Optimality conditions for the calculus of variations with higher-order delta derivatives

We prove the Euler-Lagrange delta-differential equations for problems of the calculus of variations on arbitrary time scales with delta-integral functionals depending on higher-order delta derivatives.Comment: Submitted 26/Jul/2009; Revised 04/Aug/2010; Accepted 09/Aug/2010; for publication in "Applied Mathematics Letters

Structural and optical properties of europium doped zirconia single crystals fibers grown by laser floating zone

Yttria stabilized zirconia single crystal fibers doped with europium ions were developed envisaging optical applications. The laser floating zone technique was used in order to grow millimetric high quality single crystal fibers. The as-grown fibers are completely transparent and inclusion free, exhibiting a cubic structure. Under ultraviolet (UV) excitation, a broad emission band appears at 551 nm. The europium doped fibers are translucent with a tetragonal structure and exhibit an intense red emission at room temperature under UV excitation. The fingerprint transition lines between the 5D0 and 7FJ(0–4) multiplets of the Eu3+ ions are observed with the main emission line at ∼ 606 nm due to 5D0→7F2 transition. Photoluminescence excitation and wavelength dependent the photoluminescence spectra confirm the existence of different Eu3+ optical centers. © 2011 American Institute of PhysicsFCT-PTDC/CTM/66195/2006FCT-SFRH/BD/45774/200

PMD tolerant nonlinear compensation using in-line phase conjugation

In this paper, we numerically investigate the impact of polarisation mode dispersion on the efficiency of compensation of nonlinear transmission penalties for systems employing one of more inline phase conjugation devices. We will show that reducing the spacing between phase conjugations allows for significantly improved performance in the presence polarisation mode dispersion or a significant relaxation in the acceptable level of polarization mode dispersion. We show that these results are consistent with previously presented full statistical analysis of nonlinear transmission appropriately adjusted for the reduced section length undergoing compensation

Generalized retarded integral inequalities

We prove some new retarded integral inequalities. The results generalize those in [J. Math. Anal. Appl. 301 (2005), no. 2, 265--275].Comment: Changes suggested by the referee don

SW England Rare Earth Elements (REE) Stream Sediment Dataset user guide

This report describes how 3378 stream sediment samples collected between 2002 and 2013 across SW England by the BGS G-BASE project were analysed to determine the total concentration of 16 rare earth elements (REE)by inductively-coupled mass spectrometry (ICP-MS) and x-ray fluorescence spectrometry (XRFS). It documents the methods used to process and display the resultant chemical data. The analytical results were used to create a series of raster (ASCII format) grids and interpolated geochemical maps (PNG images) showing the distribution of REE across SW England

Leitmann's direct method of optimization for absolute extrema of certain problems of the calculus of variations on time scales

The fundamental problem of the calculus of variations on time scales concerns the minimization of a delta-integral over all trajectories satisfying given boundary conditions. This includes the discrete-time, the quantum, and the continuous/classical calculus of variations as particular cases. In this note we follow Leitmann's direct method to give explicit solutions for some concrete optimal control problems on an arbitrary time scale.Comment: Accepted for publication (9/January/2010) in Applied Mathematics and Computatio

Structural Transitions in a Classical Two-Dimensional Molecule System

The ground state of a classical two-dimensional (2D) system with finite number of charged particles, trapped by two positive impurities charges localized at a distance (zo) from the 2D plane and separated from each other by a distance xp are obtained. The impurities are allowed to carry more than one positive charge. This classical system can form a 2D-like classical molecule that exhibits structural transitions and spontaneous symmetry breaking as a function of the separation between the positive charges before it transforms into two independent 2D-like classical atoms. We also observe structural transitions as a function of the dielectric constant of the substrate which supports the charged particles, in addition to broken symmetry states and unbinding of particles.Comment: 9 pages, 7 figure

Compatible blends of thermoplastic starch and hydrolyzed ethylene-vinyl acetate copolymers

AbstractEthylene-vinyl acetate copolymer (EVA) with 19% of vinyl acetate and its derivatives modified by hydrolysis of 50 and 100% of the initial vinyl acetate groups were used to produce blends with thermoplastic starch (TPS) plasticized with 30wt% glycerol. The blends were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, water absorption, stress–strain mechanical tests, dynamic mechanical analysis and thermogravimetric analysis. In contrast to the blends with unmodified EVA, those made with hydrolyzed EVA were compatible, as demonstrated by the brittle fracture surface analysis and the results of thermal and mechanical tests. The mechanical characteristics and water absorption of the TPS were improved even with a small addition (2.5wt%) of hydrolyzed EVA. The glass transition temperature rose with the degree of hydrolysis of EVA by 40 and 50°, for the EVA with 50 and 100% hydrolysis, respectively. The addition of hydrolyzed EVA proved to be an interesting approach to improving TPS properties, even when very small quantities were used, such as 2.5wt%

Necessary Optimality Conditions for Higher-Order Infinite Horizon Variational Problems on Time Scales

We obtain Euler-Lagrange and transversality optimality conditions for higher-order infinite horizon variational problems on a time scale. The new necessary optimality conditions improve the classical results both in the continuous and discrete settings: our results seem new and interesting even in the particular cases when the time scale is the set of real numbers or the set of integers.Comment: This is a preprint of a paper whose final and definite form will appear in Journal of Optimization Theory and Applications (JOTA). Paper submitted 17-Nov-2011; revised 24-March-2012 and 10-April-2012; accepted for publication 15-April-201

Valorização agrícola de lamas de origem têxtil

Valorização agrícola de lamas de origem têxtil