441 research outputs found
Bestimmung von freiem Melamin entlang der Wertschöpfungskette
No full textAuthor DI Anna Christina Pfeifer, BSc.Abweichender Titel laut Übersetzung der Verfasserin/des VerfassersDissertation Johannes Kepler Universität Linz 2025Arbeit nach Ablauf der Sperre auf den öffentlichen PCs in den Bibliotheken der JKU+Medizin abrufba
Bestimmung von freiem Melamin entlang der Wertschöpfungskette
No full textAuthor DI Anna Christina Pfeifer, BSc.Abweichender Titel laut Übersetzung der Verfasserin/des VerfassersDissertation Johannes Kepler Universität Linz 2025Arbeit nach Ablauf der Sperre auf den öffentlichen PCs in den Bibliotheken der JKU+Medizin abrufba
A atitude holística do trabalhador no ambiente de trabalho e sua qualidade de vida
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Engenharia de Produção.Este trabalho teve como objetivo compreender a repercussão da atitude holística, desenvolvida pelo trabalhador no ambiente de trabalho, na sua qualidade de vida. Participaram dessa pesquisa sete trabalhadores residentes em Florianópolis, capital do estado de Santa Catarina. A pesquisa foi desenvolvida com a abordagem qualitativa permitindo a flexibilidade, a abertura e a profundidade requeridas para o tema po
Surdez e preconceito: os desafios enfrentados pela comunidade surda em Crônicas da Surdez, de Paula Pfeifer
No full textO presente trabalho tem como objetivo perceber a presença de preconceito em relação ao
sujeito Surdo durante sua inserção no meio social. Para tanto, foi necessário trilhar um
caminho de pesquisa que trouxesse alguém que, de fato, tivesse vivido essa experiência. A
vivência do preconceito em relação à surdez é encontrada nos retratos realizados pelo livro
de Paula Pfeifer, Crônicas da Surdez, publicado em 2013. No primeiro capítulo, são
abordadas as concepções de cada tema em questão e o que se pretende ao analisar a obra
referida. Na segunda parte, apresenta-se a crônica como gênero literário, pois foi o gênero
escolhido pela autora para trazer sua biografia e relatar suas experiências. Por isso, buscou-se
compreendê-lo melhor, como funciona sua estrutura e suas características, para assim
entender o porquê a autora fez essa escolha. Logo mais, fez-se a apresentação do livro de
Paula Pfeifer, que é a autora, um pouco sobre sua vida e do porquê ela foi escolhida para
representar a temática. Por último, realiza-se uma análise das crônicas em questão, na qual
constam as relações que elas apresentam com a pesquisa.The present work aims to perceive the presence of prejudice in relation to the deaf subjects
during their insertion in the social environment. Therefore, it was necessary to carry out
research and readings that would bring someone who had actually lived this experience. The
experience of prejudice in relation to deafness is found in the portraits made by Paula
Pfeifer's book, Crônicas da Surdez, published in 2013. In the first chapter, the conceptions of
each theme and what is intended when analyzing the work are addressed. In the second part,
the crônica is presented as a literary genre, as it was the genre chosen by the author to bring
her biography and report her experiences. Therefore, we sought to understand it better, how
its structure and characteristics work, in order to understand why the author made this
choice. Thenceforth, the book by Paula Pfeifer was presented, who the author is, a little
about her life and why she was chosen to represent the theme. Finally, an analysis of the
crônicas is developed, in which the relationships they present with the research are set out
Analyse und Optimierung der Schaumschlackenfahrweise eines Gleichstrom-Elektrolichtbogenofens mittels Machine Learning Verfahren
No full textModulare Prüfplanung
No full textStarting point of this paper was the insight that inspection planning in its current state does not satisfy today’s needs. The globalization of markets, dynamic sampling of product life cycles and the continuously increasing demands of customers lead to deep changes. Companies react with adaptation of both structural and process organization – processes are being modified, internal structures redefined. The inspection planning was not yet considered except of IT support in some single functions. Steadily increasing product recalls state that products with failures are given into the market – even with security relevant failure. Less visible are the impacts caused by products which lead to lower sales volume or benefits. The causes are one the one hand the costs for amendments, to abolish the failures. On the other hand customers substitute products if the features do not match their needs. In this paper the modular inspection planning was developed, considering globalization of markets, dynamic sampling of product life cycles and the continuously increasing demands of customers: Integrated in the chain of production, strictly orientated to customer needs, based on methods of QM and involving all necessary departments in a company. The concept consists of fife modules planning, development, ramp-up, serial production and application which are positioned along the chain of production. The modules are based on the three dimensions: functions of inspection planning use of QM methods and expertise of departments. The creation and development of the inspection plan is parallel to product development. While the first modules consider customer need when defining the inspection features the following modules integrate the information gained during development and production. Eventually the module application verifies the inspection plan and starts rework if necessary. The internally closed modules are based upon another – the achievment of objectives in ensured by Quality Gates. The maturity of content is assessed from the point of views of internal supplier at the beginning and internal customers at the end of each module. If deviations occur actions are defined and permanently monitored to ensure that the targets will be met
Zuammenhang zwischen der NK-Zell Lizensierung und dem zellulären Glukosemetabolismus in menschlichen natürlichen Killerzellen
No full textNatural killer (NK) cells express activating and inhibitory receptors to distinguish between healthy and aberrant cells. Whereas activating receptors detect stress-ligands on virus-infected or malignant cells, inhibitory receptors bind to self-molecules that are expressed by all nucleated host cells. Inhibitory receptors that bind to self-molecules mediate self-tolerance and transfer functional competence to NK cells, allowing these cells to respond upon activation. This process is known as NK-cell education. Thereby, educated NK cells exhibit increased responsiveness upon stimulation while being tolerant towards healthy host cells at the same time. In contrast, uneducated NK cells, that lack inhibitory receptors for self-molecules, have been shown to be hyporesponsive upon stimulation. To date, little is known about the underlying molecular mechanisms leading to functional differences between educated and uneducated NK cells. An increasing number of studies have shown that immune cell functions can be directly influenced by cellular metabolic pathways. Changes within these metabolic pathways may therefore play a role in NK-cell education. For this reason, the aim of this work was to determine the glycolytic profiles of educated and uneducated NK cells. Primary human NK cells were isolated and co-cultured with the target cell lines K-562 and 721.221. NK-cell function and the expression of inhibitory receptors was assessed via flow cytometry. Based on functional and phenotypical analysis, NK cells were stratified into educated and uneducated NK-cell subsets. In order to determine the glycolytic profile of educated and uneducated NK cells, these subsets were examined for the expression of the glucose transporter Glut1. Using fluorescence-activated cell sorting, NK cells were divided into educated and uneducated NK-cell populations, which were subsequently analyzed for their glycolytic activity in a Seahorse XF glycolysis stress test. Data revealed, that educated NK cells exhibited an increased functional capacity upon stimulation with target cell lines compared to uneducated NK cells. Furthermore, educated NK cells displayed an increased surface expression of the glucose transporter Glut1. In addition, educated NK cells possessed an elevated glycolytic profile. The results of this work showed that educated NK cells display a characteristic metabolic profile that provides a potential model for the underlying mechanisms that lead to functional differences between educated and uneducated NK cells.Natürliche Killer (NK)-Zellen sind Teil des angeborenen Immunsystems und werden zu der Gruppe der Lymphozyten gezählt. Sie besitzen die Fähigkeit abnormale Zellen, wie beispielsweise Tumorzellen oder virusinfizierte Zellen von normalen, körpereigenen Zellen zu unterscheiden. Dies geschieht mit Hilfe spezieller inhibitorischer und aktivierender Rezeptoren auf der Zelloberfläche dieser Zellen. Inhibitorische Rezeptoren vermitteln den Zellen eine Toleranz gegenüber körpereigenen normalen Zellen, während aktivierende Rezeptoren die Zellen zur Ausübung von zytotoxischen Funktionen anregen, welche zum Tod der Zielzelle führen können. Inhibitorische Rezeptoren, welche an körpereigene Moleküle binden, übertragen dabei eine funktionelle Kompetenz, welche es den Zellen erlaubt auf aktivierende Signale zu reagieren. Fehlt den Zellen diese funktionelle Kompetenz, bleiben sie passiv. Dieser Prozess ist auch als NK-Zell Lizensierung bekannt. Dabei weisen lizensierte NK-Zellen bei Stimulation eine erhöhte Funktion gegenüber unlizensierten NK-Zellen auf. Über die zugrunde liegenden molekularen Mechanismen, welche zu funktionellen Unterschieden zwischen lizensierten und unlizensierten NK-Zellen führen, ist nur wenig bekannt. Eine zunehmende Anzahl von Studien konnte zeigen, dass die Funktionen von Immunzellen maßgeblich durch zelluläre Stoffwechselwege beeinflusst werden können. Veränderungen innerhalb dieser Stoffwechselwege könnten daher eine Rolle bei der Übertragung von funktioneller Kompetenz in lizensierten NK-Zellen spielen. Aus diesem Grund war es das Ziel dieser Arbeit, das glykolytische Profil von lizensierten und unlizensierten NK-Zellen zu bestimmen und miteinander zu vergleichen. Dafür wurden primäre human NK-Zellen aus Vollblut isoliert und anschließend mit Zielzelllinien stimuliert. Mit Hilfe von durchflusszytometrischen Methoden konnte die funktionelle Aktivität sowie die Expression von inhibitorischen Rezeptoren bestimmt werden. Basierend auf diesen funktionellen und phänotypischen Analysen, wurden NK-Zellen in lizensierte und unlizensierte Untergruppen eingeteilt. Für die Bestimmung des glykolytischen Profils wurden lizensierte und unlizensierte NK-Zellen auf die Expression des Glukosetransporters Glut1 untersucht. Mittels Fluoreszenz-aktivierter Zellsortierung konnten lizensierte und unlizensierte NK-Zellen isoliert und die glykolytische Aktivität in einem Seahorse XF Glykolyse Stresstest gemessen werden. Dabei konnte gezeigt werden, dass lizensierte NK-Zellen erhöhte Funktion gegenüber unlizensierten NK-Zellen besitzen. Lizensierte NK-Zellen wiesen darüber hinaus eine gesteigerte Expression des Glukosetransporters Glut1 auf. Zudem zeigten lizensierte NK-Zellen ein erhöhtes glykolytisches Profil. Die Ergebnisse dieser Arbeit zeigten, dass lizensierte NK-Zellen ein charakteristisches metabolisches Profil besitzen, welches ein mögliches Erklärungsmodell für die funktionellen Unterschiede zwischen lizensierten und unlizensierten NK-Zellen liefert
OsseoPro: a catalogue of osseous projectiles of the Central European Late Upper Palaeolithic (23–14 ka calBP)
No full textThis catalogue contains metric and visual data on osseous projectiles (points, barbed points, half-round rods, foreshafts) from selected late Upper Palaeolithic sites in Central Europe. For each assemblage considered, there are attribute systems (*csv files) and images (*tif files) available. The catalogue is updated continuously. The work on this catalogue was funded by the Deutsche Forschungsgemeinschaft (DFG) within the framework of the projects: PF 841/2-1 “Raw material. Weapon. Prey: Comparative analysis of the osseous projectile technology of the Central European Magdalenian“ (2016–2019) https://gepris.dfg.de/gepris/projekt/277455211?language=en and PF 841/4-1 “Grubgrabian – Epigravettian – Magdalenian. Characterization of the late Upper Palaeolithic in eastern Central Europe (c. 23.000–14.000 calBP) based on the osseous tools” (2021–2023) https://gepris.dfg.de/gepris/projekt/442218485 Principal investigator: Dr. Sebastian J. Pfeifer Friedrich Schiller University Jena Seminar Prehistoric Archaeology Löbdergraben 24a, 07743 Jena https://orcid.org/0000-0002-1102-4265 Unless stated otherwise, Sebastian J. Pfeifer is the author of all data in this catalogue. The pictures are published under the Creative Commons BY-NC-ND 4.0 DE license (attribution, non-commercial, no derivatives) https://creativecommons.org/licenses/by-nc-nd/4.0/ Have a question or remark? Drop us a mail: [email protected]
Development of a numerical model for the heat and mass transport in an electric arc furnace freeboard
No full textThe topic of this thesis is the development of a numerical model to investigate the heat and mass transport in an EAF freeboard. Some of the challenges presently faced by European steelmakers are increasing costs for raw materials and energy, as well as strict environmental policies. These can be addressed by improving the energy efficiency of the EAF steelmaking process by reducing off-gas and cooling losses. This can be achieved by increasing the degree of combustion of CO and H2 in the furnace freeboard. A better understanding of the mechanisms that cause unwanted emissions during the steelmaking process can also help to develop new methods to reduce pollutants. The long term motivation behind the topic of this thesis is therefore to create a numerical EAF model with which the influence of process innovations on the fluid flow field, energy transport and chemical reactions within the freeboard of an electric arc furnace can be analysed. At this stage, the main objective is to qualitatively investigate the influence of the arc region on the amount of post-combustion within the freeboard. The effect of a change in the foamy slag height on the resulting amount of post-combustion is also investigated.The numerical EAF model represents the power-on/flat-bath stage of the steelmaking process in an exemplary AC electric arc furnace for quasi-steady state heat loss conditions. The AC EAF has a capacity of 100 tons of steel, a transformer rating of 90 MVA and and an inner vessel diameter of 6.1 m. A simplified time-averaged arc model based on the channel arc model was developed in order to include the influence of the arc region on the conditions within the freeboard. The plasma arcs are not part of the solution domain, but are represented as segmented cylindrical surfaces extending from each electrode tip to the bath surface. In contrast to previous models, this simplified arc model includes not only the energy input due to the intense thermal radiation, but also the kinetic energy input due to the arc in- and outflow as well as the energy input due to the heating of the entrained furnace atmosphere in the arcs. The graphite electrodes are part of the solution domain, whereby the Joule heating due to the AC current flowing through the electrodes is taken into account. For the energy balance of the solution domain the energy input from the arc region plus the Joule heating in the electrodes represents the electric power input from the secondary circuit. This energy contribution is much smaller than the true electric power input, as it equates the amount needed, in addition to the other energy inflows, to cover the stationary power losses. The discrete ordinates thermal radiation model available in the CFD code ANSYS FLUENT (Version 14.5) was chosen to model the thermal radiation exchange, whereby the thermal radiation absorption coefficient of the furnace atmosphere is calculated with the weighted-sum-of-grey-gases-model. Species transport with volumetric reactions and the finite-rate/eddy dissipation turbulence chemistry interaction is used to calculate the mass transfer and chemical reactions within the freeboard. The furnace atmosphere is defined to be a mixture of CO, CO2, H2O, N2 and O2. The post combustion of CO to CO2 is simulated according to the gas-shift reaction available for the oxidation of CO in FLUENT. The realizable k-ε model with standard wall functions for the near wall treatment was selected to simulate the turbulent viscous flow. The geometry of the EAF model extends from the uppermost layer of the metal bath to the beginning of the off-gas extraction downstream of the post-combustion gap. The foamy slag is modelled as a solid layer and the top layer of the bath, also considered as a solid, is included. These two layers allow the simulation of downward absorption and redistribution of energy from the arc region, which is reflected by the resulting temperature distribution at the foamy slag layer surface. Burners, lances or injectors are not included at present. The decarburization of the molten metal bath is taken into account by the definition of a homogenous source of CO at the surface of the foamy slag layer. An average value for the graphite electrode consumption is modelled by a corresponding CO source and O2 sink at the electrode surfaces. Ingress air is defined to enter the freeboard through the slag door, roof gap and electrode gaps and air flows in at the post-combustion gap. It is assumed that a small amount of steam enters the vessel through the electrode gaps due to electrode cooling. The upper vessel, roof, exhaust elbow and exhaust extraction are cooled by water cooled panels. The walls of the lower vessel, balcony and roof delta zone are defined to consist of refractory material and are cooled by natural convection and thermal radiation to the ambient on the outside of the vessel.The results obtained with the numerical EAF model are used to evaluate the influence of the inclusion of the energy input due to the heating and increase in momentum of the furnace atmosphere drawn into and flowing out of the arc region on the conditions within the freeboard. Furthermore, the impact of the arc region flow on the post-combustion of CO to CO2 in the freeboard for a free-burning arc length of 230 mm is compared to that for a free-burning arc length of only 50 mm.The modelling of the arc region has a large influence on the flow field, temperature distribution and post-combustion. The results show that due to the inclusion of the arc in- and outflow a total increase in the simulated energy input within the vessel of 4.42 MW results. This is due to the correspondingly higher temperatures and circulation leading to an increase in the post-combustion of CO to CO2 within the freeboard. The inclusion of the arc in- and outflow should therefore not be neglected in future EAF models. An increased slag height not only protects the cooling panels from the thermal radiation of the arcs. It also leads to a reduction in the interaction between the flow in the arc region and in the freeboard. This in turn reduces the amount of mixing of CO from the slag layer with the ingress air and therefore also the amount of post-combustion in the freeboard. As a result a decrease in the free-burning arc length from 230 mm to 50 mm leads to a reduction in the total energy input within the solution domain of 3.22 MW. The numerical EAF simulation model developed during this thesis delivers valuable information which helps one to understand the heat and mass transfer processes taking place within the EAF freeboard. Furthermore, several important insights were gained concerning necessary future developments of the model
Gasanalytik, Schichtdickenmessungen und Stabilitätsuntersuchungen an kostengünstigen Elektroden für stationäre Energiespeicher
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