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Randall D. Peters

Publications and source records attributed to Randall D. Peters.

At least 19 recordsLinked to original sources
arXiv2013

Two novel methods for studying lowest frequency Earth oscillations before earthquakes

Two novel methods, one that is experimental and the other comprising a pair of theoretical types (one component that is mathematically rigorous and the other that is of frequency domain computational type), are being used in concert to study the motion of the Earth at periods in the neighborhood of 1000 s to beyond 10,000 s. Corresponding to frequencies lower than what is routinely measured by commercial seismographs, our observations are yielding new insights into the mysteries of Earth dynamics responsible for earthquakes.

physics.gen-ph↗
arXiv2012

Prediction of Catastrophes: an experimental model

Catastrophes of all kinds can be roughly defined as short duration-large amplitude events following and followed by long periods of "ripening". Major earthquakes surely belong to the class of 'catastrophic' events. Because of the space-time scales involved, an experimental approach is often difficult, not to say impossible, however desirable it could be. Described in this article is a "laboratory" setup that yields data of a type that is amenable to theoretical methods of prediction. Observations are made of a critical slowing down in the noisy signal of a solder wire creeping under constant stress. This effect is shown to be a fair signal of the forthcoming catastrophe in both of two dynamical models. The first is an "abstract" model in which a time dependent quantity drifts slowly but makes quick jumps from time to time. The second is a realistic physical model for the collective motion of dislocations (the Ananthakrishna set of equations for creep). Hope thus exists that similar changes in the response to noise could forewarn catastrophes in other situations, where such precursor effects should manifest early enough.

physics.data-an↗
arXiv2010

Physics Education using a Smartphone Accelerometer

Described is an experiment in which a smartphone was caused to move at steady state in a vertical plane, on a path that was nearly circular. During a time interval of data acquisition that encompassed multiple orbits, the acceleration of the phone was measured by means of its internal accelerometer. A subsequent analysis of the data that was collected shows reasonable agreement between experiment and a simple theory of the motion.

physics.gen-ph↗
arXiv2010

Smart-phone Sensor of Pendulum Motion

Described is an experiment where the embedded accelerometer of a smart-phone was used to study the free decay of a `simple' pendulum to which the phone was attached.

physics.gen-ph↗
arXiv2009

Pendulum Sensor using an Optical Mouse

An optical mouse that is in common use with personal computers is employed to measure the motion of a pendulum. The pendulum can be monitored (i) realtime only, or (ii) also with data storage for later detailed analysis using Excel. The software developed for this purpose is a LabView executable algorithm. It allows the user to select among several modes that include filtering operations. The limiting resolution of this position sensor, which is in the neighborhood of 50 micrometers, is determined by the 'dpi' specification of the mouse.

physics.gen-ph↗
arXiv2009

A New Look at an Old Tool-the Cumulative Spectral Power of Fast-Fourier Transform Analysis

As an old and widely used tool, it is still possible to find new insights and applications from Fast Fourier Transform (FFT)-based analyses. The FFT is frequently used to generate the Power Spectral Density (PSD) function, by squaring the spectral components that have been corrected for influence from the instrument that generated the data. Although better than a raw-data spectrum, by removing influence of the instrument transfer function, the PSD is still of limited value for time varying signals with noise, due to the very nature of the Fourier transform. The authors present here another way to treat the FFT data, namely the Cumulative Spectral Power (CSP), as a promising means to overcome some of these limitations. As will be seen from the examples provided, the CSP holds promise in a variety of different fields.

physics.data-an↗
arXiv2007

A New Tool for Seismology--the Cumulative Spectral Power

The power spectral density (PSD) function is commonly used to specify seismometer performance. It is derived from the FFT of acceleration and correction is made for the transfer function of the instrument that generated the data. As with any such spectrum of density (`per Hz') type, the noise inherent to a PSD is large. This article illustrates the value of a function that is derived from the PSD and for which the influence of noise is significantly reduced. Called the cumulative spectral power (CSP), it is obtained from the PSD through the noise-reducing process of integration. The maximum of the CSP (corresponding to the longest graphed value of the period) provides a means for estimating the total vibrational power of the earth. The present author has significantly simplified the process of PSD generation. Thus routine graphing is straightforwared-of first the FFT, followed by the generation of both a PSD and its associated CSP. The unique properties of the CSP make it valuable for the study of a variety of earth dynamics. For example, the strking simplicity of a CSP graph generated from a record containing a strong teleseismic earthquake is undoubtedly important to the development and refinement of any viable theory of earthquake dynamics.

physics.geo-ph↗
arXiv2006

Compound Pendulum to Monitor Hurricanes and Tropical Storms

The period of an undamped compound pendulum has been selected to maximize the instrument's response to microseisms, when functioning as a type of horizontal seismometer. When functioning as a tiltmeter, the instrument is also capable of monitoring eigenmode oscillations of the Earth. Other instruments designed by the author, some of which were monitored during hurricanes, suggest that storm seismicity in the frequency range of this pendulum could aid the process of hurricane forecasting.

physics.geo-ph↗
arXiv2006

Compton-Energy Scale of Friction Quantization

Numerous different experiments by the author, approaching nearly two decades of study, point strongly toward the possibility that friction operates around a mesoscale quantum of energy having the value 11 pJ.

physics.gen-ph↗
arXiv2006

Measurement of Earth's Free-Oscillations using a Pendulum

One of the best ways to measure low-frequency eigenmode oscillations of the Earth is to monitor a simple pendulum responding to tilt. A theoretical basis for the method is given, by investigating a particular, well-known standing wave-the one with 53 minute period corresponding to oblate/prolate spheroidal deviations from the geoid.

physics.geo-ph↗
arXiv2006

Earth oscillations induced by Hurricane Katrina

Seismograph records show that Katrina was responsible for many motions of the Earth in addition to the well known microseismic `noise' that is known to accompany oceanic disturbances.

physics.geo-ph↗
arXiv2005

Hurricanes and Earth Hum

A modernized conventional pendulum has been used to show that hurricanes Katrina and Ophelia excited eigenmode oscillations of the Earth as well as microseisms.

physics.geo-ph↗
arXiv2005

Creep-Enhanced Low-Frequency Sensitivity of Seismometers

The frequency response of a seismometer is typically assumed to be the textbook case of a viscous damped, simple harmonic oscillator. Real mechanical oscillators are not ideal, and the damping at low frequencies, due to internal friction, is presently too poorly understood to describe from first principles. Even if the low-level motions were smooth (which they are not), the mean position of a seismic mass changes because of creep and creep recovery. This article shows that secondary creep can actually serve to increase the sensitivity of a seismometer at low frequencies.

physics.geo-ph↗
arXiv2005

Correlation measurements of Atmospheric Pressure variations and Seismicity during Hurricane Dennis

During the passage of hurricane Dennis, two functionally different instruments made continuous recordings from their location in Macon, Georgia. These were (i) a non-conventional vertical seismometer, and (ii) a low-level differential pressure sensor. Data were collected for 72 hours, beginning when the eye of the storm was located in the vicinity of Key West, Florida. Over the ensuing three-day period, fluctuations in the outputs from the two instruments were found to be highly correlated, with the exception of one eight hour interval.

physics.geo-ph↗
arXiv2005

Hurricane Excitation of Earth Eigenmodes

A non-conventional vertical seismometer, with good low-frequency sensitivity, was used to study earth motions in Macon, Georgia USA during the time of hurricane Charley, August 2004. During its transitions between water and land, the powerful storm showed an interesting history of microseisms and also generated more than half-a-dozen surprisingly coherent oscillations, whose frequencies ranged from 0.9 to 3 mHz.

physics.geo-ph↗