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The distinct properties and affordances of paper provide benefits that enabled paper to maintain an important role in the digital age. This is so much so, that some pen–paper interaction has been imitated in the digital world with touchscreens and stylus pens. Because digital medium also provides several advantages not available to physical paper, there is a clear benefit to merge the two mediums. Despite the plethora of concepts, prototypes and systems to digitise handwritten information on paper, these systems require specially prepared paper, complex setups and software, which can be used solely in combination with paper, and, most importantly, do not support the concurrent precise interaction with both mediums (paper and touchscreen) using one pen only. In this paper, we present the design, fabrication and evaluation of the Hybrid Stylus. The Hybrid Stylus is assembled with the infinity pencil tip (nib) made of graphite and a specially designed shielded tip holder that is attached to an active stylus. The stylus can be used for writing on a physical paper, while it still maintains all the features needed for tablet interaction. Moreover, the stylus also allows simultaneous digitisation of handwritten information on the paper when the paper is placed on the tablet screen. In order to evaluate the concept, we also add a user-friendly manual alignment of paper position on the underlying tablet computer The evaluation demonstrates that the system achieves almost perfect digitisation of strokes (98.6% of strokes were correctly registered with only 1.2% of ghost strokes) whilst maintaining excellent user experience of writing with a pencil on the paper. [ABSTRACT FROM AUTHOR]

Portable spectroscopic instruments are an interesting alternative for in-field and on-line measurements. However, the practical implementation of visible-near infrared (VIS-NIR) portable sensors in the forest sector is challenging due to operation in harsh environmental conditions and natural variability of wood itself. The objective of this work was to use spectroscopic methods as an alternative to visual grading of wood quality. Three portable spectrometers covering visible and near infrared range were used for the detection of selected naturally occurring wood defects, such as knots, decay, resin pockets and reaction wood. Measurements were performed on wooden discs collected during the harvesting process, without any conditioning or sample preparation. Two prototype instruments were developed by integrating commercially available micro-electro-mechanical systems with for-purpose selected lenses and light source. The prototype modules of spectrometers were driven by an Arduino controller. Data were transferred to the PC by USB serial port. Performance of all tested instruments was confronted by two discriminant methods. The best performing was the microNIR instrument, even though the performance of custom prototypes was also satisfactory. This work was an essential part of practical implementation of VIS-NIR spectroscopy for automatic grading of logs directly in the forest. Prototype low-cost spectrometers described here formed the basis for development of a prototype hyperspectral imaging solution tested during harvesting of trees within the frame of a practical demonstration in mountain forests. [ABSTRACT FROM AUTHOR]

Highlights • Historical timber-framed wall system was investigated under cyclic loads. • Damage progression and post-elastic behaviour was analysed by image-based tracking method. • Plastic deformations and local damage occurred in some joints. • Observations are important for the design of strengthening or repair interventions. Abstract The scope of this paper is to analyse local phenomena associated with the damage progression and post-elastic behaviour of a historical timber-framed wall system under cyclic loads. It was assessed on series of points identified on the wall by processing time-resolved sequences of images. Dedicated methodology of image-based tracking method was developed to analyse local phenomena, such as relative displacements, rotations and deformations in the wall. It was possible to deduce that plastic deformations and local damage occurred in some joints. This type of observation is important for the design of rigorous strengthening or repair interventions. [ABSTRACT FROM AUTHOR]

Thermal modification processes significant affect the chemical configuration of the wood matrix improving moisture-related properties and material durability. In addition, the distinctive dark tones of heat-treated timber increase the economic value of several light-colored species. However, these treatments alter the substrates and it could influence the performance of coating products, necessary to maintain the surface features in certain end-use sectors. Ash wood ( Fraxinus excelsior L.) samples industrially treated at 192 °C, 202 °C and 212 °C were coated with decorative waterborne polyurethane and industrial UV-hardened coatings. Afterwards, the samples were subjected to accelerated weathering. The resulting surface topography was assessed with a 3D scanner and a profilometer, revealing slight changes in the texture. Color changes were quantified with hyperspectral imaging by generating surface color maps in CIE Lab coordinates. The results indicate acceptable photostability of thermally modified wood. Changes in wettability, surface free energy, work of adhesion and cohesion were determined by contact angle. Higher hydrophilicity after weathering was observed, but with an acceptable overall performance. At the same time, polar and dispersive shares were redistributed depending on the applied coating. It was demonstrated that heat-treated wood could be an optimal substrate for innovative wood-based products, suitable for use outdoor and exposure to changing weather conditions. [ABSTRACT FROM AUTHOR]

The influence of the thermal modification process on wood machinability was investigated with four minor species of low economic importance. A set of representative experimental samples was machined to the form of disks with sharp and dull tools. The resulting surface quality was visually evaluated by a team of experts according to the American standard procedure ASTM D-1666-87. The objective quantification of the surface quality was also done by means of a three dimensions (3D) surface scanner for the whole range of grain orientations. Visual assessment and 3D surface analysis showed a good agreement in terms of conclusions. The best quality of the wood surface was obtained when machining thermally modified samples. The positive effect of the material modification was apparent when cutting deodar cedar, black pine and black poplar in unfavorable conditions (i.e., against the grain). The difference was much smaller for an easy-machinability specie such as Italian alder. The use of dull tools resulted in the worst surface quality. Thermal modification has shown a very positive effect when machining with dull tools, leading to a relevant increment of the final surface smoothness. [ABSTRACT FROM AUTHOR]

Timber structures can undergo alteration during their service life, which can be caused by mechanical, environmental or biological agents (bacteria, fungi and insects), because of the biological nature of the material. On site characterization of timber members is a very challenging task, especially assuming that both, the structure itself and material used for construction have to be evaluated. Current assessment procedures are limited to visual inspection, occasionally supported by a few instrumental analyses (such as wood moisture content measurement and drilling resistance tests). However, a clear tendency for the application of various non-destructive techniques is observed nowadays. The paper presents an overview on the current applications of infrared spectroscopy for the characterization of various alteration phenomena in wooden artefacts. A literature review is complemented by a series of results, reported from experimental campaigns carried out by the authors. The aim of the paper is to demonstrate the applicability of the proposed method for the analysis of different degradation processes occurring in timber members, with a special attention on wood aging, weathering, biotic decay by fungi and waterlogging. Examples of spectra evaluation as well as limitation of proposed methods are presented. Case studies including classification of decay type, analysis of the weathering dynamic and characterization of waterlogged wooden samples are briefly illustrated. Practical application of spectroscopy within timber structure assessment is considered as a very important supplement to the typical information collected during ordinary tests. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The use of wood-based connectors as a possible substitute of metal fasteners, for specific applications, in modestly loaded and moderately dense timber components, in new timber assemblies as well as for restoration works, is discussed. The densification technique has been used to obtain a wood-based material with higher mechanical performance with respect to the natural wood. A dedicated research has been carried out to monitor the compression behaviour of the wooden nails. The progress of pushing force during insertion of the wooden nails into wood samples was analysed and served for insertion process control. 600 compression tests were carried out to evaluate the mechanical behaviour of densified wooden nails, obtained from four different hardwood species and with different densification ratios. Beech, densified at 0° ring angle, 60% densification ratio, was selected for the further experimental campaign on the joints. Ten push-out tests have been performed on timber-to-timber joints. Results in terms of rigidity, resistance and post-elastic behaviour are discussed. The observed variability (slip modulus CoV = 26.7%, maximum load CoV = 23.7%) is mainly dependent on the occurrence of geometric flaws during nail insertion. Ductility exhibited by a group of joints was given by nail embedding into the wood before failure as well as by the bending resistance of the nail. The choice of an optimized technology for wood densification and for nail insertion is considered as a key factor for the optimal employment of the novel connectors. [ABSTRACT FROM AUTHOR]

On site characterization of wood members is a very challenging task, after consideration of all the variables affecting the material used for the construction and the complexity of the structure itself. Current procedures are limited to few characterizations; in general based on visual inspection supported by the localized drilling resistance analysis and moisture content estimation. The goal of this work was to highlight the potential of the infrared spectroscopy as a tool capable of providing complementary information for the expert inspector assessing the timber structures. The paper presents several examples of successful application of mid and near infrared spectroscopy as used for prediction of physical and mechanical properties of wood. Requirements for implementation of mid and/or near infrared spectroscopy in routine assessment protocols are also provided. [ABSTRACT FROM AUTHOR]

The manuscript presents the application of NDT imaging techniques as complementary tools to be used during visual inspection. NDT imaging can be used to map inhomogeneity and to identify the areas at the highest risk for damage in timber structures. The paper highlights the potential of imaging techniques accepted and practiced for the assessment of timber structures. Multi-sensor approaches are presented and recommended for multi-scale, multi-resolution correlated information, which allow the non-destructive, reliable and fast assessment of damage and risk level in the existing timber structures. [ABSTRACT FROM AUTHOR]

The proper timber structure assessment is of great importance to assure safe service of buildings as well as to preserve cultural heritage objects for future generations. However, due to peculiar anatomic structure of wood, anisotropy and heterogeneity, its characterization is a problematic task. Several methods are used nowadays for improving existing structure assessment routines, including also continuous monitoring of the structure performance. Current trend for using multiple sensors simultaneously is more favorable than a single sensor approach due to superior representation of the real-world cases. Moreover, the availability of novel statistical tools to handle many variables concurrently is another motivation for rapid changes within the field of measurement technology. It is important, therefore, to assure proper pre-processing of the signals from sensors, appropriate data fusion and optimal data analysis. The integrated use of non-destructive testing methodologies and data handling techniques to assess, monitor and predict properties of wood within structures and buildings is briefly described in this work. Examples for successful applications of the different data analysis techniques on the assessment and monitoring of civil engineering constitutions are reported. Multi-sensor approach may be a very attractive alternative to the conventional assessment and can provide supplementary data to be considered when inspector decision is made. It is assumed that, after additional developments, such methodologies can serve as assisting tools for non-destructive assessment of the wooden structures, service life prediction of structural elements and to support selection of optimal conservation process. [ABSTRACT FROM AUTHOR]

Chemical and physical characteristics of wood from six European populations of Picea abies were investigated taking into consideration their genetic differentiation determined by four microsatellites markers. The growth conditions of investigated spruce trees differed significantly. As a consequence, several adaptations were observed in samples from varying environments. The adaptation mechanisms include a variation to the annual rings morphology as well as the physical properties of the wood. It was proved that some properties, such as wood density or latewood ratio, are strictly correlated to the environmental variables. Results show that trees from geographically distinct populations present some diversity in the genotypes. It was also noticed that some trees did not share their genetic profile with other plants from the same location due to high intrapopulation variability. Samples from Finland possessed the lowest level of internal differentiation, while samples from northern Poland presented the lowest allele richness and were most divergent from the others. It was not possible to correlate any wood properties (chemical or physical) to genetic features of the population due to high intrapopulation diversity. [ABSTRACT FROM AUTHOR]

The thermo-vacuum process is an alternative technology for thermal modification of wood where reduction of oxygen concentration inside the reactor, necessary to avoid wood combustion, is obtained by applying vacuum. The goal of this research was to exploit the potential of near infrared spectroscopy for the quality control of TMW (prediction of mass loss and equilibrium moisture content in both softwoods and hardwoods), exposed to the thermal treatment in vacuum conditions. Applied chemometric techniques confirm great potentiality of the near infrared spectroscopy. Important parameters characterizing quality of TMW in vacuum conditions were predicted with high accuracy. Prediction errors of chemometric models based on near infrared spectra were relatively small; 0.9% and 0.36% in case of mass loss and equilibrium moisture content respectively. Such methodology might be helpful for development of on-line process control and for further optimization of the thermal treatment procedure at industrial scale. [ABSTRACT FROM AUTHOR]

Wood is one of the oldest building materials and, thanks to its favorable mechanical and technological properties, one of the most versatile. Due to its biological nature, wooden artefacts can undergo some alteration during their service life that can be caused by mechanical, environmental or biological agents. Waterlogged and buried wood elements, present in wetlands and aquatic environments, are subject to modifications at the chemical and anatomical level, which also affect physical and related mechanical properties of the material. The possibility to predict long-term performance and the rate of modification of mechanical/physical properties of the wood material in specific environmental conditions is crucial for proper design and optimal maintenance of submerged load-bearing timber structures. Therefore, prediction models to estimate selected material properties were developed within this study. For this purpose Fourier Transform near-infrared (FT-NIR) spectroscopy and multivariate analysis based on partial least-squares (PLS) were used. The models proved to be effective to predict selected dynamic and physical parameters of waterlogged samples. However, in order to include the effect of water saturation in the material on site further research is indispensable. The possible detrimental effect on wood mechanical properties of waterlogging in differing environmental conditions is also discussed in this paper. Dynamic tests were performed on samples of two species, Quercus robur L. and Pinus sylvestris L., after 8 years of deposition in two differing sites. Additionally, the results obtained from fresh and archaeological samples were compared. No significant effects have been observed due to the depositional environment after short-term waterlogging. A more remarkable difference in the rate of the modification of dynamic and physical (density) properties can be attributed to differing natural features of the tested wooden species. It may be concluded that, in order to ensure a longer service-life of waterlogged timber structures, original wooden material should be properly selected, with regard to species, growth conditions, and log characteristics. [ABSTRACT FROM AUTHOR]

[Display omitted] • Feasibility of a portable NIR sensor for determination of wood quality aspects was demonstrated. • The best performance was obtained for prediction of moisture, density and mechanical properties. • NIR was capable of classifying defects, trace raw resources and predicting delamination. • Suggestions for industrial integration in glue-laminated timber production were provided. The feasibility of a portable NIR sensor for off-line determination of diverse wood quality aspects relevant in the production of glue-laminated timber was demonstrated. The best performance was noticed for assessing wood moisture content, with a lower capacity to estimate wood density and mechanical properties. NIR spectroscopy was modestly capable of predicting surface roughness. However, the traceability of the raw resources and the automatic classification of diverse wood defects were successfully demonstrated. The developed chemometric model could predict the total delamination and detailed delamination length. Finally, recommendations regarding further system development were provided with the aim of implementation and integration of the NIR measurement into glue-laminated timber production plants. [ABSTRACT FROM AUTHOR]

Understanding mechanisms of materials deterioration during service life is fundamental for their confident use in the building sector. This work presents analysis of time series of data related to wood weathering acquired at three scales (molecular, microscopic, macroscopic) with different sensors. By using several complementary techniques, the material description is precise and complete; however, the data provided by multiple equipment are often not directly comparable due to different resolution, sensitivity and/or data format. This paper presents an alternative approach for multi-sensor data fusion and modelling of the deterioration processes by means of PARAFAC model. Time series data generated within this research were arranged in a data cube of dimensions samples × sensors × measuring time. The original protocol for data fusion as well as novel meta parameters, such as cumulative nested biplot, was proposed and tested. It was possible to successfully differentiate weathering trends of diverse materials on the basis of the NIR spectra and selected surface appearance indicators. A unique advantage for such visualization of the PARAFAC model output is the possibility of straightforward comparison of the degradation kinetics and deterioration trends simultaneously for all tested materials. Image 1 • Multi-sensor data fusion facilitates understanding the weathering processes for diverse woods. • Multiway analysis allows capturing at best time trend. • Nested biplots are useful for combination of model loading in different modes. • A single model explains effect of wood modification, time and deterioration. [ABSTRACT FROM AUTHOR]

Heterogeneity of kraft lignin is one of the main limitations for the development of high-performance applications. Therefore, refining lignin using organic solvents is a promising strategy to obtain homogenous fractions with controlled quality in terms of structure and properties. In this work, one-step refining processes for hardwood kraft lignin using nine organic solvents of different chemical nature and polarity were carried out with the aim of investigating and understanding the effect of the type of organic solvent on the quality of resulting fractions. Structural features of both soluble and insoluble lignin fractions were assessed by GPC, Py-GC-MS, and FTIR linked to PCA analysis. Moreover, functional properties such as physical appearance, hygroscopicity, antioxidant capacity, and thermal properties were evaluated. The results evidenced the relationship between the nature and polarity of the solvents and the properties of the obtained soluble and insoluble fractions. [ABSTRACT FROM AUTHOR]

The modern wood converting processes consists of several stages and material drying belongs to the most influencing future performances of products. The procedure of drying wood is usually realized between subsequent sawing operations, affecting significantly cutting conditions and general properties of material. An alternative methodology for determination of mechanical properties (fracture toughness and shear yield stress) based on cutting process analysis is presented here. Two wood species (pine and beech) representing soft and hard woods were investigated with respect to four diverse drying methods used in industry. Fracture toughness and shear yield stress were determined directly from the cutting power signal that was recorded while frame sawing. An original procedure for compensation of the wood density variation is proposed to generalize mechanical properties of wood and allow direct comparison between species and drying methods. Noticeable differences of fracture toughness and shear yield stress values were found among all drying techniques and for both species, but only for beech wood the differences were statistically significant. These observations provide a new highlight on the understanding of the effect of thermo-hydro modification of wood on mechanical performance of structures. It can be also highly useful to optimize woodworking machines by properly adjusting cutting power requirements. [ABSTRACT FROM AUTHOR]

The cutting force is an energetic effect of splitting material, and might be considered from a point of view of modern fracture mechanics. Forecasting of the shear plane angle in cutting broaden possibilities for modelling of the cutting process even for thin uncut chips. Such mathematical model has been developed here for description of the orthotropic materials’ cutting on the base of fracture theory, and includes work of separation (fracture toughness) in addition to the material plasticity and friction. The original methodology of simultaneous determination of the fracture toughness and the shear yield strength on the basis of wood cutting forces (or cutting power) is also presented in this paper. The set of data necessary for computation can be easily obtained while cutting wood with common rotating tools, such as a circular saw or a router bit. The results generated include both fracture toughness and shear yield stresses in the shear plane, separately for two anatomical directions of wood. The simplicity and reliability of this method provides wide range of practical applications. [ABSTRACT FROM AUTHOR]

The floor in a building is an integral part of the interior and is usually considered as a very valuable component of decoration. The flooring style, construction, manufacturing technologies, finishing and maintenance reflects local traditions, available resources and craftsmanship. Traditional techniques of parquet surface finishing were used in manor houses of South-Eastern Poland until the 1st half of the 20th century. Unfortunately, the major part of historical wooden parquets was irreversibly destroyed due to the introduction of collective property and the expropriation of manor houses after World War II. It is necessary to develop the knowledge related to the chemical, physical and mechanical properties of antique floor heritage, for its proper conservation. Near infrared spectroscopy was applied here for rapid and non-destructive recognition of natural finishes traditionally applied for the protection of the wooden floors. The system was capable to correctly identify the reference finishes applied on contemporary wood samples. However, analyses of antiques floors were more problematic. The set of samples of original antique decorative wooden flooring was collected from manor houses in Tarnowiec and Falejówka. Both houses contained well preserved wooden flooring that had not been subject to restoration in the past. The method shows great potential, even if in some cases an ambiguous classification was obtained. The reasons included natural deteriorations of floors during service life. Originally used substances might change their chemical composition during lifetime as a result of aging, weathering, usage and external contaminations. Given that, it was concluded that the results of spectroscopic evaluations might provide valuable assistance to conservators and facilitate decisions on the proper object maintenance. [ABSTRACT FROM AUTHOR]

The goal of this work was to develop Fourier-transform-near-infrared-spectroscopy-based methodology for monitoring kinetics and estimating the biodegradation rate of coniferous pulp paper. Two experiments with paper-degrading fungi were tested: one with Chaetomium globosum alone and the other with a mixture of Aspergillus niger , Trichoderma viride , and Penicillium funiculosum . Paper sheets made of fibers with the addition of 0, 2, 3, or 5% of cationic starch and resinous adhesive were used as test samples. In order to quantify the resistance of the paper to biodegradation, tests of breaking length and evaluation of the degree of fungal infestation were performed during infestation. It was found that addition of cationic starch and resin adhesives improved mechanical properties of paper; however, it also increased susceptibility to fungal colonization. Degradation of paper colonized by C. globosum was more advanced and exhibited more rapid kinetics. Spectral analysis revealed that spectra were most varying in bands 4283, 4400, 4742, and 4808 cm −1 , which correspond to –CH, and –OH functional groups of cellulose and hemicelluloses. Differences in spectra were in good agreement with the reference methods; therefore this technique has potential for monitoring the paper biodegradation process and predicting changes in the paper's mechanical properties. [ABSTRACT FROM AUTHOR]

The shrinking global forest area limits the supply of industrially usable raw resources. This, in combination with the ever-increasing consumption of timber due to population growth can lead to the lack of a positive balance between the annual volumetric growth and consumption of wood. An important innovation toward increasing environmental and economic sustainability of timber production is to reduce the volume of wood residues by minimizing the sawing kerf. It results in higher material yield but may impact the dimensional accuracy of derived products. Therefore, the cutting tool geometry as well as the sawing process as a whole must be carefully optimized to assure optimal use of resources. The goal of this study is to better understand the causes of machining errors that occur when sawing wood with saws of varying thickness of kerf, with a special focus on re-sawing thin lamellae performed on the gang saw. Numerical simulations were tested against experimental results, considering influence of diverse components of cutting forces, in addition to the initial and operating stiffness coefficients of the saw blade. It has been demonstrated that asymmetric loads from the cutting process for the scraper saw blade can cause sawing inaccuracies. The simulation methodology developed in this research can be straightforwardly extended towards determination of optimal geometry of other cutting tools, particularly with the reduced sawing kerf. This may lead to more sustainable use of natural resources as well as an increase in economic gain for the wood processing industries. [ABSTRACT FROM AUTHOR]

Refining of industrial lignin to produce homogeneous fractions is essential for high-value applications. However, the understanding of key interactions between a variety of solvents with lignin polymer is still uncertain. In this work, single-step fractionation of industrial hardwood kraft lignin (HKL) using organic solvents of different polarities – ethanol, acetone, diethyl ether and hexane – was investigated by combining an experimental and theoretical approach. Experimental results revealed that higher polarity solvents (ethanol and acetone) exhibited higher solubility yield compared to moderate and low polarity solvents. The chemical differences between lignin fractions were proven by pyrolysis gas chromatography mass spectrometry and near infrared spectroscopy. Density functional theory (DFT) results indicated that ethanol presented higher interaction energy followed by acetone, diethyl ether and hexane, which was consistent with experimental findings. Hydrogen bond and non-covalent interaction results from DFT demonstrated that the predominant interaction was found for high polarity of ethanol over other solvents and γ-OH in the lignin model is the key site. Unlabelled Image • Single-step fractionation was carried out for hardwood kraft lignin using 4 solvents. • Higher polarity solvents exhibited higher solubility yield. • Fractionation with diethyl ether leaded to homogeneous low molecular weight fraction. • Quantum chemical calculations showed that ethanol exhibited higher interaction energy. • γ-OH in the lignin model is the key site for strong hydrogen bonding. [ABSTRACT FROM AUTHOR]

13 C nuclear magnetic resonance and mid-infrared spectroscopies were used for characterizing changes in the chemical structure of wood polymers (cellulose, hemicellulose and lignin) in relation to the tree growth location. Samples of three provenances in Europe (Finland, Poland and Italy) were selected for studies. The requirement was to use untreated solid wood samples to minimize any manipulation to the nanostructure of native wood. The results confirm that the chemical and physical properties of samples belonging to the same wood species ( Picea abies Karst.) differ due to the origin. Both FT-IR and dynamic NMR spectroscopies were able to correctly discriminate samples originating from three different provenances in Europe. Such methods might be very useful for both, research and understanding of wood microstructure and its variability due to the growth conditions. [ABSTRACT FROM AUTHOR]

Several properties of wood including the cutting power requirements can be correlated to wood density. Therefore, according to the literature, the cutting power requirements (and/or cutting forces) could be computed as a function of the wood specific gravity. This research shows that such an approach, based solely on specific gravity, may be considered a rather rough and imperfect estimate of cutting power. Samples of Scots pine (Pinus sylvestris L.) wood from different provinces in Poland with varying densities were machined on a sash gang saw. The average cutting force versus average wood density (estimated with the standard gravimetric method) was calculated, and the local cutting forces correlated to the local wood density. The average values of the cutting forces measured at selected points along the sample's length were calculated by linear regression to the X-ray absorbance (density) estimated by means of X-ray radiography. [ABSTRACT FROM AUTHOR]