1,720,972 research outputs found
Sub-wavelength coatings on metals by ALD
No full textThe equations that describe reflection and transmission of electromagnetic field on various interfaces of transparent materials can be found from almost any textbook on optics.
A lot less known problems are related to the behavior of e.m. field on such interfaces where one part is a dielectric material and the other one metal layer.
In such cases one can for example modify the colour of the metal in the reflected visible light by varying the film thickness.
In most common cases the metal surface is being oxidized either spontaneously or by a controlled treatment.
Then the visible light normally becomes transmitted through the oxide layer and may experience a number of internal reflections between the metal/oxide and the oxide/air boundaries leading to scattering and absorption losses and to a large phase change.
In this thesis the main focus has been to calculate and experimentally test the effect of an oxide layer on the reflected light by taking into account higher order reflection events in the analysis One motivation was to test the applicability of the atomic layer deposition method for modifying the optical response of metal surfaces by highly controllable sub-wavelength metal oxide coatings.
The atomic layer deposition (ALD) has become a prominent technique for conformal deposition of thin films.
By using ALD one can get pinhole free films of almost perfectly uniform thickness in this work ALD was used to deposit optical oxide coatings with the main emphasis on very thin sub-wavelength thick films on metals.
One application of optical coatings that was tested in this work is an optical polarizer.
The idea is to reduce one polarization component of light as effectively as possible.
In order to find the behavior of the two polarization components of the light field in thin optical coatings the physical system was simulated using Matlab.
In the experimental part of the work, a polarizing component was fabricated by using ALD to make a 229 nm thick A1203 film it was also experimentally tested by measuring reflected light using the monochromatic (635 nm laser) source in a setup that included a goniometer Rather satisfactory agreement between the experimental reflectance curve and the simulated data was found
Towards metal free counter electrodes for dye-sensitized solar cells
Get PDFThis thesis provides a technical overview of results from addressing the critical steps in preparing counter electrodes for dye-sensitized solar cells (DSC) on flexible substrates (mainly plastics) to pave the way towards low-cost DSCs. The aim was to develop low-temperature counter electrode inks and pastes that could be suitable for high volume manufacturing processes. A special focus was given on the mechanical stability (flexibility and adhesion) of the materials that were deposited through a low-temperature route.
Different low temperature inks and pastes based on carbon composites were tested as a replacement to expensive platinum nanoparticles based catalyst layer and showed good mechanical stability, comparable photovoltaic performance and low charge transfer resistance in complete dye-sensitized solar cells.
Indium doped tin oxide (ITO) layer that is normally used as a conductor on plastic substrates was successfully replaced with a single walled carbon nanotube (SWCNT) film deposited as a low-temperature curable ink on polyvinyl chloride (PVC) substrate. The SWCNT films exhibited remarkably good mechanical stability when subjected to bending and tape adhesion tests. Coating the film with a thin layer of conducting polymer poly (3, 4-ethylenedioxythiophene (PEDOT) increased its catalytic performance comparable to a reference platinum counter electrode.
Relevant to scaling up DSC preparation, a two way electrolyte filling method was studied as a means to suppress performance losses that occur due to non-homogenous distribution of electrolyte components. The method enhanced the photovoltaic performance of a segmented measurement cell by up to 42% compared to traditional one way filling of the electrolyte.
The aforementioned results provide pathways for the future development of robust flexible counter electrodes that can be beneficial especially from the perspective of high throughput roll-to-roll processing of flexible DSCs on polymer substrates
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
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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