A computer music system that follows a human conductor

An electronic orchestra with a complex performance database and MIDI (Musical Instrument Digital Interface) controllers is presented. This system responds to the gestures of a conductor through a CCD camera and a sensor glove. The processing of musical information is examined, and the system and its operation are described. It consists of a gesticulation system and the MIDI controllers. The human interface is also discussed. The first professional conductor who tried the system could direct it without special skills or knowledge of either MIDI or a computer. Tests revealed feedback effects on the behavior of the users through their auditory sense, which in turn suggested some ways to determine the parameters of tempo prediction and compensation. The system can play in concert with human performers and even as a part of a symphony orchestra     

Theoretical analysis of longevity testing on bubble memory devices

Theoretical results of magnetic bubble device long-term reliability testing are reported. The bubble during propagation along Permalloy tracks is represented by a simple, one-dimensional stochastic model. An equation to describe fluctuation in cylindrical bubble radius is approximated in the Langevin type stochastic differential equation, in which a set of small effects, such as interaction among bubbles and crystal nonuniformity, are considered as a white noise forcing term. Estimating the average time to bubble annihilation or runout (bubble memory mean time to failure) is reduced to a level-crossing problem for a random process. Calculated bias field margin degradation shows a qualitative agreement with experimental results for an actual bubble device. Bubble material parameters for obtaining maximum operation time are suggested.     

Optical time-division multiplexer utilizing a modulation signal supplied to optical modulators as a reference

We propose and demonstrate an optical time-division multiplexer which multiplexes optical pulse trains coming from different sources and which varies their time position, it controls the time position of each pulse train on the basis of a modulation signal supplied to optical modulators and outputs a multiplexed pulse train in a synchronized state. Experiments demonstrate that the pull-in time was less than 10 s and that a time-varying pulse train passing through an 80-km-long fiber can be controlled to a desired position within 200 ps/spl times/0.47%.     

A new type magnetic modulator

A one-core magnetic modulator based on a new principle is described which operates as a high-sensitivity small-input dc-ac converter with a drift or noise level of the order of 10^-16watts. The residual output in response to an excess input can be kept below about 10-μA turns in terms of equivalent input. In the case of push-pull connections, the characteristics are greatly improved, under far more loose conditions than with conventional second-harmonic-type modulator.