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Copyright of Natural Gas Industry is the property of Natural Gas Industry Journal Agency and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Metasurfaces are two-dimensional artificial structures with numerous subwavelength elements arranged periodically or aperiodically. They have demonstrated their exceptional capabilities in electromagnetic wave polarization manipulation, opening new avenues for manipulating electromagnetic waves. Metasurfaces exhibiting electrically controlled reconfigurable polarization manipulation have garnered widespread research interest. These unique metasurfaces can dynamically adjust the polarization state of electromagnetic waves through real-time modification of their structure or material properties via electrical signals. This article provides a comprehensive overview of the development of metasurfaces exhibiting electrically controlled reconfigurable polarization manipulation and explores the technological advancements of metasurfaces with different transmission characteristics in the microwave region in detail. Furthermore, it delves into and anticipates the future development of this technology.

【Objective】 Soil dielectric constant measures the ability of a soil to transmit electric fields. It is the ratio of the capacitance of a soil sample to the capacitance of air-filled space of the same volume. In this paper, we systematically analyze the factors that influence the dielectric constant, offering an updated perspective on soil dielectric constant modeling. 【Method】 This study systematically identifies the primary factors influencing soil dielectric constant based on soil dielectric theory. Additionally, it categorizes and summarizes existing soil dielectric constant models, facilitating a comparative analysis of their strengths, weaknesses, applications, and future development. 【Result】 The primary influencing factors governing the dielectric constant varied with soil types, with notable dependence on testing frequency. However, the dielectric constant remains a valuable indicator of soil water content. The soil dielectric constant models were broadly categorized into four types: theoretical, semi-empirical, empirical, and boundary models. 【Conclusion】 Presently, there is a dearth of research focusing on the dielectric properties and model development specific to regional soils. Enhancing model accuracy necessitates incorporating the influence of soil-phase composition, mineral composition, and microstructure on the dielectric constant. This refinement will broaden the application studies for assessing and analyzing soil physical and chemical properties based on dielectric constant testing.

Objective To investigate the effect of electromagnetic wave power density on the expression of glial fibrillary acidic protein ( GFAP) in the hippocampus of SD rats under 1 800 MHz electromagnetic wave irradiation, and whether it exhibits a “window effect”. Methods Ninety-eight 4-week-old SPF-grade SD rats were randomly divided into 14 groups, with 7 rats in each group. Seven groups were exposed groups (frequency：1 800MHz, power densities: 0.1 mW/cm², 0.3 mW/cm², 0.5 mW/cm², 0.7 mW/cm², 0.9 mW/cm², 1.0 mW/cm², 1.2 mW/cm²) and corresponding 7 groups were control groups (power density: 0 mW/cm²) . Exposure was conducted for 12 hours daily for 3 weeks. After exposure, Western Blot was used to detect the expression level of GFAP in the hippocampal tissue, and immunohistochemistry staining was performed to determine the average optical density (MOD) value of GFAP-positive expression products in the DG, CA3, and CA1 regions of the hippocampal tissue, to determine the power density window of GFAP expression in the hippocampus of SD rats under 1 800 MHz exposure. Results At power densities of 0.1 mW/cm² and 0.3 mW/cm², Western Blot results showed increased expression of GFAP in the rat hippocampus (P < 0.05), and immunohistochemistry staining demonstrated increased MOD values of GFAP in the three regions (P< 0.05). Conclusion Long-term exposure to 1 800 MHz electromagnetic radiation has a “window effect” on the expression of GFAP in the DG, CA3, and CA1 regions of the hippocampus in SD rats, with power density windows of 0.1 mW/cm² and 0.3 mW/cm². [ABSTRACT FROM AUTHOR]

Copyright of Journal of Irrigation & Drainage is the property of Journal of Irrigation & Drainage Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Computer Measurement & Control is the property of Magazine Agency of Computer Measurement & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

As a device for missile-borne system to transmit and receive electromagnetic waves, the functions of missile-borne antenna are becoming more and more abundant. The shared-aperture antenna can improve the aperture utilization rate of missile seeker and can avoid radiation interference between antennas. This paper proposes a low profile circularly polarized shared-aperture antenna for missile seeker antenna based on the theory of microstrip circular polari-zed antenna. More specifically, the sequential rotation feed technology is adopted for the rectangular microstrip antenna in the high-frequency C-band part, while the orthogonal double feed technology is adopted for the cross microstrip antenna in the low-frequency S-band part. The nested shared-aperture antenna structure is adopted to realize the design of shared aperture antenna of 63 mm×63 mm×1.574 mm. The reflection coefficient is less than -10 dB in the frequency bands of 4.87~5.13 GHz and 2.49~2.51 GHz. The relative bandwidth of high-frequency antenna is 8.1% and that of low-frequency antenna is 0.4%. The axial ratio of the two antennas in the maximum radiation direction at the center frequency is less than 3 dB. The experimental data show that the shared-aperture antenna designed and applied to the missile-borne antennacan significantly improve the aperture utilization of the missile seeker, and can also eliminate the deterioration of the radiation performances caused by the mutual coupling of antennas.

To study the frequency response characteristics of knitted fabric-based frequency selective surface (FSS), high-pass knitted fabric-based FSS were designed and prepared. The electromagnetic transmission characteristics were tested in a microwave anechoic chamber. The results show that weft-knitted fabric based FSS has high-pass and low-resistance electromagnetic properties. When the placement direction of the knitted fabrics and the polarization mode of electromagnetic wave are different, the frequency response characteristics are distinct. When the ratio of conductive yarns increases, the electromagnetic wave shield ability and breathability of knitted fabric based FSS are enhanced. The shielding ability of the fabric increases with the density, but the permeability of the fabric decreases. As the incident angle of electromagnetic wave increases, the electromagnetic wave component entering the fabric decreases, and the electromagnetic wave passing through the fabric decreases. Therefore, under the premise of wear comfort, the frequency response characteristics of knitted fabrics can be controlled and selective transmission of electromagnetic wave can be achieved by designing the structure and weaving parameters of knitted fabrics and adjusting the polarization mode and incidence angle of electromagnetic wave.

Copyright of Aero Weaponry is the property of Aero Weaponry Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to solve the problems of the complex modeling process, high computational complexity, and low prediction accuracy of the existing field strength prediction models, a mine roadway field strength prediction model based on improved convolutional neural network(CNN) is proposed. By analyzing the influence factors of electromagnetic wave transmission in large-scale fading channels in mines, using antenna operating frequency, roadway cross-sectional dimensions, roadway wall roughness, roadway wall inclination, roadway wall relative permittivity and transceiver distance as model inputs, using the electromagnetic wave propagation path loss as model outputs, the model is able to predict the changes of the roadway field strength. The improved CNN adds batch normalization layer after each convolutional layer to replace the original pooling layer so as to avoid the loss of data characteristics due to down-sampling of the pooling layer, to keep the output of each convolutional layer similarly distributed, to improve the network generalization capacity and to speed up the network convergence. The simulation results show that compared with the field strength prediction models based on CNN, BP neural network and support vector machine, the model has high consistency between the predicted value and the actual value, has stronger robustness, and improves the accuracy of mine roadway field strength prediction effectively.

Copyright of China Forest Products Industry is the property of China Forest Products Industry Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Railway Signalling & Communication Engineering is the property of Railway Signalling & Communication Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Mine Automation is the property of Industry & Mine Automation Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Beijing University of Technology is the property of Journal of Beijing University of Technology, Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Calcium cobaltate thin films were prepared by coating and sintering on alumina ceramic substrate with calcium cobaltate powder prepared by sol-gel method. The phase structure, temperature resistance characteristics and wave-absorbing properties of the thin films were studied. It is found that the calcium cobaltate powders prepared by sol-gel method are composed of Ca9Co12O28 phase, and the powder particles are uniform, with a certain orientation growth and obvious lamellar structure. The sintered calcium cobaltate film is composed of fine Ca3 Co4 O9 phase, which is closely bound to the alumina substrate. The thickness is about 20 µm. The square resistance of the films decreases rapidly with the increase of temperature, and keep around 20 Ω/□ at 300 °C to 800 °C. At 800 °C, the resistance-film type metamaterial absorber exhibits double absorption peaks at 8 GHz to 18 GHz. [ABSTRACT FROM AUTHOR]

Copyright of Guangdong Architecture Civil Engineering is the property of Guangdong Architecture Civil Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In view of complicated electromagnetic wave propagation environment in mine tunnel, a multipath channel model of electromagnetic wave propagation in mine tunnel was established by use of image method. In the paper, calculation methods of total propagation distance, incidence angle and reflecting angle of three-dimensional helix ray, and expressions of total receiving power and transmission loss were presented. The simulation results show that attenuation of electromagnetic wave field intensity is larger near transmitting antenna with fast fading phenomena, which verify the model can predict electromagnetic wave field intensity distribution in tunnel accurately.

Depending on the computer, network analyzer, three dimensional coordinate instrument and antenna, the authors developed an automatic electromagnetic data acquisition system in the laboratory. The system was designed by using graphical programming language called Lab VIEW. It could do data acquisition and real-time display, and overcame the tedious and time -consuming work that data were manually saved at each measurement point in the traditional experiment. This automatic electromagnetic data acquisition system plays a very important role in strengthening professional skills and training the creative ability of students. It can improve the training quality of students. [ABSTRACT FROM AUTHOR]

Copyright of Computer Measurement & Control is the property of Magazine Agency of Computer Measurement & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In view of problems that basic path loss model based on received signal strength indicator (RSSI) is established on visual range between sending node and receiving node and it is not conformed to transmission characteristics of mine electromagnetic wave, the paper proposed an improved transmission path loss model of mine electromagnetic wave. On basis of basic model only considers attenuation factor, the improved model adds coefficient of multipath parameter and employs the least square method to calculate the two parameters. The calculation and Matlab simulation results show that the value obtained by use of the improved model is closer to measured value and has less error, and received power and transmission attenuation decrease with increasing of node interval.

Copyright of Zhongguo Kejishi Zazhi (Chinese Journal for the History of Science & Technology) is the property of Chinese Academy of Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Antenna theory was used to analyze the energy coupling characteristics between electromagnetic wave and metal structures and the calculation model of the matched load's maximum power under resonance condition was established. The experiment device for measuring RF energy scraped spark's ignition threshold power was designed to measure the ignition threshold power. Tests show that the ignition threshold power is independent on the electromagnetic wave frequency and slightly reduces with the increase of the plate rate, always keeping above 0.168 W. Combining the calculation model of the matched load's maximum power, the relation graph of wave frequency and the threshold field is established to guide the utilization of RF devices in coal mines. [ABSTRACT FROM AUTHOR]

The effect of uniform plasma on the electromagnetic wave (EMW) transmittance on micro-strip line is investigated by simulations. The dependence of transmission coefficients of EMW on the plasma frequency (density), the electron-molecule collision frequency, the thickness and width of the plasma layer etc are obtained under large and small gaps on the line. The results show that before filled with plasma in the gap, EMW with higher frequency can pass the gap while that with lower frequency cut off. After filled with dense plasma layer of appropriate thickness and width, the gap allows the low-frequency EMW to transfer. The transmittance increases with the plasma frequency, but decreases with the collision frequency. On the other hand, the filled plasma causes an attenuation peak at high-frequency band with position being proportional to the plasma frequency but independent on the collision frequency. The discharge plasma is feasible to be used to control the EMW transmission on the micro-strip lines. [ABSTRACT FROM AUTHOR]

Processing technology of using electromagnetic wave equipment setting wool polyester blended yarn was discussed. Defects of traditional thermo-hydro setting were analyzed, the better setting processing was explored by the orthogonal test, and the blended yarn related property index before and after setting were tested. The result showed that the better setting processing was: fourth power, 4 min, controlling yarn regain about 9.1% . It was considered that after using the better electromagnetic wave setting processing, yarn breaking tenacity can increase about 15.1%, breaking elongation rate can increase about 1.9%, setting ratio can reach above 83%, the production demands can be reached. [ABSTRACT FROM AUTHOR]