The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform
Akira Nakashima - One of the best experts on this subject based on the ideXlab platform.
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an online estimation of Rotational Velocity of flying ball via aerodynamics
IFAC Proceedings Volumes, 2014Co-Authors: Akira Nakashima, Takeshi Okamoto, Yoshikazu HayakawaAbstract:Abstract We propose a novel estimation method of the Rotational Velocity of a flying ball as well as its position and translational Velocity via aerodynamics model by measuring the ball trajectory using the middle speed cameras for table tennis system. The aerodynamics model is complex nonlinear and the measured data of the ball trajectory has quantization errors because the size of the ball is very small in the field of view of the middle speed cameras. Then, we consider the estimation by minimizing the difference between the trajectories which are measured by the cameras and numerically solved by integrating the aerodynamics model respectively. Since the difference is not analytical function, the minimization is solved by the downhill simplex method, where some modification is introduced for improving the converge speed. The effectiveness of the method is verified by numerical simulations.
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A registration algorithm for on-line measuring the Rotational Velocity of a table tennis ball
2011 IEEE International Conference on Robotics and Biomimetics, 2011Co-Authors: Chunfang Liu, Yoshikazu Hayakawa, Akira NakashimaAbstract:We propose a registration algorithm for on-line measuring the Rotational Velocity of a table tennis ball in which the nearest neighbor interpolation method is presented to estimate the intensities of the pixels on the later frame by using the information of the previous frame. The conjugate gradient method is used to seek the optimum of the Rotational parameter. Experimental results with both a ball rotated by a Rotational machine and a flying ball shot from a catapult machine sufficiently demonstrate the effectiveness of the proposed method.
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ROBIO - A registration algorithm for on-line measuring the Rotational Velocity of a table tennis ball
2011 IEEE International Conference on Robotics and Biomimetics, 2011Co-Authors: Chunfang Liu, Yoshikazu Hayakawa, Akira NakashimaAbstract:We propose a registration algorithm for on-line measuring the Rotational Velocity of a table tennis ball in which the nearest neighbor interpolation method is presented to estimate the intensities of the pixels on the later frame by using the information of the previous frame. The conjugate gradient method is used to seek the optimum of the Rotational parameter. Experimental results with both a ball rotated by a Rotational machine and a flying ball shot from a catapult machine sufficiently demonstrate the effectiveness of the proposed method.
Douglas R Gies - One of the best experts on this subject based on the ideXlab platform.
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stellar rotation in young clusters i evolution of projected Rotational Velocity distributions
The Astrophysical Journal, 2006Co-Authors: Wenjin Huang, Douglas R GiesAbstract:Open clusters offer us the means to study stellar properties in samples with well-defined ages and initial chemical composition. Here we present a survey of projected Rotational velocities for a large sample of mainly B-type stars in young clusters to study the time evolution of the Rotational properties of massive stars. The survey is based on moderate-resolution spectra made with the WIYN 3.5 m and CTIO 4 m telescopes and Hydra multi-object spectrographs, and the target stars are members of 19 young open clusters with an age range of approximately 6-73 Myr. We made fits of the observed lines He I λλ4026, 4387, 4471, and Mg II λ4481, using model theoretical profiles to find projected Rotational velocities for a total of 496 OB stars. We find that there are fewer slow rotators among the cluster B-type stars relative to nearby B stars in the field. We present evidence consistent with the idea that the more massive B stars (M > 9 M☉) spin down during their main-sequence phase. However, we also find that the Rotational Velocity distribution appears to show an increase in the numbers of rapid rotators among clusters with ages of 10 Myr and higher. These rapid rotators appear to be distributed between the zero age and terminal age main-sequence locations in the Hertzsprung-Russell diagram, and thus only a minority of them can be explained as the result of a spin-up at the terminal age main sequence due to core contraction. We suggest instead that some of these rapid rotators may have been spun up through mass transfer in close binary systems.
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stellar rotation in young clusters i evolution of projected Rotational Velocity distributions
arXiv: Astrophysics, 2005Co-Authors: Wenjin Huang, Douglas R GiesAbstract:Open clusters offer us the means to study stellar properties in samples with well-defined ages and initial chemical composition. Here we present a survey of projected Rotational velocities for a large sample of mainly B-type stars in young clusters to study the time evolution of the Rotational properties of massive stars. The survey is based upon moderate resolution spectra made with the WIYN 3.5 m and CTIO 4 m telescopes and Hydra multi-object spectrographs, and the target stars are members of 19 young open clusters with an age range of approximately 6 to 73 Myr. We made fits of the observed lines He I 4026, 4387, 4471 and Mg II 4481 using model theoretical profiles to find projected Rotational velocities for a total of 496 OB stars. We find that there are fewer slow rotators among the cluster B-type stars relative to nearby B stars in the field. We present evidence consistent with the idea that the more massive B stars (M > 9 solar masses) spin down during their main sequence phase. However, we also find that the Rotational Velocity distribution appears to show an increase in the numbers of rapid rotators among clusters with ages of 10 Myr and higher. These rapid rotators appear to be distributed between the zero age and terminal age main sequence locations in the Hertzsprung-Russell diagram, and thus only a minority of them can be explained as the result of a spin up at the terminal age main sequence due to core contraction. We suggest instead that some of these rapid rotators may have been spun up through mass transfer in close binary systems.
Chunfang Liu - One of the best experts on this subject based on the ideXlab platform.
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A registration algorithm for on-line measuring the Rotational Velocity of a table tennis ball
2011 IEEE International Conference on Robotics and Biomimetics, 2011Co-Authors: Chunfang Liu, Yoshikazu Hayakawa, Akira NakashimaAbstract:We propose a registration algorithm for on-line measuring the Rotational Velocity of a table tennis ball in which the nearest neighbor interpolation method is presented to estimate the intensities of the pixels on the later frame by using the information of the previous frame. The conjugate gradient method is used to seek the optimum of the Rotational parameter. Experimental results with both a ball rotated by a Rotational machine and a flying ball shot from a catapult machine sufficiently demonstrate the effectiveness of the proposed method.
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ROBIO - A registration algorithm for on-line measuring the Rotational Velocity of a table tennis ball
2011 IEEE International Conference on Robotics and Biomimetics, 2011Co-Authors: Chunfang Liu, Yoshikazu Hayakawa, Akira NakashimaAbstract:We propose a registration algorithm for on-line measuring the Rotational Velocity of a table tennis ball in which the nearest neighbor interpolation method is presented to estimate the intensities of the pixels on the later frame by using the information of the previous frame. The conjugate gradient method is used to seek the optimum of the Rotational parameter. Experimental results with both a ball rotated by a Rotational machine and a flying ball shot from a catapult machine sufficiently demonstrate the effectiveness of the proposed method.
Wenjin Huang - One of the best experts on this subject based on the ideXlab platform.
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stellar rotation in young clusters i evolution of projected Rotational Velocity distributions
The Astrophysical Journal, 2006Co-Authors: Wenjin Huang, Douglas R GiesAbstract:Open clusters offer us the means to study stellar properties in samples with well-defined ages and initial chemical composition. Here we present a survey of projected Rotational velocities for a large sample of mainly B-type stars in young clusters to study the time evolution of the Rotational properties of massive stars. The survey is based on moderate-resolution spectra made with the WIYN 3.5 m and CTIO 4 m telescopes and Hydra multi-object spectrographs, and the target stars are members of 19 young open clusters with an age range of approximately 6-73 Myr. We made fits of the observed lines He I λλ4026, 4387, 4471, and Mg II λ4481, using model theoretical profiles to find projected Rotational velocities for a total of 496 OB stars. We find that there are fewer slow rotators among the cluster B-type stars relative to nearby B stars in the field. We present evidence consistent with the idea that the more massive B stars (M > 9 M☉) spin down during their main-sequence phase. However, we also find that the Rotational Velocity distribution appears to show an increase in the numbers of rapid rotators among clusters with ages of 10 Myr and higher. These rapid rotators appear to be distributed between the zero age and terminal age main-sequence locations in the Hertzsprung-Russell diagram, and thus only a minority of them can be explained as the result of a spin-up at the terminal age main sequence due to core contraction. We suggest instead that some of these rapid rotators may have been spun up through mass transfer in close binary systems.
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stellar rotation in young clusters i evolution of projected Rotational Velocity distributions
arXiv: Astrophysics, 2005Co-Authors: Wenjin Huang, Douglas R GiesAbstract:Open clusters offer us the means to study stellar properties in samples with well-defined ages and initial chemical composition. Here we present a survey of projected Rotational velocities for a large sample of mainly B-type stars in young clusters to study the time evolution of the Rotational properties of massive stars. The survey is based upon moderate resolution spectra made with the WIYN 3.5 m and CTIO 4 m telescopes and Hydra multi-object spectrographs, and the target stars are members of 19 young open clusters with an age range of approximately 6 to 73 Myr. We made fits of the observed lines He I 4026, 4387, 4471 and Mg II 4481 using model theoretical profiles to find projected Rotational velocities for a total of 496 OB stars. We find that there are fewer slow rotators among the cluster B-type stars relative to nearby B stars in the field. We present evidence consistent with the idea that the more massive B stars (M > 9 solar masses) spin down during their main sequence phase. However, we also find that the Rotational Velocity distribution appears to show an increase in the numbers of rapid rotators among clusters with ages of 10 Myr and higher. These rapid rotators appear to be distributed between the zero age and terminal age main sequence locations in the Hertzsprung-Russell diagram, and thus only a minority of them can be explained as the result of a spin up at the terminal age main sequence due to core contraction. We suggest instead that some of these rapid rotators may have been spun up through mass transfer in close binary systems.
Yoshikazu Hayakawa - One of the best experts on this subject based on the ideXlab platform.
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an online estimation of Rotational Velocity of flying ball via aerodynamics
IFAC Proceedings Volumes, 2014Co-Authors: Akira Nakashima, Takeshi Okamoto, Yoshikazu HayakawaAbstract:Abstract We propose a novel estimation method of the Rotational Velocity of a flying ball as well as its position and translational Velocity via aerodynamics model by measuring the ball trajectory using the middle speed cameras for table tennis system. The aerodynamics model is complex nonlinear and the measured data of the ball trajectory has quantization errors because the size of the ball is very small in the field of view of the middle speed cameras. Then, we consider the estimation by minimizing the difference between the trajectories which are measured by the cameras and numerically solved by integrating the aerodynamics model respectively. Since the difference is not analytical function, the minimization is solved by the downhill simplex method, where some modification is introduced for improving the converge speed. The effectiveness of the method is verified by numerical simulations.
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A registration algorithm for on-line measuring the Rotational Velocity of a table tennis ball
2011 IEEE International Conference on Robotics and Biomimetics, 2011Co-Authors: Chunfang Liu, Yoshikazu Hayakawa, Akira NakashimaAbstract:We propose a registration algorithm for on-line measuring the Rotational Velocity of a table tennis ball in which the nearest neighbor interpolation method is presented to estimate the intensities of the pixels on the later frame by using the information of the previous frame. The conjugate gradient method is used to seek the optimum of the Rotational parameter. Experimental results with both a ball rotated by a Rotational machine and a flying ball shot from a catapult machine sufficiently demonstrate the effectiveness of the proposed method.
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ROBIO - A registration algorithm for on-line measuring the Rotational Velocity of a table tennis ball
2011 IEEE International Conference on Robotics and Biomimetics, 2011Co-Authors: Chunfang Liu, Yoshikazu Hayakawa, Akira NakashimaAbstract:We propose a registration algorithm for on-line measuring the Rotational Velocity of a table tennis ball in which the nearest neighbor interpolation method is presented to estimate the intensities of the pixels on the later frame by using the information of the previous frame. The conjugate gradient method is used to seek the optimum of the Rotational parameter. Experimental results with both a ball rotated by a Rotational machine and a flying ball shot from a catapult machine sufficiently demonstrate the effectiveness of the proposed method.
