Eutectic Microbonding of Composite Materials Using Microwave Technology

2021 ◽  
Vol 1164 ◽  
pp. 17-23
Author(s):  
Robert Cristian Marin ◽  
Iulian Ştefan ◽  
Răzvan Ionuţ Iacobici ◽  
Sorin Vasile Savu
Keyword(s):  
Magnetic Materials ◽  
Electromagnetic Waves ◽  
Large Scale ◽  
Input Power ◽  
Thermal Source ◽  
Microwave Generator ◽  
Eutectic Alloys ◽  
Ball Mills ◽  
Load Impedance ◽  
Base Materials

The paper aims to report researches in microbonding process of composite magnetic materials using as thermal source the heat produced in base materials by the conversion of the electromagnetic waves with high frequency into thermal energy. This technology can be applied by targeting the base materials with microwaves and taking into account that composite magnetic materials based on ferrites, present good absorbance and conversion properties of the microwaves into heat. For experimental research, the base materials were sintered sampled of raw products obtained from stoichiometric mixtures of 6Fe2O3 + BaCO3. The raw products were obtained by milling and alloying processes using planetary ball mills. The milling and alloying processes have been perfomed in dry environement for homogeneous mixtures and wet environment for mixtures obtained using mechanical alloying. In terms of eutectic alloys used for microbonding, there have been used lead free Sn96,5%+Ag3%+Cu0,5% with melting point around 2170 C. The microbonding process have been perfomed in two steps: first step was focused on prepairing the base materials by cleaning and deposition of eutectic alloys on their surfaces; the second step was the heating of the base materials in microwave field. A microwave generator with adjustable input power from 0 W to 6000 W with a WR340 waveguide have been used as thermal sources. The researches have shown that the base materials were bonded using less than 10 % of microwave power and the eutectic alloys reached the melting temperature în less than 3 seconds when the magnetron was set to full power. A matching load impedance automatic tuner up to 6000 W have been used for increasing the level of absorbed power from nicrowave generator to samples and decreasing the level of rejected power from composite magnetic material to microwave generator. The temperature have been measured using IR pyrometers with range measurement between 0 and 7000 C. The process can be succesfully applied to a large scale for small parts of electrical engines with permanent cermic magnets.

scholarly journals Wireless power transfer system rigid to tissue characteristics using metamaterial inspired geometry for biomedical implant applications

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ramesh K. Pokharel ◽  
Adel Barakat ◽  
Shimaa Alshhawy ◽  
Kuniaki Yoshitomi ◽  
Costas Sarris
Keyword(s):  
Electromagnetic Waves ◽  
Wireless Power Transfer ◽  
Split Ring Resonator ◽  
Input Power ◽  
Power Transfer ◽  
Wireless Power ◽  
Biomedical Implant ◽  
Safety Regulations ◽  
Wireless Power Transfer System ◽  
Tissue Characteristics

AbstractConventional resonant inductive coupling wireless power transfer (WPT) systems encounter performance degradation while energizing biomedical implants. This degradation results from the dielectric and conductive characteristics of the tissue, which cause increased radiation and conduction losses, respectively. Moreover, the proximity of a resonator to the high permittivity tissue causes a change in its operating frequency if misalignment occurs. In this report, we propose a metamaterial inspired geometry with near-zero permeability property to overcome these mentioned problems. This metamaterial inspired geometry is stacked split ring resonator metamaterial fed by a driving inductive loop and acts as a WPT transmitter for an in-tissue implanted WPT receiver. The presented demonstrations have confirmed that the proposed metamaterial inspired WPT system outperforms the conventional one. Also, the resonance frequency of the proposed metamaterial inspired TX is negligibly affected by the tissue characteristics, which is of great interest from the design and operation prospects. Furthermore, the proposed WPT system can be used with more than twice the input power of the conventional one while complying with the safety regulations of electromagnetic waves exposure.

scholarly journals The relationship between small-scale and large-scale ionospheric electron density irregularities generated by powerful HF electromagnetic waves at high latitudes

2006 ◽  
Vol 24 (11) ◽  
pp. 2901-2909 ◽  
Author(s):  
E. D. Tereshchenko ◽  
B. Z. Khudukon ◽  
M. T. Rietveld ◽  
B. Isham ◽  
T. Hagfors ◽  
...  
Keyword(s):  
Geomagnetic Field ◽  
Electromagnetic Waves ◽  
Large Scale ◽  
Small Scale ◽  
Direction Parallel ◽  
Model Calculations ◽  
Amplitude Fluctuations ◽  
Field Lines ◽  
Experimental Values ◽  
Magnetic Zenith

Abstract. Satellite radio beacons were used in June 2001 to probe the ionosphere modified by a radio beam produced by the EISCAT high-power, high-frequency (HF) transmitter located near Tromsø (Norway). Amplitude scintillations and variations of the phase of 150- and 400-MHz signals from Russian navigational satellites passing over the modified region were observed at three receiver sites. In several papers it has been stressed that in the polar ionosphere the thermal self-focusing on striations during ionospheric modification is the main mechanism resulting in the formation of large-scale (hundreds of meters to kilometers) nonlinear structures aligned along the geomagnetic field (magnetic zenith effect). It has also been claimed that the maximum effects caused by small-scale (tens of meters) irregularities detected in satellite signals are also observed in the direction parallel to the magnetic field. Contrary to those studies, the present paper shows that the maximum in amplitude scintillations does not correspond strictly to the magnetic zenith direction because high latitude drifts typically cause a considerable anisotropy of small-scale irregularities in a plane perpendicular to the geomagnetic field resulting in a deviation of the amplitude-scintillation peak relative to the minimum angle between the line-of-sight to the satellite and direction of the geomagnetic field lines. The variance of the logarithmic relative amplitude fluctuations is considered here, which is a useful quantity in such studies. The experimental values of the variance are compared with model calculations and good agreement has been found. It is also shown from the experimental data that in most of the satellite passes a variance maximum occurs at a minimum in the phase fluctuations indicating that the artificial excitation of large-scale irregularities is minimum when the excitation of small-scale irregularities is maximum.

scholarly journals Printed and Flexible Microheaters Based on Carbon Nanotubes

Nanomaterials ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1879
Author(s):  
Aniello Falco ◽  
Francisco J. Romero ◽  
Florin C. Loghin ◽  
Alina Lyuleeva ◽  
Markus Becherer ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Small Area ◽  
Large Scale ◽  
Operating Temperature ◽  
Flexible Substrate ◽  
Cost Effective ◽  
Input Power ◽  
Maximum Temperature ◽  
Flexible Sensors ◽  
Manufacturing Method

This work demonstrates a cost-effective manufacturing method of flexible and fully printed microheaters, using carbon nanotubes (CNTs) as the heating element. Two different structures with different number of CNT layers have been characterized in detail. The benchmarking has been carried out in terms of maximum operating temperature, as well as nominal resistance and input power for different applied voltages. Their performances have been compared with previous reports for similar devices, fabricated with other technologies. The results have shown that the heaters presented can achieve high temperatures in a small area at lower voltages and lower input power. In particular, the fully printed heaters fabricated on a flexible substrate covering an area of 3.2 mm2 and operating at 9.5 V exhibit a maximum temperature point above 70 °C with a power consumption below 200 mW. Therefore, we have demonstrated that this technology paves the way for a cost-effective large-scale fabrication of flexible microheaters aimed to be integrated in flexible sensors.

Achieving Quasi-Isothermal Air Compression With Multistage Compressors for Large-Scale Energy Storage

2013 ◽  
Author(s):  
Kai Wang ◽  
Peiwen Li ◽  
Ara Arabyan
Keyword(s):  
Energy Storage ◽  
Compression Ratio ◽  
Large Scale ◽  
High Efficiency ◽  
Pressure Ratio ◽  
Compressed Air ◽  
Thermal Source ◽  
Round Trip ◽  
Compression Process ◽  
Compression Scheme

The round trip efficiency of compressed air for energy storage is greatly limited by the significant increase in the temperature of the compressed air (and the resulting heat loss) in high-ratio adiabatic compression. This paper introduces a multi-stage compression scheme with low-compression-ratio compressors and inter-compressor natural convection cooling resulting in a quasi-isothermal compression process that can be useful for large-scale energy storage. When many low pressure ratio compressors work inline, a high overall compression ratio can be achieved with high efficiency. The quasi-isothermally compressed air can then be expanded adiabatically in turbines to generate power with the addition of thermal energy, from either fuel or a solar thermal source. This paper presents mathematical models of such an energy storage system and discusses its round-trip performance with different operating schemes.

Evaluation of Composite Electromagnetic Wave Absorber made of Polystyrene Resin and Permalloy or Sendust

2007 ◽  
Vol 350 ◽  
pp. 239-242 ◽  
Author(s):  
Kenji Sakai ◽  
Shinzo Yoshikado
Keyword(s):  
Electromagnetic Wave ◽  
Magnetic Materials ◽  
Electromagnetic Waves ◽  
Return Loss ◽  
Soft Magnetic Materials ◽  
Complex Permeability ◽  
Soft Magnetic ◽  
Mixture Ratio ◽  
Polystyrene Resin ◽  
Frequency Dependences

The frequency dependences of the complex permeability μ r*, complex permittivity ε r*, and return loss were investigated for composite electromagnetic wave absorbers made of soft magnetic materials (permalloy or sendust) and polystyrene resin. For permalloy, two types of particle shape were used: grain-type or flake-type. The volume mixture ratio of magnetic materials was varied in the range from 40 % to 70 %. The values of the real part μ ’ and imaginary part μ ” of μ r * increased with increasing mixture ratio of magnetic materials. The frequency dependence of μ r * for flake-type permalloy composite was similar to that for sendust composite. All absorbers showed the absorption of electromagnetic waves in the frequency range above 1 GHz.

scholarly journals Review of The Effectiveness of Plant Media Extracts in Barium Hexaferrite Magnets (BaFe12O19)

2021 ◽  
Vol 6 (2) ◽  
pp. 39-52
Author(s):  
Jaya Edianta ◽  
Nanang Fauzi ◽  
Marzuki Naibaho ◽  
Fitri Suryani Arsyad ◽  
Idha Royani
Keyword(s):  
Hydrothermal Synthesis ◽  
Literature Review ◽  
Magnetic Materials ◽  
Electromagnetic Waves ◽  
Sol Gel ◽  
Synthesis Method ◽  
Barium Hexaferrite ◽  
Material Synthesis ◽  
Betel Leaf ◽  
Herbal Plant

Betel leaf is a typical Indonesian herbal plant that propagates on other tree trunks. So far, betel leaf has only been used in biomedicine and traditional medicine, whereas the chemical compounds of betel leaf can be used to absorb electromagnetic waves. In this mini-review, we review several research results to discuss the potential effectiveness of betel leaf in barium hexaferrite as an absorber of electromagnetic radiation. We compiled this mini-review based on the literature review method that is discussed extensively and in-depth regarding the chemical composition of betel leaf, modification of the development of barium hexaferrite material with betel leaf media extract, characteristics of BaFe12O19 as absorption of electromagnetic waves, and the effectiveness of media extracts in BaFe12O19 as absorption of electromagnetic waves. Based on the results of the literature review, the modification of BaFe12O19 material synthesis can include microemulsion, solid-state, coprecipitation, sol-gel, and hydrothermal synthesis. So far, hydrothermal synthesis is a synthesis method of mixing betel leaf extract media and ferrite-based magnets that have been studied before. Betel leaf in ferrite-based magnetic materials has been studied not to damage the surface morphology and characteristics of the magnetic material. The results of the assessment also show the effectiveness of adding other elements or compounds such as Ni, Al2O3, and composites in ferrite-based magnetic materials that can absorb more than 90% of electromagnetic waves in the frequency range 2-18 GHz.

scholarly journals RIS-Assisted Space-Air-Ground Integrated Networks: New Horizons for Flexible Access and Connectivity

2021 ◽  
Author(s):  
Lina Bariah ◽  
Lina Mohjazi ◽  
Hanaa Abumarshoud ◽  
Bassant Selim ◽  
sami muhaidat ◽  
...  
Keyword(s):  
Electromagnetic Waves ◽  
Large Scale ◽  
Low Cost ◽  
High Rate ◽  
Time Variability ◽  
Disruptive Technology ◽  
Efficient Manner ◽  
Integrated Network ◽  
Integrated Networks ◽  
Research Issues

Space-air-ground integrated network (SAGIN) has emerged as a paradigm shifting architecture that offers large-scale, flexible wireless coverage and seamless, high-rate connectivity to complement terrestrial communications. Nonetheless, unlocking the potentials of SAGIN is subject to addressing non-trivial challenges associated with their inherent time-variability, self-organization, and heterogeneity. Meanwhile, the concept of reconfigurable intelligent surfaces (RISs) is recognized as a disruptive technology that supports an unprecedented control of electromagnetic waves propagation and potentially offers significant enhancements in spectral efficiency, coverage expansion, and security, all achieved in a low-cost and energy-efficient manner. We anticipate that the integration of RISs into SAGIN will not only play a fundamental role in improving the quality of inter- and intra- layer communications, but will also provide complex interactions among the three network segments, and hence, opens the horizons for a new breed of applications across all industries. In this article, we explore the underlying opportunities and challenges of integrating RIS-enabled communications into SAGIN, and present a forward-looking overview of the cross-layer operational elements supported by RISs. Finally, we outline major enabling technologies and present a look ahead toward addressing open research issues.

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