1,720,969 research outputs found
Modern pressure measurement technology and structural design for wind: a new collaborative paradigm for wind and structural engineers
Full text linkAgainst a brief historical overview, this paper presents the Database-assisted Design (DAD) approach, a conceptually simple, transparent, and rigorous approach to structural design for wind, which fully exploits the potential of modern computational capabilities and pressure measurement technology. A novel collaborative framework between wind and structural engineers assures the effectiveness of this approach and establishes clear lines of responsibility for their respective contributions to the design process. Wind effects with design mean recurrence intervals are determined by DAD more accurately than is possible by using conventional methods for estimating aerodynamic loads, dynamic effects, and wind directionality effects. The DAD approach is consistent with Building Information Modeling (BIM) requirements, and is in principle applicable to most structures for which wind pressures are determined by aerodynamic testing or CFD methods
Estimation of Wind Effects on High-Rise Structures by the Global Load Effects and Database-Assisted Design Methods
Full text linkStructural wind effects on high-rise buildings subjected to extreme directional winds can be determined by one of three methods: (i) HFB (high frequency balance), used only for buildings with very complex shapes or with many fine-scale features, (ii) GLE (global load effects), commonly used in current commercial wind engineering laboratory practice, and (iii) the DAD (Database Assisted Design) method. The purpose of this paper is to consider the advantages and drawbacks of the GLE and DAD methods, both of which use the multi-channel pressure scanning system. Following these methods’ brief description, it is noted that the GLE method has over DAD the advantage of significantly lower computational time requirements. This is shown to be due to GLE’s basic assumption that the peak Demand-to-Capacity Indexes (DCIs) of all the building’s structural members occur at the same time. It is then shown that this assumption is incorrect, and that it results in the GLE method’s underestimation of all the structural members’ DCIs, inter-story drift ratios, and top floor accelerations. In contrast, the DAD method is shown to satisfy all applicable strength and serviceability performance criteria. However, the computational resources required for DAD’s use exceed the resources typically available to small or mid-sized structural design offices. Recent research results concerning the DAD method are then noted, and various approaches are proposed to the reduction of the DAD method’s computation time requirements by up to two orders of magnitude
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
Chaotic transitions in deterministic and stochastic dynamical systems: applications of Melnikov processes in engineering, physics, and neuroscience
No full textThe classical Melnikov method provides information on the behavior of deterministic planar systems that may exhibit transitions, i.e. escapes from and captures into preferred regions of phase space. This book develops a unified treatment of deterministic and stochastic systems that extends the applicability of the Melnikov method to physically realizable stochastic planar systems with additive, state-dependent, white, colored, or dichotomous noise. The extended Melnikov method yields the novel result that motions with transitions are chaotic regardless of whether the excitation is deterministic or stochastic. It explains the role in the occurrence of transitions of the characteristics of the system and its deterministic or stochastic excitation, and is a powerful modeling and identification tool. The book is designed primarily for readers interested in applications. The level of preparation required corresponds to the equivalent of a first-year graduate course in applied mathematics. No previous exposure to dynamical systems theory or the theory of stochastic processes is required. The theoretical prerequisites and developments are presented in the first part of the book. The second part of the book is devoted to applications, ranging from physics to mechanical engineering, naval architecture, oceanography, nonlinear control, stochastic resonance, and neurophysiology
Modern pressure measurement technology and structural design for wind: a new collaborative paradigm for wind and structural engineers
No full textAgainst a brief historical overview, this paper presents the Database-assisted Design (DAD) approach, a conceptually simple, transparent, and rigorous approach to structural design for wind, which fully exploits the potential of modern computational capabilities and pressure measurement technology. A novel collaborative framework between wind and structural engineers assures the effectiveness of this approach and establishes clear lines of responsibility for their respective contributions to the design process. Wind effects with design mean recurrence intervals are determined by DAD more accurately than is possible by using conventional methods for estimating aerodynamic loads, dynamic effects, and wind directionality effects. The DAD approach is consistent with Building Information Modeling (BIM) requirements, and is in principle applicable to most structures for which wind pressures are determined by aerodynamic testing or CFD methods
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
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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