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Att presentera information i virtuell verklighet : En studie om var och hur information bör presenteras i virtuell verklighet vid användning av en fordonssimulator.Boman, Joel, Forsmark, Markus, Schagerström, Waldemar January 2017 (has links)
When talking about how to present information in virtual reality, the possibilities are countless, but there are also many problems surrounding the spatial location of the information. This study aims to examine where and how the instructions in a vehicle training simulator should be presented in a future implementation of the interface in virtual reality. To find this out, a gameplay was created in which four different placements of the instructions were made. Three options were based on earlier studies made by Smith (2015) and Jose (2016) and the fourth was based on the existing information in the vehicle training simulator. These gameplays were presented as a movie to a number of interviewees and followed up by questions after each movie. The interviewees were asked to give the movies three ratings from 1-5, valuing how they perceived the presentation of the instructions. To get further opinions, comments was collected from the interviewees throughout each session. In this two ways, we got answers to which of the four options the interviewees thought was best. The study showed that there were two options that stood out among the others and both were based on the concept of a head-up display, also known as a HUD. One was represented in the bottom of the windshield and the other one in the top. The result of which one of them who were perceived as best is too close to say, although the study is considered to have reached its goal, which was to help the developers on their way to a decision that will eventually be implemented.
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Placement autonomique de machines virtuelles sur un système de stockage hybride dans un cloud IaaS / Autonomic virtual machines placement on hybrid storage system in IaaS cloudOuarnoughi, Hamza 03 July 2017 (has links)
Les opérateurs de cloud IaaS (Infrastructure as a Service) proposent à leurs clients des ressources virtualisées (CPU, stockage et réseau) sous forme de machines virtuelles (VM). L’explosion du marché du cloud les a contraints à optimiser très finement l’utilisation de leurs centres de données afin de proposer des services attractifs à moindre coût. En plus des investissements liés à l’achat des infrastructures et de leur coût d’utilisation, la consommation énergétique apparaît comme un point de dépense important (2% de la consommation mondiale) et en constante augmentation. Sa maîtrise représente pour ces opérateurs un levier très intéressant à exploiter. D’un point de vue technique, le contrôle de la consommation énergétique s’appuie essentiellement sur les méthodes de consolidation. Or la plupart d'entre elles ne prennent en compte que l’utilisation CPU des machines physiques (PM) pour le placement de VM. En effet, des études récentes ont montré que les systèmes de stockage et les E/S disque constituent une part considérable de la consommation énergétique d’un centre de données (entre 14% et 40%). Dans cette thèse nous introduisons un nouveau modèle autonomique d’optimisation de placement de VM inspiré de MAPE-K (Monitor, Analyze, Plan, Execute, Knowledge), et prenant en compte en plus du CPU, les E/S des VM ainsi que les systèmes de stockage associés. Ainsi, notre première contribution est relative au développement d’un outil de trace des E/S de VM multi-niveaux. Les traces collectées alimentent, dans l’étape Analyze, un modèle de coût étendu dont l’originalité consiste à prendre en compte le profil d’accès des VM, les caractéristiques du système de stockage, ainsi que les contraintes économiques de l’environnement cloud. Nous analysons par ailleurs les caractéristiques des deux principales classes de stockage, pour aboutir à un modèle hybride exploitant au mieux les avantages de chacune. En effet, les disques durs magnétiques (HDD) sont des supports de stockage à la fois énergivores et peu performants comparés aux unités de calcul. Néanmoins, leur prix par gigaoctet et leur longévité peuvent jouer en leur faveur. Contrairement aux HDD, les disques SSD à base de mémoire flash sont plus performants et consomment peu d’énergie. Leur prix élevé par gigaoctet et leur courte durée de vie (comparés aux HDD) représentent leurs contraintes majeures. L’étape Plan a donné lieu, d’une part, à une extension de l'outil de simulation CloudSim pour la prise en compte des E/S des VM, du caractère hybride du système de stockage, ainsi que la mise en oeuvre du modèle de coût proposé dans l'étape Analyze. Nous avons proposé d’autre part, plusieurs heuristiques se basant sur notre modèle de coût et que nous avons intégrées dans CloudSim. Nous montrons finalement que notre approche permet d’améliorer d’un facteur trois le coût de placement de VM obtenu par les approches existantes. / IaaS cloud providers offer virtualized resources (CPU, storage, and network) as Virtual Machines(VM). The growth and highly competitive nature of this economy has compelled them to optimize the use of their data centers, in order to offer attractive services at a lower cost. In addition to investments related to infrastructure purchase and cost of use, energy efficiency is a major point of expenditure (2% of world consumption) and is constantly increasing. Its control represents a vital opportunity. From a technical point of view, the control of energy consumption is mainly based on consolidation approaches. These approaches, which exclusively take into account the CPU use of physical machines (PM) for the VM placement, present however many drawbacks. Indeed, recent studies have shown that storage systems and disk I/O represent a significant part of the data center energy consumption (between 14% and 40%).In this thesis we propose a new autonomic model for VM placement optimization based on MAPEK (Monitor, Analyze, Plan, Execute, Knowledge) whereby in addition to CPU, VM I/O and related storage systems are considered. Our first contribution proposes a multilevel VM I/O tracer which overcomes the limitations of existing I/O monitoring tools. In the Analyze step, the collected I/O traces are introduced in a cost model which takes into account the VM I/O profile, the storage system characteristics, and the cloud environment constraints. We also analyze the complementarity between the two main storage classes, resulting in a hybrid storage model exploiting the advantages of each. Indeed, Hard Disk Drives (HDD) represent energy-intensive and inefficient devices compared to compute units. However, their low cost per gigabyte and their long lifetime may constitute positive arguments. Unlike HDD, flash-based Solid-State Disks (SSD) are more efficient and consume less power, but their high cost per gigabyte and their short lifetime (compared to HDD) represent major constraints. The Plan phase has initially resulted in an extension of CloudSim to take into account VM I/O, the hybrid nature of the storage system, as well as the implementation of the previously proposed cost model. Secondly, we proposed several heuristics based on our cost model, integrated and evaluated using CloudSim. Finally, we showed that our contribution improves existing approaches of VM placement optimization by a factor of three.
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Engreppsskördare med Head-Up DisplayJärrendal, Dan, Tinggård Dillekås, Hans January 2007 (has links)
<p>Arbetsbelastningen för föraren i en engreppsskördare är stor. Vid aptering måste föraren fokusera om blicken för att läsa av information från en Head-Down Display (HDD) samtidigt som föraren måste ha kontroll på kranspetsen vilket bidrar till arbetsbelastningen.</p><p>Syftet med projektet var att undersöka om arbetsbelastningen i engreppsskördare reducerades med Head-Up Display (HUD) under aptering. Först testades fyra HUD-gränssnitt i en simulator, därefter omarbetades gränssnitten innan de slutligen testades i en engreppsskördare i fält. En HUD-demonstrator utvecklades för detta ändamål.</p><p>Resultatet visade att arbetsbelastningen samt apteringstiderna minskade i simulatortestet med HUD jämfört med HDD. I fältstudien förblev arbetsbelastningen oförändrad men apteringstiderna minskade.</p><p>Att arbetsbelastningen minskade med HUD jämfört med HDD kan bero på att HUD är bättre än HDD och/eller att konceptens gränssnitt är effektivare att arbeta med än Valmet Maxi gränssnittet.</p><p>En HUD-demonstrator som fungerar under ljusstarka förhållanden och som tål påfrestningarna i en skördare borde utvecklas för vidare tester.</p>
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Pavement Deterioration and PE Pipe Behaviour Resulting from Open-Cut and HDD Pipeline Installation TechniquesAdedapo, Adedamola Adedeji 14 September 2007 (has links)
The damaging impact of continuous utility cuts on flexible pavement performance has been shown to be a major problem for urban roads and pavement mangers due to high reconstruction and maintenance costs. Horizontal Directional Drilling (HDD) is a trenchless construction method that does not require continuous trenching. HDD pipe installation techniques can reduce reinstatement costs, shorten construction periods, and lower social costs due to reduced user traffic delays. In this thesis, a detailed field study and numerical investigations was completed to quantify pavement deterioration and polyethylene (PE) pipe performance when pipelines are installed under flexible pavements using both traditional open-cut and HDD construction methods.
Two 200mm SDR-17 DIPS HDPE pipes were installed 1.5m below a flexible pavement using open-cut and HDD construction technique. A state-of-the-art instrumentation and data acquisition systems were developed to measure HDD drill rig, PE pipes and pavement responses during pipe installations and for a period of about three years afterwards. Field data from (GPR) surveys, falling weight deflectometer (FWD) tests, surface distress surveys, and ground surface elevation survey were used to evaluate pavement deterioration due to the pipeline installations. The mechanisms of ground deformations during HDD and open-cut pipe installation were numerically investigated with FLAC3D, a commercial finite difference program. A hybrid constitutive model consisting of the traditional Duncan-Chang hyperbolic model and Mohr-Coulomb perfectly plastic model was developed and implemented in FLAC3D to simulate the non-linear stress-strain and stress dependent behavior of granular materials.
Field test results show that the HDD installed pipe have significantly lower construction induced strains and ring deflections when compared to the open cut-and-cover installation and the mechanism of pipe deformation differs for the two construction techniques. The two pipes performed satisfactory over the long-term monitoring period as deflections and strain levels were below acceptable limits and there was no apparent deterioration of the pipe.
Pipe deflections resulting from environmental effects (freeze and thaw) were found to be more significant than those due to material creep. Furthermore, the modified Iowa’s and Plastic Pipe Institute’s (PPI) ring deflection equations were found to over estimate pipe deflection for the open-cut and HDD installed pipes by about 114 and 50 percent, respectively.
Results from field tests found that the HDD installation did not results in any observable change in the condition of the pavement structure performance, while the structure and integrity of pavement section in the vicinity of the open-cut was adversely impacted by utility cut excavation. It was determined numerically that when an unsupported excavation is created within a typical flexible pavement structure, distress zones that extend laterally from the face of the excavation to a distance of approximately 80% of the depth of excavation is developed. The results of the analyses suggests that better restoration techniques are required to eliminate the adverse effect caused by the stress relief within the pavement structure during a utility cut. Furthermore, the area of potential pavement deterioration should be extended beyond the edge of the utility cut to encompass the ‘distress zones’ when determining fees to cover pavement damage and restoration costs.
Results obtained from numerical simulations advanced the understanding of the mechanism, magnitude, and extent of deformation within the pavement structure during HDD pipe installation in frictional and cohesive subgrade soils. Relationship between HDD annular bore pressures and displacements have been incorporated into design Charts and Tables for use in estimating maximum allowable bore pressures for HDD installation beneath flexible pavements. Critical bore pressures that would limit ground deformations and prevent excessive pavement deformations are presented. Critical bore pressures were compared to estimated allowable bore pressures obtained from the widely used Delft Geotechnics equation. The Delft Geotechnics equation was found to over estimate allowable bore pressure for HDD installation beneath flexible pavement.
HDD pipeline installations under flexible pavement were found to have significantly lower restoration costs, social costs and maintenance cost than open-cut pipeline installations.
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Engreppsskördare med Head-Up DisplayJärrendal, Dan, Tinggård Dillekås, Hans January 2007 (has links)
Arbetsbelastningen för föraren i en engreppsskördare är stor. Vid aptering måste föraren fokusera om blicken för att läsa av information från en Head-Down Display (HDD) samtidigt som föraren måste ha kontroll på kranspetsen vilket bidrar till arbetsbelastningen. Syftet med projektet var att undersöka om arbetsbelastningen i engreppsskördare reducerades med Head-Up Display (HUD) under aptering. Först testades fyra HUD-gränssnitt i en simulator, därefter omarbetades gränssnitten innan de slutligen testades i en engreppsskördare i fält. En HUD-demonstrator utvecklades för detta ändamål. Resultatet visade att arbetsbelastningen samt apteringstiderna minskade i simulatortestet med HUD jämfört med HDD. I fältstudien förblev arbetsbelastningen oförändrad men apteringstiderna minskade. Att arbetsbelastningen minskade med HUD jämfört med HDD kan bero på att HUD är bättre än HDD och/eller att konceptens gränssnitt är effektivare att arbeta med än Valmet Maxi gränssnittet. En HUD-demonstrator som fungerar under ljusstarka förhållanden och som tål påfrestningarna i en skördare borde utvecklas för vidare tester.
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Pavement Deterioration and PE Pipe Behaviour Resulting from Open-Cut and HDD Pipeline Installation TechniquesAdedapo, Adedamola Adedeji 14 September 2007 (has links)
The damaging impact of continuous utility cuts on flexible pavement performance has been shown to be a major problem for urban roads and pavement mangers due to high reconstruction and maintenance costs. Horizontal Directional Drilling (HDD) is a trenchless construction method that does not require continuous trenching. HDD pipe installation techniques can reduce reinstatement costs, shorten construction periods, and lower social costs due to reduced user traffic delays. In this thesis, a detailed field study and numerical investigations was completed to quantify pavement deterioration and polyethylene (PE) pipe performance when pipelines are installed under flexible pavements using both traditional open-cut and HDD construction methods.
Two 200mm SDR-17 DIPS HDPE pipes were installed 1.5m below a flexible pavement using open-cut and HDD construction technique. A state-of-the-art instrumentation and data acquisition systems were developed to measure HDD drill rig, PE pipes and pavement responses during pipe installations and for a period of about three years afterwards. Field data from (GPR) surveys, falling weight deflectometer (FWD) tests, surface distress surveys, and ground surface elevation survey were used to evaluate pavement deterioration due to the pipeline installations. The mechanisms of ground deformations during HDD and open-cut pipe installation were numerically investigated with FLAC3D, a commercial finite difference program. A hybrid constitutive model consisting of the traditional Duncan-Chang hyperbolic model and Mohr-Coulomb perfectly plastic model was developed and implemented in FLAC3D to simulate the non-linear stress-strain and stress dependent behavior of granular materials.
Field test results show that the HDD installed pipe have significantly lower construction induced strains and ring deflections when compared to the open cut-and-cover installation and the mechanism of pipe deformation differs for the two construction techniques. The two pipes performed satisfactory over the long-term monitoring period as deflections and strain levels were below acceptable limits and there was no apparent deterioration of the pipe.
Pipe deflections resulting from environmental effects (freeze and thaw) were found to be more significant than those due to material creep. Furthermore, the modified Iowa’s and Plastic Pipe Institute’s (PPI) ring deflection equations were found to over estimate pipe deflection for the open-cut and HDD installed pipes by about 114 and 50 percent, respectively.
Results from field tests found that the HDD installation did not results in any observable change in the condition of the pavement structure performance, while the structure and integrity of pavement section in the vicinity of the open-cut was adversely impacted by utility cut excavation. It was determined numerically that when an unsupported excavation is created within a typical flexible pavement structure, distress zones that extend laterally from the face of the excavation to a distance of approximately 80% of the depth of excavation is developed. The results of the analyses suggests that better restoration techniques are required to eliminate the adverse effect caused by the stress relief within the pavement structure during a utility cut. Furthermore, the area of potential pavement deterioration should be extended beyond the edge of the utility cut to encompass the ‘distress zones’ when determining fees to cover pavement damage and restoration costs.
Results obtained from numerical simulations advanced the understanding of the mechanism, magnitude, and extent of deformation within the pavement structure during HDD pipe installation in frictional and cohesive subgrade soils. Relationship between HDD annular bore pressures and displacements have been incorporated into design Charts and Tables for use in estimating maximum allowable bore pressures for HDD installation beneath flexible pavements. Critical bore pressures that would limit ground deformations and prevent excessive pavement deformations are presented. Critical bore pressures were compared to estimated allowable bore pressures obtained from the widely used Delft Geotechnics equation. The Delft Geotechnics equation was found to over estimate allowable bore pressure for HDD installation beneath flexible pavement.
HDD pipeline installations under flexible pavement were found to have significantly lower restoration costs, social costs and maintenance cost than open-cut pipeline installations.
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Atomar aufgelöste Strukturuntersuchungen für das Verständnis der magnetischen Eigenschaften von FePt-HAMR-PrototypmedienWicht, Sebastian 20 December 2016 (has links) (PDF)
Dank der hohen uniaxialen Kristallanisotropie der L10-geordneten Phase gelten nanopartikuläre FePt+C-Schichten als aussichtsreiche Kandidaten zukünftiger Datenspeichersysteme. Aus diesem Grund werden in der vorliegenden Arbeit in Kooperation mit HGST- A Western Digital Company Prototypen solcher Medien strukturell bis hin zu atomarer Auflösung charakterisiert. Anhand von lokalen Messungen der Gitterparameter der FePt-Partikel wird gezeigt, dass die Partikel dünne, zementitartige Verbindungen an ihrer Oberfläche aufweisen. Zusätzlich werden große Partikel mit kleinem Oberfläche-Volumen-Verhältnis von kontinuierlichen Kohlenstoffschichten umschlossen, was die Deposition weiteren Materials verhindert.
Eine Folge davon ist die Entstehung einer zweiten Lage statistisch orientierter Partikel, die sich negativ auf das magnetische Verhalten der FePt-Schicht auswirkt. Weiterhin wird die besondere Bedeutung des eingesetzten Substrats sowie seiner Gitterfehlpassung zur L10-geordneten Einheitszelle nachgewiesen. So lässt sich das Auftreten fehlorientierter ebenso wie das L12-geordneter Kristallite im Fall großer Fehlpassung und einkristalliner Substrate unterdrücken, was andererseits jedoch zu einer stärkeren Verkippung der [001]-Achsen der individuellen FePt-Partikel führt. Abschließend wird mithilfe der Elektronenholographie nachgewiesen, dass die Magnetisierungsrichtungen der FePt-Partikel aufgrund von Anisotropieschwankungen von den [001]-Achsen abweichen können. / Highly textured L10-ordered FePt+C-films are foreseen to become the next generation of magnetic data storage media. Therefore prototypes of such media (provided by HGST- A Western Digital Company) are structurally investigated down to the atomic level by HR-TEM and the observed results are correlated to the magnetic performance of the film. In a first study the occurrence of a strongly disturbed surface layer with a lattice spacing that corresponds to cementite is observed. Furthermore the individual particles are surrounded by a thin carbon layer that suppresses the deposition of further material and leads, therefore, to the formation of a second layer of particles.
Without a contact to the seed layer these particles are randomly oriented and degrade the magnetic performance of the media. A further study reveals, that a selection of single-crystalline substrates with appropriate lattice mismatch to the L10-ordered unit cell can be applied to avoid the formation of in-plane oriented and L12-ordered crystals. Unfortunately, the required large mismatch results in a broadening of the texture of the [001]-axes of the individual grains. As electron holography studies reveal, the orientation of the magnetization of the individual grains can differ from the structural [001]-axis due to local fluctuations of the uniaxial anisotropy.
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Residential Use of Building Integrated Photo VoltaicsBalabadhrapatruni, Aswini 2011 May 1900 (has links)
Building Integrated Photo Voltaics (BIPVs) are devices which are manufactured to replace building components exposed to sufficient sunlight to generate energy. Photo Voltaic Roof tiles are Building Integrated components which can be used instead of traditional roofing materials. The following thesis is focused on comparing traditional, cheaper asphalt roof tiles with Photo Voltaic (PV) roofing tiles in terms of energy cost savings during their respective Net Present Values. The method used for achieving this is computer simulation made possible by software named "Solar Advisory Model" (SAM), developed by National Renewable Energy Laboratories (NREL), to simulate energy output and resultant energy costs saved. The simulations have been run on a prototype example of a model of a dwelling unit's roof area. The simulations have been repeated for 35 cities all over the U.S.A. for 5 different climatic zones on the same prototype example of the dwelling unit. Similarly, the roof area being laid with an array of PV roof tiles has been estimated for coverage by traditional asphalt roof shingles by using data from the RS Means construction costs data. The estimated costs associated with the asphalt roof area have been adjusted to a different set of 35 locations from the 5 climatic zones by using the location factor from RS Means.
A statistical analysis was done to analyze the data, net present value of roofing materials being the dependent variable versus climatic zones and roofing material as the independent variables. The statistical model also included CDD (Cooling Degree Days) and HDD (Heating Degree Days) as co-variates. The results indicate that NPV (Net Present Value) of BIPV roof is significantly different from that of asphalt roof.
Another statistical analysis was done to determine the effect of climatic zones on energy savings due to the use of BIPV roofing. Energy savings (in US$) was used as a dependent variable, and climatic zone as the independent variable. HDD AND CDD were also included in this model as co-variates. The results of this test indicate that both climatic zone and HDD have an effect on total energy savings.
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Atomar aufgelöste Strukturuntersuchungen für das Verständnis der magnetischen Eigenschaften von FePt-HAMR-PrototypmedienWicht, Sebastian 12 December 2016 (has links)
Dank der hohen uniaxialen Kristallanisotropie der L10-geordneten Phase gelten nanopartikuläre FePt+C-Schichten als aussichtsreiche Kandidaten zukünftiger Datenspeichersysteme. Aus diesem Grund werden in der vorliegenden Arbeit in Kooperation mit HGST- A Western Digital Company Prototypen solcher Medien strukturell bis hin zu atomarer Auflösung charakterisiert. Anhand von lokalen Messungen der Gitterparameter der FePt-Partikel wird gezeigt, dass die Partikel dünne, zementitartige Verbindungen an ihrer Oberfläche aufweisen. Zusätzlich werden große Partikel mit kleinem Oberfläche-Volumen-Verhältnis von kontinuierlichen Kohlenstoffschichten umschlossen, was die Deposition weiteren Materials verhindert.
Eine Folge davon ist die Entstehung einer zweiten Lage statistisch orientierter Partikel, die sich negativ auf das magnetische Verhalten der FePt-Schicht auswirkt. Weiterhin wird die besondere Bedeutung des eingesetzten Substrats sowie seiner Gitterfehlpassung zur L10-geordneten Einheitszelle nachgewiesen. So lässt sich das Auftreten fehlorientierter ebenso wie das L12-geordneter Kristallite im Fall großer Fehlpassung und einkristalliner Substrate unterdrücken, was andererseits jedoch zu einer stärkeren Verkippung der [001]-Achsen der individuellen FePt-Partikel führt. Abschließend wird mithilfe der Elektronenholographie nachgewiesen, dass die Magnetisierungsrichtungen der FePt-Partikel aufgrund von Anisotropieschwankungen von den [001]-Achsen abweichen können.:1 Einleitung
2 Grundlagen
2.1 Magnetische Datenspeicherung
2.1.1 Longitudinale magnetische Datenspeicherung (LMR)
2.1.2 Perpendikuläre Medien (PMR)
2.1.3 Thermisch-unterstützte Schreibprozesse (HAMR)
2.2 Das binäre Legierungssystem Eisen-Platin
2.2.1 Die L10-Ordnungsphase
2.2.2 Partikuläre FePt-Schichten
2.3 Strukturelle Besonderheiten nanoskopischer Systeme
2.3.1 Vorzugsorientierungen in polykristallinen Materialien
2.3.2 Einfluss der Substratoberfläche
2.4 Magnetische Eigenschaften
2.4.1 Magnetokristalline Anisotropie
2.4.2 Das Stoner-Wohlfarth-Modell der Eindomänenteilchen
2.4.3 Besonderheiten nanoskopischer FePt-Magnete
2.5 Prinzipien der hochauflösenden Transmissionselektronenmikroskopie
2.5.1 Bild- und Kontrastentstehung
2.5.2 Angewandte Bildgebungsverfahren
2.5.3 Elektronenholographie
3 Experimentelles
3.1 Probenherstellung mittels Kathodenzerstäubung
3.2 Präparation von TEM-Lamellen und VSM-Proben
3.3 Strukturelle Charakterisierung
3.3.1 Klassische und hochaufgelöste Transmissionselektronenmikroskopie
3.3.2 Elektronenenergieverlustspektroskopie (EELS)
3.3.3 Röntgendiffraktometrie (XRD)
3.3.4 Rasterkraftmikroskopie (AFM)
3.4 Vermessung der magnetischen Eigenschaften
3.4.1 Korrektur der Hysteresemessungen
3.4.2 Untersuchung des Wechselwirkungsverhaltens
3.4.3 Bestimmung der Anisotropiefelder
3.4.4 Ermittlung der magnetischen Phasenschiebung mittels Holographie
4 Legierungsbildung und Segregationsphänomene
4.1 Charakterisierung der Platinverteilung
4.2 Untersuchung der Kohlenstoffsegregation
4.3 Einfluss von Kupfer-Additiven
5 Untersuchung des Substrateinflusses
5.1 Einfluss der Gitterfehlpassung zu einkristallinen Substraten
5.2 Vergleich einkristalliner und polykristalliner Substrate
5.3 Einfluss von Substratkorngrenzen
5.4 Auswirkungen der Substratrauheit
6 Magnetische Charakterisierung einzelner FePt Inseln mittels Elektronenholographie
6.1 Experimentelle Bestimmung der magnetischen Phasenschiebung
6.2 Simulation der Phasenkontraste
7 Zusammenfassung / Highly textured L10-ordered FePt+C-films are foreseen to become the next generation of magnetic data storage media. Therefore prototypes of such media (provided by HGST- A Western Digital Company) are structurally investigated down to the atomic level by HR-TEM and the observed results are correlated to the magnetic performance of the film. In a first study the occurrence of a strongly disturbed surface layer with a lattice spacing that corresponds to cementite is observed. Furthermore the individual particles are surrounded by a thin carbon layer that suppresses the deposition of further material and leads, therefore, to the formation of a second layer of particles.
Without a contact to the seed layer these particles are randomly oriented and degrade the magnetic performance of the media. A further study reveals, that a selection of single-crystalline substrates with appropriate lattice mismatch to the L10-ordered unit cell can be applied to avoid the formation of in-plane oriented and L12-ordered crystals. Unfortunately, the required large mismatch results in a broadening of the texture of the [001]-axes of the individual grains. As electron holography studies reveal, the orientation of the magnetization of the individual grains can differ from the structural [001]-axis due to local fluctuations of the uniaxial anisotropy.:1 Einleitung
2 Grundlagen
2.1 Magnetische Datenspeicherung
2.1.1 Longitudinale magnetische Datenspeicherung (LMR)
2.1.2 Perpendikuläre Medien (PMR)
2.1.3 Thermisch-unterstützte Schreibprozesse (HAMR)
2.2 Das binäre Legierungssystem Eisen-Platin
2.2.1 Die L10-Ordnungsphase
2.2.2 Partikuläre FePt-Schichten
2.3 Strukturelle Besonderheiten nanoskopischer Systeme
2.3.1 Vorzugsorientierungen in polykristallinen Materialien
2.3.2 Einfluss der Substratoberfläche
2.4 Magnetische Eigenschaften
2.4.1 Magnetokristalline Anisotropie
2.4.2 Das Stoner-Wohlfarth-Modell der Eindomänenteilchen
2.4.3 Besonderheiten nanoskopischer FePt-Magnete
2.5 Prinzipien der hochauflösenden Transmissionselektronenmikroskopie
2.5.1 Bild- und Kontrastentstehung
2.5.2 Angewandte Bildgebungsverfahren
2.5.3 Elektronenholographie
3 Experimentelles
3.1 Probenherstellung mittels Kathodenzerstäubung
3.2 Präparation von TEM-Lamellen und VSM-Proben
3.3 Strukturelle Charakterisierung
3.3.1 Klassische und hochaufgelöste Transmissionselektronenmikroskopie
3.3.2 Elektronenenergieverlustspektroskopie (EELS)
3.3.3 Röntgendiffraktometrie (XRD)
3.3.4 Rasterkraftmikroskopie (AFM)
3.4 Vermessung der magnetischen Eigenschaften
3.4.1 Korrektur der Hysteresemessungen
3.4.2 Untersuchung des Wechselwirkungsverhaltens
3.4.3 Bestimmung der Anisotropiefelder
3.4.4 Ermittlung der magnetischen Phasenschiebung mittels Holographie
4 Legierungsbildung und Segregationsphänomene
4.1 Charakterisierung der Platinverteilung
4.2 Untersuchung der Kohlenstoffsegregation
4.3 Einfluss von Kupfer-Additiven
5 Untersuchung des Substrateinflusses
5.1 Einfluss der Gitterfehlpassung zu einkristallinen Substraten
5.2 Vergleich einkristalliner und polykristalliner Substrate
5.3 Einfluss von Substratkorngrenzen
5.4 Auswirkungen der Substratrauheit
6 Magnetische Charakterisierung einzelner FePt Inseln mittels Elektronenholographie
6.1 Experimentelle Bestimmung der magnetischen Phasenschiebung
6.2 Simulation der Phasenkontraste
7 Zusammenfassung
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Presentation av taktisk information på bildskärm : Head-Up Display som stöd för tidsstyrd taxning med flygplanEklund, Rikard January 2012 (has links)
No description available.
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