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The problem of creating a receiver for incoherent microwave radiation from sources realized on the basis of ultra-wideband oscillators of chaotic oscillations and objects and surfaces "illuminated" by these sources has been considered. The structure of the device is proposed, the experimental sample is described, and its ability to register sources of incoherent microwave radiation with an integrated output power of ~2 mW at a distance of more than 100 m is shown. [ABSTRACT FROM AUTHOR]

A diagnostic technique is proposed for the mode of generalized synchronization in systems with a complex chaotic attractor topology based on consideration of tubes of trajectories in the phase space of interacting systems. The method functionality is tested by the numerical simulation of two mutually coupled modified Lorentz systems: one in the chaotic state, and another in the hyperchaotic state. The results are compared to the data obtained by calculating the Lyapunov exponent spectrum and show good agreement. [ABSTRACT FROM AUTHOR]

An experimental investigation of the multipath propagation of ultrawideband (UWB) microwave chaotic radio pulses in a wireless channel has been carried out. Based on the results of measurements, conditions of receiving chaotic radio pulses upon passage via a multipath channel are established for various signal delay times. [ABSTRACT FROM AUTHOR]

We present experimental data on the development of chaotic oscillations in a nonautonomous magnetoacoustic oscillator based on a hybrid magnetoacoustic resonator of the reflection type. The proposed oscillator exhibits regimes of quasi-periodic and chaotic generation under an external low-frequency periodic force. The chaotic dynamics of the magnetoacoustic oscillator is caused by the presence of delay and bistability in the system. [ABSTRACT FROM AUTHOR]

The task of wideband illumination of objects and surfaces by radiation from artificial noncoherent microwave sources with the aim of subsequent observation by radiometric equipment is considered. The main problem in solving this task consists in creating efficient microwave generators analogous to available sources of lighting in the visible spectral range. We propose to use generators of ultrawideband chaotic oscillations as sources of noncoherent microwave radiation. An experimental prototype of this source taking the form of a SiGe-crystal-based microgenerator of dynamic chaos is described. [ABSTRACT FROM AUTHOR]

Correlation characteristics of chimera states have been calculated using the coefficient of mutual correlation of elements in a closed-ring ensemble of nonlocally coupled chaotic maps. Quantitative differences between the coefficients of mutual correlation for phase and amplitude chimeras are established for the first time. [ABSTRACT FROM AUTHOR]

The transition from coherence to incoherence in an ensemble of nonlocally coupled logistic maps is considered. Chimera states of two types (amplitude and phase) are found. The mechanism and conditions of their appearance are determined. [ABSTRACT FROM AUTHOR]

A method of transmitting information with the expansion of the spectrum based on spectral interference between the reference noise and the information noise signal with a delay of different time according to the stream of binary bits is proposed. The occurrence of intrasystem noises with a shift in evaluation of the autocorrelation effect at the output of a two-channel correlation receiver is found. The possibility of noise-resistant transmission of information during spectral modulation as a result of the superposition of completely incoherent ultrawideband noise chaotic signals is shown. [ABSTRACT FROM AUTHOR]

A new technique of manipulating with fullerene C over graphene on a SiO substrate is proposed. To stop the chaotic motion of molecules and limit its range, it is suggested to use a corrugated substrate. The study has shown that, at the corrugation wavelength of 3.4 nm and depth of 1.6 nm, the fullerene motion becomes directed with a deviation within 0.5 nm. The fullerene motion becomes even more definite, with a deviation from a straight line within tenths of an angstrom by the action of an external electric field, which allows one to manipulate the motion along the bottom of a groove. The method proposed can serve as a basis for the controlled assembly of molecules to supermolecular structures of given configurations, which can be applied in bio- and nanoelectronics. [ABSTRACT FROM AUTHOR]

We propose a method of controlling an ensemble of mobile agents with variable coupling topology that is based on the principles of phase synchronization in a system of regular and chaotic oscillators. Results of modeling of the controlled motion of mobile agents in systems with serial, parallel, and strictly preset motion are presented. [ABSTRACT FROM AUTHOR]

We present results of an experimental investigation of the transition to a microwave dynamic chaos regime in ring oscillators based on normally magnetized yttrium iron garnet (YIG) films. It is established that an increase in the ring gain leads to the sequential generation of monochromatic, periodic, quasi-periodic, and chaotic signals. The quasi-periodic regime is characterized by the appearance of secondary modulation of the signal amplitude. In the regime of dynamic chaos generation, the parameters can be controlled by gain of the ring. [ABSTRACT FROM AUTHOR]

A method for the reconstruction of the architecture, strength of couplings, and parameters of elements in ensembles of coupled time-delay systems from their time series is proposed. The effectiveness of the method is demonstrated on chaotic time series of the ensemble of diffusively coupled nonidentical Ikeda equations in the presence of noise. [ABSTRACT FROM AUTHOR]

The character of a boundary of the domain of generalized synchronization (GS) regime has been studied for a system of three chaotic oscillators, two which are unidirectionally coupled with the third. It is established that the position of the GS boundary on the plane of coupling parameters is determined by the detuning of frequencies of the interacting chaotic oscillators. The character of this arrangement is explained in the framework of the modified system approach. [ABSTRACT FROM AUTHOR]

A prototype of an ultrawideband (UWB) microwave chaos generator based on a nonlinear spin-wave transmission line, a multistage transistor amplifier with an output amplifier based on GaAs field-effect transistors, and a microstrip bandpass filter was constructed. The possibility of autonomous generation of a UWB chaotic microwave signal with a central frequency of 3 GHz and a total power of about 4 W in a frequency band exceeding 30% was demonstrated. The proposed chaos generator is characterized by a fairly high efficiency of about 20%. [ABSTRACT FROM AUTHOR]

A method for increasing the accuracy of estimation of the predictability time of noisy chaotic dynamics from system-related point sequences is proposed. General laws observed in the application of this method to interspike interval series of model threshold devices of two types operating in the regime of phase-coherent chaos are illustrated. [ABSTRACT FROM AUTHOR]

A promising type of ultrawideband (UWB) signals for communications and radar techniques operating in an unlicensed frequency range of 3.1-10.6 GHz, which has been actively developed in recent years, is offered by chaotic oscillations. We have designed and studied a chaotic oscillator with a uniform distribution of spectral power density in the range of 3-8 GHz. The possibility of using these oscillators in multiband UWB communication systems and noise generators for radio-engineering measurements is discussed. [ABSTRACT FROM AUTHOR]

A new scheme of incoherent reception of chaotic radio pulses using a reference chaos generator is described. Analysis of the proposed scheme confirms its performance and efficiency. The scheme exhibits selectivity and can be used for separating pulses generated by several sources. [ABSTRACT FROM AUTHOR]

This Letter reports the development of a directly chaotic communication system, in which chaos generators are used that are based on yttrium-iron garnet (YIG) films. YIG-based chaos generators provide a stable chaotic synchronous response and almost ideal masking of the signal with high communication reliability and quality. Characteristics of these generators are compared with conventional chaos generators. [ABSTRACT FROM AUTHOR]

A new approach to analysis of the synchronization of chaotic oscillations in two (or more) coupled oscillators is described that makes it possible to reveal changes in the structure of attractors and detect the appearance of intermittency. The proposed method is based on a symbolic analysis developed previously in the velocity-curvature space of multidimensional sequences and maps. The method is tested by application to a Lorentz system. The results confirm the informativity of the analyzer and reveal specific features of changes in the structure of an attractor of the three-component test system. [ABSTRACT FROM AUTHOR]

A new method of symbolic analysis based on finite discretization of velocity-curvature space is proposed. A minimum alphabet is introduced in a natural way, and a number of initial analytic measures are defined that make it possible to study the structure of discrete mapping dynamics. The proposed method is tested by application to a system of two unidirectionally coupled logistic maps. It is shown that this method can be used to reveal and study changes in the structure of attractors. In the given example, features in the attractor structure of the driven subsystem are studied upon its escape from the identical synchronization regime. [ABSTRACT FROM AUTHOR]

Time series of chaotic oscillations have been observed for the first time in an auto-oscillator for the 8-mm wavelength range based on an avalanche transit-time diode. The noise generator based on this diode has been used as a signal source for a noise radar prototype. [ABSTRACT FROM AUTHOR]

We present the results of a comparative study of the chaotic generation of parametric spin waves in yttrium-iron garnet (YIG) films grown from a standard solution melt and in the films grown from a weakly dissociated solution melt containing garnet ferrite and orthoferrite clusters. It is shown that the efficiency of magnetic chaos generation is significantly higher in the latter case. [ABSTRACT FROM AUTHOR]

Generation of chaotic dissipative solitons has been observed in an active ring resonator with one-dimensional periodic ferromagnetic microstructure comprising a single-crystalline film of yttrium iron garnet (YIG) with a lattice of grooves oriented perpendicular to the direction of propagation of a magnetostatic surface wave (MSSW). A quasi-periodic train of chaotic dissipative solitons was generated in this system under the conditions of three-magnon processes of MSSW decay due to the passive synchronization (PS) of spin wave self-modulation in a frequency band corresponding to the first bandgap. The PS onset was caused by the saturable absorption of microwave signals within the bandgap of the MSSW transmission line. [ABSTRACT FROM AUTHOR]

The features of induced synchronization of a Chua oscillator with a nonlinear element admitting cubic approximation have been numerically simulated for a system where the autonomous operation admits regular or chaotic regimes determined by losses in the oscillatory circuit. The cases of deterministic synchronization (under the action of a harmonic external driving signal) and chaotic synchronization (chaotic control) have been considered. It is established that, outside the band of synchronous oscillations that corresponds to the deterministic synchronization, the external harmonic signal stimulates the transformation of regular oscillations into chaos with the motions switched between two attractors. In cases of chaotic synchronization, there is a residual 'noise' in the form of differential chaotic oscillations, which grows with increasing non-identity of the driving and driven signals. [ABSTRACT FROM AUTHOR]

Transient processes in a chain of nonidentical Chua oscillators resistively coupled via nonlinear elements admitting cubic approximation have been numerically simulated in cases of mutual and unidirectional coupling. It is demonstrated that the transient processes during both mutual and induced (unidirectional) chaotic synchronization are enhanced with increasing detuning between the oscillatory circuits of partial subsystems and suppressed with increasing coefficient of coupling. The time of establishment of a synchronous operation regime in the case of mutual coupling is, under otherwise identical conditions, shorter than in the case of unidirectional coupling. The dependence of the duration of establishment of a synchronous operation regime on the moment of coupling switch-on is considered. [ABSTRACT FROM AUTHOR]

A method for the quantitative analysis of the degree and parameters of synchronization of the chaotic oscillations in two coupled oscillators is proposed, which makes it possible to reveal a change in the structure of attractors. The proposed method is tested on a model system of two unidirectionally coupled logistic maps. It is shown that the method is robust with respect to both the presence of a low-intensity noise and a nonlinear distortion of the analyzed signal. Specific features of a rearranged structure of the attractor of a driven subsystem in the example under consideration have been studied. [ABSTRACT FROM AUTHOR]

We have experimentally studied specific features of the generation of chaotic microwave pulse trains in a self-oscillating ring system with nonlinear delay line on surface magnetostatic waves, bandpass filter, and power amplifier on GaAs field-effect transistors under the action of an external pulse-modulated microwave signal occurring outside the band of the generated chaotic signal. It is established that a decrease in the off/duty ratio in the external pulse-modulated microwave signal leads to an increase in this ratio for the chaotic microwave pulses. The integral power of the chaotic microwave signal generated under the pulsed external signal action is increased as compared to the power of signal generated in the autonomous regime. [ABSTRACT FROM AUTHOR]

The effect of shielding an electron source from a homogeneous external magnetic field of the drift chamber on the nonlinear dynamics of the electron beam with a virtual cathode (VC) and on the characteristics of output microwave radiation in a low-voltage vircator have been numerically simulated within the framework of a two-dimensional model. It is established that the increased degree of shielding of the electron source from the external magnetic field leads to the complication of the VC dynamics in the system and the corresponding chaotization of the output microwave radiation. Physical processes that account for the observed effect of shielding are analyzed. [ABSTRACT FROM AUTHOR]

Passive synchronization (PS) of spin wave self-modulation frequencies of a chaotic microwave signal has been observed for the first time in a self-oscillatory ring system involving a nonlinear passive element with saturable absorption. The development of PS led to the generation of a periodic train of chaotic microwave pulses with an off/duty ratio exceeding 20. It is established that the repetition period of chaotic microwave pulses can be controlled by changing gain in the ring system. [ABSTRACT FROM AUTHOR]

A scheme of the generator of chaotic oscillations in the microwave band is proposed that is based on two drift klystrons coupled in a ring circuit. The first klystron doubles the frequency of the input signal and the second klystron mixes the second harmonic signal and the reference signal representing a periodic sequence of radio pulses filled with the third harmonic, followed by separation of the differential first harmonic signal. As a result, the transformation of the signal phase during the period of pulse repetition is described by a stretching map of the circle (Bernoulli map) and demonstrates chaotic behavior. Results of numerical calculations are presented that confirm the implementation of the proposed mechanism to ensure the generation of robust, structurally stable chaos in the system under consideration. [ABSTRACT FROM AUTHOR]

The possibility to control for statistical characteristics of chaotic oscillation regimes by use of noise is studied. For synchronous oscillation regimes in the dynamics of coupled oscillatory systems, it is shown that noise leads to significant changes in the mean Hölder exponent. The presence of a monotonic dependence of this quantity on the intensity of the external noise makes it possible to generate a chaotic signal with given correlation characteristics. [ABSTRACT FROM AUTHOR]

We have studied the process of generalized chaotic synchronization establishment in a network of mutually coupled logistic maps and analyzed the character of interaction between elements of the network on the passage from asynchronous to synchronous dynamics related to increase in the coupling parameter. Peculiarities of the interaction between elements of the network and the onset of generalized synchronization have been elucidated using the method of phase tubes. [ABSTRACT FROM AUTHOR]

An external harmonic drive signal is used for stimulating chaos in a system with time delay, in which the parameters admit only rigid excitation of oscillations and a single impact produces only regular motions. The results of numerical simulations are presented and the mechanism of chaos induction is considered. [ABSTRACT FROM AUTHOR]

The phenomenon of generalized chaotic synchronization has been studied in a system of two unidirectionally coupled chaotic oscillators modeling two-sresonator klystron autooscillators. A mechanism explaining the observed behavior is presented. [ABSTRACT FROM AUTHOR]

The generation of chaotically modulated oscillations in autooscillatory systems with frequency control is considered. It is shown that, by coupling two such systems, it is possible to considerably expand a region corresponding to the generation of chaotic oscillations in the space of parameters of this ensemble and to provide additional means of controlling the characteristics of oscillations by changing the parameters of coupling. [ABSTRACT FROM AUTHOR]

The chaotic dynamics of a gyrotron with nonfixed field structure is numerically simulated and the Lyapunov exponents of chaotic attractors are calculated. The dimensions of chaotic attractors estimated using the Kaplan-Yorke formula prove to be anomalously high. This fact is related to the presence of a large number of high- Q eigenmodes in the gyrotron resonator operating in the vicinity of a critical frequency of the electrodynamic system. [ABSTRACT FROM AUTHOR]

The relationship between the phase synchronization of chaotic oscillators and their time scale synchronization has been considered, and it is established that the onset of the time scale synchronization depends on the resolving power of the base wavelet. This synchronization usually appears either before or (if said resolving power is insufficient) simultaneously with the onset of phase synchronization. The results are illustrated in the case of one-way coupled Rössler type dynamical systems. © 2005 Pleiades Publishing, Inc. [ABSTRACT FROM AUTHOR]

The problem of constructing model maps based on the experimental chaotic time series is considered. A new method of estimation of the model parameters for one-dimensional maps is proposed, which employs a least squares procedure and calculations of the objective function using iterations of the model map in the reverse time. The results of a numerical experiment show that the proposed method provides much more accurate estimates than does the traditional approach at a moderate noise level below a certain threshold. The greater the number of parameters to be evaluated, the higher the threshold and, hence, the broader the domain of high efficiency of the new method. © 2005 Pleiades Publishing, Inc. [ABSTRACT FROM AUTHOR]

Two coupled dynamical systems of the Rössler type are studied, and it is shown that the generalized synchronization regime can be considered as a partial case of the time scale synchronization process. © 2004 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]

We consider the time required for complete synchronization of two identical one-way coupled van der Pol-Duffing oscillators occurring in the regime of dynamic chaos. The influence of the initial phase difference between oscillators on the duration of the process of complete synchronization has been studied. At a fixed phase of chaotic oscillations of the self-excited drive oscillator, the period of time (past the coupling onset) during which the complete synchronization regime is established depends on the phase of the self-excited response oscillator. [ABSTRACT FROM AUTHOR]

The possibility of a continuous feedback control of chaos in an electron beam with supercritical current is considered within the framework of a hydrodynamical model of the Pierce diode. A method for controlling chaotic dynamics through stabilization of an unstable equilibrium state in a distributed active medium is proposed. © 2003 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]

Relations describing the spatiotemporal field of pulsation of the hydrodynamic parameters of a turbulent flow have been derived based on the wave model of turbulence. The process of chaotization of the pulsation field is analyzed. The results of calculations of the longitudinal and transverse velocity pulsation components are compared to the results of measurements reported by H. Reichardt. © 2003 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]

We describe a method of constructing model differential equations using the scalar chaotic time series for systems under external action with discrete spectrum. The approach is based on taking into account the explicit time dependence in the structure of a model and approximating this dependence by trigonometric series. The proposed method is verified by numerical experiments on standard nonlinear systems driven by periodic and quasiperiodic factors of various types. © 2003 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]

We consider an approach to the analysis of nonstationary processes based on the application of wavelet basis sets constructed using segments of the analyzed time series. The proposed method is applied to the analysis of time series generated by a nonlinear system with and without noise. © 2003 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]

We have studied the dynamic regimes of an autonomous chaotic system (a modified oscillator with inertial nonlinearity) and found a chaotic attractor of a new type. The autocorrelation function, power spectrum, and Lyapunov exponents of this attractor have been calculated. Some of these characteristics resemble the behavior of a strange nonchaotic attractor. [ABSTRACT FROM AUTHOR]

A scheme of data transmission through a radio channel masked by chaotic oscillations is considered. A mathematical model describing the system is formulated in the case of chaotic oscillations generated in two separated frequency bands. The results of a numerical analysis of the model are presented. It is demonstrated that hidden data transmission in such a channel is possible. [ABSTRACT FROM AUTHOR]

A system of two inductively coupled chaotic oscillators is considered. Normalized equations of motion for oscillators with arbitrary parameters are derived in the case of a cubic approximation of the nonlinear elements. The results of a numerical analysis of the features of interaction between chaotic coupled nonidentical subsystems are presented and a realistic experiment is described. [ABSTRACT FROM AUTHOR]

A characteristic is suggested for the evaluation of the degree of synchronization of the chaotic oscillations in a system of two coupled oscillators. The proposed value is tested by application to the case of two unidirectionally coupled logistic maps. It is shown that this characteristic is stable with respect to a low noise and a nonlinear distortion of the signal. [ABSTRACT FROM AUTHOR]

The capability of calculating the highest Lyapunov index during analysis of the so-called point processes [1] is analyzed. Two mathematical models describing the generation of pulses by receptor neurons are considered and the conditions are established for which the dynamic characteristics of chaotic oscillations, determined from the output sequence of pulses, are retained during linear transformations of the neuron input signal. [ABSTRACT FROM AUTHOR]

Equations describing a ring system of three unidirectionally coupled Chua oscillators (subsystems) are presented. Numerical analysis is performed in the case in which only one subsystem is autooscillatory. It is shown that non-auto-oscillatory subsystems (simplified to single-shot trigger type) exhibit complication of circuit oscillations that is accompanied by multiplication of the oscillation frequencies and expansion of the generated spectrum. [ABSTRACT FROM AUTHOR]