A Wollaston prism interferometer implemented with a digitizer

Objective of this work was to implement a Wollaston prism interferometer with a digitizer so as to perform the evaluation procedure of interferograms automatically by means of a microcomputer. The adopted opto-electronic sensing device is a linear array of 1,024 bar-shaped (15 m × 26 m) silicon photodiodes with center-to-center spacing 25 m. A stepping motor can move the array board in order to investigate the whole interferometric image. Scanning time is about 10 ms/line. Application of the system to measurements of concentration profiles in some mass diffusion processes of a binary gas mixture proves the ability of the digitizer to accurately measure gas densities. The performance and the potentiality of the sensor are analyzed and discussed.     

A Reuniformization for Contractive Mappings in Uniform Spaces

Let X be a complete uniform HAUSDORFF space with a uniformity generated by a saturated family of pseudometrics ?? = {?_α(x, y): α ? A} and let T: X → X be a continuous mapping. The paper contains necessary and sufficient conditions for the existence of a new family of pseudometrics ??*={?*(x, y): α*?A*} generated the same topology such that T is contractive with respect to ??*.     

Selection theorems,based on generalized variation and oscillation

In this paper we prove selection theorems for everywhere and almost everywhere convergent subsequences, based on the notion of uniformly limited oscillation, ofA, Λ-oscillation and ofA, Λ-variation, whereA is a system of intervals and Λ a sequence of reals. By this, we generalize and strengthen the selection theorems of Schrader (for oscillation) and of Waterman (for Λ-variation).     

Regular and Chaotic Solutions of Duffing's Equation for Large Forcing

This paper uses an analytical approximation to study the periodicand chaotic solutions of the forced—damped Duffing's equation.The forcing is of fixed frequency and is taken to be a multipleof cos t. The forcing amplitude is large and its reciprocalis used to construct a small parameter , which is used as anexpansion parameter in the approximation. The solutions aredetermined as functions of . The damping is linear and proportionalto the velocity; the constant of proportionality is held fixedin this study.     

Searching for light Higgs scalar bosons in the next generation of electron-positron collider at LEP

Thee ⁺ e ^–-collider facilities at LEP II, with the CM energy S in the range 100–170 GeV, may be able to detect light Higgs bosons, assuming a high luminosity. The production cross sections of a light Higgs bosonH ⁰ in association with the neutral gauge bosonZ ⁰ are calculated for varying ranges of the CM energy expected to be available to LEP II and VLEEP (Novosibirsk) and for various values of the light Higgs mass. It is found that production cross sections are sizable in comparison with those for the very massive Higgs bosons in proton-anti(proton) supercolliders, Tevatron, Sp¯pS, and SSC, respectively. The implication of this feature is pointed out. Further, prospects for light Higgs production in association with the charged gauge bosonW ^– in ultraenergetic neutrino beams are examined.     

Observables on hypergraphs

Observables on hypergraphs are described by event-valued measures. We first distinguish between finitely additive observables and countably additive ones. We then study the spectrum, compatibility, and functions of observables. Next a relationship between observables and certain functionals on the set of measures M(H) of a hypergraph H is established. We characterize hypergraphs for which every linear functional on M(H) is determined by an observable. We define the concept of an effect and show that observables are related to effect-valued measures. Finally, we define operational transformations from M(H) to itself and show that they can be described as a certain combination of effects.On leave from University of Berne, Institute of Mathematical Statistics, Sidlerstrasse 5, CH-3012 Berne, Switzerland.     

On the use of symmetrized dot patterns for the visual characterization of speech waveforms and other sampled data

While the spectrogram (and related graphic analyses) have been invaluable in showing the general frequency content of an input signal, sometimes it is difficult for trained and untrained users to see on the spectrogram differences which are perceptible to the ear. In this paper, several demonstrations of a novel representation are presented which, in some cases, can make subtle differences in input signals obvious to the human analyst. The representation, a "symmetrized dot pattern" (SDP), provides a stimulus in which local visual correlations are integrated to form a global percept and can potentially be applied to the detection and characterization of significant features of any sampled data.     

A two-stage nonlinear cochlear model possesses automatic gain control

A model of the cochlea is explored using as stimuli two simultaneously presented sinusoids of equal amplitude. The model consists of two stages: a linear bandpass filter, followed by a reservoir-type representation of the hair-cell/nerve-fiber complex. Fast Fourier transforms of the model's output were computed. While the amplitudes of the individual response components were strongly nonlinear functions of intensity, the ratio of the magnitudes of the response components at the frequencies of the two stimulating sinusoids was found to be nearly equal, over a wide intensity range, to the ratio of the amplitudes which those stimulating sinusoids possessed at the output of the filter. Thus the reservoir stage exerts "automatic gain control".