18,588 research outputs found
Precision voltage regulator
Balanced positive and negative voltage output circuit, in which error voltage for control is developed from difference in absolute value of positive and negative voltages referenced to a common point, regulates voltage for use with inertial reference unit. Fast-acting, temperature-compensated, high-gain operational amplifier circuits maintain common point
Science and Applications Space Platform (SASP) End-to-End Data System Study
The capability of present technology and the Tracking and Data Relay Satellite System (TDRSS) to accommodate Science and Applications Space Platforms (SASP) payload user's requirements, maximum service to the user through optimization of the SASP Onboard Command and Data Management System, and the ability and availability of new technology to accommodate the evolution of SASP payloads were assessed. Key technology items identified to accommodate payloads on a SASP were onboard storage devices, multiplexers, and onboard data processors. The primary driver is the limited access to TDRSS for single access channels due to sharing with all the low Earth orbit spacecraft plus shuttle. Advantages of onboard data processing include long term storage of processed data until TRDSS is accessible, thus reducing the loss of data, eliminating large data processing tasks at the ground stations, and providing a more timely access to the data
Heat sterilizable Ni-Cd battery development Quarterly report, 1 Apr. - 30 Jun. 1968
Development of heat sterilizable, hermetically sealed nickel cadmium batteries for space application
A least squares method for the reduction of free-oscillation data
Least squares determination of frequency, damping ratio, amplitude, and phase angle from free oscillation dat
Electronic integrator for gyro rate output voltages
Circuit which integrates spacecraft gyro output voltages to provide analog position signals has been developed. Accurate integration is provided by all solid state system which uses no choppers and takes advantage of commercially available flight qualified components
Residual magnetism holds solenoid armature in desired position
Holding solenoid uses residual magnetism to hold its armature in a desired position after excitation current is removed from the coil. Although no electrical power or mechanical devices are used, the solenoid has a low tolerance to armature displacement from the equilibrium position
The School of the Future
An article from the June 1920 issue of Popular Educator, about the consolidation of rural schools in the Midwest.https://scholarworks.uni.edu/education_history/1001/thumbnail.jp
Net energy analysis of solar and conventional domestic hot water systems in Melbourne, Australia
It is commonly assumed that solar hot water systems save energy and reduce greenhouse gas emissions. Very rarely has the life-cycle energy requirements of solar hot water systems been analysed, including their embodied energy. The extent to which solar hot water systems save energy compared to conventional systems in Melbourne, Australia, is shown through a comparative net energy analysis. The solar systems provided a net energy saving compared to the conventional systems after 0.5 to 2 years, for electricity and gas systems respectively.<br /
The Velocity Distribution of the Nearest Interstellar Gas
The bulk flow velocity for the cluster of interstellar cloudlets within about
30 pc of the Sun is determined from optical and ultraviolet absorption line
data, after omitting from the sample stars with circumstellar disks or variable
emission lines and the active variable HR 1099. Ninety-six velocity components
towards the remaining 60 stars yield a streaming velocity through the local
standard of rest of -17.0+/-4.6 km/s, with an upstream direction of l=2.3 deg,
b=-5.2 deg (using Hipparcos values for the solar apex motion). The velocity
dispersion of the interstellar matter (ISM) within 30 pc is consistent with
that of nearby diffuse clouds, but present statistics are inadequate to
distinguish between a Gaussian or exponential distribution about the bulk flow
velocity. The upstream direction of the bulk flow vector suggests an origin
associated with the Loop I supernova remnant. Groupings of component velocities
by region are seen, indicating regional departures from the bulk flow velocity
or possibly separate clouds. The absorption components from the cloudlet
feeding ISM into the solar system form one of the regional features. The
nominal gradient between the velocities of upstream and downstream gas may be
an artifact of the Sun's location near the edge of the local cloud complex. The
Sun may emerge from the surrounding gas-patch within several thousand years.Comment: Typographical errors corrected; Five tables, seven figures;
Astrophysical Journal, in pres
Universal trapping scaling on the unstable manifold for a collisionless electrostatic mode
An amplitude equation for an unstable mode in a collisionless plasma is
derived from the dynamics on the two-dimensional unstable manifold of the
equilibrium. The mode amplitude decouples from the phase due to the
spatial homogeneity of the equilibrium, and the resulting one-dimensional
dynamics is analyzed using an expansion in . As the linear growth rate
vanishes, the expansion coefficients diverge; a rescaling
of the mode amplitude absorbs these
singularities and reveals that the mode electric field exhibits trapping
scaling as . The dynamics for
depends only on the phase where is the derivative of the dielectric as
.Comment: 11 pages (Latex/RevTex), 2 figures available in hard copy from the
Author ([email protected]); paper accepted by Physical Review
Letter
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