325 research outputs found
Transit service quality analysis using cluster analysis and decision trees: a step forward to personalized marketing in public transportation
[EN] A transit service quality study based on cluster analysis was performed to extract detailed customer profiles sharing similar appraisals concerning the service. This approach made it possible to detect specific requirements and needs regarding the quality of service and to personalize the marketing strategy. Data from various customer satisfaction surveys conducted by the Transport Consortium of Granada (Spain) were analyzed to distinguish these groups; a decision tree methodology was used to identify the most important service quality attributes influencing passengers overall evaluations. Cluster analysis identified four groups of passengers. Comparisons using decision trees among the overall sample of all users and the different groups of passengers identified by cluster analysis led to the discovery of differences in the key attributes encompassed by perceived quality.The authors also acknowledge the Granada Consorcio de Transportes for making the data set available for this study. Griselda Lopez wishes to express her acknowledgement to the regional ministry of Economy, Innovation and Science of the regional government of Andalusia (Spain) for their scholarship to train teachers and researchers in Deficit Areas. Rocio de Ona wishes to express her acknowledgement to the regional ministry of Economy, Innovation and Science of the regional government of Andalusia (Spain) for the Excellence Research Project denominated "Q-METROBUS-Quality of service indicator for METROpolitan public BUS transport services'', co-funded with Feder.De Oña, J.; De Oña, R.; LĂłpez-Maldonado, G. (2015). 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Support Syst. 35, 231â243 (2003)De Oña, J., de Oña, R., Calvo, F.J.: A classification tree approach to identify key factors of transit service quality. Expert Syst. Appl. 39, 11164â11171 (2012)De Oña, R., de Oña, J.: Analyzing transit service quality evolution using decision trees and gender segmentation. WIT Trans Built Environ 130, 611â621 (2013)De Oña, J., de Oña, R., Eboli, L., Mazzulla, G.: Perceived service quality in bus transit service: a structural equation approach. Transp. Policy 29, 219â226 (2013a)De Oña, J., LĂłpez, G., Mujalli, R.O., Calvo, F.J.: Analysis of traffic accidents on rural highways using Latent Class Clustering and Bayesian Networks. Accid. Anal. Prev. 51, 1â10 (2013b)De Oña, J., de Oña, R., Eboli, L., Mazzulla, G.: Heterogeneity in perceptions of service quality among groups of railway passengers. Int J Sustain Transp 9(8), 612â626 (2014a)De Oña, R., Eboli, L., Mazzulla, G.: Key factors affecting rail service quality. A decision tree approach. 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A proposal for cost-related and market-oriented train running charges
[EN] This paper examines some key aspects of a charging system for promoting railway transport, including charges reflecting a clear relationship with costs (transparency) and charges reflecting the quality of the infrastructure managerÂżs service. Train running charges recover track-related costs and can help to develop a charging system that meets these requirements. To orient train running charges to the market, a method for processing track maintenance and renewal costs is proposed whereby the quality of the service provided by an infrastructure is measured according to its utility to the railway undertaking. To achieve transparency, a single indicator is used for cost planning and the subsequent levying of costs on railway undertakings. The paper includes an example of how proposed train running charges would be calculated according to data from 14 European countries. The example shows that short-distance trains generate the lowest maintenance and renewal costs, followed by long-distance trains and freight trains.This work was supported by the Spanish Ministerio de Fomento [grant number PT-2007-056-05CCPP].Calvo, F.; De Oña, J.; De Oña, R.; LĂłpez-Maldonado, G.; Garach, L. (2014). A proposal for cost-related and market-oriented train running charges. Transportation Planning and Technology. 37(4):354-372. https://doi.org/10.1080/03081060.2014.897127S354372374Baumgartner, J. P. 2001. âPrices and Costs in the Railway Sector.â Laboratoire d'IntermodalitĂ© des Transports et de Planification. Ăcole Polytechnique FĂ©dĂ©rale de Lausanne. Accessed February 4. http://litep.epfl.châ2014Calvo, F., and J. de Oña. 2012a. âAn Approach to Mark-Ups through Capacity Charges.âProceedings of the ICE â Transport. Accessed February 4. http://www.icevirtuallibrary.com/content/article/10.1680/tran.11.00050.Calvo, F., & De Oña, J. (2012). Are rail charges connected to costs? Journal of Transport Geography, 22, 28-33. doi:10.1016/j.jtrangeo.2011.11.004Calvo, F., de Oña, J., LĂłpez, G., Garach, L., & de Oña, R. (2013). Rail track costs management for efficient railway charges. Proceedings of the Institution of Civil Engineers - Transport, 166(6), 325-335. doi:10.1680/tran.11.00001Calvo, F., de Oña, J., & Nash, A. (2007). Proposed Infrastructure Pricing Methodology for Mixed-Use Rail Networks. Transportation Research Record: Journal of the Transportation Research Board, 1995(1), 9-16. doi:10.3141/1995-02CENIT, TIS PT, IWW, and HERRY. 2007. âRailCalc. Calculation of Charges for the Use of Rail Infrastructure.â Prepared for the European Commission Directorate General for Energy and Transport. Accessed February 4. http://ec.europa.eu/transport/rail/legislation/doc/railcalc_discussion_paper_final.pdf.ECMT (European Conference of Ministers of Transport). 2005. âCharges for the Use of Infrastructure in ECMT Railways.â Draft final report. ECMT/CS/CF(2005)1/REV1. Accessed February 4. http://lnweb90.worldbank.org/ECA/Transport.nsf/ECADocByUnid/2CF8BE276F63A37D85256FB20043A05D?Opendocument.EPFL (Ecole Polytechnique FĂ©derale de Lausanne). 2003. âIMPROVERAIL: IMPROVEd Tools for RAILway Capacity and Access Management.â Accessed February 4. http://litep.epfl.ch.Network Rail. 2006. âUsage Costs â Assessment Methodology.â Draft for consultation. Accessed February 4. http://www.networkrail.co.uk/browse%20documents/regulatory%20documents/access%20charges%20reviews/consultations%20on%20future%20charging/variable%20track%20access%20charges/g-%20usage%20costs%20methodology%20sept%2006.pdf.Nyström, B., & Söderholm, P. (2010). Selection of maintenance actions using the analytic hierarchy process (AHP): decision-making in railway infrastructure. Structure and Infrastructure Engineering, 6(4), 467-479. doi:10.1080/15732470801990209ORR (Office of Rail Regulation). 2005. âRevision of Variable Usage and Electrification Asset Usage Charges: Final Report.â Accessed February 4. http://www.rail-reg.gov.uk/upload/pdf/bah_variable-usage-initial-report_jan05.pdf.Quinet, E. (2003). Short term adjustments in rail activity: the limited role of infrastructure charges. Transport Policy, 10(1), 73-79. doi:10.1016/s0967-070x(02)00047-1Thomas, J. 2002. âEU Task Force on Rail Infrastructure Charging: Summary Findings on Best Practice in Marginal Cost Pricing.â IMPRINT-EUROPE. Implementing Reform in Transport. Effective Use of Research on Pricing in Europe. A European Commission-funded Thematic Network (2001â2004). Accessed February 4. www.imprint-eu.org/public/Presentations/imprint3_Thomas.ppt.UIC (International Union of Railways). 2008. âLasting Infrastructure Cost Benchmarking (LICB).â Summary Report. Accessed February 4. http://www.uic.org/spip.php?article582
Detection of very-high-energy gamma-ray emission from the vicinity of PSR B1706-44 with H.E.S.S
The energetic pulsar PSR B1706-44 and the adjacent supernova remnant (SNR)
candidate G 343.1-2.3 were observed by H.E.S.S. during a dedicated
observational campaign in 2007. A new source of very-high-energy (VHE; E > 100
GeV) gamma-ray emission, HESS J1708-443, was discovered with its centroid at
RA(J2000) = 17h08m10s and Dec(J2000) = -44d21', with a statistical error of 3
arcmin on each axis. The VHE gamma-ray source is significantly more extended
than the H.E.S.S. point-spread function, with an intrinsic Gaussian width of
0.29 +/- 0.04 deg. Its energy spectrum can be described by a power law with a
photon index Gamma = 2.0 +/- 0.1 (stat) +/- 0.2 (sys). The integral flux
measured between 1-10 TeV is ~17% of the Crab Nebula flux in the same energy
range. The possible associations with PSR B1706-44 and SNR G343.1-2.3 are
discussed.Comment: 4+ pages, 2 figures; v1 submitted to ICRC Proceedings on 15 May 2009;
v2 has additional references and minor change
Gamma rays from microquasars Cygnus X-1 and Cygnus X-3
Gamma-ray observations of microquasars at high and very-high energies can
provide valuable information of the acceleration processes inside the jets, the
jet-environment interaction and the disk-jet coupling. Two high-mass
microquasars have been deeply studied to shed light on these aspects: Cygnus
X-1 and Cygnus X-3. Both systems display the canonical hard and soft X-ray
spectral states of black hole transients, where the radiation is dominated by
non-thermal emission from the corona and jets and by thermal emission from the
disk, respectively. Here, we report on the detection of Cygnus X-1 above 60 MeV
using 7.5 yr of Pass8 Fermi-LAT data, correlated with the hard X-ray state. A
hint of orbital flux modulation was also found, as the source is only detected
in phases around the compact object superior conjunction. We conclude that the
high-energy gamma-ray emission from Cygnus X-1 is most likely associated with
jets and its detection allow us to constrain the production site. Moreover, we
include in the discussion the final results of a MAGIC long-term campaign on
Cygnus X-1 that reaches almost 100 hr of observations at different X-ray
states. On the other hand, during summer 2016, Cygnus X-3 underwent a flaring
activity period in radio and high-energy gamma rays, similar to the one that
led to its detection in the high-energy regime in 2009. MAGIC performed
comprehensive follow-up observations for a total of about 70 hr. We discuss our
results in a multi-wavelength context.Comment: Proceedings of the 35th International Cosmic Ray Conference (ICRC
2017), Bexco, Busan, Korea (arXiv:1708.05153
Comparative study of Ag nanoparticles incorporation in TiO2 coatings by doping and impregnation techniques
En el presente estudio se incorporan nanopartĂculas de Ag sintetizadas mediante un proceso coloidal a recubrimientos de SiO2 y TiO2 mediante el dopado de los precursores sol-gel. En otra tĂ©cnica, los recubrimientos de SiO2 y TiO2 se impregnaron con iones Ag+ para luego producir la foto-reducciĂłn. La caracterizaciĂłn de las nanopartĂculas de Ag se hizo por microscopĂa electrĂłnica de transmisiĂłn (TEM), difracciĂłn de rayos X con haz rasante (GXRD) y espectroscopia UV-Visible antes y despuĂ©s de incorporarse a los distintos soles, observando que el estado de oxidaciĂłn depende del entorno. TambiĂ©n se estudiaron recubrimientos con estructura jerarquizada mediante la combinaciĂłn de las distintas composiciones y se los analizĂł por TEM, GXRD y degradaciĂłn fotocatalĂtica de naranja de metilo. Se observĂł una intensa actividad fotocatalĂtica bajo iluminaciĂłn UV. El factor clave en la eficiencia fotocatalĂtica de los sistemas de recubrimientos multicapas reside en el estado metĂĄlico de las nanopartĂculas de Ag que pueden reducir la recombinaciĂłn de los electrones y agujeros foto-generados los cuales incrementan la eficiencia en la transferencia de portadores de carga. La mejor eficiencia fue obtenida para los sistemas SiO2/Ag-TiO2 denso y mesoporoso impregnados y Ag-SiO2/TiO2 mesoporoso dopado.con un porcentaje de degradaciĂłn 36% mayor que la referencia de los sistemas no dopados. Finalmente se realizaron ensayos bactericidas, revelando una potente actividad bactericida en el caso de las tres cepas estudiadas, notablemente aumentada para todas las muestras dopadas con Ag.In the present study, Ag NPs have been synthesized by colloidal process and incorporated into SiO2 and TiO2 coatings by doping of sol-gel precursors. In other technique, SiO2 and TiO2 films were impregned by Ag+ ions and then they were photoreduced. Ag nanoparticles characterization was carried out through Transmission Electron Microscopy (TEM), Grazing X-ray diffraction (GXRD) and UV- visible spectroscopy before and after being combined with the different sols, observing that the oxidation state of Ag NPs depends on the environment. Coatings doped with Ag nanoparticles were also prepared with hierarchical structures built by combining the different composition and analysed by TEM, GXRD and photocatalytic degradation of methyl orange. High photocatalytic efficiency was observed under UV illumination. The key factor in the photocatalytic efficiency of the multilayer coating systems resides in the metallic state of Ag NPs that could reduce the recombination of photo-generated electrons and holes thus increasing the transfer efficiency of the charge carriers. The best efficiency was obtained for SiO2/Ag-TiO2 dense and mesoporous impregnated and Ag-SiO2/TiO2 mesoporous system with a percentage of degradation 36 % higher than the reference of non-doped systems. Finally, bactericide assays were performed, showing a strong bactericide activity over the three strains tested, remarkably increased for all the samples doped with Ag.Fil: Roldan, Maria Virginia. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Rosario. Instituto de FĂsica de Rosario (i); ArgentinaFil: de Oña, P.. Universidad Nacional de Rosario. Facultad de Ciencias BioquĂmicas y FarmacĂ©uticas; ArgentinaFil: Castro, Y.. Instituto de Ceramica y Vidrio de Madrid; EspañaFil: Grau, R.. Universidad Nacional de Rosario. Facultad de Ciencias BioquĂmicas y FarmacĂ©uticas; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; ArgentinaFil: DurĂĄn, A.. Instituto de Ceramica y Vidrio de Madrid; EspañaFil: Pellegri, Nora Susana. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Rosario. Instituto de FĂsica de Rosario (i); Argentin
Prospects for Observations of Pulsars and Pulsar Wind Nebulae with CTA
The last few years have seen a revolution in very-high gamma-ray astronomy
(VHE; E>100 GeV) driven largely by a new generation of Cherenkov telescopes
(namely the H.E.S.S. telescope array, the MAGIC and MAGIC-II large telescopes
and the VERITAS telescope array). The Cherenkov Telescope Array (CTA) project
foresees a factor of 5 to 10 improvement in sensitivity above 0.1 TeV,
extending the accessible energy range to higher energies up to 100 TeV, in the
Galactic cut-off regime, and down to a few tens GeV, covering the VHE photon
spectrum with good energy and angular resolution. As a result of the fast
development of the VHE field, the number of pulsar wind nebulae (PWNe) detected
has increased from one PWN in the early '90s to more than two dozen firm
candidates today. Also, the low energy threshold achieved and good sensitivity
at TeV energies has resulted in the detection of pulsed emission from the Crab
Pulsar (or its close environment) opening new and exiting expectations about
the pulsed spectra of the high energy pulsars powering PWNe. Here we discuss
the physics goals we aim to achieve with CTA on pulsar and PWNe physics
evaluating the response of the instrument for different configurations.Comment: accepted for publication in Astroparticle Physic
Air quality in Enclosed Railway Stations: quantifying the impact of diesel trains through deployment of multi-site measurement and random forest modelling
Progress in Monte Carlo design and optimization of the Cherenkov Telescope Array
The Cherenkov Telescope Array (CTA) will be an instrument covering a wide
energy range in very-high-energy (VHE) gamma rays. CTA will include several
types of telescopes, in order to optimize the performance over the whole energy
range. Both large-scale Monte Carlo (MC) simulations of CTA super-sets
(including many different possible CTA layouts as sub-sets) and smaller-scale
simulations dedicated to individual aspects were carried out and are on-going.
We summarize results of the prior round of large-scale simulations, show where
the design has now evolved beyond the conservative assumptions of the prior
round and present first results from the on-going new round of MC simulations.Comment: 4 pages, 5 figures. In Proceedings of the 33rd International Cosmic
Ray Conference (ICRC2013), Rio de Janeiro (Brazil). All CTA contributions at
arXiv:1307.223
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