Nonlinear response of a blade-stiffened graphite-epoxy panel with a discontinuous stiffener: Work in progress

The problem of calculating detailed stress distributions around discontinuities in buckled, composite structural components for use with the various analytical failure prediction techniques has not been thoroughly explored. The purpose here is the application of computational methods to the detailed stress analysis problem which is the focus of this session of the workshop. One approach to uncovering the difficulties of this type of analysis and to providing specific directions for future research in this area is a direct attack on the problem using currently available analysis tools. A candidate problem has been selected and experiences from calculating its structural response are described

THE ECONOMIC FACTORS INFLUENCING PRODUCERS' DEMAND FOR FARM MANAGERS

Results from a Tobit model showed a complementary relationship between marketing inputs and the decision to hire farm managers. According to the results, as farmers increase expenditure on marketing consultants and information systems, their expenditure on farm managers increase as well.Farm Management,

Crop Revenue and Yield Insurance Demand: A Subjective Probability Approach

A multinomial logit is utilized to model the choice of whether to purchase yield or revenue insurance using subjectively elicited survey data. Our results indicate that the demand for crop insurance is inelastic (-0.40), consistent with most earlier yield elasticity estimates, but the elasticity for choices between yield and revenue insurance is found to be relatively more elastic (-0.88).crop insurance, elasticities, multinomial logit model, revenue demand, subjective elicitation, survey, Agribusiness, Crop Production/Industries, Demand and Price Analysis, Q18,

Continued fraction solution of Krein's inverse problem

The spectral data of a vibrating string are encoded in its so-called characteristic function. We consider the problem of recovering the distribution of mass along the string from its characteristic function. It is well-known that Stieltjes' continued fraction provides a solution of this inverse problem in the particular case where the distribution of mass is purely discrete. We show how to adapt Stieltjes' method to solve the inverse problem for a related class of strings. An application to the excursion theory of diffusion processes is presented.Comment: 18 pages, 2 figure

A matrix-valued point interactions model

We study a matrix-valued Schr\"odinger operator with random point interactions. We prove the absence of absolutely continuous spectrum for this operator by proving that away from a discrete set its Lyapunov exponents do not vanish. For this we use a criterion by Gol'dsheid and Margulis and we prove the Zariski denseness, in the symplectic group, of the group generated by the transfer matrices. Then we prove estimates on the transfer matrices which lead to the H\"older continuity of the Lyapunov exponents. After proving the existence of the integrated density of states of the operator, we also prove its H\"older continuity by proving a Thouless formula which links the integrated density of states to the sum of the positive Lyapunov exponents

Target Markets for Grain and Cotton Marketing Consultants and Market Information Systems

This paper examines the use of market consultants and market information systems by grain and cotton producers. A model of producer demand for marketing information and consultants is proposed that decomposes price received into exogenous and endogenous components. The analysis is based on a survey of over 1,600 producers. The results suggest that expenditures on market information systems and market consultants are not independent and, more specifically, expenditures on marketing consultants substitute for expenditures on market information systems.expected utility, market information, marketing, risk, Tobit, Marketing,

Preference for Risk Management Information Sources: Implications for Extension and Outreach Programming

This article examines farmers’ preferences for various risk management information sources. Our results suggest that information from risk management experts, in-depth materials studied on their own, and popular press outlets tend to be preferred and are ranked highly by producers. Using a regression model to investigate farmer/farm attributes that affect preference for a particular risk management information source, we find that younger farmers with college education, higher leverage, assets greater than $1 million, risk-loving attitudes, and who have used professional services (marketing consultants) tend to prefer information from risk management experts, the Internet, and marketing clubs/other producers. On the other hand, producers who prefer self-study of educational materials and popular press information sources tend to be younger, with lower leverage levels, and have used fewer professional services.crop insurance, extension, information sources, outreach, risk management, Risk and Uncertainty,

Timescales of successful and failed subduction: insights from numerical modelling

The relatively short duration of the early stages of subduction results in a poor geological record, limiting our understanding of this critical stage. Here, we utilize a 2D numerical model of incipient subduction, that is the stage after a plate margin has formed with a slab tip that extends to a shallow depth and address the conditions under which subduction continues or fails. We assess energy budgets during the evolution from incipient subduction to either a failed or successful state, showing how the growth of potential energy, and slab pull, is resisted by the viscous dissipation within the lithosphere and the mantle. The role of rheology is also investigated, as deformation mechanisms operating in the crust and mantle facilitate subduction. In all models, the onset of subduction is characterized by high lithospheric viscous dissipation and low convergence velocities, whilst successful subduction sees the mantle become the main area of viscous dissipation. In contrast, failed subduction is defined by the lithospheric viscous dissipation exceeding the lithospheric potential energy release rate and velocities tend towards zero. We show that development of a subduction zone depends on the convergence rate, required to overcome thermal diffusion and to localise deformation along the margin. The results propose a minimum convergence rate of ∼ 0.5 cm yr−1 is required to reach a successful state, with 100 km of convergence over 20 Myr, emphasizing the critical role of the incipient stage