87,053 research outputs found
A Posteriori Error Estimates for Energy-Based Quasicontinuum Approximations of a Periodic Chain
We present a posteriori error estimates for a recently developed
atomistic/continuum coupling method, the Consistent Energy-Based QC Coupling
method. The error estimate of the deformation gradient combines a residual
estimate and an a posteriori stability analysis. The residual is decomposed
into the residual due to the approximation of the stored energy and that due to
the approximation of the external force, and are bounded in negative Sobolev
norms. In addition, the error estimate of the total energy using the error
estimate of the deformation gradient is also presented. Finally, numerical
experiments are provided to illustrate our analysis
Plasmonic Light Trapping in an Ultrathin Photovoltaic Layer with Film-Coupled Metamaterial Structures
A film-coupled metamaterial structure is numerically investigated for
enhancing the light absorption in an ultrathin photovoltaic layer of
crystalline gallium arsenide (GaAs). The top subwavelength concave grating and
the bottom metallic film could not only effectively trap light with the help of
wave interference and magnetic resonance effects excited above the bandgap, but
also practically serve as electrical contacts for photon-generated charge
collection. The energy absorbed by the active layer is greatly enhanced in the
film-coupled metamaterial structure, resulting in significant enhancement on
the short-circuit current density by three times over a free-standing GaAs
layer at the same thickness. The results would facilitate the development of
next-generation ultrathin solar cells with lower cost and higher efficiency
Castelnuovo-Mumford Regularity in Biprojective Spaces
We define the concept of regularity for bigraded modules and bigraded
polynomial ring. In this setting we prove analogs of some of the classical
results on -regularity for graded modules over polynomial algebras.Comment: 17 Pages, 2 figure
Curvilinear Base Points, Local Complete Intersection and Kozsul Syzygies in Biprojective Spaces
We prove analogs of results of Cox/Schenck on the structure of certain ideals
in the bigraded polynomial ring k[s,u;t,v].Comment: 12 page
Shelf Space Fees and Inter-Brand Competition
When in-store display influences consumer choices, shelf space allocation can be strategically used by retailers to extract payments from manufacturers. The paper finds that manufacturers with more popular brands have higher willingness-to-pay for the premium shelf spaces of supermarkets. Shelf space fees soften inter-brand competition and result in higher sale-weighted average retail price as well as inter-brand price differences. The fees increase the industry profit but lower the upstream profit. Both the aggregate consumer surplus and social welfare are negatively affected. This paper suggests that even when the fees do not drive small manufacturers out of retail stores, they might still be anti-competitive.Antitrust, In-store display, Shelf space fee, Retail market, Slotting allowance
Slotting Allowances and Retailer Market Power
This paper uses a bilateral oligopoly model to study the slotting allowances in retailing industries. There are two symmetric manufacturers competing in the upstream market. In the downstream, there are a large retailer with considerable market share, and many small retailers with insignificant market shares. Suppose that only the large retailer is able to require slotting allowances. The retailers engage in price competition with spatial differentiation. The model suggests that the large retailer uses slotting allowances to capitalize its market power. By requiring slotting fees, the large retailer can raise the wholesale prices faced by the competing small retailers, and therefore lower their profit margins and market shares. The large retailer, on the contrary, achieves greater profit margins and market share. The lump sum part of the slotting fees is wholly bore by the manufacturers. But the slotting fees that are linear to the sales are actually bore by the competing small retailers and their customers. In this sense, requiring slotting allowance is an exclusionary strategy of the large retailer.Exclusionary strategy, Market power, Slotting allowance
Uncertain Consumer Tastes and Two-Part Tariff
A service provider sells to homogenous risk-averse consumers through a two-part tariff. The consumers have uncertain tastes toward the service. They subscribe the service before the uncertainty resolves. In contrast with the common view that a monpolist's optimal two-part tariff for homogeneous consumers should entail a usuage rate equalising to the firm's marginal production cost, I show that when consumers have uncertain tastes, the service provider's optimal two-part tariff entails a usuage rate that is greater than the marginal cost.uncertain taste, risk aversion, service pricing, two-part tariff
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