1,720,974 research outputs found
Korkearesoluutioisen spektrometrin valosensorin päivitys valomonistinputkesta valoherkkään kennoon
No full textTämä pro gradu-tutkielma keskittyy optiseen spektroskopiaan soveltuvan mittauslaitteiston kehitykseen. Kehitystyön motivaationa on päästä mittaamaan ionilähdeplasman emissioviivoissa tapahtuvia muutoksia millisekuntiluokan aikaskaaloissa. Päivitys mahdollistaa esimerkiksi plasmassa olevien ionien lämpötilojen aikakehityksen mittaamisen emissioviivojen Doppler-levenemien avulla. Tutkielman mittauslaitteistona toimii korkearesoluutioinen spektrometri, jonka valomonistinputkivalosensori päivitetään valoherkkään kennoon osana tutkielmaa. Kehitystyön osuus koostuu sopivan valoherkän kennon valinnasta, sen asennuksesta spektrometrin valomonistinputken tilalle sekä kennon ohjausohjelmiston kehityksestä. Tämän jälkeen päivitettyä järjestelmää käytetään mikroaaltoteholla pulssitetun elektronisyklotroniresonanssi (ECR)-ionilähteen tuottaman helium ja argon plasman He II, Ar II ja Ar X-ionien emissioviivojen aikakehityksen mittaamiseen. Ionilähteen mikroaaltotehoa pulssitetaan 1 Hz taajuudella käyttäen 50% pulssisuhteista kanttiaaltoa. Lopuksi työssä kehitetään ohjelmisto mittauksissa saadun mittausdatan analysoimiseksi.
ECR-ionilähdeplasmassa kirkkaan He II-ionin 468,570 nm emissioviivan tapauksessa laitteistolla päästiin 1 ms aikaresoluutioon hyvällä signaali-kohinasuhteella. Tässä mittauksessa saatujen tulosten mukaan He II-ionin lämpötila pysyy koko mikroaaltotehopulssin ajan lähes vakiona (1,40 ± 0,09) eV lämpötilassa. Emissiointensiteetiltään pienemmät Ar II-ionin 427,753 nm ja Ar X-ionin 553,327 nm emissioviivat saatiin mitattua nopeimmillaan 60 ms aikaresoluutiolla. Näiden emissioviivojen intensiteettien mitattiin kasvavan mikroaaltotehon ollessa päällä ja vähenevän sen ollessa pois päältä. Ionipopulaatioita vastaavien lämpötilojen mitattiin nousevan mikroaaltotehon sammuessa ja laskevan sen käynnistyessä. Näiden mittaustulosten perusteella spektrometrin päivitys onnistui ja se avaa uusia mahdollisuuksia tutkia ECR-ionilähteiden tuottamaa plasmaa.This master's thesis focuses on the development of measuring equipment suitable for optical spectroscopy. The motivation of the development work is to be able to measure the changes in the optical emission line profiles of the ion source plasma in millisecond time scales. The upgrade makes it possible to measure the time evolution of the ion temperatures in the plasma by means of a Doppler broadening of the emission lines. The measuring equipment used in this thesis is a high-resolution spectrometer equipped with photomultiplier tube sensor. This sensor will be changed to an image sensor as part of the thesis. The development work consists of the selection of an suitable imaging sensor, replacing the spectrometers photomultiplier tube with the sensor and developing an image sensor control software. The upgraded equipment is used to measure the changes in He II, Ar II and Ar X-ions emission lines as a function of time, produced by microwave power pulsed electron cyclotron resonance (ECR) ion source. The microwave power of the ion source is pulsed at a frequency of 1 Hz using a 50% duty cycle square wave. Finally, a software for analysing the measurement data is developed in this work.
In the case of the bright He II-ions 468.570 nm emission line in ECRIS plasma, the equipment achieved a 1 ms time resolution with a good signal-to-noise ratio. According to the measurement results obtained, the temperature of the He II-ion remains near constant, at (1.40 ± 0.09) eV, throughout the microwave power pulse. The lines with a lower emission intensities, Ar II-ions 427.753 nm emission line and Ar X-ions 553.327 nm emission line, were measured at their fastest with a time resolution of 60 ms. The intensities of these emission lines were measured to increase when the microwave power was on and decrease when it was off. Temperatures corresponding to ion populations, on the other hand, were measured to increase as microwave power was turned off and decreased as it was turned on. Based on these measurement results, the spectrometer upgrade proved to be successful and it opens new possibilities to study the plasma produced by ECR ion sources.unknown accessibilityei tietoa saavutettavuudest
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
Mu-transposonivälitteisen protokollan optimointi ja lentivirusvektorien integraatiopaikka-analyysi
No full textVariations 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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