1,720,992 research outputs found
Nanogenerators for Human Body Energy Harvesting
No full textHumans generate remarkable quantities of energy while performing daily activities, but this energy usually dissipates into the environment. Here, we address recent progress in the development of nanogenerators (NGs): devices that are able to harvest such body-produced biomechanical and thermal energies by exploiting piezoelectric, triboelectric, and thermoelectric physical effects. In designing NGs, the end-user's comfort is a primary concern. Therefore, we focus on recently developed materials giving flexibility and stretchability to NGs. In addition, we summarize common fabrics for NG design. Finally, the mid-2020s market forecasts for these promising technologies highlight the potential for the commercialization of NGs because they may help contribute to the route of innovation for developing self-powered systems
Modeling and Measurement of an Ultrasound Power Delivery System for Charging Implantable Devices Using an AlN-Based pMUT as Receiver
No full textUltrasound power delivery can be considered a convenient technique for charging implantable medical devices. In this work, an intra-body system has been modeled to characterize the phenomenon of ultrasound power transmission. The proposed system comprises a Langevin transducer as transmitter and an AlN-based square piezoelectric micro-machined ultrasonic transducer as receiver. The medium layers, in which elastic waves propagate, were made by polydimethylsiloxane to mimic human tissue and stainless steel to replace the case of the implantable device. To characterize the behavior of the transducers, measurements of impedance and phase, velocity and displacement, and acoustic pressure field were carried out in the experimental activity. Then, voltage and power output were measured to analyze the performance of the ultrasound power delivery system. For a root mean square voltage input of approximately 35 V, the power density resulted in 21.6 mu W cm(-2). Such a result corresponds to the data obtained with simulation through a one-dimensional lumped parameter transmission line model. The methodology proposed to develop the ultrasound power delivery (UPD) system, as well as the use of non-toxic materials for the fabrication of the intra-body elements, are a valid design approach to raise awareness of using wireless power transfer techniques for charging implantable devices
Flexible teg on the ankle for measuring the power generated while performing activities of daily living
No full textIn this work, a commercial flexible thermoelectric generator (f-TEG) was used to harvest the body thermal energy during the execution of activities of daily living (ADL). The f-TEG was placed at the level of the ankle, and the performed activities were sitting at the desk and walking. In the first stage of measurements, tests were performed to choose the value of the resistor load that maximizes the power output. Then, while performing ADL, the values of generated power were in the range from 100 to 450 μW. Moreover, while users are walking, the pattern of the output signal of f-TEG is compatible to a sine function with frequency close to that one of human gait. This preliminary result may represent a new way to study the movement of human body to recognize ADL
Measurement system for classification of hand's gesture
No full textThe goal was to create precise hardware that would be able to measure signal of myopotentials from defined area of forearm for the computer analysis without external noise and with right amplification. The second goal was to program an algorithm which could classify specific gestures of hand based on an analy17sis of myopotencial signals. The computer software was programmed in C# programming language. Signal processing and drawing to user interface was in real time. The one of five possible gestures that user made was analysed by using fuzzy logic and designed system of scaling. It was developed fuzzy classification which is able to recognize gestures with high accuracy
Consumer perceptions on smart wearable devices for medical and wellness purposes
No full textThis study examined Smart Wearable Devices (SWDs) in the form of smartwatches, fitness trackers, smart textiles and jewelry for medical and wellness purposes in the IoT era. Forty-five volunteers participated in a semi-structured interview. The data collected from respondents was used to study consumer perceptions of SWDs. Although many of the participants in the study had heard of SWDs, almost none knew what Body Sensor Networks (BSNs) were. An investigation was also conducted to find a solution to the problem of abandoning the use of SWDs. In the results, many respondents stated a 'real need' for the device as the most important feature for not abandoning it. Some of the smartwatches, fitness trackers, smart textiles and jewelry exhibited at CES 2019 - Las Vegas were listed in the text to highlight the advances in the SWD market. In the authors' opinions, very important steps forward have been made with smart jewelry
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
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