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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.
291

Model based design of an expiratory valve and voice-coil actuator and evaluation of complete expiratory system performance with a PI controller

KIESI, MIKKO, AXELSSON SJÖBLOM, ROBERT January 2016 (has links)
Mechanical ventilators are devices in critical care to assist breathing in case of expiratory dysfunction. The expiratory valve is a critical component to the ventilator as it controls the pressure in the patient’s lungs. The design process of a new expiratory valve assembly is a time consuming one due to the wide range of possible design solutions both the voice-coil actuators and membrane valves typically used in ventilators. This thesis evaluates the possibility of creating and using analytical models for model based development to speed up the early design phases of a expiratory valve assembly. The main components, voice-coil actuator and membrane valve are modelled separately and experimentally verified. A complete expiratory system model and hardware-in-the-loop test setup are constructed in order to explore how well can the dynamic properties and control performance of valve assembly be predicted. Finally various questions in the valve assembly design are explored and a new design is proposed to demonstrate the capabilities of the model based approach. The resulting voice-coil and membrane valve models can be considered accurate enough for fast exploration of the design space, as an error rate below 10% is reached without manual tuning for each design. / Mekaniska ventilatorer är en utrustning inom intensivvården för assisterad andning för patienter med nedsatt andningsförmåga. Utandningsventilen är en kritisk komponent till ventilatorn då den kontrollerar lungtrycket hos patienten. Design processen för en ny utandningsventil är en tidskrävande process mycket på grund av den mängd olika design möjligheter som kan utforskas för både talspole aktuatorn samt membran ventilen som oftast används i ventilatorerna. I detta examensarbete utforskades möjligheterna till att skapa och använda analytiska modeller för modellbaserad utveckling för att accelerera de tidiga design stadierna för en utandningsventil. Huvudkomponenterna, talspole aktuatorn och membran ventilen är modellerade separat och experimentellt verifierade. En fullständig modell för hela utandningssystemet samt en hardware-in-the-loop test plattform är konstruerad för att utforska hur väl de dynamiska egenskaperna samt kontroll prestandan för en utandningsventil kan prediceras. Slutligen utforskas diverse frågor angående ventil designen och en ny design föreslås för att demonstrera möjligheterna med en modellbaserad metod. Den slutliga modellen för både talspole aktuatorn och membran ventilen kan betraktas som tillräcklig precisa för snabb utforskning inom de olika design möjligheterna, då en felprocent under 10% är uppnådd utan manuell finjustering för varje design.
292

Étude de la polycystine-1 délété de son motif coiled-coil sur les mécanismes intracellulaires in vivo

Paul, Marie-Lorna 04 1900 (has links)
La polykystose rénale autosomique dominante (PKRAD) est une maladie génétique rénale qui se manifeste par le développement de kystes au rein. Elle résulte de mutations dans le gène PKD1/polycystine-1 (PC-1), contenant un motif coiled-coil et dans le gène PKD2/PC-2 dont les fonctions restent à élucider. À partir d’un chromosome artificiel bactérien, le gène Pkd1 murin (BAC-Pkd1) a été modifié afin de générer 4 lignées de souris transgéniques délété du motif coiled-coil Pkd1Δcoiled-coil et 3 lignées contrôles Pkd1TAG possédant 1-35 copies du transgène. Ces 2 transgènes ont un profil d’expression identique à l’endogène et le niveau dépend du nombre de copies. Alors que les souris Pkd1TAG développent la PKRAD de sévérité proportionnelle au niveau d’expression, les lignées Pkd1Δcoiled-coil en sont épargnées. Ces résultats démontrent l’importance du motif coiled-coil dans la maladie. Les souris Pkd1Δcoiled-coil croisées par Pkd1-/- (létale à la naissance), Pkd1-/- ; Pkd1Δcoiled-coil survivent après la naissance et permettent d’analyser in vivo les interactions, la signalisation et le rôle physiologique du motif coiled-coil. Ces souris Pkd1-/- ; Pkd1Δcoiled-coil avec une copie du transgène présentent des kystes rénaux et meurent ~2 semaines alors que celles à hautes copies n’ont aucun phénotype comme les Pkd1TAG. Les résultats génétiques et biochimiques démontrent que Pc-1Δcoiled-coil est hypomorphe. Bien que Pc-1Δcoiled-coil subit son clivage autoprotéolytique, l’analyse du transport intracellulaire de Pc1Δcoiled-coil montre un délai de maturation. Alors qu’in vitro le trafic Pc-1/Pc-2 dépend du motif coiled-coil pour leur interaction, in vivo une interaction Pc-1Δcoiled-coil/Pc-2 est détectée, suggérant un site d’interaction distinct. Nos études in vivo démontrent que le motif coiled-coil de Pc-1 joue un rôle clé dans sa maturation et l’existence d’un nouveau partenaire de Pc-1 pour son transport intracellulaire. / Autosomal dominant polycystic kidney disease (ADPKD) is the most prevalent genetic disorder that is characterize by the formation of bilateral renal cysts and leads to kidney failure. It results from mutations in the PKD1/polycystin-1(PC-1) gene, containing a coiled-coil motif, and in the PKD2/PC-2 gene, the functions of which remain to be elucidated. From a bacterial artificial chromosome, the murine Pkd1 gene (Pkd1-BAC) was modified in order to obtain 4 transgenic mouse lines deleted from it coiled-coil motif (Pkd1Δcoiled-coil) and 3 Pkd1TAG control lines possessing 1-35 copies of the transgene. These two transgenes have an expression profile identical to the endogenous gene and their expression depends on the number of copies. While Pkd1TAG mice develop ADPKD with a severity proportional to the level of expression, the Pkd1Δcoiled-coil lines are spared. These results demonstrate the importance of the coiled-coil motif in the disease. Pkd1Δcoiled-coil mice crossed by Pkd1-/- (lethal by birth), Pkd1-/-; Pkd1Δcoiled-coil survive after birth and allow the interactions, signaling and physiological role of the coiled-coil motif to be analyzed in vivo. These Pkd1-/-; Pkd1Δcoiled-coil mice with one copy of the transgene show kidney cysts and die ~ 2-weeks while high-copy ones have no phenotype as opposed to Pkd1-/-; Pkd1TAG who eventually develop cyst after 1 year. The genetic and biochemical results demonstrate that Pc-1Δcoiled-coil is hypomorphic. Although Pc-1Δcoiled-coil undergoes its autoproteolytic cleavage, analysis of the intracellular transport of Pc-1Δcoiled-coil shows a delay in maturation. While Pc-1 and Pc-2 appear to interact in vitro through their coiled-coil motif and co-transport, a Pc-1Δcoiled-coil -Pc-2 interaction is conserved in the kidney, suggesting a distinct mechanism of interactions in vivo. Thus, our results show that the coiled-coil motif of Pc-1 in vivo is involved in the maturation independently of Pc-2, highlighting the existence of a critical partner in intracellular transport.
293

Modelling and design approaches of magnetostrictive actuators

Oscarsson, Mattias January 2007 (has links)
A magnetostrictive material elongates when it is subjected to a magnetic field. This effect can then be used to design powerful actuators. The department of electromagnetic engineering has been working with magnetostricitve material and their applications since the 1980s and is presently engaged in a project focusing on magnetostrictive transducer utilisation for the aeronautic field. The focus of the presented work has been to develop and improve methods and tools supporting the development of magnetostrictive actuators. The axial-radial model was previously developed at the department and is well suited for circular cross sections of magnetostrictive rods. It is, however, common to laminate the magnetostrictive rods resulting in rectangular cross sections. The use of Cauer circuits allows modelling of the shielding effect. This shielding effect results in non-homogenous magnetisation and stress in both rectangular and circular cross sections of the rod. A model based on Cauer circuits, including a hysteresis model based on experimental data, was developed during the project. Furthermore, it is demonstrated how figures of merit and the use of finite element methods can be used to find optimised designs in a systematic and computational efficient way. The modified generalised Fabry factor and the magnetisation inhomogeneity coefficient are two proposed new figures of merit. A Magnetostricitve material is characterised through an experimental procedure. Usually, magnetostrictive material exhibit large hysteresis. An important part of the material characterisation is the post-processing of the measurement data, including a de-hysterisation procedure. In the thesis, a de-hysterisation method which ensures energy consistent data is presented. Energy consistent material data is essential to achieve energy consistent simulations of magnetostrictive systems. It is also demonstrated how the knowledge at the department can be utilised in international projects. In an ongoing project, the department is engaged in two sub tasks. In one of these sub tasks a high torque actuator is to be developed for the helicopter industry. The developed magnetostrictive models are used to perform system simulations of such actuator systems. In the other sub task a device for power harvesting from vibrations is analysed. It has now been shown how to adapt the load impedance in order to extract maximal electric power from the device. / QC 20101115
294

Efficacy of a Multi-Channel Array Coil for Pediatric Cardiac Magnetic Resonance Imaging

Ravi, Anandh January 2008 (has links)
No description available.
295

Livscykelanalys av en härvsats

Brodin, Gustav, Johansson, Klara Mia Johanna January 2022 (has links)
Livscykelanalys (LCA) används för att beräkna produktsystemets potentiella miljöpåverkan och identifiera hotspots i livscykeln. Resultatet kan användas för att tilllämpaåtgärder på produktsystemets hotspots för en minskad potentiell miljöpåverkan. SCC AB är specialiserade på tillverkning av härvsatser, som är en delkomponent ielmotorer och generatorer. En härvsats består av lindningstråd gjord av koppar ochisoleringsmaterial. Syftet med denna studie är att redovisa kvalitativa- och kvantitativadata om härvsatsens potentiella miljöpåverkan under tillverkningen genom att– beräkna potentiell miljöpåverkan från vald härvsats– identifiera var det finns störst potential att göra förbättringar i livscykel– redovisa förbättringar för att minska potentiell miljöpåverkan i livscykeln. Den funktionella enheten (FE) är definierad som nytillverkning av generatorlindning tillrenovering av elektrisk utrustning. I jämförelse med andra härvsatser är den av mellanstorlek ochinte den mest producerade härvtypen på SCC. Den har en märkspänning (Un) på 13,8 kV ochbestår av 100 härvor gjorda av 1650 kg koppar och 230 kg isoleringsmaterial. Resultatet erhålls för miljöpåverkanskategorierna Global uppvärmnings-potential(GUP), försurnings-potential (FP) och abiotisk resursutarmnings-potential (ARP). Global uppvärmning beror främst på smältverket och koppargruvan som står för 43%respektive 38% av det totala bidraget på 9106 kg koldioxidekvivalenter (CO2e). Detär främst smältverket som bidrar till försurning på 63% av det totala bidraget på 279kg svaveldioxidekvivalenter (SO2e). Abiotisk resursutarmning beror till största delenpå koppargruvan som står för 82% av det totala bidraget på 3330 kg kopparekvivalenter (CUe). Förbättringsanalysen är baserad på ett materialflödesbaserat cirkularitetsmått (MEM),vilket beräknas genom att jämföra användning av primär- och sekundär kopparråvarai produktionen. Analysen visar att det finns sekundärproducerad lindningstråd påmarknaden som kan användas i tillverkning och kan beställas till en extra kostnad. Slutsatsen är att sekundärproducerad lindningstråd kan ersätta primärproduceradlindningstråd till en extra ekonomisk kostnad för att tillämpa en open loop mellan SCCAB och smältverket. Det kan bidra till en potentiellt minskad miljöpåverkan och enfrämjad CE. / Lifecycle assessment (LCA) is used to calculate the products potential environmentalimpact and identify hotspots in the life cycle. The result can be used to apply measuresto the product system hotspots for a reduced potential environmental impact. SCC AB specializes in the manufacture of coils, which are a sub-component in electricmotors and generators. A coil set consists of winding wire made of copper and insulating material. The purpose of this study is to present qualitative and quantitativedata on the coil set during production by– calculate the potential environmental impact from the selected coil set– identify the greatest potential to make improvements in the life cycle– report improvements to reduce the potential environmental impact in thelife cycle. The functional unit (FU) is defined as the manufacture of generator coil set for the renovation of electrical equipment. In comparison with other coil set, it is of medium size and not themost produced coil set on SCC. It has a rated voltage (Un) of 13.8 kV and consists of 100 coilsmade of 1650 kg of copper and 230 kg of insulation material. The result is obtained for the environmental impact categories global warming potential (GWP), acidification potential (AP) and abiotic resource depletion potential(ADP). Global warming is mainly due to the copper smelter and the copper mine,which account for 43% and 38%, respectively, of the total contribution of 9106 kgcarbon dioxide equivalents (CO2e). It is mainly the copper smelter that contributesto acidification of 63% of the total contribution of 279 kg sulphur dioxide equivalents(SO2e). Abiotic resource depletion is largely due to the copper mine, which accountsfor 82% of the total contribution of 3330 kg of copper equivalents (CUe). The improvement analysis is based on a material flow circularity measure (MEM),which is calculated by comparing the use of primary and secondary copper materialin the production. The analysis shows that there are secondary-produced wires on themarket thar can be used to produce the coil set. The conclusion is that secondary produced winding wire can replace primary windingwire at an extra financial cost to apply an open loop between SCC AB and the smelter.It can contribute to a potentially reduced environmental impact and a promoted CE.
296

Electromagnetic modellin and testing of a Thomson coil based actuator

Hátsági, Bence January 2017 (has links)
The aim of the present thesis is to improve and optimize a Thomson coil based actuatorfor medium voltage vacuum interrupters. The Thomson coil based actuator’s concept isdiscussed. The thesis presents analytical as well as finite element models of the actuatoralong with a comparison of their results. Several experimental setups have been built forthis degree project and they are described in the thesis. Measurements from these setupsare also compared to simulation results. The thesis concludes by drawing conclusionsfrom the compared results and proposes possible directions for additional work in thenear future. / Målsättningen för denna uppsats är att förbättra och optimera en aktuator för mellanspänningsvakuumbrytare baserad på en Thomsonspole. Aktuatorkonceptet analyserasoch diskuteras. Uppsatsen presenterar analytiska modeller såväl som numeriska modellerför FEM av aktuatorn, samt jämförelser av resultaten från simuleringar gjorda av dessa.Flera experimentuppställningar har byggts under detta examensprojekt och beskrivs idenna uppsatsen. Mätningar från dessa uppställningar jämförs också med resultaten frånsimuleringarna. Uppsatsen drar slutligen slutsatser utifrån resultaten och föreslår möjligavägar för ytterligare arbete på området inom en snar framtid.
297

Coil Sensitivity Estimation and Intensity Normalisation for Magnetic Resonance Imaging / Spolkänslighetsbestämning och intensitetsnormalisering för magnetresonanstomografi

Herterich, Rebecka, Sumarokova, Anna January 2019 (has links)
The quest for improved efficiency in magnetic resonance imaging has motivated the development of strategies like parallel imaging where arrays of multiple receiver coils are operated simultaneously in parallel. The objective of this project was to find an estimation of phased-array coil sensitivity profiles of magnetic resonance images of the human body. These sensitivity maps can then be used to perform an intensity inhomogeneity correction of the images. Through investigative work in Matlab, a script was developed that uses data embedded in raw data from a magnetic resonance scan, to generate coil sensitivities for each voxel of the volume of interest and recalculate them to two-dimensional sensitivity maps of the corresponding diagnostic images. The resulting mapped sensitivity profiles can be used in Sensitivity Encoding where a more exact solution can be obtained using the carefully estimated sensitivity maps of the images. / Inom magnetresonanstomografi eftersträvas förbättrad effektivitet, villket bidragit till utvecklingen av strategier som parallell imaging, där arrayer av flera mottagarspolar andvänds samtidigt. Syftet med detta projekt var att uppskattamottagarspolarnas känslighetskarta för att utnyttja dem till i metoder inom magnetresonansavbildning. Dessa känslighetskartor kan användas för att utföra intensitetsinhomogenitetskorrigering av bilderna. Genom utforskande arbete i Matlab utvecklades ett skript som tillämpar inbyggd rådata, från en magnetiskresonansavbildning för att generera spolens känslighet för varje voxel av volymen och omberäkna dem till tvådimensionella känslighetskartor av motsvarande diagnostiska bilder. De resulterande kartlagda känslighetsprofilerna kan användas i känslighetskodning, där en mer exakt lösning kan erhållas med hjälp av de noggrant uppskattade känslighetskartorna.
298

Durability Analysis of Helical Coil Spring in Vehicle Suspension Systems

Kumar, Dhananjay 11 November 2021 (has links)
The suspension system in vehicles supports the vehicle's road stability and ride quality by scaling down the vibration responses resulting from road surface's roughness. This research focuses on fatigue life analysis of coil spring component. Static linear analysis is conducted on the 3D model of helical coil spring to investigate deformation and stress responses. Modal analysis evaluates the characteristics of vibration, i.e. natural resonance frequencies and corresponding mode shapes. The stress frequency response is generated after performing the harmonic analysis on the spring. Dynamics and performance of spring are analyzed over practical frequency range of 0 Hz to 200 Hz. Fatigue life estimation of vehicle suspension spring is performed using the stress data obtained from frequency response analysis. The stress-life (S-N) approach is utilized for fatigue life assessment of suspension spring. This durability analysis technique can be utilized in the automotive industry to improve reliability of vehicles. The outcome of this research can contribute in analysis and design of modern smart vehicles. / Master of Science / The suspension system in vehicles supports the vehicle's road stability and ride quality by scaling down the vibration responses resulting from road surface's roughness. This research focuses on the fatigue life analysis of suspension spring component. Initial phase of analysis is conducted to investigate the deformation and stress in 3D model of spring. Dynamics and performance of spring are analyzed over applicable frequency range of 0 Hz to 200 Hz. Fatigue life of vehicle suspension spring is evaluated using stress data from frequency response analysis. This durability analysis technique can be utilized in the automotive industry to improve reliability of vehicles. The outcome of this research can contribute in analysis and design of modern smart vehicles.
299

Functional investigation of plant specific long coiled-coil proteins, PAMP INDUCED COILED-COIL (PICC) and PICC-LIKE (PICL) in Arabidopsis thaliana

Venkatakrishnan, Sowmya January 1900 (has links)
No description available.
300

Analýza a návrh vinutí střídavých strojů / Analysis and design of the AC machines winding.

Vorel, Luboš January 2014 (has links)
This diploma thesis is focused on an analysis and design of an AC machines windings. In the theoretical part of the thesis, differences between single-layer and double-layer windings are explained. Next, the properties of a stator winding of synchronous machines are described. Finally, the winding factor is determined by means of a standard calculation method and by means of a new progressive calculation method, too. In the experimental part of this thesis, the stator winding of a high-speed synchronous generator excited by permanent magnets on the rotor is designed. This generator is driven by a steam turbine.

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