Polytechnic University of Catalonia

About: Polytechnic University of Catalonia is a education organization based out in Barcelona, Spain. It is known for research contribution in the topics: Finite element method & Population. The organization has 16006 authors who have published 45325 publications receiving 949306 citations. The organization is also known as: UPC - BarcelonaTECH & Technical University of Catalonia.

Tropospheric Ozone Assessment Report: Present-day distribution and trends of tropospheric ozone relevant to climate and global atmospheric chemistry model evaluation

Abstract: The Tropospheric Ozone Assessment Report (TOAR) is an activity of the International Global Atmospheric Chemistry Project. This paper is a component of the report, focusing on the present-day distribution and trends of tropospheric ozone relevant to climate and global atmospheric chemistry model evaluation. Utilizing the TOAR surface ozone database, several figures present the global distribution and trends of daytime average ozone at 2702 non-urban monitoring sites, highlighting the regions and seasons of the world with the greatest ozone levels. Similarly, ozonesonde and commercial aircraft observations reveal ozone’s distribution throughout the depth of the free troposphere. Long-term surface observations are limited in their global spatial coverage, but data from remote locations indicate that ozone in the 21st century is greater than during the 1970s and 1980s. While some remote sites and many sites in the heavily polluted regions of East Asia show ozone increases since 2000, many others show decreases and there is no clear global pattern for surface ozone changes since 2000. Two new satellite products provide detailed views of ozone in the lower troposphere across East Asia and Europe, revealing the full spatial extent of the spring and summer ozone enhancements across eastern China that cannot be assessed from limited surface observations. Sufficient data are now available (ozonesondes, satellite, aircraft) across the tropics from South America eastwards to the western Pacific Ocean, to indicate a likely tropospheric column ozone increase since the 1990s. The 2014–2016 mean tropospheric ozone burden (TOB) between 60˚N–60˚S from five satellite products is 300 Tg ± 4%. While this agreement is excellent, the products differ in their quantification of TOB trends and further work is required to reconcile the differences. Satellites can now estimate ozone’s global long-wave radiative effect, but evaluation is difficult due to limited in situ observations where the radiative effect is greatest.

A Globally Stable PD Controller for Bilateral Teleoperators

Abstract: In a recent scheme, with delayed derivative action [Lee and Spong, IEEE Trans. Robot., vol. 22, no. 2, pp. 269--281, Apr. 2006], it is claimed that a simple proportional derivative (PD) scheme yields a stable operation. Unfortunately, the stability proof hinges upon unverifiable assumptions on the human and contact environment operators, namely, that they define Linfin-stable maps from velocity to force. In this short paper, we prove that it is indeed possible to achieve stable behavior with simple PD-like schemes-even without the delayed derivative action-under the classical assumption of passivity of the terminal operators.

Kinetics of Biomass Pyrolysis: a Reformulated Three-Parallel-Reactions Model

Abstract: The thermal decompositions of sugarcane bagasse and waste-wood samples are studied using thermogravimetric analysis. Assuming the addition of three independent parallel decompositions, these corresponding to three pseudocomponents linked to the hemicellulose, cellulose, and lignin, the weight loss associated with the pyrolysis process is simulated. First, an irreversible first-order reaction model is assumed for each pseudocomponent. Results show that the model-simulated curves do not fit well to the experimental data. Consequently, a further kinetic study is carried out for the pure lignin (Kraft alkali lignin), which demonstrates that the pyrolysis of lignin is better described by a third-order reaction rate law. The reformulation of the lignin kinetic model, and its subsequent implementation in the summative model (for the third pseudocomponent), has allowed one to reach a good agreement between simulated and experimental data.

Constraints on the physics of type ia supernovae from the x-ray spectrum of the tycho supernova remnant

Abstract: In this paper we use high-quality X-ray observations from XMM-Newton and Chandra to gain new insights into the explosion that originated Tycho's supernova 433 yr ago We perform a detailed comparison between the ejecta emission from the spatially integrated X-ray spectrum of the supernova remnant and current models for Type Ia supernova explosions We use a grid of synthetic X-ray spectra based on hydrodynamic models of the evolution of the supernova remnant and nonequilibrium ionization calculations for the state of the shocked plasma We find that the fundamental properties of the X-ray emission in Tycho are well reproduced by a one-dimensional delayed detonation model with a kinetic energy of ~12 ? 1051 ergs All the other paradigms for Type Ia explosions that we have tested, including one-dimensional deflagrations, pulsating delayed detonations, and sub-Chandrasekhar explosions, as well as deflagration models calculated in three dimensions, fail to provide a good approximation of the observed ejecta emission Our results require that the supernova ejecta retain some degree of chemical stratification, with Fe peak elements interior to intermediate-mass elements This strongly suggests that a supersonic burning front (ie, a detonation) must be involved at some stage in the physics of Type Ia supernova explosions

Epidemics and immunization in scale‐free networks

Abstract: In this chapter we want to provide a review of the main results obtained in the modeling of epidemic spreading in scale-free networks. In particular, we want to show the different epidemiological framework originated by the lack of any epidemic threshold and how this feature is rooted in the extreme heterogeneity of the scale-free networks' connectivity pattern.