Preprints
Filtering by Subject: Engineering
Network topology and rainfall controls on the variability of combined sewer overflows and loads
Published: 2019-10-24
Subjects: Civil and Environmental Engineering, Engineering, Environmental Engineering
Water and pollutant fluxes from combined sewer overflows (CSO) have a significant impact on receiving waters. The random nature of rainfall forcing dominates the variability of sewer discharges, pollutant loads, and concentrations. An analytical model developed here, shows how sewer network topology and rainfall properties variously impact the stochasticity of CSO functioning. Probability [...]
Lessons for Machine Learning from the Analysis of Porosity-Permeability Transforms for Carbonate Reservoirs
Published: 2019-10-13
Subjects: Engineering
Prediction of permeability is one of the most difficult aspects of reservoir characterization because permeability cannot be directly measured by current well logging technology. This is particularly challenging for carbonate rocks. Machine learning (ML) and robust multivariate methods have been developed that have been used in many fields of study to make accurate estimators for variables of [...]
Redshift of Earthquakes via Focused Blind Deconvolution of Teleseisms
Published: 2019-10-13
Subjects: Applied Mathematics, Earth Sciences, Electrical and Computer Engineering, Engineering, Geophysics and Seismology, Physical Sciences and Mathematics, Signal Processing
We present a robust factorization of the teleseismic waveforms resulting from an earthquake source into signals that originate from the source and signals that characterize the path effects. The extracted source signals represent the earthquake spectrum and its variation with azimuth. Unlike most prior work on source extraction, our method is data-driven, and it does not depend on any [...]
The sensitivity of estimates of multiphase fluid and solid properties of porous rocks to image processing
Published: 2019-10-10
Subjects: Chemical Engineering, Civil and Environmental Engineering, Earth Sciences, Engineering, Hydrology, Petroleum Engineering, Physical Sciences and Mathematics, Transport Phenomena
X-ray microcomputed tomography X-ray microCT) is a rapidly advancing technology that has been successfully employed to study flow phenomena in porous media. It offers an alternative approach to core scale experiments for the estimation of traditional petrophysical properties such as porosity and single-phase flow permeability. It can also be used to investigate properties that control multiphase [...]
Machine learning on field data for hydraulic fracturing design optimization
Published: 2019-10-08
Subjects: Engineering, Physical Sciences and Mathematics
Growing amount of fracturing stimulation jobs in the recent two decades resulted in a significant amount of measured data available for construction of predictive models via machine learning (ML). Simulataneous evolution of machine learning has made it possible to apply algorithms on the hydraulic fracture database. A typical multistage fracturing job on a near-horizontal well today involves a [...]
Crack to pulse transition and magnitude statistics during earthquake cycles on a self-similar rough fault
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 [...]
Does a damaged fault zone mitigate the near-field landslide risk during supershear earthquakes?—Application to the 2018 magnitude 7.5 Palu earthquake.
Published: 2019-10-03
Subjects: Civil and Environmental Engineering, Earth Sciences, Engineering, Geotechnical Engineering, Physical Sciences and Mathematics
The impact of earthquakes can be severely aggravated by cascading secondary hazards. The 2018 Mw 7.5 Palu, Indonesia earthquake led to devastating tsunamis and landslides, while triggered submarine landslides possibly contributed substantially to generate the tsunami. The rupture was supershear over most of its length, but its speed was unexpectedly low, between the S-wave velocity Vs and [...]
Mechanisms controlling fluid break-up and reconnection during two-phase flow in porous media
Published: 2019-10-01
Subjects: Earth Sciences, Engineering, Geophysics and Seismology, Life Sciences, Physical Sciences and Mathematics
The use of Darcys law to describe steady-state multiphase flow in porous media has been justified by the assumption that the fluids flow in continuously connected pathways. However, a range of complex interface dynamics have been observed during macroscopically steady-state flow, including intermittent pathway flow where flow pathways periodically disconnect and reconnect. The physical [...]
Representative elementary volumes, hysteresis and heterogeneity in multiphase flow from the pore to continuum scale
Published: 2019-09-22
Subjects: Earth Sciences, Engineering, Hydrology, Physical Sciences and Mathematics
Representative elementary volumes (REVs) and heterogeneity are key concepts in continuum multiphase flow, yet their manifestation from the pore-scale and associated impacts with the flow regime are not well understood. We use a multi-scale experimental and modelling approach to elucidate the role of REVs, hysteresis and heterogeneity in multiphase flow in two distinct water-wetting Bentheimer [...]
Paradoxical impact of sprawling intra-Urban Heat Islets: Reducing mean surface temperatures while enhancing local extremes
Published: 2019-09-09
Subjects: Civil and Environmental Engineering, Earth Sciences, Engineering, Life Sciences, Physical Sciences and Mathematics, Statistics and Probability
Cities are at the forefront of climate change impacts and face a growing burden of adaptation to ensuing natural hazards. Extreme heat is a particularly challenging hazard as persistent heatwaves are locally exacerbated by the Urban Heat Island (UHI) effect. As a result, there is an increasing scientific interest in the influence of diverse urban morphologies on UHI. However, as the temperatures [...]
Hydropower dependency and climate change in sub-Saharan Africa: A nexus framework and evidence-based review
Published: 2019-09-06
Subjects: Civil and Environmental Engineering, Earth Sciences, Engineering, Environmental Sciences, Environmental Studies, International and Area Studies, Physical Sciences and Mathematics, Social and Behavioral Sciences
In sub-Saharan Africa, 160 million grid-connected electricity consumers live in countries where hydropower accounts for over 50% of total power supply. A warmer climate with more frequent and intense extremes could result in supply reliability issues. Here, (i) a robust framework to highlight the interdependencies between hydropower, water availability, and climate change is proposed, (ii) the [...]
Building back bigger in hurricane strike zones
Published: 2019-09-03
Subjects: Civil and Environmental Engineering, Earth Sciences, Engineering, Environmental Sciences, Geomorphology, Physical Sciences and Mathematics, Sustainability
Despite decades of regulatory efforts in the United States to decrease vulnerability in developed coastal zones, exposure of residential assets to hurricane damage is increasing — even in places where hurricanes have struck before. Comparing plan-view footprints of individual residential buildings before and long after major hurricane strikes, we find a systematic pattern of ‘building back [...]
The near-tip region of a hydraulic fracture with pressure-dependent leak-off and leak-in
Published: 2019-09-03
Subjects: Earth Sciences, Engineering, Environmental Sciences, Hydrology, Oil, Gas, and Energy, Physical Sciences and Mathematics, Volcanology
This paper is concerned with an analysis of the near tip region of a propagating fluid-driven fracture in a saturated permeable rock. The study attempts to accurately resolve the coupling between the physical processes - rock breakage, fluid pressure drop in the viscous fluid flow in the fracture, and fluid exchange between fracture and the rock - that exert influence on the hydraulic fracture [...]
Emergent self-similarity and scaling properties of fractal intra-Urban Heat Islets for diverse global cities
Published: 2019-09-02
Subjects: Civil and Environmental Engineering, Earth Sciences, Engineering, Environmental Sciences, Physical Sciences and Mathematics, Statistics and Probability
Urban areas experience elevated temperatures due to the Urban Heat Island (UHI) effect. However, temperatures within cities vary considerably and their spatial heterogeneity is not well characterized. Here, we use Land Surface Temperature (LST) of 78 global cities to show that the Surface UHI (SUHI) is fractal. We use percentile-based thermal thresholds to identify heat clusters emerging within [...]
Accounting for training data error in machine learning applied to Earth observations
Published: 2019-08-29
Subjects: Earth Sciences, Engineering, Environmental Monitoring, Environmental Sciences, Life Sciences, Physical Sciences and Mathematics
Remote sensing, or Earth Observation (EO), is increasingly used to understand Earth system dynamics and create continuous and categorical maps of biophysical properties and land cover, especially based on recent advances in machine learning (ML). ML models typically require large, spatially explicit training datasets to make accurate predictions. Training data (TD) are typically generated by [...]