General distributed economic framework for dynamic spectrum allocation

The emergence of novel radio techniques enables the application of advantageous revolutionary spectrum policies. An important body of research has appeared about possible frequency management schemes, but none of them proposes solutions that meet every related criteria. In this paper we present our work on dynamic spectrum allocation and pricing that offers a distributed mechanism design, well-suited to practical employment issues. Our model handles interference effects without any restricting assumptions, provides universal scalable and incentive-compatible allocation and pricing mechanisms. We provide both analytical and numerical evaluation of the proposed framework, and in either case we prove this latter to be a suitable approach to efficient and flexible spectrum utilization.     

High-temperature dielectric response of ferroelectric relaxors

It has long been considered that polar nanoregions in relaxors form at Burns temperature T(d) ≈ 600K. High-temperature dielectric investigations of Pb(Mg(1/3)Nb(2/3)) O(3) (PMN) single crystal, PMN-PbTiO(3) ceramics, and (Pb,La) (Zr,Ti)O(3) ceramics reveal, however, that dielectric dispersion, detected around 600K, is due to the Maxwell-Wagner-type contributions of surface layers. The intrinsic response was analyzed in terms of the universal scaling, taking into account the asymptotic and the correction-to-scaling behavior, and the results imply much higher T(d) or formation of polar nanoregions in a broad temperature range. High values of the dielectric constant indicate, however, that polar order already exists at the highest measured temperatures of 800K. The obtained critical exponents indicate critical behavior associated with universality classes typically found in spin glasses.     

Absorption and fluorescence spectroscopic study on complexation of Oxazine 1 Dye by calix[8]arenesulfonate

It has been established by combined absorption and fluorescence measurements that the cationic dye Oxazine 1 (OX) and the polyvalent anionic host calix[8]arenesulfonate (SCA8) form two complexes in simultaneous reactions: OX + SCA8 <--> OX.SCA8 (1), and OX.SCA8 + OX <--> OX(2).SCA8 (2). The equilibrium constants for the two reactions, as functions of the ionic strength (I), and the absorption and fluorescence spectra of the two complex species have been determined by a least-squares fitting method from the experimental data. The variations of the binding constants with the ionic strength could be described on the basis of Debye-Huckel theory. The equilibrium constants are large; their values extrapolated to I = 0 are K(1) = 5.5 x 10(6) M(-1) and K(2) = 4.4 x 10(5) M(-1). The fluorescence of OX undergoes a strong static quenching upon complexation. These results indicate that the complexes are held together by strong electrostatic forces. The addition of non-fluorescent tetramethylammonium chloride to OX-SCA8 mixtures results in a dramatic fluorescent enhancement, which demonstrates the potential applicability of this supramolecular system in fluorescence assays.     

Electrical and thermal properties of vinylidene fluoride–trifluoroethylene-based polymer system with coexisting ferroelectric and relaxor states

Dielectric, thermal, and electrocaloric investigations of poly(vinylidene fluoride–trifluoroethylene) P(VDF–TrFE) copolymer, irradiated with high-energy electrons, are reported. While the ferroelectric copolymer is transformed into a relaxor system at high irradiation doses, dielectric investigations, particularly nonlinear dielectric experiments, i.e., temperature dependences of the second and the third harmonic dielectric response, clearly evidence that at lower doses ferroelectric and relaxor states coexist in the P(VDF–TrFE). This is confirmed by the differential scanning calorimetry, which further reveals the influence of irradiation on the copolymer crystallinity and melting point. Finally, it is shown that large electrocaloric response of VDF–TrFE-based polymers is further enhanced in systems with coexisting relaxor and normal ferroelectric states.     

The effect of calcium zirconate modifications on the microstructure and functional properties of sodium niobate thin films prepared by chemical solution deposition

Sodium niobate thin films doped with manganese (NN), and NN films modified with 5 or 10 mol % calcium zirconate (CZ) on platinized silicon substrates were prepared by chemical solution deposition. The 250-nm-thick films crystallize in a perovskite phase with fine, equiaxed grains. The NN films exhibit well-shaped ferroelectric loops with a remanent polarization and coercive field of ～10 μC/cm² and ～100 kV/cm, respectively. The modification with CZ strongly influences the ferroelectric response of the films: the remanent polarization progressively decreases to around 2.5 μC/cm². The absence of an anti-ferroelectric response, which has previously been confirmed in bulk NN-CZ ceramics, is attributed to the nanoscale microstructure and residual thermal stresses. All the studied films exhibit a piezoelectric response with the highest piezoelectric d₃₃ coefficient of 35 pm/V at 300 kV/cm bias field for the NN modified films with 5 mol % CZ, making them candidates for lead-free piezoelectric thin-film applications.     

Terrestrial laser scanning for the comprehensive structural health assessment of the Baptistery di San Giovanni in Florence,Italy: an integrative methodology for repeatable data acquisition,visualization and analysis

The ravages of time, natural and man-made disasters, pollution, fatigue, overexposure, mismanagement, and the unintended consequences of efforts to preserve our cultural patrimony, have all taken a major toll on historical structures. Structural health assessment is the first pivotal step towards creating a strategy for long-term life-cycle management. Historical structures provide an abundance of unique challenges that when combined serve as a great qualifying test for the study of as-built structures. This paper explores the diagnostic value of terrestrial laser scanning for the structural health assessment of the Baptistery di San Giovanni in Florence, Italy and proposes an integrative methodology for repeatable data acquisition, processing, visualization and analysis. The presented study proves that even under challenging circumstances, efficient documentation of entire structures is possible. The case study at the Baptistery demonstrates that even when objectives are not formed prior to the survey, comprehensive data sets of high quality and reliability will enable meaningful structural health assessments. With a reliable comprehensive baseline model in place, it can be annotated, qualitatively analyzed and recurring surveys can be conducted to track changes and damages throughout time.