Suchergebnisse

The problem of parametrization of the eddy fluxes of a potential vorticity is discussed. Traditional diffusion parameterization is complemented by the inclusion of a rotational component. For the analysis of the new scheme, a quasi-geostrophic model of the dynamics of the barotropic flow in a zonal channel with a non-uniform bottom is used. An analytical solution of the problem is found and the influence of topography on the flow disturbances is discussed. It is shown that the equation for the eddy potential enstrophy allows to relate diffusion and «rotational» coefficients.

The aim of this research is to estimate the sediment yield in the Pirapama River Basin and in the area of contribution of the Pirapama Reservoir and to identify areas susceptible to soil erosion for identification of critical erosion watersheds during the period from 2000 to 2010. This study was conducted to design a framework for evaluating and identifying critical erosion in Pirapama watershed, based on the tolerable erosion concept, by using the Soil and Water Assessment Tool (SWAT) model. SWAT was calibrated and validated for two streamflow stations (Cachoeira Tapada and Destilaria Inexport) for the period from 2000 to 2010. The results show that the simulated data for Cachoeira Tapada station were considered good (NS = 0.68 and R² = 0.71) and very good (PBIAS = 1.46%). Regarding the statistical data in the validation, the values of NS (0.67), R² (0.85), and PBIAS (19.18%) were considered good, very good, and satisfactory, respectively. The statistical data obtained in the calibration of the model for the fluviometric station Destilaria Inexport indicated that the simulated data are considered very good, with R² = 0.84, NS = 0.81, and PBIAS = 2.33%. In the validation, the statistics showed values consistent with the literature, with NS = 0.72, R² = 0.86, and PBIAS = –19.11%, which are considered good, very good, and satisfactory, respectively. The estimated average sediment yield in the Pirapama River basin ranged from 0.10 to 129.90 ton/ha.year. The results of the sediment yield estimates in the contribution area of the Pirapama Reservoir showed that the mean sediment yield of the sub-basins upstream of the Pirapama Reservoir was 61.49 ton/ha.year for the period analysed. According to the annual estimates performed, 5.59 ton/ha.year of this amount reaches the Pirapama Reservoir, which corresponds to 9% of the soil losses incident in the area. Thus, the sub-basins upstream of the Pirapama Reservoir were identified as portions of the basin that are susceptible to the erosion process. Sediment yield in these portions can interfere with the volume of water of the Pirapama Reservoir when the eroded material is carried to the depth of the lake.

Abstract. We present a downscaling approach for the study of wave-induced extreme water levels at a location on a barrier island in Yucatán (Mexico). Wave information from a 30-year wave hindcast is validated with in situ measurements at 8 m water depth. The maximum dissimilarity algorithm is employed for the selection of 600 representative cases, encompassing different combinations of wave characteristics and tidal level. The selected cases are propagated from 8 m water depth to the shore using the coupling of a third-generation wave model and a phase-resolving non-hydrostatic nonlinear shallow-water equation model. Extreme wave run-up, R2%, is estimated for the simulated cases and can be further employed to reconstruct the 30-year time series using an interpolation algorithm. Downscaling results show run-up saturation during more energetic wave conditions and modulation owing to tides. The latter suggests that the R2% can be parameterized using a hyperbolic-like formulation with dependency on both wave height and tidal level. The new parametric formulation is in agreement with the downscaling results (r2  =  0.78), allowing a fast calculation of wave-induced extreme water levels at this location. Finally, an assessment of beach vulnerability to wave-induced extreme water levels is conducted at the study area by employing the two approaches (reconstruction/parameterization) and a storm impact scale. The 30-year extreme water level hindcast allows the calculation of beach vulnerability as a function of return periods. It is shown that the downscaling-derived parameterization provides reasonable results as compared with the numerical approach. This methodology can be extended to other locations and can be further improved by incorporating the storm surge contributions to the extreme water level.

[EN] There are numerous passive strategies for reducing energy consumption in Spanish traditional vernacular architecture, depending on external conditions and also on the intended use of the interior of these constructions. In the case study analyzed, localized in an interior area of Spain, known as La Mancha, a set of vernacular buildings have been studied. Solar protection and solar gain, for example, are the key resources related to solar control. While cross ventilation, self-ventilation, or induced ventilation are related to the energy efficiency of the airflow. Other mechanisms identified are, for example, thermal insulation and thermal inertia of the materials. All these K-factors have been checked and parameterized in order to understand these vernacular strategies. Finally, thanks to a comparison of such resources, the study achieved a set of criteria for the use of these solutions in contemporary local architecture. ; The authors would like to thank the European Union framework 7th program for making this work possible via the LIMA project as well as to the following fellowships: The R&D FPI-UPV (P.A.I.D. program of the Universitat Politecnica de Valencia) and the FPU by the Spanish Ministerio de Educacion, Cultura y Deporte. ; Cristini ., V.; Ruiz Checa, JR.; Higón Calvet, JL.; Palmero Iglesias, LM. (2015). Passive energy saving strategies in vernacular architecture: parameterization of resources applied to a case study. WIT Transactions on the Built Environment (Online). 153:287-297. https://doi.org/10.2495/STR150241 ; S ; 287 ; 297 ; 153

This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 668119 (project "IDentiFY"). We thank Dr. Reiner Zorn for helpful comments on his article [7]; Dr. Oliver Neudert and Dr. Carlos Mattea for introduction to the field-cycling relaxometry and their suggestions about a test sample; and Prof. Dr. Michael Vogel for permission to use the 7Li stimulated-echo data. ; Peer reviewed ; Publisher PDF

287 297 153 ; S ; [EN] There are numerous passive strategies for reducing energy consumption in Spanish traditional vernacular architecture, depending on external conditions and also on the intended use of the interior of these constructions. In the case study analyzed, localized in an interior area of Spain, known as La Mancha, a set of vernacular buildings have been studied. Solar protection and solar gain, for example, are the key resources related to solar control. While cross ventilation, self-ventilation, or induced ventilation are related to the energy efficiency of the airflow. Other mechanisms identified are, for example, thermal insulation and thermal inertia of the materials. All these K-factors have been checked and parameterized in order to understand these vernacular strategies. Finally, thanks to a comparison of such resources, the study achieved a set of criteria for the use of these solutions in contemporary local architecture. The authors would like to thank the European Union framework 7th program for making this work possible via the LIMA project as well as to the following fellowships: The R&D FPI-UPV (P.A.I.D. program of the Universitat Politecnica de Valencia) and the FPU by the Spanish Ministerio de Educacion, Cultura y Deporte.

The definitive version is available at: http://www3.interscience.wiley.com/journal/4125/home ; This paper examines a model for estimating canopy resistance rc and reference evapotranspiration ETo on an hourly basis. The experimental data refer to grass at two sites in Spain with semiarid and windy conditions in a typical Mediterranean climate. Measured hourly ETo values were obtained over grass during a 4 year period between 1997 and 2000 using a weighing lysimeter (Zaragoza, northeastern Spain) and an eddy covariance system (Córdoba, southern Spain). The present model is based on the Penman-Monteith (PM) approach, but incorporates a variable canopy resistance rc as an empirical function of the square root of a climatic resistance r* that depends on climatic variables. Values for the variable rc were also computed according to two other approaches: with the rc variable as a straight-line function of r* (Katerji and Perrier, 1983, Agronomie 3(6): 513-521) and as a mechanistic function of weather variables as proposed by Todorovic (1999, Journal of Irrigation and Drainage Engineering, ASCE 125(5): 235-245). In the proposed model, the results show that rc/ra (where ra is the aerodynamic resistance) presents a dependence on the square root of r*/ra, as the best approach with empirically derived global parameters. When estimating hourly ETo values, we compared the performance of the PM equation using those estimated variable rc values with the PM equation as proposed by the Food and Agriculture Organization, with a constant rc = 70 s m-1. The results confirmed the relative robustness of the PM method with constant rc, but also revealed a tendency to underestimate the measured values when ETo is high. Under the semiarid conditions of the two experimental sites, slightly better estimates of ETo were obtained when an estimated variable rc was used. Although the improvement was limited, the best estimates were provided by the Todorovic and the proposed methods. The proposed approach for rc as a function of the square root of r* may be considered as an alternative for modelling rc, since the results suggest that the global coefficients of this locally calibrated relationship might be generalized to other climatic regions. It may also be useful to incorporate the effects of variable canopy resistances into other climatic and hydrological models. ; This work was funded by the Spanish Ministry of Science and Technology under project REN2001-1630/CLI and by the Department of Universities and Research (Generalitat de Catalunya) under project 2001SGR-00306- The second author was also supported by a fellowship from the High Council of Research and Development of the Autnomous Government of Aragon. ; Peer reviewed

This paper examines a model for estimating canopy resistance rc and reference evapotranspiration ETo on an hourly basis. The experimental data refer to grass at two sites in Spain with semiarid and windy conditions in a typical Mediterranean climate. Measured hourly ETo values were obtained over grass during a 4 year period between 1997 and 2000 using a weighing lysimeter (Zaragoza, northeastern Spain) and an eddy covariance system (Córdoba, southern Spain). The present model is based on the Penman-Monteith (PM) approach, but incorporates a variable canopy resistance rc as an empirical function of the square root of a climatic resistance r* that depends on climatic variables. Values for the variable rc were also computed according to two other approaches: with the rc variable as a straight-line function of r* (Katerji and Perrier, 1983, Agronomie 3(6): 513-521) and as a mechanistic function of weather variables as proposed by Todorovic (1999, Journal of Irrigation and Drainage Engineering, ASCE 125(5): 235-245). In the proposed model, the results show that rc/ra (where ra is the aerodynamic resistance) presents a dependence on the square root of r*/ra, as the best approach with empirically derived global parameters. When estimating hourly ETo values, we compared the performance of the PM equation using those estimated variable rc values with the PM equation as proposed by the Food and Agriculture Organization, with a constant rc = 70 s m-1. The results confirmed the relative robustness of the PM method with constant rc, but also revealed a tendency to underestimate the measured values when ETo is high. Under the semiarid conditions of the two experimental sites, slightly better estimates of ETo were obtained when an estimated variable rc was used. Although the improvement was limited, the best estimates were provided by the Todorovic and the proposed methods. The proposed approach for rc as a function of the square root of r* may be considered as an alternative for modelling rc, since the results suggest that the global coefficients of this locally calibrated relationship might be generalized to other climatic regions. It may also be useful to incorporate the effects of variable canopy resistances into other climatic and hydrological models. ; Spanish Ministry of Science and Technology. Grant Number: REN2001‐1630/CLI Department of Universities and Research (Generalitat de Catalunya). Grant Number: 2001SGR‐00306 High Council of Research and Development of the Autonomous Government of Aragon

Abstract. The mesoscale meteorological model MM5 is applied to 22 selected days with intense precipitation in the region of Epirus, NW Greece. At first, it was investigated whether and to what extend an increased horizontal resolution (from 8 to 2 km) improves the quantitative precipitation forecasts. The model skill was examined for the 12-h accumulated precipitation recorded at 14 meteorological stations located in Epirus and by using categorical and descriptive statistics. Then, the precipitation forecast skill for the 2 km grid was studied: (a) without and (b) with the activation of a convective parameterization scheme. From the above study, the necessity of the use of a scheme at the 2 km grid is assessed. Furthermore, three different convective parameterization schemes are compared: (a) Betts-Miller, (b) Grell and (c) Kain-Fritsch-2 in order to reveal the scheme, resulting in the best precipitation forecast skill in Epirus. Kain-Fritsch-2 and Grell give better results with the latter being the best for the high precipitation events.

Ereignisdiskrete Simulationsmodelle im betriebsbegleitenden Einsatz der Produktion werden genutzt, um die Ausbringungsmenge oder die benötigten Komponenten innerhalb eines bestimmten Zeitraums vorherzusagen. Für valide Simulationsergebnisse muss die Simulation die Realität ausreichend genau abbilden. Das vorgestellte System (MWS4SimPar) nutzt einen datengesteuerten Ansatz zur Erkennung von Abweichungen zwischen Simulation und realem System sowie ein Wissensmanagement, um die Abweichungen anzupassen.
 
Discrete-event simulation models are used in a production environment to predict the output quantity or the required components within a certain period. For this purpose, the simulation must represent the real system with sufficiently accuracy to obtain valid results. The presented system (MWS4SimPar) uses a data-driven approach to detect deviations between simulation and real system and a knowledge management system to adjust the deviations.

Abstract. Avalanches and subaqueous debris flows are two cases of a wide range of natural hazards that have been previously modeled with non-Newtonian fluid mechanics approximating the interplay of forces associated with gravity flows of granular and solid–liquid mixtures. The complex behaviors of such flows at unsteady flow initiation (i.e., destruction of structural jamming) and flow stalling (restructuralization) imply that the representative viscosity–stress relationships should include hysteresis: there is no reason to expect the timescale of microstructure destruction is the same as the timescale of restructuralization. The non-Newtonian Herschel–Bulkley relationship that has been previously used in such models implies complete reversibility of the stress–strain relationship and thus cannot correctly represent unsteady phases. In contrast, a thixotropic non-Newtonian model allows representation of initial structural jamming and aging effects that provide hysteresis in the stress–strain relationship. In this study, a thixotropic model and a Herschel–Bulkley model are compared to each other and to prior laboratory experiments that are representative of an avalanche and a subaqueous debris flow. A numerical solver using a multi-material level-set method is applied to track multiple interfaces simultaneously in the simulations. The numerical results are validated with analytical solutions and available experimental data using parameters selected based on the experimental setup and without post hoc calibration. The thixotropic (time-dependent) fluid model shows reasonable agreement with all the experimental data. For most of the experimental conditions, the Herschel–Bulkley (time-independent) model results were similar to the thixotropic model, a critical exception being conditions with a high yield stress where the Herschel–Bulkley model did not initiate flow. These results indicate that the thixotropic relationship is promising for modeling unsteady phases of debris flows and avalanches, but there is a need for better understanding of the correct material parameters and parameters for the initial structural jamming and characteristic time of aging, which requires more detailed experimental data than presently available.