scholarly journals Coupled Geomechanical-Flow Assessment of CO2 Leakage through Heterogeneous Caprock during CCS

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Guan Woo Kim ◽  
Tae Hong Kim ◽  
Jiho Lee ◽  
Kun Sang Lee
Keyword(s):  
Carbon Capture ◽  
Homogeneous Model ◽  
Vertical Displacement ◽  
Tectonic Stress ◽  
Heterogeneous Model ◽  
Geomechanical Properties ◽  
Secure Storage ◽  
Heterogeneous Models ◽  
Fracture Reactivation ◽  
Carbon Capture Sequestration

The viability of carbon capture sequestration (CCS) is dependent on the secure storage of CO2 in subsurface geologic formations. Geomechanical failure of caprock is one of the main reasons of CO2 leakage from the storage formations. Through comprehensive assessment on the petrophysical and geomechanical heterogeneities of caprock, it is possible to predict the risk of unexpected caprock failure. To describe the fracture reactivation, the modified Barton–Bandis model is applied. In order to generate hydro-geomechanically heterogeneous fields, the negative correlation between porosity and Young’s modulus/Poisson’s ratio is applied. In comparison with the homogeneous model, effects of heterogeneity are examined in terms of vertical deformation and the amount of leaked CO2. To compare the effects of heterogeneity, heterogeneous models for both geomechanical and petrophysical properties in coupled simulation are designed. After 10-year injection with petrophysically heterogeneous and geomechanically homogeneous caprock, CO2 leakage is larger than that of the homogeneous model. In contrast, heterogeneity of geomechanical properties is shown to mitigate additional escape of CO2. Vertical displacement of every heterogeneous model is larger than homogeneous model. The model with compressive tectonic stress shows much more stable trapping with heterogeneous caprock, but there is possibility of rapid leakage after homogeneous caprock failure.

scholarly journals Homogeneous Approach for Composite Under Dynamic Contact With Friction

2007 ◽  
Author(s):  
Guillaume Peillex ◽  
Laurent Baillet ◽  
Yves Berthier
Keyword(s):  
Elastic Properties ◽  
Coulomb Friction ◽  
Homogeneous Model ◽  
Dynamic Contact ◽  
Stick Slip ◽  
Heterogeneous Model ◽  
Friction Law ◽  
Heterogeneous Models ◽  
The Matrix ◽  
Coulomb Friction Law

An explicit dynamic 2D finite element model of a composite under dynamic tribological loading is proposed. The software used for this kind of application manages contact conditions thanks to the Lagrange multipliers. The kind of contact is a deformable against rigid surface one. First of all due to ill-posedness of the classical Coulomb friction law, a regularized Coulomb friction law that allows local and global convergence of the models even under the presence of contact instabilities is proposed. This friction law is experimentally motivated and is similar to the simplified “Prakash-Clifton” law. In a second time the dynamic tribological behavior of the composite is studied by the mean of different models where the heterogeneities of the material are explicitly introduced. Those heterogeneous models stand for a description of the microscopic scale of the composite. A comparison is made between the results given by these heterogeneous models and the results obtained by the analysis of a homogeneous model. The elastic properties of the homogeneous model are obtained through classical homogenization process which is suitable here because the scale separation, difference between the size of the heterogeneities and the wavelength of the loading, is sufficiently important. The homogeneous model represents the macroscopic scale of the composite. Equivalence between heterogeneous models and the homogeneous one is straightforward if the contrast of Young’s modulus between the heterogeneities and the matrix is sufficiently low and if the local contact dynamic is stable. This equivalence has been observed for different contact instabilities like slip-separated, and stick-slip-separated ones. When the equivalence between the models is not ensured, because of high contrast of elastic properties for example, an adaptation of the dynamic parameter of the friction law is necessary to retrieve this equivalence. Finally the determination of the stresses and their evolution along the time in the heterogeneities and in the matrix is performed thanks to the relocalization process. This process is mixing dynamic analysis of the homogeneous models and fast static calculations on heterogeneous model. This process has already been applied to structures submitted to static loading but to our knowledge this is the first attempt to use it for dynamic contact problems. So this work highlights a full multi-scale approach for composite under dynamic contact with friction loading.

Capillary network structure does not affect theoretical analysis of glomerular size selectivity

1995 ◽  
Vol 268 (5) ◽  
pp. F972-F979
Author(s):  
A. Remuzzi ◽  
B. Ene-Iordache
Keyword(s):  
Pressure Drop ◽  
Homogeneous Model ◽  
Wistar Rat ◽  
Size Selectivity ◽  
Membrane Pore ◽  
Heterogeneous Model ◽  
Glomerular Size ◽  
The Difference ◽  
Membrane Pore Size ◽  
Log Normal

Anatomical studies have demonstrated that the glomerular capillaries are complex and heterogeneous networks. Conventional models of glomerular size selectivity, however, are based on the assumption of simplified geometries. We developed a theoretical model of glomerular size-selective function based on the geometric data obtained in a previous reconstruction of a glomerular network from a normal Munich-Wistar rat. This heterogeneous model was compared with the homogeneous model conventionally used to calculate membrane selective parameters from the fractional clearance of two test solutes, neutral dextran and Ficoll. For both models we assumed a hypothetical log-normal distribution of pore sizes and calculated optimal membrane pore-size parameters using previously published values of fractional clearances. The difference between the sieving coefficients calculated with the two models was negligible, never exceeding 5.5%. Since the homogeneous model does not consider the pressure drop along the glomerular capillary, we also computed fractional clearances with the homogeneous model, assuming the same pressure drop as in the heterogeneous one. The differences in computed fractional clearances using the homogeneous model with and without a pressure drop were less than 1.2%. We concluded that models based on identical capillary networks can therefore be used for interpreting sieving coefficients for macromolecules.

scholarly journals Process Knowledge Graph Modeling Techniques and Application Methods for Ship Heterogeneous Models

2021 ◽  
Author(s):  
Jinfeng Liu ◽  
Jianwei Dong ◽  
Xuwen Jing ◽  
Xuwu Cao ◽  
Chenxiao Du ◽  
...  
Keyword(s):  
Process Design ◽  
Welding Process ◽  
Mapping Method ◽  
Knowledge Graph ◽  
Case Based Reasoning ◽  
Test Model ◽  
Process Knowledge ◽  
Heterogeneous Model ◽  
Heterogeneous Models ◽  
Component Assembly

Abstract In the process design and reuse of marine component products, there are a lot of heterogeneous models, causing the problem that the process knowledge and process design experience contained in them are difficult to express and reuse. Therefore, a process knowledge representation model for ship heterogeneous model is proposed in this paper. Firstly, the multi-element process knowledge graph is constructed, and the heterogeneous ship model is described in a unified way. Then, the multi-strategy ontology mapping method is applied, and the semantic expression between the process knowledge graph and the entity model is realized. Finally, by obtaining implicit semantics based on case-based reasoning and checking the similarity of the matching results, the case knowledge reuse is achieved, to achieve rapid design of the process. This method provides reliable technical support for the design of ship component assembly and welding process, greatly shortens the design cycle, and improves the working efficiency. In addition, a case study of the test model is carried out to verify the feasibility and efficiency of the proposed method.

scholarly journals Intima heterogeneity in stress assessment of atherosclerotic plaques

2017 ◽  
Vol 8 (1) ◽  
pp. 20170008 ◽  
Author(s):  
Ali C. Akyildiz ◽  
Lambert Speelman ◽  
Bas van Velzen ◽  
Raoul R. F. Stevens ◽  
Antonius F. W. van der Steen ◽  
...  
Keyword(s):  
Sensitivity Analysis ◽  
Plaque Rupture ◽  
Homogeneous Model ◽  
Sensitivity Analyses ◽  
Homogeneous Material ◽  
Sensitivity Index ◽  
Stress Assessment ◽  
Heterogeneous Models ◽  
Homogeneous Models ◽  
Accuracy Stress

Atherosclerotic plaque rupture is recognized as the primary cause of cardiac and cerebral ischaemic events. High structural plaque stresses have been shown to strongly correlate with plaque rupture. Plaque stresses can be computed with finite-element (FE) models. Current FE models employ homogeneous material properties for the heterogeneous atherosclerotic intima. This study aimed to evaluate the influence of intima heterogeneity on plaque stress computations. Two-dimensional FE models with homogeneous and heterogeneous intima were constructed from histological images of atherosclerotic human coronaries ( n = 12). For homogeneous models, a single stiffness value was employed for the entire intima. For heterogeneous models, the intima was subdivided into four clusters based on the histological information and different stiffness values were assigned to the clusters. To cover the reported local intima stiffness range, 100 cluster stiffness combinations were simulated. Peak cap stresses (PCSs) from the homogeneous and heterogeneous models were analysed and compared. By using a global variance-based sensitivity analysis, the influence of the cluster stiffnesses on the PCS variation in the heterogeneous intima models was determined. Per plaque, the median PCS values of the heterogeneous models ranged from 27 to 160 kPa, and the PCS range varied between 43 and 218 kPa. On average, the homogeneous model PCS values differed from the median PCS values of heterogeneous models by 14%. A positive correlation ( R 2 = 0.72) was found between the homogeneous model PCS and the PCS range of the heterogeneous models. Sensitivity analysis showed that the highest main sensitivity index per plaque ranged from 0.26 to 0.83, and the average was 0.47. Intima heterogeneity resulted in substantial changes in PCS, warranting stress analyses with heterogeneous intima properties for plaque-specific, high accuracy stress assessment. Yet, computations with homogeneous intima assumption are still valuable to perform sensitivity analyses or parametric studies for testing the effect of plaque geometry on PCS. Moreover, homogeneous intima models can help identify low PCS, stable type plaques with thick caps. Yet, for thin cap plaques, accurate stiffness measurements of the clusters in the cap and stress analysis with heterogeneous cap properties are required to characterize the plaque stability.

scholarly journals SBML2Modelica: integrating biochemical models within open-standard simulation ecosystems

2019 ◽  
Vol 36 (7) ◽  
pp. 2165-2172 ◽  
Author(s):  
F Maggioli ◽  
T Mancini ◽  
E Tronci
Keyword(s):  
State Of The Art ◽  
General Purpose ◽  
Heterogeneous Model ◽  
Simulation Languages ◽  
Experimental Campaign ◽  
Heterogeneous Models ◽  
Open Standard ◽  
Level 3 ◽  
Model Networks ◽  
Definition Of

Abstract Motivation SBML is the most widespread language for the definition of biochemical models. Although dozens of SBML simulators are available, there is a general lack of support to the integration of SBML models within open-standard general-purpose simulation ecosystems. This hinders co-simulation and integration of SBML models within larger model networks, in order to, e.g. enable in silico clinical trials of drugs, pharmacological protocols, or engineering artefacts such as biomedical devices against Virtual Physiological Human models. Modelica is one of the most popular existing open-standard general-purpose simulation languages, supported by many simulators. Modelica models are especially suited for the definition of complex networks of heterogeneous models from virtually all application domains. Models written in Modelica (and in 100+ other languages) can be readily exported into black-box Functional Mock-Up Units (FMUs), and seamlessly co-simulated and integrated into larger model networks within open-standard language-independent simulation ecosystems. Results In order to enable SBML model integration within heterogeneous model networks, we present SBML2Modelica, a software system translating SBML models into well-structured, user-intelligible, easily modifiable Modelica models. SBML2Modelica is SBML Level 3 Version 2—compliant and succeeds on 96.47% of the SBML Test Suite Core (with a few rare, intricate and easily avoidable combinations of constructs unsupported and cleanly signalled to the user). Our experimental campaign on 613 models from the BioModels database (with up to 5438 variables) shows that the major open-source (general-purpose) Modelica and FMU simulators achieve performance comparable to state-of-the-art specialized SBML simulators. Availability and implementation SBML2Modelica is written in Java and is freely available for non-commercial use at https://bitbucket.org/mclab/sbml2modelica.

A Numerical Model for Studying the Effect of Plasma Layer on the Process of Blood Oxygenation in the Pulmonary Capillaries

1990 ◽  
Vol 112 (4) ◽  
pp. 457-463 ◽  
Author(s):  
Maithili Sharan ◽  
M. P. Singh ◽  
A. Aminataei
Keyword(s):  
Molecular Diffusion ◽  
Plasma Layer ◽  
Nonlinear Partial Differential Equations ◽  
Homogeneous Model ◽  
Blood Oxygenation ◽  
Facilitated Diffusion ◽  
Heterogeneous Model ◽  
The Core ◽  
Pulmonary Capillaries ◽  
Diffusion Convection

A two layer model for the blood oxygenation in pulmonary capillaries is proposed. The model consists of a core of erythrocytes surrounded by a symmetrically placed plasma layer. The governing equations in the core describe the free molecular diffusion, convection, and facilitated diffusion due to the presence of haemoglobin. The corresponding equations in the plasma layer are based on the free molecular diffusion and the convective effect of the blood. According to the axial train model for the blood flow proposed by Whitmore (1967), the core will move with a uniform velocity whereas flow in the plasma layer will be fully developed. The resulting system of nonlinear partial differential equations is solved numerically. A fixed point iterative technique is used to deal with the nonlinearities. The distance traversed by the blood before getting fully oxygenated is computed. It is shown that the concentration of O2 increases continuously along the length of the capillary for a given ratio of core radius to capillary radius. It is found that the rate of oxygenation increases as the core to capillary ratio decreases. The equilibration length increases with a heterogeneous model in comparison to that in a homogeneous model. The effect of capillary diameters and core radii on the rate of oxygenation has also been examined.

scholarly journals Analysis of ground deformation based on GPS in Sanshandao gold mine, China

2018 ◽  
Vol 55 (1) ◽  
pp. 7-14
Author(s):  
Fengshan Ma ◽  
Hongyu Gu ◽  
Jie Guo ◽  
Rong Lu
Keyword(s):  
Ground Deformation ◽  
Horizontal Displacement ◽  
Vertical Displacement ◽  
Mining Area ◽  
Tectonic Stress ◽  
Gold Mine ◽  
Motion Patterns ◽  
Metal Mine ◽  
Risk Areas ◽  
Discontinuous Deformation

Sanshandao Gold Mine is the first and largest mine operating below sea level in China. Mining has been practiced in this region for at least 25 years. In recent years, buildings above the mining area have been extensively damaged. GPS (with 315 monitoring points) was used to monitor the ground deformation since 2009. Ground deformation induced by mining is much more complex in metal mine than that in coal mines due to the well-developed joints, high tectonic stress and several intersecting faults. All of the factors are analyzed in this study. The results show that discontinuous deformation has occurred on the surface because of the sliding to F3 (name of fault), and there are two motion patterns of F3 during the mining process. Additionally, joints in rock masses with steep dip angles contribute to the vertical displacement and joints with shallow dip angles contribute to the horizontal displacement. Meanwhile, high tectonic stress dramatically enlarges the scale of ground deformation, especially with respect to the horizontal displacement. This deformation results in a striped formation of compressed and stretched regions. Additionally, high-risk and potential risk areas are identified in this study. Finally, the successive data measured since 2009 can contribute to a deeper understanding of ground deformation in metal mine.

Heat Transfer in Fixed Bed Elliptic Cylindrical Reactor via Two-Phase Model

2020 ◽  
Vol 400 ◽  
pp. 45-50
Author(s):  
Antonildo Santos Pereira ◽  
Rodrigo Moura da Silva ◽  
Maria Conceição Nóbrega Machado ◽  
Luan Pedro Melo Azerêdo ◽  
Anderson Ferreira Vilela ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Solid Phase ◽  
Homogeneous Model ◽  
Fixed Bed ◽  
Fluid Phase ◽  
Packed Bed ◽  
Two Phase ◽  
Heterogeneous Model ◽  
Fully Implicit ◽  
Cylindrical Reactor

The study of heat transfer in fixed bed tubular reactors of heated or cooled walls has presented great interest by the academy and industry. The adequate and safe design of such equipment requires the use of reliable and realistic mathematical. Unfortunately several studies are restrict to homogeneous model applied to circular and elliptic cylindrical reactors. Then, the objective of this work was to predict heat transfer in packed-bed elliptic cylindrical reactor, by using a proposed heterogeneous model. The mathematical model is composed for one solid phase and another fluid phase, in which the balance equation for each constituent is applied separately. The finite volume method was utilized to solve the partial differential equations using the WUDS scheme for interpolation of the convective and diffusive terms, and the fully implicit formulation. Results of the temperature distribution of the fluid and solid phases along the reactor are presented and analyzed. It was verified that the highest temperature gradients of the phases are located close to the wall and inlet of the reactor.

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