Horizontally mounted compressors offer the advantage of reduced height in central air-conditioning units but prove difficult to produce economically due to costs associated with the manufacture of acceptable lubrication systems for the compressors. This study develops an effective, affordable oil pump for use on a horizontal compressor. Concepts are proven through testing of prototype assemblies. Test results drive modifications for future prototypes, and prototypes demonstrating adequate performance are modified for ease of manufacture. Research in this study proves that the most suitable design results from a modification of a rotating vane pump. The pump’s modifications enable it to pump oil in the same direction, regardless of the direction of shaft rotation and to prime itself when totally dry of oil. However, extensive use of horizontal compressors hinges upon the development of a satisfactory suspension system.

The extraordinary properties of the single wall carbon nanotubes (SWCNTs) have stimulated an enormous amount of research towards the realization of SWCNT-based products for different applications ranging form nanocomposites to nanoelectronics. Their high charge mobility, exceedingly good current-carrying capacities and ability to be either semiconducting or metallic render them ideal building blocks for nanoelectronics. For nanoelectronic applications, either individual or parallel aligned SWCNTs are advantageous. Moreover, closely packed arrays of parallel SWCNTs are required in order to sustain the relatively large currents found in high frequency devices. Two key areas still require further development before the realization of large-scale nanoelectronics. They are the reproducible control of the nanotubes spatial position/orientation and chiral management. In terms of nanotube orientation, different techniques have been demonstrated for the fabrication of horizontally aligned SWCNTs with either post synthesis routes (e.g. dielectrophoresis and Langmuir-Blodgett approach) or direct growth (e.g. chemical vapor deposition (CVD)). The low temperature of the production process, allowing the formation of aligned nanotubes on pretty much any substrate, is the main advantage of the post synthesis routes, while the poor levels of reproducibility and spatial control, and the limited quality of the aligned tubes due to the inherently required process steps are limitations. The simplicity, up-scalability, along with the reproducible growth of clean high quality SWCNTs with well-controlled spatial, orientation and length, make CVD the most promising for producing dense horizontally well-aligned SWCNTs. These CVD techniques suffer some drawbacks, namely, that because they are synthesized using catalyst particles (metals or non-metals) the catalyst material can contaminate the tubes and affect their intrinsic properties. Thus, the catalyst-free synthesis of aligned SWNT is very desirable. This thesis comprises detailed and systematic experimental investigations in to the fabrication of horizontally aligned SWCNTs using both post growth (Dielectrophoresis) and direct growth (CVD) methods. Both catalyst-assisted and catalyst-free SWCNTs are synthesized by CVD. While metallic nanoparticles nucleate and grow SWCNTs, opened and activated fullerene structures are used for all carbon catalyst-free growth of single wall and double wall carbon nanotubes. The systematic studies allow for a detailed understanding of the growth mechanisms of catalyst and catalyst-free grown SWCNTs to be elucidated. The data significantly advances our understanding of horizontally aligned carbon nanotubes by both post synthesis alignment as well as directly as-synthesized routes. Indeed, the knowledge enables such tubes to be grown in high yield and with a high degree of special control. It is shown, for the first time, how one can grow horizontally aligned carbon nanotubes in crossbar configurations in a single step and with bespoke crossing angles. In addition, the transport properties of the aligned tubes at room temperature are also investigated through the fabrication of devices based on these tubes. / Die außergewöhnlichen Eigenschaften von einwandigen Kohlenstoffnanoröhren (engl. single wall carbon nanotubes, SWCNTs) haben bemerkenswerte Forschungsaktivitäten zur Verwirklichung von auf SWCNTs basierenden Anwendungen für verschiedene Bereiche, die von Nanokompositen bis hin zur Nanoelektronik reichen, stimuliert. Ihre hohe Ladungsträgermobilität und die außerordentlichen hohen Ladungsdichten, die in SWCNTs erreicht werden können sowie ihre Eigenschaft, entweder halbleitend oder metallisch zu sein, machen sie zu idealen Konstituenten von nanoelektronischen Schaltkreisen. Für Anwendungen in der Nanoelektronik sind entweder einzelne oder parallel angeordnete SWCNTs vorteilhaft. Darüber hinaus sind dicht gepackte Anordnungen von SWCNTs erforderlich, um die relativ hohen Ströme in Hochfrequenzbauelementen zu transportieren. Für eine erfolgreiche Realisierung von großskaligen nanoelektronischen Bauteilen, die auf SWCNTs basieren, sind noch zwei enorm wichtige Kernprobleme zu lösen, die weitere Forschungsanstrengungen erfordern: die reproduzierbare und verlässliche Kontrolle der räumlichen Positionierung und Orientierung der Nanoröhren sowie die Kontrolle der Chiralität der einzelnen SWCNTs. Hinsichtlich der Orientierung der Nanoröhren kann die horizontal parallele Ausrichtung von SWCNTs mit verschiedenen Techniken erreicht werden. Diese setzen entweder nach dem eigentlichen Wachstum der Röhren ein (Post-Synthese-Methoden wie z.B. Dielektrophorese oder Langmuir-Blodgett-Techniken) oder erreichen direkt während des Wachstums (z.B. durch Chemical-Vapor-Deposition-Methoden (CVD)) die parallele Anordnung. Durch die niedrigen Prozesstemperaturen, die während des Herstellungsprozesses erforderlich sind, erlauben die nach der eigentlichen Synthese stattfindenden Ausrichtungsmethoden die parallele Anordnung von Nanoröhren auf nahezu jedem Substrat, jedoch stellen die geringe Reproduzierbarkeit dieser Prozesse, die schwierige Kontrollierbarkeit der räumlichen Anordnung und die limitierte Qualität der ausgerichteten Röhren aufgrund der erforderlichen Prozessschritte natürliche Beschränkungen dieser Techniken dar. Die einfache Durchführung und ihre Skalierbarkeit, zusammen mit dem reproduzierbaren Wachstum qualitativ sehr hochwertiger SWCNTs mit hoher Kontrolle von räumlicher Anordnung, Orientierung und Länge machen die CVD-Methode zur erfolgversprechendsten Technik für die Herstellung von dichtgepackten hochparallelen horizontalen Anordnungen von SWCNTs. Diese CVD-Ansätze weisen jedoch auch einige Nachteile auf, die in den bei der Synthese verwendeten Katalysatorpartikeln (metallisch oder nicht-metallisch) begründet liegen, da das Katalysatormaterial die Röhren kontaminieren und dadurch ihre intrinsischen Eigenschaften beeinflussen kann. Daher ist eine katalysatorfreie Synthesemethode für ausgerichtete SWCNTs ein höchst erstrebenswertes Ziel. Die vorliegende Arbeit beschreibt detaillierte und systematische experimentelle Untersuchungen zur Herstellung von horizontalen, parallel ausgerichteten Anordnungen von SWCNTs unter Verwendung von Methoden, die sowohl nach dem eigentlichen Wachstum der Nanoröhren (Dielektrophorese) als auch während des Wachstums ansetzen (CVD). Bei den CVD-Methoden werden sowohl solche, die auf der Verwendung von Katalysatoren basieren, als auch katalysatorfreie Techniken verwendet. Während metallische Nanopartikel den Ausgangspunkt für das Wachstum von SWCNTs darstellen, werden geöffnete und aktivierte Fullerenstrukturen verwendet, um das katalysatorfreie Wachstum von reinen ein- oder mehrwandigen Nanoröhren zu erreichen. Die systematischen Untersuchungen ermöglichen ein tiefgehendes Verständnis der Wachstumsmechanismen von SWCNTs, die unter Verwendung von Katalysatoren oder katalysatorfrei erzeugt synthetisiert wurden. Die erzielten Ergebnisse erhöhen in einem hohen Maß das Verständnis der Herstellung von horizontal parallel angeordneten Nanoröhren, die durch Post-Synthese-Methoden oder direkt während des Wachstumsprozesses ausgerichtet wurden. Die erzielten Einsichten erlauben die Herstellung solcher Strukturen mit hoher Ausbeute und mit einem hohen Maß an räumlicher Kontrolle der Anordnung. Zum ersten Male kann ein Verfahren präsentiert werden, mit dem horizontal parallel angeordnete Nanoröhren in gekreuzten Strukturen mit wohldefinierten Kreuzungswinkeln hergestellt werden können. Zusätzlich werden die Transporteigenschaften von parallel ausgerichteten Nanoröhren bei Raumtemperatur, durch die Herstellung von auf den dargestellten Strukturen basierenden Bauelementen, untersucht.

Live load distribution factors are used to determine the live-load moment for bridge girder design when a two dimensional analysis is conducted. A simple, analysis of bridge superstructures are considered to determine live-load factors that can be used to analyze different types of bridges. The distribution of the live load factors distributes the effect of loads transversely across the width of the bridge superstructure by proportioning the design lanes to individual girders through the distribution factors. This research study consists of the determination of live load distribution factors (LLDFs) in both interior and exterior girders for horizontally curved concrete box girder bridges that have central angles, with one span exceeding 34 degrees. This study has been done based on real geometry of bridges designed by a company for different locations. The goal of using real geometry is to achieve more realistic, accurate, and practical results. Also, in this study, 3-D modeling analyses for different span lengths (80, 90, 100, 115, 120, and 140 ft) have been first conducted for straight bridges, and then the results compared with AASHTO LRFD, 2012 equations. The point of starting with straight bridges analyses is to get an indication and conception about the LLDF obtained from AASHTO LRFD formulas, 2012 to those obtained from finite element analyses for this type of bridge (Concrete Box Girder). After that, the analyses have been done for curved bridges having central angles with one span exceeding 34 degrees. Theses analyses conducted for various span lengths that had already been used for straight bridges (80, 90, 100, 115, 120, and 140 ft) with different central angles (5º, 38º, 45º, 50º, 55º, and 60º). The results of modeling and analyses for straight bridges indicate that the current AASHTO LRFD formulas for box-girder bridges provide a conservative estimate of the design bending moment. For curved bridges, it was observed from a refined analysis that the distribution factor increases as the central angle increases and the current AASHTO LRFD formula is applicable until a central angle of 38º which is a little out of the LRFD`s limits.

Pile foundations are extensively used to support various structures that are constructed in soft/loose soils, where shallow foundations would be considered ineffective due to low bearing capacities and large settlements. The design of these structures to accommodate lateral applied loads in particular, usually imposed by winds, water and earth pressures, has gained popularity over the past few decades. The behaviour of horizontally loaded piled foundations is a complex soil-structure interaction problem and is usually concerned with the relative stiffness between the pile and the surrounding soil, where the relative stiffness is a function of both the stiffness and properties of the pile and the stiffness of the soil. Many design assumptions and methods used for pile foundations are based on the principles observed from metal piles. This raises the question of the validity and accuracy of assumptions and methods for the use of analysing and designing reinforced concrete piles, that exhibits highly non-linear material behaviour and changing pile properties after cracking. Due to the elastic behaviour of metal sections, these methods typically only focus on the soil component of the soil-structure interaction problem, only allowing changes and non-linear behaviour of the soil surrounding the pile to take place upon load application, mostly disregarding the behaviour and response of the pile itself. The main purpose and objective of the study was to determine whether aluminium sections in a centrifuge could be used to realistically and sufficiently accurately model the monotonic and cyclic response of reinforced concrete piles subjected to lateral loading. This was observed though a number of tests conducted in a geotechnical centrifuge on scaled aluminium and reinforced concrete piles, subjected to both monotonic and cyclic loading. After conducting the tests on both the scaled aluminium and reinforced concrete piles in the centrifuge it was concluded that aluminium sections cannot be used to accurately model and predict the lateral behaviour of reinforced concrete piles. Both the scaled aluminium and reinforced concrete piles proved to model the concept of laterally loaded piles quite well regarding bending at low loads. However, even at low lateral loads, the observed response of the scaled reinforced concrete was significantly different than that observed from the scaled aluminium pile. Furthermore, as the magnitude of the applied load and bending increased, the scaled reinforced concrete pile cracked, resulting in non-linear behaviour of the section under loading, which was not the case for the scaled aluminium pile that remained uncracked. This contributed to the difference in behaviour between the piles studied, therefore, the true material behaviour and failure mechanisms involved with reinforced concrete piles were not replicated by using a scaled aluminium pile section. The non-linear behaviour of the scaled reinforced concrete pile after cracking affected both the behaviour of the pile, as well as the response of the soil surrounding the pile, in contrast with the behaviour observed from the scaled aluminium pile. / Dissertation (MEng)--University of Pretoria, 2020. / The Concrete Institute / Concrete Society of Southern Africa / WindAfrica project / Civil Engineering / MEng (Structural Engineering) / Unrestricted

The extraordinary properties of the single wall carbon nanotubes (SWCNTs) have stimulated an enormous amount of research towards the realization of SWCNT-based products for different applications ranging form nanocomposites to nanoelectronics. Their high charge mobility, exceedingly good current-carrying capacities and ability to be either semiconducting or metallic render them ideal building blocks for nanoelectronics. For nanoelectronic applications, either individual or parallel aligned SWCNTs are advantageous. Moreover, closely packed arrays of parallel SWCNTs are required in order to sustain the relatively large currents found in high frequency devices. Two key areas still require further development before the realization of large-scale nanoelectronics. They are the reproducible control of the nanotubes spatial position/orientation and chiral management. In terms of nanotube orientation, different techniques have been demonstrated for the fabrication of horizontally aligned SWCNTs with either post synthesis routes (e.g. dielectrophoresis and Langmuir-Blodgett approach) or direct growth (e.g. chemical vapor deposition (CVD)). The low temperature of the production process, allowing the formation of aligned nanotubes on pretty much any substrate, is the main advantage of the post synthesis routes, while the poor levels of reproducibility and spatial control, and the limited quality of the aligned tubes due to the inherently required process steps are limitations. The simplicity, up-scalability, along with the reproducible growth of clean high quality SWCNTs with well-controlled spatial, orientation and length, make CVD the most promising for producing dense horizontally well-aligned SWCNTs. These CVD techniques suffer some drawbacks, namely, that because they are synthesized using catalyst particles (metals or non-metals) the catalyst material can contaminate the tubes and affect their intrinsic properties. Thus, the catalyst-free synthesis of aligned SWNT is very desirable. This thesis comprises detailed and systematic experimental investigations in to the fabrication of horizontally aligned SWCNTs using both post growth (Dielectrophoresis) and direct growth (CVD) methods. Both catalyst-assisted and catalyst-free SWCNTs are synthesized by CVD. While metallic nanoparticles nucleate and grow SWCNTs, opened and activated fullerene structures are used for all carbon catalyst-free growth of single wall and double wall carbon nanotubes. The systematic studies allow for a detailed understanding of the growth mechanisms of catalyst and catalyst-free grown SWCNTs to be elucidated. The data significantly advances our understanding of horizontally aligned carbon nanotubes by both post synthesis alignment as well as directly as-synthesized routes. Indeed, the knowledge enables such tubes to be grown in high yield and with a high degree of special control. It is shown, for the first time, how one can grow horizontally aligned carbon nanotubes in crossbar configurations in a single step and with bespoke crossing angles. In addition, the transport properties of the aligned tubes at room temperature are also investigated through the fabrication of devices based on these tubes.:Introduction ……………………………………………………………….…………… 11 1 Carbon nanotubes basics ……………………………………………………. 15 1.1 sp2 hybridization …………………………………………………….……… 16 1.2 Graphene basics ………………………………………………………...… 16 1.3 Single wall carbon nanotubes Basics …………………………… 18 1.4 Synthesis of single wall carbon nanotubes ………………… 24 1.4.1 Arc discharge ………………………………………………… 24 1.4.2 Laser ablation ……………………………………………… 24 1.4.3 Chemical vapor deposition …………………………… 25 1.4.4 The as-produced carbon nanotubes …………… 25 1.5 Potential applications of single wall carbon nanotubes 26 1.6 Challenges face single wall carbon nanotubes ………… 27 2 Horizontally aligned single wall carbon nanotubes: a review of fabrication and characterization ………………………………………………… 29 2.1 Introduction …………………………………………...………………………………………… 29 2.2 The requisites of horizontally aligned single wall carbon nanotubes 31 2.3 Characterization of Horizontally aligned single wall carbon nanotubes 32 2.3.1 Electron microscopy …………………………………………………………… 32 2.3.2 Scanning probe microscopy ……………………………………...…………… 34 2.3.3 Spectroscopy ……………………………………………………………………… 35 2.4 Fabrication of horizontally aligned single wall carbon nanotubes ……… 36 2.4.1 Dielectrophoresis (Growth-then-place) …………………….…………… 36 2.4.2 Chemical vapor deposition (Growth-in-place) ………...…………… 40 2.5 Transistor performance from horizontally aligned single wall carbon nanotubes ……… 67 2.5.1 Field effect transistor ……………….…………...………………………….…… 67 2.5.2 Thin film transistor …………………………….…...…………………….……… 68 3 Dielelectrophoretic deposition of single wall carbon nanotubes 69 3.1 Deposition of single wall carbon nanotubes in between metallic electrodes ………………… 69 3.1.1 Dispersion of single wall carbon nanotubes ………………………… 69 3.1.2 Dielectrophoretic alignment of single wall carbon nanotubes 70 3.2 CNTFET topographical characterization …………..………………………..……… 70 3.3 Dielectrophoresis advantages and drawbacks ………………………….....……… 72 4 Growth of catalyst-assisted horizontally aligned single wall carbon nanotubes …..………..... 75 4.1 Experimental procedure ….………………………………………………………...……… 76 4.1.1 ST-cut quartz substrates preparation ……………………….....……… 76 4.1.2 Catalyst solutions preparation ……………………………........……… 76 4.1.3 Growth of single wall carbon nanotubes ……………………………… 77 4.1.4 Single wall carbon nanotubes transfer into silicon substrates 78 4.2 Substrate thermal treatment ………………………………………………..........……… 79 4.3 Formed catalyst nanoparticles ………………………………………………...……… 82 4.4 As-grown single wall carbon nanotubes ………………...……………..…………… 84 4.5 Transferred single wall carbon nanotubes ………………...………….……...…… 91 4.6 Chapter summary ………………………………………………...…………………………… 92 5 Growth of catalyst-free horizontally aligned single wall carbon nanotubes … 93 5.1 Experimental procedure ………………………………………………………………….… 94 5.1.1 Different fullerene-based structure ……………………...……………… 94 5.1.2 Pre-treatment of fullerene structures …………………………...…….. 95 5.1.3 Growth of catalyst-free single wall carbon nanotubes ………… 96 5.2 Different fullerene structures nucleate the growth of single wall carbon nanotubes …… 97 5.3 C60 nucleated aligned single wall carbon nanotubes .……………...………… 98 5.3.1 Orientation of the as-grown nanotubes …………………………..… 98 5.3.2 Yield of the grown nanotubes ……………………………………………… 99 5.3.3 Activated sp2 caps ……………………………………………………...……….… 103 5.3.4 Type of the grown nanotubes …………………………………...………… 106 5.3.5 Growth mechanism of carbon nanotubes nucleated from fullerene … 109 6 Electrical characterization of the aligned single wall carbon nanotubes ……… 113 6.1 Device fabrication …………………………………………………………………..…………… 114 6.1.1 FET fabrication over the dielectrophoretic deposited carbon nanotubes … 114 6.1.2 Fabrication of the CVD grown nanotubes based device …………114 6.2 Electrical characterization of dielectrophoretic deposited single wall carbon nanotubes 115 6.2.1 I-V characteristics of the dielectrophoretic deposited nanotubes 115 6.2.2 Defect detection ………………………………………………………………..…… 117 6.3 Electrical characterization of the CVD grown nanotubes ……………………… 120 6.3.1 IV-Characteristics of the metal-assisted single wall carbon nanotubes ……… 120 6.3.2 Electrical behaviour of the catalyst-free single wall carbon nanotubes …………122 7 Conclusions and outlook ……………..……………………..………………………… 125 Appendix ……..……………………………………..………………………….……………. 129 Bibliography …...…………………………………..………………………….……………. 133 List of figures ….…………………………………..………………………….……………. 143 Glossary …………..…………………………………..………………………….……………. 147 Publications ………………………………………..………………………….……………. 149 Curriculum vitae ……………………………………..………………..…………………. 153 Acknowledgment ……..…………………………………..…..…………………………. 155 Declaration …………………………………………………..…..…………………………. 157 / Die außergewöhnlichen Eigenschaften von einwandigen Kohlenstoffnanoröhren (engl. single wall carbon nanotubes, SWCNTs) haben bemerkenswerte Forschungsaktivitäten zur Verwirklichung von auf SWCNTs basierenden Anwendungen für verschiedene Bereiche, die von Nanokompositen bis hin zur Nanoelektronik reichen, stimuliert. Ihre hohe Ladungsträgermobilität und die außerordentlichen hohen Ladungsdichten, die in SWCNTs erreicht werden können sowie ihre Eigenschaft, entweder halbleitend oder metallisch zu sein, machen sie zu idealen Konstituenten von nanoelektronischen Schaltkreisen. Für Anwendungen in der Nanoelektronik sind entweder einzelne oder parallel angeordnete SWCNTs vorteilhaft. Darüber hinaus sind dicht gepackte Anordnungen von SWCNTs erforderlich, um die relativ hohen Ströme in Hochfrequenzbauelementen zu transportieren. Für eine erfolgreiche Realisierung von großskaligen nanoelektronischen Bauteilen, die auf SWCNTs basieren, sind noch zwei enorm wichtige Kernprobleme zu lösen, die weitere Forschungsanstrengungen erfordern: die reproduzierbare und verlässliche Kontrolle der räumlichen Positionierung und Orientierung der Nanoröhren sowie die Kontrolle der Chiralität der einzelnen SWCNTs. Hinsichtlich der Orientierung der Nanoröhren kann die horizontal parallele Ausrichtung von SWCNTs mit verschiedenen Techniken erreicht werden. Diese setzen entweder nach dem eigentlichen Wachstum der Röhren ein (Post-Synthese-Methoden wie z.B. Dielektrophorese oder Langmuir-Blodgett-Techniken) oder erreichen direkt während des Wachstums (z.B. durch Chemical-Vapor-Deposition-Methoden (CVD)) die parallele Anordnung. Durch die niedrigen Prozesstemperaturen, die während des Herstellungsprozesses erforderlich sind, erlauben die nach der eigentlichen Synthese stattfindenden Ausrichtungsmethoden die parallele Anordnung von Nanoröhren auf nahezu jedem Substrat, jedoch stellen die geringe Reproduzierbarkeit dieser Prozesse, die schwierige Kontrollierbarkeit der räumlichen Anordnung und die limitierte Qualität der ausgerichteten Röhren aufgrund der erforderlichen Prozessschritte natürliche Beschränkungen dieser Techniken dar. Die einfache Durchführung und ihre Skalierbarkeit, zusammen mit dem reproduzierbaren Wachstum qualitativ sehr hochwertiger SWCNTs mit hoher Kontrolle von räumlicher Anordnung, Orientierung und Länge machen die CVD-Methode zur erfolgversprechendsten Technik für die Herstellung von dichtgepackten hochparallelen horizontalen Anordnungen von SWCNTs. Diese CVD-Ansätze weisen jedoch auch einige Nachteile auf, die in den bei der Synthese verwendeten Katalysatorpartikeln (metallisch oder nicht-metallisch) begründet liegen, da das Katalysatormaterial die Röhren kontaminieren und dadurch ihre intrinsischen Eigenschaften beeinflussen kann. Daher ist eine katalysatorfreie Synthesemethode für ausgerichtete SWCNTs ein höchst erstrebenswertes Ziel. Die vorliegende Arbeit beschreibt detaillierte und systematische experimentelle Untersuchungen zur Herstellung von horizontalen, parallel ausgerichteten Anordnungen von SWCNTs unter Verwendung von Methoden, die sowohl nach dem eigentlichen Wachstum der Nanoröhren (Dielektrophorese) als auch während des Wachstums ansetzen (CVD). Bei den CVD-Methoden werden sowohl solche, die auf der Verwendung von Katalysatoren basieren, als auch katalysatorfreie Techniken verwendet. Während metallische Nanopartikel den Ausgangspunkt für das Wachstum von SWCNTs darstellen, werden geöffnete und aktivierte Fullerenstrukturen verwendet, um das katalysatorfreie Wachstum von reinen ein- oder mehrwandigen Nanoröhren zu erreichen. Die systematischen Untersuchungen ermöglichen ein tiefgehendes Verständnis der Wachstumsmechanismen von SWCNTs, die unter Verwendung von Katalysatoren oder katalysatorfrei erzeugt synthetisiert wurden. Die erzielten Ergebnisse erhöhen in einem hohen Maß das Verständnis der Herstellung von horizontal parallel angeordneten Nanoröhren, die durch Post-Synthese-Methoden oder direkt während des Wachstumsprozesses ausgerichtet wurden. Die erzielten Einsichten erlauben die Herstellung solcher Strukturen mit hoher Ausbeute und mit einem hohen Maß an räumlicher Kontrolle der Anordnung. Zum ersten Male kann ein Verfahren präsentiert werden, mit dem horizontal parallel angeordnete Nanoröhren in gekreuzten Strukturen mit wohldefinierten Kreuzungswinkeln hergestellt werden können. Zusätzlich werden die Transporteigenschaften von parallel ausgerichteten Nanoröhren bei Raumtemperatur, durch die Herstellung von auf den dargestellten Strukturen basierenden Bauelementen, untersucht.:Introduction ……………………………………………………………….…………… 11 1 Carbon nanotubes basics ……………………………………………………. 15 1.1 sp2 hybridization …………………………………………………….……… 16 1.2 Graphene basics ………………………………………………………...… 16 1.3 Single wall carbon nanotubes Basics …………………………… 18 1.4 Synthesis of single wall carbon nanotubes ………………… 24 1.4.1 Arc discharge ………………………………………………… 24 1.4.2 Laser ablation ……………………………………………… 24 1.4.3 Chemical vapor deposition …………………………… 25 1.4.4 The as-produced carbon nanotubes …………… 25 1.5 Potential applications of single wall carbon nanotubes 26 1.6 Challenges face single wall carbon nanotubes ………… 27 2 Horizontally aligned single wall carbon nanotubes: a review of fabrication and characterization ………………………………………………… 29 2.1 Introduction …………………………………………...………………………………………… 29 2.2 The requisites of horizontally aligned single wall carbon nanotubes 31 2.3 Characterization of Horizontally aligned single wall carbon nanotubes 32 2.3.1 Electron microscopy …………………………………………………………… 32 2.3.2 Scanning probe microscopy ……………………………………...…………… 34 2.3.3 Spectroscopy ……………………………………………………………………… 35 2.4 Fabrication of horizontally aligned single wall carbon nanotubes ……… 36 2.4.1 Dielectrophoresis (Growth-then-place) …………………….…………… 36 2.4.2 Chemical vapor deposition (Growth-in-place) ………...…………… 40 2.5 Transistor performance from horizontally aligned single wall carbon nanotubes ……… 67 2.5.1 Field effect transistor ……………….…………...………………………….…… 67 2.5.2 Thin film transistor …………………………….…...…………………….……… 68 3 Dielelectrophoretic deposition of single wall carbon nanotubes 69 3.1 Deposition of single wall carbon nanotubes in between metallic electrodes ………………… 69 3.1.1 Dispersion of single wall carbon nanotubes ………………………… 69 3.1.2 Dielectrophoretic alignment of single wall carbon nanotubes 70 3.2 CNTFET topographical characterization …………..………………………..……… 70 3.3 Dielectrophoresis advantages and drawbacks ………………………….....……… 72 4 Growth of catalyst-assisted horizontally aligned single wall carbon nanotubes …..………..... 75 4.1 Experimental procedure ….………………………………………………………...……… 76 4.1.1 ST-cut quartz substrates preparation ……………………….....……… 76 4.1.2 Catalyst solutions preparation ……………………………........……… 76 4.1.3 Growth of single wall carbon nanotubes ……………………………… 77 4.1.4 Single wall carbon nanotubes transfer into silicon substrates 78 4.2 Substrate thermal treatment ………………………………………………..........……… 79 4.3 Formed catalyst nanoparticles ………………………………………………...……… 82 4.4 As-grown single wall carbon nanotubes ………………...……………..…………… 84 4.5 Transferred single wall carbon nanotubes ………………...………….……...…… 91 4.6 Chapter summary ………………………………………………...…………………………… 92 5 Growth of catalyst-free horizontally aligned single wall carbon nanotubes … 93 5.1 Experimental procedure ………………………………………………………………….… 94 5.1.1 Different fullerene-based structure ……………………...……………… 94 5.1.2 Pre-treatment of fullerene structures …………………………...…….. 95 5.1.3 Growth of catalyst-free single wall carbon nanotubes ………… 96 5.2 Different fullerene structures nucleate the growth of single wall carbon nanotubes …… 97 5.3 C60 nucleated aligned single wall carbon nanotubes .……………...………… 98 5.3.1 Orientation of the as-grown nanotubes …………………………..… 98 5.3.2 Yield of the grown nanotubes ……………………………………………… 99 5.3.3 Activated sp2 caps ……………………………………………………...……….… 103 5.3.4 Type of the grown nanotubes …………………………………...………… 106 5.3.5 Growth mechanism of carbon nanotubes nucleated from fullerene … 109 6 Electrical characterization of the aligned single wall carbon nanotubes ……… 113 6.1 Device fabrication …………………………………………………………………..…………… 114 6.1.1 FET fabrication over the dielectrophoretic deposited carbon nanotubes … 114 6.1.2 Fabrication of the CVD grown nanotubes based device …………114 6.2 Electrical characterization of dielectrophoretic deposited single wall carbon nanotubes 115 6.2.1 I-V characteristics of the dielectrophoretic deposited nanotubes 115 6.2.2 Defect detection ………………………………………………………………..…… 117 6.3 Electrical characterization of the CVD grown nanotubes ……………………… 120 6.3.1 IV-Characteristics of the metal-assisted single wall carbon nanotubes ……… 120 6.3.2 Electrical behaviour of the catalyst-free single wall carbon nanotubes …………122 7 Conclusions and outlook ……………..……………………..………………………… 125 Appendix ……..……………………………………..………………………….……………. 129 Bibliography …...…………………………………..………………………….……………. 133 List of figures ….…………………………………..………………………….……………. 143 Glossary …………..…………………………………..………………………….……………. 147 Publications ………………………………………..………………………….……………. 149 Curriculum vitae ……………………………………..………………..…………………. 153 Acknowledgment ……..…………………………………..…..…………………………. 155 Declaration …………………………………………………..…..…………………………. 157

Thesis deals with horizontally curved bridge on the ramp in Brno. Designed structure is continous beam formed by bicameral shape, on which are considered the effects of traffic according to ČSN EN 1991-2. Based on the results of stress the structure is designed.

O objetivo central desta dissertação é apresentar as folheações infinitesimalmente polares, fornecendo uma demonstração para o teorema que as caracteriza. Seguimos a abordagem original encontrada em Lytchak e Thorbergsson [25], de 2010. Diretamente da definição e do teorema principal obtem-se dois exemplos: folheações polares e folheações riemannianas singulares de codimensão 1 ou 2. Dedicamos especial atenção a um terceiro exemplo: folheações sem pontos horizontalmente conjugados. A demonstração deste resultado utiliza resultados obtidos anteriormente pelos mesmos autores em 2007, Lytchak e Thorbergsson [24]. Abordamos também, brevemente, as implicações do teorema caracterizador (que é um resultado local) sobre o quociente global de uma folheação infinitesimalmente polar. Variedades com folheações infinitesimalmente polares podem ser encaradas como um objeto que apresenta aspectos clássicos do teorema do toro maximal para grupos de Lie compactos, em um contexto mais amplo. / The present work aims at introducing infinitesimally polar foliations -- as defined by Lytchak and Thorbergsson [25] -- providing a proof for the classification theorem. Polar foliations and low codimension singular Riemannian foliations are two immediate examples. A third example is given by foliations without horizontally conjugate points. The proof of this assertion relies on previous results established by the same authors in Lytchak and Thorbergsson [24]. The classification theorem for infinitesimally polar foliations is a local result; we also derive from it some global consequences on the quotient space of such foliations. Infinitesimally polar foliations may be regarded as a generalised setting where one can find characteristic features from the maximal torus theorem for compact Lie groups.

O objetivo central desta dissertação é apresentar as folheações infinitesimalmente polares, fornecendo uma demonstração para o teorema que as caracteriza. Seguimos a abordagem original encontrada em Lytchak e Thorbergsson [25], de 2010. Diretamente da definição e do teorema principal obtem-se dois exemplos: folheações polares e folheações riemannianas singulares de codimensão 1 ou 2. Dedicamos especial atenção a um terceiro exemplo: folheações sem pontos horizontalmente conjugados. A demonstração deste resultado utiliza resultados obtidos anteriormente pelos mesmos autores em 2007, Lytchak e Thorbergsson [24]. Abordamos também, brevemente, as implicações do teorema caracterizador (que é um resultado local) sobre o quociente global de uma folheação infinitesimalmente polar. Variedades com folheações infinitesimalmente polares podem ser encaradas como um objeto que apresenta aspectos clássicos do teorema do toro maximal para grupos de Lie compactos, em um contexto mais amplo. / The present work aims at introducing infinitesimally polar foliations -- as defined by Lytchak and Thorbergsson [25] -- providing a proof for the classification theorem. Polar foliations and low codimension singular Riemannian foliations are two immediate examples. A third example is given by foliations without horizontally conjugate points. The proof of this assertion relies on previous results established by the same authors in Lytchak and Thorbergsson [24]. The classification theorem for infinitesimally polar foliations is a local result; we also derive from it some global consequences on the quotient space of such foliations. Infinitesimally polar foliations may be regarded as a generalised setting where one can find characteristic features from the maximal torus theorem for compact Lie groups.