Filtering by Subject: Mechanical Engineering

Robust Probabilities of Detection and Quantification Uncertainty for Aerial Methane Detection: Examples for Three Airborne Technologies

Bradley Mark Conrad, David R Tyner, Matthew R Johnson

Published: 2022-06-17
Subjects: Atmospheric Sciences, Climate, Environmental Monitoring, Mechanical Engineering, Oil, Gas, and Energy, Statistical Methodology, Statistical Models

Thorough understanding of probabilities of detection (POD) and quantification uncertainties is fundamentally important when applying aerial measurement technologies as part of alternative means of emission limitation (AMEL) or alternate fugitive emissions management programs (Alt-FEMP), as part of monitoring, reporting, and verification (MRV) efforts, and in surveys designed to support [...]

Experimental investigation of fire spread across a vegetative fuel bed incorporating the effect of wind velocity

Reza Ziazi, Abhinandan Singh, Ahmed O. Said, et al.

Published: 2022-05-10
Subjects: Engineering, Mechanical Engineering

Wind, moisture content, and density of fuel are three environmental factors that affect the rate of fire spread in wildland fires by changing the rate of convection, radiation, and conduction heat transfer from the flames and burned fuels to the unburned fuel. These effects have been experimentally investigated in the current study to further understand the complex phenomena of wildland fire [...]

Spatio-temporal clustering of seismicity enabled by off-fault plasticity

Md Shumon Mia, Mohamed Abdelmeguid, Ahmed Elbanna

Published: 2021-12-06
Subjects: Applied Mechanics, Civil and Environmental Engineering, Dynamics and Dynamical Systems, Earth Sciences, Engineering, Engineering Mechanics, Engineering Science and Materials, Geophysics and Seismology, Mechanical Engineering, Mechanics of Materials, Other Mechanical Engineering, Physical Sciences and Mathematics, Tribology

While significant progress has been made in understanding earthquake source processes in linear elastic domains, the effect of more realistic rheologies including plasticity is poorly understood. Here, we simulate sequence of earthquake and aseismic slip of a 2D antiplane rate-and-state fault embedded in a full-space elastic-plastic bulk. We show that off-fault plasticity may lead to partial [...]

An analytical solution to the Navier–Stokes equation for incompressible flow around a solid sphere

Ahmad Talaei, Timothy J. Garrett

Published: 2020-08-25
Subjects: Applied Mathematics, Earth Sciences, Engineering, Fluid Dynamics, Mechanical Engineering, Other Mechanical Engineering, Partial Differential Equations, Physical Sciences and Mathematics, Physics, Special Functions

This paper is concerned with obtaining a formulation for the flow past a sphere in a viscous and incompressible fluid, building upon previously obtained well-known solutions that were limited to small Reynolds numbers. Using a method based on a summation of separation of variables, we develop a general analytical solution to the Navier--Stokes equation for the special case of axially symmetric [...]

Crack to pulse transition and magnitude statistics during earthquake cycles on a self-similar rough fault

Elias Rafn Heimisson

Published: 2019-10-08
Subjects: Earth Sciences, Engineering, Geophysics and Seismology, Mechanical Engineering, Physical Sciences and Mathematics, Tectonics and Structure, Tribology

Faults in nature demonstrate fluctuations from planarity at most length scales that are relevant for earthquake dynamics. These fluctuations may influence all stages of the seismic cycle; earthquake nucleation, propagation, arrest, and inter-seismic behavior. Here I show quasi-dynamic plane-strain simulations of earthquake cycles on a self-similar and finite 10 km long rough fault with [...]

A Novel Hybrid Finite Element-Spectral Boundary Integral Scheme for Modeling Earthquake Cycles: Application to Rate and State Faults with Low-Velocity Zones

Mohamed Abdelmeguid, Xiao Ma, Ahmed Elbanna

Published: 2019-05-14
Subjects: Applied Mechanics, Earth Sciences, Engineering, Geophysics and Seismology, Mechanical Engineering, Physical Sciences and Mathematics

We present a novel hybrid finite element (FE) - spectral boundary integral (SBI) scheme that enables efficient simulation of earthquake cycles. This combined FE-SBI approach captures the benefits of finite elements in modelling problems with nonlinearities, as well as the computational superiority of SBI. The domain truncation enabled by this scheme allows us to utilize high-resolution finite [...]

Poroelastic effects destabilize mildly rate-strengthening friction to generate stable slow slip pulses

Elias Rafn Heimisson, Eric M Dunham, Martin Almquist

Published: 2019-03-18
Subjects: Applied Mechanics, Earth Sciences, Engineering, Geology, Geophysics and Seismology, Mechanical Engineering, Physical Sciences and Mathematics, Physics, Statistical, Nonlinear, and Soft Matter Physics, Tribology

Slow slip events on tectonic faults, sliding instabilities that never accelerate to inertially limited ruptures or earthquakes, are one of the most enigmatic phenomena in frictional sliding. While observations of slow slip events continue to mount, a plausible mechanism that permits instability while simultaneously limiting slip speed remains elusive. Rate-and-state friction has been successful [...]

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