Digital games are based on interactive virtual environments where graphics and audio are combined. In many of these games there is lot of effort put into graphics while leaving the audio part underdeveloped. Audio in games is important in order to immerse the player in the virtual environment. Where a high level of emulated reality is needed graphics and audio should be combined on a similar level of realism. To make this possible a sophisticated method for audio simulation is needed. In the audio simulation field previous attempts at using ray tracing methods were successful. With methods based on ray tracing the sound waves are traced from the audio source to the listener in the virtual environment, where the environment is based on a scene consisting of implicit surfaces. A key part in the tracing computations is finding the intersection point between a sound wave and the surfaces in the scene. Sphere tracing is an alternative method for finding the intersection point and has been shown to be feasible for real-time usage on the graphics processing unit (GPU). To be interactive a game environment runs in real-time, this fact puts a time constraint on the rendering of the graphics and audio. The time constraint is based on the time window to render one frame in the synchronized rendering of graphics and audio based on the frame rate of the graphics. Consumer computer systems of today are in general equipped with a GPU, if an audio simulation can use the GPU in real-time this is a possible implementation target in a game system. The aim of this thesis is to investigate if audio simulation with the ray tracing method based on sphere tracing is possible to run in real-time on the GPU. An audio simulation system is implemented in order to examine the possibility for real-time usage based on computation time. The results of this thesis show that audio simulation with implicit surfaces using sphere tracing is possible to use in real-time with the GPU in some form. The time consumption for an audio simulation system like this is small enough to enable it for real-time usage. Based on an interactive graphics frame rate the time consumption allows the graphics and audio computations to use the GPU in the same frame time.

This thesis explores the prestige associated in late medieval Scotland with Flemish luxury products, using a material culture-based approach founded on the premise that objects can reveal the beliefs and attitudes of those who used them. Adding to existing scholarship which concentrates on the economic, political, and diplomatic connections between Scotland and Flanders, this research offers a new artefactual dimension to this relationship. It challenges the perception of Scotland as culturally and materially unsophisticated while simultaneously considering how objects were used in the expression of elite power and status. What drives this work is that late medieval Scottish elites were fully immersed in the most highly regarded and fashionable material trends of western Europe and that their consumption patterns fit into a wider mentality which saw Flemish craftsmanship as an ideal. A new model is thus presented, moving away from the traditional concentration on fluctuating wool exports and taking into account the cultural agency of noble, ecclesiastic, and burghal elites. It entails the initial examination of Scottish consumer demand and its impact on the Flemish luxury market. Following this are chapters on gift exchange and the presentation of magnificence, centred around the perception of the Flemish aesthetic as representative of elite status. Finally, this approach is applied to the burghal and clerical spheres, arguing that Flemish church furniture played a role in the formation and maintenance of elite urban identities. The comprehensive examination of artefactual sources, combined with the commercial, ritual, and ceremonial evidence found in written sources, enables the building up of a clearer impression of Scoto-Flemish material culture than has previously been realised. It is demonstrated that the material environment of late medieval Scottish elites was comparable to those of other European polities, constituting a common cultural sphere furnished by the luxury products of Flanders and the southern Low Countries.

In this dissertation the aim was to investigate the usage of algorithms found in computer science and apply suitable algorithms to the problem of decoding multiple-input multipleoutput (MIMO) space-time-frequency block coded signals. It was found that the sphere decoder is a specific implementation of the A* tree search algorithm that is well known in computer science. Based on this knowledge, the sphere decoder was extended to include a priori information in the maximum a posteriori probability (MAP) joint decoding of the STFC block coded MIMO signals. The added complexity the addition of a priori information has on the sphere decoder was investigated and compared to the sphere decoder without a priori information. To mitigate the potential additional complexity several algorithms that determine the order in which the symbols are decoded were investigated. Three new algorithms incorporating a priori information were developed and compared with two existing algorithms. The existing algorithms compared against are sorting based on the norms of the channel matrix columns and the sorted QR decomposition. Additionally, the zero forcing (ZF) and minimum mean squared error (MMSE) decoderswith and without decision feedback (DF) were also extended to include a priori information. The developed method of incorporating a priori information was compared to an existing algorithm based on receive vector translation (RVT). The limitation of RVT to quadrature phase shift keying (QPSK) and binary shift keying (BPSK) constellations was also shown in its derivation. The impact of the various symbol sorting algorithms initially developed for the sphere decoder on these decoders was also investigated. The developed a priori decoders operate in the log domain and as such accept a priori information in log-likelihood ratios (LLRs). In order to output LLRs to the forward error correcting (FEC) code, use of the max-log approximation, occasionally referred to as hard-to-soft decoding, was made. In order to test the developed decoders, an iterative turbo decoder structure was used together with an LDPC decoder to decode threaded algebraic space-time (TAST) codes in a Rayleigh faded MIMO channel. Two variables that have the greatest impact on the performance of the turbo decoder were identified: the hard limit value of the LLRs to the LDPC decoder and the number of independently faded bits in the LDPC code. / Dissertation (MEng)--University of Pretoria, 2013. / gm2014 / Electrical, Electronic and Computer Engineering / unrestricted

[pt] A questão que move esta estudo gira em torno de indagações teóricas acerca do papel das novas mídias na formação política atual. Parto da ideia de que a internet desempenha, hoje, papel central no desenho da esfera pública. Faz- se necessário, entretanto, transcender o conceito, tal como pontuado por Jurgen Habermas, visto que este defende que o agir nesta esfera resume-se a expor e ouvir ideias em sua forma discursiva verbal. É intrínseco, portanto, que atuando na esfera pública podemos formar nossas opiniões, compartilhá-las e transformá-las, configurando-a, por princípio, como um espaço formativo. Normalmente, autores da área da educação relacionam o pensamento de Habermas à formação política em, pelo menos, duas vertentes: a construção de um público apto a argumentar utilizando a linguagem verbal; e sua relação com a formação dos indivíduos, no tocante a sua capacidade de construir opiniões de forma crítica e reflexiva. Ela é, então, caracterizada pelo autor como um espaço racional e mediado pela linguagem verbal. Acredito, contudo, que algo foge a essas interpretações, especialmente, quando observamos a interação na web. Defendo a tese de que é preciso considerar a esfera pública virtual uma tecnologia cognitiva, ampliando sua conhecida vertente discursiva verbal. O intuito da pesquisa é unir uma série de aspectos que, em detrimento da valorização do discurso racional, acabam excluídas da análise habermasiana e da pedagogia crítica. Isso não significa abandonar a ideia de que a esfera pública seja um espaço de atos de fala, de discussão de ideias ou mesmo de emancipação social ou criação de consciência política, mas procurar ir além. Interessa-me englobar, a esse vasto repertório, uma concepção de funcionamento da mente/racionalidade que incorpore também aspectos corporais, emocionais e tecnológicos ao uso dos artefatos conectados à internet como tecnologias cognitivas, extensões de nossa mente e objetos materiais que produzem e/ ou alteram o sentido empregadona construção de significados e visões de mundo. Isso implica compreender esses objetos como constitutivos e transformadores e, não apenas, instrumentos procedimentais ou mediadores na construção de nossas opiniões e ideologias políticas. / [en] The question that moves this thesis includes theoretical inquiries about the role of new media in the current political formation. I start from the idea that the internet plays, nowadays, a central position in the design of the public sphere, because it has been presented as the great deliberative arena today. It is necessary, however, to transcend the concept, as designed by Jurgen Habermas. He argues that acting in this sphere means to expose and listen to ideas in the verbal discursive form. It is, therefore, acting in the public sphere that we can form our opinions, share them and also transform them. Because it has these configurations the public space is by principle a formative space. Usually, authors of Education area relate Habermas s thinking to political formation in at least two strands: the construction of a public apt to argue using verbal language; and to form individuals capable of constructing their opinions in a critical and reflexive way. It means that public sphere is then a rational space mediated by verbal language. I believe, however, that something escapes these interpretations, especially when we observe the interaction on the web. I defend the thesis that it is necessary to consider the virtual public sphere as a cognitive technology, amplifying its wellknown verbal discourse. The aim of the research is to unite a series of aspects that, to the detriment of the valorization of the rational discourse, are excluded from the habermasian analysis and the critical pedagogy. It doesn t mean I m rejecting the idea that the public sphere is a space of speech acts, discussion of ideas or social emancipation, but go further. I am interested in including in this vision a conception of mind / rationality that also incorporates corporal, emotional and technological aspects to the use of internet connected artifacts as cognitive technologies, extensions of our mind and material objects that produce and / or altering construction of meanings and visions of the world. This implies understanding these objects as constitutive and transformative, not merely procedimental instruments or mediators in the construction of our political opinions and ideologies.

One of the most popular ways to exploit the advantages of a multiple-input multiple-output (MIMO) system is using space time block coding. A space time block code (STBC) is a finite set of complex matrices whose entries consist of the information symbols to be transmitted. A linear STBC is one in which the information symbols are linearly combined to form a two-dimensional code matrix. A well known method of maximum-likelihood (ML) decoding of such STBCs is using the sphere decoder (SD). In this thesis, new constructions of STBCs with low sphere decoding complexity are presented and various ways of characterizing and reducing the sphere decoding complexity of an STBC are addressed. The construction of low sphere decoding complexity STBCs is tackled using irreducible matrix representations of Clifford algebras, cyclic division algebras and crossed-product algebras. The complexity reduction algorithms for the STBCs constructed are explored using tree based search algorithms. Considering an STBC as a vector space over the set of weight matrices, the problem of characterizing the sphere decoding complexity is addressed using quadratic form representations. The main results are as follows. A sub-class of fast decodable STBCs known as Block Orthogonal STBCs (BOSTBCs) are explored. A set of sufficient conditions to obtain BOSTBCs are explained. How the block orthogonal structure of these codes can be exploited to reduce the SD complexity of the STBC is then explained using a depth first tree search algorithm. Bounds on the SD complexity reduction and its relationship with the block orthogonal structure are then addressed. A set of constructions to obtain BOSTBCs are presented next using Clifford unitary weight designs (CUWDs), Coordinate-interleaved orthogonal designs (CIODs), cyclic division algebras and crossed product algebras which show that a lot of codes existing in literature exhibit the block orthogonal property. Next, the dependency of the ordering of information symbols on the SD complexity is discussed following which a quadratic form representation known as the Hurwitz-Radon quadratic form (HRQF) of an STBC is presented which is solely dependent on the weight matrices of the STBC and their ordering. It is then shown that the SD complexity is only a function of the weight matrices defining the code and their ordering, and not of the channel realization (even though the equivalent channel when SD is used depends on the channel realization). It is also shown that the SD complexity is completely captured into a single matrix obtained from the HRQF. Also, for a given set of weight matrices, an algorithm to obtain a best ordering of them leading to the least SD complexity is presented using the HRQF matrix.

This study examines the potential for the Internet, or more specifically the World Wide Web, to enhance local democracy and local governance by providing a networked public sphere. It is located in post-industrial theories of social and political transformation, which see a new, uncertain and complex society emerging which may transform the political significance of the 'local'. Whilst a number of causes are identified as culpable in this process, it is the ICT revolution and the development of the Web in particular, that is seen as possessing a democratising potential that, if realised, may bring greater resilience to geographic localities. The potential of the Web to provide a new networked public sphere is based upon contested views that its topography, its hyperlinked structure, can enable the ordinary citizen's voice to be heard above those that traditionally dominate political discourse. However, there has been no attention paid to this potential being realised at a local governance level within which, this study argues, a favourable environment should exist for a local online networked public sphere to prosper. Accordingly, this prospect is empirically explored here through a case study of the use made of the Web by a variety of local civic, political and institutional actors during a 2008 local (Manchester, UK) referendum on introducing the largest traffic congestion charging scheme in the country. This research applies a distinctive mixed method approach within a conceptually defined internet mediated domain of local governance. Relational Hyperlink Analysis is used to analyse the structural significance of the captured congestion charge. This analysis uses Social Network Analysis (SNA) and an associated statistical technique, Exponential Random Graph Modelling (ERGM) to render the network visible and understandable. To further illuminate how the network was used by local civic and institutional actors involved in the referendum the research draws upon a network ethnography approach which uses SNA to identify subjects for qualitative investigation. The study offers some evidence of the Web providing 'just enough' links in this local context to suggest the structural existence of a networked public sphere. However, further evidence from the narratives and the statistical model paint an alternative picture. This suggests that, in the main, hyperlinking behaviour and use made of the network corresponds to a 'politics as usual' scenario where cliques are more likely to proliferate and powerful economic and media interests dominate online as they do offline. If the ordinary citizen's voice is to be heard in this context then there is a requirement for policy intervention to establish a trusted local networked public sphere or online civic space, independent of vested interests but linked to the local governance decision making process. In addition to this there is a requirement for greater education, particularly aimed at senior local governance policy makers, in the culture of online engagement.

No description available.

The maturation of the public sphere in Argentina during the late nineteenth and early twentiethcenturies was a critical element in the nation-building process and the overall development ofthe modern state. Within the context of this evolution, the discourse of disease generatedintense debates that subsequently influenced policies that transformed the public spaces ofBuenos Aires and facilitated state intervention within the private domains of the city’sinhabitants. Under the banner of hygiene and public health, municipal officials thusEuropeanized the nation’s capital through the construction of parks and plazas and likewiseutilized the press to garner support for the initiatives that would remedy the unsanitaryconditions and practices of the city. Despite promises to the contrary, the improvements to thepublic spaces of Buenos Aires primarily benefited the porteño elite while the efforts to rootout disease often targeted working-class neighborhoods. The model that reformed the publicspace of Buenos Aires, including its socially differentiated application of aesthetic order andpublic health policies, was ultimately employed throughout the Argentine Republic as theconsolidated political elite rolled out its national program of material and social development.

Orientador: Cristiano Torezzan / Dissertação (mestrado profissional) - Universidade Estadual de Campinas, Instituto de Matemática Estatística e Computação Científica / Made available in DSpace on 2018-08-27T01:15:40Z (GMT). No. of bitstreams: 1 Miranda_FabianoBoaventurade_M.pdf: 1712497 bytes, checksum: 35928984d709d1154545670e07948f87 (MD5) Previous issue date: 2015 / Resumo: Neste trabalho estudamos o problema da quantização vetorial, com especial interesse no uso de códigos esféricos para quantização de fontes gaussianas. Este problema tem diversas aplicações envolvendo compressão de sinais, tais como de som e imagem, garantindo altas taxas de compressão. Nos três primeiros capítulos fazemos uma apresentação dos principais fundamentos teóricos do tema, procurando apresentar exemplos que valorizam a intuição e conceitos geométrico, no caso de dimensões 2 e 3, abordando a quantização vetorial com ênfase na técnica conhecida como forma/ganho. No último capítulo apresentamos uma proposta original que utiliza códigos em camadas de toros para a quantização vetorial. A proposta é exemplificada através da construção do esquema de quantização em dimensão 4 e alguns testes de desempenho são apresentados / Abstract: We study the vector quantization problem with a special interest in the use of spherical codes for Gaussian sources. This problem appears in several applications involving signal compression such as sound, images and data transmission. The first three chapters are devoted to basic concepts of quantization and also to presented some intuitive examples and geometrical interpretations. We focus our attention on the shape and gain vector quantization and we introduce a new approach to this problem using spherical codes constructed in layers of flat tori in dimension 4. Besides the construction, some results on computations simulations are presented / Mestrado / Matematica Aplicada e Computacional / Mestre em Matemática Aplicada e Computacional

Orientador: Flávio Caldas da Cruz / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin / Made available in DSpace on 2018-08-30T22:47:31Z (GMT). No. of bitstreams: 1 Depetri_WilliamIunes_M.pdf: 11907943 bytes, checksum: 4f7cedccb63e0fd32bea356921cb78f6 (MD5) Previous issue date: 2016 / Resumo: Pentes de frequência ópticos têm sido desenvolvidos para medias de precisão e metrologia, mas tabém vêm ganhando interesse para espectroscopia de precisão de banda larga. Pentes ópticos no infravermelho médio são muito atraentes para espectroscopia molecular, dado que eles permitem acesso a fortes bandas vibracionais de gases na chamada "região de digital molecular". Pentes ópticos são uma tecnologia bem desenvolvida no infravermelho próximo, dado a disponibilidade de lasers de Ti:Safira e Er-fiber, e apesar de desenvolvimentos recentes, sua extensão para o infravermelho médion depende de conversão não-linear de frequência. Aqui, pretendemos estudar a greração de pentes ópticos no infravermelho médio via geração de diferença de frequência e amplificação paramétrica óptica do espectro de um oscilador de femtosegundo no infravermelho próximo. Neste trabalho, analizamos numericamente difereça de frequência e amplificação paramétrica para a geração de pentes de frequência ópticos no infravermelho médio resolvendo no domínio do tempo as equações acopladas para o campo elétrico em mistura de três ondas para pulsos ultracurtos. Uma abordagem tradicional é a utilização de quasi-phase matching em cristais periodicamente polados, o que pode ser bastante eficiente, porém apresenta limitações na largura de banda. Nóis investigamos cristais periódicos com um período fixo, e cristais aperiódicos, ou chirped, tanto com chirp contínuo como discreto. Nós comparamos as configurações nas quais a amplificação paramétrica é otimizada ou não, explorando uma analogia entre conversãpo não-linear em sistemas de dois níveis. Nossos resultados são apresentados como gráficos temporais da propagação dos pulsos, seus respectivos espectros e potências ao longo dos cristais, e comparados com resultados experimentais, com o intuito de ajudar experimentos futuros / Abstract: Optical frequency combs (OFC) have been developed for precision measurements and metrology, but have also gained interest for broadband precision spectroscopy. OFC in the mid-infrared (MIR) are very attractive for molecular spectroscopy, since they allow to access the strong vibrational bands of gases in the so-called molecular fingerprint region. OFC are a well-developed technology in the near-infrared, due to the avilability of Ti:Saphire or Er-fiber lasers, and spite of recent developments, their extension into the MIR relies on nonlinear frequency conversion. Here we intend to study the generation of MIR OFC via difference frequency generation (DFG) and optical parametric amplification (OPA) of spectral portions of a near-infrared femtosecond oscillator. In this work, we numerically analyze DFG and OPA for the generation of optical frequency combs in the mid-infrared by solving the time-domain coupled wave equations for the electric fields in three-wave mixing for ultrashort pulses. A traditional approach is to use quasi-phase matching in periodically poled crystals, which can be quite efficient but may have bandwidth limitations.We investigate periodically poled crystals with a single-grating and aperiodic or chirped crystal with either continuous or discrete chirp. We compare the configurations in which a strong pump pulse has higher or smaller wavelength compared to the signal, cases in which the parametric amplification is enhanced or not. We also analyze these results in the context of adiabatic frequency conversion, which explores an analogy between nonlinear conversion and two-level systems. Our results are presented as time plots for the propagation of the pulses, their corresponding spectra and powers along the crystals and are compared to experimental results, and also intended to support further experiments / Mestrado / Física / Mestre em Física / 132987/2014-7 / CNPQ