Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title><jats:p>To study the propagation characteristics of acoustic emission signals in <jats:italic>Zelkova schneideriana</jats:italic> under different boundary conditions, three types of boundary conditions were generated by applying aluminum plates and sound-absorbing cotton on the surface of <jats:italic>Zelkova schneideriana</jats:italic> specimens. Firstly, the sudden and continuous acoustic emission (AE) sources were simulated by PLB (pencil–lead break) tests and signal generator on the specimen surface, and the AE signals were collected by 5 sensors equally spaced on the surface of the specimen, and the sampling frequency was set to 500 kHz. Then, the detailed signals of different frequency bands were obtained by wavelet decomposition, and TDOA (the time difference of arrival) and correlation analysis method were used to calculate the time difference of longitudinal wave and surface transverse wave and the corresponding propagation velocity, respectively. Finally, the pulse trains with different energy levels generated by the signal generator were used as AE sources to study the attenuation law of AE signal energy with distance under different boundary conditions. The results show that the boundary changes can lead to a significant increase in the surface transverse wave velocity, and have no significant effect on the longitudinal wave velocity. At the same time, the energy attenuation of surface and longitudinal waves is faster after the aluminum plate and sound-absorbing cotton are affixed, and the distance of longitudinal waves attenuation to 90% is reduced from 186 to 139 mm, and the distance of surface transverse waves propagation is reduced from 312 to 226 mm.</jats:p>

<jats:title>Abstract</jats:title><jats:p>Progress in the condensation of lignin is believed to interfere with delignification in alkaline pulping processes without any clear evidence, which motivated us to revisit it quantitatively. This study is the 3rd in the series which evaluates the condensation reactions of lignin in model systems of soda cooking processes using 4-(1-hydroxyethyl)-2-methoxyphenol (apocynol, Ap) and 2-methoxy-4-methylphenol (creosol, Cr). Ap was primarily converted to 2-methoxy-4-vinylphenol (vinylguaiacol, Vg) via the quinone methide intermediate to establish equilibrium before condensation reactions proceeded. Only the <jats:italic>α</jats:italic>-5-type condensation product between Ap and Cr (ApCr, 1-(4-hydroxy-3-methoxyphenyl)-1-(2-hydroxy-3-methoxy-5-methylphenyl)ethane) and the <jats:italic>α</jats:italic>-<jats:italic>β</jats:italic>-type condensation product between Ap and Vg or two molecules of Vg (ApVg, <jats:italic>trans</jats:italic>-1,3-bis(4-hydroxy-3-methoxyphenyl)but-1-ene) were identified without detecting any self-condensation products of Ap. The <jats:italic>α</jats:italic>-<jats:italic>β</jats:italic>-type condensation has not been well known and is an important finding of this study. The formation of ApVg was over 10 times faster than that of ApCr, which demonstrates that the <jats:italic>α</jats:italic>-<jats:italic>β</jats:italic>-type condensation is a major mode in soda cooking. However, because origins of <jats:italic>α</jats:italic>-<jats:italic>β</jats:italic>-type condensation substructures, such as C<jats:sub>6</jats:sub>-C<jats:sub>2</jats:sub>-type enol ethers, do not exist in native lignin, the results support our previous conclusion that the condensation reactions of lignin progress less frequently than previously believed.</jats:p>

<jats:title>Abstract</jats:title><jats:p>Particle gluing operating parameters in particleboard (PB) production have an important influence on the mechanical properties of PBs. This study developed a multi-objective optimization model based on support vector regression (SVR) optimized by the non-dominated sorted genetic algorithm-II (NSGA2) to realize the multi-objective accurate prediction of PB mechanical properties (modulus of elasticity (MOE), modulus of rupture (MOR), and internal bonding (IB) strength) by adjusting particle gluing operating parameters. The NSGA2-SVR multi-objective prediction model was trained by 496 groups of experimental data of particle gluing operating parameters and PB mechanical properties. The prediction results of the NSGA2-SVR multi-objective prediction model were evaluated by 124 groups of experimental data and compared with the prediction results of the back propagation neural network (BPNN) model, general regression neural network (GRNN) model, and SVR model. The mean absolute percentage errors (MAPEs) of the NSGA2-SVR model were 49.11%, 33.64%, and 24.20% lower than that of the BPNN model, GRNN model, and SVR model, respectively. The Theil’s inequality coefficients (TICs) of the NSGA2-SVR model were 40.93%, 27.39%, and 18.58% lower than that of the BPNN model, GRNN model, and SVR model, respectively. The results showed that the multi-objective prediction model based on NSGA2-SVR has a superior fitting and higher prediction accuracy for the prediction performance of particle gluing operating parameters, and the NSGA2-SVR model can be applied to the multi-objective synchronous prediction of particle gluing operating parameters in the PB production line.</jats:p>

<jats:title>Abstract</jats:title><jats:p>The leaves and twigs of <jats:italic>Lindera</jats:italic> spp. have long been used as a herbal medicine and toothpicks in Japan. However, little is known about individual variations in the extractives of these species, because many previous studies have not distinguished extractives between individuals. In this study, we investigated the extractives of <jats:italic>L. umbellata</jats:italic> at the individual level. The detailed identification of the inter- and intra-individual variations in the major terpenoids and flavonoids in native <jats:italic>L. umbellata</jats:italic> may greatly contribute to the development of cultivation techniques and the effective use of forest resources. The contents of major components of <jats:italic>L. umbellata</jats:italic>, including four terpenoids (1,8-cineole, linalool, geraniol, and geranyl acetate) and five low-molecular-weight phenolics (pinocembrin chalcone, pinocembrin, pinostrobin chalcone, pinostrobin, and 5,6-dehydrokawain), were analyzed in leaves and twigs seasonally (June, August, and October). The compositions of the major terpenoids were strongly dependent on the properties of each individual and were generally independent of leaves and twigs. Moreover, geranyl acetate was characteristically present in the twigs of some individuals. As new findings regarding linalool, some individuals showed characteristic enantiomeric excesses, presumably because of biotic factors, and the proportion of these enantiomers was kept constant in each individual, regardless of the season. The total phenolic contents in leaves were more than twice those detected in twigs, and the leaves tended to contain more chalcones and twigs more flavanones. Furthermore, the contents of chalcones (pinocembrin chalcone vs. pinostrobin chalcone) and flavanones (pinocembrin vs. pinostrobin) were positively correlated in both leaves and twigs. The coefficient of variation (CV) clearly showed that the content of the major terpenoids was determined by inter-individual rather than intra-individual differences. Although the results obtained in this study should at present only be applicable to a limited population native to specific regions, our findings provide key knowledge in considering the sustainable use of <jats:italic>L. umbellata</jats:italic>.</jats:p>

<jats:title>Abstract</jats:title><jats:p>This study investigated using waste mushroom beds as insulation material and applied compression-drying to eliminate the coarse voids that are unfavorable for insulation. The relationship between air-dry density and thermal conductivity was investigated. The mean air-dry density of the uncompacted waste mushroom beds was approximately 200 kg/m<jats:sup>3</jats:sup>, which increased to approximately 550 kg/m<jats:sup>3</jats:sup> after four levels of compression-drying. A linear relationship was recognized between the air-dry density and thermal conductivity of the waste mushroom bed. Comparing this relationship to those of wood and mat-formed wood-based panels showed that the thermal conductivity of a waste mushroom bed is similar to that of wood at low densities and mat-formed wood-based panels at high densities. Furthermore, the thermal conductivity of heat bridges was estimated using a series–parallel heat-flow model for voids and substances, and the substance thermal conductivity was in the order of wood (0.218 W/mK), waste mushroom bed (0.288 W/mK), and mycelium (0.368 W/mK). The same heat-flow model was applied to a waste mushroom bed to obtain the substance thermal conductivity along the heat-flow direction. The results show that the waste mushroom bed substance also has an anisotropic thermal conductivity.</jats:p>