Berechnung der Schaufelgitterströmung mit Grenzschicht und Ablösung

Zusammenfassung Für die Berechnung der ebenen station?ren Unterschallstr?mung durch gerade Schaufelgitter unter Einbeziehung von Reibungseffekten wird ein Verfahren vorgestellt. Die wesentlichen Elemente der iterativ arbeitenden Gesamtprozedur sind ein Oberfl?chensingularit?tenverfahren für die inkompressible Potentialstr?mung, ein Integralverfahren für die Grenzschicht und ein Verdr?ngungsmodell für Hinterkantenabl?sung. Au?erdem wird, unter Beschr?nkung auf kleine Machzahlen, eine einfache Kompressibilit?tskorrektur vorgesehen. Das Verfahren wird soweit verallgemeinert, da? auch mehrteilige Gitterschaufeln behandelt werden k?nnen. Nach einer ausführlichen Darstellung des Verfahrens werden Rechenergebnisse gezeigt und mit Me?ergebnissen verglichen.     

Measurements with multi-point microprobes: Effect of suspended solids on the hydrodynamics of bubble columns for application in chemical and biotechnological processes

Many experimental studies reveal that suspended solids considerably alter the coalescence behaviour and hydrodynamic functions of wo-phase flow. But no systematic efforts have yet been undertaken to separate the effects of different particle properties on local gas hold-up, bubble size and interfacial area gas/liquid. The aim of this paper is to present the local values of these parameters in three-phase fluidized beds of different solids, using miniaturized optical fiber and conductivity needle probes. It is shown that particle concentration, size and, in particular, density are decisive for the change in coalescence behaviour. Ranges of normal (?_S > ?_L) and inverse fluidization (?_S < ?_L) must be distinguished and the flow regime also exerts a strong influence on the interactions between the dispersed phases, the transition point itself being a function of particle properties can be observed, This effect is evaluated for different column diameters, between 0.1 and 0.3 m.     

Electronic Interactions of Cyclopropyl Groups: Synthesis and Photoelectron Spectra of Model Compounds Derived from Triasterane,Nortricyclane and Norbornane

The syntheses of the new hydrocarbons trimethylenetriasterane 12 , trispirocyclopropanetriasterane 3 , trispirocyclopropanenortricyclane 4 , and of the trispirocyclopropanenorbornanes 5, 6 , and 7 are reported. 12 contains six vinylcyclopropane units rigidly held in an antiperiplanar (ap) conformation in a D_3h symmetric framework. 3 and 4 are the first model compounds with bicyclopropyl units rigidly fixed in an s-trans (ap) conformation (Θ = 180°). Their PE spectra reveal that the interaction parameter β_ww = −1.73 eV for this arrangement is the same as that for Θ = 0°.     

Reductive transformations

Summary 2,3-Diheptyl- and 2,3,6,7-tetraheptyl-9, 10-anthraquinone are reduced to the corresponding diols and subjected to esterification with the chlorides derived from mono- and di-acids. The resulting polyesters are nicely soluble in organic solvents and can be characterized by vapor pressure osmometry and NMR spectroscopy.     

DEPFET sensors, A Test Case To Study 3d Effects

DEPleted Field Effect Transistors are inherently 3d structures, collecting carriers due to X-rays in a potential well beneath a gate controlled MOSFET channel. This charge modulates the MOSFET current and has to be removed periodically into a direction orthogonal to the MOSFET channel. The amplitude of the modulation is 10⁻² of the drain current and has to be computed with errors smaller 10⁻³. To reach this goal, test functions are introduced, which solve the related adjoint discrete problem and cancel the first order error terms for each terminal current. The proper ‘discrete integration by parts’ reduces rounding and allows to compute the current balance for typical conditions with a relative error smaller than 10⁻¹².