18,395 research outputs found
Tungsten-rhenium alloy thermocouples effective for high-temperature measurement
Tungsten-rhenium alloy thermocouples, specifically, insulated, sheathed W/W plus 26Re and W plus 5 Re/W plus 26 Re thermocouples, are effective for temperature measurement in excess of 2920 degrees C. These thermocouples have a high thermoelectric output and excellent relationship to temperatures up to 2760 degrees C
The cognitive demands of second order manual control: Applications of the event related brain potential
Three experiments are described in which tracking difficulty is varied in the presence of a covert tone discrimination task. Event related brain potentials (ERPs) elicited by the tones are employed as an index of the resource demands of tracking. The ERP measure reflected the control order variation, and this variable was thereby assumed to compete for perceptual/central processing resources. A fine-grained analysis of the results suggested that the primary demands of second order tracking involve the central processing operations of maintaining a more complex internal model of the dynamic system, rather than the perceptual demands of higher derivative perception. Experiment 3 varied tracking bandwidth in random input tracking, and the ERP was unaffected. Bandwidth was then inferred to compete for response-related processing resources that are independent of the ERP
An investigation of pulsar searching techniques with the Fast Folding Algorithm
Here we present an in-depth study of the behaviour of the Fast Folding
Algorithm, an alternative pulsar searching technique to the Fast Fourier
Transform. Weaknesses in the Fast Fourier Transform, including a susceptibility
to red noise, leave it insensitive to pulsars with long rotational periods (P >
1 s). This sensitivity gap has the potential to bias our understanding of the
period distribution of the pulsar population. The Fast Folding Algorithm, a
time-domain based pulsar searching technique, has the potential to overcome
some of these biases. Modern distributed-computing frameworks now allow for the
application of this algorithm to all-sky blind pulsar surveys for the first
time. However, many aspects of the behaviour of this search technique remain
poorly understood, including its responsiveness to variations in pulse shape
and the presence of red noise. Using a custom CPU-based implementation of the
Fast Folding Algorithm, ffancy, we have conducted an in-depth study into the
behaviour of the Fast Folding Algorithm in both an ideal, white noise regime as
well as a trial on observational data from the HTRU-S Low Latitude pulsar
survey, including a comparison to the behaviour of the Fast Fourier Transform.
We are able to both confirm and expand upon earlier studies that demonstrate
the ability of the Fast Folding Algorithm to outperform the Fast Fourier
Transform under ideal white noise conditions, and demonstrate a significant
improvement in sensitivity to long-period pulsars in real observational data
through the use of the Fast Folding Algorithm.Comment: 19 pages, 15 figures, 3 table
Mixed Symmetry Solutions of Generalized Three-Particle Bargmann-Wigner Equations in the Strong-Coupling Limit
Starting from a nonlinear isospinor-spinor field equation, generalized
three-particle Bargmann-Wigner equations are derived. In the strong-coupling
limit, a special class of spin 1/2 bound-states are calculated. These solutions
which are antisymmetric with respect to all indices, have mixed symmetries in
isospin-superspin space and in spin orbit space. As a consequence of this mixed
symmetry, we get three solution manifolds. In appendix \ref{b}, table 2, these
solution manifolds are interpreted as the three generations of leptons and
quarks. This interpretation will be justified in a forthcoming paper.Comment: 17 page
Apollo-11 lunar sample information catalogue
The Apollo 11 mission is reviewed with emphasis on the collection of lunar samples, their geologic setting, early processing, and preliminary examination. The experience gained during five subsequent missions was applied to obtain physical-chemical data for each sample using photographic and binocular microscope techniques. Topics discussed include: binocular examination procedure; breccia clast dexrriptuons, thin section examinations procedure typical breccia in thin section, typical basalt in thin section, sample histories, and chemical and age data. An index to photographs is included
CF6-6D engine short-term performance deterioration
Studies conducted as part of the NASA-Lewis CF6 jet engine diagnostics program are summarized. An 82-engine sample of DC-10-10 aircraft engine checkout data that were gathered to define the extent and magnitude of CF6-6D short term performance deterioration were analyzed. These data are substantiated by the performance testing and analytical teardown of CF6-6D short term deterioration engine serial number (ESN) 451507
CF6-6D engine performance deterioration
Cruise cockpit recordings and test cell performance data in conjunction with hardware inspection data from airline overhaul shops were analyzed to define the extent and magnitude of performance deterioration of the General Electric CF6-6D model engine. These studies successfully isolated short-term deterioration from the longer term, and defined areas where a significant reduction in aircraft energy requirements for the 1980's can be realized. Unrestored losses which remain after engine refurbishment represent over 70% of the loss at engine shop visit. Sixty-three percent of the unrestored losses are cost-effective to restore which could reduce fuel consumed by CF6-6D engines in 1980 by 10.9 million gallons
New Non-Diagonal Singularity-Free Cosmological Perfect-Fluid Solution
We present a new non-diagonal G2 inhomogeneous perfect-fluid solution with
barotropic equation of state p=rho and positive density everywhere. It
satisfies the global hyperbolicity condition and has no curvature singularity
anywhere. This solution is very simple in form and has two arbitrary constants.Comment: Latex, no figure
A Novel Bacterial Silage Additive Effective Against Clostridial Fermentation
Silage quality is determined by factors including the content of butyric acid and ammonium-N. These parameters have to be restricted especially in lightly wilted silages due to a higher risk of clostridia contamination. In this study a novel silage additive was tested in grass silages of low dry matter content. The objective of this experiment was to explore the effect of the silage additive on quality parameters in comparison to an untreated control
Stress condensation in crushed elastic manifolds
We discuss an M-dimensional phantom elastic manifold of linear size L crushed
into a small sphere of radius R << L in N-dimensional space. We investigate the
low elastic energy states of 2-sheets (M=2) and 3-sheets (M=3) using analytic
methods and lattice simulations. When N \geq 2M the curvature energy is
uniformly distributed in the sheet and the strain energy is negligible. But
when N=M+1 and M>1, both energies appear to be condensed into a network of
narrow M-1 dimensional ridges. The ridges appear straight over distances
comparable to the confining radius R.Comment: 4 pages, RevTeX + epsf, 4 figures, Submitted to Phys. Rev. Let
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