Artificial neural network modeling for predicting final moisture content of individual Sugi (Cryptomeria japonica) samples during air-drying

Sugi (Cryptomeria japonica D. Don) lumber is known to have a large variability in final moisture content (MC_f) and is difficult to dry. This study assessed the capability of artificial neural networks (ANNs) to predict the MC_f of individual wood samples. An ANN model was developed based on initial moisture content, basic density, annual ring orientation, annual ring width, heartwood ratio and lightness (L ^* in the CIE L ^* a ^* b ^* system). The performance of the ANN model was compared with a principal component regression (PCR) model. The ANN model showed good agreement with the experimentally measured MC_f with a higher correlation coefficient (r) and a lower root mean square error (RMSE) than the PCR model, demonstrating the importance of nonlinearity of the variables and the higher capability of the ANN model than the PCR model. By adding redness (a ^* ) and yellowness (b ^* ) and drying time to the input variables of ANNs, r and RMSE values were improved to 0.98 and 1.2 % for the training data set, and 0.85 and 2.2 % for the testing data set, respectively. Although the developed ANNs are available under the limited conditions of this study, our results suggest that the ANNs proposed offer reliable models and powerful prediction capability for the MC_f, even though wood properties vary considerably and their complex interrelations are not fully elucidated.     

Moisture content variability in kiln-dried <Emphasis Type="Italic">Gmelina arborea</Emphasis> wood: effect of radial position and anatomical features

Gmelina arborea is one of the most important species for plantation in tropical areas. However, high variability in final moisture content (MC_f) is a problem in the drying process. This study sought to determine the variability in MC_f in relation to distance from the pith (DP), and anatomic elements. Boards of 1.2 cm in thickness obtained from bark to the pith from 15-year-old plantation trees were dried in a pilot kiln. Anatomical characteristics, initial moisture content (MC_i), and specific gravity (SG) were also determined. Pearson correlation matrix was conducted between MC_f and the other variables. DP, fiber length, and ray width were correlated negatively with MC_f, while fiber diameter was positively correlated. Other studied anatomical properties showed no statistical correlations. Other wood properties such as SG and MC_i showed some influence on MC_f. DP can be considered as a good practical predictor for MC_f in G. arborea because some wood properties are related to MC_f. However, other wood characteristics that are not related with DP also influence MC_f, such as the presence of sapwood, MC_i variation between and within trees, fiber diameter, and ray width. These results suggest that MC_f variation in G. arborea is difficult to determine.     

Treatment of sugi （Cryptomeria japonica D.） sapwood with aqueous solution of acetic acid

Sugi sapwood samples were processed with aqueous solution of acetic acid in order to find the response of the weight of sugi sapwood and the treatment of aqueous solution of acetic acid. The result showed that loss of weight for the treated sugisapwood was about equal to yield of extracts from sugi sapwood, and increased with the increment of the concentration of aqueous solution of acetic acid. Fourier transform infrared spectroscopy spectra changes of the treated sugi wood and extracts from sugi sapwood were analyzed by FT-IR spectroscopic technique. Increasing tendency of absorption intensities of the stretching vibration at 3 400 cm^-1 of hydroxyl group (OH) and C=C in lignin stretching vibration at 1510 cm^-1 of benzene ring inlignin were observed from FT-IR of the treated sugi sapwood. From FT-IR spectra of extracts from sugi sapwood by aqueoussolution of acetic acid, the dissolution of lignin was observed during the treatment with 30% acetic acid solution aqueous.     

Environmental effects on the color of sugi (Cryptomeria japonica D. Don) heartwood

Sugi (Cryptomeria japonica D. Don) is one of the most important planted trees in Taiwan. The normal heartwood of sugi has a red to pinkish rose color. Unfortunately, this pleasant appearance is susceptible to discoloration after environmental exposures. This discoloration is a serious defect that decreases the value of sugi products. The objective of this study was to investigate the effects of environmental factors such as moisture, oxygen, and lights of different wavelengths on the discoloration of sugi. The results show that under the combined effects of light and oxygen the color of heartwood changes from red (or rosepink) to bluish green. The color further darkens and eventually turns to black with the presence of moisture. As for the effect of light wavelengths on the discoloration of sugi heartwood, it was found that the red color was enhanced after being irradiated with light of wavelengths above 600 nm. Botha ^* andb ^* values increased significantly as a result of such exposure.     

Colorimetry of wood specimens from French Guiana

The color of 97 species of wood specimens from French Guiana was measured on their radial and tangential surfaces with a colorimeter. We obtained the tristimulus values of X, Y, and Z of the 10° standard observer under the illuminant of D ₆₅, and the values of the CIELAB color system, L ^*, a^*, b^*, C^*, and h. When the lightness index (L ^*) was <54, b ^*, C ^*, and h showed positive correlations against L ^*. When L ^* was >54, a ^* and C ^* showed negative correlations against L ^*. These results imply that wood color should be discussed by separating wood specimens into the high and low-lightness groups. A good positive correlation was found between the L ^* and h throughout the whole range of L ^*. It is thought that the value of h can be an important index, as can L ^*, for comparing of wood color because h shows a simple relation with L ^*.     

Predicting oven-dry density of Sugi (Cryptomeria japonica) using near infrared (NIR) spectroscopy and its effect on performance of wood moisture meter

We propose a non-destructive method to predict the oven-dry density of Sugi (Cryptomeria japonica D. Don) using near infrared (NIR) spectroscopy so as to calibrate a commercial moisture meter. A prediction model for oven-dry density was developed using NIR spectra obtained from Sugi samples with a known density. The density of air-dried Sugi boards was predicted with the developed model. Then, the moisture content (MC) of the boards was measured by a hand-held capacitance-type and an in-line microwave moisture meters. For each board, the moisture meters were calibrated by the predicted density. The predicted density was correlated with the measured one with an R ² of 0.81 and a standard error of prediction (SEP) of 15.3 kg/m³ within the measured density of 279.2–436.4 kg/m³, indicating that the developed model was applicable for predicting oven-dry density of Sugi. The MC readings of both moisture meters showed a good correlation with the oven-dry MC that ranged from 12.1 to 28.9 %. For both moisture meters, the density calibration with the NIR-predicted density gave a higher R ² and a lower SEP than with the conventional calibration with the mean density. These results demonstrate that the present density calibration using NIR spectroscopy could improve the performance of the moisture meters for the air-dried Sugi boards with varying densities.     

Wood properties and their among-family variations in 10 open-pollinated families of Picea jezoensis

This study aimed to evaluate radial and among-family variations of wood properties in Picea jezoensis. A total of 174 trees were randomly selected from 10 open-pollinated families in a progeny trial for measuring stem diameter, dynamic Young’s modulus of log (DMOE_log), annual ring width (ARW), air-dry density (AD), modulus of elasticity (MOE), and modulus of rupture (MOR). Mean values of DMOE_log, AD, MOE, and MOR were 9.60 GPa, 0.41 g/cm³, 9.44 GPa, and 76.6 MPa, respectively. Significant differences among families were observed in all properties. F values obtained by analyzing variance in wood properties were higher than those generally observed in growth traits. In addition, F values in wood properties remained relatively higher from the 1st to 25th annual ring from the pith, although F value in ARW rapidly decreased with each increase in annual ring number. These results indicate that genetic factors largely contributed to the variance in wood properties compared with the growth traits.     

Nondestructive evaluation of drying stress level on wood surface using near-infrared spectroscopy

A nondestructive technique for swiftly measuring the stress level of the surface of wood is proposed, which is important for process control in timber drying. Partial least squares (PLS) regression models for predicting surface-released strain (ε) were developed using NIR spectra obtained from Sugi (Cryptomeria japonica D. Don) samples during drying. The predictive ability of the models was evaluated by PLS analysis and by comparing NIR-predicted ε with laboratory-measured values. The PLS regression model using the NIR spectra pre-processed by MSC and second derivatives with a wavelength range of 2,000–2,220 nm showed good agreement with the measurement (R ² = 0.72). PLS analysis identified the wavelengths around 2,035 nm as making significant contributions to the prediction of ε. Orthogonal signal correction (OSC) was an effective pre-processing technique to reduce the number of factors required for the model using the wavelength range 1,300–2,500 nm. However, the predictive ability of the OSC-corrected model was not improved. Elapsed times to reach the maximum tensile stress (T _max) and the stress reversal point (T _rev) at the wood surface during drying were detected correctly for 75 % of the samples. The results show that NIR spectroscopy has potential to predict the drying stress level of the timber surface and to detect critical periods in drying, such as T _max and T _rev.     

Microfibril angle and density of hinoki (Chamaecyparis obtusa) trees in 15 half-sib families in a progeny test stand in Kyushu, Japan

It was previously believed in Japan that the wood qualities of hinoki (Chamaecyparis obtusa) were superior to sugi (Cryptomeria japonica). However, few studies of wood properties such as MFA (microfibril angle of S₂ layer in secondary wall of tracheid) have been completed for hinoki. Some reports have found that hinoki plus tree families have similar mechanical properties to sugi. Here we report the characteristics of MFA and density of hinoki half-sib families in a progeny test stand. There were significant differences in MFA and density between families. The wood properties of two families, Nakatsu 3 and Kanzaki 5, are stable in radial pattern and suitable for structural use. Early selection of hinoki families by MFA and density may be difficult. Effects of MFA and density on E _d (dynamic modulus of elasticity) of logs differed between families. The effects of growth rate on MFA and density differed between families and also between juvenile and mature wood. The faster growth rate in Nakatsu 3 appeared to improve wood properties and increase E _d of logs, although in many other families, faster growth rate had negative effects on desirable wood properties for structural use.     

Heat-induced colour changes of pine (Pinus pinaster) and eucalypt (Eucalyptus globulus) wood

Heat treatment of Pinus pinaster and Eucalyptus globulus wood was carried out by hot air in an oven for 2–24 h at 170–200°C and by steam in an autoclave for 2–12 h at 190–210°C. The colour parameters L*, a* and b* were determined by the CIELAB method on radial, tangential and transverse sections of untreated and treated wood, and their variation with regard to the treatment (ΔL*, Δa* and Δb*) were calculated in percent. For untreated eucalypt wood, lightness (L*) varied between 54.1 and 63.8% with a* between 7.4 and 8.5, and b* between 15.7 and 19.9. For untreated pine wood, L* varied between 67.3 and 76.1%, a* between 6.9 and 7.6 and b* between 16.3 and 24.1. Oven heat-treated wood became darker (ΔL* about 50% for 4% mass loss), and this was more for eucalypt wood under the same treatment conditions. In general, the contribution of red (a*) and yellow (b*) colour decreased with heat treatment. The transverse section of the two species darkened less for both the treatments with small differences between radial and tangential sections. Lightness decrease was related to chemical changes; with good correlations with glucose (R ² = 0.96), hemicelluloses (R ² = 0.92) and lignin (R ² = 0.86). As regards colour, the heat treatments showed an interesting potential to improve the wood quality for solid timber products from pine and eucalypt.     

Evaluation of dried-wood odors: comparison between analytical and sensory data on odors from dried sugi (<Emphasis Type="Italic">Cryptomeria japonica</Emphasis>) wood

The emissions of volatile organic compounds from air-dried, conventionally dried, and high-temperaturedried sugi wood were compared by gas chromatographymass spectrometry. Terpenes were clearly the main compound group in the air-dried wood samples, whereas acetic acid was only detected in the high-temperature-dried wood samples, indicating that considerable changes occurred in the volatile compound emission profile during hightemperature processing. The most abundant compounds in the air-dried wood and conventionally dried wood were δ-cadinene, α-muurolene, and β-cadinene (sesquiterpenes) for all specimens, and a-pinene and D-limonene (monoterpenes) for conventionally dried wood and air-dried wood. In contrast, acetic acid was detected only in the hightemperature-dried wood. Sensory evaluation of volatile organic compounds was performed by 18 male university students. Volatile compounds of air-dried wood and conventionally dried wood were assessed as being significantly more soothing than those from high-temperature-dried wood. This study was presented in part at the 57th Annual Meeting of the Japan Wood Research Society, Hiroshima, August 2007     

醋酸水溶液处理对杉树材影响

为了研究醋酸水溶液处理给杉树材重量带来的变化,使用醋酸水溶液对杉树材进行了处理。结果发现处理后杉树材重量的减小量大约等于抽出物的重量,而且随着醋酸水溶液浓度的增加而增加。利用傅立叶变换红外光谱法对处理后的杉树材及抽出物进行了光谱分析。从处理后杉树材的光谱图可以观察到3400cm-1附近的OH伸缩振动及1510cm-1附近的木质素中苯环C=C伸缩振动的吸收强度有增加倾向。从醋酸水溶液抽出物光谱图可以发现用浓度30%醋酸水溶液处理时木质素被溶出。图2表2参6。     

Evaluation of end-check propagation based on mode I fracture toughness of sugi (<Emphasis Type="Italic">Cryptomeria japonica</Emphasis>)

The relation between crack propagation based on fracture mechanics and end-check propagation during drying was evaluated in this study. Corresponding to the direction of end-check propagation, the mode I fracture toughness of air-dried sugi specimens in TR, TL, and intermediate systems was examined by single-edge-notched bending tests. The occurrence and propagation of end checks on sugi (Cryptomeria japonica D. Don) blocks during drying were observed at the scale of the annual rings. It was found that the critical stress intensity factor (K _IC) decreased as the crack propagation changed from TL to TR. The value of K _IC in the TR system was significantly lower than that in the TL system. As a measure of fracture energy, the area under the load-crack opening displacement curve in the TR system was more than twice that in the TL and intermediate systems. These results indicate that cracks perpendicular to the tangential direction initiate radially with ease, and then crack arrest occurs to prevent growing. This finding provides a consistent interpretation of the end-check propagation observed during drying as follows: tiny end checks, as an analog of TR cracks, occur easily and selectively in latewood or transition wood and propagate toward the pith during drying. When there is no corresponding secondary check in the forward latewood, the checks are arrested and do not propagate further.     

Antifungal activity of essential oils isolated from Egyptian plants against wood decay fungi

The essential oils of eighteen Egyptian plants were extracted by hydrodistillation and their chemical compositions were analyzed by GC-MS. The antifungal activity of the isolated oils was evaluated against two wood decay fungi Hexagonia apiaria and Ganoderma lucidum in vitro. The essential oil of Artemisia monosperma showed the highest inhibitory effect against H. apiaria (EC₅₀ = 31 mg L^?1) and G. lucidum (EC₅₀ = 53 mg L^?1). The results of in vitro tests indicated that the essential oils of Cupressus sempervirens, Citrus limon, Thuja occidentalis, Schinus molle, A. monosperma and Pelargonium graveolens were the most potent inhibitors against both fungi. These six oils caused significant reduction of wood mass loss of Scots pine sapwood after 6 weeks of fungal exposure. The oil of C. limon revealed the highest reduction of wood mass loss caused by H. apiaria, while A. monosperma oil displayed the highest reduction of wood loss caused by G. lucidum. These results support the potential use of essential oils for wood protection against decay fungi.     

尾叶桉与赤桉正反析因交配杂种F_1材性遗传参数的估算

[目的]通过尾叶桉与赤桉杂种F1材质性状的遗传参数估算及其分析,为桉树杂交育种材性改良亲本选配和交配设计提供理论依据。[方法]以尾叶桉与赤桉6×6正反析因交配杂种F1测定林为材料,并以相应亲本自由授粉的半同胞子代作对照。9年生时,对各小区的杂种和家系(5株小区,6次重复)选取2株平均木,在胸高1. 3 m处沿南北向钻取木芯,共984个,测定木材基本密度、纤维长、纤维宽和纤维长宽比,利用ASReml-R估算4个材质指标的特殊配合力、杂种优势、父母本单株狭义遗传力、遗传相关和表型相关系数。[结果]表明:尾叶桉与赤桉正反交的杂种木材基本密度优于对照,呈明显的杂种优势;反交组合杂种其木材基本密度优于正交组合杂种,正交组合杂种的纤维特性优于反交组合的;在正交组合杂种中,木材基本密度、纤维长和纤维长宽比的母本效应低于父本效应;而反交组合杂种中,4个材质指标的母本效应均高于父本效应。木材基本密度和纤维特性指标受中至低遗传控制。正反交组合杂种中,除纤维长宽比外,其余3个材质指标的显性效应大于加性效应。对于遗传相关,杂种的木材基本密度与纤维宽呈极显著的负相关,与纤维长宽比呈极显著的正相关,与纤维长呈不显著负相关,纤维长与纤维宽呈显著正相关。对于表型相关,除纤维宽与纤维长宽比呈不显著正相关外,其余性状间均呈极显著正相关。[结论]尾叶桉与赤桉杂种的材质性状遗传差异因亲本和交配方式而异,表明通过种间杂交和正向选择进行材质性状的遗传改良具有潜力。     

Comparative study on growth,wood quality and financial returns of teak (Tectona grandis L.f.) managed under three different agroforestry practices

Growth, wood quality parameters and productivity estimations of 12-year-old teak (Tectona grandis L.f.) grown under three agroforestry systems, namely unmanaged block (B_um), unmanaged line on the farm boundary (L_um) and intensively managed block (B_im) plantations are studied. Mean annual increment (MAI) of 0.020, 0.006 and 0.016 m³ tree^?1 year^?1 was recorded in L_um, B_um and B_im, respectively. Overall growth performance of teak raised in L_um, plantation appears to be better than two block plantations (B_um and B_im). For evaluating various wood quality parameters, tree logs from each plantation were tested for different physical and mechanical properties according to the standard procedures. The wood quality of B_um was found to be comparatively superior to B_im and much better than those of L_um. The 12-year-old farm teak trees from three systems exhibited lower average values of different wood quality parameters compared to mature forest teak. Since physical and strength properties of B_um were inferior compared to L_um and B_im, its exploitation is not advisable at this stage. Line plantation, however, releases land for cultivation of arable crops and does not demand any special silvicultural management as required by B_im. Although, total extractable volume of teak wood available after 12-years of age from B_um was much smaller compared to B_im or L_um, its commercial exploitation at an early age may be preferred over other two practices due to better wood quality and lower management cost. For optimum economic utilization and mechanical maturity of wood, harvesting of block plantation may be delayed for about 10-15 years because growth volume and strength properties are expected to improve with age of tree.     

醋酸水溶液预处理对柳杉木材炭化的影响

杉木(日本柳杉)经醋酸水溶液处理后，重量减少。将处理前后柳杉木材在4℃下进行炭化，得到了木醋液、木焦油和木炭。与未处理材相比，处理材木醋液的收率增加，而木焦油和木炭的收率减少。处理液的醋酸浓度增加后，木醋液和木焦油的收率几乎不变，但木炭的收率稍微减少了。用毛细管气相色谱法对木醋液的成分进行了定量分析。与未处理材相比，处理材木醋液中糠醛(呋喃甲醛)及5-羟甲基糠醛的收量增加，而羧酸类、苯酚类、邻苯二酚、愈创木酚类及麦芽酚的收量几乎不变。当醋酸浓度从0增至3％时，糠醛的收量随着增加，但是当醋酸浓度从3％增至30％时，其收量却几乎不变。     

Study of hydration behaviors of wood-cement mixtures: compatibility of cement mixed with wood fiber strand obtained by the water-vapor explosion process

To provide information on the feasibility of using exploded wood fiber strand (WFS) obtained by the water-vapor explosion process in wood-cement mixtures, the compatibility between cement and exploded WFS and its improvement with various additive chemicals were investigated by observation and analysis on hydration behaviors in terms of hydration characteristics: maximum hydration temperature (T _max) and required time (t _max). The three types of cement, six additive chemicals, and exploded WFS (sugi, air-dried and water-soaked) were employed as raw materials in this study. The hydration behaviors of mixtures demonstrated that exploded WFS had strong retarding effects on cement hydration and completely prevented mixtures from setting. The analysis of sugar revealed that the sugar contents of exploded WFS were much higher than those in unexploded wood and increased to about 20-fold (air-dried) and 10-fold (water-soaked), respectively. The degraded polysaccharides became a major factor and played an important role in inhibiting the setting of cement. Moreover, high-performance liquid chromatography analysis proved that the main peaks representing the molecular weight of polysaccharides in extractives of exploded WFS shifted markedly to a lower range of polymerization. MgCl₂ was determined to be an effective additive chemical for restraining the inhibitory influences. Addition contents of 2%–3% and 4%–5% were available and acceptable for quick-curing cement and ordinary Portland cement, respectively. As for the furnace-slag cement, the composite additive chemicals of MgCl₂ (4%) and CaO (2%) were found to have an obvious accelerating effect.Part of this report was presented at the 51th Annual Meeting of the Japan Wood Research Society, Tokyo, April 2001     

Drying and anatomical characteristics of sugi wood attacked by bacteria during pond storage

Seven species of bacteria were isolated and identified from ponded sugi (Cryptomeria japonica D. Don) logs, and six species showed potent wood-degrading activities. To evaluate the effects of these isolated bacteria on the drying and anatomical characteristics of wood, small fresh blocks of sugi were immersed in water suspensions containing bacteria for 1–7 months. The permeability and drying properties were evidently improved. Most of the encrusting substances adhering to the cell lumens and the pit chambers were removed, and the pit membranes were destroyed. These anatomical changes due to bacterial activity were assumed to improve the permeability of sugi wood.Part of this report was presented at the 40^th annual meeting of the Japan Wood Research Society, Tsukuba, April 1990; the 41^st annual meeting of the Japan Wood Research Society, Matsue, April 1991; and the IUFRO XX World Congress, Tampere, August 1995     

HTST hydrolysis of wood: Modelling of the kinetics and projections on reactor configuration

Summary We present experimental data on hydrolysis of wood in high temperature short residence time (HTST) and low acid concentration conditions. Effects of temperature, acid concentration, particle size and liquid/solid ratio are discussed. A kinetic model is proposed which accounts for effects of temperature and acid concentration. This kinetic model is used to predict performance of a twin-screw extruder as a hydrolyser which consists of ideal mixed flow or plug flow reactor units in series.Symbols A Acid concentration in liquid phase - A Acid concentration in solid phase - A₀ Initial mass of sulphuric acid, g - C Cellulose content of solid phase, % - d Diameter of wood particles, m - E₁ Activation energy of cellulose hydrolysis, cal. mol^-1 - E₂ Activation energy of glucose degradation, cal. mol^-1 - F Objective function, refers to Eq. (5) - G Glucose yield - G_e Glucose yield at equilibrium - G_{i, exp} Experimental glucose yield (Eq. (5)) - G_{i, th} Calculated glucose yield (Eq. (5)) - G_max Maximum glucose yield - k^* Parameter defined by Eq. (9) - k₁ Rate constant of cellulose hydrolysis, s^-1 - k₂ Rate constant of glucose degradation, s^-1 - k ₁ ^* Apparent rate constant of cellulose hydrolysis, s^-1 - k ₂ ^* Apparent rate constant of glucose degradation, s^-1 - k₁₀ Pre-exponential factor of constant k₁, s^-1 - k₂₀ Pre-exponential factor of constant k₂, s^-1 - K Parameter defined in Table 3 - m Constant - m_g Mass of glucose produced, g - M₀ Initial mass of wood, g - M Mass of saturated steam delivered, g - M Mass of saturated steam delivered after 120 s of reaction time, g - m₀ Initial mass of water, g - n Constant - N Number of reactor units - q_i Volume flow rate in reactor units, m³ · s^-1 - r_g Conversion rate of glucose, s^-1 - R Ideal gas constant, 1.987 cal · mol^-1 K^-1 - t Reaction time, s - T Temperature, K - V_i Volume of reactor units, m³ - W Water content of wood sample, % - X, X Parameters defined in Table 3 - Y, Z Parameters defined in Table 3 - Constant defined in Eq. (4), s^-1 - v Number of experimental points (Eq. (5)) - _i Residence time in plug flow unit, s - _i Residence time in mixed flow unit, s