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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.
41

Concept Design and Prototyping of a Test Rig for In Vitro Hemolysis Assessment of Pulsatile Blood Pumps : A design with an Improved Blood Filling and De-airing Interface / Konceptdesign och prototypframställning av en testrigg för in vitro hemolysbedömning av pulserande blodpumpar : En design med ett förbättrat gränssnitt för blodfyllning och avluftning

Lee, Yun-Ting January 2022 (has links)
Hemolysis assessment of heart pumps is necessary to be carried out before progressing to clinical trials. Blood pump hemolysis assessment standards, such as ASTM F1830 and F1841, were initially based on continuous flow pumps and included the pulsatile flow pumps later in 2019. However, a lack of guidance on the test rig design results in diverse rigs being applied in literature and companies. An aluminum-profile-based rig, which was named the old rig in this study, was created based on Gräf’s mock loop for pulsatile flow pumps in the literature. Nevertheless, this rig was without a user-friendly interface for blood-filling and de-airing, and it led to a risk of blood leakage, more effort required, and a chance of more hemolysis induced during the processes. Thus, this thesis aims to create a new rig for pulsatile flow pumps and improve its usability for blood filling and de-airing. To achieve the goals, a new rig design concept and its prototype were generated through the design thinking process. Next, user experience testings with the tasks, rig filling, de-airing, and emptying, were given to 5 users to validate if the features of the new rig could satisfy the user needs and improve the usability in terms of efficiency and user satisfaction. Lastly, two blood tests were conducted with the paired rigs, the old rig, and the new rig, based on the same pulsatile flow pump prototypes to investigate the impact of the new system layout on the hemolysis assessment. The results from the user experience testing showed that the new rig had a higher efficiency mainly based on the positive qualitative feedback of the users. The average satisfaction scores in all three tasks were higher on the new rig than on the old rig. Furthermore, the new rig did not induce more hemolysis than the old rig based on the two blood tests. Though the results were not statistically significant, the new rig could be a potential reference for a new standard of hemolysis testing on pulsatile blood pumps with user-friendly blood filling and de-airing processes. / Hemolys bedömning av hjärtpumpar är nödvändigt att utföras innan fortsättning till kliniska tester. Blodpump hemolys bedömning standarder, såsom ASTM F1830 och F1841, var initialt baserade på kontinuerliga flödespumpar, men sedan 2019 har även pulserande pumpar blivit inkluderadeDock, ingen klar vägledning av test rigg design, resulterar i att diverse riggar har använts i litteraturen och företag. En aluminiumprofilbaserad rigg, som i denna studie fick namnet den gamla riggen, skapades utifrån Gräfs mock loop för pulserande flödespumpar i litteraturen. Ändå saknade denna rigg ett användarvänligt gränssnitt för blodfyllning och avluftning, och det ledde till risk för blodläckage, mer ansträngning som krävdes och en chans att mer hemolys inducerades under processerna. Således, syftet med denna avhandling är att skapa en ny rigg för pulserade flödespumpar och förbättra användbarheten för blodfyllning och avluftning. För att uppnå målet, generades en ny rigg design koncept och dess prototyp genom designtänkande processen. Sedan, gavs följande användarupplevelse uppgifter, riggfyllning, avluftning och tömning till 5 användare för att validera om funktionerna på den nya riggen kunde uppfylla användarens behov och förbättra användbarheten gällande effektivitet och användarnöjdhet. Slutligen, genomfördes två försök med blod med de parade riggarna, gamla riggen och den nya riggen, baserat på samma pulserade flödespump prototyp för att undersöka det nya systemets layout påverkan på hemolys bedöming. Resultatet från användarupplevelse försöken visade att den nya riggen hade högre effektivitet vilket främst baserades på den kvalitativa återkopplingen från användarna. Den genomsnittliga tillfredsställelsen i alla tre uppgifter var högre med den nya riggen än med gamla riggen. Det var ingen ökning av hemolys i den nya riggen, baserat på de två blodförsöken. Trots att resultaten inte var statiskt säkerställt, så visade det sig vara en potentiell referens för en ny standard för hemolystestning på pulserade blodpumpar med användarvänliga blodfyllnings- och avluftningsprocesser.
42

Information Presentation in Search Engines on Mobile Devices

Öfverman, Jakob January 2010 (has links)
<p>This thesis discusses the possibilities to visualise the presentation layer of a search engine on a mobile device in an alternative way. Previous work in the area has shown that the use of text-based-lists can be problematic when accessed on a device with a limited display. In the scope of the thesis and in order to tackle the current problems when displaying the results a literature review was carried out. The findings of the review formed the basis for a requirement definition on which a mock-up was developed. The mock-up was then evaluated and tested during a usability test where a number of users got to experience the alternative presentation layer that uses a visualisation technique called tree- map. The results from the test show that the mock-up could be seen as a alternative to the current presentation of results. The mock-up also shows that a future implementation could also include the use of categories and sorting of information in order to provide content with a meaning.</p>
43

Experimental study of the mechanics of the intra-aortic balloon

Biglino, Giovanni January 2010 (has links)
This thesis deals with the mechanics of the Intra-Aortic Balloon Pump (IABP), the most widely used temporary cardiac assist device, whose beneficial action is based on the principle of counterpulsation. The investigation is carried out in vitro in increasingly more realistic setups, including a mock circulatory system with physiological distribution of peripheral resistance and compliance in which IABP counterpulsation was simulated. Pressure and flow measurements show the effect of variables such as intra-luminal pressure, angle and aortic compliance on balloon hemodynamics. These data are complemented by results on the duration of balloon inflation and deflation obtained by means of high-speed camera visualisation. Furthermore, wave intensity analysis is carried out and it is identified as a possible alternative method for the assessment of IABP performance. This work includes two prototypes of intra-aortic balloons of novel shape with the balloon chamber tapering both from and toward the balloon tip. In clinical terms, with reference to the semi-recumbent position in which patients assisted with the IABP are nursed in the intensive care unit, the results presented in this thesis indicate that operating the balloon at an angle compromises the benefit of counterpulsation when assessed in vitro.
44

L'interface multi-utilisateur pour le travail collaboratif avec les multiples représentations de la maquette numérique / Multi-user interface and its use for collaborative work with multiple representations of Digital Mock-Up

Li, Bo 19 December 2017 (has links)
Les outils actuels de gestion industrielle s'appuient généralement sur l'ingénierie concourante, qui implique la réalisation des étapes de gestion du cycle de vie des produits en parallèle et l'intégration des données techniques pour le partage entre les différents experts. Divers experts utilisent des logiciels spécifiques à leur domaine pour produire diverses données compilées via une maquette numérique. Ces experts multidisciplinaires ont tendance à travailler en collaboration pendant le développement de produits. Au cours d'activités de conception collaborative synchrones, telles que les revues de projet et la prise de décisions, les experts de différents domaines doivent dialoguer, négocier et choisir pour résoudre les différences multidisciplinaires. De nombreux domaines tels que la conception collaborative et de l’évaluation des produits avec multiples experts, ont une grande demande de nouveaux outils d'aide à la collaboration. Avec le développement des technologies de l'Interaction Homme-Machine (IHM), il est possible de concevoir des outils et des méthodes plus intuitifs pour améliorer la collaboration co-localisée entre les experts.Dans cette thèse, afin d'améliorer la collaboration avec des experts de différents domaines et communiquer via la maquette numérique, une IHM multi-utilisateurs avec des représentations différentes lors d'un travail collaboratif a été pris en considération et son influence sur la collaboration multidisciplinaire co-localisée est étudiée. Un schéma de la méthodologie d'évaluation de la contribution à un système multi-utilisateurs et des expérimentations sont proposées. Les résultats des expériences des résultats significatifs concernant l’efficacité de la réalisation de la tâche, l'utilisabilité de l'Interaction Homme-Machine et la performance de la collaboration lors de l'utilisation de l'interface multi-utilisateurs dans les scénarios de collaboration multidisciplinaires. Les contributions et apports de cette interface sont discutés. / The current industrial management tools generally rely on Concurrent Engineering, which involves conducting Product Lifecycle Management stages in parallel and integrating technical data for sharing across different experts. Various experts use domain-specific software to produce various data into Digital mock-up. These multidisciplinary experts have trends to work collaboratively during product development. During co-located synchronous collaborative design activities, such as project review and decision-making, experts from different domains must discuss, negotiate, and compromise to solve multidisciplinary differences. Many areas, such as early collaborative design and multi-expert product evaluation, have a great demand for new collaborative support tools. With the development of Human Computer Interaction, it is possible to devise more intuitive tools to enhance co-located collaboration across experts.In this thesis, to enhance the collaboration with experts on different domains to communicate with DMU, a multi-user interface across users with different representations during a collaborative work has been taken into consideration and its influence on co-located multidisciplinary collaboration is investigated. A schema of the methodology for evaluating the contribution to a multi-user system and the multiple users’ experiences is proposed. Results of experiments show the significances of the efficiency of task, the usability of interface, and the performance of collaboration during the use of multi-user CHI in multidisciplinary collaborative scenarios. The contributions of what multi-user interface brings to the design criteria of multi-user interface and multi-user co-located collaboration are discussed.
45

Three Essays on Phishing Attacks, Individual Susceptibility, and Detection Accuracy

Bera, Debalina 08 1900 (has links)
Phishing is a social engineering attack to deceive and persuade people to divulge private information like usernames and passwords, account details (including bank account details), and social security numbers. Phishers typically utilize e-mail, chat, text messages, or social media. Despite the presence of automatic anti-phishing filters, phishing messages reach online users' inboxes. Understanding the influence of phishing techniques and individual differences on susceptibility and detection accuracy is an important step toward creating comprehensive behavioral and organizational anti-phishing awareness programs. This dissertation seeks to achieve a dual purpose in a series of three essays. Essay 1 seeks to explore the nature of phishing threats that including identifying attack intentions, and psychological and design techniques of phishing attacks. Essay 2 seeks to understand the relative influence of attack techniques and individual phishing experiential traits on people's phishing susceptibility. Essay 3 seeks to understand an individual's cognitive and affective differences that differentiate between an individual's phishing detection accuracy.
46

Information Presentation in Search Engines on Mobile Devices

Öfverman, Jakob January 2010 (has links)
This thesis discusses the possibilities to visualise the presentation layer of a search engine on a mobile device in an alternative way. Previous work in the area has shown that the use of text-based-lists can be problematic when accessed on a device with a limited display. In the scope of the thesis and in order to tackle the current problems when displaying the results a literature review was carried out. The findings of the review formed the basis for a requirement definition on which a mock-up was developed. The mock-up was then evaluated and tested during a usability test where a number of users got to experience the alternative presentation layer that uses a visualisation technique called tree- map. The results from the test show that the mock-up could be seen as a alternative to the current presentation of results. The mock-up also shows that a future implementation could also include the use of categories and sorting of information in order to provide content with a meaning.
47

Developing an anthropology curriculum for high school: A case study from Durant High School, Hillsborough County, Florida

Bennett, Kory McNeil 01 June 2005 (has links)
It has become increasingly apparent that anthropology has much to offer when it comes to educating our youth. This is true for all grade levels, kindergarten through senior level studies in high school. Here, this idea will be explored further by focusing on the students of Durant High School (DHS) of Plant City, Florida.This project was designed to explore the idea of combining widely accepted pedagogical theories (Gardner 1983, 1993, 1999; Geraci 2000; Silver, Strong and Perini 1997) with anthropological theory and methods in order to devise effective curricula for high school archaeology and other anthropology courses. More essentially, teachers must combine four approaches when designing curricula: multiple intelligences (MI), learning styles(LS), modes of presentation, and the use of ethnographic field methods. Through a combination of MI, LS, available modes of presentation, and ethnographic methods three major goals were accomplished.
48

"Take Another Look At 'Em": Passing Performances of Gender in the Junior-Freshman Weddings of Florida State College for Women, 1909-1925

Jünke, Sarah Lynne 01 January 2011 (has links)
Junior-freshmen weddings were all-female mock weddings that were performed as annual traditions on college campuses throughout the U.S. in the early part of the twentieth-century. In the weddings, college women played both the men's and women's roles, and were joined as husband and wife by their college administration. This thesis focuses on the junior-freshman weddings of Florida State College for Women during the years 1909-1925 and argues that the weddings expressed the conflicted cultural contexts that college women in the Progressive Era confronted, but that, significantly, this expression was done through passing performances of gender. The women's choice of passing performances in the junior-freshman weddings allowed them to appropriate metaphors of masculinity as their own, thereby challenging a dominant gender ideology that limited their roles within society and their relationship with structures of power. In their performances of gender, play is the language they used to express this challenge. Because there were no existing scholarly studies of junior-freshmen weddings, it was necessary to comparatively examine analyses of other types of mock weddings. Through this examination it was possible to elucidate a working definition of what mock weddings are, which helps to understand not only junior-freshmen weddings, but also provides a framework from which to investigate the many other types of mock weddings that are as of yet unstudied.
49

System and Method for Comparison and Training of Mechanical Circulatory Support Devices: A Patient Independent Platform Using the Total Artificial Heart and Donovan Mock Circulation System

DeCook, Katrina Jolene January 2015 (has links)
Mechanical circulatory support (MCS) is a viable therapy for end stage heart failure. However, despite clinical success, the ability to compare MCS devices in vitro and perform training scenarios is extremely limited. Comparative studies are limited as different devices cannot be interchanged in a patient due to the surgical nature of implant. Further, training and failure scenarios cannot be performed on patients with devices as this would subject a patient to a failure mode. A need exists for a readily available mock system that can perform comparative testing and training scenarios with MCS devices. Previously, our group has fabricated a well characterized mock circulation system consisting of a SynCardia temporary Total Artificial Heart (TAH) and Donovan Mock Circulation tank (DMC tank). Further, utilizing this system with the TAH operating in reduced output mode, a heart failure model was developed. In the present study, three ventricular assist devices (VADs) were independently attached to the heart failure model to compare device performances over a range of preloads and afterloads. In addition, specific clinical scenarios were created with the system to analyze how VAD-displayed waveforms from the system correlate with clinical scenarios. Finally, each VAD was powered off while attached to the heart failure model to compare fluid flow through the VAD in a pump-failure scenario. We demonstrated that this system can successfully be utilized to compare MCS devices (i.e. ventricular assist devices) and for successful training of patients and clinicians.
50

Design, development and evaluation of centrifugal ventricular assist devices

Timms, Daniel Lee January 2005 (has links)
Heart disease is the developed world's biggest killer, and the shortage of donor hearts has accelerated the development of mechanical alternatives. Scientists, engineers and clinicians have attempted to replicate the human heart with a mechanical device for over 50 years. Although a number of pulsating devices have been developed, and in some cases worked briefly, they have invariably failed to match the success of heart transplantation. In an attempt to produce a suitable alternative, current research is focused on devices that do not replace the heart; but rather work along side it to assist its function. Many of these devices help the failing left ventricle; however some patients require the additional implantation of a second device to assist a failing right ventricle. This increases implantation time and associated risk, and because of the size of the current devices, reduces the access of smaller patients to this vital technology. The overall thesis objective focuses on the progressive design, development and preliminary evaluation of two novel centrifugal type ventricular assist devices, a bi-left ventricular device (Bi-LVAD) and a single bi-ventricular assist device (Bi-VAD). The devices have the respective capability to assist either the left ventricle, or both ventricles of a failing heart. The current concept for each VAD employs both magnetic and hydrodynamic suspension techniques to float a rotating double impeller, a technique that aims to reduce blood damage and component wear, two of the major problems encountered with current generation devices. Each VAD design was developed by conducting experimentation and drawing conclusions from a variety of engineering research fields, such as flow visualization, rotary pump design and testing, fluid dynamics, hemodynamics and heart failure, and magnetic motor bearing design. In order to evaluate pump prototype designs, it was necessary to design and develop a novel pulsatile systemic and pulmonary mock circulation loop capable of reproducing the hemodynamics of heart failure in the systemic and pulmonary circuits. The investigation then specifically examined the static hydraulic forces on the impeller of a centrifugal blood pump during operation in this mock circulation loop. The recorded magnitude and direction of radial and axial thrust then influenced the selection of magnetic and hydrodynamic bearing configurations to minimise impeller touchdown in the intended hemodynamic environment. This research required the development of correctly designed impeller (semi-open/closed) and volute (single, double, circular) components for each ventricular assist application and a unique test facility to isolate impeller hydraulic forces in addition to the mock circulation loop. The proposed Bi-LVAD incorporates symmetrical blade designs on each side of the double sided impeller. The device assists the function of the left ventricle only with symmetrical axial pressure distribution and elimination of stagnant regions beneath the impeller. These features improve axial touchdown capacity and reduce thrombus formation respectively. The proposed Bi-VAD incorporates different blade designs on each side of the double impeller to augment the function of both the left and right cardiac chambers. The design has the additional potential to act as a total artificial heart (TAH). To date there is no Bi-VAD/TAH system available that incorporates an LVAD and RVAD in one rotary pump. Successful development of each innovative VAD will provide an alternative to heart transplantation, potentially saving lives of many terminal heart patients each year. No longer would heart transplant candidates need to wait for the untimely death of a donor to provide a suitable heart. Instead, this new generation device would be available immediately, and be almost universally compatible with all patients. It has the potential to dramatically increase a patient’s expected lifetime, and to deliver them a higher quality of life.

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