Auslegungskriterien für elektrostatische Emulsionsspaltanlagen

Design criteria for electrostatic de-emulsifiers. Electrostatic de-emulsifiers have been successfully used over many years for desalting of crude oil. The emulsions used for this application are rather unstable and break down easily. Different equipment and conditions are required for highly stable emulsions, such as are used for liquid membrane permeation. To permit use of higher field strengths without danger of short circuiting this new equipment must be fitted with insulated electrodes, with preference being given to glass-insulated liquid electrodes. An important feature is also a defined distance between the electrodes which are arranged in concentric manner to increase the de-emulsification rate. The rate of de-emulsification can also be increased by using high frequency (10 kHz) instead of the usual low frequency (50 Hz) alternating voltage.     

Effect of the finish rolling and cooling conditions on the properties of microalloyed plate steels

The processing parameters of finish rolling and cooling of three HSLA steels were varied in a wide range applying the plane strain hot compression simulation test on the hot deformation simulator (Wumsi). Evaluating the flow curves of the deformation steps, some metallurgical phenomena in austenite during hot deformation could be determined. The results of material testing after the simulation experiments exhibit a strong correlation between the finish rolling and cooling conditions and the final mechanical properties of the steels tested. As a way to increase strength, lowering finishing temperatures and/or accelerating cooling after finish rolling proved to be most effective. To improve notch toughness, on the other hand, a high total finishing strain should be applied as well as low finishing temperatures, however, above A_r3.     

Zur Frage der Erwärmung von Leimfugen im hochfrequenten Wechselfeld

European Journal of Wood and Wood Products -     

Stationäres Kriechverhalten innendruckbelasteter dünnwandiger Kreiszylinderschalen unter Berücksichtigung des orthotropen Werkstoffverhaltens und des CSD-Effektes

Zusammenfassung In Hinblick auf eine verbesserte Werkstoffausnutzung und aufgrund experimenteller Daten hochtemperaturbeanspruchter Werkstoffe sind bei der Auslegung von z.B. zylindrischen Druckkesseln und Rohrleitungen der chemischen Industrie und des Kraftwerkbaus au?er dem orthotropen Werkstoffverhalten auch unterschiedliche Druck- und Zugkriechgrenzen (creep-strength-differential effect, kurz CSD-Effekt genannt) zu berücksichtigen. Hierzu wird im Rahmen der Darstellungstheorie tensorwertiger Funktionen eine Materialgleichung vorgeschlagen, die in Verbindung mit dem Norton-Baileyschen Kriechgesetz für die Berechnung des sekund?ren Kriechverhaltens axialysmmetrisch belasteter dünnwandiger Kreiszylinderschalen zugrunde gelegt wird, wobei die vielfach in der Literatur verwendete Sandwich-Konstruktion nicht benutzt wird. Vielmehr gehen die Untersuchungen von einer einheitlichen Vollwandschale aus, deren Kriechverformung dann mit Hilfe der finiten Differenzen-Methode zusammen mit dem erweiterten Newton-Verfahren ermittelt wird. Numerische Beispielrechnungen werden für die an den Enden eingespannte offene Kreiszylinderschale, die mit Innendruck belastet ist, durchgeführt. Es zeigt sich, da? sowohl orthotropes Werkstoffverhalten wie auch unterschiedliche Druck- und Zugkriechgrenzen gro?en Einflu? auf die Verschiebungen und Biegemomente haben. Die Untersuchung wurde von der Deutschen Forschungsgemeinschaft (DFG) finanziell unterstützt, wofür an dieser Stelle gedankt sei.     

Spannungsverlust bei Einankerumformern auf Grund experimenteller Untersuchungen

Ohne Zusammenfassung     

Frictionally excited thermoelastic instability in disc brakes—Transient problem in the full contact regime

Exceeding the critical sliding velocity in disc brakes can cause unwanted forming of hot spots, non-uniform distribution of contact pressure, vibration, and also, in many cases, permanent damage of the disc. Consequently, in the last decade, a great deal of consideration has been given to modeling methods of thermoelastic instability (TEI), which leads to these effects. Models based on the finite element method are also being developed in addition to the analytical approach.The analytical model of TEI development described in the paper by Lee and Barber [Frictionally excited thermoelastic instability in automotive disk brakes. ASME Journal of Tribology 1993;115:607-14] has been expanded in the presented work. Specific attention was given to the modification of their model, to catch the fact that the arc length of pads is less than the circumference of the disc, and to the development of temperature perturbation amplitude in the early stage of breaking, when pads are in the full contact with the disc. A way is proposed how to take into account both of the initial non-flatness of the disc friction surface and change of the perturbation shape inside the disc in the course of braking.     

Zur adsorptiven Abscheidung von Isocyanaten aus Abgasen

Ohne Zusammenfassung Reihe 3 Nr. 100 (1985) der FORTSCHRITT-BERICHTE VDI gibt den vollen Wortalut der Arbeit als Manuskript gedruckt wieder. 84 Seiten, Preis 58 DM. Bestellungen an die VDI-Verlag GmbH, Postfach 1139, 4000 Düsseldrof 1.     

Efficient Metal‐Free Aerobic Photooxidation of Sulfides to Sulfoxides Mediated by a Vitamin B2 Derivative and Visible Light

We have developed a metal‐free process for the aerobic photooxygenation of sulfides to sulfoxides mediated by riboflavin tetraacetate or riboflavin (vitamin B₂) photocatalysts and visible light (450 nm) in an acetonitrile‐water (85:15 v/v) mixture. The optimised solvent system leads to both singlet‐oxygen and electron‐transfer pathways in photooxygenation, thus allowing oxidation of electron‐poor and electron‐rich thioanisoles, dialkyl sulfides and sterically hindered sulfides. Besides having a broad substrate scope, the method has very short reaction times and requires low catalyst loading (down to 0.1 mol%). These properties are due to the high photocatalyst stability and the extremely high quantum yields (1.3 for thioanisole oxygenation). Moreover, the method is chemoselective, producing only sulfoxides without overoxidation to sulfones. Taking into account the broad substrate scope, high selectivity and high efficiency, this method distinguishes itself from those previously reported. Other advantages include easy work‐up of the reaction mixture, the availability and biodegradability of the photocatalysts and mild reaction conditions. We demonstrated, on a preparative scale, its practical application in the synthesis of the psychostimulant modafinil, in the selective oxidation of methionine derivatives, and in the detoxification of mustard gas.