Using Markov chains for modelling networks

The paper contains the review and the discussion on modelling communication networks with the use of queuing models and Markov chains. It shows how to take into account various characteristics of real systems - like some control mechanisms and the traffic self-similarity. There are presented two mechanisms modelled with Markov chains: the RED algorithm in TCP/IP and a self-similar traffic shaping

Multi-class 3D region growing algorithm

This paper describes generalization of multi-class region growing algorithm allowing for segmentation of 3D images (series of slices). The multi-class region growing algorithm was proposed in [1]. Additionally, a new method for finding the start region was presented. As its 2D version the new algorithm does not need initial parameters since it features segmentation quality assessment. A series of segmentations is performed on a dataset, each segmentation quality is assessed and the best one is picked. Additionally, the number of classes in the image is determined automatically. The multi-class 3D region growing algorithm is tested on CT and MRI scans. Different types of MRI scans are used. The scans come from multiple sources. The results are shown in the form of 3D reconstruction accompanied by a selected 2D slice. In addition, such selected algorithm performance issues are discussed as effective algorithm implementation; fast dilation implementation is also mentioned. The paper explains all concepts and operations used by the algorithm. It includes numerous figures and algorithm pseudo-code descriptions

Parallelization of the Tarticle-in-CelP (PIC) density calculations in plasma computer simulations

The paper deals with the problem of parallelized Particle-In-Cell charge density calculations used in computer plasma simulation. The dependencies between the execution time and the simulation parameters such as the number of 'macro particles', plasma density, particular charge distribution technique and the number of processing units are presented. The local computer cluster and MPI standard have been used in order to parallelize calculations

Computer network traffic analysis with the use of statistical self-similarity factor

The optimal computer network performance models require accurate traffic models, which can capture the statistical characteristic of actual traffic. If the traffic models do not represent traffic accurately, one may overestimate or underestimate the network performance. The paper presents confirmation of the self-similar nature of the selected protocols in the computer network communication layer. It shows that the good measure of self-similarity is a Hurst factor

The XML interoperability and the Polish Energy Market needs

There are only a few months from the Polish Energy Market openning. This subject, especially in the face of the last political confusion about the natural gas delivery has been a topic of many publications and speeches of politicians during the last months. But, besides this medial outcry, well working and flexible Polish Energy Market, as it is planned, is a very complex problem to solve, and there are many tasks to be done before the 1 July 2007 [1]. In this work the author focuses on the aspects of information flow coordination between the end-users (consumers of energy) and other participants (generators, transmitters, wholesale resellers - the players) of the Polish Energy System. In this article there will be described a concept of two direct electronic data exchange between the energy measure unit located at let's say Kowalsky's house, and any other computer systems of the player

A hybrid approach to segmentation of medical images

The paper presents information theory based image segmentation algorithms. Both advantages and problems related to them are discussed. Then a segmentation framework based on combination of information theory and fuzzy logic is proposed

The use of self-organising maps to investigate heat demand profiles

District heating companies are responsible for delivering the heat produced in central heat plants to the consumers through a pipeline system. At the same time they are expected to keep the total heat production cost as low as possible. Therefore, there is a growing need to optimise heat production through better prediction of customers needs. The paper illustrates the way neural networks, namely self-organised maps can be used to investigate long-term demand profiles of consumers. Real-life historical sales data is used to establish a number of typical demand profiles

Computer modelling of the decay of atomic compound nuclei

We present numerical algorithm which describes the decay of hot, rotating compound nuclei. This algorithm treats the fission dynamics in conjunction with light-particle (n, p, a) evaporation. The detailed results are given for the n%Pt nucleus at the excitation energy of 100 MeV

The role of local optimizations in evolutionary process of atomic clusters modeling

The application of genetic algorithms in a physical problem of modeling of isolated atomic clusters is the topic of our research. Evolutionary algorithms are a mechanism of the global optimization learning about the solution of the search space. This mechanism plays the role of giving the candidates to global optima. We can use the local optimization in the evolutionary process to improve the efficiency of our algorithm. The goal of our work is evaluation of the influence of the local optimization methods (type of simple gradient) on the growing of the efficiency and accuracy of the evolutionary process in optimization of atomic clusters modeling

The LubMedNet services for data storage and télédistribution

This paper is reports several Radiological and Oncological Information Systems integrated by a very efficient medical network system. The system covers the entire image flowpath in the Diagnostic Radiology Department (i.e. image acquisition, processing, archiving, long term storage) and allows for transmitting medical images through Municipal Area Network. The system has been working reliably since November 1999. About 22000 CT examinations have been archived using our system. Over 300 special examinations for radiotherapy planning have been sent to the Lublin Oncology Centre