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200 results on '"Rieger W"'

3. Small Catchment Runoff Sensitivity to Station Density and Spatial Interpolation: Hydrological Modeling of Heavy Rainfall Using a Dense Rain Gauge Network

Author

Hohmann, C., Kirchengast, G., O, S., Rieger, W., and Foelsche, U.

Subjects
precipitation interpolation, extreme events, sensitivity analysis, Water supply for domestic and industrial purposes, spatial rainfall resolution, rain gauge network, precipitation variability, Hydraulic engineering, TC1-978, TD201-500, hydrological modeling
Abstract

Precipitation is the most important input to hydrological models, and its spatial variability can strongly influence modeled runoff. The highly dense station network WegenerNet (0.5 stations per km2) in southeastern Austria offers the opportunity to study the sensitivity of modeled runoff to precipitation input. We performed a large set of runoff simulations (WaSiM model) using 16 subnetworks with varying station densities and two interpolation schemes (inverse distance weighting, Thiessen polygons). Six representative heavy precipitation events were analyzed, placing a focus on small subcatchments (10–30 km2) and different event durations. We found that the modeling performance generally improved when the station density was increased up to a certain resolution: a mean nearest neighbor distance of around 6 km for long-duration events and about 2.5 km for short-duration events. However, this is not always true for small subcatchments. The sufficient station density is clearly dependent on the catchment area, event type, and station distribution. When the network is very dense (mean distance &lt, 1.7 km), any reasonable interpolation choice is suitable. Overall, the station density is much more important than the interpolation scheme. Our findings highlight the need to study extreme precipitation characteristics in combination with runoff modeling to decompose precipitation uncertainties more comprehensively.

Published
2021

7. Application of curvilinear higher order edge elements to scattering problems using the boundary element method

Author

Huber, C.J., Rieger, W., Haas, M., and Rucker, W.M.

Subjects
Scattering (Mathematics) -- Research, Boundary value problems -- Research, Electromagnetism -- Research, Business, Electronics, Electronics and electrical industries
Abstract

A boundary element method in terms of the field variables is applied to three-dimensional electromagnetic scattering problems. We propose higher order edge elements of quadrilateral shape for the field approximation on curved surfaces. The tangential components of the unknown field variables are interpolated by the edge element. The Galerkin method is implemented to obtain a set of linear equations. The applicability of the proposed edge element is investigated by the comparison of numerical results with analytical solutions. Index terms - Boundary element methods, electromagnetic scattering

Published
1999

8. A boundary element formulation using higher order curvilinear edge elements

Author

Huber, C.J., Rieger, W., Haas, M., and Rucker, W.M.

Subjects
Magnetostatics -- Research, Magnetic fields -- Research, Coordinates, Curvilinear -- Research, Business, Electronics, Electronics and electrical industries
Abstract

A boundary element method in terms of the field variable is applied to three-dimensional magnetostatic problems. We propose higher order edge elements of quadrilateral shape for the field approximation on curved surfaces. The tangential component of the unknown field variable is interpolated by the edge element. The Galerkin method is implemented to obtain a set of linear equations. The applicability of the proposed edge element is investigated by TEAM Workshop problem 13 assuming linear material properties. Index terms - Edge elements, magnetic fields, boundary element method, singular integrals.

Published
1998

46. Two-dimensional electron gases induced by spontaneous and piezoelectric polarization charges in N- and Ga-face AlGaN/GaN heterostructures

Author

Ambacher, O., primary, Smart, J., additional, Shealy, J. R., additional, Weimann, N. G., additional, Chu, K., additional, Murphy, M., additional, Schaff, W. J., additional, Eastman, L. F., additional, Dimitrov, R., additional, Wittmer, L., additional, Stutzmann, M., additional, Rieger, W., additional, and Hilsenbeck, J., additional

Published
1999
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