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  • Author or Editor: P. Pagès x
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Abstract  

The gamma-ray spectrum analysis program, GAMANAL, has been modifed to operate on a microcomputer. The program uses an algorithm involving a Gaussian and a tailing term for fitting and resolving peaks obtained from spectrometers using germanium semiconductor detectors. Gamma-ray energies, intensities and absolute photon emission rates can be determined. A graphical output showing the original and fitted data can also be obtained. The results generated by the program are stored on disk as ASCII files for futher analysis. This allows the use of other computer programs and languages in tasks such as decay curve analysis, radionuclide activity measurements and neutron activation analysis.

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Abstract  

The increasing trend towards the use of fine oil filtration in modern jet engines suggests that the Spectrometric Oil Analysis Program (SOAP), which routinely monitors the health of aeroengines, may no longer be effective in detecting abnormal wear trends. Since the oil filter contains a wealth of information on wear in a system, it may be necessary to perform engine health monitoring through Filter Debris Analysis (FDA). In the present study, a method was developed for the determination of 19 wear elements (Ag, Al, Au, Cd, Co, Cr, Cu, In, Fe, Mg, Mn, Mo, Ni, Sb, Sn, Ti, V, W and Zn) in aircraft engine oil filter debris samples using the analytical technique of Neutron Activation Analysis (NAA). Results obtained by NAA for the analysis of two types of filter debris samples compared well with results obtained previously for similar samples and it appears that FDA should be very useful for following wear trends.

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Abstract  

Used lubricating oil analysis programs are currently employed by both the military and industry in an attempt to minimize some of the costs associated with equipment failure. The periodic determination of water elements in the lubricant of an oil-wetted system can provide very useful information on the condition or health of the system and an early indication of impending failure. In the present study, the application of Neutron Activation Analysis (NAA) to used oil analysis was investigated. The method developed allowed for the determination of fifteen elements (Ag, Al, Cl, Cr, Cu, Fe, In, Mg, Mn, Mo, Na, Ni, Sn, Ti and Zn) associated with engine wear or deterioration. Results obtained for the analysis of used naval diesel oils exhibited good agreement with results obtained by Atomic Absorption Spectrophotometry (AAS) methods. A drawback of the NAA procedure is that the determination of Fe, a major wear element in most systems, involves an analysis time of approximately one week.

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Abstract  

A new utility program for processing data in neutron activation analysis (NAA) has been developed for use on MS-DOS microcomputers. Peak areas are read from ASCII data files of gamma-ray spectra which have been processed by a Gaussian peak fitting program, GAMANAL-PC. Elemental concentrations are then calculated by this new program, QUACANAL, via a semi-absolute algorithm that uses pre-determined activation constants. User-defined ASCII library files are employed to specify the elements of interest required for analysis, and (n, p) and (n, ) interferences are taken into account. The program has been written in turbo PASCAL, is menu driven and contains options for processing data from cyclic NAA. An interactive philosophy has been used in designing the program.

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Abstract  

This paper describes the results of photoreduction of uranyl (UO2 2+) ion to U4+ in 0.2M HNO3 and ethanol using a 308 nm XeCl excimer laser. The effects of different concentrations of ethanol and the addition of sulfamic acid on the quantum yield for U4+ formation are discussed.

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Abstract  

A crystallization kinetics analysis of several polypropylene-polyethylene (PP-PE), PP-rich copolymers was made by means of differential scanning calorimetry. The crystallization was studied via calorimetric measurements at different cooling rates. Several additives were added to the base material. Some test samples were subjected to artificial ageing processes. A modified isoconversional method was used to describe the crystallization process under non-isothermal conditions. The value of the Avrami parameter was determined for primary and secondary crystallization.

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