Assortment optimization with position effects under the nested logit model

We study the assortment optimization problem with position effects under the nested logit model, whose goal is to find the revenue-maximizing subset of products as well as their corresponding display positions. In this joint assortment-position optimization problem, the choices of products are affected by not only their qualities and prices but also the positions where they are displayed. Despite determining the assortment and their corresponding display positions sequentially, we propose to solve this problem in an integrated way to obtain the optimal solution. We formulate this problem as a nonlinear binary integer programming model and develop a dynamic programming based solution approach to obtain the optimal assortment-position assignments. We carry out extensive numerical experiments to evaluate the benefit of our integrated approach. The most important insight we discover is that it is not necessarily better to put the most attractive products in the best position. Moreover, we show that compared to the sequential approaches, our approach can improve revenue by 10.38% on average, which suggests that firms should take into consideration position effects when making assortment decisions. Finally, we discuss results related to two extensions of this problem, that is, the special case when positions are preassigned to nests, and the joint assortment-position-price optimization problem.     

Social benefits of government investment in enterprises

A critical issue for many governments is boosting the adoption rates of products or technologies that enhance consumer surplus or total social welfare. Governments may, for example, pay subsidies to producers or to consumers to stimulate the manufacture or consumption of specific products, for example, energy-efficient appliances or more effective drugs. This research proposes a strategic government investment policy, namely, share acquisition, and demonstrates its effectiveness in reaching societal objectives. We consider a Cournot quantities-choice market comprised of homogeneous firms where the government intervenes to buy shares, and turning private firms into state-owned enterprises. We recognize that purchasing a single private firm is the optimal policy for the government to reach its societal objectives. Additionally, taking into consideration financial constraints, we find that the optimal stake increases with the budget. Compared with the optimal output-based subsidy policy, when the budget is low, the optimal government investment policy induces a higher consumer surplus. In addition, in differentiated Cournot competition, under which firms compete in selling substitutable products, we find that when the budget is sufficient, the optimal stake purchased first decreases and then increases according to the substitutability level among products.     

国内外安全标准现状与发展及其对构建国防工业安全标准体系的启示

介绍了国外发达国家、先进组织机构安全标准及体系的现状与特点,分析了国内安全标准的制修订情况和危险化学品、防尘防毒安全生产标准体系的分类与构成。在分析国防科技工业安全标准现状的基础上,提出了构建国防工业安全标准体系的主要任务和实施要求。     

论信息化战争条件下我军装甲兵部队数字化建设

通过对信息化战场和数字化部队的描述,说明在信息化战争中,装甲兵部队仍然是地面战争主要突击力量,在分析了信息化战争特点的基础上提出加速我军装甲兵信息化发展建设的建议及方法。     

一种新型的不精确推理——SCESS不精确推理

本文是以模糊数学理论为基础,并考虑了人的心理因素,构造出一种新型的不精确推理。它已在一个实用的专家系统——突发性案件专家支持系统(SCESS)中得到实现。该推理能处理用单个数值、模糊区间和自然语言描述的不精确知识的可信度,并通过用户的态度得出相应的结论。     

过程速率有限对卡诺制冷机制冷系数与利润率间关系的影响

本文讨论在给定的热源温度和压缩比的情况下,涉及活塞惯性且过程进行的速率有限,只考虑传热不可逆影响的内可逆卡诺制冷机的制冷系数与利润率的关系,得到了一些有意义的结论,为实际制冷机设计提供了一个新的理论依据。     

以弱胜强 以退为进——老予军事哲学思想探析

本文从三个方面探讨<老子>军事哲学思想:一、从根本战略思想看,<老子>主张"柔弱胜刚强",其实质是认为新事物必然战胜旧事物;二、从谋略角度来考察,<老子>主张面对强敌,弱军不妨先退一步,后发制人,因而取胜;三、在前两点基础上形成的一套以弱胜强的独特战法.     

FBN和JF402在泡沫洗消剂中的展开作用及其对泡沫性能的影响

研究了FBN、JF402 2种碳氟表面活性剂与发泡剂配伍后形成的水溶液在油面上的铺展及泡沫性能（发泡力和稳定性）。结果表明FBN、JF402的加入可提高体系的铺展能力。FBN的铺展性能好于JF402,但JF402泡沫性能好于FBN。     

二价阳离子对梭曼的水解作用

实验就4种不同浓度的二价阳离子,研究了它们对梭曼的水解作用和对梭曼水解酶的激活作用．结果表明随着二价钴离子浓度增高,对梭曼催化水解作用增强,其中0．6mmol／L Co^2＋价钴离子对人肝梭曼水解作用最强;18mmol／L Co^2＋对酶的催化水解激活作用最强．     

破片侵彻多层间隔铝靶的试验及数值模拟研究

对破片侵彻多层间隔铝靶进行了试验和数值模拟研究,获得了破片在不同速度、不同侵彻角时破片的侵彻深度,在此基础上利用拟合的方式建立了计算公式,并将数值模拟结果和计算公式的计算结果进行了对比,结果表明两者吻合较好,所建立的计算公式可靠。