Monopoly Distortions in Durability and Multi-Dimensional Quality

I show that Swan’s (1970) independence result requires a multiplicative interaction between durability and all other quality attributes. Because there is no compelling argument for a multiplicativity in quality, monopolists tend to distort durability, even with constant marginal costs. Distortions in durability and other quality aspects are aligned exactly when the marginal cost of quality do not increase too much with durability

Evaluation of Fly Ash Concrete Durability Containing Class II Durability Aggregates, July 1986

Fly ash was used in this evaluation study to replace 15% of the cement in Class C-3 concrete paving mixes. One Class "c" ash from Iowa approved sources was examined in each mix. Substitution rate was based on 1 to 1 basis, for each pound of cement removed 1.0 pound of ash was added. The freeze/thaw durability of the concrete studied was not adversely affected by the presence of fly ash. This study reveals that the durability of the concrete test specimens made with Class II durability aggregates was slightly increased in all cases by the substitution of cement with 15% Class "c" fly ash. In all cases durability factors either remained the same or slightly improved except for one case where the durability factor decreased from 36 to 34. The expansion decreased in all cases

Collusion and Durability

We develop a model to show that cartels that produce goods with lower durability are easier to sustain implicitly. This observation gen- erates the following results: 1) implicit cartels have an incentive to pro- duce goods with an inefficiently low level of durability; 2) a monopoly or explicit cartel is welfare superior to an implicit cartel; 3) welfare is non-monotonic in the number of firms; 4) a regulator may demand inefficiently high levels of durability to prevent collusion

Theoretical backgrounds of durability analysis by normalized equivalent stress functionals

Generalized durability diagrams and their properties are considered for a material under a multiaxial loading given by an arbitrary function of time. Material strength and durability under such loading are described in terms of durability, safety factor and normalized equivalent stress. Relations between these functionals are analysed. We discuss some material properties including time and load stability, self-degradation (ageing), and monotonic damaging. Phenomenological strength conditions are presented in terms of the normalized equivalent stress. It is shown that the damage based durability analysis is reduced to a particular case of such strength conditions. Examples of the reduction are presented for some known durability models. The approach is applicable to the strength and durability description at creep and impact loading and their combination

A reverse chemical ecology approach to explore wood natural durability

The natural durability of wood species, defined as their inherent resistance to wood‐destroying agents, is a complex phenomenon depending on many biotic and abiotic factors. Besides the presence of recalcitrant polymers, the presence of compounds with antimicrobial properties is known to be important to explain wood durability. Based on the advancement in our understanding of fungal detoxification systems, a reverse chemical ecology approach was proposed to explore wood natural durability using fungal glutathione transferases. A set of six glutathione transferases from the white‐rot Trametes versicolor were used as targets to test wood extracts from seventeen French Guiana neotropical species. Fluorescent thermal shift assays quantified interactions between fungal glutathione transferases and these extracts. From these data, a model combining this approach and wood density significantly predicts the wood natural durability of the species tested previously using long‐term soil bed tests. Overall, our findings confirm that detoxification systems could be used to explore the chemical environment encountered by wood‐decaying fungi and also wood natural durability

Load profile effect on durability of proton exchange membrane fuel cells

Proton Exchange Membrane Fuel Cells (PEMFC) are a promising technology for substitution of hydrocarbon powerdrives and battery based electrical supply systems. However, below-required durability is still an important factor that hinders its widespread use, thus, novel operating approaches are required to surpass this shortcoming. The present abstract presents a line of research directed towards the of analysis and definition of load profile characteristics in order to design controllers and operation strategies that optimize cell efficiency and durability. Degradation of the catalyst layer, commonly composed of platinum supported on carbon (Pt/C), mainly due to platinum loss by oxidation/dissolution and the resulting reduction of Electrochemical Active Surface Area (ECSA), is the main issue reducing the durability of PEMFC.Peer ReviewedPostprint (author's final draft

Fatigue strength and durability analysis by normalised equivalent stress functionals

Generalised fatigue durability diagrams are considered for a material under multi-axial loading given by a (non-regularly) oscillating function of time. Phenomenological strength conditions under such loading are presented in terms of the normalised equivalent stress functionals both for quasi-ductile rupture and brittle fracture. Examples of the functionals are presented for some known and new durability models including those sensitive to the load sequence. Some complex strength conditions applicable to the durability description at fatigue, creep, dynamic loading and their combinations are presente

Tree crown architecture: a tool for decay resistance evaluation

The variability of natural durability contributes to the bad perception of some wood end-users. In our search, we need to adjust our methods and strategies to estimate natural durability and extract higher value from wood resources. Architectural analysis is essentially a detailed, multilevel, comprehensive and dynamic approach to plant development. Numerous biological process which impact some wood properties like durability are linked with tree development. A better understanding of the interelationship between tree physiology through tree achitecture analysis and natural durability could be an approach to predict this property. This study explore the relation between the crown architecture, decay resistance and wood extractives in Dicorynia guianensis in order to propose tree crown architecture as an evalution decay resistance tool. (Résumé d'auteur

Collusion and Durability

We make the observation that cartels which produce goods with lower durability are easier to sustain implicitly. This observation generates the following results: 1) implicit cartels have an incentive to produce goods with an inefficiently low level of durability; 2) a monopoly or explicit cartel is welfare superior to an implicit cartel; 3) welfare is non--monotonic in the number of firms; 4) a regulator may demand inefficiently high levels of durability to prevent collusion.

Collusion and Durability

We develop a model to show that cartels that produce goods with lower durability are easier to sustain implicitly. This observation gen- erates the following results: 1) implicit cartels have an incentive to pro- duce goods with an inefficiently low level of durability; 2) a monopoly or explicit cartel is welfare superior to an implicit cartel; 3) welfare is non-monotonic in the number of firms; 4) a regulator may demand inefficiently high levels of durability to prevent collusion.cartels; collusion; durability