Streckenkomplexe auf Flächen

Ohne Zusammenfassung     

Integrable Nonlinear Equations for Water Waves in Straits of Varying Depth and Width

A considerable amount of information is currently available on the creation and propagation of large solitary waves in marine straits. In order to be able to analyze such data we develop a theoretical model, extending previous one-dimensional models to the case of straits with varying width and depth, and nonvanishing vorticity. Starting from the Euler equations for a three-dimensional homogeneous incompressible inviscid fluid, we derive, in the quasi-one-dimensional long-wave and shallow-water approximation, a generalized KadomtsevPetviashvili (GKP) equation, together with its appropriate boundary conditions. In general, the coefficients of this equation depend on the form of the bottom and on the vorticity; the sides of the straits figure only in the boundary conditions. Under certain restrictions on the vorticity and the geometry of the straits we reduce the GKP equation to one of several completely integrable partial differential equations, in order to study the evolution of solitons which originate in the straits.     

Redox Potential and Crystal Chemistry of Hexanuclear Cluster Compounds

Most of TM₆-cluster compounds (TM = transition metal) are soluble in polar solvents, in which the cluster units commonly remain intact, preserving the same atomic arrangement as in solids. Consequently, the redox potential is often used to characterize structural and electronic features of respective solids. Although a high lability and variety of ligands allow for tuning of redox potential and of the related spectroscopic properties in wide ranges, the mechanism of this tuning is still unclear. Crystal chemistry approach was applied for the first time to clarify this mechanism. It was shown that there are two factors affecting redox potential of a given metal couple: Lever’s electrochemical parameters of the ligands and the effective ionic charge of TM, which in cluster compounds differs effectively from the formal value due to the bond strains around TM atoms. Calculations of the effective ionic charge of TMs were performed in the framework of bond valence model, which relates the valence of a bond to its length by simple Pauling relationship. It was also shown that due to the bond strains the charge depends mainly on the atomic size of the inner ligands.     

Concerning the design of capacitively driven induction coil guns

The authors consider the design of capacitively driven, multisection, electromagnetic coil launchers, or coil guns, taking their transient behavior into account. A lumped-parameter computer simulation is developed to predict the performance of the launcher system. It is shown that a traveling electromagnetic wave can be generated on the barrel by the resonance of drive coils and their capacitors. More than half of the energy initially stored in the capacitor bank can be converted into kinetic energy of the projectile in one shot, and an additional quarter can be utilized in subsequent shots, if the launcher dimensions, resonant frequency, and firing sequence are properly selected. The projectile starts smoothly from zero initial velocity and with zero initial sleeve current. Section-to-section transitions which have significant effects on the launcher performance are also discussed. Experimental results were obtained with a small model and are in good agreement with theoretical predictions     

Löslichkeit und Adsorbierbarkeit von Benzoesäure und Salizylsäure in Gegenwart gemischter organischer Lösungsmittel

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