The world problem: on the computability of the topology of 4-manifolds

Topological classification of the 4-manifolds bridges computation theory and physics. A proof of the undecidability of the homeomorphy problem for 4-manifolds is outlined here in a clarifying way. It is shown that an arbitrary Turing machine with an arbitrary input can be encoded into the topology of a 4-manifold, such that the 4-manifold is homeomorphic to a certain other 4-manifold if and only if the corresponding Turing machine halts on the associated input. Physical implications are briefly discussed.Comment: Submitted to Class. Quant. Gra

Ride quality meter

A ride quality meter is disclosed that automatically transforms vibration and noise measurements into a single number index of passenger discomfort. The noise measurements are converted into a noise discomfort value. The vibrations are converted into single axis discomfort values which are then converted into a combined axis discomfort value. The combined axis discomfort value is corrected for time duration and then summed with the noise discomfort value to obtain a total discomfort value

Meter Scoping Study

This report presents a summary of metering technology and cost information from past studies in an attempt to identify key barriers to more widespread implementation

Infants’ perception of rhythmic patterns

We explored 9-month-old infants perception of auditory temporal sequences in a series of three experiments. In Experiment 1, we presented some infants with tone sequences that were expected to induce a strongly metric framework and others with a sequence that was expected to induce a weakly metric framework or no such framework. Infants detected a change in the context of the former sequences but not in the latter sequence. In Experiment 2, infants listened to a tone sequence with temporal cues to duple or triple meter. Infants detected a change in the pattern with duple meter but not in the pattern with triple meter. In Experiment 3, infants listened to a tone sequence with harmonic cues to duple or triple meter. As in Experiment 2, infants detected a change in the context of the duple meter pattern but not in the context of triple meter. These findings are consistent with processing predispositions for auditory temporal sequences that induce a metric framework, particularly those in duple meter

Acoustic ground impedance meter

A method and apparatus are presented for measuring the acoustic impedance of a surface in which the surface is used to enclose one end of the chamber of a Helmholz resonator. Acoustic waves are generated in the neck of the resonator by a piston driven by a variable speed motor through a cam assembly. The acoustic waves are measured in the chamber and the frequency of the generated acoustic waves is measured by an optical device. These measurements are used to compute the compliance and conductance of the chamber and surface combined. The same procedure is followed with a calibration plate having infinite acoustic impedance enclosing the chamber of the resonator to compute the compliance and conductance of the chamber alone. Then by subtracting, the compliance and conductance for the surface is obtained