1,720,956 research outputs found
Tuned-Inerter-Based-Dampers with linear hysteretic damping for earthquake protection of building structures
Full text linkThe inerter is a two-terminal device that generates a resisting force proportional to the relative acceleration between its two terminals. To date, three main types of inerters have been introduced in the literature based on inertial mass (inertance) generation mechanisms: fluid inerters, rack-and-pinion inerters, and ball-screw inerters. In such mechanisms, significant levels of inertance can be generated while keeping the actual mass to a minimum.
This feature of inerters has attracted many researchers in the earthquake engineering community to explore their use for protecting building structures against earthquakes. For this purpose, inerters are often combined with a stiffness and a damping element in various confiigurations to form so-called tuned-inerter-based-dampers (TIBDs). There are three TIBDs mostly found in the literature: (1) tuned-viscous-mass-damper (TVMD); (2) tuned-inerter-damper (TID); (3) tuned-mass-damper-inerter (TMDI).
One common layout of the three TIBDs is they have at least two elements connected in parallel. In the TVMD, the two elements are viscous damper and inerter, while in the TID and TMDI, the two elements are spring and viscous damper. For the first time, the possibilities for the devices to exhibit hysteresis through the two elements in parallel are explored in this thesis. In particular, two linear hysteretic damping concepts are discussed: (1) complex damping; and (2) complex stiffness.
Furthermore, novel concepts of passive tuned inerter dampers with linear hysteretic damping, namely the tuned inerter hysteretic damper (TIhD) and the tuned mass hysteretic damper inerter (TMhDI) are introduced. Both concepts were developed based on the well established TID concept whereby the parallel connected viscous damping and spring elements are replaced by a complex stiffness model. The idea is to design a more realistic tuned inerter damper that captures the hysteretic behavior of the dampers. The aim is to develop a modified method to solve the equation of motion of structures with complex stiffness in the time domain.
Finally, a shake table experiment was performed for a three-storey structure equipped with a TMhDI device on its base storey, subjected to both harmonic and earthquake base inputs. The TMhDI uses gel dampers as its hysteretic damping element. The inerter element was realised by a flywheel inerter which was designed by using a frictionless linear guide mechanism. For comparison, a shake table experiment was also performed for the same three-structure equipped with a TMDI device on its base storey level. The viscous damping element was realised using eddy current dampers. It is shown that the analytical model of both TMhDI and TMDI are in good agreement with the experimental results. Furthermore, these experiments also confirm the distinction between both devices, particularly in the structure's second and third modes of vibrations, where the structure equipped with the TMhDI has a larger response
THE USE OF AN INERTER FOR BASE-ISOLATION SYSTEM IN A SINGLE-DEGREE-OF-FREEDOM STRUCTURE
No full textThis paper presents seismic performance of a single-degree-of-freedom (SDOF) structure equipped with a base isolation system (BIS). Common BIS employs rubber material to provide lateral flexibility in order to minimize the transmitted energy induced by the ground motion to the structure. The concept is to lower the structural natural frequency such that it falls far below the pre-dominant frequency of most earthquakes. A similar effect can also be achieved by using a device called inerter, a two-terminal device generated forces proportional to the relative acceleration between its two terminals. Instead of reducing stiffness, inerter amplifies the theoretical mass of the structure without significantly increase its physical mass. It is because, depending on the inertance-generation mechanism, an inerter is capable of generating inertance – a constant ratio of forces and relative accelerations of the inerter – several times higher than its physical mass. In this paper, the effectiveness of inerter for use as a BIS is compared to the common BIS concept. The results show that, for a similar natural frequency level, a BIS with inerter has narrower response around the resonance in the frequency domain. Furthermore, in the time domain analysis, the structure with an inerter has a lower response compared to the structure with a traditional BIS when subjected to a long-period earthquake ground motio
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
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
Utilising computational fluid dynamics to investigate damping effects in fluid inerter-based vibration control devices
No full textAbstract Over the past two decades, inerters have attracted significant attention in structural control. Numerous applications in engineering fields have proposed employing inerter-based control devices to mitigate structural vibrations. While theoretical studies have demonstrated performance enhancements, practical implementation and experimental validation have remained limited primarily due to cost and technical challenges. Studies conducted with the physically built inerters have showed discrepancies between theoretical model of the inerter and its actual performance because of factors such as nonlinearities and damping effects. Computational Fluid Dynamics (CFD) can provide a more accurate model of the inerter without the need for costly experimental setups. This paper presents a CFD analysis aimed at evaluating the actual performance of a fluid inerter-based control device for vibration mitigation of single degree of freedom (SDOF) structure. The accurate modeling of the inerter obtained through CFD is used to evaluate the performance of the inerter-based control device. The results reveal an important difference between vibration mitigation performance when comparing the ideal theoretical model and the CFD model.</jats:p
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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