WOOD RESEARCH Volume 61, Number 5, 2016
Andrea Nasswettrová, Soňa Křivánková, Pavel Šmíra, Jan Štěpánek, Martin Friedl, and Jan Trubák

Acoustic detection of wood-destroying insects during

This thesis deals with experimental verification of hot-air preservation efficiency on wooden members of structures against larvae of wood-destroying insects, particularly against larvae of longhorn beetle Hylotrupes bajulus L. The verification of hot-air efficiency on mortality of larvae was performed within the process of hot-air preservation of a room of a building in Čeladná, Czech Republic. Parameters of hot-air preservation met the specifications of standards according to which the process is controlled. The efficiency was monitored by means of the Acoustic Pack acoustic system which recorded acoustic emissions of larvae emitted during wood ingestion. To verify the acoustic system and hot-air preservation, the samples were subject to destruction analysis after the preservation. Using a Keyence VHX-S550E digital microscope, the analysis of changes in the structure of larvae before and after the process of preservation was performed. The results showed that designed parameters of hot-air preservation lead to the mortality of larvae.

WOOD RESEARCH Volume 62, Number 1, 2017
Andrea Nasswettrová, Soňa Křivánková, and Pavel Šmíra

Comparison of the results of dendrochronological measuring based on different images of a historical wood sample of silver fir (Abies alba) from the Czech republic

The aim of the paper was to compare the results of different methods of measuring the tree rings curve performed using different images of a reference sample made from a historical wooden con-struction of silver fir wood. The tree-ring curves were measured using two measurement methods: firstly manually on the traversing table using a stereo microscope with TSAPWin dendrochronolog-ical software and secondly in the LignoVision software (LV) from uploaded image files (scans, modified monographic scans and X-ray scans). Automatic image analysis was also tested in this software. Results showed that the tree-ring curves based on manual determination of printed-out photographs and scans using a stereo microscope on a traversing table and on manual determination of identical digital images in LignoVision matched to a large extent the data obtained by measuring the physical sample. The results were worse when tree-ring curves were measured from an X-ray scan, both using stereo microscope on a printed image, and using LignoVision. The automatic anal-ysis of the LignoVision software showed a high error rate. Finally, the results of measurements of individual image types and the possibilities of practical use of individual image records of dendro-chronological samples are discussed.

WOOD RESEARCH Volume 63, Number 1, 2018
Soňa Křivánková, Andrea Nasswettrová, and Pavel Šmíra

Comparison of image quality between a medical and an industrial ct scanner for use in non-destructive testing of tree-ring widths in an oak (Quercus robur) historical sculpture of Madonna

The aim of this paper was to compare the tree-ring width measurement results obtained using standard medical CT scanner Light Speed VCT 64 with the results obtained from industrial CT scanner GE phoenix v|tome|x 240 during dendrochronological dating of a historical wooden sculpture. The examined object was a polychrome wooden sculpture of Madonna, which was of historical value – that is why equipment enabling non-destructive measurement of tree-ring width for dendrochronological dating had to be used. The sculpture was made of ring porous English oak wood (Quercus robur), which is very easy to measure. There are also standard chronologies available for this material for the area of the Czech Republic to be used for absolute dendrochronological dating. During the first stage of the research, an available CT scanner designed for medical examination of human tissue was used; then the object was measured again using an industrial CT scanner where better results could be expected thanks to higher image resolution. This paper compares the quality of images from both scanners and the results of tree-ring width measurement from the output of the two CT scanners. The re-sults successfully document the possibility of obtaining images of sufficient quality to measure the grow ring widths of oak wood using computed tomography, proving that wooden objects can be subject to dendrochronological dating even if strict non-destructivity is required.