Infralow Frequency Range Research Articles

Diagnostics, measurement and control of electrical parameters supercapacitors

This article considers possible approaches to diagnostics and measurement electrical parameters of supercapacitors. The analysis the results of diagnostics and measurement the parameters of supercapacitors has determined a significant frequency dependence of theirs. The discrepancy between the two-element equivalent circuit of supercapacitors has been established. Diagnostics and control electrical parameters of supercapacitors in the infralow frequency range can be performed by direct conversion methods. In this case, high-precision low-resistance resistors can be used as an exemplary measure. For the diagnostics and design of meters for the electrical parameters of supercapacitors of capacitors, the authors propose an iterative-recursive method for determining the numerical values of the electrical parameters of the equivalent circuit of such objects. The essence of the proposed iterative-recursive method is that at the first stage, the iterative approximation determines the number of n-absorption links, which it is enough to know when developing, manufacturing and operating supercapacitors. Theoretical and experimental studies of the equivalent circuit of supercapacitors show that the equivalent resistance of such capacitors and their capacitance increase with decreasing frequency of the measuring signal, and the nature of these dependences is determined by the number of n-absorption links and the numerical values of the elements of each link.

Fabrication of 1D-Nanofiber/Fe₂O₃ Composites with Tailored Magnetic Properties.

A novel flexible electrospun nanofiber/γ-Fe₂O₃ composite has been obtained from suspension of γ-Fe₂O₃ nanoparticles in polyvinylpyrolidone solution in dimethylformamide. The impedance spectroscopy of the synthesized nanofiber/γ-Fe₂O₃ composite was carried out. Negative magnetoresistance and giant magnetocapacitance effects, as well as phenomenon of a "negative capacitance" at room temperature were observed in magnetic field (2.75 κOe) in infra-low frequency range. The polarization properties and volt-ampere characteristics of the nanocomposite in the applied magnetic field indicate the increase in the dielectric permittivity ɛ and the emergence of spin electromotive force, which enables us to accumulate of electric energy at quantum level. A quantum-mechanical model, which explained the non-monotonous behaviour of the volt-ampere characteristic of the novel nanofiber based composite, has been suggested.

Anomalous Behavior of the Terrestrial Electric Field Intensity at Multiple Frequencies of Relativistic Binary Star Systems

The vertical component of the terrestrial electric field intensity has been proven to be spectrally localized at multiple frequencies of forty-three relativistic binary star systems. The used four time series contain multiannual observations of the terrestrial electric field intensity in the infralow frequency range. The used method is eigenoscopy developed by the present authors. The matrix of second sample moments is computed at finite time spans. The eigenvectors of the moment matrix and their amplitude spectra are computed and analyzed. A database of the discovered anomalous behavior has been built.

Gravitational Wave Track in the Electromagnetic Field of the Earth in the Infra-Low Frequency Range

Signals in the infra-low frequency range in the electric and geomagnetic fields of the Earth have been detected, corresponding to frequencies of gravitational waves (GWs) emitted by a series of binary star systems (BSS). The coherence of the detected signals has been investigated. The amplitude characteristics of signals in the electric and geomagnetic fields at GW frequencies of BSS are estimated. The estimates of the amplitudes of the detected signals are in line with model estimates.

Helicopter vibration isolation: Design approach and test results

This paper presents a strategy based on the approach of designing and inserting into helicopter vibration isolation systems mountable mechanisms with springs of adjustable sign-changing stiffness for system stiffness control. A procedure to extend the effective area of stiffness control is presented; a set of parameters for sensitivity analysis and practical mechanism design is formulated. The validity and flexibility of the approach are illustrated by application to crewmen seat suspensions and vibration isolators for equipment protection containers. The strategy provides minimization of vibrations, especially in the infra-low frequency range which is the most important for crewmen efficiency and safety of the equipment. This also would prevent performance degradation of some operating systems. The effectiveness is demonstrated through measured data obtained from development and parallel flight tests of new and operating systems.

Effect of change in the physical properties of water at its peculiar temperature points on the dielectric behavior of sodium polyacrylate

The behavior of sodium polyacrylate is studied via broadband dielectric spectroscopy. The non-Debye response in the frequency range 0.1 Hz–1.0 MHz, the non-Markovian dispersion in the infralow-frequency range, and the anomalies of dielectric permittivity and ac conductivity near “peculiar” temperatures of water (20, 35, 50, and 75°C) are ascertained experimentally. These facts make it possible to assign sodium polyacrylate to disordered media, in which the temperature behavior of dielectric parameters is described by the Kohlrausch–Williams–Watts relaxation function.

Application of the Superslow Relaxation Model in the Description of Time Series of the Vertical Electric Field Component in the Earth’s Atmospheric Boundary Layer in the Infra-Low Frequency Range

To explain the presence of spectrally localized, mutually uncorrelated the electric field components in the Earth’s atmospheric boundary layer in the infra-low frequency range, it is proposed to use the model of fractionally integrated white Gaussian noise. It is shown that the uncorrelated components of the fractionally integrated (of order 0.5) white Gaussian noise have a coherence index close to that of the uncorrelated components of time series of the electric field. The energy distribution of the uncorrelated components of the fractionally integrated noise is also close to the energy distribution of the components of the electric field. To lay the basis for a physical interpretation of fractionally integrated noise, it is proposed to use the differential equation of superslow relaxation.

An impedance analyzer of semiconductor structures in the infra-low frequency range

An impedance analyzer of semiconductor structures at infralow frequencies is designed. The analyzer contains a remote measuring head placed near the studied structure and an electronic unit connected to the computer via a USB interface. The analyzer measures the capacitance, conductivity, and current of a structure in a frequency range of 0.01–10 Hz. The measurement ranges of the capacitance value are 10, 100, and 1000 pF, of the current—25, 250, and 2500 pA, and of the conductivity—10, 100, and 1000 pS.

Non-Debye relaxation and resonance phenomena in dielectric spectra of CaCu3Ti4O12 family functional ceramic materials

Experimental data on dielectric spectra of calcium copper titanate, CaCu 3 Ti 4 O 12 (CCTO) family functional ceramics have been studied and analyzed. It is shown that there are both non-Debye relaxation and resonance regions in their spectra. An occurrence of a retardation of complex permittivity and a relaxation of electric modulus is established. An average relaxation frequency of the electric modulus is considerably (in some cases several orders of magnitude) larger than the retardation frequency of the permittivity. A parallel connection of the capacity and complex conductivity is used to model and interpret experimental data on a negative permittivity in the infralow frequency range. Computer simulation enables us to reveal that the hopping conductivity, characteristic for disordered heterogeneous systems, is to be taken into account to describe adequately experimental data on passing the real part of the capacity (or permittivity) through zero. We have found a critical frequency at which the parallel resonance would take place.

Compliant bistable mechanism for low frequency vibration energy harvester inspired by auditory hair bundle structures

This paper presents a bio-inspired mechanism for the performance enhancement of piezoelectric power generation in vibration energy harvesting. A compliant bistable mechanism for vibration energy harvesting was explored based on the negative stiffness inspired by the auditory hair bundle structures. The proposed mechanism consists of a compliant, four-bar linkage system to mimic the hair bundle structure inside an inner ear. Our initial prototype energy harvester demonstrates that the compliant bistable mechanism featuring negative stiffness outperforms the conventional vibration energy harvester in the infra-low frequency range (1–10 Hz).

A multi-stage high-speed railroad vibration isolation system with “negative” stiffness

The intensity of mechanical vibrations generated by a moving train increases at high speeds. Conventional railroad vibration isolation systems are either insensitive or inefficient in the infra-low frequency range, which is the range most hazardous to humans. In this work, an approach for upgrading a multi-stage system for engineers, crew, passengers, and people living near railroads is presented. The approach involves the design of geometrically similar redundant mechanisms with “negative” stiffness that could be compactly inserted into all system stages without degrading structure and safety. The approach is implemented in the design of seat suspensions. Finally, a concept relevant to the design of mechanisms for vehicle spring hangers and track bed elements is discussed in terms of the dimensional analysis.

Peculiarities in the work of laser gravitational antennas in the infra-low frequency range

We study the methodology of measuring quasistatic perturbations of geophysical nature in laser gravitational-wave interferometers. We calculate the transfer function of such an instrument in the destructive interference mode (the “dark spot” mode) taking into account the natural asymmetry of the optical Fabry-Perot cavity lengths in its arms. Formulas have been obtained for estimating the output signal power modulation at the frequency of photon circulation in the arms due to geophysical perturbations. The estimates are compared with the results of observations at the LIGO interferometer.

Temperature dependence of the dielectric parameters of thin arsenic triselenide layers with high bismuth content

The temperature and frequency dependences of the dielectric parameters (dielectric permittivity and loss tangent) of modified arsenic triselenide layers with high bismuth content have been studied. In the infralow frequency range, an increase in the temperature leads to significant growth of the real component of the complex permittivity and the appearance of maxima in the dielectric loss tangent. At greater frequencies, these maxima shift toward higher temperatures.

Investigation of hysteresis loops in SBN single crystal

Temperature-field evolution of hysteresis loops (HL's) in Sr0.61Ba0.39Nb2O6 single crystal doped with 0,01% Cr2O3 (SBN:Cr), were studied in infralow frequency range and in wide temperature range. The anomalous behavior of the material's repolarization characteristics, obtained from the HL's calculation: effective dielectric permittivity, HL area, etc., was revealed.

Slow Polarization Kinetics in Relaxor Ferroelectrics

Ferroelectric relaxors lead magnesium niobate (PMN) and barium-strontium niobate (SBN) solid solutions of various compositions are shown to exhibit general features of dielectric properties in infralow frequency range. These features are related to the essentially inhomogeneous structures with long-lived metastable states. The irreducibility of some first cycles of hysteresis loops, an absence of the single-valued coercive field, giant relaxation times and very high potential barriers are signatures of the structural disorder typical for relaxors. The probable spectra of distribution of the barriers in energy are reconstructed. The recently published data are reviewed and some new results are presented.

Method of phase measurement in the infralow frequency range and its realization

Method of phase measurement in the infralow frequency range and its realization

Measurement of the harmonic coefficient in the infralow frequency range

Measurement of the harmonic coefficient in the infralow frequency range

Electrical relaxation properties of dry human compact bone tissue in the infralow frequency range

Electrical relaxation properties of dry human compact bone tissue in the infralow frequency range

Investigation of curing an epoxy resin by the polarization current method

1. An investigation of the curing kinetics of an epoxy resin by the polarization current method at constant temperature reveals, on the infralow frequency range f=0.001–1 Hz, the existence of a relaxation process which during polymerization changes shape and is shifted toward longer times.