1,720,969 research outputs found
Speed Measurement of Projectile Using Vision System and Least Square Regression with Different Amplitude Sliding Window
No full textThis paper presents a case study in which vision system is used to measure the speed of a projectile approximately 1 m long and weighing 20 kg. The projectile, ejected by a canister, is expected to reach a speed between 20 and 60 m/s. A vision system-based method using colored stripes on the projectile’s tip and tail was employed. By tracking the advancement of the stripes along the fire axis it was possible to compute the speed at the canister’s exit using a linear regression model. To improve measurement accuracy, sliding windows and sensor fusion techniques were used
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
Calibration to Differentiate Power Output by the Manual Wheelchair User from the Pushrim-Activated Power-Assisted Wheel on a Force-Instrumented Computer-Controlled Wheelchair Ergometer
Full text linkTo examine the biomechanical demands of manual wheelchair propulsion, it is crucial to determine the wheelchair user’s (WCU) force for propulsion technique parameter calculation. When using a pushrim-activated power-assisted wheelchair (PAPAW) on a wheelchair ergometer, a combined propulsion force from the WCU and PAPAW is exerted. To understand PAPAW’s assistance and distinguish the WCU’s force application from the force exerted by the PAPAW, both propulsion components must be assessed separately. In this study, a calibration of the PAPAW on an ergometer was developed to achieve this separation. The calibration consists of five steps: (I) Collecting data on force and velocity measured from the ergometer, along with electrical current and velocity from the PAPAW. (II) Synchronizing the velocity signals of the wheelchair ergometer and PAPAW using cross-correlation. (III) Calibrating the PAPAW’s electromotors to convert electrical current (mA) to force (N). A product-specific motor constant of 0.30, provided an average ICC of 0.563, indicating a moderate agreement between the raw ergometer data (N) and the motor constant-converted drive-rim (PAPAW) data (from mA to N). (IV) Subtracting the PAPAW’s force signal from the ergometer’s measured force to isolate forces generated by the WCU. (V) Using markerless motion capture to determine and validate the phase of hand contact with the handrim. This technical note provides an example of PAPAW calibration for researchers and clinicians. It emphasizes the importance of integrating this calibration into the development of PAPAW devices to reveal the complex interaction between PAPAW and WCU during wheelchair propulsion
Impacts of Racket Handle Design on Table Tennis Topspin Forehand Rally Performance Among Beginner Players
Full text linkPhysical inactivity is a major global public health concern, and table tennis offers a low-impact, engaging way to promote physical activity across various age groups. However, many beginners struggle to maintain effective participation due to their lower skill levels. Therefore, the development and reinforcement of stable grip techniques is crucial because it will help beginners achieve sustainable improvements in performance. This will provide additional opportunities to increase physical activity, and therefore overall health, across all age groups. Thus, in this study, we investigate the effects of a prototype table tennis handle on the racket angle and performance of beginners. The prototype handle features a 20° tilt to assist the player in maintaining a stable topspin forehand grip during play. The participants were randomized into three groups, Groups A, B, and C, which used the prototype handle, standard handle, and practiced with the prototype but performed tests with the standard handle, respectively. The participants executed topspin forehand strokes in approximately 30 min of practice, and data on racket angles, swing mechanics, success rates, and ball landing positions were collected. The results showed that Group A exhibited a larger racket open angle and a smaller racket face Angle than the other groups. However, the groups showed no significant differences in hit positions or overall success rates. Our results suggest that although the prototype handle can influence racket angles and some performance aspects, individual differences and swing mechanics should be considered
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
Validation of Partial Weight-Bearing estimator using instrumented crutches
No full textIncremental weight-bearing is common during post-surgery gait rehabilitation minimize implant
failures and enhance healing of the soft tissue. The Partial Weight-Bearing (PWB) method involves
gradually increasing the weight load on the limb over time, a process that is tailored to each patient
based on the severity of their injury and the clinician's discretion
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