Preset Conditions Research Articles

Growing Single Crystal Corundum Tubes by Verneuil Technique in Stable Conditions

AbstractThe authors analyze the process of corundum tube growth by modified Verneuil's method from the viewpoint of its stability. The article shows that the process is stable in the case of thin‐walled tubes and becomes unstable when the tube wall thickness exceeds a certain critical value which is known to be below the capillary constant. The critical thickness of the tube wall grows with a decrease of the heat flux density differential from the burner along the furnace muffle and with an increase of the tube's outer radius.As a result of a process of crystal growth under preset conditions constant cross‐section single crystaal corundum tubes have been obtained.

On the Microstructure of Copolymer Chains Obtained by the Linear Heterocopolycondensation Process

Abstract During the statistical analysis of copolymers obtained by the heteropolycondensation method, simulating the difference in the reactivity of the original comonomers by varying the preset reactive conditions, it is shown that the microstructure of the condensation copolymer chains should not depend on the relative reactivity of the comonomers. It is also shown that the microstructure of the chains can be influenced by choosing the copolycondensation conditions in such a way that the process would proceed from a insufficient quantity of the intermonomer in the reactive zone.

New Developments in High-Frequency Power Sources

The induction heating industry has recently introduced a new high-frequency power source, the static frequency converter. The converter uses solid-state low-loss thyristors to guide currents to the induction heating load generating high-frequency power at high efficiency. Unlike the conventional motor generator, the output frequency of the static converter is variable, being self-controlled from the induction heating load. It follows the load impedance and adjusts itself to maintain preset conditions. This paper describes to the potential induction heating user what a static converter is, how it works, and how it compares with its more familiar counterpart, the motor?generator.

An analysis of transfer in gas-shielded welding arcs

THE commercial success of a metal-arc-welding process depends in large measure upon the mode by which molten metal is transferred from the electrode to the workpiece. Excessively large drops will produce irregular beads which, in some cases, are bounded by regions of spatter. The presence of spatter not only mars the appearance of the joint but also represents a loss in deposition efficiency. This phase of the welding problem has occupied a prominent place in arc physics research during the past decade. Motion pictures showing transfer in slow motion is a familiar tool which has contributed to our knowledge of the various patterns and modes of metallic transfer with preset welding conditions.