9,646 research outputs found
Classification Characteristics of Carbon Nanotube Polymer Composite Chemical Vapor Detectors
The first step in combating a chemical weapons threat is contamination avoidance. This is accomplished by the detection and identification of chemical agents. The Air Force has several instruments to detect chemical vapors, but is always looking for lighter, faster, and more accurate technology for a better capability. This research is focused on using carbon nanotube polymer composite sensors for chemical detection. More specifically, models are developed to classify three sets of sensor data according to vapor using various multivariate techniques. Also, prediction models of a mixed sensor output are developed using neural networks and regression analysis. The classifiers developed are able to accurately classify three vapors for a specific set of data, but have problems when tested against data from aged sensors as well as data generated from a different set of new sensors. These results indicate that further research should be conducted to ensure accuracy in identifying chemical vapors using these types of sensors
New results from H.E.S.S. observations of galaxy clusters
Clusters of galaxies are believed to contain a significant population of
cosmic rays. From the radio and probably hard X-ray bands it is known that
clusters are the spatially most extended emitters of non-thermal radiation in
the Universe. Due to their content of cosmic rays, galaxy clusters are also
potential sources of VHE (>100 GeV) gamma rays. Recently, the massive, nearby
cluster Abell 85 has been observed with the H.E.S.S. experiment in VHE gamma
rays with a very deep exposure as part of an ongoing campaign. No significant
gamma-ray signal has been found at the position of the cluster. The
non-detection of this object with H.E.S.S. constrains the total energy of
cosmic rays in this system. For a hard spectral index of the cosmic rays of
-2.1 and if the cosmic-ray energy density follows the large scale gas density
profile, the limit on the fraction of energy in these non-thermal particles
with respect to the total thermal energy of the intra-cluster medium is 8% for
this particular cluster. This value is at the lower bounds of model
predictions.Comment: 4 pages, one figure, invited talk at the 2nd Heidelberg workshop:
"High-Energy Gamma-rays and Neutrinos from Extra-Galactic Sources", January
13 - 16, 2009, to be published in Int. J. Mod. Phys.
ICCM2015: A Comparison of RANS and LES Computational Methods in Analyzing Ventilation Flow Through a Room Fitted with a Two-Sided Windcatcher
A windcatcher is a structure for providing natural ventilation using wind power; it is usually fitted on the roof of a building to exhaust the inside stale air to the outside and supplies the outside fresh air into the building interior space working by pressure difference between outside and inside of the building. In this paper, the behaviour of free wind flow through a three-dimensional room fitted with a centred position two-canal bottom shape windcatcher model is investigated numerically, using a commercial computational fluid dynamics (CFD) software package and LES (Large Eddy Simulation) CFD method. The results have been compared with the obtained results for the same model but using RANS (Reynolds Averaged Navier-Stokes) CFD method. The model with its surrounded space has been considered in both method. It is found that the achieved results for the model from LES method are in good agreement with RANS method’s results for the same model
A comparison of two computational methods (RANS and LES) in analysing of ventilation flow through a room fitted with a two-sided windcatcher for free flow condition
A windcatcher is a structure for providing natural ventilation using wind power; it is usually fitted on the roof of a building to exhaust the inside stale air to the outside and supplies the outside fresh air into the building interior space working by pressure difference between outside and inside of the building. In this paper, the behaviour of free wind flow through a three-dimensional room fitted with a centred position two-canal bottom shape windcatcher model is investigated numerically, using a commercial computational fluid dynamics (CFD) software package and LES (Large Eddy Simulation) CFD method. The results have been compared with the obtained results for the same model but using RANS (Reynolds Averaged Navier-Stokes) CFD method. The model with its surrounded space has been considered in both method. It is found that the achieved results for the model from LES method are in good agreement with RANS method’s results for the same model
Comparisons of elastic and rigid blade-element rotor models using parallel processing technology for piloted simulations
A piloted comparison of rigid and aeroelastic blade-element rotor models was conducted at the Crew Station Research and Development Facility (CSRDF) at Ames Research Center. A simulation development and analysis tool, FLIGHTLAB, was used to implement these models in real time using parallel processing technology. Pilot comments and quantitative analysis performed both on-line and off-line confirmed that elastic degrees of freedom significantly affect perceived handling qualities. Trim comparisons show improved correlation with flight test data when elastic modes are modeled. The results demonstrate the efficiency with which the mathematical modeling sophistication of existing simulation facilities can be upgraded using parallel processing, and the importance of these upgrades to simulation fidelity
No Evidence for Evolution in the Far-Infrared-Radio Correlation out to z ~ 2 in the eCDFS
We investigate the 70 um Far-Infrared Radio Correlation (FRC) of star-forming
galaxies in the Extended Chandra Deep Field South (ECDFS) out to z > 2. We use
70 um data from the Far-Infrared Deep Extragalactic Legacy Survey (FIDEL),
which comprises the most sensitive (~0.8 mJy rms) and extensive far-infrared
deep field observations using MIPS on the Spitzer Space Telescope, and 1.4 GHz
radio data (~8 uJy/beam rms) from the VLA. In order to quantify the evolution
of the FRC we use both survival analysis and stacking techniques which we find
give similar results. We also calculate the FRC using total infrared luminosity
and rest-frame radio luminosity, qTIR, and find that qTIR is constant (within
0.22) over the redshift range 0 - 2. We see no evidence for evolution in the
FRC at 70 um which is surprising given the many factors that are expected to
change this ratio at high redshifts.Comment: 18 pages, 13 figures. Accepted for publication in Ap
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