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基于ARMA模型的中国农产品价格的分析与预警 总被引:2,自引:0,他引:2
采用ARMA模型,对中国农产品生产价格指数(1979-2010)时间序列进行了建模分析.结果表明,ARMA(5,1)模型是平稳的且是可逆的.对2011-2013的中国农产品生产价格指数GPIFP进行了短期预测.预测结果分别是112,102和108.采用ARMA模型进行农产品生产价格指数的分析与预测,能较好地反映其动态变化,对促进我国农产品价格市场和谐发展具有重要的参考价值. 相似文献
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飞机排班是航空运输生产计划的重要环节,对航空公司的正常运营和整体效益有着决定性影响;飞机排班通常构建为大规模整数规划问题,是航空运筹学研究的重要课题,构建的模型属于严重退化的NP-Hard问题.在考虑对多种机型的飞机进行排班时,大大增加了问题的复杂性.针对航空公司实际情况,建立多种机型的飞机排班模型;为实现模型的有效求解,提出了基于约束编程的动态列生成算法;即用约束编程快速求解航班连线(航班串)并计算航班串简约成本,动态选择列集并与限制主问题进行迭代.最后,利用国内某航空公司干线航班网络实际数据验证模型和算法的有效性. 相似文献
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航班延误影响机场和航空公司的正常运行,同时给旅客出行带来不便,因此,对航班延误的预测分析具有重要的现实意义.在机场放行能力约束条件下,分析航班延误波及情况,对延误时长进行定量预测.以航班历史数据为学习样本,计算在前序航班延误的影响下,后续航班在不同延误等级的初始条件概率,并按照航班优先级以及预测时段机场的放行能力约束,对初始条件概率进行修正,从而对航班延误时长进行短期预测.最后通过实例分析,结果表明考虑机场放行能力约束,提升了航班延误预测的准确度,验证了方法的有效性. 相似文献
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将时间序列分析引入到气温时间序列预测的研究中,深入分析气温样本数据,并对其建立ARMA模型.采用最佳准则函数法确定模型的阶数,并利用自相关函数对模型的残差进行了检验.通过条件期望预测和适时修正预测方法求得预测值,与真实值的比较得到适时修正预测精确度比条件期望预测的精确度高. 相似文献
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本文针对同一机场中同机型的多架飞机受到干扰后, 飞机路径恢复的多目标最优化问题进行研究。首先根据航空公司实际航班调整的常用原则和航班干扰管理的基本思想, 基于连接网络建立多目标规划模型, 其中两个目标按照优先级排列:第一个目标为最小化航班的最大延误时间, 第二个目标为最小化参与交换的飞机数量。然后根据该问题的航班波结构特点, 结合求解多目标规划的分层序列法, 分析优化问题的若干最优性质, 并基于快速排序算法和最小费用路算法设计出多项式算法。最后用算例验证了算法的有效性。该研究结果可以为航空公司减少航班延误提供理论和技术支持。 相似文献
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F. J. Schuurmann P. R. Krishnaiah A. K. Chattopadhyay 《Journal of multivariate analysis》1973,3(4):445-453
In this paper, the authors cosider the derivation of the exact distributions of the ratios of the extreme roots to the trace of the Wishart matrix. Also, exact percentage points of these distributions are given and their applications are discussed. 相似文献
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《European Journal of Operational Research》2005,161(2):377-385
The valuation of levered investment in the practice is made with the WACC approach, even if the superior technique of the APV is available. The paper shows that the APV can be interpreted as the arbitrage free value of the portfolio made by an investment and a supporting loan. Therefore the WACC evaluation, generally different from the APV, allows for arbitrage. We provide various conditions which completely characterize the sign of the error as a functions of all the variables entering the model. 相似文献
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用常微分方程模型分析预防和隔离措施对SARS发病率的影响 总被引:2,自引:2,他引:0
通过建立常微分方程模型 ,分析了预防和隔离措施对 SARS发病率的影响 ,并把计算结果与实际统计数据进行了比较 ,结果表明 ,及时高效的预防和隔离措施能够有效地控制 SARS的传播 . 相似文献
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《Chaos, solitons, and fractals》2001,12(6):1101-1109
Two recent findings necessitate a closer look at the existing standard models of particle physics and cosmology. These are the discovery of neutrino oscillation, and hence a non-zero mass on the one hand and, on the other, observations of distant supernovae which indicate that contrary to popular belief, the universe would continue to expand for ever, possibly accelerating in the process. In this paper it is pointed out that relatively recent studies which indicate a stochastic, quantum vacuum underpinning and a fractal structure for space time, reconcile both of the recent observations, harmoniously. 相似文献
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Hans Jürgen Borchers 《Annales Henri Poincare》2002,3(1):1-17
The spectrum of the translations in local quantum field theory will be analyzed in order to show that in a positive energy representation without vacuum vector and with lowest mass m1 there is no gap in the spectrum which is larger than 2m1. In particular in a zero mass representation there is no hole at all. These results are obtained with methods of analytic functions of several complex variables. 相似文献
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Presented by A. F. Pixley. 相似文献
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For a Riesz operator T on a reflexive Banach space X with nonzero eigenvalues
denote by E(λi; T) the eigen-projection corresponding to an eigenvalue λi. In this paper we will show that if the operator sequence
is uniformly bounded, then the Riesz operator T can be decomposed into the sum of two operators Tp and Tr: T = Tp + Tr, where Tp is the weak limit of Tn and Tr is quasi-nilpotent. The result is used to obtain an expansion of a Riesz semigroup T(t) for t ≥ τ. As an application, we consider the solution of transport equation on a bounded convex body. 相似文献
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A. G. Shukhov 《Mathematical Notes》1999,65(4):510-515
Let {
} be a sequence of finitely presented groups with generating setA={a1, …, am}, and letRk be the symmetrized set of words over the alphabetA∪A−1 obtained from the defining words and their inverses by all cyclic shifts. We shall assume that the words inRk are cyclically irreducible, and their lengths tend to ∞ ask increases. In the paper, it is proved that ifRk satisfies the small cancellation conditionC'(1/6) and the number of relators increases not very rapidly with increasingk, then the growth rate ψ(Gk) tends to 2m−1 ask→∞.
Translated fromMatematicheskie Zametki, Vol. 65, No. 4, pp. 611–617, April, 1999. 相似文献