30,897 research outputs found
Report on the development of the Manned Orbital Research Laboratory /MORL/ system utilization potential. Task area IV - MORL SYSTEM improvement study, book 2
Environmental control and life support systems analyses for improved Manned Orbital Research Laborator
Amplitude squeezed light from a laser
Intensity squeezed light was successfully generated using semiconductor lasers with sub-Poissonian pumping. Control of the pumping statistics is crucial and is achieved by a large series resistor which regulates the pump current; its sub-Poissonian statistics are then transferred to the laser output. The sub-Poissonian pumping of other laser systems is not so simple, however, and their potential as squeezed states sources is apparently diminished. We consider a conventional laser incoherently pumped well above threshold, and allow for pump depletion of the ground state. In this regime, sub-Poissonian photon statistics and squeezed amplitude fluctuations are produced
The Paraldor Project
Paraldor is an experiment in bringing the power of categorical languages to
lattice QCD computations. Our target language is Aldor, which allows the
capture of the mathematical structure of physics directly in the structure of
the code using the concepts of categories, domains and their
inter-relationships in a way which is not otherwise possible with current
popular languages such as Fortran, C, C++ or Java. By writing high level
physics code portably in Aldor, and implementing switchable machine dependent
high performance back-ends in C or assembler, we gain all the power of
categorical languages such as modularity, portability, readability and
efficiency.Comment: 4 pages, 2 figures, Lattice 2002 conference proceeding
Computing the Loewner driving process of random curves in the half plane
We simulate several models of random curves in the half plane and numerically
compute their stochastic driving process (as given by the Loewner equation).
Our models include models whose scaling limit is the Schramm-Loewner evolution
(SLE) and models for which it is not. We study several tests of whether the
driving process is Brownian motion. We find that just testing the normality of
the process at a fixed time is not effective at determining if the process is
Brownian motion. Tests that involve the independence of the increments of
Brownian motion are much more effective. We also study the zipper algorithm for
numerically computing the driving function of a simple curve. We give an
implementation of this algorithm which runs in a time O(N^1.35) rather than the
usual O(N^2), where N is the number of points on the curve.Comment: 20 pages, 4 figures. Changes to second version: added new paragraph
to conclusion section; improved figures cosmeticall
Effect of a Spin-1/2 Impurity on the Spin-1 Antiferromagnetic Heisenberg Chain
Low-lying excited states as well as the ground state of the spin-1 antiferro-
magnetic Heisenberg chain with a spin-1/2 impurity are investigated by means of
a variational method and a method of numerical diagonalization. It is shown
that 1) the impurity spin brings about massive modes in the Haldane gap, 2)
when the the impurity-host coupling is sufficiently weak, the phenomenological
Hamiltonian used by Hagiwara {\it et al.} in the analysis of ESR experimental
results for NENP containing a small amount of spin-1/2 Cu impurities is
equivalent to a more realistic Hamiltonian, as far as the energies of the
low-lying states are concerned, 3) the results obtained by the variational
method are in semi-quantitatively good agreement with those obtained by the
numerical diagonalization.Comment: 11 pages, plain TeX (Postscript figures are included), KU-CCS-93-00
Renormalization group maps for Ising models in lattice gas variables
Real space renormalization group maps, e.g., the majority rule
transformation, map Ising type models to Ising type models on a coarser
lattice. We show that each coefficient of the renormalized Hamiltonian in the
lattice gas variables depends on only a finite number of values of the
renormalized Hamiltonian. We introduce a method which computes the values of
the renormalized Hamiltonian with high accuracy and so computes the
coefficients in the lattice gas variables with high accuracy. For the critical
nearest neighbor Ising model on the square lattice with the majority rule
transformation, we compute over 1,000 different coefficients in the lattice gas
variable representation of the renormalized Hamiltonian and study the decay of
these coefficients. We find that they decay exponentially in some sense but
with a slow decay rate. We also show that the coefficients in the spin
variables are sensitive to the truncation method used to compute them.Comment: 22 pages, 9 color postscript figures; minor revisions in version
Making the small oblique parameters large
We compute the oblique parameters, including the three new parameters ,
and introduced recently by the Montreal group, for the case of one
scalar multiplet of arbitrary weak isospin and weak hypercharge . We
show that, when the masses of the heaviest and lightest components of the
multiplet remain constant, but increases, the oblique parameter and
the three new oblique parameters increase like , while only
increases like . For large multiplets with masses not much higher than , the oblique parameters and may become much larger than
and .Comment: 9 pages, standard LATEX, 3 figures available from the authors, report
CMU-HEP93-17 and DOE-ER/40682-4
Design of a Torque Current Generator for Strapdown Gyroscopes
The design, analysis, and experimental evaluation of an optimum performance torque current generator for use with strapdown gyroscopes, is presented. Among the criteria used to evaluate the design were the following: (1) steady-state accuracy; (2) margins of stability against self-oscillation; (3) temperature variations; (4) aging; (5) static errors drift errors, and transient errors, (6) classical frequency and time domain characteristics; and (7) the equivalent noise at the input of the comparater operational amplifier. The DC feedback loop of the torque current generator was approximated as a second-order system. Stability calculations for gain margins are discussed. Circuit diagrams are shown and block diagrams showing the implementation of the torque current generator are discussed
Influence of temper condition on the nonlinear stress-strain behavior of boron-aluminum
The influence of temper condition on the tensile and compressive stress-strain behavior for six boron-aluminum laminates was investigated. In addition to monotonic tension and compression tests, tension-tension, compression-compression, and tension--compression tests were conducted to study the effects of cyclic loading. Tensile strength results are a function of the laminate configuration; unidirectional laminates were affected considerably more than other laminates with some strength values increasing and others decreasing
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