9,901 research outputs found
Analysis of AIS Data of the Recluse Oil Field, Recluse, Wyoming
Airborne Imaging Spectrometer (AIS) data were flown over the Recluse, Wyoming oil field on September 9, 1984. Processing software was developed at Earth Satellite Corporation (EarthSat) for interactive analysis of the AIS data. EarthSat's AIS processing capabilities include destriping, solar irradiance corrections, residual calculations, geometric resampling, equal energy normalization, interactive spectral classifications and a variety of compressive algorithms to reduce the data to 8-bit format with a minimum of information loss. The in-house photolab facilities of EarthSat can routinely produce high-quality color renditions of the enhanced AIS data. A total of 80 lithologic samples were collected under the AIS flight lines. Correlation (within the atmospheric windows) between the laboratory and the AIS spectra of sample sites was generally poor. Reasonable correlation was only possible in large, freshly plowed fields. Mixed pixels and contrast between the natural and sample's surfaces were believed responsible for the poor correlation. Finally, a drift of approximately three channels was observed in the diffraction grating position within the 1.8 to 2.1 micron quadrant
An analytical study of electric vehicle handling dynamics
Hypothetical electric vehicle configurations were studied by applying available analytical methods. Elementary linearized models were used in addition to a highly sophisticated vehicle dynamics computer simulation technique. Physical properties of specific EV's were defined for various battery and powertrain packaging approaches applied to a range of weight distribution and inertial properties which characterize a generic class of EV's. Computer simulations of structured maneuvers were performed for predicting handling qualities in the normal driving range and during various extreme conditions related to accident avoidance. Results indicate that an EV with forward weight bias will possess handling qualities superior to a comparable EV that is rear-heavy or equally balanced. The importance of properly matching tires, suspension systems, and brake system front/rear torque proportioning to a given EV configuration during the design stage is demonstrated
Hammerhead, an ultrahigh resolution ePix camera for wavelength-dispersive spectrometers
Wavelength-dispersive spectrometers (WDS) are often used in synchrotron and
FEL applications where high energy resolution (in the order of eV) is
important. Increasing WDS energy resolution requires increasing spatial
resolution of the detectors in the dispersion direction. The common approaches
with strip detectors or small pixel detectors are not ideal. We present a novel
approach, with a sensor using rectangular pixels with a high aspect ratio
(between strips and pixels, further called "strixels"), and strixel
redistribution to match the square pixel arrays of typical ASICs while avoiding
the considerable effort of redesigning ASICs. This results in a sensor area of
17.4 mm x 77 mm, with a fine pitch of 25 m in the horizontal direction
resulting in 3072 columns and 176 rows. The sensors use ePix100 readout ASICs,
leveraging their low noise (43 e, or 180 eV rms). We present results
obtained with a Hammerhead ePix100 camera, showing that the small pitch (25
m) in the dispersion direction maximizes performance for both high and low
photon occupancies, resulting in optimal WDS energy resolution. The low noise
level at high photon occupancy allows precise photon counting, while at low
occupancy, both the energy and the subpixel position can be reconstructed for
every photon, allowing an ultrahigh resolution (in the order of 1 m) in
the dispersion direction and rejection of scattered beam and harmonics. Using
strixel sensors with redistribution and flip-chip bonding to standard ePix
readout ASICs results in ultrahigh position resolution (1 m) and low
noise in WDS applications, leveraging the advantages of hybrid pixel detectors
(high production yield, good availability, relatively inexpensive) while
minimizing development complexity through sharing the ASIC, hardware, software
and DAQ development with existing versions of ePix cameras.Comment: 8 pages, 6 figure
Novel designs for Penning ion traps
We present a number of alternative designs for Penning ion traps suitable for
quantum information processing (QIP) applications with atomic ions. The first
trap design is a simple array of long straight wires which allows easy optical
access. A prototype of this trap has been built to trap Ca+ and a simple
electronic detection scheme has been employed to demonstrate the operation of
the trap. Another trap design consists of a conducting plate with a hole in it
situated above a continuous conducting plane. The final trap design is based on
an array of pad electrodes. Although this trap design lacks the open geometry
of the traps described above, the pad design may prove useful in a hybrid
scheme in which information processing and qubit storage take place in
different types of trap. The behaviour of the pad traps is simulated
numerically and techniques for moving ions rapidly between traps are discussed.
Future experiments with these various designs are discussed. All of the designs
lend themselves to the construction of multiple trap arrays, as required for
scalable ion trap QIP.Comment: 11 pages, 10 figure
Doppler-free laser spectroscopy of buffer gas cooled molecular radicals
We demonstrate Doppler-free saturated absorption spectroscopy of cold
molecular radicals formed by laser ablation inside a cryogenic buffer gas cell.
By lowering the temperature, congested regions of the spectrum can be
simplified, and by using different temperatures for different regions of the
spectrum a wide range of rotational states can be studied optimally. We use the
technique to study the optical spectrum of YbF radicals with a resolution of 30
MHz, measuring the magnetic hyperfine parameters of the electronic ground
state. The method is suitable for high resolution spectroscopy of a great
variety of molecules at controlled temperature and pressure, and is
particularly well-suited to those that are difficult to produce in the gas
phase.Comment: 11 pages, 4 figure
The Anti-Coincidence Detector for the GLAST Large Area Telescope
This paper describes the design, fabrication and testing of the
Anti-Coincidence Detector (ACD) for the Gamma-ray Large Area Space Telescope
(GLAST) Large Area Telescope (LAT). The ACD is LAT first-level defense against
the charged cosmic ray background that outnumbers the gamma rays by 3-5 orders
of magnitude. The ACD covers the top and 4 sides of the LAT tracking detector,
requiring a total active area of ~8.3 square meters. The ACD detector utilizes
plastic scintillator tiles with wave-length shifting fiber readout. In order to
suppress self-veto by shower particles at high gamma-ray energies, the ACD is
segmented into 89 tiles of different sizes. The overall ACD efficiency for
detection of singly charged relativistic particles entering the tracking
detector from the top or sides of the LAT exceeds the required 0.9997.Comment: 33 pages, 19 figure
Operations on integral lifts of K(n)
This very rough sketch is a sequel to arXiv:1808.08587; it presents evidence
that operations on lifts of the functors K(n) to cohomology theories with
values in modules over valuation rings of local number fields, indexed by
Lubin-Tate groups of such fields, are extensions of the groups of automorphisms
of the indexing group laws, by the exterior algebras on the normal bundle to
the orbits of the group laws in the space of lifts.Comment: \S 2.0 hopefully less cryptic. To appear in the proceedings of the
2015 Nagoya conference honoring T Ohkawa. Comments very welcome
Dynamics of axialized laser-cooled ions in a Penning trap
We report the experimental characterization of axialization - a method of
reducing the magnetron motion of a small number of ions stored in a Penning
trap. This is an important step in the investigation of the suitability of
Penning traps for quantum information processing. The magnetron motion was
coupled to the laser-cooled modified cyclotron motion by the application of a
near-resonant oscillating quadrupole potential (the "axialization drive").
Measurement of cooling rates of the radial motions of the ions showed an
order-of-magnitude increase in the damping rate of the magnetron motion with
the axialization drive applied. The experimental results are in good
qualitative agreement with a recent theoretical study. In particular, a
classical avoided crossing was observed in the motional frequencies as the
axialization drive frequency was swept through the optimum value, proving that
axialization is indeed a resonant effect.Comment: 8 pages, 9 figure
Software development cultures and cooperation problems: a field study of the early stages of development of software for a scientific community
In earlier work, I identified a particular class of end-user developers, who include scientists and whom I term 'professional end-user developers', as being of especial interest. Here, I extend this work by articulating a culture of professional end-user development, and illustrating by means of a field-study how the influence of this culture causes cooperation problems in an inter-disciplinary team developing a software system for a scientific community. My analysis of the field study data is informed by some recent literature on multi-national work cultures. Whilst acknowledging that viewing a scientific development through a lens of software development culture does not give a full picture, I argue that it nonetheless provides deep insights
Segal-Bargmann-Fock modules of monogenic functions
In this paper we introduce the classical Segal-Bargmann transform starting
from the basis of Hermite polynomials and extend it to Clifford algebra-valued
functions. Then we apply the results to monogenic functions and prove that the
Segal-Bargmann kernel corresponds to the kernel of the Fourier-Borel transform
for monogenic functionals. This kernel is also the reproducing kernel for the
monogenic Bargmann module.Comment: 11 page
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