The orthophosphates materials are one of the most important groups in the field technologically advanced materials that are accessible, inexpensive, and environmentally friendly. This materials are ...of great demand due to their various optoelectronic applications in recent years. In this study, a solid-state method was employed to synthesize the AgCoPO
4
orthophosphate sample. Analyzing the XRD pattern, of the studied compound, confirms the triclinic phase with the
P
1
¯
space group. The examination of SEM analysis and energy dispersive spectroscopy (EDS) revealed the same morphology and different particle sizes. As for the EDX analysis, all chemical elements were detected and found in their appropriate ratio. Besides, the impedance spectroscopy measurements conducted at 100 Hz to 5 MHz and 473–673 K are used to investigate the electrical and dielectric properties of the AgCoPO
4
compound. The frequency dependence of the conductivity of alternating current is explained using Jonscher’s law. The calculated activation energy is in accordance with Arrhenius’s behavior based on DC conductivity, which was determined to be 0.93 (2) eV. The primary transport mechanism is governed by the correlated barrier hopping model. A comparative study of impedance and modulus responses versus frequency suggests Cole–Cole behavior. deep investigation of the electric and dielectric performances demonstrated a significant dielectric constant (
ε
′ ∼ 10
4
) at low frequencies and low dielectric loss at high frequencies. Thus, it highlights its exceptional dielectric potential, particularly in applications related to electronic capacitors.
This work presents some electrical properties based on the impedance measurements as well as the dielectric constants and electric modulus. In order to through light in the electrical conductivity ...and dielectric properties of Rb2HAsO4Te(OH)6 (Rb As Te), we have carried out complex impedance spectroscopy technique in the frequency range 200 Hz–5 MHz at various temperatures (304 K–493 K). The complex impedance diagram at different temperatures showed a single semicircle, implying that the response originated from a single capacitive element corresponding to the grains. AC and dc conductivities were studied to explore the mechanisms of conduction. The experimental data shows that the ac conductivity of this compound is proportional to ωs (s < 1), the value of s is temperature-dependent.
The conductivity evolution versus temperature reveals the presence of the super-ionic- protonic conduction phase transition. The dielectric properties's dependence on both temperature and frequencies of the compound has been reported. The ionic-protonic conductivity and conductivity relaxation calculated from the impedance and modulus spectra respectively were found to be thermally activated. The conductivity relaxation parameters of some H+ and Rb+ conducting in the RbAsTe material have been determined from an analysis of AC conductivity data measured in a wide temperature range. The near value of activation energies obtained from the hopping frequency and equivalent circuit confirms that the transport is through ion hopping mechanism dominated by the motion of the H+ ion in the structure of the investigated material, thus the displacement of the Rb+ cations at the level of the tunnels.
•We have characterized the phase transition observed in DSC curve of the new compound Rb2HAsO4Te(OH)6.•The frequency dependent AC conductivity indicates that the conduction process is thermally activated.•The protonic conduction in the new compound is probably due to a hopping mechanism.•The temperature dependence of s is investigated in order to understand the conduction mechanism in the different phases.
New pyrophosphate of ceramic compounds LiNa
3-x
Ag
x
P
2
O
7
(
x
= 0.2 and 0.6) is synthesized by a solid-state method. All the compounds crystallize in the orthorhombic lattice with space group ...C222
1
. The infrared spectra of these compounds show characteristic bands due to a P
2
O
7
group. The two semicircles observed in the complex impedance identify the presence of the grain interior and grain boundary contributions to the electrical response in these materials. The frequency independent conductivity of these compounds shows Arrhenius-type behavior. The activation energies have been calculated at the levels of impedance, electric modulus studies, and DC conductivity which suggest that the conductions are ionic in nature. The conductivity increases with an increase in Ag substitution. In order to determine the conduction mechanism, the AC conductivity and its frequency exponent have been analyzed in this work by a theoretical model based on quantum mechanical tunneling: the non-overlapping small polaron tunneling model (NSPT) is confirmed for
x
= 0.2 and
x
= 0.6. The conduction mechanism is studied with the help of Elliot’s theory, and the Elliot’s parameters are determined.
In this work, the performance analysis and discussion of a space vector modulation technique used for a three-phase direct matrix converter feeding a three-phase induction motor is presented. For ...this, the induction motor models and the method of the space vector modulation technique are developed. Then, the overall electrical drive system is simulated using MatLab/Simulik software. Results obtained from simulation are the harmonic spectrum analysis of the motor current and the total harmonic distortion for unbalanced input voltages. These results show the good performance of the control system strategy.
This work presents some electrical properties based on impedance measurements as well as the dielectric constants and electric modulus. In order to study the electrical conductivity and dielectric ...properties of PrNaMnMoO
6
, complex impedance spectroscopy techniques were carried out in the frequency range 200 Hz–5 MHz at various temperatures (409–457 K). The complex impedance diagram at different temperatures showed a single semicircle, implying that the response originated from a single capacitive element corresponding to the grains. AC and dc conductivities were studied to explore the mechanisms of conduction. It can be seen from the experimental data that the AC conductivity of this compound is proportional to ω
s
(s < 1), and the value of s is to be temperature-dependent, which has a tendency to decrease in temperature. Activation energy values deduced from both dc conductivity and hopping frequency are in the order of E
a
= 0.32 eV and E
a
= 0.29 eV, respectively. The two values E
a
= 0.32 eV and E
a
= 0.29 eV of activation energies obtained from the hopping frequency and equivalent circuit confirms that the transport is through an ion hopping mechanism dominated by the motion of the Na
+
ion in the structure of the investigated material. In general, the size of the A ion influences the crystal symmetry significantly, while that of the B ion does not change the symmetry, but changes the lattice volume proportionally. The influence of the nature of the divalent A-site cations on the dielectric properties was evaluated by resistivity measurements in the frequency range. It is found that relative permittivity and dielectric loss regularly change with A cation size.
Many scientific researchers have proposed the control of the induction motor without speed sensor. These methods have the disadvantage that the variation of the rotor resistance causes an error of ...estimating the motor speed. Thus, simultaneous estimation of the rotor resistance and the motor speed is required. In this paper, a scheme for estimating simultaneously the rotor resistance and the rotor speed of an induction motor using fuzzy logic has been developed. We present a method which is based on two adaptive observers using fuzzy logic without affecting each other and a simple algorithm in order to facilitate the determination of the optimal values of the controller gains. The control algorithm is proved by the simulation tests. The results analysis shows the characteristic robustness of the two observers of the proposed method even in the case of variation of the rotor resistance.
The polycrystalline samples of Li
4
P
2
O
7
were prepared by solid-state reaction technique. The formation of the compounds was checked by X-ray diffraction technique (XRD). Detailed dielectric and ...electrical properties of the compounds were analyzed as a function of frequency (200 Hz–5 MHz) and temperature (611–671 K). The impedance data were well fitted to two equivalent electrical circuits. The results of the modulus study reveal the presence of two distinct relaxation processes suggesting the presence of grains and grain boundaries in the sample. Analysis of the dielectric constants
ε
″ and loss tangent tan (
δ
) with frequency shows a distribution of relaxation times. The activation energy found from the Arrhenius plot confirms that the conduction process in the material is not due to simple hopping mechanism. The temperature dependence of frequency exponent
s
was investigated to understand the conduction mechanism in Li
4
P
2
O
7
. The overlapping large polaron tunneling (OLPT) model can explain the temperature dependence of the frequency exponent.
L’éducation thérapeutique portant sur les techniques d’inhalation occupe une place importante dans la prise en charge thérapeutique de la maladie asthmatique. L’efficacité thérapeutique des ...dispositifs d’inhalation (DI) est fortement conditionnée par une technique d’inhalation rigoureuse.
Évaluer la qualité de la technique d’inhalation et mesurer l’impact d’une méthode éducative directe, centrée sur la technique d’utilisation des DI, sur l’amélioration de cette technique et sur le contrôle de la maladie.
Étude prospective descriptive, menée entre septembre–décembre 2021, incluant 43 patients suivis pour asthme confirmé, régulièrement pendant au moins 6 mois à la consultation d’allergologie C de l’hôpital Mami Ariana, sous traitement inhalé au long cours prescrit depuis au moins 6 mois avant l’inclusion dans l’étude. Un programme d’éducation thérapeutique a comporté 3 niveaux d’action : identification des erreurs dans la technique d’inhalation, démonstration de la technique d’inhalation et évaluation de l’éducation thérapeutique.
L’âge moyen des patients est de 40,7 ans±17 avec une prédominance féminine à 86 %. Les DI utilisés par nos patients ont été les aérosols doseurs AD (75 %) et les inhalateurs de poudre sèche IPS (25 %). La moyenne des erreurs d’inhalation par patient a été de 3,5 erreurs/patient pour les AD, et 4 erreurs/patient pour les IPS. Les erreurs d’inhalation ont été positivement corrélés à l’âge avancé (p=0,045) et le nombre des DI utilisés (p=0,01). Notre programme d’éducation a permis une amélioration significative du nombre d’erreurs/patient avec une amélioration du contrôle de l’asthme (p<0,05).
L’éducation thérapeutique personnalisée par une méthode directe et individuelle centrée sur les techniques d’inhalation permet d’améliorer le contrôle et l’évolution de la maladie asthmatique.
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