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[IEEE 2018 USNC-URSI Radio Science Meeting (Joint with AP-S Symposium) - Boston, MA, USA (2018.7.8-2018.7.13)] 2018 USNC-URSI Radio Science Meeting (Joint with AP-S Symposium) - Sub-Diffraction Holographic Imaging with Resonant Scatterers in Proximity of the Objects
摘要： To overcome the well-known 'diffraction limit' in the resolution of electromagnetic imaging systems, we propose the use of resonant near-field scatterers incorporated in the holographic imaging techniques. These scatterers convert a portion of the evanescent spectrum in the proximity of the object to propagating spectrum which is measurable by the antenna in the far-field.
关键词： microwave and millimeter wave imaging,sub-diffraction imaging,resonant scatterers
更新于2025-09-23 15:22:29
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Accounting for Static and Dynamic Open Water in the Modeling of SMAP Brightness Temperatures Over Peatlands
摘要： Hydrological change in peatlands due to anthropogenic disturbance and global warming can release enormous amounts of greenhouse gas emissions. Passive microwave satellite observations are an opportunity to globally monitor these changes. Abundant static and dynamic open water surfaces in peatlands strongly affect observed brightness temperatures (Tb). Here, we account for these contributions in radiative transfer modeling using NASA's Goddard Earth Observing System Model version 5 (GEOS-5) static open water mask and, for the dynamic open water fraction, the simulated inundated area using a version of the GEOS-5 Catchment land surface model that has been modified for peatland areas (PEAT-CLSM). Modeled Tb is compared against two years of SMAP L-band Tb. Preliminary results indicate: (i) a bias reduction when including the static open water fraction in a simple RTM mixing model, and (ii) significantly improved correlation between modeled and observed Tb when using land surface output from PEAT-CLSM instead of the operational CLSM.
关键词： organic soil,radiative transfer model,soil moisture,L-band,passive microwave
更新于2025-09-23 15:22:29
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Bistatic SAR: Forecasting Spatial Resolution
摘要： This paper derives closed form expressions for bistatic synthetic aperture radar spatial resolution of a generalized system from the k-space or the wavenumber domain. These spatial resolution equations have not previously appeared in the literature. From these equations, significant resolution is found in both range and cross-range forecasting a forward-scatter bistatic synthetic aperture radar image when the elevation angles of each bistatic platform are significantly different. Simulation and lab tests demonstrated the forward scatter resolution.
关键词： image resolution,synthetic aperture radar,radar remote sensing,spatial resolution,radar imaging,bistatic radar,microwave imaging
更新于2025-09-23 15:22:29
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Microwave Hydrothermal Synthesis of In <sub/>2</sub> O <sub/>3</sub> -ZnO Nanocomposites and Their Enhanced Photoelectrochemical Properties
摘要： Indium oxide (In2O3) doped zinc oxide (ZnO) nanocomposites were successfully synthesized through a facile microwave hydrothermal method. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), N2 adsorption–desorption isotherms (BET) and UV-Vis diffuse reflectance spectroscopy. The morphology of In2O3-ZnO composites was observed to be like flowers, and the diameter of particles constituting the porous petal was about 30 nm. The photoelectrocatalytic test results showed that the photoelectrocatalytic methylene blue (MB) degradation efficiency using In2O3-ZnO nanocomposites as photocatalysts under visible light irradiation and a certain voltage could reached above 95.3% after 60 min, much higher than that of In2O3 particles and ZnO particles. The enhanced photoelectrocatalytic activity was attributed to the doping of In2O3 and applied voltage, which beneficially reduced the recombination of electrons and holes in the photoelectrocatalytic process, therefore, it promoted the production of active species (?OH and ?O2-).
关键词： photoelectrochemical properties,visible light irradiation,methylene blue degradation,In2O3-ZnO nanocomposites,microwave hydrothermal synthesis
更新于2025-09-23 15:22:29
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Microwave photonics‐based all optical wavelength conversion of Nyquist‐DP‐16QAM for flex‐grid optical networks with 112 Gbps
摘要： We propose and demonstrate an all optical wavelength conversion of Nyquist differential phase 16 quadrature amplitude modulation based on microwave photonics signal processing for flex-grid optical networks. By analyzing the mechanism of the microwave photonics and the components, multi-adjusting the parameters of wavelength tunable laser with smooth and adjustable optical intensity can be obtained. Then, the multi-channel photonic signals with the minimal guard space of 5 GHz can be obtained, which provide more than 20 flex-grids for optical transmission with transparent rate and format. The optical power of converted wavelengths, optical signal-to-noise ratio, error vector magnitude, and bit error rate (BER) are studied under the condition of different flex-grids, the frequencies of which are from 15 GHz to 36 GHz. The channel frequency spacing and amplitude of the converted wavelength can be dynamically adjusted via parameter configuration. Flex-grid spacing strategies and channel selecting strategies are given. The BER performance of all converted channels can fall below the forward error correction threshold of 3.8 × 10?3 by optimizing the optical power of the receiver end. The results show the tradeoff between the BER and the detected optical power of the receiver end. These research findings could provide solutions for spectrum allocation and routing selection when wavelength conversion is needed in optical links.
关键词： coherent communication,microwave photonics,wavelength conversion,flex-grid optical networks
更新于2025-09-23 15:22:29
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Photocatalytic Degradation of Reactive Brilliant Red X-3B Based on Microwave Electrodeless Lamp and Long Lifetime Immobilized TiO<sub/>2</sub>
摘要： A novel photocatalytic system (MEL/TiO2/QS) based on microwave electrodeless lamp (MEL) and TiO2 films supported on quartz sheets (TiO2/QS) was established for high photocatalytic efficiency and long catalyst life. The results showed that the degradation efficiency for reactive brilliant red X-3B in MEL/TiO2/QS was equally as that in a suspended TiO2 system. Furthermore, under the microwave irradiation, the TiO2/QS had high catalytic activity after successively used 10 times without additional separation and regeneration. The pseudo-first-order kinetics was employed to describe decomposition of the dye and reaction rates at different initial dye concentrations, followed by the Langmuir–Hinshelwood kinetic model. The mineralization process and final products were also analyzed by total organic carbon (TOC) and ion chromatography (IC). The research might be useful in the commercial scale application of low cost and high efficiency photocatalytic process.
关键词： reactive brilliant red X-3B,Catalyst regeneration,microwave electrodeless lamp,TiO2 films
更新于2025-09-23 15:22:29
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[IEEE 2017 14th IEEE India Council International Conference (INDICON) - Roorkee (2017.12.15-2017.12.17)] 2017 14th IEEE India Council International Conference (INDICON) - Design and study of Cylindrical RF pill box window for 100 GHz BWO with Single side Tapered Output Coupler
摘要： The paper represents the design and implementation of a Silicon Pillar Bow Windmill used in LED output coupler at a frequency of 100 GHz with cylindrical waveguides. The design and simulation have been carried out using CST microwave studio. The designed windmill has a circular aluminum disc with a thickness of 3.19 μm and radius of 2500 μm. The circular disc is sandwiched between two circular waveguides. The designed windmill has been simulated and the return loss and insertion loss are obtained as -22.38 dB and -0.000723 dB respectively at this frequency. The designed windmill has good performance and can be used for low and medium power microwave applications.
关键词： Silicon Pillar Bow Windmill,LED output coupler,insertion loss,CST microwave studio,return loss,cylindrical waveguides
更新于2025-09-23 15:22:29
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Ultra-Rapid Crystallization of L-Alanine Using Monomode Microwaves, Indium Tin Oxide and Metal-Assisted and Microwave-Accelerated Evaporative Crystallization
摘要： The use of indium tin oxide (ITO) and focused monomode microwave heating for the ultra-rapid crystallization of L-alanine (a model amino acid) is reported. Commercially available ITO dots (< 5 mm) attached to blank poly(methyl)methacrylate (PMMA, 5 cm in diameter with 21-well silicon isolators: referred to as the iCrystal plates) were found to withstand prolonged microwave heating during crystallization experiments. Crystallization of L-alanine was performed at room temperature (a control experiment), with the use of two microwave sources: a 2.45 GHz conventional microwave (900 W, power level 1, a control experiment) and 8 GHz (20 W) solid state, monomode microwave source with an applicator tip that focuses the microwave field to a 5-mm cavity. Initial appearance of L-alanine crystals and on iCrystal plates with ITO dots took 47 ± 2.9 min, 12 ± 7.6 min and 1.5 ± 0.5 min at room temperature, using a conventional microwave and focused monomode microwave heating, respectively. Complete evaporation of the solvent using the focused microwaves was achieved in 3.2 ± 0.5 min, which is ~52-fold and ~172-fold faster than that observed at room temperature and using conventional microwave heating, respectively. The size and number of L-alanine crystals was dependent on the type of the 21-well iCrystal plates and the microwave heating method: 33 crystals of 585 ± 137 μm in size at room temperature > 37 crystals of 542 ± 100 μm in size with conventional microwave heating > 331 crystals of 311 ± 190 μm in size with focused monomode microwave. FTIR, optical microscopy and powder X-ray diffraction analysis showed that the chemical composition and crystallinity of the L-alanine crystals did not change when exposed to microwave heating and ITO surfaces. In addition, theoretical simulations for the binding of L-alanine molecules to ITO and other metals showed the predicted nature of hydrogen bonds formed between L-alanine and these surfaces.
关键词： ITO,Microwave heating,Silver island films,Evaporative crystallization
更新于2025-09-23 15:22:29
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Exfoliation of graphite as flexible SERS substrate with high dye adsorption capacity for Rhodamine 6G
摘要： Adsorption is one of the most important processes in wastewater treatment, especially for dye removal. In addition to adsorption, there must be a vigilant technique, such as Surface Enhanced Raman spectroscopy (SERS), for detection of low concentration of dye molecules to detect water foiling. Herein, we report a simple, low cost, rapid and e?cient technique for the production of exfoliated graphite (EG) under microwave irradiation at 800 W in 1 min, as excellent adsorption material for Rhodamine 6G (R6G) dye. The e?ect of adsorption process parameters such as pH, contact time, isotherm models (Langmuir and Freundlich) and kinetic models (pseudo-?rst and pseudo-second-order) on dye removal under aqueous solutions, were investigated. The maximum adsorption capacity for R6G dye is 212.72 ( ± 5.3) mg/g. Meanwhile compressing of EG, into a ?exible graphite sheet (FGS) demonstrates responsive SERS for R6G molecules up to detection limit of 10?7 mol/L. However, with silver nanoparticle incorporation, the detection limit increases up to 10?12 mol/L. Performance of ?exible sheet checked over a month by rubbing sheet through paper and cloth doesn’t have any impact on the synthesis of exfoliated graphite. Aging factor of the sheet also shows reproducible SERS spectra after a month. These are the highest reported values till today, for adsorption of R6G dye on Exfoliated graphite, with reasonable SERS detection.
关键词： Microwave irradiation,Flexible graphite sheet,Exfoliated graphite,SERS,Adsorption
更新于2025-09-23 15:22:29
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Microwave transmission performance of fused silica ceramics in microwave high-temperature heating
摘要： Compared with traditional heating methods, microwave heating is widely used in many industrial heating fields because of its advantages, such as material-selective heating, volumetric heating and high-efficiency heating. However, previous studies have shown that the heating mode depends on the transmission performance of refractory insulation materials. In this study, a commonly used refractory material (fused silica ceramics) for microwave heating was studied, according to the law of electromagnetic wave propagation in a single-layer plate, the power transmission coefficient (PTC) of the material at different thickness, temperature and frequency (915 MHz and 2360 MHz) was calculated and analysed, in order to design the refractory structure which has good microwave transmission performance in the whole microwave heating process. The results show that the transmission performance of fused silica ceramics fluctuates regularly with increasing thickness, and there are several microwave transmission peaks in the PTC patterns, the thicknesses corresponding to the transmission peaks at frequency 2360 MHz are in order 0.033 m, 0.065 m and 0.098 m; as the temperature increases, the position of the transmission peaks will shift to a smaller thickness, the transmission performance of fused silica ceramics decreases slightly with increasing temperature. Comparing the transmission performance of mullite, alumina (Al2O3) and fused silica ceramics, it was found that the fused silica ceramics have excellent transmission properties; especially it is at high temperature. The results of this study can provide guidance for the selection of refractory structure materials and sizes as well as the optimization of heating process parameters in high-temperature microwave heating.
关键词： A. Microwave heating,D. Transmission performance,B. Fused silica ceramic,C. High temperature wave transmitting material
更新于2025-09-23 15:22:29