9:00 AM - 9:15 AM
[STT35-01] Technological innovation of accelerometers with applications to seismometers
Keywords:accelerometry, velocimetry, seismometers, regularization, GNSS, waveform reconstruction of acceleration and velocity
Seismology is built on three basic disciplines: mathematics, physics and instrumentation. It is certainly true that any interpretations of earthquakes without a master knowledge on mathematics and physics do not make sense but could be nothing more than a story. On the other hand, data used to study the natural phenomena of earthquakes has to depend on seismic instrumentation. In this talk, we will focus on the most fundamental component of instruments for seismometers, namely, accelerometers. Since the first accelerometer was made around 1923 in America and the first strong motion seismometer was produced in 1933 by the National Coast and Geodetic Survey of the US, huge advance in hardware technology has been achieved, with a great number of patents on accelerometers worldwide, in particular, from Japan, the USA and Europe.
Unfortunately, there still exist a number of critical technological problems with accelerometry, which can be summarized as follows:
[1] with the increase of sampling rate, accelerations look like going up and down randomly and with an extremely large amplitude, depending on the noise of the original measurements. In other words, accelerations look like random noise. This phenomenon should be totally unacceptable physically. More precisely, the data from an accelerometer are not physical accelerations but totally random. One of such examples from a strong motion seismometer is shown in Fig. 1 (see Fig. 3 of Xu et al. 2021) in association with the 2013 Lushan Mw6.3 earthquake;
[2] if the sampling rate is sufficiently low, velocity and acceleration signals are distorted, the extent of which depend on that specific rate of sampling; and
[3] no velocimeters and accelerometers can produce correct and physically meaningful values of instantaneous velocity and acceleration for a moving object,
according to the recent patent application on accelerometry by Xu (2021). The same can be said about velocimetry, as also documented in Xu (2021).
In this talk, we will present a regularization method to compute velocity and acceleration and its apparatus, which have been shown to successfully solve the critical technological problems mentioned in the above and documented in the recent research paper by Xu et al. (2021) and a patent application under review by Xu (2021). Our patented research has shown that current technology of accelerometers can result in incorrect values of acceleration by a factor of several hundreds to thousands in terms of peak ground acceleration (PGA), depending on the noise level of the original measurements of accelerometers. An example is shown in Fig. 2 (see also Figs. 2 and 9 of Xu (2021) and Fig. 8 of Xu et al. (2021)). As a result of these researches, we expect a technological revolution in velocimetry and accelerometry. As a by-product or as a direct application of our research, seismometers expect an immediate technological innovation as well to produce physically meaningful raw data of velocity and/or acceleration.
P Xu, F Du, Y Shu, H Zhang, Y Shi (2021) Regularized reconstruction of peak ground velocity and acceleration from very high-rate GNSS precise point positioning with applications to the 2013 Lushan Mw6. 6 earthquake.
Journal of Geodesy 95, article number 17, doi.org/10.1007/s00190-020-01449-6
P Xu (2021) A regularization method to compute velocity and acceleration and its apparatus. Patent submitted on 13 Jan 2021
Unfortunately, there still exist a number of critical technological problems with accelerometry, which can be summarized as follows:
[1] with the increase of sampling rate, accelerations look like going up and down randomly and with an extremely large amplitude, depending on the noise of the original measurements. In other words, accelerations look like random noise. This phenomenon should be totally unacceptable physically. More precisely, the data from an accelerometer are not physical accelerations but totally random. One of such examples from a strong motion seismometer is shown in Fig. 1 (see Fig. 3 of Xu et al. 2021) in association with the 2013 Lushan Mw6.3 earthquake;
[2] if the sampling rate is sufficiently low, velocity and acceleration signals are distorted, the extent of which depend on that specific rate of sampling; and
[3] no velocimeters and accelerometers can produce correct and physically meaningful values of instantaneous velocity and acceleration for a moving object,
according to the recent patent application on accelerometry by Xu (2021). The same can be said about velocimetry, as also documented in Xu (2021).
In this talk, we will present a regularization method to compute velocity and acceleration and its apparatus, which have been shown to successfully solve the critical technological problems mentioned in the above and documented in the recent research paper by Xu et al. (2021) and a patent application under review by Xu (2021). Our patented research has shown that current technology of accelerometers can result in incorrect values of acceleration by a factor of several hundreds to thousands in terms of peak ground acceleration (PGA), depending on the noise level of the original measurements of accelerometers. An example is shown in Fig. 2 (see also Figs. 2 and 9 of Xu (2021) and Fig. 8 of Xu et al. (2021)). As a result of these researches, we expect a technological revolution in velocimetry and accelerometry. As a by-product or as a direct application of our research, seismometers expect an immediate technological innovation as well to produce physically meaningful raw data of velocity and/or acceleration.
P Xu, F Du, Y Shu, H Zhang, Y Shi (2021) Regularized reconstruction of peak ground velocity and acceleration from very high-rate GNSS precise point positioning with applications to the 2013 Lushan Mw6. 6 earthquake.
Journal of Geodesy 95, article number 17, doi.org/10.1007/s00190-020-01449-6
P Xu (2021) A regularization method to compute velocity and acceleration and its apparatus. Patent submitted on 13 Jan 2021