融合情感评论倾向与均衡长尾物品的推荐方法

推荐领域中已有研究较多的考虑属性维度在评分-物品上来提高算法的准确性,对于用户对产品的真实态度判断不够。论文利用LSTM神经网络模型将用户评论情感得分和用户评分进行融合分析,来计算用户对物品真正的兴趣度;运用向量空间对用户情感进行三分类,借鉴经济学中基尼系数的思想,引入惩罚因子通过对热门物品进行调节,发挥系统的长尾能力从而增加推荐结果的覆盖率,从而实现对热门物品和冷门物品被推荐程度的均衡优化。最后,对情感系数和惩罚系数参数的取值进行实验,得出最优模型参数组合,结果表明,评论的情感因素和惩罚系数对于构建性能更优的推荐模型效果明显,该模型在推荐的准确率和覆盖率上相较其他主流模型更加符合用户需求。     

摩擦磨损试验机设计的基础 Ⅱ.摩擦磨损试验机设计方法的研究

本讲介绍采用设计方法学的方法对摩擦磨损试验机设计进行研究的结果,建立了摩擦磨损试验机的要求明细表,功能结构图、设计模幅箱和方案评价目标树。根据本讲所阐述的方法,既可使摩擦磨损试验机的设计程序和方案评价建立在一套比较科学的和行之有效的方法上,又能作为建立摩擦磨损试验机CAD(计算机辅助设计)系统的基础。     

Retailer’s optimal ordering policy for deteriorating items with maximum lifetime under supplier’s trade credit financing

Many products such as fruits, vegetables, pharmaceuticals, volatile liquids, and others not only deteriorate continuously due to evaporation, obsolescence, spoilage, etc. but also have their expiration dates (i.e., a deteriorating item has its maximum lifetime). Although numerous researchers have studied economic order quantity (EOQ) models for deteriorating items, few of them have taken the maximum lifetime of a deteriorating item into consideration. In addition, a supplier frequently offers her/his retailers a permissible delay in payments in order to stimulate sales and reduce inventory. There is no interest charge to a retailer if the purchasing amount is paid to a supplier within the credit period, and vice versa. In this paper, we propose an EOQ model for a retailer when: (1) her/his product deteriorates continuously, and has a maximum lifetime, and (2) her/his supplier offers a permissible delay in payments. We then characterize the retailer’s optimal replenishment cycle time. Furthermore, we discuss a special case for non-deteriorating items. Finally, we run several numerical examples to illustrate the problem and provide some managerial insights.     

Economic production quantity model with repair failure and limited capacity

We develop an economic production quantity (EPQ) model with random defective items and failure in repair. The existence of only one machine results with limited production capacity and shortages. The aim of this research is to derive the optimal cycle length, the optimal production quantity and the optimal back ordered quantity for each product so as to minimize the total expected cost (holding, shortage, production, setup, defective items and repair costs). The convexity of the model is derived and the objective function is proved convex. Two numerical examples illustrate the practical usage of the proposed method.     

An extension of partial backordering EOQ with correlated demand caused by cross-selling considering multiple minor items

Zhang et al. (2011) proposed the partial backordering EOQ with correlated demand caused by cross-selling, where a portion of the sales of a minor item is associated with those of a major item. In this paper, we extend their model to make it more applicable to dealing with the inventory replenishment problem for multiple associated items. We formulate the model as a mixed integer nonlinear programming (MINLP) problem and develop a global optimum search procedure with the fill rate given. We further employ a one-dimensional search on the fill rate to obtain the minimum total inventory cost within a predetermined precision, which enjoys polynomial computational complexity.     

同位网格上SIMPLE算法收敛特性的Fourier分析

应用Fourier方法研究了同位网格上SIMPLE算法求解浅水方程的收敛特性,并就松弛因子组合及阻力项的影响进行了分析.结果表明,采用合适的松弛因子组合可以很快地消除高频区域的误差,同时也可逐步消减迭代中低频区域的误差以获得收敛解.在保证收敛的前提下,低频误差分量决定了迭代速度,而且浅水方程中阻力项越大越利于SIMPLE算法收敛.     

基于测试项抽取的测试用例复用方法

针对测试用例复用过程中测试用例与被测模块相关性较高的现状,提出了一种测试用例复用的方法.通过抽取测试用例步骤序列的测试项,生成一个测试项集合,然后在新测试工作时检索该集合以实现测试用例的复用.另外,为了便于测试用例的管理,文中采用XML描述测试用例.实例表明,该方法能够有效降低测试用例与被测模块相关性,提高测试效率.     

新课程高考化学选考题学生答题的初步调查与思考——基于新课标全国卷

通过调查与思考,得出新课程高考选考题学生选择及作答的结果与学校开设选修课程模块、试题的难易程度、学生作答时间多少、学生的学习能力等4个因素相关。建议学校应在开足选修课程模块的前提下,赋予学生表现出其主体的选择性,从而切合新课程选修多模块的设计思路及新课程改革的核心理念"一切为了每一位学生的发展"。     

需求受库存影响下具有固定保质期物品的最优订货策略

带有固定保质期物品的订货是供应链终端销售系统的一个重要决策问题,假设需求依赖库存展示水平并考虑"后进先出"的销售策略而建立了相应的库存决策模型,其中物品在固定保质期内仍具有常数的变质速率.然后以系统平均利润最大化为目标讨论了模型最优解的存在性及唯一性,并提供了寻求模型整体最优解的简单方法.最后给出应用实例,并分析了模型参数变化对最优订货策略的影响.     

Weibull变质率和短缺量拖后的易变质物品EOQ模型

基于需求和采购价格均为时变的EOQ模型,考虑物品的变质率呈更符合现实情况的三参数Weibull分布,同时考虑短缺量拖后和资金时值对易变质物品库存管理的影响,构建了相应的EOQ模型.应用数学软件Matlab对该库存模型进行仿真计算和主要影响参数的灵敏度分析.结果表明,该模型存在最优解,且各主要影响参数对最优库存控制各有不同程度的影响,资金时值对库存总成本净现值的影响程度要甚于短缺量拖后的影响,故在制定科学的库存策略时资金时值需要更加关注.