Search results for "Operations"
showing 10 items of 1692 documents
Reconstruction of events recorded with the surface detector of the Pierre Auger Observatory
2020
Cosmic rays arriving at Earth collide with the upper parts of the atmosphere, thereby inducing extensive air showers. When secondary particles from the cascade arrive at the ground, they are measured by surface detector arrays. We describe the methods applied to the measurements of the surface detector of the Pierre Auger Observatory to reconstruct events with zenith angles less than 60 using the timing and signal information recorded using the water-Cherenkov detector stations. In addition, we assess the accuracy of these methods in reconstructing the arrival directions of the primary cosmic ray particles and the sizes of the induced showers.
Models and solution methods for the uncapacitatedr-allocationp-hub equitable center problem
2017
Hub networks are commonly used in telecommunications and logistics to connect origins to destinations in situations where a direct connection between each origin–destination (o-d) pair is impractical or too costly. Hubs serve as switching points to consolidate and route traffic in order to realize economies of scale. The main decisions associated with hub-network problems include (1) determining the number of hubs (p), (2) selecting the p-nodes in the network that will serve as hubs, (3) allocating non-hub nodes (terminals) to up to r-hubs, and (4) routing the pairwise o-d traffic. Typically, hub location problems include all four decisions while hub allocation problems assume that the valu…
On the hardness of evaluating criticality of activities in a planar network with duration intervals
2003
Complexity results for problems of evaluating the criticality of activities in planar networks with duration time intervals are presented. We show that the problems of asserting whether an activity is possibly critical, and of computing bounds on the float of an activity in these networks are NP-complete and NP-hard, respectively.
Persecution and Patronage: Oscar Buneman’s years in Britain
2016
The German student Oscar Bunemann, in trouble with the Nazi authorities in the mid-1930s, chose to emigrate to Britain and pursue a PhD there. After emigration, his surname appears as Buneman. On the verge of completing his degree in 1940, he was detained as an enemy alien and spent almost a year in internment. Upon release, he found work as an atomic scientist in England, and went on to lead a post-war career as a pioneering plasma physicist in the USA.We study forced migration of European scientists before and during the Second World War, and scientific patronage in the host countries. Buneman’s case is interesting from several points of view. Being a non-Jewish, non-communist, anti-Nazi …
A new indicator for higher education student performance
2014
The debate on academic achievement is a heated issue that involves all the higher education contexts. This paper attempts to provide an indicator that can make the measurement of university student performance easier and that can be easily applied to different systems, making comparisons more fair. The Italian University System is used as a starting point to make several considerations on the current measures and to build up a new performance indicator. Then, a generalization for other marking systems is shown and finally a quantile regression is performed to investigate some determinants of the new performance indicator, also with respect to the current one.
L’urbanité de l’héritage industriel La reconversion du viaduc de la High Line à New York
2015
At the heart of urban dynamics over the past few decades, the reconversion of riverside and port spaces in cities of the western world is associated with the deindustrialisation of these sites, often situated near historic city centres. This contemporary situation puts industrial heritage conversion at the centre of thinking which goes beyond the mere conservation of the original value of the buildings to question the future of cities, in relation to the notion of sustainability. In New York, after thirty years of neglect, the old railway viaduct known as the “High Line” has been transformed into an elevated, linear urban parkway. The project must be reframed within the Hudson Riverpark ope…
The Olt River pollution monitoring, using spatial analysis, analityc hierarchy process and technique for order preference by similarity methods
2016
Abstract Environmental pollution is one of the most serious problems of the contemporary world. Chemical industry is one of the major sources of environmental pollutants. Human knowledge and experience is currently focused on the use of assessment methods and techniques before and during the onset of such activities. For instance, it is common to consider the integration of multiple constraining factors and also, taking into account their high complexity and the application of one of the various techniques of Multi-Criteria Decision Making. The purpose of this study is to determine the location of the least and most polluted areas from several sampling points on the Olt River, in Romania. I…
Improving the prediction of air pollution peak episodes generated by urban transport networks
2016
Abstract This paper illustrates the early results of ongoing research developing novel methods to analyse and simulate the relationship between trasport-related air pollutant concentrations and easily accessible explanatory variables. The final scope is to integrate the new models in traditional traffic management support systems for a sustainable mobility of road vehicles in urban areas. This first stage concerns the relationship between the hourly mean concentration of nitrogen dioxide (NO2) and explanatory factors reflecting the NO2 mean level one hour back, along with traffic and weather conditions. Particular attention is given to the prediction of pollution peaks, defined as exceedanc…
A note on cooperative versus non-cooperative strategies in international pollution control
2002
Abstract In this note, we evaluate the scope of Dockner and Long’s [Journal of Environment Economics and Management 24 (1993) 13] conclusion on the efficiency of the non-cooperative outcome in a differential game of international pollution control. We also complete the study of the different equilibria the differential game can present. Our results show that their conclusion requires that the initial value of the stock of pollution be higher than the Pareto-efficient pollution stock so that the equilibrium path of emissions involves a decreasing stock of pollution. Our results also show that the application of the procedure proposed by Tsutsui and Mino [Journal of Economic Theory 52 (1990) …
Three Hours Ahead Prevision of SO2 Pollutant Concentration Using an Elman Neural based Forecaster
2008
Abstract Indoor air quality near the industrial site is tightly joined to pollutant concentration level, since outdoor pollution heavily influences air quality and, consequently, inhabitants health. A pollution management system is essential for health protection. Automatic air quality management systems have became an important research issue with strong implications for inhabitants’ health. In this paper an automatic forecaster based on neural networks for SO 2 concentration prevision is proposed. The analyzed area covers different small towns near the industrial site of Priolo, in the south of the world. Among these towns, Melilli was the first town in Italy that was evacuated for high l…