2,436 research outputs found
Suppression of combustion oscillations with mechanical devices Interim report
Static rocket thrust chamber simulator for cylindrical cold flow-type apparatus desig
Circuit QED and sudden phase switching in a superconducting qubit array
Superconducting qubits connected in an array can form quantum many-body
systems such as the quantum Ising model. By coupling the qubits to a
superconducting resonator, the combined system forms a circuit QED system.
Here, we study the nonlinear behavior in the many-body state of the qubit array
using a semiclassical approach. We show that sudden switchings as well as a
bistable regime between the ferromagnetic phase and the paramagnetic phase can
be observed in the qubit array. A superconducting circuit to implement this
system is presented with realistic parameters .Comment: 4 pages, 3 figures, submitted for publication
Flow of nitrogen-pressurized Halon 1301 in fire extinguishing systems
Halon 1301 which is a halocarbon fire extinguishing agent (CBrF3) used by the U.S. Army for vehicle fire suppression is discussed. Halon 1301 is discharged under nitrogen pressure, and the Halon-nitrogen mixture is a two phase, two component mixture that obeys compressible fluid laws and exhibits choking effects. A computer model was developed to analyze the discharge of Halon and nitrogen from a storage bottle through pipes and nozzles. The model agrees well with data from Halon 1301 discharge tests. The discharge time depends mainly on nozzle area and pipe volume, for given initial conditions. Graphs were developed for estimating discharge times. A nozzle employing multiple concentric converging/diverging nozzles was developed which gave hemispherical coverage
Rotational spectroscopy of AlO: Low N transitions of astronomical interest in the X^2 Sigma^+ state
The detection of rotational transitions of the AlO radical at millimeter
wavelengths from an astronomical source has recently been reported. In view of
this, rotational transitions in the ground X^2 Sigma^+ state of AlO have been
reinvestigated. Comparisons between Fourier transform and microwave data
indicate a discrepancy regarding the derived value of gamma_D in the v = 0
level of the ground state. This discrepancy is discussed in the light of
comparisons between experimental data and synthesized rotational spectra in the
v = 0, 1 and 2 levels of X^2 Sigma^+. A list of calculated rotational lines in
v = 0, 1 and 2 of the ground state up to N' = 11 is presented which should aid
astronomers in analysis and interpretation of observed AlO data and also
facilitate future searches for this radical.Comment: To appear in Astronomy and Astrophysic
Canonically conjugate pairs and phase operators
For quantum mechanics on a lattice the position (``particle number'')
operator and the quasi-momentum (``phase'') operator obey canonical commutation
relations (CCR) only on a dense set of the Hilbert space. We compare exact
numerical results for a particle in simple potentials on the lattice with the
expectations, when the CCR are assumed to be strictly obeyed. Only for
sufficiently smooth eigenfunctions this leads to reasonable results. In the
long time limit the use of the CCR can lead to a qualitativel wrong dynamics
even if the initial state is in the dense set.Comment: 4 pages, 5 figures. Phys. Rev. A, in pres
Nine years of comparative effectiveness research education and training: initiative supported by the PhRMA Foundation
The term comparative effectiveness research (CER) took center stage with passage of the American Recovery and Reinvestment Act (2009). The companion US$1.1 billion in funding prompted the launch of initiatives to train the scientific workforce capable of conducting and using CER. Passage of the Patient Protection and Affordable Care Act (2010) focused these initiatives on patients, coining the term âpatient-centered outcomes researchâ (PCOR). Educational and training initiatives were soon launched. This report describes the initiative of the Pharmaceutical Research and Manufacturers Association of America (PhRMA) Foundation. Through provision of grant funding to six academic Centers of Excellence, to spearheading and sponsoring three national conferences, the PhRMA Foundation has made significant contributions to creation of the scientific workforce that conducts and uses CER/PCOR
A dilemma in representing observables in quantum mechanics
There are self-adjoint operators which determine both spectral and
semispectral measures. These measures have very different commutativity and
covariance properties. This fact poses a serious question on the physical
meaning of such a self-adjoint operator and its associated operator measures.Comment: 10 page
Canonical and kinetic forms of the electromagnetic momentum in an ad hoc quantization scheme for a dispersive dielectric
An ad hoc quantization scheme for the electromagnetic field in a weakly
dispersive, transparent dielectric leads to the definition of canonical and
kinetic forms for the momentum of the electromagnetic field in a dispersive
medium. The canonical momentum is uniquely defined as the operator that
generates spatial translations in a uniform medium, but the quantization scheme
suggests two possible choices for the kinetic momentum operator, corresponding
to the Abraham or the Minkowski momentum in classical electrodynamics. Another
implication of this procedure is that a wave packet containing a single dressed
photon travels at the group velocity through the medium. The physical
significance of the canonical momentum has already been established by
considerations of energy and momentum conservation in the atomic recoil due to
spontaneous emission, the Cerenkov effect, the Doppler effect, and phase
matching in nonlinear optical processes. In addition, the data of the Jones and
Leslie radiation pressure experiment is consistent with the assignment of one
?k unit of canonical momentum to each dressed photon. By contrast, experiments
in which the dielectric is rigidly accelerated by unbalanced electromagnetic
forces require the use of the Abraham momentum.Comment: 21 pages, 1 figure, aip style, submitted to PR
Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 parsecs: The Northern Sample I
We have embarked on a project, under the aegis of the Nearby Stars (NStars)/
Space Interferometry Mission Preparatory Science Program to obtain spectra,
spectral types, and, where feasible, basic physical parameters for the 3600
dwarf and giant stars earlier than M0 within 40 parsecs of the sun. In this
paper we report on the results of this project for the first 664 stars in the
northern hemisphere. These results include precise, homogeneous spectral types,
basic physical parameters (including the effective temperature, surface gravity
and the overall metallicity, [M/H]) and measures of the chromospheric activity
of our program stars. Observed and derived data presented in this paper are
also available on the project's website at http://stellar.phys.appstate.edu/
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