1,721,062 research outputs found
Space-time processing for the detection of airborne targets in IR image sequences
No full texthe
problem
of
detecting airborne targets
in a
sequence of
images recorded
by
a long
range
infra-red
sensor
is
investigated.
The
generalised likelihood ratio
test
detector
is
derived.
The
detector structure and
its
actual implementation
are
discussed. Approximated expressions of
the
false
alarm and
detection
probabilities are obtained
and
validated
by
means
of
simulations.
Example
results
obtained on a
set
of
experimental data are reporte
Novel background removal algorithm for navy Infrared Search and Track systems
No full textNavy infrared search and track (IRST) systems aim at detecting long range airborne targets closing the naval unit at low altitude above the sea surface.1 The target signal is a 2-D pulse of small spatial extent and is well approximated by the sensor point spread function (PSF); further, the signal to clutter ratio (SCR) is usually very low and detection cannot be performed on a single frame. Multiple frame detection algorithms are therefore used to improve the detection probability. Such algorithms integrate the target signal over a number of consecutive frames by means of appropriate 3-D filters tuned to different target trajectories (velocity or directional filters234). The typical naval surveillance scenario includes background features such as clear sky, clouds, and sea.5 These features are usually nonstationary and their mean value undergoes changes both in space and time. For the integration to be effective, the structures in the IR images must be removed prior to 3-D filtering. This operation, which is called background removal, consists in adaptively estimating the spatially varying mean of the background signal and on subtracting it from each image. Background removal represents a critical step, because even a small error in the background estimate can mask the possible target
High-resolution analysis of the nu(4) absorption band of (CH2BrF)-Br-79
No full textThe gas-phase infrared spectrum of the fundamental band of CH 79BrF was recorded in the 1010 –1116 cm1 wavenumber 42
79
region using a TDL spectrometer. In this first high-resolution investigation of the synthesized
Br isotopic form, more than
10 200 transitions of this a/b-hybrid band centered at 1068.5385 cm
1
were assigned and, using the Watson’s A-reduced
Hamiltonian in the Ir-representation, a reliable set of molecular constants for the excited state v 1 was determined. From
4
ground state combination differences having rotational quantum numbers J and Ka up to 97 and 21, respectively, improved and extended ground state rotational and centrifugal distortion constants were calculated as well. Comparison between the observed and calculated band intensities in appropriate regions of the spectrum gave an estimate of the transition dipole- moment ratio along the a and b axes as a/b 2.0 0.2, in agreement with the predicted theoretical value of 1.99
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Lengthy, detailed political profile of U.S. represenative John E. Baldacci, a Ba
No full textLengthy, detailed political profile of U.S. represenative John E. Baldacci, a Bangor Democrat, who is currently considered to head the pack of those aspiring to be elected governor of Maine in 2001. With a brief outline of Baldacci\u27s gubernatorial agenda
Modelling and experimental validation of H2S emissions in geothermal power plants
No full textA commercial computer software, used to model and simulate geothermal power plants, has been investigated by comparing simulation outputs with field data of existing plants. Although most simulation results were in good agreement with the field data, the program failed when predicting the H2S distribution between the plant streams. The computer program has, therefore, been partly modified on the basis of pilot-scale experiments directed at investigating the H2S behaviour in the two main plant sections, i.e. the direct contact condenser and the cooling tower. The modified version fits the field data well and is a useful tool for assessing methods to reduce the environmental impact of releasing H2S into the atmosphere
«E la morte fuggirà loro». Post-zombie e ritornanti. Elementi formali e tematici di un'apocalittica delle serie Tv
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