20,433 research outputs found
Two dimensional recursive digital filters for near real time image processing
A program was designed toward the demonstration of the feasibility of using two dimensional recursive digital filters for subjective image processing applications that require rapid turn around. The concept of the use of a dedicated minicomputer for the processor for this application was demonstrated. The minicomputer used was the HP1000 series E with a RTE 2 disc operating system and 32K words of memory. A Grinnel 256 x 512 x 8 bit display system was used to display the images. Sample images were provided by NASA Goddard on a 800 BPI, 9 track tape. Four 512 x 512 images representing 4 spectral regions of the same scene were provided. These images were filtered with enhancement filters developed during this effort
New GOES satellite synchronized time code generation
The TRAK Systems' GOES Satellite Synchronized Time Code Generator is described. TRAK Systems has developed this timing instrument to supply improved accuracy over most existing GOES receiver clocks. A classical time code generator is integrated with a GOES receiver
Aerodynamic characteristics of the 40- by 80/80- by 120-foot wind tunnel at NASA Ames Research Center
The design and testing of vane sets and air-exchange inlet for the 40 x 80/80 x 120-ft wind tunnel at NASA Ames are reported. Boundary-layer analysis and 2D and 3D inviscid panel codes are employed in computer models of the system, and a 1/10-scale 2D facility and a 1/50-scale 3D model of the entire wind tunnel are used in experimental testing of the vane sets. The results are presented in graphs, photographs, drawings, and diagrams are discussed. Generally good agreement is found between the predicted and measured performance
A connection between the Camassa-Holm equations and turbulent flows in channels and pipes
In this paper we discuss recent progress in using the Camassa-Holm equations
to model turbulent flows. The Camassa-Holm equations, given their special
geometric and physical properties, appear particularly well suited for studying
turbulent flows. We identify the steady solution of the Camassa-Holm equation
with the mean flow of the Reynolds equation and compare the results with
empirical data for turbulent flows in channels and pipes. The data suggests
that the constant version of the Camassa-Holm equations, derived under
the assumptions that the fluctuation statistics are isotropic and homogeneous,
holds to order distance from the boundaries. Near a boundary, these
assumptions are no longer valid and the length scale is seen to depend
on the distance to the nearest wall. Thus, a turbulent flow is divided into two
regions: the constant region away from boundaries, and the near wall
region. In the near wall region, Reynolds number scaling conditions imply that
decreases as Reynolds number increases. Away from boundaries, these
scaling conditions imply is independent of Reynolds number. Given the
agreement with empirical and numerical data, our current work indicates that
the Camassa-Holm equations provide a promising theoretical framework from which
to understand some turbulent flows.Comment: tex file, 29 pages, 4 figures, Physics of Fluids (in press
High-performance light-weight electrodes for hydrogen-oxygen fuel cells
High performance light weight electrodes for hydrogen oxygen fuel cell
Imperfect identity
Questions of identity over time are often hard to answer. A long
tradition has it that such questions are somehow soft: they have no unique,
determinate answer, and disagreements about them are merely verbal. I
argue that this claim is not the truism it is taken to be. Depending on how
it is understood, it turns out either to be false or to presuppose a highly
contentious metaphysical claim
N, L Distributions For Electron-Capture From H(1s) By C⁶⁺and O8+
Total cross sections for electron-capture from the ground state of hydrogen by C6+(40, 50, 60, 80, 100 and 120 keV/u) and O8+(40, 50, 60, 80, 100, 120 and 140keV/u) have been calculated using the classical-trajectory Monte Carlo (CTMC) technique. We tabulate these cross sections as a function of projectile energy for (i) capture to all product states, (ii) capture to product n-levels, and (iii) capture to product n, l-levels. The results of these calculations agree with and extend previous CTMC n, ldistribution results. © 1989 IOP Publishing Ltd
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