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Tytuł:
On strong automorphisms of direct products of Witt rings. Part 2
Autorzy:
Stępień, M. R.
Stępień, L.
Powiązania:
https://bibliotekanauki.pl/articles/122291.pdf
Data publikacji:
2013
Wydawca:
Politechnika Częstochowska. Wydawnictwo Politechniki Częstochowskiej
Tematy:
Witt rings
strong automorphisms
group rings
Opis:
In the paper strong automorphisms of finitely generated Witt rings are considered. Every finitely generated Witt ring can be expressed in terms of Z / 2Z and basic indecomposable Witt rings using the operations of group ring formation and direct product. Groups of strong automorphisms of basic indecomposables and their direct products and the description of all strong automorphisms of any group Witt ring are known. In this paper the strong automorphisms of direct products of group Witt rings are considered. Presented are two wide classes of Witt rings where the group of strong automorphisms is isomorphic to the direct product of groups of strong automorphisms of Witt rings which are factors in the direct product.
Źródło:
Journal of Applied Mathematics and Computational Mechanics; 2013, 12, 4; 119-125
2299-9965
Pojawia się w:
Journal of Applied Mathematics and Computational Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Invo-regular unital rings
Autorzy:
Danchev, Peter V.
Powiązania:
https://bibliotekanauki.pl/articles/747073.pdf
Data publikacji:
2018
Wydawca:
Uniwersytet Marii Curie-Skłodowskiej. Wydawnictwo Uniwersytetu Marii Curie-Skłodowskiej
Tematy:
Unit-regular rings
clean rings
strongly clean rings
idempotents
involutions
nilpotents
units
Opis:
It was asked by Nicholson (Comm. Algebra, 1999) whether or not unit-regular rings are themselves strongly clean. Although they are clean as proved by Camillo-Khurana (Comm. Algebra, 2001), recently Nielsen and Ster showed in Trans. Amer. Math. Soc., 2018 that there exists a unit-regular ring which is not strongly clean. However, we define here a proper subclass of rings of the class of unit-regular rings, called invo-regular rings, and establish that they are strongly clean. Interestingly, without any concrete indications a priori, these rings are manifestly even commutative invo-clean as defined by the author in Commun. Korean Math. Soc., 2017.
Źródło:
Annales Universitatis Mariae Curie-Skłodowska, sectio A – Mathematica; 2018, 72, 1
0365-1029
2083-7402
Pojawia się w:
Annales Universitatis Mariae Curie-Skłodowska, sectio A – Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Some results of reverse derivation on prime and semiprime Γ-rings
Autorzy:
Suliman, Neshtiman
Powiązania:
https://bibliotekanauki.pl/articles/729163.pdf
Data publikacji:
2015
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
Prime Γ-rings
semiprime Γ-rings
derivations
reverse derivations
Opis:
In the present paper, it is introduced the definition of a reverse derivation on a Γ-ring M. It is shown that a mapping derivation on a semiprime Γ-ring M is central if and only if it is reverse derivation. Also it is shown that M is commutative if for all a,b ∈ I (I is an ideal of M) satisfying d(a) ∈ Z(M), and d(a ∘ b) = 0.
Źródło:
Discussiones Mathematicae - General Algebra and Applications; 2015, 35, 1; 53-58
1509-9415
Pojawia się w:
Discussiones Mathematicae - General Algebra and Applications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Some mixed matrix problems over several discrete valuation rings
Autorzy:
Gubareni, N.
Powiązania:
https://bibliotekanauki.pl/articles/122874.pdf
Data publikacji:
2013
Wydawca:
Politechnika Częstochowska. Wydawnictwo Politechniki Częstochowskiej
Tematy:
valuation rings
local invariant rings
discrete valuation rings
approximation theorem
mixed flat matrix problems
Opis:
This article presents some results about several district valuation rings with a common skew field of fractions. They are obtained from the approximation theorem for discrete valuation rings. These results give the possibility to solve basic mixed matrix problems for such rings. We present the solution of some mixed flat matrix problems over several district valuation rings with common skew field of fractions.
Źródło:
Journal of Applied Mathematics and Computational Mechanics; 2013, 12, 4; 47-58
2299-9965
Pojawia się w:
Journal of Applied Mathematics and Computational Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Localization in semicommutative (m,n)-rings
Autorzy:
Iancu, Lăcrimioara
Pop, Maria
Powiązania:
https://bibliotekanauki.pl/articles/728784.pdf
Data publikacji:
2000
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
(m,n)-rings
semicommutative (m,n)-rings
(m,n)-rings of quotients
(m,n)-division rings
(m,n)-semidomains
n-groups
n-semigroups
Opis:
We give a construction for (m,n)-rings of quotients of a semicommutative (m,n)-ring, which generalizes the ones given by Crombez and Timm and by Paunić for the commutative case. We also study various constructions involving reduced rings and rings of quotients and give some functorial interpretations.
Źródło:
Discussiones Mathematicae - General Algebra and Applications; 2000, 20, 2; 233-253
1509-9415
Pojawia się w:
Discussiones Mathematicae - General Algebra and Applications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Some Remarks on Rings
Autorzy:
Obojska, Lidia
O’Hara, Paul
Powiązania:
https://bibliotekanauki.pl/articles/745218.pdf
Data publikacji:
2010
Wydawca:
Polskie Towarzystwo Matematyczne
Tematy:
Distribution law
Rings
Isomorphism
Opis:
Algebraic structures such as Rings, Fields, Boolean Algebras (Set Theory) and \(\sigma\)-Fields are well known and much has been written about them. In this paper we explore some properties of rings related to the distribution law. Specifically, we shall show that for rings there exists only one distribution law. Moreover, for the ring \((Z_{p(p−1)n} +, \cdot)\), where \((p, n) = 1\) there exist isomorphic groups \((G, +)\), \((H, \cdot)\), \(G, H \subset Z_{p(p−1)n}\) of the order \((p − 1)\). Finally, we note that every ring \((Z_{pn}, +, \cdot)\) contains subfields \(\text{mod}(pn)\).
Źródło:
Commentationes Mathematicae; 2010, 50, 1
0373-8299
Pojawia się w:
Commentationes Mathematicae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Semiprime FDI-rings
Autorzy:
Gubareni, N.
Powiązania:
https://bibliotekanauki.pl/articles/122728.pdf
Data publikacji:
2014
Wydawca:
Politechnika Częstochowska. Wydawnictwo Politechniki Częstochowskiej
Tematy:
semiprime rings
prime rings
nilpotent ideal
nilpotency index
Jacobson radical
semiperfect ring
complete set of idempotents
FDI-rings
Opis:
In this paper we present some results for FDI-rings, i.e. rings with a complete set of pairwise orthogonal primitive idempotents. We consider the nilpotency index of ideals and give its upper band for ideals in some classes of rings. We also give a new proof of a criterion of semiprime FDI-rings to be prime.
Źródło:
Journal of Applied Mathematics and Computational Mechanics; 2014, 13, 4; 49-59
2299-9965
Pojawia się w:
Journal of Applied Mathematics and Computational Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the Witt rings of function fields of quasihomogeneous varieties
Autorzy:
Jaworski, Piotr
Powiązania:
https://bibliotekanauki.pl/articles/966718.pdf
Data publikacji:
1997
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
Witt rings
graded rings
selfdual vector bundles
quasihomogeneous varieties
residue homomorphisms
Źródło:
Colloquium Mathematicum; 1997, 73, 2; 195-219
0010-1354
Pojawia się w:
Colloquium Mathematicum
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Semihereditary rings and related topics
Autorzy:
Gubareni, N.
Powiązania:
https://bibliotekanauki.pl/articles/122027.pdf
Data publikacji:
2011
Wydawca:
Uniwersytet Humanistyczno-Przyrodniczy im. Jana Długosza w Częstochowie. Wydawnictwo Uczelniane
Tematy:
semihereditary rings
homological algebra
non commutative rings
pierścienie półdziedziczne
algebra homologiczna
pierścienie nieprzemienne
Opis:
A ring A is called right (left) semihereditary if all finitely generated right (left) ideals of A are projective. In this paper we consider non-commutative semihereditary rings and show their connection with non-commutative valuation rings. We also present some criterion for a module to be flat.
Źródło:
Scientific Issues of Jan Długosz University in Częstochowa. Mathematics; 2011, 16; 33-38
2450-9302
Pojawia się w:
Scientific Issues of Jan Długosz University in Częstochowa. Mathematics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A variation of zero-divisor graphs
Autorzy:
Gupta, Raibatak
Sen, M.
Ghosh, Shamik
Powiązania:
https://bibliotekanauki.pl/articles/729141.pdf
Data publikacji:
2015
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
rings
zero-divisor graphs
finite fields
Opis:
In this paper, we define a new graph for a ring with unity by extending the definition of the usual 'zero-divisor graph'. For a ring R with unity, Γ₁(R) is defined to be the simple undirected graph having all non-zero elements of R as its vertices and two distinct vertices x,y are adjacent if and only if either xy=0 or yx=0 or x+y is a unit. We consider the conditions of connectedness and show that for a finite commutative ring R with unity, Γ₁(R) is connected if and only if R is not isomorphic to ℤ₃ or $ℤ₂^k$ (for any k ∈ ℕ-{1}\). Then we characterize the rings R for which Γ₁(R) realizes some well-known classes of graphs, viz., complete graphs, star graphs, paths (i.e., $P_n$), or cycles (i.e., $C_n$). We then look at different graph-theoretical properties of the graph Γ₁(F), where F is a finite field. We also find all possible Γ₁(R) graphs with at most 6 vertices.
Źródło:
Discussiones Mathematicae - General Algebra and Applications; 2015, 35, 2; 159-176
1509-9415
Pojawia się w:
Discussiones Mathematicae - General Algebra and Applications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Automatic search of automorphisms of Witt rings
Autorzy:
Stępień, L.
Stępień, M. R.
Powiązania:
https://bibliotekanauki.pl/articles/121845.pdf
Data publikacji:
2011
Wydawca:
Uniwersytet Humanistyczno-Przyrodniczy im. Jana Długosza w Częstochowie. Wydawnictwo Uczelniane
Tematy:
Witt rings
automorphisms
strong automorphisms
automorphisms of Witt rings
pierścień Witta
automorfizm
automorfizmy pierścieni Witta
Opis:
The investigation of strong automorphisms of Witt rings is a difficult task because of variety of their structures. Cordes Theorem, known in literature as Harrison-Cordes criterion (cf. [1, Proposition 2.2], [3, Harrison's Criterion]), makes the task of describing all the strong automorphisms of a given (abstract) Witt ring W = (G, R) easier. By this theorem, it suffices to find all such automorphisms ơ of the group G that map the distiguished element -1 of the group G into itself (i.e. ơ(-1) = -1) in which the value sets of 1-fold Pfister forms are preserved in the following sense: ơ(D(1, α)) = D(1, ơ(α)) for all α ∈ G. We use the above criterion and the well-known structure of the group G as a vector space over two-element field F2 for searching all automorphisms of this group. Then we check Harrison-Cordes criterion for found automorpisms and obtain all the automorpisms of a Witt ring W. The task is easy for small rings (with small groups G). For searching of all strong automorpisms of bigger Witt rings we use a computer which automatizes the procedure described above. We present the algorithm for finding strong automorphisms of a Witt rings with finite group G and show how this algorithm can be optimized.
Źródło:
Scientific Issues of Jan Długosz University in Częstochowa. Mathematics; 2011, 16; 141-146
2450-9302
Pojawia się w:
Scientific Issues of Jan Długosz University in Częstochowa. Mathematics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Lie ideals in prime Γ-rings with derivations
Autorzy:
Suliman, Nishteman
Majeed, Abdul-Rahman
Powiązania:
https://bibliotekanauki.pl/articles/728934.pdf
Data publikacji:
2013
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
prime Γ-rings
Lie ideals
derivations
Opis:
Let M be a 2 and 3-torsion free prime Γ-ring, d a nonzero derivation on M and U a nonzero Lie ideal of M. In this paper it is proved that U is a central Lie ideal of M if d satisfies one of the following
(i) d(U)⊂ Z,
(ii) d(U)⊂ U and d²(U)=0,
(iii) d(U)⊂ U, d²(U)⊂ Z.
Źródło:
Discussiones Mathematicae - General Algebra and Applications; 2013, 33, 1; 49-56
1509-9415
Pojawia się w:
Discussiones Mathematicae - General Algebra and Applications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On strong automorphisms of direct products of Witt rings. Part 1
Autorzy:
Stępień, M. R.
Stępień, L.
Powiązania:
https://bibliotekanauki.pl/articles/973617.pdf
Data publikacji:
2013
Wydawca:
Politechnika Częstochowska. Wydawnictwo Politechniki Częstochowskiej
Tematy:
Witt rings
quaternionic structures
strong automorphisms
Opis:
The notion of Witt ring is fundamental in bilinear algebra. Automorphisms of Witt rings have been investigated until recent years. In this paper we consider Witt rings which are direct products of finite number of other Witt rings. We shall present a necessary condition in order to group of all strong automorphisms of direct product of Witt rings be a direct product of groups of strong automorphisms of Witt rings which are factors in the direct product. Subsequently, there are considered some examples of Witt rings, where described condition is fulfilled.
Źródło:
Journal of Applied Mathematics and Computational Mechanics; 2013, 12, 3; 123-133
2299-9965
Pojawia się w:
Journal of Applied Mathematics and Computational Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Some homological properties of skew PBW extensions arising in non-commutative algebraic geometry
Autorzy:
Lezama, Oswaldo
Powiązania:
https://bibliotekanauki.pl/articles/38117319.pdf
Data publikacji:
2017-06-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
Auslander regularity condition
Cohen-Macaulay rings
strongly noetherian algebras
skew PBW extensions
filtered-graded rings
point modules
Opis:
In this short paper we study for the skew PBW (Poincar-Birkhoff-Witt) extensions some homological properties arising in non-commutative algebraic geometry, namely, Auslander-Gorenstein regularity, Cohen-Macaulayness and strongly noetherianity. Skew PBW extensions include a considerable number of non-commutative rings of polynomial type such that classical PBW extensions, quantum polynomial rings, multiplicative analogue of the Weyl algebra, some Sklyanin algebras, operator algebras, diffusion algebras, quadratic algebras in 3 variables, among many others. Parametrization of the point modules of some examples is also presented.
Źródło:
Discussiones Mathematicae - General Algebra and Applications; 2017, 37, 1; 45-57
1509-9415
Pojawia się w:
Discussiones Mathematicae - General Algebra and Applications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fossil wood from the Roztocze region (Miocene, SE Poland) : a tool for palaeoenvironmental reconstruction
Autorzy:
Kłusek, M.
Powiązania:
https://bibliotekanauki.pl/articles/2059126.pdf
Data publikacji:
2006
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Roztocze
fossil wood
wood anatomy
growth rings
Opis:
This article presents the results of anatomical and growth ring analyses of Badenian fossil wood from the Roztocze region. All the wood specimens examined are classified as Taxodioxylon taxodii Goth. The growth rings of these woods are very narrow, and they vary considerably in width. Tracheids have large diameters and thin cell walls.The latewood zone is wide; the transition between early and latewood is gradual. Both false and wedge rings and also reaction wood zones are often found. These characteristics of the fossil wood make it a suitable aid to reconstructing the environmental conditions prevailing while the trees were alive. The environmental requirements of these ancient Roztocze trees are interpreted by comparison with those of their nearest living relatives, with the conclusion that they lived in waterlogged or temporarily flooded stands under seasonally changing environmental conditions and with a long growing season. The climate was warm and humid and characterized by significant variability, mainly as regards the amount of precipitation.
Źródło:
Geological Quarterly; 2006, 50, 4; 465-474
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Automatic search of rational self-equivalences
Autorzy:
Stępień, L.
Stępień, M. R.
Powiązania:
https://bibliotekanauki.pl/articles/950276.pdf
Data publikacji:
2018
Wydawca:
Uniwersytet Humanistyczno-Przyrodniczy im. Jana Długosza w Częstochowie. Wydawnictwo Uczelniane
Tematy:
rational self-equivalences
automorphisms of Witt rings
Witt rings
algebra
algorithm
automatic search
automorfizm
pierścień Witta
algorytm
Opis:
Two Witt rings that are not strongly isomorphic (i.e., two Witt rings over two fields that are not Witt equivalent) have different groups of strong automorphisms. Therefore, the description of a group of strong automorphisms is different for almost every Witt ring, which requires the use various tools in proofs. It is natural idea to use computers to generate strong automorphisms of the Witt rings, which is especially effective in the case of the finitely generated Witt rings, where a complete list of strong automorphisms can be created. In this paper we present the algorithm that was used to generate strong automorphisms from the infinite group of strong automorphisms of the Witt ring of rational numbers W(Q).
Źródło:
Scientific Issues of Jan Długosz University in Częstochowa. Mathematics; 2018, 23; 67-74
2450-9302
Pojawia się w:
Scientific Issues of Jan Długosz University in Częstochowa. Mathematics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Measurements of maximum crankcase pressure for evaluation of the piston-rings- cylinder assembly
Autorzy:
Abramek, K.F.
Abramek, F.
Powiązania:
https://bibliotekanauki.pl/articles/242436.pdf
Data publikacji:
2009
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
blow-by
wear
piston
rings
cylinder
crankcase
Opis:
In the paper is presented statistical analysis of the effect of compression-ignition engine working time on the phenomenon of exhaust gas maximum pressure increase in crankcase and cylinder liner, pistons and rings wear. Characteristics of the crankcase maximum pressure variations were made for the start-up speed and for selected rotational speeds of the 359 compression-ignition engine crankshaft as well as micrometric measurements of the cylinder liner and pistons and rings wear. The engine was operated under normal traction conditions while pressure analyses and cylinder liner micrometric measurements were made, respectively, after an operational run of 204864 km. Crankcase exhaust gas maximum pressure measurements were made both with air vent open and closed for a cold (lubricating oil temperature of 285 K) and a warm engine (333 K). Basing on the analysis of obtained examination results, it was showed that crankcase exhaust gas maximum pressure measurement (also during the start-up) may be used for determination of engine run and life. Average and maximum wear and tear of cylinder liner s, maximum wear and tear of pistons in the perpendicular plane to the piston pin axis, dependency of maximum crankcase pressure in the function of operational mileage of a 359 engine for lubricating oil temperature of 333 K, dependency of maximum crankcase pressure in the function of operational mileage for lubricating oil temperature of 285 K are presented.
Źródło:
Journal of KONES; 2009, 16, 2; 23-28
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Climatic sensitivity of delta13C in tree rings of Quercus robur L., Populus tremula L. and Pinus sylvestris L. in Vilnius region (eastern Lithuania)
Autorzy:
Barisevičiūtė, Rūta
Skipitytė, Raminta
Pukienė, Rutilė
Lapeikaitė, Indrė
Kakaras, Irmantas
Remeikis, Vidmantas
Powiązania:
https://bibliotekanauki.pl/articles/956802.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Instytut Dendrologii PAN
Tematy:
δ13c
climate
tree-rings
dendroclimatology
Opis:
The aim of this work was to evaluate the possibilities of using carbon isotope measurements to determine a strong climate signal of trees influenced by the pollutant stress as well as to examine the difference in reaction of several investigated species to the climate change. Eurasian aspen (Populus tremula), pedunculate oak (Quercus robur) and Scots pine (Pinus sylvestris) trees from Vilnius region were selected for the stable carbon isotope analysis. Our results showed that over the last 70 years (1940–2009) the climate during summer months was the most important factor for the variation of stable carbon isotope values in tree rings, but its influence on different tree species slightly differed. δ13C measurements in Eurasian aspen best corresponded to the air temperature and the precipitation signal in July–August. Oak was more sensitive to the temperature and relative humidity in June–July. A positive correlation coefficient with temperature in the period of transition from the previous vegetation to dormancy season (previous September–October) was specific to oak as well. Scots pine grown at a polluted site was sensitive only to precipitation in summer months of the growing season. The correlation between δ13C measurements and climate data was determined to be from low to moderate in all the investigated trees and did not exceed the value of |r| ≥ 0.71 suggested by McCarroll et al. (2003) as a necessary value for the reliable climate reconstruction. However, the highest correlation coefficient values of 0.65 and 0.61, obtained between the maximal air temperature throughout the hydrological year (previous September–current August) and δ13C in oak rings or between mean monthly sunshine hours throughout July–August and δ13C values in aspen rings, respectively, are comparable with those used in many palaeoclimatic reconstructions that were based even on weaker correlations.
Źródło:
Dendrobiology; 2017, 78; 1-9
1641-1307
Pojawia się w:
Dendrobiology
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:
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:
Problemy profilowania i eksploatacji powierzchni roboczej elementów formujących pras walcowych
Some problems of surface shaping and the exploitation of the forming elements of roller presses
Autorzy:
Janewicz, A.
Powiązania:
https://bibliotekanauki.pl/articles/258414.pdf
Data publikacji:
2010
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Technologii Eksploatacji - Państwowy Instytut Badawczy
Tematy:
elementy formujące
wgłębienia formujące
brykieciarka walcowa
konstrukcja
eksploatacja
roller press
forming rolls
forming rings
pocket shapes
rings design
exploitation
Opis:
W artykule przedstawiono niektóre czynniki mające wpływ na profilowanie walcowej powierzchni roboczej narzędzi formujących brykieciarek walcowych. Narzędzia te stanowią zasadniczy element określający możliwości stosowania i eksploatacji tych urządzeń. Właściwy wybór rodzaju i kształtu wgłębień formujących oraz sposobu ich rozmieszczenia, czyli ukształtowanie powierzchni roboczej ma istotny wpływ na proces zagęszczania i scalania materiałów drobnoziarnistych. Wybór tworzywa konstrukcyjnego oraz odpowiednich metod jego obróbki, a także technika wykonywania wgłębień formujących decydują o eksploatacji i trwałości narzędzi i prasy oraz o prawidłowym przebiegu procesu brykietowania. Przedstawiono również podstawy geometrycznego kształtowania wgłębień formujących i ich rozmieszczenia na walcowej powierzchni elementu formującego, tzn. pierścienia, walca lub segmentu. Rozważono przypadek podstawowy, tzn. brykiet w kształcie "poduszki" z płaszczyzną podziału.
Some of the factors affecting the shaping of the cylindrical working surface of tools (i.e. rings) used in roller-presses for briquetting are presented. These tools are an essential element in determining the applicability and operation of these devices. They often suffer heavy abrasive wear, and they are highly mechanically loaded. The appropriate choice of the type and shape of the mould cavities (pockets) and how they are deployed, that is the shaping the working surface, has a significant influence on the process of compaction and consolidation of fine-grained materials. Choosing material for forming rolls (rings, segments, or cylinder) and corresponding methods of treatment and exercise technique cavities forming operation determine the tool life and the press and smooth the process of briquetting. The article also presented a simplified method of shaping and placement of pockets on the cylindrical surface of the ring, cylinder, or a segment. Considered is the basic case, i.e. briquette plane of division.
Źródło:
Problemy Eksploatacji; 2010, 2; 149-157
1232-9312
Pojawia się w:
Problemy Eksploatacji
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mathematical model of piston ring sealing in combustion engine
Autorzy:
Koszałka, G.
Guzik, M
Powiązania:
https://bibliotekanauki.pl/articles/258834.pdf
Data publikacji:
2014
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
exhaust gas blow-by
displacements of rings
twisting of rings
oil film
cylinder
piston
ring
mathematical model
lubrication
Opis:
This paper presents a mathematical model of piston-rings-cylinder sealing (TPC) of a combustion engine. The developed model is an itegrated model of gas flow through gaps in TPC unit , displacements and twisting motions of piston rings in ring grooves as well as generation of oil film between ring face surfaces and cylinder liner. Thermal deformations and wear of TPC unit elements as well as heat exchange between flowing gas and surrounding walls , were taken into account in the model. The paper contains descriptions of: assumptions used for developing the model , the model itself, its numerical solution as well as its computer application for carrying out simulation tests.
Źródło:
Polish Maritime Research; 2014, 4; 66-78
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Noethérianité de certaines algèbres de fonctions analytiques et applications
Autorzy:
Elkhadiri, Abdelhafed
Hlal, Mouttaki
Powiązania:
https://bibliotekanauki.pl/articles/1207892.pdf
Data publikacji:
2000
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
Nash functions
regular rings
analytic algebra
subanalytic sets
Opis:
Let $M ⊂ ℝ^{n}$ be a real-analytic submanifold and H(M) the algebra of real analytic functions on M. If K ⊂ M is a compact subset we consider $S_{K}={f ∈ H(M)| f(x) ≠ 0 \ \text{for all} \ x ∈ K}$; $S_{K}$ is a multiplicative subset of $H(M)$. Let $S_{K}^{-1}H(M)$ be the localization of H(M) with respect to $S_{K}$. In this paper we prove, first, that $S_{K}^{-1}H(M)$ is a regular ring (hence noetherian) and use this result in two situations:
   1) For each open subset $Ω ⊂ ℝ^{n}$, we denote by O(Ω) the subalgebra of H(Ω) defined as follows: f ∈ O(Ω) if and only if for all x ∈ Ω, the germ of f at x, $f_{x}$, is algebraic on $H(ℝ^{n})$. We prove that if Ω is a bounded subanalytic subset, then O(Ω) is a regular ring (hence noetherian).
   2) Let $M ⊂ ℝ^{n}$ be a Nash submanifold and N(M) the ring of Nash functions on M; we have an injection N(M) → H(M). In [2] it was proved that every prime ideal p of N(M) generates a prime ideal of analytic functions pH(M) if M or V(p) is compact. We use our Theorem 1 to give another proof in the situation where V(p) is compact. Finally we show that this result holds in some particular situation where M and V(p) are not assumed to be compact.
Źródło:
Annales Polonici Mathematici; 2000, 75, 3; 247-256
0066-2216
Pojawia się w:
Annales Polonici Mathematici
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nowe biodegradowalne pierścienie do zespalania jelita grubego
New biodegradable rings for large intestine integration
Autorzy:
Drop, R.
Mazurkiewicz, S.
Szaraniec, B.
Woźny, Z.
Gryń, K.
Cygan, R.
Powiązania:
https://bibliotekanauki.pl/articles/285186.pdf
Data publikacji:
2013
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Polskie Towarzystwo Biominerałów
Tematy:
implanty
biomateriały
pierścienie zespalające
implants
biomaterials
biodegradable rings
Opis:
Próby łączenia jelit za pomocą implantów sięgają początków XIX w, kiedy to opracowane zostały pierwsze pierścienie zespalające przez Denansa (1827) i Henroza (1826). Kolejna konstrukcja zaproponowana przez Murphyego, tzw. guzik Murphyego, stała się inspiracją dla komercyjnych implantów, ulegających fragmentacji pierścieni Valtrac® (Biofragmentable Anastomotic Ring) do zespoleń jelitowych, których produkcję w latach osiemdziesiątych XX wieku rozpoczęła firma Davis & Geck. Równocześnie rozwijane były techniki zespalania jelit za pomocą staplerów (Hültl 1908, Petz 1924, Androsov 1950), które również w latach osiemdziesiątych XX wieku stały się jednym ze standardów postępowania w chirurgii jelita grubego. Prace nad opracowaniem skutecznego, łatwego w aplikacji i ulegającego w pełni biodegradacji implantu do zespoleń jelit nadal trwają. Zakładają one dążenie do możliwie najmniejszego uszkodzenia tkanek, zapewnienia szczelności zespolenia i odpowiedniej wielkości jego światła, przy zachowaniu prawidłowego ukrwienia i niewywoływaniu nadmiernego napięcia w jelitach. Jedną z propozycji nowoczesnego rozwiązania problemu związanego z zespalaniem jelita grubego może stanowić w pełni biodegradowalny układ pierścieni wykonany z poliestrów alifatycznych mocowanych bezszwowo. Aplikacja pierścieni zakłada odwinięcie zespalanych części jelita na zewnątrz jego światła, a następnie ich połączenie przez docisk dzięki odpowiedniemu systemowi blokującemu. Prototypy implantów do zespalania jelit otrzymano metodą wtrysku przy użyciu wtryskarki ślimakowej Multiplas. Temperatura wtrysku wynosiła 160-170°C, a ciśnienie w układzie 60-90 kg/cm2. Prototypy implantów wykonano z polimeru resorbowalnego - polilaktydu PLA firmy NatureWork, USA (PLA Ingeo 3251D). Pierwsze doświadczenia prowadzone in vitro i in vivo wskazują, że wykonane implanty mogą z powodzeniem spełniać wspomniane powyżej założenia i dodatkowo dzięki łatwej aplikacji znacznie skrócić czas trwania operacji. Zaproponowana konstrukcja układu pierścieni oraz właściwości fizyko-mechaniczne zastosowanego materiału polimerowego pozwoliły w prosty sposób zespolić jelito uzyskując jednakowy regulowany docisk na jego obwodzie.
The attempts at integrating intestines by means of implants date back to the beginning of the 19th century, when integrating rings were developed by Denans (1827) and Henroz (1826). Another construction, proposed by Murphy, the, so called, Murphy’s button, became an inspiration for commercial implants – the Valtrac® fragmentable rings (Biofragmentable Anastomotic Rings) for intestine integration, whose production was initiated in 1980s by Davis & Geck. Simultaneously developed were techniques of intestine integration with the use of staplers (Hültl 1908, Petz 1924, Androsov 1950), which, also in the 1980s, became one of the standards for large intestine surgery procedures. Works on the development of an effective, easily applicable and fully biodegradable implant for intestine integration are still being conducted. The main goal, providing a minimal tissue damages, is to obtain a leakproof anastomosis with a proper size of its inner diameter along with the preservation of the adequate blood supply and no excessive tensions in the intestines. One of the proposals of a modern solution to the problem connected with large intestine integration can be a fully biodegradable system of rings made of seamless-mounted aliphatic polyesters. The applying procedure assumes turning parts of the intestine, which are meant to be integrated, inside-out and stretching their edges on the rings. Next, rings are joined together by pressing them “face to face” and locking with the appropriate seamless blocking system. Prototypes of large intestine integration implants were obtained by the injection moulding (screw injection moulding machine Multiplas). The injection temperature was 160-170°C and the pressure in the system was 60-90 kg/cm2. The implant prototypes were prepared from a polymer – the PLA polylactide by NatureWork, USA (PLA Ingeo 3251D). The initial in vitro and in vivo experiments show that the elaborated implants can successfully meet the above mentioned assumptions and, additionally, because of their easy application, significantly shorten the time of the surgical procedure. The proposed construction of the ring system and the physico-mechanical properties of the applied polymer material made it possible to easily integrate the intestine and achieve a similar, regulated, pressure on its circumference.
Źródło:
Engineering of Biomaterials; 2013, 16, no. 122-123 spec. iss.; 56-57
1429-7248
Pojawia się w:
Engineering of Biomaterials
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
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