1,720,992 research outputs found
Optical absorption and photoluminescence spectroscopy
No full textIn this chapter, we summarize the optical absorption and photoluminescence (PL) spectroscopy of metal-halide perovskite semiconductors that are substantially important to understand their behavior in optoelectronic devices and estimate their performance limits. First, we introduce the most common methods to measure the optical absorption of perovskite materials and their limitations followed by the common methods of extracting optical bandgap. Then, we discuss the near bandgap states, the process of light absorption and exciton generation in metal-halide perovskites as well as tuning the optical bandgap of them via chemical modifications. Second, we explain the PL spectroscopy of perovskites and the process involved in it alongside the main extracted parameters including diffusion lengths and carrier lifetime. We also discuss the concept of photon recycling in halide perovskite as well as the exciton binding energy and excitonic peaks in PL. Furthermore, we show effective strategies to tune and stabilize the PL in metal-halide perovskite as well as the impact of crystallinity and charge extraction layers on the PL. Finally, we show the temperature dependency of PL in metal-halide perovskites
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
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
LCL Filter Design for Single-Phase Grid-Connected PV Inverters with Double-frequency Unipolar PWM Switching
No full textThe current injected by PV inverters to the grid must contain low harmonic content within the standard limitations. However, the output voltage of inverters consists of large harmonic components at switching frequencies due to the PWM switching. Thus, an LCL filter is normally installed at the inverter output to efficiently reduce the current harmonics. Among different PWM switching schemes, double-frequency unipolar PWM has drawn little attention due to the issue of common-mode leakage current in transformerless inverters. However, this switching method offers advantages such as a lower harmonic content and higher efficiency. This paper paves the way for the implementation of double-frequency PWM switching scheme in transformerless single-phase grid-connected PV inverters by introducing a detailed description on LCL filter design. Theoretical and simulation studies on a complete PV converter are conducted in MATLAB/SIMULINK to prepare a straightforward LCL filter design procedure
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
- …
