Un modèle d'approximation de diffusion pour la distribution du temps d'acheminement des paquets dans les réseaux de senseurs

Nous proposons un modèle qui s'appuie sur l'approximation de diffusion pour l'estimation de la fonction de densité de probabilité du temps d'acheminement des paquets dans un réseaux de senseurs sans fils à sauts multiples. Dans sa forme générale, le modèle tient compte d'une part de la non homogénéité du milieu de propagation et de la répartition des noeuds intermédiaires dans l'espace et d'autre part, des éventuels changements des caractéristiques du réseau dans le temps. La retransmission des paquets perdus est également pris en compte dans le modèle

The fluid flow approximation of the TCP vegas and reno congestion control mechanism

TCP congestion control algorithms have been design to improve Internet transmission performance and stability. In recent years the classic Tahoe/Reno/NewReno TCP congestion control, based on losses as congestion indicators, has been improved and many congestion control algorithms have been proposed. In this paper the performance of standard TCP NewReno algorithm is compared to the performance of TCP Vegas, which tries to avoid congestion by reducing the congestion window (CWND) size before packets are lost. The article uses fluid flow approximation to investigate the influence of the two above-mentioned TCP congestion control mechanisms on CWND evolution, packet loss probability, queue length and its variability. Obtained results show that TCP Vegas is a fair algorithm, however it has problems with the use of available bandwidth

On stochastic models of internet traffic

The paper discusses various models of self-similar Internet traffic and techniques for estimating the intensity of Long-Range Dependence (LRD). In the experimental part real data sets collected in IITiS PAN are used together with synthetic LRD flows generated using Fractional Gaussian noise and Markov modulated Poisson processes. We are especially interested in Markov models since they can be incorporated in Markov queueing models, for which powerful analytical and numerical techniques are availabl

Fluid-Flow Approximation in the Analysis of Vast Energy-Aware Networks

The paper addresses two issues: (i) modeling dynamic flows transmitted in vast TCP/IP networks and (ii) modeling the impact of energy-saving algorithms. The approach is based on the fluid-flow approximation, which applies first-order differential equations to analyze the evolution of queues and flows. We demonstrate that the effective implementation of this method overcomes the constraints of storing large data in numerical solutions of transient problems in vast network topologies. The model is implemented and executed directly in a database system. It can analyze transient states in topologies of more than 100,000 nodes, i.e., the size which was not considered until now. We use it to investigate the impact of an energy-saving algorithm on the performance of a vast network. We find that it reduces network congestion and save energy costs but significantly lower network throughput

Modelowanie dynamiki przesyłów TCP/IP z uwzględnieniem mechanizmu RED

The paper presents the results of modeling of selected modern computer networks scenarios. The study used a mathematical model of fluid flow approximation, describing the effects of time varying packet traffic on the network switches and packet loss generation by the assumptions of the RED mechanism used in routers. The carried out experiments included the influence of the parameters initial settings on the behavior of a whole system.W pracy przedstawiono wyniki modelowania wybranych scenariuszy współczesnych sieci komputerowych. W badaniach zastosowano model matematyczny aproksymacji fluid flow, opisujący wpływ zmiennego w czasie natężenia ruchu pakietów na przełączniki sieciowe i generowanie strat pakietowych, zgodnie z założeniami mechanizmu RED stosowanego w routerach. Przeprowadzone doświadczenia obejmowały wpływ początkowych ustawień parametrów na zachowanie układu

Man-machine interactions 3

Man-Machine Interaction is an interdisciplinary field of research that covers many aspects of science focused on a human and machine in conjunction.  Basic goal of the study is to improve and invent new ways of communication between users and computers, and many different subjects are involved to reach the long-term research objective of an intuitive, natural and multimodal way of interaction with machines.  The rapid evolution of the methods by which humans interact with computers is observed nowadays and new approaches allow using computing technologies to support people on the daily basis, making computers more usable and receptive to the user's needs.   This monograph is the third edition in the series and presents important ideas, current trends and innovations in  the man-machine interactions area.  The aim of this book is to introduce not only hardware and software interfacing concepts, but also to give insights into the related theoretical background. Reader is provided with a compilation of high-quality original papers covering a wide scope of research topics divided into elven sections,  namely: human-computer interactions, robot control,  embedded and navigation systems, bio data analysis and mining, biomedical signal  processing, image and sound processing, decision support and expert systems, rough and fuzzy systems, pattern recognition, algorithms and optimization, computer networks and mobile technologies and data management systems

Diffusion Model of an ATM Network Node

International audienc

4th International Conference on Man–Machine Interactions

This book provides an overview of the current state of research on development and application of methods, algorithms, tools and systems associated with the studies on man-machine interaction. Modern machines and computer systems are designed not only to process information, but also to work in dynamic environment, supporting or even replacing human activities in areas such as business, industry, medicine or military. The interdisciplinary field of research on man-machine interactions focuses on broad range of aspects related to the ways in which human make or use computational artifacts, systems and infrastructure.   This monograph is the fourth edition in the series and presents new concepts concerning analysis, design and evaluation of man-machine systems. The selection of high-quality, original papers covers a wide scope of research topics focused on the main problems and challenges encountered within rapidly evolving new forms of human-machine relationships. The presented material is structured into following sections: human-computer interfaces, robot, control, embedded and navigation systems, bio-data analysis and mining, biomedical signal processing, image and motion data processing, decision support and expert systems, pattern recognition, fuzzy systems, algorithms and optimisation, computer networks and mobile technologies, and data management systems

The use of a non-integer order PI controller with an active queue management mechanism

In this paper the performance of a fractional order PI controller is compared with that of RED, a well-known active queue management (AQM) mechanism. The article uses fluid flow approximation and discrete-event simulation to investigate the influence of the AQM policy on the packet loss probability, the queue length and its variability. The impact of self-similar traffic is also considered