Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 12

Liczba wyników na stronie
first rewind previous Strona / 1 next fast forward last
Wyniki wyszukiwania
help Sortuj według:

help Ogranicz wyniki do:
first rewind previous Strona / 1 next fast forward last
PL
F2Tx to komputerowy system planowania strategicznego oraz projektowania konfiguracji i wyposażenia światłowodowych sieci dostępowych o architekturze FTTH, FTTB i FTTC realizowanych w technice PON Zaimplementowany przy użyciu współczesnych narzędzi z dziedziny programowania matematycznego i baz danych F2Tx jest oparty na zaawansowanych algorytmach optymalizacji sieci, wykorzystujących modele i metody programowania liniowego całkowitoliczbowego i teorii grafów. Komercyjna wersja systemu została wdrożona pod nazwą RNOS w Orange Polska i posłużyła min, do zaprojektowania sieci FTTH dla Warszawy.
EN
F2Tx is a computer system for strategic network planning and designing the configuration and equipment of PON technique-based fibre access networks that utilize FTTH. FTTB and FTTC architectures. Implemented with contemporary mathematical programming and database management tools, F2Tx employs advanced network optimisation algorithms based on mixed-integer linear programming and graph theory. A commercial version of the system named FiNOS has been deployed at Orange Poland and used for designing, e.g. an FTTH network for Warsaw.
2
EN
This paper discusses compact node-link formulations for MPLS fast reroute optimal single path layout. We propose mathematical formulations for MPLS fast reroute local protection echanisms. In fact, we compare one-to-one (also called detour) local protection and many-to-one (also called facility backup) local protection mechanisms with respect to minimized maximum link utilization. The optimal results provided by the node-links are compared with the suboptimal results provided by algorithms based on non-compact linear programming (path generation) approach and IP-based approach.
5
Content available Path Diversity Protection in Two-Layer Networks
EN
The paper addresses an optimization problem related to dimensioning links in a resilient two-layer network. A particular version of the problem which assumes that links of the upper layer are supported by unique paths in the lower layer is considered. Two mixed-integer programming formulations of this problem are presented and discussed. Direct resolving of these formulations requirespre-selection of "good" candidate paths in the upper layer of the network. Thus, the paper presents an alternative approach which is based on decomposing the resolution process into two phases, resolved iteratively. The first phase subproblem is related to designing lower layer path flows that provide the capacities for the logical links of the upper layer. The second phase is related to designing the flow patterns in the upper layer with protection assured through diversity of paths. In this phase we take into account the failures of the logical links that result from the failures of the lower layer links (so called shared risk link groups).
EN
The paper deals with traffic recovery in IP/MPLS network carrying traffic of different priority classes. Two off-line network design problems are presented employing two different recovery mechanisms - single backup path and failure-dependent backup path protection. Also, two routing strategies are studied in this paper. A network design problem with failure-dependent path protection mechanism combined with the routing strategy implying both load balancing and path length minimization is proposed in this paper. The efficiency of the approach proposed is tested by combining optimization and simulation tools. Numerical experiments show that using the proposed protection mechanism allows more traffic to be accommodated in the network and decreases the number of disrupted LSPs in case of failure, as compared to other recovery options considered.
EN
Telecommunications networks are facing increasing demand for Internet services. Therefore, the problem of telecommunications network design with the objective to maximize service data flows and provide fair treatment of all services is very up-to-date. In this application, the so-called max-min fair (MMF) solution concept is widely used to formulate the resource allocation scheme. It assumes that the worst service performance is maximized and the solution is additionally regularized with the lexicographic maximization of the second worst performance, the third one, etc. In this paper we discuss solution algorithms for MMF problems related to telecommunications network design. Due to lexicographic maximization of ordered quantities, the MMF solution concept cannot be tackled by the standard optimization model (mathematical programme). However, one can formulate a sequential lexicographic optimization procedure. The basic procedure is applicable only for convex models, thus it allows to deal with basic design problems but fails if practical discrete restrictions commonly arriving in telecommunications network design are to be taken into account. Then, however, alternative sequential approaches allowing to solve non-convex MMF problems can be used.
PL
Przedstawiono różne rodzaje akumulatorów wykorzystywanych w przemyśle oraz technologie ich wytwarzania. Szczegółowo omówiono właściwości użytkowe i wymagania eksploatacyjne akumulatorów z ciekłym elektrolitem, z dodatnią płytą pancerną OPzS.
EN
The paper presents different types of batteries for industrial use and their production technology. Application characteristics and operating requirements of liąuid elect-rolyte batteries with armoured positwe plates (OPzS) - are discussed in detail.
EN
The bit rate of modern applications typically varies in time. We consider the traffic elastic if the rate of the sources can be controlled as a function of free resources along the route of that traffic. The objective is to route the demands optimally in sense of increasing the total network throughput while setting the rates of sources in a fair way. We propose a new fairness definition the relative fairness that handles lower and upper bounds on the traffic rate of each source and we compare it with two other known fairness definitions, namely, the max-min and the proportional rate fairness. We propose and compare different routing algorithms, all with three types of fairness definitions. The algorithms are all a tradeoff between network throughput, fairness and computational time.
EN
We show how the so called dual benders decomposition approach (DBDA), proposed by Minoux and Serrault (1981), can be extended to the optimal design problems of multi-layer networks robust to failures and demand variations considered by Pióro (1998). DBDA substantially enforces the Lagrangian relaxation technique combined with sub-gradient optimisation used in Pióro.
12
Content available remote Iteracyjne projektowanie wielowarstwowych sieci telekomunikacyjnych
PL
Cechami charakterystycznymi typowych współczesnych sieci telekomunikacyjnych jest wielowarstwowość (w sensie hierarchii zasobów sieci) oraz występowanie wklęsłych funkcji kosztu. Niniejszy artykuł opisuje iteracyjne podejście do projektowania sieci tego rodzaju. Rozważane są mianowicie wielowarstwowe sieci telekomunikacyjne, w których wymiarowanie krawędzi odbywa się przy użyciu funkcji wklęsłych, w efekcie czego funkcje kosztu krawędzi są także wklęsłe. Badany problem można określić jako zadanie wyznaczenia najtańszych przepływów wielotowarowych, uogólnione na sieć wielowarstwową. Zaproponowane w artykule algorytmy stanowią istotne rozwinięcie metody Yageda dotyczącej sieci jednowarstwowej z wklęsłymi funkcjami kosztu krawędzi oraz zestawem linowych ograniczeń na przepływy. Algorytm Yageda został udoskonalony i następnie wykorzystany w iteracyjnym schemacie projektowania sieci wielowarstwowej. Efektywność przedstawionych rozwiązań została zilustrowana za pomocą przykładów numerycznych. Rozważane algorytmy mają charakter ogólny i mogą być wykorzystane np. przy projektowaniu sieci ATM zbudowanych na dzierżawionych ścieżkach warstwy synchronicznej SDH, gdyż w tym przypadku funkcje wymiarowania krawędzi we wszystkich warstwach są wklęsłe lub liniowe.
EN
Typical telecommunication networks of today can be characterized as multi-layer networks (in the sense of resources hierarchy) with concave cost functions. In this article an iterated approach to the design of networks of this type is presented. Namely the networks taken into consideration are multi-layer telecommunication networks with concave link dimensioning functions, implying concave link cost functions. The investigated problem can be described as a task of finding the cheapest multi-commodity flows in a multi-layer network. Algorithms proposed in this paper substantially extend the approach of Yaged to deal with single-layer network dimensioning problems with concave link capacity cost function and a set of linear flow constraints. The paper first introduced a refined Yaged algorithm and then shows how to use it iteratively to design a network with many layers of resources. The effectiveness of the proposed approach is illustrated by means of numerical examples. The proposed methods are well suited for the nominal design of ATM networks based on leased SDH synchronous layer paths, since in this case the dimensioning functions in all layers are either concave or linear.
first rewind previous Strona / 1 next fast forward last
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.