Importance of thermal radiation for transition to flashover in a compartment fire will be demonstrated. A one zone model is developed with the objective of capturing the key mechanisms responsible for the initiation of flashover, i.e. physics of flashover. Thermal radiation is shown to be a key point and the inclusion of a three-dimensional radiation model is essential in the development of an accurate understanding of flashover. The heat transfer from the bounding wall of the compartment, the particulate concentration in the hot layer and the ventilation opening are shown to be key parameters which can lead to thermal instability and the resulting initiation of flashover. (C) 2004 Elsevier Ltd. All rights reserved.

Spatially-varying infiltration, geometry, and roughness along with spatially- and temporally-varying wetted perimeter effects on furrow advance and application uniformity were investigated. Extensive field-gathered infiltration, geometry, roughness, and advance/recession data was collected and used to calibrate and validate the simulation model.

Model simulation was done for both a single furrow as well as on a field-wide basis. Variable furrow inflow was incorporated into the field-wide analysis. Model simulations were evaluated to determine the importance to irrigation performance of each spatially-varying model input. Flow rate, infiltration function variability, furrow geometry and furrow roughness influence irrigation performance in decreasing order of importance.

The focus of this paper is on the demonstration that some rather well-known network-based formulation in operations research, that have heretofore largely gone unnoticed in activity-based travel research, offer a potentially powerful technique for advancing the general development of the activity-based modeling approach. These formulations can provide an analytical framework that unifies the complex interactions among the resource allocation decisions made by household in conducting their daily affairs outside the home, while preserving the utility-maximizing principle presumed to guide such decisions. A mathematical programming formulation is developed and used to identify the similarities and difference between traditional trip-based modeling methodologies and those pertaining to an activity-based approach. It is demonstrated that the two approaches are directly related.

The formulation of a multiple absorption coefficient zonal method (MACZM) is presented. The concept of generic exchange factors (GEF) is introduced. Utilizing the GEF concept, the MACZM is shown to be effective in simulating accurately the physics of radiative exchange in multidimensional, inhomogeneous, nongray media. The method can be applied directly to a fine-grid finite-difference or finite-element computation. It is thus suitable for direction implementation in an existing computational fluid dynamics (CFD) code for analysis of radiative heat transfer in practical engineering systems. The feasibility of the method is demonstrated by calculating the radiative exchange between a high-temperature (similar to 3,000K) molten nuclear fuel (UO2) and water (with a large variation in absorption coefficient from the visible to the infrared) in a highly three-dimensional and inhomogeneous environment simulating the premixing phase of a steam explosion.