429 research outputs found
Test and evaluate passive orbital disconnect struts (PODS 3)
The objectives of the Passive Orbital Disconnect Struts (PODS) test are to evaluate modal resonance of the PODS-III supports to obtain engineering data required for use of PODS-III on flight systems; determine possible performance improvements in large LO2/LH2 space applications. (1) Modal Vibration Tests. A modal resonance survey is performed on a set of six PODS-III struts assembled in a dewar simulator. The survey conditions simulate both launch and orbital loadings of the struts. The orbital load range spans a full to an empty tank. The frequencies surveyed cover the range consistent with Shuttle qualification requirements and the principal resonant modes of the strut system. (2) Benefit study. The benefit of using PODS-III supports on OTV and Space Station LO sub 2 and LH sub 2 reference tanks was compared to nondisconnect supports. Four LO sub 2 and LH sub 2 tanks were studied under various conditions: (1) holding the launch resonance at 35 Hz and varying the orbit resonance; (2) analyzing both full and emtpy tanks at launch; (3) varying orbit boundary temperaure; (4) varying the number of struts; (5) varying orbit times; and (6) using or not using vapor cooling
Identifying Intimate Partner Violence: A Review of Three Measures for Implementation in Primary Care Settings
KRb Feshbach Resonances: Modeling the interatomic potential
We have observed 28 heteronuclear Feshbach resonances in 10 spin combinations
of the hyperfine ground states of a 40K 87Rb mixture. The measurements were
performed by observing the loss rates from an atomic mixture at magnetic fields
between 0 and 700 G. This data was used to significantly refine an interatomic
potential derived from molecular spectroscopy, yielding a highly consistent
model of the KRb interaction. Thus, the measured resonances can be assigned to
the corresponding molecular states. In addition, this potential allows for an
accurate calculation of the energy differences between highly excited levels
and the rovibrational ground level. This information is of particular relevance
for the formation of deeply bound heteronuclear molecules. Finally, the model
is used to predict Feshbach resonances in mixtures of 87Rb combined with 39K or
41K.Comment: 4 pages, 3 figure
Radio frequency association of heteronuclear Feshbach molecules
We present a detailed analysis of the production efficiency of weakly bound
heteronuclear KRb-Feshbach molecules using radio frequency association in a
harmonic trap. The efficiency was measured in a wide range of temperatures,
binding energies and radio frequencies. A comprehensive analytical model is
presented, explaining the observed asymmetric spectra and achieving good
quantitative agreement with the measured production rates. This model provides
a deep understanding of the molecule association process and paves the way for
future experiments which rely on Feshbach molecules e.g. for the production of
deeply bound molecules.Comment: 5 pages, 4 figure
Parametric amplification of vacuum fluctuations in a spinor condensate
Parametric amplification of vacuum fluctuations is crucial in modern quantum
optics, enabling the creation of squeezing and entanglement. We demonstrate the
parametric amplification of vacuum fluctuations for matter waves using a spinor
F=2 Rb-87 condensate. Interatomic interactions lead to correlated pair creation
in the m_F= +/- 1 states from an initial unstable m_F=0 condensate, which acts
as a vacuum for m_F unequal 0. Although this pair creation from a pure m_F=0
condensate is ideally triggered by vacuum fluctuations, unavoidable spurious
initial m_F= +/- 1 atoms induce a classical seed which may become the dominant
triggering mechanism. We show that pair creation is insensitive to a classical
seed for sufficiently large magnetic fields, demonstrating the dominant role of
vacuum fluctuations. The presented system thus provides a direct path towards
the generation of non-classical states of matter on the basis of spinor
condensates.Comment: 5 pages, 4 figure
Active synthetic soil
A synthetic soil/fertilizer for horticultural application having all the agronutrients essential for plant growth is disclosed. The soil comprises a synthetic apatite fertilizer having sulfur, magnesium, and micronutrients dispersed in a calcium phosphate matrix, a zeolite cation exchange medium saturated with a charge of potassium and nitrogen cations, and an optional pH buffer. Moisture dissolves the apatite and mobilizes the nutrient elements from the apatite matrix and the zeolite charge sites
Sum index and difference index of graphs
Let be a nonempty simple graph with a vertex set and an edge set
. For every injective vertex labeling , there are
two induced edge labelings, namely defined by
, and defined by
. The sum index and the difference index are the minimum
cardinalities of the ranges of and , respectively. We provide upper
and lower bounds on the sum index and difference index, and determine the sum
index and difference index of various families of graphs. We also provide an
interesting conjecture relating the sum index and the difference index of
graphs
Multi-resonant spinor dynamics in a Bose-Einstein condensate
We analyze the spinor dynamics of a Rb-87 F=2 condensate initially prepared
in the m_F=0 Zeeman sublevel. We show that this dynamics, characterized by the
creation of correlated atomic pairs in m_F=+/-1, presents an intriguing
multi-resonant magnetic field dependence induced by the trap inhomogeneity.
This dependence is directly linked to the most unstable Bogoliubov spin
excitations of the initial m_F = 0 condensate, showing that, in general, even a
qualitative understanding of the pair creation efficiency in a spinor
condensate requires a careful consideration of the confinement.Comment: 5 pages, 4 figure
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