numerical characteristics of fuzzy numbers based on credibility measure. Especially, the variance of symmetric fuzzy numbers is formulated, and a super bound for the variance of fuzzy numbers is presented. Meanwhile, some conclusions relative to credibility measure, optimistic and pessimistic values are also given. 展开更多
关键词 fuzzy number credibility measure optimisticvalue pessimistic value expected value variance
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ON THE TRANSIENT DEPARTURE PROCESS OF M^x/G/1 QUEUEING SYSTEM WITH SINGLE SERVER VACATION 被引量:4
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作者 Yinghui TANG 《Journal of Systems Science & Complexity》 SCIE EI CSCD 2007年第4期562-571,共10页
This paper studies the transient departure process of M^x/G/1 queueing system with single server vacation. We present a simple probability decomposition method to derive the expected number of departures occurring in ... This paper studies the transient departure process of M^x/G/1 queueing system with single server vacation. We present a simple probability decomposition method to derive the expected number of departures occurring in finite time interval from any initial state and the asymptotic expansion of the expected number. Especially, we derive some more practical results for some special cases. 展开更多
关键词 Asymptotic expansion expected number group arrival server vacation.
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