Gears are an integral part of devices ranging from simple wrist watches to complex systems like automotive and wave energy converters. They play a very important role in the transfer of torque. There are several types of gears to be chosen from, depending on the application. This thesis work deals exclusively with hypoid gears. A hypoid gear is a type of bevel gear, that transmits torque between two non-parallel shafts. It is similar to a spiral bevel gear, except that the pinion axis can be oset. It is this ability to offset, that renders hypoidgears as highly sought-after gears for automotive applications. It is crucial that these hypoid gears are designed efficiently and that their life before failure is predictable, to a reasonable degree of accuracy. To enable such predictions, this thesis makes an effort to build a finite element (FE) model. With the developed FE model, a study of the effect of press-fit on the ring gear's root bending stresses, that is present in a hypoid gear set of a car's Rear-Drive Unit (RDU), was carried out. The FE model was built on three different software - Transmission 3D (T3D), Hypoid Face Milled (HFM) and MSC Marc (Marc). The effect of press-fit on root bending stresses of the ring gear was first analyzed on T3D. To determine if the press-fit was correctly induced, the model was rebuilt and analyzed on Marc. HFM was used to determine the effect of inclusion of different components on the root bending stresses. Additionally,the HFM model was also replicated on Marc and a press-fit of 100m was induced. This was done to see if modelling the press-fit on HFM gave similar results to that of T3D and if using HFM in conjunction with Marclead to a better modelling procedure. It was found that the maximum root bending stresses increased linearly with increasing press-fit dimension. It was also found that the inclusion of different parts does not cause a significant increase in root bending stresses, except for the inclusion of differential cage. The effect of press-fit could not be quantified despite knowing that it affects the root bending stresses. When the same analysis done on HFM or T3D was done on Marc, there wasa 10% increase in stresses at highly stressed zone in Marc model of T3D; there was 10-15% increase in stresse sat highly stressed zone in the HFM model of Marc. Hence, quantification remained an impediment. It was not possible to quantify the error that occurred during the migration of analysis from HFM or T3D to Marc. However, potential causes of these errors could be the error in computation of bearing forces and difference in the definition of contacts in the software. Owing to large computational time and limited working period, all the analysis on Marc was carried out for one position and for the first time step of the gear mesh. If the errors in migration of analysis from one software to another could be quantified, then this modelling can be used to estimate the contribution of press-fit to rootbending stresses on the ring-gear. Although the contact pattern comparison between the virtual models andthe physical test suggests that HFM is a more trustworthy software, it is recommended to conduct some straingauge measurements on different ring gear teeth and then compare the results with those of the virtual model. / Kugghjul är en integrerad del av utrustningar som sträcker sig fråan enkla armbandsur till komplexa system som bilar eller vågfrakftverkomvandlare. De spelar en mycket viktig roll vid överföring av vridmoment. Det finns flera typer av kugghjul som man kan välja från, beroende på applikationen. Detta projekt handlar exklusivt om hypoidväaxlar. En hypoidväxel är en typ av vinkelväxel som överför vridmoment mellan två icke parallella axlar. Det liknar ett spiralformat växel, förutom att kugghjulets axel kan förskjutas. Det är denna förmåga att kompensera, vilket gör hypoidväxlar en mycket eftertraktade redskap för fordonsapplikationer. Det är avgörande att dessa hypoid-redskap är konstrueras effektivt och att deras liv före misslyckande ar förutsägbart, i en rimlig grad av noggrannhet. För att möjliggöra sådana Förutsägelser gör denna avhandling ett försök att bygga en finita-element (FE) modell. Med den utvecklade FE-modellen utfördes en studie av effekten av presspassning pa ringvaxelns rotböjspänningar, som finns i en hypoid växelsats av en bilens Bakre enhet (RDU). FE-modellen byggdes på tre olika programvaror: Transmission 3D (T3D), Hypoid Face Milled (HFM) och MSCMarc (Marc). Effekten av presspassning på riggböjspänningarna hos ringväxeln analyserades först på T3D. För att bestämma om presspassningen var korrekt inducerad, byggdes modellen och analyserades på Marc. HFM användes för att bestämma effekten av inkludering av olika komponenter på rotböjspänningarna. Dessutom replikerades HFM-modellen också på Marc och en presspassning på 100 microns inducerades. Detta gjordes för att se om modellering av presspass på HFM gav liknande resultat som T3D och om man använde HFM i kombination med Marc leder det till ett bättre modelleringsförfarande. Det visade sig att de maximala rotböjspänningarna ökade linjärt med ökande presspassningsdimension. Det konstaterades ocksåa att införandet av olika delar inte orsakar en signifikant ökning av rotböjspänningar, utom införandet av differentialbur. Effekten av presspassning kunde inte kvantifieras trots att man vet det påverkar rotböjspänningarna. När samma analys gjord på HFM eller T3D gjordes på Marc, fanns det en 10% ökning av späanningar vid starkt stressad zon i Marc-modellen av T3D; det var 10-15% ökning av spänningar vid starkt stressad zon i HFM-modellen av Marc. Därför förblev kvantifiering ett hinder. Det var inte möjligt att kvantifiera felet som inträffade under analysanalysen från HFM eller T3D till Marc. Dock kan potentiella orsaker till dessa fel vara felet vid beräkning av bärkrafter och skillnad i definitionen av kontakter i programvaran. På grund av stor beräkningstid och begränsad arbetstid utfördes all analys på Marc för bara en position och för det forsta steget av växelns nät. Om felen i migration av analys från en programvara till en annan kunde kvantifieras, då kan denna modellering användas för att beräkna bidragen från presspassning till rotböjspänningar på ringväxeln. Även om kontaktmönstersjämforelsen mellan de virtuella modellerna och det fysiska testet föreslår att HFM är en mer pålitlig programvara, rekommenderas det att utföra en viss belastning Mätmätningar på olika ringväxeltänder och sedan jämföra sedan resultaten med dem från virtuella modellen.

The telecom sector contributes to 1.6% of global emissions and is expanding to meet the increasing demand, raising concerns regarding energy consumption and CO2 emissions. This study investigates the potential of Network Function Virtualization (NFV) technology to decrease the operating carbon footprint and additionally aid to reach NetZero goals by 2040. A comparative case study with a network located in an African country evaluated the Mobile Switching Center Server (MSC-S) in a Physical Network Function (PNF) versus NFV deployment. To evaluate the results a Green ICT evaluation framework has been utilized, containing three sections Green ICT Strategy, Green ICT Practice, and Green ICT Measure, and has been adjusted to fit the context of the case. Initial results showed that the MSC-S with the NFV deployment consumes significantly more energy than the previous PNF solution. This was suspected to be a consequence of non-optimized hardware utilization. In a scenario analysis, it was shown that increased hardware efficiency for the NFV technology leads to lower operating energy consumption. However, the derived configurations could potentially lead to redundancy and service issues. The results from both the base case and scenario analysis were further evaluated with the refined framework. A final framework was suggested considering Green ICT Learnings and Contextual factors to facilitate the evaluation and strategy for future Green ICT initiatives. / Telekomsektorn bidrar till 1,6% av de globala koldioxidutsläppen och expanderar för att möta den ökande efterfrågan, vilket bidragit till en större oro kring energiförbrukning och CO2-utsläpp. Denna studie undersöker potentialen hos NFV teknik för att minska det operativa koldioxidavtrycket samt bidra till att uppnå NetZero-målen 2040. I en jämförande fallstudie av ett telekomnätverk i ett afrikanskt land utvärderades en MSC-S applikation i en PNF kontra NFV installation. För att utvärdera resultaten har ett utvärderingsramverk för Grön ICT använts, som innehåller tre delar: Grön ICT-strategi, Grön ICT-praktik och Grön ICT-mått. Vidare har ramverket anpassats för att kunna appliceras på fallstudien. Resultaten från den initiala basfallsstudien visade att MSC-S med NFV-utbyggnaden förbrukar betydligt mer energi än den tidigare PNF-lösningen. Detta misstänktes vara en konsekvens av en icke-optimerad hårdvaruanvändning. I en scenarioanalys visades att ökad hårdvarueffektivitet för NFV-tekniken leder till lägre driftsenergiförbrukning. De föreslagna konfigurationerna, med högre hårdvarueffektivitet, bidrar visserligen till potentiella redundans- och serviceproblem. Resultaten från både basfalls- och scenarioanalysen utvärderades ytterligare med det förfinade ramverket för Grön ICT. Ett slutligt ramverk föreslogs som tog hänsyn till Gröna ICT-lärdommar och kontextuella faktorer. Syftet med det slutgiltiga ramverket är att underlätta utvärdering av strategier för framtida Gröna ICT-initiativ

We show that finite de Finetti-type results may be viewed as results on the approximation of certain continuous functions of a parameter by a sequence of positive operators (Ln) . For distribtions that depend on a finite-dimensional statistic (Tn) only, Ln is the expectation operator of (Tn) under the extremal infinite exchangeable distributions. The rate of approximation of finite exchangeable distributions by mixtures of marginals of infinite exchangeable distributions is the rate of approximation of a single function of the parameter, namely the second indefinite integral of the Fisher information. Our results include a major part of what is known about finite de Finetti theorems. The theory is, however, not only valid for the case when the extremal infinite exchangeable distributions are products of identical distributions. It applies as well to Markov-exchangeable distributions or the linear model. Moreover, the metric is not restricted to the supremum norm. (author's abstract) / Series: Forschungsberichte / Institut für Statistik

The demand for treatment strategies of musculoskeletal tissues is continuously growing, especially considering the increasing number of elderly people with degenerative diseases of the skeletal system. Despite major strides in the field of bone regenerative medicine during the years, current therapies, such as bone grafts, still have several limitations. Multipotent stem cells, such as mesenchymal stem cells (MSCs) are promising candidates for tissue repair because of their differentiation potential and their capacity to undergo extensive replication. However, isolating a homogeneous population of MSCs from multiple sources is an area that needs to be addressed. Also, the knowledge regarding the mechanisms and pathways that lead to the final osteogenic differentiation is still scarce. The following research is a feasibility study on a new isolation technique developed by our lab. The major focus of the research will be the isolation and characterization of mesenchymal stem cells from both adult bone marrow and umbilical cord blood using a novel isolation method based on immunodepletion. Furthermore we will look at the potential of these isolated MSCs to differentiate into mature, bone producing osteoblasts. The results of the studies showed that our novel isolation method allowed proliferation of a homogeneous MSC population. Our irnrnunodepleted MSCs were 99% double positive for antibodies CD44 and CD105 which are highly specific for multipotent MSCs while cells isolated using the plastic adherence method were only 43% double positive for the two MSC-specific markers. Homogeneous MSCs were derived from both adult bone marrow and umbilical cord blood using our isolation method. Utilizing the techniques of confocal microscopy, von Kossa staining, and RTPCR we also show that MSCs, upon stimulation with osteogenic supplements, differentiate into osteoblasts capable of being used for bone tissue engineering applications.

Les patients atteints de cancers reçoivent différents traitement, tels que la radiothérapie ou la chimiothérapie. Actuellement, environ 60% des enfants survivants du cancer développent des effets secondaires cognitifs, consécutifs aux traitements énoncés précédemment. Compte tenu de la perspective du développement psychomoteur de l’enfant et de l’immaturité du système nerveux central (SNC) chez ces patients, il s’avère particulièrement pertinent d’étudier les effets secondaires que provoquent les traitements anticancéreux sur le développement cognitif de cette population de malades. Des études ont démontrées l’existence de liens étroits entre ces effets secondaires et l’abolition de la neurogénèse provoquée principalement par l’irradiation. Ce projet de maîtrise porte sur les effets du facteur de croissance épidermique, l’EGF (un facteur de croissance impliqué dans la prolifération cellulaire) sur la neurogénèse de la souris. Nous avons également cherché un vecteur de sécrétion efficace pour permettre une diffusion continue d’EGF à long terme (2 à 4 semaines). Notre hypothèse est que l’EGF serait capable de stimuler la neurogénèse et protéger les cellules de l’apoptose dans le cerveau de la souris, suite à une irradiation. Nous avons montré un effet positif de l’EGF sur la formation et la prolifération des neuroblastes Dcx(+) dans la zone sous ventriculaire (ZSV) et non dans l’hippocampe (Hi), suite à l’injection de l’EGF, directement dans le cerveau à l’aide d’une pompe osmotique. Nous avons observé que cette augmentation de la quantité de jeunes neurones est indépendante de la capacité de l’EGF à les protéger de l’apoptose. L’EGF ne protège pas non plus les blastes leucémiques, issus de lignées de cellules humaines, des effets secondaires d’une irradiation. Les cellules souches mésenchymateuses (CSM) modifiées génétiquement et générées pour sécréter l’EGF ne montrent aucun effet sur la stimulation de la neurogénèse quand elles sont directement injectées dans le cerveau. Finalement, nos résultats indiquent que l’EGF pourrait être un bon candidat pour le développement de nouvelles thérapies pour traiter les effets secondaires que provoque une irradiation du cerveau. L’utilisation de pompes pour permettre l’administration d’EGF dans le cerveau devient alors très intéressante pour améliorer la qualité de vie des patients. / Patients with cancer receive different treatments such as radiotherapy (ionizing radiation) or chemotherapy. Currently about 60% of children surviving cancer are prone to the development of treatment-related delayed side effects, such as neurocognitive impairments. Given the prospect of psychomotor development of children and central nervous system (CNS) immaturity in these patients, it is especially relevant to study the adverse effects related to cognitive impairment caused by cancer treatments on this population of patients. Studies have shown the existence of close links between this delayed side effects and the abolition of neurogenesis caused mainly by irradiation. This masters degree project concerns the effects of epidermal growth factor, EGF (a growth factor involved in cell proliferation), on neurogenesis in the C57BL/6 mice, which drastically decrease after exposure to ionizing radiation. We also sought a vector of efficient secretion to allow continuous long-term secretion of EGF (2-4 weeks). Our hypothesis is that EGF will stimulate neurogenesis and protect cells from apoptosis in the brain of mice following radiation. We have shown a positive effect of EGF on the formation and proliferation of young neurons Dcx (+) in the subventricular zone (SVZ) but not in the hippocampus (Hi) following EGF injection directly in the brain using an osmotic pump. We also observed that the increase of young neurons is independent of the ability of EGF to protect them from apoptosis. Moreover, EGF doesn’t protect leukemic human blasts after irradiation. Mesenchymal stem cells (MSC) genetically engineered to secrete EGF did not stimulate neurogenesis when injected directly in the brain. Finally our results indicate that EGF could be a good candidate for the development of new therapies to treat the side effects that irradiation causes in the brain. The use of pumps to allow the administration of recombinant EGF in specific brain regions becomes very interesting. Indeed this delivery system is increasingly used and effective to help improve the quality of life of patients.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Multinational companies (MNCs) often choose to locate near other MNCs in order to gain advantages from each other. This is one ingredient in creating a cluster, an area composed of companies, institutions and/or organisations, sharing a similar technology or knowledge base with mutual benefits for the cluster participants. Market forces have created the majority of the clusters in the world. Still, governments frequently aim at creating clusters in order to promote regional development and growth. This is the case with the Multimedia Super Corridor (MSC) in Malaysia that was launched in 1996. My purpose with this thesis is to examine if the creation and running of the MSC has had economical benefits for Malaysia and to examine the MSC’s potential to become profitable and productive. The MSC is a new technological area and it is still under construction. The return on investment seems to be negative and the area is dependent on the Malaysian government for its development. The infrastructure, political and economical factors seem, according to my analysis, to be sufficient for creating the MSC. However, the low level of human resource is a problem for the cluster. Furthermore, Malaysia’s comparative advantage does not seem to be in high-technology production but rather in high-quality manufacturing. Even though the MSC is unlikely to develop into a world leading high-technology cluster, it can help to transfer Malaysia into a new phase of development.

Saab Aerostructures has developed the Crew Entrance Door (CED) for Airbus A400M. Airbus has decided some different load cases for which the Crew Entrance Door must be built to withstand without something breaking down. The door is maneuvered by a mechanical system and the load cases are essential for the sizing of the components in the mechanical system. Saab has previously used MS Excel to analytically calculate resulting forces in the mechanical system due to external and/or internal loads in the different load cases. This report describes how the mechanical system for A400M Crew Entrance Door instead can be modeled and solved numerically with the computer program MSC Adams/View. Creating a model of a mechanical system in MSC Adams/View proved to be easy and fairly quick. The benefit of working with MSC Adams instead of MS Excel is that it is quicker and more user friendly. The major differences when comparing results were believed to be an effect of comparing results from a kinematic model with results from a dynamic model. Therefore it is in the Authors opinion that the analytical method to calculate resulting forces with MS Excel can be replaced by numerical calculations with MSC Adams/View. However, apart from calculating reaction forces there are additional post-simulation calculations for which it is perhaps more beneficial to use MS Excel. To do these post-simulation calculations in MS Excel it is easy to use exported results from MSC Adams. If Saab Aerostructures decide to start working with MSC Adams/View and if Saab wants geometry to be imported to the model, then an advise from the Author is to have a software installed which can convert step-files (*.stp or *.step) to the MSC Adams preferred file format Parasolid (*.xmt_txt or *.x_t). The software should also be able to repair geometry which will greatly increase mass accuracy.

Normally the trucks with four wheel drive option will be running in rear wheel drives and the front wheels will be rotating freely. In extreme tough driving conditions, the risk for getting stopped or slipping the rear wheels in mud is high. When the driver tries to engage the four wheel drive option and due to the difference in relative rotational speed of the dog clutch parts, there is a risk for slipping off or bouncing back of the dog clutch. After studying the importance of gear geometry and a few parameters, the team ended up with a new design and the performance of the design found satisfactory when simulated in MSC ADAMS.

The cycle space of a strongly connected graph has a basis consisting of directed circuits. The concept of relevant circuits is introduced as a generalization of the relevant cycles in undirected graphs. A polynomial time algorithm for the computation of a minimum weight directed circuit basis is outlined. (author's abstract) / Series: Preprint Series / Department of Applied Statistics and Data Processing