Characterization of bronze Roman coins of the fifth century called <Emphasis Type="Italic">nummi</Emphasis> through different analytical techniques

Mixing of different organic charge-transfer-complexes (CT-complexes) might allow the adjustment of the optical and morphological properties of the resulting material system. In this work, a study of two CT-complexes, mixed by thermal coevaporation at different concentrations by substituting only the acceptor molecules, is presented. Electron diffraction patterns, which were collected on samples of the ternary system of the prototypical CT-complexes DBTTF-TCNQ and DBTTF-F₄TCNQ do not show any indication of a mixed crystalline phase or novel crystalline order. X-ray diffraction measurements additionally confirm the phase separation in the ternary system. However, upon mixing of the complexes, the degree of crystallinity of the individual phases is reduced. This effect correlates with the mixing ratio of the CT-complexes in the ternary compound. Furthermore, we do not observe a shift or the appearance of new peaks in the infrared spectra of (DBTTF-TCNQ) _x :(DBTTF-F₄TCNQ)_1?x . Hence, there is no indication for a pronounced or novel chemical interaction between the individual CT-complexes in the mixed compound.     

Molecular charge distributions, core-ionization energies, and the point-charge approximation. An addendum

In earlier papers the atoms-in-molecules concept of Bader was used to show the inadequacies of the point-charge model for calculating potentials at atoms in molecules and, hence, for accounting for shifts in core-ionization energies in terms of atomic charges. Because questions have been raised about the suitability of the basis set that was used, part of these calculations has been repeated with the 6-31G^** basis set. The conclusions of the earlier study are unchanged: the point-charge model does not accurately give the potentials at atoms in molecules. A multipole model gives better results, but needs to be carried at least to octupole terms.     

New FIR Laser Lines from CHD2OH Methanol

We have investigated CHD₂OH methanol as source of far-infrared (FIR) laser radiation using the optical pumping technique. Our new waveguide pulsed CO₂ laser, with peak powers as high as some kW, has allowed us to observe 12 new lines. Each of them is characterized in wavelength, relative polarization, intensity, optimum operating pressure and pump offset from the center of the exciting CO₂ line.     

Mean fractional-order-derivatives differential equations and filters

The solution of differential equations of fractional order is generalized to the case when the fractional order derivatives are integrated with respect to the order of differentiation. The formal solution is found by means of the Laplace Transform. The solutions of the integro-differential equations, defined by means of derivatives of fractional order and of their integrals with respect to the order of differentiation, are also discussed in terms of filtering.

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Sunto Si generalizza la soluzione di equazioni differenziali di ordine frazionario al caso in cui le derivate frazionarie sono integrate rispetto all’ordine di differenziazione. La soluzione formale è trovata a mezzo della Transformata di Laplace. Le soluzioni delle equazioni integrodifferenziali, definite a mezzo delle derivate di ordine frazionario e dei loro integrali rispetto all’ordine di differenziazione, sono discusse a mezzo della teoria dei filtri.

     

Genetic algorithms for supply-chain scheduling: A case study in the distribution of ready-mixed concrete

The coordination of just-in-time production and transportation in a network of partially independent facilities to guarantee timely delivery to distributed customers is one of the most challenging aspect of supply chain management. From a theoretical perspective, the timely production/distribution can be viewed as a hybrid combination of planning, scheduling and routing problems, each notoriously affected by nearly prohibitive combinatorial complexity. From a practical viewpoint, the problem calls for a trade-off between risks and profits. This paper focuses on the ready-mixed concrete delivery: in addition to the mentioned complexity, strict time-constraints forbid both earliness and lateness of the supply. After developing a detailed model of the considered problem, we propose a novel meta-heuristic approach based on a hybrid genetic algorithm combined with constructive heuristics. A detailed case study derived from industrial data is used to illustrate the potential of the proposed approach.