scholarly journals Preparation and electromagnetic properties characterization of reduced graphene oxide/strontium hexaferrite nanocomposites

2020 ◽  
Vol 9 (1) ◽  
pp. 105-114 ◽  
Author(s):  
Shumin Du ◽  
Huaiyin Chen ◽  
Ruoyu Hong
Keyword(s):  
Electromagnetic Wave ◽  
Environmental Pollution ◽  
Electromagnetic Interference ◽  
Electromagnetic Waves ◽  
Rapid Development ◽  
Living Environment ◽  
World Health ◽  
Electromagnetic Properties ◽  
Strontium Hexaferrite ◽  
Wave Radiation

AbstractWith the rapid development of electronics and information technology, electronics and electrical equipment have been widely used in our daily lives. The living environment is full of electromagnetic waves of various frequencies and energy. Electromagnetic wave radiation has evolved into a new type of environmental pollution that has been listed by the WHO (World Health Organization) as the fourth largest source of environmental pollution after water, atmosphere, and noise. Studies have shown that when electromagnetic wave radiation is too much, it can cause neurological disorders. And electromagnetic interference will cause the abnormal operation of medical equipment, precision instruments and other equipment, and therefore cause incalculable consequences. Therefore, electromagnetic protection has become a hot issue of concern to the social and scientific circles.

Graphene nanohybrids: excellent electromagnetic properties for the absorbing and shielding of electromagnetic waves

2018 ◽  
Vol 6 (17) ◽  
pp. 4586-4602 ◽  
Author(s):  
Maosheng Cao ◽  
Chen Han ◽  
Xixi Wang ◽  
Min Zhang ◽  
Yanlan Zhang ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Charge Transport ◽  
Microwave Absorption ◽  
Electromagnetic Interference ◽  
Electromagnetic Waves ◽  
Electromagnetic Properties ◽  
Response Mechanism ◽  
Microwave Response ◽  
Electromagnetic Interference Shielding

The microwave absorption, electromagnetic interference shielding, and microwave response mechanism of graphene hybrids are highlighted, including relaxation, charge transport, magnetic resonance,etc.

scholarly journals Spatial transformation-enabled electromagnetic devices: from radio frequencies to optical wavelengths

2015 ◽  
Vol 373 (2049) ◽  
pp. 20140363 ◽  
Author(s):  
Zhi Hao Jiang ◽  
Jeremy P. Turpin ◽  
Kennith Morgan ◽  
Bingqian Lu ◽  
Douglas H. Werner
Keyword(s):  
Electromagnetic Waves ◽  
Transformation Optics ◽  
Electromagnetic Properties ◽  
Wave Radiation ◽  
Experimental Investigations ◽  
Electromagnetic Spectrum ◽  
Coordinate Transformations ◽  
Electromagnetic Devices ◽  
Optical Wavelengths ◽  
Radio Frequencies

Transformation optics provides scientists and engineers with a new powerful design paradigm to manipulate the flow of electromagnetic waves in a user-defined manner and with unprecedented flexibility, by controlling the spatial distribution of the electromagnetic properties of a medium. Using this approach, over the past decade, various previously undiscovered physical wave phenomena have been revealed and novel electromagnetic devices have been demonstrated throughout the electromagnetic spectrum. In this paper, we present versatile theoretical and experimental investigations on designing transformation optics-enabled devices for shaping electromagnetic wave radiation and guidance, at both radio frequencies and optical wavelengths. Different from conventional coordinate transformations, more advanced and versatile coordinate transformations are exploited here to benefit diverse applications, thereby providing expanded design flexibility, enhanced device performance, as well as reduced implementation complexity. These design examples demonstrate the comprehensive capability of transformation optics in controlling electromagnetic waves, while the associated novel devices will open up new paths towards future integrated electromagnetic component synthesis and design, from microwave to optical spectral regimes.

scholarly journals Facile Preparation and Highly Efficient Catalytic Performances of Pd-Cu Bimetallic Catalyst Synthesized via Seed-Mediated Method

Nanomaterials ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 6 ◽  
Author(s):  
Fangke Zhan ◽  
Juanjuan Yin ◽  
Jingxin Zhou ◽  
Tifeng Jiao ◽  
Lexin Zhang ◽  
...  
Keyword(s):  
Environmental Pollution ◽  
Bimetallic Catalyst ◽  
Low Cost ◽  
Rapid Development ◽  
High Energy ◽  
Living Environment ◽  
Preparation Methods ◽  
Highly Efficient ◽  
Bimetallic Composite ◽  
Seed Mediated

With the rapid development of industry, the problem of environmental pollution has become increasingly prominent. Exploring and preparing green, efficient, and low cost catalysts has become the key challenge for scientists. However, some conventional preparation methods are limited by conditions, such as cumbersome operation, high energy consumption, and high pollution. Here, a simple and efficient seed-mediated method was designed and proposed to synthesize a highly efficient bimetallic catalyst for catalyzing nitro compounds. A Pd-Cu bimetallic composite (BCM) can be prepared by synthesizing the original seed crystal of precious metal palladium, then growing the mature nanocrystalline palladium and supporting the transition metal copper. Importantly, after eight consecutive catalytic cycles, the conversion of the catalyzed 2-NA was 84%, while the conversion of the catalyzed 4-NP was still 72%. And the catalytic first order rates of 2-NA and 4-NP constants were 0.015 s−1, and 0.069 s−1, respectively. Therefore, current research of nanocomposites catalyst showed great significance for serious environmental pollution problems and the protection of living environment, providing a new idea for the preparation of new bimetallic catalytic materials.

Electromagnetic Properties of Bearing Cement-Based Materials

2011 ◽  
Vol 261-263 ◽  
pp. 663-668
Author(s):  
Ai Li Guo ◽  
Ri Gao ◽  
Heng Jing Ba
Keyword(s):  
Electromagnetic Wave ◽  
Electromagnetic Waves ◽  
Building Materials ◽  
Incident Angle ◽  
High Strength ◽  
Wave Incident ◽  
Electromagnetic Properties ◽  
Frequency Range ◽  
Electromagnetic Wave Incident ◽  
Cement Based Materials

For studying absorption/bearing integration of building materials, high-strength cement-based materials were prepared by using active fly ash, silica fume and quartz, etc. Electromagnetic parameters of the cement-based materials were measured through coaxial method, and then by means of these parameters, the reflectivity of electromagnetic waves of the cement-based materials were simulated under variable electromagnetic wave incident angle (θ), frequency (f) and thickness of the material(d).The reflectivity of electromagnetic waves with 8~18GHz frequency range vertically transmitting into the cement-based materials was obtained through far field radar scattered cross-section measurement, and was compared with simulated reflectance under the same incident conditions. The results show that the high-strength cement-based materials with imaginary part of dielectric constant can consume energy of the incident electromagnetic wave. Incident angle less than 15° has little effect on the reflectivity of the cement-based materials in 2~18GHz frequency range. While the thickness of the cement-based materials is 15mm or 25mm, simulation results of the reflectivity are in good agreement with measured ones. Measured absorption peak and -10dB bandwidth increase with the increasing of thickness of the cement-based materials with compressive strength of 120.7MPa. This suggests that the cement-based materials studied in this paper have the characteristics of absorption/bearing integration.

scholarly journals Electromagnetic-wave radiation due to diastrophism of magma dike growth in Izu-Miyake volcanic eruptions in Japan in 2000

2001 ◽  
Vol 1 (1/2) ◽  
pp. 43-51 ◽  
Author(s):  
M. Hata ◽  
I. Takumi ◽  
H. Yasukawa
Keyword(s):  
Electromagnetic Wave ◽  
Magnetic Flux ◽  
Volcanic Activity ◽  
Electromagnetic Waves ◽  
Volcanic Eruptions ◽  
Wave Radiation ◽  
Gps Data ◽  
Radiation Mechanisms ◽  
The Earth ◽  
Gps Observation

Abstract. A large 10 cm per day diastrophism of the crust was experienced between Kozu and Niijima Islands during the Izu-Miyake volcanic eruptions in Japan on 3–4 August 2000. The diastrophism was detected through GPS observation. The seismometer also complied a swarm of earth-quakes at this time. Our electromagnetic wave data, observed at 223 Hz at the Omaezaki site, about 110 km and 150 km northwest of the Kozu and Miyake Islands, respectively, detected a clear, anomalous magnetic flux radiation that corresponded well with the seismographic and GPS data. Similar radiation was received for about one week preceding the big volcanic eruption that occurred on 18 August 2000. These observations indicate that the electromagnetic wave monitoring system has the potential to monitor and/or warn of volcanic activity, and the facts disclose one of the mysterious radiation mechanisms of electromagnetic waves emitted from the Earth.

scholarly journals ANALYSES OF RADIATION OF ELECTROMAGNETIC WAVES IN THE HIGH-VOLTAGE AIR DUCT (150 kV) CONSTRUCTION ON HEALTH

2017 ◽  
Vol 3 (4) ◽  
pp. 152-159
Author(s):  
Erwin Azizi Jayadipraja
Keyword(s):  
Magnetic Field ◽  
Electromagnetic Wave ◽  
Field Strength ◽  
Electric Field ◽  
Magnetic Field Strength ◽  
High Voltage ◽  
Electromagnetic Waves ◽  
Wave Radiation ◽  
Strength Analysis ◽  
The Government

Background: High-voltage air ducts is the government program to supply electricity needs. However, in practice, obstacles have been identified in the form of rejection from the community due to the outstanding issues that high-voltage air ducts have an impact on health.Aim: This research aims to analysis the magnitude of electromagnetic wave radiation of high-voltage air ducts construction on health.Methods: The study was conducted by measuring electromagnetic wave radiation prior to high-voltage air ducts (150 kV) construction and predicting the amount of radiation generated after this operation and its impact on health.Result: The field measurement result showed that the highest strength of magnetic field in the absence of construction and operation activity of high-voltage air ducts 150 kV was 0.00085 mT and the highest electric field was 0.004241251 V/m. The results of the magnetic field strength analysis showed that the highest strength of magnetic field and electric field when the high-voltage air ducts is completed and operated was magnetic field of 0.00415 mT and electric field of 38.4 V/m. The value was far lower than the standard limits recommended by IRPA / INIRC, WHO1990 and SNI 04-6950-2003. The allowed electric field strength is 5 kV / m and the allowed magnetic field strength is 0.1 mT.Conclusion: Electromagnetic wave radiation of High-Voltage Air Ducts is not exceeded the allowed limit, so it will not cause a direct risk to health.

scholarly journals GAMBARAN INDUKSI ELEKTROMAGNETIK BEBERAPA JENIS HANDPHONE YANG DIGUNAKAN MAHASISWA KEDOKTERAN ANGKATAN 2013

2014 ◽  
Vol 2 (1) ◽  
Author(s):  
Rich V. Wowor
Keyword(s):  
Magnetic Field ◽  
Electromagnetic Wave ◽  
Radiation Field ◽  
Electromagnetic Waves ◽  
Wave Radiation ◽  
Cross Sectional ◽  
Significant Difference ◽  
The Difference ◽  
Harmful Radiation ◽  
Post Hoc

Abstract: Mobile phone is a source of potentially harmful radiation. The form of signals in two radiation field, the near magnetic field and the remote magnetic field. This research is quantitative, with a cross-sectional approach. The results of the study, the highest standby electromagnetic waves is BlackBerry smartphone, while lowest  one is the Samsung. At the calling modes, highest is Blackberry and Nokia and the  lowest one is Samsung. At the receiving modes the biggest wave is Blackberry, lowest is Samsung. Based on the results of the ANOVA test it was found that there is a significant difference (p = 0.003, p <0.05) in the fourth electromagnetic waves smartphone brands when making a call. While in standby and receive calls no significant difference (p = 0.120 and p = 0.115, p> 0.05). Therefore, no difference statistically and required further analysis (post-hoc) to test the Least Significant Difference (LSD) or the Least Significance difference (LSD). There is a significant difference between the top of the electromagnetic wave smartphone brands Samsung, Nokia, and Blackberry at the time of call. While all four brands of smartphones is apparently the difference electromagnetic waves of the Samsung and Nokia with significant difference (p = 0.001), followed by the differences between the Samsung and Blackberry (p = 0.002). It can also take a look at the difference in the mean difference of the four brands of electromagnetic waves where the average difference between Nokia and Samsung is the smallest (-4.035), followed by the difference between the Samsung with Blackberry (-4.001). Keywords: handphone, electromagnetic wave, radiation field.   Abstrak: Handphone merupakan sumber radiasi potensial yang membahayakan. Signal telepon seluler yang dikirim membentuk dua buah lapangan radiasi yakni, medan magnet dekat dan medan magnet jauh. Penelitian ini bersifat kuantitatif, dengan pendekatan cross sectional. Hasil penelitian, smartphone saat standby tertinggi Blackberry, terendah Samsung. Saat panggilan tertinggi Blackberry dan Nokia, terendah Samsung. Saat menerima panggilan, terbesar adalah Blackberry, terendah Samsung. Berdasarkan hasil uji ANOVA terdapat perbedaan bermakna (p = 0,003; p<0,05) induksi elektromagnetik pada keempat merk smartphone saat melakukan panggilan. Sedangkan pada saat standby dan menerima panggilan tidak terdapat perbedaan yang bermakna (p = 0,120 dan p = 0,115; p > 0,05).  Oleh karena tidak terdapat perbedaan secara statistik maka diperlukan analisis lanjutan (post-hoc) dengan melakukan uji Beda Nyata Terkecil (BNT) atau Least Significance Diferrence (LSD). Terdapat perbedaan yang bermakna atas induksi elektromagnetik smartphone antara merk Samsung, Nokia, dan Blackberry pada saat melakukan panggilan. Sedangkan dari keempat merk smartphone tersebut ternyata perbedaan induksi elektromagnetik antara merk Samsung dan Nokia memiliki perbedaan yang paling signifikan (p = 0,001) kemudian diikuti oleh perbedaan antara merk Samsung dengan Blackberry (p = 0,002). Hal ini dapat juga kita lihat pada selisih perbedaan rerata dari keempat merk tersebut dimana selisih rerata induksi elektromagnetik antara merk Samsung dengan Nokia merupakan yang terkecil (-4,035) kemudian diikuti oleh selisih antara merk Samsung dengan Blackberry (-4,001). Kata kunci: Handphone, induksi elektromagnetik, lapangan radiasi.

Electromagnetic Radiation on Human Health Hazards and Protective Measures in Modern Society

2012 ◽  
Vol 518-523 ◽  
pp. 1022-1026 ◽  
Author(s):  
Jiang Yong Xing
Keyword(s):  
Electromagnetic Wave ◽  
Environmental Pollution ◽  
Electromagnetic Radiation ◽  
Human Health ◽  
Electromagnetic Waves ◽  
Modern Society ◽  
Radiation Hazards ◽  
Protective Measures ◽  
Material Life ◽  
Rich Material

The discovery of electromagnetic waves and applications change the way people live in modern society, from the telephone, radio, TV to your computer, mobile phone, the electromagnetic wave for people to create a rich material life and spiritual life. Electromagnetic wave on the increasingly serious environmental pollution, electromagnetic radiation hazards on human health can not be ignored. Humans not only to continue to develop the application of electromagnetic waves, but recognize the dangers of electromagnetic radiation, to strengthen the protection, so that the electromagnetic waves more effectively for the benefit of mankind.

Detection of delamination in composites by using electromagnetic penetrating radar

2014 ◽  
Vol 5 (2) ◽  
pp. 151-156
Author(s):  
Z. Mechbal ◽  
A. Khamlichi
Keyword(s):  
Electromagnetic Wave ◽  
Electromagnetic Waves ◽  
Electromagnetic Wave Propagation ◽  
Wave Reflection ◽  
Image Features ◽  
Partial Reflection ◽  
Straight Path ◽  
Reflected Signal ◽  
Short Time ◽  
Intervening Factors

Composites made from E-glass/epoxy or aramid/epoxy are frequently used in aircraft and aerospace industries. These materials are prone to suffer from the presence of delamination, which can reduce severely the performance of aircrafts and even threaten their safety. Since electric conductivity of these composites is rather small, they can propagate electromagnetic waves. Detection of delamination damage can then be monitored by using an electromagnetic penetrating radar scanner, which consists of emitting waves having the form of short time pulses that are centered on a given work frequency. While propagating, these waves undergo partial reflection when running into an obstacle or a material discontinuity. Habitually, the radar is moved at constant speed along a straight path and the reflected signal is processed as a radargram that gives the reflected energy as function of the two-way time and the antenna position.In this work, modeling of electromagnetic wave propagation in composites made from E-glass/epoxy was performed analytically. The electromagnetic wave reflection from a delamination defect was analyzed as function of key intervening factors which include the defect extent and depth, as well as the work frequency. Various simulations were performed and the obtained results have enabled to correlate the reflection pattern image features to the actual delamination defect characteristics which can provide quantification of delamination.

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