Computational Representation of Constitutive Relations for Porous Material
Computational Representation of Constitutive Relations for Porous Material

Author: Lynn Seaman

Publisher:

Published: 1974

Total Pages: 170

ISBN-13:

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Porous materials are used as a protection against x-radiation because of their ability to minimize the stress generated by the radiation and to attenuate that stress as it propagates. For accurate design of this protection, wave propagation calculations are made to simulate the radiation deposition, stress generation, propagation, and spallation caused by stress waves. For such a calculation it is necessary to have a constitutive relation (stress-strain-energy relation, or equation of state) that describes the material's response to heating and to compressive and tensile loading. The objective of this report is to document a set of constitutive relations that provide for: Elastic and plastic compaction loading with rate dependence; Heating or cooling that can occur simultaneously with loading; Unloading and rate-dependent fracture; and, Melting and vaporization, with explicit treatment of solid, liquid, vapor, and mixed phases. Accompanying these relations is a user's manual that includes a derivation of the equations for the model and procedures for using it in Lagrangian wave propagation computer programs.

Innovative Polymeric Adsorbents
Innovative Polymeric Adsorbents

Author: Kyoichi Saito

Publisher: Springer

Published: 2018-04-05

Total Pages: 193

ISBN-13: 9811085633

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This book presents the reader with a story-based narrative of discovery and development of radiation-induced graft polymerization. The report presented here accomplishes this by relating the inspiring account of research and development based on long-term collaboration among a professor, an engineer, and an entrepreneur. Their goal, ultimately successful, was to come up with a method for grafting functional polymer chains onto existing trunk polymers. The desired outcome was to produce feasible forms for practical use as adsorbents such as porous hollow-fiber membranes, porous sheets, nonwoven fabrics, and fibers. Adsorbents that specifically and efficiently bind to target ions and molecules are essential for capturing uranium species in seawater and antibody drugs in biological fluids and for removing metal ions from ultrapure water and radioactive cesium ions from contaminated water. This unique volume, with its clearly written text and many illustrative figures and diagrams, demonstrates the advantages of the high-adsorption capacity and rate and the easy handling of new polymeric adsorbents over conventional adsorbents. The dynamic behavior of graft chains as described here is certain to appeal especially to chemists, physicists, and material scientists as well as to other readers with an interest in this valuable subject.

A Parametric Analysis of a Coupled Chemistry-radiation Model in Porous Media
A Parametric Analysis of a Coupled Chemistry-radiation Model in Porous Media

Author: Farid C. Christo

Publisher:

Published: 2000

Total Pages: 26

ISBN-13:

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Executive Summary: The accuracy and reliability of numerical models to predict combustion and thermal radiation characteristics of gaseous and solid fuels, relies heavily on their ability to adequately couple the various transport mechanisms in the process. These processes usually include chemical reactions, turbulent mixing, and radiation heat transfer. The work presented here is aimed at developing a numerical model (ChemRad) to calculate the laminar combustion inside porous media, accounting for detailed chemistry and radiative heat transfer. This study is part of an ongoing research program aiming at developing computational capabilities to model the performance of infrared (IR) emitting devices. More specifically to assess the potential use of porous radiant burner technologies in the design of a new generation of IR tracking and decoy devices. The numerical model presented here has a unique capability for handling complex and detailed chemical kinetics accurately and efficiently, hence eliminating chemistry-related errors in the solution. The greatest source of errors in the model, however remains the uncertainty in some input parameters that describe the microstructure and optical properties of the porous medium. Accordingly a systematic analysis of the solution's sensitivity (or lack of it) to variations in nine input parameters has been conducted. Three of the parameters; voidage, tortuosity, and area density represent the microstructural properties of the porous medium, and the remaining six parameters describe the optical properties of the porous material. These are the emissivity, reflectivity, single scattering albedo, extinction coefficient, forward- and backward radiation scattering fractions. It has been found that the most influential parameters (in order of significance) are the area density, voidage, reflectivity, and the forward-to-backward scattering ratio. The capability of the ChemRad model to capture the combustion characteristics has been successfully demonstrated by a favourable agreement between the model predictions and the experimental results, which are documented in a separate technical report to be published soon.earning and res.these central o.