1,721,035 research outputs found
Challenge-Response Authentication Scheme with Chaotic Lasers
No full textIn this paper, we numerically evaluate a hardware-based method for authentication using a pair of twin chaotic lasers. This method belongs to the PUF (Physically Unclonable Function) class; however, it does not require storing the response of the hardware in a database, because both users own the same hardware (one of the twin chaotic lasers), producing, on the fly, the same response, i.e., the same chaotic waveform, when subject to the same stimulus (injection from a third laser) in the same working conditions (local injection, pump current). A bit sequence can be easily obtained from the chaotic waveforms by electronic processing, and authentication consists in comparing the sequences produced by the twin lasers. This scheme is proposed above all for authentication of a client in an unsecure environment to a server in a secure environment, but it can be used also for peer-to-peer authentication. Both the case of open- and close-loop chaotic lasers are considered. Simulations are based on the Lang-Kobayashi model
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
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
Time-of-flight delay-line laser telemeter
No full textWe propose a new telemeter scheme for absolute distance measurements, based on the op- toelectronic emulation of a semiconductor ring laser working in a suitable bistable regime. The feedback provided by a moveable external reflector (defining the measuring arm) and by a short electronic delay line, generates electrical switching in the circuit, the period of which is linearly related to the distance of the measuring arm reflector. This telemeter is not affected by the ambiguity problem. It requires only a single laser diode and a photodi- ode, in a simple optical arrangement, and low-cost electronic circuitry. Experiments have been performed both on a fiber path and in the air
La patologia biomeccanica dell'arto superiore: una nuova epidemia?
No full textWork-related upper limb disorders are one leading occupational diseases in many industrialized countries. The paper reviews the evidence of work-relatedness of the most common upper limb disorders (namely carpal tunnel syndrome, hand-wrist and shoulder tendinitis, trapezius myalgia, hand hammer syndrome). Attention is drawn to the difference in the number of reported cases in Italy and other countries, assuming, as an underlying cause, underreporting of such conditions in Italy
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
Movimenti ripetitivi degli arti superiori: risultati della valutazione dell'esposizione attuale e dell'indagine clinica negli addetti ad un reparto di lavorazione di carni suine del modenese
No full textExposure assessment tests were undertaken to measure the biomechanical overload factors affecting the upper limbs. The tests were carried out on a group of 86 workers employed on the cutting, boning and trimming line of a pork meat processing plant. Anamnestic screening and clinical tests targeted at correlated disorders were also performed and were followed by instrumental tests. The results are reported with respect to frequency of repetitive technical actions, degree of muscular involvement, postural risk, several complementary factors and distribution of recovery periods. The clinical investigation showed a high prevalence of carpal tunnel syndrome, tendon disorders of the hand and epicondylosis of the elbow, in addition to other disorders. The report confirms the presence of additional risks for the workers, both in the past and under present circumstances, and suitable preventive measures are formulated
Distance measurement by delayed optical feedback in a ring laser
Full text linkWe numerically study the behavior of a semiconductor ring laser subject to bidirectional
delayed optical feedback, when the isolated laser is in the quasi-unidirectional regime.
The optical feedback, provided by two external refectors located in front of the ring output waveguides, can modify the laser regime produced by the cross-saturation between
the clockwise and the counter-clockwise mode. Thus, the system exhibits new diferent regimes, most of which are asymmetric and bidirectional, with alternating dominant
mode. Two of these regimes are of special interest in view of applications, because the
laser switching period, between the clockwise and the counter-clockwise mode, is linearly
related to the time of fight from the laser to one or both refectors. In these operating conditions, the laser is thus suitable to implement a telemeter. A convenient electrical output
signal is obtained by a photodiode located behind one (partially refecting) fxed mirror,
or by measuring the voltage drop across the laser junction. Simulations are performed by
mathematical models based on rate-equations, assuming typical literature parameters for a
1 mW ring laser
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