El rock and roll : un producto con aura

Comunicador (a) SocialPregrad

Information-theoretic environment modeling for mobile robot localization

To enhance robotic computational efficiency without degenerating accuracy, it is imperative to fit the right and exact amount of information in its simplest form to the investigated task. This thesis conforms to this reasoning in environment model building and robot localization. It puts forth an approach towards building maps and localizing a mobile robot efficiently with respect to unknown, unstructured and moderately dynamic environments. For this, the environment is modeled on an information-theoretic basis, more specifically in terms of its transmission property. Subsequently, the presented environment model, which does not specifically adhere to classical geometric modeling, succeeds in solving the environment disambiguation effectively. The proposed solution lays out a two-level hierarchical structure for localization. The structure makes use of extracted features, which are stored in two different resolutions in a single hybrid feature-map. This enables dual coarse-topological and fine-geometric localization modalities. The first level in the hierarchy describes the environment topologically, where a defined set of places is described by a probabilistic feature representation. A conditional entropy-based criterion is proposed to quantify the transinformation between the feature and the place domains. This criterion provides a double benefit of pruning the large dimensional feature space, and at the same time selecting the best discriminative features that overcome environment aliasing problems. Features with the highest transinformation are filtered and compressed to form a coarse resolution feature-map (codebook). Localization at this level is conducted through place matching. In the second level of the hierarchy, the map is viewed in high-resolution, as consisting of non-compressed entropy-processed features. These features are additionally tagged with their position information. Given the identified topological place provided by the first level, fine localization corresponding to the second level is executed using feature triangulation. To enhance the triangulation accuracy, redundant features are used and two metric evaluating criteria are employ-ed; one for dynamic features and mismatches detection, and another for feature selection. The proposed approach and methods have been tested in realistic indoor environments using a vision sensor and the Scale Invariant Feature Transform local feature extraction. Through experiments, it is demonstrated that an information-theoretic modeling approach is highly efficient in attaining combined accuracy and computational efficiency performances for localization. It has also been proven that the approach is capable of modeling environments with a high degree of unstructuredness, perceptual aliasing, and dynamic variations (illumination conditions; scene dynamics). The merit of employing this modeling type is that environment features are evaluated quantitatively, while at the same time qualitative conclusions are generated about feature selection and performance in a robot localization task. In this way, the accuracy of localization can be adapted in accordance with the available resources. The experimental results also show that the hybrid topological-metric map provides sufficient information to localize a mobile robot on two scales, independent of the robot motion model. The codebook exhibits fast and accurate topological localization at significant compression ratios. The hierarchical localization framework demonstrates robustness and optimized space and time complexities. This, in turn, provides scalability to large environments application and real-time employment adequacies

Beautiful, Self‐Absorbed, and Shallow: People of Color Perceive W hite Women as an Ethnically Marked Category

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/96379/1/jasp980.pd

Which countries does the world talk about? An examination of factors that shape country presence on Twitter

This study investigates which countries were mentioned most on Twitter during 2013 and what factors—country attributes, communication and economic resources, and contexts—can explain country presence on Twitter. Tweet mentions from 210 countries were derived using full fire hose archival searches. We identify trends that differ from the patterns found in news flow literature. And the results suggest a new era of international communication via Web-based social networks. Although core and semiperiphery countries are mentioned more than periphery countries, mobile phone penetration and sociopolitical instability have reshaped the contours of country images, and only 28% of the 50 most-mentioned countries on Twitter were core countries. This study discusses the implications of evolving social media for traditional news media outlets, world politics, and international relations.https://ijoc.org/index.php/ijoc/article/view/5002Published versio

sj-sav-4-ips-10.1177_01925121241228556 – Supplemental material for Does world system theory rein in social media? Identifying factors contributing to country mentions on X

Supplemental material, sj-sav-4-ips-10.1177_01925121241228556 for Does world system theory rein in social media? Identifying factors contributing to country mentions on X by Michael G Elasmar, H Denis Wu and Jacob Groshek in International Political Science Review</p

sj-docx-2-ips-10.1177_01925121241228556 – Supplemental material for Does world system theory rein in social media? Identifying factors contributing to country mentions on X

Supplemental material, sj-docx-2-ips-10.1177_01925121241228556 for Does world system theory rein in social media? Identifying factors contributing to country mentions on X by Michael G Elasmar, H Denis Wu and Jacob Groshek in International Political Science Review</p

sj-docx-1-ips-10.1177_01925121241228556 – Supplemental material for Does world system theory rein in social media? Identifying factors contributing to country mentions on X

Supplemental material, sj-docx-1-ips-10.1177_01925121241228556 for Does world system theory rein in social media? Identifying factors contributing to country mentions on X by Michael G Elasmar, H Denis Wu and Jacob Groshek in International Political Science Review</p

sj-sav-3-ips-10.1177_01925121241228556 – Supplemental material for Does world system theory rein in social media? Identifying factors contributing to country mentions on X

Supplemental material, sj-sav-3-ips-10.1177_01925121241228556 for Does world system theory rein in social media? Identifying factors contributing to country mentions on X by Michael G Elasmar, H Denis Wu and Jacob Groshek in International Political Science Review</p

Interindustry and Intraindustry Competition in Satellite Broadcasting: A Comparative Case Study on the United States, Japan, England, and France

This study explores the role of intra- and interindustry competition in the evolution of satellite broadcasting with case studies on the United States, Japan, England, and France. The case studies revealed that different patterns of inter- and intraindustry competition play a critical role in the business strategies of satellite broadcasters and their expansion in terms of subscription and market share. The findings of this research suggest that a policy framework that guarantees an adequate level of competition among content delivery technologies is required.