Inventory‐Based Dynamic Pricing with Costly Price Adjustment

We study an average‐cost stochastic inventory control problem in which the firm can replenish inventory and adjust the price at anytime. We establish the optimality to change the price from low to high in each replenishment cycle as inventory is depleted. With costly price adjustment, scale economies of inventory replenishment are reflected in the cycle time instead of lot size—An increased fixed ordering cost leads to an extended replenishment cycle but does not necessarily increase the order quantity. A reduced marginal cost of ordering calls for an increased order quantity, as well as speeding up product selling within a cycle. We derive useful properties of the profit function that allows for reducing computational complexity of the problem. For systems requiring short replenishment cycles, the optimal solution can be easily computed by applying these properties. For systems requiring long replenishment cycles, we further consider a relaxed problem that is computational tractable. Under this relaxation, the sum of fixed ordering cost and price adjustment cost is equal to (greater than, less than) the total inventory holding cost within a replenishment cycle when the inventory holding cost is linear (convex, concave) in the stock level. Moreover, under the optimal solution, the time‐average profit is the same across all price segments when the inventory holding cost is accounted properly. Through a numerical study, we demonstrate that inventory‐based dynamic pricing can lead to significant profit improvement compared with static pricing and limited price adjustment can yield a benefit that is close to unlimited price adjustment. To be able to enjoy the benefit of dynamic pricing, however, it is important to appropriately choose inventory levels at which the price is revised.     

基于一种半开式滑槽球副的3-PSP并联平台设计

提出在并联机构中应用一种1移动3转动半开式滑槽球副结构,该运动副将1个移动副和1个球副集成为一个复合的运动副,可以缩短并联机构中支链的尺寸链,有助于提高并联机构精度。基于半开式滑槽球副设计了一种3自由度(3-DOF)PSP三轴并联平台,通过对此机构进行的运动分析和支链的精度分析,导出各个支链的逆解方程,同时根据影响支链运动精度的各个因素给出支链系统误差的线性补偿方程,证明此并联机构具有易于控制、运动精度高的优势。     

Subgroup Analysis with Time‐to‐Event Data Under a Logistic‐Cox Mixture Model

Subgroup detection has received increasing attention recently in different fields such as clinical trials, public management and market segmentation analysis. In these fields, people often face time‐to‐event data, which are commonly subject to right censoring. This paper proposes a semiparametric Logistic‐Cox mixture model for subgroup analysis when the interested outcome is event time with right censoring. The proposed method mainly consists of a likelihood ratio‐based testing procedure for testing the existence of subgroups. The expectation–maximization iteration is applied to improve the testing power, and a model‐based bootstrap approach is developed to implement the testing procedure. When there exist subgroups, one can also use the proposed model to estimate the subgroup effect and construct predictive scores for the subgroup membership. The large sample properties of the proposed method are studied. The finite sample performance of the proposed method is assessed by simulation studies. A real data example is also provided for illustration.     

Estimating Abundance from Presence–Absence Maps via a Paired Negative‐Binomial Model

The estimation of abundance from presence–absence data is an intriguing problem in applied statistics. The classical Poisson model makes strong independence and homogeneity assumptions and in practice generally underestimates the true abundance. A controversial ad hoc method based on negative‐binomial counts (Am. Nat.) has been empirically successful but lacks theoretical justification. We first present an alternative estimator of abundance based on a paired negative binomial model that is consistent and asymptotically normally distributed. A quadruple negative binomial extension is also developed, which yields the previous ad hoc approach and resolves the controversy in the literature. We examine the performance of the estimators in a simulation study and estimate the abundance of 44 tree species in a permanent forest plot.     

城市化进程中少数民族流动人口就业现状、存在问题及其对策分析

城市化进程的加快,必然导致人口流动,更多少数民族人口流动到城市就业.作者对成都市少数民族流动人口就业现状、特征进行了调查,分析了少数民族流动人口就业存在的问题,并就与之相关的对策进行了探讨.     

曲线分类建模方法及其在GDP预测中的应用

传统方法解决大规模时序曲线的预测建模问题,需要对每条曲线逐一建模,使得建模工作量相当庞大,在实际应用中缺乏可操作性。文章提出一种解决此问题的新方法——曲线分类建模方法。该方法先减少曲线的模型种类,再进行曲线分类和分类建模,在尽可能保留原始信息的前提下较大程度地降低了建模的工作量。文章阐述了该方法的原理和计算过程,并以应用于多地区GDP曲线的预测案例说明该方法的实用性和有效性。     

信息学框架下学术期刊综合评价实证研究

从信息学的角度,阐述了学术期刊的功能,提出了信息学框架下学术期刊评价的质量观,同时构建了基于印刷型与电子型的学术期刊综合评价指标体系,并选择代表基础学科、医学和工程技术这三大类的物理学类期刊、医科大学学报类期刊和机械工程类期刊进行了实证研究,由此验证了学术期刊信息学评价方法及指标体系设置的合理性.     

特征AHP在高校教师教学质量评定中的应用

本文针对高校教师教学质量的评定提出了一种特征层次分析法。首先通过分析教学质量的影响因素,建立三层层次分析模型。在其基础上引入特征法,选取特征群并确定特征群中个体的权重,利用反算法根据组合权重及方案层权重,求取准则层评定指标权重,避免了不同质指标间对比的不确定性,摒除了专家直接给出评定指标对比矩阵的主观性,减少了对教师评定过程的不一致性和不完备性。     

本科院校课程建设评价指标体系研究

课程建设水平的高低直接影响着高校教学质量的高低和所培养人才的情况.而课程建设评价指标设立的正确与否,则成为正确评价课程建设水平的     

存现句There的语义格定位

There-be存现结构深层次的语言特点一直吸引着英语语言学家作深入的研究。近年来,There-be仔现句得到汉语语言学家越来越多的关注。传统的分析认为,there对句子没有任何贡献,许多语言学家把there称为“虚义”(exp letive)成分。虚词there的研究伴随着生成语法理论的发展,不少重要的理论假设都直接涉及there的研究。围绕there解释的各种理论催生了许多新的理论假说。对there进行准确定位有助于正确认识存现句结构的本质,化简某些理论构建的复杂性。