1,720,977 research outputs found
Efficiency enhancement via metal-coated porous amorphous silicon back reflectors incorporated in amorphous silicon solar cells
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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
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
Simulation of Optical Energy Deposition for Pulsed Laser-Induced Single Event Effects Testing in Microelectronic Devices
No full textPulsed laser-induced charge injection is a popular experimental technique for investigation of single event effects in microelectronic devices. Unlike traditional heavy ion testing, which is costly and limited to a relatively small number of facilities around the world, pulsed laser testing utilizes widely available measurement systems. However, while extensive first principles modeling of the interaction of heavy ions with microelectronic devices has been carried out to both understand and predict the behavior of the devices when struck by heavy ions, similar first principles modeling efforts for pulsed laser testing has not been done. In this thesis, simulation capabilities are developed to model the interaction of laser light with microelectronic devices and the subsequent electronic single event effects that occur. A commercially available optical simulation package is modified to incorporate optical processes germane to pulsed lasers, including several nonlinear effects, in order to produce accurate three-dimensional distributions of deposited energy. These distributions are then incorporated into a standard device simulation tool to capture the device response to the laser pulse. Comparison of simulated and experimental results for pulse laser testing of a large area silicon diode shows good agreement for multiple pulse energies and reverse bias conditions
Investigation of Coupling Strategies and Subwavelength Features in Photonic Crystal Cavities for Optical Modulators
No full textOptical signal processing is a crucial field for meeting our growing information needs, finding use for example in fiber optics for long-haul telecommunications. There is currently an aim to bring optical technologies closer and closer to the chip where information is processed, potentially allowing for more energy-efficient and higher-bandwidth signal processing. Photonic crystals (PhCs), engineered media that exhibit photonic band gaps, can be designed to produce resonant optical cavities, and the operation of these PhC cavities provides a versatile platform for the creation of nanoscale optical modulators to encode and decode signals with light. In this dissertation, design strategies for silicon PhC cavities are investigated in order to establish techniques for optimizing the performance and functionality of these devices within optical modulators. First, the use of a bus waveguide, side-coupled to a PhC cavity, is demonstrated to enable high-transmission, high-quality-factor resonance, giving rise to a novel PhC cavity design with uniform mirrors. In addition, a methodology is developed for combining different unit cell geometries into a single PhC cavity, which allows for non-traditional unit cell shapes with specific functionality to be included with minimal impact on quality factor, such as the “bowtie” for enhanced light-matter interaction. Following these design advances, applications of these PhC cavities are then explored for use in optical modulators. A hybrid Si-VO2 PhC cavity platform for optical modulation is designed and simulated by carefully incorporating the phase change material VO2 onto a PhC to control the wavelength and quality factor of its resonance, and thereby achieve a simulated modulation depth of 10 dB. Additionally, a bowtie PhC cavity geometry is investigated for all-optical switching, motivated by the potential of the high peak energy density of the bowtie shape to enhance nonlinear optical processes in silicon. PhCs are, therefore, envisioned as a building block for components of photonic integrated circuits, and their use in resonant cavities has applications in next-generation optical switching
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