1,720,981 research outputs found
La simmetrizzazione del ciclo di misura
Full text linkPer ciclo di misura simmetrico s’intende quello composto di un’andata e di un ritorno; all’andata si prendono n punti di misura in sequenza temporale diretta {1,2,...,n 1,n}, e al ritorno in sequenza inversa {n,n 1,...2,1}. Si prende poi per ciascun punto la media dei valori ottenuti all’andata e al ritorno. È noto ai più che tale pratica è raccomandabile, soprattutto per la misurazione d’oggetti monodimensionali (ad esempio calibri a passi o righe ottiche), nonostante il raddoppio del tempo di misura e il calcolo delle medie. Forse meno noto è perché sia buona pratica, quali siano i vantaggi e quali i limiti; e, soprattutto, se e come tale pratica possa essere estesa efficacemente al caso di misurazioni effettivamente tridimensionali.
Scopo del presente articolo è indagare questi aspetti. Partendo dal caso semplice della misurazione monodimensionale, si esaminerà in quali condizioni la tecnica è efficace, e quali ne siano i limiti effettivi; infine, s’estenderà l’analisi al caso generale tridimensionale, e si svolgeranno alcune considerazioni pratiche circa la sua applicabilità
Distributed Minimum Time Servicing for a Team of Dubins Vehicles
No full textIn this paper we study the following problem for a team of Dubins vehicles, i.e. nonholonomic vehicles moving at constant longitudinal speed along planar paths with bounded curvature. Given the initial configurations of the vehicles, find the point in the plane that minimizes the time to be reached by all vehicles. We call it "minimum-time servicing problem". We show that this problem can be approximated by an abstract linear program, namely a generalized version of linear programming, that can be solved in a distributed way over a network. We provide a control and communication law for a wireless network of Dubins vehicles to compute and reach the "minimum-time servicing point" while maintaining the network connected
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
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
Model-based sampling plans for CMM inspection of form tolerances
No full textWe propose a method for designing CMM inspection plans of small size for use in
form error evaluation of parts from batch or mass production. The method exploits a
priori information coming from large sample inspection of one or a few parts of the
lot. It is based on a regression model fitted to the large sample. The model is used
twice. First, it provides the dominant pattern of the surface. Then, the deviations
from the model that are relevant to form error are captured by weighting the points
of the convex-hull of the large sample with the regression residuals. Basing on two
case studies we show that the method provides enough accurate estimates of
straightness and flatness and, differently from sample-based methods, is also able
to make the user aware of possible outlier parts during inspection
Plant landscape and phytodiversity in the ancient town of Erice (NW Sicily)
Full text linkThe The town of Erice, in the province of Trapani, is an environmental unicum in the context of the ancient settlements of western Sicily. Its history, substrates, and particular climate, generated by its geo-orographic position, make it a particular hotspot of natural and cultural biodiversity. Located on the top of Mount San Giuliano, in addition to natural habitats with their specific florulas, the town shows small gardens and among the few inhabitants there is a widespread green culture. A tourist des- tination by its various architectural and landscape historical peculiarities, Erice presents a residential center made up by small stone buildings, with small courtyards or “bagli” often used to house pergolas, decorative or fruit plants placed in pots or in the ground. Protected from the wind - thanks to the special microclimatic conditions that occur at the top of the relief exposed to moist sea breeze- they find the optimal environment to grow and preserve.
The Giardino del Balio, Villa Pepoli and the remains of the park around the town, as well as the Castello di Venere and the various rocky relieves within the town, the old walls of protection of the city, are ideal habitats for many native and cultivated species. Among the former we remember the endemic and very rare Centaurea erycina, Silene nefelites, and Brassica villosa subsp. drepanensis Other endemic species find the best habitat in emerging cliffs and in architectural artefacts; they are Silene fruticosa, Dianthus rupicola subsp. rupicola, Seseli bocconei, etc. In the same contexts other chasmophytes are also frequent among which Athamantha sicula emerges. On the margin of Villa Pepoli, awesome trees of Prunus mahaleb subsp. mahaleb testify to the ancient settlement of native tree species - rare on the island - then locally cultivated. In the Giardino del Balio, in addition to the ancient borders of Buxus sempervirens, luxuriant specimens of B. balearica remarks the sub-oceanic character of the climate at the top of Mt. San Giuliano. The presence of a rich contingent of pteridophytes and bryophytes also depends on such climate, including the rare epiphytic moss Cryphaea het- eromalla, common right on the branches of the two Buxus species
- …
