scholarly journals A Field Evidence Model: How to Predict Transport in a Heterogeneous Aquifers at Low Investigation Level?

2020 ◽  
Author(s):  
Alraune Zech ◽  
Peter Dietrich ◽  
Sabine Atttinger ◽  
Georg Teutsch
Keyword(s):  
Large Scale ◽  
Transport Model ◽  
Numerical Models ◽  
Structural Parameters ◽  
Structural Complexity ◽  
Monitoring Cost ◽  
Heterogeneous Aquifers ◽  
Field Evidence ◽  
Starting Point ◽  
Evidence Model

Abstract. Aquifer heterogeneity in combination with data scarcity is a major challenge for reliable solute transport prediction. Velocity fluctuations cause non-regular plume shapes with potentially long tailing and/or fast traveling mass fractions. High monitoring cost and presumably missing simple concepts have limited the incorporation of heterogeneity to many field transport models up to now. We present a hierarchical aquifer model which combines large-scale deterministic structures and simple stochastic approaches. Such a heterogeneous conductivity can easily be integrated into a numerical models. Depending on the modeling aim, the required structural complexity can be adapted. The same holds for the amount of available field data. The conductivity model is constructed step-wise following field evidence from observations; though relying on as minimal data as possible. Starting point are deterministic blocks, derived from head profiles and pumping tests. Then, sub-scale heterogeneity in form of random binary inclusions are introduced to each block. Structural parameters can be determined e.g. from flowmeter measurements. As proof of concept, we implemented a predictive transport model for the heterogeneous MADE site. The proposed hierarchical aquifer structure reproduces the plume development of the MADE-1 transport experiment without calibration. Thus, classical ADE models are able to describe highly skewed tracer plumes by incorporating deterministic contrasts and effects of connectivity in a stochastic way even without using uni-modal heterogeneity models with high variances. The reliance of the conceptual model on few observations makes it appealing for a goal-oriented site specific transport analysis of less well investigated heterogeneous sites.

scholarly journals A field evidence model: how to predict transport in heterogeneous aquifers at low investigation level

2021 ◽  
Vol 25 (1) ◽  
pp. 1-15
Author(s):  
Alraune Zech ◽  
Peter Dietrich ◽  
Sabine Attinger ◽  
Georg Teutsch
Keyword(s):  
Large Scale ◽  
Transport Model ◽  
Structural Parameters ◽  
Structural Complexity ◽  
Model Complexity ◽  
Monitoring Cost ◽  
Transport Modelling ◽  
Aquifer Heterogeneity ◽  
Field Evidence ◽  
Starting Point

Abstract. Aquifer heterogeneity in combination with data scarcity is a major challenge for reliable solute transport prediction. Velocity fluctuations cause non-regular plume shapes with potentially long-tailing and/or fast-travelling mass fractions. High monitoring cost and a shortage of simple concepts have limited the incorporation of heterogeneity into many field transport models up to now. We present an easily applicable hierarchical conceptualization strategy for hydraulic conductivity to integrate aquifer heterogeneity into quantitative flow and transport modelling. The modular approach combines large-scale deterministic structures with random substructures. Depending on the modelling aim, the required structural complexity can be adapted. The same holds for the amount of monitoring data. The conductivity model is constructed step-wise following field evidence from observations, seeking a balance between model complexity and available field data. The starting point is a structure of deterministic blocks, derived from head profiles and pumping tests. Then, subscale heterogeneity in the form of random binary inclusions is introduced to each block. Structural parameters can be determined, for example, from flowmeter measurements or hydraulic profiling. As proof of concept, we implemented a predictive transport model for the heterogeneous MADE site. The proposed hierarchical aquifer structure reproduces the plume development of the MADE-1 transport experiment without calibration. Thus, classical advection–dispersion equation (ADE) models are able to describe highly skewed tracer plumes by incorporating deterministic contrasts and effects of connectivity in a stochastic way without using uni-modal heterogeneity models with high variances. The reliance of the conceptual model on few observations makes it appealing for a goal-oriented site-specific transport analysis of less well investigated heterogeneous sites.

scholarly journals INVESTIGATIONS ON SCOUR DEVELOPMENT AT TRIPOD FOUNDATIONS FOR OFFSHORE WIND TURBINES: MODELING AND APPLICATION

2012 ◽  
Vol 1 (33) ◽  
pp. 90 ◽  
Author(s):  
Arne Stahlmann ◽  
Torsten Schlurmann
Keyword(s):  
Large Scale ◽  
Mechanical Stability ◽  
Transport Model ◽  
Structural Parameters ◽  
Complex Structure ◽  
Wind Farms ◽  
Point Of View ◽  
Offshore Wind ◽  
Offshore Wind Farms ◽  
Physical Model Tests

Regarding offshore constructions, there is still a lack in knowledge of scour progression for complex structures like foundations for offshore wind energy converters at present, which is however necessary for its dimensioning. As an example of such complex structure types, tripod foundations are constructed in German offshore wind farms at present. In order to describe physical processes and influencing factors on scour progression from a scientific point of view, comprehensive investigations on the scouring phenomena for tripod foundations have been carried out and will be partly presented here. The overall investigation method consists of a combination of 1:40 small and 1:12 large scale physical model tests in wave flumes, numerical simulations using CFD methods and in-situ measured scour data. For the numerical modeling part, a sediment transport model formulation has been implemented into OpenFOAM software code. The results show a general variability of scour depending on the load boundary conditions and structural parameters. Scours occur both at the foundation piles and directly under the structure, which in this form could not be predicted using standard approaches, but which has to be taken into account when regarding the soil mechanical stability and the final dimensioning of the foundations.

scholarly journals Numerical Modeling of the Hydro-Morphodynamics of a Distributary Channel of the Po River Delta (Italy) during the Spring 2009 Flood Event

Geosciences ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 209 ◽  
Author(s):  
Michael Nones ◽  
Vittorio Maselli ◽  
Arianna Varrani
Keyword(s):  
Large Scale ◽  
Numerical Models ◽  
River Delta ◽  
Flood Event ◽  
Po River ◽  
Modeling Tools ◽  
Field Evidence ◽  
River Hydraulics ◽  
Flooding Event ◽  
Distributary Channel

One-dimensional (1D) numerical models generally provide reliable results when applied to simulate river hydraulics and morphodynamics upstream of the tidal influence, given the predominantly unidirectional flow conditions. Such models, however, can also be used to reproduce river hydraulics across the fluvial to marine transition zone when specific conditions occur, as during high discharge events, and the results obtained via these simple modeling tools can provide indicative trends that may guide more structured and detailed modeling of a particularly critical area. In this study, the application of a 1D model setup with hydrologic engineering centers river analysis system (HEC-RAS) for simulating the hydro-morphodynamic conditions of a distributary channel of the Po River Delta (Italy) during a flooding event that occurred in Spring 2009 is presented. The channel bathymetry and the grainsize composition was taken from field measurements, while the dimension of the plume offshore the delta was derived from a MODIS image acquired at the peak of the flood. The comparison between the numerical outcomes and the field evidence shows the reliability of the proposed 1D modeling approach in representing the delta dynamics at a large scale, as well as in showing locations where more spatially detailed studies are needed. The code was also able to adequately reproduce the channel hydro-morphodynamics and the sediment data as derived from a core sample taken a few km offshore during the flooding event of April–May 2009. Through a sensitivity analysis, it is also proven that the dimension of the river plume can influence the evolution of the prodelta, while having a rather negligible effect inland, because of the major stresses induced by the high river discharge during the flood event.

Use of CFD Tools in Internal Deflector Design for Cross Flow Turbine Efficiency Improvement

2012 ◽  
Author(s):  
Sergio D. Croquer ◽  
Jesus de Andrade ◽  
Jorge Clarembaux ◽  
Freddy Jeanty ◽  
Miguel Asuaje
Keyword(s):  
Power Plants ◽  
Large Scale ◽  
Numerical Models ◽  
Fluid Dynamic ◽  
Cross Flow ◽  
Small Scale ◽  
Efficiency Improvement ◽  
Hydropower Generation ◽  
Turbine Efficiency ◽  
Starting Point

Cross Flow Turbines (CFT), also known as Banki or Ossberger turbines are broadly used in small scale hydropower generation. Easy construction and operation, low CAPEX and OPEX and fairly independent efficiency from flow rate are the main characteristics of the CFT. However, they also tend to have a modest efficiency (80%), hence they are not considered for large scale power plants. Previous work have focused on use of Internal Deflectors (ID) for CFT efficiency improvement. However experimental flow observation and characterization inside CFT is hard to achieve. This work proposes use of Computational Fluid Dynamic (CFD) tools as an aid in ID design. A transient regime, two-dimensional, numerical model of a CFT without any internal deflectors was carried out. Deviation from experimental results at BEP was close to 5%. CFT w/o ID results were used as ID design starting point. Parameters: Upper Blade Position and ID Length were defined and varied obtaining six different ID versions. Numerical models were carried out for evaluation of ID effect on CFT. CFT hydraulic efficiency improvement was achieved for all ID versions studied (range 0.5%–3%, average:1.9%). Output power was also augmented (range 0.3%–4%, average:2.5%)for all cases.

Identification of N-Substituted Triazolo-azetidines as Novel Antibacterials using pDualrep2 HTS Platform

2019 ◽  
Vol 22 (5) ◽  
pp. 346-354
Author(s):  
Yan A. Ivanenkov ◽  
Renat S. Yamidanov ◽  
Ilya A. Osterman ◽  
Petr V. Sergiev ◽  
Vladimir A. Aladinskiy ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Large Scale ◽  
Underlying Mechanism ◽  
Luciferase Assay ◽  
Reporter System ◽  
E Coli ◽  
Starting Point ◽  
High Concentrations ◽  
Mic Value

Aim and Objective: Antibiotic resistance is a serious constraint to the development of new effective antibacterials. Therefore, the discovery of the new antibacterials remains one of the main challenges in modern medicinal chemistry. This study was undertaken to identify novel molecules with antibacterial activity. Materials and Methods: Using our unique double-reporter system, in-house large-scale HTS campaign was conducted for the identification of antibacterial potency of small-molecule compounds. The construction allows us to visually assess the underlying mechanism of action. After the initial HTS and rescreen procedure, luciferase assay, C14-test, determination of MIC value and PrestoBlue test were carried out. Results: HTS rounds and rescreen campaign have revealed the antibacterial activity of a series of Nsubstituted triazolo-azetidines and their isosteric derivatives that has not been reported previously. Primary hit-molecule demonstrated a MIC value of 12.5 µg/mL against E. coli Δ tolC with signs of translation blockage and no SOS-response. Translation inhibition (26%, luciferase assay) was achieved at high concentrations up to 160 µg/mL, while no activity was found using C14-test. The compound did not demonstrate cytotoxicity in the PrestoBlue assay against a panel of eukaryotic cells. Within a series of direct structural analogues bearing the same or bioisosteric scaffold, compound 2 was found to have an improved antibacterial potency (MIC=6.25 µg/mL) close to Erythromycin (MIC=2.5-5 µg/mL) against the same strain. In contrast to the parent hit, this compound was more active and selective, and provided a robust IP position. Conclusion: N-substituted triazolo-azetidine scaffold may be used as a versatile starting point for the development of novel active and selective antibacterial compounds.

scholarly journals Urban Policies and Large Projects in Central City Areas: The Example of Madrid (Spain)

Urban Science ◽  
2021 ◽  
Vol 5 (2) ◽  
pp. 42
Author(s):  
Dolores Brandis García
Keyword(s):  
Urban Planning ◽  
20Th Century ◽  
Large Scale ◽  
Central City ◽  
Global Market ◽  
Late 20Th Century ◽  
Public And Private ◽  
Urban Policies ◽  
Starting Point ◽  
The City

Since the late 20th century major, European cities have exhibited large projects driven by neoliberal urban planning policies whose aim is to enhance their position on the global market. By locating these projects in central city areas, they also heighten and reinforce their privileged situation within the city as a whole, thus contributing to deepening the centre–periphery rift. The starting point for this study is the significance and scope of large projects in metropolitan cities’ urban planning agendas since the final decade of the 20th century. The aim of this article is to demonstrate the correlation between the various opposing conservative and progressive urban policies, and the projects put forward, for the city of Madrid. A study of documentary sources and the strategies deployed by public and private agents are interpreted in the light of a process during which the city has had a succession of alternating governments defending opposing urban development models. This analysis allows us to conclude that the predominant large-scale projects proposed under conservative policies have contributed to deepening the centre–periphery rift appreciated in the city.

scholarly journals Vanadium Redox Flow Batteries: A Review Oriented to Fluid-Dynamic Optimization

Energies ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 176
Author(s):  
Iñigo Aramendia ◽  
Unai Fernandez-Gamiz ◽  
Adrian Martinez-San-Vicente ◽  
Ekaitz Zulueta ◽  
Jose Manuel Lopez-Guede
Keyword(s):  
Large Scale ◽  
Numerical Models ◽  
Fluid Dynamic ◽  
Renewable Energy Sources ◽  
Vanadium Redox Flow Battery ◽  
Redox Flow Batteries ◽  
Design Flexibility ◽  
Flow Batteries ◽  
Exchange Membrane ◽  
Vanadium Redox

Large-scale energy storage systems (ESS) are nowadays growing in popularity due to the increase in the energy production by renewable energy sources, which in general have a random intermittent nature. Currently, several redox flow batteries have been presented as an alternative of the classical ESS; the scalability, design flexibility and long life cycle of the vanadium redox flow battery (VRFB) have made it to stand out. In a VRFB cell, which consists of two electrodes and an ion exchange membrane, the electrolyte flows through the electrodes where the electrochemical reactions take place. Computational Fluid Dynamics (CFD) simulations are a very powerful tool to develop feasible numerical models to enhance the performance and lifetime of VRFBs. This review aims to present and discuss the numerical models developed in this field and, particularly, to analyze different types of flow fields and patterns that can be found in the literature. The numerical studies presented in this review are a helpful tool to evaluate several key parameters important to optimize the energy systems based on redox flow technologies.

scholarly journals Process-Based Model Prediction of Coastal Dune Erosion through Parametric Calibration

2021 ◽  
Vol 9 (6) ◽  
pp. 635
Author(s):  
Hyeok Jin ◽  
Kideok Do ◽  
Sungwon Shin ◽  
Daniel Cox
Keyword(s):  
Large Scale ◽  
Numerical Models ◽  
Model Performance ◽  
Coastal Dunes ◽  
Wave Transformation ◽  
Storm Event ◽  
Face Model ◽  
Dune Erosion ◽  
Simulation Performance ◽  
Sand Bar

Coastal dunes are important morphological features for both ecosystems and coastal hazard mitigation. Because understanding and predicting dune erosion phenomena is very important, various numerical models have been developed to improve the accuracy. In the present study, a process-based model (XBeachX) was tested and calibrated to improve the accuracy of the simulation of dune erosion from a storm event by adjusting the coefficients in the model and comparing it with the large-scale experimental data. The breaker slope coefficient was calibrated to predict cross-shore wave transformation more accurately. To improve the prediction of the dune erosion profile, the coefficients related to skewness and asymmetry were adjusted. Moreover, the bermslope coefficient was calibrated to improve the simulation performance of the bermslope near the dune face. Model performance was assessed based on the model-data comparisons. The calibrated XBeachX successfully predicted wave transformation and dune erosion phenomena. In addition, the results obtained from other two similar experiments on dune erosion with the same calibrated set matched well with the observed wave and profile data. However, the prediction of underwater sand bar evolution remains a challenge.

scholarly journals Contracting in land and natural resources: a tale of exclusion

2021 ◽  
Vol 17 (1) ◽  
pp. 145-153
Author(s):  
Federica Violi
Keyword(s):  
Natural Resources ◽  
Large Scale ◽  
Sustainable Development Goals ◽  
Host Countries ◽  
Developmental Needs ◽  
Starting Point ◽  
The World ◽  
Development Goals ◽  
Short Essay ◽  
Public Environment

By browsing the website of Land Matrix, one can measure the extent of land-related large-scale investments in natural resources (LRINRs) and place it on the world map. At the time of writing, the extent of these investments covers an area equal to the surfaces of Spain and Portugal together – or, for football fans, around 60 million football pitches. These investment operations have often been saluted as instrumental to achieve the developmental needs of host countries and as the necessary private counterpart to state (and interstate) efforts aimed at (sustainable) development goals. Yet, the realities on the ground offer a scenario characterised by severe instances of displacement of indigenous or local communities and environmental disruptions. The starting point of this short essay is that these ‘externalities’ are generated through the legal construct enabling the implementation of these investment operations. As such, this contribution lies neatly in the line of research set forth in the excellent books of Kinnari Bhatt and Jennifer Lander, from the perspective of both the development culture shaping these investment operations and the private–public environment in which these are situated. The essay tries and dialogues with both components, while focusing at a metalevel on the theoretical shifts potentially geared to turn a ‘tale of exclusion’ into a ‘tale of inclusion’.

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