197 results on '"Jansen, Joachim"'
Search Results
2. Causality guided machine learning model on wetland CH4 emissions across global wetlands
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Yuan, Kunxiaojia, Zhu, Qing, Li, Fa, Riley, William J, Torn, Margaret, Chu, Housen, McNicol, Gavin, Chen, Min, Knox, Sara, Delwiche, Kyle, Wu, Huayi, Baldocchi, Dennis, Ma, Hongxu, Desai, Ankur R, Chen, Jiquan, Sachs, Torsten, Ueyama, Masahito, Sonnentag, Oliver, Helbig, Manuel, Tuittila, Eeva-Stiina, Jurasinski, Gerald, Koebsch, Franziska, Campbell, David, Schmid, Hans Peter, Lohila, Annalea, Goeckede, Mathias, Nilsson, Mats B, Friborg, Thomas, Jansen, Joachim, Zona, Donatella, Euskirchen, Eugenie, Ward, Eric J, Bohrer, Gil, Jin, Zhenong, Liu, Licheng, Iwata, Hiroki, Goodrich, Jordan, and Jackson, Robert
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Earth Sciences ,Machine Learning and Artificial Intelligence ,Climate Action ,Eddy covariance CH4 emission ,Wetlands ,Causal inference ,Machine learning ,Biological Sciences ,Agricultural and Veterinary Sciences ,Meteorology & Atmospheric Sciences ,Agricultural ,veterinary and food sciences ,Biological sciences ,Earth sciences - Abstract
Wetland CH₄ emissions are among the most uncertain components of the global CH₄ budget. The complex nature of wetland CH₄ processes makes it challenging to identify causal relationships for improving our understanding and predictability of CH₄ emissions. In this study, we used the flux measurements of CH₄ from eddy covariance towers (30 sites from 4 wetlands types: bog, fen, marsh, and wet tundra) to construct a causality-constrained machine learning (ML) framework to explain the regulative factors and to capture CH₄ emissions at sub-seasonal scale. We found that soil temperature is the dominant factor for CH₄ emissions in all studied wetland types. Ecosystem respiration (CO₂) and gross primary productivity exert controls at bog, fen, and marsh sites with lagged responses of days to weeks. Integrating these asynchronous environmental and biological causal relationships in predictive models significantly improved model performance. More importantly, modeled CH₄ emissions differed by up to a factor of 4 under a +1°C warming scenario when causality constraints were considered. These results highlight the significant role of causality in modeling wetland CH₄ emissions especially under future warming conditions, while traditional data-driven ML models may reproduce observations for the wrong reasons. Our proposed causality-guided model could benefit predictive modeling, large-scale upscaling, data gap-filling, and surrogate modeling of wetland CH₄ emissions within earth system land models.
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- 2022
3. Monitoring of carbon-water fluxes at Eurasian meteorological stations using random forest and remote sensing
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Xie, Mingjuan, Ma, Xiaofei, Wang, Yuangang, Li, Chaofan, Shi, Haiyang, Yuan, Xiuliang, Hellwich, Olaf, Chen, Chunbo, Zhang, Wenqiang, Zhang, Chen, Ling, Qing, Gao, Ruixiang, Zhang, Yu, Ochege, Friday Uchenna, Frankl, Amaury, De Maeyer, Philippe, Buchmann, Nina, Feigenwinter, Iris, Olesen, Jørgen E., Juszczak, Radoslaw, Jacotot, Adrien, Korrensalo, Aino, Pitacco, Andrea, Varlagin, Andrej, Shekhar, Ankit, Lohila, Annalea, Carrara, Arnaud, Brut, Aurore, Kruijt, Bart, Loubet, Benjamin, Heinesch, Bernard, Chojnicki, Bogdan, Helfter, Carole, Vincke, Caroline, Shao, Changliang, Bernhofer, Christian, Brümmer, Christian, Wille, Christian, Tuittila, Eeva-Stiina, Nemitz, Eiko, Meggio, Franco, Dong, Gang, Lanigan, Gary, Niedrist, Georg, Wohlfahrt, Georg, Zhou, Guoyi, Goded, Ignacio, Gruenwald, Thomas, Olejnik, Janusz, Jansen, Joachim, Neirynck, Johan, Tuovinen, Juha-Pekka, Zhang, Junhui, Klumpp, Katja, Pilegaard, Kim, Šigut, Ladislav, Klemedtsson, Leif, Tezza, Luca, Hörtnagl, Lukas, Urbaniak, Marek, Roland, Marilyn, Schmidt, Marius, Sutton, Mark A., Hehn, Markus, Saunders, Matthew, Mauder, Matthias, Aurela, Mika, Korkiakoski, Mika, Du, Mingyuan, Vendrame, Nadia, Kowalska, Natalia, Leahy, Paul G., Alekseychik, Pavel, Shi, Peili, Weslien, Per, Chen, Shiping, Fares, Silvano, Friborg, Thomas, Tallec, Tiphaine, Kato, Tomomichi, Sachs, Torsten, Maximov, Trofim, di Cella, Umberto Morra, Moderow, Uta, Li, Yingnian, He, Yongtao, Kosugi, Yoshiko, and Luo, Geping
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- 2023
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4. Satellite-based modeling of wetland methane emissions on a global scale (SatWetCH4 1.0).
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Bernard, Juliette, Salmon, Elodie, Saunois, Marielle, Peng, Shushi, Serrano-Ortiz, Penélope, Berchet, Antoine, Gnanamoorthy, Palingamoorthy, Jansen, Joachim, and Ciais, Philippe
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MODIS (Spectroradiometer) ,EDDY flux ,ATMOSPHERIC models ,METHANE ,WETLANDS ,ATMOSPHERIC methane - Abstract
Wetlands are major contributors to global methane emissions. However, their budget and temporal variability remain subject to large uncertainties. This study develops the Satellite-based Wetland CH
4 model (SatWetCH4), which simulates global wetland methane emissions at 0.25° × 0.25° and monthly temporal resolution, relying mainly on remote-sensing products. In particular, a new approach is derived to assess the substrate availability, based on Moderate-Resolution Imaging Spectroradiometer (MODIS) data. The model is calibrated using eddy covariance flux data from 58 sites, allowing for independence from other estimates. At the site level, the model effectively reproduces the magnitude and seasonality of the fluxes in the boreal and temperate regions but shows limitations in capturing the seasonality of tropical sites. Despite its simplicity, the model provides global simulations over decades and produces consistent spatial patterns and seasonal variations comparable to more complex land surface models (LSMs). Such an independent data-driven approach based on remote-sensing products is intended to allow for future studies of intra-annual variations in wetland methane emissions. In addition, our study highlights uncertainties and issues in wetland extent datasets and the need for new seamless satellite-based wetland extent products. In the future, there is potential to integrate this one-step model into atmospheric inversion frameworks, thereby allowing for the optimization of the model parameters using atmospheric methane concentrations as constraints and hopefully better estimates of wetland emissions. [ABSTRACT FROM AUTHOR]- Published
- 2025
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5. Implementing a Relevance Tracker Module
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Jansen, Joachim, Devriendt, Jo, Bogaerts, Bart, Janssens, Gerda, and Denecker, Marc
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Computer Science - Artificial Intelligence - Abstract
PC(ID) extends propositional logic with inductive definitions: rule sets under the well-founded semantics. Recently, a notion of relevance was introduced for this language. This notion determines the set of undecided literals that can still influence the satisfiability of a PC(ID) formula in a given partial assignment. The idea is that the PC(ID) solver can make decisions only on relevant literals without losing soundness and thus safely ignore irrelevant literals. One important insight that the relevance of a literal is completely determined by the current solver state. During search, the solver state changes have an effect on the relevance of literals. In this paper, we discuss an incremental, lightweight implementation of a relevance tracker module that can be added to and interact with an out-of-the-box SAT(ID) solver., Comment: Paper presented at the 9th Workshop on Answer Set Programming and Other Computing Paradigms (ASPOCP 2016), New York City, USA, 16 October 2016
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- 2016
6. Towards critical white ice conditions in lakes under global warming
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Weyhenmeyer, Gesa A., Obertegger, Ulrike, Rudebeck, Hugo, Jakobsson, Ellinor, Jansen, Joachim, Zdorovennova, Galina, Bansal, Sheel, Block, Benjamin D., Carey, Cayelan C., Doubek, Jonathan P., Dugan, Hilary, Erina, Oxana, Fedorova, Irina, Fischer, Janet M., Grinberga, Laura, Grossart, Hans-Peter, Kangur, Külli, Knoll, Lesley B., Laas, Alo, Lepori, Fabio, Meier, Jacob, Palshin, Nikolai, Peternell, Mark, Pulkkanen, Merja, Rusak, James A., Sharma, Sapna, Wain, Danielle, and Zdorovennov, Roman
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- 2022
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7. Water temperature, mixing, and ice phenology in the arctic–alpine Lake Darfáljávri (Lake Tarfala), northern Sweden.
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Kirchner, Nina, Weckström, Jan, Jansen, Joachim, Schenk, Frederik, Barnett, Jamie, Granebeck, Annika, Leppäranta, Matti, and Korhola, Atte
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ICE on rivers, lakes, etc. ,WATER temperature ,HEAT flux ,PUBLIC records ,WINTER ,TUNDRAS - Abstract
In the rapidly warming circumpolar Arctic, recent research of lakes has focused on their climatology and ecology but is challenged by sparsity of wintertime data. At the c. 48-m-deep and c. 0.5-km
2 large proglacial Darfáljávri (Lake Tarfala), located in an arctic–alpine environment in the Scandinavian Mountains, year-round water temperatures were previously reported for 2016 to 2019. Here, this record is continued for 2019–2020 and 2021–2022, complemented by time-lapse imagery records of the state of the lake surface, as well as degree-day modeling of ice phenology (timing of ice-on and ice-off). Darfáljávri is cryostratified during winter, with interannual variations in the thermocline's thickness and temperature range. The ice season lasts from October to July. Modeled ice-on dates match observed ones reasonably well; however, observed ice-off dates occur much later than modeled ones, likely because of cold impact from Darfáljávri's glacial environment as inferred from a comparison with a close tundra lake. Though new insights into the complex lake mixing and ice phenology are provided, it remains to attribute the characteristics of Darfáljávri's winter stratification to additional potential drivers, such as lake ice thickness, atmospheric heat fluxes, and the water balance of the lake. [ABSTRACT FROM AUTHOR]- Published
- 2024
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8. A Lake Biogeochemistry Model for Global Methane Emissions: Model Development, Site‐Level Validation, and Global Applicability.
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Tan, Zeli, Yao, Huaxia, Melack, John, Grossart, Hans‐Peter, Jansen, Joachim, Balathandayuthabani, Sivakiruthika, Sargsyan, Khachik, and Leung, L. Ruby
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OXIDATION kinetics ,SURFACE diffusion ,EBULLITION ,METHANE ,MODEL validation - Abstract
Lakes are important sentinels of climate change and may contribute over 30% of natural methane (CH4) emissions; however, no earth system model (ESM) has represented lake CH4 dynamics. To fill this gap, we refined a process‐based lake biogeochemical model to simulate global lake CH4 emissions, including representation of lake bathymetry, oxic methane production (OMP), the effect of water level on ebullition, new non‐linear CH4 oxidation kinetics, and the coupling of sediment carbon pools with in‐lake primary production and terrigenous carbon loadings. We compiled a lake CH4 data set for model validation. The model shows promising performance in capturing the seasonal and inter‐annual variabilities of CH4 emissions at 10 representative lakes for different lake types and the variations in mean annual CH4 emissions among 106 lakes across the globe. The model reproduces the variations of the observed surface CH4 diffusion and ebullition along the gradients of lake latitude, depth, and surface area. The results suggest that OMP could play an important role in surface CH4 diffusion, and its relative importance is higher in less productive and/or deeper lakes. The model performance is improved for capturing CH4 outgassing events in non‐floodplain lakes and the seasonal variability of CH4 ebullition in floodplain lakes by representing the effect of water level on ebullition. The model can be integrated into ESMs to constrain global lake CH4 emissions and climate‐CH4 feedback. Plain Language Summary: Lakes are highly sensitive to climate change and can produce over 30% of natural methane (CH4) emissions. However, these emissions are not well understood or included in global CH4 assessments. Current lake CH4 models either miss key processes or haven't been tested with observations from different environments. To address this, we improved the Advanced Lake Biogeochemistry Model (ALBM) to better simulate CH4 production, oxidation, and transport. We also created a new data set of CH4 emissions from 106 lakes worldwide to validate the model. Our improved model shows promising performance in simulating observed emissions. Our findings highlight the importance of including CH4 production in oxygen‐rich water, the impact of water level change on CH4 bubble release, and a new method for CH4 oxidation in lake CH4 models. The improved ALBM can now be used in Earth system models to better predict global lake CH4 emissions and their impact on climate change. Key Points: We enhanced and validated the Advanced Lake Biogeochemistry Model for lake CH4 emissions using a new global data setThe model captures lake CH4 emissions across diverse environments and accounts for seasonal and inter‐annual variationsLake CH4 models should include oxic CH4 production, water level impact on ebullition, and a new method for CH4 oxidation [ABSTRACT FROM AUTHOR]
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- 2024
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9. Satellite-based modeling of wetland methane emissions on a global scale (SatWetCH4 1.0)
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Bernard, Juliette, primary, Saunois, Marielle, additional, Salmon, Elodie, additional, Ciais, Philippe, additional, Peng, Shushi, additional, Berchet, Antoine, additional, Serrano-Ortiz, Penélope, additional, Gnanamoorthy, Palingamoorthy, additional, and Jansen, Joachim, additional
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- 2024
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10. Supplementary material to "Satellite-based modeling of wetland methane emissions on a global scale (SatWetCH4 1.0)"
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Bernard, Juliette, primary, Saunois, Marielle, additional, Salmon, Elodie, additional, Ciais, Philippe, additional, Peng, Shushi, additional, Berchet, Antoine, additional, Serrano-Ortiz, Penélope, additional, Gnanamoorthy, Palingamoorthy, additional, and Jansen, Joachim, additional
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- 2024
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11. Model revision inference for extensions of first order logic
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Jansen, Joachim
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Computer Science - Artificial Intelligence - Abstract
I am Joachim Jansen and this is my research summary, part of my application to the Doctoral Consortium at ICLP'14. I am a PhD student in the Knowledge Representation and Reasoning (KRR) research group, a subgroup of the Declarative Languages and Artificial Intelligence (DTAI) group at the department of Computer Science at KU Leuven. I started my PhD in September 2012. My promotor is prof. dr. ir. Gerda Janssens and my co-promotor is prof. dr. Marc Denecker. I can be contacted at joachim.jansen@cs.kuleuven.be or at: Room 01.167 Celestijnenlaan 200A 3001 Heverlee Belgium An extended abstract / full version of a paper accepted to be presented at the Doctoral Consortium of the 30th International Conference on Logic Programming (ICLP 2014), July 19-22, Vienna, Austria
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- 2014
12. Simulating dynamic systems using Linear Time Calculus theories
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Bogaerts, Bart, Jansen, Joachim, Bruynooghe, Maurice, De Cat, Broes, Vennekens, Joost, and Denecker, Marc
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Computer Science - Logic in Computer Science - Abstract
To appear in Theory and Practice of Logic Programming (TPLP). Dynamic systems play a central role in fields such as planning, verification, and databases. Fragmented throughout these fields, we find a multitude of languages to formally specify dynamic systems and a multitude of systems to reason on such specifications. Often, such systems are bound to one specific language and one specific inference task. It is troublesome that performing several inference tasks on the same knowledge requires translations of your specification to other languages. In this paper we study whether it is possible to perform a broad set of well-studied inference tasks on one specification. More concretely, we extend IDP3 with several inferences from fields concerned with dynamic specifications.
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- 2014
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13. Predicate Logic as a Modeling Language: Modeling and Solving some Machine Learning and Data Mining Problems with IDP3
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Bruynooghe, Maurice, Blockeel, Hendrik, Bogaerts, Bart, De Cat, Broes, De Pooter, Stef, Jansen, Joachim, Labarre, Anthony, Ramon, Jan, Denecker, Marc, and Verwer, Sicco
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Computer Science - Logic in Computer Science ,Computer Science - Artificial Intelligence - Abstract
This paper provides a gentle introduction to problem solving with the IDP3 system. The core of IDP3 is a finite model generator that supports first order logic enriched with types, inductive definitions, aggregates and partial functions. It offers its users a modeling language that is a slight extension of predicate logic and allows them to solve a wide range of search problems. Apart from a small introductory example, applications are selected from problems that arose within machine learning and data mining research. These research areas have recently shown a strong interest in declarative modeling and constraint solving as opposed to algorithmic approaches. The paper illustrates that the IDP3 system can be a valuable tool for researchers with such an interest. The first problem is in the domain of stemmatology, a domain of philology concerned with the relationship between surviving variant versions of text. The second problem is about a somewhat related problem within biology where phylogenetic trees are used to represent the evolution of species. The third and final problem concerns the classical problem of learning a minimal automaton consistent with a given set of strings. For this last problem, we show that the performance of our solution comes very close to that of a state-of-the art solution. For each of these applications, we analyze the problem, illustrate the development of a logic-based model and explore how alternatives can affect the performance., Comment: To appear in Theory and Practice of Logic Programming (TPLP)
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- 2013
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14. Bulk Transfer Coefficients Estimated From Eddy-Covariance Measurements Over Lakes and Reservoirs
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Guseva, S., Armani, F., Desai, A. R., Dias, N. L., Friborg, T., Iwata, H., Jansen, Joachim, Luko, G., Mammarella, I, Repina, I, Rutgerson, Anna, Sachs, T., Scholz, K., Spank, U., Stepanenko, V, Torma, P., Vesala, T., Lorke, A., Guseva, S., Armani, F., Desai, A. R., Dias, N. L., Friborg, T., Iwata, H., Jansen, Joachim, Luko, G., Mammarella, I, Repina, I, Rutgerson, Anna, Sachs, T., Scholz, K., Spank, U., Stepanenko, V, Torma, P., Vesala, T., and Lorke, A.
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The drag coefficient, Stanton number and Dalton number are of particular importance for estimating the surface turbulent fluxes of momentum, heat and water vapor using bulk parameterization. Although these bulk transfer coefficients have been extensively studied over the past several decades in marine and large-lake environments, there are no studies analyzing their variability for smaller lakes. Here, we evaluated these coefficients through directly measured surface fluxes using the eddy-covariance technique over more than 30 lakes and reservoirs of different sizes and depths. Our analysis showed that the transfer coefficients (adjusted to neutral atmospheric stability) were generally within the range reported in previous studies for large lakes and oceans. All transfer coefficients exhibit a substantial increase at low wind speeds (<3 m s(-1)), which was found to be associated with the presence of gusts and capillary waves (except Dalton number). Stanton number was found to be on average a factor of 1.3 higher than Dalton number, likely affecting the Bowen ratio method. At high wind speeds, the transfer coefficients remained relatively constant at values of 1.6.10(-3), 1.4.10(-3), 1.0.10(-3), respectively. We found that the variability of the transfer coefficients among the lakes could be associated with lake surface area. In flux parameterizations at lake surfaces, it is recommended to consider variations in the drag coefficient and Stanton number due to wind gustiness and capillary wave roughness while Dalton number could be considered as constant at all wind speeds. Plain Language Summary In our study, we investigate the bulk transfer coefficients, which are of particular importance for estimation the turbulent fluxes of momentum, heat and water vapor in the atmospheric surface layer, above lakes and reservoirs. The incorrect representation of the surface fluxes above inland waters can potentially lead to errors in weather and climate prediction models. For
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- 2023
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15. Author Correction: Towards critical white ice conditions in lakes under global warming
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Weyhenmeyer, Gesa A., primary, Obertegger, Ulrike, additional, Rudebeck, Hugo, additional, Jakobsson, Ellinor, additional, Jansen, Joachim, additional, Zdorovennova, Galina, additional, Bansal, Sheel, additional, Block, Benjamin D., additional, Carey, Cayelan C., additional, Doubek, Jonathan P., additional, Dugan, Hilary, additional, Erina, Oxana, additional, Fedorova, Irina, additional, Fischer, Janet M., additional, Grinberga, Laura, additional, Grossart, Hans-Peter, additional, Kangur, Külli, additional, Knoll, Lesley B., additional, Laas, Alo, additional, Lepori, Fabio, additional, Meier, Jacob, additional, Palshin, Nikolai, additional, Peternell, Mark, additional, Pulkkanen, Merja, additional, Rusak, James A., additional, Sharma, Sapna, additional, Wain, Danielle, additional, and Zdorovennov, Roman, additional
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- 2023
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16. Inferring Accountability from Trust Perceptions
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Decroix, Koen, Butin, Denis, Jansen, Joachim, Naessens, Vincent, Hutchison, David, Series editor, Kanade, Takeo, Series editor, Kittler, Josef, Series editor, Kleinberg, Jon M., Series editor, Kobsa, Alfred, Series editor, Mattern, Friedemann, Series editor, Mitchell, John C., Series editor, Naor, Moni, Series editor, Nierstrasz, Oscar, Series editor, Pandu Rangan, C., Series editor, Steffen, Bernhard, Series editor, Terzopoulos, Demetri, Series editor, Tygar, Doug, Series editor, Weikum, Gerhard, Series editor, Prakash, Atul, editor, and Shyamasundar, Rudrapatna, editor
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- 2014
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17. A logic-based framework for the security analysis of Industrial Control Systems
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Lemaire, Laurens, Vossaert, Jan, Jansen, Joachim, and Naessens, Vincent
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- 2017
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18. Bootstrapping Inference in the IDP Knowledge Base System
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Bogaerts, Bart, Jansen, Joachim, de Cat, Broes, Janssens, Gerda, Bruynooghe, Maurice, and Denecker, Marc
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- 2016
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19. Causality guided machine learning model on wetland CH4 emissions across global wetlands
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Yuan, Kunxiaojia, primary, Zhu, Qing, additional, Li, Fa, additional, Riley, William J., additional, Torn, Margaret, additional, Chu, Housen, additional, McNicol, Gavin, additional, Chen, Min, additional, Knox, Sara, additional, Delwiche, Kyle, additional, Wu, Huayi, additional, Baldocchi, Dennis, additional, Ma, Hongxu, additional, Desai, Ankur R., additional, Chen, Jiquan, additional, Sachs, Torsten, additional, Ueyama, Masahito, additional, Sonnentag, Oliver, additional, Helbig, Manuel, additional, Tuittila, Eeva-Stiina, additional, Jurasinski, Gerald, additional, Koebsch, Franziska, additional, Campbell, David, additional, Schmid, Hans Peter, additional, Lohila, Annalea, additional, Goeckede, Mathias, additional, Nilsson, Mats B., additional, Friborg, Thomas, additional, Jansen, Joachim, additional, Zona, Donatella, additional, Euskirchen, Eugenie, additional, Ward, Eric J., additional, Bohrer, Gil, additional, Jin, Zhenong, additional, Liu, Licheng, additional, Iwata, Hiroki, additional, Goodrich, Jordan, additional, and Jackson, Robert, additional
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- 2022
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20. Neue Möglichkeiten der Kommunikation schaffen die Basis für den Unternehmenserfolg
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Jansen, Joachim and Jäger, Wolfgang, editor
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- 1999
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21. Global increase in methane production under future warming of lake bottom waters
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Jansen, Joachim, Woolway, Richard Iestyn, Kraemer, Benjamin M., Albergel, Clément, Bastviken, David, Weyhenmeyer, Gesa A., Marcé, Rafael, Sharma, Sapna, Sobek, Sebastian, Tranvik, Lars J., Perroud, Marjorie, Golub, Malgorzata, Moore, Tadhg N., Råman Vinnå, Love, La Fuente, Sofia, Grant, Luke, Pierson, Don C., Thiery, Wim, Jennings, Eleanor, Hydrology and Hydraulic Engineering, and Faculty of Engineering
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Climate Research ,Climate Change ,Biodiversity & Conservation ,NORTHERN LAKES ,Environmental Sciences & Ecology ,SEDIMENT CHARACTERISTICS ,aquatic ,climate change ,greenhouse gases ,limnology ,methane ,temperature ,tropics ,Global Warming ,Klimatforskning ,Environmental Chemistry ,CH4 EMISSIONS ,General Environmental Science ,Global and Planetary Change ,Science & Technology ,CLIMATE-CHANGE ,CONSEQUENCES ,Ecology ,Atmosphere ,Temperature ,CONSUMPTION ,PROFILES ,EBULLITION ,Miljövetenskap ,Lakes ,ARCTIC LAKES ,TEMPERATURE-DEPENDENCE ,Biodiversity Conservation ,Life Sciences & Biomedicine ,Methane ,Environmental Sciences - Abstract
Lakes are significant emitters of methane to the atmosphere, and thus are important components of the global methane budget. Methane is typically produced in lake sediments, with the rate of methane production being strongly temperature dependent. Local and regional studies highlight the risk of increasing methane production under future climate change, but a global estimate is not currently available. Here, we project changes in global lake bottom temperatures and sediment methane production rates from 1901 to 2099. By the end of the 21st century, lake bottom temperatures are projected to increase globally, by an average of 0.86-2.60 degrees C under Representative Concentration Pathways (RCPs) 2.6-8.5, with greater warming projected at lower latitudes. This future warming of bottom waters will likely result in an increase in methane production rates of 13%-40% by the end of the century, with many low-latitude lakes experiencing an increase of up to 17 times the historical (1970-1999) global average under RCP 8.5. The projected increase in methane production will likely lead to higher emissions from lakes, although the exact magnitude of the emission increase requires more detailed regional studies. Funding Agencies|Deutsche Forschungsgemeinschaft [AD 91/22-1]; European Regional Development Fund [FEDER--MCIU-AEI/CGL2017-86788-C3-2-P]; FP7 Ideas: European Research Council [336642]; H2020 European Research Council [725546]; Knut och Alice Wallenbergs Stiftelse [KAW 2018-0191]; Natural Environment Research Council
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- 2022
22. Winter inverse lake stratification under historic and future climate change
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Woolway, R. Iestyn, Denfeld, Blaize, Tan, Zeli, Jansen, Joachim, Weyhenmeyer, Gesa A., La Fuente, Sofia, Woolway, R. Iestyn, Denfeld, Blaize, Tan, Zeli, Jansen, Joachim, Weyhenmeyer, Gesa A., and La Fuente, Sofia
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Millions of lakes inversely stratify during winter. Seemingly subtle variations in the duration of winter stratification can have major ecological effects by, for example, altering the vertical distribution of oxygen and nutrients in lakes. Yet, the influence of climate change on winter stratification has been largely unexplored. To fill this knowledge gap, here we used a lake-climate model ensemble to investigate changes in winter stratification from 1901 to 2099 across 12,242 representative lakes situated throughout the Northern Hemisphere. By the end of the 21st century, winter stratification duration is projected to shorten by an average of 18.5–53.9 d under Representative Concentration Pathways (RCPs) 2.6–8.5. Projected changes are faster in warmer geographical regions, in which 35–69% of lakes will no longer inversely stratify by 2070–2099 under RCPs 2.6–8.5. This shortening and loss of winter stratification will likely have numerous implications for lakes, including the misalignment of lifecycle events causing shifts in biodiversity.
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- 2022
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23. Bulk Transfer Coefficients Estimated from Eddy-Covariance Measurements over Lakes and Reservoirs
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Guseva, Sofya, primary, Armani, Fernando, additional, Desai, Ankur Rashmikant, additional, Dias, Nelson Luís, additional, Friborg, Thomas, additional, Iwata, Hiroki, additional, Jansen, Joachim, additional, Lükő, Gabriella, additional, Mammarella, Ivan, additional, Repina, Irina, additional, Rutgersson, Anna, additional, Sachs, Torsten, additional, Scholz, Katharina, additional, Spank, Uwe, additional, Stepanenko, Victor M, additional, Torma, Péter, additional, Vesala, Timo, additional, and Lorke, Andreas, additional
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- 2022
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24. Winter inverse lake stratification under historic and future climate change
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Woolway, R. Iestyn, primary, Denfeld, Blaize, additional, Tan, Zeli, additional, Jansen, Joachim, additional, Weyhenmeyer, Gesa A., additional, and La Fuente, Sofia, additional
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- 2021
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25. Winter Limnology : How do Hydrodynamics and Biogeochemistry Shape Ecosystems Under Ice?
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Jansen, Joachim, MacIntyre, Sally, Barrett, David C., Chin, Yu-Ping, Cortés, Alicia, Forrest, Alexander L., Hrycik, Allison R., Martin, Rosemary, McMeans, Bailey C., Rautio, Milla, Schwefel, Robert, Jansen, Joachim, MacIntyre, Sally, Barrett, David C., Chin, Yu-Ping, Cortés, Alicia, Forrest, Alexander L., Hrycik, Allison R., Martin, Rosemary, McMeans, Bailey C., Rautio, Milla, and Schwefel, Robert
- Abstract
The ice-cover period in lakes is increasingly recognized for its distinct combination of physical and biological phenomena and ecological relevance. Knowledge gaps exist where research areas of hydrodynamics, biogeochemistry and biology intersect. For example, density-driven circulation under ice coincides with an expansion of the anoxic zone, but abiotic and biotic controls on oxygen depletion have not been disentangled, and while heterotrophic microorganisms and migrating phytoplankton often thrive at the oxycline, the extent to which physical processes induce fluxes of heat and substrates that support under-ice food webs is uncertain. Similarly, increased irradiance in spring can promote growth of motile phytoplankton or, if radiatively driven convection occurs, more nutritious diatoms, but links between functional trait selection, trophic transfer to zooplankton and fish, and the prevalence of microbial versus classical food webs in seasonally ice-covered lakes remain unclear. Under-ice processes cascade into and from the ice-free season, and are relevant to annual cycling of energy and carbon through aquatic food webs. Understanding the coupling between state transitions and the reorganization of trophic hierarchies is essential for predicting complex ecosystem responses to climate change. In this interdisciplinary review we describe existing knowledge of physical processes in lakes in winter and the parallel developments in under-ice biogeochemistry and ecology. We then illustrate interactions between these processes, identify extant knowledge gaps and present (novel) methods to address outstanding questions.
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- 2021
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26. Inferring Accountability from Trust Perceptions
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Decroix, Koen, primary, Butin, Denis, additional, Jansen, Joachim, additional, and Naessens, Vincent, additional
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- 2014
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27. Winter Limnology: How do Hydrodynamics and Biogeochemistry Shape Ecosystems Under Ice?
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Jansen, Joachim, primary, MacIntyre, Sally, additional, Barrett, David C., additional, Chin, Yu‐Ping, additional, Cortés, Alicia, additional, Forrest, Alexander L., additional, Hrycik, Allison R., additional, Martin, Rosemary, additional, McMeans, Bailey C., additional, Rautio, Milla, additional, and Schwefel, Robert, additional
- Published
- 2021
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28. Environmental and societal consequences of winter ice loss from lakes.
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Hampton, Stephanie E., Powers, Stephen M., Dugan, Hilary A., Knoll, Lesley B., McMeans, Bailey C., Meyer, Michael F., OÕReilly, Catherine M., Ozersky, Ted, Sharma, Sapna, Barrett, David C., Chandra, Sudeep, Jansen, Joachim, McClure, Ryan P., Rautio, Milla, Weyhenmeyer, Gesa A., and Xiao Yang
- Published
- 2024
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29. FLUXNET-CH4: A global, multi-ecosystem dataset and analysis of methane seasonality from freshwater wetlands
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Delwiche, Kyle B., primary, Knox, Sara Helen, additional, Malhotra, Avni, additional, Fluet-Chouinard, Etienne, additional, McNicol, Gavin, additional, Feron, Sarah, additional, Ouyang, Zutao, additional, Papale, Dario, additional, Trotta, Carlo, additional, Canfora, Eleonora, additional, Cheah, You-Wei, additional, Christianson, Danielle, additional, Alberto, M. Carmelita R., additional, Alekseychik, Pavel, additional, Aurela, Mika, additional, Baldocchi, Dennis, additional, Bansal, Sheel, additional, Billesbach, David P., additional, Bohrer, Gil, additional, Bracho, Rosvel, additional, Buchmann, Nina, additional, Campbell, David I., additional, Celis, Gerardo, additional, Chen, Jiquan, additional, Chen, Weinan, additional, Chu, Housen, additional, Dalmagro, Higo J., additional, Dengel, Sigrid, additional, Desai, Ankur R., additional, Detto, Matteo, additional, Dolman, Han, additional, Eichelmann, Elke, additional, Euskirchen, Eugenie, additional, Famulari, Daniela, additional, Friborg, Thomas, additional, Fuchs, Kathrin, additional, Goeckede, Mathias, additional, Gogo, Sébastien, additional, Gondwe, Mangaliso J., additional, Goodrich, Jordan P., additional, Gottschalk, Pia, additional, Graham, Scott L., additional, Heimann, Martin, additional, Helbig, Manuel, additional, Helfter, Carole, additional, Hemes, Kyle S., additional, Hirano, Takashi, additional, Hollinger, David, additional, Hörtnagl, Lukas, additional, Iwata, Hiroki, additional, Jacotot, Adrien, additional, Jansen, Joachim, additional, Jurasinski, Gerald, additional, Kang, Minseok, additional, Kasak, Kuno, additional, King, John, additional, Klatt, Janina, additional, Koebsch, Franziska, additional, Krauss, Ken W., additional, Lai, Derrick Y. F., additional, Mammarella, Ivan, additional, Manca, Giovanni, additional, Marchesini, Luca Belelli, additional, Matthes, Jaclyn Hatala, additional, Maximon, Trofim, additional, Merbold, Lutz, additional, Mitra, Bhaskar, additional, Morin, Timothy H., additional, Nemitz, Eiko, additional, Nilsson, Mats B., additional, Niu, Shuli, additional, Oechel, Walter C., additional, Oikawa, Patricia Y., additional, Ono, Keisuke, additional, Peichl, Matthias, additional, Peltola, Olli, additional, Reba, Michele L., additional, Richardson, Andrew D., additional, Riley, William, additional, Runkle, Benjamin R. K., additional, Ryu, Youngryel, additional, Sachs, Torsten, additional, Sakabe, Ayaka, additional, Sanchez, Camilo Rey, additional, Schuur, Edward A., additional, Schäfer, Karina V. R., additional, Sonnentag, Oliver, additional, Sparks, Jed P., additional, Stuart-Haëntjens, Ellen, additional, Sturtevant, Cove, additional, Sullivan, Ryan C., additional, Szutu, Daphne J., additional, Thom, Jonathan E., additional, Torn, Margaret S., additional, Tuittila, Eeva-Stiina, additional, Turner, Jessica, additional, Ueyama, Masahito, additional, Valach, Alex C., additional, Vargas, Rodrigo, additional, Varlagin, Andrej, additional, Vazquez-Lule, Alma, additional, Verfaillie, Joseph G., additional, Vesala, Timo, additional, Vourlitis, George L., additional, Ward, Eric J., additional, Wille, Christian, additional, Wohlfahrt, Georg, additional, Wong, Guan Xhuan, additional, Zhang, Zhen, additional, Zona, Donatella, additional, Windham-Myers, Lisamarie, additional, Poulter, Benjamin, additional, and Jackson, Robert B., additional
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- 2021
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30. Volatile organic compound fluxes in a subarctic peatland and lake
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Seco, Roger, primary, Holst, Thomas, additional, Matzen, Mikkel Sillesen, additional, Westergaard-Nielsen, Andreas, additional, Li, Tao, additional, Simin, Tihomir, additional, Jansen, Joachim, additional, Crill, Patrick, additional, Friborg, Thomas, additional, Rinne, Janne, additional, and Rinnan, Riikka, additional
- Published
- 2020
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31. Temperature Proxies as a Solution to Biased Sampling of Lake Methane Emissions
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Jansen, Joachim, primary, Thornton, Brett F., additional, Wik, Martin, additional, MacIntyre, Sally, additional, and Crill, Patrick M., additional
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- 2020
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32. Supplementary material to "Volatile Organic Compound fluxes in a subarctic peatland and lake"
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Seco, Roger, primary, Holst, Thomas, additional, Matzen, Mikkel Sillesen, additional, Westergaard-Nielsen, Andreas, additional, Li, Tao, additional, Simin, Tihomir, additional, Jansen, Joachim, additional, Crill, Patrick, additional, Friborg, Thomas, additional, Rinne, Janne, additional, and Rinnan, Riikka, additional
- Published
- 2020
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33. Drivers of diffusive CH<sub>4</sub> emissions from shallow subarctic lakes on daily to multi-year timescales
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Jansen, Joachim, primary, Thornton, Brett F., additional, Cortés, Alicia, additional, Snöälv, Jo, additional, Wik, Martin, additional, MacIntyre, Sally, additional, and Crill, Patrick M., additional
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- 2020
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34. Universal design of the largest waterpark in Scandinavia
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Jansen, Joachim Kaland, Tufte, Thea, and Mæland, Kari Aase
- Abstract
Bacheloroppgave i ergoterapi, Høgskulen på Vestlandet BER332
- Published
- 2020
35. Drivers of diffusive lake CH4 emissions on daily to multi-year time scales
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Jansen, Joachim, Thornton, Brett F., Cortés, Alicia, Snöälv, Jo, Wik, Martin, MacIntyre, Sally, and Crill, Patrick M.
- Subjects
Climate Research ,Geosciences, Multidisciplinary ,Miljövetenskap ,Multidisciplinär geovetenskap ,Environmental Sciences ,Klimatforskning - Abstract
Lakes and reservoirs are important emitters of climate forcing trace gases. Various environmental drivers of the flux, such as temperature and wind speed, have been identified, but their relative importance remains poorly understood. Here we use an extensive field dataset to disentangle physical and biogeochemical controls on the turbulence-driven diffusive flux of methane (CH4) on daily to multi-year timescales. We compare 8 years of floating chamber fluxes from three small, shallow subarctic lakes (2010–2017, n = 1306) with fluxes computed using 9 years of surface water concentration measurements (2009–2017, n = 606) and a small-eddy surface renewal model informed by in situ meteorological observations. Chamber fluxes averaged 6.9 ± 0.3 mg m−2 d−1 and gas transfer velocities (k600) from the chamber-calibrated surface renewal model averaged 4.0 ± 0.1 cm h−1. We find robust (R2 ≥ 0.93, p
- Published
- 2020
36. Carbon trace gas dynamics in subarctic lakes
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Jansen, Joachim
- Subjects
climate change ,Geochemistry ,gas transfer ,methane ,lakes ,carbon dioxide ,proxy ,Geokemi ,fluxes - Abstract
Northern lakes are important sources of greenhouse gases carbon dioxide and methane to the atmosphere. Emissions are expected to increase as the climate continues to warm. Even so, lake carbon budgets are currently poorly constrained. This is in part because of a limited understanding of the processes that govern the flux. This thesis focuses on the physical and biogeochemical drivers of carbon trace gas emissions from three small, post-glacial lakes situated within the Stordalen Mire, a subarctic peatland underlain by thawing permafrost in northern Sweden. A unique, multiyear dataset is used to quantify the importance of different emission pathways – ebullition, turbulence-driven diffusion and release from storage – on short and long timescales. In summer and on seasonal to interannual timescales, emissions are robust functions of thermal energy input. Short-term storage-and-release cycles are governed by kinetic drivers, such as turbulence fuelled by wind shear and, to a lesser extent, by thermal convection. In winter, when the lakes are ice-covered, persistent anoxia and density-driven currents enable methane accumulation at rates exceeding summer emissions. Release at ice-off in spring can constitute the majority of annual methane emissions and scales predictably with ice-cover season length, except in warm winters when snowmelt displaces lake water. Most lake flux studies focus on the warmest summer months and omit the spring efflux, as well as emissions in the colder ice-free months which, because of the well-known temperature-dependency of carbon cycling processes, tend to be low. The latter sampling bias may lead to a substantial overestimation of the ice-free flux in regional and global lake emission budgets. Temperature proxies, potentially combined with gas transfer models, can efficiently gap-fill colder months to arrive at a more representative flux estimate, but important feedbacks, such as lake degassing with increasing wind speed, must be taken into account. The mechanisms emerging from intense study of the Stordalen lakes are likely to be found in a majority of northern lakes, which are small, seasonally ice-covered and of post-glacial origin. However, because gas transfer velocity and temperature sensitivity are spatiotemporally variable, field observations remain essential for the development and calibration of models, and to predict future emissions. At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Submitted. Paper 3: Manuscript.
- Published
- 2020
37. Volatile organic compound fluxes in a subarctic peatland and lake
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Seco, Roger, Holst, Thomas, Sillesen Matzen, Mikkel, Westergaard-Nielsen, Andreas, Li, Tao, Simin, Tihomir, Jansen, Joachim, Crill, Patrick, Friborg, Thomas, Rinne, Janne, Rinnan, Riikka, Seco, Roger, Holst, Thomas, Sillesen Matzen, Mikkel, Westergaard-Nielsen, Andreas, Li, Tao, Simin, Tihomir, Jansen, Joachim, Crill, Patrick, Friborg, Thomas, Rinne, Janne, and Rinnan, Riikka
- Abstract
Ecosystems exchange climate-relevant trace gases with the atmosphere, including volatile organic compounds (VOCs) that are a small but highly reactive part of the carbon cycle. VOCs have important ecological functions and implications for atmospheric chemistry and climate. We measured the ecosystem-level surface-atmosphere VOC fluxes using the eddy covariance technique at a shallow subarctic lake and an adjacent graminoid-dominated fen in northern Sweden during two contrasting periods: the peak growing season (mid-July) and the senescent period post-growing season (September-October). In July, the fen was a net source of methanol, acetaldehyde, acetone, dimethyl sulfide, isoprene, and monoterpenes. All of these VOCs showed a did cycle of emission with maxima around noon and isoprene dominated the fluxes (93 +/- 22 mu mol m(-2) d(-1), mean +/- SE). Isoprene emission was strongly stimulated by temperature and presented a steeper response to temperature (Q(10) = 14.5) than that typically assumed in biogenic emission models, supporting the high temperature sensitivity of arctic vegetation. In September, net emissions of methanol and isoprene were drastically reduced, while acetaldehyde and acetone were deposited to the fen, with rates of up to -6.7 +/- 2.8 mu mol m(-2) d(-1) for acetaldehyde. Remarkably, the lake was a sink for acetaldehyde and acetone during both periods, with average fluxes up to -19 +/- 1.3 mu mol m(-2) d(-1) of acetone in July and up to -8.5 +/- 2.3 mu mol m(-2) d(-1) of acetaldehyde in September. The deposition of both carbonyl compounds correlated with their atmospheric mixing ratios, with deposition velocities of -0.23 +/- 0.01 and -0.68 +/- 0.03 cm s(-1) for acetone and acetaldehyde, respectively. Even though these VOC fluxes represented less than 0.5 % and less than 5 % of the CO2 and CH4 net carbon ecosystem exchange, respectively, VOCs alter the oxidation capacity of the atmosphere. Thus, understanding the response of their emissions to clima
- Published
- 2020
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38. Temperature Proxies as a Solution to Biased Sampling of Lake Methane Emissions
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Jansen, Joachim, Thornton, Brett F., Wik, Martin, MacIntyre, Sally, Crill, Patrick M., Jansen, Joachim, Thornton, Brett F., Wik, Martin, MacIntyre, Sally, and Crill, Patrick M.
- Abstract
Lake emissions of the climate forcing trace gas methane (CH4) are spatiotemporally variable, but biases in flux measurements arising from undersampling are poorly quantified. We use a multiyear data set (2009-2017) of ice-free CH(4)emissions from three subarctic lakes obtained with bubble traps (n = 14,677), floating chambers (n = 1,306), and surface concentrations plus a gas transfer model (n = 535) to quantify these biases and evaluate corrections. Sampling primarily in warmer summer months, as is common, overestimates the ice-free season flux by a factor 1.4-1.8. Temperature proxies based on Arrhenius functions that closely fit measured fluxes (R-2 >= 0.93) enable gap filling the colder months of the ice-free season and reduce sampling bias. Ebullition (activation energy 1.36 eV) expressed greater temperature sensitivity than diffusion (1.00 eV). Resolving seasonal and interannual variability in fluxes with proxies requires similar to 135 sampling days for ebullition, and 22 and 14 days for diffusion via models and chambers, respectively.
- Published
- 2020
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39. Response to RC2
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Jansen, Joachim, primary
- Published
- 2019
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40. Supplementary material to "Drivers of diffusive lake CH<sub>4</sub> emissions on daily to multi-year time scales"
- Author
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Jansen, Joachim, primary, Thornton, Brett F., additional, Cortes, Alicia, additional, Snöälv, Jo, additional, Wik, Martin, additional, MacIntyre, Sally, additional, and Crill, Patrick M., additional
- Published
- 2019
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41. Drivers of diffusive lake CH4 emissions on daily to multi-year time scales
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Jansen, Joachim, primary, Thornton, Brett F., additional, Cortes, Alicia, additional, Snöälv, Jo, additional, Wik, Martin, additional, MacIntyre, Sally, additional, and Crill, Patrick M., additional
- Published
- 2019
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42. Climate‐Sensitive Controls on Large Spring Emissions of CH4 and CO2 From Northern Lakes
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Jansen, Joachim, Thornton, Brett F., Jammet, Mathilde M., Wik, Martin, Cortés, Alicia, Friborg, Thomas, MacIntyre, Sally, Crill, Patrick M., Jansen, Joachim, Thornton, Brett F., Jammet, Mathilde M., Wik, Martin, Cortés, Alicia, Friborg, Thomas, MacIntyre, Sally, and Crill, Patrick M.
- Abstract
Northern lakes are important sources of the climate forcing trace gases methane (CH4) and carbon dioxide (CO2). A substantial portion of lakes' annual emissions can take place immediately after ice melt in spring. The drivers of these fluxes are neither well constrained nor fully understood. We present a detailed carbon gas budget for three subarctic lakes, using 6 years of eddy covariance and 9 years of manual flux measurements. We combine measurements of temperature, dissolved oxygen, and CH4 stable isotopologues to quantify functional relationships between carbon gas production and conversion, energy inputs, and the redox regime. Spring emissions were regulated by the availability of oxygen in winter, rather than temperature as during ice‐free conditions. Under‐ice storage increased predictably with ice‐cover duration, and CH4 accumulation rates (25 ± 2 mg CH4‐C·m−2·day−1) exceeded summer emissions (19 ± 1 mg CH4‐C·m−2·day−1). The seasonally ice‐covered lakes emitted 26–59% of the annual CH4 flux and 15–30% of the annual CO2 flux at ice‐off. Reduced spring emissions were associated with winter snowmelt events, which can transport water downstream and oxygenate the water column. Stable isotopes indicate that 64–96% of accumulated CH4 escaped oxidation, implying that a considerable portion of the dissolved gases produced over winter may evade to the atmosphere.
- Published
- 2019
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43. Advanced Techniques for Grounding and Solving in the IDP Knowledge Base System : Geavanceerde technieken voor grounden en solven in het IDP kennisbanksysteem
- Author
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Jansen, Joachim, Denecker, Marc, and Janssens, Gerda
- Abstract
The area of Knowledge Representation and Reasoning, a subfield of Artificial Intelligence, studies how knowledge can be represented and how it can be used for automated reasoning. Several declarative programming paradigms implement this by developing a formal language to symbolically represent knowledge, as well as an associated form of inference to achieve the desired solution. Recently, the Knowledge Base System (KBS) paradigm has been proposed, based on the idea that knowledge is not inherently linked to a specific reasoning task. Instead, this paradigm proposes to express knowledge in a truly declarative manner. Additionally, to stress reusability of this knowledge, the KBS paradigm allows the knowledge to be combined with one out of a set of possible inferences, each providing a solution to some type of computational task. The initial implementation of this KBS paradigm, also known as the IDP3 system, provided a suitable laboratory to examine a new type of software engineering. State-of-the-art declarative programming systems such as IDP3, clasp, WASP, and lp2sat work using the ground-and-solve methodology. First, the high-level language is ground into a low-level propositional language. As a second step the grounding is used as input for general-purpose, low-level propositional (generally SAT-like) solvers. This thesis contains a thorough study of the impact of different grounding approaches on the solver behaviour. I.e., if the grounding process that is used is smart and results in a smaller low-level representation, does this impact the search behaviour of the underlying solver? The language supported by the IDP3 system contains constraints and definitions. For the purpose of this thesis, we split up definitions into two kinds: input* (also called intentional or stratified predicates, or domain atoms) and search definitions. Input* definitions are definitions that depend on concepts that are known beforehand and can be evaluated. One contribution of this thesis is the evaluation of input* definitions using Tabled Prolog. In order to use these techniques, definitions have to be transformed into a format usable by Prolog. The main challenge in this transformation is correctly projecting away the types and rich language constructs, whilst taking into acount Prolog's left-to-right execution mechanism. Search definitions on the other hand cannot be evaluated because they depend on unknown data. This text elaborates how the above translation to Prolog can be re-used: 1) to partially evaluate definitions, deriving as much information as possible, and 2) ground definitions using a Tabled Prolog execution mechanism. We developed a method to guide the solver to focus on relevant parts in the search space. Only the part of the specification that is linked with the current search branch of the problem has to be taken into account. The goal of this technique is to prevent certain decisions from being made once it is possible to prove that they will not influence the outcome of searching in the current search branch. Additionally, this leads us to an improved stopping criterion for SAT(ID) solvers since any state without relevant decisions is considered an end state, instead of only states in which all literals have been decided. An implementation of technique is presented. The implementation uses a incremental approach, adjusting certain data structures based on the changes in the solver state. With this work we intend to increase the usability of the IDP3 system and elevate it to a "mature" Knowledge Base System. Abstract iii Contents vii List of Acronyms xi List of Symbols xiii List of Figures xvii List of Tables xix 1 Introduction 1 2 Preliminaries: FO(·) 7 2.1 Some Mathematical Basics 7 2.1.1 Sets 7 2.1.2 Lists 8 2.1.3 Type 9 2.1.4 Typings and Tuples 9 2.1.5 Functions 9 2.1.6 Predicate 10 2.2 The Language FO(·) 10 2.2.1 Vocabulary Σ 11 2.2.2 Interpretation I 13 2.2.3 Theory T 17 2.2.4 Concluding Example: Sudoku 21 2.3 Semantics for FO(·) 23 2.3.1 Evaluating a Term in a Structure 24 2.3.2 Semantics of Formulas 24 2.3.3 Semantics of Definitions 24 2.4 Conclusion 26 3 Preliminaries: KBS and IDP 27 3.1 KBS paradigm: Inferences as Tools for Solving Problems 27 3.1.1 Inferences 28 3.1.2 Advantages of the KBS Paradigm 30 3.2 The IDP System 30 3.2.1 The Grounder of IDP 31 3.2.2 The Solver of IDP 40 3.3 Conclusion 43 4 Experimental Evaluation of a State-of-the-art Grounder 45 4.1 Grounding Technique Experiments 46 4.1.1 Experimental Evaluation of RED 49 4.1.2 Experimental Evaluation of LUP 51 4.1.3 Experimental Evaluation of GWB 52 4.2 Solver Behaviour on Optimized Ground Theories 53 4.3 Conclusion 60 5 Complementing the IDP3 system with XSB 63 5.1 Preliminaries 63 5.1.1 Workflow Analysis of IDP3 64 5.1.2 The Calculating Definitions Step 65 5.2 Evaluating input∗ Symbols With XSB 69 5.2.1 Translating FO(·) to a tabled Prolog Program 69 5.2.2 Choosing and Configuring a Prolog System 79 5.2.3 Calling XSB from IDP3 80 5.3 Experimental Evaluation 81 5.4 Refining Definitions With XSB 84 5.5 Conclusion 88 6 Relevance for SAT(ID) 91 6.1 Introduction 91 6.2 Preliminaries 93 6.2.1 PC(ID) 93 6.2.2 Justifications 94 6.3 Relevance 96 6.3.1 Observations 96 6.3.2 Exploiting Relevance 99 6.4 Implementing Relevance as part of an Existing SAT(ID) Solver 100 6.4.1 The Basic Framework 100 6.4.2 Deriving the Justification Status of Literals 101 6.4.3 Implementing the Relevance Tracker 103 6.5 Experimental Evaluation 109 6.6 Conclusion 114 7 Conclusion 117 7.1 Contributions and Conclusions 117 7.2 Future Research Ideas 119 A Additional XSB Prolog code 121 A.1 The forall/2 Predicate in XSB 121 A.2 Translation of IDP3 Built-in Arithmetic Operators to XSB Prolog Code 121 A.3 Translation of IDP3 Aggregate Terms to XSB Prolog Code 123 Bibliography 125 Curriculum Vitae 135 List of Publications 137 status: published
- Published
- 2016
44. The origin of methane in the East Siberian Arctic Shelf unraveled with triple isotope analysis
- Author
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Sapart, Célia J., primary, Shakhova, Natalia, additional, Semiletov, Igor, additional, Jansen, Joachim, additional, Szidat, Sönke, additional, Kosmach, Denis, additional, Dudarev, Oleg, additional, van der Veen, Carina, additional, Egger, Matthias, additional, Sergienko, Valentine, additional, Salyuk, Anatoly, additional, Tumskoy, Vladimir, additional, Tison, Jean-Louis, additional, and Röckmann, Thomas, additional
- Published
- 2017
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45. Translating ASP to a typed language without Herbrand functions
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Jansen, Joachim and Janssens, Gerda
- Subjects
ASP ,IDP3 ,Theory transformation ,Type derivation - Abstract
Answer Set Programming (ASP) and FO(·) are two similar state-of-the-art languages for declarative problem solving. This paper presents an automatic transformation from ASP programs to FO(·) programs for the IDP3 system. There are two main language differences that have to be overcome. Firstly there is the introduction of types, which are mandatory in FO(·) but not present in ASP. Secondly there are Herbrand function terms that are present in ASP but not sufficiently supported in IDP3. In this paper we give a short overview of both languages and introduce our transformation that overcomes these differences in the respective languages. ispartof: pages:1-14 ispartof: Proceedings of the 3d Workshop on Grounding, Transforming, and Modularizing Theories with Variables pages:1-14 ispartof: Workshop on Grounding, Transforming, and Modularizing Theories with Variables location:Lexington, KY, USA date:27 Sep - 27 Sep 2015 status: published
- Published
- 2015
46. Drivers of diffusive lake CH4 emissions on daily to multi-year time scales.
- Author
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Jansen, Joachim, Thornton, Brett F., Cortes, Alicia, Snöälv, Jo, Wik, Martin, MacIntyre, Sally, and Crill, Patrick M.
- Subjects
WIND speed ,METEOROLOGICAL observations ,WIND shear ,ENVIRONMENTAL engineering ,WATER ,WATER temperature ,TRACE gases - Abstract
Lakes and reservoirs are important emitters of climate forcing trace gases. Various environmental drivers of the flux, such as temperature and wind speed, have been identified, but their relative importance remains poorly understood. Here we use an extensive field dataset to disentangle physical and biogeochemical controls on the turbulence-driven diffusive flux of methane (CH
4 ) on daily to multi-year timescales. We compare 8 years of floating chamber fluxes from three small, shallow subarctic lakes (2010-2017, n = 1306) with fluxes computed using 9 years of surface water concentration measurements (2009-2017, n = 606) and a small-eddy surface renewal model informed by in situ meteorological observations. Chamber fluxes averaged 6.9 ± 0.3 mg m-2 d-1 and gas transfer velocities (k600 ) from the chamber-calibrated surface renewal model averaged 4.0 ± 0.1 cm h-1 . We find robust (R2 ≥ 0.93, p < 0.01) Arrhenius-type temperature functions of the CH4 flux (Ea ' = 0.90 ± 0.14 eV) and of the surface CH4 concentration (Ea ' = 0.88 ± 0.09 eV). Chamber derived gas transfer velocities tracked the power-law wind speed relation of the model (k ∝ u3/4 ). While the flux increased with wind speed, during storm events (U10 ≥ 6.5 m s-1 ) emissions were reduced by rapid water column degassing. Spectral analysis revealed that on timescales shorter than a month emissions were driven by wind shear, but on longer timescales variations in water temperature governed the flux, suggesting emissions were strongly coupled to production. Our findings suggest that accurate short- and long term projections of lake CH4 emissions can be based on distinct weather- and climate controlled drivers of the flux. [ABSTRACT FROM AUTHOR]- Published
- 2019
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47. The origin of methane in the East Siberian Arctic Shelf unraveled with triple isotope analysis
- Author
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Sapart, Célia J., Shakhova, Natalia, Semiletov, Igor, Jansen, Joachim, Szidat, Sönke, Kosmach, Denis, Dudarev, Oleg, van der Veen, Carina, Egger, M.J., Sergienko, Valentine, Salyuk, Anatoly, Tumskoy, Vladimir, Tison, Jean-Louis, Röckmann, Thomas, Sapart, Célia J., Shakhova, Natalia, Semiletov, Igor, Jansen, Joachim, Szidat, Sönke, Kosmach, Denis, Dudarev, Oleg, van der Veen, Carina, Egger, M.J., Sergienko, Valentine, Salyuk, Anatoly, Tumskoy, Vladimir, Tison, Jean-Louis, and Röckmann, Thomas
- Abstract
The Arctic Ocean, especially the East Siberian Arctic Shelf (ESAS), has been proposed as a significant source of methane that might play an increasingly important role in the future. However, the underlying processes of formation, removal and transport associated with such emissions are to date strongly debated. CH4 concentration and triple isotope composition were analyzed on gas extracted from sediment and water sampled at numerous locations on the shallow ESAS from 2007 to 2013. We find high concentrations (up to 500 µM) of CH4 in the pore water of the partially thawed subsea permafrost of this region. For all sediment cores, both hydrogen and carbon isotope data reveal the predominant occurrence of CH4 that is not of thermogenic origin as it has long been thought, but resultant from microbial CH4 formation. At some locations, meltwater from buried meteoric ice and/or old organic matter preserved in the subsea permafrost were used as substrates. Radiocarbon data demonstrate that the CH4 present in the ESAS sediment is of Pleistocene age or older, but a small contribution of highly 14C-enriched CH4, from unknown origin, prohibits precise age determination for one sediment core and in the water column. Our sediment data suggest that at locations where bubble plumes have been observed, CH4 can escape anaerobic oxidation in the surface sediment.
- Published
- 2017
48. The origin of methane in the East Siberian Arctic Shelf unraveled with triple isotope analysis
- Author
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Sapart, Célia, Sergienko, Valentine, Salyuk, Anatoly, Tumskoy, Vladimir, Tison, Jean-Louis, Röckmann, Thomas, Shakhova, Natalia, Semiletov, Igor, Jansen, Joachim, Szidat, Sönke, Kosmach, Denis, Dudarev, Oleg, Van der Veen, Carina, Egger, Matthias, Sapart, Célia, Sergienko, Valentine, Salyuk, Anatoly, Tumskoy, Vladimir, Tison, Jean-Louis, Röckmann, Thomas, Shakhova, Natalia, Semiletov, Igor, Jansen, Joachim, Szidat, Sönke, Kosmach, Denis, Dudarev, Oleg, Van der Veen, Carina, and Egger, Matthias
- Abstract
The Arctic Ocean, especially the East Siberian Arctic Shelf (ESAS), has been proposed as a significant source of methane that might play an increasingly important role in the future. However, the underlying processes of formation, removal and transport associated with such emissions are to date strongly debated. CH4 concentration and triple isotope composition were analyzed on gas extracted from sediment and water sampled at numerous locations on the shallow ESAS from 2007 to 2013. We find high concentrations (up to 500 μM) of CH4 in the pore water of the partially thawed subsea permafrost of this region. For all sediment cores, both hydrogen and carbon isotope data reveal the predominant occurrence of CH4 that is not of thermogenic origin as it has long been thought, but resultant from microbial CH4 formation. At some locations, meltwater from buried meteoric ice and/or old organic matter preserved in the subsea permafrost were used as substrates. Radiocarbon data demonstrate that the CH4 present in the ESAS sediment is of Pleistocene age or older, but a small contribution of highly 14C-enriched CH4, from unknown origin, prohibits precise age determination for one sediment core and in the water column. Our sediment data suggest that at locations where bubble plumes have been observed, CH4 can escape anaerobic oxidation in the surface sediment., SCOPUS: ar.j, info:eu-repo/semantics/published
- Published
- 2017
49. The origin of methane in the East Siberian Arctic Shelf unraveled with triple isotope analysis
- Author
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ERC-PHOXY: Phosphorus dynamics in low-oxygen marine systems: quantifying the nutrient-climate connection in Earth’s past, present and future, General geochemistry, Sub Atmospheric physics and chemistry, Sub Algemeen Marine & Atmospheric Res, Geochemistry, Sapart, Célia J., Shakhova, Natalia, Semiletov, Igor, Jansen, Joachim, Szidat, Sönke, Kosmach, Denis, Dudarev, Oleg, van der Veen, Carina, Egger, M.J., Sergienko, Valentine, Salyuk, Anatoly, Tumskoy, Vladimir, Tison, Jean-Louis, Röckmann, Thomas, ERC-PHOXY: Phosphorus dynamics in low-oxygen marine systems: quantifying the nutrient-climate connection in Earth’s past, present and future, General geochemistry, Sub Atmospheric physics and chemistry, Sub Algemeen Marine & Atmospheric Res, Geochemistry, Sapart, Célia J., Shakhova, Natalia, Semiletov, Igor, Jansen, Joachim, Szidat, Sönke, Kosmach, Denis, Dudarev, Oleg, van der Veen, Carina, Egger, M.J., Sergienko, Valentine, Salyuk, Anatoly, Tumskoy, Vladimir, Tison, Jean-Louis, and Röckmann, Thomas
- Published
- 2017
50. Refining definitions with unknown opens using XSB for IDP3
- Author
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Jansen, Joachim, Janssens, Gerda, Ströder, Thomas, and Swift, Terrance
- Subjects
IDP3 ,Definition refinement ,Partial evaluation ,XSB - Abstract
FO(·)IDP3 is a declarative modeling language that extends first-order logic with inductive definitions, partial functions, types and aggregates. Its model generator IDP3 grounds the problem into a low-level (propositional) representation and consequently use a generic solver to search for a solution. Recent work introduced a technique that evaluates all definitions that depend on fully known information before the grounding step. In this paper, we extend this technique, which allows us to refine the interpretation of defined symbols when they depend on information that is only partially given instead of completely given. We use our existing transformation of FO(·)IDP3 definitions to Tabled Prolog rules and extend it to support definitions that depend on information that is possibly partially unknown. In this paper we present an algorithm that uses XSB Prolog to evaluate these rules in such a way that we achieve the most precise possible refinement of the defined symbols. Experimental results show that our technique derives extra information for the defined symbols. ispartof: pages:15-29 ispartof: Proceedings of the international joint workshop on implementation of constraint and logic programming systems and logic-based methods in programming environments 2014 pages:15-29 ispartof: International Joint Workshop on Implementation of Constraint and Logic Programming Systems and Logic-based Methods in Programming Environments location:Vienna, Austria date:17 Jul - 18 Jul 2014 status: published
- Published
- 2014
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