Global ETD Search

1	Computational Hydrosystem Analysis: Applications to the Meijiang and Nankou Catchments in China Sun, Feng 11 July 2011 (has links) (PDF) Hydrosystems are important elements of the hydraulic cycle. With population growth and climatic change impacting water resources, the existing water transport systems need to be reproduced in order to optimize the usage of the precious water resources. The individual flow process i.e. unsaturated soil flow and groundwater flow in porous and fractured media can be expressed by partial differential equations mathematically. The numerical models are generally used to give solutions of these equations with specific conditions. In this work, the numerical solutions are carried out using the scientific software OpenGeoSys (OGS) based on the finite element method. The complex geometrical structure model domain can be imported into the numerical model with an implemented graphical interface. A GIS based relational database model GeoHydroDataBase (GHDB) designed to create a specialized set of geo- and hydro-objects is integrated with the numerical model. The multi-field and detailed computational hydrosystem analysis methodology is applied to Meijiang catchment and Nankou site respectively. As an application, the case study for the Meijiang area with the focus on surface/subsurface water interaction and the recharge response from surface infiltration to groundwater with different time series discretization. In the Nankou case study, a 3-D regional groundwater flow model is developed. The hydrogeological system is reproduced according to sparsely distributed boreholes data. The model calibration and sensitivity analysis are accomplished with inverse methods by applying a model independent parameter estimation system (PEST). The results of the calibrated model show reasonable agreements with observed water levels. The transient groundwater flow simulations reflect the observed drawdown of the last 9 years and show the formation of a depression cone in an intensively pumped area. The well calibrated 3-D groundwater model provides hydrogeological parameters and lateral fluxes from the adjacent mountain area for the following transport modeling and remediation scenarios analysis. In this study the method of capture zone type curves is used to estimate the pumping rate and the number of pumping wells needed for the contaminated aquifer cleanup. The analytical solutions of drawdown at the pumping wells (for both single pumping well and double wells) are compared with those calculated from the numerical model. Computergestützte Hydrosystemanalyse Bewegung des Wassers in den Untergrund OGS PEST Meijiang Nankou China Computational Hydrosystem Analysis water movement in the subsurface OGS PEST Meijiang Nankou China ddc:550 rvk:RR 69354 rvk:AR 22140 rvk:AR 22350
2	Computational Hydrosystem Analysis: Applications to the Meijiang and Nankou Catchments in China Sun, Feng 24 June 2011 (has links) Hydrosystems are important elements of the hydraulic cycle. With population growth and climatic change impacting water resources, the existing water transport systems need to be reproduced in order to optimize the usage of the precious water resources. The individual flow process i.e. unsaturated soil flow and groundwater flow in porous and fractured media can be expressed by partial differential equations mathematically. The numerical models are generally used to give solutions of these equations with specific conditions. In this work, the numerical solutions are carried out using the scientific software OpenGeoSys (OGS) based on the finite element method. The complex geometrical structure model domain can be imported into the numerical model with an implemented graphical interface. A GIS based relational database model GeoHydroDataBase (GHDB) designed to create a specialized set of geo- and hydro-objects is integrated with the numerical model. The multi-field and detailed computational hydrosystem analysis methodology is applied to Meijiang catchment and Nankou site respectively. As an application, the case study for the Meijiang area with the focus on surface/subsurface water interaction and the recharge response from surface infiltration to groundwater with different time series discretization. In the Nankou case study, a 3-D regional groundwater flow model is developed. The hydrogeological system is reproduced according to sparsely distributed boreholes data. The model calibration and sensitivity analysis are accomplished with inverse methods by applying a model independent parameter estimation system (PEST). The results of the calibrated model show reasonable agreements with observed water levels. The transient groundwater flow simulations reflect the observed drawdown of the last 9 years and show the formation of a depression cone in an intensively pumped area. The well calibrated 3-D groundwater model provides hydrogeological parameters and lateral fluxes from the adjacent mountain area for the following transport modeling and remediation scenarios analysis. In this study the method of capture zone type curves is used to estimate the pumping rate and the number of pumping wells needed for the contaminated aquifer cleanup. The analytical solutions of drawdown at the pumping wells (for both single pumping well and double wells) are compared with those calculated from the numerical model. info:eu-repo/classification/ddc/550 ddc:550
3	Numerical modelling of multiple borehole heat exchanger array for sustainable utilisation of shallow geothermal energy Chen, Shuang 24 August 2022 (has links) A PhD dissertation which presented a numerical modelling study on the long-term behavior in the multiple borehole heat exchanger array system for sustainable utilisation of shallow geothermal energy. info:eu-repo/classification/ddc/621 ddc:621
4	Relationship between Facial Attractiveness and Occlusal Treatment Outcomes: A Retrospective Study Fowler, Chad Eric 01 January 2007 (has links) The goal of this study was to determine if a relationship exists between pretreatment facial attractiveness and posttreatment occlusal outcome in orthodontic patients. A randomized sample of forty-seven patients (26 males, 21 females) was selected for inclusion in this study. Orthodontic evaluators rated pretreatment patient photographs (frontal smile, frontal, profile) using a 100 mm visual analog scale (VAS). Occlusal outomes were evaluated using percentage reduction in weighted Peer Assessment Rating (PAR) index scores and the American Board of Orthodontics objective grading system (ABO-OGS). Spearman correlation coefficients were calculated to assess the relationship between pretreatment VAS attractiveness ratings and posttreatment occlusal scores. There was a fair correlation between facial attractiveness and reduction in weighted PAR index scores for all patients (r=.41, p<.01) and for male patients (r=.48, p<.05). The results showed a good correlation between facial attractiveness and the ABO-OGS for females (r=-.55, p<.05). facial attractiveness orthodontics treatment outcomes PAR index scores ABO-OGS scores Dentistry Medicine and Health Sciences Orthodontics and Orthodontology
5	Variable-Density Flow Processes in Porous Media On Small, Medium and Regional Scales Walther, Marc 03 November 2014 (has links) (PDF) Nowadays society strongly depends on its available resources and the long term stability of the surrounding ecosystem. Numerical modelling has become a general standard for evaluating past, current or future system states for a large number of applications supporting decision makers in proper management. In order to ensure the correct representation of the investigated processes and results of a simulation, verification examples (benchmarks), that are based on observation data or analytical solutions, are utilized to evaluate the numerical modelling tool. In many parts of the world, groundwater is an important resource for freshwater. While it is not only limited in quantity, subsurface water bodies are often in danger of contamination from various natural or anthropogenic sources. Especially in arid regions, marine saltwater intrusion poses a major threat to groundwater aquifers which mostly are the exclusive source of freshwater in these dry climates. In contrast to common numerical groundwater modelling, density-driven flow and mass transport have to be considered as vital processes in the system and in scenario simulations for fresh-saltwater interactions. In the beginning of this thesis, the capabilities of the modelling tool OpenGeoSys are verified with selected benchmarks to represent the relevant non-linear process coupling. Afterwards, variable-density application and process studies on different scales are presented. Application studies comprehend regional groundwater modelling of a coastal aquifer system extensively used for agricultural irrigation, as well as hydro-geological model development and parametrization. In two process studies, firstly, a novel method to model gelation of a solute in porous media is developed and verified on small scale laboratory observation data, and secondly, investigations of thermohaline double-diffusive Rayleigh regimes on medium scale are carried out. With the growing world population and, thus, increasing pressure on non-renewable resources, intelligent management strategies intensify demand for potent simulation tools and development of novel methods. In that way, this thesis highlights not only OpenGeoSys’ potential of density-dependent process modelling, but the comprehensive importance of variable-density flow and transport processes connecting, both, avant-garde scientific research, and real-world application challenges. Dichteabhängig Strömung Stofftransport Wärmetransport Grundwasser Numerische Simulation Finite-Elemente-Verfahren FEM OpenGeoSys OGS Open Source Benchmark IWAS Oman Al-Batinah Arid Fallstudie Viskosität Gel Dichte thermohaline Stabilität Variable-Density Density-Driven Density-Dependent Flow Mass Transport Heat Transport Numerical Simulation Finite-Element-Method FEM OpenGeoSys OGS Open Source Benchmark IWAS Oman Al-Batinah Case Study Arid Viscosity Gel Density Thermohaline Stability ddc:550 rvk:AR 22140 rvk:AR 22600 Grundwasser Finite-Elemente-Methode Viskosität Temperatur Transportprozess Simulation Dichte <Physik> Fallstudie Salzwasser-Süßwasser-Grenze Salzwasser Meerwasser Oman Open Source Benchmark Semiarides Gebiet Gel Stabilität
6	Variable-Density Flow Processes in Porous Media On Small, Medium and Regional Scales Walther, Marc 07 May 2014 (has links) Nowadays society strongly depends on its available resources and the long term stability of the surrounding ecosystem. Numerical modelling has become a general standard for evaluating past, current or future system states for a large number of applications supporting decision makers in proper management. In order to ensure the correct representation of the investigated processes and results of a simulation, verification examples (benchmarks), that are based on observation data or analytical solutions, are utilized to evaluate the numerical modelling tool. In many parts of the world, groundwater is an important resource for freshwater. While it is not only limited in quantity, subsurface water bodies are often in danger of contamination from various natural or anthropogenic sources. Especially in arid regions, marine saltwater intrusion poses a major threat to groundwater aquifers which mostly are the exclusive source of freshwater in these dry climates. In contrast to common numerical groundwater modelling, density-driven flow and mass transport have to be considered as vital processes in the system and in scenario simulations for fresh-saltwater interactions. In the beginning of this thesis, the capabilities of the modelling tool OpenGeoSys are verified with selected benchmarks to represent the relevant non-linear process coupling. Afterwards, variable-density application and process studies on different scales are presented. Application studies comprehend regional groundwater modelling of a coastal aquifer system extensively used for agricultural irrigation, as well as hydro-geological model development and parametrization. In two process studies, firstly, a novel method to model gelation of a solute in porous media is developed and verified on small scale laboratory observation data, and secondly, investigations of thermohaline double-diffusive Rayleigh regimes on medium scale are carried out. With the growing world population and, thus, increasing pressure on non-renewable resources, intelligent management strategies intensify demand for potent simulation tools and development of novel methods. In that way, this thesis highlights not only OpenGeoSys’ potential of density-dependent process modelling, but the comprehensive importance of variable-density flow and transport processes connecting, both, avant-garde scientific research, and real-world application challenges.:Abstract Zusammenfassung Nomenclature List of Figures List of Tables I Background and Fundamentals 1 Introduction 1.1 Motivation 1.2 Structure of the Thesis 1.3 Variable-Density Flow in Literature 2 Theory and Methods 2.1 Governing Equations 2.2 Fluid Properties 2.3 Modelling and Visualization Tools 3 Benchmarks 3.1 Steady-state Unconfined Groundwater Table 3.2 Theis Transient Pumping Test 3.3 Transient Saltwater Intrusion 3.4 Development of a Freshwater Lens II Applications 4 Extended Inverse Distance Weighting Interpolation 4.1 Motivation 4.2 Extension of IDW Method 4.3 Artificial Test and Regional Scale Application 4.4 Summary and Conclusions 5 Modelling Transient Saltwater Intrusion 5.1 Background and Motivation 5.2 Methods and Model Setup 5.3 Simulation Results and Discussion 5.4 Summary, Conclusion and Outlook 6 Gelation of a Dense Fluid 6.1 Motivation 6.2 Methods and Model Setup 6.3 Results and Conclusions 7 Delineating Double-Diffusive Rayleigh Regimes 7.1 Background and Motivation 7.2 Methods and Model Setup 7.3 Results 7.4 Conclusions and Outlook III Summary and Conclusions 8 Important Achievements 9 Conclusions and Outlook Bibliography Publications Acknowledgements Appendix info:eu-repo/classification/ddc/550 ddc:550

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