1,720,962 research outputs found
Theoretical study of direct and indirect single ionisation by electron impact.
No full textThe dissertation analyses the processes of single ionisation with electron impact using the distorted wave approximation. The work focuses on W5+, W25+, W26+, Fe3+ and Se3+ ions. The atomic data of these ions are important and have practical application perspectives for understanding and controlling astrophysical processes and thermonuclear plasma dynamics. The direct and indirect ionisation processes of ions are analysed, and the cross sections of the ionisation effect are determined. The correlation effects of Fe3+ and W5+ ions were also investigated and the experimental data of these ions and Se3+ ion were explained for the first time. The introduction discusses the importance of plasma studies and the need to investigate ionisation in iron, selenium, and tungsten. The work aims to investigate the processes of single ionisation by electron impact using the distorted wave method and to propose more accurate methods. The main theory is discussed in the theoretical chapter: electron impact ionization, wave functions, radiation and Auger transitions, resonant excitation-double autoionisation process, distorted wave approximation, cross section scaling coefficient, correlation effects, modelling of metastable states. The dissertation concludes with the main conclusions that are related to the defended statements. The dissertation is prepared in English, its volume is 103 pages. The dissertation consists of content, the list of author's publications and conference papers, the list of abbreviations used in the dissertation, introduction, theory overview, the results section, conclusions, and the list of used literature with 98 sources. The dissertation contains 33 illustrations, 5 tables and 1 appendix
Tiesioginės ir netiesioginės viengubos jonizacijos elektronų smūgiais tyrimas.
No full textThe dissertation analyses the processes of single ionisation with electron impact using the distorted wave approximation. The work focuses on W5+, W25+, W26+, Fe3+ and Se3+ ions. The atomic data of these ions are important and have practical application perspectives for understanding and controlling astrophysical processes and thermonuclear plasma dynamics. The direct and indirect ionisation processes of ions are analysed, and the cross sections of the ionisation effect are determined. The correlation effects of Fe3+ and W5+ ions were also investigated and the experimental data of these ions and Se3+ ion were explained for the first time. The introduction discusses the importance of plasma studies and the need to investigate ionisation in iron, selenium, and tungsten. The work aims to investigate the processes of single ionisation by electron impact using the distorted wave method and to propose more accurate methods. The main theory is discussed in the theoretical chapter: electron impact ionization, wave functions, radiation and Auger transitions, resonant excitation-double autoionisation process, distorted wave approximation, cross section scaling coefficient, correlation effects, modelling of metastable states. The dissertation concludes with the main conclusions that are related to the defended statements. The dissertation is prepared in English, its volume is 103 pages. The dissertation consists of content, the list of author's publications and conference papers, the list of abbreviations used in the dissertation, introduction, theory overview, the results section, conclusions, and the list of used literature with 98 sources. The dissertation contains 33 illustrations, 5 tables and 1 appendix
Research of characteristics of a phase change material based thermal energy storage unit
No full textDisertacijoje taikant analitinį modelį, skaitinį modeliavimą ir eksperimentinius tyrimus tiriamas fazinio virsmo medžiagos pagrindu veikiantis šilumos kaupimo
įrenginys.
Darbe sprendžiami keli pagrindiniai uždaviniai, susiję su fazinio virsmo medžiagų termofizikinių savybių, šilumokaičio geometrijos ir šilumnešio parametrų įtaka fazinio virsmo medžiagos (FVM) pagrindu veikiančio šilumos kaupimo renginio veikimo charakteristikoms.
Disertaciją sudaro įvadas, trys skyriai, bendrosios išvados, naudotos literatūros ir autoriaus publikacijų disertacijos tema sąrašai ir du priedai.
Įvadiniame skyriuje aptariama tiriamoji problema, darbo aktualumas, aprašomas tyrimų objektas, formuluojamas darbo tikslas bei uždaviniai, aprašoma tyrimų metodika, darbo mokslinis naujumas, darbo rezultatų praktinė reikšmė, ginamieji teiginiai. Įvado pabaigoje pristatomos disertacijos tema autoriaus paskelbtos publikacijos ir pranešimai konferencijose bei disertacijos struktūra.
Pirmasis skyrius skirtas literatūros analizei. Skyriaus pabaigoje formuluojamos išvados ir tikslinami disertacijos uždaviniai.
Antrajame skyriuje pateikta FVM pagrindu veikiančio šilumos kaupimo
įrenginio tyrimų metodika, kurios pagrindu atliekamas kompleksinis tyrimas,
apimantis skaitinį modeliavimą, analitinių išraiškų taikymą ir eksperimentus.
Trečiajame skyriuje pateikti FVM pagrindu veikiančio šilumos kaupimo
įrenginio tyrimų rezultatai. Analizuojami skaitinio modeliavimo rezultatai, nagrinėjant temperatūros pasiskirstymą ir fazės virsmo trukmę pasirinktuose FVM šilumos kaupimo įrenginio taškuose ir plokštumoje. Atliekamas šilumos atidavimo koeficiento nustatymas taikant analitines išraiškas, gauti rezultatai lyginami su eksperimentiniais. Aprašomi ir analizuojami eksperimentinių tyrimų, apimančių FVM tankio kitimo, šilumokaičio geometrijos, šilumnešio masinio debito ir temperatūros įtaką įrenginio veikimo charakteristikoms, rezultatai.Daktaro disertacij
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
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