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  • 2006  (7)
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  • 2006  (7)
  • 1
    Language: English
    In: AEUE - International Journal of Electronics and Communications, 2006, Vol.60(1), pp.13-19
    Description: A federation approach for security in future distributed service delivery platforms for mobile users offers some key advantages over an integrated solution relying on a common choice of a standardized authentication technology. By agreeing on an exchange protocol for security assertions rather than on the detailed security mechanisms, Service Aggregators and Access Network Operators will be able to federate their customer offerings flexibly and jointly offer services. The consumer will find formerly separate offerings combined, and Service Operators will enjoy open interfaces towards the network's service delivery platform. Through the use of Security Assertion Markup Language (SAML), standardized assertion statements can be made not only for the user's identity, but also on attributes and authorizations associated with it. This will allow a seamless personalized service experience offering single sign-on across separate operational domains. An example from automobile telematics is used to illustrate the concepts.
    Keywords: Security ; Assertion ; Single Sign-on ; Saml ; Open Service Provisioning ; Telematics ; Automotive ; Engineering
    ISSN: 1434-8411
    E-ISSN: 1618-0399
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  • 2
    Language: English
    In: Hydrology and Earth System Sciences , 495-506., 2006
    Description: A classical transport experiment was performed in a field plot of 2.5 m2 using the dye tracer brilliant blue. The measured tracer distribution demonstrates the dominant role of the heterogeneous soil structure for solute transport. As with many other published experiments, this evidences the need of considering the macroscopic structure of soil to predict flow and transport. We combine three different approaches to represent the relevant structure of the specific situation of our experiment: i) direct measurement, ii) statistical description of heterogeneities and iii) a conceptual model of structure formation. The structure of soil layers was directly obtained from serial sections in the field. The sub-scale heterogeneity within the soil horizons was modelled through correlated random fields with estimated correlation lengths and anisotropy. Earthworm burrows played a dominant role at the transition between the upper soil horizon and the subsoil. A model based on percolation theory is introduced that mimics the geometry of earthworm burrow systems. The hydraulic material properties of the different structural units were obtained by direct measurements where available and by a best estimate otherwise. From the hydraulic structure, the 3-dimensional velocity field of water was calculated by solving Richards' Equation and solute transport was simulated. The simulated tracer distribution compares reasonably well with the experimental data. We conclude that a rough representation of the structure and a rough representation of the hydraulic properties might be sufficient to predict flow and transport, but both elements are definitely required.
    Keywords: Beauce ; Centre ; Calcisol;Dye Tracer;Soil Structure;Percolation ; Expérimentation Au Champ ; Structure Du Sol ; Île De France ; Transfert Hydrique
    Source: AGRIS (Food and Agriculture Organization of the United Nations)
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  • 3
    Language: English
    In: Hydrology and Earth System Sciences, 10, 495-506, 2006
    Description: A classical transport experiment was performed in a field plot of 2.5 m2 using the dye tracer brilliant blue. The measured tracer distribution demonstrates the dominant role of the heterogeneous soil structure for solute transport. As with many other published experiments, this evidences the need of considering the macroscopic structure of soil to predict flow and transport. We combine three different approaches to represent the relevant structure of the specific situation of our experiment: i) direct measurement, ii) statistical description of heterogeneities and iii) a conceptual model of structure formation. The structure of soil layers was directly obtained from serial sections in the field. The sub-scale heterogeneity within the soil horizons was modelled through correlated random fields with estimated correlation lengths and anisotropy. Earthworm burrows played a dominant role at the transition between the upper soil horizon and the subsoil. A model based on percolation theory is introduced that mimics the geometry of earthworm burrow systems. The hydraulic material properties of the different structural units were obtained by direct measurements where available and by a best estimate otherwise. From the hydraulic structure, the 3-dimensional velocity field of water was calculated by solving Richards' Equation and solute transport was simulated. The simulated tracer distribution compares reasonably well with the experimental data. We conclude that a rough representation of the structure and a rough representation of the hydraulic properties might be sufficient to predict flow and transport, but both elements are definitely required.
    Keywords: Beauce ; Centre ; Expérimentation Au Champ ; Structure Du Sol ; Île De France ; Transfert Hydrique ; Dye Tracer ; Calcisol ; Percolation ; Soil Structure
    Source: AGRIS (Food and Agriculture Organization of the United Nations)
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  • 4
    Language: English
    In: Hydrology and Earth System Sciences , 495-506., 2006
    Description: A classical transport experiment was performed in a field plot of 2.5 m2 using the dye tracer brilliant blue. The measured tracer distribution demonstrates the dominant role of the heterogeneous soil structure for solute transport. As with many other published experiments, this evidences the need of considering the macroscopic structure of soil to predict flow and transport. We combine three different approaches to represent the relevant structure of the specific situation of our experiment: i) direct measurement, ii) statistical description of heterogeneities and iii) a conceptual model of structure formation. The structure of soil layers was directly obtained from serial sections in the field. The sub-scale heterogeneity within the soil horizons was modelled through correlated random fields with estimated correlation lengths and anisotropy. Earthworm burrows played a dominant role at the transition between the upper soil horizon and the subsoil. A model based on percolation theory is introduced that mimics the geometry of earthworm burrow systems. The hydraulic material properties of the different structural units were obtained by direct measurements where available and by a best estimate otherwise. From the hydraulic structure, the 3-dimensional velocity field of water was calculated by solving Richards' Equation and solute transport was simulated. The simulated tracer distribution compares reasonably well with the experimental data. We conclude that a rough representation of the structure and a rough representation of the hydraulic properties might be sufficient to predict flow and transport, but both elements are definitely required.
    Keywords: Beauce ; Centre ; Calcisol;Dye Tracer;Soil Structure;Percolation ; Expérimentation Au Champ ; Structure Du Sol ; Île De France ; Transfert Hydrique
    Source: AGRIS (Food and Agriculture Organization of the United Nations)
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  • 5
    In: Water Resources Research, May 2006, Vol.42(5), pp.n/a-n/a
    Description: This paper presents a vision that advocates hydropedology as an advantageous integration of pedology and hydrology for studying the intimate relationships between soil, landscape, and hydrology. Landscape water flux is suggested as a unifying precept for hydropedology, through which pedologic and hydrologic expertise can be better integrated. Landscape water flux here encompasses the source, storage, flux, pathway, residence time, availability, and spatiotemporal distribution of water in the root and deep vadose zones within the landscape. After illustrating multiple knowledge gaps that can be addressed by the synergistic integration of pedology and hydrology, we suggest five scientific hypotheses that are critical to advancing hydropedology and enhancing the prediction of landscape water flux. We then present interlinked strategies for achieving the stated vision. It is our hope that by working together, hydrologists and pedologists, along with scientists in related disciplines, can better guide data acquisition, knowledge integration, and model‐based prediction so as to advance the hydrologic sciences in the next decade and beyond.
    Keywords: Catchment Hydrology ; Landscape Processes ; Scale ; Soil Hydrology ; Soil Physics ; Vadose Zone
    ISSN: 0043-1397
    E-ISSN: 1944-7973
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  • 6
    Text Resource
    Text Resource
    XVI International Conference on Computational Methods in Water Resources
    Language: English
    Description: The determination of hydraulic parameter functions is crucial for the modeling of multiphase flow in porous media. The combination of multistep-outflow experiments and inverse modeling is a standard method for the determination of hydraulic properties for unsaturated flow. Up to now it is necessary to assume, that the sample is homogeneous, which is not true for most natural porous media. Measurement techniques like x-ray tomography, geoelectrics and georadar allow the non-destructive determination of the spatial structure of a sample. If thus the structure of a sample is known, it can be possible to estimate the hydraulic property functions of the basic materials of a soil with multistep-outflow experiments and an optimisation procedure, which takes the structure explicitly into account. A code for parameter optimisation in 2D and 3D structured material is presented and applied to experimental data. The estimated hydraulic parameters for homogeneous and heterogeneous samples are compared....
    Source: DataCite
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  • 7
    Text Resource
    Text Resource
    XVI International Conference on Computational Methods in Water Resources
    Language: English
    Description: The determination of hydraulic parameter functions is crucial for the modeling of multiphase flow in porous media. The combination of multistep-outflow experiments and inverse modeling is a standard method for the determination of hydraulic properties for unsaturated flow. Up to now it is necessary to assume, that the sample is homogeneous, which is not true for most natural porous media. Measurement techniques like x-ray tomography, geoelectrics and georadar allow the non-destructive determination of the spatial structure of a sample. If thus the structure of a sample is known, it can be possible to estimate the hydraulic property functions of the basic materials of a soil with multistep-outflow experiments and an optimisation procedure, which takes the structure explicitly into account. A code for parameter optimisation in 2D and 3D structured material is presented and applied to experimental data. The estimated hydraulic parameters for homogeneous and heterogeneous samples are compared....
    Source: DataCite
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
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