关键词： Traditional retail   supermarkets   e-commerce   supply chains  

摘要： Food retail has been in continuous evolution for the past century-both in developing and developed countries-from local traditional stores to supermarkets to e-commerce. In this paper we analyze the evolution of food retail by building a store choice equilibrium model and providing an illustrated discussion. The patterns in retail in any given time and place of different types of stores (such as traditional shops, supermarkets, and online e-commerce) depend on two main factors. The first are consumers' characteristics such as income, tastes, and travel costs of going to different stores and/or shipping costs if purchasing online. The second are the stores' cost structures, which include item costs from upstream producers, the costs of procurement supply chains (beyond the cost of the item) for perishable items, and the costs of in-store storage. We show under what conditions in equilibrium the different retail types exist and which can become dominant, and what types of goods (dry packaged foods versus perishables) are distributed by what type of retailers.

关键词： Circular economy   Product families   Indicators   Sustainability   Functional performance  

摘要： Currently, design for sustainability is a necessary issue in any product development process. This situation is due to the existing and increasing pressure under industrial activities that follow a linear economy model based on design, manufacture, use and final disposal. As a feasible solution, Circular Economy (CE) model is considered a key strategy to enhance the overall sustainability performance of products, including strategies to improve the useful life of products and close flows of material in a circular path. In the measurement of circularity, existing sustainability indicators are oriented solely to single products and do not consider the product family approach, which involves the use of a common product platform comprised by constructive components or modules able to generate different product variants to satisfy a variety of customer requirements. Consequently, this paper proposes six indicators regarding material flow, reusability, reconfiguration, and functional performance. Such indicators are focused on measuring the circularity of product families respect the circularity of components among their product variants. A case study based on a family of prosthetic fingers is developed to demonstrate the implementation and usefulness of the proposed set of indicators. (C) 2018 Elsevier Ltd. All rights reserved.

关键词： 随机离散模型   Lyapunov函数   经济模型   渐近均方稳定  

摘要： 本文研究随机离散模型在一类经济模型上的应用。通过构造Lyapunov函数,得到模型在平衡点渐近均方稳定的充分条件,所得结果经过数值仿真进行验证。

关键词： Lotka-Volterra生物经济模型   分数阶   平衡点   Block-by-Block算法  

摘要： 对种群生物的肆意捕获会导致自然资源的严重破坏和生态环境的不稳定发展,如何把握好两者之间的平衡使得可再生资源达到最优开采是一个重要的课题,同时它对可持续发展产生直接影响。文章在提出分数阶带捕获的Lotka-Volterra生物经济模型的基础上,定性分析了该系统的平衡点附近的渐进稳定、分叉、混沌等产生的条件,得出了食饵种群持久生存前提下的最大经济效益;运用Block-by-Block算法对该系统平衡点的演化规律进行相应的时间序列图、相图等仿真研究。结果表明：随着捕获者经济效益的不同限制,该生物经济模型处于不同的演化状态,为生态资源合理应用提供理论依据。

摘要： A framework is developed to explain export participation among firms that produce differentiated products and may choose to exert costly effort to find foreign buyers. Export participation is linked to firm search costs, importer search costs, tariffs, the rate of contract breakdown, the distribution of bargaining power, and the degree of product differentiation. Propositions are derived that shed light on historic changes in export participation among firms while also generating hypotheses for further study. The model is applied to small U.S. food manufacturers and is shown to be able to explain changes in export participation among such firms.

关键词： Entrepreneurial philanthropy   Economics of education   University endowments  

摘要： A century ago, great entrepreneurs of American capitalism created major research universities. Today, donations are largely being channeled to the most successful universities. This paper explores the impact of entrepreneurial philanthropy on the creation and endowment of universities. It presents an integro-differential model that yields a nonlinear relation between university endowment and quality. Empirical tests validate the model, showing that university quality bears a nonlinear (quadratic) relationship with private giving (endowments).

关键词： economic MPC   stochastic nonlinear systems   probabilistic closed-loop stability  

摘要： This work focuses on the design of stochastic Lyapunov-based economic model predictive control (SLEMPC) systems for a broad class of stochastic nonlinear systems with input constraints. Under the assumption of stabilizability of the origin of the stochastic nonlinear system via a stochastic Lyapunov-based control law, an economic model predictive controller is proposed that utilizes suitable constraints based on the stochastic Lyapunov-based controller to ensure economic optimality, feasibility and stability in probability in a well-characterized region of the state-space surrounding the origin. A chemical process example is used to illustrate the application of the approach and demonstrate its economic benefits with respect to an EMPC scheme that treats the disturbances in a deterministic, bounded manner. (c) 2018 American Institute of Chemical Engineers AIChE J, 64: 3312-3322, 2018