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Wyszukujesz frazę "Zieliński, J." wg kryterium: Autor


Tytuł:
Analysis and Comparison of the Fade Phenomenon in the SFN DAB+ Network With Two and Three Transmitter
Autorzy:
Zielinski, Ryszard J.
Powiązania:
https://bibliotekanauki.pl/articles/226043.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
single-frequency network
fades
DAB+
Opis:
Single Frequency Networks (SFN) of transmitters are currently used in television and digital broadcasting to effectively cover large areas using minimal spectral resources and using transmitters with much lower power than if the same area were covered using one transmitter. It is therefore a very ecological solution. In this way, much better reception conditions are obtained in large city areas, as the signal reaches the receiving antenna from different directions, reducing the risk of shading. However, in this type of network one should take into account the loss of signal caused by signal interference. Using the appropriate propagation model, it is possible, with appropriate assumptions, to check how the operation of the third transmitter affects the distribution and size of the deepest fades in relation to the network in which there are two transmitters.
Źródło:
International Journal of Electronics and Telecommunications; 2020, 66, 1; 85-92
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Frequency Dependent Mismatch Correction Scheme for Zero-IF Receivers
Autorzy:
Hibner, R.
Zieliński, R. J.
Powiązania:
https://bibliotekanauki.pl/articles/226210.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
zero-IF
ZIF
compensation
quadrature
IQ
wideband
dynamic range
image correction
Opis:
This paper shows effective method of linear distortions compensation in zero-IF receivers. With application of frequency domain processing a computation efficient method was developed that allows to correct quadrature mismatch in Zero-IF receiver along with gain and group delay independent of receiving signal type. Method was implemented and tested on hardware platform confirming its effectiveness. This method makes it possible to build high sensitivity devices to monitor spectrum in very wide frequency ranges.
Źródło:
International Journal of Electronics and Telecommunications; 2018, 64, 1; 13-18
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Verification Methodology of Fade Characteristics in a DAB+ SFN in Wroclaw
Autorzy:
Michalski, Igor
Zielinski, Ryszard J.
Powiązania:
https://bibliotekanauki.pl/articles/1844537.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
frequency network
SFN
DAB+
fade characteristics
fade measurements
Opis:
The article presents the methodology for measuring verification of the phenomenon of fades in the DAB+ SFN. The verification is related to comparing the characteristics of the fades determined theoretically with the occurring fades in the real environment of a large city. The conditions favorable for the occurrence of fading are presented and by selecting the appropriate propagation analysis tool, the places where the occurrence of fading is most likely were selected. In these places an analysis of the characteristics of fades was carried out and the conditions for their verification were determined.
Źródło:
International Journal of Electronics and Telecommunications; 2021, 67, 3; 537-542
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Measurement of Special Shielding Materials at S and C Band Using Improved Free-Space Transmission Technique
Autorzy:
Dvurechenskaya, N.
Zieliński, R. J.
Powiązania:
https://bibliotekanauki.pl/articles/226270.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
nonwoven
fabric
shielding effectiveness
freespace measurements
surface resistivity
Opis:
In this paper we discuss state of the art in the field of shielding materials investigation. Two types of newly manufactured shielding materials (nonwoven and fabric) were measured using improved free-space transmission technique at 2-5 GHz depending on electromagnetic wave (EM) polarization and antenna to specimen distance. Results of shielding effectiveness (SE) evaluation based on measured complex transmission coefficients (S21) were presented and compared with SE measured using coaxial transmission line technique. Also results of surface resistance measurements with the four-probe technique for the test materials are shown.
Źródło:
International Journal of Electronics and Telecommunications; 2011, 57, 3; 329-334
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
High Altitude Platform : Future of Infrastructure
Autorzy:
Malinowski, A.
Zieliński, R. J.
Powiązania:
https://bibliotekanauki.pl/articles/226948.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
HAP
High Altitude Platform
rural area
infrastructure
Opis:
High Altitude Platform (HAP) concept and idea is presented in the article. Characteristics, advantages and disadvantages of HAPs are described. There is also the comparison available between HAPs and existing telecommunication infrastructure (terrestrial and satellite). Selected examples of the possible limitation and technological restrictions of HAP based systems are presented in the article.
Źródło:
International Journal of Electronics and Telecommunications; 2010, 56, 2; 191-196
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Simulation Model of the Radio Frequency MIMO-OFDM System
Autorzy:
Kowal, M.
Kubal, S.
Piotrowski, P.
Zieliński, R. J.
Powiązania:
https://bibliotekanauki.pl/articles/226276.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
MIMO-OFDM
Simulink
simulator
Opis:
The paper presents a simulation model of the radio frequency MIMO-OFDM system. The simulation model was made in Matlab Simulink environment. It contains the transmitter, the receiver and the telecommunication channel models. The telecommunication channel model consists of models used during development of technical documentation of IEEE 802.11n. Signals generated at the transmitter output are fully compatible with signals described in IEEE 802.11n [1]. Simulations are conducted on a radio frequency, so they can be compared with results of measurements of real systems.
Źródło:
International Journal of Electronics and Telecommunications; 2011, 57, 3; 323-328
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Operational characteristic of wireless WiMax and IEEE 802.11x systems in underground mine environments
Autorzy:
Kowal, M.
Kubal, S.
Piotrowski, P.
Zieliński, R. J.
Powiązania:
https://bibliotekanauki.pl/articles/227021.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
WLAN
WiMAX
throughput
delay
mine environment
Opis:
The paper presents research results pertaining to transmission parameters of wireless communication systems, based on WiMax and IEEE 802.11x radio interfaces. Research was performed in severe operating conditions of an underground mine - testing various parameters, such as: throughput, delays and maximum range.
Źródło:
International Journal of Electronics and Telecommunications; 2010, 56, 1; 81-86
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Measurements of shielding effectiveness of textile materials containing metal by the free-space transmission technique with data processing in the time domain
Autorzy:
Dvurechenskaya, N.
Bajurko, P. R.
Zieliński, R. J.
Yashchyshyn, Y.
Powiązania:
https://bibliotekanauki.pl/articles/221789.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
textiles
shielding effectiveness
free-space transmission technique
time-domain gating
Opis:
The results of shielding effectiveness (SE) measurements of textile materials containing metal by the free-space transmission technique (FSTT) in the 1-26.5 GHz frequency range are presented in the paper. It is shown that experimental data processing using time-domain gating (TDG) makes it possible to effectively remove diffracted and reflected components from the desired signal. The comparison with the results obtained by other techniques, namely modified FSTT with TDG and coaxial line probe technique (ASTM D4935-99) is given. The comparison shows that the proposed technique gives more reasonable results while the measurement set-up is simpler in realization.
Źródło:
Metrology and Measurement Systems; 2013, 20, 2; 217-228
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A combined numerical-experimental model of air foil bearing compliant structure
Autorzy:
Łagodziński, J.
Zieliński, P.
Powiązania:
https://bibliotekanauki.pl/articles/175400.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
airfoil bearing
numerical model
gas bearing coefficients
Opis:
The paper concerns the development process of numerical-experimental model of air foil bearing compliant structure. Theoretically, static and dynamic characteristics of the foil bearing are the result of elastic combined properties of the two serially connected elements. One of them is a thin gas film of very small thickness and relatively high static and dynamic stiffness. The second elastic element is a pretensioned bump foil spring. This paper focuses on the properties of compliant foil structure and leaves aside the gas film behavior. At the beginning of the model development, the global stiffness and damping properties of compliant structure were obtained from the test stand measurements. In the next step, some assumptions concerning the model were made. The main one was the replacememy of the single bumps of the corrugated foil by the set of elastic-damping numerical elements. At last, the fine-tuning of the model was carried out. The tuning involved changing of subelements local damping and stiffness properties, which in effect influenced the global properties of foil bearing. The tuning criterion for the model was defined as follows: the bearing global stiffness and damping properties of the model should not differ from the experimentally obtained values more than 10%.
Źródło:
Transactions of the Institute of Fluid-Flow Machinery; 2016, 133; 117-129
0079-3205
Pojawia się w:
Transactions of the Institute of Fluid-Flow Machinery
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Durability and narrow pore size distribution (PSD) of carbons fabricated from Salix Viminalis wood
Autorzy:
Łukaszewicz, J.P.
Zieliński, K.
Powiązania:
https://bibliotekanauki.pl/articles/184999.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
węgiel drzewny
Salix viminalis
wooden charcoal
carbon molecular sieves
specific surface
pore structure
Opis:
Microporous carbon molecular sieves of extremely narrow pore size distribution were obtained by carbonization of a novel raw material (Salix viminalis). The precursor is inexpensive and widely accessible. The pore capacity and specific surface area are upgradable by H3PO4 treatment without significant change of narrowed PSD. The dominating pore size indicates that these molecular sieves are a potential competitor to other nanoporous materials such as opened and purified carbon nanotubes.
Źródło:
Chemical and Process Engineering; 2011, 32, 3; 195-201
0208-6425
2300-1925
Pojawia się w:
Chemical and Process Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mechanical Properties of VM12 Steel after 30 000 Hrs of Ageing at 600°C Temperature
Właściwości mechaniczne stali VM12 po 30 000 godzin starzenia w temperaturze 600°C
Autorzy:
Golański, G.
Zieliński, A.
Słania, J.
Jasak, J.
Powiązania:
https://bibliotekanauki.pl/articles/353394.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
VM12 steel
ageing
microstructure
mechanical properties
stal VM12
starzenie
mikrostruktura
właściwości mechaniczne
Opis:
The paper describes the influence of different times of ageing on mechanical properties and microstructure stability in hardened and tempered VM12 steel exposed to service temperature - 600°C. Detailed microstructural and microchemical analysis of secondary phases was carried out using scanning electron microscopy (SEM + EDX) and X-ray phase analysis of carbide isolates. Performed research has proved high stability of strength properties of the investigated steel, which is connected with the lath stability of the microstructure of tempered martensite. Slight changes in strength properties were accompanied by over 50% reduction in impact strength KV of the examined cast steel, from the level of 83 J in the as-received condition to 38 J after 30 000 hrs of ageing at the temperature of 600°C. Significant decrease in impact energy KV of VM12 steel results from the growth of the amount and size of precipitations on grain boundaries.
W pracy przedstawiono wyniki badań zmian w mikrostrukturze i właściwościach mechanicznych stali VM12 po 30000 godzin starzenia w temperaturze 600°C. Przeprowadzone badania wykazały, że długotrwałe starzenie stali VM12 prowadzi do względnego wzrostu wydzieleń po granicach ziaren, głównie po granicach ziaren byłego austenitu oraz skutkuje zanikiem wydzieleń typu MX oraz wydzielaniem fazy Lavesa. Zmiany w mikrostrukturze w niewielkim stopniu wpłyneły na zmiany właściwości wytrzymałościowych (granicy plastyczności, wytrzymałości na rozciąganie) o ok. 7%, natomiast spowodowały ponad 50% redukcje udarności KV z poziomu 83 J w stanie wyjściowym do 38 J po 30 000 godzin starzenia. Ponadto starzenie stali VM12 skutkowało ok. 16% obniżeniem twardości HV10 co powiązano z zanikiem wydzieleń typu MX.
Źródło:
Archives of Metallurgy and Materials; 2014, 59, 4; 1351-1354
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Enhancing capabilities of Atomic Force Microscopy by tip motion harmonics analysis
Autorzy:
Babicz, S.
Smulko, J.
Zieliński, A.
Powiązania:
https://bibliotekanauki.pl/articles/199918.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
atomic force microscopy (AFM)
harmonics
van der Waals forces
Opis:
Motion of a tip used in an atomic force microscope can be described by the Lennard-Jones potential, approximated by the van der Waals force in a long-range interaction. Here we present a general framework of approximation of the tip motion by adding three terms of Taylor series what results in non-zero harmonics in an output signal. We have worked out a measurement system which allows recording of an excitation tip signal and its non-linear response. The first studies of spectrum showed that presence of the second and the third harmonics in cantilever vibrations may be observed and used as a new method of the investigated samples characterization.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2013, 61, 2; 535-539
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The service life of the repair welded joint of Cr-Mo / Cr-Mo-Y
Autorzy:
Sroka, M.
Zieliński, A.
Mikuła, J.
Powiązania:
https://bibliotekanauki.pl/articles/355828.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
creep
welded joint
Cr-Mo
Cr-M-V steel
residual life
Opis:
The service life of the repair welded joint of Cr-Mo / Cr-Mo-Y This paper presents the evaluation of the service life of dissimilar repair welded joint from Cr-Mo/Cr-Mo-V steel after 200,000 h service under creep condition. The investigations of microstructure using scanning electron microscopy, investigations of mechanical properties at room and elevated temperature as well as creep tests of the basic material from Cr-Mo and Cr-Mo-V steel and welded joint from these steels were carried out. The investigations allowed the tune of further safe operation of the repair welded joint in relation to the residual life of the materials to be determined. The evaluation of residual life and disposable residual life, and thus the estimation or determination of possible time of further safe operation, is crucial when the elements are operated much beyond the design work time.
Źródło:
Archives of Metallurgy and Materials; 2016, 61, 3; 1315-1320
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Changes In Properties and Microstructure of High-Chromium 9-12%Cr Steels Due to Long-Term Exposure at Elevated Temperature
Autorzy:
Zieliński, A.
Dobrzański, J.
Purzyńska, H.
Golański, G.
Powiązania:
https://bibliotekanauki.pl/articles/351104.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
steel P91
P92
VM12
microstructure
mechanical properties
long-term annealing
Opis:
This paper presents the characteristics of the performance of P91 (X10CrMoVNb9-1), P92 (X10CrWMoVNb9-2) and VM12 (X12CrCoWVNb12-2-2) steels used for condition assessment of the pressure components of boilers with supercritical steam parameters. Studies on the mechanical properties, microstructure tests using scanning and transmission electron microscopy, and X-ray analysis of the phase composition of precipitates were performed for selected steels in the as-received condition and after long-term annealing. These steel characteristics are used for the evaluation of the microstructural changes and mechanical properties of the material of components after long-term service. The result of this study is the database of material characteristics representing the mechanical properties related to the microstructure analysis and it can be used for diagnosis of the components of pressure parts of power boilers.
Źródło:
Archives of Metallurgy and Materials; 2016, 61, 2B; 957-964
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Recent alterations of aerosol concentration, mercury distribution and organic matter deposition in the Arctic
Autorzy:
Pempkowiak, J.
Zielinski, T.
Petelski, T.
Zaborska, A.
Beldowski, J.
Powiązania:
https://bibliotekanauki.pl/articles/11960.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
aerosol concentration
mercury distribution
organic matter
organic carbon
deposition
Arctic
Opis:
Material fluxes in the Arctic and Antarctic have been, in several respects, strongly affected recently. For example, atmospheric turbidity conditions are frequently subject to strong changes due to haze and dust transport episodes, which can cause considerable perturbations in the radiation balance of the atmosphere beyond regional scale. This, directly or indirectly, contributes to the increased mercury deposition and organic matter fluxes to sediments. The results show that local emissions are not always the most important factors influencing the composition of aerosol in the atmosphere of the west Spitsbergen region. The direct radiative impact of polar aerosols on the surface and at the top of the atmosphere (TOA) need to be studied more closely through both theoretical studies on the aerosol radiative properties and measurements of the surface reflectance characteristics. Mercury dissolved/solid partitioning, both in the unconsolidated, fluffy layer of suspended matter covering the sediments, and the uppermost sediment layer, indicate that the influence of the athmospheric mercury deposition event (AMDE) can prolong well into summer (July/August), and can provide a pathway to the food chain for mercury contained in sediments. Since terrigenous supplies of organic carbon to the Barents Sea are minor (∼5%) compared to the marine supply, modern sediment deposits in this region sequester on average 6.0 g/m2year organic carbon, or 5.8% of the annual integrated pelagic primary production. This burial fraction exceeds, by a factor of 3, the burial fraction derived for the Holocene.
Źródło:
Papers on Global Change; 2011, 18
2300-8121
1730-802X
Pojawia się w:
Papers on Global Change
Dostawca treści:
Biblioteka Nauki
Artykuł

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