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.

Identification of an extended Bouc–Wen model with application to seismic protection through hysteretic devices

Abstract: In this paper is proposed an extended Bouc–Wen model for improving its capability to approximate experimental symmetric hysteretic loops. On the basis of the generalized equation there are defined integral and differential conditions that describe the essential geometric properties of a hysteretic curve. Next, a new method based on Genetic Algorithms is developed to identify the Bouc–Wen model parameters from experimental hysteretic loops obtained from periodic loading tests. The performance of presented approach is illustrated for two types of seismic protection devices with hysteretic characteristics: elastomeric base isolators and buckling restrained dissipative braces. The applicability of proposed method is highlighted by using the derived models to analyse by numerical simulation the efficiency of these devices for reducing seismic response of a three stories civil structure.

A spectrophotometric catalogue of HII galaxies

Abstract: We present a spectrophotometric catalogue of 90 emission-line galaxies (ELGs) discovered during an ob- jective - prism survey that aimed to search for dwarf galax- ies within the voids (Popescu et al. 1996, 1998). The paper presents line ratios, equivalent widths and absolute fluxes for the emission-lines seen in the spectra of the galaxies. A list of newly discovered Wolf-Rayet galaxies is presented. Many objects included in the catalogue have low metallic- ity and the extreme cases are proposed as candidates for very low metallicity galaxies.

Radial solutions for Neumann problems involving mean curvature operators in Euclidean and Minkowski spaces

Abstract: In this paper we study the existence of radial solutions for Neumann problems in a ball and in an annular domain, associated to mean curvature operators in Euclidean and Mmkowski spaces. Our approach relies on the Leray-Schauder degree together with some fixed point reformulations of our nonlinear Neumann boundary value problems (C) 2010 WILEY-VCH Verlag GmbH & Co KGaA, Weinheim

New Seismic and Tomography Data in the Southern Part of the Harghita Mountains (Romania, Southeastern Carpathians): Connection with Recent Volcanic Activity

Abstract: The southern part of the southeastern Carpathians represents the site of the most recent volcanic eruptions of the entire Carpathian-Pannonian region. The products of these eruptions range from 42 to 10 Ka radiocarbon ages in the South Harghita Mountains (high K calc-alkaline rocks with adakite-like features), and at 1.2–0.6 Ma K–Ar ages in the Persani Mountains (alkali basalts). They were emplaced in a post-collisional regime. Ciomadul volcano is located at the southernmost part of the NW–SE oriented Calimani-Gurghiu-Harghita range crossing the inner part of the southeastern Carpathians and in the rough proximity of the Vrancea seismic zone (at ca. 60 km toward NW). Its magma generation is attributed to geodynamic events closely related to the seismogenic area. A number of particular geophysical and geochemical features located in the study region, including (1) the abrupt attenuation of the seismic waves originating from the Vrancea intermediate-depth foci, (2) the most intense heat-flow anomaly in Romania, (3) the most prominent 3He/4He anomaly measured in natural “postvolcanic” gas emanations, are all in favor of the hypothesis of a still existing hot local magma chamber. Data acquired during recent seismic monitoring of the Vrancea zone and its neighborhoods suggest an enhancement of the local seismicity beneath the southern edge of the South Harghita Mts., both at crustal and subcrustal levels. At the same time, recent tomography images obtained using local earthquake data correlate well with the presence of a vertically extended low-velocity zone coming from the upper mantle to the assumed magmatic chambers located in the crust. The present data, supporting the presence of an active crustal magma chamber beneath Ciomadul, allow us to consider that future volcanic activity at this volcano cannot be discarded.

Biodiversity variability across elevations in the Carpathians: Parallel change with landscape openness and land use:

Abstract: An understanding of contemporary and likely future biodiversity requires knowledge of how past human societies have shaped diversity patterns. Here, we use long-term pollen data sets extending from lowlands to subalpine environment in the Carpathian region (Romania) with the aim of exploring the relationship between landscape openness, anthropogenic disturbance, elevation and vegetation richness over the Holocene. We found that landscape openness represents a significant driver of pollen richness: The more open sites from mid (440–750 m) and high elevations (1550–1850 m) showed on average greater diversity than more forested upland sites (1050–1360 m). For the first time, our results show pollen richness patterns along elevation gradients that remain constant over the Holocene. Although significant only over the last 3000 cal. yr BP, these elevational patterns become accentuated with stronger evidence of anthropogenic impact. We also found a strong link between diversity change and major land use strategi...