scholarly journals Composite Metamaterials: Classification, Design, Laws and Future Applications

2021 ◽  
Author(s):  
Tarek Fawzi ◽  
Ammar A.M. Al-Talib
Keyword(s):  
Electromagnetic Radiation ◽  
Power Management ◽  
Electromagnetic Waves ◽  
Solar Power ◽  
Natural Materials ◽  
Artificial Materials ◽  
Crowd Control ◽  
Potential Applications ◽  
Meta Atom

The development of science and applications have reached a stage where the naturally existed materials are not meeting the required properties. Metamaterials (MMs) are artificial materials that obtain their properties from their accurately engineered meta-atoms rather than the characteristics of their constituents. The size of the meta-atom is small compared to light’s wavelength. A metamaterial (MM) is a term means beyond material which has been engineered in order to possess properties that does not exist in naturally-found materials. Currently, they are made of multiple elements such as plastics and metals. They are being organized in iterating patterns at a scale that is smaller than wavelengths of the phenomena it influences. The properties of the MMs are not derived from the forming materials but their delicate size, geometry, shape, orientation, and arrangement. These properties maintain MMs to manipulate the electromagnetic waves via promoting, hindering, absorbing waves to attain an interest that goes beyond the natural materials’ potency. The apt design of MMs maintains them of influencing the electromagnetic radiation or sound in a distinctive technique never found in natural materials. The potential applications of MMs are wide, starting from medical, aerospace, sensors, solar-power management, crowd control, antennas, army equipment and reaching earthquakes shielding and seismic materials.

scholarly journals Phase-to-pattern inverse design paradigm for fast realization of functional metasurfaces via transfer learning

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Ruichao Zhu ◽  
Tianshuo Qiu ◽  
Jiafu Wang ◽  
Sai Sui ◽  
Chenglong Hao ◽  
...  
Keyword(s):  
Transfer Learning ◽  
Electromagnetic Waves ◽  
Inverse Method ◽  
Inverse Design ◽  
Learning Network ◽  
Design Paradigm ◽  
Simulation And Experiment ◽  
Meta Atom ◽  
Trained Network ◽  
Input Phase

AbstractMetasurfaces have provided unprecedented freedom for manipulating electromagnetic waves. In metasurface design, massive meta-atoms have to be optimized to produce the desired phase profiles, which is time-consuming and sometimes prohibitive. In this paper, we propose a fast accurate inverse method of designing functional metasurfaces based on transfer learning, which can generate metasurface patterns monolithically from input phase profiles for specific functions. A transfer learning network based on GoogLeNet-Inception-V3 can predict the phases of 28×8 meta-atoms with an accuracy of around 90%. This method is validated via functional metasurface design using the trained network. Metasurface patterns are generated monolithically for achieving two typical functionals, 2D focusing and abnormal reflection. Both simulation and experiment verify the high design accuracy. This method provides an inverse design paradigm for fast functional metasurface design, and can be readily used to establish a meta-atom library with full phase span.

scholarly journals Preventive measures to reduce harmful effects produced by electromagnetic radiation on health

2021 ◽  
pp. 42-53
Author(s):  
Y. Stein ◽  
◽  
Keyword(s):  
Electromagnetic Radiation ◽  
Electromagnetic Waves ◽  
Preventive Measures ◽  
Biological Effects ◽  
Scientific Evidence ◽  
Base Stations ◽  
Power Lines ◽  
Thermal Safety ◽  
Low Frequencies ◽  
Safety Standards

Man-made electromagnetic waves are the most widely and rapidly expanding exposure in today's world, including exposure in several frequency groups: extremely low frequencies (ELF) from electricity lines, hybrid car batteries and high power lines (>3 Hz–3 kHz), radiofrequency (RF) and microwave frequencies including millimeter waves (3 kHz–300 GHz) from mobile phones, towers, base stations and wireless devices, and intermediate frequencies "Dirty Electricity" emitted from power lines. While such organizations as ICNIRP (the International Commission on Non-Ionizing Radiation Protection) still continue to claim that electromagnetic radiation can cause "only thermal effects", clinging to theory that does not match facts and upholding obsolete thermal safety standards, extensive scientific evidence has clearly demonstrated that non-thermal health effects produced by electromagnetic radiation do exist, are important to health, and should be taken into consideration when safety standards are set. This review aims to highlight some evidence of biologic effects in various body systems, and to suggest preventive measures to reduce such effects on health. Exposure to electromagnetic radiation at intensities lower than thermal safety standards has been associated with non-thermal biological effects including damage and changes to cells and DNA. This review presents evidence of such effects demonstrated in: the hematologic system, the nervous system, the immune system, the reproductive system, the skin and muscles, the cardiovascular system, glucose metabolism, and Electrohypersensitivity ("Microwave sickness"). Protective measures are then suggested to reduce these effects.

Determination of the velocity of short electromagnetic waves by interferometry

1952 ◽  
Vol 213 (1112) ◽  
pp. 123-141 ◽  
Keyword(s):  
Phase Velocity ◽  
Electromagnetic Radiation ◽  
Free Space ◽  
Electromagnetic Waves ◽  
Wave Beam ◽  
Wave Length ◽  
Wave Frequency ◽  
Space Wave

A new measurement of the velocity of electromagnetic radiation is described. The result has been obtained, using micro-waves at a frequency of 24005 Mc/s ( λ = 1∙25 cm), with a form of interferometer which enables the free-space wave-length to be evaluated. Since the micro-wave frequency can also be ascertained, phase velocity is calculated from the product of frequency and wave-length. The most important aspect of the experiment is the application to the measured wave-length of a correction which arises from diffraction of the micro-wave beam. This correction is new to interferometry and is discussed in detail. The result obtained for the velocity, reduced to vacuum conditions, is c 0 = 299792∙6 ± 0∙7 km/s.

Hippocampal Oxidative Stress Induced by Radiofrequency Electromagnetic Radiation and the Neuroprotective Effects of Aerobic Exercise in Rats: A Randomized Control Trial

2021 ◽  
pp. 1-7
Author(s):  
Mina Rasouli Mojez ◽  
Abbas Ali Gaeini ◽  
Siroos Choobineh ◽  
Mohsen Sheykhlouvand
Keyword(s):  
Oxidative Stress ◽  
Superoxide Dismutase ◽  
Glutathione Peroxidase ◽  
Aerobic Exercise ◽  
Electromagnetic Radiation ◽  
Antioxidant Capacity ◽  
Electromagnetic Waves ◽  
Control Group ◽  
And Control ◽  
Radiofrequency Electromagnetic Radiation

Background: The present study determined whether 4 weeks of moderate aerobic exercise improves antioxidant capacity on the brain of rats against oxidative stress caused by radiofrequency electromagnetic radiation emitted from cell phones. Methods: Responses of malondialdehyde, catalase, glutathione peroxidase, and superoxide dismutase, as well as the number of hippocampal dead cells, were examined. Male Wistar rats (10–12 wk old) were randomly assigned to 1 of 4 groups (N = 8): (1) moderate aerobic exercise (EXE) (2 × 15–30 min at 1215 m/min speed with 5 min of active recovery between sets), (2) exposure to 900/1800 MHz radiofrequency electromagnetic waves 3 hours per day (RAD), (3) EXE + RAD, and (4) exposure to an experimental phone without battery. Results: Following the exposure, the number of the hippocampal dead cells was significantly higher in group RAD compared with groups EXE, EXE + RAD, and control group. Malondialdehyde concentration in group RAD was significantly higher than that of groups EXE, EXE + RAD, and control group. Also, the activity of catalase, glutathione peroxidase, and superoxide dismutase in groups EXE, EXE + RAD, and control group was significantly higher compared with those of the exposure group. Conclusion: This study demonstrated that moderate aerobic exercise enhances hippocampal antioxidant capacity against oxidative challenge in the form of radiofrequency electromagnetic waves.

4. Windows in the sky

2016 ◽  
pp. 39-46
Author(s):  
Geoff Cottrell
Keyword(s):  
Solar Radiation ◽  
Electromagnetic Radiation ◽  
Electromagnetic Waves ◽  
Outer Space ◽  
Cosmic Ray ◽  
High Energy ◽  
Electromagnetic Spectrum ◽  
Radio Waves ◽  
Transverse Waves ◽  
The Universe

The atmosphere influences much of what can be seen through a telescope. Most of the atmosphere lies within 16 km from the Earth’s surface. Further out, the air becomes thinner until it merges with outer space. In the ionosphere—a layer 75–1000 km high—neutral atoms are ionized by solar radiation and high-energy cosmic ray particles arriving from distant parts of the Universe. ‘Windows in the sky’ explains electromagnetic radiation and the electromagnetic spectrum from gamma rays through to visible light and radio waves. Electromagnetic waves are transverse waves that can be polarized. The atmosphere acts as a filter and blocks cosmic electromagnetic radiation. Atmospheric turbulence distorts starlight resulting in ‘twinkling’ stars.

scholarly journals Design of Solar Power Management Circuit Based on Wireless Sensor Network

2017 ◽  
Vol 13 (12) ◽  
pp. 67
Author(s):  
Jianying Shi ◽  
Yanbin Xu
Keyword(s):  
Wireless Sensor Network ◽  
Sensor Network ◽  
Power Management ◽  
Control Algorithm ◽  
Solar Power ◽  
Discharge Power ◽  
Wireless Sensor ◽  
Battery Charge ◽  
Point Tracking ◽  
Solar Battery

<p class="0abstract">To explore the design of solar power management circuit, the fuzzy logic control algorithm based on MPPT (max power point tracking), which has fast control speed and good environment robustness, is adopted as the control algorithm. In addition, the MPPT solar battery charge and discharge power management circuit is designed and successfully applied in the on-line measurement projects of dielectric loss of wireless sensor network in Jilin Province LG Electronics Company. The results show that the charging efficiency of solar battery charge and discharge power management circuit can reach above 80%, and the current of static power management circuit is less than 1mA. In different light intensities, the dynamic power management is intelligently carried out. At last, it is concluded that the stability and reliability of circuit are quite high.</p>

scholarly journals MieLab: A Software Tool to Perform Calculations on the Scattering of Electromagnetic Waves by Multilayered Spheres

2011 ◽  
Vol 2011 ◽  
pp. 1-10 ◽  
Author(s):  
Ovidio Peña-Rodríguez ◽  
Pedro Pablo González Pérez ◽  
Umapada Pal
Keyword(s):  
Electromagnetic Radiation ◽  
Graphical User Interface ◽  
Electromagnetic Waves ◽  
Software Tool ◽  
Virtual Laboratory ◽  
Small Particles ◽  
The Third ◽  
Functional Behavior ◽  
Architectural Model ◽  
Friendly Graphical User Interface

In this paper, we present MieLab, a free computational package for simulating the scattering of electromagnetic radiation by multilayered spheres or an ensemble of particles with normal size distribution. It has been designed as a virtual laboratory, including a friendly graphical user interface (GUI), an optimization algorithm (to fit the simulations to experimental results) and scripting capabilities. The paper is structured in five different sections: the introduction is a perspective on the importance of the software for the study of scattering of light scattering. In the second section, various approaches used for modeling the scattering of electromagnetic radiation by small particles are discussed. The third and fourth sections are devoted to provide an overview of MieLab and to describe the main features of its architectural model and functional behavior, respectively. Finally, several examples are provided to illustrate the main characteristics of the software.

scholarly journals Evaluation of Selected Metasurfaces’ Sensitivity to Planar Geometry Distortions

2019 ◽  
Vol 10 (1) ◽  
pp. 261
Author(s):  
Przemyslaw Lopato ◽  
Michal Herbko
Keyword(s):  
Numerical Models ◽  
Plane Deformation ◽  
Planar Geometry ◽  
Geometrical Parameters ◽  
Optical Frequency ◽  
Passive Devices ◽  
Planar Structures ◽  
Artificial Materials ◽  
Potential Applications ◽  
The Impact

In the last decade, the application of metamaterials has become a very interesting way of implementing passive devices in microwave, terahertz, and optical frequency ranges. Up until now, selective filters, absorbers, polarizers, and lenses have been designed and constructed using these artificial materials, simultaneously showing the possibility for many other potential applications. Because of the simplified fabrication process, in particular, planar structures called metasurfaces (MS), are developing very fast. In the literature, there are many studies on the properties of various metasurfaces, but there are a lack of papers related to the analysis of the impact of structure deformations on their properties. In this paper, three commonly utilized structures of metasurfaces were designed for the same resonant frequency and on the same substrate. The numerical models were built and verified using the measurements of fabricated structures. During the experiment, the geometrical parameters of the metasurface cells were swept and a mechanical in-plane deformation in orthogonal directions was applied to the examined structures. Finally, sensitivity to the geometry distortions of the analyzed structures was evaluated and discussed.

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