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Tytuł:
Mutational witches’ broom impact on the growth of the parent branch in several Pinaceae species
Autorzy:
Zhuk, E.
Vasilyeva, G.
Goroshkevich, S.
Powiązania:
https://bibliotekanauki.pl/articles/2077653.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Instytut Dendrologii PAN
Tematy:
somatic mutation
annual rings
crown part interaction
Opis:
Mutational witches’ broom is a part of the tree crown with abnormally dense branching and slow shoot growth, which putatively originates from a cell in a bud apical meristem and can be visually differentiated from the normal crown. The witches’ broom forms a large branching system which competes sufficiently with other parts of the tree crown. However, the competitive relationship and the interaction between the mutant and normal crown parts have not yet been studied. We investigated the patterns and dynamics of the competitive relationship between witches’ broom and normal branching systems of the same tree of five Pinaceae species by tree ring analysis. Three saw-cuts were made in each tree: on the lateral branch with the witches’ broom, on the proximal part of the axial branch in front of the branch with the witches’ broom, on the distal part of the axial branch right after the branch with the witches’ broom. An- nual radial growth was measured to the nearest 0.01 mm, and annual ring areas from three saw-cuts were analysed to compare the growth dynamics before and after witches’ broom appearance. The growth of the lateral branch with the witches’ broom sharply increased in the year of witches’ broom appearance by 2–10 times. The growth of the distal part of the axial branch sharply decreased in the same year, which could be explained only by the witches’ broom appearance. All branches with witches’ brooms gradually became thicker than the distal part of the branch, 3–150 times at the peak of growth, and occasionally outgrew even the proximal part of the branch. Thus, witches’ broom is drastically morphologically and physiologically different from the rest of the crown. All witches’ brooms had their own vertically oriented axis of symmetry and represented autonomous branching systems that were not subordinate to any other branching systems. They break the normal donor-acceptor relationship in a tree and eagerly consume resources without being fully involved in their production. The mutation clearly affects the hormonal regulation of growth and morphogenesis and turns a witches’ broom into a new metabolic sink.
Źródło:
Dendrobiology; 2020, 83; 52-59
1641-1307
Pojawia się w:
Dendrobiology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Wave propagation in piezoelectric rings with rectangular cross-sections
Autorzy:
Zhang, X.
Wang, Y.
Chen, H.
Powiązania:
https://bibliotekanauki.pl/articles/279995.pdf
Data publikacji:
2015
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
piezoelectric rings
orthogonal polynomial
guided wave
dispersion curves
Opis:
The ring ultrasonic transducers are widely used in the ocean engineering and medical fields. This paper employs an extended orthogonal polynomial approach to solve the guided wave propagation in two-dimensional structures, i.e. piezoelectric rings with rectangular cross- -sections. The extended polynomial approach can overcome the drawbacks of the conven- tional orthogonal polynomial approach which can be used to solve wave propagation in one-dimensional structures. Through numerical comparison with the available results for a rectangular aluminum bar, the validity of the present approach is illustrated. The dispersion curves and displacement and electric potential distributions of various rectangular piezo- electric rings are calculated, and the effects of different radius to thickness ratios, width to height ratios and polarizing directions on the dispersion curves are illustrated.
Źródło:
Journal of Theoretical and Applied Mechanics; 2015, 53, 3; 673-682
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigation of round Scots pine wood WC01 class using X-ray computer tomography
Autorzy:
Zatoń, Patrycja
Kozakiewicz, Paweł
Mańkowski, Piotr
Powiązania:
https://bibliotekanauki.pl/articles/2171746.pdf
Data publikacji:
2022
Wydawca:
Szkoła Główna Gospodarstwa Wiejskiego w Warszawie. Wydawnictwo Szkoły Głównej Gospodarstwa Wiejskiego w Warszawie
Tematy:
X-ray computer tomography
quality of round wood
Scots pine wood
density of wood
annual rings
moisture content of wood
Opis:
Investigation of round Scots pine wood WC01 class using X-ray computer tomography. Scots pine is the most widespread type of wood in Poland with wide industrial use. The typical starting material used for the production of layered floor elements are logs of WC01 class (class according to the Polish Standard PN-D-95008: 1992 and Order no 72 - GM-900-5 / 2013 of General Director of the State Forests in Poland). Using X-ray computed tomography, tests of fresh wood in the bark were carried out, confirming the full suitability of this technique for the precise assessment of wood density as well as its grain and distribution of anatomical defects (knots). The different level of humidity of sapwood and heartwood in fresh wood is visible in tomographic images and translates into a much higher recorded density of the wetter zone of sapwood. Calibration of the tomograph used made it possible to convert the Hounsfield density scale into actual densities expressed in kg/m3.
Badania okrągłego drewna sosnowego klasy WC01 z zastosowaniem rentgenowskiej tomografii komputerowej. Sosna zwyczajna to najbardziej rozpowszechniony gatunek drewna w Polsce o szerokim zastosowaniu przemysłowym. Typowym surowcem wyjściowym stosowanym do produkcji warstwowych elementów podłogowych są kłody klasy WC01. Przy wykorzystaniu rentgenowskiej tomografii komputerowej przeprowadzono badania świeżego drewna w korze, potwierdzając pełną przydatność tej techniki do precyzyjnej oceny gęstości drewna a także jego słoistości i rozmieszczenia wad anatomicznych (sęków). Różny poziom wilgotności drewna bieli i twardzieli w świeżym drewnie jest doskonale widoczny w obrazach tomograficznych i przekłada na zdecydowanie wyższą odnotowaną gęstość wilgotniejszej strefy drewna bielastego. Wzorcowanie zastosowanego tomografu w danym trybie nastaw pozwoliło na przeliczenie skali gęstościowej Hounsfilda na rzeczywiste i jednocześnie praktyczne wartości gęstości wyrażone w kg/m3.
Źródło:
Annals of Warsaw University of Life Sciences - SGGW. Forestry and Wood Technology; 2022, 117; 97--105
1898-5912
Pojawia się w:
Annals of Warsaw University of Life Sciences - SGGW. Forestry and Wood Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of asymmetric elliptical shapes of the sealing ring sliding surface on the main parameters of the oil film
Autorzy:
Wróblewski, P.
Powiązania:
https://bibliotekanauki.pl/articles/133158.pdf
Data publikacji:
2017
Wydawca:
Polskie Towarzystwo Naukowe Silników Spalinowych
Tematy:
rings with asymmetrical sliding surface shape
friction loss
oil film
quantification of lubricant oil consumption
straty tarcia
film olejowy
zużycie oleju smarowego
Opis:
This article discusses the results of simulation studies of the effect of selected sealing ring sets with asymmetrical elliptical sliding surfaces on the oil layer thickness distribution over the whole operating range of an internal combustion engine. The problem of calculating the sliding surface coverage with visco-elastic oil film as well as in mixed friction conditions is discussed. The effect of asymmetrical elliptical sliding surfaces particularly on the dimensionless slip and squeeze indicators was determined, defining these surfaces ability to produce an oil film. The research results presented in this article show that there exists a real possibility of friction loss reduction in the cylinder and sealing rings contact area, while maintaining the oil film continuity between the sliding surfaces.
Źródło:
Combustion Engines; 2017, 56, 1; 84-93
2300-9896
2658-1442
Pojawia się w:
Combustion Engines
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The effect of the distribution of variable characteristics determining the asymmetry of the sealing rings sliding surfaces on the values of friction loss coefficients and other selected parameters of oil film
Autorzy:
Wróblewski, P.
Powiązania:
https://bibliotekanauki.pl/articles/133559.pdf
Data publikacji:
2017
Wydawca:
Polskie Towarzystwo Naukowe Silników Spalinowych
Tematy:
rings asymmetrical sliding surface
friction loss
oil film
straty tarcia
film olejowy
Opis:
The article presents the results of research on the effect of the change in coordinates that determine the location of the common vertex of the parabolas and ellipses demonstrating the asymmetric shape of the rings sliding surfaces on the change in the thickness of oil film, the amount of scraped oil, and the oil left on the cylinder wall, once a set of selected sealing rings has passed, as well as the results concerning friction losses. Mathematical relationships of the asymmetric shapes of the rings sliding surfaces were presented, and the values of coefficients characterizing selected parameters of oil film and friction losses were determined. It was confirmed that there is a large dependence of the coordinate values of the vertices determining the asymmetric shapes of these surfaces on the condition and cooperation between piston rings and the cylinder bearing surface, and mainly on the amount of the oil scraped in the selected engine strokes.
Źródło:
Combustion Engines; 2017, 56, 4; 107-116
2300-9896
2658-1442
Pojawia się w:
Combustion Engines
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Load condition analysis of pipe flange connection with gasket flat gasket and loose clamping rings
Autorzy:
Wróbel, Gabriel
Walczak, Kazimierz
Powiązania:
https://bibliotekanauki.pl/articles/2105506.pdf
Data publikacji:
2022
Wydawca:
Stowarzyszenie Komputerowej Nauki o Materiałach i Inżynierii Powierzchni w Gliwicach
Tematy:
pipe
connection
clamping rings
ring stiffness
polyester-glass composites
rura
połączenie
sztywność obwodowa
kompozyty poliestrowo-szklane
Opis:
Purpose: This paper describes the study of the connection with loose fixing composite rings of pipe flanges. The elastic properties of the joint components - gasket, pressure flanges, rings and fixing bolts were determined experimentally. Design/methodology/approach: The criterion of joint tightness was formulated. The constructed model was used to determine the analytical dependence of the joint leakage pressure on the assembly torque of bolts tightening. The correctness of the model was confirmed by the agreement of the analytical results with the experimental results. Findings: Quantitative characteristics were determined for the selected type of joint. Practical implications: The formulated conclusions indicate the possibility of using the model to support the design process and to select the structural parameters of the joint meeting the operational requirements and safety criteria. Originality/value: Produced with recycled materials using.
Źródło:
Journal of Achievements in Materials and Manufacturing Engineering; 2022, 111, 1; 5--17
1734-8412
Pojawia się w:
Journal of Achievements in Materials and Manufacturing Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of engine load on piston ring pack operation of an automotive IC engine
Autorzy:
Wolff, Andrzej
Koszałka, Grzegorz
Powiązania:
https://bibliotekanauki.pl/articles/2097662.pdf
Data publikacji:
2022
Wydawca:
Polskie Towarzystwo Naukowe Silników Spalinowych
Tematy:
automotive IC engine
piston rings
blowby
ring dynamics
hydrodynamic lubrication
mixed friction
silnik o spalaniu wewnętrznym
pierścienie tłokowe
przedmuchy spalin
dynamika pierścienia
smarowanie hydrodynamiczne
tarcie mieszane
Opis:
A piston-rings-cylinder (PRC) assembly determines the blowby, engine oil consumption, and friction and wear processes accompanying the system's operation. Thus, it is crucial for the whole IC engine efficiency and lifetime. A lot of research effort is put into increasing the performance of this complex and highly dynamic system. Advanced, comprehensive models play an important role in understanding and improving the PRC system. In the presented work, the effect of load on the operation of the ring pack of an automotive gasoline engine is analyzed. A comprehensive model that covers the gas flow through the crevices of the PRC system, ring displacements in the groove, and ring lubrication was used for this analysis. The results of the simulations show that the local thickness of the oil film, especially near the piston top dead center is compared to the height of the combined surface roughness of a cylinder liner and piston rings, and friction-related asperity contact strongly increases as the engine load increases. The simulations also show that the engine load affects the axial displacements of the rings in the grooves but practically does not affect the thickness of the oil film left by the ring pack on the cylinder liner.
Źródło:
Combustion Engines; 2022, 61, 3; 88--94
2300-9896
2658-1442
Pojawia się w:
Combustion Engines
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of piston ring profiles and oil temperature distribution on cylinder liner lubrication of a marine two-stroke engine
Autorzy:
Wolff, Andrzej
Powiązania:
https://bibliotekanauki.pl/articles/132952.pdf
Data publikacji:
2019
Wydawca:
Polskie Towarzystwo Naukowe Silników Spalinowych
Tematy:
marine engines
piston rings
gasdynamics
hydrodynamic lubrication
mixed friction
silniki okrętowe
pierścienie tłokowe
gazodynamika
smarowanie hydrodynamiczne
tarcie mieszane
Opis:
In the paper a comprehensive model of a piston-ring-cylinder (PRC) system has been presented. The local thickness of the oil film can be compared to height of the combined surface roughness of a cylinder liner and piston rings. Equations describing the mixed lubrication problem based on the empirical mathematical model formulated in works of Patir, Cheng and Greenwood, Tripp have been applied. The main parts of the model have been experimentally verified abroad by the author at the marine engine designing centre. In contrast to the previous papers of the author concerning the PRC system of combustion engines, new calculation results for a marine two-stroke engine have been presented. Firstly the right selection of barrel-shaped sliding surface of piston rings has been analysed. Secondly the influence of oil temperature distribution along the cylinder liner on the lubrication of the PRC system has been assessed. The developed model and software can be useful for optimization of the PRC system design.
Źródło:
Combustion Engines; 2019, 58, 3; 257-263
2300-9896
2658-1442
Pojawia się w:
Combustion Engines
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of engine load on piston ring pack operation of a marine two - stroke engine
Autorzy:
Wolff, A.
Powiązania:
https://bibliotekanauki.pl/articles/246695.pdf
Data publikacji:
2012
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
marine engines
piston rings
gas dynamics
hydrodynamic lubrication
mixed friction
Opis:
A set of piston rings is used to form a dynamic gas seal between the piston and cylinder wall. Many physical phenomena are associated with the operation of the system piston-ring-cylinder (PRC), such as: inter-ring gas dynamics for the labyrinth seal, hydrodynamic lubrication and mixed friction in gaps between the rings and cylinder liner, oil flow and distribution of lubricant along the liner, twist motion of rings, liner temperature influence on the oil viscosity. A complex model of the PRC system has been developed by the author. Among own models it includes several sub-models taken from literature, like: a model of viscous oil flow between rough gap surfaces formulated by Patir and Cheng and an elastic contact model of Greenwood and Tripp. The main parts of the mathematical model and software have been experimentally verified abroad by the author at the marine engine-designing centre. A relatively good qualitative and quantitative compatibility between the experimental measurements and calculated results has been achieved. In contrast to the previous papers of the author, new calculation results for a marine two-stroke engine have been presented. These results concern influence of engine load on piston ring pack operation of the analysed engine. They include basic physical quantities associated with gas and oil flow in the piston-ring-cylinder system of the engine. The developed model can be utilized for: evaluation of gas leakage through the sealing ring set, prediction of lubrication conditions of piston rings and oil consumption, defining areas of the possible cylinder liner wear and profile changes of piston rings sliding surfaces, and thus can be useful for optimization of the PRC system design.
Źródło:
Journal of KONES; 2012, 19, 2; 557-568
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of piston ring pack configuration on blowby and friction losses in a marine two-stroke engine
Autorzy:
Wolff, A.
Powiązania:
https://bibliotekanauki.pl/articles/134100.pdf
Data publikacji:
2017
Wydawca:
Polskie Towarzystwo Naukowe Silników Spalinowych
Tematy:
marine engines
piston rings
gas dynamics
hydrodynamic lubrication
mixed friction
silnik okrętowy
pierścień tłokowy
dynamika gazów
smarowanie hydrodynamiczne
tarcie mieszane
Opis:
In the paper a comprehensive model of a piston ring pack motion on an oil film has been presented. The local thickness of the oil film can be compared to height of the combined surface roughness of a cylinder liner and piston rings. Equations describing the mixed lubrication problem based on the empirical mathematical model formulated in works of Patir, Cheng and Greenwood, Tripp have been combined and used in this paper. In addition a model of gas flow through the labyrinth seal of piston rings has been developed. The main parts of the model and software have been experimentally verified abroad by the author at the marine engine designing centre. For the selected two-stroke marine engine, the influence of the number of piston rings used and the type of the top ring lock (straight or overlapped) on blowby to piston underside and on friction losses of the piston-ring-cylinder (PRC) system have been investigated. The developed model and software can be useful for optimization of the PRC system design.
Źródło:
Combustion Engines; 2017, 56, 3; 164-170
2300-9896
2658-1442
Pojawia się w:
Combustion Engines
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Lata wskaźnikowe świerka pospolitego w Beskidach Zachodnich
Pointer years of Norway spruce in the Western Beskidy Mountains (southern Poland)
Autorzy:
Wilczyński, S.
Szymański, N.
Powiązania:
https://bibliotekanauki.pl/articles/991365.pdf
Data publikacji:
2014
Wydawca:
Polskie Towarzystwo Leśne
Tematy:
gory
Beskidy Zachodnie
drzewa lesne
swierk pospolity
przyrost drzew
sloje przyrostu rocznego
przyrost grubosci
czynniki klimatyczne
lata wskaznikowe
tree rings
pointer years
norway spruce
western beskidy mountains
altitudinal zone
Opis:
The frequency of site and zonal pointer years in Norway spruce in two altitudinal zones (500−900 m and 900−1370 m a.s.l.) in the Western Beskidy Mountains was analysed. In total, 32 tree stands were studied – 16 in each zone. In both zones number of negative site pointer years increased along with increase of number of positive site pointer years. Above 900 m a. s. l. number of site pointer years increased along with the altitude, while below 900 m a.s.l. their number decreased along with the altitude. We found no common pointer years for all 32 populations. In lower zone, short winter, early and very warm spring or high precipitation in June and July in a given year caused negative pointer years. In the upper one positive pointer years occurred after the warm autumn and in years with the warm growing season.
Źródło:
Sylwan; 2014, 158, 12; 883-892
0039-7660
Pojawia się w:
Sylwan
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Life span and growth rate of Middle Jurassic mesohibolitid belemnites deduced from rostrum microincrements
Autorzy:
Wierzbowski, H.
Powiązania:
https://bibliotekanauki.pl/articles/2061020.pdf
Data publikacji:
2013
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
belemnite rostra
belemnites
growth rings
Polish Jura Chain
Bathonian
Ore Bering Częstochowa Clay Formation
rostry belemnitów
belemnity
pierścienie wzrostu
Wyżyna Krakowsko-Częstochowska
baton
formacja częstochowskich iłów rudonośnych
Opis:
The microincrements of nine Middle Jurassic mesohibolitid belemnite rostra (Hibolithes jurensis, Pachybelemnopsis fusiformis and Pachybelemnopsis “subhastatus”) were analysed to measure the ontogenic age and growth rate of the belemnites. The microincrements are interpreted to have been formed daily based on analogy with extant coleoid cephalopods and the frequency of circadian rhythms in animal activity. The mesohibolitid belemnites are found to have had a short life span of ca. 1 year. The short life span of the belemnites studied is similar to the life span of modern coleoids (squids, cuttlefishes and common octopuses). It restricts the utility of belemnite rostra as a proxy for average secular seawater temperatures and chemistry. Short-lived cycles (2–8 days) in the belemnite growth rate are linked to variations in the metabolic activity of these animals. Minor diagenetic alteration revealed by the dull cathodoluminescence of some rostra is found to have no effect on the preservation of the growth rings.
Źródło:
Volumina Jurassica; 2013, 11, 1; 1--18
1896-7876
1731-3708
Pojawia się w:
Volumina Jurassica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Struktura drewna konstrukcyjnego
Structural timber characteristics
Autorzy:
Wdowiak, A.
Powiązania:
https://bibliotekanauki.pl/articles/105498.pdf
Data publikacji:
2017
Wydawca:
Politechnika Rzeszowska im. Ignacego Łukasiewicza. Oficyna Wydawnicza
Tematy:
drewno
struktura mikroskopowa
struktura makroskopowa
przyrosty roczne
biel
twardziel
pęcherze
wycieki żywiczne
promienie łykodrzewne
sosna zwyczajna
Pinus sylvestris L.
świerk pospolity
Picea abies Karst.
modrzew europejski
Larix decidua Mill.
jodła pospolita
Abies alba Mill.
daglezja zielona
Pseudotsuga menziesii Franco
wood
microscopic structure
macroscopic structure
annual rings
sapwood and heartwood
resin pockets and leaks
medullary rays
pine
spruce
European larch
silver fir
Douglas fir
Opis:
Drewno to priorytetowy surowiec dla przemysłu celulozowego i energetycznego. Źródłem surowcowym są lasy. Powierzchnia lasów w Polsce, z roku na rok, nieustannie wzrasta. Wzrost lesistości od roku 1945 wynosi 8,4%. Przyrost ten jest wynikiem zalesiania gruntów użytkowanych przez rolnictwo i nieużytków [1]. W monografii przedstawiono budowę mikroskopową i makroskopową drewna sosny zwyczajnej Pinus sylvestris L., pochodzącej z czterech wybranych krain przyrodniczoleśnych Polski: Kraina A - Mazowiecko – Podlaska Kraina Przyrodniczo – Leśna (Nadleśnictwo Garwolin), Kraina B - Małopolska Kraina Przyrodniczo – Leśna (Nadleśnictwo Przedbórz), Kraina C - Śląska Kraina Przyrodniczo – Leśna (Nadleśnictwo Kędzierzyn Koźle), Kraina D - Karpacka Kraina Przyrodniczo – Leśna (Nadleśnictwo Piwniczna). Ukazano strukturę mikroskopową jodły pospolitej Abies alba Mill, modrzewia europejskiego Larix decidua Mill. pochodzącego z zabytkowego obiektu wybudowanego w 1860 r., sosny zwyczajnej Pinus sylvestris L. poddanej 5 - letnim wpływom atmosferycznym oraz degradacji biologicznej. Określono przyrosty roczne, biel i twardziel, pęcherze i wycieki żywiczne oraz promienie łykodrzewne. Zaprezentowano właściwości rozpoznawcze wybranych rodzajów drewna iglastego, w szczególności zabarwienie twardzieli, szerokość przyrostów rocznych, udział bielu i twardzieli, obecność przewodów żywicznych, przejście z drewna wczesnego do późnego czy strukturę sęka. Dodatkowo scharakteryzowano takie gatunki drzew, jak sosna zwyczajna Pinus sylvestris L., świerk pospolity Picea abies Karst., modrzew europejski Larix decidua Mill., jodła pospolita Abies alba Mill., daglezja zielona Pseudotsuga menziesii Franco [1-2].
Wood is a basic raw material for paper and pulp industry, and also in power generation. Wood supplies are provided by forests. In Poland, the area of forests continues to increase annually. Since 1945, forest cover has grown by 8.4%. The increment results from afforestation of the land with former agricultural use, and of uncultivated land [1]. In the monograph, the micro- and macroscopic structure of wood from pine Pinus sylvestris L. was presented. The wood originated from four selected nature-forest areas of Poland, namely Area A - Mazowiecko – Podlaska Nature-Forest Area (Garwolin Forest Inspectorate), Area B - Małopolska Nature-Forest Area (Przedbórz Forest Inspectorate), Area C - Śląska Nature-Forest Area (Kędzierzyn Koźle Forest Inspectorate), Area D - Karpacka Nature-Forest Area (Piwniczna Forest Inspectorate). Wood microscopic structure analysis was performed for the following conifer species: silver fir Abies alba Mill, European larch Larix decidua Mill., the wood of which was obtained from a historical structure built in 1860, and pine Pinus sylvestris L., the wood of which was exposed to atmospheric conditions and biological degradation for a 5 – year period. The following features were specified: annual rings, sapwood and heartwood, resin pockets and leaks, and also medullary rays. The distinctive properties of selected coniferous wood species were presented, including heartwood colour, the width of annual rings, sapwood and heartwood content, the occurrence of resin ducts, transition from earlywood to latewood, and also knot structure. Additionally, the characteristics of the wood of the following species were provided: pine Pinus sylvestris L., spruce Picea abies Karst., European larch Larix decidua Mill., silver fir Abies alba Mill., Douglas fir Pseudotsuga menziesii Franco [1-2].
Źródło:
Czasopismo Inżynierii Lądowej, Środowiska i Architektury; 2017, 64, 4/I; 363-378
2300-5130
2300-8903
Pojawia się w:
Czasopismo Inżynierii Lądowej, Środowiska i Architektury
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Zmienność wybranych cech makrostruktury i gęstości drewna dębu czerwonego (Quercus rubra L.) z Polski południowo-wschodniej
Variability of selected macrostructural features and the wood density of northern red oak (Quercus rubra L.) from south-eastern Poland
Autorzy:
Wąsik, R.
Michalec, K.
Powiązania:
https://bibliotekanauki.pl/articles/979284.pdf
Data publikacji:
2020
Wydawca:
Polskie Towarzystwo Leśne
Tematy:
red oak
sapwood
annual rings
latewood
density
Opis:
The aim of the paper was to determine the variability of selected macrostructural features and wood density for northern red oak growing in south−eastern Poland. On 4 study plots, we sampled each tree, taking an increment core from the northern side of the trunk, from the height of 1.3 m. The number of tree rings, width and the share of sapwood was measured. The cores were scanned and then tree ring and latewood widths were measured. The latewood proportion in each ring was calculated. Next, starting from the bark, the cores were divided into sections containing 10 annual rings. The relative wood density was determined for each section, then the density was calculated for entire stem cross−section. The mean sapwood width was 1.5 cm. It included 7 annual rings on average, and its share in the trunk cross−sectional area reached 17%. Younger red oaks (II and III age classes) had a significantly higher share of sapwood compared to older trees (IV and V age classes). The investigated red oaks formed narrow−ring wood with an average width of 2.16 mm. The trees growing on deciduous forest habitat had a more equal tree ring width compared to trees from coniferous forest habitats, where this feature showed also higher variability. The latewood proportion in the studied red oaks was 60% on average. The mean relative wood density was 0.578 g/cm3 and it was slightly higher than the value given for red oaks growing in North America. The calculated absolute density (with an assumed volumetric shrinkage from 12.9 to 13.7%) varied from 0.664 to 0.670 g/cm3. It classifies the investigated wood as moderately heavy. Similar density values are given for native oaks, which allows to assume that the technical quality of the wood of red oaks growing in Poland is similar to native oak species. The wood of trees from deciduous forest habitat showed a significantly higher density and a more equal distribution compared to the trees from coniferous forest sites. The raw material of red oaks obtained from deciduous forest habitats should characterize by a better technical quality of wood in comparison with that obtained from coniferous forest sites.
Źródło:
Sylwan; 2020, 164, 10; 850-859
0039-7660
Pojawia się w:
Sylwan
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A reduction theorem for ring varieties whose subvariety lattice is distributive
Autorzy:
Volkov, Mikhail
Powiązania:
https://bibliotekanauki.pl/articles/729065.pdf
Data publikacji:
2010
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
variety of rings
subvariety lattice
distributive lattice
torsion-bounded variety
Mal'tsev product
Opis:
We prove a theorem (for arbitrary ring varieties and, in a stronger form, for varieties of associative rings) which basically reduces the problem of a description of varieties with distributive subvariety lattice to the case of algebras over a finite prime field.
Źródło:
Discussiones Mathematicae - General Algebra and Applications; 2010, 30, 1; 119-132
1509-9415
Pojawia się w:
Discussiones Mathematicae - General Algebra and Applications
Dostawca treści:
Biblioteka Nauki
Artykuł

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