31,067 research outputs found

    Application of Time-Fractional Order Bloch Equation in Magnetic Resonance Fingerprinting

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    Magnetic resonance fingerprinting (MRF) is one novel fast quantitative imaging framework for simultaneous quantification of multiple parameters with pseudo-randomized acquisition patterns. The accuracy of the resulting multi-parameters is very important for clinical applications. In this paper, we derived signal evolutions from the anomalous relaxation using a fractional calculus. More specifically, we utilized time-fractional order extension of the Bloch equations to generate dictionary to provide more complex system descriptions for MRF applications. The representative results of phantom experiments demonstrated the good accuracy performance when applying the time-fractional order Bloch equations to generate dictionary entries in the MRF framework. The utility of the proposed method is also validated by in-vivo study.Comment: Accepted at 2019 IEEE 16th International Symposium on Biomedical Imaging (ISBI 2019

    Aerospace medicine and biology: A continuing bibliography with indexes (supplement 352)

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    This bibliography lists 147 reports, articles and other documents introduced into the NASA Scientific and Technical Information System during July 1991. Subject coverage includes: aerospace medicine and psychology, life support systems and controlled environments, safety equipment, exobiology and extraterrestrial life, and flight crew behavior and performance

    Orbital angular momentum 25 years on [invited]

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    Twenty-five years ago Allen, Beijersbergen, Spreeuw, and Woerdman published their seminal paper establishing that light beams with helical phase-fronts carried an orbital angular momentum. Previously orbital angular momentum had been associated only with high-order atomic/molecular transitions and hence considered to be a rare occurrence. The realization that every photon in a laser beam could carry an orbital angular momentum that was in excess of the angular momentum associated with photon spin has led both to new understandings of optical effects and various applications. These applications range from optical manipulation, imaging and quantum optics, to optical communications. This brief review will examine some of the research in the field to date and consider what future directions might hold

    Using ICT tools to manage knowledge: a student perspective in determining the quality of education

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    Within the e-learning context of a university, technology has the potential to facilitate the knowledge interaction between the source (instructor) and the recipient (students). From a literature review, it can be concluded that prior studies have not explored the types of channels that encourage knowledge transfer in this environment. For example, how explicit knowledge travels through the e-learning environment and goes through interaction processes and is received and acquired is largely unknown. According to Alavi & Leidner (2001), Information and Communication Technology (ICT) can help speed up the processes of transferring knowledge from those who have knowledge to those seeking knowledge. Within the university context, technologies such as email, Internet, IRC chat, bulletin boards and tools such as WebCT and BlackBoard have the potential to facilitate the transfer of knowledge and act as a link between source and recipient. Effective knowledge transfer has to consider effective knowledge acquisition, which are therefore inexplicably linked. Nonaka's spiral model addresses knowledge acquisition through spiraling processes in which an individual would be able to convert tacit knowledge to explicit knowledge and vice versa. According to Nonaka & Takeuchi (1995) there are four types of interaction, which give way to the conversion of one form of knowledge into another, namely tacit-to-tacit, tacit-to-explicit, explicit-to-tacit and explicit-to-explicit. In an academic environment, this can be studied as the source, either transferring tacit or explicit knowledge, and similarly as the recipient, receiving knowledge either in tacit or explicit form. Nonaka & Takeuchi (1995) also refer to this as the SECI model, where SECI stands for Socialisation, Externalisation, Combination and Internalisation. This 'Research in Progress' reports the outcomes of a study undertaken to understand how and to what extent knowledge spiraling processes and accompanying characteristics of SECI can be ICT-enabled to contribute towards the studying and learning processes for university education. A survey instrument was developed for this purpose and it is currently undergoing peer-review and other customary validity and reliability tests. Once the instrument is validated, it will be administered on about 50 tertiary students. It is hoped that the results obtained from this survey will be reported in the QIK 2005 conference

    Space exploration: The interstellar goal and Titan demonstration

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    Automated interstellar space exploration is reviewed. The Titan demonstration mission is discussed. Remote sensing and automated modeling are considered. Nuclear electric propulsion, main orbiting spacecraft, lander/rover, subsatellites, atmospheric probes, powered air vehicles, and a surface science network comprise mission component concepts. Machine, intelligence in space exploration is discussed

    Autonomous Systems, Robotics, and Computing Systems Capability Roadmap: NRC Dialogue

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    Contents include the following: Introduction. Process, Mission Drivers, Deliverables, and Interfaces. Autonomy. Crew-Centered and Remote Operations. Integrated Systems Health Management. Autonomous Vehicle Control. Autonomous Process Control. Robotics. Robotics for Solar System Exploration. Robotics for Lunar and Planetary Habitation. Robotics for In-Space Operations. Computing Systems. Conclusion

    Design and Control of a Hand Prosthesis

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    Práce předkládá metody a výsledky návrhu, výroby a výzkumu pětiprsté protézy ruky. Inspirace jdoucí z přírody a z toho vyvozený princip použitého mechanizmu je uveden. Základní koncept řídícího schéma založeného na procesingu a ohodnocení EMG je navrhnut a implementován. Části senzorického systému protézy jsou navrhnuty a zahrnuty do rídícího algoritmu a shématu. Velké množství inovací a návrhů pro budoucí práce a výzkum jsou prezentovány, stejně tak komplexní analýza a diskuse dosažených a možných budoucích výsledků.The text shows idea flow, methods and results in design, manufacture and research of five--fingered prosthetic hand. The inspiration of the nature and mechanical principle elicited is presented. Fundamental control scheme based on processing and evaluation of EMG is designed and implemented. The segments of sensory system are designed and involved into the overall controll scheme idea. Large innovations and suggestions for future work and research are given with complex discussion through reached and hopefully future results.
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