Approximate solutions of certain shallow shell problems

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Fast reliable interrogation of procedurally defined implicit surfaces using extended revised affine arithmetic.

Techniques based on interval and previous termaffine arithmetic next term and their modifications are shown to provide previous term reliable next term function range evaluation for the purposes of previous termsurface interrogation.next term In this paper we present a technique for the previous termreliable interrogation of implicit surfacesnext term using a modification of previous termaffine arithmeticnext term called previous term revised affine arithmetic.next term We extend the range of functions presented in previous termrevised affine arithmeticnext term by introducing previous termaffinenext term operations for arbitrary functions such as set-theoretic operations with R-functions, blending and conditional operators. The obtained previous termaffinenext term forms of arbitrary functions provide previous termfasternext term and tighter function range evaluation. Several case studies for operations using previous termaffinenext term forms are presented. The proposed techniques for previous termsurface interrogationnext term are tested using ray-previous termsurfacenext term intersection for ray-tracing and spatial cell enumeration for polygonisation. These applications with our extensions provide previous termfast and reliablenext term rendering of a wide range of arbitrary previous termprocedurally defined implicit surfacesnext term (including polynomial previous termsurfaces,next term constructive solids, pseudo-random objects, previous termprocedurally definednext term microstructures, and others). We compare the function range evaluation technique based on previous termextended revised affine arithmeticnext term with other previous termreliablenext term techniques based on interval and previous termaffine arithmeticnext term to show that our technique provides the previous termfastestnext term and tightest function range evaluation for previous termfast and reliable interrogation of procedurally defined implicit surfaces.next term Research Highlights The main contributions of this paper are as follows. ► The widening of the scope of previous termreliablenext term ray-tracing and spatial enumeration algorithms for previous termsurfacesnext term ranging from algebraic previous termsurfaces (definednext term by polynomials) to general previous termimplicit surfaces (definednext term by function evaluation procedures involving both previous termaffinenext term and non-previous termaffinenext term operations based on previous termrevised affine arithmetic)next term. ► The introduction of a technique for representing procedural models using special previous termaffinenext term forms (illustrated by case studies of previous termaffinenext term forms for set-theoretic operations in the form of R-functions, blending operations and conditional operations). ► The detailed derivation of special previous termaffinenext term forms for arbitrary operators

Fast Reliable Ray-tracing of Procedurally Defined Implicit Surfaces Using Revised Affine Arithmetic

Fast and reliable rendering of implicit surfaces is an important area in the field of implicit modelling. Direct rendering, namely ray-tracing, is shown to be a suitable technique for obtaining good-quality visualisations of implicit surfaces. We present a technique for reliable ray-tracing of arbitrary procedurally defined implicit surfaces by using a modification of Affine Arithmetic called Revised Affine Arithmetic. A wide range of procedurally defined implicit objects can be rendered using this technique including polynomial surfaces, constructive solids, pseudo-random objects, procedurally defined microstructures, and others. We compare our technique with other reliable techniques based on Interval and Affine Arithmetic to show that our technique provides the fastest, while still reliable, ray-surface intersections and ray-tracing. We also suggest possible modifications for the GPU implementation of this technique for real-time rendering of relatively simple implicit models and for near real-time for complex implicit models

Incisions / Insertions: re-inscribing narrative into a city landscape

Dating back to the late 1700's from the skirt of Devil's Peak down to what used to be the shoreline of Cape Town, this once walled off city has undergone plentiful re-inscriptions of the landscape till today. Remnants of the old French line fortifications remain along the slope of Trafalgar Park, disregarded and lost in the city 'scapes. The reading and re-tracing to pre-existing and existing layers of the precinct has been developed through blackout art methods of incisions and insertions to acknowledge the pre-existing and the existing in order to create a new narrative for this land without a landscape. In establishing the character of the narrative and the architecture thereof, the imagination of the space transcribed from archetypes - people - from the surrounds and what could be their ultimate feeling for what should be placed forms the landscape and how their individual expectations meet with others. The narrative is split twofold, the one is that the moments along the Bigger story is the park intervention - traces of the incision old fort wall - strung into the city block and the other is the pedestrian insertion armature which cuts through the site, providing for a short cut to the train station. The path aims to take the pedestrian through a series of spatial experiences through the site. These experiences are shaped by the tectonic expression. The architecture of the new is at constant dialogue with the existing, playing on a series of incisions and insertions. The cross pollination of the varying programme in the precinct facilitates this dynamic spatial experience through the link

Assessing the African mobile telephony boom : the impact of the mobile phone and its relationship to the digital divide

Includes abstract.Includes bibliographical references (leaves 78-81).This dissertation provides an overview of the boom in mobile telephony in Africa, experienced in terms of exceptional and increasing subscriber growth. It provides a description of the mobile telephony boom, as well as its social political and economic impacts. It investigates what effect mobile telephony has had on the bridging of a broader digital divide, conceived of in terms of inequalities in access to information and communication technologies between Africa and the rest of the world, as well within Africa itself. It concludes that the boom in mobile telephony has had far-reaching impacts on the continent at all levels of African society. In particular, mobile phones have had a significant economic impact on the continent, which the author argues has been from the bottom up -affecting greatly the base of the economic pyramid and the informal sector. Mobile telephony has however not made a significant impact in the bridging of the digital divide conceived of in terms of access to the internet. A broader digital divide still exists which mobile telephony may not provide the tools to bridge

Recollect: home video and the autobiographical self

A thesis submitted to the Faculty of Arts, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy. Johannesburg, 2015This research looks at home video footage and family photographs as part of the visual portrait of a curated record of the autobiographical self. The research includes a written thesis exploring the theoretical concerns and provides a reflexive analysis of the creative component of the PhD, which is a 60-minute documentary film. The research, both creative and written, assesses how autobiographical memory is informed and shaped by home video recordings, and how new digital formats have allowed home video to collapse the boundaries between the personal and the public. It also explores how personal narratives speak to the wider socio-political and cultural concerns of a particular time. These ‘collapses’ between boundaries provide a playful, pluralistic approach to a history of the self. The many paradigms that coexist within the work – the past and the present, time and space, previously accepted narratives and newly formed ones – do not exist as binary to each other, but rather exist in conversation with each other and serves to explore the ever elastic subject/object dichotomy. The autobiographical film is titled Fraternal, with the tagline ‘The future isn’t like it used to be’. It tells the emotional story of the relationships between myself and my twin, and our parents – the hellos and goodbyes, arrivals and departures, beginnings and endings that happen within family ties. The film is set against the backdrop of the political situation in southern Africa during the 1980s and 1990s. It is cut predominantly from personal home video footage: a mixture of Super 8mm, Hi8 and DV footage shot largely between 1984 and 1994 in Zimbabwe and South Afric

Space-Time Transfinite Interpolation of Volumetric Material Properties

The paper presents a novel technique based on extension of a general mathematical method of transfinite interpolation to solve an actual problem in the context of a heterogeneous volume modelling area. It deals with time-dependent changes to the volumetric material properties (material density, colour and others) as a transformation of the volumetric material distributions in space-time accompanying geometric shape transformations such as metamorphosis. The main idea is to represent the geometry of both objects by scalar fields with distance properties, to establish in a higher-dimensional space a time gap during which the geometric transformation takes place, and to use these scalar fields to apply the new space-time transfinite interpolation to volumetric material attributes within this time gap. The proposed solution is analytical in its nature, does not require heavy numerical computations and can be used in real-time applications. Applications of this technique also include texturing and displacement mapping of time-variant surfaces, and parametric design of volumetric microstructures

Convergence, Confusion, Conflation - An Analysis of the Intersection of Human Rights and Humanitarian Discourses

This study starts with an observation: human rights and humanitarianism are often conflated into one and the same thing, even by scholars of these respective fields. A muddled use of terminology makes this lack of clarity evident; as such, the importance and power of language and discourse lies at the centre of this project. This thesis is set out to explore intersections and map convergences of human rights and humanitarianism—as discourses, as practices, and as related bodies of law (International Human Rights Law (IHRL) and Humanitarian Law (IHL)). In doing so, it seeks to draw attention to the beneficial potential of an interaction that can –at times– be synergetic, but also to the tensions it creates, when, far from mutually strengthening, human rights and humanitarianism work in contradiction. First, this thesis analyses the rapprochement between IHL and IHRL. This initial focus on the legal frameworks sets the ground for the subsequent study of converging discourses and practices, but it is also intrinsically valuable, laying bare some of the tensions around the jurisdictions, scopes of application, and protections afforded by these bodies of law. Second, focusing on four big player – two on the human rights side (Amnesty International and Human Rights Watch), and two on the humanitarian side (the International Committee of the Red Cross and Médecins Sans Frontières), this thesis turns to analysing dominant discourses. Noting the increased overlap in scopes of activities, and thus in discourse, it studies the impacts of the humanitarian-isation of human rights reporting, as well as of the human rights-isation of humanitarian discourse and practice. Looking at the predicament between denunciation and access, central to humanitarian work, we see how the pervasion of rights-speak has influenced that dilemma, and the way humanitarian actors navigate it. Third, taking inspiration from Raymond Williams’s keyword approach, this study then zeroes in on the term ‘protection’, having identified it as central to this convergence. A closer analysis of this term’s evolution, (contested) meanings and uses allows us to unlock understandings of this phenomenon. This thesis considers ‘Protection’ –ubiquitous in both discourses– as it partly constitutes, and furthers the convergence. This thesis studies the efforts to make its definition consensual and some of the consequences of the confusion around it. Finally, by analysing the compounded terms of ‘protection of civilians’ and ‘responsibility to protect’, it explores the ways in which ‘protection’ penetrated UN discourse, acting as a Trojan horse for the tensions created by the convergence of human rights and humanitarianis

Convergence, Confusion, Conflation - An Analysis of the Intersection of Human Rights and Humanitarian Discourses

This study starts with an observation: human rights and humanitarianism are often conflated into one and the same thing, even by scholars of these respective fields. A muddled use of terminology makes this lack of clarity evident; as such, the importance and power of language and discourse lies at the centre of this project. This thesis is set out to explore intersections and map convergences of human rights and humanitarianism—as discourses, as practices, and as related bodies of law (International Human Rights Law (IHRL) and Humanitarian Law (IHL)). In doing so, it seeks to draw attention to the beneficial potential of an interaction that can –at times– be synergetic, but also to the tensions it creates, when, far from mutually strengthening, human rights and humanitarianism work in contradiction. First, this thesis analyses the rapprochement between IHL and IHRL. This initial focus on the legal frameworks sets the ground for the subsequent study of converging discourses and practices, but it is also intrinsically valuable, laying bare some of the tensions around the jurisdictions, scopes of application, and protections afforded by these bodies of law. Second, focusing on four big player – two on the human rights side (Amnesty International and Human Rights Watch), and two on the humanitarian side (the International Committee of the Red Cross and Médecins Sans Frontières), this thesis turns to analysing dominant discourses. Noting the increased overlap in scopes of activities, and thus in discourse, it studies the impacts of the humanitarian-isation of human rights reporting, as well as of the human rights-isation of humanitarian discourse and practice. Looking at the predicament between denunciation and access, central to humanitarian work, we see how the pervasion of rights-speak has influenced that dilemma, and the way humanitarian actors navigate it. Third, taking inspiration from Raymond Williams’s keyword approach, this study then zeroes in on the term ‘protection’, having identified it as central to this convergence. A closer analysis of this term’s evolution, (contested) meanings and uses allows us to unlock understandings of this phenomenon. This thesis considers ‘Protection’ –ubiquitous in both discourses– as it partly constitutes, and furthers the convergence. This thesis studies the efforts to make its definition consensual and some of the consequences of the confusion around it. Finally, by analysing the compounded terms of ‘protection of civilians’ and ‘responsibility to protect’, it explores the ways in which ‘protection’ penetrated UN discourse, acting as a Trojan horse for the tensions created by the convergence of human rights and humanitarianis

Embedded Implicit Stand-ins for Animated Meshes: a Case of Hybrid Modelling

In this paper we address shape modelling problems, encountered in computer animation and computer games development that are difficult to solve just using polygonal meshes. Our approach is based on a hybrid modelling concept that combines polygonal meshes with implicit surfaces. A hybrid model consists of an animated polygonal mesh and an approximation of this mesh by a convolution surface stand-in that is embedded within it or is attached to it. The motions of both objects are synchronised using a rigging skeleton. This approach is used to model the interaction between an animated mesh object and a viscoelastic substance, normally modelled in implicit form. The adhesive behaviour of the viscous object is modelled using geometric blending operations on the corresponding implicit surfaces. Another application of this approach is the creation of metamorphosing implicit surface parts that are attached to an animated mesh. A prototype implementation of the proposed approach and several examples of modelling and animation with near real-time preview times are presented