Combining forecasts of electricity consumption in China with time-varying weights updated by a high-order Markov chain model

Electricity consumption forecasting has been always playing a vital role in power system management and planning. Inaccurate prediction may cause wastes of scarce energy resource or electricity shortages. However, forecasting electricity consumption has proven to be a challenging task due to various unstable factors. Especially, China is undergoing a period of economic transition, which highlights this difficulty. This paper proposes a time-varying-weight combining method, i.e. High-order Markov chain based Time-varying Weighted Average (HM-TWA) method to predict the monthly electricity consumption in China. HM-TWA first calculates the in-sample time-varying combining weights by quadratic programming for the individual forecasts. Then it predicts the out-of-sample time-varying adaptive weights through extrapolating these in-sample weights using a high-order Markov chain model. Finally, the combined forecasts can be obtained. In addition, to ensure that the sample data have the same properties as the required forecasts, a reasonable multi-step-ahead forecasting scheme is designed for HM-TWA. The out-of-sample forecasting performance evaluation shows that HM-TWA outperforms the component models and traditional combining methods, and its effectiveness is further verified by comparing it with some other existing models.     

显示问题式教材编纂法构想

传统的教材编纂法属于＂显示完美式教材编纂法＂,力求显示教材已将相应领域的问题都圆满解决,对于其中存在的问题不有意加以显示,甚至有意加以掩藏,故无法激发学生的创新意识、创新能力,甚或对创新有抑制作用。应采用＂显示问题式教材编纂法＂,力求将相应领域存在的各种问题显示出来,使学生产生创新的意念,明了创新的着力点,从而有力地促进学生创新能力的提高。     

中小型商业裙楼经营模式研究与创新——以南京市为例

以南京市为例，分析中小型商业裙楼空置的原因，研究现有商业地产经营模式，进行租售结合模式创新，提出适合中小型商业裙楼项目的节点招商，对比其他租售结合模式，明确节点招商的权属、租务合同等问题，详述其适用性和操作过程，并提出可能存在的问题。     

Misspecifications of the Normal Distribution

Incorrect statements about the normal distribution are discussed and illustrated with counterexamples.     

Computing the probability of hash table/urn overflow

We analyze the probability of a random distribution of n balls into m urns of size b resulting in no overflows. This solves the computational problem associated with a classical combinatorial extreme-value distribution. The problem arose during the analysis of a technique, called perfect hashing, for organizing data in computer files. The results and techniques presented can be used to solve several problems in the analysis of hashing techniques     

Asymptotic behaviour of a test statistic for detection of change in mean of vectors

The paper gives an asymptotic distribution of a test statistic for detecting a change in a mean of random vectors with dependent components. The studied test statistic has a form of a maximum of a square Euclidean norms of vectors with components being standardized partial cumulative sums of deviations from means. The limit distribution was obtained using a result of Piterbarg [1994. High deviations for multidimensional stationary Gaussian processes with independent components. In: Zolotarev, V.M. (Ed.), Stability Problems for Stochastic Models, pp. 197–210].     

我国普通教育与职业教育的协调性发展初论

从普通教育和职业教育的发展经历入手，研究总结我国现发展阶段，如何利用普通教育和职业教育分合经验，探究出既有利于我国社会生产力提高又有利于社会民主与教育机会均等的普通教育和职业教育协调发展的路子。     

Accent on Teaching Materials

A linear combination test for combining several tests of the correlation coefficient in the bivariate normal distribution is proposed. The linear combination test is compared with the well-known Fisher method of combining tests. It is shown by a Monte Carlo study that the linear combination test has a larger power.     

The linear combination,product and ratio of Laplace random variables

The distributions of linear combinations, products and ratios of random variables arise in many areas of engineering. In this paper, the exact distributions of the linear combination α X+β Y, the product |X Y| and the ratio |X/Y| are derived when X and Y are independent Laplace random variables. The Laplace distribution, being the oldest model for continuous data, has been one of the most popular models for measurement errors in engineering.     

聚合物/表面活性剂二元复合驱研究进展

从聚合物/表面活性剂二元体系的特点出发，综述了聚/表聚/表二元复合体系的实验室研究现状以及在胜利油田孤东七区54-61进行的矿场试验情况。聚/表二元复合驱是在聚/表/碱三元复合驱的基础上去掉碱所形成的低浓度的驱油体系，可以最大限度地发挥聚合物的粘度和弹性，减少乳化液处理带来的负面影响，减弱由于碱的存在引起的地层以及井筒结垢的现象。通过国内外研究结果分析表明，聚/表二元复合体系提高原油采收率幅度在20%左右；矿场试验取得了较好的效果。聚/表二元复合体系可以克服三元体系的缺点，作为一项新的驱油方法具有宽阔的发展空间。