Faculty Profiles - INAGAKI Tetsuya

Papers - INAGAKI Tetsuya

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Selective assessment of duplex heat-treated wood by near-infrared spectroscopy with principal component and kinetic analyses Reviewed Open Access

Tetsuya Inagaki, Yuuki Asanuma, Satoru Tsuchikawa

JOURNAL OF WOOD SCIENCE Vol. 64 ( 1 ) page： 6 - 15 2018.2

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal) Publisher：SPRINGER JAPAN KK

We selectively assessed the thermal and hygrothermal treatment times of duplex heat-treated samples from the softwood hinoki cypress (Chamaecyparis obtusa) and the hardwood Japanese zelkova (Zelkova serrata) using near-infrared (NIR) spectroscopy with principal component analysis (PCA) and spectral-kinetic analysis. Wood samples from each species were thermally or hygrothermally treated at 120, 130, 150, and 180 A degrees C, and the second-derivative spectra of these samples in the 6300-5450 cm(-1) range, where moisture content has the smallest effect, were then subjected to PCA. The master curve that was calculated by kinetic analysis successfully explained changes in the first principal component (PC1) scores with thermal treatment time for all temperatures. The angles between the PC1 loadings that explained the spectral variation due to thermal and hygrothermal treatment were 79A degrees for hinoki and 80A degrees for zelkova. Thus, calculation of the inner product between the second-derivative spectra of duplex heat-treated wood and a loading vector that explained the spectral variation due to thermal or hygrothermal treatment allowed us to selectively assess the thermal and hygrothermal treatment times.

DOI： 10.1007/s10086-017-1670-z

Web of Science

Scopus

Effect of cellular structure on the optical properties of wood Reviewed Open Access

Mayuka Ban, Tetsuya Inagaki, Te Ma, Satoru Tsuchikawa

JOURNAL OF NEAR INFRARED SPECTROSCOPY Vol. 26 ( 1 ) page： 53 - 60 2018.2

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal) Publisher：SAGE PUBLICATIONS LTD

To construct robust calibrations of wood properties by near infrared spectroscopy, one must independently evaluate the spectral contributions of light absorption and light scattering. However, the light propagation in wooden cellular structures is difficult to interpret because these structures are complex, heterogeneous, and anisotropic. This study investigates the reduced scattering coefficients of softwood and hardwood (with ring-porous or diffuse-porous vessels) at 846 nm by time-resolved spectroscopy. It also evaluates the effect of wooden cellular structure and air-dry density on the light propagation. After determining the reduced scattering coefficients, we observed cross-sectional microscopic images of the wood samples. Eighty-five percent of the variation in the reduced scattering coefficients was explainable by the air-dry density, area ratio of the cell wall, and the median pore area. Monte Carlo simulations of the light propagation through wood revealed that most of the photon transport occurs in the cell-wall substance.

DOI： 10.1177/0967033518757233

Open Access

Web of Science

Scopus

A novel combined application of capacitive method and near-infrared spectroscopy for predicting the density and moisture content of solid wood Reviewed

Vu Thi Hong Tham, Tetsuya Inagaki, Satoru Tsuchikawa

WOOD SCIENCE AND TECHNOLOGY Vol. 52 ( 1 ) page： 115 - 129 2018.1

Language：English Publishing type：Research paper (scientific journal) Publisher：SPRINGER

The use of a capacitive method and near-infrared (NIR) spectroscopy to simultaneously predict the density and moisture content (MC) of wood samples was investigated. Prediction accuracy of both methods was individually investigated by multivariate analyses. The capacity and absorbance at two wavelengths in the NIR range were combined to predict both the properties by the specific models. All wavelength combinations in the range of 908-1676 nm were tested, and the best combination yielding the highest coefficient of determination (R (2)) was chosen. This novel method showed a strong correlation between predicted and measured data, independent of sample thickness and wood species. The prediction accuracy of the wood samples, from green wood to oven-dried conditions, showed promising results for all thicknesses, with R (2) = 0.79, root-mean-square error of cross-validation (RMSECV) = 0.10 g/cm(3), and residual predictive deviation (RPD) = 2.22 for density and R (2) = 0.80, RMSECV = 25.70%, and RPD = 2.22 for MC. In the case of below fiber saturation point to oven-dried state, R (2) value was slightly decreased in the prediction of MC and slightly increased in the prediction of density, but RMSECV of MC declined significantly (maximum 5.46%) compared to the range of MC from saturated point (maximum 39.56%). These results were considerably better than those obtained by modeling the capacitive or NIR method individually, and improvement was particularly apparent in estimating density. The results suggest the possibility of a new device combining the capacitive method and NIR spectroscopy to predict density and MC more accurately.

DOI： 10.1007/s00226-017-0974-x

Web of Science

Scopus

Near-infrared hyperspectral imaging for classification of mung bean seeds Reviewed Open Access

Kaewkarn Phuangsombut, Te Ma, Tetsuya Inagaki, Satoru Tsuchikawa, Anupun Terdwongworakul

INTERNATIONAL JOURNAL OF FOOD PROPERTIES Vol. 21 ( 1 ) page： 799 - 807 2018

Language：English Publishing type：Research paper (scientific journal) Publisher：TAYLOR & FRANCIS INC

Hard mung bean seeds pose a problem in the sprouting process as they develop mold and infect neighboring seeds. Near-infrared hyperspectral imaging combined with partial least squares discriminant analysis was applied to develop a classifying model to separate hard mung beans from normal ones. The orientation of the measured beans was found to affect the classification result. The optimal partial least squares discriminant analysis model based on all orientations resulted in a correlation coefficient (R) of 0.919 with a root mean squared error of prediction of 0.197. The non-germinative parts were mapped and were concentrated at one end of the bean. Finally, a germinability index was proposed according to the proportion of colored areas between the germinative and non-germinative parts from the hyperspectral imaging results.

DOI： 10.1080/10942912.2018.1476378

Open Access

Web of Science

Scopus

Quality Evaluation of Engineered Wood by THz-TDS Reviewed

Moe Kashima, Satoru Tsuchikawa, Tetsuya Inagaki

2018 43RD INTERNATIONAL CONFERENCE ON INFRARED, MILLIMETER, AND TERAHERTZ WAVES (IRMMW-THZ) Vol. 2018-September 2018

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

This study attempts simultaneous prediction of grain angle, density and moisture content by THz time domain spectroscopy (THz-TDS) which has sufficient spatial resolution and transparency for wood. Terahertz waves transmitted through wood contain information on moisture content, density, grain angle and crystallinity of the sample. In this study, we measured spectra of 14 kinds of wood (5 soft wood, 9 hard woods) at various moisture contents and air-dried douglas fir while rotating the sample against the polarization of the terahertz wave. It was shown that the fiber orientation, density and moisture content of wood can be predicted simultaneously from the calculated complex permittivity.

DOI： 10.1109/IRMMW-THz.2018.8510155

Web of Science

Scopus

Dynamic behavior of wood chemical components under drying process measured by near infrared spectroscopy Reviewed

Shiho Sugii, Takaaki Fujimoto, Harusa Tsutsumi, Tetsuya Inagaki, Satoru Tsuchikawa

JOURNAL OF NEAR INFRARED SPECTROSCOPY Vol. 25 ( 6 ) page： 400 - 406 2017.12

Language：English Publishing type：Research paper (scientific journal) Publisher：SAGE PUBLICATIONS LTD

This study examined the dynamic behavior of wood chemical components during the drying process using near infrared spectroscopy. Principal component analysis and generalized two-dimensional correlation spectroscopy were applied to identify significant absorption bands from the heavily overlapping near infrared spectra. The near infrared spectra were successively acquired over the moisture content range of 60-11%. The principal component analysis scores indicated that the wood-water interaction in the moisture content range of 60-46% significantly differed from that in the range of 45-11%. The synchronous 2D correlation spectrum constructed from the spectra in the moisture content range of 60-46% revealed that the cell wall components and water molecules responded to the drying process even though the wood exceeded the fiber saturation point. In the moisture content range of 45-11%, the H-bonded OH groups in the crystalline region of cellulose clearly increased with the decrease in bound water. Moreover, the sequential order of events was also clarified from the asynchronous spectrum.

DOI： 10.1177/0967033517733379

Web of Science

Scopus

High-Resolution and Non-destructive Evaluation of the Spatial Distribution of Nitrate and Its Dynamics in Spinach (Spinacia oleracea L.) Leaves by Near-Infrared Hyperspectral Imaging Reviewed Open Access

Hao-Yu Yang, Tetsuya Inagaki, Te Ma, Satoru Tsuchikawa

FRONTIERS IN PLANT SCIENCE Vol. 8 2017.11

Language：English Publishing type：Research paper (scientific journal) Publisher：FRONTIERS MEDIA SA

Nitrate is an important component of the nitrogen cycle and is therefore present in all plants. However, excessive nitrogen fertilization results in a high nitrate content in vegetables, which is unhealthy for humans. Understanding the spatial distribution of nitrate in leaves is beneficial for improving nitrogen assimilation efficiency and reducing its content in vegetables. In this study, near-infrared (NIR) hyperspectral imaging was used for the non-destructive and effective evaluation of nitrate content in spinach (Spinacia oleracea L.) leaves. Leaf samples with different nitrate contents were collected under various fertilization conditions, and reference data were obtained using reflectometer apparatus RQflex 10. Partial least squares regression analysis revealed that there was a high correlation between the reference data and NIR spectra (r(2) = 0.74, root mean squared error of cross-validation = 710.16 mg/kg). Furthermore, the nitrate content in spinach leaves was successfully mapped at a high spatial resolution, clearly displaying its distribution in the petiole, vein, and blade. Finally, the mapping results demonstrated dynamic changes in the nitrate content in intact leaf samples under different storage conditions, showing the value of this non-destructive tool for future analyses of the nitrate content in vegetables.

DOI： 10.3389/fpls.2017.01937

Open Access

Web of Science

Scopus

The effect of path length, light intensity and co-added time on the detection limit associated with NIR spectroscopy of potassium hydrogen phthalate in aqueous solution Reviewed Open Access

Tetsuya Inagaki, Tomoko Watanabe, Satoru Tsuchikawa

PLOS ONE Vol. 12 ( 5 ) page： e0176920 2017.5

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：PUBLIC LIBRARY SCIENCE

Near infrared (NIR) spectroscopy is a common means of non-invasively determining the concentrations of organic compounds in relatively transparent aqueous solutions. Rigorous determination for limit of detection (LOD) is of importance for the application use of NIR spectroscopy. The work reported herein determined the LOD with the analysis of potassium hydrogen phthalate (KHP) in water with partial least square (PLS) calibration in the range of 6300 - 5800 cm (-1) between the two strong absorption bands of water, in which the C-H overtone bands of KHP are located. A comparison of the LOD estimated when using various condition (path length, aperture and co-added scan times) showed that the lowest LOD for KHP obtained with a fiber optic cable attachment equipped NIR spectrometer is approximately 150 ppm.

DOI： 10.1371/journal.pone.0176920

Calibration of SilviScan data of Cryptomeria japonica wood concerning density and microfibril angles with NIR hyperspectral imaging with high spatial resolution Reviewed

Te Ma, Tetsuya Inagaki, Satoru Tsuchikawa

HOLZFORSCHUNG Vol. 71 ( 4 ) page： 341 - 347 2017.4

Language：English Publishing type：Research paper (scientific journal) Publisher：WALTER DE GRUYTER GMBH

Wood density and microfibril angle (MFA) are strongly correlated with wood stiffness, swelling/shrinkage, and its anisotropy. Understanding the spatial distribution of these data is critical for solid timber applications. In this study, near-infrared (NIR) hyperspectral imaging has been calibrated for evaluation of wood density and MFA in an effective manner. Briefly, five wood samples collected from both normal wood (NW) and compression wood (CW) moieties of two different Cryptomeria japonica trees were analyzed. Partial least squares (PLS) regression analysis was performed to determine the relationship between X-ray densitometry data obtained by SilviScan and NIR spectra, and cross-validation (leave-one-out) approach served for prediction performances. The validation coefficient of determination (r(2)) between the predicted densities by the NIR technique and the X-ray data was 0.83 with a root mean squared error of cross-validation (RMSECV) of 105.2 kg m(-3). Regarding MFA, the r(2) was 0.77 and RMSECV 5.36 degrees. Wood density was successfully maped as well as the MFA at a high spatial resolution. As a result, the detection of annual growth ring features and evaluation of aspects of heterogeneous wood quality has been facilitated. The mapping results were visually checked by looking at the difference between earlywood (EW) and latewood (LW) for density and by means of the Maule color reaction indicating high lignin contents in CW in terms of MFA validation as CWs have high MFA values.

DOI： 10.1515/hf-2016-0153

Web of Science

Scopus

Classification of mung bean seeds for sprout production using near-infrared spectroscopy and hyperspectral imaging Reviewed

K. Phuangsombut, A. Terdwongworakul, N. Suttiwijitpukdee, A. Phuangsombut, S. Tsuchikawa, T. Inagaki, T. Ma

Vol. 23 page： 23-29 2017

Stiffness and moisture content prediction model of wooden veneer using fast online near-infrared (NIR) spectroscopic system Reviewed

Forestry Research and Engineering: International Journal Vol. 1 page： 00006 2017

Modulus of elasticity prediction model on sugi (Cryptomeria japonica) lumber using online near-infrared (NIR) spectroscopic system Reviewed International coauthorship

International Wood Products Journal Vol. 8 page： 193 - 200 2017

Modulus of elasticity prediction model on sugi (Cryptomeria japonica) lumber using online near-infrared (NIR) spectroscopic system Reviewed

Imran Arra'd Sofianto, Tetsuya Inagaki, Kouchi Kato, Mariya Itoh, Satoru Tsuchikawa

INTERNATIONAL WOOD PRODUCTS JOURNAL Vol. 8 ( 4 ) page： 193 - 200 2017

Language：English Publishing type：Research paper (scientific journal) Publisher：TAYLOR & FRANCIS LTD

In this study, static bending measurements and online NIR spectra acquisitions were combined to construct modulus of elasticity (MOE) prediction model for sugi lumber. NIR spectra were acquired from tangential surface of sugi lumbers at a speed of 120 m min(-1) to assess its effectiveness in the wood industry. Cross-validation partial least squares regression (CV-PLSR) and test-set-validation partial least squares regression (TSV-PLSR) analyses were employed for analysing the data. The second derivative (2d) spectra with 19 smoothing points (Savitzky-Golay algorithm, second polynomial) gave the best result as spectral pre-processing treatment with the lowest root mean square error of cross-validation and the highest coefficient of determination for cross-validation based on the optimum number of latent variables as assessed from the minimum validation residual variance value in the CV-PLSR analysis. These 2d spectra were then used in the TSV-PLSR analysis for 100 repetitions to check the robustness of the calibration.

DOI： 10.1080/20426445.2017.1378398

Web of Science

Scopus

Estimation of wood density, moisture content and fiber orientation by THz time domain spectroscopy Reviewed

Tetsuya Inagaki, Moe Kashima, Satoru Tsuchikawa

28th International Conference on Wood Science and Technology, ICWST 2017: Implementation of Wood Science in Woodworking Sector page： 3 - 6 2017

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (international conference proceedings) Publisher：University of Zagreb - Faculty of Forestry

Terahertz (THz) radiation has the potential to be a useful tool for sensing and imaging of wood because wood is relatively transparent at these frequencies (below about 1 THz). In this study, demonstration of simultaneous prediction of solid wood density, moisture content and fiber orientation, all of which are critical in manufacturing operations, of 14 species including softwood and hard wood was accomplished using terahertz time-domain spectroscopy (THz-TDS). THz measurements of wood at various moisture contents were taken for 19 orientations of the THz field (0-180o with 10o step) with respect to the visible grain. The real part of refractive index value and absorption cosfficient had strong correlation with density and moisture content of the wood. A strong correlation between measured and predicted values for density and moisture content were observed. The possibility for the estimation of fiber orientation using the birefringence property of wood were shown.

Scopus

NIR Spectral-kinetic analysis for thermally degraded Sugi (Cryptomeria japonica) wood Reviewed

Tetsuya Inagaki, Miyuki Matsuo and Satoru Tsuchikawa

Applied Physics A 2016

Effect of heat treatment on colour changes of black alder and beech veneers Reviewed Open Access

Salca, EA, Kobori, H, Inagaki, T, Kojima, Y, Suzuki, S

JOURNAL OF WOOD SCIENCE Vol. 622 page： 297-304 2016

Three-fibre-based diffuse reflectance spectroscopy for estimation of total solid content in natural rubber latex Reviewed

Tetsuya Inagaki Daisuke Nozawa, Yoshiaki Shimomura and Satoru Tsuchikawa,

Journal of Near infrared spectroscopy Vol. 24 page： 327-335 2016

Optical Properties of Drying Wood Studied by Time-Resolved Near-Infrared Spectroscop Reviewed Open Access

Konagaya K., Inagaki T., Kitamura R. and Tsuchikawa S

Optic Express Vol. 9 page： 9561-9573 2016

Fast online NIR technique to predict MOE and moisture content of sawn lumber Reviewed

Hikaru Kobori, Tetsuya Inagaki, Takaaki Fujimoto, Tsutomu Okura, Satoru Tsuchikawa

HOLZFORSCHUNG Vol. 69 ( 3 ) page： 329-338 2015.4

Combined effects of UV light and elevated temperatures on wood discolouration Reviewed

Laszlo Tolvaj, Satoru Tsuchikawa, Tetsuya Inagaki, Denes Varga

Vol. 49 ( 6 ) page： 1225-1237 2015

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Papers - INAGAKI Tetsuya