Autor: Dimitrov, V. - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Ground State and Magnetostatic Properties of a Dipole System Arranged in Two-Dimensional Lattice
Autorzy:: Bolcal, E.
Dimitrov, V.
Aktaş, B.
Aslan, H.
Bozkurt, A.
Tematy:: 75.10.-b; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1491456.pdf Link otwiera się w nowym oknie
Opis:: A system of nano sized modomain ferromagnetic particle arranged in two-dimensional lattice is theoretically investigated. The basic aim of the investigation is to find the ground state of these types of models where the interaction is long-ranged and anisotropic. The numerical calculations show that for some lattices there is a number of degenerated states near the zero temperature. The ground state of these systems is basically of a complicated antiferromagnetic type.
Dostawca treści:: Biblioteka Nauki

Artykuł

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Skocz do pozycji: 2.

Tytuł:: Biomass of the xerothermic oak ecosystem on a site of community importance, BG0001040 "Zapadna Stara Planina i Predbalkan", Bulgaria
Autorzy:: Lyubenova, M.
Dimitrova, V.
Georgieva, N.
Dimitrov, D.
Tematy:: biomass
xerothermic plant
forest ecosystem
oak
plant community
Quercus frainetto-Quercus cerris forest
Zapadna Stara Planina i Predbalkan area
Natura 2000 area
Bulgaria; Pokaż więcej
Wydawca:: Sieć Badawcza Łukasiewicz - Instytut Technologii Drewna
Powiązania:: https://bibliotekanauki.pl/articles/52482.pdf Link otwiera się w nowym oknie
Opis:: The belowground and aboveground biomass was estimated for the tree story, sproutsand seedling regeneration in a representative Quercus frainetto – Quercus cerris ecosystem on “Zapadna Stara planina i Predbalkan”, a Site of Community Importance (SCI). The biomass was measured by destructive sampling (on sample or “model trees” representing three calculated density classes for each species and cut at the stump) of leaves, annual and perennial branches, wood, bark and root components. The belowground (root) biomass was also calculated from a subsample. The data obtained were compared to the results of previous studies and the values on the Bazilevich and Rodin [1971] scale. The ecological status of the forest ecosystem studied and its functional efficiency are discussed based on the study results and specific climate data.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Introducing new engine performance lab at the Department of Motor Vehicles and Combustion Engines of Wroclaw University of Technology
Nowa pracowania badań obciążeniowych w Zakładzie Pojazdów Samochodowych i Silników Spalinowych Politechniki Wrocławskiej
Autorzy:: Haller, P.
Wróbel, R.
Dimitrov, R.
Mihaylov, V.
Tematy:: emission testing
emission test methods
engine test house
pomiary emisji
testy emisji spalin
hamownia podwoziowa; Pokaż więcej
Wydawca:: Polskie Towarzystwo Naukowe Silników Spalinowych
Powiązania:: https://bibliotekanauki.pl/articles/133385.pdf Link otwiera się w nowym oknie
Opis:: The Engine Test Stand is a measuring position providing wide range of features, enabling data acquisition, used to determine specific engine performance characteristics. Chassis dynamometers are more convenient and easier to operate (engine removal from a car is not required). At the same time, precision and accuracy as well as reproducibility of measurements remain high. Measurement lab at The Motor Vehicles and Combustion Engines Institute at Wroclaw University of Technology enables sophisticated diagnosis of all types of passenger cars and motorcycles. The station in our lab is capable of conducting the exhaust gas emission analysis of leaded petrol engines under specific load or with no load at all. In case of passenger cars equipped with a catalytic converter and lambda sensor, it is not only crucial to adjust the emission levels but also determine the lambda sensor values and oxygen content in the exhaust stream. What’s more important, the measurement process can be followed online which facilitates team work and delivers substantial speed ups.
Hamownia jest stacjonarnym stanowiskiem pomiarowym umożliwiającym pozyskanie niezbędnych danych do wyznaczenia charakterystyki silnika. W przeciwieństwie do hamowni silnikowych, hamownie podwoziowe są proste i szybkie w obsłudze (nie trzeba wyjmować silnika), a jednocześnie ich precyzja pomiaru parametrów pojazdu jest wysoka, podobnie jak powtarzalność przeprowadzanych testów. Stanowisko badawcze w Zakładzie Pojazdów Samochodowych i Silników Spalinowych Politechniki Wrocławskiej oferuje za pośrednictwem swego programu do symulacji obciążeń idealną bazę do diagnostyki wszystkich typów samochodów osobowych oraz motocykli pod obciążeniem. Możliwe jest również dokonania analizy spalin pojazdów zasilanych etyliną bez obciążenia lub pod obciążeniem. W samochodach osobowych z katalizatorem i sonda lambdą ważne jest nie tylko ustawienie wartości emisyjnych, ale też określenie wartości lambda i zawartości tlenu. A co najważniejsze pomiary mogą być podglądane w trybie online, co ułatwia i przyspiesza pracę zespołową zakładu.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Książka = Book ; KS/4/2012/P20
New developments in fuzzy sets, intuitionistic fuzzy sets, generalized nets and related topics. Volume II: applications * Generalized net model of the students’ knowledge assessments using self organizing map with intuitionistic fuzzy estimations
Autorzy:: Bineva, V.
Sotirova, Evdokia
Gordon, C.
Jonova, I.
Dimitrov, Ivan
Sotirov, Sotir
Wydawca:: Instytut Badań Systemowych. Polska Akademia Nauk
Systems Research Institute. Polish Academy of Sciences
Powiązania:: Książka = Book
Opis:: [5], 235-242 stron ; 21 cm
Bibliografia s. 240-242
[5], 235-242 pages ; 21 cm
The paper presents a generalized net model of the Self Organizing Map (SOM) that evaluates the students’ answers based on defined set criterions. To be involved in practice there are used evaluation in intuitionistic fuzzy form about the students’ knowledge. This is proper to be used as a basic element for e-learning systems’ building.
Bibliography p. 240-242
Dostawca treści:: RCIN - Repozytorium Cyfrowe Instytutów Naukowych

Książka

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Skocz do pozycji: 5.

Tytuł:: Adaptive potential and productivity of two Salix viminalis L. clonal varieties grown in North Central Bulgaria
Autorzy:: Stankova, T.
Gyuleva, V.
Tsvetkov, I.
Popov, E.
Kalmukov, K.
Dimitrov, D.N.
Andonova, E.
Stefanova, P.
Tematy:: basket willow
spacing
rotation
allometry
site conditions; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Dendrologii PAN
Powiązania:: https://bibliotekanauki.pl/articles/2130197.pdf Link otwiera się w nowym oknie
Opis:: Salix viminalis L. is a broadly cultivated willow species that has been intensively used for breeding purposes, particularly in selection of clones and hybrids for biomass production. The present study aimed to explore and compare growth and adaptability of two basket willow (Salix viminalis L.) clonal varieties - rubra and purpurea - at the specific edaphic and climate conditions and cultivation practice presented in an experimental plantation in North Central Bulgaria. The influence of spacing, genotype, root age and rotation on their productivity were also investigated and allometric relationships for non-destructive estimation of woody plant biomass were suggested. The trial plantation was established in the spring of 2018 as 4 sectors of a Nelder wheel plot with 15 nearly-square spacings, ranging from 0.25 to 9.80 m2 (40000–1020 plants per hectare). The two varieties were arranged in 4 four-spoke sectors (2 sectors per clone). Data collection took place from 2018 to 2020 and comprised 1- and 2-year rotations. The study showed that Salix viminalis var. rubra was more susceptible to desiccation-causing adverse climatic changes, poorly adapted to the specific conditions of the study site and gradually died out during the second and the third year. Salix viminalis var. purpurea exhibited steady survival rate (97 - 77%) and annual biomass productivity varying from 3 to 17 Mg/ha/year across the densities, sectors and years. During the first year of growth purpurea variety had a significantly higher plant weight and sprout number than rubra variety. Growing space affected positively the number of shoots and tree dendromass, and sprouting was reinforced by coppicing that doubled the shoot number during the subsequent rotation. This was reflected in the development of the stump-level allometric models that were differentiated according to rotation. The stump-level allometric model of higher predictive power was based on the main shoot length and shoot number. An exponential relationship to the breast-height shoot diameter was also suggested for biomass estimation of each sprout separately.
Dostawca treści:: Biblioteka Nauki

Artykuł

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Skocz do pozycji: 6.

Tytuł:: Element enrichment and provenance of the detrital component in Holocene sediments from the Western Black Sea
Autorzy:: Dekov, V.M.
Darakchieva, V.Y.
Billstrom, K.
Garbe-Schonberg, C.D.
Kamenov, G.D.
Gallinari, M.
Dimitrov, L.
Ragueneau, O.
Kooijman, E.
Tematy:: trace element concentration
isotope analysis
enrichment factor
Holocene sediment
catchment area
geochemical analysis
Black Sea; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Oceanologii PAN
Powiązania:: https://bibliotekanauki.pl/articles/2079273.pdf Link otwiera się w nowym oknie
Opis:: Concentrations of a large set of major and trace elements, and Sr, Nd and Pb isotope ratios were measured in Holocene sediments cored in the western deep Black Sea in order to unravel: (1) the controls of element enrichment, and (2) sources of the detrital component. The transition of the basin from oxic to euxinic resulted in enrichment or depletion in a number of elements in the deep-sea sediments. Authigenic Fe enrichment appears to depend on the amount of Fe mobilized from the sediment through the benthic redox shuttle mechanism and free H2S in the water column (degree of “euxinization”). Manganese enrichment is controlled by diagenetic reactions within the sediment: the dissolution of Mn minerals, Mn2+ diffusion upward and reprecipitation. Barium enrichment is also controlled by diagenetic reactions, sulfate reduction and methanogenesis, that take place above and below the sulfate-methane transition, respectively. The major part of V, Co, Ni, Cu, Zn, Cr, Mo, Cd and Sb is inferred to have co-precipitated with Fe in the euxinic deep waters and to have been incorporated into authigenic Fe-sulfides. Basin reservoir effect additionally influences the Mo enrichment. The U enrichment is interpreted to have a different origin in the two organic-rich stratigraphic units (II and I). It is inferred to be: (i) at the expense of the U inventory of the deepwater pool and a result of inorganic reduction of U at euxinic conditions in the lower Unit II; and (ii) at the expense of the U inventory of the surface water pool and a result of biogenic uptake and transfer to the sediment by the plankton in the upper Unit I. The high field strength elements are closely linked to the detrital component and their depletion in the organic-rich sediments reflects a dilution of the detrital component by the biogenic one. The enrichments of REE, Sn and Th are likely controlled by adsorption on clay minerals. Sr-Nd-Pb isotope compositions of the alumino-silicate component of the studied sediments are relatively uniform. They are most likely controlled by riverine suspended matter supplied mainly in the NW Black Sea (Danube Delta) and transported southward by marine currents, and to a lesser degree by suspended matter from the small rivers draining SE Bulgaria and NW Turkey. Wind-blown dust from the Sahara Desert appears to have a minor contribution to the alumino-silicate component of the sediments. The slight shift in the Pb isotopes in Unit I upper layers is possibly caused by the addition of anthropogenic Pb.
Dostawca treści:: Biblioteka Nauki