Wake flow past a plate with spoiler II: Gravity effects

Summary The effects of transverse gravity on steady flow past a split plate are investigated, by adopting the wake model proposed in the preceding paper (I). The existence and uniqueness of the solution as well as the convergence of an iteration process involving the free streamlines are proved for large Froude numbers by means of the Banach contraction mapping principle using Lipschitz norms.

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Sunto Si studiano gli effetti dovuti ad un campo di gravità uniforme trasversale sul flusso con scia attorno ad un profilo sottile con spoiler usando un modello proposto nel precedente lavoro (I). Si dimostra l'esistenza, unicità, e la convergenza di un procedimento iterativo sulle linee di corrente libere, per grandi numeri di Froude, mediante il principio di contrazione in spazi di Banach.

     

Estimation of Jc(B) dependence from self-field alternating current (AC) losses measured on Bi-2223/Ag tapes

Transport AC losses measured in self-field conditions on multifilamentary Bi-2223 tapes are often found to be lower than those calculated within the framework of the critical state model for a bulk wire with elliptical cross section, though generally higher than predicted for a strip. This effect is sometimes ascribed to the non-ideal geometry of the tapes, which does not exactly reproduce either shape. Here we propose an alternative explanation assuming that the critical current density of superconducting material depends on magnetic field. In practice, we analyzed the AC loss curve and deduced different I_c values for the individual data points, using the standard Norris equation for elliptical conductor. This gives the relation between ‘calculated' I_c and the self-field associated to AC transport current, which can be regarded as an alternative way to qualify the dependence of J_c on magnetic field. Important is that this procedure covers the range of fields below the self-field at I_c where the measurement in background DC field can not be used to determine J_c(B).     

A boundary version of Ahlfors’ Lemma,locally complete conformal metrics and conformally invariant reflection principles for analytic maps

A boundary version of Ahlfors’ Lemma is established and used to show that the classical Schwarz-Carathéodory reflection principle for holomorphic functions has a purely conformal geometric formulation in terms of Riemannian metrics. This conformally invariant reflection principle generalizes naturally to analytic maps between Riemann surfaces and contains among other results a characterization of finite Blaschke products due to M. Heins. D. Kraus was supported by a HWP scholarship O. Roth and S. Ruscheweyh received partial support form the German-Israeli Foundation (grant G-809-234.6/2003)     

Thermal,spectral and biological properties of Zn(II) complex compounds with phenazone

The thermal decomposition of the complexes Zn(form)₂⋅2phen (I), Zn(ac)₂⋅2phen (II), Zn(prop)₂⋅2phen (III), Zn(but)₂⋅2phen (IV), where phen=phenazone, form=formiate, ac=acetate, prop=propionate, but=butyrate has been studied in air by TG/DTG and DTA methods. The possible mechanism of the thermal decomposition was proposed. The final product of thermal decomposition was ZnO. IR data show unidentate coordination of carboxylate group to Zn(II) ion. The complexes were tested against various strains of microorganisms and their efficiency decrease in the sequence yeasts >bacteria>filamentous fungi.     

Gradually truncated log-normal in USA publicly traded firm size distribution

We study the statistical distribution of firm size for USA and Brazilian publicly traded firms through the Zipf plot technique. Sale size is used to measure firm size. The Brazilian firm size distribution is given by a log-normal distribution without any adjustable parameter. However, we also need to consider different parameters of log-normal distribution for the largest firms in the distribution, which are mostly foreign firms. The log-normal distribution has to be gradually truncated after a certain critical value for USA firms. Therefore, the original hypothesis of proportional effect proposed by Gibrat is valid with some modification for very large firms. We also consider the possible mechanisms behind this distribution.     

Influence of the vertical profile of Saharan dust on the visible direct radiative forcing

The vertical profile of Saharan dust in the atmosphere is generally characterized by a large aerosol concentration in the mid troposphere, differently from the climatological distribution of other types of particles, that show a peak at the surface and a rapid decrease with height. Saharan dust is also characterized by particles of relatively large size of irregular shape, and variable values of the single scattering albedo (the ratio between radiation scattering and extinction). The dust's peculiar vertical distribution is expected to produce an effect on the calculation of the direct aerosol radiative forcing at the surface and at the top of the atmosphere. This effect is investigated by comparing estimates of aerosol direct visible radiative forcing at the surface and at the top of the atmosphere for dust vertical profiles measured in the Mediterranean, and for the climatological profile. The radiative forcing is estimated by means of an accurate radiative transfer model, and for the ocean surface. The sensitivity of the results on the solar zenith angle, aerosol optical depth, and aerosol absorption is also investigated. The aerosol radiative forcing at the surface shows a very small dependency on the aerosol vertical profile. At the top of the atmosphere, the radiative forcing is weakly dependent on the vertical profile (up to 10% variation on the daily average forcing) for low absorbing particles; conversely, it shows a strong dependency (the daily radiative forcing may vary up to 100%) for absorbing particles. The top of the atmosphere visible radiative forcing efficiency produced by dust having single scattering albedo <0.7 is higher by 4 W m⁻² when the observed vertical profile instead of the standard profile is used in the calculations (i.e. it produces a lower cooling). For values of the single scattering albedo around 0.67, the sign of the forcing depends on the vertical profile. The influence of the vertical distribution on the radiative forcing is largest at small values of the solar zenith angle, and at short wavelengths.     

Synthesis of enantiomerically pure functionalised trianglamine macrocycles by N-acylation and N-alkylation reactions

The N-alkylation and N-acylation reactions of trianglamine macrocycles are described leading to an efficient synthesis of enantiomerically pure functionalised hexa-amide and hexa-amine trianglamine macrocycles.