4,183 research outputs found
NCAR telemetry and command system
The development of a pulse code modulation data encoder, a computerized ground station, and a PCM command system for obtaining and reproducing data from a balloon-borne experiment is discussed. The components of the system and the manner of operation are described. The capabilities and limitations of the system are analyzed
Improved silver-zinc battery-terminal seals
Development of battery terminal seal for sealing electrolyte for periods of three to five years is discussed. Operating conditions of battery are defined. Components of electrolyte seal and method of production are reported. Schematic diagrams of device are included
Culture Techniques for Rearing Soil Anthropods
Excerpt: Interest in soil biology has been prompted by recent investigations into the action of insecticides on plants and animals. Observations in the field must be supplemented by laboratory investigations conducted under controlled conditions. Consequently, it becomes necessary to rear and handle soil animals under artificial situations for bio-assay and life cycle studies. When large numbers of individuals are required, special problems in maintenance and manipulation arise. Relatively inexpensive and simple methods for such projects are essential and this paper describes some of those techniques which we have found expedient
An eight-month climatology of marine stratocumulus cloud fraction, albedo, and integrated liquid water
As part of the FIRE/Extended Time Observations (ETO) program, extended time observations were made at San Nicolas Island (SNI) from March to October, 1987. Hourly averages of air temperature, relative humidity, wind speed and direction, solar irradiance, and downward longwave irradiance were recorded. The radiation sensors were standard Eppley pyranometers (shortwave) and pyrgeometers (longwave). The SNI data were processed in several ways to deduce properties of the stratocumulus covered marine boundary layer (MBL). For example, from the temperature and humidity the lifting condensation level, which is an estimate of the height of the cloud bottom, can be computed. A combination of longwave irradiance statistics can be used to estimate fractional cloud cover. An analysis technique used to estimate the integrated cloud liquid water content (W) and the cloud albedo from the measured solar irradiance is also described. In this approach, the cloud transmittance is computed by dividing the irradiance measured at some time by a clear sky value obtained at the same hour on a cloudless day. From the transmittance and the zenith angle, values of cloud albedo and W are computed using the radiative transfer parameterizations of Stephens (1978). These analysis algorithms were evaluated with 17 days of simultaneous and colocated mm-wave (20.6 and 31.65 GHz) radiometer measurements of W and lidar ceilometer measurements of cloud fraction and cloudbase height made during the FIRE IFO. The algorithms are then applied to the entire data set to produce a climatology of these cloud properties for the eight month period
Recent Extreme Ultraviolet Solar Spectra and Spectroheliograms
Extreme ultraviolet solar spectra and spectroheliogram analyse
Issues in Forest Restoration: Full Cost Accounting of the 2010 Schultz Fire
The Schultz Fire of 2010 burned just over 15,000 forested acres and caused the evacuation of hundreds of homes. Heavy floods followed the fire, resulting in extensive damage to property downstream from the charred hillsides. Nearly three years later, seasonal flooding is still a concern and residents continue to live under the threat of swift floodwaters that may carve unanticipated pathways through their sloping neighborhoods.
Official reports form city, county, state, and federal governments have listed response and mitigation costs of the fire and flood at nearly 133 million and $147 million
Transient interference of transmission and incidence
Due to a transient quantum interference during a wavepacket collision with a
potential barrier, a particular momentum, that depends on the potential
parameters but is close to the initial average momentum, becomes suppressed.
The hole left pushes the momentum distribution outwards leading to a
significant constructive enhancement of lower and higher momenta. This is
explained in the momentum complex-plane language in terms of a saddle point and
two contiguous ``structural'' poles, which are not associated with resonances
but with incident and transmitted components of the wavefunction.Comment: 4 pages of text, 6 postscript figures, revte
Classical Limit of Demagnetization in a Field Gradient
We calculate the rate of decrease of the expectation value of the transverse
component of spin for spin-1/2 particles in a magnetic field with a spatial
gradient, to determine the conditions under which a previous classical
description is valid. A density matrix treatment is required for two reasons.
The first arises because the particles initially are not in a pure state due to
thermal motion. The second reason is that each particle interacts with the
magnetic field and the other particles, with the latter taken to be via a
2-body central force. The equations for the 1-body Wigner distribution
functions are written in a general manner, and the places where quantum
mechanical effects can play a role are identified. One that may not have been
considered previously concerns the momentum associated with the magnetic field
gradient, which is proportional to the time integral of the gradient. Its
relative magnitude compared with the important momenta in the problem is a
significant parameter, and if their ratio is not small some non-classical
effects contribute to the solution.
Assuming the field gradient is sufficiently small, and a number of other
inequalities are satisfied involving the mean wavelength, range of the force,
and the mean separation between particles, we solve the integro- partial
differential equations for the Wigner functions to second order in the strength
of the gradient. When the same reasoning is applied to a different problem with
no field gradient, but having instead a gradient to the z-component of
polarization, the connection with the diffusion coefficient is established, and
we find agreement with the classical result for the rate of decrease of the
transverse component of magnetization.Comment: 22 pages, no figure
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