3,993 research outputs found
Assessment of Energy Efficiency Measures in Food Cold Supply Chains: A Dairy Industry Case Study
The quality of human nutrition has acquired significant improvements thanks to the opportunity to store food in suitable temperature conditions. Refrigeration has allowed the slowing of chemical and biological degradation and hence the waste of foodstuff, but at the same time increases energy consumption. These effects impact the environment and the sustainability performance of the cold chain, and drive consumersâ choices. The stakeholders of the chain are, therefore, constantly looking for improvement actions to reduce environmental impacts. This paper aims to provide a methodology for prioritizing and assessing the energy efficiency measures for cold chains in terms of quality losses and specific energy consumption, distinguishing between technological, maintenance, and managerial opportunities. This analysis is based on the cold supply chain tool, developed under the H2020 project ICCEE (âImproving Cold Chain Energy Efficiencyâ) which focuses on a holistic approach, not looking only at the individual stages of the cold chain. Furthermore, an economic evaluation has been proposed considering cost savings and the investment needed
Manufacture and Test of the Prototype 5 T Superconducting Undulator for the LHC Synchrotron Radiation Profile Monitor
A superconducting undulator wound with Nb-Ti based conductor, will be used in the LHC as a key part of the synchrotron radiation profile monitor system. Two undulators are needed, one per each circulating beam, providing 5 T in a 60 mm bore over two periods of 280 mm each. A full scale prototype has been designed and successfully tested in the end of 2004. In this paper, the electromagnetic and the mechanical design of the undulator are summarized. The fabrication of the prototype is described and the successful cold test results, both power test and magnetic flux density measurements, are reported
A new catalogue of ISM content of normal galaxies
We have compiled a catalogue of the gas content for a sample of 1916
galaxies, considered to be a fair representation of `normality'. The definition
of 'normal' galaxy adopted in this work implies that we have purposely excluded
from the catalogue galaxies having distorted morphology (such as interaction
bridges, tails or lopsidedness) and/or any signature of peculiar kinematics
(such as polar rings, counterrotating disks or other decoupled components). In
contrast, we have included systems hosting active galactic nuclei (AGN) in the
catalogue. This catalogue revises previous compendia on the ISM content of
galaxies, and compiles data available in the literature from several small
samples of galaxies. Masses for warm dust, atomic and molecular gas, as well as
X-ray luminosities have been converted to a uniform distance scale taken from
the Catalogue of Principal Galaxies (PGC). We have used two different
normalization factors to explore the variation of the gas content along the
Hubble sequence: the blue luminosity and the square of linear diameter. Our
catalogue significantly improves the statistics of previous reference
catalogues and can be used in future studies to define a template ISM content
for 'normal' galaxies along the Hubble sequence. The catalogue can be accessed
on-line at http://dipastro.pd.astro.it/galletta/ismcat/Comment: 12 pages. 4 figures, 6 tables - A&A accepte
Diffuse Gas and LMXBs in the Chandra Observation of the S0 Galaxy NGC 1553
We have spatially and spectrally resolved the sources of X-ray emission from
the X-ray faint S0 galaxy NGC 1553 using an observation from the Chandra X-ray
Observatory. The majority (70%) of the emission in the 0.3 - 10.0 keV band is
diffuse, and the remaining 30% is resolved into 49 discrete sources. Most of
the discrete sources associated with the galaxy appear to be low mass X-ray
binaries (LMXBs). The luminosity function of the LMXB sources is well-fit by a
broken power-law with a break luminosity comparable to the Eddington luminosity
for a 1.4 solar mass neutron star. It is likely that those sources with
luminosities above the break are accreting black holes and those below are
mostly neutron stars in binary systems. Spectra were extracted for the total
emission, diffuse emission, and sum of the resolved sources; the spectral fits
for all require a model including both a soft and hard component. The diffuse
emission is predominately soft while the emission from the sources is mostly
hard. Approximately 24% of the diffuse emission arises from unresolved LMXBs,
with the remainder resulting from thermal emission from hot gas. There is a
very bright source at the projected position of the nucleus of the galaxy. The
spectrum and luminosity derived from this central source are consistent with it
being an AGN; the galaxy also is a weak radio source. Finally, the diffuse
emission exhibits significant substructure with an intriguing spiral feature
passing through the center of the galaxy. The X-ray spectrum and surface
brightness of the spiral feature are consistent with adiabatic or shock
compression of ambient gas, but not with cooling. This feature may be due to
compression of the hot interstellar gas by radio lobes or jets associated with
the AGN.Comment: 23 pages using emulateapj.sty; ApJ, in press; revised version
includes correction to error in the L_X,src/L_B ratio as well as other
revision
Scaling relations of cluster elliptical galaxies at z~1.3. Distinguishing luminosity and structural evolution
[Abridged] We studied the size-surface brightness and the size-mass relations
of a sample of 16 cluster elliptical galaxies in the mass range
10^{10}-2x10^{11} M_sun which were morphologically selected in the cluster RDCS
J0848+4453 at z=1.27. Our aim is to assess whether they have completed their
mass growth at their redshift or significant mass and/or size growth can or
must take place until z=0 in order to understand whether elliptical galaxies of
clusters follow the observed size evolution of passive galaxies. To compare our
data with the local universe we considered the Kormendy relation derived from
the early-type galaxies of a local Coma Cluster reference sample and the WINGS
survey sample. The comparison with the local Kormendy relation shows that the
luminosity evolution due to the aging of the stellar content already assembled
at z=1.27 brings them on the local relation. Moreover, this stellar content
places them on the size-mass relation of the local cluster ellipticals. These
results imply that for a given mass, the stellar mass at z~1.3 is distributed
within these ellipticals according to the same stellar mass profile of local
ellipticals. We find that a pure size evolution, even mild, is ruled out for
our galaxies since it would lead them away from both the Kormendy and the
size-mass relation. If an evolution of the effective radius takes place, this
must be compensated by an increase in the luminosity, hence of the stellar mass
of the galaxies, to keep them on the local relations. We show that to follow
the Kormendy relation, the stellar mass must increase as the effective radius.
However, this mass growth is not sufficient to keep the galaxies on the
size-mass relation for the same variation in effective radius. Thus, if we want
to preserve the Kormendy relation, we fail to satisfy the size-mass relation
and vice versa.Comment: Accepted for publication in A&A, updated to match final journal
versio
GASP XVIII: Star formation quenching due to AGN feedback in the central region of a jellyfish galaxy
We report evidence for star formation quenching in the central 8.6 kpc region
of the jellyfish galaxy JO201 which hosts an active galactic nucleus, while
undergoing strong ram pressure stripping. The ultraviolet imaging data of the
galaxy disk reveal a region with reduced flux around the center of the galaxy
and a horse shoe shaped region with enhanced flux in the outer disk. The
characterization of the ionization regions based on emission line diagnostic
diagrams shows that the region of reduced flux seen in the ultraviolet is
within the AGN-dominated area. The CO J map of the galaxy disk reveals
a cavity in the central region. The image of the galaxy disk at redder
wavelengths (9050-9250 \overset{\lower.5em\circ}{\mathrm{A}}) reveals the
presence of a stellar bar. The star formation rate map of the galaxy disk shows
that the star formation suppression in the cavity occurred in the last few
10 yr. We present several lines of evidence supporting the scenario that
suppression of star formation in the central region of the disk is most likely
due to the feedback from the AGN. The observations reported here make JO201 a
unique case of AGN feedback and environmental effects suppressing star
formation in a spiral galaxy.Comment: Author's accepted manuscrip
Chromatic confocal setup for displacement measurement using a supercontinuum light source
Chromatic confocal microscopy is a technique to measure distances by analyzing the spectrum of the light reflected by a sample. The key element of the confocal setup is a dispersive lens, which focuses
different wavelengths at different distances from the lens. In this paper,a novel setup realized with a
supercontinuum light source and a spatial filter composed by reflective elements is described.The supercontinuum source is implemented by injecting high power pulses from a microchip laser into a
Ge-doped microstructured optical fiber. The usage of metallic parabolic mirrors, for the focusing and
collimation required in the spatial filter, lets the dispersive lens be the only dispersive element of the
confocal setup and improves the efficiency of the spatial filter itself. A silicon-based spectrometer is
used for the acquisition of the spectra, which are normalized and Gaussian-fitted before extracting the
displacement information. A complete calibration is performed, and the set of wavelengths from
500 nm to 900 nm can be mapped into a280 um measuring range. The obtained relativ eaccuracy of
0.36% shows an enhancement of almost one order of magnitude when compared to other supercontinuum-based confocal systems
Achievements in CTF3 and Commissioning status
The aim of the latest CLIC test facility CTF3, built at CERN by an international collaboration, is to prove the main feasibility issues of the CLIC two-beam acceleration technology. Several of the main goals have been already achieved in the past years, like the full-loading linac operation mode and the delay loop principle. During 2008 also the combiner ring concept has been experimentally proven and the recombined beam has been used to generate the RF power. In parallel in the fall of the year also the probe beam line commissioning had started
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