随机性模型下(s,S)订货策略在企业库存中的应用分析

现代企业在库存管理上主要采用两种模型,即确定性决策模型和随机性决策模型。通过对某拥有军用和民用两种产品的轮胎企业的调查研究,设计了适合其库存管理的决策模型。针对其民用轮胎产品需求的特性,结合企业数月实际的需求量,通过确定性模型推导出一般的随机性模型。仿真实验结果显示,(s,S)模型比EOQ模型有成本更低的优异性。     

基于Struts2结构的在线考试系统设计与实现

基于Struts2和J2EE技术框架,结合MySQL数据库,设计并实现了一个基于B/S架构的在线考试系统,重点阐述了用户答题模块的设计,并提出了一种系统随机出题的方法。     

浅谈《概率论与随机过程》课程教学

《概率论与随机过程》是电子信息类专业的一门重要的学科基础课,该课程不仅具有较强的理论性,还具有较强的实践性。因此在课程教学中,如何有效组织课程内容,提高学生学习兴趣,进而开拓学生思维,是本课程教师应该深思的问题。文章结合作者的教学经验,对该课程的教学方法进行了总结和探索。     

纪昀《乌鲁木齐杂诗》中的河西民俗——郝浚等《乌鲁木齐杂诗注》补正

纪昀《乌鲁木齐杂诗·民俗》中有的诗描写的实际上是河西走廊的民俗。这是因为乾隆年间政府大规模的迁徙河西民户到新疆屯垦，民户遂把河西的民俗带到了新疆。纪昀的这些诗，展示出了一幅幅活泼泼的风俗画，是研究清代前期河西民俗的重要资料，是西部边塞诗在清代的新发展。郝浚等人注释的《乌鲁木齐杂诗注》对“民俗”一类诗的解释没能追根溯源，个别观点僵化，有必要做一些补正。     

兰登书屋数字化发展研究

通过分析兰登书屋日渐成熟的电子书、有声书经营以及跨媒体出版方式,总结它在实现出版全球化过程中的宝贵经验。面对出版全球化、数字化的浪潮,享誉世界的大众图书出版商兰登书屋在运用数字手段拓展、巩固海外市场方面取得了骄人的成绩。它的数字化发展道路对我国出版业具有一定借鉴意义。     

Uncertain educational returns in a developing economy

This paper estimates the distribution of educational returns by gender for India. While previous studies focus on mean returns, the variance of educational returns has important implications for policy-making and micro-level decision making with respect to education. If the variance of educational returns is large, it can leave large sections of the population with negative returns; if the variance of educational returns is gender specific, it can influence households’ decisions to educate girls versus boys. Our econometric results provide evidence that India's labor markets are characterized by significant uncertainty and that the uncertainty is systematically larger for women.     

显式评分的重启动随机游走推荐算法研究

针对目前重启动随机游走推荐算法偏重隐式评分而忽略显式评分的问题,采用监督重启动随机游走算法,使得用户喜爱的项目被访问的概率大于用户不喜爱的项目的概率,从而做出推荐。实验表明,该算法可以有效地提高推荐的准确性。     

基于假设间隔的弱随机特征子空间生成算法

集成算法是机器学习领域的研究热点。随机子空间算法是集成算法的一个主要算法。随机子空间生成的特征子集可能含有冗余特征、噪声特征,影响算法的分类精度。为此,本文提出了一种基于假设间隔的弱随机特征子空间生成算法（WRSSimba）,有效去除了特征子集中冗余特征和噪声特征。在UCI数据集上的实验结果表明,WRSSimba的分类性能优于随机子空间算法和Simba算法。     

Iron removal from waterlogged wood: Extraction by electrophoresis and chemical treatments

Abstract

The presence of iron oxides (lepidocrocite, goethite) in archeological wood may result in a degradation of the wood matrix. Extraction of these iron oxides is largely dependent on their solubility. In this study, balsa wood samples were impregnated with iron oxides to test extraction treatments. Additionally, archeological wood samples were also examined to determine treatment efficiency. Electrophoresis and simple immersion treatments were performed using various chemical solutions: a neutral and a conductive substance (potassium nitrate), an acid (acetic acid), three alkaline chelating agents (tri-ammonium and tri-sodium citrate and sodium oxalate), three acidic and slightly acidic chelating agents (ethylenediaminetetraacetic acid (EDTA), citric acid, and oxalic acid), and a reductant (sodium dithionite). Potassium nitrate did not extract sufficient amounts of iron, irrespective of whether the treatment was conducted by electrophoresis or simple immersion; any observable dissolution was attributed to protonation because of the acidic pH around the anode (as low as 3). Dissolution in acetic acid did not extract iron with either treatment. Strong chelating agents improved extraction, and these compounds gave the best results for simple immersion, particularly EDTA. This chemical is well adapted for use on archeological objects because of its chemical properties (stability constant, speciation based on pH). The addition of sodium dithionite to the solution improved dissolution. Even though electrophoresis improved extraction (in particular for tri-ammonium citrate), none of the tested chelating chemicals were suitable for electrophoresis because of a significant increase in temperature as well as high anode corrosion. The presence of iron sulfide in the archeological wood limited the effectiveness of the tested chemicals. A pre-treatment in sodium persulfate was expanded to include oxidized iron sulfide in oxy/hydroxide iron, which improved the extraction rate.     

Meta-Analysis of Meta-Analyses in Communication: Comparing Fixed Effects and Random Effects Analysis Models

Thirty-nine meta-analyses obtained from the past 10 years of communication research (1997–2007) were reanalyzed using fixed effects (FE), random effects (RE), and Hunter and Schmidt (HS) meta-analytic methods. The majority of studies (62%) reported use of the HS model in the original analysis. Differences identified between models include (a) greater propensity for Type 1 error under the FE approach, (b) episodes of inflated effect size (ES) under the RE approach, and (c) high levels of heterogeneity in population ESs across studies. Recommendations are made for scholars to appropriately choose and implement meta-analytic models in future research.