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Wyszukujesz frazę "phase distributions" wg kryterium: Temat


Wyświetlanie 1-4 z 4
Tytuł:
Generation of Asymmetrical Difference Patterns from Array Antennas
Autorzy:
Satyanarayana, M.
Raju, G. S. N.
Powiązania:
https://bibliotekanauki.pl/articles/226481.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
asymmetric patterns
arrays
array antennas
marine
radars
amplitude distributions
phase distributions
Opis:
It is common to produce sum patterns from array antennas. These patterns are basically symmetric with one main lode in bore sight and symmetric sidelobe structure around the main beam. The antennas associated with the marine radars are required to produce patterns with asymmetric side lobes. Asymmetrical patterns are very useful for marine radars when ships sail in turbulent water where roll and pitch exists.In particular the sidelobes in one side are lower than those of the other side. It is also essential to produce difference patterns with asymmetric structure from the boresight direction. These patterns are required to have null in the bore sight and high difference slope in the same direction. When these patterns are required from marine radars, the side lobes associated with the difference pattern on the either side of the boresight is at the different heights. In the present work, such useful patterns are generated from the newly designed arrays. The amplitude and phase distributions are designed for small and large arrays. The radiation patterns are numerically computed and they are presented in u- domain.
Źródło:
International Journal of Electronics and Telecommunications; 2011, 57, 2; 185-190
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Queuing models for cellular networks with generalised Erlang service distributions
Autorzy:
Jayasuriya, A.
Powiązania:
https://bibliotekanauki.pl/articles/307731.pdf
Data publikacji:
2003
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
sieci komórkowe
cellular networks
phase type distributions
generalised Erlang
Opis:
Providing seamless handover is one of the major problems in mobile communication environments. Careful dimensioning of the network and the underlying teletraffic analysis plays a major role in determining the various grade of services (GoSs) that can be provided at various network loads for handover users. It has been shown that the channel holding time of a cell, one of the important parameters in any teletraffic analysis, can be accurately modelled by Erlang distributions. This paper focuses on solving queuing systems with generalised Erlang service distributions and exponential arrival distributions. We present the quasi-birth-death (QBD) process, which characterises the queuing models with generalised Erlang service and exponential interarrival distributions. We then use the properties of Erlang distributions and characteristics of channel allocation process of cellular networks to simplify the queues used to model cellular networks. The use of these simplifications provide a significant reduction in computation time required to solve these QBDs.
Źródło:
Journal of Telecommunications and Information Technology; 2003, 2; 55-61
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Approximation of message inter-arrival and inter-departure time distributions in IMS/NGN architecture using phase-type distributions
Autorzy:
Kaczmarek, S.
Sac, M.
Powiązania:
https://bibliotekanauki.pl/articles/308647.pdf
Data publikacji:
2013
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
call processing performance
IMS
message interarrival time distributions
message inter-departure time distributions
NGN
phase type distributions
traffic model
Opis:
Currently it is assumed that requirements of the information society for delivering multimedia services will be satisfied by the Next Generation Network (NGN) architecture, which includes elements of the IP Multimedia Subsystem (IMS) solution. In order to guarantee Quality of Service (QoS), NGN has to be appropriately designed and dimensioned. Therefore, proper traffic models should be proposed and applied. This requires determination of queuing models adequate to message inter-arrival and interdeparture time distributions in the network. In the paper the above mentioned distributions in different points of a single domain of NGN are investigated, using a simulation model developed according to the latest standards and research. Relations between network parameters and obtained message inter-arrival as well as interdeparture time distributions are indicated. Moreover, possibility of approximating the above mentioned distributions using phase-type distributions is investigated, which can be helpful in identifying proper queuing models and constructing an analytical model suitable for NGN.
Źródło:
Journal of Telecommunications and Information Technology; 2013, 3; 9-18
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The non-stationary two-phase flow evaluation by radioisotopes
Autorzy:
Petryka, L.
Zych, M.
Murzyn, R.
Powiązania:
https://bibliotekanauki.pl/articles/148777.pdf
Data publikacji:
2005
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
two-phase flow
radiotracers
gamma transmission technique
velocity and density distributions
Opis:
Two-phase flows, especially those commonly applied during hydraulic exploitation of minerals, are often characterized by the presence of serious variations of density. The adequate control of such a system produces high discrepancy of the mixture velocity. These flows cannot be examined by traditional impulse injection of a tracer. A solution to these difficulties is proposed based on the application of sealed sources and measuring methods calibrated by radiotracers during steady conditions of the flow. The paper presents the results of a full-scale test in a laboratory installation where the stream of water is transporting upwards naturally dispersed nodules through a Ř150 mm vertical pipe. A specially designed equipment allows the control of mixture density as well as the measurement of water and the velocity of particular nodules. The obtained results illustrate the capabilities of radiotracers and possibilities how they can be applied in different two-phase flows, when both density and velocity of the components significantly vary during observation.
Źródło:
Nukleonika; 2005, 50, 1; 43-46
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-4 z 4

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