1,748 research outputs found
Risk and Economic Growth
In the expectation of the EU integration, the improvement of the economic growth on medium term constitutes a national strategic objective. The achievement of a compatible economy regarding to the mechanism, structure and legislative with the EU countries economies allows for a multitude of actions and measures that must be realized, inclusive the evolution until certain levels of some synthetic economic indicators that characterizes economic growth. This paper presents the evolution of the economic growth indicators in period 1990 – 2004 as well as the evolution of the factors that contributes to economic growth.economic growth, risk, macroeconomic indicators, multi-criteria analysis
Unveiling the cause of hybrid morphology radio sources (HyMoRS)
19 pages, 4 figures, 6 tables. Accepted for publication in MNRASHybrid morphology radio sources (HyMoRS) are a rare group of radio galaxies in which differing Fanaroff & Riley morphologies (FR I/II) are observed for each of the two lobes. While they potentially provide insights into the formation of lobe structure, particle acceleration, and the FR dichotomy, previous work on HyMoRS has mainly been limited to low-resolution studies, searches for new candidates, and milliarcsecond-scale VLBI observations of the core region. In this paper, we use new multi-array configuration Very Large Array (VLA) observations between 1 and 8 GHz to determine the morphology of HyMoRS on arcsecond scales and perform the first well-resolved spectral study of these unusual sources. We find that while the apparent FR I lobe is centre-brightened, this is the result of a compact acceleration region resembling a hotspot with a spectrum more consistent with an FR II ("strong-flavour") jet. We find that the spectra of the apparent FR I lobes are not similar to their classical counterparts and are likely the result of line-of-sight mixing of plasma across a range of spectral ages. We consider possible mechanisms that could lead to the formation of HyMoRS under such conditions, including environment asymmetry and restarted sources, concluding through the use of simple modelling that HyMoRS are the result of orientation effects on intrinsically FR II sources with lobes non-parallel to the inner jet.Peer reviewedFinal Accepted Versio
A large narrow band H survey at : the bright end of the luminosity function, cosmic variance and clustering across cosmic time
We carried out the largest ( Mpc, 26 deg) H
narrow band survey to date at in the SA22, W2 and XMMLSS
extragalactic fields. Our survey covers a large enough volume to overcome
cosmic variance and to sample bright and rare H emitters up to an
observed luminosity of erg s, equivalent to yr. Using our sample of sources brighter than
erg s ( yr), we derive H
luminosity functions, which are well described by a Schechter function with
Mpc and
erg s (with a fixed faint end slope ). We find that
surveys probing smaller volumes ( Mpc) are heavily
affected by cosmic variance, which can lead to errors of over per cent in
the characteristic density and luminosity of the H luminosity function.
We derive a star formation rate density of yr, in agreement with the redshift-dependent
H parametrisation from Sobral et al. (2013). The two-point correlation
function is described by a single power law , corresponding to a clustering length of Mpc/h. We find that the most luminous H emitters at
are more strongly clustered than the relatively fainter ones. The
H emitters at in our sample reside in
dark matter haloes. This implies that the most
star forming galaxies always reside in relatively massive haloes or group-like
environments and that the typical host halo mass of star-forming galaxies is
independent of redshift if scaled by , as
proposed by Sobral et al. (2010).Comment: Accepted for publication in MNRAS; 18 pages, 19 figures, 6 table
COMPETITIVENESS THROUGH KNOWLEDGE – ASSESSMENT OF THE EUROPEAN UNION MEMBER STATES BASED ON THE KNOWLEDGE ASSESSMENT METHODOLOGY (KAM) DEVELOPED BY THE WORLD BANK
The present study attempts to make a diagnosis of the progress of European Union member states in the transition towards the knowledge economy. We used the World Bank KAM Methodology developed in the programme Knowledge for Development and the database available on the web page of the World Bank. KAM Methodology was described and the European progress towards the knowledge economy was assessed according to this methodology, with the focus on the Romanian situation, from a comparative perspective.knowledge economy; competitiveness through knowledge
Suggested Operation Grid-Connected Lithium-Ion Battery Energy Storage System for Primary Frequency Regulation:Lifetime Perspective
STUDIES ON FLUTTER PREDICTION
The purpose of this paper is to study the instability of the dynamic flutter. The justification is expressed by the fact that the occurrence of flutter within the aircraft’s flight envelope results in irreversible structural deformation which consequently leads to serious damage. Therefore the mathematical modeling of this phenomenon and its validation are very important. The instability of the dynamic flutter is characterized by critical speed and critical pulsation of oscillatory movements. In this paper, the quasi-stationary model and the Theodorsen model have been analyzed for calculating the aerodynamic forces and torques, and a comparison of them has been carried out. The fluid-structure coupling is done by rewriting the equations, considering that the forces are given by closed formulas. For the mathematical modeling of the flutter there have been used the p-k and V-g methods based on the Theodorsen model and the quasi-stationary model. In order to modeling the free vortices aerodynamic forces and moments, the equations which describe both the motion of the structure and the fluid flow had to be integrated simultaneously in time. The fluid-structure coupling is considered as a combination of two systems that describe the aeroelastic behavior of the structure
Neutral hydrogen gas, past and future star-formation in galaxies in and around the 'Sausage' merging galaxy cluster
CIZA J2242.8+5301 (, nicknamed 'Sausage') is an extremely massive
( ), merging cluster with shock waves
towards its outskirts, which was found to host numerous emission-line galaxies.
We performed extremely deep Westerbork Synthesis Radio Telescope HI
observations of the 'Sausage' cluster to investigate the effect of the merger
and the shocks on the gas reservoirs fuelling present and future star formation
(SF) in cluster members. By using spectral stacking, we find that the
emission-line galaxies in the 'Sausage' cluster have, on average, as much HI
gas as field galaxies (when accounting for the fact cluster galaxies are more
massive than the field galaxies), contrary to previous studies. Since the
cluster galaxies are more massive than the field spirals, they may have been
able to retain their gas during the cluster merger. The large HI reservoirs are
expected to be consumed within Gyr by the vigorous SF and AGN
activity and/or driven out by the out-flows we observe. We find that the
star-formation rate in a large fraction of H emission-line cluster
galaxies correlates well with the radio broad band emission, tracing supernova
remnant emission. This suggests that the cluster galaxies, all located in
post-shock regions, may have been undergoing sustained SFR for at least 100
Myr. This fully supports the interpretation proposed by Stroe et al. (2015) and
Sobral et al. (2015) that gas-rich cluster galaxies have been triggered to form
stars by the passage of the shock.Comment: Accepted to MNRAS, 14 pages, 9 figures, 7 table
Valve vs. solid-state microphone preamplifier: a comparative study
This paper outlines research carried out to determine the perceptual and objective differences between a solid-state and a valve preamplifier running at low voltages. ABX testing was employed and showed that there were perceivable differences between the two systems. A comprehensive objective analysis was performed, which utilised tests for total harmonic distortion + noise (THD+N), intermodulation distortion (IMD), THD versus frequency and frequency response in order to ensure the two systems were performing in their linear region. In addition, MIRToolbox was utilised to extract low-level features such as spectral centroid, skewness and novelty. The electronic measurements combined with the MIRToolbox support the listeners’ subjective descriptors that there is a difference in brightness and harmonic content between the two types of preamplifiers. A correlation theory was developed, which linked the objective and the subjective measurements
A stringent upper limit to 18cm radio emission from the extrasolar planet system tau Bootis
Context: It has been speculated for many years that some extrasolar planets
may emit strong cyclotron emission at low radio frequencies in the range 10-100
MHz. Despite several attempts no such emission has yet been seen.
Aims: The hot Jupiter system tau Bootis is one of the nearest (d=15 pc)
exoplanets known to date. The gravitational influence of this massive hot
Jupiter (M=6 M_jup) has locked the star-planet system, making the star rotate
in P~3.3 days, similar to the orbital period of the planet. From the well
established correlation between stellar rotation and radio luminosity, it is
conceivable that the tau Bootis system emits strong radio emission at
significantly higher frequencies than currently probed, which we aimed to
investigate with this work.
Methods: We observed tau Bootis with the Westerbork Synthesis Radio Telescope
(WSRT) at a frequency of 1.7 GHz. for 12 hours in spectral line mode, reaching
a noise level of 42 microJy/beam at the position of the target.
Results: No 18cm radio emission is detected from tau Bootis, resulting in a 3
sigma upper limit of 0.13 mJy, corresponding to a 18cm radio luminosity of
<3.7e13 erg/s/Hz. We observe tau Bootis to be two orders of magnitude fainter
than expected from the stellar relation between radio luminosity and rotation
velocity.
Conclusions: This implies that either the tau Bootis system is underluminous
in the radio compared to similar fast-rotating stars, or that we happened to
observe the target during a low state of radio emission.Comment: 4 pages, 1 figure: Accepted for publication in A&
Consumption For The Fulfillment Of Human Life
The present moment is characterized by the syntagm of „hiperconsumption society”, as we assist to an unprecedented augmentation of our desires to consume, associated with a fundamental change of values. The study analyzes, based on the vast scientific literature, the causes and the effects of this hypertrophy of consumption, based on the assumption of Oswald „Economic performance is not intrinsically interesting... Economic things matter only in so far as they make people happier.” Also, as a new paradigm on economic development is being outlined in the economic science, using „health of the living” as a fundamental value, understood as an ensemble of parameters that create the frame for what must be a normal and desired evolution, we analyzed the means that are available and can be used for the transition towards a healthy model of consumption. From the perspective of consumers’ protection, we consider that education for a healthy consumption is an appropriate answer that can generate a durable change of the present pattern towards a more generous consumption from an intergenerational point of view that can also sustain a high quality of life for the generations that coexists and succeed themselves.healthy consumption, consumer education, the right to education, underconsumption and hyperconsumption, paradox of happiness, imperatives of human life
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