1,720,963 research outputs found
All optical switching in ultrashort photonic crystal couplers
No full textWe demonstrate the possibility of performing all optical switching in ultrashort photonic crystal couplers. The proposed structure exploits the AlGaAs Kerr nonlinearity to obtain an ultracompact power-controlled switch
Fiber Bragg Gratings embedded inside 3D-printed Patches - sensor design and mechanical characterization
No full textThe application of optical fibers with fiber Bragg gratings (FBG) in the civil, biomedical and robotics fields presents several challenges related to the positioning and gluing of the sensor to the surface to be monitored. For this reason, the development of 3D-printed patches that embed optical fibers has become relevant in recent years. The studies existing in the literature focus on some specific process parameters, like the infill density and the choice of the material of the patch. However, a systematic analysis regarding the interaction between the material of the patch material and the embedded fiber coating to secure adhesion and strain transfer is still missing. This preliminary study aims at assessing the performances of 3D-printed patches embedding optical fibers in different combinations of filament materials and coatings of the fiber. Two sensors per combination of filament material (ABS, PLA) and coating of the fiber (acrylate, polyimide) are fabricated and mechanically tested. The results indicate that the fabrication process is more reliable when using polyimide-coated fibers, and the measurements of the resulting sensors are more repeatable
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
PID controlling approach based on FBG array measurements for laser ablation of pancreatic tissues
Full text linkIn this paper, we propose a temperature-based proportional–integral–derivative (PID) controlling algorithm using highly dense fiber Bragg grating (FBG) arrays for laser ablation (LA) of ex vivo pancreatic tissues. Custom-made highly dense FBG arrays with a spatial resolution of 1.2 mm were fabricated with the femtosecond point-by-point writing technology and optimized for LA applications. In order to obtain proper PID gain values, finite element method-based iterative simulation of different PID gains was performed. Then, the proposed algorithm, with numerically derived PID gains, was experimentally validated. In the experiments, the point temperature was controlled at different distances from the laser fiber tip (6.0 mm, 7.2 mm, 8.4 mm, and 10.8 mm). The obtained results report robust controlling and correlation between controlled distance and the resulting area of ablation. The results of the work encourage further investigation of FBG array application for LA control
Analysis on the plié and grand plié in classical ballet with magneto-inertial measurement units
No full textBallet dancers look for the perfection of movements not only for the elegance of the performance, but, above all, to prevent from injuries. The plié and the grand plié are movements of paramount importance in ballet dancing and they are extensively performed by beginners. An improper exercise execution can eventually lead to severe injuries. Thus, the design of a wearable system able to provide a quantitative estimation of the movement quality can help determining and correcting the different types of mistakes. At the same time, the system must be easy to use and must not hinder the movements of the dancer. In this work, we propose a system based on magneto-inertial measurement units (MIMU) that measures the orientation of the dancer femur and shinbone, during the plié and the grand plié performed by a professional ballet dancer. The dancer was asked to perform the two classical positions in a series of correct and incorrect executions. When the plié is performed incorrectly, the average femur inclination angle increases from 36.3±0.7° to 39.7±1.4° and the average femur direction angle decreases from 94.5±4.0° to 70.5±3.4°. When the grand plié is performed incorrectly, the average femur inclination angle increases from 67.2±0.5° to 79.0±3.0°, the average femur direction angle increases from 39.0±2.3° to 51.6±6.3° and the average shinbone direction angle increases from 116.3±2.6° to 142.8±4.0°. These results show that the proposed wearable system is able to identify and estimate the improper execution of the tasks, without hindering or alterating the movement of the dancer
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
Validation and assessment of a posture measurement system with magneto-inertial measurement units
Full text linkInappropriate posture and the presence of spinal disorders require specific monitoring systems. In clinical settings, posture evaluation is commonly performed with visual observation, electrogoniometers or motion capture systems (MoCaps). Developing a measurement system that can be easily used also in non-structured environments would be highly beneficial for accurate posture monitoring. This work proposes a system based on three magneto-inertial measurement units (MIMU), placed on the backs of seventeen volunteers on the T3, T12 and S1 vertebrae. The reference system used for validation is a stereophotogrammetric motion capture system. The volunteers performed forward bending and sit-to-stand tests. The measured variables for identifying the posture were the kyphosis and the lordosis angles, as well as the range of movement (ROM) of the body segments. The comparison between MIMU and MoCap provided a maximum RMSE of 5.6° for the kyphosis and the lordosis angles. The average lumbo-pelvic contribution during forward bending (41.8 ± 8.6%) and the average lumbar ROM during sit-to-stand (31.8 ± 9.8° for sitting down, 29.6 ± 7.6° for standing up) obtained with the MIMU system agree with the literature. In conclusion, the MIMU system, which is wearable, inexpensive and easy to set up in non-structured environments, has been demonstrated to be effective in posture evaluation
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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