Wszystkie pola: packet - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: Hermite and Laguerre wave packet expansions
Autorzy:: Epperson, Jay
Powiązania:: https://bibliotekanauki.pl/articles/1218865.pdf
Data publikacji:: 1997
Wydawca:: Polska Akademia Nauk. Instytut Matematyczny PAN
Opis:: This paper describes expansions in terms of Hermite and Laguerre functions similar to the Frazier-Jawerth expansion in Fourier analysis. The wave packets occurring in these expansions are finite linear combinations of Hermite and Laguerre functions. The Shannon sampling formula played an important role in the derivation of the Frazier-Jawerth expansion. In this paper we use the Christoffel-Darboux formula for orthogonal polynomials instead. We obtain estimates on the decay of the Hermite and Laguerre wave packets by investigating two closely related oscillatory integrals.
Źródło:: Studia Mathematica; 1997, 126, 3; 199-217
0039-3223
Pojawia się w:: Studia Mathematica
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: The Wave Packet Study of Exciton Dynamics in the ZnSe-ZnTe Quantum Well
Autorzy:: Bała, P.
Powiązania:: https://bibliotekanauki.pl/articles/1969006.pdf
Data publikacji:: 1998-08
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:: 03.65.-w
71.35.-y
72.80.Ey
Opis:: In this paper we perform a detailed study of the formation and the dynamics of the exciton in the ZnSe/ZnTe quantum well taking into account two-particle nature of the process. The electron-hole interaction is included in the model through the electrostatic potential, which results in a nonlinear coupling of the electron and hole equations of motion. The coupled time-dependent Schrodinger equation describing the electron and hole dynamics is integrated numerically. The detailed dynamics of the excitonic electron-hole pair in the quantum well is presented for different uniform electric field applied across the structure.
Źródło:: Acta Physica Polonica A; 1998, 94, 2; 240-244
0587-4246
1898-794X
Pojawia się w:: Acta Physica Polonica A
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Adaptive wavelet techniques for compressing digital mammograms
Autorzy:: Bruckmann, A.
Flatscher, H.
Schell, T.
Uhl, A.
Powiązania:: https://bibliotekanauki.pl/articles/1954514.pdf
Data publikacji:: 1999
Wydawca:: Politechnika Gdańska
Tematy:: wavelet compression
wavelet packet
time-varying decomposition
NSMRA
mammograms
Opis:: In this work we investigate the possible benefit of employing adaptive wavelet algorithms instead of the classical fixed pyramidal wavelet decomposition for the compression of digital mammograms. In particular, we target on adaptive wavelet packet and NSMRA decompositions. We observe that information cost function optimized wavelet packet subband structures do not offer compression performance gain in this case whereas NSMRA decompositions moderately improve the results of classical wavelet decompositions. Due to the lack of fast and reliable search algorithms fixed NSMRA decompositions need to be generated and employed for classes of similar images.
Źródło:: TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 1999, 3, 4; 381-396
1428-6394
Pojawia się w:: TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Differentiation packet transfer quality in ip-based networks
Autorzy:: Burakowski, Wojciech.
Kopertowski, Zbigniew.
Bęben, Andrzej.
Powiązania:: Biuletyn WIŁ 2002, s. 37-43
Data publikacji:: 2002
Tematy:: Systemy łączności i transmisji informacji
Łączność wojskowa technika
Opis:: Rys., tab.; Bibliogr.; Abstr.
Dostawca treści:: Bibliografia CBW

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Skocz do pozycji: 5.

Tytuł:: Simple analysis of the impact of packet loss and delay on voice transmission quality
Autorzy:: Perlicki, K.
Powiązania:: https://bibliotekanauki.pl/articles/309277.pdf
Data publikacji:: 2002
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: E-model
packet network
packet loss
delay
transmission quality rating
Opis:: In this paper a simple analytical expression based on E-model is applied to analyse the impact of packet loss and delay on voice transmission quality. The relationship between overall transmission quality rating, packet loss and delay G.711, G.723 and G.729 codes is presented.
Źródło:: Journal of Telecommunications and Information Technology; 2002, 2; 53-56
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:: Methods for evaluation packet delay distribution of flows using Expedited Forwarding PHB
Autorzy:: Kaczmarek, S.
Narloch, M.
Powiązania:: https://bibliotekanauki.pl/articles/308193.pdf
Data publikacji:: 2004
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: packet delay distribution
Expedited Forwarding PHB
differentiated services
Service Level Specification
IP QoS
Opis:: The paper regards problem of providing statistical performance guarantees for real-time flows using Expedited Forwarding Per Hop Behavior (EF PHB) in IP Differentiated Services networks. Statistical approach to EF flows performance guarantees, based on calculation of probability that end-to-end packet delay is larger than certain value, allows larger network utilization than previously proposed deterministic approach. In the paper different methods of packet delay distribution evaluation are presented and compared. Considered cases comprise evaluation of delay distribution models for the core network and evaluation of end-to-end packet delay in the network consisted of edge node and chain of core nodes. Results obtained with aid of analytical models are compared with simulation results.
Źródło:: Journal of Telecommunications and Information Technology; 2004, 2; 29-37
1509-4553
1899-8852
Pojawia się w:: Journal of Telecommunications and Information Technology
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Packet switch architecture with multiple output queueing
Autorzy:: Danilewicz, G.
Głąbowski, M.
Kabaciński, W.
Kleban, J.
Powiązania:: https://bibliotekanauki.pl/articles/308342.pdf
Data publikacji:: 2004
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: high-speed packet switching
output queueing
buffer
switch fabric
switching node
multicast
Opis:: In this paper the new packet switch architecture with multiple output queuing (MOQ) is proposed. In this architecture the nonblocking switch fabric, which has the capacity of N _N2 N2, and output buffers arranged into N separate queues for each output, are applied. Each of N queues in one output port stores packets directed to this output only from one input. Both switch fabric and buffers can operate at the same speed as input and output ports. This solution does not need any speedup in the switch fabric as well as arbitration logic for taking decisions which packets from inputs will be transferred to outputs. Two possible switch fabric structures are considered: the centralized structure with the switch fabric located on one or several separate boards, and distributed structure with the switch fabric distributed over line cards. Buffer arrangements as separate queues with independent write pointers or as a memory bank with one pointer are also discussed. The mean cell delay and cell loss probability as performance measures for the proposed switch architecture are evaluated and compared with performance of OQ architecture and VOQ architecture. The hardware complexity of OQ, VOQ and presented MOQ are also compared. We conclude that hardware complexity of proposed switch is very similar to VOQ switch but its performance is comparable to OQ switch.
Źródło:: Journal of Telecommunications and Information Technology; 2004, 4; 76-83
1509-4553
1899-8852
Pojawia się w:: Journal of Telecommunications and Information Technology
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Towards broadband global optical and wireless networking
Autorzy:: Marciniak, M.
Powiązania:: https://bibliotekanauki.pl/articles/308934.pdf
Data publikacji:: 2004
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: optical networks
wireless networks
radio-over-fibre
optical packet networks
transparent networks
Opis:: This paper presents a novel, non-conventional approach to the future optical and wireless hybrid transport network, capable of supporting dominant kinds of trac, i.e., voice/real time, wireless and packet data tracffic in a single transport network. The proposed model combines different technologies as connection and connectionless networks, optical cable and wireless (microwave/millimetre wave or optical wireless), being suitable for a variety of purposes and services in order to achieve global broadband networking features. Our new networking model contains an extension to wireless world in order to achieve mobility and personalisation of connection. From the networking point of view it consists of an upgrade of real-time traffic with the microwave modulated optical wave, in order to carry out conventional mobile wireless signals via optical fibres over long distances and without significant distortion. The whole available bandwidth can be fully exploited in the hybrid network. In the IP part of the network the quality of service (QoS) can be differentiated for various classes of packets and network reliability/survivability can be categorised for the whole hybrid network. This proposal combines complete and revolutionary shift to packet traffic with smooth evolutionary upgrades. We believe the model presented here is a powerful tool to trace the future evolution of telecommunications worldwide for the next 25 years.
Źródło:: Journal of Telecommunications and Information Technology; 2004, 3; 65-70
1509-4553
1899-8852
Pojawia się w:: Journal of Telecommunications and Information Technology
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Evolutionary paths in wireless communication systems
Autorzy:: Michalski, W.
Powiązania:: https://bibliotekanauki.pl/articles/309042.pdf
Data publikacji:: 2005
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: cellular mobile radio systems
wireless local area networks
wireless personal networks
wide area wireless packet data systems
satellite-based mobile systems
paging/messaging systems
cordless telephones
access points
switches
GPRS
Mobile IP
WLAN cellular integration
Opis:: The paper contains a review and analysis of evolutionary paths of seven most important, from network development strategy point of view, wireless communication systems, especially the WLAN operating according to the IEEE 802.11 standard. With respect to WLAN, trends related to evolution toward mobile network and self organizing network as well as toward integration of WLAN and GSM using GPRS are presented. Concerning WLAN architecture development, evolution paths toward distributed controlled network as well as centrally coordinated and controlled network are described. Moreover, analysis includes cellular mobile radio systems, wireless personal networks, wide area wireless packet data systems, satellite-based mobile systems, paging/messaging systems and cordless telephones. With respect to these systems, general evolution process and trends associated with this process are described.
Źródło:: Journal of Telecommunications and Information Technology; 2005, 3; 105-111
1509-4553
1899-8852
Pojawia się w:: Journal of Telecommunications and Information Technology
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: Use of Modified Adaptive Heuristic Critic Algorithm for Novel Scheduling Mechanism in Packet-Switched Networks
Autorzy:: Jednoralski, M.
Kacprzak, T.
Powiązania:: https://bibliotekanauki.pl/articles/92909.pdf
Data publikacji:: 2005
Wydawca:: Uniwersytet Przyrodniczo-Humanistyczny w Siedlcach
Tematy:: reinforcement learning
telecommunication networks
packet scheduling
Opis:: In this paper a novel scheduling algorithm of packet selection in a switch node for transmission in a network channel, based on Reinforcement Learning and modified Adaptive Heuristic Critic is introduced. A comparison of two well known scheduling algorithms: Earliest Deadline First and Round Robin shows that these algorithms perform well in some cases, but they cannot adapt their behavior to traffic changes. Simulation studies show that novel scheduling algorithm outperforms Round Robin and Earliest Deadline First by adapting to changing of network conditions.
Źródło:: Studia Informatica : systems and information technology; 2005, 2(6); 21-34
1731-2264
Pojawia się w:: Studia Informatica : systems and information technology
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 11.

Tytuł:: One-Dimensional versus Three-Dimensional Approaches to the Rydberg Wave Packet Dynamics
Autorzy:: Kopyciuk, T.
Parzyński, R.
Powiązania:: https://bibliotekanauki.pl/articles/2046881.pdf
Data publikacji:: 2006-07
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:: 32.80.Rm
03.65.Ge
Opis:: We show that a one-dimensional approximation to a real three-dimensional atom offers good results for a selected group of the Rydberg states. It is demonstrated in the context of evolution of the Rydberg wave packets produced by the so-called half-cycle pulses.
Źródło:: Acta Physica Polonica A; 2006, 110, 1; 41-49
0587-4246
1898-794X
Pojawia się w:: Acta Physica Polonica A
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 12.

Tytuł:: Performance evaluation of the multiple output queueing switch with different buffer arrangements strategy
Autorzy:: Danilewicz, G.
Kabaciński, W.
Pleban, J.
Parniewicz, D.
Dąbrowski, P.
Powiązania:: https://bibliotekanauki.pl/articles/308008.pdf
Data publikacji:: 2006
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: packet switching
switch fabric
multiple output queueing
Opis:: Performance evaluation of the multiple output queueing (MOQ) switch recently proposed by us is discussed in this paper. In the MOQ switch both the switch fabric and buffers can operate at the same speed as input and output ports. This solution does not need any speedup in the switch fabric as well as any matching algorithms between inputs and outputs. In this paper new performance measures for the proposed MOQ switch are evaluated. The simulation studies have been carried out for switches with different buffer arrangements strategy and of capacity 2×2, 4×4, 8×8, 16×16 and 32×32, and under selected traffic patterns. The simulations results are also compared with OQ switches of the same sizes.
Źródło:: Journal of Telecommunications and Information Technology; 2006, 3; 43-48
1509-4553
1899-8852
Pojawia się w:: Journal of Telecommunications and Information Technology
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 13.

Tytuł:: Simple admission control procedure for QoS packet switched military networks
Autorzy:: Duda, D.
Burakowski, W.
Powiązania:: https://bibliotekanauki.pl/articles/308006.pdf
Data publikacji:: 2006
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: QoS
admission control
measurement based AC
Opis:: Providing quality of service (QoS) into the networks based on the packet switched technologies, as ATM and IP, is currently the challenge for the military communication system designers. The main element for achieving QoS capabilities is to implement effective admission control (AC) function, which regulates the volume of submitted traffic to the network. The traditional approach for the AC is that it is invoked by each call requesting QoS. As a consequence, the call set-up latency is increasing and, in addition, the signaling traffic in the network is growing. This paper proposes a simple AC method that is based on the online traffic load measurements and assumes that the AC is involved only when the load exceeds a predefined threshold. As a consequence, for most of the connections the AC is not necessary to be executed and this causes lower set-up phase duration and limits the volume of signaling traffic. The numerical results showing effectiveness of the approach are included and compared with traditional AC performing.
Źródło:: Journal of Telecommunications and Information Technology; 2006, 3; 38-42
1509-4553
1899-8852
Pojawia się w:: Journal of Telecommunications and Information Technology
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 14.

Tytuł:: Impact of the duration of speech sequences on speech quality
Autorzy:: Pocta, P.
Vaculík, M.
Powiązania:: https://bibliotekanauki.pl/articles/308555.pdf
Data publikacji:: 2007
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: voice transmission quality of service
speech sequence
intrusive measurement
perceptual evaluation of speech quality
jitter rate
packet loss
Opis:: This paper describes simulations of speech sequences transmission for intrusive measurement of voice transmission quality of service (VTQoS) in the environment of IP networks. The aim of the simulations was to investigate the impact of the different durations of speech sequences on speech quality from the jitter rate and packet loss point of view in IP networks. The ITU-T G.729 and ITU-T G.723.1 encoding schemes were used for the purpose of the simulations. The assessment of speech quality was realized by means of perceptual evaluation of speech quality (PESQ) algorithm. A comparison of the impact of different durations of speech sequences on speech quality and determination of the optimal duration of speech sequence for measurements of speech quality in telecommunication networks, is the aim of this paper.
Źródło:: Journal of Telecommunications and Information Technology; 2007, 4; 72-76
1509-4553
1899-8852
Pojawia się w:: Journal of Telecommunications and Information Technology
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 15.

Tytuł:: Recovery of impact signatures in diesel engine using wavelet packet transform (WPT)
Wykrywanie wymuszeń impulsowych w silniku ZS za pomocą pakietów falkowych (WPT)
Autorzy:: Flekiewicz, M.
Madej, H.
Powiązania:: https://bibliotekanauki.pl/articles/329184.pdf
Data publikacji:: 2007
Wydawca:: Polska Akademia Nauk. Polskie Towarzystwo Diagnostyki Technicznej PAN
Tematy:: diagnostyka uszkodzeń
silnik spalinowy
drgania
WPT
fault diagnosis
engine vibration
Opis:: A fault diagnosis technique for internal combustion engines using time-scale representations of vibration signal is presented in this paper. Engine block vibration results as a sum of many excitations mainly connected with engine speed and their intensity increases with the appearance of a fault or in case of higher engine elements wearing. In this paper an application of acceleration signals for the estimation of the influence of piston skirt clearance on diesel engine block vibrations has been described. Engine body accelerations registered for three simulated cases representing piston skirt clearance variations were an object of preliminary analysis. The presented procedures were applied to vibration and pressure signals acquired for a 0.5 dm3 Ruggerini, air cooled diesel engine. Reciprocating machines are difficult to diagnose using traditional frequency domain techniques because of generate transient vibration. In conducted experiments WPT has been chosen as the decomposition tool for feature extraction as a tool providing a flexible time-frequency resolution and a rich library of redundant wavelet bases.
W artykule przedstawiono wyniki badań diagnostycznych silnika ZS za pomocą analizy czasowo-częstotliwościowej. Drgania bloku i głowicy badanego silnika są spowodowane wieloma wymuszeniami związanymi z jego prędkością obrotową a ich intensywność wzrasta wraz z pojawianiem się uszkodzeń mechanicznych, zużycia eksploatacyjnego oraz występowania anomalii w procesie spalania. Sygnały przyspieszeń drgań wykorzystano do określenia wpływu stanu symulowanego luzu w złożeniu tłok cylinder. W ramach badań silnika ZS, chłodzonego powietrzem o pojemności 0,5 dm3 firmy Ruggerini zasymulowano trzy wartości luzu. Ze względu na fakt, że silniki spalinowe są złożonymi obiektami diagnozowania wykorzystanie tradycyjnych metod analizy częstotliwościowej nie zapewnia precyzyjnej identyfikacji charakterystycznych wymuszeń. W prowadzonych badaniach przeprowadzono dekompozycję sygnału drganiowego za pomocą pakietów falkowych (WPT).
Źródło:: Diagnostyka; 2007, 4(44); 25-30
1641-6414
2449-5220
Pojawia się w:: Diagnostyka
Dostawca treści:: Biblioteka Nauki

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