Linear Expansion And Thickness Swell Of Mdf As A Function Of Panel Density And Sorption State

Experiments were conducted using ASTM standard methods to determine the medium density fiberboard (MDF) expansion properties and swelling characteristics as a function of panel density and sorption state. Specimens without density profile were produced by removing the surface layers of laboratory MDF panels. The results from the trials showed that for laboratory MDF, linear expansion is homogenous in panel plane. When specimen density increased, linear expansion, linear expansion coefficient, thickness shrinkage coefficient, linear contraction, and linear contraction coefficient increased. Thickness swell was higher than thickness shrinkage at any density level. Thickness swell coefficient was higher than thickness shrinkage coefficient for low density levels. The values of linear contraction and linear contraction coefficient (in desorption) were higher than the values of linear expansion and linear expansion coefficient (in adsorption). The values on thickness swell and thickness shrinkage were much higher than the values of linear expansion and linear expansion and linear contraction at any density level. The effect of density on linear expansion, linear expansion coefficient and linear contraction coefficient was significantly stronger than the effect of density on thickness swell, thickness swell coefficient and thickness shrinkage

Finite Element Modeling Of The Hygroscopic Warping Of Medium Density Fiberboard

The objective of this study was to develop a three-dimensional finite element model of the hygromechanical deformation of medium density fiberboard (MDF) panels with various vertical density profiles subjected to moisture adsorption on one face. The theoretical model was based on three sets of equations: 1) three-dimensional equations of unsteady-state moisture diffusion, 2) three-dimensional equations of mechanical equilibrium, and 3) Hooke's law for plane isotropy, which takes into account shrinkage and swelling through the panel thickness. The finite element model was applied to six panels with various density profiles. For both the simulations and the experiments, the warping was caused by moisture adsorption from one of the faces of 560-mm x 560-mm x 12-mm MDF panels while the other surface and the edges were sealed. Physical and mechanical characteristics defined as a function of density and moisture content were used as model inputs. The model made it possible to capture the rapid initial development of maximum warp and its following decrease as moisture content equalized through panel thickness; the effect of the density profile on the level of warp caused by moisture adsorption; and warp fluctuations resulting from changes in the ambient relative humidity, and from the hysteresis in the expansion coefficient between adsorption and desorption. To validate the model, the warp development of laboratory MDF panels was compared to simulation results. The agreement between calculated and actual panel warping confirmed that the model could successfully be used to simulate moisture movement in MDF and the resulting warp, and to help in the optimization of panel vertical density profiles aiming at better stability of form in MDF panels. For the typical experimental cases, it was observed that there was a strong effect of panel density profile on the levels of warp and its dynamics. The levels of warp increased with average panel density. The panels with sharper density profile developed stronger warp compared to panels with an even profile. When the density profile was skewed towards one of the surfaces, the panel developed positive or negative warp and did not return to the original flat form

Mechanical Properties of MDF as a Function of Density and Moisture Content

This study examined the effect of medium density fiberboard (MDF) density and moisture content on MDF moduli of elasticity E1, E3, shear modulus, G13, and Poisson's ratios v12 and v13. The relation of all parameters with density was determined from MDF panels without density profile with average density levels of 540 kg/m3, 650 kg/m3, and 800 kg/m3. The relation with moisture content was determined from specimens conditioned to 50%, 65%, and 80% relative humidity. Panel E1, E3, and G13 increased with density increase and decreased with moisture conent increase. At each nominal density level, the values of E1 were much higher than the values of G13, which in turn were higher than the values of E3. The effect of density and moisture content on the Poisson's ratios was not significant

Effect of Panel Moisture Content and Density on Moisture Movement in MDF

This study examined the effect of medium density fiberboard (MDF) density and sorption state on the sorption isotherms and the effect of panel moisture content and density on the effective water conductivity and diffusion coefficient of MDF panels. A total of 39 laboratory-made MDF panels with dimensions 650 mm X 650 mm X 12 mm divided into 3 density groups (540 kg/m3, 650 kg/m3, and 800 kg/m3) was produced. The surface layers of each panel were removed, and the thickness of the remaining core layer of homogeneous density was reduced by sanding to 6 mm. The sorption isotherms were determined by exposing MDF samples to controlled relative humidities. The effective water conductivity was determined by the instantaneous profile method. Medium density fiberboard from all density levels displayed a marked sorption hysteresis. Both in adsorption and in desorption, the MDF specimens with higher density levels equilibrated at higher levels of moisture content. Moisture content had a stronger effect than density on the effective water conductivity. In desorption, the higher the moisture content level, the higher the effective water conductivity. Conversely, in adsorption, the effective water conductivity decreased as moisture content increased. The effective water conductivity in desorption and the diffusion coefficients both in desorption and adsorption were significantly higher for panels with a density of 540 kg/m3 than for densities of 650 and 800 kg/m3. In adsorption, the effective water conductivity of panels with a density of 540 kg/m3 was significantly higher than for a density of 800 kg/m3

Experimental Setup for Neural Networks and Camera-Based Navigation of Mobile Systems

The aim of this work is the application and evaluation of a method to visually detect markers at a distance of up to five meters and determine their real-world position. Combinations of cameras and lenses with different parameters were studied to determine the optimal configuration. Based on this configuration, camera images were taken after proper calibration. These images are then transformed into a bird's eye view using a homography matrix. The homography matrix is calculated with four-point pairs as well as with coordinate transformations. The obtained images show the ground plane un distorted, making it possible to convert a pixel position into a real-world position with a conversion factor. The proposed approach helps to effectively create data sets for training neural networks for navigation purposes

Performance evaluation of low-cost particulate matter sensors

The need to measure basic aerosol parameters has increased dramatically in the last decade. This is due mainly to their harmful effect on the environment and on public health. Legislation requires that particle emissions and ambient levels, workplace particle concentrations and exposure to them are measured to confirm that the defined limits are met and the public is not exposed to harmful concentrations of aerosols

Image-Based Automated Hit Detection and Score Calculation on a Steel Dartboard

This paper presents an approach for implementing an automated hit detection and score calculation system for a steel dartboard using a standard webcam. First, the rectilinear field separations of the dartboard are described mathematically by means of line slopes and are than stored. These slopes serve as a basis for later score calculation. In addition, thrown darts have to be detected and the pixel at which the dart cuts the dartboard has to be determined. When this information is known, a comparison is made using the line slopes, allowing the field number of the hit to be detected. The decision for single, double or triple hit is made by evaluating the defined colors on the dartboard. All these functions are then packaged in a Matlab GUI

Algorithms for cloud segmentation with ground-based camera images

This paper deals with the detection and segmentation of clouds on high-dynamic-range (HDR) images of the sky as well as the calculation of the position of the sun at any time of the year. In order to predict the movement of clouds and the radiation of the sun for a short period of time, the clouds thickness and position have to be known as precisely as possible. Consequently, the segmentation algorithm has to provide satisfactory results regardless of different weather, illumination and climatic conditions. The principle of the segmentation is based on the classification of each pixel as a cloud or as a sky. This classification is usually based on threshold methods, since these are relatively fast to implement and show a low computational burden. In order to predict if and when the sun will be covered by clouds, the position of the sun on the images has to be determined. For this purpose, the zenith and azimuth angles of the sun are determined and converted into XY coordinates