1,721,043 research outputs found
Electroadhesion Suction Cups
No full textSuction cups are the light bulbs of robotics and automation. They are simple, reliable, yet energy-hungry, and require a bulky and noisy vacuum infrastructure. This work reports Electroadhesion (EA) Suction Cups: soft, silent, monolithic, electrically-driven grippers, with a power consumption of only 1.5 W, that can grasp flat and curved objects, with smooth or rough surfaces, holding payloads up to 1.5 kg. This performance is enabled by a deeper understanding of the contact mechanics of electroadhesion systems. A thin and soft membrane containing interdigitated electrodes zips onto the object driven by electrostatic forces, conforming to the object's shape and thus establishing large-area contact. The lifting force is transmitted to a robot arm through a small pillar connected at the center of the membrane. This design maximizes the peeling force and enables the formation of passive vacuum inside the conical chamber formed when the membrane stretches during lifting. Object release is obtained by turning off the voltage and optionally by opening a valve to quickly break the vacuum. EA suction cups address many shortcomings of widely used vacuum-driven grippers, offering a compact, fully electric, and energy-efficient solution that meets the needs for efficiency and portability in both industrial and service robotics
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
Microfabrication of capillary electrospray emitters and ToF characterization of the emitted beam
No full textMicrofabrication, assembly, and characterization of internally fed arrays ofelectrospray emitters for spacecraft propulsion are discussed. Several different emitter geometries were fabricated, and the sprayed beams from these emitters are characterized for their ion/droplet composition. It is shown that with smaller inner diameters, ionic mode of operation can be achieved more easily, due to the increase in the hydraulic impedance. Up to 2000 sIsp was measured from capillaries with 5μm inner diameter and 100μm with 750V extraction voltageusing EMI-BF4. Due to the small dimensions of the microfabricatedcapillaries, the onset and ionic mode operation voltages can be significantly lower than macroscopic emitters. The major failure mode for the emitters was the liquid overflow from the capillary tip, which can be resolvedthrough coatings that wet the ionic liquids differently. A detailed study of the wetting behavior of two ionic liquids is also presented for variousmaterials compatible with silicon microfabrication technolog
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
Voltage tuning of the resonance frequency of electroactive polymer membranes over a range of 75%
Full text linkWe report on a novel technique to control the resonance frequency of polymer membranes, without additional external actuators. An electrostatic force is used to apply compressive stress to a dielectric electroactive polymers membrane, consisting of a 25 micron thick, 1 to 4 mm diameter, polydimethylsiloxane (PDMS) film bonded onto patterned silicon or Pyrex wafers. Both sides of the membranes are rendered conductive by low-energy metal ion implantation. Ion implantation is chosen because it stiffens the membrane much less than sputtering a film of similar thickness. The initial resonance frequency of the membrane is given by its geometry, the Young’s modulus and stress of the composite film. The technique presented here allows tuning the resonance frequency from this initial value down to zero (at the buckling threshold) by adding compressive stress due to a voltage difference applied to the electrodes on both sides of the membrane. We have measured a reduction of the first mode resonance frequency of up to 77% (limited by dielectric breakdown) for ion-implanted membranes. The tuning is repeatable and allows for continuous variation. Excellent agreement was found between our measurements and an analytical model we developed based on the Rayleigh-Ritz theory.LMT
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
Sexual Abuse of Children in Comparative and International Perspective
No full textChild sexual abuse (CSA) is a chronic problem that can occur in any family or any country. National governments, international organizations, and non-governmental organizations have given it increasingly high priority in recent decades. Scholars also have given CSA increased attention though more at clinical case-study than at policy levels. Some basic epidemiological conclusions can be drawn. Girls are at considerably greater CSA risk than boys, but in some places boys also experience high levels of victimization. Perpetrators are much more likely to be male than female, and family members or acquaintances than strangers. Victimization is not only by adults but also by young people. Cross-national knowledge is underdeveloped. Comparative studies are rare, partly because they are expensive and complicated to organize but also because of fundamental differences in legal and research definitions of the behaviours studied. Only a few countries have successfully established long-term surveys and data series that provide a solid empirical basis for describing CSA and changes in its nature, prevalence, and incidence. The US data provide a firm basis for concluding that the incidence of CSA in that country has dropped substantially since the early 1990s in parallel with drops in rates of violence generally and sex crimes specifically. The CSA research mission is to build the tools and infrastructure to learn what is happening today, and has happened over time, cross-nationally and in all individual countries, in order to develop better policies at the national and international level
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