2,808 research outputs found

    Accuracy of simulated data for bifacial systems with varying tilt angles and share of diffuse radiation

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    Potential investors in bifacial PV systems are still deterred by the uncertainty of energy yield predictions. Validation of the prediction methods and establishing an accuracy range is therefore a central prerequisite concerning the bankability of the bifacial technology. Because of the sensitivity on multiple additional factors compared to standard monofacial installations, the yield simulation of a bifacial PV array is far more complicated. The available simulation tools for bifacial systems still have to prove their reliability, also for predicting the effect of varying ambient and installation conditions. Moreover, bifacial devices enable new types of applications, such as vertical installations. In this work, we compare the results of simulation tools developed at ISC Konstanz and ECN.TNO, as well as the output of the commercial PVsyst simulation software, to measured data. The measured data is obtained by a test rig that carries out a continuous and automated variation of the tilt angle. The test rig is not a single stand-alone module but an array in order to include shading effects of real extended systems. In addition, the measurements focus on a central module, which represents the conditions of a typical device in an array. Days with differing light intensity and share of diffuse radiation were chosen to determine the impact of the insolation conditions on the simulation accuracy. General trends with regard to the sensitivity to tilt and insolation conditions are analyzed in order to evaluate the quality of state-of-the-art bifacial energy yield simulations

    A decision support system to improve performances of airport check-in services

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    The recent remarkable increase in air passenger traffic has been fostering a considerable congestion of the airport facilities. In this context, traditional procedures employed for check-in operations have been supported by alternative methods, based on the use of self-service options (kiosks, web services, app for mobile phones, etc). However, even if such innovations are contributing to improve the service level provided to passengers, field investigations suggest that traditional procedures will be employed also in the future, especially for medium and long-haul flights, where baggage dropping is required. For this reason, the passengers allocation problem at check-in counters is attracting growing attention by the scientific community and several decision support tools, involving both optimization and simulation methods, have been proposed. Most of the available approaches aim at deciding the optimal number of check-in counters to be activated, in such a way to balance the operative costs and passengers waiting times. Such approaches assume that the service capacity (in terms of available check-in operators and counters) is given and determined on the basis of physical constraints (related to the available space in the terminal) and of staff scheduling decisions made at a tactical level. The present contribution tries to overcome this limitation, by proposing a decision support system, based on a mathematical model, capable of designing optimal check-in policies by also incorporating staff scheduling decisions. The model is tested on some real-world case studies; computational results are evaluated, along with the practical usability of the approach

    Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV

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    The performance of muon reconstruction, identification, and triggering in CMS has been studied using 40 inverse picobarns of data collected in pp collisions at sqrt(s) = 7 TeV at the LHC in 2010. A few benchmark sets of selection criteria covering a wide range of physics analysis needs have been examined. For all considered selections, the efficiency to reconstruct and identify a muon with a transverse momentum pT larger than a few GeV is above 95% over the whole region of pseudorapidity covered by the CMS muon system, abs(eta) < 2.4, while the probability to misidentify a hadron as a muon is well below 1%. The efficiency to trigger on single muons with pT above a few GeV is higher than 90% over the full eta range, and typically substantially better. The overall momentum scale is measured to a precision of 0.2% with muons from Z decays. The transverse momentum resolution varies from 1% to 6% depending on pseudorapidity for muons with pT below 100 GeV and, using cosmic rays, it is shown to be better than 10% in the central region up to pT = 1 TeV. Observed distributions of all quantities are well reproduced by the Monte Carlo simulation.Comment: Replaced with published version. Added journal reference and DO

    Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV