Background and Purpose: Nowadays selection of resonant raw material in forests is not practically carried out; there are no standards and samples for a tree with such timber, and, consequently, ...rational target use of this unique natural material is not achieved. Thereof a lot of valuable wood remains in forests or is harvested for utilizing as general-purpose forest products or firewood. The research is focused on the studies of interrelation of resonant properties of wood and its biomorphological attributes such as crown diameter and height, trunk habitus, branchless zone extension, etc.
Materials and Methods: Test material for the research of dendroacoustic parameters were cross-section radial cores 4.0 mm in diameter selected with an increment borer at breath height from 16 model trees after cutting them down. Simultaneously, diameters of trunks at relative heights (H) of 0.2Н, 0.5Н and 0.7Н, as well as branchless zone extension and tree crown parameters (its extension, first alive knot fastening height, etc.) were defined. Then, the interrelation was revealed between the biometric data of a tree trunk and average sound velocity measured across the trunk with UK-14П ultrasonic device at different relative heights.
Results: The results submitted in this paper present practical value and assess the accuracy of standing spruce wood resonant properties' forecasting based on its ‘wood study portrait’ parameters.
Conclusions: Acoustic properties of wood depend on biomorphology of a tree as well. The parameters of stem tapering, trunk volume and especially branchless zone extension and crown elevation have, to any extent, the greatest practical value for standing resonant raw material express diagnostics.
Background and Purpose: Studies of the physical-mechanical and acoustic properties of maple wood as a potential material for musical instruments manufacturing are extremely scarce. Related to this, ...dendro-acoustic studies of maples introduced by geographic origin are of great practical importance in order to create target plantations with predicted technical quality of wood.
Materials and Methods: Maples from abroad introduced by geographic origin into the Botanical Garden of the Volga State University of Technology of the Republic of Mari El of Russia were used for the research. For comparison, the Norway maple of local origin (Acer platanoides L.) was selected. The studies were carried out by the frequency-amplitude method for determining Young's dynamic modulus and the acoustic constant of sound emission according to the criterion of academician N. Andreyev.
Results: It was revealed that there are differences in the density and dendroacoustic indices of maple wood of local origin and maple trees introduced by geographic origin. Norway maple (Acer platanoides L.) turned out to possess the largest acoustic constant characterizing the resonant properties of wood. Introduced maple trees, plane-tree maple (Acer pseudoplatanus L.) and sugar maple (Acer saccharinum L.) are only slightly inferior in terms of this indicator.
Conclusions: The dendroacoustic properties of maple wood are generally much lower than that of resonant spruce. Consequently, the acoustic role of maple wood in the back plates of the violin and other string instruments is completely different than that of the top plate made from the resonant material of coniferous species. To reveal this difference in more detail, comparative studies and dendroacoustic identification of maple wood in blanks and musical instruments with different levels of acoustic characteristics are necessary.
The density of wood inside the stick varies greatly according to the diameter and height of the tree. The development of a non-destructive method of predicting an average density of wood in all ...specific breed stem-base density in parts of the tree is of great practical importance. For this purpose, the research was conducted to identify the patterns of wood density dynamics against the height and the diameter of birch trees growing in the conditions of the Middle Volga Region in Russia. Fourteen model birch trees (Betula pendula) were selected as research material on two plots in the plantations of the Scientific-Experimental Forest District of the Volga State University of Technology (VSUT) in the Republic of Mari El of Russia. From each felled model tree 50.0 mm cross-section discs were carved at a distance of 1.3 m from the root collar and at relative heights of 0.25H, 0.5H, and 0.75H. Prototypes in the form of 20x20x30 mm rectangular prisms (long side along the wood grain) were made from their north and south sides at a distance of 0.25R, 0.5R and 0.75R from the stem core along the NS diagonal. Density studies were conducted by measuring the density of the wood sample immersed in liquid against the buoyant force. It has been revealed that there are both differences and patterns of change in density in the longitudinal and cross-section directions of the trunk of a birch tree growing in the conditions of the Middle Volga Region in Russia. Based on the results obtained, a mathematical model of these laws has been formulated. Сlose relationship between the average density of the stick and its diameter at breast height (DBH) cross-section average density, i.e. ρtree=178.52+0.641ρdbh (r=0.922) has been revealed. By applying a well-known method of determining the density of cross-section radial core extracted from the wood by an age borer at this height, wood density of the birch trees growing in the Middle Volga Region can be calculated according to this equation.
Na početku trećeg tisućljeća znanstvenici i stručnjaci iz mnogih zemalja još pokušavaju odgonetnuti „tajnu Stradivarija” koristeći se naprednim tehnološkim rješenjima iz područja fi zike, matematike, ...kemije, biologije i drugih znanosti. Nepobitno je dokazano da je jedna od osnovnih tajni velikog majstora violina umijeće prepoznavanja odgovarajućeg materijala za izradu violina. Nažalost, Stradivari, Amati, Guarneri i drugi poznati predstavnici stare talijanske škole nisu ostavili nikakve naputke o izboru najboljeg materijala. No povijesna je činjenica da su oni drvo za gudačku ploču, glavni zvučni dio violine, odabirali kuckanjem po površini drva i dizajnirali instrument izabirući materijal prema zvučnosti, a obilježja dobre zvučnosti bila su poznata samo njima. Suvremenim znanstvenim rječnikom može se reći da su ti veliki majstori imali profesionalnu vještinu dekodiranja akustičnog odgovora izvornog materijala koji je unaprijed određivao kvalitetu proizvoda. Na temelju rezultata provedenih istraživanja ne može se tvrditi da su otkrivene sve tajne tog umijeća. Za tu bi svrhu bilo potrebno provesti obuhvatna i kompleksna istraživanja, i temeljna i primijenjena, integrirajući napore znanstvenika i stručnjaka s različitih područja: fi zičara, akustičara, drvnih tehnologa, šumara i, što je najvažnije, priznatih majstora iz područja proizvodnje odgovarajućih glazbenih instrumenata. U radu su prikazani prvi rezultati primjene tehnike mjerenja koja se temelji na pobuđivanju vibracija debla posebnim uređajem, uz snimanje, dekodiranje i analizu akustičnog odgovora te uzimanjem u obzir uvjeta rasta i općih morfoloških obilježja stabla, odnosno njegove veličine, oblika krošnje i dužine, oblika debla i sl. S obzirom na to da ne postoje analogna istraživanja, odnosno da još ne postoji „akustični standard” za zvučnost drva, dobiveni su podaci analizirani u skladu s općim odredbama akustične dijagnostike. Prihvaćeni osnovni akustični parametri jesu vibracije, potrošnja energije i spektralna svojstva zvuka, broj rezonantnih pikova, apsorpcija i prigušenje vibracija te raspodjela frekvencija spektra.
Strength of aged wood in old constructions Fedyukov, Vladimir; Chernov, Vasilii; Chernova, Maria
Istraživanja i projektovanja za privredu,
2020, Letnik:
18, Številka:
1
Journal Article
New method and technical solutions for nondestructive express diagnostics and targeted selection of spruce wood with unique dendro-acoustic properties aged in buildings are presented. Flow charts of ...equipment and ways of its application to identify resonant properties of wood in different parts of a building, including the walls made of round timbers, ceiling and floor boards are given. The proposed ways of wood quality diagnostics in buildings has its advantages over conventional methods.
The paper presents the results of dendroacoustic research and statistical and correlation analysis. The insights of heuristic identification based on biotechnology law are also given with the aim of ...defining the relationship of wood resonant properties with the form of seed scales of spruce growing in the Kama-Volga region of Russia. Key words: sonorous spruce, cone biomorphology, wood macrostructure, density, sound velocity, acoustic constant, dendroacoustic indices identification U radu su prikazani rezultati dendroakustickog istraZivanja te statisticke i korelacijske analize. Autori takoder daju uvid u heuristicku identifikaciju utemeljenu na primjeni biotehnickog zakona radi definiranja odnosa rezonantnih svojstava drva i oblika ljuske smrekova sjemena u ruskoj regiji Kama-Volga. Kljucne rijeci: akusticna smreka, biomorfologija cesera, makrostruktura drva, gustoca drva, brzina zvuka, akusticna konstanta, identifikacija dendroakustickih indikacija
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