7,639 research outputs found
Barium release system
A chemical system is described for releasing a good yield of free barium neutral atoms and barium ions in the upper atmosphere and interplanetary space for the study of the geophysical properties of the medium. The barium is released in the vapor phase so that it can be ionized by solar radiation and also be excited to emit resonance radiation in the visible range. The ionized luminous cloud of barium becomes a visible indication of magnetic and electrical characteristics in space and allows determination of these properties over relatively large areas at a given time
Rocket having barium release system to create ion clouds in the upper atmosphere
A chemical system for releasing a good yield of free barium atoms and barium ions to create ion clouds in the upper atmosphere and interplanetary space for the study of the geophysical properties of the medium is presented
Structural assembly in space
A cost algorithm for predicting assembly costs for large space structures is given. Assembly scenarios are summarized which describe the erection, deployment, and fabrication tasks for five large space structures. The major activities that impact total costs for structure assembly from launch through deployment and assembly to scientific instrument installation and checkout are described. Individual cost elements such as assembly fixtures, handrails, or remote minipulators are also presented
Design criteria for payload workstation accommodations
Anticipated shuttle sortie payload man-system design criteria needs are investigated. Man-system interactions for the scientific disciplines are listed and the extent is assessed to which documented Skylab experience is expected to provide system design guidance for each of the identified interactions. Where the analysis revealed that the reduced Skylab data does not answer the anticipated needs candidate criteria, based on unreduced Skylab data, available prior research, original analysis, or related requirements derived from previous space programs, are provided
COPTRAN - A method of optimum communication systems design
Single set of mathematical expressions describes system cost and probability of error of data transmission in terms of four basic parameters in the link equation. A Lagrange multiplier sets up equations whose solutions yield the optimum values for system design considerations and weight and cost values
Dosimetry for radiobiological studies of the human hematopoietic system
A system for estimating individual bone marrow doses in therapeutic radiation exposures of leukemia patients was studied. These measurements are used to make dose response correlations and to study the effect of dose protraction on peripheral blood cell levels. Three irradiators designed to produce a uniform field of high energy gamma radiation for total body exposures of large animals and man are also used for radiobiological studies
Efficient numerical solution of the time fractional diffusion equation by mapping from its Brownian counterpart
The solution of a Caputo time fractional diffusion equation of order
is expressed in terms of the solution of a corresponding integer
order diffusion equation. We demonstrate a linear time mapping between these
solutions that allows for accelerated computation of the solution of the
fractional order problem. In the context of an -point finite difference time
discretisation, the mapping allows for an improvement in time computational
complexity from to , given a
precomputation of . The mapping is applied
successfully to the least-squares fitting of a fractional advection diffusion
model for the current in a time-of-flight experiment, resulting in a
computational speed up in the range of one to three orders of magnitude for
realistic problem sizes.Comment: 9 pages, 5 figures; added references for section
Generalised balance equations for charged particle transport via localised and delocalised states: Mobility, generalised Einstein relations and fractional transport
A generalised phase-space kinetic Boltzmann equation for highly
non-equilibrium charged particle transport via localised and delocalised states
is used to develop continuity, momentum and energy balance equations,
accounting explicitly for scattering, trapping/detrapping and recombination
loss processes. Analytic expressions detail the effect of these microscopic
processes on the mobility and diffusivity. Generalised Einstein relations (GER)
are developed that enable the anisotropic nature of diffusion to be determined
in terms of the measured field-dependence of the mobility. Interesting
phenomena such as negative differential conductivity and recombination
heating/cooling are shown to arise from recombination loss processes and the
localised and delocalised nature of transport. Fractional transport emerges
naturally within this framework through the appropriate choice of divergent
mean waiting time distributions for localised states, and fractional
generalisations of the GER and mobility are presented. Signature impacts on
time-of-flight current transients of recombination loss processes via both
localised and delocalised states are presented.Comment: 21 pages, 4 figure
- …