98 results
Search Results
Now showing 1 - 10 of 98
- ItemTemporal Role Annotation for Named Entities(Amsterdam [u.a.] : Elsevier, 2018) Koutraki, Maria; Bakhshandegan-Moghaddam, Farshad; Sack, Harald; Fensel, Anna; de Boer, Victor; Pellegrini, Tassilo; Kiesling, Elmar; Haslhofer, Bernhard; Hollink, Laura; Schindler, AlexanderNatural language understanding tasks are key to extracting structured and semantic information from text. One of the most challenging problems in natural language is ambiguity and resolving such ambiguity based on context including temporal information. This paper, focuses on the task of extracting temporal roles from text, e.g. CEO of an organization or head of a state. A temporal role has a domain, which may resolve to different entities depending on the context and especially on temporal information, e.g. CEO of Microsoft in 2000. We focus on the temporal role extraction, as a precursor for temporal role disambiguation. We propose a structured prediction approach based on Conditional Random Fields (CRF) to annotate temporal roles in text and rely on a rich feature set, which extracts syntactic and semantic information from text. We perform an extensive evaluation of our approach based on two datasets. In the first dataset, we extract nearly 400k instances from Wikipedia through distant supervision, whereas in the second dataset, a manually curated ground-truth consisting of 200 instances is extracted from a sample of The New York Times (NYT) articles. Last, the proposed approach is compared against baselines where significant improvements are shown for both datasets.
- ItemThe Research Core Dataset (KDSF) in the Linked Data context(Amsterdam [u.a.] : Elsevier, 2019) Walther, Tatiana; Hauschke, Christian; Kasprzik, Anna; Sicilia, Miguel-Angel; Simons, Ed; Clements, Anna; de Castro, Pablo; Bergström, JohanThis paper describes our efforts to implement the Research Core Dataset (“Kerndatensatz Forschung”; KDSF) as an ontology in VIVO. KDSF is used in VIVO to record the required metadata on incoming data and to produce reports as an output. While both processes need an elaborate adaptation of the KDSF specification, this paper focusses on the adaptation of the KDSF basic data model for recording data in VIVO. In this context, the VIVO and KDSF ontologies were compared with respect to domain, syntax, structure, and granularity in order to identify correspondences and mismatches. To produce an alignment, different matching approaches have been applied. Furthermore, we made necessary modifications and extensions on KDSF classes and properties.
- ItemEvaluation of Expert Reports to Quantify the Exploration Risk for Geothermal Projects in Germany(Amsterdam [u.a.] : Elsevier, 2015) Ganz, Britta; Ask, Maria; Hangx, Suzanne; Bruckman, Viktor; Kühn, MichaelThe development of deep geothermal energy sources in Germany still faces many uncertainties and high upfront investment costs. Methodical approaches to assess the exploration risk are thus of major importance for geothermal project development. Since 2002, expert reports to quantify the exploration risk for geothermal projects in Germany were carried out. These reports served as a basis for insurance contracts covering the exploration risk. Using data from wells drilled in the meantime, the reports were evaluated and the stated probabilities compared with values actually reached.
- ItemNitrous oxide emissions from winter oilseed rape cultivation(Amsterdam [u.a.] : Elsevier, 2017) Ruser, Reiner; Fuß, Roland; Andres, Monique; Hegewald, Hannes; Kesenheimer, Katharina; Köbke, Sarah; Räbiger, Thomas; Quinones, Teresa Suarez; Augustin, Jürgen; Christen, Olaf; Dittert, Klaus; Kage, Henning; Lewandowski, Iris; Prochnow, Annette; Stichnothe, Heinz; Flessa, HeinzWinter oilseed rape (Brassica napus L., WOSR) is the major oil crop cultivated in Europe. Rapeseed oil is predominantly used for production of biodiesel. The framework of the European Renewable Energy Directive requires that use of biofuels achieves GHG savings of at least 50% compared to use of fossil fuel starting in 2018. However, N2O field emissions are estimated using emission factors that are not specific for the crop and associated with strong uncertainty. N2O field emissions are controlled by N fertilization and dominate the GHG balance of WOSR cropping due to the high global warming potential of N2O. Thus, field experiments were conducted to increase the data basis and subsequently derive a new WOSR-specific emission factor. N2O emissions and crop yields were monitored for three years over a range of N fertilization intensities at five study sites representative of German WOSR production. N2O fluxes exhibited the typical high spatial and temporal variability in dependence on soil texture, weather and nitrogen availability. The annual N2O emissions ranged between 0.24 kg and 5.48 kg N2O-N ha−1 a−1. N fertilization increased N2O emissions, particularly with the highest N treatment (240 kg N ha−1). Oil yield increased up to a fertilizer amount of 120 kg N ha−1, higher N-doses increased grain yield but decreased oil concentrations in the seeds. Consequently oil yield remained constant at higher N fertilization. Since, yield-related emission also increased exponentially with N surpluses, there is potential for reduction of the N fertilizer rate, which offers perspectives for the mitigation of GHG emissions. Our measurements double the published data basis of annual N2O flux measurements in WOSR. Based on this extended dataset we modeled the relationship between N2O emissions and fertilizer N input using an exponential model. The corresponding new N2O emission factor was 0.6% of applied fertilizer N for a common N fertilizer amount under best management practice in WOSR production (200 kg N ha−1 a−1). This factor is substantially lower than the linear IPCC Tier 1 factor (EF1) of 1.0% and other models that have been proposed. © 2017
- ItemDeep Geothermal Energy for Lower Saxony (North Germany) – Combined Investigations of Geothermal Reservoir Characteristics(Amsterdam [u.a.] : Elsevier, 2014) Hahne, Barbara; Thomas, Rüdiger; Bruckman, Viktor J.; Hangx, Suzanne; Ask, MariaFor the economic success of a geothermal project the hydraulic properties and temperature of the geothermal reservoir are crucial. New methodologies in seismics, geoelectrics and reservoir geology are tested within the frame of the collaborative research programme “Geothermal Energy and High-Performance Drilling” (gebo). Within nine geoscientific projects, tools were developed that help in the evaluation and interpretation of acquired data. Special emphasis is placed on the investigation of rock properties, on the development of early reservoir assessment even during drilling, and on the interaction between the drilling devices and the reservoir formation. The propagation of fractures and the transport of fluid and heat within the regional stress field are investigated using different approaches (field studies, seismic monitoring, multi-parameter modelling). Geologic structural models have been created for simulation of the local stress field and hydromechanical processes. Furthermore, a comprehensive dataset of hydrogeochemical environments was collected allowing characterisation and hydrogeochemical modelling of the reservoir.
- ItemModelling the Surface Heat Flow Distribution in the Area of Brandenburg (Northern Germany)(Amsterdam [u.a.] : Elsevier, 2013) Cacace, Mauro; Scheck-Wenderoth, Magdalena; Noack, Vera; Cherubini, Yvonne; Schellschmidt, Rüdiger; Kühn, Michael; Juhlin, Christopher; Held, Hermann; Bruckman, Viktor; Tambach, Tim; Kempka, ThomasA lithosphere scale geological model has been used to determine the surface heat flow component due to conductive heat transport for the area of Brandenburg. The modelling results have been constrained by a direct comparison with available heat flow measurements. The calculated heat flow captures the regional trend in the surface heat flow distribution which can be related to existing thermal conductivity variations between the different sedimentary units. An additional advective component due to topography induced regional flow and focused flow within major fault zones should be considered to explain the spatial variation observed in the surface heat flow.
- ItemCarrier Lifetime in Liquid-phase Crystallized Silicon on Glass(Amsterdam [u.a.] : Elsevier, 2016) Vetter, Michael; Gawlik, Annett; Plentz, Jonathan; Andrä, Gudrun; Ribeyron, Pierre-Jean; Cuevas, Andres; Weeber, Arthur; Ballif, Christophe; Glunz, Stefan; Poortmans, Jef; Brendel, Rolf; Aberle, Armin; Sinton, Ron; Verlinden, Pierre; Hahn, GisoLiquid-phase crystallized silicon on glass (LPCSG) presents a promising material to fabricate high quality silicon thin films, e.g. for solar cells and modules. Barrier layers and a doped amorphous silicon layer are deposited on the glass substrate followed by crystallization with a line focus laser beam. In this paper we introduce injection level dependent lifetime measurements generated by the quasi steady-state photoconductance decay method (QSSPC) to characterize LPCSG absorbers. This contactless method allows a determination of the LPCSG absorber quality already at an early stage of solar cell fabrication, and provides a monitoring of the absorber quality during the solar cell fabrication steps. We found minority carrier lifetimes higher than 200ns in our layers (e.g. n-type absorber with ND=2x1015cm-3) indicating a surface recombination velocity SBL<3000cm/s at the barrier layer/Si interface.
- ItemChapter scientists in the IPCC AR5-experience and lessons learned(Amsterdam [u.a.] : Elsevier, 2015) Schulte-Uebbing, Lena; Hansen, Gerrit; Hernández, Ariel Macaspac; Winter, MartenIPCC Assessment Reports provide timely and accurate information on anthropogenic climate change to policy makers and the public. The reports are written by hundreds of scientists in a voluntary, collaborative effort. Growing amounts of literature and complex procedural and administrative requirements, however, make this effort a substantial management challenge next to a scientific one. During the 5th Assessment Cycle, IPCC Working Groups II and III initiated a program that recruited volunteer scientific assistants who provided technical and logistical support to author teams. In this paper we describe and analyze strengths and weaknesses of this ‘Chapter Scientist program’, based on an extensive survey among Chapter Scientists (CS) and interviews with other stakeholders. We conclude that the program was a useful innovation that that enabled authors to focus more on their core scientific tasks and that contributed to improving the quality of the assessment. We highly recommend similar programs for future scientific assessments. Key criteria for success that we identified are (a) involvement of early-career scientists as CS, (b) close integration of CS in the assessment process, (c) recruitment of CS through an open call to achieve transparency, and (d) provision of funds for such a program to support travel costs and compensation of CS.
- ItemThe Cyclostratigraphy Intercomparison Project (CIP): consistency, merits and pitfalls(Amsterdam [u.a.] : Elsevier, 2019) Sinnesael, Matthias; De Vleeschouwer, David; Zeeden, Christian; Batenburg, Sietske J.; Da Silva, Anne-Christine; de Winter, Niels J.; Dinarès-Turell, Jaume; Drury, Anna Joy; Gambacorta, Gabriele; Hilgen, Frederik J.; Hinnov, Linda A.; Hudson, Alexander J.L.; Kemp, David B.; Lantink, Margriet L.; Laurin, Jiří; Li, Mingsong; Liebrand, Diederik; Ma, Chao; Meyers, Stephen R.; Monkenbusch, Johannes; Montanari, Alessandro; Nohl, Theresa; Pälike, Heiko; Pas, Damien; Ruhl, Micha; Thibault, Nicolas; Vahlenkamp, Maximilian; Valero, Luis; Wouters, Sébastien; Wu, Huaichun; Claeys, PhilippeCyclostratigraphy is an important tool for understanding astronomical climate forcing and reading geological time in sedimentary sequences, provided that an imprint of insolation variations caused by Earth’s orbital eccentricity, obliquity and/or precession is preserved (Milankovitch forcing). Numerous stratigraphic and paleoclimate studies have applied cyclostratigraphy, but the robustness of the methodology and its dependence on the investigator have not been systematically evaluated. We developed the Cyclostratigraphy Intercomparison Project (CIP) to assess the robustness of cyclostratigraphic methods using an experimental design of three artificial cyclostratigraphic case studies with known input parameters. Each case study is designed to address specific challenges that are relevant to cyclostratigraphy. Case 1 represents an offshore research vessel environment, as only a drill-core photo and the approximate position of a late Miocene stage boundary are available for analysis. In Case 2, the Pleistocene proxy record displays clear nonlinear cyclical patterns and the interpretation is complicated by the presence of a hiatus. Case 3 represents a Late Devonian proxy record with a low signal-to-noise ratio with no specific theoretical astronomical solution available for this age. Each case was analyzed by a test group of 17-20 participants, with varying experience levels, methodological preferences and dedicated analysis time. During the CIP 2018 meeting in Brussels, Belgium, the ensuing analyses and discussion demonstrated that most participants did not arrive at a perfect solution, which may be partly explained by the limited amount of time spent on the exercises (∼4.5 hours per case). However, in all three cases, the median solution of all submitted analyses accurately approached the correct result and several participants obtained the exact correct answers. Interestingly, systematically better performances were obtained for cases that represented the data type and stratigraphic age that were closest to the individual participants’ experience. This experiment demonstrates that cyclostratigraphy is a powerful tool for deciphering time in sedimentary successions and, importantly, that it is a trainable skill. Finally, we emphasize the importance of an integrated stratigraphic approach and provide flexible guidelines on what good practices in cyclostratigraphy should include. Our case studies provide valuable insight into current common practices in cyclostratigraphy, their potential merits and pitfalls. Our work does not provide a quantitative measure of reliability and uncertainty of cyclostratigraphy, but rather constitutes a starting point for further discussions on how to move the maturing field of cyclostratigraphy forward.
- ItemAssessing the organic fraction of municipal solid wastes for the production of lactic acid(Amsterdam [u.a.] : Elsevier, 2019) López-Gómez, J. Pablo; Latorre-Sánchez, Marcos; Unger, Peter; Schneider, Roland; Coll Lozano, Caterina; Venus, JoachimWith an estimated yearly production of about 140 Mt in the EU, conventionally, the organic fraction of municipal solid wastes (OFMSW) has been disposed in landfills with negative environmental effects. Nonetheless, the chemical composition of this residue make it a substrate with great bioconversion potential. In this study, OFMSW from Spanish municipal treatment plants, were evaluated for the production of LA. Samples were identified according to the sorting mechanisms employed for their collection in: (A) separately collected, (B) non-separately collected and (C) separately collected+paper/cardboard. Enzymatic hydrolysis was used to produce hydrolysates A, B and C accordingly. Hydrolysate A showed the highest total sugars and glucose content with values of 70 and 55 g·L−1, respectively. Following the characterisation, a screening showed that growth of B. coagulans was possible in all three hydrolysates. Furthermore, lab scale fermentations showed that LA final concentrations could reach around 60 g·L−1, with yields from total sugars of above 0.60 g·g−1. A technical scale fermentation of the hydrolysate A resulted in a final LA concentration of 60.7 g·L−1, a yield of 0.71 g·g−1 with a productivity of 2.68 g·L−1·h−1. Overall, it was estimated that 0.23 g of LA could be produced from one g of dry OFMSW.