Heat transfer through porous multiphase systems: measurement, modelling and application in printing of coated papers

This work examines the thermal transfer through porous media by means of measurement of the effective thermal conductivity and modelling of the structural parameters. While most of the work is of a general nature, the porous media in focus are pigment plus latex binder systems as used for paper coatings. As such, the application field of thermal effects in printing is discussed. At first the use of a dynamic measurement method for the thermal conductivity of porous coating pigment binder systems in the form of tablets is evaluated. In addition, a Lumped Parameter Model is developed to analyse the measured thermal conductivities in terms of the material volume fractions and their structural configuration. The model therefore uses two independent structural parameters instead of porosity alone as the governing parameter. This enables a discussion following modelling approaches adopting parameter modelling and structural modelling. A combination of both is used to discuss the solid-solid connectivity of pigment binder systems. It is shown by the model parameter of pigment connectivity that a disruption of the pigment packing already at low concentrations of binder occurs related to surface and colloid chemistry factors which cause the binder to accumulate first at pigment nodal points. The analysis of different pigment binder systems shows that, due to the presence of two interacting solid phases, the effective thermal conductivity cannot be modelled by using porosity and pore structure alone, but also requires the additional parameter of dual solid phase connectivity. It is proposed, therefore, that a combination of pore structure analysis and thermal conductivity measurement can be used to identify and parameterise subtleties in interactive particulate systems. For the application of toner fusing in electrophotography it is shown that a thermally insulating coating layer leads to a concentration of the fusing energy on the surface, thus aiding the fusing/adhesion development of the toner while shielding the base paper from undesired heating. In the heatset web-offset drying process, an insulating precoating in combination with liquid barrier properties can lead to a similar shielding of the base paper and thus helps to maintain an even moisture profile effectively reducing the waving/fluting tendency

Fused deposition of ceramics: a comprehensive experimental, analytical and computational study of material behavior, fabrication process and equipment design

Customer-driven product customization and continued demand for cost and time savings have generated a renewed interest in agile manufacturing based on improvements on Rapid Prototyping (RP) technologies. The advantages of RP technologies are: 1. ability to shorten the product design and development time, 2.) suitability for automation and decrease in the level of human intervention, 3.) ability to build many geometrically complex shapes. A shift from âprototypingâ to âmanufacturingâ necessitates the following improvements: flexibility in choice of materials; part integrity and built-in characteristics to meet performance requirements; dimensional stability and tolerances; improved surface finish. A project funded by ONR has been undertaken to develop an agile manufacturing technology for fabrication of ceramic and multi-component parts to meet various needs of the Navy, such as transducers, etc. The project is based on adaptation of a layered manufacturing concept since the program required that the new technology be developed based on a commercially available RP technology. Among various RP technologies available today, Fused Deposition Modeling (FDM) has been identified as the focus of this research because of its potential versatility in the choice of materials and deposition configuration. This innovative approach allows for designing and implementing highly complex internal architectures into parts through deposition of different materials in a variety of configurations in such a way that the finished product exhibit characteristics to meet the performance requirements. This implies that, in principle, one can tailor-make the assemble[stet] of materials and structures as per specifications of an optimum design. The program objectives can be achieved only through accurate process modeling and modeling of material behavior. Oftentimes, process modeling is based on some type of computational approach where as modeling of material behavior is based on extensive experimental investigations. Studies are conducted in the following categories: flow modeling during extrusion and deposition; thermal modeling; flow control during deposition; product characterization and property determination for dimensional analysis; and development of a novel technology based on a mini-extrusion system. Studies in each of these stages have involved experimental as well as analytical approaches to develop a comprehensive modeling.Ph.D., Materials Engineering -- Drexel University, 200

Energy: A continuing bibliography with indexes (Issue 29)

This bibliography lists 1360 reports, articles, and other documents introduced into the NASA scientific and technical information system from January 1, 1981 through March 31, 1981

Energy: A continuing bibliography with indexes, issue 32

This bibliography lists 1316 reports, articles, and other documents introduced into the NASA scientific and technical information system from October 1, 1981 through December 31, 1981

Energy: A continuing bibliography with indexes, issue 19

A bibliographical list of 1339 reports, articles, and other documents introduced into the NASA scientific and technical information system from July 1, 1978 through September 30, 1978 are presented

Energy: A continuing bibliography with indexes, supplement 16, January 1978

This bibliography lists 1287 reports, articles, and other documents introduced into the NASA scientific and technical information system from October 1, 1977 through December 31, 1977

Energy: A continuing bibliography with indexes, issue 34

This bibliography lists 1015 reports, articles, and other documents introduced into the NASA scientific and technical information system from April 1, 1981 through June 30, 1981