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CAD predložak za pojedine faze proizvodnje vijaka za beton
No full textConcrete screw anchors are well-known fasteners used in industries such as construction, automotive or nuclear. Among cold forming’s different methods, the ones mainly used for producing screw anchors are extrusion and upsetting. Screws must consistently meet the given requirements and perform the way they are meant to in different environments, and that's the task for which multi-stage cold forming is a suitable choice. Multi-stage cold forming is a widely used forming process for efficient and fast mass-production of simple and complex parts with great mechanical properties. Benefits to this forming process are negligible loss of material, good dimensional control, great surface finish, improved strength, and reproducibility. However, the forming sequence must be carefully designed by highly experienced die designers, and it requires both their experienced judgment and the implementation of established design rules. The development of such sequences is being improved through the years. Since one specific screw is designed in a couple of variations, to reduce the total design time, engineers have implemented CAD templates for automatically generating the forming stages for different screw lengths. The final product’s dimensions, tools, and machine parameters are given as an input, and the template outputs the forming part’s dimensions through the stages for different screw sizes and lengths. The template for hexagonal head screw anchors had issues with replicating the part’s dimensions from the machine, i.e., the actual formed stages were not following the computer-generated ones. The initially assumed root causes for the dimension differences were that the volume distribution between the screw’s head and body are not the same for all stages. Likewise, the effects of some machine parameters, such as different ejector positions, were previously not thoroughly examined. Therefore, the main objective of this thesis is to have a better understanding of the volume distribution between the screw’s head and body through the stages, and of the forming process itself. For these reasons, an analysis of the semi-finished screw billets through the stages using precise measurements and numerical analysis is necessary. The effects of different ejector positions were observed on the measurements, and further tested in a numerical analysis tool Deform2D. The necessary adjustments to the template are finally implemented, and the modified template is tested. The modified template had smaller differences to the real parts in comparison to the initial one.Betonski sidreni vijci su dobro poznati spojni elementi korišteni u industrijama kao što su građevinska, automobilna i nuklearna. Između različitih metoda hladnog oblikovanja, one koje se najviše koriste za proizvodnju betonskih vijaka su ekstruzija i sabijanje. Vijci moraju redovito zadovoljavati različite zahtjeve koji se na njih postavljaju i to u različitim okruženjima, a da bi se to postiglo, idealan proces proizvodnje je hladno oblikovanje. Hladno oblikovanje u više faza je često korišteni proces oblikovanja za efikasnu i brzu masovnu proizvodnju jednostavnih i kompleksnih dijelova s odličnim mehaničkim svojstvima. Prednosti ovog procesa su zanemarivi gubitak materijala, dimenzijska točnost, dobra kvaliteta površine, poboljšana čvrstoća i ponovljivost. Međutim, redoslijed operacija mora biti pažljivo oblikovan od strane iskusnih konstruktora alata i zahtjeva njihovu iskustvenu procjenu, kao i implementaciju općih pravila deformiranja. Takvi redoslijedi operacija se poboljšavaju kroz godine. S obzirom da jedan vijak ima nekoliko varijacija veličine, inženjeri su implementirali CAD predloške za automatsko generiranje redoslijeda operacija za različite dužine i veličine vijaka s ciljem smanjenja ukupnog vremena procesa dizajna. Dimenzije gotovog proizvoda i parametri alata i strojeva unose se u predložak, koji onda stvara redoslijed sa svim dimenzijama kroz različite faze, za različite veličine i dužine vijaka. Jedan predložak koji generira vijke sa šesterokutnom glavom nije dobro replicirao dimenzije stvarnog proizvoda, tj. dimenzije na proizvedenim dijelovima nisu u potpunosti odgovarale dimenzijama na predlošku. Inicijalno pretpostavljeni uzroci tog problema su nejednaka distribucija volumena između glave i tijela vijka kroz faze na stvarnim uzorcima. Nadalje, efekti podešavanja nekih parametara strojeva, kao što su pozicije izbacivača, nisu prethodno bile detaljnije ispitane. S obzirom na to, glavni cilj ovog rada je formiranje boljeg razumijevanja distribucije volumena između glave i tijela vijka kroz faze, ali i samog proizvodnog procesa. Iz tih razloga, potrebna je analiza pojedinih poluproizvoda vijaka kroz proizvodne faze uz pomoć preciznih mjerenja uzoraka i numeričke analize. Efekti različitih pozicija izbacivača su prepoznati pomoću mjerenja, i dodatno ispitani uz pomoć alata za numeričku analizu Deform2D. Potrebne promjene na predlošku su u konačnici implementirane, a promijenjeni predložak je ispitan. Novi predložak je imao manje razlike između stvarnih vrijednosti i onih u predlošku u odnosu na inicijalni
Device for inspection of heat exchanger tubes
No full textU ovom je radu opisan razvoj uređaja za ispitivanje stanja cijevi izmjenjivača topline. Radi boljeg razumijevanja problema, na samom početku dan je kratki osvrt na nuklearne elektrane i njihovu važnost, kao i objašnjenje pojma nuklearne energije i njena pretvorba unutar jedne takve elektrane. S obzirom na to da je izmjenjivač topline element koji prenosi toplinu između pojedinačnih zatvorenih krugova rashladnog medija nuklearne elektrane, detaljnije je opisan način i važnost hlađenja jednog od tih krugova. Dan je i pregled različitih vrsta izmjenjivača topline, od kojih je najčešći, shell and tube, detaljnije opisan. U uvodnom dijelu opisan je i pojam nerazornih ispitivanja, njihova važnost i primjena, kao i najčešća oštećenja na cijevima izmjenjivača topline. Nakon opisa problema, započeta je faza koncipiranja uređaja gdje se analiziralo tržište u smislu pretrage patenata, postojećih uređaja, kao i pregleda postojećih uređaja tvrtke Inetec. Analiza tržišta poslužila je za definiranje tehničkih zahtjeva uređaja, koji zajedno s potrebama utvrđenima u razgovoru s inženjerima u Inetecu čine kuću kvalitete koja daje bolju sliku rasporede resursa za danji razvoj. Kreirana je funkcijska struktura uređaja i detaljno objašnjene interakcije između njegovih podsustava. Rješenja za pojedine funkcije dane su u morfološkoj matrici, nakon koje su generirani koncepti. Koncepti su evaluirani i detaljno je opisana konstrukcijska razrada pojedinih komponenti odabranog koncepta. Odabrani koncept razrađen je i modeliran u programskom paketu Autodesk Inventor 2020. U zadnjem dijelu je ispitana mogućnost unošenja i montiranja uređaja u virtualnu prostoriju izmjenjivača topline korištenjem tehnike virtualne stvarnosti.This thesis covers the development of a heat exchanger's tube inspection device. For better understanding of the problem, at the beginning of the thesis a short description of a nuclear power plant is given, along with the explanation of the term „nuclear energy“ and it's transformation inside one of such power plants. Since heat exchanger is an element which transfers heat between closed media circuits of a nuclear power plant, importance and methods of cooling such circuits are explained in detail. There is also given an overview of different types of heat exchangers, where the most common one, shell and tube is described in detail. In the introduction, the term Non Destructive Testing is also explained, along with its importance and application, together with an explanation of most common defects in heat exchanger tubes. After the problem's description, conceptualization phase has started where market research was conducted in terms of patent search, existing products analysis and Inetec's existing products analysis. Market research has been used for defining technical requirements of the device which, along with user needs defined in conversation with Inetec engineers construct house of quality which gives a better overview of resource distribution for the future product development. Functional structure of the product is made and interactions between product's subsystems are explained in detail. Solutions for partial functions are given in the morphological matrix, after which concepts were generated. Concepts were evaluated and selected concept's further development is documented and explained in detail. The selected concept is developed and modelled in Autodesk Inventor 2020 software. The possibility of installation and assembly of the device in heat exchanger's room is examined in the last part of the thesis using virtual reality technology
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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