This bachelor thesis has been carried out at GKN Aerospace. GKN is a member of European Space Agency, designing and manufacturing rocket-nozzles for the Ariane rockets. The manufacturing process entails many welds. Weld-simulations have been made to investigate stresses and plastic strains on simplified geometries. Plastic strains have been evaluated parallel and normal to the weld for plate geometries of shell-elements with rectangular cross-section and sandwich-cross-section, using the FEM-program MSC.marc. Results shows that plate width and length have negligible effect on the plastic strains when one weld is made. A comparison between a sandwich-sector cone and a sandwich plate was made, to investigate how plastic strains and stresses were affected of geometry. Plastic strains and stresses parallel the weld are the same. Plastic strains and stresses normal the weld are affected by changing geometry. Studies on differences in stresses between solid and shell elements propose use of solid elements near the weld region, if stresses are of interest.

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第18947号 / 工博第3989号 / 新制||工||1614 / 31898 / 京都大学大学院工学研究科航空宇宙工学専攻 / (主査)教授 泉田 啓, 教授 琵琶 志朗, 教授 西脇 眞二 / 学位規則第4条第1項該当

Glaucoma is a group of diseases that lead to a progressive loss of vision in the majority of the cases due to elevated intraocular pressure (IOP). Glaucoma is the second leading cause of blindness after cataract. According to the National Eye Institute's report, there were almost 2.7 million detected cases in the United States in 2010.Everybody older than 40, African Americans and Hispanics at any age, are at high risk and would need frequent IOP measurement in order to diagnose the disease at an early stage. Majority of the existing tonometers measure the IOP through the cornea and their operation requires clinical professionals. As a result, the measurement has to take place at the doctor's office and requires local anesthesia. This work demonstrates a novel multi-probe tactile-tonometer, which is operated by the patients and measures the IOP through their eyelid. Finite element (FE) models were used to estimate the static, mechanical response of the eye, due to indentation at different IOPs. The models include hyperelastic behavior of the sclera and cornea. The thickness variation of the sclera, throughout the geometry was also considered. Volumetric constraint was applied on the eye cavity, but its actual anatomic structure was neglected. In-vitro indentation tests were performed on enucleated porcine eyeballs, as a proof of concept of tactile-tonometry. Eye/patient specific calibration method was demonstrated, in order to further improve accuracy ("Forward Biomechanics"), and in-vivo estimation of biomechanical properties of the eye ("Inverse Biomechanics"). The method uses simplified FE models and a feed forward artificial neural network (ANN). The tactile-tonometer was implemented for human use, and clinical studies were performed on a small number (10) of human subjects. Based on the measurements from the recruited 10 patients (3 females, 7 males) with a mean age ±SD of 43±19.33 and the measured IOP range of 9.25-21.25mmHg, the novel technique has a mean of differences of ≈ 0mmHg and its 95% limits of agreement are ±4.84mmHg with respect to the Goldmann Applanation Tonometer.

Alla barn har en rättighet att känna sig trygga i skolan och inte bli utsatta för kränkande behandling eller mobbning. Mobbning är ett problem som måste uppmärksammas alltmer eftersom det inte alltid tas på allvar trots att varje skola har någon form av antimobbningsplan. Mobbning kan uttryckas i form av fysisk, psykosocial och verbal mobbning. Vårt syfte med undersökningen är att lyfta fram barns uppfattning om mobbning. Då lyder vår problemformulering som följer: Hur uppfattas mobbning av barn i årskurs fem på sex olika skolor? Vårt intresse ligger i att utföra vår undersökning i årskurs fem på sex olika skolor som aktivt arbetar med olika program mot mobbning. Undersökningen är inte avsedd som en jämförande studie. Vår metod är kvalitativ i form av en helt anonym enkätundersökning med öppna frågor då vi anser att ämnet är alltför känsligt för att använda vid intervjuer. Svaren vi får är inte ämnade att föra statistik utan syftet är att analysera och tolka barnens svar för att skapa en förståelse av deras uppfattning. Vi har valt att i analysen av enkätsvaren använda oss av symbolisk interaktionism, social identitetsteori, rollteori och aggression som gruppfenomen.

No description available.

The Thirteenth East Asia-Pacific Conference on Structural Engineering and Construction, September 11-13, 2013, Sapporo, Japan (EASEC-13)

Biomedical image processing is a very important research area. Image analysis is one of the most important techniques in studies related to heart functions. The clinical assessment of LV function is very important to evaluate the heart function for patients or suspected heart disease sufferers. 2D echocardiography allows us to study the dynamic analysis of the heart which results in obtaining the quantitative and qualitative analysis of the LV. Cardiac function quantitative analysis depends on the heart’s shape characteristics like the enclosed area and heart wall thickness. The segmentation of medical images and obtaining the traces of the LV boundaries is an essential procedure to get the quantitative and qualitative analysis. Yet, in clinical procedure, this task depends on manual tracing which is slow, tedious and time consuming job. Hence, automating this clinical procedure during the cardiac cycle is of great importance. The aim of this thesis is to automate the manual process of detecting and tracking the LV boundaries of 2D echocardiographic image sequence. Instead of depending only on the imaging based techniques, the designed and implemented framework utilizes the LV mechanics beside the imaging based techniques. When it comes to information extraction from patterns which have been classified, it has been proved that the different contour detection methods complement each other. As a result, efficient combination of different contour detectors is expected to achieve better contour detection than if only one detector is used. This combination of contour detectors produces incremental gains in overall performance. In the first framework, the detection and tracking are accomplished by employing the extended Kalman filter framework to combine the contours estimated by the biomechanical model and the contours extracted using the deformable models. An alternative framework is used by employing averaging fusion followed by level set method. A gold standard is created from three manual outlines and utilized in the experimental results to evaluate the automated results. The tracking and segmentation of LV during the cardiac cycle was accomplished successfully in all cases. The results showed limits of agreement for an average perpendicular distance of 1.277 ±0.252 mm versus the created gold standard. This proved that this framework achieved better performance in tracking and segmenting the LV through the cardiac cycle.

Over the last 20 to 30 years, the field of structural fire design has shifted from relying on single element fire resistance testing to the consideration of the effects of full-frame behaviour. The change has been driven by the desire to build more advanced structures and reduce costs. It has been facilitated in part due to structural testing, and in part due to development of complex modelling techniques. This thesis considers the modelling of concrete structures, and presents new techniques and methodologies for analysing the performance of structures in fire. The first part of this work traces modelling techniques from fundamental constitutive behaviour through to sectional capacity calculation. Load induced thermal strain and constitutive modelling approaches are investigated and their impact on structural behaviour is considered. A new, general, technique for conducting sectional analysis on concrete elements is also created. The method relies on analysis of the sectional tangent stiffness to efficiently calculate the biaxial bending capacity of a concrete section subject to any heating regime. This approach is more accurate and conservative than current methods and has the potential to be used as a design tool. This work develops a series of new approaches for the design of large structures subject to fire. A rational and quantifiable methodology is developed for assessing the performance of a structure when subject to fire; this new approach addresses the mismatch in complexity between current vi modelling techniques and measures of structural performance. It allows a more precise approach to be taken to the definition of failure; and can be easily used to compare the structure’s response to different design fires. Finally, a new technique for the definition of design fires founded on fundamental fire dynamics is presented. The approach challenges the assumptions typically made when applying temperature-time curves and is based around the observed phenomenon of travelling fires. A concrete framed structure is subject to a number of travelling fires and the response is assessed using both conventional techniques and the new, in depth analysis.

In a world where money often is the main controlling factor, everything that can be tends to be more and more optimized. Regarding electrical machines, developers have always had the goal to make them better. The latest trend is to make machines as efficient as possible, which calls for accurate simulation models where different designs can be tested and evaluated. The finite element method is probably the most popular approach since it makes it possible to, in an easy and accurate way, get numerical solutions to a variety of physics problems with complex geometries and non-linear materials. This licentiate thesis includes two different projects in which finite element methods have had a central roll. In the first project, the goal was to develop a simulation model to be able to predict demagnetization of permanent magnets. It is of great importance to be able to predict if a permanent magnet will be demagnetized or not in a certain situation. In the worst case, the permanent magnets will be completely destroyed and the machine will be completely useless. However, it is more probable that the permanent magnets will not be completely destroyed and that the machine still will be functional but not as good as before. In a time where money is more important than ever, the utilization has to be as high as possible. In this study the demagnetization risk for different rotor geometries in a 12 kW direct driven permanent magnet synchronous generator was studied with a proprietary finite element method simulation model. The demagnetization study of the different rotor geometries and magnet grades showed that here is no risk for the permanent magnets in the rotor as it is designed today to be demagnetized. The project also included experimental verification of the simulation model. The simulation model was compared with experiments and the results showed good agreement. The second project treated the redesign of the rotor in the generator previously mentioned. The goal was to redesign the surface mounted NdFeB rotor to use a field concentrating design with ferrite permanent magnets instead. The motivation was that the price on NdFeB magnets has fluctuated a lot the last few years as well as to see if it was physically possible to fit a ferrite rotor in the same space as the NdFeB rotor. A new rotor design with ferrite permanent magnets was presented together with an electromagnetic and a mechanical design.

Slėginiams indams ir įrangai keliami griežti stiprumo ir patikimumo reikalavimai, kurie reglamentuojami tarptautinių ir vietinių standartų. Keičiant slėginio indo eksploatavimo sąlygas ir parametrus, būtina atlikti jo stiprumo įvertinimą. Tiriama talpykla, kurioje numatyta laikyti emulsinį kurą, esant atitinkamo dydžio vidiniam slėgiui. Tyrimas atliekamas naudojant baigtinių elementų metodo programinį paketą SolidWorks Simulation, kuris leidžia modeliuoti talpyklą kevaliniais elementais ir įvertinti skirtingų apkrovimo būdų įtaką bendram konstrukcijos įtempių būviui. Tyrimas parodė, kad pavojingiausiose vietose įtempiai neviršija reglamentuojamų leidžiamų įtempių reikšmių ir talpykla yra tinkama, esant naujoms eksploatavimo sąlygoms. / The requirements of strength and reliability for pressure vessel and equipment are defined by international and local standarts and codes. In case of change of working condition and parameters, it is necessary to define the strength of the structure. The vessel under consideration is projected to contain emulsified fuel under internal pressure. The finite element software package SolidWorks Simulation is used for research. It allows to model the pressure vessel by shell elements. The combined classes of stress due to a combination of loads are deffined. The research shows that the stress intensity in the ares of maximum identified stresses does not exceed the allowable stress and the pressure vessel is proper for operation.