- 著者
- Yuta Katori Kan Okubo
- 出版者
- The Institute of Electronics, Information and Communication Engineers
- 雑誌
- IEICE Communications Express (ISSN:21870136)
- 巻号頁・発行日
- vol.7, no.10, pp.352-357, 2018 (Released:2018-10-01)
- 参考文献数
- 12
- 被引用文献数
- 2
For years, researchers have been studying the relation between earthquakes and geomagnetic field signals using observation results. Following our continuous geomagnetic observation, this report describes geomagnetic signal changes generated by earthquakes and tsunami waves. Results show that detection of their occurrence using geomagnetic field measurement is effective for providing an early alarm system for disaster mitigation. Robust detection requires the robust estimation of a geomagnetic field using multiple observation results. This study introduced a deep neural network (DNN) to estimate geomagnetic fields. Results clarified that the proposed DNN model using data of multiple axes at multiple observation points as input data provides efficient solutions for geomagnetic estimation.
- 著者
- Tomokazu Okugi Kan Okubo
- 出版者
- The Institute of Electronics, Information and Communication Engineers
- 雑誌
- IEICE Communications Express (ISSN:21870136)
- 巻号頁・発行日
- vol.11, no.4, pp.165-170, 2022-04-01 (Released:2022-04-01)
- 参考文献数
- 6
- 被引用文献数
- 1
The propagation analysis of an automotive radar using the finite-difference time-domain (FDTD) method uses tens of billions of analysis cells, and the simulation time is several days to several weeks. This study developed a method of accelerating the FDTD simulation for automotive radar analysis using a cluster-type supercomputer with multiple GPUs. An analysis region was divided into blocks, which were allocated to GPUs. The start time of the operation of each GPU was controlled according to radio wave propagation from a radiation antenna. The proposed method reduced the total simulation time by approximately 34% compared to a conventional method.
- 著者
- Yuta Katori Shinji Isogami Tsunehiro Hato Akira Tsukamoto Keiichi Tanabe Nobuhito Ohnishi Chikara Furukawa Kan Okubo
- 出版者
- The Institute of Electronics, Information and Communication Engineers
- 雑誌
- IEICE Communications Express (ISSN:21870136)
- 巻号頁・発行日
- vol.7, no.3, pp.71-76, 2018 (Released:2018-03-01)
- 参考文献数
- 9
- 被引用文献数
- 1
Our research group reported successful observation of “co-faulting” Earth’s magnetic field changes because of piezomagnetic effects caused by earthquake tremors during the 2008 Iwate-Miyagi Nairiku earthquake of M7.2 using a geomagnetic observation system with flux-gate magnetometers. This is an important finding: electromagnetic fields propagate from a source to an observation site at the light speed in the crustal materials. Further earthquake detection efforts can lead us to a new system for super-early warning of earthquake detection with the geomagnetic signal. However, the observed result with the earthquake was suggested that the geomagnetic field change accompanying fault movement, whose sources are the piezomagnetic effects, is very small and short term. Therefore, to develop an extremely important high-resolution magnetometer system, we first conducted long-term precise geomagnetic observations using a high-temperature superconductor based superconducting quantum-interference device (HTS-SQUID) magnetometer system. The HTS-SQUID magnetometer system had never been used for high-resolution geomagnetic observations outdoors. Since March 2012, we have observed geomagnetic field using the HTS-SQUID magnetometer at Iwaki observation site (IWK) in Fukushima, Japan. Comparison between the introduced HTS-SQUID magnetometer and conventional flux-gate clarified that the HTS-SQUID magnetometer in our system has higher resolution of magnetic field observation.