Yu Haipeng

Auto detection of wood texture orientation by Radon transform

A novel and efficient approach for detecting wood texture orientation by computer was presented. Four Matlab functions were tried to describe the relative position and orientation of wood texture pixels, to detect texture shape and to create skeletal lines image of wood texture, and BWMORPH function was found the best one. Then by Radon transform, it generated a signature composed of 180 values, each value summing up the size of texture lines that are shaped along that angle, and a two dimensional curve plot was drawn to represent the texture orientation of wood. Furthermore, it analyzed texture orientations of forty species as well as their general statistic laws, classified by softwood, hardwood, radial section and tangential section, and the results showed that texture orientation laws described by Radon transform plot and their extracting datum were in accord with the impression of wood texture that people possessed in daily life, which confirmed the validity of this new approach and their appealing utilization potentials.

Measurement of the dynamic modulus of elasticity of wood panels

This study investigated the dynamic modulus of elasticity (DMOE) of wood panels of Fraxinus mandshurica, Pinus koraiensis, and Juglans mandshurica using the natural frequency measurement system of fast Fourier transform (FFT). The results were compared with the static modulus of elasticity (ES) tested by a mechanical test machine. The results show a significant correlation between ES, transverse vibration DMOE (EF), and longitudinal vibration DMOE (EL). For all of these species, the correlation between ES, EF and EL is more significant than the individual species, which indicated that the FFT method is universal. The correlations between ES and sample’s density (ρ) are significant, but the correlation coefficient of ES and ρ is lower than those between EF, EL and ES. The ES of wood is more accurately tested by the analysis based on FFT measurement than by the estimation based on density.

Preliminary study on the characteristics of tactility of wood by physiological index HRV

We used heart rate variability (HRV), an electrophysiological index, to investigate the changes of the sympathetic and parasympathetic nervous systems of people when they were in contact with wood and other materials, in a time-domain, a frequency-domain, and by means of nonlinear dynamics. Our aim was to discover the relations among thermal parameters of different kinds of material, human physiological feedbacks, and psychological perceptions. It shows that the activity of the sympathetic nervous system when in contact with wood increased no more than when in contact with metal and ceramic materials, while the activity of the parasympathetic nervous system weakened less than when in contact with these materials. The time taken by the sympathetic and parasympathetic nervous systems to revert to their normal state after contact with cloth and wood was shorter than that after contact with metal and ceramic. A subjective survey, by SD method, showed that the tactility of wood was favorable and people preferred wood to other kinds of material. Correlation analysis’ results showed that there was a close correlation among the HRV indices, human psychological emotion ratings, and thermal parameters of the different kinds of materials. The experiment proves that the effect of wood on our autonomous nervous system is slightly better than that of other materials except for cloth. Wood does not damage people’s health.