--- _id: '11864' abstract: - lang: eng text: Auctions are widely used on the Web. Applications range from internet advertising to platforms such as eBay. In most of these applications the auctions in use are single/multi-item auctions with unit demand. The main drawback of standard mechanisms for this type of auctions, such as VCG and GSP, is the limited expressiveness that they offer to the bidders. The General Auction Mechanism (GAM) of [1] is taking a first step towards addressing the problem of limited expressiveness by computing a bidder optimal, envy free outcome for linear utility functions with identical slopes and a single discontinuity per bidder-item pair. We show that in many practical situations this does not suffice to adequately model the preferences of the bidders, and we overcome this problem by presenting the first mechanism for piece-wise linear utility functions with non-identical slopes and multiple discontinuities. Our mechanism runs in polynomial time. Like GAM it is incentive compatible for inputs that fulfill a certain non-degeneracy requirement, but our requirement is more general than the requirement of GAM. For discontinuous utility functions that are non-degenerate as well as for continuous utility functions the outcome of our mechanism is a competitive equilibrium. We also show how our mechanism can be used to compute approximately bidder optimal, envy free outcomes for a general class of continuous utility functions via piece-wise linear approximation. Finally, we prove hardness results for even more expressive settings. article_processing_charge: No author: - first_name: Paul full_name: Dütting, Paul last_name: Dütting - first_name: Monika H full_name: Henzinger, Monika H id: 540c9bbd-f2de-11ec-812d-d04a5be85630 last_name: Henzinger orcid: 0000-0002-5008-6530 - first_name: Ingmar full_name: Weber, Ingmar last_name: Weber citation: ama: 'Dütting P, Henzinger MH, Weber I. An expressive mechanism for auctions on the web. In: Proceedings of the 20th International Conference on World Wide Web. Association for Computing Machinery; 2011:127-136. doi:10.1145/1963405.1963427' apa: 'Dütting, P., Henzinger, M. H., & Weber, I. (2011). An expressive mechanism for auctions on the web. In Proceedings of the 20th international conference on World wide web (pp. 127–136). Hyderabad, India: Association for Computing Machinery. https://doi.org/10.1145/1963405.1963427' chicago: Dütting, Paul, Monika H Henzinger, and Ingmar Weber. “An Expressive Mechanism for Auctions on the Web.” In Proceedings of the 20th International Conference on World Wide Web, 127–36. Association for Computing Machinery, 2011. https://doi.org/10.1145/1963405.1963427. ieee: P. Dütting, M. H. Henzinger, and I. Weber, “An expressive mechanism for auctions on the web,” in Proceedings of the 20th international conference on World wide web, Hyderabad, India, 2011, pp. 127–136. ista: 'Dütting P, Henzinger MH, Weber I. 2011. An expressive mechanism for auctions on the web. Proceedings of the 20th international conference on World wide web. WWW: International Conference on World Wide Web, 127–136.' mla: Dütting, Paul, et al. “An Expressive Mechanism for Auctions on the Web.” Proceedings of the 20th International Conference on World Wide Web, Association for Computing Machinery, 2011, pp. 127–36, doi:10.1145/1963405.1963427. short: P. Dütting, M.H. Henzinger, I. Weber, in:, Proceedings of the 20th International Conference on World Wide Web, Association for Computing Machinery, 2011, pp. 127–136. conference: end_date: 2011-04-01 location: Hyderabad, India name: 'WWW: International Conference on World Wide Web' start_date: 2011-03-28 date_created: 2022-08-16T09:05:34Z date_published: 2011-04-01T00:00:00Z date_updated: 2023-02-17T10:21:18Z day: '01' doi: 10.1145/1963405.1963427 extern: '1' language: - iso: eng month: '04' oa_version: None page: 127 - 136 publication: Proceedings of the 20th international conference on World wide web publication_identifier: isbn: - 978-145030632-4 publication_status: published publisher: Association for Computing Machinery quality_controlled: '1' scopus_import: '1' status: public title: An expressive mechanism for auctions on the web type: conference user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87 year: '2011' ... --- _id: '12651' abstract: - lang: eng text: Temperature data from three Automatic Weather Stations and twelve Temperature Loggers are used to investigate the spatiotemporal variability of temperature over a glacier, its main atmospheric controls, the suitability of extrapolation techniques and their effect on melt modeling. We use data collected on Juncal Norte Glacier, central Chile, during one ablation season. We examine temporal and spatial variability in lapse rates (LRs), together with alternative statistical interpolation methods. The main control over the glacier thermal regime is the development of a katabatic boundary layer (KBL). Katabatic wind occurs at night and in the morning and is eroded in the afternoon. LRs reveal strong diurnal variability, with steeper LRs during the day when the katabatic wind weakens and shallower LRs during the night and morning. We suggest that temporally variable LRs should be used to account for the observed change. They tend to be steeper than equivalent constant LRs, and therefore result in a reduction in simulated melt compared to use of constant LRs when extrapolating from lower to higher elevations. In addition to the temporal variability, the temperature-elevation relationship varies also in space. Differences are evident between local LRs and including such variability in melt modeling affects melt simulations. Extrapolation methods based on the spatial variability of the observations after removal of the elevation trend, such as Inverse Distance Weighting or Kriging, do not seem necessary for simulations of gridded temperature data over a glacier. article_number: D23109 article_processing_charge: No article_type: original author: - first_name: L. full_name: Petersen, L. last_name: Petersen - first_name: Francesca full_name: Pellicciotti, Francesca id: b28f055a-81ea-11ed-b70c-a9fe7f7b0e70 last_name: Pellicciotti citation: ama: 'Petersen L, Pellicciotti F. Spatial and temporal variability of air temperature on a melting glacier: Atmospheric controls, extrapolation methods and their effect on melt modeling, Juncal Norte Glacier, Chile. Journal of Geophysical Research: Atmospheres. 2011;116(D23). doi:10.1029/2011jd015842' apa: 'Petersen, L., & Pellicciotti, F. (2011). Spatial and temporal variability of air temperature on a melting glacier: Atmospheric controls, extrapolation methods and their effect on melt modeling, Juncal Norte Glacier, Chile. Journal of Geophysical Research: Atmospheres. American Geophysical Union. https://doi.org/10.1029/2011jd015842' chicago: 'Petersen, L., and Francesca Pellicciotti. “Spatial and Temporal Variability of Air Temperature on a Melting Glacier: Atmospheric Controls, Extrapolation Methods and Their Effect on Melt Modeling, Juncal Norte Glacier, Chile.” Journal of Geophysical Research: Atmospheres. American Geophysical Union, 2011. https://doi.org/10.1029/2011jd015842.' ieee: 'L. Petersen and F. Pellicciotti, “Spatial and temporal variability of air temperature on a melting glacier: Atmospheric controls, extrapolation methods and their effect on melt modeling, Juncal Norte Glacier, Chile,” Journal of Geophysical Research: Atmospheres, vol. 116, no. D23. American Geophysical Union, 2011.' ista: 'Petersen L, Pellicciotti F. 2011. Spatial and temporal variability of air temperature on a melting glacier: Atmospheric controls, extrapolation methods and their effect on melt modeling, Juncal Norte Glacier, Chile. Journal of Geophysical Research: Atmospheres. 116(D23), D23109.' mla: 'Petersen, L., and Francesca Pellicciotti. “Spatial and Temporal Variability of Air Temperature on a Melting Glacier: Atmospheric Controls, Extrapolation Methods and Their Effect on Melt Modeling, Juncal Norte Glacier, Chile.” Journal of Geophysical Research: Atmospheres, vol. 116, no. D23, D23109, American Geophysical Union, 2011, doi:10.1029/2011jd015842.' short: 'L. Petersen, F. Pellicciotti, Journal of Geophysical Research: Atmospheres 116 (2011).' date_created: 2023-02-20T08:18:14Z date_published: 2011-12-16T00:00:00Z date_updated: 2023-02-20T10:29:44Z day: '16' doi: 10.1029/2011jd015842 extern: '1' intvolume: ' 116' issue: D23 keyword: - Paleontology - Space and Planetary Science - Earth and Planetary Sciences (miscellaneous) - Atmospheric Science - Earth-Surface Processes - Geochemistry and Petrology - Soil Science - Water Science and Technology - Ecology - Aquatic Science - Forestry - Oceanography - Geophysics language: - iso: eng main_file_link: - open_access: '1' url: https://doi.org/10.1029/2011JD01584 month: '12' oa: 1 oa_version: Published Version publication: 'Journal of Geophysical Research: Atmospheres' publication_identifier: issn: - 0148-0227 publication_status: published publisher: American Geophysical Union quality_controlled: '1' scopus_import: '1' status: public title: 'Spatial and temporal variability of air temperature on a melting glacier: Atmospheric controls, extrapolation methods and their effect on melt modeling, Juncal Norte Glacier, Chile' type: journal_article user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87 volume: 116 year: '2011' ... --- _id: '12649' abstract: - lang: eng text: Physically based hydrological models describe natural processes more accurately than conceptual models but require extensive data sets to produce accurate results. To identify the value of different data sets for improving the performance of the distributed hydrological model TOPKAPI we combine a multivariable validation technique with Monte Carlo simulations. The study is carried out in the snow and ice-dominated Rhonegletscher basin, as these types of mountainous basins are generally the most critical with respect to data availability and sensitivity to climate fluctuations. Each observational data set is used individually and in combination with the other data sets to determine a subset of best parameter combinations out of 10,000 Monte Carlos runs performed with randomly generated parameter sets. We validate model results against discharge, glacier mass balance, and satellite snow cover images for a 14 year time period (1994–2007). While the use of all data sets combined provides the best overall model performance (defined by the concurrent best agreement of simulated discharge, snow cover and mass balance with their respective measurements), the use of one or two variables for constraining the model results in poorer performance. Using only one data set for constraining the model glacier mass balance proved to be the most efficient observation leading to the best overall model performance. Our main result is that a combination of discharge and satellite snow cover images is best for improving model performance, since the volumetric information of discharge data and the spatial information of snow cover images are complementary. article_number: W07519 article_processing_charge: No article_type: original author: - first_name: David full_name: Finger, David last_name: Finger - first_name: Francesca full_name: Pellicciotti, Francesca id: b28f055a-81ea-11ed-b70c-a9fe7f7b0e70 last_name: Pellicciotti - first_name: Markus full_name: Konz, Markus last_name: Konz - first_name: Stefan full_name: Rimkus, Stefan last_name: Rimkus - first_name: Paolo full_name: Burlando, Paolo last_name: Burlando citation: ama: Finger D, Pellicciotti F, Konz M, Rimkus S, Burlando P. The value of glacier mass balance, satellite snow cover images, and hourly discharge for improving the performance of a physically based distributed hydrological model. Water Resources Research. 2011;47(7). doi:10.1029/2010wr009824 apa: Finger, D., Pellicciotti, F., Konz, M., Rimkus, S., & Burlando, P. (2011). The value of glacier mass balance, satellite snow cover images, and hourly discharge for improving the performance of a physically based distributed hydrological model. Water Resources Research. American Geophysical Union. https://doi.org/10.1029/2010wr009824 chicago: Finger, David, Francesca Pellicciotti, Markus Konz, Stefan Rimkus, and Paolo Burlando. “The Value of Glacier Mass Balance, Satellite Snow Cover Images, and Hourly Discharge for Improving the Performance of a Physically Based Distributed Hydrological Model.” Water Resources Research. American Geophysical Union, 2011. https://doi.org/10.1029/2010wr009824. ieee: D. Finger, F. Pellicciotti, M. Konz, S. Rimkus, and P. Burlando, “The value of glacier mass balance, satellite snow cover images, and hourly discharge for improving the performance of a physically based distributed hydrological model,” Water Resources Research, vol. 47, no. 7. American Geophysical Union, 2011. ista: Finger D, Pellicciotti F, Konz M, Rimkus S, Burlando P. 2011. The value of glacier mass balance, satellite snow cover images, and hourly discharge for improving the performance of a physically based distributed hydrological model. Water Resources Research. 47(7), W07519. mla: Finger, David, et al. “The Value of Glacier Mass Balance, Satellite Snow Cover Images, and Hourly Discharge for Improving the Performance of a Physically Based Distributed Hydrological Model.” Water Resources Research, vol. 47, no. 7, W07519, American Geophysical Union, 2011, doi:10.1029/2010wr009824. short: D. Finger, F. Pellicciotti, M. Konz, S. Rimkus, P. Burlando, Water Resources Research 47 (2011). date_created: 2023-02-20T08:18:03Z date_published: 2011-07-01T00:00:00Z date_updated: 2023-02-20T10:39:57Z day: '01' doi: 10.1029/2010wr009824 extern: '1' intvolume: ' 47' issue: '7' language: - iso: eng main_file_link: - open_access: '1' url: https://doi.org/10.1029/2010WR009824 month: '07' oa: 1 oa_version: Published Version publication: Water Resources Research publication_identifier: issn: - 0043-1397 publication_status: published publisher: American Geophysical Union quality_controlled: '1' scopus_import: '1' status: public title: The value of glacier mass balance, satellite snow cover images, and hourly discharge for improving the performance of a physically based distributed hydrological model type: journal_article user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87 volume: 47 year: '2011' ... --- _id: '12652' abstract: - lang: eng text: We explore the robustness and transferability of parameterizations of cloud radiative forcing used in glacier melt models at two sites in the Swiss Alps. We also look at the rationale behind some of the most commonly used approaches, and explore the relationship between cloud transmittance and several standard meteorological variables. The 2 m air-temperature diurnal range is the best predictor of variations in cloud transmittance. However, linear and exponential parameterizations can only explain 30–50% of the observed variance in computed cloud transmittance factors. We examine the impact of modelled cloud transmittance factors on both solar radiation and ablation rates computed with an enhanced temperature-index model. The melt model performance decreases when modelled radiation is used, the reduction being due to an underestimation of incoming solar radiation on clear-sky days. The model works well under overcast conditions. We also seek alternatives to the use of in situ ground data. However, outputs from an atmospheric model (2.2 km horizontal resolution) do not seem to provide an alternative to the parameterizations of cloud radiative forcing based on observations of air temperature at glacier automatic weather stations. Conversely, the correct definition of overcast conditions is important. article_processing_charge: No article_type: original author: - first_name: Francesca full_name: Pellicciotti, Francesca id: b28f055a-81ea-11ed-b70c-a9fe7f7b0e70 last_name: Pellicciotti - first_name: Thomas full_name: Raschle, Thomas last_name: Raschle - first_name: Thomas full_name: Huerlimann, Thomas last_name: Huerlimann - first_name: Marco full_name: Carenzo, Marco last_name: Carenzo - first_name: Paolo full_name: Burlando, Paolo last_name: Burlando citation: ama: 'Pellicciotti F, Raschle T, Huerlimann T, Carenzo M, Burlando P. Transmission of solar radiation through clouds on melting glaciers: A comparison of parameterizations and their impact on melt modelling. Journal of Glaciology. 2011;57(202):367-381. doi:10.3189/002214311796406013' apa: 'Pellicciotti, F., Raschle, T., Huerlimann, T., Carenzo, M., & Burlando, P. (2011). Transmission of solar radiation through clouds on melting glaciers: A comparison of parameterizations and their impact on melt modelling. Journal of Glaciology. Cambridge University Press. https://doi.org/10.3189/002214311796406013' chicago: 'Pellicciotti, Francesca, Thomas Raschle, Thomas Huerlimann, Marco Carenzo, and Paolo Burlando. “Transmission of Solar Radiation through Clouds on Melting Glaciers: A Comparison of Parameterizations and Their Impact on Melt Modelling.” Journal of Glaciology. Cambridge University Press, 2011. https://doi.org/10.3189/002214311796406013.' ieee: 'F. Pellicciotti, T. Raschle, T. Huerlimann, M. Carenzo, and P. Burlando, “Transmission of solar radiation through clouds on melting glaciers: A comparison of parameterizations and their impact on melt modelling,” Journal of Glaciology, vol. 57, no. 202. Cambridge University Press, pp. 367–381, 2011.' ista: 'Pellicciotti F, Raschle T, Huerlimann T, Carenzo M, Burlando P. 2011. Transmission of solar radiation through clouds on melting glaciers: A comparison of parameterizations and their impact on melt modelling. Journal of Glaciology. 57(202), 367–381.' mla: 'Pellicciotti, Francesca, et al. “Transmission of Solar Radiation through Clouds on Melting Glaciers: A Comparison of Parameterizations and Their Impact on Melt Modelling.” Journal of Glaciology, vol. 57, no. 202, Cambridge University Press, 2011, pp. 367–81, doi:10.3189/002214311796406013.' short: F. Pellicciotti, T. Raschle, T. Huerlimann, M. Carenzo, P. Burlando, Journal of Glaciology 57 (2011) 367–381. date_created: 2023-02-20T08:18:21Z date_published: 2011-03-01T00:00:00Z date_updated: 2023-02-20T09:47:00Z day: '01' doi: 10.3189/002214311796406013 extern: '1' intvolume: ' 57' issue: '202' language: - iso: eng main_file_link: - open_access: '1' url: https://doi.org/10.3189/002214311796406013 month: '03' oa: 1 oa_version: Published Version page: 367-381 publication: Journal of Glaciology publication_identifier: eissn: - 1727-5652 issn: - 0022-1430 publication_status: published publisher: Cambridge University Press quality_controlled: '1' scopus_import: '1' status: public title: 'Transmission of solar radiation through clouds on melting glaciers: A comparison of parameterizations and their impact on melt modelling' type: journal_article user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87 volume: 57 year: '2011' ... --- _id: '12650' abstract: - lang: eng text: Streamflow is a hydrological variable measured at a defined river cross-section; it spatially integrates the runoff generating processes in the contributing watershed, including precipitation and air temperature. Trends in streamflow are progressive changes in the time series of streamflow that can be detected with statistical methods and their statistical significance can be assessed. Mountainous regions are particularly vulnerable to streamflow change because of their high specific runoff and the sensitivity to the distribution of precipitation and air temperature, and the processes of snow accumulation and melt. alternative_title: - Encyclopedia of Earth Sciences Series article_processing_charge: No author: - first_name: Peter full_name: Molnar, Peter last_name: Molnar - first_name: Paolo full_name: Burlando, Paolo last_name: Burlando - first_name: Francesca full_name: Pellicciotti, Francesca id: b28f055a-81ea-11ed-b70c-a9fe7f7b0e70 last_name: Pellicciotti citation: ama: 'Molnar P, Burlando P, Pellicciotti F. Streamflow Trends in Mountainous Regions. In: Singh V, Singh P, Haritashya U, eds. Encyclopedia of Snow, Ice and Glaciers. 1st ed. Dordrecht: Springer Nature; 2011:1084-1089. doi:10.1007/978-90-481-2642-2_543' apa: 'Molnar, P., Burlando, P., & Pellicciotti, F. (2011). Streamflow Trends in Mountainous Regions. In V. Singh, P. Singh, & U. Haritashya (Eds.), Encyclopedia of Snow, Ice and Glaciers (1st ed., pp. 1084–1089). Dordrecht: Springer Nature. https://doi.org/10.1007/978-90-481-2642-2_543' chicago: 'Molnar, Peter, Paolo Burlando, and Francesca Pellicciotti. “Streamflow Trends in Mountainous Regions.” In Encyclopedia of Snow, Ice and Glaciers, edited by Vijay Singh, Pratap Singh, and Umesh Haritashya, 1st ed., 1084–89. Dordrecht: Springer Nature, 2011. https://doi.org/10.1007/978-90-481-2642-2_543.' ieee: 'P. Molnar, P. Burlando, and F. Pellicciotti, “Streamflow Trends in Mountainous Regions,” in Encyclopedia of Snow, Ice and Glaciers, 1st ed., V. Singh, P. Singh, and U. Haritashya, Eds. Dordrecht: Springer Nature, 2011, pp. 1084–1089.' ista: 'Molnar P, Burlando P, Pellicciotti F. 2011.Streamflow Trends in Mountainous Regions. In: Encyclopedia of Snow, Ice and Glaciers. Encyclopedia of Earth Sciences Series, , 1084–1089.' mla: Molnar, Peter, et al. “Streamflow Trends in Mountainous Regions.” Encyclopedia of Snow, Ice and Glaciers, edited by Vijay Singh et al., 1st ed., Springer Nature, 2011, pp. 1084–89, doi:10.1007/978-90-481-2642-2_543. short: P. Molnar, P. Burlando, F. Pellicciotti, in:, V. Singh, P. Singh, U. Haritashya (Eds.), Encyclopedia of Snow, Ice and Glaciers, 1st ed., Springer Nature, Dordrecht, 2011, pp. 1084–1089. date_created: 2023-02-20T08:18:07Z date_published: 2011-07-01T00:00:00Z date_updated: 2023-02-20T10:35:28Z day: '01' doi: 10.1007/978-90-481-2642-2_543 edition: '1' editor: - first_name: Vijay full_name: Singh, Vijay last_name: Singh - first_name: Pratap full_name: Singh, Pratap last_name: Singh - first_name: Umesh full_name: Haritashya, Umesh last_name: Haritashya extern: '1' language: - iso: eng month: '07' oa_version: None page: 1084-1089 place: Dordrecht publication: Encyclopedia of Snow, Ice and Glaciers publication_identifier: eisbn: - 978-90-481-2642-2 eissn: - 1871-756X isbn: - 978-90-481-2641-5 issn: - 1388-4360 publication_status: published publisher: Springer Nature quality_controlled: '1' scopus_import: '1' status: public title: Streamflow Trends in Mountainous Regions type: book_chapter user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87 year: '2011' ...