1,720,964 research outputs found
Out of frame: expanding perspective into real space
No full textIt might sound strange to hear that our - locally - Euclidean environment can be thought as a special case inside the Projective space. According to linear perspective, indeed, we use to think at the opposite situation, or at projective images as special cases inside the isometric Euclidean space. But what happens when perspective breaks down the flatness of the picture plane (π) expanding its pattern beyond or across it? It becomes a three-dimensional space as well, distorted according to the projective pattern, namely a Relief-perspective, whose illusionary strength is empowered by its physical accessibility. Paraphrasing Rudolph Arnheim, it becomes a polarized pyramidal space whose ideal apex (A), working as a vanishing point, can stay in front as well as behind the sight point (S), along the viewing line (Fig. 1). In the first case an accelerated perspective illusion is generated, where represented space appears longer than it actually is (i.e. apex at Aa). In the second case, a decelerated perspectival illusion is achieved, where represented space appears shorter than it really is (i.e. apex at Ad). The two effects can also be combined in the same space. In both situations the illusion can be more or less emphasized by increasing or decreasing the distance between the perspective apex and viewpoint. From a geometrical point of view, the unlimited range of visually equivalent projective configurations descends from the non-bijective DNA of any single projection. Therefore two limit cases emerge: when the apex belongs to picture plane π (Ao) a pla-nar perspective is generated; when it moves at infinity (A∞) we are back to Euclidean space. In this sense Euclidean space can be seen as a special case of projective space. From an historical point of view, Leonardo Da Vinci already stated that perspective painting is based on two opposite pyramids, one having its apex at the sight point, the other at the horizon distance. Geometrical principles and graphic applications carried on by either traditional procedures or digital simulations will be dis-cussed, emphasizing the homological relationships among real space, relief-perspective spaces, perspective images. Last but not least, the educational power of this approach in the architectural design curricula will be highlighted, and some selected projects concerning three-dimensional thrompe l’œil, developed by master students from the course Geometrical Complements of Graphic Representation at the Polytechnic of Milan, will be shown
Neapolitan open-staircases vaulted system
No full textThe vaulted open-staircases system in Naples (Italy) is one of the most interesting expressions of the building art. Therein, the functions of the arch and vault aren’t only related to the covering requirements and support, but they form a single whole with the definition of a path, where it shows the combination between the harmonic architectural function and the structural function. Springs from a dynamic architecture linked to the succession of ever-changing visual achieved through scenographic artifices and from the structural function. This allows to interpret the staircase entire system in relation to the form-stress ratio. This allows to interpret the entire system of the staircase in relation to shape-stress ratio.
Generally, the arches and vaults that compose the Neapolitan open-staircases do not differ in con-struction, in materials used or in construction techniques from those which constitute the building where the staircase is at service, but for plane impost geometric arrangement that must cover (and at the same time, support) the ramps of staircases.
The rampants (generally called 'gooseneck') can be realized by arches or vaults. The vaults, however, in addition to the characteristic of lay down plane at staggered levels, have geometric characteristics of shape and construction due to the particular type of the dismount or relax walkway. Through the survey operations and consequent staircases plant geometric analysis, have been classified the dif-ferent configurations from the vaults to cover the different staircase spaces. The geomet-ric-configurative analysis, accompanied by the realization of three-dimensional models, has led to a typological characterization about the structure of rampant and the staircase type, where the most frequent type is closed on three sides and open on the courtyard intended as scenic background. From this geometric analysis came out the following main correspondences depending on the ramps structure: mid rampant barrel used in the staircases with free shaft; sail vault in support of the dis-mount or relax walkway; cross rampant present in walling staircases or in pillared shaft system
Geometry and architecture: the shape and curves in the nineteenth century drawings of the “Regio Teatro” in Cagliari
No full textStarting from Vitruvian models, theatres changes their geometries through centuries. Between sixteenth and seventeenth centuries, they lost their classicist unity for a model organized into two distinct parts: the perspective space of the stage and the auditorium. The early modern building introduced an elongated auditorium drawn with U shape. The following geometrical evolutions were closely conceive to guarantee perfect views from the stands to the stage. In a second time, the U-shaped plan is declined into mixtilinear profiles, reaching finally to elliptical or ovals shapes or to horse-shoe shaped theatres. The Teatro Regio is located in the Castello of Cagliari, along the medieval city walls. The history of this theater began in 1767 with the project commissioned by the Baron Francesco Zapata to the piedmontese engineer Saverio Belgrano. The archives keep some drawings illustrating an U-shaped solution for this plan. In 1831, the early building was redesigned by Giuseppe Cominotti on a horseshoe shape. A third and final project is directed by Gaetano Cima in 1836 when the architect is committed to complete his work. The Teatro Regio was badly damaged by the bombings of Cagliari in 1943, during World War II
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Exploration of Straw Fiber as Reducing Agent Utilization in Rotary Hearth Furnace Process for Direct Reduced Iron Production
No full textStraw fiber is a waste obtained by jet milling after extracting valuable substances form corn straw through steam explosion-washing-mechanical carding process. At the same time, it is also a clean and renewable reducing agent. In this study, physical and chemical characteristics of straw fiber were investigated firstly. The usage of straw fiber in rotary hearth furnace process for direct reduced iron production was then discussed. The results show that on one hand, fixed carbon content in straw fiber is low, which is unfavorable for the productivity of direct reduced iron; on the other hand, ash and sulfur content is also low, which improves the quality of direct reduced iron. Besides, the fibrous structure is conducive to improving the pelletizing performance of carbon-containing pellets, thus reducing an additional amount of binder. Compared with common reducing agents, straw fiber provides better reduction effect, and straw fiber carbon-containing pellets possess higher compressive strength and larger volumetric shrinkage, which is beneficial to increase the thickness of the whole material layer in rotary hearth furnace. In addition, these carbon-containing pellets also have advantages of lowering C/O ratio and shortening reduction time. The appropriate C/O and reduction time are 0.8 and 15 min, respectively, and the particle size of straw fiber below 0.15 mm has better reduction effect. This study aims to provide theoretical and technical basis for the utilization of straw fiber in rotary hearth furnace process
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe 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
Textual criticism of drawings in historical/scientific treatise on representation. The Caput in De prospectiva pingendi
No full textThe proposed article aims to provide a methodological contribution to reading historical/scientific treatise on representation. In philology, textual criticism is the critical analysis of literary texts aimed at a deep understanding of the text and the author’s intentions. In historical/scientific treatises on representation, the work is composed of two “texts” of equal importance: one is literary, the other graphic. In these cases therefore, textual criticism should be applied to both “texts” at the same time. The case study chosen to investigate the potential of the research method is the first illustrated treatise dedicated to perspective: De Prospectiva Pingendi by Piero della Francesca. While this is a work aimed at painters, the theoretical principles and applications of perspective are also addressed, contributing to a definition of the scientific basis of descriptive geometry. The bibliography is very rich, including essays by C. Winterberg (1899), G. Nicco Fasola (1942), M. Kemp (1994), and K. Andersen (2007). However, it should be noted that graphics that could explain the reasoning behind Piero della Francesca’s drawing are not always included, especially in critical editions. Among the pages of the treatise, proposition 8 in book III holds particular importance for the proposed investigation. Here, Piero constructs the perspective of a human head, which is first positioned straight (frontal position), and then looks upwards (generic position). This proposition represents a major step in that for the first and only time, the author addresses the theme of free forms. To read this proposition critically, it is necessary to refer to a hybrid digital model (polygonal mesh, T-Splines, and NURBS) developed by studying the codices housed in the Palatina Library in Parma and the Municipal Library in Bordeaux. Construction of the digital model allows us to understand both Piero’s refined spatial reasoning and its relative plane rendering in an original reverse path that highlights the scientific nature of the entire treatise and the potential of digital representation as applied to the textual criticism of drawings
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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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