Publications by Dong Liu | EPFL Graph Search

Effects of velocity-dependent apparent toughness on the pre- and post-shut-in growth of a hydraulic fracture

We investigate the growth of a plane-strain/radial hydraulic fracture in an infinite impermeable medium driven by a constant injection rate assuming that the apparent toughness scales with the decreasing fracture growth rate in a power-law relation. The vi ...

ELSEVIER SCI LTD2022

Laboratory investigation of hydraulic fracture growth in Zimbabwe gabbro

Brice Tanguy Alphonse Lecampion, Dong Liu

2022

Propagation of a plane-strain hydraulic fracture accounting for a rough cohesive zone

Brice Tanguy Alphonse Lecampion, Dong Liu

The quasi-brittle nature of rocks challenges the basic assumptions of linear hydraulic fracture mechanics (LHFM): namely, linear elastic fracture mechanics and smooth parallel plates lubrication fluid flow inside the propagating fracture. We relax these hy ...

2021

Combining active and passive acoustic methods to image hydraulic fracture growth in laboratory experiments

Brice Tanguy Alphonse Lecampion, Dong Liu, Seyyedmaalek Momeni

We combine active and passive acoustic measurements to improve the spatio- temporal imaging of hydraulic fracture growth performed under true triaxial confinement in the laboratory. 64 active piezo-electric transducers (54 P waves, 10 S waves) work in sour ...

IOP2021

Hydraulic fracture growth in quasi-brittle materials

Dong Liu

Hydraulic fracturing is a technique often used in the oil and gas industry to enhance the production of wells in low-permeability reservoirs. It consists of fluid injection at a sufficiently large injection rate to create and propagate tensile fractures in ...

EPFL2021

Canonical Notch signaling controls the early thymic epithelial progenitor cell state and emergence of the medullary epithelia lineage in fetal thymus development

Freddy Radtke, Ute Koch, Dong Liu

Thymus function depends on the epithelial compartment of the thymic stroma. Cortical thymic epithelial cells (cTECs) regulate T cell lineage commitment and positive selection, while medullary (m) TECs impose central tolerance on the T cell repertoire. Duri ...

2020

Time-lapse reconstruction of the fracture front from diffracted waves arrivals in laboratory hydraulic fracture experiments

Brice Tanguy Alphonse Lecampion, Thomas Emmanuel Blum, Dong Liu

4-D acoustic imaging via an array of 32 sources/32 receivers is used to monitor hydraulic fracture (HF) propagating in a 250 mm cubic specimen under a true-triaxial state of stress. We present a method based on the arrivals of diffracted waves to reconstru ...

2020

Propagation of a plane-strain hydraulic fracture accounting for the presence of a cohesive zone and a fluid lag

Dong Liu

We revisit the problem of the propagation of a plane-strain fluid-driven fracture in a quasi-brittle impermeable medium accounting for the presence of a fluid lag. The fracture process zone is simulated using a linear-softening cohesive model while lubrica ...

2019

Growth of a radial hydraulic fracture accounting for the viscous fluid flow in a rough cohesive zone

Brice Tanguy Alphonse Lecampion, Dong Liu

We investigate the growth of an axisymmetric hydraulic fracture in an impermeable quasi-brittle material accounting for the presence of a fluid lag. The process zone is simulated using a linear softening cohesive zone model and is characterized by an incre ...

2019

Propagation of a fluid-driven fracture with fracture length dependent apparent toughness

Brice Tanguy Alphonse Lecampion, Dong Liu

We investigate the growth of a hydraulic fracture assuming a power-law dependence of material toughness with fracture length for plane strain and radial geometries. Such a toughness fracture length dependence models in a simple manner a toughening mechanis ...

2019

NTIRE 2018 Challenge on Spectral Reconstruction from RGB Images

Radu Timofte, Marjan Shahpaski, Ruofan Zhou, Fayez Lahoud, Majed El Helou, Dong Liu, Lei Zhang, Soumik Sarkar, Himanshu Sharma, Bing Zhang, Chang Chen

This paper reviews the first challenge on spectral image reconstruction from RGB images, i.e., the recovery of whole-scene hyperspectral (HS) information from a 3- channel RGB image. The challenge was divided into 2 tracks: the “Clean” track sought HS reco ...

2018

EEG-based lower-limb movement onset decoding: Continuous classification and asynchronous detection

Mohamed Bouri, Ricardo Andres Chavarriaga Lozano, José del Rocio Millán Ruiz, Kyuhwa Lee, Fumiaki Iwane, Dong Liu

Brain-machine interfaces (BMIs) have been used to incorporate the user intention to trigger robotic devices by decoding movement onset from electroencephalography (EEG). Active neural participation is crucial to promote brain plasticity thus to enhance the ...

2018

Decoding of Self-paced Lower-Limb Movement Intention: A Case Study on the Influence Factors

Ricardo Andres Chavarriaga Lozano, José del Rocio Millán Ruiz, Dong Liu

Brain-machine interfaces (BMIs) have been applied as new rehabilitation tools for motor disabled individuals. Active involvement of cerebral activity has been shown to enhance neuroplasticity and thus to restore mobility. Various studies have focused on th ...

Frontiers Research Foundation2017

Brain-actuated gait trainer with visual and proprioceptive feedback

Mohamed Bouri, Ricardo Andres Chavarriaga Lozano, José del Rocio Millán Ruiz, Kyuhwa Lee, Dong Liu

Objective. Brain-machine interfaces (BMIs) have been proposed in closed-loop applications for neuromodulation and neurorehabilitation. This study describes the impact of different feedback modalities on the performance of an EEG-based BMI that decodes moto ...

Institute of Physics2017

A Brain-Controlled Exoskeleton with Cascaded Event-Related Desynchronization Classifiers

Ricardo Andres Chavarriaga Lozano, José del Rocio Millán Ruiz, Kyuhwa Lee, Dong Liu, Dong Liu

This paper describes a brain-machine interface for the online control of a powered lower-limb exoskeleton based on electroencephalogram (EEG) signals recorded over the user’s sensorimotor cortical areas. We train a binary decoder that can distinguish two d ...

Elsevier2017

An EEG-based brain-computer interface for gait training

José del Rocio Millán Ruiz, Kyuhwa Lee, Dong Liu

This work presents an electroencephalography (EEG)-based Brain-computer Interface (BCI) that decodes cerebral activities to control a lower-limb gait training exoskeleton. Motor imagery (MI) of flexion and extension of both legs was distinguished from the ...

2017

Endogenous Control of Powered Lower-Limb Exoskeleton

Ricardo Andres Chavarriaga Lozano, José del Rocio Millán Ruiz, Kyuhwa Lee, Dong Liu

We present an online decoding method for controlling a powered lower-limb exoskeleton using endogenously generated electroencephalogram (EEG) signals of human users. By performing a series of binary classifications, users control the exoskeleton in three d ...

Springer Int Publishing Ag2017