515 research outputs found
Factors affecting cleanup of exhaust gases from a pressurized, fluidized-bed coal combustor
The cleanup of effluent gases from the fluidized-bed combustion of coal is examined. Testing conditions include the type and feed rate of the coal and the sulfur sorbent, the coal-sorbent ratio, the coal-combustion air ratio, the depth of the reactor fluidizing bed, and the technique used to physically remove fly ash from the reactor effluent gases. Tests reveal that the particulate loading matter in the effluent gases is a function not only of the reactor-bed surface gas velocity, but also of the type of coal being burnt and the time the bed is operating. At least 95 percent of the fly ash particules in the effluent gas are removed by using a gas-solids separator under controlled operating conditions. Gaseous pollutants in the effluent (nitrogen and sulfur oxides) are held within the proposed Federal limits by controlling the reactor operating conditions and the type and quantity of sorbent material
Lewis Research Center's coal-fired, pressurized, fluidized-bed reactor test facility
A 200-kilowatt-thermal, pressurized, fluidized-bed (PFB) reactor, research test facility was designed, constructed, and operated as part of a NASA-funded project to assess and evaluate the effect of PFB hot-gas effluent on aircraft turbine engine materials that might have applications in stationary-power-plant turbogenerators. Some of the techniques and components developed for this PFB system are described. One of the more important items was the development of a two-in-one, gas-solids separator that removed 95+ percent of the solids in 1600 F to 1900 F gases. Another was a coal and sorbent feed and mixing system for injecting the fuel into the pressurized combustor. Also important were the controls and data-acquisition systems that enabled one person to operate the entire facility. The solid, liquid, and gas sub-systems all had problems that were solved over the 2-year operating time of the facility, which culminated in a 400-hour, hot-gas, turbine test
Continuous Human Activity Recognition using a MIMO Radar for Transitional Motion Analysis
The prompt and accurate recognition of Continuous Human Activity (CHAR) is
critical in identifying and responding to health events, particularly fall risk
assessment. In this paper, we examine a multi-antenna radar system that can
process radar data returns for multiple individuals in an indoor setting,
enabling CHAR for multiple subjects. This requires combining spatial and
temporal signal processing techniques through micro-Doppler (MD) analysis and
high-resolution receive beamforming. We employ delay and sum beamforming to
capture MD signatures at three different directions of observation. As MD
images may contain multiple activities, we segment the three MD signatures
using an STA/LTA algorithm. MD segmentation ensures that each MD segment
represents a single human motion activity. Finally, the segmented MD image is
resized and processed through a convolutional neural network (CNN) to classify
motion against each MD segment
Milliarcsecond structure and variability of methanol maser emission in three high-mass protostars
{The variability study of 6.7\,GHz methanol masers has become a useful way to
improve our understanding of the physical conditions in high-mass star-forming
regions.} {Based on the single-dish monitoring using the Irbene telescopes, we
selected three sources with close sky positions.} {We imaged them using the
European Very Long Baseline Interferometer Network and searched available data
on VLBI archives to follow detailed changes in their structures and single
maser spot variability.} {All three targets show a few groups of maser
cloudlets of a typical size of 3.5\,mas and the majority of them show linear or
arched structures with velocity gradients of order 0.22\kms\,mas. The
cloudlets and overall source morphologies are remarkably stable on time scales
of 7-15\,yr supporting a scenario of variability due to changes in the maser
pumping rate.}Comment: 20 page
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