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End date: 2022 × Start date: 2020 × End date: 2019 × Start date: 2010 × Type: Article × Publisher: Cambridge : Cambridge Univ. Press ×

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    Geothermal play typing in Germany, case study Molasse Basin: A modern concept to categorise geothermal resources related to crustal permeability
    (Cambridge : Cambridge Univ. Press, 2019) Moeck, Inga S.; Dussel, Michael; Weber, Josef; Schintgen, Tom; Wolfgramm, Markus
    The majority of running geothermal plants worldwide are located in geological settings with convection- or advection-dominant heat transport. In Germany as in most regions in Europe, conduction is the dominating heat transport mechanism, with a resulting average geothermal gradient. The geothermal play type concept is a modern methodology to group geothermal resources according to their geological setting, and characteristic heat transport mechanisms. In particular, the quantity of heat transport is related to fluid flow in natural or engineered geothermal reservoirs. Hence, the permeability structure is a key element for geothermal play typing. Following the existing geothermal play type catalogue, four major geothermal play types can be identified for Germany: intracratonic basins, foreland basins and basement/crystalline rock provinces as conduction-dominated play types, and extensional terrains as the convection-dominated play type. The installed capacity of geothermal facilities sums up to 397.1 MWth by the end of 2018. District heating plants accounted for the largest portion, with about 337.0 MWth. The majority of these installations are located in the play type 'foreland basin', namely the Molasse Basin in southern Germany. The stratigraphic unit for geothermal use is the Upper Jurassic, also known as 'Malm' formation, a carbonate reservoir with high variability in porosity and permeability. Recently drilled wells in the southernmost Molasse Basin indicate the Upper Jurassic as a tight, fracture-controlled reservoir, not usable for conventional hydrothermal well doublets. Our new data compilation including the recently drilled deep geothermal well Geretsried reveals the relation of porosity and permeability to depth. The results suggest that obviously diagenetic processes control permeability with depth in carbonate rock, diminishing the predictability of reservoir porosity and permeability. The play type concept helps to delineate these property variations in play type levels because it is based on geological constraints, common for exploration geology. Following the general idea of play typing, the results from this play analysis can be transferred to geological analogues as carbonate rock play levels in varying depth. © The Author(s) 2020.
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    Excitation and relaxation dynamics in ultrafast laser irradiated optical glasses
    (Cambridge : Cambridge Univ. Press, 2016) Mauclair, C.; Mermillod-Blondin, A.; Mishchik, K.; Bonse, J.; Rosenfeld, A.; Colombier, J.P.; Stoian, R.
    We discuss the dynamics of ultrashort pulsed laser excitation in bulk optical silica-based glasses (fused silica and borosilicate BK7) well-above the permanent modification threshold. We indicate subsequent structural and thermomechanical energy relaxation paths that translate into positive and negative refractive index changes, compression and rarefaction zones. If fast electronic decay occurs at low excitation levels in fused silica via self-trapping of excitons, for carrier densities in the vicinity of the critical value at the incident wavelength, persistent long-living absorptive states indicate the achievement of low viscosity matter states manifesting pressure relaxation, rarefaction, void opening and compaction in the neighboring domains. An intermediate ps-long excited carrier dynamics is observed for BK7 in the range corresponding to structural expansion and rarefaction. The amount of excitation and the strength of the subsequent hydrodynamic evolution is critically dependent on the pulse time envelope, indicative of potential optimization schemes.
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    Assessing human and environmental pressures of global land-use change 2000-2010
    (Cambridge : Cambridge Univ. Press, 2019) Creutzig, Felix; Bren d'Amour, Christopher; Weddige, Ulf; Fuss, Sabine; Beringer, Tim; Gläser, Anne; Kalkuhl, Matthias; Steckel, Jan Christoph; Radebach, Alexander; Edenhofer, Ottmar
    Global land is turning into an increasingly scarce resource. We here present a comprehensive assessment of co-occuring land-use change from 2000 until 2010, compiling existing spatially explicit data sources for different land uses, and building on a rich literature addressing specific land-use changes in all world regions. This review systematically categorizes patterns of land use, including regional urbanization and agricultural expansion but also globally telecoupled land-use change for all world regions. Managing land-use change patterns across the globe requires global governance. Here we present a comprehensive assessment of the extent and density of multiple drivers and impacts of land-use change. We combine and reanalyze spatially explicit data of global land-use change between 2000 and 2010 for population, livestock, cropland, terrestrial carbon and biodiversity. We find pervasive pressure on biodiversity but varying patterns of gross land-use changes across world regions. Our findings enable a classification of land-use patterns into three types. The 'consumers' type, displayed in Europe and North America, features high land footprints, reduced direct human pressures due to intensification of agriculture, and increased reliance on imports, enabling a partial recovery of terrestrial carbon and reducing pressure on biodiversity. In the 'producer' type, most clearly epitomized by Latin America, telecoupled land-use links drive biodiversity and carbon loss. In the 'mover' type, we find strong direct domestic pressures, but with a wide variety of outcomes, ranging from a concurrent expansion of population, livestock and croplands in Sub-Saharan Africa at the cost of natural habitats to strong pressure on cropland by urbanization in Eastern Asia. In addition, anthropogenic climate change has already left a distinct footprint on global land-use change. Our data- and literature-based assessment reveals region-specific opportunities for managing global land-use change. © 2019 The Author(s).
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    Varieties of Signature Tensors
    (Cambridge : Cambridge Univ. Press, 2019) Améndola, Carlos; Friz, Peter; Sturmfels, Bernd
    The signature of a parametric curve is a sequence of tensors whose entries are iterated integrals. This construction is central to the theory of rough paths in stochastic analysis. It is examined here through the lens of algebraic geometry. We introduce varieties of signature tensors for both deterministic paths and random paths. For the former, we focus on piecewise linear paths, on polynomial paths, and on varieties derived from free nilpotent Lie groups. For the latter, we focus on Brownian motion and its mixtures.
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    On the regularity of SLE trace
    (Cambridge : Cambridge Univ. Press, 2017) Friz, Peter K.; Tran, Huy
    We revisit regularity of SLE trace, for all κ≠8, and establish Besov regularity under the usual half-space capacity parametrization. With an embedding theorem of Garsia–Rodemich–Rumsey type, we obtain finite moments (and hence almost surely) optimal variation regularity with index min(1+κ/8,2), improving on previous works of Werness, and also (optimal) Hölder regularity à la Johansson Viklund and Lawler.