65,976 research outputs found
Active experiments using rocket-borne shaped charge barium releases
A reliable payload system and scaled down shaped charges were developed for carrying out experiments in solar-terrestrial magnetospheric physics. Four Nike-Tomahawk flights with apogees near 450 km were conducted to investigate magnetospheric electric fields, and two Taurus-Tomahawk rockets were flown in experiments on the auroral acceleration process in discrete auroras. In addition, a radial shaped charge was designed for plasma perturbation experiments
AMPS definition study on Optical Band Imager and Photometer System (OBIPS)
A study was conducted to define the characteristics of a modular optical diagnostic system (OBIPS) for AMPS, to provide input to Phase B studies, and to give information useful for experiment planning and design of other instrumentation. The system described consists of visual and UV-band imagers and visual and UV-band photometers; of these the imagers are most important because of their ability to measure intensity as a function of two spatial dimensions and time with high resolution. The various subsystems of OBIPS are in themselves modular with modules having a high degree of interchangeability for versatility, economy, and redundancy
Stability of string defects in models of non-Abelian symmetry breaking
In this paper we describe a new type of topological defect, called a homilia
string, which is stabilized via interactions with the string network. Using
analytical and numerical techniques, we investigate the stability and dynamics
of homilia strings, and show that they can form stable electroweak strings. In
SU(2)xU(1) models of symmetry breaking the intersection of two homilia strings
is identified with a sphaleron. Due to repulsive forces, the homilia strings
seperate, resulting in sphaleron annihilation. It is shown that electroweak
homilia string loops cannot stabilize as vortons, which circumvents the adverse
cosmological problems associated with stable loops. The consequences for GUT
scale homilia strings are also discussed.Comment: 15 pages, revtex, with 8 figures. Submitted to PR
Nonlocal symmetries of Riccati and Abel chains and their similarity reductions
We study nonlocal symmetries and their similarity reductions of Riccati and
Abel chains. Our results show that all the equations in Riccati chain share the
same form of nonlocal symmetry. The similarity reduced order ordinary
differential equation (ODE), , in this chain yields
order ODE in the same chain. All the equations in the Abel chain also share the
same form of nonlocal symmetry (which is different from the one that exist in
Riccati chain) but the similarity reduced order ODE, , in
the Abel chain always ends at the order ODE in the Riccati chain.
We describe the method of finding general solution of all the equations that
appear in these chains from the nonlocal symmetry.Comment: Accepted for publication in J. Math. Phy
Universal Behavior in Large-scale Aggregation of Independent Noisy Observations
Aggregation of noisy observations involves a difficult tradeoff between
observation quality, which can be increased by increasing the number of
observations, and aggregation quality which decreases if the number of
observations is too large. We clarify this behavior for a protypical system in
which arbitrarily large numbers of observations exceeding the system capacity
can be aggregated using lossy data compression. We show the existence of a
scaling relation between the collective error and the system capacity, and show
that large scale lossy aggregation can outperform lossless aggregation above a
critical level of observation noise. Further, we show that universal results
for scaling and critical value of noise which are independent of system
capacity can be obtained by considering asymptotic behavior when the system
capacity increases toward infinity.Comment: 10 pages, 3 figure
Gravitational radiation from infall into a black hole: Regularization of the Teukolsky equation
The Teukolsky equation has long been known to lead to divergent integrals
when it is used to calculate the gravitational radiation emitted when a test
mass falls into a black hole from infinity. Two methods have been used in the
past to remove those divergent integrals. In the first, integrations by parts
are carried out, and the infinite boundary terms are simply discarded. In the
second, the Teukolsky equation is transformed into another equation which does
not lead to divergent integrals. The purpose of this paper is to show that
there is nothing intrinsically wrong with the Teukolsky equation when dealing
with non-compact source terms, and that the divergent integrals result simply
from an incorrect choice of Green's function. In this paper, regularization of
the Teukolsky equation is carried out in an entirely natural way which does not
involve modifying the equation.Comment: ReVTeX, 23 page
Milk Marketing Orders: Who Wins and Who Loses?
Livestock Production/Industries, Marketing, Q13, Q18,
Crop identification technology assessment for remote sensing (CITARS). Volume 6: Data processing at the laboratory for applications of remote sensing
The results of classifications and experiments for the crop identification technology assessment for remote sensing are summarized. Using two analysis procedures, 15 data sets were classified. One procedure used class weights while the other assumed equal probabilities of occurrence for all classes. Additionally, 20 data sets were classified using training statistics from another segment or date. The classification and proportion estimation results of the local and nonlocal classifications are reported. Data also describe several other experiments to provide additional understanding of the results of the crop identification technology assessment for remote sensing. These experiments investigated alternative analysis procedures, training set selection and size, effects of multitemporal registration, spectral discriminability of corn, soybeans, and other, and analyses of aircraft multispectral data
Milk Marketing Order Winners and Losers
Do milk marketing orders affect various demographic groups differently? To answer this question, we use supermarket scanner data to estimate an incomplete demand system for dairy products. Based on these estimates, we simulate substitution effects among dairy products and the welfare impacts of price changes resulting from changes in milk marketing orders for various consumer groups. While we find little difference in own- and cross-price substitution elasticities of demand, the welfare effects of price changes vary substantially across demographic groups, with some losing and others winning from this government program. Families with young children suffer from marketing orders, while wealthier childless couples benefit. Additionally, we find that households with lower incomes pay a larger percentage of their income due to marketing orders than those with higher income levels.Consumer/Household Economics,
Crop Identification Technology Assessment for Remote Sensing (CITARS)
The results of classifications and experiments performed for the Crop Identification Technology Assessment for Remote Sensing (CITARS) project are summarized. Fifteen data sets were classified using two analysis procedures. One procedure used class weights while the other assumed equal probabilities of occurrence for all classes. In addition, 20 data sets were classified using training statistics from another segment or date. The results of both the local and non-local classifications in terms of classification and proportion estimation are presented. Several additional experiments are described which were performed to provide additional understanding of the CITARS results. These experiments investigated alternative analysis procedures, training set selection and size, effects of multitemporal registration, the spectral discriminability of corn, soybeans, and other, and analysis of aircraft multispectral data
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