29,179 research outputs found
EKG isolator
Light beam transmits heartbeat signal from electrodes on patient to electrocardiograph without exposing patient to possible severe electrical shock. System provides complete isolation between patient and EKG instrumentation
Cogeneration Technology Alternatives Study (CTAS). Volume 3: Industrial processes
Cogenerating electric power and process heat in single energy conversion systems rather than separately in utility plants and in process boilers is examined in terms of cost savings. The use of various advanced energy conversion systems are examined and compared with each other and with current technology systems for their savings in fuel energy, costs, and emissions in individual plants and on a national level. About fifty industrial processes from the target energy consuming sectors were used as a basis for matching a similar number of energy conversion systems that are considered as candidate which can be made available by the 1985 to 2000 time period. The sectors considered included food, textiles, lumber, paper, chemicals, petroleum, glass, and primary metals. The energy conversion systems included steam and gas turbines, diesels, thermionics, stirling, closed cycle and steam injected gas turbines, and fuel cells. Fuels considered were coal, both coal and petroleum based residual and distillate liquid fuels, and low Btu gas obtained through the on site gasification of coal. An attempt was made to use consistent assumptions and a consistent set of ground rules specified by NASA for determining performance and cost. Data and narrative descriptions of the industrial processes are given
Determination of the radionuclide content of feces and urine from astronauts engaged in space flight
Measurement of radiation exposure of Apollo 7, 8, 9, and 10 astronauts by determination of radionuclide content of feces and urin
Developmental design, fabrication, and test of acoustic suppressors for fans of high bypass turbofan engines
An analysis procedure was developed for design of acoustically treated nacelles for high bypass turbofan engines. The plan was applied to the conceptual design of a nacelle for the quiet engine typical of a 707/DC-8 airplane installation. The resultant design was modified to a test nacelle design for the NASA Lewis quiet fan. The acoustic design goal was a 10 db reduction in effective perceived fan noise levels during takoff and approach. Detailed nacelle designs were subsequently developed for both the quiet engine and the quiet fan. The acoustic design goal for each nacelle was 15 db reductions in perceived fan noise levels from the inlet and fan duct. Acoustically treated nacelles were fabricated for the quiet engine and quiet fan for testing. Performance of selected inlet and fan duct lining configurations was experimentally evaluated in a flow duct. Results of the tests show that the linings perform as designed
Verification of computer-aided designs of traveling-wave tubes utilizing novel dynamic refocusers and graphite electrodes for the multistage depressed collector
A computational procedure for the design of TWT-refocuser-MDC systems was used to design a short dynamic refocusing system and highly efficient four-stage depressed collector for a 200-W, 8- to 18-GHz, TWT. The computations were carried out with advanced, multidimensional computer programs which model the electron beam as a series of disks of charge and follow their trajectories from the RF input of the TWT, through the slow-wave structure and refocusing section, to their points of impact in the depressed collector. Secondary emission losses in the MDC were treated semi-quantitatively by injecting a representative beam of secondary electrons into the MDC analysis at the point of impact of each primary beam. A comparison of computed and measured TWT and MDC performance showed very good agreement. The electrodes of the MDC were fabricated from a particular form of isotropic graphite that was selected for its low secondary electron yield, ease of machinability, and vacuum properties. This MDC was tested (at CW) for more than 1000 hr with negligible degradation in TWT and MDC performances
Ab Initio Liquid Hydrogen Muon Cooling Simulations with ELMS in ICOOL
This paper presents new theoretical results on the passage of muons through
liquid hydrogen which have been confirmed in a recent experiment. These are
used to demonstrate that muon bunches may be compressed by ionisation cooling
more effectively than suggested by previous calculations.
Muon cooling depends on the differential cross section for energy loss and
scattering of muons. We have calculated this cross section for liquid H2 from
first principles and atomic data, avoiding traditional assumptions. Thence, 2-D
probability maps of energy loss and scattering in mm-scale thicknesses are
derived by folding, and stored in a database. Large first-order correlations
between energy loss and scattering are found for H2, which are absent in other
simulations. This code is named ELMS, Energy Loss & Multiple Scattering. Single
particle trajectories may then be tracked by Monte Carlo sampling from this
database on a scale of 1 mm or less. This processor has been inserted into the
cooling code ICOOL. Significant improvements in 6-D muon cooling are predicted
compared with previous predictions based on GEANT. This is examined in various
geometries. The large correlation effect is found to have only a small effect
on cooling. The experimental scattering observed for liquid H2 in the MUSCAT
experiment has recently been reported to be in good agreement with the ELMS
prediction, but in poor agreement with GEANT simulation.Comment: 6 pages, 3 figure
Splitting hairs of the three charge black hole
We construct the large radius limit of the metric of three charge supertubes
and three charge BPS black rings by using the fact that supertubes preserve the
same supersymmetries as their component branes. Our solutions reproduce a few
of the properties of three charge supertubes found recently using the Born
Infeld description. Moreover, we find that these solutions pass a number of
rather nontrivial tests which they should pass if they are to describe some of
the hair of three charge black holes and three charge black rings.Comment: 15 pages, LaTeX, v2 minor correction
Cosmic Ray Propagation: Nonlinear Diffusion Parallel and Perpendicular to Mean Magnetic Field
We consider the propagation of cosmic rays in turbulent magnetic fields. We
use the models of magnetohydrodynamic turbulence that were tested in numerical
simulations, in which the turbulence is injected on large scale and cascades to
small scales. Our attention is focused on the models of the strong turbulence,
but we also briefly discuss the effects that the weak turbulence and the slab
Alfv\'enic perturbations can have. The latter are likely to emerge as a result
of instabilities with in the cosmic ray fluid itself, e.g., beaming and
gyroresonance instabilities of cosmic rays. To describe the interaction of
cosmic rays with magnetic perturbations we develop a non-linear formalism that
extends the ordinary Quasi-Linear Theory (QLT) that is routinely used for the
purpose. This allows us to avoid the usual problem of 90 degree scattering and
enable our computation of the mean free path of cosmic rays. We apply the
formalism to the cosmic ray propagation in the galactic halo and in the Warm
Ionized medium (WIM). In addition, we address the issue of the transport of
cosmic rays perpendicular to the mean magnetic field and show that the issue of
cosmic ray subdiffusion (i.e., propagation with retracing the trajectories
backwards, which slows down the diffusion) is only important for restricted
cases when the ambient turbulence is far from what numerical simulations
suggest to us. As a result, this work provides formalism that can be applied
for calculating cosmic ray propagation in a wide variety of circumstances.Comment: minor changes, accepted to Ap
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