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The melt-quenching method was used to manufacture newly synthesized glasses with a nominal composition of 60B2O3 – 20CaO – 15ZnO – 5Li2O – xEu2O3: 0 (Eu-0.0) ≤ x ≤ 0.5 (Eu-0.5) mol%. The structural, physical, FTIR, UV–visible spectra, and mechanical properties of the synthesized Eu-x glasses are examined. XRD results verified the amorphous condition of proposed glasses. The density (ρ) of the prepared glasses increased from 3.231 to 3.338 g cm−3, but in contrast, the molar volume (VM) decreased from 20.643 to 20.506 cm3 mol−1 with increasing Eu3+ ions. FTIR spectroscopy illustrated absorbance peaks appear around 393 and 464 nm, which indicates the presence of electronic states in the wide band gap of glass matrix. These peaks are attributed to the 5L6 and 5D2 electronic states of Eu3+ ions. UV–visible measurements showed an improvement in optical absorbance and a decrease in optical energy gap. The Eu3+ ions mol% doping into the proposed glasses results in generating photoluminescence glasses, which is attributed to the 5D0 → 7F1, 5D0 → 7F2, 5D0 → 7F3, and 5D0 → 7F4 electronic transitions of Eu3+ ions. Thus, the emission spectra due to the 393 nm excitation results in the appearance of emission peaks at 593 (orange), 617 (strong red), 653 (red), and 698 (red) nm. The Poisson's ratio (σ) of Eu-x glasses is decreased from 0.3927 to 0.3903 as the molar fraction of Eu3+ ions is increased from 0.0 to 0.5 mol%. The thermodynamic properties of the glassy network are hidden in the Gibbs free energy (G) which started at 33.56 and ended at 33.72 kJ.cm−3 at low and high Eu3+ ions content mol%. Furthermore, all elastic moduli increased linearly with molar increment of Eu3+ ions in the molecular structure of the proposed glassy network. [ABSTRACT FROM AUTHOR]

In this work, the role of insertion cobalt(II) on the physical properties, dielectric spectroscopy, and photon attenuation parameters of the prepared glasses 25NaF-10ZnO-(65-x)B2O3-xCoO-0.6Y2O3: x = 0.0 (Co-0.0) ≤ x ≤ 0.5 (Co-0.5) mol% has been investigated. The amorphous state of samples verified via the XRD measurements. The density (ρ) ∈ [2.9824, 3.0058 g.cm−3]. The molar volume (Vm) ∈ [21.868, 21.715 cm3.mol−1] as an increase of CoO from 0.0 to 0.5 mol% in the glass network. Dielectric spectroscopy of borate glass loaded with varying cobalt content was investigated throughout frequency range from 50 to 5 MHz. The recorded dielectric constant at 3 kHz was enhanced from 14.4 to 17.8 by cobalt doping. The dependency of tangent loss (tan δ) for all investigated glasses on frequency is normal behavior with dielectric relaxation which is enhanced and shifted by cobalt doping. At the photon energy (E = 0.015 MeV), the mass-attenuation-coefficient (MAC) values were 10.192, 10.246, 10.300, 10.354, and 10.408 cm2/g for the samples Co-0.0, Co-0.1, Co-0.2, Co-0.30, Co-0.4, and Co-0.5, respectively. These MAC values are corresponding to as increment of 0.216 cm2/g between the low and high CoO contents presented in the glass samples. Values of half value layer (HVL) of all proposed specimens were more significant than that of RS-360 and RS-520 commercial glasses. Results confirmed that the suggested glasses are suitable for radiation attenuation. [ABSTRACT FROM AUTHOR]

Instability of an adaptive flux observer (AFO) in the regenerating mode at low frequencies is a great challenge of sensorless induction motor (SIM) drives. Zero observer feedback gains (OFGs) in the regenerating mode at low frequencies are the main reasons for moving the dominant zero of the speed estimators to the unstable region. OFGs should be appropriately selected to transfer the unstable dominant zero to the stable region. In this paper, genetic algorithm (GA) and particle swarm optimization (PSO) techniques were used to design the OFGs for a stable observer. A fair comparison of the dominant zero location between the two approaches using the optimized OFGs is presented under parameter deviation. Analytical results and the design procedure of the OFGs using the two approaches are presented under deviations of stator resistance and mutual inductance to guarantee a stable dominant zero in the regenerating mode of IM. The dominant zeros obtained by PSO had a superior location to that obtained by GA for both stator resistance and mutual inductance deviations. It was observed that one of the gains had an almost constant value over a wide range of parameter deviations. However, the value of the other gain was dependent on the deviation of machine parameters. The advantage of using PSO over GA is that the relation between the gain and parameter deviation can be represented by a deterministic and mostly linear relationship. Simulation and experimental work of the SIM drive are presented and evaluated under the optimized OFGs. [ABSTRACT FROM AUTHOR]

Nowadays, multi-criteria decision-making (MCDM) methods are used widely in many fields of research and applications. Many studies have shown that MCDM approaches are effective in determining the optimal solution to a variety of symmetrical and asymmetrical problems with numerous parameters. This article investigates a novel approach using multi criteria decision making (MCDM) to optimize the parameters of static var compensator (SVC) and power system stabilizers (PSS). The proposed technique integrates similarity membership function reduction algorithm (SMFRA), removal effects of criteria (REC) and combined compromise solution (CoCoSo). In the first stage, (SMFRA) is employed to select the most dominant controller parameters in the optimization process. Secondly, the weights of the reduced parameters are computed based on (REC). Finally, (CoCoSo) method searches for the optimal setting parameters. A detailed sensitivity analysis is presented to evaluate the obtained results. It is found that the suggested integrated technique is time saving, easily implemented and of low computation burden, which can successfully be implemented to solve a wide range of issues, both comparable and dissimilar. [ABSTRACT FROM AUTHOR]

The ability of space plasmas to self-regulate through mechanisms involving self-generated fluctuations is a topic of high interest. This paper presents the results of a new advanced quasilinear (QL) approach for the instability of electromagnetic ion-cyclotron modes driven by the relative alpha-proton drift observed in solar wind. For an extended parametric analysis, the present QL approach includes also the effects of intrinsic anisotropic temperatures of these populations. The enhanced fluctuations contribute to an exchange of energy between proton and alpha particles, leading to important variations of the anisotropies, the proton-alpha drift and the temperature contrast. The results presented here can help understand the observational data, in particular, those revealing the local variations associated with the properties of protons and alpha particles as well as the spatial profiles in the expanding solar wind. [ABSTRACT FROM AUTHOR]

In this paper, firstly we introduce the notions of soft supra locally α -closed sets in soft supra topological spaces. We investigate the relationships with different types of subsets of soft supra topological spaces. Secondly, we introduce the notion of SSL- α C-continuous functions and a decomposition of soft supra continuity is obtained. [ABSTRACT FROM AUTHOR]

This paper proposes an adaptive flux observer (AFO) method of sensorless induction motor (IM) drives. The AFO gains are designed to ensure accurate estimated speed, especially at very low frequencies in the regenerating mode of operation. Stability analysis of AFO with the designed gains is presented using the Lyapunov theory. These gains are calculated to be adaptively dependent on the IM variables and parameters. The observer gains play a significant role on the stability and precision of AFO in the regenerating mode. The influence of the machine parameters mismatch on the AFO stability with zero feedback gains as well as the proposed feedback gains is provided. The sensitivity to stator resistance is also analyzed. The complete sensorless IM drive with the proposed AFO is executed by both MATLAB/Simulink program, and also in the laboratory. Analytical and experimental results under various working conditions are provided to prove the effectiveness of the proposed AFO, especially at very low stator frequencies. [ABSTRACT FROM AUTHOR]

In this study, the role of TiO2 on the physica, and optical properties as well as the γ-ray protection features of a set of six glass samples with the chemical formula (65-X)B2O3–15BaO–5Bi2O3–15ZnO–XTiO2, where X = 0–10 mol% in the step of 2% have been investigated. The density (ρ) increased gradually from 3.70 to 3.93 g/cm3 and the molar volume (Vm) reduced from 27.71 to 26.72 cm3/mol as the TiO2 content increased from 0 to 10 mol%. By the inclusion of TiO2 in the glass networks, some absorption bands in the ultraviolet and visible regions are formed. Values of the indirect optical band gaps (Eg) were 2.550, 2.510, 2.470, 2.370, 2.270, and 2.180 eV for Ti-0.0, Ti-2.0, Ti-4.0, Ti-6.0, Ti-8.0, and Ti-10.0 glasses, respectively. The linear refractive index (n0) calculated values varied from 2.515 to 2.631. The linear-attenuation coefficient ( μ) followed the order: Ti-0.0 < Ti-2.0 < Ti-4.0 < Ti-6.0 < Ti-8.0 < Ti-10.0. The sample coded as Ti-10.0 glass sample (highest content of TiO2) has the lowest half (HVL) and tenth (TVL) value layer. Within the investigated energy range of within the range: 51.590–19.480, 50.676–19.722, 50.696–19.833, 50.271–20.012, 49.860–20.193, and 49.460–20.376 for the prepared samples Ti-0.0, Ti-2.0, Ti-4.0, Ti-6.0, Ti-8.0, and Ti-10.0 glasses, respectively. Results confirmed that the suggested titanium bismo-borate glasses can be used in the optical field and as alternative materials for radiation shielding applications. [ABSTRACT FROM AUTHOR]

In the present article, samples of erbium (Er)-doped bismo-borate glasses have been fabricated with general chemical compositions: 70B2O3–10CaO–10Li2O−(10-x)Bi2O3− xEr2O3: 0 (Er-0.0) ≤ x ≤ 1 (Er-1.0) mol% using the conventional melt-quench process. The impact of Er3+ ions on the structure and optical (linear and nonlinear) characteristics of Er-0.0/Er-1.0 glass blocks have been investigated. XRD measurements showed the lack in crystallinity of the prepared samples. In the range of UV-Vis measurements, there are absorption bands attributed to the electronic transitions (4f−4f) of Er3+ ions. The absorption bands seen at wavelengths of approximately 366, 379, 409, 452, 490, 523, 545, 653, 797, and 978 nm are associated with electronic transitions from the ground state, 4I15/2, to several excited states, namely 4G9/2, 2G11/2, 2H9/2, 4F5/2, 4F7/2, 2H11/2, 4S3/2, 4F9/2, 4I9/2, and 4I11/2, respectively. The optical band gap (Eg) values ranged from 2.61 to 3.11 eV for Er0.0 to Er1.0 glass samples, respectively. Values of linear refractive index (n0) ranged from 2.498 to 2.374. Values of the nonlinear refractive index varied from 7.76 to 4.99, while the third order non-linear optical susceptibility (χ(3)) values ranged from 5.14 to 3.14 for Er0.0 to Er1.0 glasses, respectively. Therefore, the suggested glasses can be used in several optical applications such as opto-electronic devices. [ABSTRACT FROM AUTHOR]

The influence of nickel-oxide (NiO) addition on the structural, optical, physical properties, and dielectric spectroscopy of lead-borated glass blocks of the chemical form: (70-x)B2O3-25Na2O-5PbO-xNiO: x = 0 (Ni-0.0)-2.5 (Ni-2.5) molar percentage was tested experimentally using various methods. X-ray diffraction measurements confirmed the amorphous character of prepared Ni-glasses. Density increased gradually from 2.5981 to 2.7568 g cm−3, whereas molar-volume declined from 29.0131 to 28.0202 cm3 mol−1 as Ni2+ ions-contenting samples improved from 0.0 to 2.5 mol% in glasses network. In the absorption UV-region, optical-gap energy changed between 2.94 and 2.48 eV. In absorption within Vis-region, the intensity of the absorbed band enhanced gradually with red-shift in their positions as Ni2+ ions content increased. In the absorption NIR-region, an increase in the IR absorption bands was observed and confirmed the enhanced heat-absorption capacity of the investigated glasses as their NiO content increased. Dielectric spectroscopy at frequencies ranging from 50 Hz to 5 MHz of (70-x)B2O3-25Na2O-5PbO-xNiO: x = 0, 0.5, 1.0, 1.5, 2.0, and 2.5 mol% glasses are carried out to determine the impact of nickel doping on dielectric spectroscopy items. Nickel doping gradually increased the dielectric constant. At high frequencies, the transport rate among nearby conductive sites is increased while the shifting length of the charges is greatly reduced which leads to higher conductivity. [ABSTRACT FROM AUTHOR]

Six specimens of iron (II)-doped borate glasses with the following chemical formula: 75B2O3–15PbO–10BaO3–xFe2O3: x = 0.0–0.5 mol% with an incremental step of 0.1 were produced using the traditional melt quench method. The effects of iron ion doping on mechanical, dielectric properties, and radiation protection effectiveness (RPE) of the prepared samples were investigated. The oxygen-packing density (OPD) and molar volume (OMV) increased as iron (II) content increased in the glasses network. Therefore, the created non-bridging oxygen (NBO) increased. Elastic parameters of the investigated samples enhanced as a function of Fe2O3 content. As the molar percentage of Fe2O3 increased from 0 to 5.0 mol%, Poisson's glasses ratio fluctuates between 0.365 and 0.3700. As the energy of the incoming photon increases, the RPE tends to fall below 100% in low-energy regions. The sample with the code Fe2O3-0.5 exhibits the smallest value (R = 0.156498 cm−1) and the largest molar fraction (Fe2O3 = 0.5 mol%), as well as the maximum molar volume and Vickers hardness. Dielectric spectroscopy of manufactured glasses is investigated at various frequencies ranging from 50 Hz to 5 MHz at room temperature to explore chemical alterations caused by iron doping on dielectric spectroscopy components like the dielectric constant ( ε ′ ) and tangent loss (tan δ). Results showed that the dielectric constant drastically declines with a rise in the frequency domains up to 700 Hz for all glasses doped with varying amounts of iron and appears almost constant at higher frequencies for all glasses. The inclusion of iron increased the amount of (NBO) elements in the inside molecular framework of glass, which significantly increased the dielectric constant. [ABSTRACT FROM AUTHOR]

This study investigates the synthesis, physical, vibrational, optical, and dielectric characteristics of bismuth-borate barium glasses doped with chromium, with the aim of exploring their potential for use in optical applications. The chemical formula of the proposed glasses was (70-x)B2O3 − 10Bi2O3 − 20BaO − xCrO3: x = 0 (BBBCr0.0) − 0.5 (BBBCr0.5) mol%. The structure nature was examined. The physical features, FTIR spectroscopy, and linear/nonlinear optical properties have been investigated. Based on the XRD measurements, the prepared glasses were amorphous in nature. The density (ρ) of the glasses slightly decreased, while the molar volume (Vm) increased with increasing CrO3 content in the glass network. The percentage fraction of BO4 (N4) gradually increased at the expense of the percentage fraction of BO3 (N3) as the chromium content increased up to 0.2 mol%. However, for concentrations of chromium over 0.2 mol%, a reverse transformation from BO4 to BO3 was detected. The optical energy bands (Eg) changed from 3.07 to 1.41 eV, whereas the linear refractive index (n0) changed from 2.38 to 2.98 for BBBCr-glasses. The metallization criterion (M) values ranged from 0.392 to 0.265, indicating that the glasses have a wide range of potential for use in various optical applications. In addition, the nonlinear refractive index (n2) values ranged from 3.26 × 10−11 to 26.35 × 10−11 (esu), while the χ(3) values varied from 5.16 × 10−12 to 33.34 × 10−12 (esu) for the BBBCr-glasses with chromium concentrations ranging from 0.0 to 0.5 mol%. The real part of permittivity has the same value with chromium doping up to 0.2 mol% and then it is highly increased for concentrations greater than 0.2 mol%. The findings of this study highlight the potential of bismuth-borate barium glasses doped with chromium as a highly versatile and adaptable material for use in a range of optical applications. [ABSTRACT FROM AUTHOR]

The electron firehose instabilities are among the most studied kinetic instabilities, especially in the context of space plasmas, whose dynamics is mainly controlled by collisionless waveâ€"particle interactions. This paper undertakes a comparative analysis of the aperiodic electron firehose instabilities excited either by the anisotropic temperature or by the electron counter-beaming populations. Two symmetric counter-beams provide an effective kinetic anisotropy similar to the temperature anisotropy of a single (nondrifting) population, with the temperature along the magnetic field direction larger than that in the perpendicular direction. Therefore, the counter-beaming plasma is susceptible to firehose-like instabilities (FIs), parallel and oblique branches. Here we focus on the oblique beaming FI, which is also aperiodic when the free energy is provided by symmetric counter-beams. Our results show that, for relative small drifts or beaming speeds (U), not exceeding the thermal speed (α), the aperiodic FIs exist in the same interval of wavenumbers and the same range of oblique angles (with respect to the magnetic field direction), but the growth rates of counter-beaming FI (CBFI) are always higher than those of temperature anisotropy FI (TAFI). For U / α > 1, however, another electrostatic two-stream instability is also predicted, which may have growth rates higher than those of CBFI, and may dominate in that case the dynamics. [ABSTRACT FROM AUTHOR]

Boundary layer analysis is invoked to clarify the aspects of variable thermal conductivity and thermophoretic forces on a steady state of MHD micropolar fluid flow in the existence of a uniform transverse magnetic field along an isothermal horizontal plate. The micropolar pattern permits the rotational freedom degrees that lead to couple stresses and a non symmetric stress tensor. The initiated PDEs governing the case pattern are mutated into a non-dimensional system due to proper transformations. The transformed mathematical governing equations are solved by implementing a very potent computer algebra software MATLAB code. The plotted graphs analyzed the attitude of multiple physical aspects involving factors on the flow attitude of micropolar velocity and angular velocity and temperature. Through the involved factors, the couple stress, skin friction and Nusselt number are manifested and interpreted amply. A new outcome for drag force and heat gradient experienced by the key factors is portrayed. Augmentation in Ω results in the thermophoretic forces that encapsulate the mass transmission. The local Nusselt number strengthened as the thermal conductivity, heat absorption factors or wall suction velocity were improved, and weakened due to the existence of viscous dissipation or heat generation impacts. As a particular case, the governing field equations of a classical Newtonian liquid are given by dropping the micropolar parameter impacts. [ABSTRACT FROM AUTHOR]

Zinc-lead-borate glasses doped with sodium oxides and varying molar quantities of nickel oxide ranging from 0.5 to 2.5 mol% having the form (70-x)B 2 O 3 –5ZnO–20Na 2 O–5PbO-xNiO denoted as Ni0.0 - Ni2.5 have been created using standard melt quenching procedure. The physical, structural, and radiation shielding competence of the samples under consideration have all been evaluated. The density of these glasses grew as the NiO portion in their glassy structure increased. Introduction of Ni ions generated magnified changes in the local field of borate ions, resulting in the formation of tetrahedral BO4 units. Values of the mass-attenuation coefficients (MACs) increased considerably with increasing NiO content. For NiO concentrations of 0.0, 0.5, 1.0, 1.5, 2.0, and 2.5 mol%, the obtained linear-attenuation coefficients (LACs) were 44.376, 45.398, 46.565, 47.977, 49.328, and 50.737 cm−1 at 0.015 MeV, respectively. The lowest half value layer (HVL) values were obtained at 0.015 MeV and ranged from 0.016 to 0.014 cm for Ni0.0 and Ni2.5, respectively. At photon energy (Eγ = 0.015 and 15 MeV), the effective atomic number (Z eff) of the investigated glasses ranged from 43.99 to 10.80 and 42.44 to 11.08 for Ni0.0 and Ni2.5, respectively. • B 2 O 3 –ZnO–Na 2 O–PbO–NiO glasses have been successfully fabricated. • Physical and FTIR characteristics have been investigated. • Radiation shielding capacities have been examined. • Suggested glasses can be applied in medical applications. [ABSTRACT FROM AUTHOR]

In this work, (Ni 0.5 Pb 0.5 Fe 2 O 4) nano-ferrites has been prepared by a flash auto combustion technique, then new films of polyvinyl chloride (PVC) doped with x(Ni 0.5 Pb 0.5 Fe 2 O 4) nanoparticles: x = 0 (PVC/PNF0) – 10 (PVC/PNF10) wt% have been fabricated. The nature, physical, linear optical as well as γ-ray attenuation capacity of the fabricated PVC/(Ni 0.5 Pb 0.5 Fe 2 O 4) nanocomposites (NCs) sheets have been investigated. The crystalline state of (Ni 0.5 Pb 0.5 Fe 2 O 4) NPs, and amorphous state of pure PVC, and PVC/(Ni 0.5 Pb 0.5 Fe 2 O 4) films were performed by XRD measurements. The density (ρ) increased from 1.4451 to 2.613 g cm−3 for PVC/PNF0 and PVC/PNF10 sheets as the (Pb 0.5 Ni 0.5 Fe 2 O 4) NPs content increased from 0 to 10 wt%. The direct band gap (E g a p d i r e c t ) decreased from 5.259 to 2.969 eV, whereas Urbach energy (E U) increased from 0.439 to 4.812 eV. The index of refraction (n) for the fabricated films increased with increasing the concentration of (Ni 0.5 Pb 0.5 Fe 2 O 4) NPs. The highest and lowest mass attenuation coefficient (MAC) values possessed at 0.015 and 15 MeV, respectively. The effective atomic number (Z eff) of the currently films followed the trend: (Z eff) PVC/PNF0 < (Z eff) PVC/PNF1 < (Z eff) PVC/PNF3 < (Z eff) PVC/PNF5 < (Z eff) PVC/PNF10. The half value layer (HVL) parameter possessed the trend: (HVL) PVC/PNF0 > (HVL) PVC/PNF1 > (HVL) PVC/PNF3 > (HVL) PVC/PNF5 > (HVL) PVC/PNF10. The fabricated PVC/(Ni 0.5 Pb 0.5 Fe 2 O 4) NCs films can be used in electronic, optical, and radiation shielding applications. • PVC doped with Ni-Pb spinel nano-ferrites samples has been fabricated. • Physical properties of the investigated nanocomposites have been studied. • Linear optical properties have been investigated. • Capacity of radiation attenuation of the fabricated films has been evaluated. [ABSTRACT FROM AUTHOR]