1,720,964 research outputs found
VARISA - A VARIable Stiffness soft robotics Arm based on inverse pneumatic actuators and differential drive fiber jamming
No full textSea Shell Bioinspired Variable Stiffness Mechanism Enabled by Hybrid Jamming Transition
No full textLayer jamming and positive pressure jamming demonstrated great potential in soft robotic applications. The combination of these technologies can increase the performance of variable stiffness-oriented designs. Inspired by the shape of sea shell radial ribs, we introduce a planar lightweight device that can be easily adapted to different application scenarios, providing both significant stiffness variation and high load-bearing capabilities. Exploiting the ease of the system in terms of design and manufacturing, we tested the device with a different number of layers. It shows higher performances than standard layer jamming systems: in particular, the 1 layer per side version (7.5g) shows a variable stiffness ratio of 64:1 and a force required to reach a 10 mm deflection equal to 19N. The same values for the 5 layers per side version (17.2g) are 42.5:1 and 62N. These values are in line with the most promising innovative approaches reported in the literature on layer jamming. In addition, the presented results allow making a comparison between the introduced device and the biological counterpart in terms of performance, showing the validity of sea shells as a bioinspiration source for variable stiffness systems
Harnessing Mechanical Instabilities in the Development of an Efficient Soft Pump for an Artificial Heart Ventricle Simulator
Full text linkWhile mechanical instabilities were traditionally considered as failure events, triggering them in a controlled fashion recently paved the way to novel functionalities and improved performance, especially in systems made of soft materials. In this article, we present a novel cable-driven compliant mechanism whose pumping function is based on mechanical instabilities. Specifically, the cables are arranged in helices wrapped around a soft shell chamber that hosts the fluid, and upon pulling, they cause its dramatic volumetric reduction by inducing a torsional instability that maximizes the pumping action. We introduce a geometrical model to describe the deformation kinematics of the soft pump and a finite element model to investigate the detailed postbuckling behavior of the shell. Both models show very good agreement with the experiments. The computational model allowed us to perform a parametric study of the behavior of the soft pump as a function of the number of turns of the cables and their displacement upon pulling. Finally, we demonstrate experimentally the applicability of our soft pump as an artificial ventricle simulator, since the pumped volumes at physiologically relevant afterload pressures approach those found in left and right human ventricles
Variable stiffness structure inspired by seashells
No full textVariable stiffness is typically employed in soft robotics to address the trade-off between compliance and the ability to generate stability when required. Among the several approaches investigated, jamming transition systems show remarkable stiffness performance and fast response. Building upon the preliminary study on a seashell bioinspired variable stiffness structure, here we extend the design space through a parametric study supported by a finite element model based on commercially available software. The study allows establishing the relationship between the design parameters and the stiffness performance. Moreover, the optimal configuration in terms of performance to energy consumption is identified and compared to previous similar approaches. Finally, the low computational cost of the finite element model demonstrated to be an effective tool for the analysis of complex geometries, thereby establishing a foundation for the development of cost-effective and lightweight soft robotic devices empowered by variable stiffness capabilities (e.g. a wearable device for assistance)
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
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