Primitive man learned to make iron by placing iron ore and charcoal in a clay pot and building a fire in the pot. A crude bellows provided the forced draft that started a smelting or reduction action that deposited iron at the bottom of the pot, which when removed and hammered, could be forged into a variety of shapes. This was a far cry from the process discovered in the mid-1800s that formed the basis of the giant steel industries being developed in Europe and America. The blast furnace was invented by Henry Bessemer, an English metallurgist whose process was thereafter referred to as the Bessemer process. This process involved the introduction of forced air into the pig iron refining procedure, which raised the temperature of the crucible so that any impurities in the molten pig iron were burned away, and in the process, a more malleable metal was created—steel.

Zusammenfassung

Zur Analyse des Produktspektrums sowie zur Festlegung von Entwicklungsschwerpunkten wurde auf Datenmaterial aus einer Marktumfrage /46/, auf das statistische Jahrbuch 1989 /47/ und auf die Resultate von Expertengesprächen mit führenden Konfektionären, Endverbrauchern und Anlagenherstellern zurückgegriffen. Demnach werden in der Bundesrepublik Deutschland in den sechs Hauptbranchen PKW-Industrie, Braune und Weiße Ware-Industrie, Steuerungselektronik, Luft- und Raumfahrttechnik sowie in der LKW-Branche jährlich 93 Mio Leitungssätze produziert. Auf die Fahrzeugindustrie entfallen davon über 45%, in der Unterhaltungselektronik und Weiße-Ware-Industrie werden 25% bzw. 16% der Leitungssätze montiert.

It is proved that, by using state feedback, it is not possible to place the poles of a linear time invariant system to the left of a certain critical negative real number if the system matrix is subject to uncertainties (perturbations) of a given (small) magnitude.

Summary

In the paper the open-die forward extrusion process is analysed in order to determine the influence of the most important geometrical and frictional parameters on the practical suitability of the operation. Experimental tests have been carried out and their results have been compared with the numerical ones derived by FEA.

The profiles of averaged circular and axial velocity components, temperature, and pressure are measured in the axisymmetric channel of the energy separation chamber of a vortex tube with the introduction of additional flow in the near-axis zone on the side cross section where throttle is located.