Development of models and online diagnostic monitors of the high-temperature corrosion of refractories in oxy/fuel glass furnaces : final project report.

This report summarizes the results of a five-year effort to understand the mechanisms and develop models that predict the corrosion of refractories in oxygen-fuel glass-melting furnaces. Thermodynamic data for the Si-O-(Na or K) and Al-O-(Na or K) systems are reported, allowing equilibrium calculations to be performed to evaluate corrosion of silica- and alumina-based refractories under typical furnace operating conditions. A detailed analysis of processes contributing to corrosion is also presented. Using this analysis, a model of the corrosion process was developed and used to predict corrosion rates in an actual industrial glass furnace. The rate-limiting process is most likely the transport of NaOH(gas) through the mass-transport boundary layer from the furnace atmosphere to the crown surface. Corrosion rates predicted on this basis are in better agreement with observation than those produced by any other mechanism, although the absolute values are highly sensitive to the crown temperature and the NaOH(gas) concentration at equilibrium and at the edge of the boundary layer. Finally, the project explored the development of excimer laser induced fragmentation (ELIF) fluorescence spectroscopy for the detection of gas-phase alkali hydroxides (e.g., NaOH) that are predicted to be the key species causing accelerated corrosion in these furnaces. The development of ELIF and the construction of field-portable instrumentation for glass furnace applications are reported and the method is shown to be effective in industrial settings

Prospects for Cable in the 100 Largest Television Markets

The Federal Communications Commission, hoping "to get cable moving without jeopardizing over-the-air broadcasting," recently proposed rules that would allow cable systems in the 100 largest television markets to carry a limited number of distant signals. This paper employs a nonlinear model of cable penetration to assess the effect of the proposed rules. The model is developed using a sample of 63 cable systems located where several signals can be received over the air with no particular reception problems. Applying the model to some typical top-100 market situations, the author concludes that the proposed rules "will meet the Commission's objective. But more is necessary to keep cable moving, because the rules by themselves are probably not sufficient to make cable profitable in most of the top-100 markets. To succeed in the cities, cable must attract customers with new services in addition to the traditional package of better reception plus distant signals."

New Television Networks

A simple model of television network competitive behavior is used to explore the prospects for new networks. Overall, the prospects are not very bright. A fourth network with complete, unhandicapped, nationwide coverage could coexist profitably with the existing three, but the industry would need a severe regulatory restructuring to make such a network possible. Most networks with incomplete coverage would not be profitable, including networks of existing independent stations, cable systems, new VHF "drop-in" stations (suggested by an Office of Telecommunications Policy report), or combinations of these. A network using existing independents plus new UHF stations constructed to give it nationwide coverage may become profitable as the UHF reception handicap continues to drop. None of the new networks considered threatens the profitability of the existing three networks.