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Flow patterns and heat transfer in a square cross-section micro condenser working at low mass fluxes
This paper was presented at the 3rd Micro and Nano Flows Conference (MNF2011), which was held at the Makedonia Palace Hotel, Thessaloniki in Greece. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, Aristotle University of Thessaloniki, University of Thessaly, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute.Flow patterns and heat transfer in an air-cooled square cross-section micro condenser were investigated. The test section consisted of a borosilicate square micro channel, of inner and outer hydraulic diameters of 0.49 mm and 0.6 mm respectively, and a length of 100 mm. The transparent material of the micro channel allowed the visualization of the different condensation flow patterns. The imposed mass velocities were ranging between 1 and 10 kg m-2 s-1. In this range of mass fluxes, three main flow regimes were identified: Annular regime, intermittent regime, and spherical bubbles regime. Then, the isolated bubbles zone (the end of the intermittent zone + the spherical bubbles zone) was particularly studied. A specific experimental procedure was developed, basing on bubble tracking, in order to determine accurately the hydraulic and thermal parameters profiles in this zone according to the axial position in the micro channel, such as the vapour quality profile x(z). Thanks to energy balance, the liquid temperature profile Tl(z) in the isolated bubbles zone was determined for different initial values. A thermal non-equilibrium between the liquid and vapour phases was identified. Therefore, the latent heat flux was then quantified and compared to the total heat flux in this zone.FNRAE (MATRAS) and the Microgravity Application Program of the European Space Agenc
Monitoring the Paraguayan epidemiological dengue surveillance system (2009-2011) using Benford's law
Introduction: Dengue is the most widespread arbovirus worldwide. In Paraguay, it reappeared in 1988-1989, with one of the largest epidemic outbreaks occurring in 2011. Objective: To evaluate the performance of the dengue epidemiological surveillance system in Paraguay between 2009 and 2011. Materials and methods: We conducted an ecological study with secondary epidemiological surveillance data. We analyzed notified cases of the disease based on the distribution expected by Benford's law. To this end, we used the first and second digits from the global records stratified by region, season, population density, indicators of housing conditions and heads of cattle. Results: The epidemiological surveillance system performed better during non-epidemic periods and in the states with better housing conditions and fewer heads of cattle. Conclusion: Given that a difference in the performance existed, we recommended that the system remains operating at the same high alert level even during periods when fewer cases are expected. The technology used by the method proposed to monitor the notification of cases is easy to transfer to operational staff
A new ordering principle for the classical statistical analysis of Poisson processes with background
Inspired by the recent proposal by Feldman and Cousins of a ``unified
approach to the classical statistical analysis of small signals'' based on a
choice of ordering in Neyman's construction of classical confidence intervals,
I propose a new ordering principle for the classical statistical analysis of
Poisson processes with background which minimizes the effect on the resulting
confidence intervals of the observation of less background events than
expected. The new ordering principle is applied to the calculation of the
confidence region implied by the recent null result of the KARMEN neutrino
oscillation experiment.Comment: 16 pages including 5 figures, RevTeX. Final version published in
Phys. Rev. D 59 (1999) 05300
Effects of neutrino oscillations and neutrino magnetic moments on elastic neutrino-electron scattering
We consider elastic antineutrino-electron scattering taking into account
possible effects of neutrino masses and mixing and of neutrino magnetic moments
and electric dipole moments. Having in mind antineutrinos produced in a nuclear
reactor we compute, in particular, the weak-electromagnetic interference terms
which are linear in the magnetic (electric dipole) moments and also in the
neutrino masses. We show that these terms are, however, suppressed compared to
the pure weak and electromagnetic cross section. We also comment upon the
possibility of using the electromagnetic cross section to investigate neutrino
oscillations.Comment: 12 pages, REVTEX file, no figures, submitted to Phys.Rev.
Limits on the neutrino magnetic moment from the MUNU experiment
The MUNU experiment was carried out at the Bugey nuclear power reactor. The
aim was the study of electron antineutrino-electron elastic scattering at low
energy. The recoil electrons were recorded in a gas time projection chamber,
immersed in a tank filled with liquid scintillator serving as veto detector,
suppressing in particular Compton electrons. The measured electron recoil
spectrum is presented. Upper limits on the neutrino magnetic moment were
derived and are discussed.Comment: 9 pages, 7 figures Added reference: p.3, 1st col., TEXONO Added
sentence: p.4, 1st col., electron attachement Modified sentence: p.5, 1st
col., readout sequence Added sentence: p.5, 1st col., fast rise time cu
Is CP Violation Observable in Long Baseline Neutrino Oscillation Experiments ?
We have studied CP violation originated by the phase of the neutrino mixing
matrix in the long baseline neutrino oscillation experiments. The direct
measurements of CP violation is the difference of the transition probabilities
between CP-conjugate channels. In those experiments, the CP violating effect is
not suppressed if the highest neutrino mass scale is taken to be 1\sim 5 \eV,
which is appropriate for the cosmological hot dark matter. Assuming the
hierarchy for the neutrino masses, the upper bounds of CP violation have been
caluculated for three cases, in which mixings are constrained by the recent
short baseline ones. The calculated upper bounds are larger than ,
which will be observable in the long baseline accelerator experiments. The
matter effect, which is not CP invariant, has been also estimated in those
experiments.Comment: 28 pages, LaTex file, 6 figures included using epsfig Matter effect
is estimated(Figs.3(a) (b)). Physical parameters are change
Lepton Mixing Matrix in Standard Model Extended by One Sterile Neutrino
We consider the simplest extension of the standard electroweak model by one
sterile neutrino that allows for neutrino masses and mixing. We find that its
leptonic sector contains much less free physical parameters than previously
realized. In addition to the two neutrino masses, the lepton mixing matrix in
charged current interactions involves (n-1) free physical mixing angles for n
generations. The mixing matrix in neutral current interactions of neutrinos is
completely fixed by the two masses. Both interactions conserve CP. We
illustrate the phenomenological implications of the model by vacuum neutrino
oscillations, tritium beta decay and neutrinoless double beta decay. It turns
out that, due to the revealed specific structure in its mixing matrix, the
model with any n generations cannot accommodate simultaneously the data by
KamLAND, K2K and CHOOZ.Comment: 14 pages, no figures; version 2: (1) added a short paragraph at the
end of subsec 2.2 to record the counting of physical parameters for any
numbers of generations and sterile neutrinos for completeness; (2) added a
note in ref list, item [18] to quote and comment on an earlier work; (3)
added the second paper to ref list, item [17]; (4) fixed typo
Chaotic Amplification of Neutrino Chemical Potentials by Neutrino Oscillations in Big Bang Nucleosynthesis
We investigate in detail the parameter space of active-sterile neutrino
oscillations that amplifies neutrino chemical potentials at the epoch of Big
Bang Nucleosynthesis. We calculate the magnitude of the amplification and show
evidences of chaos in the amplification process. We also discuss the
implications of the neutrino chemical potential amplification in the Big Bang
Nucleosynthesis. It is shown that with a eV \nue, the amplification
of its chemical potential by active-sterile neutrino oscillations can lower the
effective number of neutrino species at Big Bang Nucleosynthesis to
significantly below 3.Comment: Revtex 20 pages, 7 postscript figures. Also by
ftp://astro.queensu.ca/pub/shi/ . Submitted to PR
Constraints on long-baseline neutrino oscillation probabilities and CP asymmetries from neutrino oscillation data
We consider long-baseline neutrino oscillations in the framework of two
schemes with mixing of four massive neutrinos which can accommodate all the
existing indications in favour of neutrino mixing. Within these schemes, we
derive bounds on the oscillation probabilities and the CP-odd
neutrino-antineutrino asymmetries in long-baseline experiments. Using the
results of short-baseline neutrino oscillation experiments, we obtain rather
strong upper bounds on the long-baseline probabilities 1-P(nu_e->nu_e) and
P(nu_mu->nu_e). Nevertheless, the projected sensitivities of the MINOS and
ICARUS experiments are better than our bounds. We also show that there are no
corresponding constraints for nu_mu->nu_mu and nu_mu->nu_tau long-baseline
oscillations and that the CP-odd asymmetry in the latter channel can reach the
maximal value allowed by the unitarity of the mixing matrix. Some schemes with
mixing of three neutrinos are also considered.Comment: 32 pages including 5 figures, RevTeX. New discussion of the matter
effect
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