FABRICATION OF METALLIC-GLASS RIBBON REINFORCED GLASS-CERAMIC MATRIX COMPOSITES

Metallic-glass ribbon reinforced glass-ceramic matrix composites were fabricated by conventional wet pressing and sintering techniques. Some of the important aspects of composite fabrication are discussed. Variables such as binder content, compaction pressure and specimen size, and their interdependency on one another are discussed. The optimum processing conditions required to obtain the best specimens are described. The sintering temperature was also found to be very important. The sintering temperature not only controls the softening characteristics of the parent glass, but also affects the specimen distortion. Proper selection of the sintering temperature can ensure minimum distortion in the specimens, while at the same time retain the ease and efficiency of fabrication.     

Precipitation behavior in a medium carbon,ti-v-n microalloyed steel

The precipitation behavior of a medium carbon steel microalloyed with Ti, V, and N has been studied by analytical transmission electron microscopy in the as-cast and isothermally heat-treated states, as well as at different stages in the thermomechanical processing of the steel. Mixed (Ti,V) nitrides were found in all the structures, but there was no evidence for mixed carbonitride formation. The Hillert-Staffansson model was used to predict the composition of the nitrides as a function of tem-perature. Upon prolonged aging many of the precipitates became “fragmented” and were no longer single crystals. At the same time, the volume fraction of precipitates dropped, while their average Ti content increased. Possible explanations for this unexpected behavior are discussed in this article.     

Studies in biogas technology. Part II. Optimisation of plant dimensions

In this paper, the design basis of the conventional Khadi and Village Industries Commission biogas plants has been elucidated. It has been shown that minimisation of the cost of the gas holder alone leads to the narrow and deep digesters of conventional plants. If instead, the total capital cost of the gas holder plus digester is minimised, the optimisation leads to wide and shallow digesters, which are less expensive. To test this alternative, two prototype plants have been designed, constructed and operated. These plants are not only 25–40% cheaper, but their performance is actually slightly better than the conventional plants.     

Electroinitiated polymerization and copolymerization of phenylacetylene

Summary A linear conjugated polymer [(C₆H₅C=CH)] _n, with a trans rich, cis-trans copolymer structure results from the electropolymerization of phenylacetylene.     

Reliability of a 2-Unit Standby Redundant System with Repair, Maintenance and Standby Failure

A repairable 2-unit warm-standby system with repair and preventive maintenance is discussed. Two models are presented. In each of the models the mean time to system failure and the steady state availability are calculated. Some numerical calculations illustrate the results.     

A redundant system with non-instantaneous switchover and “preparation time” for the repair facility

This paper discusses two models of two-unit standby redundant systems in which the switchover time is a random variable and the repair facility is not available for a random time immediately after each repair completion. In model I the probability distributions of the life time of the online unit and switchover time are general while all the other distributions are exponential. Model II is a cold standby system in which the probability distributions of the “preparation time” of the repair facility is exponential and all the other distributions are general. Using the regeneration point technique the availability functions of the two systems are determined. Several special cases are also discussed.