Maciej Ogorzalek

Identifiability and identification of chaotic systems based on adaptive synchronization

Keywords: chaos ; Non-Linear Signal Processing Reference LANOS-CONF-1997-015 Record created on 2004-12-03, modified on 2017-05-12

Global relative parameter sensitivities of the feed-forward loops in genetic networks

It is well known that the feed-forward loops (FFLs) are typical network motifs in many real world biological networks. The structures, functions, as well as noise characteristics of FFLs have received increasing attention over the last decade. This paper aims to further investigate the global relative parameter sensitivities (GRPS) of FFLs in genetic networks modeled by Hill kinetics by introducing a simple novel approach. Our results indicate that: (i) for the coherent FFLs (CFFLs), the most abundant type 1 configuration (C1) is the most globally sensitive to system parameters, while for the incoherent FFLs (IFFLs), the most abundant type 1 configuration (I1) is the least globally sensitive to system parameters; (ii) the less noisy of a FFL configuration, the more globally sensitive of this circuit to its parameters; and (iii) the most abundant FFL configurations are often either the least sensitive (robust) to system parameters variation (IFFLs) or the least noisy (CFFLs). Therefore, the above results can well explain the reason why FFLs are network motifs and are selected by nature in evolution. Furthermore, the proposed GRPS approach sheds some light on the potential real world applications, such as the synthetic genetic circuits, predicting the effect of interventions in medicine and biotechnology, and so on.

On symbolic dynamics of a chaotic second‐order digital filter

This paper presents a contribution to the symbolic analysis of fractal patterns exhibited by a second-order digital filter with modular adder overflow characteristic. We use symbolic dynamics for the analysis of phenomena encountered in the system. We present several new results concerning the existence of admissible sequences for periodic orbits in the filter. an efficient computational algorithm based on rigorous mathematical results presented in the paper enabled us to calculate sequences with long periods, thus allowing deeper understanding of the underlying mechanisms of complex behaviour encountered in the filter.

Hyperchaos, clustering and cooperative phenomena in CNN arrays composed of chaotic circuits

This paper presents a study of complex dynamic phenomena in arrays composed of interacting chaotic circuits. Such arrays are thought of as a new paradigm for signal processing. Depending on the connection strength between the cells the array can show disorganised hyperchaotic behavior or organised in a specific way coherent behavior which might be useful in information processing. Patterns of behavior depending on coupling values are studied in this paper. Chuas circuits are taken as standard chaotic cells.<<ETX>>

Computational Intelligence and Image Processing Methods for Applications in Skin Cancer Diagnosis

Digital photography provides new powerful diagnostic tools in dermatology. Dermoscopy is a special photography technique which enables taking photos of skin lesions in chosen lighting conditions. Digital photography allows for seeing details of the skin changes under various enlargements and coloring. Computer-assisted techniques and image processing methods can be further used for image enhancement and analysis and for feature extraction and pattern recognition in the selected images. Special techniques used in skin-image processing are discussed in detail. Feature extraction methods and automated classification techniques based on statistical learning and model ensembling techniques provide very powerful tools which can assist the doctors in taking decisions. Performance of classifiers will be discussed in specific case of melanoma cancer diagnosis. The techniques have been tested on a large data set of images.

Exploring chaos in Chua's circuit via unstable periodic orbits

Unstable periodic orbits inherently embedded in strange attractors provide a useful characterization of chaotic behavior. The authors analyze unstable periodic orbits existing in chaotic orbits in Chuas circuit. Uncovering such orbits is feasible and numerically tractable. Specific algorithms and programs have been developed for this purpose. Unstable periodic orbits provide not only information about the attractor geometry but can be further used for calculation of metric descriptors such as dimension or Lyapunov exponents, and can be treated as a basis for controlling chaos.<<ETX>>

Signal coding and compression based on chaos control techniques

This paper presents a new technique for signal coding and compression based on chaos control techniques. Given signal (e.g. speech or any other) recorded in a time interval is cut into smaller samples, further each of the sections is stored as a piece of a chaotic trajectory supplied by a chosen chaos generator (coder!). Effective techniques (based on a chaos control procedure) for finding initial conditions of the chaos generator to produce a desired shape of the output signal with a desired accuracy are described. In effect the signal to be coded/compressed can be stored as a set of points-initial conditions of the chosen chaos generator. Recovery of the original signal is straightforward: the stored initial conditions are applied to the coding chaos generator and the solutions taken in appropriate intervals are simply pieced together. Advantages and drawbacks of the proposed technique are discussed.

Extending Extensible Authentication Protocol over IEEE 802.15.4 Networks

Internet into our physical world and making it present everywhere. This evolution is also raising challenges in issues such as privacy, and security. For that reason, this work is focused on the integration and lightweight adaptation of existing authentication protocols, which are able also to offer authorization and access control functionalities. In particular, this work is focused on the Extensible Authentication Protocol (EAP). EAP is widely used protocol for access control in local area networks such Wireless (802.11) and wired (802.3). This work presents an integration of the EAP frame into IEEE 802.15.4 frames, demonstrating that EAP protocol and some of its mechanisms are feasible to be applied in constrained devices, such as the devices that are populating the IoT networks.

Computer-Aided 3D ICs Layout Design

Computer-aided 3D ICs layout design requires efficient search of large and discontinuous spaces and no deterministic algorithms are able to perform such a task. The paper presents a new framework for visual kind of intelligent layout design. In the proposed approach a shape grammar generates possible design solutions while intelligent algorithms control the direction of the solution space exploration. Although the method is not limited to a particular design assignment, the paper focuses on a 3D ICs layout problem to demonstrate its potential.

Semantic analysis of skin lesions using radial basis function neural networks

Artificial Neural Networks have been successfully applied to abroad spectrum of complex analysis problems. Computational intelligence is finding more and more applications in computer aided diagnostics, helping doctors to process large quantities of various medical data. In dermatology it is extremely difficult to perform automatic diagnostic differentiation of malignant melanoma based only on dermatoscopic images. Applying artificial intelligence algorithms to explore and search large database of dermatoscopic images allow doctors to semantically filter out image with specified characteristics. This paper presents an approach for characteristic objects classification found in image database of pigment skin lesions, based on radial basis function kernel for artificial neural networks.