Optimized bolted joint

A method is disclosed for joining segments of the skin of an aircraft. The ends of the skin are positioned in close proximity or abutt each other. The skin is of constant thickness throughout the joint and is sandwiched between splice plates, which taper in thickness from the last to the first bolt rows in order to reduce the stiffness of the splice plate and thereby reduce the load transfer at the location where bypass loads are the highest

Amplitude squeezed light from a laser

Intensity squeezed light was successfully generated using semiconductor lasers with sub-Poissonian pumping. Control of the pumping statistics is crucial and is achieved by a large series resistor which regulates the pump current; its sub-Poissonian statistics are then transferred to the laser output. The sub-Poissonian pumping of other laser systems is not so simple, however, and their potential as squeezed states sources is apparently diminished. We consider a conventional laser incoherently pumped well above threshold, and allow for pump depletion of the ground state. In this regime, sub-Poissonian photon statistics and squeezed amplitude fluctuations are produced

Adjoint error estimation and spatial adaptivity for EHL-like models

The use of adjoint error estimation techniques is described for a model problem that is a simplified version of an EHL line contact. Quantities of interest, such as friction, may be dependent upon the accuracy of the Solution in some parts of the domain more than in others. The use of an inexpensive extra solve to calculate an adjoint solution is described for estimating the intergrid error in the value of friction calculated, and as a basis for local refinement. It is demonstrated that this enables an accurate estimate for the quantity of interest to be obtained from a less accurate solution of the model problem

Critical joints in large composite aircraft structure

A program was conducted at Douglas Aircraft Company to develop the technology for critical structural joints of composite wing structure that meets design requirements for a 1990 commercial transport aircraft. The prime objective of the program was to demonstrate the ability to reliably predict the strength of large bolted composite joints. Ancillary testing of 180 specimens generated data on strength and load-deflection characteristics which provided input to the joint analysis. Load-sharing between fasteners in multirow bolted joints was computed by the nonlinear analysis program A4EJ. This program was used to predict strengths of 20 additional large subcomponents representing strips from a wing root chordwise splice. In most cases, the predictions were accurate to within a few percent of the test results. In some cases, the observed mode of failure was different than anticipated. The highlight of the subcomponent testing was the consistent ability to achieve gross-section failure strains close to 0.005. That represents a considerable improvement over the state of the art

A high-throughput ab initio review of platinum-group alloy systems

We report a comprehensive study of the binary systems of the platinum group metals with the transition metals, using high-throughput first-principles calculations. These computations predict stability of new compounds in 38 binary systems where no compounds have been reported in the literature experimentally, and a few dozen of as yet unreported compounds in additional systems. Our calculations also identify stable structures at compound compositions that have been previously reported without detailed structural data and indicate that some experimentally reported compounds may actually be unstable at low temperatures. With these results we construct enhanced structure maps for the binary alloys of platinum group metals. These are much more complete, systematic and predictive than those based on empirical results alone.Comment: 24 pages, 12 figure

Attempts to Locate Culex Tarsalis Larvae In Traditional Mosquito - Breeding Habitats from Brookings County, South Dakota

A total of 33 potential mosquito breeding sites were identified and selected during the early spring of 2003. These mosquito habitats were selected from both natural and urban settings within Brookings County, Sd, and represented the various classifications of habitats potentially used by various mosquito species for larval development including: flowing streams, ponded streams, lake edges, swamps and marshes, shallow-permanent ponds, shallow-temporary pools, intermittent- ephemeral puddles, natural containers and artificial containers. These sites were monitored weekly during the summer for the condition of the water and sampled for the presence of mosquito larvae. A standard collection of 10 “dips” using a 13 cm mosquito dipper was made from each location. Collected larvae were preserved (70% ethanol), dehydrated in an ethanol series, mounted on glass slides, identified and enumerated. Focus was given to Culex larvae because Culex tarsalis is a primary vector for West Nile Virus in South Dakota. Moderate numbers of larvae were recovered from many of the sites during the summer, but by August 6 only 21 of the sites contained water, and therefore, still able to support larval development. Culex tarsalis larvae were not found in any natural site; the only sites they where they could be found were 6 artificial containers possessing these larvae only after August 5. Culex tarsalis larvae were found in 2 locations that were not part of the original study sites. These included larvae found during early summer in an artificial barrel mesocosm within Oak Lake, and larvae found in a water-filled, shallow tire-imprint located in a hayfield in Minnehaha County, South Dakota

Impact of Recent Tax Stimulants on Modest Enterprises

The recession year 1958 found Congress in a mood to aid and encourage small business through more favorable tax treatment. The thrust of the ensuing legislation touched in varying degrees the whole life span of a modest enterprise, from organization through liquidation. The focus here, however, will be confined to a consideration of the practical impact of the recent statutory changes on the organizational and ordinary operational phases of such a business

Impact of Diet and Quality Grade on Shelf Life of Beef Steaks

Steers were fed a diet containing dry rolled corn, steam flaked corn, dry rolled corn with 30% dried distillers grains, or steam flaked corn with 30% dried distillers grains. Strip loins from upper 2/3 Choice and Select- grade carcasses were obtained to evaluate the effects of diet and quality grade on shelf life characteristics. Strip loins were aged for 2, 9, 16, or 23 days. Results suggest that steaks from cattle fed steam flaked corn (with or without dried distillers grains) and from cattle fed dried distillers grains (regardless of corn type) had higher levels of many unsaturated fatty acids, more discoloration, and greater lipid oxidation compared to the dry rolled corn treatments or the no dried distillers grains treatments, respectively. Feeding of dry rolled corn or diets without dried distillers grains maintained red color better during retail display. Choice- grade steaks had significantly higher levels of unsaturated fatty acids like 18:2 and total polyunsaturated fatty acids than Select- grade steaks but did not diff er in color stability or oxidation. These data indicate the longest shelf life will occur when cattle are fed diets containing dry rolled corn (versus steam flaked corn) or without dried distillers grains (versus with dried distillers grains) and that both steam flaked corn and distillers grains have a negative impact on shelf life. Quality grade did not affect color stability