An air-bearing weight offload system for ground test of heavy LSS structures

The capability and use of the Gravity Offload Facility (GOF) are discussed. Briefly explained are the: truss and base casting; carriage assembly; carriage weldment; vertical lift axis control; lifting cylinder; payload gimbal; motion base layout; and control processor

Development of a phase-change thermal storage system using modified anhydrous sodium hydroxide for solar electric power generation

A thermal storage system for use in solar power electricity generation was investigated analytically and experimentally. The thermal storage medium is principally anhydrous NaOH with 8% NaNO3 and 0.2% MnO2. Heat is charged into storage at 584 K and discharged from storage at 582 K by Therminol-66. Physical and thermophysical properties of the storage medium were measured. A mathematical simulation and computer program describing the operation of the system were developed. A 1/10 scale model of a system capable of storing and delivering 3.1 x 10 to the 6th power kJ of heat was designed, built, and tested. Tests included steady state charging, discharging, idling, and charge-discharge conditions simulating a solar daily cycle. Experimental data and computer-predicted results are correlated. A reference design including cost estimates of the full-size system was developed

Superconductivity generated by coupling to a Cooperon in a 2-dimensional array of 4-leg Hubbard ladders

Starting from an array of four-leg Hubbard ladders weakly doped away from half-filling and weakly coupled by inter-ladder tunneling, we derive an effective low energy model which contains a partially truncated Fermi surface and a well defined Cooperon excitation formed by a bound pair of holes. An attractive interaction in the Cooper channel is generated on the Fermi surface through virtual scattering into the Cooperon state. Although the model is derived in the weak coupling limit of a four-leg ladder array, an examination of exact results on finite clusters for the strong coupling t-J model suggests the essential features are also present for a strong coupling Hubbard model on a square lattice near half-filling.Comment: 20 pages, 4 figure

Laser-zone Growth in a Ribbon-to-ribbon (RTR) Process Silicon Sheet Growth Development for the Large Area Silicon Sheet Task of the Low Cost Solar Array Project

A technique for growing limited-length ribbons continually was demonstrated. This Rigid Edge technique can be used to recrystallize about 95% of the polyribbon feedstock. A major advantage of this method is that only a single, constant length silicon ribbon is handled throughout the entire process sequence; this may be accomplished using cassettes similar to those presently in use for processing Czochralski waters. Thus a transition from Cz to ribbon technology can be smoothly affected. The maximum size being considered, 3 inches x 24 inches, is half a square foot, and will generate 6 watts for 12% efficiency at 1 sun. Silicon dioxide has been demonstrated as an effective, practical diffusion barrier for use during the polyribbon formation

Cost reduction in bio-diesel production.

End of Project ReportAs part of a programme to assess bio-diesel production from low-cost materials, the availability of waste oils and fats in Ireland and the EU was assessed, and the behaviour of their esters in vehicles was measured. The utilisation of beef tallow from BSE risk organisms was given special attention. Esterification of high-FFA tallow required the use of excess methanol and base catalyst. Acidification, followed by glycerol separation and secondary acid-catalysed esterification, brought ester yields up to acceptable levels. The high melting point of the ester restricted its use in vehicles to low proportions in mixes with mineral diesel. Fuels made up from low-cost esters behaved well in vehicle trials, even where there was a high level of dilution of the engine oil. The only problems arose from inadequate low-temperature properties and from suspended solids in the tallow ester. Within the EU, there are sufficient waste oils and fats available to greatly increase bio-diesel production. In Ireland, there is sufficient for a small production unit

The use of air induction nozzles for herbicide application to sugar beet.

End of Project ReportTrials were carried out over a three-year period in Oak Park to compare airinduction with conventional nozzles for weed control in sugar beet. Two makes of low-drift nozzle (Bubble Jet and DriftBETA) were compared with conventional fans. All nozzles were used at a pressure of 3 bar. Two sizes (015 and 03) of each type of nozzle were used, to allow volumes of 110 and 220 litres per hectare to be applied. These nozzles were used to apply two-spray programmes to sugar-beet crops. In four of the weed control trials, tank mixes of products with some residual action (Progress, Goltix, Venzar and Debut) were used. In the other two trials, a contact-only spray (Betanal E) was used. The aim was to see how the nozzles behaved with contact-only sprays as well as those with more complex modes of action. Spray drift was also measured with the size 03 nozzles. Spray drift reductions from 37% to 64% were measured when the air-induction nozzles were compared with conventional fans. In general, the tank mix programme gave better weed control than the contact-only treatments. Within programmes, differences between the application methods were significant in two trials. In both of these, the conventional nozzles gave the best results. Looking at the mean results of the tank-mix trials, two trends were suggested: higher water volumes gave slightly better weed control, and the effect of the coarser sprays was slight. With the contact-only sprays, the decline in performance with the coarser sprays was more emphatic, and the lower volumes appeared to give slightly better control. It is concluded that in calm conditions conventional fan or cone nozzles should continue to be used, but that air-induction nozzles are a valuable fall-back when it is necessary to spray in a moderate breeze. In these situations, and with the normal tank-mix programmes, small nozzle sizes applying very low volumes should be avoided. Makes of air-induction nozzle which give very coarse spray should also be avoided

Video guidance, landing, and imaging systems

The adaptive potential of video guidance technology for earth orbital and interplanetary missions was explored. The application of video acquisition, pointing, tracking, and navigation technology was considered to three primary missions: planetary landing, earth resources satellite, and spacecraft rendezvous and docking. It was found that an imaging system can be mechanized to provide a spacecraft or satellite with a considerable amount of adaptability with respect to its environment. It also provides a level of autonomy essential to many future missions and enhances their data gathering ability. The feasibility of an autonomous video guidance system capable of observing a planetary surface during terminal descent and selecting the most acceptable landing site was successfully demonstrated in the laboratory. The techniques developed for acquisition, pointing, and tracking show promise for recognizing and tracking coastlines, rivers, and other constituents of interest. Routines were written and checked for rendezvous, docking, and station-keeping functions

Analysis of fatigue, fatique-crack propagation, and fracture data

Analytical methods have been developed for consolidation of fatigue, fatigue-crack propagation, and fracture data for use in design of metallic aerospace structural components. To evaluate these methods, a comprehensive file of data on 2024 and 7075 aluminums, Ti-6A1-4V, and 300M and D6Ac steels was established. Data were obtained from both published literature and unpublished reports furnished by aerospace companies. Fatigue and fatigue-crack-propagation analyses were restricted to information obtained from constant-amplitude load or strain cycling of specimens in air at room temperature. Fracture toughness data were from tests of center-cracked tension panels, part-through crack specimens, and compact-tension specimens

Local Section Meetings

n/