1,720,956 research outputs found
Numerical simulation of secondary heat exchanger S-ALLEGRO
No full textTato práce se zabývá numerickými simulacemi tepelných výměníků pro jaderné elektrárny s plynem chlazeným rychlým rektorem (zkráceně GFR). Obsahuje rešerši shrnující obecně fungování jaderných elektráren, jejich význam, historii, typy a generace jaderných reaktorů se zaměřením na GFR, a dále také popisující teorii tepelných výměníků, jejich typy a metodiku jejich návrhu. Na rešerši navazuje hlavní část práce, kterou je provedená výpočetní analýza sekundárního tepelného výměníku zařízení S-Allegro. Analýza zahrnuje výpočet kriteriálními rovnicemi, a především numerickou simulací, přičemž obě metody byly porovnány s experimentem a bylo dosaženo velmi dobré shody. Výstupem práce jsou také poznatky a doporučení ohledně výpočtů a numerických simulací tepelných výměníků pro reaktory GFR a také návrhy na možné úpravy zkoumaného tepelného výměníku zformulované na základě provedených simulací.This thesis focuses on numerical simulations of heat exchangers for nuclear power plants with gas-cooled fast reactors (GFR). It opens with a literature review summarizing the general oper ation of nuclear power plants, their significance, history, types, and generations of nuclear reactors, with a particular emphasis on GFRs. Furthermore, it describes the theory of heat exchangers, their various types, and the methodology of their design. Building on the literature review, the core part of the thesis presents a computational analysis of the secondary heat exchanger of the S-Allegro facility. The analysis includes calculations using criterial equations and, most importantly, numerical simulation. Both methods were compared to the experiment, achieving very good agreement. The outcomes of this work include insights and recommenda tions regarding the calculation and numerical simulation of heat exchangers for GFRs, as well as proposed modifications to the studied heat exchanger based on the conducted simulations
Numerical simulation of secondary heat exchanger in S-Allegro
No full textThis paper presents a computational analysis of the Secondary Heat Exchanger (SHX) in the S-Allegro experimental facility. The S-Allegro facility is a helium circuit which serves as an experimental platform for validating thermohydraulic calculations of helium flow in support of Gascooled Fast Reactor (GFR) development. A computational analysis performed on the SHX included calculations using criterial equations of heat transfer and, most importantly, numerical simulation. Both methods were compared to experimental data and adjusted to achieve a good agreement. The results of the numerical simulations are used to analyse flows in the heat exchanger and identify potential improvements in future design of heat exchangers for GFR. The study provides insights into the thermal performance of helium-water heat exchangers and contributes to the validation of computational methods for GFR technology development
Design of micromanipulator for scanning electron microscope
No full textThis thesis describes the process of design, manufacture and testing of a device for the detection of cathodoluminescent effect in scanning electron microscope. Firstly, it summarizes the basics of electron microscopy, specifically the design and manufacture of vacuum systems. It also deals with ways of using 3D printing in the prototyping of vacuum components. Then it describes the process of development of a device, which enables the user to measure cathodoluminescence in an electron microscope. The device consists of a feedthrough for optical fibre and a micromanipulator which allows the user to position the tip of the fibre to the sample. The signal from the fibre is processed in a photomultiplier for which a case is designed as a part of this thesis, or in a spectrophotometer. During the development process the device is being tested by performing some measurements and is adjusted to increase functionality and user comfort
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
Design of micromanipulator for scanning electron microscope
No full textThis thesis describes the process of design, manufacture and testing of a device for the detection of cathodoluminescent effect in scanning electron microscope. Firstly, it summarizes the basics of electron microscopy, specifically the design and manufacture of vacuum systems. It also deals with ways of using 3D printing in the prototyping of vacuum components. Then it describes the process of development of a device, which enables the user to measure cathodoluminescence in an electron microscope. The device consists of a feedthrough for optical fibre and a micromanipulator which allows the user to position the tip of the fibre to the sample. The signal from the fibre is processed in a photomultiplier for which a case is designed as a part of this thesis, or in a spectrophotometer. During the development process the device is being tested by performing some measurements and is adjusted to increase functionality and user comfort
Variations on the Author
No full text“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
No full textWe 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
No full textWe 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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