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1.
李春 《数学的实践与认识》2014,(10)
研究具有脉冲接种的手足口病SEIR传播模型,首先得到了系统的无病周期解,其次证明了无病周期解的渐进稳定性并得到了系统渐进稳定性的条件.最后,根据已获得的数据对系统进行了数值模拟,得到了脉冲接种周期的临界值. 相似文献
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《数学的实践与认识》2018,(19)
考虑了一类对易感人群实施脉冲接种的传染病模型,应用微分方程的初值理论得出了系统的无病周期解,进而,应用脉冲微分不等式的比较定理,证明了当R_01时,无病周期解的全局渐近稳定性.最后,研究了对易感人群实施脉冲接种在传染病预防中的效果. 相似文献
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建立了具有非线性接触率脉冲预防接种的SIR传染病模型,利用脉冲微分方程理论,对模型的动力学性态进行了分析,给出了模型的阀值,证明了无病周期解的存在性及全局渐近稳定性. 相似文献
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研究了具有脉冲接种的多易感群体的DS-I-R传染病模型,分析了该模型无病周期解的存在性,给出了对疾病传播有重要影响的基本再生数,得到了无病周期解全局稳定性的充分条件. 相似文献
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提出了一个数学模型,用于研究脉冲投放免疫因子对HBV传染病动力学的影响.通过利用脉冲微分不等式和比较定理,证明了HBV模型的无病周期解的存在性,给出了无病周期解的全局渐近稳定性和系统的持续性的充分条件.研究结果表明:短的投放周期或适当的免疫因子投放量可以导致HBV的清除. 相似文献
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本文研究脉冲喷洒杀虫剂的植物病害模型.考虑在传染率随时间周期变化和森林树木总数保持不变的条件下,讨论具有垂直传播的一类具有单个种群的脉冲喷洒农药的SIRS模型,根据单值算子和Bohl-Brouaser不动点理论证明了无病周期解存在性,并且利用单值矩阵,Floquet理论得到其基本再生数并且给出了其无病周期解局部渐近稳定的条件. 相似文献
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We study the nilpotency of the sums of all coefficients of some sorts of products of polynomials over reversible, IFP, and NI rings, and introduce an SCN ring as a generalization. We characterize SCN rings in relation with related ring properties, and also provide several useful properties and ring extensions of SCN rings. 相似文献
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本文分析了15具白骨化尸体标本的股骨汞(Hg),铅(Pb),镉(Cd)元素含量数据,在三年的时间内采集了3次,一共收集到45个数据。首先将这组数据看着纵向数据,利用线性随机效应混合模型、Cox随机混合效应模型进行分析,结果显示,如果对每个白骨化尸体标本建立线性模型,可以精确预测出死亡时间,而且不需要采集铅元素含量数据。混合效应模型的预测效果也很好,最大误差不会超过1个月。其次我们对数据不作任何假设,利用机器学习中随机森林方法分析数据,并利用5折交叉验证方法来判断结果的可靠性,训练集和测试集的NMSE分别为0.1205944,0.5604286,因此可以用训练出的模型来预测死亡时间。 相似文献
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João C. Teixeira João F. Bigotte Hugo M. Repolho António P. Antunes 《European Journal of Operational Research》2019,272(2):608-620
Location modeling techniques have been applied to an extremely wide variety of public facilities. However, their application to one of the most ubiquitous public facilities – courts of justice – has been very rare. In this paper, we describe a study promoted by the Ministry of Justice of Portugal to define a proposal for the country's new judiciary map – that is, the spatial organization of the judicial system. The new map aims to promote the efficiency and specialization of the justice system (leading to better and faster court decisions) and to provide a good level of accessibility to courts. We developed two optimization models addressing those goals – a districting model, to determine the borders of new, large judicial districts; and a court location model, to determine the location, type, size, and coverage area of the courts included in each new district. Both models are discrete facility location models and consider hierarchical facilities – generic courts and specialized courts of multiple types. Our study was publicly acknowledged by the Portuguese government as having contributed to the new judiciary map that has since been approved and implemented. 相似文献
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本文在LF拓扑空间中建立了L-fuzzy集网的弱收敛(R-收敛)概念,应用文[4]中的R-闭包,系统讨论了它们的性质,证明了等式RlimA_n=∧(∨A_m)_R和RlimA_n=A_n=∧(∨A_m)_R并且给出了L-fuzzy集网与其子网之间的关系。 相似文献
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Arthur Cohen Harold B. Sackrowitz 《Annals of the Institute of Statistical Mathematics》1990,42(4):623-636
The problem of estimating the probability of unobserved outcomes or, as it is sometimes called, the conditional probability
of a new species, is studied. Good's estimator, which is essentially the same as Robbins' estimator, namely the number of
singleton species observed divided by the sample size, is studied from a decision theory point of view. The results obtained
are as follows: (1) When the total number of different species is assumed bounded by some known number, Good's and Robbins'
estimators are inadmissible for squared error loss. (2) If the number of different species can be infinite, Good's and Robbins'
estimators are admissible for squared error loss. (3) Whereas Robbins' estimator is a UMVUE for theunconditional probability of a new species obtained in one extra sample point, Robbins' estimator is not a uniformly minimum mean squared
error unbiased estimator of the conditional probability of a new species. This answers a question raised by Robbins. (4) It
is shown that for Robbins' model and squared error loss, there are admissible Bayes estimators which do not depend only on
a minimal sufficient statistic. A discussion of interpretations and significance of the results is offered.
Research supported by NSF Grant DMS-88-22622. 相似文献
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Yu. A. Dabaghian 《Theoretical and Mathematical Physics》2008,156(1):996-1019
We discuss how to obtain exact and approximate distributions for various statistical characteristics of the spectra of quantum
graphs using previously found exact solutions of the spectral problem. We indicate the relation between the appearing spectral
decompositions and the theory of weakly dependent random variables and indicate the relation between the known limit theorems
for trigonometric sums and the universal statistical properties of the spectra of quantum chaotic systems.
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Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 156, No. 1, pp. 38–66, July, 2008. 相似文献
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The aim of this paper is to establish the uniform convergence of the densities of a sequence of random variables, which are functionals of an underlying Gaussian process, to a normal density. Precise estimates for the uniform distance are derived by using the techniques of Malliavin calculus, combined with Stein?s method for normal approximation. We need to assume some non-degeneracy conditions. First, the study is focused on random variables in a fixed Wiener chaos, and later, the results are extended to the uniform convergence of the derivatives of the densities and to the case of random vectors in some fixed chaos, which are uniformly non-degenerate in the sense of Malliavin calculus. Explicit upper bounds for the uniform norm are obtained for random variables in the second Wiener chaos, and an application to the convergence of densities of the least square estimator for the drift parameter in Ornstein–Uhlenbeck processes is discussed. 相似文献
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有资格限制的指派问题的求解方法 总被引:3,自引:0,他引:3
在实际的指派工作中,常会遇到某个人有没有资格去承担某项工作的问题,因此,本建立了有资格限制的指派问题的数学模型。在此数学模型中,将效益矩阵转化为判定矩阵,由此给出了判定此种指派问题是否有解的方法;在有解的情况下,进一步将效益矩阵转化为求解矩阵,从而将有资格限制的指派问题化为传统的指派问题来求解。最后给出了一个数值例子来说明这样的处理方法是有效的。 相似文献
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以高超声速飞行器纵向运动的空气动力学模型和结构动力学模型为依据,采用数值分析的方法,研究了高超声速飞行器动力系统平衡点集的拓扑结构.首先根据高超声速飞行器在巡航阶段的飞行边界的限制条件得到在给定的飞行高度和马赫数下的平衡点集,由此近似估算出了高超声速飞行器的飞行包线.然后根据得到的平衡点集,分别研究了高超声速飞行器的迎角、升降舵偏角和发动机的燃料当量比与飞行马赫数和高度的关系,并进行了数值拟合,在此基础上分别描绘了以上三个拟合关系式的曲面关系图。 相似文献