1,720,964 research outputs found
Multifunctional sub-100 μm thickness flexible piezo/triboelectric hybrid water energy harvester based on biocompatible AlN and soft parylene C-PDMS-EcoflexTM
No full textNanogenerators have emerged recently as a new technology for harvesting energy from renewable and clean energy sources. Water in nature carries high amounts of kinetic and electrostatic energy; it is ubiquitous and widely accessible in different forms: i.e. as droplets, flows or waves. Either piezoelectric or triboelectric nanogenerators (PENGs, TENGs) have been shown to be effective for harvesting energy from liquids and ocean but the integration of both transduction mechanisms in a single hybrid device allows to exploit several operating conditions and to optimize performances, overcoming the limits of single components. Current piezo-tribo hybrid devices are mostly based on scarcely durable polymers or thick lead-based ceramic materials. Additionally, they are often limited to a specific application or environment due to their architecture and employed materials. In this work, a multifunctional, flexible and conformal hybrid nanogenerator (HNG) has been developed with a sub-100 μm thickness and with a novel combination of biocompatible thin-film piezo-ceramic and soft polymeric materials, for harvesting energy of different water sources, i.e. impacts, raindrops and buoying waves. The PENG component is based on a double-sided metallized AlN thin film, sputtered on polyimide. The TENG component is made of a metallized porous patch made of a mixture of PDMS and platinum-catalyzed silicone (EcoflexTM), encapsulated by a friction film of Parylene C surface-treated with UV/ozone. As a result, the HNG exhibits non-algebraic enhanced performances: the resulting power densities under tapping are ~ 6.5 mW/m2 for PENG, 65 mW/m2 for TENG, ~ 230 mW/m2 for HNG. Multifunctionality is demonstrated by harvesting energy from different water-conveyed sources (i.e. impacts/breakwaters, raindrops, buoying waves). In particular, the device shows optimal and reliable energy harvesting performance under strong impulsive impacts (~ 0.8 W/m2) and raindrops impacts (~ 9 mW/m2). A custom buoyant device, called piezo-JellyFish (pJF), is proposed to exploit the HNGs for harvesting wave energy, based on a connection of three HNGs acting as oral arms: this system yields ~ 3.2 mW/m2, with 3 cm-amplitude standing waves. Finally, the HNG exhibits optimal adhesion on the skin and can be also used for monitoring human motions, revealing its multifunctionality also as a wearable conformal sensor
Conformal, Ultra-thin Skin-Contact-Actuated Hybrid Piezo/Triboelectric Wearable Sensor Based on AlN and Parylene-Encapsulated Elastomeric Blend
No full textFlexible electronics based on piezoelectric/triboelectric devices is an attractive technology for human sensing. Their hybridization overcomes the limitations of single components, resulting in compliant skin sensors with enhanced performances and applicability. Such hybrid devices are typically based on wide-area scarcely durable polymers or lead-containing piezoelectric materials; they are often not biocompatible and poorly skin-adaptable, lacking in multifunctionality. In this work, a novel compliant, conformal hybrid piezoelectric-triboelectric ultra-thin wearable sensor made of biocompatible materials is reported. The device is in contact with skin through an ultra-soft patch covered on both sides by a thin friction parylene film. Its working principle is unprecedently based on three simultaneous, complementary and mutually enhancing effects: piezoelectric, skin-contact-actuation, and piezo-tribo hybrid contact. The device can detect, with high sensitivity and wide measurement range, both the impulsiveness of sudden motions and the slower micro-friction phenomena due to skin deformations, ensuring a stable and repeatable identification of bio-signals typical of body movements. The device multifunctionality is shown for identifying gait walking, distinguishing hand gestures with a 5-sensor system on the hand back, and monitoring human joints motions (neck, wrist, elbow, knee, ankle). The assessed energy harvesting capabilities demonstrate the suitability for fabrication of more complex self-powered sensing systems
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
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
Wearable Multiple Body Signal Monitoring System with Single Biocompatible AlN Piezoelectric Sensor
Full text linkRemote monitoring of vital body signals has drawn the attention of late, particularly with the burst of COVID-19. Wearable devices are started to be widely used for non-invasive health monitoring tasks. This work presents a wearable system for multiple body signal monitoring using only one biocompatible aluminum nitride piezoelectric sensor and a custom wireless electronic device for data acquisition and transmission. The proposed sensor has been customized for the suprasternal notch, where we can simultaneously extract heart rate, respiration rate, and deglutition events. These parameters are helpful for the remote diagnosis of multiple diseases like cardiac arrhythmia, asthma, and dysphagia. Moreover, heart sound components have been derived from the same signal, providing critical information about heart health and insight into possible heart diseases. The preliminary experimental results show that the proposed wearable system can be used for personalized healthcare applications and offers a promising solution for unobtrusive remote health monitoring
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