1,720,959 research outputs found
Study of the effect of protective on wood photo-degradation by colour measurements, FT-IR spectroscopy and hyperspectral imaging
No full textThe aim of this work is to investigate the effect of protective materials on poplar (Populus spp.) wood modifications as consequence of artificial photo-degradation in controlled environment. Starting from previous results [1-4], this study tried to understand what happens to wood surface under the protective layer.
As protective materials, shellac, beeswax and Linfoil® were tested to compare traditional and novel products generally used for wood. The samples covered by these protective layers were artificially aged in Solar Box for 1064 hours. As comparison, also uncovered samples were tested.
At chosen times, the samples were investigated by reflectance spectrophotometry, Fourier transform infrared spectroscopy and hyperspectral imaging in order to study the colour and chemical modification occurred to wood both covered and uncovered with the protective products. The obtained data were statistically elaborated in order to verify their significance.
Colour measurements highlighted that the protective materials reduced the wood colour changes in respect to un-protected samples. FT-IR spectroscopy demonstrated that photo-degradation caused mainly lignin decomposition with the production of new chromophore groups on wood surface. Also in this case un-covered wood underwent greater modifications in respect to protected one. Hyperspectral imaging in the SWIR range (1000-2500 nm), coupled with chemometric methods, clearly showed the variation between the spectral behavior of poplar wood for ageing time 0 and 1064 hours, with different protective layers.
It is interesting to note that protective materials have a partial effect on wood photo-degradation by little reducing the changes.
Such results can contribute to evaluate the effect of protective materials on wood during sun exposure
Hyperspectral imaging as a technique for investigating the effect of consolidating materials on wood
No full textThe focus of this study was to investigate the potential of hyperspectral imaging (HSI) in the monitoring
of commercial consolidant products applied on wood samples. Poplar (Populus spp.) and walnut (Juglans
Regia L.) were chosen for the consolidant application. Both traditional and innovative products were selected,
based on acrylic, epoxy, and aliphatic compounds. Wood samples were stressed by freeze/thaw cycles in order
to cause material degradation without the loss of wood components. Then the consolidant was applied under
vacuum. The samples were finally artificially aged for 168 h in a solar box chamber. The samples were acquired
in the short wave infrared (1000 to 2500 nm) range by SISUChema XLTMdevice (Specim, Finland) after 168 h of
irradiation. As comparison, color measurement was also used as an economic, simple, and noninvasive technique
to evaluate the deterioration and consolidation effects on wood. All data were then processed adopting a
chemometric approach finalized to define correlation models, HSI based, between consolidating materials, wood
species, and short-time aging effects
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Damages to soil and tree species by cable-skidding in Caspian forests of Iran
Full text linkAim of study: The main aims of this study were to determine of damage level to residual stand and soil disturbance from mechanized selection logging.
Area of study: Mixed beech stands in Caspian forests, northern Iran.
Material and methods: Point-transect and systematic plot sampling were used for assessing damages to soil and trees, respectively.
Main results: 89% of forest soil area was undisturbed or shallow disturbed, and 5.2% was deep disturbed. Soil bulk density of top 10 cm in the winching corridors, ruts and skid trails were increased 10.7%, 20.6% and 32.1% respectively than controlled area. Frequency of damages to regeneration and trees were 12% and 11.2%. The frequency of damages to regeneration was increased with increasing of their heights, but frequency of damages to trees was decreased with increasing of their diameter. The most type of damages was bole wounds in sizes of 100 to 200 cm2 within 1 m from the ground level, and deep wounds. The frequency of damages was different in tree species (p = 0.001). The mean size of bole wounds was 174 cm2, and the mean height of bole wounds was 70 cm from ground level. The intensity of wounds on trees bole were decreased with increasing of their heights from ground level (p = 0.02), while their sizes were increased (p = 0.001).
Research highlights: Winching of logs was the main cause of damages to soil and residual stand. The detailed planning strategy will reduce damage to level which is acceptable and predictable
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Modeling color and chemical changes on normal and red heart beech wood by reflectance spectrophotometry, Fourier Transform Infrared spectroscopy and hyperspectral imaging
No full textThe use of beech is a key topic for Europe as it is one of the most important and abundant broad-leaf species. Physical, mechanical and esthetical features influence both the value and the usage of this wood in each commercial product. In this sense, the comprehension of the surface color modifications induced by solar irradiation is of crucial importance to define the commercial value of the beech wood.
Starting from these general remarks, the aim of this work is to study the surface modifications on beech wood with and without red heartwood by different spectroscopic techniques and to obtain a modeling of the changes validated by rigorous statistical and chemometric methods together with principal component analysis.
The artificial photo-irradiation of the wood samples was performed in a Solar Box. Reflectance spectrophotometry, Fourier Transform Infrared spectroscopy and hyperspectral imaging were used to assess artificial sunlight influence. The experimental data were statistically treated in order to evaluate their significance.
Color monitoring allowed to find that the chromatic coordinates (L*a*b*) in normal wood and in red heartwood tended to similar values after 504 h of photo-irradiation.
Fourier Transform Infrared spectroscopy showed the rate of photo-degradation of wood surface due to lignin oxidation and the statistical analysis allowed to demonstrate that red heart and normal wood have the same behavior.
Concerning hyperspectral imaging (HSI), the detected spectral features were correlated to color changes in the Visible-Near Infrared (VIS-NIR) range (400-1000 nm) and to the variations of cellulose and lignin during accelerated aging in the Short-Wave Infrared (SWIR) range (1000-2500 nm).
The most important result is that a correlation, validated by statistical analysis, of the color changes may be derived with the photo-degradation of wood components obtained by spectral analysis. This fact suggests the possibility to choose the reflectance spectrophotometry as a non-invasive, simple standard method to monitor the state of preservation of the wood surfaces
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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