Alexander R. Volkovskii
University of California, San Diego
Network
Latest external collaboration on country level. Dive into details by clicking on the dots.
Publication
Featured researches published by Alexander R. Volkovskii.
IEEE Transactions on Circuits and Systems I-regular Papers | 2000
Mikhail M. Sushchik; Lev S. Tsimring; Alexander R. Volkovskii
Using chaotic signals in spread-spectrum communications has a few clear advantages over traditional approaches. Chaotic signals are nonperiodic, wideband, and more difficult to predict, reconstruct, and characterize than periodic carriers. These properties of chaotic signals make it more difficult to intercept and decode the information modulated upon them. However, many suggested chaos-based communication schemes do not provide processing gain, a feature highly desirable in spread-spectrum communication schemes. In this paper, we suggest two communication schemes that provide a processing gain. The performance of these and of the earlier proposed differential chaos shift keying is studied analytically and numerically for discrete time implementations. It is shown that, when performance is characterized by the dependence of bit error rate on E/sub b//N/sub 0/, the increase of the spreading sequence length beyond a certain point degrades the performance. For a given E/sub b//N/sub 0/, there is a length of the spreading sequence that minimizes the bit error rate.
Archive | 2001
Henry D. I. Abarbanel; R. Huerta; P. Lecanda; Mikhail I. Rabinovich; Alexander R. Volkovskii
Following studies of olfactory processing in insects and fish, we investigate neural networks whose dynamics in phase space is represented by orbits near the heteroclinic connections between saddle regions (fixed points or limit cycles). These networks encode input information as trajectories along the heteroclinic connections. If there are N neurons in the network, the capacity is approximately e(N-1)!, i.e., much larger than that of most traditional network structures. We show that a small winnerless competition network composed of FitzHugh-Nagumo spiking neurons efficiently transforms input information into a spatiotemporal output.
IEEE Communications Letters | 2000
Mikhail M. Sushchik; Nikolai F. Rulkov; Lawrence E. Larson; Lev S. Tsimring; Henry D. I. Abarbanel; Kung Yao; Alexander R. Volkovskii
In this letter we investigate a communication strategy for digital ultra-wide bandwidth impulse radio, where the separation between the adjacent pulses is chaotic arising from a dynamical system with irregular behavior. A pulse position method is used to modulate binary information onto the carrier. The receiver is synchronized to the chaotic pulse train, thus providing the time reference for information extraction. We characterize the performance of this scheme in terms of error probability versus E/sub b//N/sub 0/ by numerically simulating its operation in the presence of noise and filtering.
Physical Review E | 2000
Reynaldo D. Pinto; Pablo Varona; Alexander R. Volkovskii; Attila Szücs; Henry D. I. Abarbanel; Michail I. Rabinovich
We report on experimental studies of synchronization phenomena in a pair of analog electronic neurons (ENs). The ENs were designed to reproduce the observed membrane voltage oscillations of isolated biological neurons from the stomatogastric ganglion of the California spiny lobster Panulirus interruptus. The ENs are simple analog circuits which integrate four-dimensional differential equations representing fast and slow subcellular mechanisms that produce the characteristic regular/chaotic spiking-bursting behavior of these cells. In this paper we study their dynamical behavior as we couple them in the same configurations as we have done for their counterpart biological neurons. The interconnections we use for these neural oscillators are both direct electrical connections and excitatory and inhibitory chemical connections: each realized by analog circuitry and suggested by biological examples. We provide here quantitative evidence that the ENs and the biological neurons behave similarly when coupled in the same manner. They each display well defined bifurcations in their mutual synchronization and regularization. We report briefly on an experiment on coupled biological neurons and four-dimensional ENs, which provides further ground for testing the validity of our numerical and electronic models of individual neural behavior. Our experiments as a whole present interesting new examples of regularization and synchronization in coupled nonlinear oscillators.
Neuroreport | 2000
Attila Szücs; Pablo Varona; Alexander R. Volkovskii; Henry D. I. Abarbanel; Mikhail I. Rabinovich; Allen I. Selverston
Small assemblies of neurons such as central pattern generators (CPG) are known to express regular oscillatory firing patterns comprising bursts of action potentials. In contrast, individual CPG neurons isolated from the remainder of the network can generate irregular firing patterns. In our study of cooperative behavior in CPGs we developed an analog electronic neuron (EN) that reproduces firing patterns observed in lobster pyloric CPG neurons. Using a tuneable artificial synapse we connected the EN bidirectionally to neurons of this CPG. We found that the periodic bursting oscillation of this mixed assembly depends on the strength and sign of the electrical coupling. Working with identified, isolated pyloric CPG neurons whose network rhythms were impaired, the EN/biological network restored the characteristic CPG rhythm both when the EN oscillations are regular and when they are irregular.
international symposium on circuits and systems | 2004
Young-Jun Lee; Jihyun Lee; Yong-Bin Kim; Joseph Ayers; Alexander R. Volkovskii; Allen I. Selverston; Henry D. I. Abarbanel; Mikhail I. Rabinovich
We discuss a VLSI electronic neuron circuit that implements the Hindmarsh and Rose neuron model. Magnitude and time scaling techniques are employed for a 2 V power supply operation. A subthreshold operation technique and a single MOS resistor are used to minimize area and power consumption. Output bursts of the electronic neuron can be modulated dynamically by varying the input voltage level. The circuit is designed using a 0.25 /spl mu/m CMOS standard process, and the total power dissipation is 163.4 /spl mu/watt.
Physics Letters A | 1993
Nikolai F. Rulkov; Alexander R. Volkovskii
Abstract A new type of synchronized chaos conditioned by the threshold synchronization of relaxation oscillators with chaotic behaviour is studied experimentally. It is shown that for a certain parameter ratio the pulses generated by the chaotic oscillator may be synchronized by periodic and chaotic pulse sequences generated by the drive oscillator. It is found that the threshold synchronization regime enables one to detect modulation of chaotic signals.
IEEE Transactions on Circuits and Systems I-regular Papers | 2001
Nikolai F. Rulkov; Alexander R. Volkovskii
In this paper, we discuss fundamentals for the design of a source of chaotic signals based on a blocking oscillator circuit. We study a modification of a well-known circuit of blocking oscillator which leads to the onset of chaotic oscillations. The output signal of such chaotic oscillator is a series of short term pulses characterized by chaotic fluctuations of time intervals between pulses. Such chaotic pulse signals possess a broad-band continuous power spectrum and short correlation length. We discuss the results of theoretical and experimental studies of nonlinear dynamics of the chaotic blocking oscillator.
Applied Bionics and Biomechanics | 2010
Joseph Ayers; Nikolai F. Rulkov; Dan Knudsen; Yong-Bin Kim; Alexander R. Volkovskii; Allen I. Selverston
We are developing robot controllers based on biomimetic design principles. The goal is to realise the adaptive capabilities of the animal models in natural environments. We report feasibility studies of a hybrid architecture that instantiates a command and coordinating level with computed discrete-time map-based DTM neuronal networks and the central pattern generators with analogue VLSI Very Large Scale Integration electronic neuron aVLSI networks. DTM networks are realised using neurons based on a 1-D or 2-D Map with two additional parameters that define silent, spiking and bursting regimes. Electronic neurons ENs based on Hindmarsh--Rose HR dynamics can be instantiated in analogue VLSI and exhibit similar behaviour to those based on discrete components. We have constructed locomotor central pattern generators CPGs with aVLSI networks that can be modulated to select different behaviours on the basis of selective command input. The two technologies can be fused by interfacing the signals from the DTM circuits directly to the aVLSI CPGs. Using DTMs, we have been able to simulate complex sensory fusion for rheotaxic behaviour based on both hydrodynamic and optical flow senses. We will illustrate aspects of controllers for ambulatory biomimetic robots. These studies indicate that it is feasible to fabricate an electronic nervous system controller integrating both aVLSI CPGs and layered DTM exteroceptive reflexes.
Chaos Solitons & Fractals | 1994
Nikolai F. Rulkov; Alexander R. Volkovskii; A. Rodriguez-Lozano; Ezequiel del Río; Manuel G. Velarde
Abstract Synchronization of chaotic self-excited oscillations and chaotic synchronous response are studied using chaotic electronic oscillators with unidirectional coupling.