The Experts below are selected from a list of 118110 Experts worldwide ranked by ideXlab platform
Y Kharrazi - One of the best experts on this subject based on the ideXlab platform.
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study on the effect of prolonged mechanical Vibration on the grain refinement and density of a356 aluminum alloy
Materials & Design, 2009Co-Authors: Farshid Taghavi, H Saghafian, Y KharraziAbstract:Abstract In the present paper, the effect of Vibration Frequency and time on the size of α-Al primary solid phase and density on an A356 aluminum alloy was studied. The Vibration frequencies and times used were 10, 20, 30, 40 and 50 Hz and 5, 10 and 15 min, respectively. It was observed that the increase in Vibration time up to 15 min and Vibration Frequency up to 50 Hz led to decrease in the size of α-Al phase. The results show that maximum grain refinement was occurred at 50 Hz and 15 min Vibration conditions. At these conditions, the size of α-Al phase decreased down to 173 μm and 53% grain refinement was achieved. However, it was observed that the increase in Frequency up to 50 Hz and time up to 15 min led to increase in the density of A356 aluminum alloy. The best density was obtained at 50 Hz and 15 min resulting in density of 2.68 g/cm3.
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study on the ability of mechanical Vibration for the production of thixotropic microstructure in a356 aluminum alloy
Materials & Design, 2009Co-Authors: Farshid Taghavi, H Saghafian, Y KharraziAbstract:In the present paper, efficiency of mechanical Vibration for producing semisolid slurry with thixotropic microstructure in an A356 aluminum alloy was studied. The effects of Vibration Frequency and time were investigated on the size and morphology of α-Al phase and grain refinement degree. It was observed that thixotropic microstructure could be obtained in the Al alloy by applying mechanical Vibration. It was also found that size and morphology of α-Al phase were strongly affected by Vibration Frequency and time.
Xianbing Huang - One of the best experts on this subject based on the ideXlab platform.
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distributed fiber sparse wideband Vibration sensing by sub nyquist additive random sampling
Optics Letters, 2018Co-Authors: Jingdong Zhang, Hua Zheng, Tao Zhu, Guolu Yin, Min Liu, Yongzhong Bai, Feng Qiu, Xianbing HuangAbstract:The round-trip time of the light pulse limits the maximum detectable Vibration Frequency response range of phase-sensitive optical time domain reflectometry (ϕ-OTDR). Unlike the uniform laser pulse interval in conventional ϕ-OTDR, we randomly modulate the pulse interval so that an equivalent sub-Nyquist additive random sampling (sNARS) is realized for every sensing point of the long interrogation fiber. For a ϕ-OTDR system with 10 km sensing length, the sNARS method is optimized by theoretical analysis and Monte Carlo simulation, and the experimental results verify that a wideband sparse signal can be identified and reconstructed. Such a method can broaden the Vibration Frequency response range of ϕ-OTDR, which is of great significance in sparse-wideband-Frequency Vibration signal detection.
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distributed fiber sparse wideband Vibration sensing by sub nyquist additive random sampling
arXiv: Instrumentation and Detectors, 2017Co-Authors: Jingdong Zhang, Hua Zheng, Tao Zhu, Guolu Yin, Min Liu, Yongzhong Bai, Feng Qiu, Xianbing HuangAbstract:The round trip time of the light pulse limits the maximum detectable Vibration Frequency response range of phase-sensitive optical time domain reflectometry ({\phi}-OTDR). Unlike the uniform laser pulse interval in conventional {\phi}-OTDR, we randomly modulate the pulse interval, so that an equivalent sub-Nyquist additive random sampling (sNARS) is realized for every sensing point of the long interrogation fiber. For an {\phi}-OTDR system with 10 km sensing length, the sNARS method is optimized by theoretical analysis and Monte Carlo simulation, and the experimental results verify that a wide-band spars signal can be identified and reconstructed. Such a method can broaden the Vibration Frequency response range of {\phi}-OTDR, which is of great significance in sparse-wideband-Frequency Vibration signal detection, such as rail track monitoring and metal defect detection.
Dong Wook Kim - One of the best experts on this subject based on the ideXlab platform.
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Vibration stimulation effect on biomechanical variation of lower-limb joint according to Vibration perception threshold
JVE International, 2017Co-Authors: Kiyoung Kwak, Huigyun Kim, Kyukeun Song, Dong Wook KimAbstract:Vibration applied to relaxed muscle or tendon causes tonic reflex contraction in a muscle. Furthermore, when Vibration is applied to a muscle, involuntary enhancement of EMG and contraction is induced. Regarding this finding, many studies on the influence of Vibration on a muscle and static posture have been performed. However, precedent studies have limitations in applying single characteristic-Vibration without any consideration on personal difference on Vibration. And studies have been performed to research the change in dynamic state according to the intensity of sensing Vibration, but no analysis has been performed on the biomechanical aspect of the lower-limb joints. Nor any consideration was given on the effect of Vibration Frequency. Therefore, the purpose of this study was to analyze the biomechanical variation in the lower-limb joints according to the characteristics of the mechanical Vibration stimulation flowing into Achilles tendon and tibialis anterior tendon during gait, in consideration of the Vibration perception threshold and Vibration Frequency. For this purpose, this study measures the Vibration perception threshold according to Vibration Frequency at each tendon exposed to the stimulation. According to the result, Vibration perception threshold varies according to vibrating tendon and Vibration Frequency. Based on the measurement result of Vibration perception threshold, Vibration is applied to an Achilles tendon and tibialis anterior tendon during gait. In order to analyze the biomechanical variation in the lower-limb joints according to the characteristics of Vibration stimulation applied to each tendon during gait, the angle, moment and power of the lower-limb joints is analyzed using 3D motion analysis system. As a result, biomechanical variation, when Vibration lower than a perception threshold is applied, is similar to the variation when Vibration at perception threshold is applied. This result implies that Vibration stimulation may cause biomechanical variation of lower-limb joints. Furthermore, this means that its biomechanical variation may vary according to the characteristics of the Vibration applied
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the effect of mechanical Vibration stimulation of perception subthreshold on the muscle force and muscle reaction time of lower leg
Applied Bionics and Biomechanics, 2016Co-Authors: Huigyun Kim, Kiyoung Kwak, Dong Wook KimAbstract:The objective of this study is to investigate the effect of mechanical Vibration stimulation on the muscle force and muscle reaction time of lower leg according to perception threshold and Vibration Frequency. A Vibration stimulation with perception threshold intensity was applied on the Achilles tendon and tibialis anterior tendon. EMG measurement and analysis system were used to analyze the change of muscle force and muscle reaction time according to perception threshold and Vibration Frequency. A root-mean-square (RMS) value was extracted using analysis software and Maximum Voluntary Contraction (MVC) and Premotor Time (PMT) were analyzed. The measurement results showed that perception threshold was different from application sites of Vibration Frequency. Also, the muscle force and muscle reaction time showed difference according to the presence of Vibration, Frequency, and intensity. This result means that the Vibration stimulation causes the change on the muscle force and muscle reaction time and affects the muscles of lower leg by the characteristics of Vibration stimulation.
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variation of ankle biomechanical property according to vibro perception threshold and Vibration Frequency
Biomedical Engineering Letters, 2016Co-Authors: Kiyoung Kwak, Huigyun Kim, Dong Wook KimAbstract:Purpose The purpose of this study was to investigate the biomechanics according to vibro-perception threshold and Vibration Frequency during gait.
Farshid Taghavi - One of the best experts on this subject based on the ideXlab platform.
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study on the effect of prolonged mechanical Vibration on the grain refinement and density of a356 aluminum alloy
Materials & Design, 2009Co-Authors: Farshid Taghavi, H Saghafian, Y KharraziAbstract:Abstract In the present paper, the effect of Vibration Frequency and time on the size of α-Al primary solid phase and density on an A356 aluminum alloy was studied. The Vibration frequencies and times used were 10, 20, 30, 40 and 50 Hz and 5, 10 and 15 min, respectively. It was observed that the increase in Vibration time up to 15 min and Vibration Frequency up to 50 Hz led to decrease in the size of α-Al phase. The results show that maximum grain refinement was occurred at 50 Hz and 15 min Vibration conditions. At these conditions, the size of α-Al phase decreased down to 173 μm and 53% grain refinement was achieved. However, it was observed that the increase in Frequency up to 50 Hz and time up to 15 min led to increase in the density of A356 aluminum alloy. The best density was obtained at 50 Hz and 15 min resulting in density of 2.68 g/cm3.
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study on the ability of mechanical Vibration for the production of thixotropic microstructure in a356 aluminum alloy
Materials & Design, 2009Co-Authors: Farshid Taghavi, H Saghafian, Y KharraziAbstract:In the present paper, efficiency of mechanical Vibration for producing semisolid slurry with thixotropic microstructure in an A356 aluminum alloy was studied. The effects of Vibration Frequency and time were investigated on the size and morphology of α-Al phase and grain refinement degree. It was observed that thixotropic microstructure could be obtained in the Al alloy by applying mechanical Vibration. It was also found that size and morphology of α-Al phase were strongly affected by Vibration Frequency and time.
Jingdong Zhang - One of the best experts on this subject based on the ideXlab platform.
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distributed fiber sparse wideband Vibration sensing by sub nyquist additive random sampling
Optics Letters, 2018Co-Authors: Jingdong Zhang, Hua Zheng, Tao Zhu, Guolu Yin, Min Liu, Yongzhong Bai, Feng Qiu, Xianbing HuangAbstract:The round-trip time of the light pulse limits the maximum detectable Vibration Frequency response range of phase-sensitive optical time domain reflectometry (ϕ-OTDR). Unlike the uniform laser pulse interval in conventional ϕ-OTDR, we randomly modulate the pulse interval so that an equivalent sub-Nyquist additive random sampling (sNARS) is realized for every sensing point of the long interrogation fiber. For a ϕ-OTDR system with 10 km sensing length, the sNARS method is optimized by theoretical analysis and Monte Carlo simulation, and the experimental results verify that a wideband sparse signal can be identified and reconstructed. Such a method can broaden the Vibration Frequency response range of ϕ-OTDR, which is of great significance in sparse-wideband-Frequency Vibration signal detection.
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distributed fiber sparse wideband Vibration sensing by sub nyquist additive random sampling
arXiv: Instrumentation and Detectors, 2017Co-Authors: Jingdong Zhang, Hua Zheng, Tao Zhu, Guolu Yin, Min Liu, Yongzhong Bai, Feng Qiu, Xianbing HuangAbstract:The round trip time of the light pulse limits the maximum detectable Vibration Frequency response range of phase-sensitive optical time domain reflectometry ({\phi}-OTDR). Unlike the uniform laser pulse interval in conventional {\phi}-OTDR, we randomly modulate the pulse interval, so that an equivalent sub-Nyquist additive random sampling (sNARS) is realized for every sensing point of the long interrogation fiber. For an {\phi}-OTDR system with 10 km sensing length, the sNARS method is optimized by theoretical analysis and Monte Carlo simulation, and the experimental results verify that a wide-band spars signal can be identified and reconstructed. Such a method can broaden the Vibration Frequency response range of {\phi}-OTDR, which is of great significance in sparse-wideband-Frequency Vibration signal detection, such as rail track monitoring and metal defect detection.
