1,858 research outputs found

    The radiating part of circular sources

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    An analysis is developed linking the form of the sound field from a circular source to the radial structure of the source, without recourse to far-field or other approximations. It is found that the information radiated into the field is limited, with the limit fixed by the wavenumber of source multiplied by the source radius (Helmholtz number). The acoustic field is found in terms of the elementary fields generated by a set of line sources whose form is given by Chebyshev polynomials of the second kind, and whose amplitude is found to be given by weighted integrals of the radial source term. The analysis is developed for tonal sources, such as rotors, and, for Helmholtz number less than two, for random disk sources. In this case, the analysis yields the cross-spectrum between two points in the acoustic field. The analysis is applied to the problems of tonal radiation, random source radiation as a model problem for jet noise, and to noise cancellation, as in active control of noise from rotors. It is found that the approach gives an accurate model for the radiation problem and explicitly identifies those parts of a source which radiate.Comment: Submitted to Journal of the Acoustical Society of Americ

    Team Teaching Styles Utilized In Japan: Do They Really Work?

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    This paper continues the debate over TT(team-teaching) benefits and detriments. TT has been utilized extensively inJapan in English Language instructional courses at the elementary and juniorhigh school levels over the past 20 years. Although at times satirical, theauthor in all seriousness discusses TT and; its advantages and disadvantages inlight of his experiences in various TT instructional environments. Teamteaching can be a viable option for large or multiple classes; unfortunately, however,personality and cultural conflicts between instructors most often disallow anybenefits that might be gained by the learners. In this paper, the author willdiscuss and share his specific experiences with TT over a fifteen year periodin Japanese kindergartens, elementary schools, and junior high schools.Concluding remarks will analyze the TT approach between Japanese instructors incollaboration with their fellow Japanese teachers

    Report of the committee to review the use of J-13 well water in Nevada Nuclear Waste Storage Investigations

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    The Waste Management Project Office of the Department of Energy conducted a special audit of the activities of the Nevada Nuclear Waste Storage Investigation Project at Livermore. It was noted that there never has been a comprehensive, well-documented examination of the basis for the use of J-13 water in the nuclear waste storage investigations. In each of the sections of This Report, an issue relating to the use of J-13 water has been addressed. 58 refs., 19 figs., 8 tabs

    English Words Spelled the Same but Pronounced Differently

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    For many years I have collected about 100 such words. There are at least two types of homographs. Most frequently encountered are Type 1, in which words of closely related meanings perform as different parts of speech when pronounced differently

    Quasi-analytical root-finding for non-polynomial functions

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    Made available in DSpace on 2018-12-11T16:46:02Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-11-01Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)A method is presented for the calculation of roots of non-polynomial functions, motivated by the requirement to generate quadrature rules based on non-polynomial orthogonal functions. The approach uses a combination of local Taylor expansions and Sturm’s theorem for roots of a polynomial which together give a means of efficiently generating estimates of zeros which can be polished using Newton’s method. The technique is tested on a number of realistic problems including some chosen to be highly oscillatory and to have large variations in amplitude, both of which features pose particular challenges to root–finding methods.Departamento de Matemática Aplicada UNESP–University Estadual PaulistaDepartment of Mechanical Engineering University of BathDepartamento de Matemática Aplicada UNESP–University Estadual PaulistaFAPESP: 2014/17357-1FAPESP: 2014/22571-
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