Modeling the Relationships Between Wood Properties and Quality of Veneer and Plywood of Chinese Plantation Poplars

Following our earlier studies on the relationships between wood properties and the quality of veneer and plywood of Chinese plantation poplars, this study attempted to model their relationships with stepwise and multiple linear regression. The results show that the selected three indices of wood quality of veneer and plywood of plantations poplars grown on the shore of the Yangtse River in China, which are the variance of veneer thickness (VVT), the ratio of lathe check in veneer (ratio of the depth of check to the thickness of veneer) (RLC), and the glue-bond strength of plywood (GS), can be satisfactorily predicted with the key wood properties using the individual regression equations. The variance of veneer thickness (VVT) is a function of fiber width (FW), proportion of vessel (VP), and fiber (FP): VVT = -3.414 + 0.063 FW + 0.049 FP - 0.033 VP. The ratio of lathe check in veneer (RLC) is a function of wood hardness on tangential surface (TH), modulus of elasticity in bending (MOE), air-dry wood density (WD), and total volumetric shrinkage of wood (SV): RLC = 9.472 + 0.005 TH + 0.003 MOE + 8.366 WD - 2.302 SV. The glue-bond strength of plywood (GS) is a function of pH values (PH), fiber length (FL), fiber width (FW), vessel length (VL), and proportion of vessel (VP) and ray (RP): GS = 3.326 - 0.268 PH - 0.002 FL + 0.191 FW - 0.004 VL - 0.033 VP + 0.095 RP. The correlation coefficients (r) of the above regression equations are 0.73-0.93. The determination coefficients (r2) for the regression equations are 0.54-0.88. The regression equations are highly statistically significant at the 1% level. The differences between the model predicted and experimentally measured values are not statistically significant

Study of Manufacturing Thermochromic Wood

The development of new materials such as thermochromic wood provides an interesting option for the forest products industry. Poplar veneer was colored by ultrasonic impregnation using a thermochromic agent consisting of thermochromic dye, a chromogenic agent, 1-tetradecanol, and a sensitizing agent. In optimizing the process, the most significant influence on the extent of sample color change (ΔE) was found to be the mixing ratio of thermochromic dye to chromogenic agent. Next was the mixing ratio of thermochromic dye to 1-tetradecanol and last that of thermochromic dye to sensitizing agent. Analysis of 0variance showed that the influences of all experimental parameters on ΔE were significant at the 0.01 level. The optimum mixing ratio of thermochromic dye, the chromogenic agent, 1-tetradecanol, and the sensitizing agent was 1:8:50:1. The color of these new products changed from blue to wood color as temperature increased 26-34°C and reverted from normal wood color to blue as temperature decreased from 34-26°C

Effect of Bordered Pit Torus Position on Permeability in Chinese Yezo Spruce

The effect of different bordered pit torus positions on wood permeability was studied by air-drying and ethanol-exchange drying for green wood and by soaking in water, then followed by ethanol-exchange drying for air-dried wood of Chinese yezo spruce (Picea jezoensis var. komarovii). The results showed that different treatments caused different pit torus positions and different wood permeability. The air-drying treatment resulted in pit torus aspiration and low permeability for sapwood. The ethanol-exchange drying treatment left the pit torus in an unaspirated position and resulted in high permeability for sapwood. Soaking in water followed by ethanol-exchange drying caused deaspiration of a part of pit torus and increased permeability for both sapwood and heartwood

Experiments in Nonisothermal Diffusion of Moisture in Wood

A series of nine experiments was performed with one surface of the wood specimen maintained at approximately 70 C and the other at 29C. The warm surface was exposed to relative humidities between 10% and 50%. One series of four experiments was conducted with the cool surfaces exposed to relative humidities between 34% and 42%, while those of the other series of five were exposed at 52% to 53%. In both series, a reversal of flux direction was observed as the relative humidity of the warm surface was increased. The results were analyzed using the general sorption data presented in the USDA Wood Handbook using two equations, the first of which is based on a gradient of activated moisture content and the second on a gradient of chemical potential that contains an additional term to account for the effect of the temperature gradient. Both equations predicted the observed reversal of flux direction, but the chemical potential equation generally provided the better fit to the experimental results

Contribution Factor of Wood Properties of Three Poplar Clones to Strength of Laminated Veneer Lumber

The term "Contribution Factor" (Cf) was introduced in this paper to indicate the contribution ratio of solid wood properties to laminated veneer lumber (LVL) strength. Three poplar (Populus sp.) clones were studied, and the results showed that poplar with good solid wood properties has high Contribution Factor. The average Contribution Factor of Poplar 69 (Populus deltoides cv. I-69/55), Poplar 72 (P. euramericana cv. I-72/58), and Poplar 63 (P. deltoides cv.I-63-51) was 76.2%, 68.6%, and 66.1%, respectively. The average Contribution Factor of the three clones for shear strength, modulus of elasticity (MOE), and impact toughness was approximately 80%, which is higher than that for modulus of rupture (MOR), compressive strength, and hardness. The average Contribution Factor of the six properties tested was highest in Poplar 69 (76.2%) and the lowest in Poplar 63 (66.1%), indicating that the Contribution Factor is positively affected by solid wood properties. Densification also significantly affects LVL MOE in Poplar 72, as compared to that of Poplar 69. Poplar 63, however, showed highest improvement in MOR strength from solid wood to LVL and also highest specific LVL MOR, even though it has the lowest solid wood MOR among the three clones

Waveform-Domain Adaptive Matched Filtering: A Novel Approach to Suppressing Interrupted-Sampling Repeater Jamming

The inadequate adaptability to flexible interference scenarios remains an unresolved challenge in the majority of techniques utilized for mitigating interrupted-sampling repeater jamming (ISRJ). Matched filtering system based methods is desirable to incorporate anti-ISRJ measures based on prior ISRJ modeling, either preceding or succeeding the matched filtering. Due to the partial matching nature of ISRJ, its characteristics are revealed during the process of matched filtering. Therefore, this paper introduces an extended domain called the waveform domain within the matched filtering process. On this domain, a novel matched filtering model, known as the waveform-domain adaptive matched filtering (WD-AMF), is established to tackle the problem of ISRJ suppression without relying on a pre-existing ISRJ model. The output of the WD-AMF encompasses an adaptive filtering term and a compensation term. The adaptive filtering term encompasses the adaptive integration outcomes in the waveform domain, which are determined by an adaptive weighted function. This function, akin to a collection of bandpass filters, decomposes the integrated function into multiple components, some of which contain interference while others do not. The compensation term adheres to an integrated guideline for discerning the presence of signal components or noise within the integrated function. The integration results are then concatenated to reconstruct a compensated matched filter signal output. Simulations are conducted to showcase the exceptional capability of the proposed method in suppressing ISRJ in diverse interference scenarios, even in the absence of a pre-existing ISRJ model

Permeability and Capillary Structure of Chinese Woods

Axial permeability measurements of Chinese spruce, pine, and birch were made over a range of average pressure from 1.6 to 54 cm Hg. Linear plots of permeability vs. reciprocal mean pressure were obtained for spruce and pine in agreement with the Klinkenberg equation. Pit-opening radii were calculated from the intercepts and slopes, and the number of openings per cm2 of cross section were determined based on an assumed pit-membrane thickness of 0.1 μm. The plot of permeability vs. reciprocal mean pressure of the birch was curvilinear, indicating the presence of two conductances in series, which were assumed to be vessels and perforation plates. The calculated vessel radius and vessel concentration were in good agreement with data presented by Cheng (1980)

Waveform-Domain Adaptive Matched Filtering: A Novel Approach to Suppressing Interrupted-Sampling Repeater Jamming

The inadequate adaptability to flexible interference scenarios remains an unresolved challenge in the majority of techniques utilized for mitigating interrupted-sampling repeater jamming (ISRJ). Matched filtering system based methods is desirable to incorporate anti-ISRJ measures based on prior ISRJ modeling, either preceding or succeeding the matched filtering. Due to the partial matching nature of ISRJ, its characteristics are revealed during the process of matched filtering. Therefore, this paper introduces an extended domain called the waveform domain within the matched filtering process. On this domain, a novel matched filtering model, known as the waveform-domain adaptive matched filtering (WD-AMF), is established to tackle the problem of ISRJ suppression without relying on a pre-existing ISRJ model. The output of the WD-AMF encompasses an adaptive filtering term and a compensation term. The adaptive filtering term encompasses the adaptive integration outcomes in the waveform domain, which are determined by an adaptive weighted function. This function, akin to a collection of bandpass filters, decomposes the integrated function into multiple components, some of which contain interference while others do not. The compensation term adheres to an integrated guideline for discerning the presence of signal components or noise within the integrated function. The integration results are then concatenated to reconstruct a compensated matched filter signal output. Simulations are conducted to showcase the exceptional capability of the proposed method in suppressing ISRJ in diverse interference scenarios, even in the absence of a pre-existing ISRJ model.</p