Search results for "Relative"
showing 10 items of 1094 documents
Dielectric Characterization of Fruit Nectars at Low RF Frequencies
2015
Dielectric properties of apple, apricot, peach, and pear nectars were studied in the frequency range from 15 kHz to 30 MHz and the temperature range from 25 to 60 degrees C. Both the relative dielectric constants and the dielectric loss factors decreased by increasing frequency and increased linearly with increasing temperature with values in the order 10(4)-10(2) and 10(5)-10(2), respectively. The power dissipation densities and the power penetration depths were found to increase linearly with temperature. Power dissipation densities remained essentially constant for all the samples while power penetration depths decreased significantly on increasing frequency. The dependence of each of th…
Dielectric spectroscopy of an aligned liquid crystalline side chain polymer using high pressures
1995
Abstract The complex permittivity of a liquid crystalline side group polymer has been measured at pressure from ambient up to 300 MPa. The samples were initially not aligned, then planar and finally homeotropically aligned by the field of a 7.2 Tesla magnet. Temperatures ranged up to 130°C, and measurement frequencies from 5 Hz to 5 MHz. The equilibrium permittivity es has been interpreted in terms of an effective dipole moment μ. The frequency of maximum loss has been analysed in terms of enthalpy of activation and volume of activation for α and β relaxation processes.
Dielectric Permittivity and Conductivity of Li0.07Na0.93Ta0.1Nb0.9O3and Li0.07Na0.93Ta0.111Nb0.889O3Solid Solutions
2011
Results of studies of dielectric properties and conductivity in 290–700 K range of temperature and frequencies from 25 to 106 Hz in ferroelectric perovskite solid solutions Li0.07Na0.93Ta0.1Nb0.9 O3 and Li0.07Na0.93Ta0.111Nb0.889 O3 are reported. A first-order ferroelectric phase transition proceeds in both studied compositions within the observed range of temperature. The co-precipitated Ta2yNb2(1-y)O5 pentoxides being used for synthesis of Li0.07Na0.93Ta0.111Nb0.889O3 the Curie point shifts by ∼75 K to a lower temperature while compared with Li0.07Na0.93Ta0.1Nb0.9O3 synthesised from mechanical mixture of the Ta2O5 and Nb2O5 oxides the high-frequency dielectric permittivity and ion conduct…
Uniaxial stress dependence of the dielectric and ferroelectric properties of the Na0.5K0.5NbO3and Na0.5K0.5NbO3 + 0.5 mol%MnO2ceramics
2013
Na0.5K0.5NbO3 and Na0.5K0.5NbO3 + 0.5 mol%MnO2 lead-free ceramics have been produced by solid phase hot pressing sintering process at 1120–1145°C. The results of the X-ray diffraction measurements showed that the obtained samples possessed a perovskite structure. The micrograph of the fractured surface showed a dense ceramic structure, in compliance with 93% relative density determined by the Archimedes method. The dependence of dielectric and ferroelectric properties on the uniaxial compressive stress (0–3000 bar) of the Na0.5K0.5NbO3 and Na0.5K0.5NbO3 + 0.5 mol%MnO2 ceramics was investigated. Significant influence of the external stress on these properties was revealed. It includes a shif…
Accurate determination of the complex permittivity of materials with transmission reflection measurements in partially filled rectangular waveguides
2003
An enhanced transmission reflection technique for the precise determination of the complex permittivity of dielectric materials partially filling the cross section of a rectangular waveguide is described. Dielectric properties are determined by an iterative procedure from two-port S-parameter measurements and a numerically generated propagation constant obtained from the analysis of a partially filled waveguide. Convergence of the solution is ensured from perturbational approximations. Unlike previous approaches, an uncertainty investigation is performed, taking into account all the parameters involved in the dielectric characterization. Permittivity accuracy values are presented and, hence…
Permittivity Measurements of Lossy Liquids at Millimeter-Wave Frequencies
1983
A measurement system is described which allows the determination of the complex permittivity of high-loss liquids at millimeter waves. Basically, the setup consists of a waveguide interferometer whose unknown arm embodies a liquid holder irradiated by an open-ended rectangular waveguide. The sample thickness is varied by means of a piston driven by a micrometer screw. The bridge output then is read as a function of the liquid thickness. Best fitting between experimental and computed data through a suitable model of the system enables the permittivity to be determined. The system can operate, with high sensitivity, over the whole frequency range of the dominant mode propagating in the wavegu…
Relation of Dielectric Permittivity and Electric Field Dependence of Polarization in Some Relaxors with Perovskite Structure
2011
The dielectric nonlinearity is studied in ferroelectric relaxors 0.92PbMg1/3 Nb2/3O3-0.08PbTiO3, 0.4Na1/2Bi1/2TiO3-0.5SrTiO3-0.1PbTiO3 and Pb0.9075La0.0925 (Zr0.65Ti0.35)0.9775O3. It is shown that above the temperature of dielectric permittivity maximum nonlinearity of dielectric permittivity corresponds to electric field dependence of polarization. The influence of electric field on distribution of relaxation times is studied below the maximum of dielectric permittivity. The role of internal bias field in Pb0.9075La0.0925(Zr0.65Ti0.35)0.9775O3 ceramics is discussed.
The effects of populism as a social identity frame on persuasion and mobilization: evidence from a 15-country experiment
2020
This article investigates the impact of populist messages on issue agreement and readiness for action in 15 countries (N = 7,286). Specifically, populist communicators rely on persuasive strategies by which social group cues become more salient and affect people's judgment of and political engagement with political issues. This strategy is called ‘populist identity framing’ because the ordinary people as the in‐group is portrayed as being threatened by various out‐groups. By blaming political elites for societal or economic problems harming ordinary people, populist communicators engage in anti‐elitist identity framing. Another strategy is to blame immigrants for social problems – that is, …
Organic solvents vapor pressure and relative humidity effects on the phase transition rate of α and β forms of tegafur.
2011
The objective of this work was to investigate the relative humidity (RH) and solvent vapor pressure effects on the phase transition dynamics between tegafur polymorphic forms that do not form hydrates and solvates. The commercially available α and β modifications of 5-fluoro-1-(tetrahydro-2-furyl)-uracil, known as the antitumor agent tegafur, were used as model materials for this study. While investigating the phase transitions of α and β tegafur under various partial pressures of methanol, n-propanol, n-butanol, and water vapor, it was determined that the phase transition rate increased in the presence of solvent vapors, even though no solvates were formed. By increasing the relative air h…
Dielectric polarization in PLZT X/65/35 and PbMg1/3Nb2/3O3at the diffuse phase transition
1992
Abstract The transformation of the hysteresis loops in PLZT x/65/35 in the region of diffuse phase transition is discussed in relation to the behaviour of dielectric permittivity. The Vogel-Fulcher type dielectric relaxation is used to describe the discussed phenomena.