102,274 research outputs found
Design, analysis and test verification of advanced encapsulation systems
Analytical models were developed to perform optical, thermal, electrical and structural analyses on candidate encapsulation systems. Qualification testing, specimens of various types, and a finalized optimum design are projected
Deep inelastic scattering, diffraction, and all that
These lectures include an introduction to the partonic description of the
proton, the photon and the `colour singlet', as seen in inclusive and
semi-inclusive DIS, in collisions, and in diffractive processes,
respectively. Their formal treatment using structure, fragmentation, and
fracture functions is outlined giving an insight into the perturbative QCD
framework for these functions. Examples and comparisons with experimental data
from LEP, HERA, and Tevatron are also covered.Comment: 46 pages, 52 postscript figures, LaTeX, aipproc.sty. To be published
in the proceedings of VII Mexican Workshop on Particles and Field
NLO Scale Dependence of Semi-Inclusive Processes
We discuss the order \alpha_s^2 gluon initiated QCD corrections to one
particle inclusive deep inelastic processes. We focus in the NLO evolution
kernels relevant for the non homogeneous QCD scale dependence of these cross
sections and factorization.Comment: Poster presentation at the XXIII Physics in Collision Conference
(PIC03), Zeuthen, Germany, June 2003, 3 pages, LaTeX, 4 eps figures, PSN
FRAP1
Space-time defects :Domain walls and torsion
The theory of distributions in non-Riemannian spaces is used to obtain exact
static thin domain wall solutions of Einstein-Cartan equations of gravity.
Curvature -singularities are found while Cartan torsion is given by
Heaviside functions. Weitzenb\"{o}ck planar walls are caracterized by torsion
-singularities and zero curvature. It is shown that Weitzenb\"{o}ck
static thin domain walls do not exist exactly as in general relativity. The
global structure of Weitzenb\"{o}ck nonstatic torsion walls is investigated.Comment: J.Math.Phys.39,(1998),Jan. issu
Optimal boundary geometry in an elasticity problem: a systematic adjoint approach
p. 509-524In different problems of Elasticity the definition of the optimal geometry of the boundary, according to a given objective function, is an issue of great interest. Finding the shape of a hole in the middle of a plate subjected to an arbitrary loading such that the stresses along the hole minimizes some functional or the optimal middle curved concrete vault for a tunnel along which a uniform minimum compression are two typical examples. In these two examples the objective functional depends on the geometry of the boundary that can be either a curve (in case of 2D problems) or a surface boundary (in 3D problems). Typically, optimization is achieved by means of an iterative process which requires the computation of gradients of the objective function with respect to design variables.
Gradients can by computed in a variety of ways, although adjoint methods either continuous or discrete ones are the more efficient ones when they are applied in different technical branches. In this paper the adjoint continuous method is introduced in a systematic way to this type of problems and an illustrative simple example, namely the finding of an optimal shape tunnel vault immersed in a linearly elastic terrain, is presented.Garcia-Palacios, J.; Castro, C.; Samartin, A. (2009). Optimal boundary geometry in an elasticity problem: a systematic adjoint approach. Editorial Universitat Politècnica de València. http://hdl.handle.net/10251/654
Collapse of the ESR fine structure throughout the coherent temperature of the Gd-doped Kondo Semiconductor
Experiments on the Electron Spin Resonance (ESR) in the filled
skutterudite (), at temperatures
where the host resistivity manifests a smooth insulator-metal crossover,
provides evidence of the underlying Kondo physics associated with this system.
At low temperatures (below ), behaves
as a Kondo-insulator with a relatively large hybridization gap, and the
ESR spectra displays a fine structure with lorentzian line shape,
typical of insulating media. The electronic gap is attributed to the large
hybridization present in the coherent regime of a Kondo lattice, when Ce
4f-electrons cooperate with band properties at half-filling. Mean-field
calculations suggest that the electron-phonon interaction is fundamental at
explaining the strong 4f-electron hybridization in this filled skutterudite.
The resulting electronic structure is strongly temperature dependent, and at
about the system undergoes an insulator-to-metal
transition induced by the withdrawal of 4f-electrons from the Fermi volume, the
system becoming metallic and non-magnetic. The ESR fine structure
coalesces into a single dysonian resonance, as in metals. Still, our
simulations suggest that exchange-narrowing via the usual Korringa mechanism,
alone, is not capable of describing the thermal behavior of the ESR spectra in
the entire temperature region ( - K). We propose that temperature
activated fluctuating-valence of the Ce ions is the missing ingredient that,
added to the usual exchange-narrowing mechanism, fully describes this unique
temperature dependence of the ESR fine structure observed in
.Comment: 19 pages, 6 figure
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