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The Brock version of the Split-Step Fast Fourier Transform (SSFFT) and the Jeager version of the Implicit Finite Difference (IFD) acoustic parabolic equation models are compared with a Lloyd mirror interference pattern in the range domain. The SSFFT displays the inability to place the transmission loss nulls at the correct ranges. It is also unable to utilize bottom loss information correctly. The IFD produced nulls at the correct ranges; however, it inserted an unacceptable amount of noise except when small {1 m) vertical grid steps were used and the pressure release bottom was placed at extended depths. In shallow water cases, the IFD is able to properly represent the pressure information. Each model is explored in the wavenumter domain by use of a "Waver.u mber Technique" (WT) model with emphasis on source depth determination. The source depth may be deterained by measuring the distance between the equally spaced nulls in the wavenumber representation. Neither acoustic model was able to provide accurate source depth information when the null spacings were compared to a known source-depth determination carve. Since the null spacings were not uniformly spaced, this was tc be expected. Some specific problem areas in the models were identified by the use of the WT., http://archive.org/details/acomparisonoftwo1094519200, Lieutenant, United States Navy, Approved for public release; distribution is unlimited.

With Peter Golata, Joe Zelson, John Lane, Dawn Payne, Tim Nutter, and Tim Enright., Series XLII, Number 14A., This archival material has been provided for educational purposes. Ball State University Libraries recognizes that some historic items may include offensive content. Our statement regarding objectionable content is available at: https://dmr.bsu.edu/digital/about

With Peter Golata, Joe Zelson, John Lane, and Cory Porter., Series XLII, Number 68C., This archival material has been provided for educational purposes. Ball State University Libraries recognizes that some historic items may include offensive content. Our statement regarding objectionable content is available at: https://dmr.bsu.edu/digital/about

The Brock version of the Split-Step Fast Fourier Transform (SSFFT) and the Jeager version of the Implicit Finite Difference (IFD) acoustic parabolic equation models are compared with a Lloyd mirror interference pattern in the range domain. The SSFFT displays the inability to place the transmission loss nulls at the correct ranges. It is also unable to utilize bottom loss information correctly. The IFD produced nulls at the correct ranges; however, it inserted an unacceptable amount of noise except when small {1 m) vertical grid steps were used and the pressure release bottom was placed at extended depths. In shallow water cases, the IFD is able to properly represent the pressure information. Each model is explored in the wavenumter domain by use of a "Waver.u mber Technique" (WT) model with emphasis on source depth determination. The source depth may be deterained by measuring the distance between the equally spaced nulls in the wavenumber representation. Neither acoustic model was able to provide accurate source depth information when the null spacings were compared to a known source-depth determination carve. Since the null spacings were not uniformly spaced, this was tc be expected. Some specific problem areas in the models were identified by the use of the WT.

With Peter Golata, Joe Zelson, John Lane, and Cory Porter., Series XLII, Number 68C., This archival material has been provided for educational purposes. Ball State University Libraries recognizes that some historic items may include offensive content. Our statement regarding objectionable content is available at: https://dmr.bsu.edu/digital/about

With Peter Golata, Joe Zelson, John Lane, Dawn Payne, Tim Nutter, and Tim Enright., Series XLII, Number 14A., This archival material has been provided for educational purposes. Ball State University Libraries recognizes that some historic items may include offensive content. Our statement regarding objectionable content is available at: https://dmr.bsu.edu/digital/about

The objects which surround us in our everyday existence form a part of humanity's universal experience and are just as relevant to us as corresponding objects were to our ancestors. The object that I have chosen to render is a chair, defined by both a strong, directional light and its containment in the corner of a room. I have rendered it in a Paynes gray wash, using watercolor as my medium. The chair and its shadow are clearly defined objects in an otherwise unoccupied space and seem to maintain an isolated existence of their own. Previous artists such as Rembrandt, Goya, Van Gogh and Cezanne have concerned themselves with the representation of objects, and evolved a symbolism for the still life which went beneath the surface of the objects represented. In the manner of these artists, Georgio de Chirico also explored the metaphysical nature of objects. "The Sacred Fish" illustrates this through the use of precisely defined textural surfaces, tilted planes, extensive shadows and architectural space used like a stage setting.