20,949 research outputs found
A route generator concept for aircraft onboard fault monitoring
Because of the increasingly complex environments in which the flight crews of commercial aviation aircraft must operate, a research effort is currently underway at NASA Langley Research Center to investigate the potential benefits of intelligent cockpit aids, and to establish guidelines for the application of artificial intelligence techniques to advanced flight management concepts. The segment of this research area that concentrates on automated fault monitoring and diagnosis requires that a reference frame exist, against which the current state of the aircraft may be compared to determine the existence of a fault. This paper describes a computer program which generates the position of that reference frame that specifies the horizontal flight route
Proposed method for searches of gravitational waves from PKS 2155-304 and other blazar flares
We propose to search for gravitational waves from PKS 2155-304 as well as
other blazars. PKS 2155-304 emitted a long duration energetic flare in July
2006, with total isotropic equivalent energy released in TeV gamma rays of
approximately ergs. Any possible gravitational wave signals
associated with this outburst should be seen by gravitational wave detectors at
the same time as the electromagnetic signal. During this flare, the two LIGO
interferometers at Hanford and the GEO detector were in operation and
collecting data. For this search we will use the data from multiple
gravitational wave detectors. The method we use for this purpose is a coherent
network analysis algorithm and is called {\tt RIDGE}. To estimate the
sensitivity of the search, we perform numerical simulations. The sensitivity to
estimated gravitational wave energy at the source is about
ergs for a detection probability of 20%. For this search, an end-to-end
analysis pipeline has been developed, which takes into account the motion of
the source across the sky.Comment: 10 pages, 7 figures. Contribution to 12th Gravitational Wave Data
Analysis Workshop. Submitted to Classical and Quantum Gravity. Changes in
response to referee comment
Comparison of Integrated Gasifier-Combined Cycle and AFB-steam turbine systems for industrial cogeneration
In the cogeneration technology alternatives study (CTAS) a number of advanced coal fired systems were examined and systems using a integrated coal gasifier IGCC or a fluid bed combustor AFB were found to yield attractive cogeneration results in industrial cogeneration applications. A range of site requirements and cogeneration sizing strategies using ground rules based on CTAS were used in comparing an IGCC and an AFB. The effect of time variations in site requirements and the sensitivity to fuel and electricity price assumptions are examined. The economic alternatives of industrial or utility ownership are also considered. The results indicate that the IGCC system has potentially higher fuel and emission savings and could be an attractive option for utility ownership. The AFB steam turbine system has a potentially higher return on investment and could be attractive assuming industrial ownership
Scaling graphs of heart rate time series in athletes demonstrate the VLF, LF and HF regions
Scaling analysis of heart rate time series has emerged as an useful tool for
assessment of autonomic cardiac control. We investigate the heart rate time
series of ten athletes (five males and five females), by applying detrended
fluctuation analysis (DFA). High resolution ECGs are recorded under
standardized resting conditions over 30 minutes and subsequently heart rate
time series are extracted and artefacts filtered. We find three distinct
regions of scale-invariance, which correspond to the well-known VLF, LF, and HF
bands in the power spectra of heart rate variability. The scaling exponents
alpha are alphaHF: 1.15 [0.96-1.22], alphaLF: 0.68 [0.57-0.84], alphaVLF:
0.83[0.82-0.99]; p<10^-5). In conclusion, DFA scaling exponents of heart rate
time series should be fitted to the VLF, LF, and HF ranges, respectively
Quantum advantage by relational queries about physically realizable equivalence classes
Relational quantum queries are sometimes capable to effectively decide
between collections of mutually exclusive elementary cases without completely
resolving and determining those individual instances. Thereby the set of
mutually exclusive elementary cases is effectively partitioned into equivalence
classes pertinent to the respective query. In the second part of the paper, we
review recent progress in theoretical certifications (relative to the
assumptions made) of quantum value indeterminacy as a means to build quantum
oracles for randomness.Comment: 8 Pages, one figure, invited contribution to TopHPC2019, Tehran,
Iran, April 22-25, 201
Continuous Spin Representations of the Poincar\'e and Super-Poincar\'e Groups
We construct Wigner's continuous spin representations of the Poincar\'e
algebra for massless particles in higher dimensions. The states are labeled
both by the length of a space-like translation vector and the Dynkin indices of
the {\it short little group} , where is the space-time dimension.
Continuous spin representations are in one-to-one correspondence with
representations of the short little group. We also demonstrate how combinations
of the bosonic and fermionic representations form supermultiplets of the
super-Poincar\'e algebra. If the light-cone translations are nilpotent, these
representations become finite dimensional, but contain zero or negative norm
states, and their supersymmetry algebra contains a central charge in four
dimensions.Comment: 19 page
Primordial Gravitational Waves From Open Inflation
We calculate the spectrum of gravitational waves generated during inflation
in open inflationary models. In such models an initial epoch of
old inflation solves the horizon and flatness problems, and during this first
epoch of inflation the quantum state of the graviton field rapidly approaches
the Bunch-Davies vacuum. Then old inflation ends by the nucleation of a single
bubble, inside of which there is a shortened epoch of slow-roll inflation
giving today. In this paper we re-express the Bunch-Davies vacuum
for the graviton field in terms of the hyperbolic modes inside the bubble and
propagate these modes forward in time into the present era. We derive the
expression for the contribution from these gravity waves to the cosmic
microwave background anisotropy including the effect of a finite energy
difference across the bubble wall.Comment: 40 pages, TEX with phyzzx macro, 5 figure
Searches for Gravitational Waves from Binary Neutron Stars: A Review
A new generation of observatories is looking for gravitational waves. These
waves, emitted by highly relativistic systems, will open a new window for ob-
servation of the cosmos when they are detected. Among the most promising
sources of gravitational waves for these observatories are compact binaries in
the final min- utes before coalescence. In this article, we review in brief
interferometric searches for gravitational waves emitted by neutron star
binaries, including the theory, instru- mentation and methods. No detections
have been made to date. However, the best direct observational limits on
coalescence rates have been set, and instrumentation and analysis methods
continue to be refined toward the ultimate goal of defining the new field of
gravitational wave astronomy.Comment: 30 pages, 5 Figures, to appear in "Short-Period Binary Stars:
Observations, Analyses, and Results", Ed.s Eugene F. Milone, Denis A. Leahy,
David W. Hobil
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