Stand structure development effects on wood quality of Melina (Gmelina arborea roxb.)

Title from PDF of title page (University of Missouri--Columbia, viewed on Feb 15, 2010).The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file.Dissertation advisor: Dr. David LarsenVita.Ph.D. University of Missouri--Columbia 2009A stem analysis was perform to examines the effects of thinning treatments on Melina (Gmelina arborea) wood quality and tree architecture in the North Coast of Colombia. 27 plots under forest management regimes and age classes were evaluated. Split-plot experimental design, stepwise regression and ANOVA were developed to analyze the data. The results reveal that high precipitation regions have the higher values in most of the physics and mechanicals properties of the wood and dry regions have the lower values. No management regime improves wood properties rather that other regimes; but the log grade analysis was the lowest. Intermediate thinning regime was the best treatment applied to increase wood properties, wood quality and log grade in Melina trees. Estimation of log grade through the harvest cycle shows the highest increments at Cordoba region. Dendrometric variables such as heartwood, sapwood, and diameter and crown height are good estimators of tree volume, taper and branch modeling.Includes bibliographical reference

Single-atom control of the optoelectronic response in sub-nanometric cavities

By means of ab-initio time dependent density functional theory calculations carried out on an prototypical hybrid plasmonic device (two metallic nanoparticles bridged by a one-atom junction), we demonstrate the strong interplay between photoinduced excitation of localized surface plasmons and electron transport through the single atom. Such an interplay is remarkably sensitive to the atomic orbitals of the junction. Therefore, we show the possibility of a twofold tuning (plasmonic response and photoinduced current across the juntion) just by changing a single atom in the device.Comment: 5 pages, 5 figure

Carbon footprint from helitankers: sustainable decision making in aerial wildfire fighting

Carbon footprint (CF) can be a key factor stimulating innovation while driving sustainable decision making. The air transport sector and wildfires are considered to be relevant contributors to greenhouse gas emissions. Among the available resources for wildfire suppression, aerial firefighting ? particularly using helitankers ? is the most effective method. However the high economic costs and fuel-related emissions incurred by helitankers prevent their widespread use. This work aims to calculate the CF from helitankers in order to assess this new indicator for sustainable decision making. The CF is calculated here by a compound method based on the financial accounts of a Spanish company that owns 20 helitankers. The total cumulative corporate CF in 2012 was 5497 t CO2 equivalents. We discuss the influence of the method, its implications and future actions for the reduction of greenhouse gas emissions. Our experience should be considered as a pilot study providing further evidence of the value of using sustainable indicators in decision making

Investigación de mercado, elaboración de estrategias para la realización del relanzamiento con presupuestos reales caso: relanzamiento rapid juice

CEALCO, con su producto Pulpa de Fruta Congelada, que se comercializa con el nombre de “Rapid Juice”, tiene ya dos años en el mercado ecuatoriano. Entre los competidores más fuertes están: Maria Morena, La Jugosa y los jugos concentrados de Facundo. Para poder competir en el mercado, ante estos reconocidos competidores, Rapid Juice debe aplicar una estrategia que le permitirá aumentar sus ventas y su nivel de aceptación y reconocimiento de la marca por parte de los consumidores. Según este planteamiento, es sumamente importante para CEALCO manejar información de calidad, que sirva para lograr conocer aspectos fundamentales respecto a las características del mercado como: Establecer la situación real del mercado en la actualidad. Determinar si los actuales esfuerzos mercadológicos están correctamente encaminados. Identificar de manera exacta la dimensión del mercado. Reconocer las necesidades y las preferencias de los consumidores. Teniendo todos estos aspectos claros y basándose en los resultados obtenidos, se ha planteado dentro del proyecto, realizar un relanzamiento del producto mejorando sus características y atributos actuales así como la implementación de un nuevo plan de mercadeo, que permitirá mejorar su situación dentro del mercado de pulpa de frutas congeladas

From Microscopic to Macroscopic Description of Composite Thin Panels: A Roadmap for their Simulation in Time Domain

In this paper, we show a simulation strategy for composite dispersive thin-panels, starting from their microscopic characteristics and ending into a time-domain macroscopic model. In a first part, we revisit different semianalytic methods that may be used to obtain the S-parameter matrices. The validity of them is assessed with numerical simulations and experimental data. We also include some formulas that may be used to tailor the shielding effectiveness of panels in a design phase. In a second part, we present an extension to dispersive media of a subgridding hybrid implicit–explicit algorithm finite difference time domain (FDTD) devised by the authors to deal with that kind of materials. The method, here presented and applied to the FDTD method, is a robustly stable alternative to classical impedance boundary condition techniques. For this, a previous analytical procedure allowing to extract an equivalent effective media from S-parameters is presented, thus making this road map able to simulate any kind of dispersive thin layer. A numerical validation of the algorithm is finally shown by comparing with experimental data

Robust free-spurious formulation of high order 2.5 dimensional electromagnetic problems by using finite elements

The 3D Finite Elements Method (FEM) is an extensively accepted tool for the analysis and design of microwaves/millimetre circuits and antennas based on the use of complex materials and geometries. Despite the huge memory capacity and computation speed of the current informatics systems, the method still suffers from an expensive computational cost when the domain is 3D. In many practical structures, the knowledge of the behaviour of one field component introduces a symmetry in the formulations that allows to project the physical problem onto a bi-dimensional mesh. The result of the former is a dramatic increase of the speed and ease of handling of such kind of problems, achieving efficient tools for the computer assisted design of many complex structures used in the electrical engineering nowadays. Because nothing is free, this simplification in the computation of the numerical problems is reached after a modification into the formulation and discretization of the model in the sense to introduce the symmetry of the field component into the basis functions. Because we need the three field components, we must divide the basis functions in two sets; one keeps the vector character and is applied to approximate the transversal or meridian component of the electromagnetic field and the other set is used for the longitudinal or azimuthal component. Then, we have to work with two elements, one is vector and the other is scalar. Frequently they are called hybrid elements, or 2.5D elements. This type of problems has been intensively studied by many researchers along the last two decades [1], [2], [3], [4], [5], [6]. However, only lower order basis has been used and, since our knowledge, it has not been developed a theory linking the development of the function spaces for the cited two elements, vector and scalar which make up the hybrid elements. This is especially true when the order of the elements increases, producing the apparition of the frightened spurious modes. Besides of the lack of a robust method to obtain these higher order hybrid elements for the 2.5D problems, we consider that it is worth reviewing these procedures, trying to increase its reliability and robustness. It should be a priority to incorporate the use of higher-order elements to the discretization of 2.5D problems, as the last developments relative to pre and post processors, new and more powerful meshers and solvers. In this way we can develop new numerical tools facing the more complex geometries containing field singularities, diverse materials and multiscale details with curved boundaries that conform the structures that electrical engineers handle nowadays. This work is an extension with some new results of previous presented at [5], [7]. A complete study of the design of conical dielectric core horn antennas, ended by both, convex-plane and double-convex dielectric lens, is carried on, taking advantage of the robust performance of the developed methods

Neural-network-based curve fitting using totally positive rational bases

This paper proposes a method for learning the process of curve fitting through a general class of totally positive rational bases. The approximation is achieved by finding suitable weights and control points to fit the given set of data points using a neural network and a training algorithm, called AdaMax algorithm, which is a first-order gradient-based stochastic optimization. The neural network presented in this paper is novel and based on a recent generalization of rational curves which inherit geometric properties and algorithms of the traditional rational Bézier curves. The neural network has been applied to different kinds of datasets and it has been compared with the traditional least-squares method to test its performance. The obtained results show that our method can generate a satisfactory approximation