5,267 research outputs found
Unsupervised machine learning for detection of phase transitions in off-lattice systems I. Foundations
We demonstrate the utility of an unsupervised machine learning tool for the
detection of phase transitions in off-lattice systems. We focus on the
application of principal component analysis (PCA) to detect the freezing
transitions of two-dimensional hard-disk and three-dimensional hard-sphere
systems as well as liquid-gas phase separation in a patchy colloid model. As we
demonstrate, PCA autonomously discovers order-parameter-like quantities that
report on phase transitions, mitigating the need for a priori construction or
identification of a suitable order parameter--thus streamlining the routine
analysis of phase behavior. In a companion paper, we further develop the method
established here to explore the detection of phase transitions in various model
systems controlled by compositional demixing, liquid crystalline ordering, and
non-equilibrium active forces
Generation and use of unstructured grids for turbomachinery calculations
A wavefront mesh generator for two dimensional triangular meshes as well as a brief description of the solution method used with these meshes are presented. The interest is in creating meshes for solving the equations of fluid mechanics in complex turbomachinery problems, although the mesh generator and flow solver may be used for a larger variety of applications. The focus is on the flexibility and power of the mesh generation method for triangulating extremely complex geometries and in changing the geometry to create a new mesh. Two turbomachinery applications are presented which take advantage of this method: the analysis of pylon/strut and pylon/OGV interaction in the bypass of a turbofan
Vertical Transmission of a Phylogenetically Complex Microbial Consortium in the Viviparous Sponge \u3cem\u3eIrcinia Felix\u3c/em\u3e
Many marine demosponges contain large amounts of phylogenetically complex yet highly sponge-specific microbial consortia within the mesohyl matrix, but little is known about how these microorganisms are acquired by their hosts. Settlement experiments were performed with the viviparous Caribbean demosponge Ircinia felix to investigate the role of larvae in the vertical transmission of the sponge-associated microbial community. Inspections by electron microscopy revealed large amounts of morphologically diverse microorganisms in the center of I. felix larvae, while the outer rim appeared to be devoid of microorganisms. In juveniles, microorganisms were found between densely packed sponge cells. Denaturing gradient gel electrophoresis (DGGE) was performed to compare the bacterial community profiles of adults, larvae, and juvenile sponges. Adults and larvae were highly similar in DGGE band numbers and banding patterns. Larvae released by the same adult individual contained highly similar DGGE banding patterns, whereas larvae released by different adult individuals showed slightly different DGGE banding patterns. Over 200 bands were excised, sequenced, and phylogenetically analyzed. The bacterial diversity of adult I. felix and its larvae was comparably high, while juveniles showed reduced diversity. In total, 13 vertically transmitted sequence clusters, hereafter termed “IF clusters,” that contained sequences from both the adult sponge and offspring (larvae and/or juveniles) were found. The IF clusters belonged to at least four different eubacterial phyla and one possibly novel eubacterial lineage. In summary, it could be shown that in I. felix, vertical transmission of microorganisms through the larvae is an important mechanism for the establishment of the sponge-microbe association
Studies in transplanting summer squash
Call number: LD2668 .T4 HORT 1988 L56Master of ScienceHorticulture, Forestry, and Recreation Resource
Unsupervised machine learning for detection of phase transitions in off-lattice systems II. Applications
We outline how principal component analysis (PCA) can be applied to particle
configuration data to detect a variety of phase transitions in off-lattice
systems, both in and out of equilibrium. Specifically, we discuss its
application to study 1) the nonequilibrium random organization (RandOrg) model
that exhibits a phase transition from quiescent to steady-state behavior as a
function of density, 2) orientationally and positionally driven equilibrium
phase transitions for hard ellipses, and 3) compositionally driven demixing
transitions in the non-additive binary Widom-Rowlinson mixture
Measurement of temperature profiles in hot gases and flames
Computer program was written for calculation of molecular radiative transfer from hot gases. Shape of temperature profile was approximated in terms of simple geometric forms so profile could be characterized in terms of few parameters. Parameters were adjusted in calculations using appropriate radiative-transfer expression until best fit was obtained with observed spectra
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