19,921 research outputs found
Interactive Digital Image Manipulation System (IDIMS)
The implementation of an interactive digital image manipulation system (IDIMS) is described. The system is run on an HP-3000 Series 3 minicomputer. The IDIMS system provides a complete image geoprocessing capability for raster formatted data in a self-contained system. It is easily installed, documentation is provided, and vendor support is available
A brushless despin drive and control for a communication satellite antenna
Spin reducing mechanical drive and control system for steering communication satellite antenn
Structural dynamics verification facility study
The need for a structural dynamics verification facility to support structures programs was studied. Most of the industry operated facilities are used for highly focused research, component development, and problem solving, and are not used for the generic understanding of the coupled dynamic response of major engine subsystems. Capabilities for the proposed facility include: the ability to both excite and measure coupled structural dynamic response of elastic blades on elastic shafting, the mechanical simulation of various dynamical loadings representative of those seen in operating engines, and the measurement of engine dynamic deflections and interface forces caused by alternative engine mounting configurations and compliances
Use of computer-aided analysis techniques for cover type mapping in areas of mountainous terrain
There are no author-identified significant results in this report
Non-local quantum correlations and detection processes in QFT
Quantum detection processes in QFT must play a key role in the description of
quantum field correlations, such as the appearance of entanglement, and of
causal effects. We consider the detection in the case of a simple QFT model
with a suitable interaction to exact treatment, consisting of a quantum scalar
field coupled linearly to a classical scalar source. We then evaluate the
response function to the field quanta of two-level point-like quantum model
detectors, and analyze the effects of the approximation adopted in standard
detection theory. We show that the use of the RWA, that characterizes the
Glauber detection model, leads in the detector response to non-local terms
corresponding to an instantaneously spreading of source effects over the whole
space. Other detector models, obtained with non-standard or the no-application
of RWA, give instead local responses to field quanta, apart from source
independent vacuum contribution linked to preexisting correlations of
zero-point field.Comment: 23 page
Experimental tests of reaction rate theory: Mu+H2 and Mu+D2
Copyright @ 1987 American Institute of Physics.Bimolecular rate constants for the thermal chemical reactions of muonium (Mu) with hydrogen and deuterium—Mu+H2→MuH+H and Mu+D2→MuD+D—over the temperature range 473–843 K are reported. The Arrhenius parameters and 1σ uncertainties for the H2 reaction are log A (cm3 molecule-1 s-1)=-9.605±0.074 and Ea =13.29±0.22 kcal mol-1, while for D2 the values are -9.67±0.12 and 14.73±0.40, respectively. These results are significantly more precise than those reported earlier by Garner et al. For the Mu reaction with H2 our results are in excellent agreement with the 3D quantum mechanical calculations of Schatz on the Liu–Siegbahn–Truhlar–Horowitz potential surface, but the data for both reactions compare less favorably with variational transition-state theory, particularly at the lower temperatures.NSERC (Canada) and the Petroleum Research Foundation of the Americal Chemical Society
Non locality and causal evolution in QFT
Non locality appearing in QFT during the free evolution of localized field
states and in the Feynman propagator function is analyzed. It is shown to be
connected to the initial non local properties present at the level of quantum
states and then it does not imply a violation of Einstein's causality. Then it
is investigated a simple QFT system with interaction, consisting of a classical
source coupled linearly to a quantum scalar field, that is exactly solved. The
expression for the time evolution of the state describing the system is given.
The expectation value of any arbitrary ``good'' local observable, expressed as
a function of the field operator and its space and time derivatives, is
obtained explicitly at all order in the field-matter coupling constant. These
expectation values have a source dependent part that is shown to be always
causally retarded, while the non local contributions are source independent and
related to the non local properties of zero point vacuum fluctuations.Comment: Submitted to Journal of Physics B: 16 pages: 1 figur
Synthesising evidence to estimate pandemic (2009) A/H1N1 influenza severity in 2009-2011
Knowledge of the severity of an influenza outbreak is crucial for informing
and monitoring appropriate public health responses, both during and after an
epidemic. However, case-fatality, case-intensive care admission and
case-hospitalisation risks are difficult to measure directly. Bayesian evidence
synthesis methods have previously been employed to combine fragmented,
under-ascertained and biased surveillance data coherently and consistently, to
estimate case-severity risks in the first two waves of the 2009 A/H1N1
influenza pandemic experienced in England. We present in detail the complex
probabilistic model underlying this evidence synthesis, and extend the analysis
to also estimate severity in the third wave of the pandemic strain during the
2010/2011 influenza season. We adapt the model to account for changes in the
surveillance data available over the three waves. We consider two approaches:
(a) a two-stage approach using posterior distributions from the model for the
first two waves to inform priors for the third wave model; and (b) a one-stage
approach modelling all three waves simultaneously. Both approaches result in
the same key conclusions: (1) that the age-distribution of the case-severity
risks is "u"-shaped, with children and older adults having the highest
severity; (2) that the age-distribution of the infection attack rate changes
over waves, school-age children being most affected in the first two waves and
the attack rate in adults over 25 increasing from the second to third waves;
and (3) that when averaged over all age groups, case-severity appears to
increase over the three waves. The extent to which the final conclusion is
driven by the change in age-distribution of those infected over time is subject
to discussion.Comment: Published in at http://dx.doi.org/10.1214/14-AOAS775 the Annals of
Applied Statistics (http://www.imstat.org/aoas/) by the Institute of
Mathematical Statistics (http://www.imstat.org
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