2,581 research outputs found
Modification of surface energy in nuclear multifragmentation
Within the statistical multifragmentation model we study modifications of the
surface and symmetry energy of primary fragments in the freeze-out volume. The
ALADIN experimental data on multifragmentation obtained in reactions induced by
high-energy projectiles with different neutron richness are analyzed. We have
extracted the isospin dependence of the surface energy coefficient at different
degrees of fragmentation. We conclude that the surface energy of hot fragments
produced in multifragmentation reactions differs from the values extracted for
isolated nuclei at low excitation. At high fragment multiplicity, it becomes
nearly independent of the neutron content of the fragments.Comment: 11 pages with 13 figure
The GREGOR Fabry-P\'erot Interferometer
The GREGOR Fabry-P\'erot Interferometer (GFPI) is one of three first-light
instruments of the German 1.5-meter GREGOR solar telescope at the Observatorio
del Teide, Tenerife, Spain. The GFPI uses two tunable etalons in collimated
mounting. Thanks to its large-format, high-cadence CCD detectors with
sophisticated computer hard- and software it is capable of scanning spectral
lines with a cadence that is sufficient to capture the dynamic evolution of the
solar atmosphere. The field-of-view (FOV) of 50" x 38" is well suited for quiet
Sun and sunspot observations. However, in the vector spectropolarimetric mode
the FOV reduces to 25" x 38". The spectral coverage in the spectroscopic mode
extends from 530-860 nm with a theoretical spectral resolution R of about
250,000, whereas in the vector spectropolarimetric mode the wavelength range is
at present limited to 580-660 nm. The combination of fast narrow-band imaging
and post-factum image restoration has the potential for discovery science
concerning the dynamic Sun and its magnetic field at spatial scales down to
about 50 km on the solar surface.Comment: 14 pages, 17 figures, 4 tables; pre-print of AN 333, p.880-893, 2012
(AN special issue to GREGOR
Soil conservation and sustainable development goals(SDGs) achievement in Europe and central Asia: Which role for the European soil partnership?
Voluntary soil protection measures are not sufficient to achieve sustainable soil management at a global scale. Additionally, binding soil protection legislation at national and international levels has also proved to be insufficient for the effective protection of this almost non-renewable natural resource. The European Soil Partnership (ESP) and its sub-regional partnerships (Eurasian Sub-Regional Soil Partnership, Alpine Soil Partnership) were established in the context of FAO's Global Soil Partnership (GSP) with the mission to facilitate and contribute to the exchange of knowledge and technologies related to soils, to develop dialogue and to raise awareness for the need to establish a binding global agreement for sustainable soil management. The ESP has taken a role of an umbrella network covering countries in Europe and Central Asia. It aims to improve the dialogue in the whole region and has encouraged establishing goals that would promote sustainable soil management, taking into account various national and local approaches and priorities, as well as cultural specificities. The ESP first regional implementation plan for the 2017–2020 period was adopted and implemented along the five GSP pillars of action. Building on the experience of the last four years, this study demonstrates that establishing sub-regional and national partnerships is an additional step in a concrete sustainable soil management implementation process. It also suggests that a complementary approach between legal instruments and voluntary initiatives linked to the development of efficient communication and strong commitment is the key to success
Testing stock market convergence: a non-linear factor approach
This paper applies the Phillips and Sul (Econometrica 75(6):1771–1855, 2007) method to test for convergence in stock returns to an extensive dataset including monthly stock price indices for five EU countries (Germany, France, the Netherlands, Ireland and the UK) as well as the US between 1973 and 2008. We carry out the analysis on both sectors and individual industries within sectors. As a first step, we use the Stock and Watson (J Am Stat Assoc 93(441):349–358, 1998) procedure to filter the data in order to extract the long-run component of the series; then, following Phillips and Sul (Econometrica 75(6):1771–1855, 2007), we estimate the relative transition parameters. In the case of sectoral indices we find convergence in the middle of the sample period, followed by divergence, and detect four (two large and two small) clusters. The analysis at a disaggregate, industry level again points to convergence in the middle of the sample, and subsequent divergence, but a much larger number of clusters is now found. Splitting the cross-section into two subgroups including euro area countries, the UK and the US respectively, provides evidence of a global convergence/divergence process not obviously influenced by EU policies
High resolution TCSPC imaging of diffuse light with a one-dimensional SPAD array scanning system
Metoda za raspodjelu pogonske sile električnih vozila sa četiri kotača na kratkotrajno ili polovično skliskim cestama
In this paper, a four-wheel driving force distribution method based on driving force control is proposed. Driving force control is an anti-slip control method, previously proposed by the authors’ research group, which generates appropriate driving force based on the acceleration pedal. However, this control method cannot completely prevent reduction of driving force when a vehicle runs on an extremely slippery road. If the length of a slippery surface is shorter than the vehicle’s wheel base, the total driving force is retained by distributing the shortage of driving force to the wheels that still have traction. On the other hand, when either the left or right side runs on a slippery surface, yaw-moment is suppressed by setting total driving forces of left and right wheels to be the same. Therefore, four-wheel driving force distribution method is proposed for retaining driving force on instantaneous slippery roads, and suppressing yaw-moment on split ones. The effectiveness of the proposed distribution method is verified by simulations and experiments.U ovom radu predložena je metoda za raspodjelu pogonske sile električnih vozila sa četiri kotača temeljena na upravljanju pogonskom silom. Upravljanje pogonskom silom je metoda upravljanja koju je ranije predložila autorova istraživačka grupa, a koristi se za sprječavanje proklizavanja. Ova metoda generira prikladnu pogonsku silu temeljem pritiska na papučicu ubrzanja. Ipak, ova metoda upravljanja ne može u potpunosti spriječiti smanjenje pogonske sile kada vozilo nai.e na ekstremno sklisku cestu. Ako je dužina skliske površine kraća od me.uosovinskog razmaka vozila, ukupna pogonska sila se zadržava redistribucijom manjka pogonske sile na kotače koji i dalje imaju trakciju. S druge strane, kada lijeva ili desna strana vozila nai.e na sklisku površinu, moment zakretanja se potiskuje postavljanjem ukupne pogonske sile lijevih i desnih kotača na jednaki iznos. Dakle, metoda za raspodjelu pogonske sile predložena je za zadržavanje pogonske sile na kratkotrajno skliskim cestama, te za sprječavanje momenta zakretanja na polovično skliskim cestama. Učinkovitost predložene metode verificirana je simulacijski i eksperimentalno
Dispersive properties of quasi-phase-matched optical parametric amplifiers
The dispersive properties of non-degenerate optical parametric amplification
in quasi-phase-matched (QPM) nonlinear quadratic crystals with an arbitrary
grating profile are theoretically investigated in the no-pump-depletion limit.
The spectral group delay curve of the amplifier is shown to be univocally
determined by its spectral power gain curve through a Hilbert transform. Such a
constraint has important implications on the propagation of spectrally-narrow
optical pulses through the amplifier. In particular, it is shown that anomalous
transit times, corresponding to superluminal or even negative group velocities,
are possible near local minima of the spectral gain curve. A possible
experimental observation of such effects using a QPM Lithium-Niobate crystal is
suggested.Comment: submitted for publicatio
Photonic realization of the relativistic Kronig-Penney model and relativistic Tamm surface states
Photonic analogues of the relativistic Kronig-Penney model and of
relativistic surface Tamm states are proposed for light propagation in fibre
Bragg gratings (FBGs) with phase defects. A periodic sequence of phase slips in
the FBG realizes the relativistic Kronig-Penney model, the band structure of
which being mapped into the spectral response of the FBG. For the semi-infinite
FBG Tamm surface states can appear and can be visualized as narrow resonance
peaks in the transmission spectrum of the grating
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