1,071 research outputs found
logistic regression and response surface design for statistical modeling of investment casting process in metal foam production
Abstract A metal foam represents a promising material since it keeps the high mechanical properties of the metal while reducing the weight up to 90%. Among several manufacturing processes, the investment casting is a foundry process flexible enough to be suitable both for stochastic and for regular foams. This paper presents an experimental determination of the manufacturing process of metal regular foams by investment casting. The goal is to derive experimentally an actual formability map. The use of logistic regression and response surface design is proposed as an effective tool for determining a statistical model of the metal foam casting process
Binary Gaussian Process classification of quality in the production of aluminum alloys foams with regular open cells
none2noAluminum alloys foams with homogeneous and regular open cells have been frequently proposed and used as support structures for catalytic applications. In this kind of application, the quality of produced metal foam assumes primary importance. This paper presents an application of a classifier algorithm to predict quality in the manufacturing process of aluminum alloy foams with homogeneous and regular open cells. A data analysis methodology of experimental data, which is based on Binary Gaussian Process Classification, is presented. The proposed method is a Bayesian classification method, which gets away from any assumptions about the relationship between process inputs (the geometric design parameters of the regular unit cells) and process output (probability to obtain defective foam). We demonstrate that the proposed methodology can provide an effective tool to derive a model for the prediction of quality. An investment casting process, via 3D printing of wax patterns, is considered throughout the paper. Despite this specific case study, the methodology can be exploited in different processes in which the assumptions of traditional statistical approaches could not be easily verified, e.g., additive manufacturing.openAnglani A.; Pacella M.Anglani, A.; Pacella, M
Pions in the quark matter phase diagram
The relationship between mesonic correlations and quantum condensates in the
quark matter phase diagram is explored within a quantum field theoretical
approach of the Nambu and Jona-Lasinio (NJL) type. Mean-field values in the
scalar meson and diquark channels are order parameters signalling the
occurrence of quark condensates, entailing chiral symmetry breaking (chi SB)
and color superconductivity (2SC) in quark matter. We investigate the spectral
properties of scalar and pseudoscalar meson excitations in the phase diagram in
Gaussian approximation and show that outside the chi SB region where the pion
is a zero-width bound state, there are two regions where it can be considered
as a quasi-bound state with a lifetime exceeding that of a typical heavy-ion
collision fireball: (A) the high-temperature chi SB crossover region at low
densities and (B) the high-density color superconducting phase at temperatures
below 100 MeV.Comment: presented by D. Zablocki at the Joint Meeting
Heidelberg-Liege-Paris-Wroclaw (HLPW08), Spa, Belgium, 6-8 March 2008, 10
pages, 5 figures, LaTeX, uses aip-6s.clo, aipproc.cls and aipxfm.sty
(included
A comparative study of Gaussian Graphical Model approaches for genomic data
The inference of networks of dependencies by Gaussian Graphical models on
high-throughput data is an open issue in modern molecular biology. In this
paper we provide a comparative study of three methods to obtain small sample
and high dimension estimates of partial correlation coefficients: the
Moore-Penrose pseudoinverse (PINV), residual correlation (RCM) and
covariance-regularized method . We first compare them on simulated
datasets and we find that PINV is less stable in terms of AUC performance when
the number of variables changes. The two regularized methods have comparable
performances but is much faster than RCM. Finally, we present the
results of an application of for the inference of a gene network
for isoprenoid biosynthesis pathways in Arabidopsis thaliana.Comment: 7 pages, 1 figure, RevTex4, version to appear in the proceedings of
1st International Workshop on Pattern Recognition, Proteomics, Structural
Biology and Bioinformatics: PR PS BB 2011, Ravenna, Italy, 13 September 201
Inhomogeneous charged pion condensation phenomenon in the NJL model with quark number and isospin chemical potentials
The properties of two-flavored massive Nambu--Jona-Lasinio model in
(1+1)-dimensional spacetime are investigated in the presence of isospin and
quark number chemical potentials. The consideration is performed in the
large- limit, where is the number of colored quarks. It is shown in
the framework of this model that charged pion condensation phenomenon of dense
quark/hadron isotopically asymmetric matter is rather a spatially inhomogeneous
than a homogeneous one.Comment: 11 pages, 8 figures; version accepted for publication in PRD. arXiv
admin note: text overlap with arXiv:1106.2928, arXiv:1102.407
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