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Transmission of Sound in Ducts with Thin Shear Layers—Convergence to the Uniform Flow Case
The problem of the transmission of sound in a duct with very thin shear layers at the walls is treated by an inner expansion method. The results show that the formulation of the problem of the…
The entomofauna of the Lower Permian fossil insect beds of Kansas and Oklahoma, USA
When reviewing the holotype/neotype specimens used to describe the Wellington Formation species, it is found that 62% consist of fore wings, while 9% are complete specimens, indicating the importance of continued collecting and review of Wellington Formation insect fossils.
New Data on Homocladus grandis, A Permian Stem-Mantodean (Polyneoptera: Dictyoptera)
The range of morphological variation exhibited by the new material, in addition to wing morphology variability documented in extant mantises and roaches, suggest that H. grandis is a strephocladid species that exhibits a combination of character states unique to dictyopteran insects.
A Second Specimen of Permocoleus (Coleoptera) from the Lower Permian Wellington Formation of Noble County, Oklahoma
A second specimen from another locality in those same beds, comprised of the part and counterpart of a fragment of an elytron, is figured and discussed here and appears to represent the same species, Permocoleus wellingtonensis Lubkin and Engel.
Impedance measurements of acoustic duct liners with grazing flow
The impedance properties of acoustic duct liners are affected by airflow in the duct. Measurements have shown that interactions between the duct flow and the acoustically induced flow at and within…
Bandwidth Attenuation with a Folded Cavity Liner in a Circular Flow Duct
An extended reaction analysis is presented for investigating the bandwidth attenuation characteristics of a folded cavity resonator lining in a circular flow duct. An eigenfunction expansion…
A method of weighted residuals for the investigation of sound transmission in non-uniform ducts without flow
Optimization of duct acoustic liners of finite length
Lining design procedures generally ignore the effects of discontinuous impedance changes on reflection and modal redistribution of incident energy. The present study, spurred by preliminary work of…
A New Species of †Martynovia1, Tillyard, 1932 (Insecta: †Diaphanopterodea: †Martynoviidae) from the Lower Permian Wellington Formation of Noble County, Oklahoma
- R. Beckemeyer
- 1 April 2004
A new species of the fossil genus †Martynovia, new species, most closely resembles the Elmo (Dickinson County), Kansas species, from which it is differentiated by wing shape and venational characters.