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Wyświetlanie 1-9 z 9
Tytuł:
Lyapunov-based anomaly detection in preferential attachment networks
Autorzy:
Ruiz, Diego
Finke, Jorge
Powiązania:
https://bibliotekanauki.pl/articles/908114.pdf
Data publikacji:
2019
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
network formation model
discrete event system
anomalous event detection
model tworzenia sieci
układ zdarzeń dyskretnych
wykrywanie anomalii
Opis:
Network models aim to explain patterns of empirical relationships based on mechanisms that operate under various principles for establishing and removing links. The principle of preferential attachment forms a basis for the well-known Barabási–Albert model, which describes a stochastic preferential attachment process where newly added nodes tend to connect to the more highly connected ones. Previous work has shown that a wide class of such models are able to recreate power law degree distributions. This paper characterizes the cumulative degree distribution of the Barabási–Albert model as an invariant set and shows that this set is not only a global attractor, but it is also stable in the sense of Lyapunov. Stability in this context means that, for all initial configurations, the cumulative degree distributions of subsequent networks remain, for all time, close to the limit distribution. We use the stability properties of the distribution to design a semi-supervised technique for the problem of anomalous event detection on networks.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2019, 29, 2; 363-373
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Semi-Markov-based approach for the analysis of open tandem networks with blocking and truncation
Autorzy:
Oniszczuk, W.
Powiązania:
https://bibliotekanauki.pl/articles/907864.pdf
Data publikacji:
2009
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
sieć komputerowa
blokowanie
obcinanie
model semi-Markova
two-node network
blocking
truncation
semi-Markov model
Markov exact algorithm
Opis:
This paper describes an analytical study of open two-node (tandem) network models with blocking and truncation. The study is based on semi-Markov process theory, and network models assume that multiple servers serve each queue. Tasks arrive at the tandem in a Poisson fashion at the rate [...], and the service times at the first and the second node are nonexponentially distributed with means sA and sB, respectively. Both nodes have buffers with finite capacities. In this type of network, if the second buffer is full, the accumulation of new tasks by the second node is temporarily suspended (a blocking factor) and tasks must wait on the first node until the transmission process is resumed. All new tasks that find the first buffer full are turned away and are lost (a truncation factor). First, a Markov model of the tandem is investigated. Here, a twodimensional state graph is constructed and a set of steady-state equations is created. These equations allow calculating state probabilities for each graph state. A special algorithm for transforming the Markov model into a semi-Markov process is presented. This approach allows calculating steady-state probabilities in the semi-Markov model. Next, the algorithms for calculating the main measures of effectiveness in the semi-Markov model are presented. In the numerical part of this paper, the author investigates examples of several semi-Markov models. Finally, the results of calculating both the main measures of effectiveness and quality of service (QoS) parameters are presented.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2009, 19, 1; 151-163
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A mathematical model for file fragment diffusion and a neural predictor to manage priority queues over BitTorrent
Autorzy:
Napoli, C.
Pappalardo, G.
Tramontana, E.
Powiązania:
https://bibliotekanauki.pl/articles/331212.pdf
Data publikacji:
2016
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
P2P model
neural network
wavelet
diffusion
file sharing
model P2P
sieć neuronowa
falka
dyfuzja
wymiana plików
Opis:
BitTorrent splits the files that are shared on a P2P network into fragments and then spreads these by giving the highest priority to the rarest fragment. We propose a mathematical model that takes into account several factors such as the peer distance, communication delays, and file fragment availability in a future period also by using a neural network module designed to model the behaviour of the peers. The ensemble comprising the proposed mathematical model and a neural network provides a solution for choosing the file fragments that have to be spread first, in order to ensure their continuous availability, taking into account that some peers will disconnect.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2016, 26, 1; 147-160
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An unsupervised approach to leak detection and location in water distribution networks
Autorzy:
Quiñones-Grueiro, M.
Verde, C.
Prieto-Moreno, A.
Llanes-Santiago, O.
Powiązania:
https://bibliotekanauki.pl/articles/330518.pdf
Data publikacji:
2018
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
water distribution network
leak location
unsupervised methods
principal component analysis
demand model
sieć wodociągowa
lokalizacja wycieku
analiza składników głównych
model popytu
Opis:
The water loss detection and location problem has received great attention in recent years. In particular, data-driven methods have shown very promising results mainly because they can deal with uncertain data and the variability of models better than model-based methods. The main contribution of this work is an unsupervised approach to leak detection and location in water distribution networks. This approach is based on a zone division of the network, and it only requires data from a normal operation scenario of the pipe network. The proposition combines a periodic transformation and a data vector extension together with principal component analysis of leak detection. A reconstruction-based contribution index is used for determining the leak zone location. The Hanoi distribution network is employed as the case study for illustrating the feasibility of the proposal. Single leaks are emulated with varying outflow magnitudes at all nodes that represent less than 2.5% of the total demand of the network and between 3% and 25% of the node’s demand. All leaks can be detected within the time interval of a day, and the average classification rate obtained is 85.28% by using only data from three pressure sensors.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2018, 28, 2; 283-295
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Efficient nonlinear predictive control based on structured neural models
Autorzy:
Ławryńczuk, M.
Powiązania:
https://bibliotekanauki.pl/articles/907652.pdf
Data publikacji:
2009
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
sterowanie procesami
sterowanie predykcyjne
sieć neuronowa
optymalizacja
linearyzacja
process control
model predictive control
neuron network
optimisation
linearisation
Opis:
This paper describes structured neural models and a computationally efficient (suboptimal) nonlinear Model Predictive Control (MPC) algorithm based on such models. The structured neural model has the ability to make future predictions of the process without being used recursively. Thanks to the nature of the model, the prediction error is not propagated. This is particularly important in the case of noise and underparameterisation. Structured models have much better long-range prediction accuracy than the corresponding classical Nonlinear Auto Regressive with eXternal input (NARX) models. The described suboptimal MPC algorithm needs solving on-line only a quadratic programming problem. Nevertheless, it gives closed-loop control performance similar to that obtained in fully-fledged nonlinear MPC, which hinges on online nonconvex optimisation. In order to demonstrate the advantages of structured models as well as the accuracy of the suboptimal MPC algorithm, a polymerisation reactor is studied.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2009, 19, 2; 233-246
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fault tolerance in networked control systems under intermittent observations
Autorzy:
Georges, J. P.
Theilliol, D.
Cocquempot, V.
Ponsart, J. C.
Aubrun, C.
Powiązania:
https://bibliotekanauki.pl/articles/930171.pdf
Data publikacji:
2011
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
przeciążenie sieci
sterowanie odporne na błędy
diagnostyka uszkodzeń
system sieciowy
model wielokrotny
network congestion
fault tolerant control
fault diagnosis
networked control system
interacting multiple model
Opis:
This paper presents an approach to fault tolerant control based on the sensor masking principle in the case of wireless networked control systems. With wireless transmission, packet losses act as sensor faults. In the presence of such faults, the faulty measurements corrupt directly the behaviour of closed-loop systems. Since the controller aims at cancelling the error between the measurement and its reference input, the real outputs will, in such a networked control system, deviate from the desired value and may drive the system to its physical limitations or even to instability. The proposed method facilitates fault compensation based on an interacting multiple model approach developed in the framework of channel errors or network congestion equivalent to multiple sensors failures. The interacting multiple model method involved in a networked control system provides simultaneously detection and isolation of on-line packet losses, and also performs a suitable state estimation. Based on particular knowledge of packet losses, sensor fault-tolerant controls are obtained by computing a new control law using fault-free estimation of the faulty element to avoid intermittent observations that might develop into failures and to minimize the effects on system performance and safety.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2011, 21, 4; 639-648
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Design of the state predictive model following control system with time-delay
Autorzy:
Wang, D.
Wu, S.
Okubo, S.
Powiązania:
https://bibliotekanauki.pl/articles/907660.pdf
Data publikacji:
2009
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
sterowanie predykcyjne
opóźnienie
kontrola przeciążeń
state predictive control
time delay
model following control system (MFCS)
TCP/AQM network
congestion control
Opis:
Time-delay systems exist in many engineering fields such as transportation systems, communication systems, process engineering and, more recently, networked control systems. It usually results in unsatisfactory performance and is frequently a source of instability, so the control of time-delay systems is practically important. In this paper, a design of the state predictive model following control system (PMFCS) with time-delay is discussed. The bounded property of the internal states for the control is given, and the utility of this control design is guaranteed. Finally, examples are given to illustrate the effectiveness of the proposed method, and state predictive control techniques are applied to congestion control synthesis problems for a TCP/AQM network.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2009, 19, 2; 247-254
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Reliability-based economic model predictive control for generalised flow-based networks including actuators’ health-aware capabilities
Autorzy:
Grosso, J. M.
Ocampo-Martinez, C.
Puig, V.
Powiązania:
https://bibliotekanauki.pl/articles/330080.pdf
Data publikacji:
2016
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
model predictive control
flow based network
dynamic safety stocks
actuator health
service reliability
chance constraints
economic optimisation
sterowanie predykcyjne
niezawodność serwisu
optymalizacja ekonomiczna
Opis:
This paper proposes a reliability-based economic model predictive control (MPC) strategy for the management of generalized flow-based networks, integrating some ideas on network service reliability, dynamic safety stock planning, and degradation of equipment health. The proposed strategy is based on a single-layer economic optimisation problem with dynamic constraints, which includes two enhancements with respect to existing approaches. The first enhancement considers chance-constraint programming to compute an optimal inventory replenishment policy based on a desired risk acceptability level, leading to dynamical allocation of safety stocks in flow-based networks to satisfy non-stationary flow demands. The second enhancement computes a smart distribution of the control effort and maximises actuators’ availability by estimating their degradation and reliability. The proposed approach is illustrated with an application of water transport networks using the Barcelona network as the case study considered.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2016, 26, 3; 641-654
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Forecasting models for chaotic fractional-order oscillators using neural networks
Autorzy:
Bingi, Kishore
Prusty, B Rajanarayan
Powiązania:
https://bibliotekanauki.pl/articles/2055150.pdf
Data publikacji:
2021
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
chaotic oscillators
data driven forecasting
fractional order system
model free analysis
neural network
time series prediction
oscylator chaotyczny
układ rzędu ułamkowego
sieć neuronowa
prognozowanie szeregów czasowych
Opis:
This paper proposes novel forecasting models for fractional-order chaotic oscillators, such as Duffing’s, Van der Pol’s, Tamaševičius’s and Chua’s, using feedforward neural networks. The models predict a change in the state values which bears a weighted relationship with the oscillator states. Such an arrangement is a suitable candidate model for out-of-sample forecasting of system states. The proposed neural network-assisted weighted model is applied to the above oscillators. The improved out-of-sample forecasting results of the proposed modeling strategy compared with the literature are comprehensively analyzed. The proposed models corresponding to the optimal weights result in the least mean square error (MSE) for all the system states. Further, the MSE for the proposed model is less in most of the oscillators compared with the one reported in the literature. The proposed prediction model’s out-of-sample forecasting plots show the best tracking ability to approximate future state values.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2021, 31, 3; 387--398
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-9 z 9

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