Randomized Local Model Order Reduction

In this paper we propose local approximation spaces for localized model order reduction procedures such as domain decomposition and multiscale methods. Those spaces are constructed from local solutions of the partial differential equation (PDE) with random boundary conditions, yield an approximation that converges provably at a nearly optimal rate, and can be generated at close to optimal computational complexity. In many localized model order reduction approaches like the generalized finite element method, static condensation procedures, and the multiscale finite element method local approximation spaces can be constructed by approximating the range of a suitably defined transfer operator that acts on the space of local solutions of the PDE. Optimal local approximation spaces that yield in general an exponentially convergent approximation are given by the left singular vectors of this transfer operator [I. Babu\v{s}ka and R. Lipton 2011, K. Smetana and A. T. Patera 2016]. However, the direct calculation of these singular vectors is computationally very expensive. In this paper, we propose an adaptive randomized algorithm based on methods from randomized linear algebra [N. Halko et al. 2011], which constructs a local reduced space approximating the range of the transfer operator and thus the optimal local approximation spaces. The adaptive algorithm relies on a probabilistic a posteriori error estimator for which we prove that it is both efficient and reliable with high probability. Several numerical experiments confirm the theoretical findings.Comment: 31 pages, 14 figures, 1 table, 1 algorith

TRACEABILITY AND INFORMATION TECHNOLOGY IN THE MEAT SUPPLY CHAIN: IMPLICATIONS FOR FIRM ORGANIZATION AND MARKET STRUCTURE

The traditional food supply chain is arranged as a complex array of producers, handlers, processors, manufacturers, distributors, and retailers. As the food supply chain grew in complexity over time, little emphasis was placed on preserving information regarding the origin of raw materials and their transformation, often by multiple handlers, into consumer-ready products. This paper provides case illustrations of the implementation of information systems for support of traceability in Europe. Observations on these firms coupled with the literature on information asymmetry and transactions costs is used to provide insights into how traceability implementation might affect U.S. meat-industry structure.Agribusiness, Industrial Organization,

TRACEABILITY, TRADE AND COOL: LESSONS FROM THE EU MEAT AND POULTRY INDUSTRY

The traditional food supply chain is arranged as a complex array of producers, handlers, processors, manufacturers, distributors, and retailers. As the food supply chain grew in complexity over time, little emphasis was placed on reserving information regarding the origin of raw materials and their transformation, often by multiple handlers, into consumer ready products. This paper provides case illustrations of the implementation of information systems for support of traceability in Europe. Emphasis is on the firm level costs and benefits as well as the broader market structure and governance issues inherent in information economics of the firm.traceability, economics of the firm, information systems, internet, food supply chain, Food Consumption/Nutrition/Food Safety, International Relations/Trade, Livestock Production/Industries,

3D modelling of Ti–6Al–4V linear friction welds

Linear friction welding (LFW) is a solid-state joining process that significantly reduces manufacturing costs when fabricating Ti–6Al–4V aircraft components. This article describes the development of a novel 3D LFW process model for joining Ti–6Al–4V. Displacement histories were taken from experiments and used as modelling inputs; herein is the novelty of the approach, which resulted in decreased computational time and memory storage requirements. In general, the models captured the experimental weld phenomena and showed that the thermo-mechanically affected zone and interface temperature are reduced when the workpieces are oscillated along the shorter of the two interface contact dimensions. Moreover, the models showed that unbonded regions occur at the corners of the weld interface, which are eliminated by increasing the burn-off

E-COMMERCE: A NEW BUSINESS MODEL FOR THE FOOD SUPPLY/DEMAND CHAIN

The use of electronic commerce for quality control and cost cutting efficiencies by the food and agricultural industries in the United States is the focus of this paper. The food industry engages in e-commerce through 1.) Internet shopping for consumers called business-to-consumer (B2C) e-commerce 2.) Business-to-business (B2B) Internet market discovery exchanges used by food suppliers at any point in the supply chain, and 3.) Business-to-business (B2B) relationships that reduce costs and increase efficiencies in the procurement, storage and delivery of food to retail stores or distribution centers. This third use of e-commerce is the most highly developed and widely adopted. It allows retailers to share information about consumers' purchases and preferences with food manufacturers and farmers and for tracking food products' characteristics, source, and movement from production to consumer. This circle of information allows high quality and consistent products to be consumed at lower prices. This paper is about the development of e-commerce in the food industry, the economic concepts and goals that it meets, and the changes it brings to the industry. E-commerce both fosters and demands vertical coordination. It favors consolidation of firms. It changes the business culture from one of adversarial relationships to one of cooperation and trust. It changes the historical supply chain into a supply/demand loop while it lowers the cost of food. Policy issues arise around monopoly power, privacy, a diminution of variety, and the demise of small, undercapitalized firms.Industrial Organization, Marketing,

After the Bubble: The Survival and Ownership of Internet Marketplaces for Farmers and Agribusiness

This paper presents a theory of how industry structure and beliefs about Internet marketplace use have driven choice and ownership of marketplaces. The theory's predictions suggest that surviving Internet marketplaces will be those with strong historical linkages in an industry and those owned by or affiliated with major commodity buyers. Comparisons of these predictions with actual outcomes provide validation of the theory. Where predictions differ from results, observations are made as to the nature of the deviations.agricultural markets, electronic commerce, Internet markets, network externalities, technology adoption, Agribusiness,