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Il y a seulement une dizaine d’années que l’invariant de la complexité topologique a été défini. Il y a encore beaucoup de travail à y consacrer. Ici nous comparons algébriquement les deux invariants TC(X) et tc(X). En fait, ce qui nous motive, c’est la conjecture de leur égalité. Dans le but d’appuyer cette conjecture, nous regardons les bornes inférieures et supérieures de chacun, pour resserrer l’intervalle dans lequel ils se trouvent. Ceci nous a permis de trouver un nouveau résultat: la borne supérieure 2cat(X) de TC(X) est aussi une borne supérieure de tc(X). Ensuite, pour trois espaces nous avons calculé l’intervalle dans lequel se trouvent TC(X) et tc(X). Tous nos résultats nous incitent à dire que ces deux invariants se comportent bien de la même façon.

This thesis presents a computational study to examine lateral impact behavior of pressurized pipelines and to determine influence of internal pressure on the impact behaviors of pipelines. More than 300 numerical simulations were carried out on mild steel pipe models with different internal pressure levels and were struck at the mid-span and at the one quarter span positions. The computational results for the first time systematically revealed the effects of internal pressure, impact position, and outside diameter on the lateral impact behavior of the pipeline models. It inspects effects of important parameters such as the outside diameter and internal pressure. Quartic polynomial functions are applied to formulate the maximum crushing force (F), permanent displacement (W), and absorbed energy (E) of the pressurized pipelines during the impact problem. Response surfaces are plotted based on the generated quartic polynomial functions and the quality (accuracy) of those functions are verified through several techniques.

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The basis for performing a thermo-mechanical staggered coupled heat source analysis of a welding simulation is implemented into LS-DYNA. In this report, three methods for initiating the heat source’s mechanical motion during girth and tubular joint welding are developed and evaluated. The first method is a reformulation of the equations used at Det Norske Veritas, the second is an incorporation of the equations into excel and the third is a standalone third party software. The most efficient of the developed methods turned out to be the software which creates k-files which are implemented into the main k-file using LS-PrePost. All methods have been visually and numerically evaluated using Excel, LS-DYNA and LS-PrePost.

Orientador: Ronei Jesus Popi / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-10T12:11:57Z (GMT). No. of bitstreams: 1 Maretto_DaniloAlthmann_M.pdf: 2490749 bytes, checksum: 2efe474693fb82f366c9c3c06974de92 (MD5) Previous issue date: 2007 / Resumo: Este trabalho teve como objetivo comparar os métodos lineares de calibração "mínimos quadrados parciais" (PLS) e "padronização direta por partes" (PDS) e um método não-linear "máquina de vetores de suporte por mínimos quadrados" (LS-SVM) na transferência de calibração para modelos de calibração multivariada onde se determinou porcentagem de etanol em cachaça a cinco temperaturas diferentes e para modelos onde se determinou a porcentagem de proteína e gordura em ração para cães em três diferentes granulometrias através de espectroscopia na região do infravermelho próximo. Foram preparadas 50 amostras de cachaça entre 20,86 e 46,48% v/v através de diluição com água Milli-Q ou adição de etanol P.A. (Merck) à cachaça original. A porcentagem alcoólica foi obtida através de um densímetro digital Anton Paar DMA 4500 e os espectros a 5 temperaturas diferentes (15, 20, 25, 30 e 35ºC) foram obtidos na faixa de 850 a 1050 nm em um equipamento Agilent 8453. Um total de 38 amostras de ração moídas foi fornecido pela empresa Nutron Alimentos Ltda a qual realizou testes padrão para determinação de porcentagem de proteína e gordura nas mesmas. As amostras foram então peneiradas, sendo divididas em 3 grupos com tamanhos de partícula diferentes. Os espectros foram obtidos para todos os grupos de partículas de todas as amostras na faixa de 1000 a 2400 nm em um equipamento Varian Cary 5G. Foram feitas quatro propostas diferentes para se fazer a transferência de calibração para cada uma das três aplicações (determinação do teor de etanol em cachaça, e do teor de proteína e gordura em ração). Na grande maioria delas o LS-SVM foi quem apresentou modelos mais bem ajustados / Abstract: The aim of this work was to compare the linear methods of calibration ¿Partial Least Squares¿ (PLS) and ¿Piece-wise Direct Standardization¿ (PDS) and a nonlinear method ¿Least-Squares Support Vector Machines¿ (LS-SVM) on calibration transfer to multivariate calibration models to the determination of alcoholic grade in cachaça in five different temperatures and to determination of protein and fat content in dog food in three different particule sizes by using near infrared spectroscopy. It has been prepared 50 cachaça samples between 20.86 and 46.48% v/v through dilution with Milli-Q water or adding etanol P.A.(Merck) to the original cachaça. The alcoholic grade has been obtained through a Anton Paar DMA 4500 digital densimeter and the spectra in five different temperatures (15, 20, 25, 30 and 35ºC) has been obtained between 850 and 1050 nm in a Agilent 8453 equipament. The 38 grinded dog food samples were supplied by Nutron Alimentos Ltda wich has realized the standard tests to determination of protein and fat mass porcentage in them. The samples have been bolted, been divided in three groups with different particle sizes. The spectra have been obtained to all the particle groups of all samples between 100 and 24000 nm in a Varian Cary 5G equipament. It has been done four different proposals to do the calibration transfer to each one of the three applications (etanol grade in cachaça, and protein and fat in dog food). In the most of them LS-SVM has gotten better adjusted models / Mestrado / Quimica Analitica / Mestre em Química

The idea to use finite element (FE) models to reconstruct accidents for humans is becoming more popular the last years. They represent the human body very accurately and indicate well changes in shape, size and biomechanical properties. FE models are useful when looking at complex factors in the human body in a more systematic way and when the approach is too complicated for conventional setups. Positioned child models from PIPER were used in the process and then rotated in LS-PrePost according to impact points and impact velocities from a given literature data where information from witnessed fall accidents of children was given. The simulations were finally run in LS-Dyna and the purpose was to investigate if the resulting brain injuries were similar to the real life data. From the literature, the falling distance from lowest point of the body to the ground, the age of the child, gender, type of ground and results from CT scans were all known. To compare the results to the literature data, section cuts of the brain were taken at four locations with different time steps. Biomechanical injury predictors such as brain strain, acceleration, rotational angular acceleration and rotational angular velocity were observed and helped with the comparison. In total, 12 cases were reconstructed which ended as 22 simulations. Due to uncertainty regarding the falling height when the children fell from a swing, each swing case had 3 scenarios. Overall the comparison of predicted injury locations from LS-Dyna to real injury locations from CT scans indicated that 7 out of 12 cases compared relatively well. The comparison of a 23-month-old girl to the same case reconsructed with CRABI-18 showed similar outcomes of the angular acceleration and the angular velocity. The linear acceleration and HIC were however much higher with LS-Dyna. Comparison between the swing cases of a 10-, 12- and 13-year-old resulted in similar results for the 12- and 13 year-old girls but the 10 year boy had lower values for all biomechanical parameters except the angular velocity which was a bit higher. With more detailed information about real accidents and precise scaling of PIPER child models, reconstruction with LS-Dyna could be useful in the future to design safer playgrounds for children and to obtain injury criterion for children after fall incidents. / Användande av finita element (FE) modeller för att rekonstruera olyckor har blivit allt populärare de senaste åren. De representerar människokroppen mycket noggrant och indikerar väl förändringari form, storlek och biomekaniska egenskaper. FE-modeller är användbara när man tittar på komplexa faktorer i människokroppen på ett mer systematiskt sätt och när tillvägagångssättet är för komplicerat för konventionella metoder. PIPER barnmodellerna positionerades i enlighet med islagpunkter och islaghastigheter från en given databas där informationen från vittnade fallolyckor av barn gavs. Simuleringarna kördes slutligen i LS-Dyna och syftet var att undersöka om predikteringarna liknade de resulterande hjärnskadorna. Från databasen var fallhöjd från kroppens lägsta punkt till marken, barnets ålder, kön, typ av mark och resultat från CT skanningar kända. För att jämföra resultaten med litteraturdata togs sektionsavsnitt av hjärnan på fyra platser med olika tidspunkter. Biomekaniska skadeprediktorer såsom hjärntöjning, acceleration, vinkelacceleration och vinkelhastighet extraherades och användes i jämförelsen. Totalt, rekonstruerades 12 fallolyckor med totalt 22 simuleringar. På grund av osäkerhet om fallhöjden när barnen föll från en gunga, hade varje fall från gunga 3 scenarier/fallhöjder var. Sammantaget indikerar jämförelsen av förväntade skadepredikteringar från LS-Dyna till observerade skador från CT-skanningar att 7 av 12 fall korrelerade relativt bra. Jämförelsen av en 23 månader gammal tjej i samma fall som tidigare också rekonstruerades med en CRABI-18 docka visade liknande resultat av vinkelaccelerationen och vinkelhastigheten. Linjär acceleration och HIC var emellertid mycket högre med LS-Dyna simuleringarna. Jämförelse mellan fallen från gunga hos en 10-, 12-och 13-åring resulterade i liknande resultat för 12- och 13-åriga flickor, medan 10-åringen hade lägre värden för alla biomekaniska parametrar utom den vinkelhastighet som var lite högre. Med mer detaljerad information om verkliga olyckor och exakt uppskalning av PIPER barnmodeller kan rekonstruktion med LS-Dyna vara användbar i framtiden för att utforma säkrare lekplatser för barn och för att få skadeskala för barn efter fallhändelser.

Die Blechumformungsimulation hat sich in den letzten 25 Jahren stark weiterentwickelt. Die Simulation des gesamten Tiefziehprozesses einschließlich Beschneiden, Bördeln und Rückfedern ist bei den meisten Automobilherstellern und Werkzeugbaubetrieben ein Standardverfahren. Die Verwendung von LS-DYNA, einem der genauesten Löser für die Blechumformung, erfordert noch einiges an Expertenwissen, was die Verwendung für Methodenplaner in ihrer täglichen Arbeit erschwert. Aus diesem Grund hat Ansys eine spezielle Software für die Simulation der Blechumformung entwickelt: „Ansys Forming“. Ansys Forming ist eine benutzerfreundliche GUI zum Aufbau und zur Auswertung einer Blechumformungssimulation ohne Expertenkenntnisse von LS-DYNA.

Sheet metal forming simulation has greatly evolved over the last 25 years. Simulation of the entire deep drawing process including trimming, flanging and springback is a standard procedure at most automotive OEMs and tool shops. Using LS-DYNA, one of the most accurate solvers for sheet metal forming, still needs some expert knowledge, which makes it difficult to use for method engineers in their day-to-day work. Therefore, Ansys has been developing a dedicated application for sheet metal forming simulation, “Ansys Forming”.

Electrical machines form part of our everyday life at home and in industry plants. Currently induction machines are the backbone of the industry machine installation as these are robust, reliable and have relatively high efficiency. However as the price of energy increases and stricter efficiency regulations are put into place there is a need for more efficient electrical machines. The majority of induction machines on Sasol's plants are between 2.2 kW and 22 kW. Of these, 95% machines are connected to pump loads and 2% to fan loads. Thus the majority of the machines operate at a constant speed. Rather than try to improve an induction machine, this project proposes the design for a more efficient LS PMSM that can also be used in the same applications as mentioned above. Although LS PMSMs aren’t a new concept, the demand and industry interest in this technology has increased in recent years. Since 2000 the number of research publications with regards to this machine has increased significantly. The goal of this project is to gain a better understanding of these machines by designing a prototype. The design entitles the stator and rotor. As Sasol provided the funding for the project it was decided to design a three phase, 7.5 kW 525V, four-pole machine. During the design phase several design techniques done by other researchers were incorporated into the prototypes. The design is done with the aid of two FEM software packages namely FEMM and ANSYS Maxwell® and verified against calculated values. The final prototype is tested and compared to the predicted values determined during the design. An industry available LS PMSM from Weg, the WQuattro is also used to compare the results of the prototype. The prototype machine’s no-load, full load and locked rotor behaviour is tested as well as the back-emf waveform. From the results gained the machine is validated. The machine did not perform as predicted and further investigation into the reason is needed. Due to the incorrect wiring of the stator and some other rotor manufacturing issues the prototype cannot be fully validated. However it was found that several of the designed values correlated to the measured values. Further investigation into the under performances as well as more relevant testing and practical manufacturing method is needed. / MIng (Electrical and Electronic Engineering), North-West University, Potchefstroom Campus, 2014