The Dielectric Properties of Systems Containing Straight Polar Chains

1952 ◽  
Vol 5 (1) ◽  
pp. 135
Author(s):  
RA Sack
Keyword(s):  
Dielectric Properties ◽  
Low Frequency ◽  
Hydroxyl Groups ◽  
Total Moment ◽  
Low Frequencies ◽  
Elementary Transition ◽  
A Chain ◽  
The Individual ◽  
High Dielectric ◽  
Mathematical Derivation

A mathematical derivation is given of the dielectric properties of systems containing straight polar chains such that to each value of the total moment of a chain there corresponds only one arrangement of its dipoles. If the moments of the individual dipoles and the probability of an elementary transition are fixed, both the total dielectric loss and the effective relaxation time of the system increase in proportion to the square of the number of states of each chain. These conclusions are not valid for kinked chains and apply only qualitatively if the chains are branched. The theory provides an explanation for the high dielectric losses at low frequencies observed in many solids containing hydroxyl groups. It can further explain the low frequency absorption found in ionic crystals containing lattice imperfections ; in this interpretation the theory is related to Jaffe's theory of conductivity in polarizable media.

Temperature Dependence on Dielectric Response of La0.7Ba0.3Mn0.4Ti0.6O3 Ceramic

2015 ◽  
Vol 1107 ◽  
pp. 45-52
Author(s):  
Aaliyawani Ezzerin Sinin ◽  
Walter Charles Primus ◽  
Abdul Halim Shaari ◽  
Zainal Abidin Talib ◽  
Sinin Hamdan
Keyword(s):  
Dielectric Properties ◽  
Temperature Dependence ◽  
Low Frequency ◽  
Sintered Sample ◽  
Solid State Reaction Method ◽  
X Ray Diffraction ◽  
Conventional Solid State Reaction ◽  
Low Frequencies ◽  
X Ray ◽  
Lcr Meter

Ceramic sample of La0.70Ba0.30Mn0.40Ti0.60O3 oxide has been prepared by the conventional solid-state reaction method. The sintered sample was characterized by using x-ray diffraction (XRD) and low frequency LCR meter. XRD result shows that the sample has a cubic structure with the existence of impurity phase. The dielectric properties of La0.70Ba0.30Mn0.40Ti0.60O3 measured from room temperature to 200°C shows that the dielectric permittivity is temperature dependence with strong dispersion at low frequencies. A circuit model based on the universal capacitor response function is also being used to represent the dielectric properties of the sample.

scholarly journals A seismic vertical vibrator driven by linear synchronous motors

Geophysics ◽  
2015 ◽  
Vol 80 (2) ◽  
pp. EN57-EN67 ◽  
Author(s):  
Rik Noorlandt ◽  
Guy Drijkoningen ◽  
Johan Dams ◽  
Rob Jenneskens
Keyword(s):  
Low Frequency ◽  
Field Tests ◽  
Seismic Source ◽  
Neutral Position ◽  
Low Frequencies ◽  
Synchronous Motors ◽  
Frequency Regime ◽  
Linear Synchronous Motors ◽  
Spring Mechanism ◽  
The Individual

A linear synchronous motor (LSM) is an electric motor that can produce large controllable forces and is therefore suitable as a driving engine for a seismic vibrator. This motor consists of two independent elements, a magnet track and a coil track, allowing practically unlimited motor displacements. This makes the LSM very suitable for expanding the source frequency band to the lower frequencies in which larger strokes are needed. In contrast to hydraulic engines, the LSM performs equally well over the whole frequency range, making possible a smaller amount of signal distortion, especially at the low frequencies. To find the feasibility of an LSM-driven vibrator, we successfully designed and built a multi-LSM prototype vibrator of some 1200 kg. We addressed the synchronization between the individual motor tracks and the different motors. To lower the energy consumption, a spring mechanism was implemented that delivered the force needed to lift the vibrator mass to its neutral position. The resonance belonging to this spring mechanism was successfully suppressed with the help of a position feedback control that also suppressed the temperature effects. The seismic data acquired in the field tests proved that the prototype LSM vibrator acted very well as a seismic source. It has no trouble generating pseudorandom sweeps, and even given its limited size, it generated signals within the low-frequency regime, down to 2 Hz, rather easily.

scholarly journals Enhanced dielectric and ferroelectric properties of surface hydroxylated Na0.5Bi0.5TiO3 (NBT)-poly(vinylidene fluoride) (PVDF) composites

2018 ◽  
Vol 08 (03) ◽  
pp. 1850017 ◽  
Author(s):  
Srikanta Moharana ◽  
Shraddhakara Sai ◽  
Ram Naresh Mahaling
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
High Dielectric Constant ◽  
Vinylidene Fluoride ◽  
Ferroelectric Properties ◽  
Material Surface ◽  
Hydroxyl Groups ◽  
Energy Storage Devices ◽  
Surface Hydroxylation ◽  
High Dielectric

The surface hydroxylation treatment has been carried out by using hydrogen peroxide (H2O2) to modify the surface of Na[Formula: see text]Bi[Formula: see text]TiO3 (NBT) particles in a ferroelectric polymer (PVDF) via solution casting technique. The FTIR study confirms the presence of hydroxyl groups on the surface of NBT. The FE-SEM analysis reveals that h-NBT particles are dispersed homogeneously within the polymer matrix. The surface hydroxylation treatment plays an important role in high dielectric constant and also reduced loss by conducting the material surface with [Formula: see text]OH functional groups. The prepared composite with 40[Formula: see text]wt.% of h-NBT showed enhanced dielectric constant ([Formula: see text]114), negligible loss (0.22) and high AC conductivity as compared to that of the unmodified NBT. Such significant enhancement in dielectric properties may be due to the strong interaction between h-NBT particles and PVDF matrix at the interface. The percolation theory is used to explain the dielectric properties of h-NBT-PVDF composite. Furthermore, the remnant polarization of the un-poled h-NBT-PVDF composites (2[Formula: see text]Pr–1.19[Formula: see text][Formula: see text]C/cm2 for 40[Formula: see text]wt.% of h-NBT) is also improved. The present findings give an idea of high dielectric constant and relatively low loss composite materials as a promising candidate for electronic and energy storage devices.

TEMPORAL FLUCTUATIONS IN BIORHYTHMS: EXPRESSION OF SELF-ORGANIZED CRITICALITY?

Fractals ◽  
1993 ◽  
Vol 01 (03) ◽  
pp. 380-387 ◽  
Author(s):  
KLAUS-D. KNIFFKI ◽  
WOLFGANG MANDEL ◽  
PHUOC TRAN-GIA
Keyword(s):  
Point Process ◽  
Critical State ◽  
Degrees Of Freedom ◽  
Low Frequency ◽  
Well Being ◽  
Scale Invariant ◽  
Low Frequencies ◽  
Temporal Fluctuations ◽  
Self Organized ◽  
The Individual

Recently, a general organizing principle has been reported connecting 1/f-noise with the self-similar scale-invariant ‘fractal’ properties in space, hence reflecting two sides of a coin, the so-called self-organized critical state. The basic idea is that dynamical systems with many degrees of freedom operate persistently far from equilibrium at or near a threshold of stability at the border of chaos. Temporal fluctuations which cannot be explained as consequences of statistically independent random events are found in a variety of physical and biological phenomena. The fluctuations of these systems can be characterized by a power spectrum density S(f) decaying as f−b at low frequencies with an exponent b<1.5. We present a new approach to describe the individual biorhythm of humans using data from a colleague who has kept daily records for two years of his state of well-being applying a fifty-point magnitude category scale. This time series was described as a point process by introducing two discriminating rating levels R for the occurrence of R≥40 and R≤10. For b<1 a new method to estimate the low frequency part of S(f) was applied using counting statistics without applying Fast Fourier Transform. The method applied reliably discriminates these types of fluctuations from a random point process, with b=0.0. It is very tempting to speculate that the neural mechanisms at various levels of the nervous system underlying the perception of different values of the subjective state of well-being, are expressions of a self-organized critical state.

scholarly journals Dielectric Properties of Paper Made from Pulps Loaded with Ferroelectric Particles

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Hind El Omari ◽  
Adel Zyane ◽  
Ahmed Belfkira ◽  
Moha Taourirte ◽  
François Brouillette
Keyword(s):  
Dielectric Properties ◽  
Typha Latifolia ◽  
Adsorbed Water ◽  
Hydroxyl Groups ◽  
Short Fibers ◽  
Low Frequencies ◽  
Ceramic Particles ◽  
Fibrous Network ◽  
Pennisetum Alopecuroides ◽  
Electrical Insulation Materials

Due to its physical properties and its ease of manufacture, paper is widely used in various engineering applications such as electrical insulation materials for components in high voltage technology. In this study, paper loaded with ferroelectric nanoparticles (BaTiO3and SrTiO3) was made with fibers obtained from plants growing on the Moroccan soil [Halfa (Stipa tenacissima), Agave (Agave americana), Pennisetum (Pennisetum alopecuroides), Typha (Typha latifolia), and Junc (Juncus effusus)] and two commercial pulps (bleached softwood Kraft and newsprint grade thermomechanical pulps). A retention aid, cation polyacrylamide (Percol 292), was necessary to retain ferroelectric particles in the fibrous network and improve the dispersion of strontium titanate particles. The different pulp and handsheets used were characterized according to standard methods (Pulp and Paper Technical Association of Canada, PAPTAC). It is well known that annual and perennial plants contain high percentages of fines (length < 0.2 mm) and short fibers. The results show that there is a strong interdependence between the dielectric properties of the loaded paper and surface finish, porosity, dispersion level of ceramic particles, fines content, shape, conformability, and sheet formation. The single dielectric relaxation detected towards low frequencies is attributed to hydroxyl groups present on fiber surfaces, in ceramic particles and adsorbed water.

Features of frequency dependence of electrical conductivity and dielectric properties in lignins from conifers and deciduous trees

Holzforschung ◽  
2020 ◽  
Vol 74 (12) ◽  
pp. 1113-1122
Author(s):  
Sergey Khviyuzov ◽  
Konstantin Bogolitsyn ◽  
Aleksandr Volkov ◽  
Gennadiy Koposov ◽  
Maria Gusakova
Keyword(s):  
Electrical Conductivity ◽  
Dielectric Properties ◽  
Electric Field ◽  
High Frequency ◽  
Low Frequency ◽  
Adsorbed Water ◽  
Deciduous Trees ◽  
Hydroxyl Groups ◽  
Electrophysical Properties ◽  
Functional Nature

AbstractLignins are among the most common plant polymers and demonstrate pronounced electrical conductivity properties due to their conjugated polymolecular aromatic structure and polyfunctional nature. Electrical conductivity and dielectric properties of lignins from conifers and deciduous trees in the range of electric field frequencies from 10−2 to 107 Hz were investigated by means of dielectric spectroscopy. Characteristic parameters of static and high frequency electrical conductivity were calculated. To study the influence of the lignins functional nature on their electrophysical properties, the study determined three types of relaxators (separate charges or charge systems in the structure of a substance changing their position in space when exposed to an external alternating electric field) in the structure of the lignin macromolecule. Low-frequency relaxators are associated with oscillations of methoxyl groups. Mid-frequency relaxators correspond predominantly to phenolic hydroxyl groups and to hydroxyl groups of adsorbed water. High-frequency relaxators correspond to the hopping of π-electrons along the chain of conjugated bonds of a benzene ring. Differences in the structure and functional nature of lignins from conifers and deciduous trees cause different contributions of low-frequency relaxators. As a result, these features form differences in the electrophysical properties of lignins from conifers and deciduous trees.

The Dielectric Properties of a Series of dl-n-Eicosanols

1951 ◽  
Vol 4 (3) ◽  
pp. 359
Author(s):  
RJ Meakins ◽  
HK Welsh
Keyword(s):  
Dielectric Properties ◽  
Low Frequency ◽  
Polar Compounds ◽  
Carbon Chain ◽  
Hydroxyl Groups ◽  
Secondary Alcohols ◽  
Polar Group ◽  
Dielectric Absorption ◽  
Ready Availability ◽  
Long Chain

Initial investigations of the dielectric properties of normal long-chain secondary alcohols were made with the symmetrical compounds because of their ready availability. The properties of long-chain polar compounds are known to vary considerably, however, with the position of the polar group in the carbon chain and it therefore seemed desirable to make dielectric measurements with some unsymmetrical alcohols. The present paper describes such an investigation of a series of dl-n-eicosanols having the hydroxyl groups in the 2-, 4-, 6-, 8-, and 10-positions, respectively. The results for the melted forms show that slight asymmetry, as in the 10-compound, has little effect on the dielectric properties, but with the more unsymmetrical 4-, 6-, and 8-compounds a considerable enhancement of the dielectric absorption is observed. This is accompanied by increased dispersion of the dielectric constant which, for the 8-compound, reaches a low frequency value of 15. Both ε" and ε' decrease during storage at room temperature. Anomalous results are obtained with dl-n-eicosan-2-ol, probably due to the molecules in the crystal lattice being alternately reversed, end-to-end. As with the symmetrical secondary alcohols, the recrystallized forms give comparatively little dielectric absorption.

Impedance and dielectric properties of mercury cuprate at nonsuperconducting state

2015 ◽  
Vol 29 (29) ◽  
pp. 1550205 ◽  
Author(s):  
Z. Güven Özdemir ◽  
Ö. Aslan Çataltepe ◽  
Ü. Onbaşlı
Keyword(s):  
Dielectric Properties ◽  
Low Frequency ◽  
Interfacial Polarization ◽  
Nyquist Plot ◽  
Dielectric Constants ◽  
Frequency Interval ◽  
Radio Waves ◽  
Spectroscopy Analysis ◽  
High Dielectric ◽  
First Time

In this paper, impedance and dielectric properties of nonsuperconducting state of the mercury-based cuprate have been investigated by impedance measurements within the frequency interval of 10 Hz–10 MHz for the first time. The dielectric loss factor [Formula: see text] and ac conductivity [Formula: see text] parameters have also been calculated for non-superconducting state. According to impedance spectroscopy analysis, the equivalent circuit of the mercury cuprate system manifests itself as a semicircle in the Nyquist plot that corresponds to parallel connected resistance–capacitance circuit. The oscillation frequency of the circuit has been determined as approximately 45 kHz which coincides with the low frequency radio waves. Moreover, it has been revealed that the mercury-based cuprate investigated has high dielectric constants and hence it may be utilized in microelectronic industry such as capacitors, memory devices etc., at room temperature. In addition, negative capacitance (NC) effect has been observed for the mercury cuprate regardless of the operating temperatures at nonsuperconducting state. Referring to dispersions in dielectric properties, the main contribution to dielectric response of the system has been suggested as dipolar and interfacial polarization mechanisms.

PREPARING PUBLIC SERVANTS IN EUROPEAN COUNTRIES: ARCHETYPAL APPROACH

2018 ◽  
Vol 1 (14) ◽  
pp. 255-263
Author(s):  
Oleh Ivanovich Rohulskyi
Keyword(s):  
Public Administration ◽  
Public Service ◽  
Professional Training ◽  
European Countries ◽  
Anglo Saxon ◽  
Public Servants ◽  
German Model ◽  
Managerial Positions ◽  
A Chain ◽  
The Individual

The article describes the main components of the institutional framework of an archetypical approach to public administration. It is determined that the system of preparation of public servants is based on a chain of universal foundations of archetype, in particular, it is influenced by the principle of formation of personnel in the public service, formed on the basis of public opinion. Based on two basic principles relating to admission to public service, three basic models of training civil servants in the European country are defined: German. French and Anglo-Saxon. We analyze each of the models and define the archetypes that influenced their formation and development. The advantages of each model are determined, in particular, the benefits are: the German model of training managers is the balancing between the theoretical knowledge and practical skills that a public servant receives during training, but as a disadvantage one can distinguish the orientation of preparation for legal orientation, which limits the ability to hold managerial positions for many employees The French model of professional training of public servants should include a well-balanced understanding of tasks, namely: decentralization and territorial organization of public services, communication, support of territorial communities, in-depth knowledge and understanding of the need for cooperation with institutions of the European Commonwealth, high-quality human resource management and orientation towards environmentally friendly innovations, such a model of training of public servants is holistic, costly and effective; The Anglo-Saxon model of training of public servants is its orientation towards the implementation of the concept of public administration and the individual approach to employee training, taking into account all the specifics of its activities, providing for the formation of personnel capable of solving specific problems. It is concluded that today in most European countries dominated by mixed models that include elements of different models.

Sign in / Sign up

Export Citation Format

Share Document