2,030 research outputs found
Motor brush wear measured with strain gages
Balanced bridge circuit, supplied with low-voltage direct current and connected to a readout device, measures remaining brush material, rate of brush wear, armature runout, and brush signature
Swift Wind Turbine Testing
Swift wind turbine testing to AWEA small wind turbine test standards
The Local Leo Cold Cloud and New Limits on a Local Hot Bubble
We present a multi-wavelength study of the local Leo cold cloud (LLCC), a
very nearby, very cold cloud in the interstellar medium. Through stellar
absorption studies we find that the LLCC is between 11.3 pc and 24.3 pc away,
making it the closest known cold neutral medium cloud and well within the
boundaries of the local cavity. Observations of the cloud in the 21-cm HI line
reveal that the LLCC is very cold, with temperatures ranging from 15 K to 30 K,
and is best fit with a model composed of two colliding components. The cloud
has associated 100 micron thermal dust emission, pointing to a somewhat low
dust-to-gas ratio of 48 x 10^-22 MJy sr^-1 cm^2. We find that the LLCC is too
far away to be generated by the collision among the nearby complex of local
interstellar clouds, but that the small relative velocities indicate that the
LLCC is somehow related to these clouds. We use the LLCC to conduct a shadowing
experiment in 1/4 keV X-rays, allowing us to differentiate between different
possible origins for the observed soft X-ray background. We find that a local
hot bubble model alone cannot account for the low-latitude soft X-ray
background, but that isotropic emission from solar wind charge exchange does
reproduce our data. In a combined local hot bubble and solar wind charge
exchange scenario, we rule out emission from a local hot bubble with an 1/4 keV
emissivity greater than 1.1 Snowdens / pc at 3 sigma, 4 times lower than
previous estimates. This result dramatically changes our perspective on our
local interstellar medium.Comment: 13 pages, 12 figures. Accepted for publication in the Astrophysical
Journal. Vector figure version available at
http://www.astro.columbia.edu/~jpeek
Human activity recognition from inertial sensor time-series using batch normalized deep LSTM recurrent networks
In recent years machine learning methods for human activity recognition have been found very effective. These classify discriminative features generated from raw input sequences acquired from body-worn inertial sensors. However, it involves an explicit feature extraction stage from the raw data, and although human movements are encoded in a sequence of successive samples in time most state-of-the-art machine learning methods do not exploit the temporal correlations between input data samples. In this paper we present a Long-Short Term Memory (LSTM) deep recurrent neural network for the classification of six daily life activities from accelerometer and gyroscope data. Results show that our LSTM can processes featureless raw input signals, and achieves 92 % average accuracy in a multi-class-scenario. Further, we show that this accuracy can be achieved with almost four times fewer training epochs by using a batch normalization approach
Measurement of optical to electrical and electrical to optical delays with ps-level uncertainty
We present a new measurement principle to determine the absolute time delay
of a waveform from an optical reference plane to an electrical reference plane
and vice versa. We demonstrate a method based on this principle with 2 ps
uncertainty. This method can be used to perform accurate time delay
determinations of optical transceivers used in fibre-optic time-dissemination
equipment. As a result the time scales in optical and electrical domain can be
related to each other with the same uncertainty. We expect this method to break
new grounds in high-accuracy time transfer and absolute calibration of
time-transfer equipment
The GALFA-HI Compact Cloud Catalog
We present a catalog of 1964 isolated, compact neutral hydrogen clouds from
the Galactic Arecibo L-Band Feed Array Survey Data Release One (GALFA-HI DR1).
The clouds were identified by a custom machine-vision algorithm utilizing
Difference of Gaussian kernels to search for clouds smaller than 20'. The
clouds have velocities typically between |VLSR| = 20-400 km/s, linewidths of
2.5-35 km/s, and column densities ranging from 1 - 35 x 10^18 cm^-2. The
distances to the clouds in this catalog may cover several orders of magnitude,
so the masses may range from less than a Solar mass for clouds within the
Galactic disc, to greater than 10^4 Solar Masses for HVCs at the tip of the
Magellanic Stream. To search for trends, we separate the catalog into five
populations based on position, velocity, and linewidth: high velocity clouds
(HVCs); galaxy candidates; cold low velocity clouds (LVCs); warm, low
positive-velocity clouds in the third Galactic Quadrant; and the remaining warm
LVCs. The observed HVCs are found to be associated with previously-identified
HVC complexes. We do not observe a large population of isolated clouds at high
velocities as some models predict. We see evidence for distinct histories at
low velocities in detecting populations of clouds corotating with the Galactic
disc and a set of clouds that is not corotating.Comment: 34 Pages, 9 Figures, published in ApJ (2012, ApJ, 758, 44), this
version has the corrected fluxes and corresponding flux histogram and masse
A Cold Nearby Cloud Inside the Local Bubble
The high-latitude Galactic H I cloud toward the extragalactic radio source 3C
225 is characterized by very narrow 21 cm emission and absorption indicative of
a very low H I spin temperature of about 20 K. Through high-resolution optical
spectroscopy, we report the detection of strong, very narrow Na I absorption
corresponding to this cloud toward a number of nearby stars. Assuming that the
turbulent H I and Na I motions are similar, we derive a cloud temperature of 20
(+6, -8) K (in complete agreement with the 21 cm results) and a line-of-sight
turbulent velocity of 0.37+/-0.08 km/s from a comparison of the H I and Na I
absorption linewidths. We also place a firm upper limit of 45 pc on the
distance of the cloud, which situates it well inside the Local Bubble in this
direction and makes it the nearest-known cold diffuse cloud discovered to date.Comment: 11 pages, 3 figures, accepted for publication in ApJ Letter
Is blue dye still required during sentinel lymph node biopsy for breast cancer?
BACKGROUND:
In early breast cancer, the optimal technique for sentinel lymph node biopsy (SLNB) is the combined technique (radioisotope and Patent Blue V) which achieves high identification rates. Despite this, many centres have decided to stop using blue dye due to blue-dye-related complications (tattoo, anaphylaxis). We evaluated the SLNB identification rate using the combined technique with and without Patent Blue V and the blue-dye-related complication rates.
METHODS:
Clinical and histological data were analysed on patients undergoing SLNB between March 2014 and April 2015. SLNB was performed following standard hospital protocols using the combined technique.
RESULTS:
A total of 208 patients underwent SLNB and 160 patients (342 nodes) with complete operation notes were available for final analysis. The identification rate with the combined technique was 98.8% (n = 158/160), with blue dye alone 92.5% (n = 148/160) and with radioisotope alone 97.5% (n = 156/160). A total of 76.9% (263/342) of nodes were radioactive and blue, 15.5% (53/342) only radioactive and 2.3% (8/342) only blue, 5.3% (18/342) were neither radioactive nor blue. No anaphylactic reactions were reported and blue skin staining was reported in six (3.8%) patients.
CONCLUSION:
The combined technique should continue be the preferred technique for SLNB and should be standardised. Radioisotope alone (but not blue dye alone) has comparable sentinel node identification rates in experienced hands. National guidelines are required to optimise operative documentation
A comparison of the ground magnetic responses during the 2013 and 2015 St. Patrick's Day geomagnetic storms
Reconstructing Deconstruction: High-Velocity Cloud Distance Through Disruption Morphology
We present Arecibo L-band Feed Array 21-cm observations of a sub-complex of
HVCs at the tip of the Anti-Center Complex. These observations show
morphological details that point to interaction with the ambient halo medium
and differential drag within the cloud sub-complex. We develop a new technique
for measuring cloud distances, which relies upon these observed morphological
and kinematic characteristics, and show that it is consistent with H-alpha
distances. These results are consistent with distances to HVCs and halo
densities derived from models in which HVCs are formed from cooling halo gas.Comment: 8 pages, 2 figures, 1 tabe, Accepted to Ap
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