TY  - JOUR
A1  - Yuan, Xiaoping
A1  - Braun, Jean
A1  - Guerit, Laure
A1  - Simon, Brendan
A1  - Bovy, Benoît
A1  - Rouby, Delphine
A1  - Robin, Cécile
A1  - Jiao, R.
T1  - Linking continental erosion to marine sediment transport and deposition: A new implicit and O(N) method for inverse analysis
JF  - Earth & planetary science letters
N2  - The marine sedimentary record contains unique information about the history of erosion, uplift and climate of the adjacent continent. Inverting this record has been the purpose of many numerical studies. However, limited attention has been given to linking continental erosion to marine sediment transport and deposition in large-scale surface process evolution models. Here we present a new numerical method for marine sediment transport and deposition that is directly coupled to a landscape evolution algorithm solving for the continental fluvial and hillslope erosion equations using implicit and O(N) algorithms. The new method takes into account the sorting of grain sizes (e.g., silt and sand) in the marine domain using a non-linear multiple grain-size diffusion equation and assumes that the sediment flux exported from the continental domain is proportional to the bathymetric slope. Specific transport coefficients and compaction factors are assumed for the two different grain sizes to simulate the stratigraphic architecture. The resulting set of equations is solved using an efficient (O(N) and implicit) algorithm. It can thus be used to invert stratigraphic geometries using a Bayesian approach that requires a large number of simulations. This new method is used to invert the sedimentary geometry of a natural example, the Ogooue Delta (Gabon), over the last similar to 5 Myr. The objective is to unravel the set of erosional histories of the adjacent continental domain compatible with the observed geometry of the offshore delta. For this, we use a Bayesian inversion scheme in which the misfit function is constructed by comparing four geometrical parameters between the natural and the simulated delta: the volume of sediments stored in the delta, the surface slope, the initial and the final shelf lengths. We find that the best-fit values of the transport coefficients for silt in the marine domain are in the range of 300 - 500 m(2)/yr, in agreement with previous studies on offshore diffusion. We also show that, in order to fit the sedimentary geometry, erosion rate on the continental domain must have increased by a factor of 6 to 8 since 5.3 Ma. (C) 2019 Elsevier B.V. All rights reserved.
KW  - river erosion
KW  - sediment-transport model
KW  - efficient method
KW  - inverse analysis
KW  - the Ogooue Delta
Y1  - 2019
U6  - https://doi.org/10.1016/j.epsl.2019.115728
SN  - 0012-821X
SN  - 1385-013X
VL  - 524
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Buljak, Vladimir
A1  - Oesch, Tyler
A1  - Bruno, Giovanni
T1  - Simulating Fiber-Reinforced Concrete Mechanical Performance Using CT-Based Fiber Orientation Data
JF  - Materials
N2  - The main hindrance to realistic models of fiber-reinforced concrete (FRC) is the local materials property variation, which does not yet reliably allow simulations at the structural level. The idea presented in this paper makes use of an existing constitutive model, but resolves the problem of localized material variation through X-ray computed tomography (CT)-based pre-processing. First, a three-point bending test of a notched beam is considered, where pre-test fiber orientations are measured using CT. A numerical model is then built with the zone subjected to progressive damage, modeled using an orthotropic damage model. To each of the finite elements within this zone, a local coordinate system is assigned, with its longitudinal direction defined by local fiber orientations. Second, the parameters of the constitutive damage model are determined through inverse analysis using load-displacement data obtained from the test. These parameters are considered to clearly explain the material behavior for any arbitrary external action and fiber orientation, for the same geometrical properties and volumetric ratio of fibers. Third, the effectiveness of the resulting model is demonstrated using a second, control experiment. The results of the control experiment analyzed in this research compare well with the model results. The ultimate strength was predicted with an error of about 6%, while the work-of-load was predicted within 4%. It demonstrates the potential of this method for accurately predicting the mechanical performance of FRC components.
KW  - Fiber-reinforced concrete
KW  - X-ray computed tomography (CT)
KW  - anisotropic fiber orientation
KW  - inverse analysis
Y1  - 2019
U6  - https://doi.org/10.3390/ma12050717
SN  - 1996-1944
VL  - 12
IS  - 5
PB  - MDPI
CY  - Basel
ER  -