Herein is contained details of a comprehensive finite element survey and experimental investigation into the buckling and postbuckling characteristics of thin laminated square Carbon-Epoxy panels with various cutout geometries, subjected to uniaxial compression. The plate edges are considered to be fully fixed with constant edge displacement loading. The panels were quasi isotropic in nature with a stacking sequence of (0/90/±45)2,. Square, circular and elliptical centrally located cutouts were considered with cutout dimension/panel widths ranging from 0.1 to 0.7 in increments of 0.1. Eccentrically located circular and square cutouts were considered for cutout dimension/panel width ratios ranging from 0.1 to 0.4 with vertical and horizontal eccentricity varying from 0 to 20% of the panels width. Multiple circular cutouts with cutout dimension/panel width ranging from 0 to 0.3 with separation distance/panel width ratios ranging from 0.2 to 0.65. A finite element eigenvalue analysis was adopted to determine the critical buckling loads and buckle mode shapes for the panels. The postbuckling response of the panels were investigated by adopting a non-linear finite element analysis approach using an Incremental Newton-Raphson Iterative solution scheme. A limited experimental test programme was undertaken to act as verification to the finite element solutions. A purpose built buckling rig was designed and manufactured for the purposes of the tests. It has been confirmed that the critical buckling loads for centrally located circular and square cutouts initially reduces as the cutout size increases. After reaching a minimum value it thereafter increases with large cutout sizes, the exact changeover point being dependant upon the shape of the cutout. The orientation of ellipse major axis significantly affects the critical buckling load of a panel. A horizontally aligned ellipse exhibits similar behaviour as that to a circular or square cutout. However when the major axis is rotated relative to the horizontal axis its buckling capacity reduces monotonically till it has a buckling load less than that for an unperforated panel when vertical aligned. It has been shown when a circular cutout is eccentrically placed in a panel, for small cutout sizes the buckling load reduces with horizontal eccentricity while a small increase is experienced for vertical eccentricity. Multiple circular cutouts significantly reduce the buckling capacity of the panel for all cutout sizes and separation distances. Initial geometric imperfection in the panel does not affect the critical buckling load significantly. The postbuckled response of such panels are also insensitive to the magnitude of imperfection. Panels with circular, square and elliptical cutouts exhibit substantial postbuckled strength. The post buckling response of such panels are insensitive to cutout geometry shape.

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Life cycle analysis is carried out for 11 predicted configurations of pyrolysis biochar systems to determine greenhouse gas balance, using an original spreadsheet model. System parameters reflect deployment in Scotland, and results demonstrate that all major crop and forestry feedstocks offer greater GHG abatement than other bioenergy technologies, regardless of system configuration. Sensitivity analysis determines the relative importance of uncertain variables in the model and optimistic to pessimistic scenarios are used for system operation. Slow pyrolysis is compared to fast pyrolysis and biomass co-firing for GHG abatement and electricity production, using various scenarios for availability of indigenous Scottish feedstocks.

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Agricultural census data have been identified to possess the potential to provide constraints on carbon uptake by croplands at the regional scale. In this study, we build on previous efforts and further assess this potential quantitatively by comparing 1) fractional cropland coverage in southwestern Ontario, Canada derived from agricultural statistics against three different remotely sensed land cover maps; and 2) carbon uptakes determined from agricultural data with simulations generated by a satellite data-driven biospheric model. In addition, we assimilated the census data-derived carbon uptakes with modeled estimates in a Bayesian inverse approach to determine if and by how much constrain the crop data can provide, as exhibited by uncertainty reductions. Uncertainties in census data-derived gross primary production (GPP) estimates are carefully quantified using a Monte Carlo simulation. In general, results from the fractional cropland coverage comparison indicate significant value of the agricultural census data by revealing biases in the spatial distribution of croplands, as found in all three of the satellite land cover products. However, we find that the carbon uptake values derived from crop harvested records are still subject to significant uncertainties that have been underestimated or neglected altogether in past studies. The Monte Carlo simulation suggests that the largest source of uncertainty can be traced to errors in the growth efficiency, followed by harvest production records, and then the harvest index. As result, attention must be paid to such errors when using the agricultural census data for carbon accounting purposes or to provide constraints to simulations of crop carbon uptake.

Thesis (M.S.)--Ohio University, August, 2000. / Title from PDF t.p.