1,721,548 research outputs found
Structural Survey and Empirical Seismic Vulnerability Assessment of Churches in the Historical Center of Cusco
No full textThe seismic vulnerability assessment of buildings represents a fundamental step for seismic risk prevention and mitigation, especially in seismic-prone areas where severe damage scenarios are expected or where valuable assets are present. The city of Cusco, whose historic center has been a UNESCO World Heritage site since 1983, has a long list of seismic events that caused extensive damage. Being part of the international heritage, churches are characterized by great architectural and cultural value, and their preservation is crucial. In this paper, the seismic vulnerability assessment of churches within the historic center of Cusco is presented. The assessment is made through a two-step process. First, data on churches are collected with a structural survey at the urban scale. Second, collected data are used to determine the seismic vulnerability with an empirical method that combines field observations and engineering judgments. The most vulnerable churches in the city center are identified, and their primary structural deficiencies are determined through this process
Numerical simulations of structural modifications at a Ni-Zr sliding interface
No full textNumerical calculations have been employed to study the early stages of mechanical deformation processes due to the application of shear stress in a composite system containing a sharp interface separating two chemical species. Simulations showed that the shear stress, applied parallel to the interface, induces the generation at the interfacial region of atoms with a number of nearest neighbors different from the equilibrium one. The atoms with defective coordination gradually arrange into more complex defective structures, the dynamics of such defects promoting the migration of atomic species and their gradual mixing near the interface. The latter process finally determines the amorphization of interfacial atomic planes
Vibrational stability of graphene under combined shear and axial strains
No full textWe study the vibrational properties of graphene under combined shear and uniaxial tensile strain using density-functional perturbation theory. Shear strain always causes rippling instabilities with strain-dependent direction and wavelength; armchair strain contrasts this instability, enabling graphene stability in a large range of combined strains. A complementary description based on membrane elasticity theory nicely clarifies the competition of shear-induced instability and uniaxial tension. We also report the large strain-induced shifts of the split components of the G optical phonon line, which may serve as a shear diagnostic. As to the electronic properties, we find that conical intersections move away from the Brillouin zone border under strain, and they tend to coalesce at large strains, making the opening of gaps difficult to assess. By a detailed search, we find that even at large strains, only small gaps in the tens-of-meV range open at the former Dirac points
Molecular dynamics investigation on the role of sliding interfaces and friction in the formation of amorphous phases
No full textMolecular dynamics simulations have been employed to gain deeper insight into the microscopic dynamics of crystalline solids when mechanical forces are applied. In particular, the study focuses on the atomic scale mechanisms involved in the shear-induced relative sliding of atomic planes. Two different systems have been investigated, namely a smooth phase boundary between crystalline Ni and Zr metal lattices and a crystalline bulk region of the NiZr2 intermetallic compound. In both cases, a conventional tight-binding potential was used to reproduce the interatomic forces. Numerical calculations demonstrate that the application of shear stresses determines the deformation of the crystal and the formation of a sliding interface. A density decrease, and a corresponding increase in the average free volume available to atomic species, is observed near the sliding interface. Chemical disordering processes take place at the interface as a result of frictional forces operating during the shear-induced sliding. The generation of chemical disorder is accompanied by the accumulation of structural disorder that determines the formation of an amorphous domain at the interfacial region in both the binary and the intermetallic systems
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
L’esplorazione floristica nel Sulcis (Sardegna sud-occidentale)
No full textHere is show the account of floristic exploration in the Sulcis area. This study
is based on existing bibliography and has been done through herbarium researches in
the main national and international centres. The investigations allowed to take a census
of all the works carried out in the Sulcis area, to verify the authors and the explored
environment as well as the exsiccata stored in the various herbarium. From the analysis
emerges that the coastal and the lagoon areas have been deeply studied since the second
half of the XVIth century, the hill and the foot of the mountain areas since after the
second world war, while the mountain areas and the rivers are nowadays still less
known and sometimes totally unexplored. Is finally put in evidence which areas have a
greater need to be researched both from floristic and vegetational point of view
Non-invasive imaging of ancient foundations status in Venice (Italy) using the Electrical Resistivity Tomography technique
No full textElectrical Resistivity Tomography (ERT) has proved to be an outstanding non invasive technique to evaluate the degradation state of historical buildings, both under normal dry conditions and when materials are saturated with salt water.
An ERT test was undertaken along a portion of a canal’s wall located in Venice (Italy). The walls of the canal serve to protect the bank from damage, caused mainly by wave action generated by the transport vessels.
Preliminary information, a.s.l., collected by visual inspection, reported local absence of cement between the bricks, and the presence of less compacted materials behind the bricks. Based on these evidences, the ERT survey was performed to investigate the walls conditions both above and below m.s.l. The estimated distribution of the electrical resistivity suggested the presence of highly degraded zones within the first 30 cm of the wall’s surface. These findings were useful for the restoration project
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
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