Papers by Keyword: Microwave Technique

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Authors: Hou Kit Mun, Kok Yeow You, Mohamad Ngasri Dimon
Abstract: This paper proposes a microstrip wide-ring sensor for percentage of broken rice determination based on transmission power measurement. The microstrip wide-ring sensor with low insertion loss was designed to operate at frequency range from 1 GHz to 3 GHz. Calibration equations for measurement of percentage of broken rice at 1.93 GHz and 2.50 GHz were obtained and validated with white rice for percentage of broken rice ranging from 0% to 100%. The lowest error in percentage of broken rice prediction was 11.03% at 1.93 GHz.
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Authors: Suparut Narksitipan, Thaweedet Awirut
Abstract: In this research, zinc oxide (ZnO) films were prepared using a wet chemical reaction via a microwave technique. X-ray diffraction techniques (XRD) and energy dispersive x-ray spectroscopy (EDS) were used to study the phases, crystalline structures, chemical compositions and optical properties of the films, respectively. Optical transmittance was also measured through UV-VIS spectroscopy. Surface film morphologies were investigated by scanning electron microscopy (SEM). As a result, a ZnO phase with a hexagonal structure was detected. The EDS spectrum shows that elements of Zn and O were present. The average optical transmittance value for all films was 75% at a wavelength of 370-375 nm, a comparison among the films obtained at different times show a transmittance value slightly higher for films obtained at higher times. A calculation of the energy band gap of ZnO films was estimated to be in the range of 3.31 to 3.35 eV. Additional, the ZnO films showed a smooth surface.
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Authors: Suliana Abu Bakar, Suzana Yusup, Murni Melati Ahmad, Armando T. Quitain, Mitsuru Sasaki, Motonobu Goto, Yoshimitsu Uemura, Junaid Ahmad
Abstract: The production of biodiesel from crude palm oil (CPO) using microwave technique is investigated and has been compared with conventional heating. Two-step biodiesel production process is applied to maximize the highest biodiesel yield in short reaction time using microwave method. Sulfuric acid (H2SO4) as acid catalysts is used in pre-treatment of feedstock by esterification process followed by potassium hydroxide (KOH) as base catalyst for transesterification process with low methanol to oil ratio. The main purpose of the pre-treatment process is to reduce the free fatty acids (FFA) content of CPO from higher value of FFA content (>6.8%) to a minimum level for biodiesel production (<1%). Esterification and transesterification is carried out in fully instrumented and controlled microwave reactor system to get higher yield in shorter time. This two-step esterification and transesterification process showed that the maximum conversion of palm biodiesel obtained is 95.1% with the process conditions of methanol-to-oil molar ratio of 6:1, reaction temperature 65oC, reaction time 15min, and 2% (wt/wt) KOH amount using microwave method compared to conventional heating where the palm oil methyl ester (POME) yield obtained is 81% at the same conditions. The result showed that, the biodiesel production using microwave technique proved to be a fast and easy route to get high yields of biodiesel.
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Authors: Jin Ping Pan, Xin Wei Zhu, Lian Jiang Tan
Abstract: In the present paper, an effective method for detecting the cold weld defects in the thermal fusion weld of high-density polyethylene (HDPE) pipelines based on microwave technique is proposed. Using a microwave testing system, HDPE piping welds containing cold weld defects caused by insufficient heating time were examined by frequency sweep within the range of 9.2-9.9 GHz. At the frequencies that were most sensitive to the cold weld defects, the measured reflection coefficient S11 showed greatly different values between the good weld and those containing cold weld defects. The readily detectable differences in S11 value make the detection of the cold weld defects possible and feasible. This work provides insights for non-destructive testing of technical defects in HDPE piping welds.
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Authors: A. Verevkin, E.M. Gershenzon, G.N. Gol'tsman, N.G. Ptitsina, G.M. Chulkova, K.S. Smirnov, R. Sobolewski
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Authors: Andrzej Wyciślik, Janusz Richter
Abstract: The paper presents results of the investigation of SM5Ti3Nb2 steel carbide isolates. The acids and acid mixtures for dissolution of selected carbides phase isolates, using microwave technique were specified. This way of dissolution of carbide isolates reduced the time of mineralization to about 10-15 minutes. Presented methods of dissolution can be applied in the chemical analysis of carbide isolates, using atomic absorption spectrometry and optical emission spectrometry inductively coupled plasma. It is indicated the acids, using to removal of noncarbide metallic residue in isolates.
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