1,720,970 research outputs found
Sequential nonlinear manifold learning
No full textThe computation of compact and meaningful representations of high dimensional sensor data has recently been addressed through the development of Nonlinear Dimensional Reduction (NLDR) algorithms. The numerical implementation of spectral NLDR techniques typically leads to a symmetric eigenvalue problem that is solved by traditional batch eigensolution algorithms. The application of such algorithms in real-time systems necessitates the development of sequential algorithms that perform feature extraction online. This paper presents an efficient online NLDR scheme, Sequential-Isomap, based on incremental singular value decomposition (SVD) and the Isomap method. Example simulations demonstrate the validity and significant potential of this technique in real-time applications such as autonomous systems
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
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
Evaluation of solid-state gyroscope for robotics applications
No full texthe evaluation of a low-cost solid-state gyroscope
for robotics applications is described. An error model for the
sensor is generated and included in a Kalman filter for estimating
the orientation of a moving robot vehicle. Orientation eshation
with the error model is compared to the performance when the
error model is excluded from the system. The results demonstrate
that without error compensation, the error in localization is
between 5-15"/min but can be improved at least by a factor
of 5 if an adequate error model is supplied. Like all inertial
systems, the platform requires additional information from some
absolute position-sensing mechanism to overcome long-term drift.
However, the results show that with careful and detailed modeling
of error sources, inertial sensors can provide valuable orientation
information for mobile robot applications
Orientation estimate for mobile robots using gyroscopic information
No full textDate of Conference: 12-16 September 1994Conference Name: IEEE/RSJ International Conference on Intelligent Robots and Systems, IEEE 1994An error model for a solid-state gyroscope developed in previous work is included in a Kalman filter for improving the orientation estimate of a mobile robot. Orientation measurement with the error model is compared to the performance when no error model is incorporated in the system. The results demonstrate that without error compensation, the error in localization is between 5-15°/min but can be improved by a factor of 5 to 7 if an adequate error model is supplied. Results from tests of this gyroscope on a large outdoor mobile robot system are described and compared to the results obtained from the robot's own radar-based guidance system. Like all inertial systems, the platform requires additional information from some absolute position sensing mechanism to overcome long-term drift. However, the results show that with careful and detailed modelling of error sources, low cost inertial devices can provide valuable orientation and position information particularly for outdoor mobile robot applications
Inertial navigation systems for mobile robots
No full textA low-cost solid-state inertial navigation system
(INS) for mobile robotics applications is described. Error models
for the inertial sensors are generated and included in an Extended
Kalman Filter (EKF) for estimating the position and orientation
of a moving robot vehicle. Two Merent solid-state gyroscopes
have been evaluated for estimating the orientation of the robot.
Performance of the gyroscopes with error models is compared to
the performance when the error models are excluded from the
system. The results demonstrate that without error compensation,
the error in orientation is between 5-15"/min but can be improved
at least by a factor of 5 if an adequate error model is supplied.
Siar error models have been developed for each axis of a solid-state triaxial accelerometer and for a conducting-bubble tilt sensor which may also be used as a low-cost accelerometer. Linear
position estimation with information from accelerometers and tilt sensors is more susceptible to errors due to the double integration
process involved in estimating position. With the system described
here, the position drift rate is 1-8 cds, depending on the frequency
of acceleration changes. An integrated inertial platform
consisting of three gyroscopes, a triaxial accelerometer and two
tilt sensors is described. Results from tests of this platform on a large outdoor mobile robot system are described and compared to
the results obtained from the robot's own radar-based guidance
system. Like all inertial systems, the platform requires additional
information from some absolute position-sensing mechanism to
overcome long-term drift. However, the results show that with
careful and detailed modeling of error sources, low-cost inertial
sensing systems can provide valuable orientation and position
information particularly for outdoor mobile robot applications
- …
