869 research outputs found
Large Deviations in the Superstable Weakly Imperfect Bose Gas
The superstable Weakly Imperfect Bose Gas {(WIBG)} was originally derived to
solve the inconsistency of the Bogoliubov theory of superfluidity. Its
grand-canonical thermodynamics was recently solved but not at {point of} the
{(first order)} phase transition. This paper proposes to close this gap by
using the large deviations formalism and in particular the analysis of the Kac
distribution function. It turns out that, as a function of the chemical
potential, the discontinuity of the Bose condensate density at the phase
transition {point} disappears as a function of the particle density. Indeed,
the Bose condensate continuously starts at the first critical particle density
and progressively grows but the free-energy per particle stays constant until
the second critical density is reached. At higher particle densities, the Bose
condensate density as well as the free-energy per particle both increase
{monotonously}
The difference of boundary effects between Bose and Fermi systems
In this paper, we show that there exists an essential difference of boundary
effects between Bose and Fermi systems both for Dirichlet and Neumann boundary
conditions: at low temperatures and high densities the influence of the
boundary on the Bose system depends on the temperature but is independent of
the density, but for the Fermi case the influence of the boundary is
independent of the temperature but depends on the density, after omitting the
negligible high-order corrections. We also show that at high temperatures and
low densities the difference of the influence of the boundary between Bose and
Fermi systems appears in the next-to-leading order boundary contribution, and
the leading boundary contribution is independent of the density. Moreover, for
calculating the boundary effects at high temperatures and low densities, since
the existence of the boundary modification causes the standard virial expansion
to be invalid, we introduce a modified virial expansion.Comment: 8 page
Parameters of the eigenellipsoid for separated sector cyclotron
http://accelconf.web.cern.ch/AccelConf/c89/papers/g1-09.pdfInternational audienc
Six-dimensional beam matching for axial injection into a cyclotron
http://accelconf.web.cern.ch/AccelConf/c89/papers/g1-01.pdfInternational audienc
Trajectory Tracking Control of a Timed Event Graph with Specifications Defined by a P-time Event Graph
The aim of this paper is a trajectory tracking control of Timed Event Graphs with specifications defined by a P-time Event Graph. Two problems are solved on a fixed horizon knowing the current state: The optimal control for favorable past evolution; The prediction of the earliest future evolution of the process. These two parts make up an on-line control which is used on a sliding horizon. Completely defined in (max, +) algebra, the proposed approach is a Model Predictive Control using the componentwise order relation
Growth and optical properties of GaN/AlN quantum wells
We demonstrate the growth of GaN/AlN quantum well structures by
plasma-assisted molecular-beam epitaxy by taking advantage of the surfactant
effect of Ga. The GaN/AlN quantum wells show photoluminescence emission with
photon energies in the range between 4.2 and 2.3 eV for well widths between 0.7
and 2.6 nm, respectively. An internal electric field strength of
MV/cm is deduced from the dependence of the emission energy on the well width.Comment: Submitted to AP
Determinación paramétrica de los ejes de rotación de las articulaciones interfalángicas de los dedos
Comunicación presentada en el XXI Congreso Nacional de Ingeniería Mecánica, celebrado en Elche en Noviembre de 2016.Los ejes de rotación de las articulaciones interfalángicas de los dedos son aproximadamente
paralelos a los pliegues de flexión. Sin embargo, los modelos biomecánicos y ergonómicos
existentes suelen considerar ejes de rotación paralelos entre sí y perpendiculares a los ejes
longitudinales de las falanges. Recientemente se han utilizado técnicas de resonancia magnética
para determinar su ubicación, pero su uso de forma extensiva supone riesgos, y no está disponible
en todos los laboratorios. En este trabajo se estudia el uso de marcadores reflectantes sobre la piel
para localizar los ejes de rotación de las articulaciones interfalángicas de los dedos, y se estudia
su posible presentación paramétrica. Para ello, se localizaron los ejes de rotación de 30 sujetos con
tamaños de mano representativos de la población española, mediante el seguimiento de 12
marcadores (3 de referencia y 9 de seguimiento) sobre cada dedo. En cada articulación se
definieron los sistemas de coordenadas en los segmentos proximal y distal a partir de los
marcadores de referencia. La localización de los ejes de rotación se describió mediante las
coordenadas de la intersección del eje con el plano sagital (Px y Py) y las inclinaciones con respecto
de los planos frontal y transversal (
f y
t) de cada dedo. Estos 4 parámetros se obtuvieron de
comparar, mediante un método evolutivo de optimización, las matrices de transformación
experimentales entre los segmentos proximal y distal, con las analíticas, en un registro dinámico de
flexión/extensión. Los valores medios obtenidos para las inclinaciones con los planos frontal y
transversal resultaron ser menores de 11 y 4 grados, respectivamente, con una dispersión (8 y 4
grados) que, aun siendo moderada, no permitió obtener datos con suficiente precisión para la
mejora de los modelos biomecánicos existentes. Mediante análisis jerárquicos se comprobó que
esta dispersión se debe en parte a la variabilidad anatómica entre sujetos. Los resultados en cuanto
a localización fueron más fiables, habiendo identificado correlación de Pearson significativa de la
profundidad a la que se encuentra el eje con el grosor de la articulación (43% a 52% del grosor),
y correspondiendo el posicionamiento longitudinal con el de los marcadores utilizados
Preliminary design of a new high intensity injection system for GANIL.
http://accelconf.web.cern.ch/AccelConf/c89/papers/f6-12.pdfInternational audienc
Symmetry of matrix-valued stochastic processes and noncolliding diffusion particle systems
As an extension of the theory of Dyson's Brownian motion models for the
standard Gaussian random-matrix ensembles, we report a systematic study of
hermitian matrix-valued processes and their eigenvalue processes associated
with the chiral and nonstandard random-matrix ensembles. In addition to the
noncolliding Brownian motions, we introduce a one-parameter family of
temporally homogeneous noncolliding systems of the Bessel processes and a
two-parameter family of temporally inhomogeneous noncolliding systems of Yor's
generalized meanders and show that all of the ten classes of eigenvalue
statistics in the Altland-Zirnbauer classification are realized as particle
distributions in the special cases of these diffusion particle systems. As a
corollary of each equivalence in distribution of a temporally inhomogeneous
eigenvalue process and a noncolliding diffusion process, a stochastic-calculus
proof of a version of the Harish-Chandra (Itzykson-Zuber) formula of integral
over unitary group is established.Comment: LaTeX, 27 pages, 4 figures, v3: Minor corrections made for
publication in J. Math. Phy
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