Specification for limits of surface imperfections on elastomeric toroidal sealing rings ('O'-rings)

abstract A perturbation method for treating the scattering of plane waves by small surface imperfections on an elastic half space is presented. The solution to the first order approximation is given as convolution integrals of the surface imperfection with kernel functions defined by Fourier inversion integrals. The evaluation of these integrals is discussed and their asymptotic representations determined. The far field scattered displacements are explicitly obtained for arbitrary imperfections. The scattered field consists of a Rayleigh surface wave and four body phases which at the free surface travel with the speed of dilational or distortional waves. Numerical examples are given. In particular the error in the apparent angle of emergence due to the scattered waves is obtained. The body phases exhibit the familiar 3/2 geometric attenuation, but still may make a significant contribution at moderately long distances. A strong dependence of the magnitude of the error on the angle of incidence is demonstrated.

Download Full-text

Postpackage Pasteurization of Ready-to-Eat Deli Meats by Submersion Heating for Reduction of Listeria monocytogenes†

Journal of Food Protection ◽

10.4315/0362-028x-65.6.963 ◽

2002 ◽

Vol 65 (6) ◽

pp. 963-969 ◽

Cited By ~ 61

Author(s):

P. M. MURIANA ◽

W. QUIMBY ◽

C. A. DAVIDSON ◽

J. GROOMS

Keyword(s):

Listeria Monocytogenes ◽

Meat Products ◽

Current Data ◽

Surface Phenomena ◽

Surface Areas ◽

Surface Imperfections ◽

Product Surface ◽

Roast Beef ◽

Z Value ◽

High Level

A mixed cocktail of four strains of Listeria monocytogenes was resuspended in product purge and added to a variety of ready-to-eat (RTE) meat products, including turkey, ham, and roast beef. All products were vacuum sealed in shrink-wrap packaging bags, massaged to ensure inoculum distribution, and processed by submersion heating in a precision-controlled steam-injected water bath. Products were run in pairs at various time-temperature combinations in either duplicate or triplicate replications. On various L. monocytogenes–inoculated RTE deli meats, we were able to achieve 2- to 4-log cycle reductions when processed at 195°F (90.6°C), 200°F (93.3°C), or 205°F (96.1°C) when heated from 2 to 10 min. High-level inoculation with L. monocytogenes (~107 CFU/ml) ensured that cells infiltrated the least processed surface areas, such as surface cuts, folds, grooves, and skin. D- and z-value determinations were made for the Listeria cocktail resuspended in product purge of each of the three meat categories. However, reduction of L. monocytogenes in product challenge studies showed much less reduction than was observed during the decimal reduction assays and was attributed to a combination of surface phenomena, including surface imperfections, that may shield bacteria from the heat and the migration of chilled purge to the product surface. The current data indicate that minimal heating regimens of 2 min at 195 to 205°F can readily provide 2-log reductions in most RTE deli meats we processed and suggest that this process may be an effective microbial intervention against L. monocytogenes on RTE deli-style meats.

Download Full-text

Investigation of Surface Imperfections by Diffuse Scattering of He Atoms

Springer Series in Surface Sciences - Helium Atom Scattering from Surfaces ◽

10.1007/978-3-662-02774-5_5 ◽

1992 ◽

pp. 73-93 ◽

Cited By ~ 2

Author(s):

Ch. Wöll ◽

A. M. Lahee

Keyword(s):

Diffuse Scattering ◽

Surface Imperfections

Download Full-text

Receptivity to Surface Imperfections

IUTAM Laminar-Turbulent Transition - IUTAM Bookseries ◽

10.1007/978-3-030-67902-6_65 ◽

2021 ◽

pp. 749-755

Author(s):

Michael Gaster

Keyword(s):

Surface Imperfections

Download Full-text

The anomalous skin effect

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1952.0226 ◽

1952 ◽

Vol 215 (1123) ◽

pp. 481-497 ◽

Cited By ~ 226

Keyword(s):

Free Path ◽

Low Temperatures ◽

Skin Effect ◽

Mean Free Path ◽

Skin Depth ◽

Surface Conductance ◽

High Frequencies ◽

Surface Imperfections ◽

Anomalous Skin Effect ◽

Cadmium Lead

The anomalous skin effect arises in good conductors at low temperatures and high frequencies when the electronic mean free path becomes comparable with or greater than the classically calculated skin depth. Measurements have been made on a number of metals at frequencies of 1200 and 3600 Mc/s, and the form of variation of r. f. surface conductance with d. c. conductivity agrees well with that predicted theoretically by Reuter & Sondheimer, assuming that the electrons are scattered diffusely when they hit the surface of the metal. From the results, estimates are made of the effective value of σ/ l , the ratio of d. c. conductivity to mean free path, and hence of the free surface area of the occupied region of k -space. The estimate for copper agrees well with that expected theoretically; those for silver and gold are rather lower than the theoretical values. For the other metals investigated, tin, cadmium, lead and aluminium, no theoretical estimates are available. The results are very sensitive to the presence of surface imperfections; the effect of these is discussed.

Download Full-text

The Effect of Boundary Condition Variations on the Rolling Resistance of a Hard Sphere on Rubber Sheets

International Journal of Applied Mechanics ◽

10.1142/s1758825119500431 ◽

2019 ◽

Vol 11 (05) ◽

pp. 1950043 ◽

Cited By ~ 2

Author(s):

Gérard-Philippe Zéhil ◽

Henri P. Gavin

Keyword(s):

Measurement Errors ◽

Hard Sphere ◽

Rolling Resistance ◽

Interesting Case ◽

Analytical Models ◽

Surface Imperfections ◽

Experimental Apparatus ◽

Isolation Systems ◽

Steel Balls ◽

Resistance Forces

This paper makes an interesting case for the need to consider mechanistic variations in rolling resistance forces due to noncoplanar surfaces and surface roughness. An experimental apparatus is designed to measure rolling resistance in the practically imperfect conditions of lightly-damped rolling isolation systems. These conditions include support compliance, surface imperfections and material inhomogeneities under relatively large loads. Rolling resistance experiments are conducted on steel balls between rubber sheets. Suitable mechanistic interpretations are provided for principal sources of variability. It is shown that measurement errors can be significant and that experimental results should be considered with caution. Suitable approaches for interpreting the results are then proposed and applied to this aim. Useful analytical models are fitted successfully to the processed data.

Download Full-text