Web 数据挖掘及其在电子商务网站中的应用

Internet应用的普及使得数据挖掘技术的重点已经从传统的基于数据库的应用转移到了基于Web的应用,电子商务网站每天都会产生大量的数据,运用数据挖掘技术可以从这些数据中发现对市场分析及预测非常有益的信息。本文讨论了Web数据挖掘技术在电子商务中的应用。     

A Tutorial on Palm Distributions for Spatial Point Processes

This tutorial provides an introduction to Palm distributions for spatial point processes. Initially, in the context of finite point processes, we give an explicit definition of Palm distributions in terms of their density functions. Then we review Palm distributions in the general case. Finally, we discuss some examples of Palm distributions for specific models and some applications.     

Comparative randomized inverse sampling

According to previous literature, we define randomized inverse sampling for comparing two treatments with respect to a binary response as the sampling that stops when a total fixed number of successes, irrespective of the treatments, are observed. We have obtained elsewhere the asymptotic distributions for the counting variables involved and have shown them to be equivalent to the corresponding asymptotic distributions for multinomial sampling. In this paper, we start deriving the same basic results using different techniques, and we then show how they give rise to genuinely novel procedures when translated into finite sample approximations. As the main example, a novel confidence interval for the logarithm of the odds ratio of two success probabilities can be constructed in the case of comparative randomized inverse sampling. Some advantages over the standard multinomial sampling in terms of coverage probabilities are visible when no adjustment for cells with zero counts is applied; otherwise, the two sampling schemes appear to be fairly equivalent. This is a reassurance that under certain circumstances, inverse sampling can be safely chosen over more traditional sampling schemes.     

Cointegration in China's log import demand: Price endogeneity and structural change

The monthly data of China's log import from January 2000 to December 2013 are used to estimate the import demand elasticities, with the consideration of possible price endogeneity due to China's large share of the international log market, and structural break caused by global financial crisis in 2008. To address the possible structural break, cointegration tests allowing for a deterministic shift in the level of the variables are employed, and a two-stage estimation with top-down sequential elimination algorithm is performed on the restricted subset VECM. The results demonstrate that there exists a long-run cointegration relationship between China's log import and the explanatory variables. The import elasticities of macroeconomic development and import price are around 0.76 and −0.81, respectively. Other things being equal, the structural break would induce a 29.6% decline in China's log import. All the above parameters are significant at the 1% risk level. Furthermore, the contribution decomposition analysis suggests that China's macroeconomic development plays a dominant role in determining its log import, which implies that China's log import would not increase as quickly as before, given that its economy is shifting into the “New Normal State”. This conjecture is supported by our simulations, which indicate that, by 2020, the growth rate of China's log import will be lower than it has been in the past and the import volume would be approximately 1.1–1.6 times greater compared to imports in 2013.     

基于过程挖掘的物流运作风险发现研究

为了探究物流运作过程中存在的风险,提高物流运作效率,增强物流企业管理能力,以真实的事件日志为基础,运用过程挖掘方法发现物流企业运作过程中的风险。首先以Petri网理论为基础,构建了理想的工作模型,然后使用过程挖掘工具ProM,运用模糊挖掘算法和启发式挖掘算法,对物流运作过程中产生的真实事件日志进行挖掘,获得实际的客观视图,最后利用ProM工具的一致性检查发现物流运作过程中的异常行为模式,并分析物流运作过程中的偏差以及存在的风险。结果表明,过程挖掘能客观地揭示事件日志中活动之间的依赖关系,并发现物流企业自身运作过程中的偏差和风险。研究结果为全面、系统地分析物流企业潜在风险提供了新思路,有助于物流企业发现运作过程中的问题,对物流企业优化运作过程和提高管理效率具有重要的借鉴意义。     

中国原木进口与国际原木非法贸易问题的若干思考

在分析认识中国木材供需矛盾问题的基础上,对中国的原木进口和国际非法采伐加剧原木非法贸易之间的关系进行了探讨。中国原木进口依存度高,非法原木进口防范程度低,缺乏应有的进口门槛,行业自律机制不健全,给非法原木贸易提供了机会。为进一步探讨国际反原木非法贸易对中国原木进口需求的影响,文章采用差异化进口需求模型方法,分析了国际打击原木非法贸易背景下中国原木进口需求的相关数量变化关系。研究结果表明,中国的原木进口正在朝着理性的方向进展,来自美国、新西兰的原木进口比重日益增加而来自非法原木高危国的原木进口日益减少。基于研究提出中国应提高自身的生产能力以及完善合法认证体系,降低原木的进口依赖,同时发挥大国作用,一起推动非法原木高危国的木材合法认证体系的发展。     

一种新型木材防水专用乳化蜡的研制

以54-56#全炼蜡或半炼蜡为原料,选用复合表面活性剂作为乳化剂,重点考察了乳化剂用量、乳化温度、乳化时间、搅拌速度等影响石蜡乳化因素.实验结果表明,当乳化剂用量为蜡用量的25%,乳化温度为85～90℃,搅拌速度为400r/min时,乳化时间为30min,可以制取一种稳定的实木防水专用乳化蜡.     

计算机审计中的电子数据轨迹分析

不同阶段电子数据的操作都会留下表现各异的轨迹。从操作系统、计算机应用系统、数据传输、数据采集和分析等不同层面深入分析审计电子数据轨迹在计算机系统中表现形式，可以为审计人员提供有效的审计方法。     

Cover's universal portfolio,stochastic portfolio theory,and the numéraire portfolio

Cover's celebrated theorem states that the long‐run yield of a properly chosen “universal” portfolio is almost as good as that of the best retrospectively chosen constant rebalanced portfolio. The “universality” refers to the fact that this result is model‐free, that is, not dependent on an underlying stochastic process. We extend Cover's theorem to the setting of stochastic portfolio theory: the market portfolio is taken as the numéraire, and the rebalancing rule need not be constant anymore but may depend on the current state of the stock market. By fixing a stochastic model of the stock market this model‐free result is complemented by a comparison with the numéraire portfolio. Roughly speaking, under appropriate assumptions the asymptotic growth rate coincides for the three approaches mentioned in the title of this paper. We present results in both discrete and continuous time.