Real-Time Seismic Waveforms Estimation of the 2019 MW = 6.4 and Mw = 7.1 California Earthquakes With High-Rate Multi-GNSS Observations

Abstract. This paper presents the development and applications of a software-based quality control system that monitors volcano activity in near-real time. On the premise that external seismic manifestations provide information directly related to the internal status of a volcano, here we analyzed variations in background seismic noise. By continuous analysis of variations in seismic waveforms, we detected clear indications of changes in the internal status. The application of this method to data recorded in Villarrica (Chile) and Tungurahua (Ecuador) volcanoes demonstrates that it is suitable to be used as a forecasting tool. A recent application of this developed software-based quality control to the real-time monitoring of Teide – Pico Viejo volcanic complex (Spain) anticipated external episodes of volcanic activity, thus corroborating the advantages and capacity of the methodology when implemented as an automatic real-time procedure.

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Real-Time Coseismic Velocity and Displacements Retrieving and De-Noising Process by High-Rate GNSS

Lecture Notes in Electrical Engineering - China Satellite Navigation Conference (CSNC) 2013 Proceedings ◽

10.1007/978-3-642-37404-3_42 ◽

2013 ◽

pp. 523-537 ◽

Cited By ~ 1

Author(s):

Rui Tu ◽

Rongjiang Wang ◽

Yong Zhang ◽

Maorong Ge ◽

Qin Zhang

Keyword(s):

Real Time ◽

High Rate

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Hybrid Wavelet and Principal Component Analyses Approach for Extracting Dynamic Motion Characteristics from Displacement Series Derived from Multipath-Affected High-Rate GNSS Observations

Remote Sensing ◽

10.3390/rs12010079 ◽

2019 ◽

Vol 12 (1) ◽

pp. 79 ◽

Cited By ~ 4

Author(s):

Mosbeh R. Kaloop ◽

Cemal O. Yigit ◽

Ahmed El-Mowafy ◽

Ahmet A. Dindar ◽

Mert Bezcioglu ◽

...

Keyword(s):

Dynamic Characteristics ◽

Principal Component ◽

Dominant Frequency ◽

Shaking Table ◽

Global Navigation Satellite Systems ◽

High Rate ◽

Engineering Structures ◽

Satellite Systems ◽

Multipath Errors ◽

Gnss Observations

Nowadays, the high rate GNSS (Global Navigation Satellite Systems) positioning methods are widely used as a complementary tool to other geotechnical sensors, such as accelerometers, seismometers, and inertial measurement units (IMU), to evaluate dynamic displacement responses of engineering structures. However, the most common problem in structural health monitoring (SHM) using GNSS is the presence of surrounding structures that cause multipath errors in GNSS observations. Skyscrapers and high-rise buildings in metropolitan cities are generally close to each other, and long-span bridges have towers, main cable, and suspender cables. Therefore, multipath error in GNSS observations, which is typically added to the measurement noise, is inevitable while monitoring such flexible engineering structures. Unlike other errors like atmospheric errors, which are mostly reduced or modeled out, multipath errors are the largest remaining unmanaged error sources. The high noise levels of high-rate GNSS solutions limit their structural monitoring application for detecting load-induced semi-static and dynamic displacements. This study investigates the estimation of accurate dynamic characteristics (frequency and amplitude) of structural or seismic motions derived from multipath-affected high-rate GNSS observations. To this end, a novel hybrid model using both wavelet-based multiscale principal component analysis (MSPCA) and wavelet transform (MSPCAW) is designed to extract the amplitude and frequency of both GNSS relative- and PPP- (Precise Point Positioning) derived displacement motions. To evaluate the method, a shaking table with a GNSS receiver attached to it, collecting 10 Hz data, was set up close to a building. The table was used to generate various amplitudes and frequencies of harmonic motions. In addition, 50-Hz linear variable differential transformer (LVDT) observations were collected to verify the MSMPCAW model by comparing their results. The results showed that the MSPCAW could be efficiently used to extract the dynamic characteristics of noisy dynamic movements under seismic loads. Furthermore, the dynamic behavior of seismic motions can be extracted accurately using GNSS-PPP, and its dominant frequency equals that extracted by LVDT and relative GNSS positioning method. Its accuracy in determining the amplitude approaches 91.5% relative to the LVDT observations.

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Content Repurposing for Small Devices

Encyclopedia of Multimedia Technology and Networking ◽

10.4018/978-1-59140-561-0.ch017 ◽

2011 ◽

pp. 110-115

Author(s):

Neil C. Rowe

Keyword(s):

Real Time ◽

Automated Planning ◽

High Rate ◽

Handheld Devices ◽

Personal Digital Assistants ◽

Web Page ◽

Multimedia Delivery ◽

Video And Audio ◽

New Devices

Content repurposing is the reorganizing of data for presentation on different display hardware (Singh, 2004). It has been particularly important recently with the growth of handheld devices such as personal digital assistants (PDAs), sophisticated telephones, and other small specialized devices. Unfortunately, such devices pose serious problems for multimedia delivery. With their tiny screens (150 by 150 for a basic Palm PDA or 240 by 320 for a more modern one, vs. 640 by 480 for standard computer screens), one cannot display much information (i.e., most of a Web page); with their low bandwidths, one cannot display video and audio transmissions from a server (i.e., streaming) with much quality; and with their small storage capabilities, large media files cannot be stored for later playback. Furthermore, new devices and old ones with new characteristics have been appearing at a high rate, so software vendors are having difficulty keeping pace. So some real-time, systematic, and automated planning could be helpful in figuring how to show desired data, especially multimedia, on a broad range of devices.

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Weighting of Multi-GNSS Observations in Real-Time Precise Point Positioning

Remote Sensing ◽

10.3390/rs10010084 ◽

2018 ◽

Vol 10 (2) ◽

pp. 84 ◽

Cited By ~ 28

Author(s):

Kamil Kazmierski ◽

Tomasz Hadas ◽

Krzysztof Sośnica

Keyword(s):

Real Time ◽

Precise Point Positioning ◽

Point Positioning ◽

Gnss Observations

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Real-time inversions for finite fault slip models and rupture geometry based on high-rate GPS data

Journal of Geophysical Research Solid Earth ◽

10.1002/2013jb010622 ◽

2014 ◽

Vol 119 (4) ◽

pp. 3201-3231 ◽

Cited By ~ 51

Author(s):

S. E. Minson ◽

Jessica R. Murray ◽

John O. Langbein ◽

Joan S. Gomberg

Keyword(s):

Real Time ◽

Fault Slip ◽

High Rate ◽

Gps Data ◽

Finite Fault

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Optimization of Rapid State Estimation in Structures Subjected to High-Rate Boundary Change

ASME 2020 Conference on Smart Materials, Adaptive Structures and Intelligent Systems ◽

10.1115/smasis2020-2306 ◽

2020 ◽

Author(s):

James Scheppegrell ◽

Adriane G. Moura ◽

Jacob Dodson ◽

Austin Downey

Keyword(s):

Frequency Response ◽

State Estimation ◽

Real Time ◽

Performance Metrics ◽

Numerical Models ◽

Vertical Axis ◽

High Rate ◽

Position Measurement ◽

Data Set ◽

Variable Boundary

Abstract Many structures are subjected to varying forces, moving boundaries, and other dynamic conditions. Whether part of a vehicle, building, or active energy mitigation device, data on such changes can represent useful knowledge, but also presents challenges in its collection and analysis. In systems where changes occur rapidly, assessment of the system’s state within a useful time span is required to enable an appropriate response before the system’s state changes further. Rapid state estimation is especially important but poses unique difficulties. In determining the state of a structural system subjected to high-rate dynamic changes, measuring the frequency response is one method that can be used to draw inferences, provided the system is adequately understood and defined. The work presented here is the result of an investigation into methods to determine the frequency response, and thus state, of a structure subjected to high-rate boundary changes in real-time. In order to facilitate development, the Air Force Research Laboratory created the DROPBEAR, a testbed with an oscillating beam subjected to a continuously variable boundary condition. One end of the beam is held by a stationary fixed support, while a pinned support is able to move along the beam’s length. The free end of the beam structure is instrumented with acceleration, velocity, and position sensors measuring the beam’s vertical axis. Direct position measurement of the pin location is also taken to provide a reference for comparison with numerical models. This work presents a numerical investigation into methods for extracting the frequency response of a structure in real-time. An FFT based method with a rolling window is used to track the frequency of a data set generated to represent the range of the DROPBEAR, and is run with multiple window lengths. The frequency precision and latency of the FFT method is analyzed in each configuration. A specialized frequency extraction technique, Delayed Comparison Error Minimization, is implemented with parameters optimized for the frequency range of interest. The performance metrics of latency and precision are analyzed and compared to the baseline rolling FFT method results, and applicability is discussed.

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A Decentralized Processing Schema for Efficient and Robust Real-time Multi-GNSS Satellite Clock Estimation

Remote Sensing ◽

10.3390/rs11212595 ◽

2019 ◽

Vol 11 (21) ◽

pp. 2595

Author(s):

Jiang ◽

Gu ◽

Li ◽

Ge ◽

Schuh

Keyword(s):

Real Time ◽

High Frequency ◽

Precise Point Positioning ◽

High Rate ◽

Reference Network ◽

Satellite Clock ◽

Navigation Data ◽

Data Analyst ◽

New Strategy ◽

Clock Estimation

Real-time multi-GNSS precise point positioning (PPP) requires the support of high-rate satellite clock corrections. Due to the large number of ambiguity parameters, it is difficult to update clocks at high frequency in real-time for a large reference network. With the increasing number of satellites of multi-GNSS constellations and the number of stations, real-time high-rate clock estimation becomes a big challenge. In this contribution, we propose a decentralized clock estimation (DECE) strategy, in which both undifferenced (UD) and epoch-differenced (ED) mode are implemented but run separately in different computers, and their output clocks are combined in another process to generate a unique product. While redundant UD and/or ED processing lines can be run in offsite computers to improve the robustness, processing lines for different networks can also be included to improve the clock quality. The new strategy is realized based on the Position and Navigation Data Analyst (PANDA) software package and is experimentally validated with about 110 real-time stations for clock estimation by comparison of the estimated clocks and the PPP performance applying estimated clocks. The results of the real-time PPP experiment using 12 global stations show that with the greatly improved computational efficiency, 3.14 cm in horizontal and 5.51 cm in vertical can be achieved using the estimated DECE clock.

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