Preprints
Filtering by Subject: Engineering
High-resolution downscaled CMIP5 projections dataset of essential surface climate variables over Europe coherent with ERA5-Land reanalyses for climate change impact assessments
Published: 2020-11-27
Subjects: Engineering, Life Sciences, Physical Sciences and Mathematics
A high-resolution climate projections dataset is obtained by statistically downscaling climate projections from the CMIP5 experiment using the ERA5-Land reanalyses from the Copernicus Climate Change service. The dataset is over Europe, has a spatial resolution of 0.10° x 0.10°, comprises 21 climate models and includes 5 surface daily variables: air temperature (mean, minimum, and maximum), [...]
High-resolution downscaled CMIP5 projections dataset of essential surface climate variables over the globe coherent with ERA5 reanalyses for climate change impact assessments
Published: 2020-11-27
Subjects: Engineering, Life Sciences, Physical Sciences and Mathematics
A high-resolution climate projections dataset is obtained by statistically downscaling climate projections from the CMIP5 experiment using the ERA5 reanalyses from the Copernicus Climate Change service. The dataset is global has a spatial resolution of 0.25°x 0.25°, comprises 21 climate models and includes 5 surface daily variables: air temperature (mean, minimum, and maximum), precipitation, and [...]
The development of intermittent multiphase fluid flow pathways through a porous rock
Published: 2020-11-18
Subjects: Engineering, Physical Sciences and Mathematics
Intermittent fluid flow has recently been identified as an important transport mode for subsurface multiphase flow systems such as CO2 storage and natural gas production. However, due to experimental limitations, it has not been possible to identify why intermittency occurs at subsurface conditions and what the implications are for upscaled flow properties such as relative permeability. We [...]
Improving mechanical behaviour of collapsible soils by grouting active clay nanoparticles
Published: 2020-10-27
Subjects: Engineering, Physical Sciences and Mathematics
The primary geotechnical concern of collapsible soils such as loess is their hydromechanical instability. During (re)wetting, metastable aggregates disintegrate leading soil to collapse under the applied load or self-weight. In situ chemical stabilisation, such as grouting, is a favoured option to improve the mechanical behaviour of soils; however, the low permeability of loess limits the [...]
Forecasting landslides by taking their temperature: Combining mathematical and experimental modeling with field data on the case of the El Forn landslide (Andorra)
Published: 2020-10-25
Subjects: Engineering
In this study we are suggesting a temperature-based modeling approach for deep-seated landslides, validated through combined field monitoring and experimental testing. The Silurian shales of the shear band of El Forn landslide (Andorra) have been characterized through thermal and rate controlled triaxial tests, thereby calibrating a mathematical model that is used to monitor the behavior of [...]
An Urban Planning Sustainability Framework: Systems Approach to Blue Green Urban Design
Published: 2020-10-23
Subjects: Engineering
The climate emergency and population growth are challenging water security and sustainable urban design in cities worldwide. Sustainable urban development is crucial to minimise pressures on the natural environment and on existing urban infrastructure systems, including water, energy, and land. These pressures are particularly evident in London, which is considered highly vulnerable to water [...]
Development of new Index based supervised algorithm for separation of Built-Up and River Sand pixels from Landsat7 imagery : Comparison of performance with SVM
Published: 2020-10-22
Subjects: Computational Engineering, Engineering, Environmental Engineering
While classifying “built-up” pixels from satel- lite imagery, both machine learning & index based algo- rithms often misclassify “river sand” pixels as “built-up” ones due to the similarity in their spectral profiles. With the help of the spectral reflectance information in BLUE & GREEN bands of Landsat satellite imagery, this study has introduced a new index BRSSI (Built-Up & River Sand [...]
Tuning sedimentation through surface charge and particle shape
Published: 2020-10-22
Subjects: Engineering, Physical Sciences and Mathematics
Mud forms the foundation of many coastal and tidal environments. Clay suspensions carried downstream from rivers encounter saline waters, which encourages aggregation and sedimentation by reducing electrostatic repulsion among particles. We perform experiments to examine the effects of surface charge on both the rate and style of sedimentation, using kaolinite particles as a model mud suspension [...]
An explanation to the Nusselt-Rayleigh discrepancy in naturally convected porous media
Published: 2020-10-22
Subjects: Engineering, Physical Sciences and Mathematics
We model hydrothermal convection using a partial differential equation formed by Darcy velocity and temperature - the velocity formulation. Using the Elder problem as a benchmark, we found that the velocity formulation is a valid model of hydrothermal convection. By performing simulations with Rayleigh numbers in the non-oscillatory regime, we show that multiple quasi-steady-state solutions can [...]
Structure-from-Motion on shallow reefs and beaches: potential and limitations of consumer-grade drones to reconstruct topography and bathymetry
Published: 2020-10-21
Subjects: Civil Engineering, Engineering, Environmental Engineering, Environmental Monitoring, Environmental Studies, Fluid Dynamics, Fresh Water Studies, Geographic Information Sciences, Hydraulic Engineering, Other Civil and Environmental Engineering, Other Environmental Sciences, Remote Sensing
Reconstructing the topography of shallow underwater environments using Structure-from-Motion – Multi View Stereo (SfM-MVS) techniques applied to aerial imagery from Unmanned Aerial Vehicles (UAVs) is a challenging problem, as it involves non-linear distortions caused by water refraction. This study presents an experiment with aerial photographs collected with a consumer-grade UAV on the [...]
River Planform Extraction From High-Resolution SAR Images Via Generalised Gamma Distribution Superpixel Classification
Published: 2020-10-21
Subjects: Computer Engineering, Electrical and Computer Engineering, Engineering, Geology, Geomorphology, Hydrology
The extraction of river planforms from remotely sensed satellite images is a task of crucial importance to many applications such as land planning, water resource monitoring or flood prediction. In this paper we present a novel framework for the extraction of rivers from Synthetic Aperture Radar (SAR) images, based on superpixel segmentation and subsequent classification. Superpixel segmentation [...]
Downhole distributed acoustic sensing reveals the wave field structure of the coastal microseisms
Published: 2020-10-21
Subjects: Engineering, Physical Sciences and Mathematics
Ocean-generated seismic waves are omnipresent in passive seismic records around the world and present both a challenge for earthquakes observations and an input signal for interferometric methods for characterisation of the Earth's interior. Understanding of these waves requires the knowledge of the depth-dependence of the oceanic noise at the transition into continent. To this end, we examine 80 [...]
An analytical solution to the Navier–Stokes equation for incompressible flow around a solid sphere
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 [...]
Computing single-particle flotation kinetics using automated mineralogy data and machine learning
Published: 2020-08-21
Subjects: Earth Sciences, Engineering, Geology, Mining Engineering, Physical Sciences and Mathematics
Studies of flotation kinetics are essential for understanding, predicting, and optimizing the selective recovery of minerals and metals through flotation. Recently, much effort has been made to use intrinsic ore properties to model flotation behavior. Particle-based characterization methods, e.g. SEM-based image analysis, has enabled much of this development. However, currently available methods [...]
Quantification of non-linear multiphase flow in porous media
Published: 2020-08-20
Subjects: Earth Sciences, Engineering, Hydrology, Life Sciences, Medicine and Health Sciences, Mineral Physics, Physical Sciences and Mathematics
We measure the pressure difference during two-phase flow across a sandstone sample for a range of injection rates and fractional flows of water, the wetting phase, during an imbibition experiment. We quantify the onset of a transition from a linear relationship between flow rate and pressure gradient to a non-linear power-law dependence. We show that the transition from linear (Darcy) to [...]