Diagnostics for dependence within time series extremes

Summary. The analysis of extreme values within a stationary time series entails various assumptions concerning its long- and short-range dependence. We present a range of new diagnostic tools for assessing whether these assumptions are appropriate and for identifying structure within extreme events. These tools are based on tail characteristics of joint survivor functions but can be implemented by using existing estimation methods for extremes of univariate independent and identically distributed variables. Our diagnostic aids are illustrated through theoretical examples, simulation studies and by application to rainfall and exchange rate data. On the basis of these diagnostics we can explain characteristics that are found in the observed extreme events of these series and also gain insight into the properties of events that are more extreme than those observed.     

提高开启式2F48型活塞式制冷压缩机性能的研究

本文通过对2F4.8制冷压缩机热力过程的计算机模拟,获得气阀参数对压缩机热力性能影响的数据资料,以改进气阀结构。经过试验证明,可提高压缩机制冷量和性能系数10%以上。     

基于SVM的综合实力评估系统研究

简略介绍了支持向量机的基本思想 ,研究其在综合评价中的应用。分析了对大学进行实力评估的过程 ,建立基于SVM的评价系统。比较新评价系统和采用其他方法如PCA (PrincipalComponentAnalysis主元分析 ) ,Fisher等建立的评价系统所分别取得的拟合效果。结果表明 :采用支持向量机设计的评价系统思路清晰 ,操作简单并且能取得更为理想的评估结果。     

我国工业电力用户价值画像模型构建与应用研究

在新型冠状病毒感染肺炎疫情对我国电力市场造成巨大冲击的宏观背景下,为进一步提升我国供电企业营销服务资源配置效能,最大化撬动供电企业的综合效益,笔者开展了我国工业电力用户价值画像模型研究。本文对电力用户价值进行了分析和定义,从安全稳定价值(S)、经济效益价值(E)、契约信用价值(C)与有序用电价值(O)四个维度,构建了我国工业电力用户价值评级SECO指标模型,并集成智能算法中的RST(粗糙集理论)与数据挖掘技术中的PAM(围绕中心点切割聚类算法),构造了一种半监督自动化用户价值识别、预测与特征展示模型,模型包括基于RST的指标体系设计、基于Gower相异度系数与PAM的用户价值评级,以及基于用户画像的价值特征展示三大模块。其中,为增强聚类分析结果的科学性与可靠性,采用霍普金斯统计量进行聚类趋势判断,利用间隔统计量输出理论最佳聚类数目,运用轮廓系数评估模型效果与识别误判样本。以我国南方电网公司下属某供电企业电力用户数据进行模型测试与应用研究,得到具有较高解释性与区分度的用户细分方案,表明本模型是一套可行有效的用户价值评级与特征可视化工具。     

A hybrid ARIMA and support vector machines model in stock price forecasting

Traditionally, the autoregressive integrated moving average (ARIMA) model has been one of the most widely used linear models in time series forecasting. However, the ARIMA model cannot easily capture the nonlinear patterns. Support vector machines (SVMs), a novel neural network technique, have been successfully applied in solving nonlinear regression estimation problems. Therefore, this investigation proposes a hybrid methodology that exploits the unique strength of the ARIMA model and the SVMs model in forecasting stock prices problems. Real data sets of stock prices were used to examine the forecasting accuracy of the proposed model. The results of computational tests are very promising.     

如何建立社区支持农业中的消费者信任——惠州四季分享有机农场的个案研究

信任对 CSA 经济的可持续至关重要。 文章基于信任建立过程和信任发展的阶段性理论,通过单案例的研究方法探讨如何构建社区支持农业中的消费者信任。 研究结果表明:消费者信任的建立分为初始信任与持续信任两个阶段。 在潜在消费者的初始信任阶段,直接或间接关系、公开的信息、农 场主特征和消费体验会引发消费者的计算过程、转移过程、预测过程、意图过程和能力过程而建立消费 者初始信任。 在会员的持续信任阶段,用户体验和社会联系会引发消费者的预测过程和意图过程而维 持会员对农场的信任。     

Mixed integer (0–1) fractional programming for decision support in paper production industry

This paper presents an effective and efficient method for solving a special class of mixed integer fractional programming (FP) problems. We take a classical reformulation approach for continuous FP as a starting point and extend it for solving a more general class of mixed integer (0–1) fractional programming problems.To stress the practical relevance of the research we focus on a real-life application in paper production industry. The constantly advancing physical knowledge of large scale pulp and paper production did have a substantial impact on an existing DSS in which mixed integer (0–1) fractional programming is introduced. We show that the motivation to solve a real-life fractional programming problem can provide the basis for a new approach in a new context that has an added value of its own, even outside the given application area. We describe the main characteristics of the DSS, the necessity to develop a non-iterative solution procedure and demonstrate both the effectiveness and efficiency of the proposed approach from practical data sets.     

Global liberalization on homosexuality: Explaining the African gap

We are trapped in two divergent worlds when it comes to global views on homosexuality. There is the liberal world epitomized by Spain and other nations, where homosexuality is increasingly accepted; gays and lesbians are claiming their human rights; and laws are changing to codify that transformation. The second is the extremely anti-gay world symbolized by Africa, the Middle East and parts of Asia, where attitudes are favorable to criminalization. This research explains the “African Gap” in attitudes toward homosexuality in a comparative analysis of six African nations and Argentina and Canada, South and North America's most liberal nations on gay rights. Using Pew's 2015 Spring Global Attitudes Survey data, we find that the major variables have essentially similar effects on opinion in any context. Africa's distinction is explained by its comparatively higher levels of factors such as religion, morality dogma, and low socioeconomic status that generally retard support for homosexuality, at the same time of lower levels of factors such as education, urbanization, and personal liberty that increase gay support. Africa's extreme anti-gay outlook is mutable. Two social forces will facilitate this softening: expansion of liberalizing agents such as education and urbanization, and repositioning away from “traditionalism” toward modernism emphasizing individualism, civil rights, and personal liberties.     

On the statistical computation of the sample multiple correlation moefficient

Based on the recursive formulas of Lee (1988) and Singh and Relyea (1992) for computing the noncentral F distribution, a numerical algorithm for evaluating the distributional values of the sample squared multiple correlation coefficient is proposed. The distributional function of this statistic is usually represented as an infinite weighted sum of the iterative form of incomplete beta integral. So an effective algorithm for the incomplete beta integral is crucial to the numerical evaluation of various distribution values. Let a and b denote two shape parameters shown in the incomplete beta integral and hence formed in the sampling distribution functionn be the sample size, and p be the number of random variates. Then both 2a = p - 1 and 2b = n - p are positive integers in sampling situations so that the proposed numerical procedures in this paper are greatly simplified by recursively formulating the incomplete beta integral. By doing this, it can jointly compute the distributional values of probability dens function (pdf) and cumulative distribution function (cdf) for which the distributional value of quantile can be more efficiently obtained by Newton's method. In addition, computer codes in C are developed for demonstration and performance evaluation. For the less precision required, the implemented method can achieve the exact value with respect to the jnite significant digit desired. In general, the numerical results are apparently better than those by various approximations and interpolations of Gurland and Asiribo (1991),Gurland and Milton (1970), and Lee (1971, 1972). When b = (1/2)(n -p) is an integer in particular, the finite series formulation of Gurland (1968) is used to evaluate the pdf/cdf values without truncation errors, which are served as the pivotal one. By setting the implemented codes with double precisions, the infinite series form of derived method can achieve the pivotal values for almost all cases under study. Related comparisons and illustrations are also presented     

固定效应部分线性变系数面板模型的快速有效估计

本文将最小二乘支持向量机(LSSVM) 和二次推断函数法(QIF) 相结合，为个体内具有相关结构的固定效应部分线性变系数面板模型提供了一种新的快速估计方法；在一定的正则条件下，论证了参数估计量的渐近正态性和非参数估计量的收敛速度；采用Monte Carlo模拟考察了估计方法在有限样本下的表现并将估计技术应用于现实数据分析。该方法不仅保证了估计的有效性和统计推断力，而且程序运行速度得到较大幅度提升。