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Tremor Waveform Extraction and Automatic Location With Neural Network Interpretation
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Monitoring Subsurface Fracture Flow Using Unsupervised Deep Learning of Borehole Microseismic Waveform Data
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Waveform-dependent air fluorescence from neutral and ionic nitrogen molecules
Laser-induced air fluorescence in the ultraviolet regime is primarily attributed to transitions between the C and B states in excited neutral N 2 molecules and between the B and X states in N$^+_2$ ions. However, the mechanism underlying the former remains contentious, as direct population to the C state by light fields is forbidden by electron spin constraints. In this work, we investigate the mechanism of air fluorescence from excited neutral N 2 molecules by carrier-envelope phase–stabilized sub–4 femtosecond pulses. Our results show that fluorescence from N$^+_2$ ions reaches a maximum with cosine-like pulses, while fluorescence from excited neutral N 2 molecules peaks with sine-like pulses. In addition, by scanning the chirp of the driving pulse, we find that ionic fluorescence is maximized with chirp-free pulses, whereas neutral fluorescence favors negatively chirped pulses. These observations, supported by classical trajectory Monte Carlo simulations, support the mechanism of intersystem crossing from excited spin-singlet states, which are populated via recollision-induced strong-field excitation.
Numerical Study of the Voltage Waveform Effect on the Spatiotemporal Characteristics of a Dielectric Barrier Microdischarge in Argon
The effect of the shape of the feeding voltage on the spatiotemporal characteristics of an atmospheric- pressure barrier microdischarge in argon is demonstrated using numerical simulations based on an extended fluid model. Results of simulations performed for sinusoidal and square feeding voltages are analyzed.
Gas hydrate quantification using full-waveform inversion of sparse ocean-bottom seismic data: A case study from Green Canyon Block 955, Gulf of Mexico
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Elastic Optical Networking by Dynamic Optical Arbitrary Waveform Generation and Measurement
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Laser waveform control of extreme ultraviolet high harmonics from solids
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Using Waveform Cross Correlation for Detection, Location, and Identification of Aftershocks of the 2017 Nuclear Explosion at the North Korea Test Site
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Inherent secure communications using lattice based waveform design
The wireless communications channel is innately insecure due to the broadcast nature of the electromagnetic medium. Many techniques have been developed and implemented in order to combat insecurities and ensure the privacy of transmitted messages. Traditional methods include encrypting the data via cryptographic methods, hiding the data in the noise floor as in wideband communications, or nulling the signal in the spatial direction of the adversary using array processing techniques. This work analyzes the design of signaling constellations, i.e. modulation formats, to combat eavesdroppers from correctly decoding transmitted messages. It has been shown that in certain channel models the ability of an adversary to decode the transmitted messages can be degraded by a clever signaling constellation based on lattice theory. This work attempts to optimize certain lattice parameters in order to maximize the security of the data transmission. These techniques are of interest because they are orthogonal to, and can be used in conjunction with, traditional security techniques to create a more secure communication channel.
Embedded Fiber Optic Sensors for Measuring Transient Detonation/Shock Behavior;Time-of-Arrival Detection and Waveform Determination.
The miniaturization of explosive components has driven the need for a corresponding miniaturization of the current diagnostic techniques available to measure the explosive phenomena. Laser interferometry and the use of spectrally coated optical windows have proven to be an essential interrogation technique to acquire particle velocity time history data in one- dimensional gas gun and relatively large-scale explosive experiments. A new diagnostic technique described herein allows for experimental measurement of apparent particle velocity time histories in microscale explosive configurations and can be applied to shocks/non-shocks in inert materials. The diagnostic, Embedded Fiber Optic Sensors (EFOS), has been tested in challenging microscopic experimental configurations that give confidence in the technique's ability to measure the apparent particle velocity time histories of an explosive with pressure outputs in the tenths of kilobars to several kilobars. Embedded Fiber Optic Sensors also allow for several measurements to be acquired in a single experiment because they are microscopic, thus reducing the number of experiments necessary. The future of EFOS technology will focus on further miniaturization, material selection appropriate for the operating pressure regime, and extensive hydrocode and optical analysis to transform apparent particle velocity time histories into true particle velocity time histories as well as the more meaningful pressure time histories.
Hydro-to-Seismic modeling; for physics-based modeling of remote seismic waveforms
No abstract provided.
Predictive Fusion of Geophysical Waveforms using Fisher's Method, under the Alternative Hypothesis
This presentation tries to understand how to combine different signatures from an event or source together in a defensible way. The objective was to build a digital detector that continuously combines detection statistics recording explosions to screen sources of interest from null sources.
W17_geowave “3D full waveform geophysical models”
Performance of the MCMC inversion according to the number of cores for the computation. A) 64 cores. B) 480 cores. C) 816 cores. The true model is represented by the black line. Vsv is the wave speed of S waves polarized in the vertical plane, ξ is an anisotropy parameter. The Earth is highly anisotropics; the wavespeed of seismic waves depends on the polarization of the wave. Seismic inversion of the elastic structure is usually limited to isotropic information such as Vsv. Our research looked at the inversion of Earth anisotropy.
Investigating the 2016 Jackson, Wyoming Earthquake Sequence using Waveform Cross-correlation and Seismic Array Methods
No abstract provided.