12,324 research outputs found
Coupling between pressure and temperature waves in liquid helium
Pressure and temperature wave coupling in liquid helium model with thermal expansio
Integration of perception and reasoning in fast neural modules
Artificial neural systems promise to integrate symbolic and sub-symbolic processing to achieve real time control of physical systems. Two potential alternatives exist. In one, neural nets can be used to front-end expert systems. The expert systems, in turn, are developed with varying degrees of parallelism, including their implementation in neural nets. In the other, rule-based reasoning and sensor data can be integrated within a single hybrid neural system. The hybrid system reacts as a unit to provide decisions (problem solutions) based on the simultaneous evaluation of data and rules. Discussed here is a model hybrid system based on the fuzzy cognitive map (FCM). The operation of the model is illustrated with the control of a hypothetical satellite that intelligently alters its attitude in space in response to an intersecting micrometeorite shower
A method of isolating organic compounds present in water
Water sample is passed through a column containing macroreticular resin, which absorbs only nonionic organic compounds. These compounds are selectively separated using aqueous eluents of varying pH, or completely exuded with small amount of an organic eluent
On the existence of quantum representations for two dichotomic measurements
Under which conditions do outcome probabilities of measurements possess a
quantum-mechanical model? This kind of problem is solved here for the case of
two dichotomic von Neumann measurements which can be applied repeatedly to a
quantum system with trivial dynamics. The solution uses methods from the theory
of operator algebras and the theory of moment problems. The ensuing conditions
reveal surprisingly simple relations between certain quantum-mechanical
probabilities. It also shown that generally, none of these relations holds in
general probabilistic models. This result might facilitate further experimental
discrimination between quantum mechanics and other general probabilistic
theories.Comment: 16+7 pages, presentation improved and minor errors correcte
The active control of wing rotation by Drosophila
This paper investigates the temporal control of a fast wing rotation in flies, the ventral flip, which occurs during the transition from downstroke to upstroke. Tethered flying Drosophila actively modulate the timing of these rapid supinations during yaw responses evoked by an oscillating visual stimulus. The time difference between the two wings is controlled such that the wing on the outside of a fictive turn rotates in advance of its contralateral partner. This modulation of ventral-flip timing between the two wings is strongly coupled with changes in wing-stroke amplitude. Typically, an increase in the stroke amplitude of one wing is correlated with an advance in the timing of the ventral flip of the same wing. However, flies do display a limited ability to control these two behaviors independently, as shown by flight records in which the correlation between ventral-flip timing and stroke amplitude transiently reverses. The control of ventral-flip timing may be part of an unsteady aerodynamic mechanism that enables the fly to alter the magnitude and direction of flight forces during turning maneuvers
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