2,678 research outputs found
Investigations in space communications theory, including topics related to random processes, filtering, telemetry Semiannual status report, 1 Oct. 1966 - 31 Mar. 1967
Random processes, filtering, and telemetry problems in space communications theor
Fano Lineshapes Revisited: Symmetric Photoionization Peaks from Pure Continuum Excitation
In a photoionization spectrum in which there is no excitation of the discrete
states, but only the underlying continuum, we have observed resonances which
appear as symmetric peaks, not the commonly expected window resonances.
Furthermore, since the excitation to the unperturbed continuum vanishes, the
cross section expected from Fano's configuration interaction theory is
identically zero. This shortcoming is removed by the explicit introduction of
the phase shifted continuum, which demonstrates that the shape of a resonance,
by itself, provides no information about the relative excitation amplitudes to
the discrete state and the continuum.Comment: 4 pages, 3 figure
Artifacts with uneven sampling of red noise
The vast majority of sampling systems operate in a standard way: at each tick
of a fixed-frequency master clock a digitizer reads out a voltage that
corresponds to the value of some physical quantity and translates it into a bit
pattern that is either transmitted, stored, or processed right away. Thus
signal sampling at evenly spaced time intervals is the rule: however this is
not always the case, and uneven sampling is sometimes unavoidable.
While periodic or quasi-periodic uneven sampling of a deterministic signal
can reasonably be expected to produce artifacts, it is much less obvious that
the same happens with noise: here I show that this is indeed the case only for
long-memory noise processes, i.e., power-law noises with . The resulting artifacts are usually a nuisance although they can be
eliminated with a proper processing of the signal samples, but they could also
be turned to advantage and used to encode information.Comment: 5 figure
Evaluation of HCMM data for assessing soil moisture and water table depth
Soil moisture in the 0-cm to 4-cm layer could be estimated with 1-mm soil temperatures throughout the growing season of a rainfed barley crop in eastern South Dakota. Empirical equations were developed to reduce the effect of canopy cover when radiometrically estimating the soil temperature. Corrective equations were applied to an aircraft simulation of HCMM data for a diversity of crop types and land cover conditions to estimate the soil moisture. The average difference between observed and measured soil moisture was 1.6% of field capacity. Shallow alluvial aquifers were located with HCMM predawn data. After correcting the data for vegetation differences, equations were developed for predicting water table depths within the aquifer. A finite difference code simulating soil moisture and soil temperature shows that soils with different moisture profiles differed in soil temperatures in a well defined functional manner. A significant surface thermal anomaly was found to be associated with shallow water tables
Tunable Fano Resonances in Transport through Microwave Billiards
We present a tunable microwave scattering device that allows the controlled
variation of Fano line shape parameters in transmission through quantum
billiards. Transport in this device is nearly fully coherent. By comparison
with quantum calculations, employing the modular recursive Green's-function
method, the scattering wave function and the degree of residual decoherence can
be determined. The parametric variation of Fano line shapes in terms of
interacting resonances is analyzed.Comment: 5 pages, 4 figures, submitted to Phys. Rev.
Evaluation of HCMM data for assessing soil moisture and water table depth
Data were analyzed for variations in eastern South Dakota. Soil moisture in the 0-4 cm layer could be estimated with 1-mm soil temperatures throughout the growing season of a rainfed barley crop (% cover ranging from 30% to 90%) with an r squared = 0.81. Empirical equations were developed to reduce the effect of canopy cover when radiometrically estimating the 1-mm soil temperature, r squared = 0.88. The corrective equations were applied to an aircraft simulation of HCMM data for a diversity of crop types and land cover conditions to estimate the 0-4 cm soil moisture. The average difference between observed and measured soil moisture was 1.6% of field capacity. HCMM data were used to estimate the soil moisture for four dates with an r squared = 0.55 after correction for crop conditions. Location of shallow alluvial aquifers could be accomplished with HCMM predawn data. After correction of HCMM day data for vegetation differences, equations were developed for predicting water table depths within the aquifer (r=0.8)
Statistical hadronization of heavy flavor quarks in elementary collisions: successes and failures
We analyze recently compiled data on the production of open heavy flavor
hadrons and quarkonia in e+e- as well as pp and p-nucleus collisions in terms
of the statistical hadronization model. Within this approach the production of
open heavy flavor hadrons is well described with parameters deduced from a
thermal analysis of light flavor hadron production. In contrast, quarkonium
production in such collisions cannot be described in this framework. We point
out the relevance of this finding for our understanding of quarkonium
production in ultra-relativistic nucleus-nucleus collisions.Comment: 11 pages, 5 figures; v2: final version as accepted in Phys. Lett. B
(updated figures and references
Canonical Statistical Model and hadron production in annihilations
We discuss the production of hadrons in collisions at
GeV. We address the question wether the particle yields measured in the final
states are consistent with the statistical model predictions. In the model
formulation we account for exact conservation of all relevant quantum numbers
using the canonical description of the partition function. Within our model the
validity of the thermodynamical approach to quantify particle production in
annihilations is not obvious
Heavy quark(onium) at LHC: the statistical hadronization case
We discuss the production of charmonium in nuclear collisions within the
framework of the statistical hadronization model. We demonstrate that the model
reproduces very well the availble data at RHIC. We provide predictions for the
LHC energy where, dependently on the charm production cross section, a
dramatically different behaviour of charmonium production as a function of
centrality might be expected. We discuss also the case in elementary
collisions, where clearly the statistical model does not reproduce the
measurements.Comment: 8 pages, 5 figures; proceeding of SQM09, Buzios, Brazil, to be
published in J. Phys.
The canonical partition function for relativistic hadron gases
Particle production in high-energy collisions is often addressed within the
framework of the thermal (statistical) model. We present a method to calculate
the canonical partition function for the hadron resonance gas with exact
conservation of the baryon number, strangeness, electric charge, charmness and
bottomness. We derive an analytical expression for the partition function which
is represented as series of Bessel functions. Our results can be used directly
to analyze particle production yields in elementary and in heavy ion
collisions. We also quantify the importance of quantum statistics in the
calculations of the light particle multiplicities in the canonical thermal
model of the hadron resonance gas.Comment: 10 pages, 2 figures; submitted for publication in EPJ
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