1,720,963 research outputs found
Soft Bending Actuator for Body-Powered Application
No full textSoft actuators are inherently compliant, highly dexterous, and lightweight alternatives to traditional electromechanical actuators in many robotic applications, especially human-interactive robots. This research aims to develop a soft robotic actuator that leverages body movements to mimic the function of human fingers to perform gripping and grasping tasks. Unlike the predominantly used chamber-based actuation techniques, this study involves braiding fibres along the axis at two different angles on each half of the cylindrical actuator. This angle difference allows the actuator to bend in one direction when pressurized by a pneumatic or hydraulic source. Furthermore, winding the fibres continuously along the axis increases bending by limiting radial expansion.
As a first step, the bending concept based on variable stiffness has been validated using numerical and finite element analyses. Secondly, manufacturing a fibre-based soft actuator using materials of low Young’s moduli with a split fibre-reinforcement (SFR) technique was studied, followed by altering the fibre braiding pattern using the continuous fibre-reinforcement (CFR) method. The third study investigated the effect of Young's modulus on the bending and force output of the actuator. Additionally, a comparison was made between pneumatic and hydraulic-powered actuators. As a final step, the shoulder movements of the body were studied and utilized to power a set of actuators capable of performing gripping and grasping tasks. The low modulus materials and the continuous fibre winding technique allowed us to develop a portable, standalone, cost-effective body-powered prosthetic device
Flexible Piezoresistive Pressure Sensors Using Reduced Graphene Oxide
No full textThis thesis presents the development of flexible piezoresistive pressure sensor arrays based on reduced graphene oxide (rGO) film and an elastomer through a simple and convenient dip-coating method and ethanol flame treatment. One of the main goals was to achieve high-performance pressure sensor arrays with high sensitivity, wide working range, low hysteresis, fast response time, and good flexibility. For this purpose, a systematic study was conducted to evaluate the most significant parameters of the sensors’ resistance. Various electromechanical tests were also performed to study the sensor’s performance. Thermal and chemical characterizations and morphology studies were used to support the obtained result. According to the findings, the flexible piezoresistive pressure sensor arrays, based on rGO film with 1 mg/ml GO/DI water suspension, 3 mm thickness encapsulated in Ecoflex 00-30 demonstrated excellent flexibility, notable sensitivity (0.13 kPa-1 for pressure (P) <10 kPa) and 0.05 kPa-1 at 10 kPa < P < 30 kPa), a wide working range (0-30 kPa), long-term stability, the fast response time (40 ms), and low hysteresis (4.76%). The conduction mechanisms in these sensors made from rGO films were elucidated. It was deduced that the conducting mechanisms are dominated by Schottky/thermionic emission and Ohmic conduction. Furthermore, an electrical interface and software were developed and implemented to form a real-time visualization system of the sensor with a 4×4 array capable of a refresh rate of 2Hz. The system could accurately map simple objects placed on the sensor in a horizontal or vertical configuration and complicated and point loads. Considering the benefits of the developed flexible piezoresistive pressure sensors arrays, such as easy manufacturing processes, cost-effectiveness, environmental friendliness, and excellent performance, it can be stated that they can have potential applications in robotics, artificial intelligence, prosthetics, and human-machine interface
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
Highly stretchable capacitive strain sensor enhanced with Barium titanate silicone elastomer composite
No full textWearable electronics and soft robotics are emerging fields using soft and stretchable sensors for a variety of wearable applications. In this research, the performance of highly stretchable interdigitated capacitive (IDC) strain sensor was investigated, by fabricating sandwiched printed carbon black/Ecoflex interdigitated capacitive electrodes between stretchable Barium titanate (BTO)-silicone elastomer composite substrates. The different sizes of the BTO's nanoparticles like 100 nm or 200 nm BTO ceramic particles was dispersed uniformly in an Ecoflex™ 00-30, a silicone-based elastomer. The substrate of an IDC sensor with 100 nm particle size offers a higher relative permittivity and slightly higher change in capacitance with strain. It is demonstrated to be less reliable than an IDC sensor substrate made with 200 nm BTO nanoparticles. In this research, the influence of viscoelastic behaviour like stress relaxation, creep and strain rate dependent behaviour of BTO-Ecoflex composite substrate on the output signal of an IDC strain sensor was studied. The generalized Maxwell‐Wiechert (GMW) model was used to study the stress relaxation behaviour of BTO Ecoflex composite by varying the particle loading by 0, 10, 20, 30, and 40 wt% of 200 nm BTO ceramic particles embedded in an Ecoflex silicone‐based hyperelastic elastomer. Analysing the results shows that a pristine Ecoflex silicone elastomer is predominantly a hyperelastic material; the addition of BTO made the composite behave as a visco‐hyperelastic material. However, this stress relaxation behaviour of BTO-Ecoflex composite substrate was shown to have a negligible effect on the electrical sensing performance of the IDC large strain sensor, because the spacing between the interdigitated capacitive electrodes remains to be constant at a constant strain during the stress relaxation tests. The generalized Kelvin-Voigt (GKV) model was used to study the creep behaviour of the sensor’s substrate material, fabricated using silicone elastomer (Ecoflex 00-30) with barium titanate (200 nm BTO) filler. The results showed that the pristine Ecoflex silicone elastomer is predominately a hyperelastic material, which shows negligible creep, while the addition of BTO particles led to the composite exhibiting creep such
that the composite behaves like a visco-hyperelastic material. Hence, this behaviour results in the creep affecting the electrical sensing performance of the capacitive strain sensors during static loading conditions, because the spacing between the interdigitated capacitive electrodes increases with increasing strain at constant load during creep tests. The creep tests’ information provides insights on the impact of composite composition on creep-resistance and output signal of the IDC strain sensor (capacitance). The non-linear elastic strain rate dependent behaviour of BTO-Ecoflex composite is studied by using Ogden model. The uniaxial tensile tests at strain rates of 5, 50, and 500 mm/min show a decrease in non-linearity of the stress-strain response of the composite, with an increase in filler loading; also, there is no strain rate effect on the performance of the IDC sensor fabricated with 40 wt% 200 nm BTO-Ecoflex composite substrate. The distribution and sedimentation of the BTO filler in Ecoflex is studied by performing scanning electronic microscopy (SEM) analysis on the cryo-fractured pristine Ecoflex and 10, 20 30 and 40 wt% of BTO-Ecoflex composites, where it was found that, due to the surplus BTO filler in the polymer, the distribution of the filler is more homogeneous in the Ecoflex polymer at higher filler loading levels like 40 wt% 200 nm BTO.
The screen-printing technique was also successfully used to demonstrate the possibility of mass production of an IDC strain sensors, with 40 wt% 200 nm BTO-Ecoflex composite for large scale industrial production.
An IDC sensor was therefore fabricated based on a 40 wt% 200 nm BTO-Ecoflex composite and mounted on an elastic elbow sleeve and equipped with electronics, and successfully functioned as a reliable and robust flexible sensor. This demonstrated an application to measure the bending angle of the elbow at slow and fast movement of hand. A linear relationship with respect to the elbow bending angle was observed between the IDC sensor output signal under 50% strain and the bending of the elbow of hand indicating its potential as a stretchable, flexible and wearable sensor
Variations on the Author
No full text“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
No full textWe 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
No full textWe 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
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