5 research outputs found
Uniform controllability for the beam equation with vanishing structural damping
No full textsummary:This paper is devoted to studying the effects of a vanishing structural damping on the controllability properties of the one dimensional linear beam equation. The vanishing term depends on a small parameter . We study the boundary controllability properties of this perturbed equation and the behavior of its boundary controls as goes to zero. It is shown that for any time sufficiently large but independent of and for each initial data in a suitable space there exists a uniformly bounded family of controls in acting on the extremity . Any weak limit of this family is a control for the beam equation. This analysis is based on Fourier expansion and explicit construction and evaluation of biorthogonal sequences. This method allows us to measure the magnitude of the control needed for each eigenfrequency and to show their uniform boundedness when the structural damping tends to zero
A Numerical Method for the Controls of the Heat Equation
No full textThis work is devoted to analyze a numerical scheme for the approximation of the linear heat equation’s controls. It is known that, due to the regularizing effect, the efficient computation of the null controls for parabolic type equations is a difficult problem. A possible cure for the bad numerical behavior of the approximating controls consists of adding a singular perturbation depending on a small parameter ε which transforms the heat equation into a wave equation. A space discretization of step h leads us to a system of ordinary differential equations. The aim of this paper is to show that there exists a sequence of exact controls of the corresponding perturbed semi-discrete systems which converges to a control of the original heat equation when both h (the mesh size) and ε (the perturbation parameter) tend to zero
A numerical method for the controls of the heat equation
No full textThis work is devoted to analyze a numerical scheme for the approximation of the linear heat equation\u27s controls. It is known that, due to the regularizing effect, the efficient computation of the null controls for parabolic type equations is a difficult problem. A possible cure for the bad numerical behavior of the approximating controls consists of adding a singular perturbation depending on a small parameter ε which transforms the heat equation into a wave equation. A space discretization of step h leads us to a system of ordinary differential equations. The aim of this paper is to show that there exists a sequence of exact controls of the corresponding perturbed semi-discrete systems which converges to a control of the original heat equation when both h (the mesh size) and ε (the perturbation parameter) tend to zero. © EDP Sciences, 2014
Presepsin, C reactive protein and procalcitonin have similar accuracy for bacterial infection and sepsis in decompensated cirrhosis
No full textCurrent status of the Dalmatian pelican and the great white pelican populations of the Black Sea/Mediterranean flyway
No full textThe Dalmatian pelican (DP) Pelecanus crispus and the great white pelican (GWP) Pelecanus onocrotalus are listed as 'Vulnerable' and 'Least Concern', respectively, in the IUCN Red List. We present an updated estimation of the Black Sea/Mediterranean flyway population status of both species, based on data provided by experts working in all 7 countries of the region where pelicans breed and/or overwinter, who came together at the 1st Workshop on Pelican Research and Conservation in Prespa, Greece. The DP breeding population in the Black Sea and Mediterranean countries increased from 1730-2105 pairs in the years 2000-2010 to 2154-2437 pairs in 2011-2012. Approximately 40% of the Palaearctic breeding population of GWP occurred in Southeast Europe and Turkey. In 2011-2012 the GWP population in this region was estimated to be 4702-5175 pairs, and has remained more or less stable during the last decade. Although all the breeding sites for both species are in protected areas, disturbance at nesting places was considered to be the main threat. Direct persecution and electric power lines still cause occasional problems. In deltaic lagoons, erosion and inundation of nesting sites cause breeding failures in DPs, while in inland wetlands large water level fluctuations are a widespread problem. Decrease of fish stocks is a threat, especially in coastal areas. Many stop-over wetlands along GWP migration routes between Southeast Europe and Africa have been seriously degraded or have disappeared, resulting in serious implications for their populations. Conservation needs are listed, but further research is recommended for both species.TUB TAK research projectTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [111T465]; ECEuropean Commission Joint Research CentreEuropean Community (EC) [LIFE05 NAT/RO/000169]; Swarovski Optik; Station Biologique de la Tour du Valat through the Foundation 'Le Balkan'; MAVA Foundation through the Society for the Protection of Prespa; Station Biologique de la Tour du Valat; Society for the Protection of Prespa; WWF GreeceTaej Mundkur, Nyambayar Batbayar, Piotr Cwiertnia, Andrej Vizi, Gennady Molodan, Simba Chan, Menxiu Tong, Zinovey Petrovych and Giannis Roussopoulos are thanked for providing unpublished information and/or for comments on an earlier draft. The Hellenic Ornithological Society provided International WaterBird Census data for both species in Greece. The work of M.S., O.O. and O.G. in Turkey was funded by a TUB TAK research project (No. 111T465). The conservation and monitoring activities in Romania between 2005 and 2009 were co-funded by the EC through the project LIFE05 NAT/RO/000169. The work in Srebarna was funded by Swarovski Optik and the Station Biologique de la Tour du Valat through the Foundation 'Le Balkan'. The work in Prespa, Am vrakikos and Kerkini in Greece was funded by the MAVA Foundation through the Society for the Protection of Prespa and the Station Biologique de la Tour du Valat, and G.C. was supported by the Society for the Protection of Prespa and WWF Greece. D. Tommy King, Dan Chamberlain, Hans Kallander and an anonymous re viewer made many useful suggestions that improved an earlier draft. Julia Henderson corrected our gross mistakes in the use of the English language
