RESUMO
A neutron depth profiling (NDP) device was developed on China advanced research reactor (CARR) of China Institute of Atomic Energy (CIAE). The CARR-NDP device uses cold neutron beams transmitted by a neutron guide from the cold neutron source of CARR, and it is composed of a neutron beam collimator, and a vacuum target chamber containing a beam stopper and a detection system. The neutron flux at 1â¯m from the end of neutron guide is about 4.8â¯×â¯108 n cm-2 s-1 under operating power of 15â¯MW. A standard reference material SRM-2137 sample and a multilayer film sample were utilized to verify the performances of the CARR-NDP device.
RESUMO
Sampling behavior of multielements in a stream sediment matrix was studied with sample sizes in a range of 9 orders of magnitude by a combination of INAA, PIXE and SR-XRF. For accurately weighable sample sizes (>1mg), sampling uncertainties for 16 elements are better than 1% by INAA. For sample sizes that cannot be accurately weighed (<1mg), PIXE and SR-XRF were used and the effective sample sizes were estimated. Sampling uncertainties for seven elements are better than 1% at sample sizes of tenth mg level, and that for three elements are better than 10% on ng levels.
RESUMO
The instantaneous wear rates for both the top compression piston-ring and the cylinder-bore, in a ZS1105 diesel engine, were measured in situ using the method of thin layer activation (TLA). The experimental arrangement and methods for calibrating the test specimens are described. During a 300 s counting interval, the minimum detectable wear depths for the cylinder-bore and piston-ring were 9 and 75 nm, respectively. These values reflect average recession depths and may not reflect localized differences in wear damage. Nevertheless, such in situ techniques can be usefully employed in engine development.
