The Experts below are selected from a list of 255 Experts worldwide ranked by ideXlab platform
A.a. Serafetinides - One of the best experts on this subject based on the ideXlab platform.
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XeCl laser ablation of biocompatible PTFE studied by photothermal beam deflection.
Lasers in Medical Science, 1997Co-Authors: Constantine Skordoulis, A. L. Bolovinos, Mersini I. Makropoulou, A.a. SerafetinidesAbstract:Laser beam deflection is a useful tool for studying the dynamics of the pulsed laser ablation mechanism, and has the advantage of being used as an in situ laser damage monitoring technique for both bulk and thin film polymeric and biological tissue samples. This work employs the photothermal deflection technique to study possible photo-Acoustic Phenomena during the excimer laser ablation of biocompatible polytetrafluoroethylene (PTFE) and to examine the crater surface quality by video microscopy.
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XeCl laser ablation of biocompatible PTFE studied by photothermal beam deflection
Lasers in Medical Science, 1997Co-Authors: Constantine Skordoulis, A. L. Bolovinos, Mersini I. Makropoulou, A.a. SerafetinidesAbstract:Laser beam deflection is a useful tool for studying the dynamics of the pulsed laser ablation mechanism, and has the advantage of being used as an in situ laser damage monitoring technique for both bulk and thin film polymeric and biological tissue samples. This work employs the photothermal deflection technique to study possible photo-Acoustic Phenomena during the excimer laser ablation of biocompatible polytetrafluoroethylene (PTFE) and to examine the crater surface quality by video microscopy. Although photo-Acoustic Phenomena are detected in the laser fluence threshold region, ablation is mainly the result of the photothermal process.
Constantine Skordoulis - One of the best experts on this subject based on the ideXlab platform.
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XeCl laser ablation of biocompatible PTFE studied by photothermal beam deflection.
Lasers in Medical Science, 1997Co-Authors: Constantine Skordoulis, A. L. Bolovinos, Mersini I. Makropoulou, A.a. SerafetinidesAbstract:Laser beam deflection is a useful tool for studying the dynamics of the pulsed laser ablation mechanism, and has the advantage of being used as an in situ laser damage monitoring technique for both bulk and thin film polymeric and biological tissue samples. This work employs the photothermal deflection technique to study possible photo-Acoustic Phenomena during the excimer laser ablation of biocompatible polytetrafluoroethylene (PTFE) and to examine the crater surface quality by video microscopy.
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XeCl laser ablation of biocompatible PTFE studied by photothermal beam deflection
Lasers in Medical Science, 1997Co-Authors: Constantine Skordoulis, A. L. Bolovinos, Mersini I. Makropoulou, A.a. SerafetinidesAbstract:Laser beam deflection is a useful tool for studying the dynamics of the pulsed laser ablation mechanism, and has the advantage of being used as an in situ laser damage monitoring technique for both bulk and thin film polymeric and biological tissue samples. This work employs the photothermal deflection technique to study possible photo-Acoustic Phenomena during the excimer laser ablation of biocompatible polytetrafluoroethylene (PTFE) and to examine the crater surface quality by video microscopy. Although photo-Acoustic Phenomena are detected in the laser fluence threshold region, ablation is mainly the result of the photothermal process.
Seiji Tsutsumi - One of the best experts on this subject based on the ideXlab platform.
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experimental study of plate angle effects on Acoustic Phenomena from a supersonic jet impinging on an inclined flat plate
Journal of the Acoustical Society of America, 2017Co-Authors: Masahito Akamine, Koji Okamoto, Susumu Teramoto, Seiji TsutsumiAbstract:Acoustic waves from a rocket exhaust jet cause the intense Acoustic loading. Because the exhaust jet impinges on a flame deflector at liftoff of a launch vehicle, an adequate understanding of the Acoustic Phenomena from a supersonic impinging jet is required for prediction and reduction of the level of the Acoustic loading. The previous numerical studies on a supersonic jet impinging on an inclined flat plate [e.g., Tsutsumi et al. AIAA 2014-0882; Nonomura et al. AIAA J. 54(3), 816-827 (2016)] suggested that the plate angle has a large impact on the characteristics of the Acoustic waves from the impingement region. In the present study, experiments were carried out to discuss the effect of the plate angle on this Acoustic phenomenon. By applying the Acoustic-triggered conditional sampling to the schlieren visualization movies, which was proposed by the authors [AIAA 2016-2930], the Phenomena around the impingement region were observed in detail. The results revealed that the plate-angle variation leads to...
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effect of nozzle plate distance on Acoustic Phenomena from supersonic impinging jet
AIAA CEAS Aeroacoustics Conference, 2016Co-Authors: Masahito Akamine, Koji Okamoto, Susumu Teramoto, Tracianne B Neilsen, Takeo Okunuki, Seiji TsutsumiAbstract:For an adequate understanding of the broadband Acoustic Phenomena generated by a rocket exhaust jet impinging on a flame deflector, this study experimentally clarifies the factors that cause the di...
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Effect of Nozzle–Plate Distance on Acoustic Phenomena from Supersonic Impinging Jet
AIAA Journal, 2016Co-Authors: Masahito Akamine, Koji Okamoto, Susumu Teramoto, Tracianne B Neilsen, Takeo Okunuki, Seiji TsutsumiAbstract:For an adequate understanding of the broadband Acoustic Phenomena generated by a rocket exhaust jet impinging on a flame deflector, this study experimentally clarifies the factors that cause the di...
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Acoustic Phenomena from correctly expanded supersonic jet impinging on inclined plate
AIAA Journal, 2015Co-Authors: Masahito Akamine, Koji Okamoto, Susumu Teramoto, Takeo Okunuki, Yuta Nakanishi, Seiji TsutsumiAbstract:PAYLOAD vibration due to Acoustic waves from the exhaust plume is a significant problem during the liftoff of a launch vehicle. These Acoustic waves are considered to be caused by jet impingement on the ground or on the flame deflector at the launch pad, as well as being from the free jet region. The ground slope or flame deflector profiles are therefore considered to affect the intensity and characteristics of this Acoustic phenomenon, but design principles to suppress Acoustic wave generation have not yet been established, because the generation mechanisms of the Acoustic waves from the jet impingement have not been sufficiently clarified. Therefore, this study investigates the Acoustic Phenomena from a correctly expanded supersonic jet impinging on an inclined flat plate, through experiments conducted using a jet facility. The flow field of a supersonic jet impinging on a solid surface has been examined in many previous studies. For example, the fundamental flow structure was described by Donaldson and Snedecker [1]. From their experiments using an underexpanded jet impinging on a perpendicular or inclined plate at various angles, the flow structure was explained as being composed of three regions with different flow regimes: the free jet, impingement, and wall jet regions. The free jet region is minimally affected by the jet impingement, and its flow structure is similar to that of a free jet, as regard the potential core and supersonic shear layers. Next, the jet impinges on the plate, yielding a recirculation flow in the impingement region while, finally, the jet flows along the plate surface in the wall jet region. Carling and Hunt [2] experimentally discussed the flow field of a correctly expanded jet impinging on a perpendicular plate, and observed a series of expansion, recompression, and, in some cases, shock waves on the plate surface. As for an underexpanded jet impinging on an inclined plate, complicated shock structure in the impingement regionwas observed in the experiments of Lamont and Hunt [3], and in the calculations of Kim and Chang [4]. This structure is composed of plate shocks (i.e., standoff shocks) with additional tail shocks around the plate shocks. Nakai et al. [5] experimentally classified this structure into four types under various plate angle, nozzle–plate distance, and pressure ratio conditions. Moreover, a detailed numerical description of this shock structure was given by McIlroy and Fujii [6]. As for the investigation of the related Acoustic Phenomena, most previous studies have focused on discrete tone noise. The Acoustic characteristics and the related perpendicular jet impingement flow Phenomena were discussed in experimental studies (e.g., [7,8]) and recent numerical works (e.g., [9,10]), while, also, Risborg and Soria [11] discussed the Acoustic feedback loop of an underexpanded jet impinging on an inclined plate by visualizing Acoustic waves. As for studies on the Acoustic Phenomena from a correctly expanded supersonic jet impinging on an inclined plate, the subject that is examined in the present study, several numerical reports can be found, such as [12–14]. These studies were conducted to investigate the Acoustic Phenomena during the liftoff of a launch vehicle, and also discussed the Acoustic and flow fields, which contain complex shock structures in the impingement region. In particular, the results of these studies revealed that there exist two types of Acoustic waves: the Mach waves from the supersonic turbulent wall jet, and the Acoustic waves propagating in an approximately perpendicular direction to the plate. The Acoustic field under various impingement conditions was also calculated by Nonomura et al. [14] and Honda et al. [15] but, on the other hand, only [16] can be found as an experimental study of these Phenomena. They measured noise from Mj 1.5 correctly expanded jets impinging on inclined plates at two fixed locations, mainly focusing on the noise environment of an aircraft carrier deck. They successfully revealed the influence of the nozzle–plate distance and the jet temperature on the sound pressure level (SPL), whereas they also noted that further investigations, such as spatial distribution of SPL, localization of the source region, and optical measurements, may be useful to fully characterize the Acoustic and flow properties. As described above, these Acoustic Phenomena have been investigated numerically in detail, but discussion based on experimental data is currently lacking. Detailed experimental results are indispensable to a discussion of Acoustic Phenomena, because a limitation in the frequency range of the spectra obtained by numerical analyses exists. Therefore, the objective of the present study is to study the characteristics of the Acoustic waves from a correctly expanded supersonic jet impinging on the inclined plate experimentally. To achieve this, the Acoustic waves from the impinging jet are measured using a microphone at a jet facility. The waves are then visualized using the schlieren method, and their propagation directions, spectra, and the extent of the source region are discussed in this study.After an evaluation of the accuracy of the SPLmeasurement and confirmation of the jet profile (described in Sec. II.D.), an overview of the Acoustic field based on the results of the SPL measurements and schlieren visualization is presented inSec. III.A. Then, the spectra of the Acoustic waves are discussed in Sec. III.B. Finally, the extent of the source region of the Acoustic waves is discussed using the SPL distributions and a schlieren visualization movie analysis, in Sec. III.C. Received 26 September 2014; revision received 4 November 2014; accepted for publication4November 2014; published online 28 January 2015. Copyright© 2014byMasahitoAkamine. Published by theAmerican Institute of Aeronautics and Astronautics, Inc., with permission. Copies of this paper may be made for personal or internal use, on condition that the copier pay the $10.00 per-copy fee to the Copyright Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA 01923; include the code 1533-385X/15 and $10.00 in correspondence with the CCC. *Graduate Student, Department of Advanced Energy. Student Member AIAA. Ph.D. Student, Department of Advanced Energy; currently at IHI Corporation. Associate Professor, Department of Advanced Energy. Member AIAA. Associate Professor, Department of Aeronautics and Astronautics. Senior Member AIAA. Senior Engineer, Department of Aeronautics and Astronautics. **Engineer, JAXA’s Engineering Digital Innovation (JEDI) Center. Member AIAA.
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experimental study on Acoustic Phenomena of supersonic jet impinging on inclined flat plate
52nd Aerospace Sciences Meeting, 2014Co-Authors: Masahito Akamine, Koji Okamoto, Susumu Teramoto, Takeo Okunuki, Yuta Nakanishi, Seiji TsutsumiAbstract:Acoustic and flow fields of a Mj = 1.8 correctly-expanded jet impinging on a 45○ inclined flat plate are investigated experimentally. In the experiments, microphone measurement, Schlieren visualization, and wall static pressure measurement on the inclined plate surface are conducted for different nozzle-plate distances. When the nozzle-plate distance is 5D, two types of Acoustic waves, whose characteristics are different in propagation directions, spectra, and source locations, are observed. One propagates in the 30○ direction from the inclined plate surface, and the other propagates in the 75○ direction. When the nozzleplate distance is varied, the change of the intensities of those two types of Acoustic waves is observed, and the correlation between the Acoustic waves and the shock structures of the flow field is discussed.
Y. Miida - One of the best experts on this subject based on the ideXlab platform.
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ICCE - Web-based multimedia teaching materials for Acoustic science
International Conference on Computers in Education 2002. Proceedings., 2002Co-Authors: M. Uchimura, H. Suda, Y. MiidaAbstract:In the education of Acoustic science, it is important how the student imagines the appearances of actual Acoustic Phenomena. So, for teachers, it is an important problem as how to model the Acoustic Phenomena and to provide them to students. It cannot be seen by the eye though sounds are familiar as the Phenomena. It is this which hinders students from studying Acoustic science. Therefore it is worthy for the education of the Acoustic science that ties theories to Phenomena by simulating Acoustic Phenomena, and modeling as animations or synthetic sounds on a computer. The past multimedia teaching materials, which we made, have been hard to distribute. We are developing Web based multimedia teaching materials. They include presentation slides, simulation programs, movies, and so on. In this paper, we introduce web based multimedia teaching materials, and report the experimental effects of them.
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Web-based multimedia teaching materials for Acoustic science
International Conference on Computers in Education 2002. Proceedings., 2002Co-Authors: M. Uchimura, H. Suda, Y. MiidaAbstract:In the education of Acoustic science, it is important how the student imagines the appearances of actual Acoustic Phenomena. So, for teachers, it is an important problem as how to model the Acoustic Phenomena and to provide them to students. It cannot be seen by the eye though sounds are familiar as the Phenomena. It is this which hinders students from studying Acoustic science. Therefore it is worthy for the education of the Acoustic science that ties theories to Phenomena by simulating Acoustic Phenomena, and modeling as animations or synthetic sounds on a computer. The past multimedia teaching materials, which we made, have been hard to distribute. We are developing Web based multimedia teaching materials. They include presentation slides, simulation programs, movies, and so on. In this paper, we introduce web based multimedia teaching materials, and report the experimental effects of them.
Susumu Teramoto - One of the best experts on this subject based on the ideXlab platform.
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visualization and Acoustic triggered conditional sampling analysis of Acoustic Phenomena with screech tone of an over expanded supersonic jet
Journal of the Acoustical Society of America, 2019Co-Authors: Miho Takemura, Koji Okamoto, Susumu TeramotoAbstract:In the liftoff of launch vehicles and supersonic aircrafts, jet noise is required to be reduced because it causes various problems. To reduce the influence of jet noise, it is significant to clarify the source location and the direction of propagation as well as the spectrum of each Acoustic phenomenon. For this purpose, the authors have proposed the Acoustic-triggered conditional sampling analysis to obtain Acoustic information from high-speed schlieren movies. In the authors’ previous studies, this method was applied to correctly and under expanded jets, and the broadband Phenomena were clarified, such as Mach wave radiation and shock associated noise. In this study, this method was applied to an over-expanded jet, in which screech tone is observed in addition to the broadband Acoustic Phenomena. First, it was found that the broadband Phenomena and screech tone could be observed separately by this method with choosing the microphone location for trigger detection. Then, two screech tone noises of different frequencies are observed, and it was clarified that they are propagating to different directions from different source locations. Also, the Acoustic phenomenon generated by impingement of the same over-expanded jet on an inclined flat plate will be discussed.In the liftoff of launch vehicles and supersonic aircrafts, jet noise is required to be reduced because it causes various problems. To reduce the influence of jet noise, it is significant to clarify the source location and the direction of propagation as well as the spectrum of each Acoustic phenomenon. For this purpose, the authors have proposed the Acoustic-triggered conditional sampling analysis to obtain Acoustic information from high-speed schlieren movies. In the authors’ previous studies, this method was applied to correctly and under expanded jets, and the broadband Phenomena were clarified, such as Mach wave radiation and shock associated noise. In this study, this method was applied to an over-expanded jet, in which screech tone is observed in addition to the broadband Acoustic Phenomena. First, it was found that the broadband Phenomena and screech tone could be observed separately by this method with choosing the microphone location for trigger detection. Then, two screech tone noises of differ...
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visualization of Acoustic Phenomena of imperfectly expanded supersonic jets using Acoustic triggered conditional sampling analysis
Journal of the Acoustical Society of America, 2018Co-Authors: Yuya Sekiguchi, Koji Okamoto, Susumu TeramotoAbstract:For rockets and supersonic aircrafts, Acoustic waves from an exhaust jet cause problems of vibration and noise. To reduce the influence of Acoustic waves effectively, it is important to reveal characteristics of Acoustic Phenomena, such as source locations and the relation between the flow and Acoustic Phenomena. For this purpose, the authors carried out visualization of Acoustic field of a correctly expanded supersonic jet in the previous studies, and proposed the Acoustic-triggered conditional sampling analysis to obtain Acoustic information from high speed schlieren movies. This method is also expected to be applied to other jet Acoustic Phenomena. In this study, this method is applied to imperfectly expanded supersonic jets and the relation between the flow and Acoustic Phenomena will be discussed.For rockets and supersonic aircrafts, Acoustic waves from an exhaust jet cause problems of vibration and noise. To reduce the influence of Acoustic waves effectively, it is important to reveal characteristics of Acoustic Phenomena, such as source locations and the relation between the flow and Acoustic Phenomena. For this purpose, the authors carried out visualization of Acoustic field of a correctly expanded supersonic jet in the previous studies, and proposed the Acoustic-triggered conditional sampling analysis to obtain Acoustic information from high speed schlieren movies. This method is also expected to be applied to other jet Acoustic Phenomena. In this study, this method is applied to imperfectly expanded supersonic jets and the relation between the flow and Acoustic Phenomena will be discussed.
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experimental study of plate angle effects on Acoustic Phenomena from a supersonic jet impinging on an inclined flat plate
Journal of the Acoustical Society of America, 2017Co-Authors: Masahito Akamine, Koji Okamoto, Susumu Teramoto, Seiji TsutsumiAbstract:Acoustic waves from a rocket exhaust jet cause the intense Acoustic loading. Because the exhaust jet impinges on a flame deflector at liftoff of a launch vehicle, an adequate understanding of the Acoustic Phenomena from a supersonic impinging jet is required for prediction and reduction of the level of the Acoustic loading. The previous numerical studies on a supersonic jet impinging on an inclined flat plate [e.g., Tsutsumi et al. AIAA 2014-0882; Nonomura et al. AIAA J. 54(3), 816-827 (2016)] suggested that the plate angle has a large impact on the characteristics of the Acoustic waves from the impingement region. In the present study, experiments were carried out to discuss the effect of the plate angle on this Acoustic phenomenon. By applying the Acoustic-triggered conditional sampling to the schlieren visualization movies, which was proposed by the authors [AIAA 2016-2930], the Phenomena around the impingement region were observed in detail. The results revealed that the plate-angle variation leads to...
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effect of nozzle plate distance on Acoustic Phenomena from supersonic impinging jet
AIAA CEAS Aeroacoustics Conference, 2016Co-Authors: Masahito Akamine, Koji Okamoto, Susumu Teramoto, Tracianne B Neilsen, Takeo Okunuki, Seiji TsutsumiAbstract:For an adequate understanding of the broadband Acoustic Phenomena generated by a rocket exhaust jet impinging on a flame deflector, this study experimentally clarifies the factors that cause the di...
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Effect of Nozzle–Plate Distance on Acoustic Phenomena from Supersonic Impinging Jet
AIAA Journal, 2016Co-Authors: Masahito Akamine, Koji Okamoto, Susumu Teramoto, Tracianne B Neilsen, Takeo Okunuki, Seiji TsutsumiAbstract:For an adequate understanding of the broadband Acoustic Phenomena generated by a rocket exhaust jet impinging on a flame deflector, this study experimentally clarifies the factors that cause the di...
