Untersuchung von Honig und Kunsthonig

Ohne Zusammenfassung     

Structure and methyl groups internal rotation of difluorodimethylsilane

The rotational spectra of the normal and ¹³C isotopomers of difluorodimethylsilane have been measured by molecular beam Fourier-transform microwave (FTMW) and free-jet absorption millimeter-wave (FJ-AMMW) spectroscopy. Each rotational transition is split into several component lines due to the two methyl groups internal rotations. The corresponding V₃ barrier has been determined to be 5.256(3) kJ mol⁻¹. A r₀ structure of the heavy atoms skeleton has been obtained. The silicon atom lies—accidentally—on the center of mass of the molecule.     

Convergence conditions for restarted conjugate gradient methods with inaccurate line searches

Convergence properties of restarted conjugate gradient methods are investigated for the case where the usual requirement that an exact line search be performed at each iteration is relaxed.The objective function is assumed to have continuous second derivatives and the eigenvalues of the Hessian are assumed to be bounded above and below by positive constants. It is further assumed that a Lipschitz condition on the second derivatives is satisfied at the location of the minimum.A class of descent methods is described which exhibitn-step quadratic convergence when restarted even though errors are permitted in the line search. It is then shown that two conjugate gradient methods belong to this class.Sponsored by the United States Army under Contract No. DA-31-124-ARO-D-462.