Romanian Academy

About: Romanian Academy is a archive organization based out in Bucharest, Romania. It is known for research contribution in the topics: Population & Nonlinear system. The organization has 3662 authors who have published 10491 publications receiving 146447 citations. The organization is also known as: Academia Română & Societatea Literară Română.

On Eigenfunction Decay for Two Dimensional¶Magnetic Schrödinger Operators

Abstract: For two dimensional Schrodinger operators with a nonzero constant magnetic field perturbed by a magnetic field and a scalar potential, both vanishing arbitrarily slow at infinity, it is proved that eigenfunctions corresponding to the discrete spectrum decay faster than any exponential. Under more restrictive conditions on the perturbations, even quicker decay is obtained.

A /spl gamma/-attenuation problem for discrete-time time-varying stochastic systems with multiplicative noise

Abstract: The aim of this paper is to develop an H/sub /spl infin//-type theory for discrete time time-varying systems with multiplicative noise. Based on a version of the bounded real lemma corresponding to this class of systems, necessary and sufficient conditions for the existence of a stabilizing deterministic controller ensuring an imposed level of attenuation are derived in terms of the solutions of two linear matrix inequalities (LMI) satisfying a complementary rank condition. Moreover, explicit formulae for such controller are obtained in the case when some additional conditions are assumed. As a particular case, we consider the same problem for discrete-time time-varying periodic systems with multiplicative noise, for which it is shown that a periodic /spl gamma/-attenuating controller may be computed as function of a certain extended LMI system.

Future land use/cover changes in Romania: regional simulations based on CLUE-S model and CORINE land cover database

Abstract: Since 1990, a series of fundamental political and socioeconomic transformations in Romania have led to important structural and functional changes in the land use/cover system. This paper aims to assess the past land use/cover dynamics during the period 1990–2006 and to simulate future changes (2007–2050) to identify the main land use/cover change processes and their potential environmental and land management implications. The simulation was carried out using the Conversion of Land Use and its Effects at Small regional extent (CLUE-S) model with the CORINE Land Cover (CLC) database and several biophysical and socioeconomic explanatory variables associated with the current land use/cover pattern. Using the receiver operating characteristic (ROC) method and cross-classification maps, statistical and spatial validation was assessed to evaluate the performance of the predicted data. The predicted map could represent a useful tool for monitoring and quantifying spatial and temporal land use/cover changes at national and particularly regional level, in order to adopt appropriate land use planning and environmental policy in line with sustainable development principles. In addition, the results could be used for further analyses to examine the consequences of land use/cover changes on landscape diversity and biodiversity, the interaction between land use/cover changes and natural hazards, or the implications for ecosystem services.