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The performance of a commercial Cu-zeolite SCR catalyst after differing degrees of hydrothermal aging (aged for 72 hours at 500, 700 and 800°C with 10% moisture balanced with air) was studied by spatially resolving different key reactions using gas-phase FTIR measurements. Gases were sampled along a channel at different positions and analyzed using FTIR, which overcomes the interference of water and nitrogen on ammonia concentration detection encountered in standard mass spectrometer-based spatial resolution measurements. The NO:NO₂ concentration ratio was changed so that the standard (NO:NO₂ = 1:0), fast (NO:NO₂ = 1:1) and NO₂ (NO:NO₂ = 0:1) SCR reactions could be investigated as a function of the catalyst's hydrothermal aging extent. In addition, the effects of hydrothermal aging on the activity of NH₃ and NO oxidation were also investigated. Hydrothermal aging had little effect on NO oxidation activity.

Ground damage is economically important to airlines, but it also represents a source of well-investigated human errors. This study of maintenance-related ground damage incidents at one airline showed a small number of consistent patterns of both the final ground damage events and the latent failures which contribute to these events. This analysis led directly to specific interventions which can be targeted at specific types of ground damage incidents. Beyond ground damage, the technique can be used to focus human factors interventions on other manifestations of error, such as operational incidents.

We consider the dynamical behavior of horizontal alignments of elastic grains placed within confining walls and placed under a constant acceleration that is applied at one end of the system. We show that these systems vibrate under such a compressive force. Certain universal properties of this vibration are mentioned. These systems may be useful in designing devices for filtering out mechanical noise.

Most environments inhabited by living beings have dust. Much of that dust comes from the continuous flaking of our own skin and atmosphere borne particles of submicron size. Dust mites seem to play an important role in integrating fine scale dust, which they consume to grow, resulting in larger length scale dust. Dust continues to agglomerate and grow. Air filters are designed to remove dust and control dust agglomeration. We report a simple scaling law, based on kinematic simulations of dust filtration through a one dimensional idealized filter. The results reveal insights regarding how filters may clog in time. Our results may be of use to someone interested in designing customized air filters for optimum dust removal in an environment with a known dust distribution.