1,511 research outputs found
Sugar cane loss monitor, adapted to a commercial chopper sugar-cane harvester
In the last few years the sugar-cane mechanical harvested area has increased, especially in regions with appropriated slop. The use of this technology brings some inconveniences, such as, the increase in the percentage of extraneous matter, which causes the reduction of technological quality of the raw material, and losses in the field. Extraneous matter (trash) is composed of tops and leaves in major percentage, plus soil and roots, and eventually some metal parts. In the green cane harvest system the percentage of extraneous matter has a tendency to increase due to the great amount of vegetal matter to be processed. The increase in the blower fan speed to reduce the amount of extraneous matter can lead to an unacceptable economic level of raw material losses. The main objective of this work was, using a cane loss monitor, to evaluate and quantify the amount of visible losses of sugar cane through the primary extractor at two different fan speeds. Afterwards these losses were related to the harvester cleaning efficiency. The piezoelectric transducer shows a reasonable sensibility. The results show that the cleaning efficiency in the primary extractor (85% mean), the cane losses (between 5.68% and 2.15%) and fan speed are interrelated. The total losses and specially splinters (between 3.19% and 0.91%), showed a significant difference among the treatments.A área de cana colhida mecanicamente tem crescido, sobretudo em regiões com relevo até 12% de declividade, principalmente por ser essa uma forma de viabilizar a colheita de cana-de-açúcar crua a um custo competitivo. A adoção desse sistema introduz certos inconvenientes, tais como: aumento dos índices de matéria estranha na carga, o que, por sua vez, implica a redução da qualidade tecnológica da matéria-prima fornecida para moagem, e perdas de colmos e/ou frações no campo. A tentativa de reduzir tais índices, por meio do aumento da velocidade de saída de ar dos extratores das colhedoras, pode aumentar as perdas de matéria-prima em níveis inaceitáveis economicamente. Este trabalho avaliou o nível de perdas visíveis de lascas de cana, por meio do extrator primário da colhedora, para duas rotações do ventilador, monitorado por sensor de perdas de cana desenvolvido especialmente para esse fim. Em seguida, essas perdas foram relacionadas com a eficiência de limpeza da colhedora. Os resultados mostraram que a eficiência de limpeza do extrator primário (cerca de 85%), as perdas de cana-de-açúcar em geral (entre 5,68% e 2,51%) e a velocidade do ventilador estão diretamente relacionados. As perdas (totais), e principalmente lascas (entre 3,91% e 0,91%), apontaram diferenças significativas entre os tratamentos estudados.76477
Tracing Noble Gas Radionuclides in the Environment
Trace analysis of radionuclides is an essential and versatile tool in modern
science and technology. Due to their ideal geophysical and geochemical
properties, long-lived noble gas radionuclides, in particular, 39Ar (t1/2 = 269
yr), 81Kr (t1/2 = 2.3x10^5 yr) and 85Kr (t1/2 = 10.8 yr), have long been
recognized to have a wide range of important applications in Earth sciences. In
recent years, significant progress has been made in the development of
practical analytical methods, and has led to applications of these isotopes in
the hydrosphere (tracing the flow of groundwater and ocean water). In this
article, we introduce the applications of these isotopes and review three
leading analytical methods: Low-Level Counting (LLC), Accelerator Mass
Spectrometry (AMS) and Atom Trap Trace Analysis (ATTA)
The role of matter density uncertainties in the analysis of future neutrino factory experiments
Matter density uncertainties can affect the measurements of the neutrino
oscillation parameters at future neutrino factory experiments, such as the
measurements of the mixing parameters and \deltacp. We compare
different matter density uncertainty models and discuss the possibility to
include the matter density uncertainties in a complete statistical analysis.
Furthermore, we systematically study in which measurements and where in the
parameter space matter density uncertainties are most relevant. We illustrate
this discussion with examples that show the effects as functions of different
magnitudes of the matter density uncertainties. We find that matter density
uncertainties are especially relevant for large \stheta \gtrsim 10^{-3}.
Within the KamLAND-allowed range, they are most relevant for the precision
measurements of \stheta and \deltacp, but less relevant for ``binary''
measurements, such as for the sign of \ldm, the sensitivity to \stheta, or
the sensitivity to maximal CP violation. In addition, we demonstrate that
knowing the matter density along a specific baseline better than to about 1%
precision means that all measurements will become almost independent of the
matter density uncertainties.Comment: 21 pages, 7 figures, LaTeX. Final version to be published in Phys.
Rev.
Key Ne states identified affecting -ray emission from F in novae
Detection of nuclear-decay rays provides a sensitive thermometer of
nova nucleosynthesis. The most intense -ray flux is thought to be
annihilation radiation from the decay of F, which is destroyed
prior to decay by the F(,)O reaction. Estimates of
F production had been uncertain, however, because key near-threshold
levels in the compound nucleus, Ne, had yet to be identified. This
Letter reports the first measurement of the
F(He,)Ne reaction, in which the placement of two
long-sought 3/2 levels is suggested via triton--
coincidences. The precise determination of their resonance energies reduces the
upper limit of the rate by a factor of at nova temperatures and
reduces the average uncertainty on the nova detection probability by a factor
of 2.1.Comment: 6 pages, 4 figure
New -ray Transitions Observed in Ne with Implications for the O(,)Ne Reaction Rate
The O(,)Ne reaction is responsible for breakout
from the hot CNO cycle in Type I x-ray bursts. Understanding the properties of
resonances between and 5 MeV in Ne is crucial in the
calculation of this reaction rate. The spins and parities of these states are
well known, with the exception of the 4.14- and 4.20-MeV states, which have
adopted spin-parities of 9/2 and 7/2, respectively. Gamma-ray
transitions from these states were studied using triton--
coincidences from the F(He,)Ne reaction measured
with GODDESS (Gammasphere ORRUBA Dual Detectors for Experimental Structure
Studies) at Argonne National Laboratory. The observed transitions from the
4.14- and 4.20-MeV states provide strong evidence that the values are
actually 7/2 and 9/2, respectively. These assignments are consistent
with the values in the F mirror nucleus and in contrast to previously
accepted assignments
Non-standard interactions versus non-unitary lepton flavor mixing at a neutrino factory
The impact of heavy mediators on neutrino oscillations is typically described
by non-standard four-fermion interactions (NSIs) or non-unitarity (NU). We
focus on leptonic dimension-six effective operators which do not produce
charged lepton flavor violation. These operators lead to particular
correlations among neutrino production, propagation, and detection non-standard
effects. We point out that these NSIs and NU phenomenologically lead, in fact,
to very similar effects for a neutrino factory, for completely different
fundamental reasons. We discuss how the parameters and probabilities are
related in this case, and compare the sensitivities. We demonstrate that the
NSIs and NU can, in principle, be distinguished for large enough effects at the
example of non-standard effects in the --sector, which basically
corresponds to differentiating between scalars and fermions as heavy mediators
as leading order effect. However, we find that a near detector at superbeams
could provide very synergistic information, since the correlation between
source and matter NSIs is broken for hadronic neutrino production, while NU is
a fundamental effect present at any experiment.Comment: 32 pages, 5 figures. Final version published in JHEP. v3: Typo in Eq.
(27) correcte
Measurement of a small atmospheric ratio
From an exposure of 25.5~kiloton-years of the Super-Kamiokande detector, 900
muon-like and 983 electron-like single-ring atmospheric neutrino interactions
were detected with momentum MeV/, MeV/, and
with visible energy less than 1.33 GeV. Using a detailed Monte Carlo
simulation, the ratio was measured to be , consistent with previous results from the
Kamiokande, IMB and Soudan-2 experiments, and smaller than expected from
theoretical models of atmospheric neutrino production.Comment: 14 pages with 5 figure
Early star-forming galaxies and the reionization of the Universe
Star forming galaxies represent a valuable tracer of cosmic history. Recent
observational progress with Hubble Space Telescope has led to the discovery and
study of the earliest-known galaxies corresponding to a period when the
Universe was only ~800 million years old. Intense ultraviolet radiation from
these early galaxies probably induced a major event in cosmic history: the
reionization of intergalactic hydrogen. New techniques are being developed to
understand the properties of these most distant galaxies and determine their
influence on the evolution of the universe.Comment: Review article appearing in Nature. This posting reflects a submitted
version of the review formatted by the authors, in accordance with Nature
publication policies. For the official, published version of the review,
please see http://www.nature.com/nature/archive/index.htm
The ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: Molecular Gas Reservoirs in High-redshift Galaxies
We study the molecular gas properties of high-z galaxies observed in the ALMA Spectroscopic Survey (ASPECS) that targets an ˜1 arcmin2 region in the Hubble Ultra Deep Field (UDF), a blind survey of CO emission (tracing molecular gas) in the 3 and 1 mm bands. Of a total of 1302 galaxies in the field, 56 have spectroscopic redshifts and correspondingly well-defined physical properties. Among these, 11 have infrared luminosities {L}{IR}\gt {10}11 {L}⊙ , i.e., a detection in CO emission was expected. Out of these, 7 are detected at various significance in CO, and 4 are undetected in CO emission. In the CO-detected sources, we find CO excitation conditions that are lower than those typically found in starburst/sub-mm galaxy/QSO environments. We use the CO luminosities (including limits for non-detections) to derive molecular gas masses. We discuss our findings in the context of previous molecular gas observations at high redshift (star formation law, gas depletion times, gas fractions): the CO-detected galaxies in the UDF tend to reside on the low-{L}{IR} envelope of the scatter in the {L}{IR}{--}{L}{CO}\prime relation, but exceptions exist. For the CO-detected sources, we find an average depletion time of ˜1 Gyr, with significant scatter. The average molecular-to-stellar mass ratio ({M}{{H}2}/M *) is consistent with earlier measurements of main-sequence galaxies at these redshifts, and again shows large variations among sources. In some cases, we also measure dust continuum emission. On average, the dust-based estimates of the molecular gas are a factor ˜2-5× smaller than those based on CO. When we account for detections as well as non-detections, we find large diversity in the molecular gas properties of the high-redshift galaxies covered by ASPECS
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