Diffusion von Silizium,Phosphor, Schwefel und Mangan in flüssigem Eisen

Zusammenhang zwischen Diffusion und Aktivität. Messung der Diffusionskoeffizienten von Silizium, Phosphor, Schwefel und Mangan in flüssigem Eisen sowie in kohlenstoffgesättigtem, flüssigem Eisen. Angabe der Konzentrationsabhängigkeit und der Temperaturabhängigkeit der ermittelten Diffusionskoeffizienten.     

Three-dimensional analytical calculation of induction machines with multilayer rotor structure in cylindrical coordinates

An analytical three-dimensional solution of the field problem of induction machines with multilayer rotor structure is presented in cylindrical coordinates. The curvature of the machine is no longer neglected as against the known solution in cartesian coordinates. This results in much higher accuracy for machines with a large air-gap width or small bore radius. In addition, the analysis is performed for an arbitrary number of rotor layers and for arbitrary speed of each rotor layer.

Note on the connectivity of line graphs

Let G be a connected graph with vertex set V(G), edge set E(G), vertex-connectivity κ(G) and edge-connectivity λ(G).A subset S of E(G) is called a restricted edge-cut if G−S is disconnected and each component contains at least two vertices. The restricted edge-connectivity λ₂(G) is the minimum cardinality over all restricted edge-cuts. Clearly λ₂(G)?λ(G)?κ(G).In 1969, Chartrand and Stewart have shown that

     

Influence of thermophysical properties on pool boiling heat transfer of refrigerants

The correct prediction of the heat transfer performance of the boiling liquid within the evaporator of a refrigeration unit is one of the essential features for the successful operation of the whole unit. A theoretically consistent calculation method for the heat transfer coefficient α in nucleate boiling, which should be based on the physical phenomena connected with vapour bubbles growing, departing and sliding on the wall and with the interactions of bubbles and of neighbouring nucleation sites within the microstructure of the heating surface, does not yet exist, despite the increasing number of papers on the subject in the recent past. Instead, the predictive methods for α available at present are empirical or semiempirical, especially for heat transfer conditions relevant in practice. Many of these correlations have been established in the form of power laws in which the relative influences of the main groups of variables on α are treated by separate factors. One of these may stand for the influence of the thermophysical properties of the boiling liquid or these properties will be included in several of the factors.New experimental results are presented for pool boiling heat transfer from a single horizontal copper tube (8 mm OD) to HFC-refrigerants (R32, 125, 134a, 143a, 152a, 227ea) and hydrocarbons (propane, i-butane). The results are compared to experimental data from the literature, and methods are discussed, how to incorporate the data in semiempirical correlations to describe the influence of the thermophysical properties of the fluids on the heat transfer performance.     

Stress- and strain-induced formation of martensite and its effects on strength and ductility of metastable austenitic stainless steels

The effects of deformation-induced formation of martensite have been studied in metastable austenitic stainless steels. The stability of the austenite, being the critical factor in the formation of martensite, was controlled principally by varying the amounts of carbon and manganese. The formation of martensite was also affected by different test and rolling temperatures, rolling time, and various reductions in thickness. The terms “stress-induced” and “strain-induced” formation of martensite are defined. Experimental results show that low austenite stability resulted in stress-induced formation of martensite, high work-hardening rates, high tensile strengths, low “yield strengths,” and low elongation values. When the austenite was stable, plastic deformation was initiated by slip, and the work-hardening rate was too low to prevent early necking. A specific amount of strain-induced martensite led to an “optimum” work-hardening rate, resulting in high strengthand high ductility. For best results processing should be carried out aboveM _d and testing betweenM _d andM _s. Mechanical working aboveM _d had a negligible effect on the yield strength betweenM _d andM _s when the austenite stability was low, but its effect increased as the austenite became, more stable. Serrations appeared in the stress-strain curve when martensite was strain induced.     

Parameter pe′ der Elektronenteilleitfähigkeit in ZrO2(CaO)- und ThO2(Y2O3)-Festelektrolyten bei 1200 bis 1650 °C

Bestimmung des Parameters p_e′ (t_ion = 0,5) zur Kennzeichnung der Elektronenteilleitfähigkeit in festen Elektrolyten. Anwendung einer abgewandelten Polarisationsmethode mit EMK-Messung. Angabe der Parameter p_e′ für Festelektrolyte aus ZrO₂ mit einem Molenbruch x_CaO = 0,14 und aus ThO₂ mit einem Molenbruch bei Temperaturen zwischen 1200 und 1650 °C. Berechnung korrigierter Eichkurven für die elektrochemische Messung der Sauerstoffaktivitäten in Stahlschmelzen. Empfehlung einer bevorzugten Anwendung von ThO₂(Y₂O₃)-Elektrolyten zur Messung kleinster Sauerstoffaktivitäten.