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Support minimized inversion of acoustic and elastic wave scattering (open access)

Support minimized inversion of acoustic and elastic wave scattering

This report discusses the following topics on support minimized inversion of acoustic and elastic wave scattering: Minimum support inversion; forward modelling of elastodynamic wave scattering; minimum support linearized acoustic inversion; support minimized nonlinear acoustic inversion without absolute phase; and support minimized nonlinear elastic inversion.
Date: April 24, 1994
Creator: Safaeinili, A.
System: The UNT Digital Library
The mechanism of the oligomerization of thiophene-based para-quinodimethanes (open access)

The mechanism of the oligomerization of thiophene-based para-quinodimethanes

For the last decade, the Trahanovsky research group has focused on the study of various reactive molecules such as o-quinodimethanes (o-QDM`s) and p-quinodimethanes (p-QDM`s) derived from benzene, furan, and thiophene. These types of molecules are reactive and dimerize or polymerize at room temperature. One of the group`s interests is to understand the dimerization mechanism of these molecules. Paper 1 describes the preparation and dimerization product analyses of 2-ethylidene-5-methylene-2,5-dihydrothiophene. Insights provided by these results into the mechanism of the dimerization of 2,5-dimethylene-2,5-dihydrothiophene are discussed. In paper 2, a convenient synthesis of cyclooctadecane is presented.
Date: April 24, 1994
Creator: Wang, Yili
System: The UNT Digital Library
The analysis and minimization of oxygen contamination in the powder processing of molybdenum disilicide (open access)

The analysis and minimization of oxygen contamination in the powder processing of molybdenum disilicide

Problems with MoSi{sub 2} include low-temperature fracture toughness, high-temperature creep resistance, and ``pest`` phenomena. Oxygen introduced by powder processing may be the cause of some of these problems. This study led to the following conclusions: Supplied powders have significant oxygen present prior to processing (up to 2.5 %), in the form of silica on the surface. This oxygen contamination did not increase by exposure to air at room temperature. An improved powder processing method was developed that uses glass encapsulation. Analysis of microstructures created from powders that contained 4900 to 24,100 ppM oxygen showed that the silica was transferred to the fully dense MoSi{sub 2} as SiO{sub 2} inclusions. A method of producing MoSi{sub 2} with less oxygen was attempted.
Date: April 24, 1994
Creator: Shannon, K.
System: The UNT Digital Library
GAiN: Distributed Array Computation with Python (open access)

GAiN: Distributed Array Computation with Python

Scientific computing makes use of very large, multidimensional numerical arrays - typically, gigabytes to terabytes in size - much larger than can fit on even the largest single compute node. Such arrays must be distributed across a "cluster" of nodes. Global Arrays is a cluster-based software system from Battelle Pacific Northwest National Laboratory that enables an efficient, portable, and parallel shared-memory programming interface to manipulate these arrays. Written in and for the C and FORTRAN programming languages, it takes advantage of high-performance cluster interconnections to allow any node in the cluster to access data on any other node very rapidly. The "numpy" module is the de facto standard for numerical calculation in the Python programming language, a language whose use is growing rapidly in the scientific and engineering communities. numpy provides a powerful N-dimensional array class as well as other scientific computing capabilities. However, like the majority of the core Python modules, numpy is inherently serial. Our system, GAiN (Global Arrays in NumPy), is a parallel extension to Python that accesses Global Arrays through numpy. This allows parallel processing and/or larger problem sizes to be harnessed almost transparently within new or existing numpy programs.
Date: April 24, 2009
Creator: Daily, Jeffrey A.
System: The UNT Digital Library