9,031 research outputs found
A multiplexing architecture for mixed-signal CMOS fuzzy controllers
Limits to precision impose limits to the complexity of analog circuits, hence fuzzy analog
controllers are usually oriented to fast low-power systems with low-medium complexity. This
paper presents a strategy to preserve most of the advantages of an analog implementation, while
allowing a marked increment in system complexity.The works in this papaer has been partially funded by the spanish
C.I.C.Y.T. under contract TIC96-1392-C02-02 (SIVA
On the energy and baseline optimization to study effects related to the δ-phase (CP-/T-violation) in neutrino oscillations at a neutrino factory
In this paper we discuss the detection of CP- and T-violation effects in the framework of a neutrino factory. We introduce three quantities, which are good discriminants for a non-vanishing complex phase (δ) in the 3 × 3 neutrino mixing matrix: Δδ, ΔCP and ΔT. We find that these three discriminants (in vacuum) all scale with L/Ev, where L is the baseline and Ev the neutrino energy. Matter effects modify the scaling, but these effects are large enough to spoil the sensitivity only for baselines larger than 5000 km. So, in the hypothesis of constant neutrino factory power (i.e., number of muons inversely proportional to muon energy), the sensitivity on the δ-phase is independent of the baseline chosen. Specially interesting is the direct measurement of T-violation from the "wrong-sign" electron channel (i.e., the ΔT discriminant), which involves a comparison of the ve → vμ and vμ → ve oscillation rates. However, the vμ → ve measurement requires magnetic discrimination of the electron charge, experimentally very challenging in a neutrino detector. Since the direction of the electron curvature has to be estimated before the start of the electromagnetic shower, low-energy neutrino beams and hence short baselines, are preferred. In this paper we show, as an example, the exclusion regions in the Δm212-δ plane using the ΔCP and ΔT discriminants for two concrete cases keeping the same L/Ev ratio (730 km/7.5 GeV and 2900 km/30 GeV). We obtain a similar excluded region provided that the electron detection efficiency is ∼20% and the charge confusion 0.1%. The Δm212 compatible with the LMA solar data can be tested with a flux of 5 × 1021 muons. We compare these results with the fit of the visible energy distributions. © 2002 Elsevier Science B.V. All rights reserved
Rigidity for actions on the interval arising from hyperbolicity I: solvable groups
We consider Abelian-by-cyclic groups for which the cyclic factor acts by
hyperbolic automorphisms on the Abelian subgroup. We show that if such a group
acts faithfully by diffeomorphisms of the closed interval with no global
fixed point at the interior, then the action is topologically conjugated to
that of an affine group. Moreover, in case of non-Abelian image, we show a
rigidity result concerning the multipliers of the homotheties, despite the fact
that the conjugacy is not necessarily smooth. Some consequences for
non-solvable groups are proposed. In particular, we give new proofs/examples
yielding the existence of finitely-generated, locally-indicable groups with no
faithful action by diffeomorphisms of the interval.Comment: A more detailed proof of Proposition 4.15 adde
Symmetric random walks on Homeo+(R)
We study symmetric random walks on finitely generated groups of
orientation-preserving homeomorphisms of the real line. We establish an
oscillation property for the induced Markov chain on the line that implies a
weak form of recurrence. Except for a few special cases, which can be treated
separately, we prove a property of "global stability at a finite distance":
roughly speaking, there exists a compact interval such that any two
trajectories get closer and closer whenever one of them returns to the compact
interval. The probabilistic techniques employed here lead to interesting
results for the study of group actions on the line. For instance, we show that
under a suitable change of the coordinates, the drift of every point becomes
zero provided that the action is minimal. As a byproduct, we recover the fact
that every finitely generated group of homeomorphisms of the real line is
topologically conjugate to a group of (globally) Lipschitz homeomorphisms.
Moreover, we show that such a conjugacy may be chosen in such a way that the
displacement of each element is uniformly bounded
Length-weight relationships of demersal fishes from the upper continental slope off Colombia
Parameters of the length–weight relationship of the form W=aLb are presented for 45 demersal fish species caught on the upper continental slope of the Caribbean Sea off Colombia. The b values varied between 2.13 and 4.97, with the mean b = 3.042 (95% CI, 2.887- 3.196)
Technology and the dynamics of comparative advantage
This paper explores how trade openness affects both product and process innovation in a factor proportions model of trade and firm heterogeneity. Trade openness expands the profit opportunities of the most productive firms and expels the less efficient firms out of the market, making process innovation more attractive for the most productive firms in both industries. Incentives, however, are larger in the industry in which the country has the comparative advantage. Trade also increases the profits of prospective entrants leading to an increase in product innovation in the comparative advantage industry. In addition, I obtain a non-monotonic relationship between trade costs and a country's trade pattern: When the level of trade costs are high, a reduction in trade costs leads to an increase in process innovation in both industries, being stronger in the comparative advantage one; when the trade costs are low the effect is stronger in the comparative disadvantage one. This final result could rationalize recent empirical findings suggesting that in the last half century the Ricardian comparative advantage has become weaker over time
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