1,720,971 research outputs found
Wearable sensor (accelerometer, pressure sensing insole) gait data of older adults - Update with Prospective Falls
No full textWearable sensor (accelerometer, pressure sensing insole) gait data of older adults - Update with Prospective Fall
Wearable-sensor data with merged and separate freezing of gait episodes for freeze detection and prediction in Parkinson’s disease
No full textWearable-sensor data with merged and separate freezing of gait episodes.
Walking trials with participants with Parkinson’s disease.
Contains inertial measurement unit (IMU) and plantar-pressure based features.
Suited for freeze detection and prediction in Parkinson’s disease
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
3D optical metrology by digital moiré: Pixel-wise calibration refinement, grid removal, and temporal phase unwrapping
No full textFast, accurate three dimensional (3D) optical metrology has diverse applications in object and environment modelling. Structured-lighting techniques allow non-contacting 3D surface-shape measurement by projecting patterns of light onto an object surface, capturing images of the deformed patterns, and computing the 3D surface geometry from the captured 2D images. However, motion artifacts can still be a problem with high-speed surface-motion especially with increasing demand for higher measurement resolution and accuracy.
To avoid motion artifacts, fast 2D image acquisition of projected patterns is required. Fast multi-pattern projection and minimization of the number of projected patterns are two approaches for dynamic object measurement. To achieve a higher rate of switching frames, fast multi-pattern projection techniques require costly projector hardware modification or new designs of projection systems to increase the projection rate beyond the capabilities of off-the-shelf projectors. Even if these disadvantages were acceptable (higher cost, complex hardware), and even if the rate of acquisition achievable with current systems were fast enough to avoid errors, minimization of the number of captured frames required will still contribute to reduce further the effect of object motion on measurement accuracy and to enable capture of higher object dynamics. Development of an optical 3D metrology method that minimizes the number of projected patterns while maintaining accurate 3D surface-shape measurement of objects with continuous and discontinuous surface geometry has remained a challenge.
Capture of a single image-frame instead of multiple frames would be advantageous for measuring moving or deforming objects. Since accurate measurement generally requires multiple phase-shifted images, imbedding multiple patterns into a single projected composite pattern is one approach to achieve accurate single-frame 3D surface-shape measurement. The main limitations of existing single-frame methods based on composite patterns are poor resolution, small range of gray-level intensity due to collection of multiple patterns in one image, and degradation of the extracted patterns because of modulation and demodulation processes on the captured composite pattern image.
To benefit from the advantages of multi-pattern projection of phase-shifted fringes and single-frame techniques, without combining phase-shifted patterns into one frame, digital moiré was used. Moiré patterns are generated by projecting a grid pattern onto the object, capturing a single frame, and in a post-process, superimposing a synthetic grid of the same frequency as in the captured image. Phase-shifting is carried out as a post-process by digitally shifting the synthetic grid across the captured image. The useful moiré patterns, which contain object shape information, are contaminated with a high-frequency grid lines that must be removed. After performing grid removal, computation of a phase map, and phase-to-height mapping, 3D object shape can be computed. The advantage of digital moiré provides an opportunity to decrease the number of projected patterns. However, in previous attempts to apply digital phase-shifting moiré to perform 3D surface-shape measurement, there have been significant limitations.
To address the limitation of previous system-calibration techniques based on direct measurement of optical-setup parameters, a moiré-wavelength based phase-to-height mapping system-calibration method was developed. The moiré-wavelength refinement performs pixel-wise computation of the moiré wavelength based on the measured height (depth). In measurement of a flat plate at different depths, the range of root-mean-square (RMS) error was reduced from 0.334 to 0.828 mm using a single global wavelength across all pixels, to 0.204 to 0.261 mm using the new pixel-wise moiré-wavelength refinement.
To address the limitations of previous grid removal techniques (precise mechanical grid translation, multiple-frame capture, moiré-pattern blurring, and measurement artifacts), a new grid removal technique was developed for single-frame digital moiré using combined stationary wavelet and Fourier transforms (SWT-FFT). This approach removes high frequency grid both straight and curved lines, without moiré-pattern artifacts, blurring, and degradation, and was an improvement compared to previous techniques.
To address the limitations of the high number of projected patterns and captured images of temporal phase unwrapping (TPU) in fringe projection, and the low signal-to-noise ratio of the extended phase map of TPU in digital moiré, improved methods using two-image and three-image TPU in digital phase-shifting moiré were developed. For measurement of a pair of hemispherical objects with true radii 50.80 mm by two-image TPU digital moiré, least-squares fitted spheres to the measured 3D point clouds had errors of 0.03 mm and 0.06 mm, respectively (sphere fitting standard deviations 0.15 mm and 0.14 mm), and the centre-to-centre distance measurement between hemispheres had an error of 0.19 mm. The number of captured images required by this new method is one third that for three-wavelength heterodyne temporal phase unwrapping by fringe projection techniques, which would be advantageous in measuring dynamic objects, either moving or deforming
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
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