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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

METALLURGICAL LENGTH PREDICTION IN CONTINUOUS CASTING

Rashed Daoud Al Manasir (15454607) 16 May 2023 (has links)
<p> Around 98% of the crude steel produced in the United States goes through the CC process, in which a water-cooled mold is used to solidify molten steel using water sprays to create semifinished slabs or billets. The quality of both the exterior and inside of the slab is directly related to the rate at which it is cooled, making secondary cooling a difficult process. The heat must be removed efficiently without causing the slab to crack or deform in any way. Low grade steel is produced because of inadequate spray cooling and solidification, which leads to flaws like cracking and breakout. Real-time online dynamic casting control systems are becoming increasingly popular in continuous casting as a means to increase yield and energy efficiency. These systems are built to reliably produce high-quality steel products via real-time temperature measurements and dynamic adjustment of the spray cooling rate. For real-time heat transfer and solidification calculations in the field, the key challenge is determining an accurate Heat Transfer Coefficient (HTC) for the steel product's surface. The correlations for predicting the spray cooling rate empirically have been developed with great care. Nevertheless, these correlations are only valid under specific application circumstances. Building it takes a significant amount of time and effort, and there is no assurance that the correlation will continue to accurately predict HTC even if the development process is modified in any way. An in-depth investigation into the heat transfer mechanisms that take place during the secondary cooling step of continuous steel casting is required in order to achieve control and optimization goals for this step. The non-optimized solidification process also contributes to the formation of inhomogeneous steel properties. The project required the application of computational fluid dynamics modeling techniques so that the casting process could be regulated and improved upon. Simulation of droplet formation, droplet transport, and impingement heat transfer during secondary cooling with an air-mist nozzle in a 3D computational fluid dynamics (CFD) model is going to be done in this study with the intention of generating a multivariable correlation that can accurately predict the lumped HTC under any casting condition. This will be accomplished by using the model. It modeled the solidification of the whole continuous caster by taking into consideration the impacts of roll gap, roll diameter, casting speed, and superheat in order to estimate the metallurgical length and slab temperature. This was done in order to calculate the metallurgical length </p>
2

Effectiveness of subglottic suctioning in the prevention of ventilator associated pneumonia

Amato, Cody Winston 01 May 2011 (has links)
Ventilator-associated pneumonia (VAP) is the leading healthcare-acquired infection among ventilated patients in intensive care units (ICU). VAP is a serious patient complication that results in increased hospital length of stay, cost, morbidity, and mortality. The accumulation of subglottic secretions above the endotracheal tube (ETT) cuff increases the risk of VAP, as these secretions may leak around the cuff of the ETT resulting in aspiration and an increased risk for infection. An in depth literature review was done to determine the effectiveness of subglottic secretion aspiration (by means of specialized ETT tubes with intrinsic suction lumens) in decreasing the incidence rate of VAP. Evidenced-based data were gathered from the CINAHL Plus with Full Text, PubMed, and Cochrane Database of Systematic Reviews databases for this review. VAP guidelines recommend subglottic secretion aspiration as a means to prevent its occurrence. However, important variables such as suction pressure, frequency, secretion viscosity, and ETT cuff pressure and volume need to be considered. The interaction among these variables determines the effectiveness of subglottic secretion removal. The goal of this review was to highlight these interactions and provide evidenced-based information for critical care nurses to expand their understanding of the dynamics involved in subglottic secretion aspiration and how to efficiently use this practice to prevent VAP.
3

Istraživanje savremenih tehnologija za kontinualno livenje bronze / Exploration of modern technology for continuous casting bronze

Arsenović Milan 05 February 2015 (has links)
<p>Kontinualno livenje se razlikuje od drugih procese očvršćavanja po svom<br />prirodnom stabilnom stanju, u odnosu na spoljnog posmatrača u<br />laboratorijskim referentnim uslovima. Rastopljeni metal očvršćuje prema<br />zidovima kalupa, dok se istovremeno povlači sa dna kalupa brzinom koja<br />održava čvrsto/tečno na konstantnom položaju tokom vremena. Proces<br />funkcioniše najbolje kada svi njegovi aspekti rade u ovakvom stabilnom<br />stanju. Vertikalne mašine se koriste za kontinuirani proces livenja. Ovaj rad<br />istražuje uticaj brzina protoka liva u kontinuiranom procesu livenja . U ovom<br />istraživanju , su prikazani rezultati kontinuiranog livenja bronze. Na osnovu<br />raspodele temperature na površini uzorka, tokom ispitivanja zatezne<br />čvrstoće, vrši se detekcija pukotina. Ova ispitivanja, koristeći metode<br />mehanike loma, su primenjena zbog sigurnosti procene metalnih konstrukcija.<br />Numerička simulacija distribucije napona, je takođe predstavljena. Rezultati<br />su pokazali, da je termografija pogodan metod za praćenje i predviđanje<br />prslina i njihovog rasta, kao i za određivanje kritičkog napona u toku<br />deformacija. Na kraju ovih istraživanja, može se zaključiti, da je ovaj rad<br />doprineo razvoju i usavršavanju tehnologije za vertikalno livenje na dole u<br />značajnoj meri, kako u naučnoj tako i u komercijalnoj sferi.</p> / <p>Continuous casting is distinguished from other solidification processes by its steady<br />state nature, relative to an outside observer in laboratory frame of reference. The<br />molten metal solidifies against the mold walls, while it is simultaneously withdrawn from<br />the bottom of the mold at rate which maintains the solid/liquid interface at a constant<br />position in time. The process works best when all of its aspects operate in this steadystate<br />manner. Vertical machines are used for continuous casting process. This work<br />investigates the effect of mold flow velocities in continuous casting process. In this<br />research, are the results of continuous casting study of bronze. Based on the<br />distribution of temperature on the surface of the sample, during the tensile test, crack<br />tip are determined. The tests, using the methods of fracture mechanics, were applied<br />due to the safety assessment of metal structures. The numerical simulation of stress<br />distributions, on the same model under the same condition, is presented, too. The<br />results have showed, that thermography is a suitable method for monitoring and<br />prediction of crack initiation and growth, as well as, critical stress in deformations. At the<br />end of these studies, we can conclude that this work has contributed to the<br />development and improvement of technologies for vertical casting to down to a<br />considerable extent, both in science and in the commercial sphere.</p>
4

Advanced Numerical Techniques for Dynamic and Aerodynamic Analysis of Bridges

Naderian, Hamidreza January 2017 (has links)
To meet the economic, social and infrastructure needs of the community for safe and efficient transportation systems, long span bridges have been built throughout the world. Long span bridges are one of the most challenging kinds of structures in civil engineering. The cable-stayed bridges are of great interest mainly as an alternative and a more economic solution than the one of suspension bridges. In addition, the fiber reinforced polymer (FRP) composites are, nowadays, successfully used for constructing modern bridges, where the significant weight saving provides additional benefits. Because of the great flexibility, modern long-span cable-stayed bridges are usually very susceptible to dynamic loads especially to the earthquake and strong winds. Therefore, the earthquake-resistant and wind-resistant designs become one of key issues for successful construction of bridges. The objective of the present research is to develop a very efficient spline finite strip technique, for modelling and analysis of both conventional and hybrid FRP cable-stayed bridges. The study falls into the categories of bending, free vibration, seismic, and aerodynamic flutter analysis. The spline finite strip method (SFSM) is one of the most efficient numerical methods for structural analysis of bridges, reducing the time required for estimating the structural response without affecting the degree of accuracy. In the finite strip method, the degrees of freedom could be significantly reduced due to the semi-analytical nature of this method. However, the previous versions of SFSM are not able to model the entire bridge system. For that reason, the structural interactions between different structural components of the bridge could not be handled. In addition, the vibrations and displacements of the towers and cables could not be investigated. In the present formulation, all these obstacles have been eliminated. Moreover, the proposed finite strip technique is very efficient and accurate due to the drastic reduction in the formulation time, simplicity of data preparation, rapid rate convergence of the results, and the semi-analytical nature. Last but not least, and for the first time, a fully finite strip solution is extended to the area of wind engineering. Using the spline finite strip discretization, the aerodynamic stiffness and mass properties of the long-span cable-stayed bridge are derived. The aerodynamic properties along with the structural properties of long-span plates and bridges are formulated in the aerodynamic equation of motion and are used to analyze the flutter problem. The accuracy and efficiency of the proposed advanced finite strip method is verified against the finite element and field measurement results. The results demonstrate that this methodology and the associated computer code can accurately predict the dynamic and aerodynamic responses of the conventional and FRP long-span cable-stayed bridge systems. The outcome of the present research will lead to a comprehensive structural analysis of bridges in the framework of the proposed discretization which is more efficient and straightforward than the finite element analysis.
5

Kommunicera mera... : Vårdpersonals erfarenheter av kommunikationssituationen vid CPAP-utprovning

Liabäck, Frida January 2018 (has links)
Många patienter med obstruktivt sömnapnésyndrom (OSAS) som behandlas med Continuous Positive Airways Pressure (CPAP) avbryter sin behandling i ett tidigt skede. Att inte vara följsam behandlingen kan innebära olika hälsorisker för patienten som kan få allvarliga konsekvenser. Kommunikationssituationen vid det initiala utprovningsbesöket kan därför påverka huruvida patienten inte blir följsam och fullföljer behandlingen. Syftet med denna studie var att belysa hur vårdpersonal beskriver sina erfarenheter av kommunikationssituationen vid det initiala utprovningsbesöket av CPAP. En kvalitativ intervjustudie genomfördes med 23 personer som alla möter denna grupp av patienter.  Som analysmetod användes induktiv innehållsanalys. Vid analysen av materialet framkom tre kategorier; Bygga en relation, Inta ett pedagogiskt förhållningssätt samt Stödja patientens delaktighet. Dessa tre kategorier mynnade ut i ett tema som visade på hur kommunikationssituationen beskrevs Skapa förutsättning för lärande hos patienten. Studien belyser vikten av en samskapande vård och ett personcentrerat förhållningssätt där patienten ses som en partner i de beslut som tas samt hur vårdpersonalens pedagogiska förhållningssätt påverkar kommunikations-situationen på olika sätt. Erfarenheterna som beskrevs i studien upplevdes påverka patientens möjligheter till lärande i situationen för en ökad följsam till sin CPAP-behandling. / Many patients with obstructive sleep apnea syndrome (OSAS) treated with Continuous Positive Airways Pressure (CPAP) interrupt their treatment at an early stage. Not having adherence to the treatment implies various health risks for the patient that can have serious consequences. Therefore, the communicationsituation at the initial testing visit may affect whether the patient does not follow up and completes the treatment. The purpose of this study was to illustrate how healthcare professionals describe their experiences of the communicationsituation at the initial visit testing CPAP. A qualitative interview study was conducted with 23 people who all meet this group of patients. As an analytical method, inductive content analysis was used. In the analysis of the material three categories was revealed; Build a Relationship, Take an Educational Approach and Support the Patient's Participation. These three categories emerged in a theme that demonstrated how the communication situation was described as Creating a prerequisite for learning for the patient. The study highlights the importance of a person-centered approach, a co-productive care where the patient is seen as a partner in the decisions and how the healthcare professionals' pedagogical approaches affect the communicationsituation in different ways. The experiences described in the study were perceived to affect the patient's ability to learn in the situation for an increased adherence to the CPAP treatment.
6

Gemeinschaften in neuen Medien. Erforschung der digitalen Transformation in Wissenschaft, Wirtschaft, Bildung und öffentlicher Verwaltung: 22. Workshop GeNeMe‘19 Gemeinschaften in Neuen Medien

Köhler, Thomas, Schoop, Eric, Kahnwald, Nina 06 December 2019 (has links)
Digitalisierung ist mehr denn je das Top-Thema in Wirtschaft, Wissenschaft und gesamtgesellschaftlichen Entwicklungen. Infrastrukturen und Kompetenzen stehen im Vordergrund vieler Debatten. Die Frage, welche Branche in welchem Umfang von der Digitalisierung betroffen sein wird oder bereits ist, treibt nicht nur Führungskräfte um. Waren informationstechnologische Innovationen bis vor kurzem etwas für sogenannte (Hyper-)Nerds, so sind sie mittlerweile zum alltäglichen Gegenstand geworden. Wir haben uns offenbar auf den permanenten Wandel eingelassen. Aber: Wo geht die Reise tatsächlich hin? Sind große Datenmengen Bedrohung oder Chance? Können wir diese überhaupt verarbeiten oder bedarf es dafür grundlegend veränderter Werkzeuge und Methoden – wie Visual Analytics, Virtuelle Rekonstruktion, Virtual Engineering? Die 22. GeNeMe hat diese Themen aufgegriffen und wird sie in vielfältigen Diskussionen präsentieren. [... aus der Einleitung]:Forschung zur digitalen Transformation in Wissenschaft, Wirtschaft, Bildung und öffentlicher Verwaltung XXI Communities in New Media. Researching the Digital Transformation in Science, Business, Education & Public Administration XXV A Community Research 1 A.1 Design Claims für Community-Plattformen im Kontext des bottom-up Urbanism 1 A.2 Systemkonzept und Modellierung beruflicher Handlungen im FeDiNAR-AR-Lernsystem 12 A.3 Altersbezogene Unterschiede bei der Interaktion mit einem Virtual-Reality-System 24 A.4 Community-based Service-Learning and Digital Media – A Teaching Practice Report on a Flipped-Classroom-based Crowdfunding Course for Social Pedagogues35 A.5 Online-Debatten mit Künstlicher Intelligenz verbessern 41 B Digitale Transformation in Education and Workspace 43 B.1 „Verwaltung to go?“ – Möglichkeiten und Grenzen mobilen Arbeitens in der öffentlichen Verwaltung 43 B.2 Digitalization in schools – An empirical study of teachers’ attitude towards the use of ICTs after the introduction of a “One Laptop per Teacher” Initiative 57 B.3 Onlinegestützte Bildungs- und Beratungsformate – neue Wege zur Entlastung pflegender Angehöriger von an Demenz erkrankten Personen im ländlichen Raum durch Schaffung neuer „Sozialräume“? 70 C Online Research Methods 80 C.1 Online-Fragebogen auf mobilen Geräten: Ein Layout- Vergleich 80 C.2 Nutzung von Online-Fragebogen auf Smartphones und Desktops: Eine Analyse von soziodemographischen und Kontextfaktoren 91 C.3 Ökonomie und Fairness von Constructed-Response-Items in E-Assessments 101 C.4 Lernbedarf vs. Lernbedürfnis: eine kritische Bestandsaufnahme zur Wirksamkeit von diagnostischen Online-Selbsttests 112 D Customer Experience 121 D.1 Die Sicherung der Stadt als gesellschaftlicher Mittelpunkt – Die Inspiration als Konzept zur Stärkung der Kunde-Händler-Beziehung 121 D.2 Förderung der Kundeninteraktion zur Nutzung von Datenvisualisierungen auf Basis von Smart Metering im Privatkundenbereich 133 D.3 Bedürfniserhebung durch Chatbots an ausgewählten Touchpoints innerhalb der Kundenkommunikation 144 D.4 Shop with Heart: Entwicklung und Evaluation eines emotionsbasierten Interfaces 153 E Digital and Online Education 165 E.1 Erklärvideos zur Wissensvermittlung im Hochschulkontext – ein Praxisbeispiel im fächerübergreifenden Austausch 165 E.2 Zuversichtserfassung als Mittel zur Stärkung von selbstreguliertem Lernen 170 E.3 Digitalisation in Higher Education: A Flipped Classroom Arrangement to foster Internationalisation 174 E.4 Forecasting EduTech for the next decade. Scenario development teaching patterns in general versus academic education 178 F Knowledge Cooperation 183 F.1 LOS geht’s! Learning Experience durch Gamification 183 F.2 Datenmodelle für fachübergreifende Wissensbasen in der interdisziplinären Anwendung 189 F.3 Agile Lehr- und Lernressourcennutzung in kooperativen und kollaborativen Netzwerken 193 F.4 Gamifizierte Augmented Reality-Anwendungen im Tourismuskontext: Ein Literaturreview zu Gestaltungsansätzen, Chancen und Risiken 197 G Continious and Vocational Education 211 G.1 Peer-Groups als Antwort auf die digitale Exklusion – Best Practice Beispiel zur Förderung digitaler Fähigkeiten bei älteren Erwachsenen 211 G.2 Technologieunterstütztes Lernen in nicht-kommerziellen Weiterbildungsinstitutionen. Eine Bestandsaufnahme im sächsischen Raum 228 G.3 Digitale betriebliche Weiterbildung – wo geht die Reise hin? 240 G.4 Wie digital ist die Berufsschule? – Eine Analyse anhand von Online-Berichtsheften 252 H Motivation and Technology Use 261 H.1 Sind bescheidene Masterminds wirklich konfliktscheu? Der Einfluss von Persönlichkeit und Spielertypen auf Spielelemente in spielbasierten Lernanwendungen 261 H.2 Making the Right Choice: Gamification for Different Attribution Styles to Increase Motivation 271 H.3 Digitales Lernen fesselnd gestalten: Motivation beim Lösen verschiedener Aufgabentypen 282 H.4 Kritischer Perspektivenwechsel im virtuellen Klassenzimmer – Charakteristika einer erfolgreichen virtuellen Zusammenarbeit aus Studierendensicht 292 I Gamebased and Augmented Learning 301 I.1 Learn&Play – Entwurf eines Serious Games für Ingenieurstudiengänge nach dem Learning Mechanic – Game Mechanic Framework 301 I.2 DOmIcILE-VR – Wohnungsabnahmen virtuell trainieren 306 Autorenverzeichnis 314 / Digitalization is more than ever the top topic in economics, science and societal developments. Infrastructures and competencies are at the forefront of many debates. The question of which industry is or will be affected by digitization next and to what extent is not only driving executives around. While information technology innovations were something for so-called ‘(hyper-)nerds’ until recently, it has become an everyday item. We seem to have embarked on permanent change. But where does the journey actually go? Are large amounts of data a threat or an opportunity? Can we even process them or do we need fundamentally changed tools and methods - such as Visual Analytics, Virtual Reconstruction, Virtual Engineering? The 22nd GeNeMe has taken up these issues and will present them in various discussions. [... from the introduction]:Forschung zur digitalen Transformation in Wissenschaft, Wirtschaft, Bildung und öffentlicher Verwaltung XXI Communities in New Media. Researching the Digital Transformation in Science, Business, Education & Public Administration XXV A Community Research 1 A.1 Design Claims für Community-Plattformen im Kontext des bottom-up Urbanism 1 A.2 Systemkonzept und Modellierung beruflicher Handlungen im FeDiNAR-AR-Lernsystem 12 A.3 Altersbezogene Unterschiede bei der Interaktion mit einem Virtual-Reality-System 24 A.4 Community-based Service-Learning and Digital Media – A Teaching Practice Report on a Flipped-Classroom-based Crowdfunding Course for Social Pedagogues35 A.5 Online-Debatten mit Künstlicher Intelligenz verbessern 41 B Digitale Transformation in Education and Workspace 43 B.1 „Verwaltung to go?“ – Möglichkeiten und Grenzen mobilen Arbeitens in der öffentlichen Verwaltung 43 B.2 Digitalization in schools – An empirical study of teachers’ attitude towards the use of ICTs after the introduction of a “One Laptop per Teacher” Initiative 57 B.3 Onlinegestützte Bildungs- und Beratungsformate – neue Wege zur Entlastung pflegender Angehöriger von an Demenz erkrankten Personen im ländlichen Raum durch Schaffung neuer „Sozialräume“? 70 C Online Research Methods 80 C.1 Online-Fragebogen auf mobilen Geräten: Ein Layout- Vergleich 80 C.2 Nutzung von Online-Fragebogen auf Smartphones und Desktops: Eine Analyse von soziodemographischen und Kontextfaktoren 91 C.3 Ökonomie und Fairness von Constructed-Response-Items in E-Assessments 101 C.4 Lernbedarf vs. Lernbedürfnis: eine kritische Bestandsaufnahme zur Wirksamkeit von diagnostischen Online-Selbsttests 112 D Customer Experience 121 D.1 Die Sicherung der Stadt als gesellschaftlicher Mittelpunkt – Die Inspiration als Konzept zur Stärkung der Kunde-Händler-Beziehung 121 D.2 Förderung der Kundeninteraktion zur Nutzung von Datenvisualisierungen auf Basis von Smart Metering im Privatkundenbereich 133 D.3 Bedürfniserhebung durch Chatbots an ausgewählten Touchpoints innerhalb der Kundenkommunikation 144 D.4 Shop with Heart: Entwicklung und Evaluation eines emotionsbasierten Interfaces 153 E Digital and Online Education 165 E.1 Erklärvideos zur Wissensvermittlung im Hochschulkontext – ein Praxisbeispiel im fächerübergreifenden Austausch 165 E.2 Zuversichtserfassung als Mittel zur Stärkung von selbstreguliertem Lernen 170 E.3 Digitalisation in Higher Education: A Flipped Classroom Arrangement to foster Internationalisation 174 E.4 Forecasting EduTech for the next decade. Scenario development teaching patterns in general versus academic education 178 F Knowledge Cooperation 183 F.1 LOS geht’s! Learning Experience durch Gamification 183 F.2 Datenmodelle für fachübergreifende Wissensbasen in der interdisziplinären Anwendung 189 F.3 Agile Lehr- und Lernressourcennutzung in kooperativen und kollaborativen Netzwerken 193 F.4 Gamifizierte Augmented Reality-Anwendungen im Tourismuskontext: Ein Literaturreview zu Gestaltungsansätzen, Chancen und Risiken 197 G Continious and Vocational Education 211 G.1 Peer-Groups als Antwort auf die digitale Exklusion – Best Practice Beispiel zur Förderung digitaler Fähigkeiten bei älteren Erwachsenen 211 G.2 Technologieunterstütztes Lernen in nicht-kommerziellen Weiterbildungsinstitutionen. Eine Bestandsaufnahme im sächsischen Raum 228 G.3 Digitale betriebliche Weiterbildung – wo geht die Reise hin? 240 G.4 Wie digital ist die Berufsschule? – Eine Analyse anhand von Online-Berichtsheften 252 H Motivation and Technology Use 261 H.1 Sind bescheidene Masterminds wirklich konfliktscheu? Der Einfluss von Persönlichkeit und Spielertypen auf Spielelemente in spielbasierten Lernanwendungen 261 H.2 Making the Right Choice: Gamification for Different Attribution Styles to Increase Motivation 271 H.3 Digitales Lernen fesselnd gestalten: Motivation beim Lösen verschiedener Aufgabentypen 282 H.4 Kritischer Perspektivenwechsel im virtuellen Klassenzimmer – Charakteristika einer erfolgreichen virtuellen Zusammenarbeit aus Studierendensicht 292 I Gamebased and Augmented Learning 301 I.1 Learn&Play – Entwurf eines Serious Games für Ingenieurstudiengänge nach dem Learning Mechanic – Game Mechanic Framework 301 I.2 DOmIcILE-VR – Wohnungsabnahmen virtuell trainieren 306 Autorenverzeichnis 314

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