Wszystkie pola: Georgiev, G. - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: Hardness investigation of conventional, bulk fill and flowable dental composites
Autorzy:: Georgiev, G.
Dikova, T.
Powiązania:: https://bibliotekanauki.pl/articles/2055754.pdf
Data publikacji:: 2021
Wydawca:: Stowarzyszenie Komputerowej Nauki o Materiałach i Inżynierii Powierzchni w Gliwicach
Tematy:: resin-based composites
micro-hardness
light intensity
irradiation time
layer thickness
kompozyty żywiczne
mikrotwardość
natężenie oświetlenia
czas nasłonecznienia
grubość warstwy
Opis:: Purpose: of the present paper is to investigate the micro-hardness of three types of resin-based composites – conventional, bulk fill and flowable. Design/methodology/approach: Cylindrical specimens with a diameter of 5 mm and thicknesses of 2, 3 and 4 mm were made from each composite. They were light cured for 20, 40 and 60 s with light intensity of 600, 1000 or 1500 mW/cm2. The Vickers micro-hardness was measured on the top and bottom surface of the specimens. Findings: The highest micro-hardness was measured in bulk fill composite, followed by conventional and the lowest was measured in the flowable one. Increasing the light intensity leads to increase of the micro-hardness on both surfaces of the three composites. The increase of the irradiation time results in increase of the micro-hardness mainly on the bottom surface of the composites. The change of the layer thickness influences the conventional and the flowable composites and almost does not affect the hardness of the bulk fill composite. Research limitations/implications: The limitations of this study concerns to the values of the light intensity, which are defined by the light curing unit (LCU) used. There are many LCUs on the market; consequently, constant investigations of dental composites micro-hardness are needed. Practical implications: The investigation of the micro-hardness of the three types of composites in different modes would be very helpful for clinicians to obtain successful polymerization of composite restorations in their everyday practice. Originality/value: The micro-hardness of three types resin-based dental composites – conventional, bulk fill and flowable is investigated and compared in varying of three mode parameters – light intensity, curing time and layer thickness.
Źródło:: Journal of Achievements in Materials and Manufacturing Engineering; 2021, 109, 2; 68--77
1734-8412
Pojawia się w:: Journal of Achievements in Materials and Manufacturing Engineering
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Phase Shifter Operation of the Azimuthally Magnetized Coaxial Ferrite Waveguide
Autorzy:: Georgieva-Grosse, M.
Georgiev, G.
Powiązania:: https://bibliotekanauki.pl/articles/1419702.pdf
Data publikacji:: 2012-07
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:: 02.60.Lj
02.90.+p
41.20.-q
41.20.Jb
85.70.Ge
Opis:: The terms for operation of the coaxial waveguide, entirely filled with azimuthally magnetized latching ferrite, as a digital nonreciprocal phase shifter for the normal $TE_{01}$ mode, are found. They are classified as physical, mathematical and functional ones. The physical prerequisites are drawn from the phase curves of the structure and specify the boundaries of the interval in which it produces differential phase shift for a given numerical equivalent of the modulus of off-diagonal ferrite permeability tensor element. The mathematical condition brings the parameters of configuration together with certain roots of its characteristic equation, derived in terms of complex Kummer and Tricomi confluent hypergeometric functions and with the related to them positive real $L_2(c,ρ,n)$ numbers (c=3, 0<ρ<1, n=1). The functional criteria determine the borders of the domain of phase shifter operation of the geometry. These are functions, defined for a fixed central conductor thickness which express in normalized form the impact of the guide radius on the phase shift at the cut-off frequencies and at the envelopes, denoting the termination of the phase curves for negative ferrite magnetization from the side of higher frequencies. The same are reckoned, employing iterative methods, consisting in a repeated numerical solution of the equation mentioned, followed by a computation of the guide radius and phase constant of the wave and are plotted graphically. The influence of the parameters of transmission line on the area referred to is analyzed.
Źródło:: Acta Physica Polonica A; 2012, 122, 1; 63-70
0587-4246
1898-794X
Pojawia się w:: Acta Physica Polonica A
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: The Kummer confluent hypergeometric function and some of its applications in the theory of azimuthally magnetized circular ferrite waveguides
Autorzy:: Georgiev, G. N.
Georgieva-Grosse, M. N.
Powiązania:: https://bibliotekanauki.pl/articles/309046.pdf
Data publikacji:: 2005
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: microwave propagation in anisotropic media
microwave guides and components
ferrite phase shifters
switches
isolators
eigenvalue problems
function-theoretic and computational methods in electromagnetic theory
theoretical and numerical analysis of special functions
Opis:: Examples of the application of the confluent hypergeometric functions in miscellaneous areas of the theoretical physics are presented. It is suggested these functions to be utilized as a universal means for solution of a large number of problems, leading to: cylindrical, incomplete gamma, Coulomb wave, Airy, Kelvin, Bateman, Weber's parabolic cylinder, logarithmic-integral and exponential integral functions, generalized Laguerre, Poisson-Charlier and Hermit polynomials, integral sine and cosine, Fresnel and probability integrals, etc. (whose complete list is given), which are their special cases. The employment of such an approach would permit to develop general methods for integration of these tasks, to generalize results of different directions of physics and to find the common features of various phenomena, governed by equations, pertaining to the same family. Emphasis is placed here on the use of the Kummer function in the field of microwaves: the cases of normal and slow rotationally symmetric TE modes propagation in the azimuthally magnetized circular ferrite waveguide are considered. Lemmas on the properties of the argument, real and imaginary parts, and positive purely imaginary (real) zeros of the function mentioned in the complex (real) domain, of importance in the solution of boundary-value problem stated for normal (slow) waves, are substantiated analytically or numerically. A theorem for the identity of positive purely imaginary and real zeros of the complex respectively real Kummer function for certain parameters, is proved numerically. Tables and graphs support the results established. The terms for wave transmission are obtained as four bilaterally open intervals of variation of the quantities, specifying the fields. It turns out that the normal (slow) modes may exist in one (two) region(s). The theoretically predicted phase curves for the first waves of the two TE sets examined show that the structure explored is suitable for ferrite control components design.
Źródło:: Journal of Telecommunications and Information Technology; 2005, 3; 112-128
1509-4553
1899-8852
Pojawia się w:: Journal of Telecommunications and Information Technology
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Tandonia totevi (Wiktor, 1975) (Pulmonata: Milacidae) in Bulgaria and north eastern Greece. Redescription
Autorzy:: Schneppat, U.E.
Georgiev, D.G.
Dedov, I.K.
Wondrak, G.
Knechtle, F.
Powiązania:: https://bibliotekanauki.pl/articles/83237.pdf
Data publikacji:: 2011
Wydawca:: Uniwersytet Mikołaja Kopernika. Wydział Biologii i Ochrony Środowiska. Stowarzyszenie Malakologów Polskich
Tematy:: Tandonia totevi
Pulmonata
Milacidae
Bulgaria
Greece
slug
anatomy
redescription
biogeography
ecology
Peloponnese
Opis:: New materials of Tandonia totevi (Wiktor, 1975) from Bulgaria have enabled the authors to prepare a detailed redescription and to distinguish the species from those from southern Greece which have been confused with T. totevi for almost 30 years. From the southern Greek Islands, the Peloponnese and the island of Euboea at least three more species need to be described and discriminated from T. totevi. The spermatophores of T. totevi from Bulgaria are described here for the first time, as is an intra-integumental glandular secreting organ of unknown function. The first description of spermatozoa of T. totevi is included. The first photographs of living specimens and the first observations on the behaviour and ecology are provided.
Źródło:: Folia Malacologica; 2011, 19, 4
1506-7629
Pojawia się w:: Folia Malacologica
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Microwave radiometry in monitoring and emergency mapping of water seepage and dangerously high groundwaters
Autorzy:: Shutko, A. M.
Haldin, A.
Krapivin, V.
Novichikhin, E.
Sidorov, I.
Tishchenko, Y.
Haarbrink, R.
Georgiev, G.
Kancheva, R.
Nikolov, H.
Coleman, T.
Archer, F.
Pampaloni, P.
Paloscia, S.
Krissilov, A.
Camps Carmona, A.
Powiązania:: https://bibliotekanauki.pl/articles/307666.pdf
Data publikacji:: 2007
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: remote sensing
passive microwave radiometry
soil moisture
water seepage
risk assessment
Opis:: Detailed and geo-referenced maps identifying the locations of saturated and dry levees can be produced using microwave radiometric measurements from a light aircraft or helicopter, and integrated with GPS for positioning and orientation. The development of synergetic remote sensing technology for raised groundwater and seepage detection by the joint use of microwave and optical data along with GIS databases is an effective and most contemporary way of supporting risk assessment and facilitating disaster prevention and management. In this paper we present a remote sensing microwave technology for monitoring and detection of areas of water seepage through irrigation constructions, levees and dykes as well as for revealing areas with dangerously high groundwater level. The possibility for emergency response mapping, integrated with GPS and GIS data, facilitates the risk assessment and management services. The passive microwave radiometry (PMR) is based on spectral measurements in the millimetre to decimetre range of wavelengths. Compared to other remote sensing techniques, such as colour and infrared photography, thermal images and lidar, PMR is the only technology taking measurements under the earth's surface and therefore is very well suited for water seepage and underground water monitoring in a fast and reliable way.
Źródło:: Journal of Telecommunications and Information Technology; 2007, 1; 76-82
1509-4553
1899-8852
Pojawia się w:: Journal of Telecommunications and Information Technology
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Chromatography analysis of seminal plasma proteins in buffalo semen samples with high and low cryotolerance
Autorzy:: Ivanova, M.G.
Gradinarska, D.G.
Tsvetkov, T.S.
Kirilova, I.V.
Georgiev, B.A.
Powiązania:: https://bibliotekanauki.pl/articles/2087567.pdf
Data publikacji:: 2019
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: buffalo
seminal plasma proteins
cryotolerance
HPLC
Źródło:: Polish Journal of Veterinary Sciences; 2019, 1; 11-16
1505-1773
Pojawia się w:: Polish Journal of Veterinary Sciences
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: An experimental research on the wear of truck tire
Экспериментальное исследование износа шин грузового автомобиля
Autorzy:: Ivanov, R.
Georgiev, K.
Kadikyanov, G.
Staneva, G.
Powiązania:: https://bibliotekanauki.pl/articles/375080.pdf
Data publikacji:: 2015
Wydawca:: Politechnika Śląska. Wydawnictwo Politechniki Śląskiej
Tematy:: tire wear
experimental research
truck tire
tire
zużycie opon
badania eksperymentalne
opony do ciężarówek
ciężarówka
Opis:: An experimental device and methodology for tire wear investigation are presented. An indirect method for wear evaluating is used. The experimental results in cases of straight motion with and without side slip are obtained. The distribution of wearing on tread pattern wide is evaluated in different running conditions.
Передставлены экспериментальная установка и методика оценки износа шин. Использован косвенный метод оценки износа. Получены экспериментальные результаты при движении при наличии и отсутствии бокового увода. Сделана оценка неравномерности износа по ширине шины при разных условиях движения.
Źródło:: Transport Problems; 2015, 10, 4; 91-98
1896-0596
2300-861X
Pojawia się w:: Transport Problems
Dostawca treści:: Biblioteka Nauki

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