Eine an die Nicholsonformel anschliessende asymptotische Entwicklung für Zylinderfunktionen

Ohne Zusammenfassung Habilitationsschrift in der Fakult?t für Mathematik und Physik der Technischen Hochschule Darmstadt. Referent: Prof. Dr.A. Walther, Korreferent: Prof. Dr.C. Schmieden.     

Zur Stabilität der Strömung in einem horizontalen Rohr bei ungleichmässig erwärmter Wand

Summary The linear fluid motion in a horizontal pipe heated from below is considered, when the temperature field outside the pipe is linear. By the method of small perturbations it is shown that the fluid motion becomes unstable for a critical value of the Rayleigh number, i.e., there is an additional convective motion, the streamlines of which are concentric curves in the plane of a cross-section of the pipe.

---

---

Die Untersuchung wurde vom Wirtschaftsministerium des Landes Baden-Württemberg gefördert.     

Effects of simultaneous 13C?1H and 13C?11B decoupling on the carbon-13 n.m.r. spectra of some organoboron compounds

¹³C FT n.m.r. spectra were obtained from borates of methyl α-D -glucopyranoside, triethylboron, sodium tetraphenylboron and 1-butaneboronic acid employing a simultaneous ¹H and ¹¹B decoupling network. The effectiveness of the system was evident using the three latter organoboron compounds. Since no diminution in line broadening of signals occurred in the spectrum of the sugar borate, the absence of ¹³C? O? ¹¹B coupling was indicated. This finding was confirmed by comparing the effects of varying the temperatures of sugar borates and triethylboron on their conventional ¹³C n.m.r. spectra.     

Convergence of the perturbation theory expansion for spin-spin coupling constants

The convergence of the full perturbation theory expansion for the Fermi contact term in the spin-spin coupling constant of hydrogen fluoride has been studied. By examining the contribution of higher virtual states as the basis set is expanded to 18 atomic orbitals, it is shown that at this level of approximation the expansion does not converge. The need to also establish convergence before accepting values calculated from configuration interaction wavefunctions is discussed.The Puerto Rico Nuclear Center is operated by the University of Puerto Rico for the United States Atomic Energy Commission under Contract No. AT(40-1)-1833.     

Low temperature thermal conductivity of graphite-FeCl3 intercalation compounds

The low-temperature variation of the in-plane thermal conductivity of graphite- FeCl₃ intercalation compounds is reported. Around room temperature, though holes are participating, there is an important lattice contribution, but much smaller than in pristine graphite. The electronic contribution dominates in the liquid helium range. These preliminary results suggest lattice thermal conductivity measurements as a new tool to investigate defects introduced by intercalation.     

Nonlinear dynamical behavior of surface electromyographical signals of biceps muscle under two simulated static work postures

The primary objective of this study was to explore nonlinear characteristics, if any, of the surface myoelectrical (EMG) activity of the biceps muscle during simulated maximum voluntary contraction at a reference arm posture (MVCRP), and at an elevated static arm work posture (EAWP) observed on the manufacturing assembly line. The results showed that positive Lyapunov exponents existed for each of the trials in both work postures. The statistical test of significance showed that surface EMG of the biceps brachii was more chaotic under the MVCRP condition as compared to the EWAP condition. Based on the Kaplan-Yorke dimension, it was observed that the recorded two types of time series EMG data were similar in complexity. The study also found a significant difference in fractal dimensions between the two postures. It was concluded that the nonlinear dynamical EMG properties expressed in terms of the Lyapunov exponents, Kaplan-Yorke dimension, and fractal dimensions could be used as sensitive indices for evaluation of the level of muscular efforts under static work conditions.     

(2+2)-cycloaddition of triazolinediones to strained bicycloalkenes

Substituted norbornenes and dibenzobarrelene react under forced conditions with $\text{N}$-methyl-1,2,4-triazolin-3,5-diones to afford urazoles via (2+2)-cycloaddition.