The Experts below are selected from a list of 5319 Experts worldwide ranked by ideXlab platform
Glenn S. Smith - One of the best experts on this subject based on the ideXlab platform.
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A study of pulse radiation from several broad-band loaded monopoles
IEEE Transactions on Antennas and Propagation, 1996Co-Authors: T.p. Montoya, Glenn S. SmithAbstract:Five previously proposed designs for broad-band monopole antennas are evaluated for pulse radiation. These designs use continuous resistive loading and/or discrete capacitive loading to increase the bandwidth over that of a simple, metallic monopole. The parameters for each of the designs are scaled so that the designs can be compared on a common basis (frequency range). Each of the antennas is analyzed numerically, and quantities characteristic of their pulsed performance are computed. These quantities include the Reflected Voltage in the feeding transmission line, radiated electric field, radiating efficiency, time-domain gain, fidelity, and symmetry when the monopoles are excited by a differentiated Gaussian pulse. In addition, the input reflection coefficient and gain at broadside for monochromatic excitation are shown. Explanations are provided for the differences in performance for these designs.
Mohamed Nafis, Nur Biha - One of the best experts on this subject based on the ideXlab platform.
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Microcontroller-based moisture meter for ginger
'Penerbit Universiti Kebangsaan Malaysia (UKM Press)', 2018Co-Authors: Mohamed Nafis, Nur Biha, Abbas Zulkifly, Hassan Jumiah, Suhaime Noradira, Lee, Kim Yee, You, Kok Yeow, Othman ZauliaAbstract:This paper describes the development of a simple method to determine the permittivity and moisture content (m.c.) of ginger. The measurement system consists of a microwave sensor, directional coupler and a PIC microcontroller. The microwave sensor is a square flanged open-ended coaxial (OEC) sensor made from SMA stub contact panel with outer diameter (O.D) 4.10 mm. The microwave oven drying method was used to determine the actual m.c. of the ginger. All data acquisition, processing and display were accomplished using a PIC16F690 microcontroller programmed using Flowcode software. The actual values of the permittivity of ginger were obtained by using the Agilent (now Keysight Technologies) 85070B dielectric probe along with a HP 8720B Vector Network Analyzer (VNA). The results showed good relationships between m.c., permittivity (dielectric constant (εʹ) and loss factor (ε̋)) and Reflected Voltage. The calibration equations between Reflected Voltage and m.c. have been established for the sensor. The measurement system provides a simple, fast and accurate technique to predict m.c., εʹ and ε̋ of ginger from Reflected Voltage measurements alone. The accuracy in determination of m.c., εʹ and ε̋ in ginger was within 2.9%, 2.7%, and 3.6%, respectively
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Development of a microcontroller-based microwave instrumentation system for determination of moisture content in oil palm fruits and ginger
2018Co-Authors: Mohamed Nafis, Nur BihaAbstract:In agriculture, moisture content (MC) is among the important factors that are closely correlated to the properties of agriculture products. There is a diverse range of techniques such as Near-Infrared (NIR) spectroscopy, magnetic resonance, X-ray and computed tomography that have been used for the quality assessment in agriculture products. However, the microwave aquametry technique which applies MC measurement and correlates it to the quality of the agriculture products, has been widely used due to the fast, precise, cost and energy saving as well as compliance with safety regulations. Several sensors such as, microstrip and coplanar which are based on the attenuation measurement, have been suggested previously for the MC determination but these techniques required laborious preparation. The Keysight OEC probe has been used to determine the permittivity of agriculture products, however, it requires a network analyzer which is bulky and expensive. As a solution to this limitation, the low cost microcontroller-based microwave instrumentation system for determination of MC percentage in oil palm fruits and gingers is developed in order to determine the quality of samples by relying on MC measurement. This thesis describes in detail the development of a microcontrollerbased microwave instrumentation system for the determination of MC percentage in oil palm fruits and ginger to determine the quality of samples by relying on MC measurement. This instrumentation system or also known as reflectometer operates at 2GHz includes a stripline directional coupler, two diode detectors, a PIC microcontroller, liquid crystal display (LCD), and sensors such as open ended coaxial-stub contact panel and monopole sensors. The stripline directional coupler’s design, analysis and also performance testing are accomplished by using Microwave Office Software. The Flow Code version 5.5 was used to program the PIC16F690 microcontroller for data acquisition as well as to calculate the MC based on measured Reflected Voltage, processing and LCD display. The permittivity measurement is carried by using the Keysight 85070B dielectric probe kit that utilize with the computer controlled HP 8720B vector network analyzer software. The COMSOL Multiphysics® software is used to visualization of the electric field distribution of both the open ended coaxial-stub contact panel and monopole sensors based on the permittivity value measured. The calibration equations relating the measured Reflected Voltage by using the reflectometer to the actual MC, and permittivity (dielectric constant (ԑ′) and loss factor (ԑ")) has been established. The predicted percentage of MC in samples is calculated based on the measured Reflected Voltages can by interchanging the y and x axes. On the other hand, for the predicted permittivity measurement, the calibration equation between the Reflected Voltage and MC is substituted into the relationship between permittivity and MC. The accuracies of the calibration equations were determined by comparing the predicted MC with the actual MC using microwave oven drying method on another batch of the samples while for the permittivity measurement, the accuracy is determined by comparing the predicted and actual permittivity values that obtained from the another batch of permittivity measurement by using Keysight OEC probe. All of the calibration equations shows a good agreement for input Reflected Voltage which utilizing the Reflected Voltage values to determine the MC, ԑ′ and ԑ" by utilizing the mean relative error formula. For oil palm fruits, the accuracies for MC, ԑ′ and ԑ" were within 3.8%, 4.1%, and 4.5%, respectively. While for ginger, the accuracies for MC, ԑ′ and ԑ" were within 2.9%, 2.7%, and 3.6%, respectively
T.p. Montoya - One of the best experts on this subject based on the ideXlab platform.
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A study of pulse radiation from several broad-band loaded monopoles
IEEE Transactions on Antennas and Propagation, 1996Co-Authors: T.p. Montoya, Glenn S. SmithAbstract:Five previously proposed designs for broad-band monopole antennas are evaluated for pulse radiation. These designs use continuous resistive loading and/or discrete capacitive loading to increase the bandwidth over that of a simple, metallic monopole. The parameters for each of the designs are scaled so that the designs can be compared on a common basis (frequency range). Each of the antennas is analyzed numerically, and quantities characteristic of their pulsed performance are computed. These quantities include the Reflected Voltage in the feeding transmission line, radiated electric field, radiating efficiency, time-domain gain, fidelity, and symmetry when the monopoles are excited by a differentiated Gaussian pulse. In addition, the input reflection coefficient and gain at broadside for monochromatic excitation are shown. Explanations are provided for the differences in performance for these designs.
V. F. Tarasenko - One of the best experts on this subject based on the ideXlab platform.
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effect of the cathode material on the amplitude of the ultrashort avalanche electron beam in atmospheric pressure air
Technical Physics, 2015Co-Authors: Kh E Baksht, A G Burachenko, V. F. TarasenkoAbstract:Generation of ultrashort avalanche electron beam (UAEB) during subnanosecond breakdown in atmospheric-pressure air is investigated with a picosecond time resolution. The signals of incident and Reflected Voltage waves measured in the transmission line of the SLEP-150M generator have made it possible to reconstruct the Voltage in the electrode gap. It is found that due to an increase in the gap Voltage in the case of a stainless steel conical electrode, the UAEB amplitude is larger than for identical electrodes made of copper and aluminum. It is shown that the UAEB duration and amplitude increase when the conical electrode is replaced by a tubular electrode.
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diffuse discharge produced by repetitive nanosecond pulses in open air nitrogen and helium
Journal of Applied Physics, 2013Co-Authors: Tao Shao, M. V. Erofeev, V. F. Tarasenko, Yu V Shutko, Cheng Zhang, Evgeni Kh Baksht, Dongdong Zhang, Chengyan Ren, Ping YanAbstract:Atmospheric-pressure gas discharge driven by high Voltage pulses with fast rise-time and short duration has attracted significant attention for various plasma applications. In this paper, discharges were generated in a highly non-uniform electric field by point-plane gaps in open air by four repetitive nanosecond-pulse generators with repetition rate up to 1 kHz. The rise time of generators was 25 (generator #1), 15 (generator #2), 3 (generator #3), and 0.2 ns (generator #4) and a full width at half maximum was 40, 30-40, 5, and 1 ns, respectively. The experimental results show that there were typical discharge fashions, i.e., corona, diffuse, spark, or arc modes. The variables affecting the discharge characteristics, including the gap spacing and applied pulse parameters, were investigated. Especially, the diffuse discharges were investigated and discussed. With generator #1 at Voltage 70-120 kV, characteristics of measured x-rays on the discharge modes were studied, and it indicates that counts of x-rays in a diffuse discharge are up to a peak value under the experimental conditions. With amplitude of Voltage pulses in incident wave up to 18 (generator #3) and 12.5 kV (generator #4), runaway electron beam in low pressure helium, nitrogen, and air in a pulse-periodic mode of discharge with repetition rate up to 1 kHz was obtained. Electron beam was registered behind a thin foil in a pressure range from several to tens of Torr. X-ray radiation was obtained in a wide range of pressures, as well as at atmospheric pressure of helium, nitrogen, and air. Voltage pulses of positive and negative polarities were used. Generation of runaway electrons with pulses of positive polarity appeared because of Reflected Voltage pulses of reverse polarity.
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generation of runaway electrons in a nonuniform electric field by applying nanosecond Voltage pulses with a frequency of 100 1000 hz
Technical Physics, 2013Co-Authors: M. V. Erofeev, V. F. Tarasenko, Kh E Baksht, Yu V ShutkoAbstract:Generation of runaway electrons and X-ray radiation in helium and air under the action of a pulsed-periodic discharge in a nonuniform electric field is studied. Positive and negative Voltage pulses with a repetition rate of up to 1 kHz, a duration on the order of 1 ns, and an incident wave amplitude of 12.5 kV are applied to a needle-plane gap. For both polarities of the main Voltage pulse and a helium pressure from several Torr to several tens of Torr, the arrival of negative Reflected Voltage pulses at the gap is shown to be accompanied by an electron beam generation. X-ray radiation is detected in a wide range of pressure, including under normal pressure of helium and air.
Yu V Shutko - One of the best experts on this subject based on the ideXlab platform.
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diffuse discharge produced by repetitive nanosecond pulses in open air nitrogen and helium
Journal of Applied Physics, 2013Co-Authors: Tao Shao, M. V. Erofeev, V. F. Tarasenko, Yu V Shutko, Cheng Zhang, Evgeni Kh Baksht, Dongdong Zhang, Chengyan Ren, Ping YanAbstract:Atmospheric-pressure gas discharge driven by high Voltage pulses with fast rise-time and short duration has attracted significant attention for various plasma applications. In this paper, discharges were generated in a highly non-uniform electric field by point-plane gaps in open air by four repetitive nanosecond-pulse generators with repetition rate up to 1 kHz. The rise time of generators was 25 (generator #1), 15 (generator #2), 3 (generator #3), and 0.2 ns (generator #4) and a full width at half maximum was 40, 30-40, 5, and 1 ns, respectively. The experimental results show that there were typical discharge fashions, i.e., corona, diffuse, spark, or arc modes. The variables affecting the discharge characteristics, including the gap spacing and applied pulse parameters, were investigated. Especially, the diffuse discharges were investigated and discussed. With generator #1 at Voltage 70-120 kV, characteristics of measured x-rays on the discharge modes were studied, and it indicates that counts of x-rays in a diffuse discharge are up to a peak value under the experimental conditions. With amplitude of Voltage pulses in incident wave up to 18 (generator #3) and 12.5 kV (generator #4), runaway electron beam in low pressure helium, nitrogen, and air in a pulse-periodic mode of discharge with repetition rate up to 1 kHz was obtained. Electron beam was registered behind a thin foil in a pressure range from several to tens of Torr. X-ray radiation was obtained in a wide range of pressures, as well as at atmospheric pressure of helium, nitrogen, and air. Voltage pulses of positive and negative polarities were used. Generation of runaway electrons with pulses of positive polarity appeared because of Reflected Voltage pulses of reverse polarity.
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generation of runaway electrons in a nonuniform electric field by applying nanosecond Voltage pulses with a frequency of 100 1000 hz
Technical Physics, 2013Co-Authors: M. V. Erofeev, V. F. Tarasenko, Kh E Baksht, Yu V ShutkoAbstract:Generation of runaway electrons and X-ray radiation in helium and air under the action of a pulsed-periodic discharge in a nonuniform electric field is studied. Positive and negative Voltage pulses with a repetition rate of up to 1 kHz, a duration on the order of 1 ns, and an incident wave amplitude of 12.5 kV are applied to a needle-plane gap. For both polarities of the main Voltage pulse and a helium pressure from several Torr to several tens of Torr, the arrival of negative Reflected Voltage pulses at the gap is shown to be accompanied by an electron beam generation. X-ray radiation is detected in a wide range of pressure, including under normal pressure of helium and air.