Subjective equivalence of steering wheel vibration and sound

The subjective equivalence between steering wheel vibration and sound was investigated in two experiments. In each experiment, 20 subjects were presented 64 pairs of simultaneous sound and vibration stimuli in a simulator which reproduced a realistic driving posture. The first used stimuli measured in an automobile when driving over a coarse asphalt road surface, while the second used data obtained by driving over a 1.0 cm square metal bar. In both experiments, the acceleration time histories were scaled to eight root mean square (r.m.s.) levels from 0.5 to 4.0 m/s2 and the sound pressure time histories were scaled to eight levels from 85 to 106 dB sound pressure level (SPL). Test subjects were asked to indicate which stimuli, the sound or the vibration, was felt to be the “more unpleasant”. Regression expressions of subjective equivalence were developed for both stimuli types, in both the unweighted (decibel versus r.m.s. acceleration) and the frequency-weighted (decibel(A) versus VDV) forms. Regression slopes were found to be in the range from 23.8 to 26.8, similar to values for whole-body vibration exposures. Subjective equivalence was, however, found to be 5–15 dB(A) lower for the coarse asphalt stimuli and 15–25 dB(A) lower for the square metal bar stimuli. All other conditions remain equal, the human response to the vibration was found to increase in relative importance with respect to the sound in the case of short duration, transient, square metal bar stimuli

1D quantum models with correlated disorder vs. classical oscillators with coloured noise

We perform an analytical study of the correspondence between a classical oscillator with frequency perturbed by a coloured noise and the one-dimensional Anderson-type model with correlated diagonal disorder. It is rigorously shown that localisation of electronic states in the quantum model corresponds to exponential divergence of nearby trajectories of the classical random oscillator. We discuss the relation between the localisation length for the quantum model and the rate of energy growth for the stochastic oscillator. Finally, we examine the problem of electron transmission through a finite disordered barrier by considering the evolution of the classical oscillator.Comment: 23 pages, LaTeX fil

Flavor-oscillation clocks, continuous quantum measurements and a violation of Einstein equivalence principle

The relation between Einstein equivalence principle and a continuous quantum measurement is analyzed in the context of the recently proposed flavor-oscillation clocks, an idea pioneered by Ahluwalia and Burgard (Gen. Rel Grav. Errata 29, 681 (1997)). We will calculate the measurement outputs if a flavor-oscillation clock, which is immersed in a gravitational field, is subject to a continuous quantum measurement. Afterwards, resorting to the weak equivalence principle, we obtain the corresponding quantities in a freely falling reference frame. Finally, comparing this last result with the measurement outputs that would appear in a Minkowskian spacetime it will be found that they do not coincide, in other words, we have a violation of Einstein equivalence principle. This violation appears in two different forms, namely: (i) the oscillation frequency in a freely falling reference frame does not match with the case predicted by general relativity, a feature previously obtained by Ahluwalia; (ii) the probability distribution of the measurement outputs, obtained by an observer in a freely falling reference frame, does not coincide with the results that would appear in the case of a Minkowskian spacetime.Comment: 16 pages, accepted in Mod. Phys. Letts.

Current and vorticity auto correlation functions in open microwave billiards

Using the equivalence between the quantum-mechanical probability density in a quantum billiard and the Poynting vector in the corresponding microwave system, current distributions were studied in a quantum dot like cavity, as well as in a Robnik billiard with lambda=0.4, and an introduced ferrite cylinder. Spatial auto correlation functions for currents and vorticity were studied and compared with predictions from the random-superposition-of-plane-waves hypothesis. In addition different types of vortex neighbour spacing distributions were determined and compared with theory.Comment: PTP-LaTeX, 10 pages with 6 figures submitted to Progress of Theoretical Physics Supplemen

Dyck Paths, Motzkin Paths and Traffic Jams

It has recently been observed that the normalization of a one-dimensional out-of-equilibrium model, the Asymmetric Exclusion Process (ASEP) with random sequential dynamics, is exactly equivalent to the partition function of a two-dimensional lattice path model of one-transit walks, or equivalently Dyck paths. This explains the applicability of the Lee-Yang theory of partition function zeros to the ASEP normalization. In this paper we consider the exact solution of the parallel-update ASEP, a special case of the Nagel-Schreckenberg model for traffic flow, in which the ASEP phase transitions can be intepreted as jamming transitions, and find that Lee-Yang theory still applies. We show that the parallel-update ASEP normalization can be expressed as one of several equivalent two-dimensional lattice path problems involving weighted Dyck or Motzkin paths. We introduce the notion of thermodynamic equivalence for such paths and show that the robustness of the general form of the ASEP phase diagram under various update dynamics is a consequence of this thermodynamic equivalence.Comment: Version accepted for publicatio