On the Nature of Capital Adjustment Costs

This paper studies the nature of capital adjustment at the plant-level. We use an indirect inference procedure to estimate the structural parameters of a rich specification of capital adjustment costs. In effect, the parameters are optimally chosen to reproduce the nonlinear relationship between investment and profitability that we uncover in the plant-level data. Our findings indicate that a model which mixes both convex and nonconvex adjustment costs with irreversibility fits the data best.

Fiber optic control system integration

A total fiber optic, integrated propulsion/flight control system concept for advanced fighter aircraft is presented. Fiber optic technology pertaining to this system is identified and evaluated for application readiness. A fiber optic sensor vendor survey was completed, and the results are reported. The advantages of centralized/direct architecture are reviewed, and the concept of the protocol branch is explained. Preliminary protocol branch selections are made based on the F-18/F404 application. Concepts for new optical tools are described. Development plans for the optical technology and the described system are included

Decision Support Systems in Australian Agriculture: State of the Art and Future Development

This paper reports and discusses the results of a survey conducted with experts working in the field of decision support systems (DSS) in Australian agriculture. It also reviews the literature on DSS in the light of these experts' responses. The findings from this survey have consolidated our understanding of the current state of DSS in Australian agriculture. The uptake of DSS by farmers has been slow and various issues said to be contributing to this include fear of using computers, time constraints, poor marketing, complexity, lack of local relevance, lack of end-user involvement, and mismatched objectives between developers and users. The future prospect for the development of DSS was generally regarded to be poor. Never-the-less, the authors believe that new DSS which embrace the suggested criteria could be widely accepted by farmers. These criteria mean that to be widely used by farmers, any successful DSS needs to address widespread problems: they need to be location specific, and gain strong support from initial users. They also need to be simple to use, relevant, effective, low cost, and user friendly and it is most likely that farmers would have been involved in their development. We believe that farmers' personalities, and their attitudes towards risk management and decision making, will influence the pattern of adoption of DSS in Australian agriculture while the intergenerational change that is occurring in the management of Australian farms is a positive factor that may encourage more widespread use of these tools.DSS, farmers' decision-making, expert opinion, management decisions, Farm Management, D7, D8, Q12, Q13, Q16,

Finite element analysis of gradient coil deformation and vibration in NMR microscopy

Resolution degradation due to gradient coil deformation and vibration in NMR microscopy is investigated using finite element analysis. From the analysis, deformations due to the Lorentz force can be as large as 1-10 μm depending on the gradient strength and coil frame material. Thus, these deformations can be one of the major resolution limiting factors in NMR microscopy. Coil vibration, which depends on the input current waveform and resolution degradation due to time-variant deformation and time-invariant deformation are investigated by numerical simulations

Effects of low energy proton, electron, and simultaneously combined proton and electron environments in silicon and GaAs solar cells

Degradation of silicon and GaAs solar cells due to exposures to low energy proton and electron environments and annealing data for these cells are discussed. Degradation of silicon cells in simultaneously combined electron and low energy proton environments and previous experimental work is summarized and evaluated. The deficiencies in current solar array damage prediction techniques indicated by these data and the relevance of these deficiencies to specific missions such as intermediate altitude orbits and orbital transfer vehicles using solar electric propulsion systems are considered

Dynamics of trusses having nonlinear joints

The transient analysis of trusses having nonlinear joints can be accomplished using the residual force technique. The technique was applied a two degree of freedom spring mass system, a four bay planar truss, and an actual ten bay deployable truss. Joints chosen for analysis were the nonlinear gap joints and the linear Voigt joints. Results from the nonlinear gap analyses generally indicate that coupling between the modes can display some interesting effects during free vibration. One particularly interesting effect was that the damping of the structure appeared to be higher than could be accounted for from modal damping alone. Energy transferral from the lower to the higher modes was found to exist as a result of the modal coupling. The apparently increased damping was due to the fact that the energy transferred to the higher modes is inherently dissipated more quickly. Another interesting phenomenon was that the lower modes could drive the higher modes even during free vibration and that these modes could display a rather large quasi-steady state behavior even when modal damping was present. Gaps were also found to increase the amplitude and period of the free vibration response as expected

Conceptual mechanization studies for a horizon definition spacecraft structures and thermal subsystem

Conceptual mechanization for horizon definition spacecraft structures and thermal subsystem - spin-stabilized, hexagonal cylinder for launch of two-stage Improved Delta /DSV-3N

Improving Tracer Particle Surface Properties for Wind Tunnel Research

The surface properties of micron size polystyrene latex microspheres (PSLs) modified with quaternary alkylammonium (QA) surfactants were investigated, with a focus on the relationship between surface chemistry and adhesion. These investigations were motivated by the need to develop non-fouling tracer particles for wind tunnel studies. The goals were to relate the work of adhesion between particles and substrates to the type and amount of QA modifier in order to optimize the performance of PSL tracers. Surfactant-free emulsion polymerization (SFEP) can produce PSLs for wind tunnel tracers. Covalentlybound charged groups (derived from the initiator) stabilize PSL surfaces in water. This work used PSLs with anionic surface groups. Previous studies indicated that surface-bound charged groups on PSLs have a significant impact on their interfacial energy. Modifying charged surface groups therefore offers a method to modulate PSL interfacial properties. In this work, PSLs and films were modified by adsorption of QA surfactants

The ontology of causal process theories

There is a widespread belief that the so-called process theories of causation developed by Wesley Salmon and Phil Dowe have given us an original account of what causation really is. In this paper, I show that this is a misconception. The notion of "causal process" does not offer us a new ontological account of causation. I make this argument by explicating the implicit ontological commitments in Salmon and Dowe's theories. From this, it is clear that Salmon's Mark Transmission Theory collapses to a counterfactual theory of causation, while the Conserved Quantity Theory collapses to David Fair's phsyicalist reduction of causation