1,721,365 research outputs found
Structural health monitoring and diagnostic investigations of the Scrovegni chapel, Italy
Full text linkThe Scrovegni Chapel represents without doubt a masterpiece in the history of
painting in Italy and Europe in the 14th century and it is considered the most complete series
of frescos executed by Giotto in his mature age. Given the crucial importance of the building
from a cultural point of view, in 1995 a systematic research campaign started, including the
execution of studies on the structural health state of the Chapel. The final aim is to guarantee
optimal preservation conditions on the occasion, and in direct continuation, of the restoration
of the Giotto’s frescoes performed in 2001-2002. The investigation plan, based on nondestructive
techniques, includes punctual tests, periodically repeated, and continuous monitoring,
direct measurements and indirect identifications (back-analysis) of relevant structural
parameters. Although the structural layout of the chapel is apparently simple, the protection
of the monument is strongly connected to the fact that its historic and artistic value cannot be
separated from the structure itself and the effects of strengthening interventions carried out in
the last 150 years need to be carefully evaluated. In this framework a structural health monitoring
system has been recently installed by the authors. A network of static and dynamic sensors
controls the relevant parameters related to the structural safety of the monument and the
protection of the artistic content. The paper describes the diagnostic investigations carried
out, including ambient vibration tests, crack pattern survey and identification of possible ongoing
degradation phenomena. Then the installed monitoring equipment is presented focusing
on the algorithms developed and implemented into a processing software to perform the
online automatic analysis of static data and the identification of modal parameters. Relevant
features extracted from monitoring data are then used as inputs for the application of damage
detection algorithms and the numerical calibration of a finite element model of the structure
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
Shaking table tests to compare semi-active control algorithms for variable dampers
No full textThe authors present and discuss the main results of a experimental campaign performed
on a near full-scale semi-actively controlled steel building, in the framework of a research
program financed by the Italian Department of Civil Protection. Four control
algorithms have been investigated through shaking table tests under seven different natural
earthquakes. They belong to the family of control algorithms based on a sound physical sense,
where semi-active devices are typically seen as smart damping devices for which the amount
of dissipation can be quickly regulated: usually they require less measurements, which often
are made in the close surroundings of the device; therefore, the computational effort is fairly
moderate and, in principle, it could be sustained by small, battery-powered computing systems.
After a literature review on semi-active control algorithms, the paper first summarizes
the logic behind the ones adopted in the tests. Then a direct comparison among them is done
on the basis of the results gained from the tests. Each of the control logics has been evaluated
and compared each other in terms of effectiveness in the reduction of interstorey drifts and of
amount of dissipated energy, leading to comments may be useful for the design of a semiactive
control strategy based on the use of such kind of variable devices
Non-linear dynamic analysis of masonry towers under natural accelerograms accounting for soil-structure interaction
No full textThe object of the paper is the influence of the soil-structure interaction on the dynamic response of masonry towers, for which a high level of stress is involved already in the static field. The relevant deformations and displacements at the base of the tower suggest that a significant volume of ground is engaged into the overall dynamic response, both as a participating mass and as a potential carrier of energy dissipation. In order to investigate this aspect and assess the sensitivity of the dynamic response of the soil-structure system to different soil characteristics, the non linear dynamic response of a case study is analysed, by including in
the model a significant volume of foundation soil and considering two different ground types. The numerical model is based on a specific Rigid Body and Springs approach, in which the structure is idealized as a mechanism made of rigid elements connected each to the other by axial and shear springs. The nonlinear behaviour is lumped into the springs assigning proper constitutive laws able to model the significant inelastic aspects of the constitutive behaviour and the meso-scale damage mechanisms with a moderate computational effort. Two types of foundation soil have been considered in order to perform the dynamical analysis accounting for
the soil-structure interaction: rock and deposits of compact gravel. For both models, non-linear dynamic analyses have been performed adopting natural records having different characteristics (with regard to the frequency content; distance from the epicentre and type of soil). Some interesting considerations are derived from this comparative study about a problem that is very actual for those who deal with non linear dynamics of structures, but yet is not much explored
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
Seismic retrofit decision-making of bridges based on life-cycle cost criteria
Full text linkIn a decision-making framework within the context of performance-based design,
life-cycle cost can be regarded as a suitable benchmark performance variable to quantify and
measure performance objectives for a set of (discrete) limit states. Life-cycle cost criteria is
identified as an economic term expressed in monetary units; it accounts for the initial construction
costs, the repair costs taking into account also the loss of revenue due to down time,
and finally the maintenance cost. The expected life-cycle cost is used for retrofit design of an
existing reinforced concrete bridge infrastructure that is located in south of Italy. The retrofit
design involves decision-making between a set of viable rehabilitation schemes, which mainly
isolate the simply-supported bridge deck from the pier cap or force the deck to have a uniform
displacement along its longitudinal direction. The proposed methodology for life-cycle cost
assessment takes the advantage of a closed- and analytic-form approximation in order to take
into account the time-varying profile of the probability of exceeding a set of structural limit
states. The presented procedure can be effectively used for screening among alternative proposed
upgrading strategies while satisfying prescribed reliability-based criteria. The optimal
solution is highlighted based on the minimization of the life-cycle cost
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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