A mixed pixel- and region-based approach for using airborne laser scanning data for individual tree crown delineation in Pinus radiata D. Don plantations

The aim of this study was to evaluate the use of high-resolution airborne laser scanner (ALS) data to detect and measure individual trees. We developed and tested a new mixed pixel- and region-based algorithm (using Definiens Developer 7.0) for locating individual tree positions and estimating their total heights. We computed a canopy height model (CHM) of pixel size 0.25 m from dense first-pulse point data (8 pulses m^?2) acquired with a small-footprint discrete-return lidar sensor. We validated the results of individual tree segmentation with accurate field measurements made in 37 plots of Monterey pine (Pinus radiata D. Don) distributed over an area of 36 km². Fieldwork consisted of labelling all of the trees in each plot and measuring their height and position, for posterior integration of the data from both sources (field and lidar). The proposed algorithm correctly detected and linked 59.8% of the trees in the 37 sample plots. We also manually located the trees by using FUSION software to visualize the raw lidar data cloud. However, because the latter method is extremely time-consuming, we only considered 10 randomly selected plots. Manual location correctly detected and linked 71.9% of the trees (in this subsample the algorithm correctly detected and measured 63.5% of the trees). The R² values for the linear model relating field- and lidar-measured heights of the linked trees located manually and with the automatic location algorithm were 0.90 and 0.88, respectively.     

Processing of short fiber reinforced polypropylene. II: Statistical study of the effects of processing conditions on the impact strength

Within the general objective of analyzing and modeling the processability of polypropylene and of its short fiber composites, a statistical analysis of the relationship between processing conditions and final properties has been performed applying modern experimental design concepts. In order to gather the largest amount of information with a manageable quantity of experiments, Taguchi methods were used for the design of injection molding tests and for the analysis of experimental fiber orientation and impact strength results. Two levels of each variable of interest were selected, and the results of the analysis not only show which of the processing variables are predominant but also show that interactions between variables must be taken into account. The approach presented here offers a viable route to the scaling-up of the injection molding process through the reduction of the number of variables in the prediction of the processing behavior of semicrystalline polymers and of their composites.     

Drying of Wheat Based on the Non-Equilibrium Thermodynamics: A Numerical Study

A new mathematical model to describe simultaneous heat and mass (liquid and vapor) transfer and shrinkage during drying of capillary-porous bodies with particular reference to prolate spheroid solid is presented. As an application, the methodology was used to predict drying of soft red winter wheat (Arthur). The mathematical model was based on the nonequilibrium thermodynamics considering variable transport coefficients and convective boundary conditions at the surface of the solid. All the partial differential equations presented in the model have been written in prolate spheroidal coordinates and solved numerically by a finite-volume method using implicit fully formulation. Results of the drying and heating kinetics and moisture content and temperature distributions in a wheat kernel during drying process are presented and analyzed. The methodology allows verification of the heat, liquid, and vapor fluxes, taking into account the thermal and hydrical gradients inside the grain.     

Frequency Selective Surfaces with Anisotropic Dielectric Superstrates

A full wave analysis is developed for frequency selective surfaces composed of rectangular patches mounted on a dielectric anisotropic substrate and covered with a uniaxial anisotropic superstrate. The moment method is used in combination with the spectral domain immittance approach to determine the FSS structure reflection and transmission coefficients.     

Infiltration Pond Design for Highway Runoff Treatment in Semiarid Climates

Highway runoff disposal without concern for its specific characteristics may be associated with high material and environmental costs. An understanding of storm water management has enlightened the importance of the impacts that nonpoint pollution may cause to both surface waters and groundwater. Several systems for highway runoff treatment exist, often based on detention and infiltration processes. This paper suggests a method for design and evaluation of the design of infiltration ponds for use in semiarid climates. The design principle is based on capture and infiltration of the most polluted runoff. It takes into account the rainfall and soil hydraulic characteristics for the determination of the design volume. Seasonal variations in rainfall and evaporation were considered. The soil characteristics—hydraulic conductivity, texture, pH, and cation exchange capacity—the volume of runoff which is infiltrated, and the infiltration area are used to calculate the movement of the most mobile heavy metal, Zn, in the soil. The method presented was based and applied to highway runoff but can be used for treatment of stormwater runoff from other sources.     

Processing of short‐fiber reinforced polypropylene. I. Influence of processing conditions on the morphology of extruded filaments

An experimental investigation of the processing of glass fiber reinforced polypropylene is presented. Final fiber orientation distribution, fiber distribution in filament sections, rheological properties, final fiber length distribution and surface morphology were analyzed. This analysis was done taking into account the quantity of fibers and their interactions and flow conditions. The final fiber orientation increased when shear rate increased and fiber concentration decreased. Moreover, inhomogeneities in fiber distribution increased as the concentration of fibers decreased. The density profile showed a significant variation with fiber concentration, but it was not dependent on the shear rate applied. The viscosity showed a linear dependence with shear rate. The average fiber length and the breadth of this distribution decreased with the increasing fiber concentration and extrusion rate. The extruded filament surface showed minor roughness when the shear rate increased or when the fiber concentration decreased. The results of this experimental characterization give useful information to determine the influence of the processing variables on the final properties of short‐fiber reinforced polypropylene and constitutes the first part of a more ambitious project that also includes the development of a modeling strategy of the processing behavior for short‐fiber composites.     

A contribution to the understanding of a.c. anodizing of aluminium

Commercial aluminium has been anodized in 10% v/v sulphuric acid using alternating current. At 20 V no significant differences in colour and thickness between specimens anodized at the neutral and live terminals were detected. At higher voltages the oxide on the neutral specimens was always more yellow and thinner than that on the live specimens. The colouration was attributed to the reduction of sulphate to sulphide during the cathodic half-cycle, no other sulphur-containing species being detected by XPS. EPMA has shown that the total sulphur distribution across the film was practically uniform and independent of the operating conditions, except in thin films, where it was greatest at the free surface. With additions of ferric sulphate to the solution the reduction to sulphide was inhibited and the differences between live and neutral specimens were avoided. The total amount of sulphur remained unchanged at approximately 5% weight and no iron was incorporated in the film.