Current Issue : January - March Volume : 2015 Issue Number : 1 Articles : 4 Articles
The efficiency and factors affecting tetracycline (TC) degradation by birnessite under microwave irradiation (MI) were investigated\nunder different initial TC concentrations, solution pH, MI time, and MI power. The crystal structure, degradation efficiency,\nand reaction mechanism were investigated using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and\nultraviolet-visible spectroscopy (UV-Vis). The results showed that birnessite was an excellent microwave catalyst. The maximum\nTC removal efficiency by birnessite was 99% under MI at 400Wfor 30 min in strongly acidic media. Under MI, the surface activity\nof birnessite increased, resulting in the ability to accelerate TC removal in high temperature....
Polycrystalline samples with the chemical formula CaCu3Ti4?xZrxO12 (x = 0, 0.02, 0.1, 0.2, 0.5, and 0.1) CCTZO were synthesized\nfrom metal nitrate solutions by the sol-gel method, followed by conventional and microwave heat treatments. The X-ray diffraction\npattern of powder calcined at 800?C in conventional furnace for 3 h showed formation of a single phase. The crystal structure did\nnot change on doping with zirconium and it remained cubic in the five studied compositions. The surface morphology of samples\nsintered at 1000?C in microwave furnace for 10 min was observed using a high resolution scanning electron microscope (HR-SEM).\nThe grain sizes were in the range of 250 nmââ?¬â??5 ?m for these samples. HRSEM results show that doping with Zr enhanced grain\ngrowth or densification. Energy dispersive X-ray spectroscopy (EDX) confirmed the presence of Zr.The dielectric characteristics\nof Zr doped CCTO were studied with an LCR meter in the frequency range of 50Hzââ?¬â??1MHz. A very high dielectric constant 21,500\nwas observed for the sample doped with Zr (0.02mol%) at 50Hz....
Information about temperature distribution is complex but of critical importance for the control of various microwave applications.\nIn this paper, an innovative way of temperature distribution monitoring using ultrasonic the rmometry in microwave field is\ninvestigated.Theprinciple of ultrasonic the rmometry in the situation of ideal gas is elaborated, and reconstruction algorithm based\non Markov radial basis function approximation and singular values decomposition is presented and described in detail. In order to\nvalidate the performance of temperature distribution reconstruction of our presented algorithm, four two-dimensional temperature\ndistribution models with different complexities are utilized in simulation experiments. Especially, simulation experiments taking\nerror of measurement into account are studied to verify the robustness. Figure profiles show remarkable correspondence between\nthe reconstructed ones and their models, while quantitative analysis, including the overall temperature error analysis and the\nhotspot positioning analysis, shows that different kinds of errors calculated are all within the limit ranges. In addition, the time\nanalysis of simulation experiments also demonstrates its well real-time capability....
This paper presents the design and experiment of a novel microwave gain equalizer based on the substrate integrated waveguide\n(SIW) technique.The proposed equalizer is formed by an SIW loaded by SIW resonators, which has very compact structure and can\ncompensate for gain slope of microwave systems. Equivalent circuit analysis is given about the proposed structure for a better insight\ninto the structureââ?¬â?¢s response. A Ku-Band equalizer with four SIW resonators is simulated and fabricated with a multilayer printed\ncircuit board process.The measured results show good performance and agreement with the simulated results; an attenuation slope\nof ?4.5 dB over 12.5ââ?¬â??13.5GHz is reached with a size reduction of 76%....
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