204 research outputs found
Preconditioning for Allen-Cahn variational inequalities with non-local constraints
The solution of Allen-Cahn variational inequalities with mass constraints is of interest in many applications. This problem can be solved both in its scalar and vector-valued form as a PDE-constrained optimization problem by means of a primal-dual active set method. At the heart of this method lies the solution of linear systems in saddle point form. In this paper we propose the use of Krylov-subspace solvers and suitable preconditioners for the saddle point systems. Numerical results illustrate the competitiveness of this approach
Assessment of Heart Disease using Fuzzy Classification Techniques
In this paper we discuss the classification results of cardiac patients of ischemical cardiopathy, valvular heart disease, and arterial hypertension, based on 19 characteristics (descriptors) including ECHO data, effort testings, and age and weight. In this order we have used different fuzzy clustering algorithms, namely hierarchical fuzzy clustering, hierarchical and horizontal fuzzy characteristics clustering, and a new clustering technique, fuzzy hierarchical cross-classification. The characteristics clustering techniques produce fuzzy partitions of the characteristics involved and, thus, are useful tools for studying the similarities between different characteristics and for essential characteristics selection. The cross-classification algorithm produces not only a fuzzy partition of the cardiac patients analyzed, but also a fuzzy partition of their considered characteristics. In this way it is possible to identify which characteristics are responsible for the similarities or dissimilarities observed between different groups of patients
Introducing Semi-Interpenetrating Networks of Chitosan and Ammonium-Quaternary Polymers for the Effective Removal of Waterborne Pathogens from Wastewaters
The present work aims to study the influence of ammonium-quaternary monomers and chitosan, obtained from different sources, upon the effect of semi-interpenetrating polymer network (semi-IPN) hydrogels upon the removal of waterborne pathogens and bacteria from wastewater. To this end, the study was focused on using vinyl benzyl trimethylammonium chloride (VBTAC), a water-soluble monomer with known antibacterial properties, and mineral-enriched chitosan extracted from shrimp shells, to prepare the semi-IPNs. By using chitosan, which still contains the native minerals (mainly calcium carbonate), the study intends to justify that the stability and efficiency of the semi-IPN bactericidal devices can be modified and better improved. The new semi-IPNs were characterized for composition, thermal stability and morphology using well-known methods. Swelling degree (SD%) and the bactericidal effect assessed using molecular methods revealed that hydrogels made of chitosan derived from shrimp shell demonstrated the most competitive and promising potential for wastewater (WW) treatment.Introducing Semi-Interpenetrating Networks of Chitosan and Ammonium-Quaternary Polymers for the Effective Removal of Waterborne Pathogens from WastewaterspublishedVersio
Time-Varying Dark Energy Constraints From the Latest SN Ia, BAO and SGL
Based on the latest SNe Ia data provided by Hicken et al. (2009) with using
MLCS17 light curve fitter, together with the Baryon Acoustic Oscillation(BAO)
and strong gravitational lenses(SGL), we investigate the constraints on the
dark energy equation-of-state parameter in the flat universe, especially
for the time-varying case . The constraints from SNe data
alone are found to be: (a) as the best-fit
results; (b) for
the two parameters in the time-varying case after marginalizing the parameter
; (c) the likelihood of parameter has a high non-Gaussian
distribution; (d) an extra restriction on is necessary to improve
the constraint of the SNe Ia data on the parameters (, ). A joint
analysis of SNe Ia data and BAO is made to break the degeneracy between and
, and leads to the interesting maximum likelihoods and
. When marginalizing the parameter , the fitting results are
found to be . After
adding the splitting angle statistic of SGL data, a consistent constraint is
obtained and the constraints on time-varying
dark energy are further improved to be , which indicates that the phantom type models are
disfavored.Comment: 24 pages, 9 figures, to be published in JCA
PHYMYCO-DB: A curated database for analyses of fungal diversity and evolution.
International audienceBackground: In environmental sequencing studies, fungi can be identified based on nucleic acid sequences, using either highly variable sequences as species barcodes or conserved sequences containing a high-quality phylogenetic signal. For the latter, identification relies on phylogenetic analyses and the adoption of the phylogenetic species concept. Such analysis requires that the reference sequences are well identified and deposited in public-access databases. However, many entries in the public sequence databases are problematic in terms of quality and reliability and these data require screening to ensure correct phylogenetic interpretation. Methods and Principal Findings: To facilitate phylogenetic inferences and phylogenetic assignment, we introduce a fungal sequence database. The database PHYMYCO-DB comprises fungal sequences from GenBank that have been filtered to satisfy stringent sequence quality criteria. For the first release, two widely used molecular taxonomic markers were chosen: the nuclear SSU rRNA and EF1-a gene sequences. Following the automatic extraction and filtration, a manual curation is performed to remove problematic sequences while preserving relevant sequences useful for phylogenetic studies. As a result of curation, ,20% of the automatically filtered sequences have been removed from the database. To demonstrate how PHYMYCO-DB can be employed, we test a set of environmental Chytridiomycota sequences obtained from deep sea samples. Conclusion: PHYMYCO-DB offers the tools necessary to: (i) extract high quality fungal sequences for each of the 5 fungal phyla, at all taxonomic levels, (ii) extract already performed alignments, to act as 'reference alignments', (iii) launch alignments of personal sequences along with stored data. A total of 9120 SSU rRNA and 672 EF1-a high-quality fungal sequences are now available. The PHYMYCO-DB is accessible through the URL http://phymycodb.genouest.org/
Prospects for the Improvement of Energy Performance in Agroindustry Using Phase Change Materials
This work was partially supported by the Fundação para a Ciência e Tecnologia, UIDB/00066/2020 (CTS – Center of Technology and Systems).The use of Phase Change Materials (PCMs), able to store latent heat, represents an opportunity to improve energy efficiency in the agroindustry by means of thermal energy storage. PCMs provide higher energy density then sensible heat storage mediums, thus paving the way to multiple applications, like supporting the integration of renewables or allowing for new storage architectures, decentralized and directly installed in the chain production equipment, creating e.g. the opportunity to recover and value low-grade operational heat sub-products. Such new and decentralized architecture, not currently applied in agroindustry, is proposed in this work. A chocolate tempering machine using an organic PCM is conceived and analyzed using ANSYS Fluent software for computational fluid dynamics simulations, comparing the main aspects in the storage capacity and discharging process with a conventional sensitive heat storage solution that uses water. PCMs allows improving the stored energy, keeping the chocolate in the working temperature after being tempered for more than four times longer than using only hot water. If the PCMs are charged by renewables, the self-consumption ratio can be improved while providing energy flexibility to the user.authorsversionpublishe
Redshift of the Einstein Ring in MG1549+305
A deep spectrum taken with the Echelle Spectrograph and Imager (ESI) at the
Keck II Telescope as part of the Lenses Structure and Dynamics (LSD) Survey
reveals the redshifts of the extremely red source of the radio Einstein Ring in
the gravitational lens system MG1549+305 () and an
intermediate redshift lensed spiral galaxy (). The
source redshift allows us to determine the mass of the SB0 lens galaxy enclosed
by the Einstein Radius (R_{\rm E}=1\farcs15\pm0\farcs05) M.
This corresponds to a Singular Isothermal Ellipsoid (SIE) velocity dispersion
\kms, in good agreement with the measured stellar
velocity dispersion \kms (Leh\'ar et al. 1996). The
mass-to-light ratio within the Einstein Radius (1.4 effective radii) is
\mlu. This is only marginally larger than typical stellar
mass-to-light ratios of local early-type galaxies, indicating that dark matter
is not likely to be dominant inside the Einstein Radius.Comment: 4 pages, 3 figures, accepted for publication in MNRA
The amplitude of mass fluctuations and mass density of the Universe constrained by strong gravitational lensing
We investigate the linear amplitude of mass fluctuations in the universe,
, and the present mass density parameter of the Universe,
, from the statistical strong gravitational lensing. We use
the two populations of lens halos model with fixed cooling mass scale
M_\mathrm{c}=3\times 10^{13}h^{-1}M_{\sun} to match the observed lensing
probabilities, and leave or as a free parameter
to be constrained by data. Another varying parameter is the equation of state
of dark energy , and its typical values of -1, -2/3, -1/2 and -1/3 are
investigated. We find that is degenerate with in
a way similar to that suggested by present day cluster abundance as well as
cosmic shear lensing measurements: (Bahcall & Bode\cite{bahcall03a} and references therein). However, both
and can be safely ruled out, the
best value is when , and .
This result is different from that obtained by Bahcall & Bode
(\cite{bahcall03a}), who gives and . For , higher value of requires
and requires .Comment: 9 pages, 4 figures, references update
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