1,641 research outputs found
Matrix completion and extrapolation via kernel regression
Matrix completion and extrapolation (MCEX) are dealt with here over
reproducing kernel Hilbert spaces (RKHSs) in order to account for prior
information present in the available data. Aiming at a faster and
low-complexity solver, the task is formulated as a kernel ridge regression. The
resultant MCEX algorithm can also afford online implementation, while the class
of kernel functions also encompasses several existing approaches to MC with
prior information. Numerical tests on synthetic and real datasets show that the
novel approach performs faster than widespread methods such as alternating
least squares (ALS) or stochastic gradient descent (SGD), and that the recovery
error is reduced, especially when dealing with noisy data
Non-perturbative renormalization of lattice operators in coordinate space
We present the first numerical implementation of a non-perturbative
renormalization method for lattice operators, based on the study of correlation
functions in coordinate space at short Euclidean distance. The method is
applied to compute the renormalization constants of bilinear quark operators
for the non-perturbative O(a)-improved Wilson action in the quenched
approximation. The matching with perturbative schemes, such as MS-bar, is
computed at the next-to-leading order in continuum perturbation theory. A
feasibility study of this technique with Neuberger fermions is also presented.Comment: 11 pages and 9 figures, LaTeX2
Effect of hydrogen addition on the OH* and CH* chemiluminescence emissions of premixed combustion of methane-air mixtures
[EN] Chemiluminescence emissions measurements of OH* and CH* are used to characterize the combustion of blends of methane and hydrogen in air in a constant volume combustion bomb, with two sets of initial conditions. The combined results of combustion development cover from 0.1 to 2.5 MPa. Burning velocity, heat release and unburned/burned gas temperatures are obtained from the pressure by using a two-zone thermodynamic combustion diagnostic model. Intensity of OH* and CH* increases with the initial temperature and the percentage of hydrogen, in parallel with the usual increase in burning velocity. The timings of the peaks of OH* and CH* chemiluminescence emissions are found to correlate respectively with the maximum rate of heat release and flame temperature. These results show that both chemiluminescence signals can be used to monitorize the burning process in combustion devices operating in the pressure range studied.Reyes, M.; Tinaut, F.; Giménez, B.; Pastor, JV. (2018). Effect of hydrogen addition on the OH* and CH* chemiluminescence emissions of premixed combustion of methane-air mixtures. International Journal of Hydrogen Energy. 43(42):19778-19791. https://doi.org/10.1016/j.ijhydene.2018.09.005S1977819791434
Asparagus : fibrousness during storage
Espárragos verdes cv. UC-157 F2, seleccionados
y clasificados, se preenfriaron
por inmersión en agua a 0 °C y 200 ppm de
cloro activo, inmediatamente después de su
cosecha. Luego, se los conservó con distintas
modalidades:
• Testigo (0 - 2 °C y 95 % HR).
• Atmósfera modificada (0 - 2 °C y 95 -
100 % HR), cubriendo cada atado con
película autoadherente de PVC.
• Atmósfera controlada (0 °C, 90 % HR,
2 % CO2 y 5,5 % O2).
Durante la conservación se extrajeron
periódicamente muestras para controlar la
evolución de la fibrosidad, utilizando
presiómetro con cuchilla adaptada de acero
inoxidable (0,43 mm de espesor). Para la
determinación se realizó el cizallamiento del
turión a intervalos de 2 cm desde la punta,
registrando los kgf requeridos. El estudio
realizado demostró que para evaluar la evolución
de fibrosidad de los turiones durante la conservación basta una sola medición, a
distancia prefijada entre los 6 - 16 cm desde
la punta. La conservación en atmósfera modificada
es la más conveniente ya que tanto
las selecciones L como XL mantuvieron
mejor dureza.It was worked with green asparagus cv.
UC-157 F2; after harvest they were sorted
and classified, inmediately they were
precooled by inmersion in cold water to 0 ºC
with 200 ppm of active chlorine; then they
were conditioned in different storage
modalities:
• Test (0 - 2 °C and 95 % RH).
• Modified atmosphere (0 - 2 °C and 95 -
100 % RH) using PVC film.
• Controlled atmosphere (0 °C, 90 % RH,
2 % CO2 and 5,5 % O2).
During the storage it was taken samples
periodically and controlled the evolution of
the fibrousness, using a penetrometer
adapted with stainless steel knife (0,43 mm
of thickness). For the determination it was
done the shearing of the stalk each 2 cm from
the top and registered the kgf required. With
this study it concludes that, for evaluate the
fibrousness evolution of the stalks during
storage, is enough to do only one measuring to a predetermine distance between 6 and
16 cm from the top. It is demonstrated, too,
the convenience of modified atmosphere
modality storage where both selections L and
XL maintain a better firmness degree.Fil: Giménez, Adriana B..
Universidad Nacional de Cuyo. Facultad de Ciencias AgrariasFil: Bauzá, Mónica.
Universidad Nacional de Cuyo. Facultad de Ciencias AgrariasFil: Roby, Héctor R. .
Universidad Nacional de Cuyo. Facultad de Ciencias AgrariasFil: Llera, Joaquín.
Universidad Nacional de Cuyo. Facultad de Ciencias Agraria
Non perturbative renormalization in coordinate space
We present an exploratory study of a gauge-invariant non-perturbative
renormalization technique. The renormalization conditions are imposed on
correlation functions of composite operators in coordinate space on the
lattice. Numerical results for bilinears obtained with overlap and
O(a)-improved Wilson fermions are presented. The measurement of the quark
condensate is also discussed.Comment: Lattice2003(improve), 3 page
Four-colour photometry of eclipsing binaries. XL, uvby light curves for the B-type systems DW Carinae, BF Centauri, AC Velorum, and NSV 5783
Aims. In order to increase the limited number of B-stars with accurately known dimensions, and also the number of well studied eclipsing binaries in open clusters, we have undertaken observations and studies of four southern double-lined eclipsing B-type binaries; DWCar, BF Cen, ACVel, and NSV 5783.
Methods. Complete uvby light curves were observed between January 1982 and April 1991 at the Danish 0.5 m telescope at ESO La Silla, since 1985 known as the Strömgren Automatic Telescope (SAT). Standard indices for the systems and the comparison stars,as well as additional minima observations for ACVel, have been obtained later at SAT. For DWCar and ACVel, high-resolution spectra for definitive spectroscopic orbits have also been obtained; they are presented as part of the detailed analyses of these systems.
A few spectra of NSV 5783 are included in the present paper.
Results. For all four systems, the first modern accurate light curves have been established. DWCar is a detached system consisting of two nearly identical components. It is member of the young open cluster Cr228. A detailed analysis, based on the new light curves and 29 high-resolution spectra, is published separately. BFCen is semidetached and is member of NGC 3766. Modern spectra are
needed for a detailed study. ACVel is a detached system with at least one more star. A full analysis, based on the new light curves and 18 high-resolution spectra, is published separately. NSV 5783 is discovered to be an eclipsing binary consisting of two well-detached
components in an 11-day period eccentric (e = 0.18) orbit. Secondary eclipse is practically total. From the light curves and a few high-resolution spectra, accurate photometric elements and preliminary absolute dimensions have been determined. The quite similar components have masses of about 5 M and radii of about 3.5 R, and they seem to have evolved just slightly off the ZAMS. The
measured rotational velocities (≈150 km s−1) are about 6 times those corresponding to pseudosynchronization
Generalization error bounds for kernel matrix completion and extrapolation
© 2020 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.Prior information can be incorporated in matrix completion to improve estimation accuracy and extrapolate the missing entries. Reproducing kernel Hilbert spaces provide tools to leverage the said prior information, and derive more reliable algorithms. This paper analyzes the generalization error of such approaches, and presents numerical tests confirming the theoretical resultsThis work is supported by ERDF funds (TEC2013-41315-R and TEC2016-75067-C4-2), the Catalan Government (2017 SGR 578), and NSF grants(1500713, 1514056, 1711471 and 1509040).Peer ReviewedPostprint (published version
Influence of Production Strategy on Gross Waste Output and Temporal Pattern of Gilthead Seabream (Sparus Aurata) Farming: Implications for Environmental Management
This study compares the farm management model used in the Mediterranean gilthead seabream
(GHSB; Sparus aurata) industry (S1)—stepped entry of juveniles throughout the year with several
production cycles and fish ages overlapping in a single farm—with that used in the salmon industry
(S2)—the whole is farm filled with fish that are the same age at once with a fallowing period between
rearing cycles—in terms of waste production by coupling digestibility coefficients with growth,
feeding, and eating behavior models into a mass balance model. We considered the total C, N, and P
content in the different waste fractions (particulate and dissolved wastes). The model, which simulated
real farming conditions, showed relevant quantitative and qualitative differences between both strategies,
with stocked biomass and water temperature as the main drivers, the amount of feed wasted by
chewing as the most relevant fraction differentiating both strategies, and the fallowing period as the
main distinguishing management feature. We discuss the influence of both farming strategies on some
key performance and environmental aspects, such as benthic recovery, the breakdown of the life cycle
of pathogens, and adaptability to climate change. Our results suggest that changing the GHSB industry’s
production model is necessary for its sustainability.Versión del edito
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