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Papers by William Thissell

Bulletin of the American Physical Society, 2005

damage in the "spall plane" of tantalum incipiently spalled in a gas gun consists of voids and re... more damage in the "spall plane" of tantalum incipiently spalled in a gas gun consists of voids and regions of localized shear between the voids. A continuous path can be traced through these features from one side of the spall plane to the other. The geometry of this path has been analyzed using wavelets to show that it constitutes, to a good approximation, an affine fractal, i. e it is statistically invariant with power law dependence with different exponents normal to and along the spall plane. The details of this analysis will be presented together with insight as to the physical meaning of the results.

2015 IEEE International Conference on Computer Vision Workshop (ICCVW), 2015

A scalable open systems and standards derived software ecosystem is described for computer vision... more A scalable open systems and standards derived software ecosystem is described for computer vision analytics (CVA) assisted exploitation of full motion video (FMV). The ecosystem, referred to as the Advanced Video Activity Analytics (AVAA), has two instantiations, one for size, weight, and power (SWAP) constrained conditions, and the other for large to massive cloud based configurations. The architecture is designed to meet operational analyst requirements to increase their productivity and accuracy for exploiting FMV using local cluster or scalable cloudbased computing resources. CVAs are encapsulated within a software plug-in architecture and FMV processing pipelines are constructed by combining these plug-ins to accomplish analytical tasks and manage provenance of processing history. An example pipeline for real-time motion detection and moving object characterization using the flux tensor approach is presented. An example video ingest experiment is described. Quantitative and qualitative methods for human factors engineering (HFE) assessment to evaluate cognitive loads for alternative work flow design choices are discussed. This HFE process is used for validating that an AVAA system instantiation with candidate workflow pipelines meets CVA assisted FMV exploitation operational goals for specific analyst workflows. AVAA offers a new framework for video understanding at scale for large enterprise applications in the government and commercial sectors.

Several spallation experiments have been performed on uranium using gas gun driven normal plate i... more Several spallation experiments have been performed on uranium using gas gun driven normal plate impacts with VISAR instrumentation and soft recovery. The shock pressures achieved were 81,53, and 37 kbar. This paper will focus on modeling the free surface particle velocity trace U with of 300 ppm carbon using the I d characteristics code CHARADE. The spallation model involves the growth and coalescence of brittle cracks. Metallographical examination of recovered samples and details of the experimental apparatus are discussed in separate papers.

Ductile fracture in metals occurs by nucleation, growth, and coalescence of microvoids. We descri... more Ductile fracture in metals occurs by nucleation, growth, and coalescence of microvoids. We describe a statistical model for coalescence of voids based on localized instabilities that thin out the intervoid ligament. The model includes the stress and strain conditions for the creation of the instabilities and describes how clusters of coalesced voids grow by this process. Calculations for gas gun

Le Journal de Physique IV, 2000

Two different plates of 10100 Cu (> 99.99 % Cu) were incipiently failed using flyer plate impact ... more Two different plates of 10100 Cu (> 99.99 % Cu) were incipiently failed using flyer plate impact in a gas gun equipped with soft recovery. The cleanliness of the plates was assessed using the cold crucible melt technique. One of the plates was also tested using a momentum trapped tensile Hopkinson split pressure bar (THSPB). The recovered specimens were metallographically sectioned, polished, and etched. The resulting damage was also quantified using image analysis and optical profilometry. Micro computed tomography was also performed on two flyer plate specimens and these three dimensional measurements are compared to the sectional measurements. The quantified damage is statistically analyzed for porosity, spatially resolved volumetric void number densities and size distributions, near-neighbor distances, and clustering. A comparison is made in the THSPB tests between the relative contributions of the texture development and damage accumulation towards the overall mechanical behavior of the material.

Computers & Mathematics with Applications, 1991

The potential advantages of using symbolic manipulation software in the analysis of mathematical ... more The potential advantages of using symbolic manipulation software in the analysis of mathematical models that describe typical chemical engineering systems is described. It is suggested that the systematic application of computerized symbolic manipulation would permit application problems in chemical engineering to be solved with greater efficiency and accuracy than using tedious manual operations which are susceptible to error. In addition, a greater degree of mathematical sophistication is possible which can provide greater insight into the physical situation when compared to purely numerical techniques. To introduce the application of symbolic manipulation to chemical engineering systems, several example problems are briefly described and solved using the software package MACSYMA. The particular ones used here describe the flow of thin liquid films, the exit age probability density function for nonideal mixing in a continuous-flow stirred tank, the steady-state reactant concentrations that exist in a train of backmixed reactors with first-order reaction, and the steady-state concentrations of an organic species in a countercurrent flow multistage extraction column. The use of these for pedagogical purposes and as an entry point for analysis of more sophisticated applications is suggested and discussed. B CAi C1 = fluid viscosity, gcm-1 s-1. = fluid density, gcm-3.

Bulletin of the American Physical Society, 2005

damage in the "spall plane" of tantalum incipiently spalled in a gas gun consists of voids and re... more damage in the "spall plane" of tantalum incipiently spalled in a gas gun consists of voids and regions of localized shear between the voids. A continuous path can be traced through these features from one side of the spall plane to the other. The geometry of this path has been analyzed using wavelets to show that it constitutes, to a good approximation, an affine fractal, i. e it is statistically invariant with power law dependence with different exponents normal to and along the spall plane. The details of this analysis will be presented together with insight as to the physical meaning of the results.

2015 IEEE International Conference on Computer Vision Workshop (ICCVW), 2015

A scalable open systems and standards derived software ecosystem is described for computer vision... more A scalable open systems and standards derived software ecosystem is described for computer vision analytics (CVA) assisted exploitation of full motion video (FMV). The ecosystem, referred to as the Advanced Video Activity Analytics (AVAA), has two instantiations, one for size, weight, and power (SWAP) constrained conditions, and the other for large to massive cloud based configurations. The architecture is designed to meet operational analyst requirements to increase their productivity and accuracy for exploiting FMV using local cluster or scalable cloudbased computing resources. CVAs are encapsulated within a software plug-in architecture and FMV processing pipelines are constructed by combining these plug-ins to accomplish analytical tasks and manage provenance of processing history. An example pipeline for real-time motion detection and moving object characterization using the flux tensor approach is presented. An example video ingest experiment is described. Quantitative and qualitative methods for human factors engineering (HFE) assessment to evaluate cognitive loads for alternative work flow design choices are discussed. This HFE process is used for validating that an AVAA system instantiation with candidate workflow pipelines meets CVA assisted FMV exploitation operational goals for specific analyst workflows. AVAA offers a new framework for video understanding at scale for large enterprise applications in the government and commercial sectors.

Several spallation experiments have been performed on uranium using gas gun driven normal plate i... more Several spallation experiments have been performed on uranium using gas gun driven normal plate impacts with VISAR instrumentation and soft recovery. The shock pressures achieved were 81,53, and 37 kbar. This paper will focus on modeling the free surface particle velocity trace U with of 300 ppm carbon using the I d characteristics code CHARADE. The spallation model involves the growth and coalescence of brittle cracks. Metallographical examination of recovered samples and details of the experimental apparatus are discussed in separate papers.

Ductile fracture in metals occurs by nucleation, growth, and coalescence of microvoids. We descri... more Ductile fracture in metals occurs by nucleation, growth, and coalescence of microvoids. We describe a statistical model for coalescence of voids based on localized instabilities that thin out the intervoid ligament. The model includes the stress and strain conditions for the creation of the instabilities and describes how clusters of coalesced voids grow by this process. Calculations for gas gun

Le Journal de Physique IV, 2000

Two different plates of 10100 Cu (> 99.99 % Cu) were incipiently failed using flyer plate impact ... more Two different plates of 10100 Cu (> 99.99 % Cu) were incipiently failed using flyer plate impact in a gas gun equipped with soft recovery. The cleanliness of the plates was assessed using the cold crucible melt technique. One of the plates was also tested using a momentum trapped tensile Hopkinson split pressure bar (THSPB). The recovered specimens were metallographically sectioned, polished, and etched. The resulting damage was also quantified using image analysis and optical profilometry. Micro computed tomography was also performed on two flyer plate specimens and these three dimensional measurements are compared to the sectional measurements. The quantified damage is statistically analyzed for porosity, spatially resolved volumetric void number densities and size distributions, near-neighbor distances, and clustering. A comparison is made in the THSPB tests between the relative contributions of the texture development and damage accumulation towards the overall mechanical behavior of the material.

Computers & Mathematics with Applications, 1991

The potential advantages of using symbolic manipulation software in the analysis of mathematical ... more The potential advantages of using symbolic manipulation software in the analysis of mathematical models that describe typical chemical engineering systems is described. It is suggested that the systematic application of computerized symbolic manipulation would permit application problems in chemical engineering to be solved with greater efficiency and accuracy than using tedious manual operations which are susceptible to error. In addition, a greater degree of mathematical sophistication is possible which can provide greater insight into the physical situation when compared to purely numerical techniques. To introduce the application of symbolic manipulation to chemical engineering systems, several example problems are briefly described and solved using the software package MACSYMA. The particular ones used here describe the flow of thin liquid films, the exit age probability density function for nonideal mixing in a continuous-flow stirred tank, the steady-state reactant concentrations that exist in a train of backmixed reactors with first-order reaction, and the steady-state concentrations of an organic species in a countercurrent flow multistage extraction column. The use of these for pedagogical purposes and as an entry point for analysis of more sophisticated applications is suggested and discussed. B CAi C1 = fluid viscosity, gcm-1 s-1. = fluid density, gcm-3.