1,720,985 research outputs found
Assessment of the effectiveness of a dehumidification system by emission of electromagnetic fields: Proposal of a protocol
No full textIn this paper the operation of a dehumidification system has been studied in operating conditions and a protocol for the assessment of its effectiveness is proposed. The physical principle of the used system is based on the interaction of a pulsed electromagnetic field with the masonry materials affected by rising damp phenomena. As it is well known, water has a crucial role in decay mechanisms both by a physical and by a chemical point of view. In fact, soluble salts transport phenomena, biological growth, stress due to expanding clays, freeze–thaw cycles, are among the most diffused examples of decay mechanisms. The target of any dehumidification systems, as the one under analysis, is very ambitious and crucial in the field of cultural heritage conservation; hence starts the authors need in understanding the involved physical mechanisms and in evaluating the effectiveness of these systems. Literature reports laboratory tests carried out with the target to acquire a better knowledge of the interaction mechanism between pulsed electromagnetic field and masonry materials, with and without water presence. Very often laboratory tests are followed by tests on pilot site chosen on purpose. In the example presented in the paper, ground floor masonries belonging to an historical building, with evident rising damp phenomena, was chosen. The building is located at Saltino, Reggello close to Florence, at 995 m asl. The rising of water affects at different levels several rooms of the building at ground floor, but on the north side of the house, the effects are greater. This contribute also proposes preliminary ideas to draw a standard aimed at build up a protocol for the performance assessment of dehumidification systems, based on different physical principles. A full knowledge of physical principles is mandatory to optimize the effectiveness of these systems. The procedure to assess the effectiveness of these systems must be standardized identifying the environmental parameters to be checked in relation to the ones directly measured on the masonry
INTEGRATION OF EFD, MRM AND IRT FOR MOISTURE MAPPING ON HISTORIC MASONRY: STUDY CASES IN NORTHERN ITALY
No full textAmong the innovative techniques for detecting moisture on the historical masonry, EFD (Evanescent Field Dielectrometry) presents a high potential for providing the absolute measure of the water content, to map the salts distribution on the surfaces, without requiring to sample the materials under investigation. The integration with IRT (Infrared Thermography) results particularly useful on stone/cobbles solid masonry, because of the least reliability of the gravimetric tests on this type of wall, especially on samples collected from the layers beneath the surface. The paper presents the results on two historical buildings located in Lombardy, and the discussion regarding advantages and limits of the application: the Royal Villa in Monza and the church of Saint Ignacious in Ponte (SO)
On the Use of Haloalkane/Acrylate-Based Holographic Gratings as Compression and Rotation Sensors
Full text linkIn this work, we test the effectiveness of using highly transparent holographic phase reflection and transmission volume gratings based on multifunctional acrylates as linear compression and rotation sensors. The gratings are recorded in a holographic mixture based on multi-reticulated acrylate and haloalkanes. To activate the photo-polymerization process, we used a mixture of 6-oxocamphore and rhodamine 6G. The mixture is a simplified version of the mixture used in previous works and shows some interesting features mainly in connection with the different roles played by the rhodamine 6G dye at different writing wavelengths (Formula presented.) = 532 nm and (Formula presented.) = 460 nm. Regarding reflection gratings, the maximum achieved diffraction efficiency is ≈50% and their use as linear compression sensors produces a shift in the reflection peak of 2 nm. Following the removal of compression, the grating slowly returns to the initial state. Regarding transmission gratings, the maximum achieved diffraction efficiency is ≈45% and they demonstrate very high sensitivity to even small rotations in a free-standing configuration
Spectral, morphological and dynamical analysis of a holographic grating recorded in a photo-mobile composite polymer mixture
Full text linkWe report on the morphological, spectral and dynamical characterization of one-dimensional transmission holographic volume phase gratings, whose refractive index contrast and nanometric pitch are dynamically controlled by an incident laser light. The grating is obtained by the photo-polymerization of a recently developed photo-mobile holographic composite polymer material. The observed changes in the refractive index contrast and grating pitch strongly suggest that the reversible all-optical real-time modulation of the obtained diffraction efficiency is induced by nano-fluidics
Top-Performance Transmission Gratings with Haloalkanes-Based Polymeric Composite Materials
No full textWe report on highly transparent holographic phase transmission volume gratings recorded in the visible region at (Formula presented.) = 532 nm. The maximum measured diffraction efficiency is higher than 80% with a grating pitch of (Formula presented.) ≈ 300 nm and a refractive index modulation (Formula presented.) n ≈ 0.018. To obtain these results, we used a holographic mixture based on multi-reticulated acrylate and haloalkanes (1-bromo-butane and 1-bromo-hexane) and a synergic combination of camphore-quinone, which has a maximum absorbance at c.a. 470 nm, and R6G, here used as co-initiator, to efficiently initiate the photo-polymerization process. High transparent and high efficient holographic structures based on polymers can find applications in many research fields including integrated optics, sensors, high density data storage and security
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
- …
