During the traditional manufacturing route, there are large amount of titanium alloys wasted in the form of machining chips. The conventional recycling methods require high energy consumption and capital cost. Equal channel angular pressing (ECAP), one of the severe plastic deformation techniques, has been developed to recycle the metallic machining chips. The purpose of the PhD work is to realize the ECAP recycling of titanium alloys, in particular Ti-6Al-4V and Ti-15V-3Cr-3Al-3Sn, and investigate the effects of processing parameters on the resultant relative density, microstructure evolution, texture development and microhardness homogeneity. The microstructures of Ti-6Al-4V and Ti-15V-3Cr-3Al-3Sn machining chips obtained from conventional turning (CT) and ultrasonically assisted turning (UAT) were initially investigated. It was found that ultrafine grains were formed in the primary and secondary shear zones. For Ti-6Al-4V chips, the β phase in the shear zones was refined into nano-sized equiaxed grains and aligned up to form banded structures. For Ti-15V-3Cr-3Al-3Sn chips, the nano-crystalline grains were enveloped in the shear zones and have clear boundaries to the surrounding matrix. It was observed that in terms of microstructure, there is no significant difference between CT and UAT chips. Recycling of Ti-6Al-4V machining chips was carried out at moderate temperatures with various back-pressures. For single-pass samples, the relative density was increased with the applied back-pressure and operating temperature. It was found that after multiple passes, near fully dense recycled Ti-6Al-4V can be fabricated. The microstructure observations showed that the nano-sized equiaxed and elongated grains co-existed with relatively coarser lamellar structures which were initially refined after the first pass. In the subsequent passes, the fraction of equiaxed nano-grains increased with the number of passes. The original β phase banded structures were fragmented into individual nano-sized grains randomly distributed within α matrix. The chip boundaries were eliminated and nano-crystalline microstructure region was observed at the chip/chip interface after multiple passes. In the sample processed at 550 °C, < a →+c → > type dislocations were observed and oxide layer at chip/chip interface was detected. The texture evolution was investigated using electron backscatter diffraction. It was found that the recycled samples performed a strong basal texture along the normal to ECAP inclination direction after the first pass. After multiple passes, in addition to the normal to inclination direction, the recycled Ti-6Al-4V exhibits a basal texture towards the transverse direction. Microhardness mapping showed that the average hardness and degree of homogeneity were increased with number of passes, while the imposed back-pressure had little effect on the average value and homogeneity. Recycling of Ti-15V-3Cr-3Al-3Sn machining chips was implemented using similar ECAP conditions. The effects of processing parameters, such as back-pressure, operating temperature and number of passes, on the relative density were similar to those for Ti-6Al-4V. Microstructural characterization showed that equiaxed instead of needle shaped α precipitates formed in the β matrix due to the high dislocation density and sub-grain boundaries introduced during ECAP. In terms of microhardness, the maximum hardness was obtained at the specimen pressed at 450 °C. It was found that the applied back-pressure and number of passes enabled to improve the homogeneity, but had little effect on the average hardness.

We present the first resolved image of the debris disk around the 16 +/- 8 Myr old star, HD 114082. The observation was made in the H-band using the SPHERE instrument. The star is at a distance of 92 +/- 6 pc in the Lower Centaurus Crux association. Using a Markov chain Monte Carlo analysis, we determined that the debris is likely in the form of a dust ring with an inner edge of 27.7(-3.5)(+2.8) au, position angle -74.3 degrees(-1.5) (+0.5), and an inclination with respect to the line of sight of 6.7 degrees(+3.8)(-0.4). The disk imaged in scattered light has a surface density that is declining with radius of similar to r(-4), which is steeper than expected for grain blowout by radiation pressure. We find only marginal evidence (2 sigma) of eccentricity and rule out planets more massive than 1.0 M-Jup orbiting within 1 au of the inner edge of the ring, since such a planet would have disrupted the disk. The disk has roughly the same fractional disk luminosity (L-disk = L-* = 3.3 x 10(-3)) as HR 4796 A and beta Pictoris, however it was not detected by previous instrument facilities most likely because of its small angular size (radius similar to 0.4"), low albedo (similar to 0.2), and low scattering efficiency far from the star due to high scattering anisotropy. With the arrival of extreme adaptive optics systems, such as SPHERE and GPI, the morphology of smaller, fainter, and more distant debris disks are being revealed, providing clues to planet-disk interactions in young protoplanetary systems.

ABSTRACT   Context: Many websites today are very interactive and the users are getting used to sites that change hundreds of elements every second. Often a JavaScript framework is used to build the web site and with many changing elements on the site the need for a JavaScript framework that can handle the fast changes are needed. Each frameworks do it differently to achieving this but most of them do some manipulation with the Document Object Model (DOM).     Objectives: This research will show how fast the selected MCV like JavaScript frameworks (AngularJs, AngularJs 2.0, Aurelia, Backbone, Ember, Knockout, Mithril, Vue) can create, delete and update HTML elements on the screen.     Methods: This research have used Google Chromes TimeLine tool to measure the speed of the frameworks. The test involves creating a HTML table and fill it with a thousand rows of data with six columns. The tables content are tested to see how fast the frameworks can create, update and remove the elements.       Conclusions: Angular 2.0 almost achieved first place in all tests. Angular 1.5 did very good in the update tests and was good in the create elements test. Backbone and Ember did not do so well in the create and update tests but Backbone was the best framework in one of the delete tests. Aurelia got very good results and so did Vue which almost had the same values as Aurelia throughout the tests. Mithril and Knockout performed well in the create test which placed them in the middle among all the selected frameworks. When it came to the update tests Mithril and Knockout also found them self in the middle positions of all the frameworks.          Key Words: JavaScript, Framework, performance, Angular, Aurelia, Backbone,  Ember, Knockout, Mithril, Vue.

>Magister Scientiae - MSc

The electron microscope is an ideal tool to prepare an electron into a specified quantum state, entangle that state with states in a specimen of interest, and measure the electron final state to indirectly gain information about the specimen. There currently exist excellent technologies to prepare both momentum eigenstates (transmission electron microscopy) and position eigenstates (scanning transmission electron microscopy) in a narrow band of energy eigenstates. Similarly, measurement of the momentum and position final states is straightforward with post-specimen lenses and pixelated detectors. Measurement of final energy eigenstates is possible with magnetic electron energy loss spectrometers. In 2010 and 2011, several groups independently showed that it was straightforward to prepare electrons into orbital angular momentum eigenstates. This disseratation represents my contributions to the toolset we have to control these eigenstates: preparation, application (interaction with specimen states), and measurement. My collaborators and I showed that phase diffraction gratings efficiently produce electron orbital angular momentum eigenstates; that control of orbital angular momentum can be used to probe chirality and local magnetic fields; and that there are several routes toward efficient measurement.

The traditional way to coordinate multiple clients in a multiplayer based game on multiple platforms is to create an implementation on a per-platform basis - resulting in often four different implementations, one for each major platform - ie. iOS, Android, Windows, and Linux based operating systems. This report examines the possibility of replacing multiple so called “native apps” with a single web based implementation - granting users access on all devices that supports modern browsers, and discusses what tools were used in the development of the application and why. / Det vanliga sättet att hantera multipla klienter i spel med flerspelarlägen är att utveckla unika implementationer på en per-plattform basis - alltså att samma applikation kräver en unik implementation för var plattform som skall stödjas. Vanligtvis görs en unik implementation för iOS, Android, Windows och Unix-baserade operativsystem vardera. Denna rapport undersöker möjligheten att ersätta dessa implementationer med en unison webbaserad implementation som tillåter alla enheter ​med stöd för moderna webbläsare att använda applikationen och diskuterar vilka verktyg som använts och varför.

There are two main features in this thesis. The first is a study of the role of "tracts" of finite determination on the growth of integral functions. Such a study is of importance, since most of the known results in this field are based on the extreme case where the tracts of finite determination reduce to single lines. The second is the construction of functions, meromorphic and integral, bounded in tracts of positive angular measure, where the tracts are not confined to radial sectors.

Studying the orbital angular momentum (OAM) of light has become rather fashion- able in the 21st century. Yet, most of major advances in OAM related research have been conducted in the visible regime of light. A significant portion OAM research revolves around using OAM radiation to perform some function that is deemed useful. Examples of this are optical trapping, micro-machine manipulation and the development of advanced communication systems. Photon entanglement measurements also make use of OAM radiation. Interest in probing radiation for naturally generated OAM is far less popular. For example, interest in building OAM sensitive telescopes was sparse at the beginning of this thesis, however the first reported detection of astrophysical OAM was published in 2013. This thesis aims to tackle these two areas of sparse research by developing the components and understanding in order to build OAM sensitive millimetre-wavelength telescopes. Spiral phase plates (SPPs) are the device of choice. The majority of the thesis sets out to test three different SPPs, in order to compare and contrast different methods for their manufacture and design. Electromagnetic theory of OAM and its generation is reviewed first. Then, each SPP is modelled numerically fol- lowed by in-depth modelling of each plate by using the computational electromagnetic package FEKO. Finally, each plate is measured with a three dimensional field scanner developed as part of this thesis. Development of a new modular SPP design concludes this thesis.

Thesis (M. Sc. (Chemistry)) --University of Limpopo, 2018 / The dissertation describes the use of 2-benzenesulfonyloxyquinoxaline as a good coupling partner for different amine substrates. The palladium-mediated cross- coupling of aryl electrophiles and amines has become a widely used method of constructing arylamine frameworks. The formation of carbon-nitrogen bonds was accomplished via palladium-catalysed Buchwald-Hartwig amination employing different amine substrates to yield substituted quinoxaline-2-amines compounds in good to moderate yields. Buchwald ligands (Xphos, tButylxphos and BrettPhos), were varied with different amine substrates in an attempt of improving the yields. Compounds 81a N-phenylquinoxalin-2-amine and 82b, N-benzylquinoxalin-2-amine were obtained with the yield over 70 % employing Xphos as the ligand. Significant attention has also been given to the application of cross coupling reaction protocols in substrates bearing electron withdrawing substituents. The presence of deactivating groups on the arylamine such as fluoro, nitro and iodo proved to be a challenge as only few compounds were synthesised in moderate yields. Compound 81b, N-(4-fluorophenyl)quinoxalin-2-amine which has electronegative atom attached, showed significant improvement when employing tButyl-Xphos ligand rather than XPhos since the yield improved from 10 % to 71 %. Furthermore, nucleophilic substitution on Buchwald-Hartwig coupled compounds by treating them with alkyl iodides was successful when using methyl and ethyl electrophiles on the N-H group of 81a 2-quinoxalineamine. The synthesised quinoxaline derivatives comprised 7 novel compounds. The in vitro analysis on anti-tubercular screening against H37RvMA strains of Mycobacterium tuberculosis was conducted on 9 compounds. The results revealed none of the compounds to have promising inhibition percentages against Mycobacterium tuberculosis when compared with rifampicin which was used as a positive control. Screening against malaria with chloroquine as the control also did not yield any active compounds.

This research investigates the spectral reflectance characteristics of soil and vegetation using multi-angular and single view hyperspectral data. The question of the thesis is ???How much information can be obtained from multi-angular hyperspectral remote sensing in comparison with single view angle hyperspectral remote sensing of soil and vegetation???? This question is addressed by analysing multi-angular and single view angle hyperspectral remote sensing using data from the field, airborne and space borne hyperspectral sensors. Spectral mapping, spectral indices and Functional Data Analysis (FDA) are used to analyse the data. Spectral mapping has been successfully used to distinguish features of soil and cotton with hyperspectral data. Traditionally, spectral mapping is based on collecting endmembers of pure pixels and using these as training areas for supervised classification. There are, however, limitations in the use of these algorithms when applied to multi-angular images, as the reflectance of a single ground unit will differ at each angle. Classifications using six-class endmembers identified using single angle imagery were assessed using multi-angular Compact High Resolution Imaging Spectrometer (CHRIS) imagery, as well as a set of vegetation indices. The results showed no significant difference between the angles. Low nutrient content in the soil produced lower vegetation index values, and more nutrients increased the index values. This research introduces FDA as an image processing tool for multi-angular hyperspectral imagery of soil and cotton, using basis functions for functional principal component analysis (fPCA) and functional linear modelling. FDA has advantages over conventional statistical analysis because it does not assume the errors in the data are independent and uncorrelated. Investigations showed that B-splines with 20-basis functions was the best fit for multi-angular soil spectra collected using the spectroradiometer and the satellite mounted CHRIS. Cotton spectra collected from greenhouse plants using a spectrodiometer needed 30-basis functions to fit the model, while 20-basis functions were sufficient for cotton spectra extracted from CHRIS. Functional principal component analysis (fPCA) of multi-angular soil spectra show the first fPCA explained a minimum of 92.5% of the variance of field soil spectra for different azimuth and zenith angles and 93.2% from CHRIS for the same target. For cotton, more than 93.6% of greenhouse trial and 70.6% from the CHRIS data were explained by the first fPCA. Conventional analysis of multi-angular hyperspectral data showed significant differences exist between soil spectra acquired at different azimuth and zenith angles. Forward scan direction of zenith angle provides higher spectral reflectance than backward direction. However, most multi-angular hyperspectral data analysed as functional data show no significant difference from nadir, except for small parts of the wavelength of cotton spectra using CHRIS. There is also no significant difference for soil spectra analysed as functional data collected from the field, although there was some difference for soil spectra extracted from CHRIS. Overall, the results indicate that multi-angular hyperspectral data provides only a very small amount of additional information when used for conventional analyses.