Zobrazeno 1 - 10
of 37
pro vyhledávání: '"Ryuichi Ichikawa"'
Autor:
Ryuichi Ichikawa, Hidekazu Hachisu, Mamoru Sekido, Tetsuya Ido, Yoshifumi Hiraoka, Eiichirou Harima, Shuntaro Fukaya, Masahiro Nakashima, Koji Matsuo, Yuichi Aoyama, Akihisa Hattori, Yoichi Fukuda
The frequency accuracy of optical atomic clocks has dramatically increased over the past 15 years, improving by more than two orders of magnitude from 16 digits of precision to 18 or even 19 digits of precision. Since around 2015 researchers from aro
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::16b5886435fef4b1a72a8535820b4ded
https://doi.org/10.5194/egusphere-egu23-2983
https://doi.org/10.5194/egusphere-egu23-2983
Autor:
Ryuichi Ichikawa, J. Roda, Tetsuya Ido, Masanori Tsutsumi, Federico Perini, Filippo Levi, Giuseppe Maccaferri, Filippo Bregolin, Giampaolo Zacchiroli, Roberto Ricci, Julia Leute, Jun-ichi Komuro, Tetsuro Kondo, Rumi Takahashi, Marco Pizzocaro, Mauro Roma, Monia Negusini, Hideki Ujihara, Eiji Kawai, Nils Nemitz, Davide Calonico, E. Cantoni, Giancarlo Cerretto, Yoshihiro Okamoto, Mamoru Sekido, Gérard Petit, K. Takefuji, Kunitaka Namba, Claudio Bortolotti, Piero Barbieri, Cecilia Clivati, Alberto Mura, H. Hachisu
Publikováno v:
Nature Physics. 17:223-227
The comparison of distant atomic clocks is foundational to international timekeeping, global positioning and tests of fundamental physics. Optical-fibre links allow the most precise optical clocks to be compared, without degradation, over intracontin
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::f8c1fbe5adcbfee4ac4b25fe71fd4595
https://doi.org/10.1038/s41567-020-01038-6
https://doi.org/10.1038/s41567-020-01038-6
Autor:
Tetsuya Ido, Masanori Tsutsumi, Kunitaka Namba, Tomonari Suzuyama, Mamoru Sekido, Ken-ichi Watabe, Mauro Roma, Ryuichi Ichikawa, Julia Leute, Jun-ichi Komuro, Marco Pizzocaro, Federico Perini, Giuseppe Maccaferri, Gérard Petit, K. Takefuji, Claudio Bortolotti, H. Hachisu, Hideki Ujihara, Tetsuro Kondo, Eiji Kawai, Davide Calonico, Roberto Ricci, Monia Negusini, Nils Nemitz, Cecilia Clivati
Publikováno v:
Journal of Geodesy
Journal of Geodesy, Springer Verlag, 2021, 95 (4), ⟨10.1007/s00190-021-01479-8⟩
Journal of Geodesy, Springer Verlag, 2021, 95 (4), ⟨10.1007/s00190-021-01479-8⟩
We have developed a broadband VLBI (very long baseline interferometry) system inspired by the concept of the VLBI Global Observing System (VGOS). The new broadband VLBI system was implemented in the Kashima 34 m antenna and in two transportable stati
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::6d8d052980792b6f3d6a26fe05b84aae
https://hal.sorbonne-universite.fr/hal-03200998/document
https://hal.sorbonne-universite.fr/hal-03200998/document
Publikováno v:
Proceedings of the 52nd Annual Precise Time and Time Interval Systems and Applications Meeting.
Space-Time Standards laboratory in National institute of Information and Communications Technology (NICT), Japan, has various activities of time and frequency metrology. NICT generates and disseminates Japan Standard Time (JST. In addition to the hea
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::a502ffc8e968925ca68bccfffcd243c6
https://doi.org/10.33012/2021.17800
https://doi.org/10.33012/2021.17800
Autor:
Filippo Levi, J. Roda, Masanori Tsutsumi, Roberto Ricci, Kunitaka Namba, Claudio Bortolotti, Hideki Ujihara, Rumi Takahashi, Hidekazu Hachisu, Mauro Roma, Piero Barbieri, Tetsuro Kondo, Kazuhiro Takefuji, Eiji Kawai, Cecilia Clivati, Mamoru Sekido, Jun-ichi Komuro, Davide Calonico, Giuseppe Maccaferri, Filippo Bregolin, Tetsuya Ido, Alberto Mura, Marco Pizzocaro, Yoshihiro Okamoto, Monia Negusini, Giancarlo Cerretto, Gérard Petit, Nils Nemitz, Giampaolo Zacchiroli, Julia Leute, Federico Perini, Ryuichi Ichikawa, E. Cantoni
Publikováno v:
Proceedings of the 52nd Annual Precise Time and Time Interval Systems and Applications Meeting.
For the aim to enable precise frequency transfer over earth radius scale distance, NICT developed a broadband VLBI system observing 3-14 GHz radio frequency range, and that was implemented in a pair of transportable 2.4m diameter VLBI stations and Ka
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::dbd760c1f752860373bd093768f73ef6
https://doi.org/10.33012/2021.17776
https://doi.org/10.33012/2021.17776
Autor:
Yusuke Yokota, Hiroshi Munekane, Koichiro Doi, Toshimichi Otsubo, Yoichi Fukuda, Ryuichi Ichikawa, Takayuki Miyazaki, Shun-ichi Watanabe, Basara Miyahara, Yuichi Aoyama, Takaaki Jike, Takehiro Matsumoto, Hiroshi Takiguchi, Shinobu Kurihara, Koji Matsuo
Since the establishment in 2013, GGOS Japan, formerly known as GGOS Working Group of Japan, has actively contributed to domestic and international space-geodetic activities. Until it was established, six Japanese agencies with their own backgrounds a
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::aa93657aa3caea1a64adce5b774c9f43
https://doi.org/10.5194/egusphere-egu2020-3244
https://doi.org/10.5194/egusphere-egu2020-3244
Autor:
Takeshi Matsushima, Basara Miyahara, Ryuichi Ichikawa, Takuya Tajiri, Hiroshi Munekane, Tatsuya Momotani, Osamu Tajima, Yusaku Ohta, Hideki Ujihara, Shinsuke Satoh, Nobuo Matsushima, Taketo Nagasaki, Kentaro Araki, Hiroshi Takiguchi, Kenji Utsunomiya
We have started to develop a next-generation microwave radiometer to be used in millimeter-wave spectroscopy for the high-resolution and high-precision monitoring of water vapor behavior. The new radiometer will be suitable for not only space geodeti
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::e66af6d5aea50fea171138e13f5fe8da
https://doi.org/10.5194/egusphere-egu2020-18305
https://doi.org/10.5194/egusphere-egu2020-18305
Autor:
Hiroshi Takiguchi, Osamu Tajima, Takuya Tajiri, Ryuichi Ichikawa, Taketo Nagasaki, Kentaro Araki
Publikováno v:
The International Technical Meeting of the The Institute of Navigation.
We have developed a state-of-the-art microwave radiometer named KUMODeS (KEK Universal Moisture and Oxygen Detection System) using millimeter-wave spectroscopy to monitor water vapor behavior. We have carried out comparative measurements of precipita
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::c4040be9f11917ff7747d289bde52673
https://doi.org/10.33012/2019.16716
https://doi.org/10.33012/2019.16716
Autor:
Filippo Levi, Claudio Bortolotti, Ryuichi Ichikawa, Marco Pizzocaro, Mamoru Sekido, Federico Perini, G. Cerretto, M. Tsusumi, Filippo Bregolin, Eiji Kawai, Giuseppe Maccaferri, Tetsuya Ido, Davide Calonico, H. Ishijima, Hideki Ujihara, Monia Negusini, Nils Nemitz, Alberto Mura, Roberto Ricci, H. Hachisu, K. Takefuji, Piero Barbieri, Cecilia Clivati, Mauro Roma
We performed a frequency comparison of lattice clocks in Tokyo and Torino for the first time using broadband VLBI technique. Two portable antennas with 2.4 m diameters were installed at NICT Koganei headquarters and INAF Medicina Radio Observatory, c
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::255f188c1bcc1076efe374d36a5af7f1
http://hdl.handle.net/11583/2761077
http://hdl.handle.net/11583/2761077
Publikováno v:
International Symposium on Advancing Geodesy in a Changing World ISBN: 9783030129149
Wideband antennas for VLBI have been under development in NICT Kashima and the status of the project was reported in the poster session. An aim of this wideband observing system is Time and Frequency Transfer, the comparison of atomic clocks separate
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::ded9ec0167c7a7a1e0618ac65c2d552c
https://doi.org/10.1007/1345_2018_41
https://doi.org/10.1007/1345_2018_41