Transmission electron microscopy (TEM) is an important tool for the characterization of materials as it can provide clear understanding of the relationship between structure, property and composition of nanomaterials. For this, the in-situ TEM analysis is performed and requires specially manufactured sample holders. In particular, those designed to carry out electrical biasing can be used to understand not just the I-V characteristics but also the failure mechanism, structure-property relationship, Joule heating dynamics, electromigration, field emission properties, etc. at the nanoscale. The platforms holding the sample in most modern in-situ TEM holders rely on an insulating ceramic membrane which needs to be (almost) transparent to the imaging electron beam. Electrodes are defined through lithography and patterned on this membrane. Unfortunately, the presence of this membranes introduces several limitations such as electrostatic charging, reduction of image contrast and poor mechanical stability. To circumvent this issue it is necessary to fabricate a novel type of sample platform which does not rely on the presence of a membrane. In this work, novel membraneless sample-holding platforms were designed and manufactured using advanced microfabrication methods and tools. Besides fitting into an array of analytical tools, the novel platforms (or “chips”) can be subjected to thermal and/or chemical processing without compromising their function or structure. To test these, the electrical response of one-, two- and zero-dimensional nanoparticles were studied. Firstly, we investigated current-induced modifications in silver nanowires and expandable graphite flakes and studied various phenomenon involved. Along with these, corresponding ex-situ studies were also performed. Next, graphene oxide was explored as an alternative support platform for in-situ TEM. We successfully achieved temperature as high as 2000o C by Joule heating of graphene oxide. Furthermore, this graphene oxide platform was used as a heater and chemical processing substrate for investigating thermal stability and synthesis of inorganic nanoparticles, respectively.

The recent revolution in digital design tools is having a sea-change effect on the way buildings are designed. As the design process becomes increasingly automated, the focus of architectural expertise is shifting from the execution of drawings to the parametric definition of space and form. In other words, the architect will define a complex set of rules that, when entered into a program, create a building. This design process, coupled with digital fabrication, allows for control of the final product in ways that were previously impossible for designers. However, there is still much to learn about the ways these new tools can be integrated into the architectural design and construction process, and their effect on that process. This thesis proposes that there are five levels of parametric design, varying in level of integration and complexity. The three most complex and visionary levels of integration were tested in three full-scale design-build projects to explore the ramifications of a computational process on design. A freestanding lamp, a chair for a teacher and a barn for two donkeys were designed using parametric tools at three levels of integration. Throughout each project, particular attention was paid to the steps in the design process, the effect of parametric integration on designer agency, and the role of labor in design and construction.

As the internet-of-things hardware integration continues to develop and the requirements for electronics keep diversifying and expanding, the necessity for specialized properties other than the classical semiconductor performance becomes apparent. The success of emerging semiconductor materials depends on the manufacturability and cost as much as on the properties and performance they offer. Solution-based semiconductors are an emerging concept that offers the advantage of being compatible with large-scale manufacturing techniques and have the potential to yield high-quality electronic devices at a lower cost than currently available solutions. In this work, patterns of high-quality MAPbBr3 perovskite single crystals in specific locations are achieved through the modification of the substrate properties and solvent engineering. The fabrication of the substrates involved modifying the surface adhesion forces through functionalization with self-assembled monolayers and patterning them by photolithography processes. Spin coating and blade coating were used to deposit the perovskite solution on the modified silicon substrates. While single crystal perovskites were obtained with the modification of substrates alone, solvent engineering helped with improving the Marangoni flows in the deposited droplets by increasing the contact angle and lowering the evaporation rate, therefore controlling and improving the shape of the grown perovskite crystals. The methodology is extended to other types of perovskites such as the transparent MAPbCl3 and the lead-free MABi2I9, demonstrating the adaptability of the process. Adapting the process to electrode arrays opened up the path towards the fabrication of optoelectronic devices including photodetectors and field-effect transistors, for which the first iterations are demonstrated. Overall, manufacturing and integration techniques permitting the fabrication of single crystalline devices, such as the method in this thesis work, are fundamental in pushing hybrid perovskites towards commercialization.

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Three-dimensional spheroid arrays represent in vivo activity better than conventional 2D cell culturing. A high-throughput microfluidic chip may be capable of depositing cells into spheroid arrays, but it is difficult to regulate the path of individual cells for deposition. Droplets that encapsulate cells may aid in facilitating cell delivery and deposition in the return bend of a microfluidic chip. In this study, a low-cost method for fabricating polymer-cast microfluidic chips has been developed for rapid device prototyping. Computational fluid dynamic (CFD) simulations were conducted to quantify how a change in geometry or fluid properties affects the dynamics of a droplet. These simulations have shown that the deformation, velocity, and trajectory of a droplet are altered when varying the geometry and fluid properties of a multiphase microfluidic system. This quantitative data will be beneficial for the future design of a microfluidic chip for cell deposition into 3D spheroid arrays.

The hand thinks while it builds. Only by physically grappling with a material does one truly understand what it wants to become. In c o n t e m p o r a r y l a n d s c a p e architecture, there is typically a separation between the act of designing and the act of making, often causing a lack of practical knowledge of the capabilities of materials and their relationship to one another. To construct expressively means to comprehend a material's physical properties and how its process of production is revealed through repetition and exaggeration. This dissertation attempts to explore the pre-fabrication of landscapes through an iterative process of making by hand with the goal of uncovering material properties that would otherwise remain concealed. It starts with a material exploration on a detailed level, after which the resulting artefact is applied in the larger context of Pretoria. In addition, this exploration attempts to add to the very limited body of wor k c on c e r n i ng l an d s c ap e architectural tectonic theories. / Die hand dink wanneer dit bou. Slegs deur fisies met 'n materiaal te wroeg verstaan mens waarlik wat die materiaal wil word. In eietydse landskapargitektuur is daar tipies 'n verdeling tussen die daad van ontwerp en die daad van maak, wat dikwels lei tot 'n gebrek in praktiese kennis oor die geskiktheid van materiale asook hul verhouding tot mekaar. Uitdruklike konstruksie dui op 'n begrip van 'n materiaal se fisiese eienskappe en die tentoonstelling van sy produksieproses deur repetisie en oordrywing. Hierdie skripsie poog om die voorafvervaardiging van landskappe te verken deur die herhalende proses van maak met die hand, met die doel om materiaalseienskappe te ontdek wat andersins geskuil sou bly. Dit begin met 'n materiaalverkenning op 'n detail vlak, waarna die artefak toegepas word in die groter Pretoria konteks. Verder poog hierdie verkenning om by te dra tot die beperkte kennis van tektoniese teorie in landskapargitektuur. / Mini Dissertation (ML (Prof))--University of Pretoria, 2016. / Architecture / ML (Prof) / Unrestricted

Ce travail de thèse est consacré au développement de mécanismes pratiques pour le guidage de chaleur dans des nanostructures de silicium de faible dimension. Les applications vont du domaine de la gestion thermique des circuits intégrés aux technologies et matériaux thermoélectriques émergents à base de Si, dans lesquels le guidage thermique de la chaleur peut jouer un rôle important. L'objectif est d'étudier expérimentalement la faisabilité d'une anisotropie de conductivité thermique (κ) dans le plan, induite artificiellement, des membranes nanostructurées en Si. En combinant la thermométrie Raman, la modélisation optique et la modélisation par éléments finis (FEM), il a été possible de mesurer le gradient thermique, la conductance de la membrane et de déterminer les conductivités thermiques effectives. Cette expérience confirme la possibilité d’induire artificiellement une anisotropie élevée de κ dans des membranes en silicium. Un modèle FEM paramétré conçu à dessein a démontré la mise en œuvre possible des effets anisotropes induits dans le domaine de la gestion thermique des circuits intégrés. / This thesis work is devoted to the development of practical mechanisms for the heat guiding in silicon low-dimensional nanostructures. The motivation comes from both the field of IC thermal management and emerging technology of Si-based thermoelectric devices, where directional heat guiding can play an important role. A series of micrometre-sized thermal characterisation platforms was designed and fabricated. The objective is to study experimentally the feasibility of artificially-induced in-plane anisotropy of effective thermal conductivity (κ) in Si nanopatterned membranes. By the combined use of micro Raman Thermometry, Rigorous Coupled Wave Analysis and Finite Element Modelling (FEM) it was possible to measure the thermal gradient, membrane conductance and determine effective thermal conductivities. This experiment confirms the possibility to induce artificially high anisotropy of κ in Si phononic membranes. Finally, purposefully designed parameterized FEM model demonstrated the possible implementation of the induced anisotropic effects in the area of IC thermal-management.

Frequently, in architecture and in other professions, a results-oriented approach to design truncates the creative process. Architecture is a man-made intervention, ultimately involving a fair bit of destruction in order to eventually arrive in a state of hopefully coherent grace in the lives of its users and the built or natural context (Clark 2000, 10). It is unacceptable to proceed hastily into such complex territory-without a degree of rigor and process-driven creativity commensurate with the gravity of creating large scale, reality-altering, life-affecting structures. A process-driven inquiry requires many hours of experiment, revision, and meandering about that may initially have no relevance to any project at hand. It is time spent playing that produces creative designers, and it is creativity that we profess to provide for people. The designer that only picks up a pencil while on the clock, and walks past a stack of Legos without any urge at all to pick a few up and toy with them has lost his or her way. A re-introduction of play in the processes of designers, architects, and other creative professionals is vital to our continued place as contributors in the interest of a better world. This study seeks to illuminate the non-linear, to give play a respected spot as a design strategy. Play leads to better ideas, and toys lead to play. This will be a chronicling of one person's journey, through a play - based design process, in order that we may better understand how play fits into an inquisitive and productive design methodology.

Today, designing in digital environment is far less limiting than the physical reality that the product will end up in - stresses and forces, physical material properties, manufacturing possibilities, economic considerations and etc. are to a large extent not present in digital design tools. With many of these being directly computable it would make sense to introduce these restrictions from the physical world to the digital design environment. By doing this with we could take account of the inevitable restrictions from the very initial design phases and considerations, hopefully enabling us to make better informed decisions and designs. / Idag, designar i digitala miljön är betydligt mindre begränsande än den fysiska verkligheten att produkten kommer att hamna i - spänningar och krafter, fysikaliska materialegenskaper, tillverkningsmöjligheter, ekonomiska överväganden och etc. är i stor utsträckning inte finns i digitala designverktyg. Med många av dessa är direkt beräkningsbar det skulle vara meningsfullt att införa dessa restriktioner från den fysiska världen till den digitala designmiljö. Genom att göra detta med vi kunde ta hänsyn till de oundvikliga begränsningar från mycket ursprungliga utformning och överväganden, förhoppningsvis gör det möjligt för oss att fatta bättre underbyggda beslut och designer.

abstract: This thesis explores the possibility of fabricating superconducting tunnel junctions (STJ) using double angle evaporation using an E-beam system. The traditional method of making STJs use a shadow mask to deposit two films requires the breaking of the vacuum of the main chamber. This technique has given bad results and proven to be a tedious process. To improve on this technique, the E-beam system was modified by adding a load lock and transfer line to perform the multi-angle deposition and in situ oxidation in the load lock without breaking the vacuum of the main chamber. Bilayer photolithography process was used to prepare a pattern for double angle deposition for the STJ. The overlap length could be easily controlled by varying the deposition angles. The low-temperature resistivity measurement and scanning electron microscope (SEM) characterization showed that the deposited films were good. However, I-V measurement for tunnel junction did not give expected results for the quality of the fabricated STJs. The main objective of modifying the E-beam system for multiple angle deposition was achieved. It can be used for any application that requires angular deposition. The motivation for the project was to set up a system that can fabricate a device that can be used as a phonon spectrometer for phononic crystals. Future work will include improving the quality of the STJ and fabricating an STJs on both sides of a silicon substrate using a 4-angle deposition. / Dissertation/Thesis / Masters Thesis Mechanical Engineering 2019