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- Inner Mongolia University
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Optical analysis during reduction of nitric oxide in microwave-induced plasma promoted by activated cokes at atmospheric pressure
摘要： Emission from microwave (MW)-induced argon plasma promoted by a bed of activated coke granules was analyzed spectroscopically during non-catalytic reduction of nitric oxide (NO) at atmospheric pressure. The spectral analysis with a high resolution revealed that strong 5 peaks were recognized in a similar wavelength region to N2+ first negative band when NO molecules were included in argon plasma. The strongest peak is caused by the Ar(II) ions excited with energy corresponding to 388.033 nm in the progress of atomic transition 3s23p4(3P)4d 4D1/2 → 3s23p4(3P)4p 4D°1/2. This transition must be enhanced by an interaction with any intermediates or radical species yielded during NO reduction reactions. The plasma temperatures were determined by Boltzmann plots from intensities of any two peaks in the spectral band. The temperature was significantly different dependently on choice of two peaks, whose fact is implying non-equilibrium plasma. The maximum temperature was recognized at a high level of 40,000 K due to the activation during the reactions. The images of the plasma observed by high-speed camera showed dynamic features so that MW discharge like streamer was generated frequently in the reactor. The reaction rate could be correlated with the ratio of the area dominated by dynamic plasma to the cross section in the reactor.
关键词： High-speed camera images,Argon plasma,Microwave discharge,Spectroscopic measurement,de-NOx
更新于2025-09-23 15:22:29
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Synthesis of Mn doped ZnO nanopowders by MW-HTS and its structural, morphological and optical characteristics
摘要： In this study, undoped and Mn doped ZnO nanopowders were synthesized by using the microwave assisted hydrothermal (MW-HTS) method. Doping ratio of Mn in the ZnO was set to 1, 5 and 10%. The effect of Mn concentration on the structural and morphological properties of ZnO nanopowders was investigated using XRD, SEM, XPS and FTIR. XRD results showed that the nanopowders have hexagonal wurtzite structure. The lattice parameters increased with increasing Mn incorporation. SEM images showed that all the samples were formed in nanorod structure and the average diameter of the rods decreased with the Mn concentration. XPS results veri?ed the presence of Mn as a doping element into ZnO crystal lattice and the oxidation states of Mn and Zn. The chemical interactions of ZnO and ZnO:Mn nanopowders were determined for using FTIR spectrum.
关键词： FTIR,Mn doped ZnO,XPS,Microwave assisted hydrothermal,Nanorods
更新于2025-09-23 15:22:29
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A microwave photonic phase-tunable mixer with local oscillator frequency doubling
摘要： A microwave photonic phase-tunable mixer with a doubled local oscillator (LO) frequency is presented based on an integrated dual-polarization dual-parallel Mach-Zehnder modulator (DP-DPMZM). A radio frequency (RF) signal is sent to one of the sub-DPMZMs via an electrical 90° hybrid coupler, and the carrier-suppressed single-sideband (CS-SSB) modulation is output. Another sub-DPMZM is modulated by a LO signal, and the 2nd-order carrier-suppressed double-sideband (CS-DSB) modulation is produced by combining a fiber Bragg grating (FBG). A single bias voltage of the modulator can change the phase shift linearly. The mixing signal with double LO frequency and phase shift can be acquired after the photodetector. Experimental setup is implemented, and the results indicate that the spur suppression ratios of the up/down-converted signals are 22.5 dB and 25.2 dB. The spurious-free dynamic range (SFDR) values are 102.97 dB·Hz2/3 in the down-conversion mode and 100.81 dB·Hz2/3 in the up-conversion mode. The phase shift can be varied continuously in the range of 360°. The proposed compact link is characterized by function multiplexing, half reduction of the LO frequency and high electrical purity.
关键词： Mixer,Microwave photonics,Phase shifter,Frequency doubling
更新于2025-09-23 15:22:29
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Tissue-mimicking materials for breast phantoms up to 50 GHz
摘要： Millimeter (mm)-wave imaging has been recently proposed as a new technique for breast cancer detection, based on the significant dielectric contrast between healthy and tumor tissues. Here we propose a procedure to fabricate, electromagnetically characterize and preserve realistic breast tissue-mimicking phantoms for testing mm-wave imaging prototypes. Low-cost, non-toxic and easy-to-produce mixtures made of sunflower oil, water and gelatin were prepared and their dielectric properties were for the first time measured in the [0.5-50] GHz frequency range using a coaxial probe kit. Different oil and gelatin percentages were tested. An alternative recipe based on a waste-oil hardener was also proposed. Finally, water and sunflower oil were investigated as preservation media. The mixtures electromagnetic properties were in good agreement with those of human breast ex vivo samples. By changing the ingredient concentrations or using different solidifying agents it was possible to mimic different tissue types. Besides, we show that sunflower oil represents an effective preservation medium for the developed materials. The first breast phantom mimicking a tumor mass into healthy tissues up to 50 GHz was also successfully fabricated. Results demonstrated the potential of the designed recipes to mimic breast tissues with different biological characteristics.
关键词： microwave imaging,breast phantoms,breast cancer,dielectric properties,millimeter waves,cancer screening
更新于2025-09-23 15:22:29
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[IEEE 2018 Asia Communications and Photonics Conference (ACP) - Hangzhou, China (2018.10.26-2018.10.29)] 2018 Asia Communications and Photonics Conference (ACP) - A code-free optical undersampling technique for broadband microwave spectrum measurement
摘要： A novel broadband microwave (MW) spectrum measurement (BMSM) scheme based on code-free optical undersampling and homodyne detection is proposed. The fully analog generation of optical pulses with a far-less-than-Nyquist rate is only through modulating cascaded electrooptical modulators by a single RF tone instead of any high-speed coding sequence modulation. Homodyne detection will reduce the analysis bandwidth of BMSM and enhance the detection performance of weak signal. A multi-band signal with 20 GHz spectral range and SNR = 61 dB is used to investigate the BMSM performance of this scheme, and the results show good performance for BMSM. The potentials for further optimization in practice are also discussed.
关键词： homodyne detection,optical undersampling,microwave spectrum measurement
更新于2025-09-23 15:22:29
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[IEEE 2018 Dynamics of Systems, Mechanisms and Machines (Dynamics) - Omsk, Russia (2018.11.13-2018.11.15)] 2018 Dynamics of Systems, Mechanisms and Machines (Dynamics) - Automatic Nonlinear Modeling Technique for Gaas HEMT
摘要： A new technique for nonlinear transistor modeling is suggested. The technique includes an analytical extraction and a multistage optimization, providing fully automated modeling. An extraction algorithm for the parameters of an internal voltage-controlled current source Ids is shown. A fully automated workflow of small-signal model extraction is presented. An approach for obtaining parameters of nonlinear capacitances is described. A 0.15um GaAs pHEMT nonlinear model was built and verified with measured IV-curve, multi-bias S-parameters and power characteristics.
关键词： compact nonlinear model,microwave transistor,large-signal model,GaAs HEMT
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 - Proposal of Millimeter-Wave Adaptive Glucose-Concentration Estimation System Using Complex-Valued Neural Networks
摘要： This paper presents a novel approach for glucose concentration detection using a complex-valued neural network (CVNN) based on microwave transmission characteristics. The method leverages the dielectric properties of glucose solutions, which vary with concentration, to train a neural network that accurately predicts glucose levels from S-parameter measurements. Experimental results demonstrate high accuracy and robustness across a range of concentrations from 0 to 300 mg/dL.
关键词： complex-valued neural network,dielectric properties,glucose detection,S-parameters,microwave sensing
更新于2025-09-23 15:22:29
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Design, Development, and Operation of Seven Channels' 100-GHz Interferometer for Plasma Density Measurement
摘要： A seven-channel microwave interferometer (100 GHz) is designed, developed, and used to measure the radial profile of the plasma density (ne) in Aditya tokamak. The resolution of the density measurement is ne = 2 × 10^11 cm^-3. The spatial and time resolutions are 7 cm and 10 μs, respectively. The chord-averaged measurements from seven channels are Abel inverted to obtain the radial profile of the plasma density. Plasma density measured by the microwave interferometer is well matched with that measured by the Thomson scattering diagnostics.
关键词： Density measurements,interferometry,plasma measurements,microwave circuits
更新于2025-09-23 15:22:29
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Distributed Amplifier Based on Monolayer Graphene Field Effect Transistor
摘要： Due to the ultra-high carrier mobility and ultralow resistivity of Graphene channel, a Graphene field effect transistor (GFET) is an interesting candidate for future RF and microwave electronics. In this paper, the introduction and review of existing compact circuit-level model of GFETs are presented. A compact GFET model based on drift-diffusion transport theory is then implemented in Verilog-A for RF/microwave circuit analysis. Finally, the GFET model is used to design a GFET-based distributed amplifier (DA) using advanced design system (ADS) tools. The simulation results demonstrate a gain of 8dB, an input/output return loss less than ?10dB, -3dB bandwidth from DC up to 5GHz and a dissipation of about 60.45mW for a 1.5V power supply. The main performance characteristics of the distributed amplifier are compared with 0.18μm CMOS technology.
关键词： Microwave,ADS,Distributed Amplifier (DA),Graphene Field Effect Transistor (GFET)
更新于2025-09-23 15:22:29
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A Compact X-Band Vector Network Analyzer for Microwave Image Sensing
摘要： This work develops a compact and portable X-band vector network analyzer (VNA) for low-cost microwave image sensing applications. Since significant local oscillator (LO) injection pulling and poor LO phase noise performance may reduce the accuracy of measurement, the developed VNA uses the single-conversion technique and the phase noise cancellation technique to suppress the injection pulling effect and the LO phase noise, respectively. A hybrid phase detection algorithm that includes arctangent, arcsine and arccosine functions is proposed to overcome the bottleneck of the distortion of conventional quadrature phase detection in some phase regions. Experimental results demonstrate that the X-band microwave image sensing system that uses the developed VNA, which is highly compact and portable, can effectively yield a contour image of bones in a chicken wing and pork ribs.
关键词： transceiver,microwave image sensing,vector network analyzer,phase noise,frequency synthesizer
更新于2025-09-23 15:22:29