基于分数阶累加的灰色GM(1,1|sin)模型及其应用

本文研究了灰色模型对振荡序列的预测问题.在已有GM(1,1|sin)模型的基础上,利用分数阶算子对原始序列进行累加生成的方法,获得了分数阶累加GM(1,1|sin)模型的表达式;以平均相对误差最小化为目标,利用粒子群算法求解非线性优化问题,获得了模型的最优参数.最后以城市交通流的模拟预测为例,结果表明本文提出的模型比GM(1,1|sin)模型具有更高的模拟精度,推广了GM(1,1|sin)预测模型的结果.     

基于灰作用量优化的分数阶灰色预测模型研究

针对小样本振荡型数据序列的灰建模预测问题,提出基于灰作用量优化的分数阶GM(1,1|sin+cos)预测模型.在已有经典GM(1,1|sin)的基础上,一方面,将一阶累加灰生成拓展为分数阶累加灰生成,使得构建的模型更加符合新信息优先原理.另一方面,将灰作用量b_1 sin pk+b_2改进为b_1 sin pk+b_2 cos qk+b_3,其作用是通过增加余弦函数项cos qk,使得具有两个不同周期的运动项cos qk与b_1 sin pk+b_2叠加复合之后,能够生成更加贴近于振荡原始序列趋势和特征的时间响应序列,从而得到拟合精度较高的灰色模型.其次,对建模过程的时间响应式、模型参数p和q的最优估计问题进行了研究,构造了最优累加阶数r、参数p和q的粒子群优化算法,得到的优化模型实现了某些类型振荡序列较高精度的预测.实际数据例子结果表明,所建立的模型能够较好地模拟常见振荡型数据序列的波动趋势和特征,具有较强的适用性和拟合性能.     

分数阶反向累加非线性灰色Bernoulli模型及其应用

非线性灰色Bernoulli模型相对于普通的GM(1,1)模型,能更好的反映数据序列的非线性增长趋势.分数阶蕴含"in between"思想,分数阶累加灰色模型相对一般的累加灰色模型具有更好的预测效果和适应性.为了更好地符合新信息优先原理,实现最小信息的最大挖掘,构造了分数阶反向累加非线性灰色Bernoulli模型,即FAONGBM(1,1)模型,并给出了该模型的具体求解过程.在参数优化方面,本文通过粒子群优化(PSO)算法实现分数阶阶数和非线性指数的最优搜索.最后运用FAONGBM(1,1)模型对我国水力发电总量进行实证分析,结果证明所提出的模型具有良好的拟合精度和预测精度.     

分数阶反向累加非等间距GM(1,1)模型及应用

针对非等间距递减序列的预测问题,首先构建了一阶反向累加非等间距GM(1,1)模型(简称为非等间距GOM(1,1)模型),并给出了模型参数的最小二乘解和可用于预测的离散时间响应式.为进一步提高模拟预测精度,利用分数阶累加思想,提出了分数阶非等间距GOM(1,1)模型.以平均模拟相对误差最小化为目标,建立非线性规划模型可求解得到最优阶数.最后,以数值模拟和钛合金疲劳强度随温度变化预测为例,证实了该文提出模型的有效性和实用性.     

分数阶灰色累加生成算子与累减生成算子及互逆性

针对现有灰色预测模型主要以一阶累加生成序列作为建模序列,再累减还原为原始序列预测值,本文通过Gamma函数将累加生成算子和累减生成算子拓展到正实数领域,给出分数阶累加生成算子和分数阶累减生成算子的解析表达式,一阶和整数阶均是其特例,证明了两算子之间的互逆性.为建立分数阶灰色预测模型和拓宽灰色预测模型的应用范围提供理论基础.     

基于灰关联的GOM((p,q))(1,2)-BP神经网络模型及AQI预测

基于分数阶反向累加生成构建一种新的GM(1,2)模型,为使所构建模型能更好贴近和反映两个累加生成序列指标之间的真实关联关系,提出了基于不同序列采用不同累加阶数的GOM⁽(p,q))(1,2)模型.首先通过灰关联模型识别并筛选与特征序列关联度最大的相关因素序列,然后建立不同累加阶数的灰色模型,通过带压缩因子的粒子群优化算法求解模型最优阶数p和q,最后运用BP神经网络修正GOM⁽(p,q))(1,2)的模型值,构建GOM⁽(p,q))(1,2)-BP神经网络组合模型.模型应用于武汉市空气质量指数的预测,结果表明与单一模型相比,组合模型具有更好的性能和建模精度.     

含时滞参数的灰色GM(1,1,τ)模型及其应用

针对GM(1,1)模型未能反映系统时滞效应的问题,根据实际应用的需要,利用灰色建模思想构建了含时滞参数7的灰色GM(1,1,Υ)模型,并研究了该模型的建模机理、建模过程,给出参数估计方法.并根据模型的基本形式,构建出以原始值和背景值的一阶累减生成序列的灰色相对关联度最大化为目标的灰色关联分析法来探索时滞参数Υ的确定方法,并获得模型的离散解.最后利用该模型对美国制造业库存总量进行了模拟预测,获得较高的精度,验证了模型的有效性.     

短时交通流混沌预测模型的比较研究

短时交通流预测是实现交通流诱导的关键技术之一.针对目前短时交通混沌预测模型预测结果差异较大的问题,归纳了4种基于混沌理论的短时交通流预测模型:RBF神经网络模型、最大Lyapunov指数模型、局域线性模型和Volterra滤波器自适应预测模型,并对这4种预测模型进行了比较研究.应用4种预测模型对几个典型的非线性系统进行预测,验证了算法的准确性.然后用这4种预测模型对微观实测交通流的时间序列进行实证分析.仿真结果表明,4种预测模型对典型混沌时间序列具有很好的预测效果;而对实测交通流预测,其预测精度和稳定性较差,但可以满足实时交通流预测的需要.     

一种新的振荡型DGPM(1,N|sin)模型及其应用

针对传统多变量灰色模型未能有效预测振荡序列的问题,提出一种新的振荡型DGPM(1,N|sin)模型.首先,将非线性时间周期项和时变参数引入离散灰色预测模型;然后,建立非线性规划模型,利用遗传算法确定最优参数;最后,将该模型应用于中国消费价格指数的预测中,验证了本文模型的有效性和适用性.结果显示,振荡型DGPM(1,N|sin)模型有较高的预测精度,为振荡序列的预测提供了有效方法.     

分数阶累加生成GM~λ(1,1)模型的江苏省农民收入倍增能力预测

江苏省提出居民收入7年倍增计划.那么其农民收入能否同步倍增?基于分数阶累加生成GM~λ(1,1)灰色模型,采用2007—2012年江苏省农民收入数据,对其收入能力进行了预测.经计算发现,在MAPE误差允许范围内,选择分数阶λ值,可使预测结果更合理、更准确;最终结果表明江苏农民只需6年时间其收入就可以倍增.     

Stability Tests for Two Common Classes of Linear Time‐Delay and Hybrid Systems

The stability of linear timedelay systems with point internal delays is difficult to deal with in practice because of the fact that their characteristic equation is usually of transcendent type rather than of polynomial type. This feature usually causes the system to possess an infinite number of poles. In this paper, stability tests for this class of systems are obtained based either on extensions of classical tests applicable to delayfree systems or on approaches within the framework of twodimensional digital filters. Some of those twodimensional stability tests are also proved to be useful for stability testing of a common class of linear hybrid systems which involve coupled continuous and digital substates after a slightadhoc adaptation of the tests for that situation.     

基于EB和TB的混合及双混合随机补货策略

在分销系统中,对库存补货策略进行科学管理与控制是一直是学者们研究的热点之一,学术界始终没有有效提高三个传统库存补货策略运作效率的有效方法.在两个传统补货策略(EB(echelon-based),TB(time-based))策略的基础上,从减少EB和TB策略的极端情况角度,提出了混合策略1(HBl,Hybrid Based Policy1)和混合策略2(HB2,Hybrid Based Policy2),并将HB1和HB2的优点结合起来形成双混合策略(RH,Re-Hybrid Policy).数值试验表明,HB1、HB2对EB、TB的总成本费用比率有不同程度的改善,同时RH能有效改善HB1、HB2的总成本费用比率.     

半平面上的Dirichlet级数的$(p,q)(R)$级和$(p,q)(R)$下级

讨论半平面上的Dirichlet级数的(p,q)(R)级,(p,q)(R)下级和正规(p,q)(R)级及它们之间的联系,并讨论了(p,q)(R)级,(p,q)(R)下级与级数的指数之间的关系.     

Lower semicontinuity for approximate social Nash equilibria

We introduce a suitable concept of approximate social Nash equilibrium and we determine sufficient conditions of minimal character which guarantee, for a parametric social Nash equilibrium problem, the lower semicontinuity of the set-valued function defined by these approximate solutions. Received: December 2001     

Efficiency of purchasing and selling agents in markets with quality uncertainty: The case of illicit drug transactions

Since Akerlof’s theory of lemons, economists have viewed quality uncertainty as an informational advantage for sellers. Drawing on frontier techniques, we propose in this paper a simple method for measuring inefficiency of both sellers and buyers in markets for goods with different levels of quality. We apply a non-parametric robust double-frontier framework to the case of illicit substance markets, which suffer from imperfect information about drug quality for purchasers and to a lesser extent for sellers. We use unique data on cannabis and cocaine transactions collected in France that include information about price, quantity exchanged and purity. We find that transactional inefficiency does not really benefit either dealers or purchasers. Furthermore, information influences the performance of agents during market transactions.     

GM(1,1)模型适用域讨论及模型的改进

在已有灰色系统理论的基础上,讨论了GM(1,1)模型的适用域,明确界定了GM(1,1)模型的有效区域和禁区,并提出了GM(1,1)模型的一种改进形式——离散灰色预测DGM(1,1)模型.通过对我国经济增长的实证分析说明了该模型的有效性和可靠性.研究结果表明,提出的DGM(1,1)模型可作为灰色预测的一种精确模型,因此,为我国经济增长预测提供了一种新的方法,对当前我国经济的理性增长具有重要的指导意义.     

Abel maps and presentation schemes

We sharpen the two main tools used to treat the compactified Jacobian of a singular curve: Abel maps and presentation schemes. First we prove a smoothness theorem for bigraded Abel maps. Second we study the two complementary filtrations provided by the images of certain Abel maps and certain presentation schemes. Third we study a lifting of the Abel map of bidegree (m, 1) to the corresponding presentation scheme. Fourth we prove that, if a curve is blown up at a double point, then the corresponding presentation scheme is a ¹-bundle. Finally, using Abel maps of bidegree (m, 1), we characterize the curves having double points at worst.     

Fuzzy classifier identification using decision tree and multiobjective evolutionary algorithms

This paper presents a hybrid method for identification of Pareto-optimal fuzzy classifiers (FCs). In contrast to many existing methods, the initial population for multiobjective evolutionary algorithms (MOEAs) is neither created randomly nor a priori knowledge is required. Instead, it is created by the proposed two-step initialization method. First, a decision tree (DT) created by C4.5 algorithm is transformed into an FC. Therefore, relevant variables are selected and initial partition of input space is performed. Then, the rest of the population is created by randomly replacing some parameters of the initial FC, such that, the initial population is widely spread. That improves the convergence of MOEAs into the correct Pareto front. The initial population is optimized by NSGA-II algorithm and a set of Pareto-optimal FCs representing the trade-off between accuracy and interpretability is obtained. The method does not require any a priori knowledge of the number of fuzzy sets, distribution of fuzzy sets or the number of relevant variables. They are all determined by it. Performance of the obtained FCs is validated by six benchmark data sets from the literature. The obtained results are compared to a recently published paper [H. Ishibuchi, Y. Nojima, Analysis of interpretability-accuracy tradeoff of fuzzy systems by multiobjective fuzzy genetics-based machine learning, International Journal of Approximate Reasoning 44 (1) (2007) 4–31] and the benefits of our method are clearly shown.     

Subpullbacks and Flatness Properties of S-Posets

In [5 Laan , V. ( 2001 ). Pullbacks and flatness proprties of acts I . Comm. Algebra. 29 ( 2 ): 829 – 850 .[Taylor &; Francis Online], [Web of Science ®] , [Google Scholar], pp. 829–850] study was initiated of flatness properties of right acts A _S over a monoid S that can be described in terms when the functor A _S ?-preserves pullbacks. In that article, familiar flatness properties emerged in a new light, and new properties such as (PWP) and (WP) were discovered. In this article, we extend these results to S-posets. Also we introduce Conditions (WP) _w and (PWP) _w and consider the relation between them and Conditions (WP), (PWP), and po-flatness.