• Title/Summary/Keyword: dual-phase

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Influence of variable thermal conductivity on waves propagating through thermo-elastic medium

  • Abo-Dahab, Sayed M.;Jahangir, Adnan;Dar, Adiya
    • Structural Engineering and Mechanics
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    • v.82 no.4
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    • pp.459-467
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    • 2022
  • We investigated the influence of variable thermal conductivity on waves propagating through the elastic medium. Infinitesimal deformation results in generation of thermal signal, and is analyzed by using dual phase lag heat (DPL) conduction model. The medium considered is homogenous, isotropic and bounded by thermal shock. The elastic waves propagating through the medium are considered to be harmonic in nature, and expressions for the physical variables are obtained accordingly. Analytically, we obtained the expressions for displacement components, temperature, micro-temperature component and stresses. The theoretical results obtained are computed graphically for the particular medium by using MATLAB.

Thermo-mechanical response of size-dependent piezoelectric materials in thermo-viscoelasticity theory

  • Ezzat, Magdy A.;Al-Muhiameed, Zeid I.A.
    • Steel and Composite Structures
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    • v.45 no.4
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    • pp.535-546
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    • 2022
  • The memory response of nonlocal systematical formulation size-dependent coupling of viscoelastic deformation and thermal fields for piezoelectric materials with dual-phase lag heat conduction law is constructed. The method of the matrix exponential, which constitutes the basis of the state-space approach of modern control theory, is applied to the non-dimensional equations. The resulting formulation together with the Laplace transform technique is applied to solve a problem of a semi-infinite piezoelectric rod subjected to a continuous heat flux with constant time rates. The inversion of the Laplace transforms is carried out using a numerical approach. Some comparisons of the impacts of nonlocal parameters and time-delay constants for various forms of kernel functions on thermal spreads and thermo-viscoelastic response are illustrated graphically.

GPS/GLONASS Microstrip Active Antenna Apply to Curve Surface (곡면에 부착 가능한 GPS/GLONASS 마이크로스트립 능동 안테나)

  • Kim, Mi-Suk;Son, Seok-Bo;Joo, Hahn-Kie;Bae, Joon-Sung;Kim, Joon-O
    • Journal of the Korea Institute of Military Science and Technology
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    • v.14 no.1
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    • pp.1-8
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    • 2011
  • In this paper, dual-feed circularly polarized microstrip patch antenna for GPS L1, GPS L2, GLONASS L1 signal was fabricated by using stacked patch. It was fed by dual coaxial probe on the patch at 50ohm impedance, and was simulated to resonate at GPS L1, GPS L2, GLONASS L1. To realize characteristics of right hand circular polarization using dual-feed stacked patch antenna and hybrid coupler for $90^{\circ}$ phase difference. Output of hybrid coupler was contacted input of Low Noise Amplifier(LNA). The LNA using dual band pass filter was designed and fabricated. The measured results of the implemented antenna is VSWR < 1.5 : 1 and the gain of 32dB(Zenith) over at GPS L1, L2, GLONASS L1.

A Dual-Output Integrated LLC Resonant Controller and LED Driver IC with PLL-Based Automatic Duty Control

  • Kim, HongJin;Kim, SoYoung;Lee, Kang-Yoon
    • Journal of Power Electronics
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    • v.12 no.6
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    • pp.886-894
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    • 2012
  • This paper presents a secondary-side, dual-mode feedback LLC resonant controller IC with dynamic PWM dimming for LED backlight units. In order to reduce the cost, master and slave outputs can be generated simultaneously with a single LLC resonant core based on dual-mode feedback topologies. Pulse Frequency Modulation (PFM) and Pulse Width Modulation (PWM) schemes are used for the master stage and slave stage, respectively. In order to guarantee the correct dual feedback operation, Phased-Locked Loop (PLL)-based automatic duty control circuit is proposed in this paper. The chip is fabricated using $0.35{\mu}m$ Bipolar-CMOS-DMOS (BCD) technology, and the die size is $2.5mm{\times}2.5mm$. The frequency of the gate driver (GDA/GDB) in the clock generator ranges from 50 to 425 kHz. The current consumption of the LLC resonant controller IC is 40 mA for a 100 kHz operation frequency using a 15 V supply. The duty ratio of the slave stage can be controlled from 40% to 60% independent of the frequency of the master stage.

The Effect of Distance between Two Transducers on Sonochemical Reactions in Dual Irradiation Systems (이중 초음파 조사 시스템에서 진동부 사이의 거리가 초음파 화학 반응에 미치는 영향)

  • Kim, Eunkyung;Son, Younggyu
    • Journal of Soil and Groundwater Environment
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    • v.18 no.5
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    • pp.39-45
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    • 2013
  • Many researchers have studied the effectiveness of ultrasound in chemical and environmental engineering fields including material synthesis, pollutant removal, cleaning, extraction, and disinfection. Acoustic cavitation induced by ultrasound irradiation in aqueous phase can cause various sonophysical and sonochemical reactions without any chemicals. However most of the previous studies focused only on the relationships between ultrasonic conditions and the results of sonochemical reactions in lab-scale sonoreactors. As a results of this, only a few studies have been devoted to design and optimization of industrial scale sonoreactors. In this study, the effect of the distance between two opposite transducer modules on sonochemical reactions was investigated in single and dual irradiation systems (334 kHz) for four distances including 50, 100, 150, and 200 mm using KI dosimetry. It was found that the dual irradiation systems provided higher performance in terms of the zeroth reaction coefficient and the cavitation yield compared to the single irradiation systems. The sonochemiluminescence (SCL) images for the visualization of the cavitation field showed that cavitation active zone was larger and sonochemical reaction intensity was much higher in the dual irradiation system than in the single irradiation system.

High-Reliability Three-Phase Dual-Buck Grid-Connected Inverter without Shoot-Through Problem

  • Fu, Zhenbin;Feng, Zhihua;Chen, Xi;Zheng, Xinxin
    • Journal of Power Electronics
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    • v.19 no.2
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    • pp.454-462
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    • 2019
  • When compared to traditional bridge-type inverters, the dual-buck inverter has a higher reliability due to the fact that its bridge legs do not have a shoot-through problem. In this paper, the working principle of the dual-buck inverter is analyzed. A comparison of the working modes under full-cycle and half-cycle control is discussed. With half-cycle control, the inverter can realize a higher efficiency. However, this results in current zero-crossing distortion. The corresponding control strategy of the dual-buck inverter is proposed in order to realize both high efficiency and low current harmonic distortion. In addition, the system stability is analyzed. Dead-time is unnecessary due to the advantages of the topology. Thus, the current harmonic distortion can be further reduced. An inverter with the proposed control strategy has the advantages of high reliability, high efficiency and low current harmonic distortion. Finally, simulation and experimental results are given to verify the theoretical analysis.

Design of a Dual Band High PAE Power Amplifier using Single FET and CRLH-TL (Single FET와 CRLH 전송선을 이용한 이중대역 고효율 전력증폭기 설계)

  • Kim, Seon-Sook;Seo, Chul-Hun
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.47 no.2
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    • pp.56-61
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    • 2010
  • In this paper, high efficient power amplifier with dual band has been realized. Dual band power amplifier have used modify stub matching for single FET, center frequency 2.14GHz and 5.2GHz respectively. The dual-band operation of the CRLH TL is achieved by the frequency offset and the nonlinear phase slope of the CRLH TL for the matching network of the power amplifier. Because the control of the all harmonic components is very difficult m dual-band, we have managed only the second- and third-harmonics to obtain the high efficiency with the CRLH TL in dual-band. Dual-band characteristics in the output has to balance. Two operating frequencies are chosen at 2.14 GHz and 5.2 GHz in this work. The measured results show that the output power of 28.56 dBm and 29 dBm was obtained at 2.14 GHz and 5.2 GHz, respectively. At this point, we have obtained the power-added efficiency (PAE) of 65.824 % and 69.86 % at two operation frequencies, respectively.

Runoff Analysis Using Dual Polarization RADAR and Distributed Model (이중편파 레이더강우와 분포형 모형을 이용한 유출해석)

  • Jeong, Jiyoung;Yu, Myungsu;Yi, Jaeeung
    • Journal of Korea Water Resources Association
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    • v.47 no.9
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    • pp.801-812
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    • 2014
  • In this study, average rainfall of basin was estimated and compared with that obtained from Biseulsan dual polarization RADAR. And the runoffs are estimated using Vflo distribution model for Habcheon reservoir basin and Huicheon basin. In the rainfall estimation using dual polarization RADAR, the rainfall was estimated by using the specific phase difference and differential reflectivity of dual polarization RADAR variables. As a result, for all events rainfall estimation using dual polarization RADAR has the closest value to the gauge rainfall in terms of the peak rainfall and total rainfall. Also, runoff simulation results from dual polarization RADAR show the better results. It is concluded that the method using dual polarization radar can improve the accuracy more than a single polarization radar using only horizontal reflectivity.

Multi-Functional Microstrip Spiral Antenna : Dual-Band Operation and Multi-Pattern Control (다양한 복사패턴을 가지는 이중대역용 다기능 마이크로스트립 스파이럴 안테나)

  • 김명기;오대영;박익모
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.40 no.11
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    • pp.77-84
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    • 2003
  • This paper presents a multi-functional microstrip spital antenna that operates in dual frequency bands. Several types of beam shape can be selected by controlling the phase difference of two spiral arms with the phase shifters located on each feed line. It has a normal beam at the lower frequency band, and four different patterns at the higher frequency band: normal beam, conical beam and two types of tilted beam. The antenna exhibits more than 10% of bandwidth at each band. The antenna is fabricated with conductor backed electromagnetic absorber in order to attain unidirectional radiation pattern and confirmed the multi-functionality by measurements.