Hydroelastische Schwingungen eines schwimmenden Balkens unter einem gleichförmig bewegten Einachsfahrzeug als ebenes Problem

Übersicht Die hydroelastischen Schwingungen eines schwimmenden Rechteckbalkens unter einem gleichförmig bewegten Einachsfahrzeug werden mit Hilfe der Eigenformmethode berechnet für ebene Potentialströmung bei Ausschaltung seitlicher Wellenabstrahlung. Für den Fall des homogenen Balkens auf einem stehenden Gewässer mit rechteckigem Bett werden die Eigenformen bestimmt unter Berücksichtigung des Volumenausgleichs durch die Oberflächenwellen. Der Lösungsweg zur Berechnung der Bahnbeschleunigung des Einachsfahrzeugs wird aufgezeigt, die für die Systemantwort maßgebend ist. Am Beispiel einer kontinuierlichen Pontonbrücke unter einer rollenden Einzelmasse werden die Lastwegkurve, Oberflächenwellen und die Verteilung der Strömungsgeschwindigkeit vorgestellt.

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Two-dimensional hydroelastic beam vibrations due to an uniformly moving one axle vehicle

The hydroelastic vibrations of a rectangular beam under the effect of an uniformly moving one axle vehicle will be investigated by normal mode method for the case of two-dimensional potential flow realized by artificial elimination of surface waves aside the beam. In the case of homogeneous beam spanning over a rectangular channel filled with calm water the normal modes are determined considering surface waves only that are able to compensate the volume of the enclosed fluid. An analytical method will be shown to find the vehicle's vertical acceleration governing the response of the system. The presented example of a continuous pontoonbridge crossed by a rolling mass demonstrates the load's way, surface waves and the velocity distribution of the flow.

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Herrn Professor Dr.-Ing. Chr. Petersen zum 60. Geburtstag gewidmet     

Local mass transfer measurements in an inclined enclosure at high Rayleigh number

An electrochemical technique is used to study local mass transfer coefficients on surfaces of inclined enclosures over the range 1.1×10⁴ < Ra_H < 1.4×10¹⁰ for a nominal Schmidt number of 2280. Scaling with gcos instead of g in the Rayleigh number correlates the data well at low angles of inclination; however, as either the aspect ratio or the angle of inclination increase, the longitudinal density stratification causes the data to deviate from a power law scaling.

Theory of 31P Chemical Shifts

Abstract

The IGLO (individual gauge for localized orbitals) method¹, has been applied successfully to organic molecules.² The application to phosphorous compounds is more laborious, mainly since larger basis sets are required. By the IGLO method one obtains the chemical shielding as a sum of contributions of localized orbitals. For ³¹P the dominant contributions come from the K-shell (well transferable), the L-shell (depending somewhat on the bonding situation), the bonds attached to P (large differences between single and multiple bonds), and the lone pair on P (large variations), the contributions of distant bonds and lone pairs being small, but often not negligible. We find good agreement with experiments for those molecules for which experimental data are available (e.g. PH₃, P₂H₄, P₄, CH₃PH₂, OPF₃) and we can make predictions for others (e.g. P₂, P₂H₂, HSiP). The interpretation of the variation of is more complicated than in the case of hydrocarbons, since bond contributions are usually not transferable between different molecules, and it is hard to justify an increment system. An interesting example is the dependence of the ³¹P-shift in RC≡P on R.     

Anatomy of $B^{0}_{s,d} \to J/\psi f_{0}(980)$

The \(B^{0}_{s}\to J/\psi f_{0}(980)\) decay offers an interesting experimental alternative to the well-known \(B^{0}_{s}\to J/\psi \phi\) channel for the search of CP-violating New-Physics contributions to \(B^{0}_{s}\)–\(\bar{B}^{0}_{s}\) mixing. As the hadronic structure of the f ₀(980) has not yet been settled, we take a critical look at the implications for the relevant observables and address recent experimental data. It turns out that the effective lifetime of \(B^{0}_{s}\to J/\psi f_{0}(980)\) and its mixing-induced CP asymmetry S are quite robust with respect to hadronic effects and thereby allow us to search for a large CP-violating \(B^{0}_{s}\)–\(\bar{B}^{0}_{s}\) mixing phase ? _s , which is tiny in the Standard Model. However, should small CP violation, i.e. in the range ?0.1?S?0, be found in \(B^{0}_{s}\to J/\psi f_{0}(980)\), it will be crucial to constrain hadronic corrections in order to distinguish possible New-Physics effects from the Standard Model. We point out that \(B^{0}_{d}\to J/\psi f_{0}(980)\), which has not yet been measured, is a key channel in this respect and discuss the physics potential of this decay.     

Optimizing holographic data storage using a fractional Fourier transform

We demonstrate a method to optimize the reconstruction of a hologram when the storage device has a limited dynamic range and a minimum grain size. The optimal solution at the recording plane occurs when the object wave has propagated an intermediate distance between the near and far fields. This distance corresponds to an optimal order and magnification of the fractional Fourier transform of the object.     

Development of a Ruthenium/Phosphite Catalyst System for Domino Hydroformylation–Reduction of Olefins with Carbon Dioxide

An efficient domino ruthenium‐catalyzed reverse water‐gas‐shift (RWGS)‐hydroformylation‐reduction reaction of olefins to alcohols is reported. Key to success is the use of specific bulky phosphite ligands and triruthenium dodecacarbonyl as the catalyst. Compared to the known ruthenium/chloride system, the new catalyst allows for a more efficient hydrohydroxymethylation of terminal and internal olefins with carbon dioxide at lower temperature. Unwanted hydrogenation of the substrate is prevented. Preliminary mechanism investigations uncovered the homogeneous nature of the active catalyst and the influence of the ligand and additive in individual steps of the reaction sequence.     

Ueber die Bestimmung von Weins?ure und Citronens?ure bei Gegenwart verschiedener Basen und S?uren

Ohne Zusammenfassung     

Ueber eine neue Verf?lschung der Schwefels?ure

Ohne Zusammenfassung