Experimental Investigation of Vertical Density Profile of Medium Density Fiberboard in Hot Press

This research investigates the performance of medium density fiberboard (MDF) with respect to hot press parameters. The performance of the board, type of glue, and production efficiency determine the optimum temperature and pressure for hot pressing. The actual temperature of the hot press inside the MDF board determines the properties of the final product. Hence, the optimal hot press parameters for the desired product are experimentally obtained. Moreover, MDF is experimentally investigated in terms of its vertical density profile, bending, and internal bonding under the various input parameters of temperature, pressure, cycle time, and moisture content during the manufacturing process. The experimental study is carried out by varying the temperature, pressure, cycle time, and moisture content in the ranges of 200–220 °C, 145–155 bar, 260–275 s, and 8–10%, respectively. Consequently, the optimum input parameters of a hot-pressing temperature of 220 °C, pressure of 155 bar, cycle time of 256 s, and moisture content of 8% are identified for the required internal bonding (0.64 N/mm2), bending (32 N/mm2), and increase in both the core and peak density of the vertical density profile as per the ASTM standard.

MULTIPLE EXACT SOLUTIONS OF THE GENERALIZED TIME FRACTIONAL FOAM DRAINAGE EQUATION

In this paper, we investigate the exact solutions of the generalized time fractional foam drainage equation. The Lie-group scaling transformation method and improved [Formula: see text]-expansion method are adopted here. The equation describes the evolution of the vertical density profile of a foam under gravity. New exact solutions and maple diagrams of the generalized time fractional foam drainage equation can help us better understand the physical phenomena.

Jupiter dayside as seen by JIRAM-Juno: current status and examples of spectral data analysis

<p>The JIRAM instrument on board of the Juno spacecraft includes a spectrometer that operates in the range 2-5 μm with a spectral resolution of about 15 nm.<br>The signal measured between 2 and 3.1 um is due to the scattering of solar photons by aerosols in the daytime Jupiter atmosphere and, as such, it has been partially exploited in [1] to study the structure of "white ovals" vortexes in the southern hemisphere.<br>This contribution reviews the current status and issues of analysis of JIRAM data in this solar-dominated spectral range, with several examples from different latitudes. Modeling of vertical density profile of clouds is largely based on recent results of [2].<br>In JIRAM spectra, the region between 2.7 and 3.1 does not show any firm evidence of ammonia ice, that would be expected to produce clear spectral features here even when massively coated with contaminants such as tholines. It is therefore difficult to properly model the data assuming the optical properties of aerosols of any given realistic composition.<br><br><br>[1] Sindoni, G., et al. (2017) doi: 10.1002/2017GL072940<br>[2] Braude, A. S., et al. (2020) doi: 10.1016/j.icarus.2019.113589</p>

High-Pressure Treatment Effects on Density Profile, Surface Roughness, Hardness, and Abrasion Resistance of Paulownia Wood Boards

The goal of this study was to investigate the effects of high-pressure (HP) treatment on the mechanical performance properties of Paulownia ( spp.) wood boards. The boards were HP treated at selected pressures (20, 40, 60, 80, and 100 MPa) for 30 s. A special vacuum-packing technique that sandwiched the test boards between two steel plates was used for the HP treatment to prevent board distortion. Thickness, density, vertical density profile (VDP), cell wall percentage (VC), porosity percentage (VH), surface roughness, hardness, and abrasion resistance were evaluated to assess the performance properties of the treated and untreated boards. HP treatment resulted in 45.7% to 60.0% reduction in thickness of the boards, while it increased the density by 88% to 170%. The VDP of densified boards was distributed uniformly, and core densities were only slightly higher than surface densities. HP treatment made the Paulownia board surfaces much smoother, and three roughness parameters were reduced with increasing treatment pressure level. Hardness values of the boards were improved by 84% to 173%. The mass loss values of HP treated wood samples in abrasion tests were significantly reduced by 40.7% to 75.0%. The results of this study demonstrate that HP treatment is a useful method to improve the end-use properties of low-density wood like Paulownia. Keywords: Abrasion resistance, Hardness, High-pressure densification, Paulownia wood boards, Vertical density profile, Surface roughness.

Predicted Model of Section Stress Distribution and Bending Strength of Fiberboard Based on Vertical Density Profile

To study the impact of VDP on the bending process of fiberboard, this paper deeply researched into the dynamic changes of section stress distribution of fiberboard during the process of loading and bending and built a static bending strength predicting model, which is based on the piecewise function by simulating fiberboard VDP, theory of elasticity and plasticity, lamella inter-bedded theory and VDP model. The results show: The bending process of fiberboard can be divided into two stages which are elasticity period and elasticity-plasticity period. The latter includes both elasticity region and plasticity region, and compression region comes to elasticity bending before pulling region. The curve of bending section stress distribution is nonlinear and affected by loads and VDP. Critical section stress distribution of bending breakage and breakage load can be predicted by VDP with other condition unchanged. The value of static bending strength predicted by model is basically consistent with testing data. And the static bending strength is closely related to qualification factors of VDP. Fiberboard with high average density doesn’t always contain high static bending strength. VDP is a significant physical parameter which has impact on the bending process and performance of fiberboard, so it must be optimized and controlled in production according to for specific purpose. Key words: fiberboard, vertical density profile, section stress distribution, bending strength, predicting model