S.G. Stavrinides

THE INTERMITTENCY ROUTE TO CHAOS OF AN ELECTRONIC DIGITAL OSCILLATOR

An electronic oscillator producing digital signals, formed by a second-order, nonlinear, nonautonomous, closed loop topology that is based on two integrators and nonlinear elements (a comparator and a XOR gate), was experimentally investigated. For a certain frequency and amplitude range of the periodic driving signal, the intermittency route to chaos was observed and studied.

An Automated Acquisition Setup for the Analysis of Chaotic Systems

The design and implementation of an acquisition setup dedicated to the experimental evaluation and characterization of chaotic electronic circuits is presented. The whole setup was created using National Instruments Labview environment and it is structured in a way that it is independent of the devices used for the experimental recording of the necessary data. Next to the signals power spectrum, the embedding and correlation dimensions are calculated as well as the Kolmogorov entropy. The last two can lead to conclusions about a circuits performance in a periodic or chaotic mode.

Chaos and Complex Systems

Springer Complexity is an interdisciplinary program publishing the best research and academiclevel teaching on both fundamental and applied aspects of complex systems – cutting across all traditional disciplines of the natural and life sciences, engineering, economics, medicine, neuroscience, social and computer science. Complex Systems are systems that comprise many interacting parts with the ability to generate a new quality of macroscopic collective behavior the manifestations of which are the spontaneous formation of distinctive temporal, spatial or functional structures. Models of such systems can be successfully mapped onto quite diverse “real-life” situations like the climate, the coherent emission of light from lasers, chemical reaction-diffusion systems, biological cellular networks, the dynamics of stock markets and of the internet, earthquake statistics and prediction, freeway traffic, the human brain, or the formation of opinions in social systems, to name just some of the popular applications. Although their scope and methodologies overlap somewhat, one can distinguish the following main concepts and tools: self-organization, nonlinear dynamics, synergetics, turbulence, dynamical systems, catastrophes, instabilities, stochastic processes, chaos, graphs and networks, cellular automata, adaptive systems, genetic algorithms and computational intelligence. The three major book publication platforms of the Springer Complexity program are the monograph series “Understanding Complex Systems” focusing on the various applications of complexity, the “Springer Series in Synergetics”, which is devoted to the quantitative theoretical and methodological foundations, and the “SpringerBriefs in Complexity” which are concise and topical working reports, case-studies, surveys, essays and lecture notes of relevance to the field. In addition to the books in these two core series, the program also incorporates individual titles ranging from textbooks to major reference works.

The Route from Synchronization to Desynchronization of Chaotic Operating Circuits and Systems

In a world of an ever increasing information-trafficking, ultra wideband information transmission, as well as security are main issues. Chaotic oscillators inherently possess these two properties. Consequently, chaotic transmitter-receiver synchronization emerges as a key-topic in networked communication. The issues of synchronization robustness and synchronization stability are of great importance, if one means to turn in advantage properties of chaotic operating circuits and systems. As a result, not only synchronization accomplishment but also the ways a system desynchronizes is of great importance, if not crucial; however, these are not, usually, thoroughly studied. In this contribution a short overview of experimental work dedicated to the ways chaotic-synchronized communication systems desynchronize, is provided.

Using modern RF tools to detect chaotic behaviour of electronic circuits and systems

In this paper, a new approach in identifying chaotic behaviour of nonlinear circuits is presented. This approach could be very useful to circuit designers, whether they pursue a chaotic behaviour or not. Simulation tools used for radio-frequency circuit design (Cadence SpectreRF), initially developed to characterise harmonic oscillators, are now utilised to detect chaotic behaviour, as well as routes to chaotic mode of operation. Specifically, Periodic Steady State Convergence Norm is used for the first time for chaos detection in circuits. The advantages of this method (especially in terms of simulation time) are presented, together with an example of detection of chaotic route to chaos in the case of a chaotic-operating Colpitts oscillator.

An automated acquisition setup for the evaluation of intermittency statistics

The design and realization of an automated acquisition setup, dedicated to experimental evaluation of intermittent chaotic phenomena and the related statistics, is presented. The setup was implemented in National Instruments LabView environment and it was structured in such a way that it is not dependent of the signal-registering devices used. The circuit evaluation is achieved by registering only one signal. An experimental intermittency example confirms the systems effectiveness.

A Digital Nonautonomous Chaotic Oscillator Suitable for Information Transmission

In this brief, an all-digital chaotic operating electronic circuit, which is suitable for information modulation and chaotic transmission, is introduced. The chaotic oscillating circuit is a nonautonomous one, and it is designed in such a way that signals at all stages are digital ones. No analog subcircuit is involved in generating chaos. Oscillator design and experimental demonstration of its chaotic behavior are provided, together with the evaluation of the chaotic properties that it possesses, employing established nonlinear dynamics tools.

Multi-state memristive nanocrossbar for high-radix computer arithmetic systems

The recent discovery of memristor, a device able to store multi-bit values in a single cell, has renewed the interest for fast arithmetic operations via high-radix numeric systems. This work presents a conceptual solution for CMOS-compatible, high-radix memristive arithmetic logic units (ALUs). The latter, combine CMOS circuitry for data processing with a reconfigurable, multi-level, memristive nanocrossbar memory, which allows the compact, high-radix storage of numbers. Certain modifications introduced to the typical crossbar topology permit the parallel creation of partial products for faster multiplication. High-radix to binary data conversion is performed via a network of comparators. A simulation-based validation of read/write operations from/to a multi-level memristive crossbar was performed using SPICE and a threshold-type model of a voltage-controlled bipolar memristor.

Impulsive Synchronization Between Double-Scroll Circuits

Two identical, double-scroll circuits, in their chaotic mode of operation, are unidirectionally connected via an externally triggered electronic switch. Thus, the case of impulsive synchronization is established. Their synchronization and its dependence on the switch on-off frequency and duty cycle is demonstrated.

An Autonomous Mobile Robot Guided by a Chaotic True Random Bits Generator

In this work a robot’s controller, which ensures chaotic motion to an autonomous mobile robot, is presented. This new strategy, which is very useful in many robotic missions, generates an unpredictable trajectory by using a chaotic path planning generator. The proposed generator produces a trajectory, which is the result of a sequence of planned target locations. In contrary with other similar works, this one is based on a new chaotic true random bits generator, which has as a basic feature the coexistence of two different synchronization phenomena between mutually coupled identical nonlinear circuits. Simulation tests confirm that the whole robot’s workplace is covered with unpredictable way in a very satisfactory time.