A comparison of 3 optical systems for the detection of broadband ultrasound

There are many applications of ultrasound in the field of material properties' evaluation and structural health monitoring. Here we will consider the detection of broadband laser generated ultrasound taking as an example acoustic emission as simulated by the pencil break test. In this paper three optical methods of detecting these ultrasound signals are compared; these are polarimetry, fibre Bragg gratings and vibrometery. Of these, the first two involve the bonding of a fibre sensor to the sample, whilst the vibrometer is a non-contact instrument that measures out-of-plane displacements. FBGs respond to the inplane strains associated with an ultrasound wave whilst the polarimeter detects birefringence produced by pressure waves acting normal to the fibre. The sensitivities of the systems are compared and their relative merits are discussed. It will also be shown that the polarimetric responses of symmetric and antisymmetric Lamb waves differ, which opens up the possibility of learning more about the nature of an acoustic signal using this technique than can be determined simply from the measurement of in-plane or out-of plane displacements alone

Turbopump thermodynamic cooling

System for cooling turbopumps used in cryogenic fluid storage facilities is described. Technique uses thermodynamic propellant vent to intercept pump heat at desired conditions. Cooling system uses hydrogen from outside source or residual hydrogen from cryogenic storage tank

Southern California fisheries monitoring summary for 1993 and 1994

The southern California Monitoring and Management Units collectively gathered 803 discrete samples of 7,329 marine finfishes and invertebrates from local commercial fish markets or authorized fish transporters in 1993. Nineteen different species were sampled and biological information recorded for future summarization and use in formulating fisheries management strategies and decisions. Increased sampling efforts in 1994 resulted in 801 samples of 14,566 marine finfish and invertebrates representing 44 different species. Fisheries trends and threats to local fishing opportunities were identified. Results of Marine Recreational Fishery Statistics Survey interviews were also incorporated for a more complete overview of species targeted by both the sport and commercial industries. (26pp.

A laboratory investigation of the variability of cloud reflected radiance fields

A method to determine the radiative properties of complex cloud fields was developed. A Cloud field optical simulator (CFOS) was constructed to simulate the interaction of cloud fields with visible radiation. The CFOS was verified by comparing experimental results from it with calculations performed with a Monte Carlo radiative transfer model. A software library was developed to process, reduce, and display CFOS data. The CFSOS was utilized to study the reflected radiane patterns from simulated cloud fields

The leafage of a chordal graph

The leafage l(G) of a chordal graph G is the minimum number of leaves of a tree in which G has an intersection representation by subtrees. We obtain upper and lower bounds on l(G) and compute it on special classes. The maximum of l(G) on n-vertex graphs is n - lg n - (1/2) lg lg n + O(1). The proper leafage l*(G) is the minimum number of leaves when no subtree may contain another; we obtain upper and lower bounds on l*(G). Leafage equals proper leafage on claw-free chordal graphs. We use asteroidal sets and structural properties of chordal graphs.Comment: 19 pages, 3 figure

Letter from Robert B. McKee to Senator Langer Regarding List of Residents, October 4, 1956

This letter, dated October 4, 1956, from [illegible] on behalf of Fort Berthold Agency Superintendent Robert B. McKee to United States (US) Senator William Langer informs Langer that the list Langer requested in his letter of September 26, 1956--of the names and addresses of residents of the Fort Berthold Reservation over 21 years of age--will be sent within the next few days. See also: An Act to Provide for the Segregation of Certain Funds of the Fort Berthold Indians on the Basis of Membership Roll Prepared for Such Purposehttps://commons.und.edu/langer-papers/1749/thumbnail.jp

The relationship between church health and church growth in the Evangelical Presbyterian Church

https://place.asburyseminary.edu/ecommonsatsdissertations/1185/thumbnail.jp

Porous squeeze-film flow

The squeeze-film flow of a thin layer of Newtonian fluid filling the gap between a flat impermeable surface moving under a prescribed constant load and a flat thin porous bed coating a stationary flat impermeable surface is considered. Unlike in the classical case of an impermeable bed, in which an infinite time is required for the two surfaces to touch, for a porous bed contact occurs in a finite contact time. Using a lubrication approximation an implicit expression for the fluid layer thickness and an explicit expression for the contact time are obtained and analysed. In addition, the fluid particle paths are calculated, and the penetration depths of fluid particles into the porous bed are determined. In particular, the behaviour in the asymptotic limit of small permeability, in which the contact time is large but finite, is investigated. Finally, the results are interpreted in the context of lubrication in the human knee joint, and some conclusions are drawn about the contact time of the cartilage-coated femoral condyles and tibial plateau and the penetration of nutrients into the cartilage