1,721,120 research outputs found
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
"A S.O.M. based algorithm for video surveillance sstem parameter optimal selection"
No full textn automatic video surveillance systems, full time monitoring represents an important goal to achieve. The aim of the paper is to find a new methodology for video surveillance adaptive parameter regulation. The method presented is based on self organizing maps (SOM) which are used for parameter regulation purposes. Results shown prove how this method permits overall good performances to be achieved for all environments
Interferometria laser per applicazioni industriali: uso di diodi laser per la misura di distanza
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Wide range distance meter based on frequency modulation of a Nd:YAG laser
No full textThe paper presents a distance meter for noncontact measurement over extended ranges based on the frequency-modulated continuous-wave (FMCW) technique. A tunable diode-pumped Nd:YAG laser is used to generate the chirp signal. The system has been characterized over a measurement range from 1 to 11 m. In accordance with the state of the art of the FMCW interferometry, the average measurement accuracy of the system is 10(-4) of the measured distance. The behavior of the frequency modulator has been experimentally characterized. A suitable signal elaboration procedure has been implemented to compensate for the nonlinear behavior of the optical frequency modulator. (C) 1996 Society of Photo-Optical Instrumentation Engineers
Fiber-linked interferometric displacement sensor: analysis of residual sensitivity to fiber stress
No full textIn this paper an accurate analysis of the sensitivity to fiber-stress of a fiber-linked interferometric displacement sensor is presented, A numerical evaluation has been performed, aimed at evidencing the influence of i) the nonideal behavior of the fiber, ii) the nonideal polarization of the laser source, and iii) the fiber-ends misalignment. An experimental verification of the model, based on measurements carried out on interferometric signals from a prototype of the system, is also presented, Both the incremental operating mode and the subfringe measurement mode of the interferometer have been considered, In the incremental mode, based on the interferometric fringe transition counting, the implemented system is insensitive to fiber stress for a few degrees of fiber-ends misalignment. However, for high-accuracy measurements based on subfringe measurements, in order to reduce the sensitivity to fiber stresses, the input fiber end has to be precisely aligned to the head containing the laser source and detectors. It is also shown that, due to the uncertain behavior of the real fiber and to the nonperfect polarization of the laser, also in the case of ideal fiber-end alignment, a residual sensitivity of the system to fiber stress is still present, This sensitivity is significant only for subfringe measurements
"Optimization of corse synchronisation performances by non-linear signal pre-processing of GNSS signals in radar jammed environments"
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