5,449 research outputs found
DIMENSIONS OF KNOWLEDGE IN PROTOTYPING:A REVIEW AND CHARACTERISATION OF PROTOTYPING METHODS AND THEIR CONTRIBUTIONS TO DESIGN KNOWLEDGE
Aircraft/island/ship/satellite intercomparison: Preliminary results from July 16, 1987
The First ISCCP Regional Experiment (FIRE) objective of validating and improving satellite algorithms for inferring cloud properties from satellite radiances was one of the central motivating factors in the design of the specific field experimental strategies used in the July, 1987 marine stratocumulus intensive field observations (IFO). The in situ measuring platforms were deployed to take maximum advantage of redundant measurements (for intercomparison of the in situ sensors) and to provide optimal coverage within satellite images. One of the most ambitious of these strategies was the attempt to coordinate measurements from San Nicolas Island (SNI), the R/V Pt. Sur, the meteorological aircraft, and the satellites. For the most part, this attempt was frustrated by flight restrictions in the vicinity of SNI. The exception was the mission of July 16, 1987, which achieved remarkable success in the coordination of the platforms. This presentation concerns operations conducted by the National Center for Atmospheric Research (NCAR) Electra and how data from the Electra can be integrated with and compared to data from the Pt. Sur, SNI, and the satellites. The focus is on the large-scale, integrated picture of the conditions on July 16 from the perspective of the Electra's flight operations
Army Professionalism, the Military Ethic, and Officership in the 21st Century
The authors address what they—and many others—perceived to be a decline in military professionalism in the Army officer corps. The authors first describe the ethical, technical, and political components of military professionalism and then address the causes for the decline. They conclude by proposing a set of principles which, if adhered to, will reinvigorate the vision of the officer corps and motivate the corps to selfless service.https://press.armywarcollege.edu/monographs/1145/thumbnail.jp
Reservoir Computing Approach to Robust Computation using Unreliable Nanoscale Networks
As we approach the physical limits of CMOS technology, advances in materials
science and nanotechnology are making available a variety of unconventional
computing substrates that can potentially replace top-down-designed
silicon-based computing devices. Inherent stochasticity in the fabrication
process and nanometer scale of these substrates inevitably lead to design
variations, defects, faults, and noise in the resulting devices. A key
challenge is how to harness such devices to perform robust computation. We
propose reservoir computing as a solution. In reservoir computing, computation
takes place by translating the dynamics of an excited medium, called a
reservoir, into a desired output. This approach eliminates the need for
external control and redundancy, and the programming is done using a
closed-form regression problem on the output, which also allows concurrent
programming using a single device. Using a theoretical model, we show that both
regular and irregular reservoirs are intrinsically robust to structural noise
as they perform computation
Optical and Infrared Photometry of the Unusual Type Ia Supernova 2000cx
We present optical and infrared photometry of the unusual Type Ia supernova
2000cx. With the data of Li et al. (2001) and Jha (2002), this comprises the
largest dataset ever assembled for a Type Ia SN, more than 600 points in
UBVRIJHK. We confirm the finding of Li et al. regarding the unusually blue B-V
colors as SN 2000cx entered the nebular phase. Its I-band secondary hump was
extremely weak given its B-band decline rate. The V minus near infrared colors
likewise do not match loci based on other slowly declining Type Ia SNe, though
V-K is the least ``abnormal''. In several ways SN 2000cx resembles other slow
decliners, given its B-band decline rate (Delta m_15(B) = 0.93), the appearance
of Fe III lines and weakness of Si II in its pre-maximum spectrum, the V-K
colors and post-maximum V-H colors. If the distance modulus derived from
Surface Brightness Fluctuations of the host galaxy is correct, we find that the
rate of light increase prior to maximum, the characteristics of the bolometric
light curve, and the implied absolute magnitude at maximum are all consistent
with a sub-luminous object with Delta m_15(B) ~ 1.6-1.7 having a higher than
normal kinetic energy.Comment: 46 pages, 17 figures, to be published in Publications of the
Astronomical Society of the Pacifi
Distinguishing artefacts:evaluating the saturation point of convolutional neural networks
Prior work has shown Convolutional Neural Networks (CNNs) trained on
surrogate Computer Aided Design (CAD) models are able to detect and classify
real-world artefacts from photographs. The applications of which support
twinning of digital and physical assets in design, including rapid extraction
of part geometry from model repositories, information search \& retrieval and
identifying components in the field for maintenance, repair, and recording. The
performance of CNNs in classification tasks have been shown dependent on
training data set size and number of classes. Where prior works have used
relatively small surrogate model data sets ( models), the question
remains as to the ability of a CNN to differentiate between models in
increasingly large model repositories. This paper presents a method for
generating synthetic image data sets from online CAD model repositories, and
further investigates the capacity of an off-the-shelf CNN architecture trained
on synthetic data to classify models as class size increases. 1,000 CAD models
were curated and processed to generate large scale surrogate data sets,
featuring model coverage at steps of 10, 30, 60,
and 120 degrees. The findings demonstrate the capability of computer
vision algorithms to classify artefacts in model repositories of up to 200,
beyond this point the CNN's performance is observed to deteriorate
significantly, limiting its present ability for automated twinning of physical
to digital artefacts. Although, a match is more often found in the top-5
results showing potential for information search and retrieval on large
repositories of surrogate models.Comment: 6 Pages, 5 Figures, 2 Tables, Conference, Design Engineering, CNN,
Digital Twi
Comparison of OLYMPUS beacon and radiometric attenuation measurements at Blacksburg, Virginia
Measurements of attenuation of the 20 and 30 GHz beacons onboard the OLYMPUS satellite are compared to simultaneous observations of atmospheric attenuation by a multichannel microwave radiometer along the same path. Departures from high correlation between the two measurements are believed to be related to differences in antenna beamwidths. Mean equivalent zenith attenuations derived from the slant path data are compared to zenith observations made at previous locations
Defect detection in nano-scale transistors based on radio-frequency reflectometry
Radio-frequency reflectometry in silicon single-electron transistors (SETs)
is presented. At low temperatures (<4 K), in addition to the expected Coulomb
blockade features associated with charging of the SET dot, quasi-periodic
oscillations are observed that persist in the fully depleted regime where the
SET dot is completely empty. A model, confirmed by simulations, indicates that
these oscillations originate from charging of an unintended floating gate
located in the heavily doped polycrystalline silicon gate stack. The technique
used in this experiment can be applied for detailed spectroscopy of various
charge defects in nanoscale SETs and field effect transistorsComment: 3 pages, 3 figure
In Situ Resistance Measurements of Strained Carbon Nanotubes
We investigate the response of multi-walled carbon nanotubes to mechanical
strain applied with an Atomic Force Microscope (AFM) probe. We find that in
some samples, changes in the contact resistance dominate the measured
resistance change. In others, strain large enough to fracture the tube can be
applied without a significant change in the contact resistance. In this case we
observe that enough force is applied to break the tube without any change in
resistance until the tube fails. We have also manipulated the ends of the
broken tube back in contact with each other, re-establishing a finite
resistance. We observe that in this broken configuration the resistance of the
sample is tunable to values 15-350 kW greater than prior to breaking.Comment: Submitted to Applied Physics Letter
Remote sensing data from CLARET: A prototype CART data set
The data set containing radiation, meteorological , and cloud sensor observations is documented. It was prepared for use by the Department of Energy's Atmospheric Radiation Measurement (ARM) Program and other interested scientists. These data are a precursor of the types of data that ARM Cloud And Radiation Testbed (CART) sites will provide. The data are from the Cloud Lidar And Radar Exploratory Test (CLARET) conducted by the Wave Propagation Laboratory during autumn 1989 in the Denver-Boulder area of Colorado primarily for the purpose of developing new cloud-sensing techniques on cirrus. After becoming aware of the experiment, ARM scientists requested archival of subsets of the data to assist in the developing ARM program. Five CLARET cases were selected: two with cirrus, one with stratus, one with mixed-phase clouds, and one with clear skies. Satellite data from the stratus case and one cirrus case were analyzed for statistics on cloud cover and top height. The main body of the selected data are available on diskette from the Wave Propagation Laboratory or Los Alamos National Laboratory
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