10,346 research outputs found
Experimental study of cross flow mixing in cylindrical and rectangular ducts
An experimental investigation of non-reacting cross flow jet injection and mixing in cylindrical and rectangular ducts has been conducted with application to a low emissions combustor. Quantitative measurement of injectant concentration distributions perpendicular to the duct axis were obtained by planar digital imaging of the Mie-scattered light from an aerosol seed mixed with the injectant. The flowfield unmixedness was evaluated using (1) a mixing parameter derived from the ratio of the jet concentration fluctuations to the fully mixed concentration, and (2) probability density functions of the concentration distributions. Mixing rate was measured for 45 degree slant slot and round orifice injectors
Bach speaks: A cortical "language-network" serves the processing of music
The aim of the present study was the investigation of neural correlates of music processing with fMRI. Chord sequences were presented to the participants, infrequently containing unexpected musical events. These events activated the areas of Broca and Wernicke, the superior temporal sulcus, Heschl's gyrus, both planum polare and planum temporale, as well as the anterior superior insular cortices. Some of these brain structures have previously been shown to be involved in music processing, but the cortical network comprising all these structures has up to now been thought to be domain-specific for language processing. To what extent this network might also be activated by the processing of non-linguistic information has remained unknown. The present fMRI-data reveal that the human brain employs this neuronal network also for the processing of musical information, suggesting that the cortical network known to support language processing is less domain-specific than previously believed
Random and externally controlled occurrences of Dansgaard-Oeschger events
Dansgaard–Oeschger (DO) events constitute the most pronounced mode of
centennial to millennial climate variability of the last glacial period.
Since their discovery, many decades of research have been devoted to
understand the origin and nature of these rapid climate shifts. In recent
years, a number of studies have appeared that report emergence of DO-type
variability in fully coupled general circulation models via different
mechanisms. These mechanisms result in the occurrence of DO events at varying
degrees of regularity, ranging from periodic to random. When examining the
full sequence of DO events as captured in the North Greenland Ice Core
Project (NGRIP) ice core record, one can observe high irregularity in the
timing of individual events at any stage within the last glacial period. In
addition to the prevailing irregularity, certain properties of the DO event
sequence, such as the average event frequency or the relative distribution of
cold versus warm periods, appear to be changing throughout the glacial. By
using statistical hypothesis tests on simple event models, we investigate
whether the observed event sequence may have been generated by stationary
random processes or rather was strongly modulated by external factors. We
find that the sequence of DO warming events is consistent with a stationary
random process, whereas dividing the event sequence into warming and cooling
events leads to inconsistency with two independent event processes. As we
include external forcing, we find a particularly good fit to the observed DO
sequence in a model where the average residence time in warm periods are
controlled by global ice volume and cold periods by boreal summer insolation
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