104 research outputs found
Fragmentation-Aware Algorithm with Bordering Super-Channels in Spectrally/Spatially-Flexible Optical Networks
No full textSpectrally/spatially flexible optical networks (SS-FONs) are a promising solution to future traffic requirements in optical backbone networks. SS-FONs exploit the spatial dimension to increase the network capacity, while preserving the resource management flexibility, as they still operate within a flex-grid composed of small frequency slots (slices). A flex-grid makes it possible to realize transmission using super-channels (SChs) that comprise a set of contiguous slots. In this paper, we focus on spectral SChs, i.e., a SCh realized only on one spatial mode on each fiber. In SS-FONs, setting up and tearing down multiple lightpath requests within a flex-grid may result in spectrum fragmentation and, in turn, blocking of requests. In this work, we investigate several fragmentation metrics in a SS-FON. The problem of identifying appropriate metrics to measure fragmentation has been investigated in single-core elastic optical networks, but to the best of our knowledge, there is no such research available for SS-FONs. Therefore, we propose several fragmentation metrics for SS-FONs. We introduce the concept of bordering super-channels (B-SChs), i.e., SChs whose spectrum is allocated at the border of already allocated spectrum slots, which show promising results with regard to minimizing fragmentation. The investigation of all candidate B-SChs allows us to find the one that minimizes the network fragmentation and, in turn, spectrum waste. Hence, we propose a fragmentation-Aware (FA) algorithm with bordering SChs that assigns optical resources to dynamic requests by utilizing information from the proposed fragmentation metrics and the set of candidate B-SChs. Experiments on a representative network topology show that the investigation of multiple B-SChs in the FA algorithm reduces the blocking probability when compared to the reference FA algorithms. Finally, we analyze the impact of a spatial continuity constraint on the network fragmentation
Brown-field gradual migration planning toward spectrally-spatially flexible optical networks
No full textIn this paper, we motivate a brown-field migrationplanning as a cost-efficient procedure to scale the capacity ofshort-term realizable elastic optical networks (EONs), graduallyconverting them into spectrally-spatially flexible optical networks(SS-FONs). After a formal statement of the brown-field EON toSS-FON migration planning problem, a Stochastic Iterated LocalSearch (SILS) metaheuristic is presented to solve it in realistictime-scales. Using the proposed metaheuristic, we study themigration of two different reference backbone EONs to SS-FONsbased in realistic traffic forecasts up to year 2031, accountingfor both unicast and anycast traffic types. The obtained resultsalso serve to highlight the good performance of the proposedSILS metaheuristic versus alternative heuristic approaches usedas benchmark.The work of P. Lechowicz and K. Walkowiak was supported by NationalScience Centre, Poland under Grant 2017/27/B/ST7/00888. The work ofJ. Perell ́o and S. Spadaro was supported by the Spanish Government throughproject ALLIANCE-B (TEC2017-90034-C2-2-R) with FEDER contributionPeer Reviewe
Brown-field gradual migration planning toward spectrally-spatially flexible optical networks
No full textIn this paper, we motivate a brown-field migrationplanning as a cost-efficient procedure to scale the capacity ofshort-term realizable elastic optical networks (EONs), graduallyconverting them into spectrally-spatially flexible optical networks(SS-FONs). After a formal statement of the brown-field EON toSS-FON migration planning problem, a Stochastic Iterated LocalSearch (SILS) metaheuristic is presented to solve it in realistictime-scales. Using the proposed metaheuristic, we study themigration of two different reference backbone EONs to SS-FONsbased in realistic traffic forecasts up to year 2031, accountingfor both unicast and anycast traffic types. The obtained resultsalso serve to highlight the good performance of the proposedSILS metaheuristic versus alternative heuristic approaches usedas benchmark.The work of P. Lechowicz and K. Walkowiak was supported by NationalScience Centre, Poland under Grant 2017/27/B/ST7/00888. The work ofJ. Perell ́o and S. Spadaro was supported by the Spanish Government throughproject ALLIANCE-B (TEC2017-90034-C2-2-R) with FEDER contributionPeer ReviewedPostprint (author's final draft
System partyjny ukrainy od pomarańczowej rewolucji do Euromajdanu perspektywa instytucjonalno-prawna
No full textRecenzja: Partie i systemy partyjne Europy Środkowo-Wschodniej. Dwie dekady doświadczeń red. Arkadiusz Czwołek, Magdalena Nowak-Paralusz, Karolina Gawron-Tabor
No full textKohabitacja a trwałość gabinetów koalicyjnych w Polsce po 1991 roku
No full textIn relation to the systemic transformation, which began in Poland in 1989, there was a need to define a new political regime. Eventually it was decided to settle upon a system of government which is characterised by the duality of executive power exercised by the President, as well as Prime Minister and the government accountable to parliament. This element of the political regime creates the potential for cohabitation – an inher-ently conflictual phenomena which can have many negative consequences. One of them is the possibility of its negative impact on the duration of the coalition cabinet. In this article, we intend to test the hypothesis, according to which the phenomenon of cohabitation has a negative impact on coalition governments through the reduc-tion of their duration. The aticle consists of four parts. The first briefly characterizes the evolution of the Polish political regime, highlighting the potential for cohabita-tion which is created by the dual structure of executive – the permanent element of Polish system of government. In the second part we explain the concepts of the cabinet government and the coalition. In the third section we describe coalition gov-ernments formed in Poland in the years 1991–2014 and the phenomenon of cohabitation occurring during their lifetime. In the fourth part we examine the impact of cohabitation on the duration of coalition governments in Poland. The conclusions of the analysis are presented at the end
The Late-Roman Cottage at Exavation Site No. 2 at Tokarnia (Administrative Commune of Chęciny, District Kielce
No full textIn the course of studies of a Late-Roman settlement at excavation site No. 2 at Tokarnia there was expo sed a relic of a big cottage (excavation 2, cottage No.1).
In thiis article the author performs an analysis of the cottage equipment with a special attention focussed on ceramic vessels. This allows the author to carry out a functional
division of the obtained set of ceramic vessels. Their comparison with storage dens points out that they were playing an essential role in storage of granular products including grains. The internal division of the object is attributed by the author to
specialized cloth-weaving production.
The analyzed object is dated to the first half of 5th century A.D.Zadanie pt. „Digitalizacja i udostępnienie w Cyfrowym Repozytorium Uniwersytetu Łódzkiego kolekcji czasopism naukowych wydawanych przez Uniwersytet Łódzki” nr 885/P-DUN/2014 dofinansowane zostało ze środków MNiSW w ramach działalności upowszechniającej naukę
On the Trade-off between the Maximum Capacity and the Length of a Multicore Fiber Link
No full textThe transmission capacity of a multicore fiber (MCF) link is the sum of the capacities of its cores, but the capacity of each core depends not only on the modulation format (MF) and baud rate (BR) of the lightpaths established through the core but also on the inter-core crosstalk (XT) impairments imposed by the adjacent cores in use. For a MCF link of a given length, we propose a Binary Linear Programming formulation to determine the MF and the BR to use on each core, aiming to reach the MCF maximum capacity. Comparing the maximum capacity of a 19-core MCF with the single core fiber counterpart, the influence of the link length on the MCF capacity scaling factor reached by MCFs is characterized
- …
