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961.
W. A. Harper P. A. Beeley L. G. I. Bennett J. A. Page 《Journal of Radioanalytical and Nuclear Chemistry》1989,132(2):369-376
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. 相似文献
962.
G. B. Bennett A. D. Kahle H. Minor M. J. Shapiro 《Journal of heterocyclic chemistry》1979,16(7):1389-1392
The substituent chemical shifts of a series of para substituted-3-phenyl-as-triazine 4-oxides were studied using the Swain-Lupton F and R values. This data was compared to that obtained for parasubstituted biphenyls, phenyl pyrroles and phenyl furans. It was found that the substituent chemical shifts in the triazines behaved in a similar manner to that in the biphenyl system. 相似文献
963.
964.
Fred E. Tibbetts Maurice M. Bursey William F. Little Bennett R. Willeford Steven A. Benezra Michael K. Hoffman Paul W. Jennings 《Journal of mass spectrometry : JMS》1972,6(5):475-478
Peaks of different intensities in the mass spectra of π-toluenetricarbonylchromium and π-cycloheptatrienetricarbonylchromium were studied by deuterium labeling of the latter compound. Incomplete hydrogen randomization in cycloheptatriene ligands preceding different reactions was observed, in contrast to the results for cycloheptatriene itself. 相似文献
965.
Motion of a driven and heavily damped sine-Gordon chain with a low density of kinks and tight coupling between particles is controlled by the nucleation and subsequent annihilation of pairs of kinks and antikinks. We show that in the steady state there are no spatial correlations between kinks or between kinks and antikinks. For a given number of kinks and antikinks all geometrical distributions are equally alike, as in equilibrium. A master equation for the probability distribution for the number of kinks on a finite chain is solved, and substantiates the physical reasoning in previous work. The probability distribution characterizing the spread along the direction of particle motion of a finite chain in equilibrium as well as in the driven overdamped case is derived by simple combinatorial considerations. The spatial spread of a driven chain in the thermodynamic limit does not approach a steady state; a given particle followed in time deviates as t1/2 from its average forced motion. This result follows from the hydrodynamic equations for the dilute kink gas. Comparison is made with other recent results. 相似文献
966.
967.
Holey fibers with random cladding distributions 总被引:14,自引:0,他引:14
We provide what is to our knowledge the first direct confirmation that light can be guided in a holey fiber with randomly distributed air holes in the cladding. We also show that many of the features previously attributed to periodic holey fibers, in particular, single-mode guidance at all wavelengths, can also be obtained with random holey fibers. We provide insight into exactly how sensitive a holey fiber's optical properties are to the details of the cladding profile. 相似文献
968.
Quantifying DNA damage by gel electrophoresis, electronic imaging and number-average length analysis
DNA damages that can be converted to single- or double strand breaks can be quantified by separating DNA by gel electrophoresis and obtaining a quantitative image of the resulting distribution of DNA in the gel. We review the theory of this method and discuss its implementation, including the charge-coupled device (CCD) camera systems we developed to acquire images of fluorophore labeled DNA. 相似文献
969.
970.
In this paper, a new approach to the CalabiBernsteintheorem on maximal surfaces in the LorentzMinkowski spaceL3 is introduced. The approach is based on an upper bound forthe total curvature of geodesic discs in a maximal surface inL3, involving the local geometry of the surface and its hyperbolicimage. As an application of this, a new proof of the CalabiBernsteintheorem is provided. 相似文献