1,721,027 research outputs found
Theoretical and experimental analysis of intensity noise in a codoped erbium-ytterbium glass laser
No full textA comprehensive analysis of the mechanisms inducing intensity noise in a single-frequency, diode-pumped erbium-ytterbium glass laser is presented. Owing to the energy transfer between the codopant and the active material, the Er: Yb laser shows a markedly reduced sensitivity to pump power fluctuations, and hence its intensity noise spectrum is mainly determined by the fluctuations in the cavity losses. The experimental measurements confirm the results of the theoretical analysis. © Springer-Verlag 1998
Intensity noise reduction in a single-frequency ytterbium-codoped erbium laser
No full textWe report on intensity noise suppression in a diode-pumped, single-frequency erbium bulk-glass laser codoped with ytterbium. Using an optoelectronic feedback circuit, we acheived a 30-dB reduction of the relaxation oscillation peak, at 160-kHz frequency, to a relative intensity noise of -114 dB/Hz. A useful output power of 15 mW at 1533-nm wavelength was obtained. © 1996 Optical Society of America
Landscape management as a «sustainable agriculture» tool: the role of local administration and research in the Emilia-Romagna region (northern Italy)
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Landscape management as a “sustainable agriculture” tool: the role of local administration and research in the Emilia-Romagna region (northern Italy)
No full textOptoekectronic Feedback Control for Intensity Noise Suppression in a Codoped Erbium Ytterbium Glass Laser
No full textAn effective optoelectronic feedback circuit for the suppression of relaxation oscillations in a codoped erbium-ytterbium laser is designed and demonstrated. The presence of an additional dominant pole in the forward transfer function, due to the energy transfer process inside the active material, requires a feedback control which introduces a suitable phase shift and provides high gain at the relaxation oscillation frequency. A 30dB reduction in the relaxation oscillation noise peak has been achieved
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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