9,851 research outputs found
Effective interactions and superconductivity in the t-J model in the large-N limit
The feasibility of a perturbation expansion for Green's functions of the t-J
model directly in terms of X-operators is demonstrated using the Baym- Kadanoff
functional method. As an application we derive explicit expressions for the
kernel of the linearized equation for the superconducting order parameter in
leading order of a 1/N expansion. The linearized equation is solved numerically
on a square lattice. We find that a reasonably strong instability occurs only
for even frequency pairing with d-wavelike symmetry. Results for the transition
temperature and the effective interaction are given as a function of doping.Comment: 31 pages, 11 figure
Superconductivity, d Charge-Density Wave and Electronic Raman Scattering in High-T Superconductors
The competition of superconductivity and a d charge-density wave (CDW) is
studied in the t-J model as a function of temperature at large N where N is the
number of spin components. Applying the theory to electronic Raman scattering
the temperature dependence of the and the spectra are
discussed for a slightly underdoped case.Comment: 2 pages, 3 figures, Proc. M2S-HTSC-VII, to appear in Physica
Influence of collective effects and the d-CDW on electronic Raman scattering in high-T superconductors
Electronic Raman scattering in high-T superconductors is studied within
the t-J model. It is shown that the A and B spectra are dominated
by amplitude fluctuations of the superconducting and the d-wave CDW order
parameters, respectively. The B spectrum contains no collective effects
and its broad peak reflects vaguely the doping dependence of T, similarly
to the pronounced peak in the A spectrum. The agreement of our theory
with the experiment supports the picture of two different, competing order
parameters in the underdoped regime of high-T superconductors.Comment: 4 pages, 4 figures, will appear in PR
Analysis of monotonicity properties of some rule interestingness measures
One of the crucial problems in the field of knowledge discovery is development of good interestingness measures for evaluation of the discovered patterns. In this paper, we consider quantitative, objective interestingness measures for "if..., then... " association rules. We focus on three popular interestingness measures, namely rule interest function of Piatetsky-Shapiro, gain measure of Fukuda et al., and dependency factor used by Pawlak. We verify whether they satisfy the valuable property M of monotonic dependency on the number of objects satisfying or not the premise or the conclusion of a rule, and property of hypothesis symmetry (HS). Moreover, analytically and through experiments we show an interesting relationship between those measures and two other commonly used measures of rule support and anti-support
Definition of a resistojet control system for the Manned Orbital Research Laboratory. Volume 5 - Resistojet design and Development Final report
Resistojet design and development for Manned Orbital Research Laborator
Zero-gravity cloud physics laboratory: Experiment program definition and preliminary laboratory concept studies
The experiment program definition and preliminary laboratory concept studies on the zero G cloud physics laboratory are reported. This program involves the definition and development of an atmospheric cloud physics laboratory and the selection and delineations of a set of candidate experiments that must utilize the unique environment of zero gravity or near zero gravity
Resistojet systems studies directed to the space station/space base. Volume 2 - Biowaste resistojet system development program Final report
Space station/base biowaste resistojet system for orbit keeping and control moment gyro desaturation - systems developmen
Definition of a resistojet control system for the manned orbital research laboratory. Addendum to volume 5 - 720 hour resistojet life test Final report
Life test data for resistojet thrustors operating with ammonia or hydroge
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