Laser-induced breakdown spectroscopy for the classification of wood materials using machine learning methods combined with feature selection

In this paper,we explore whether a feature selection method can improve model performance by using some classical machine learning models,artificial neural network,k-nearest neighbor,partial least squares-discrimination analysis,random forest,and support vector machine(SVM),combined with the feature selection methods,distance correlation coefficient(DCC),important weight of linear discriminant analysis(IW-LDA),and Relief-F algorithms,to discriminate eight species of wood(African rosewood,Brazilian bubinga,elm,larch,Myanmar padauk,Pterocarpus erinaceus,poplar,and sycamore)based on the laser-induced breakdown spectroscopy(LIBS)technique.The spectral data are normalized by the maximum of line intensity and principal component analysis is applied to the exploratory data analysis.The feature spectral lines are selected out based on the important weight assessed by DCC,IW-LDA,and Relief-F.All models are built by using the different number of feature lines(sorted by their important weight)as input.The relationship between the number of feature lines and the correct classification rate(CCR)of the model is analyzed.The CCRs of all models are improved by using a suitable feature selection.The highest CCR achieves(98.55...0.39)%when the SVM model is established from 86 feature lines selected by the IW-LDA method.The result demonstrates that a suitable feature selection method can improve model recognition ability and reduce modeling time in the application of wood materials classification using LIBS.

A THEORY OF DETERMINING MASS TRANSFERPARAMETERS FOR WOOD PARTICLE MATERIALS

The transient mass transter processes in the natural drying of wood particle materials were experimental;y studied A new theory tio determme the mass transfer parameters in the Materials was developed in terms of gradient transformation method(GTM).By making use of GTM.Thewater vapour diffusion coefficient and the surtaee emission coefficent of wood chip were expermentally determined both in air phase and in solid phase.It Was found that the internal resistance to water vapour diffusion in the air phase of wood partiele aggregates is around ten to the third power as large as that in common air The drag coefficient was given to quantify the effect The phenomenon of undersurface diffusion in wood partiele bed was quantitatively modelled.The dimensionless Fourier snumber and the Biot's number for mass transfer were theoretically derived.The study showed that Biot's number for the problem investigated was the ratio of the characteristie length of wood partiele bed to the penetrating depth of the undersurface.An analytical solution of the nonlinear goveming equation for water transport process in the aggregates of wood chip was obtained by introducing the variable coefficients measured in the study into the governing equation.The comparison between the analytical solution and the observed moisture content of wood chip showed that the deviation was less than ±7%.The thermophysieal properties of wood particle materials are little known at present.The knowledge provided in the paper will be and in the handling.researeh or engineering application of wood chip.wood shavingsete.

Physical Properties and Heat Transfer of Tectona grandis L.f. Wood

Tectona grandis L.f. （teak） is native to the Indian subcontinent and southeast Asia, and today is grown in almost every tropical region, for the physical and mechanical properties of its wood. Also, important qualitative aspects render it one of the most expensive wood species in the world. This work presents a study about the physical properties and heat transfer of T. grandis wood from plantations in C.ceres, Mato Grosso, Brazil. Six trees planted at three different intervals were used--two from each planting density--selected at random and with good phytosanitary characteristics, as well as having representative diameters and heights. The following properties were determined： basic and apparent densities, volume contraction, heat transfer and fiber saturation point. The basic and apparent mean general density of the samples was 0.48 g/cm3 and 0.55 g/cm3, respectively. The mean volume contraction of the teak wood was 8.57%. With decreased levels of wood humidity, loss of volume and planting effects were not significant at 5% probability. Mean heat transfer was 7.3 h/cm and the wood fiber saturation point was 17.25%, below the range found in literature, and there was no influence of the planting density on this property. According to the results, it was concluded that planting density significantly influenced the base density of the wood; the same effect does not occur for the other physical properties, and with respect to heat transfer, the wood was considered difficult to dry.

Investigation of Wooden Beam Behaviors Reinforced with Fiber Reinforced Polymers

Wood material can be demolished over time due to different environmental factors.Structural elements may need to be strengthened over time as a result of possible natural disasters or during use.Beams are elements under load in the direction perpendicular to their axes.Therefore,they are basically under the effect of bending.When the studies on the behavior of beams against bending test are examined,it is known that the bottom surface of the material generally breaks.For this reason,fiber reinforced polymers(FRP)materials have been used in recent years to reinforce beam members.It is a scientific fact that it is necessary to prefer FRPs for the solution of this problem,as well as their properties such as lightness,corrosion and flexibility,their application without disrupting the appearance of wood.In this study,it was aimed to investigate the effect of reinforcing wooden beams with fiber reinforced polymer materials with different properties on different bending behaviors such as load bearing capacity,ductility,modulus of elasticity.It was observed that the ductility and bearing capacity of wooden beams reinforced with fiber reinforced polymer materials increased significantly compared to non-reinforced beams.

In-Situ Chemosynthesis of ZnO Nanoparticles to Endow Wood with Antibacterial and UV-Resistance Properties

Hybrid wood materials have attracted considerable attention because they have combined advantages of both wood and inorganic compounds. This work investigated the microstructural morphology, thermal stability, ultraviolet（UV） stability, and antibacterial property of composites made from wood/ZnO hybrid materials through a facile in-situ chemosynthesis methods. The X-ray diffraction（XRD） and thermogravimetric analysis（TGA） results indicated that the synthesized ZnO particles had an average grain size of about 10.8 nm. The scanning electron microscopy（SEM） observations showed that ZnO nanoflowers self-assembled with nanosheets were presented in wood cell lumens and increased with increasing Zn^（2＋）concentrations. ZnO nanoparticles were also generated in the wood cell wall, which was confirmed by the results of energy-dispersive spectroscopy（EDS）. The TGA tests also indicated that the thermal stability of wood/ZnO hybrid materials was improved after the formation of ZnO inorganic particles. Finally, the results of antibacterial efficacy tests and UV resistance tests revealed that ZnO nanoparticles showed a promising future as antimicrobial agents against Escherichia coli（E.coli） and UV resistance agents for wood protection.

Marine mycoflora of south India with special emphasis on Lignicolous Marine Fungi

A study dealing with the marine fungi associated with decaying wood samples in the brackish water mangrove ecosystem and shoreline ecosystem was carried out in south India.A total of 19 marine fungi were isolated from the brackish water mangrove ecosystem.They included 13 Ascomycetes,one Basidiomycete and five Mitosporic fungi.In terms of percent frequency of occurrence,the most frequent species obtained from the brackishwater were the Lignincola longirostris(16.60%)and Savoryella lignicola(12.09%).Nine species were found frequently.Five species were occasionally encoun-tered.Aigialus mangrovei,Aniptodera mangrovei and Halosarpheia marina were the rare species recorded.The average number of isolates per wood sample was 1.53.A total of 27 marine fungi including 15 ascomycetes,one basidiomycete and ten mitosporic fungi were recorded from the shoreline ecosystem.In terms of percent frequency of occurrence,the most frequent species obtained from Kanyakumari were the Arenariomyces trifurcates(13.66%),Corollospora maritima(12.44%),and Cirrenalia pygmea(10.98%).Seven species were found frequently.Fourteen species were occasionally encountered.Three species were found to be rare in occurrence.The average number of isolates per wood sample was 1.21.