In this study, Absorption of high frequency radio Waves in the ionospheric plasma have been investigated. The Wave equation was obtained in terms of ionospheric parameters. The numerical values of the Absorption have been calculated for 4 MHz, 4.5 MHz and 5 MHz Waves. The necessary parameters for calculation have been obtained using an International Reference Ionosphere (IRI) Model. The altitudinal, diurnal, seasonal and the variations of Absorption with frequency have been examined. The calculations show that the highest Absorption occurs in the D-region. The Absorption is higher in summer than in other seasons and is maximum at daylight. In addition, Absorption decreases with the increase of frequency.

Reduced graphene oxide (rGO) and M-type hexagonal ferrites such as BaFe12O19 have attracted great attention as electromagnetic (EM) Wave absorbing materials in recent years. In this research, different weight percents of BaFe12O19/rGO nanocomposites were incorporated into the microWave absorbing layers and their EM Wave Absorption was investigated. Barium ferrite was synthesized through the co-precipitation method. Graphene oxide (GO) was synthesized through the modified Hummers’ method. The synthesized GO was reduced to rGO nanosheets using a reducing agent. The synthesized barium ferrite and rGO were then mechanically milled to form BaFe12O19/rGO nanocomposite. The chemical bondings, phase analysis, magnetic properties, particle morphology, and EM Wave absorbing properties were investigated using FTIR, XRD, Vibration Sample Magnetometer (VSM), FESEM, and Vector Network Analyzer (VNA), respectively. The saturation magnetization (Ms) and the coercivity (Hc) of the synthesized BaFe12O19/rGO nanocomposite were 31 emu/g and 1.5 kOe, respectively. The EM Absorption properties in the X-band (8.2-12.4 GHz) showed that the maximum reflection loss (RL) of -7.39 dB could be obtained for the nanocomposite containing only 10 wt. % of BaFe12O19/rGO nanocomposite in a resin matrix with a thickness of 2 mm.

In single-body converters of ocean Wave energy, oscillations of a floating body (buoy) serve as the main driving force for electricity generation. Buoy geometry optimization is known as an approach to enhance the efficiency of these converters. In the present research, the process of Wave energy Absorption in point absorber converter is modeled as a spring-damper system. Two geometries are considered for the buoy of the converter (conical and spherical-cap). The effects of buoy geometry on its dynamics in the nonlinear Wave are investigated and comparison of these effects on dynamic performances of the modeled converter is reported. Equalization of environmental conditions and modeling of the two models were discussed, and a new equalization method was proposed. Effective Wave energy on each model was calculated based on geometrical characteristics of the corresponding buoy. Then, the models were hydrodynamically analyzed via boundary element method by taking the diffraction theory as the governing theory. The incident Wave was assumed to be a second-order Stokes Wave. Results were obtained in both time and frequency domains and validated against the results of available research. Maximum dynamic responses of the restrained buoy with spherical-cap geometry in heave and surge (vertical and horizontal directions, respectively) were found about 4.4% and 11.3% higher than the conical buoy, respectively. The average percentage of absorbed Wave energy by the modeled converter with spherical-cap buoy was about 2.2-2.5% higher than that of the other model. The average percentage of absorbed energy by the models was predicted to range within 20-24%.

Larger width of P-cladding layer in p-i-n Waveguide of traveling Wave electro-Absorption modulator (TWEAM) results in lower resistance and microWave propagation loss which provides an enhanced high speed electro-optical response. In this paper, a full-vectorial finite-difference-based optical mode solver is presented to analyze mushroom-type TWEAM for the first time. In this analysis, the discontinuities of the normal components of the electric field across abrupt dielectric interfaces which are known as the limitations of scalar and semivectorial approximation methods are considered. The optical field distributions in mushroom-type TWEAM and conventional ridge-type TWEAM of the same active region for 1.55 mm operation are presented. The important parameters in the high-frequency TWEAM design such as optical effective index which defines optical velocity and transverse mode confinement factor are calculated. The modulation response of mushroom-type TWEAM is calculated by considering interaction of microWave and optical fields in Waveguide and compared to that of conventional ridge-type TWEAM. The calculated 3dB bandwidths for ridge-type and mushroom-type TWEAM are about 139 GHz and 166 GHz for 200 mm and 114 GHz and 126 GHz for 300 mm Waveguide length, respectively.

Background and Objective: Sound Absorption coefficient determination is an important factor in selecting the proper materials to control indoor noise. Therefore, this study aimed to compare the results of sound Absorption coefficient of different materials by standing Wave ratio and transfer function method, as well as developing a regression model in adjusting the provided results. Materials and Methods: The current study was conducted on 46 acoustic materials. In order to measure the Absorption coefficient of different materials, two instruments called the impedance tube (model 9410, AvaSina, Iran) and the impedance tube (model SW 260, BSWA, USA) in compliance with ISO 10534-2 in the frequency range of 125 to 2000 Hz were utilized. Results: The obtained results from the regression model revealed that frequency of 500 Hz has the highest correlation (r=0. 968, R2=0. 936), and the lowest correlation coefficient was found at 125 Hz (r=0. 368, R2=0. 136). In addition, the correlation coefficient of NRC was 0. 829. Conclusion: The results showed that the two methods were consistant at the frequencies of 250, 500, 1000 and 2000 Hz. It can be concluded that the standing Wave ratio method is a reliable approach in determining sound Absorption coefficient of acoustic materials.

In this study, barium strontium titanate/cobalt zinc ferrite composites that composed of two different magnetic phases were investigated. Pyroelectric phase consists of barium strontium titanate particles with particle size of about 150 nm and soft magnetic phase consists of cobalt zinc ferrite nanoparticles with particle size of about 30 nm. Two phases were prepared with sol-gel method and under appropriate stoichiometry. XRD analyses indicated formation of pure phase for each magnetic phases and FESEM analysis indicate the structural properties of Cobalt-Zinc ferrite and Barium Strontium Titanate nanoparticles. Investigation of permittivity, permeability and reflection loss of samples indicated the response of electromagnetic Waves to these samples in the frequency range of 1-18 GHz. According to the reflection loss of composites, there are two mechanisms for the Absorption of electromagnetic Waves. In the first region of this frequency band, magnetic loss from Cobalt-Zinc ferrite nanoparticles is dominate and in the last region of this frequency band, dielectric loss from barium strontium titanate is dominate.

Charge and spin transport properties of a clean $SNS$ Josephson junction (triplet superconductor-normal metal-triplet superconductor) are studied using the quasiclassical Eilenberger equation of Green’s function. Our system consists of two p-Wave superconducting crystals separated by a Copper nano layer. Effects of thickness of normal layer between superconductors on the spin and charge currents are investigated. Also misorientation between triplet superconductors which creates the spin current is another subject of this paper.

In this study, we investigate the electromagnetic Wave Absorption of Hard-Soft ferrite nanocomposites in the frequency range of 1-18 GHz. These composites consist of two different magnetic phases with different weight ratios. The hard magnetic phase consists of Strontium Hexaferrite (SF) and the soft magnetic phase consists of Cobalt Zinc Ferrite (CZF). XRD analysis of the samples indicate formation of pure phase for each magnetic phases. Investigation of the real and imaginary parts of complex permittivity and permeability of samples indicate the response of electromagnetic Waves to these samples in the frequency range of 1-18 GHz. The reflection loss versus frequency shows this absorbing behavior in the samples.