1,720,958 research outputs found
Dispersion of silicon based micro-and nano-photonic structures and its device applications
No full textSignificant dispersion can occur in silicon micro- and nano-photonic structures, such as photonic crystals and microresonators. These dispersions may cause the phase shift and group velocity of light to be highly wavelength dependent along a fixed propagation path, or cause the propagation direction of light to be highly sensitive to the wavelength. These two types of effects are called longitudinal dispersion and angular dispersion, respectively. The slow-light effect is due to the longitudinal dispersion, and the angular dispersion is associated with the superprism effect in photonic crystals. Though, longitudinal dispersion has a less apparent influence on the superprism effect, as revealed through a more in-depth analysis. A synergistic theoretical framework of the dispersions is developed to enable a common examination of the longitudinal and angular dispersion in photonic crystal structures. These dispersive effects can lead to undesirable consequences, such as large losses and/or narrow bandwidths. For the slow-light effect, a basic proof will be shown for the scaling of random scattering losses due to fabrication imperfections in a photonic crystal waveguide. For the superprism effect, a fundamental limit, the bandwidth-sensitivity product, will be presented that governs the maximum angular sensitivities and the achievable bandwidth. This product is the counterpart of the bandwidth-delay product for the slow-light effect. A parallel-coupled dual racetrack silicon resonator structure is proposed and analyzed for arbitrary quadrature signal generation. The over-coupled, critically-coupled, and under-coupled scenarios are systematically studied. Simulations indicate that only the over-coupled structures can generate arbitrary quadrature signals. The effects of potential asymmetries in the coupling constants and quality factors of the two racetrack resonators are systematically studied. It is shown that these asymmetry effects can be compensated by small phase shifts in the two racetracks. The design, fabrication and characterization of silicon waveguides, resonator and periodic structures, including the parallel-coupled dual racetrack structure, will also be presented. The results have shown successful coupling of resonators. With the high dispersion of silicon micro- and nano-photonic structures, light can be modulated, switched, and steered with higher efficiency and lower power consumption. Thus this study may contribute to saving energy in photonic devices.Ph.D.Includes bibliographical referencesIncludes vitaby Ryan Anthony Integli
Towards A Mobile Ad-Hoc Mesh Network Establishing Emergency Drone System
No full textA drone based mobile ad-hoc mesh network for emergency communications is discussed. The in-progress project seeks to improve emergency and disaster area communication systems by creating a mobile, ad-hoc wireless network with an array of microcomputers, a GPS receiver, IMU, network adapter and drone. The Linux based platform includes network management, data collection, and integration with visualization. The expected outcome of this project is the establishment of a wireless mesh network capable of self-healing to support emergency response
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
Renewable Energy Educational Delivery System
No full textTechnology advancing rapidly and affecting our daily lives in more ways than ever before, it is clear that technology is now a driving force in our world. STEM disciplines are one of the key driving forces behind human progress, as their efforts have provided us with new levels of comfort and security. Every facet of engineering contributes to enhancing almost every aspect of our lives. As technology continues to evolve, the demand for skilled engineers will only increase. Therefore, it is essential that STEM education system adapts to the needs of today\u27s digitized, diversified, and rapidly changing society through an interdisciplinary hands-on STEM educational tool involving renewable energy, logistics, transportation and robotics technologies. The system seeks to support educators and the learning environment by providing an engaging multi student learning tool and a resource for educators to have insight into student engagement with the STEM education system
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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