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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.
31

Induced deficits in speed perception by transcranial magnetic stimulation of human cortical areas V5/MT+ and V3A

McKeefry, Declan J., Burton, Mark P., Vakrou, Chara, Barrett, Brendan T., Morland, A.B. 02 July 2008 (has links)
No / In this report, we evaluate the role of visual areas responsive to motion in the human brain in the perception of stimulus speed. We first identified and localized V1, V3A, and V5/MT+ in individual participants on the basis of blood oxygenation level-dependent responses obtained in retinotopic mapping experiments and responses to moving gratings. Repetitive transcranial magnetic stimulation (rTMS) was then used to disrupt the normal functioning of the previously localized visual areas in each participant. During the rTMS application, participants were required to perform delayed discrimination of the speed of drifting or spatial frequency of static gratings. The application of rTMS to areas V5/MT and V3A induced a subjective slowing of visual stimuli and ( often) caused increases in speed discrimination thresholds. Deficits in spatial frequency discrimination were not observed for applications of rTMS to V3A or V5/MT+. The induced deficits in speed perception were also specific to the cortical site of TMS delivery. The application of TMS to regions of the cortex adjacent to V5/MT and V3A, as well as to area V1, produced no deficits in speed perception. These results suggest that, in addition to area V5/MT+, V3A plays an important role in a cortical network that underpins the perception of stimulus speed in the human brain. / BBSRC
32

KBE I PRODUKTUTVECKLING PÅ SCANIA : En undersökning av potentialen i CATIA Knowledgeware / KBE IN PRODUCT DEVELOPMENT AT SCANIA : An investigation of the potential in CATIA Knowledgeware

Jonas, Lundin, Mats, Sköldebrand January 2008 (has links)
Övergången från CATIA V4 till CATIA V5 innebär nya möjligheter för konstruktörerna på Scania att arbeta med Knowledge Based Engineering, KBE, för att effektivisera och kvalitets-säkra sitt arbete. Då CATIA V5 är en ny plattform som innehåller verktyg med samlingsnamnet knowledgware, för att bygga in kunskap i modeller ville Scania undersöka potentialen i att arbeta med KBE, och hur detta skulle kunna ske på Scania. Vid traditionell produktutveckling tas en helt ny artikel fram vid behov och ofta innebär detta att arbete som tidigare utförts, görs om igen. Syftet med arbetet är därför att undersöka huruvida KBE i CATIA V5 kan erbjuda möjligheter att återanvända kunskap från tidigare arbete och samtidigt kvalitetssäkra denna, samt utreda vilka knowledgewarelicenser som i så fall kan vara lämpliga för Scania. För att göra detta har en litteraturstudie genomförts för att undersöka vad som har gjorts inom området, och även en intervjustudie har utförts inom R&D på Scania. Vidare har sakkunniga på Linköpings Universitet och Tekniska Högskolan i Jönköping intervjuats. Detta material har sedan sammanställts och analyserats för att sedan resultera i slutsats och rekommendationer. Arbetet har resulterat i en demonstrationsmodell för Scania internt, som baserar sig på den information som framkommit under litteraturstudier och intervjuer. Att arbeta med KBE har både fördelar och nackdelar där den största svårigheten ligger i att bedöma om en artikel lämpar sig för KBE-modellering. Vinsterna med KBE är att stora tidsvinster kan göras och kvalitet kan säkerställas. De mest användbara licenserna för Scanias vidkommande är KWA och PKT, med vilka exempelvis kontroller av standarder och återanvändning av geometrier kan göras. Den slutliga rekommendationen baserat på teori och resultat är att Scania bör överväga att införa KBE som arbetssätt, och därför tillsätta en grupp som fungerar som expertis inom KBE. Denna bör då fungera som support och en resurs vid skapande av KBE-modeller och ansvara för att dessa är korrekta och underhålls. Vidare bör arbete med att definiera fysiska gränssnitt mellan artiklar startas och lämpligtvis då av GEO- eller Layoutgrupperna. / The transition from CATIA V4 to CATIA V5 opens up new possibilities for designers at Scania to work with Knowledge Based Engineering, KBE, in order to increase efficiency and assure quality. As CATIA V5 is a new platform complete with tools, referred to as knowledgeware, for infusing knowledge into models, Scania wanted to investigate the potential of working with KBE, and how this could be used at Scania. In traditional product development a completely new model is produced when needed, and this often entails performing tasks already undertaken and completed. Therefore, the purpose of this thesis is to ascertain whether or not KBE in CATIA V5 can offer the possibility to reuse knowledge from previous work and assuring the quality of this, and if so, determine which knowledgeware licenses would be appropriate for Scania. In order to do this, a literature study was conducted in order to look into what had been done in this field. Also, an interview study was carried out within Scanias R&D department. In addition to this, interviews were held with expertise at Linköping University and Jönköping University. The material was then compiled and analyzed, resulting in conclusions and recommendations. The thesis resulted in a demonstration model for Scania internally, based on the information gathered from literature and interviews. Working with KBE has its pros and cons, the biggest difficulty being to determine whether or not an article is suitable for KBE-modelling. The profits of KBE include quality assurance and sizeable reductions in design time. The most useful knowledgeware licenses for Scania are KWA and PKT, which for example enables users to implement checks for standards and to easily reuse geometry. The final recommendations of this thesis, based on theory and results, is that Scania should consider introducing KBE, and should therefore appoint a group to function as an authority on KBE. This group would provide support and act as a resource in the creation of KBE-models, and also be responsible for the validity and maintenance on these. Furthermore work should begin with defining physical interfaces between articles, preferably by GEO- and Layout groups.
33

Returning culture to peacebuilding : contesting the liberal peace in Sierra Leone

Viktorova Milne, Jevgenia January 2010 (has links)
This thesis investigates the advantages and limitations of applying culture to the analysis of violent conflict and peacebuilding, with a particular focus on liberal peacebuilding in Sierra Leone. While fully aware of the critique of the concept of culture in terms of its uses for the production of difference and ‘otherness,’ it also seeks to respond to the critique of liberal peacebuilding on the account of its low sensitivity towards local culture, which allegedly undermines the peace effort. After a careful examination of the terms of discussion about culture enabled by theoretical approaches to conflict in Chapter 2, the thesis presents a theoretical framework for the analysis of cultural aspects of conflict and peace based on the processes and effects of meaning-generation (Chapter 3), developing the conceptual apparatus and vocabulary for the subsequent empirical study. Instead of bracketing out the recursive nature of cultural theorising, the developed approach embraces the recursive dynamics which arise as a result of cultural ‘embeddedness’ of the analyst and the processes which s/he seeks to elucidate, mirroring similar dynamics in the cultural production of meaning and knowledge. The framework of ‘embedded cultural enquiry’ is then used to analyse the practices of liberal peacebuilding as a particular culture, which shapes the interaction of the liberal peace with its ‘subjects’ and critics as well as framing its reception of the cultural problematic generally (Chapter 4). The application of the analytical framework to the case study investigates the interaction between the liberal peace and ‘local culture,’ offering an alternative reading of the conflict and peace process in Sierra Leone (Chapter 5). The study concludes that a greater attention to cultural meaning-making offers a largely untapped potential for peacebuilding, although any decisions with regard to its deployment will inevitably be made from within an inherently biased cultural perspective.
34

Integrating replication processes with mechanically interlocked molecules

Vidonne, Annick January 2009 (has links)
In the last twenty years, chemists have devised numerous synthetic chemical systems in which self-replication operates, demonstrating that molecules can replicate themselves without the aid of enzymes and that self-replication is not a prerogative of nucleic acids only. However, the coupling of replication to other recognition-mediated events and its exploitation in the amplification of large supramolecular assemblies, such as mechanically interlocked molecules, have remained unexplored areas. Among mechanically interlocked molecules, rotaxanes represent particularly attractive targets because of their application as molecular switches. This thesis describes how the recognition-mediated synthesis of a rotaxane can be combined to the amplification of its structure by replication. Kinetic models for the integration of self-replication with the formation of a rotaxane are presented. The logical steps required to convert these models into molecular structures through consideration of the design criteria highlighted by the models are discussed and executed. The macrocyclic component is an essential part of a rotaxane. The synthesis of several novel macrocycles is presented. Their ability to bind guests in their cavities through hydrogen bonds was probed. The best macrocycle/guest pairs were integrated in the formation of rotaxanes. Further investigations on the stoppering reaction and on the various recognition processes involved in the system lead ultimately to the construction of self-replicating rotaxanes.
35

Étude du rôle des régions variables 4 et 5 dans les changements de conformation de la gp120 du VIH-1

Coutu, Mathieu 02 1900 (has links)
Le VIH infecte les cellules par fusion de sa membrane avec la membrane de la cellule cible. Cette fusion est effectuée par les glycoprotéines de l'enveloppe (Env) qui sont synthétisées en tant que précurseur, gp160, qui est ensuite clivé en gp120 et gp41. La protéine gp41 est la partie transmembranaire du complexe de l'enveloppe et l’ancre à la particule virale alors que la gp120 assure la liaison au récepteur cellulaire CD4 et corécepteur CCR5 ou CXCR4. Ces interactions successives induisent des changements de conformation d’Env qui alimentent le processus d'entrée du virus conduisant finalement à l'insertion du peptide de fusion de la gp41 dans la membrane de la cellule cible. La sous-unité extérieure gp120 contient cinq régions variables (V1 à V5), dont trois (V1, V2 et V3) étant capables d’empêcher l’adoption spontanée de la conformation liée à CD4. Cependant, le rôle de régions variables V4 et V5 vis-à-vis de ces changements de conformation reste inconnu. Pour étudier leur effet, des mutants de l'isolat primaire de clade B YU2, comprenant une délétion de la V5 ou une mutation au niveau de tous les sites potentiels de N-glycosylation de la V4 (PNGS), ont été générés. L'effet des mutations sur la conformation des glycoprotéines d'enveloppe a été analysé par immunoprécipitation et résonance de plasmon de surface avec des anticorps dont la liaison dépend de la conformation adopté par la gp120. Ni le retrait des PNGS de la V4 ni la délétion de V5 n’a affecté les changements conformationnels d’Env tels que mesurés par ces techniques, ce qui suggère que les régions variables V1, V2 et V3 sont les principaux acteurs dans la prévention de l’adoption de la conformation lié de CD4 d’Env. / HIV infects cells by fusing its membrane with the membrane of the target cell. This fusion is performed by the envelope glycoproteins (Env) which are synthesized as a precursor, gp160, which is later cleaved into gp120 and gp41. The transmembrane protein gp41 anchors the envelope complex to the viral particle whereas the gp120 ensures the binding to the cell receptor CD4 and coreceptor CCR5 or CXCR4. These sequential interactions trigger conformational changes on Env that fuel the viral entry process ultimately leading to the insertion of the gp41-derived-fusion peptide into the target cell membrane. The exterior subunit gp120 contains five variable regions (V1 to V5), of which three (V1, V2 and V3) have been shown to restrain the spontaneous sampling of the CD4-bound conformation by gp120. However, the role of variable regions V4 and V5 in these conformational changes remains unknown. To investigate their effect, mutants of the clade B YU2 primary isolate, comprising a deletion of the V5 or mutating all V4 potential N-linked glycosylation sites (PNGS), have been generated. The effect of mutations on the conformation of the envelope glycoproteins was analyzed by immunoprecipitation with conformation-dependent antibodies and surface plasmon resonance. Neither the removal of the V4 PNGS nor the removal of V5 affected Env conformational changes as measured by these techniques. Thus, suggesting that variable regions V1, V2 and V3 are the major players in preventing Env from spontaneously snapping into the CD4-bound conformation.
36

Riktlinjer för effektivisering av arbetet med Simuleringsdriven Konstruktion

Dahlström, Erika, Johansson, Mikael January 2014 (has links)
Då många företag vill skaffa sig marknadsandelar genom att leverera rätt produkt, vid rätt tid och för rätt kostnad har de börjat arbeta med Simuleringsdriven Konstruktion. Simuleringsdriven Konstruktion hjälper dem att genom ett iterativt arbetssätt hitta optimal konstruktion tidigt i NPD-processen och därigenom reducera tid och kostnad för produktutvecklingen. Många företag som sysslar med forskning och utveckling kräver idag mer av provutrustning än tidigare för att kunna kontrollera och möta ökande krav på produkter.  Mer sofistikerad provutrustning behöver utvecklas för att möta ökade krav på produktprov. Krav så som säkerhet, kapacitet, tidseffektivitet, noggrannhet etc. Att även tid och kostnad för utveckling av provutrustning reduceras är viktigt. Detta examensarbete har syftat till att ta fram riktlinjer för effektivisering av arbetet med Simuleringsdriven Konstruktion i utvecklingsprocesser. För att ta fram relevanta riktlinjer har en fallstudie utförts. Fallstudien har bestått av en litteraturstudie samt en empirisk studie hos Scania CV AB i Södertälje. Den empiriska studien har bestått av att optimera en komponent på en befintlig provutrustning med hjälp av Simuleringsdriven Konstruktion på uppdrag av gruppen UTTD på Scania CV AB. Det har i detta examensarbete framkommit att Simuleringsdriven Konstruktion är mycket lämpligt att använda sig utav vid utveckling av provutrustning. Detta då en bättre förståelse kan fås angående hur provet kan utföras och därmed minska överdimensionering och reducera antalet fysiska prov på provutrustningen. Examensarbetet har resulterat i generiska riktlinjer för hur implementering av och arbete med Simuleringsdriven Konstruktion kan utföras i Catia V5 och GAS. Dessa riktlinjer kan användas vid konstruktion av liknande konstruktioner som UTTD arbetar med, det vill säga mekanisk konstruktion av provutrustning.
37

The functional dissection of motion processing pathways in the human visual cortex using fMRI-guided TMS

Strong, Samantha Louise January 2015 (has links)
Motion-selectivity in human visual cortex comprises a number of different cortical loci including V1, V2, V3A, V3B, hV5/MT+ and V6 (Wandell et al., 2007). This thesis sought to investigate the specific functions of V3A and sub-divisions of hV5/MT+ (TO-1 and TO-2) by using transcranial magnetic stimulation (TMS) to transiently disrupt cortical activations within these areas during psychophysical tasks of motion perception. The tasks were chosen to coincide with previous non-human primate and human neuroimaging literature; translational, radial and rotational direction discrimination tasks and identification of the position of a focus of expansion. These results assert that TO-1 and TO-2 are functionally distinct subdivisions of hV5/MT+, as we have shown that both TO-1 and TO-2 are responsible for processing translational motion direction whilst only TO-2 is responsible for processing radial motion direction. In ipsilateral space, it was found that TO-1 and TO-2 both contribute to the processing of ipsilateral translational motion. Taken in a wider context, further results also suggested that these areas may form part of a network of cortical areas contributing to perception of self-motion (heading/egomotion), as TO-2 was not found to be responsible for processing the position of the central focus of expansion (imperative for self-direction). Instead, area V3A has been implicated as functionally responsible for processing this attribute of vision. Overall it is clear that TO-1, TO-2 and V3A have specific, distinct functions that contribute towards both parallel and serial motion processing pathways within the human brain.
38

Automatisierte Ermittlung bauteilspezifischer Kennwerte in komplexen Produktstrukturen zur Abstraktion umfangreicher Gesamtbaugruppen im Textilmaschinenbereich

Kurth, Robin 01 July 2015 (has links)
Steigende Komplexität von Maschinen und Anlagen sowie unternehmensindividuelle Produktstrukturen führen zu Herausforderungen im Handling großer 3D-Modelle in kommerziell verfügbaren CAD-Systemen. Der Vortrag thematisiert die Anwendung unterschiedlicher Automatisierungsmöglichkeiten des CAD-Systems CATIA V5® der Firma Dassault Systèmes. Hierbei wird zum einen auf die besonderen Herausforderungen im Konstruktionsbereich des Textilmaschinenbaus eingegangen. Zum anderen werden Vorschläge für eine parametergesteuerte Anlagenkonzeption auf Basis von Knowledgeware, eine automatisierte Abstraktion großer Baugruppen und für die automatisierte Ermittlung masseabhängiger Parameter komplexer Produkte vorgestellt.
39

Evaluation of parametric CAD models from a manufacturing perspective to aid simulation driven design

Satish Prabhu, Nachiketh, Sarapady, Ranjan Tunga January 2019 (has links)
Scania are known among to be the world’s leading supplier of transport solutions for heavy trucks and buses. Scania’s goal is to develop combustion engines that achieve low-pollutant emissions as well as lower carbon-footprint with higher efficiency. To achieve the above Scania has invested resources in Simulation Driven Design of parametric CAD models which drives design innovation rather than following the design. This enables in creating flexible and robust models in their design process. This master thesis is being conducted in collaboration with Scania exhaust after treatment systems department, focusing on developing a methodology to automatically evaluate the cost and manufacturability of a parametric model, which is intended for an agile working environment with fast iterations within Scania. From the thesis methodology’s data collection process literature study, former thesis work and interviews with designers and cost engineers at Scania, a proposed method is developed that can be implemented during the design process. The method involved four different phase they are Design phase, Analysis phase, Validation phase and Improvement phase. The proposed method is evaluated to check the method feasibility for evaluation on parameteric CAD parts for manufacturability and costing. This proposed method is applied on two different parts of a silencer as part of a case study which is mainly to evaluate the results from Improvement phase. The focus of this thesis is to realise the proposed method through simulation software like sheet metal stamping/forming simulation, cost evaluating tool where the simulation driven design process is achieved. This is done with the help of collaboration between parameteric CAD models and the above simulation software under a common MDO framework through DOE study run or optimisation study runs. The resultant designs is later considered to be improved design in terms of manufacturability and costing.
40

Flood Proof Design of a Train Converter

Rabani, Arya, Balta, Basel, Mesleh, Ammar January 2023 (has links)
The objective of this thesis is to enhance the TC1500 LAB converter, which is anelectrical train converter to be waterproof up to a height of 650 [mm] from raillevel, addressing a pressing need in railway systems. The critical components ofthe converter have been identified for consideration. Using Freddy Olsson'smethod and the concept screening method, various designs were generated, withone alternative design chosen for each critical part identified. The result of thisproject includes innovative designs that fulfill both the company's requirementsand the functional needs identified during the project. Each design's resilienceunder various loads and environmental conditions was assessed using simulationsconducted in SimSolid, all of which successfully met the defined requirements.An actual experiment was done to validate the simulation model used in SimSolid.This work not only advances our understanding of converter design andwaterproofing, but also provides practical solutions for enhancing the durability ofrailway systems. The insights from this thesis serve as valuable resources forfuture research and the improvement of similar components in other railwaysystems.

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