The design of a battery-powered, portable headphone active noise control system with TI TMS320C5416 DSP is described. The preliminary implementation of the system on a C5416 DSK is also explained. The problems of fixed-point implementation are described and solutions are proposed. Sign-sign Fx-LMS algorithm with a dead-zone is introduced and used as the adaptation algorithm. Effective use of dynamic range to improve the accuracy in filtering operations is discussed. Details of the designed battery-powered DSP board are given and board software development process is explained. The DSK system and designed portable system is compared against two commercially available analog systems under three different types of noises / composition of tones, drill noise and propeller plane cabin noise. The results reveal that adaptive system has better overall performance.

Thesis (MEng)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Nano-satellites are mostly used in lower earth orbit applications, where communication intervals are limited, often to a combined total of less than one hour per day. With these type of inherent limitations of lower earth orbits, there are also the physical size and equipment restriction of nano-satellites to consider, especially those of the CubeSat specification. It is of critical importance to use the limited time and communication resources as effectively as possible. The network protocol has a huge influence on reliability and throughput of a satellite network. An important requisite for designing, comparing and improving network protocols is a network protocol simulator, that is able to envisage the design results. Simulation can facilitate rapid development and unforeseen discoveries. Very little information is currently available regarding communication protocols used in nano-satellites. This thesis aims to explore and improve the current status of nano-satellite network simulation, as well as to demonstrate the development of an improved communication protocol strategy. It was found that there is a lack of proper simulation tools for satellite networks, which led to the development of SatSim. SatSim is a discrete event network simulation tool, developed in Python, which can be used to develop and analyse network protocols. SatSim was verified by comparing simulation results with other published results, which made use of different software tools and theoretical throughput calculations. AX.25 is one of the most commonly used network protocols in the nano-satellite industry. It was implemented in SatSim and verified with theoretical throughput calculations, as no other simulation data on AX.25 was available. AX.25 was used as a baseline protocol to improve upon. FX.25 was developed by the Stensat Group in an attempt to improve AX.25. FX.25 adds forward error correction to AX.25, by wrapping additional data around the AX.25 frames. This method maintains backward compatibility with AX.25. FX.25 was implemented in SatSim and the simulation results proved that FX.25 was a more reliable protocol than AX.25, as it can communicate at lower elevations and over noisier communication channels. However, the drawback of the additional forward error correction is the increased overhead, which reduces the overall payload data throughput. A modular AX/FX.25 protocol was then implemented in SatSim, to exploit the strengths of both protocols. This hybrid protocol yielded significant improvements to data throughput and can enable future software defined radio or hardware developments. / AFRIKAANSE OPSOMMING: Nano-satelliete word hoofsaaklik gebruik in lae-aard wentelbaan toepassings waar kommunikasietyd beperk is, soms tot minder as een uur per dag. Gepaardgaande met hierdie inherente beperking van lae-aard wentelbane, is daar ook die verminderde omvang en kapasiteit van nano-satelliete, veral ten opsigte van die CubeSat spesifikasie. Effektiewe aanwending van die beperkte tyd en kommunikasie-hulpbronne is dus noodsaaklik. Die keuse van netwerk protokol het ’n beduidende invloed op die betroubaarheid en data deurset van ’n satelliet netwerk. ’n Belangrike voorvereiste vir die ontwerp, vergelyking en verbetering van netwerk-protokolle, is ’n netwerk simulator. Beperkte inligting is tans beskikbaar oor kommunikasie protokolle in nano-satelliet toepassings. Hierdie tesis fokus op die verbetering van nano-satelliet netwerk-simulasie, asook die ontwikkelling van ’n verbeterde netwerk-protokol strategie vir nano-satelliet toepassings. Dit het na vore gekom dat daar ’n leemte is in die beskikbaarheid van simulasie sagteware wat gerig is op die ondersoek van satelliet netwerke. Hierdie waarneming het die ontwikkeling van SatSim genoop. SatSim is ’n diskrete-gebeurtenis netwerk-simulasie sagtewarepakket wat in die Python programmeertaal ontwikkel is om netwerk protokolle te ontwikkel en te analiseer. SatSim was geverifieer deur simulasies te vergelyk met die resultate van ander navorsingspublikasies, wat van verskillende sagtewarepakkette gebruik gemaak het, sowel as teoretiese deursetberekeninge. AX.25 is een van die netwerk protokolle wat mees algemeen in die nano-satelliet bedryf voorkom. AX.25 was geïmplementeer in SatSim en geverifieer met teoretiese deursetberekeninge. AX.25 was gebruik as ’n grondslag om op te verbeter. FX.25 was ontwikkel deur die Stensat Group in ’n poging om op AX.25 te verbeter. FX.25 voeg vorentoefoutkorreksie by tot AX.25, deur addisionele data tot die AX.25 netwerk pakkies te voeg. Hierdie benadering bewerkstellig agteruit-verenigbaarheid met AX.25. FX.25 was geïmplementeer in SatSim en simulasieresultate dui daarop dat FX.25 ’n meer betroubare protokol is as AX.25, omdat dit teen laer elevasiehoeke en oor swakker kommunikasiekanale kan kommunikeer. Die verbeterde betroubaarheid is ten koste van datadeurset, as gevolg van die toevoeging van die vorentoe-foutkorreksiedata. ’n Modulêre AX/FX.25 protokol was geïmplemeteer om te kapitaliseer op die sterk eienskappe van beide protokolle. Hierdie hibriede protokol het ’n beduidende verbetering gelewer ten opsigte van data deurset en kan toekomstige sagteware-gedefinieerde radio en hardewaretoepassings stimuleer.

Seguindo a literatura mais recente sobre o tema, a presente dissertação teve por objetivo aferir as elasticidades da função de oferta brasileira de exportação de soja para a china à variabilidade da taxa de câmbio. Sob o viés que a alta inflação brasileira gera nas variáveis independentes, mais de um recorte para a instrumentalização dos diferentes determinantes foi considerado no design de pesquisa. Este adotoua cointegração por meio da abordagem do teste de Fronteiras de Pesaranpara a especificação concomitante de modelos ARDL(12,12,12,12) e ARDL (8,8,8,8,8) com doze ou oito trimestres-safra defasados, para o período compreendendo o primeiro trimestre de 1999 ao segundo de 2016. A busca por evidências para relações de longo prazo das exportações em toneladas de soja do Brasil para a China se deu em termos dos valores passados destas, bem como dos valores atuais e passados dos preços relativos, da demanda chinesa e da volatilidade cambial. A partir dos resultados destas projeções, o raciocínio sobre a influência da volatilidade cambial sobre as exportações de soja brasileira indica que esta, de fato, é positiva no longo prazo.Já no curto prazo são encontrados efeitos negativos. Assim, o aumento do risco pode diminuiras exportações dentro de um mesmo ano-safra, mas seu impacto é fundamentalmente positivo para o sojicultor. Dessa forma, como preconizado por Schultz (1980) os sojicultores são empreendedores que não são avessos ao risco. Pelo contrário, eles são entusiastas do risco, não apenas por este ser parte importante de suas decisões de investimento e financiamento, mas também porque a volatilidade maior aumenta a utilidade em exportar do sojicultor. / The objective of this dissertation was to assess the elasticity of Brazilian soybean exports to China in terms of the variability - or risk - of the exchange rate. In order to consider the bias of inflation volatility on the assessment of the independent variables, more than one methodology to calculate the different regressors was used. Projections were made using Pesaran´sbounds testapproach to cointegration, through the concomitant specification of ARDL (12,12,12,12) and ARDL(8,8,8,8,8) models consisting of up to twelve or eight lagged quarters- aggregated to the crop calendar- for the period from the first quarter of 1999 to the second quarter of 2016. Elasticity estimations from this approach allowed a search for long-run forcing influence between the regressors and Brazil\'s soybean exports, in terms of past values- in tons- of these, as well as current and past values of relative prices, Chinese demand and exchange rate volatility measures. The results of these projections indicate that an increase in risk has indeed a positiveeffect in the long term, while within the crop-year the effects are found to be negative. Thus, an increase in volatility may decrease exports in the short term, but its impact is fundamentally positive to the soy farmer. Thus, as advocated by Schultz (1980), soybean farmers are entrepreneurs who are not risk averse. On the contrary, they are risk enthusiasts, not only because the bulk of their investment decisions are subject to uncertainty, but also because an increase in volatility increases the utility that a soybean farmer extracts from exports.

This thesis deals with CNB interventions in favor of the exchange rate depreciation of November 2013. The theoretical part presents alternative tools for unconventional monetary policy when zero lower bound is binding. This thesis then describes the experience of other central banks that responded to low interest rates. Intervention of CNB is contextualized in the Czech financial system and previous economic development. The thesis analyses alternative instruments which CNB might have accessed. Based on the analyzed data this thesis concludes that despite the long-term maintenance of weakened Koruna above the level of announced exchange rate pledge the sufficiently loose monetary policy was not translated into desired price increase.

The stochastic volatility of daily foreign exchange (FX) derivatives poses a number of risks for the international banking community. Settlement risk, liquidity risk and capital adequacy are just a few immediate concerns that arise from such volatility. This thesis examines the impact of close-out netting on minimising the stochastic volatility of inter-bank FX derivatives. The problem with close-out netting is that although it is a simple formula of taking the differences between two banks at one point in time, it is the stochastic and volatile nature of FX rates that makes measuring the full impact of netting difficult. The objective of this thesis is to establish a realistic international banking framework or modelling environment in which close-out netting can be scientifically applied and examined. Five international daily FX rates will be used as sufficient approximations for five international banks. A generalised autoregressive conditionally heteroschedastic (GARCH) modelling approach is adopted as a robust and rich FX volatility paradigm. Then through Monte Carlo simulation of the resulting fitted GARCH models, we generate the distributions -with and without close-out netting. The findings of this thesis are interesting, showing that close-out netting is far more than just a simple mathematical process. Netting surely does reduce each bank's exposure to FX volatility, however, its multivariate nature reveals some important results for banking risk research and bank analysts.

This thesis focus on a yield curve modelling. It estimates unobserved "global" yield curve factors which drives changes in individual real yield curves. Yield curves of USD, GBP, JPY and EUR are considered and global factors are able to explain substantial part of their variances. The method is built on the Nelson-Siegel model which is implemented in a state-space form to be able to extract the unobserved yield factors. The estimated global yield factors are further used for explaining the evolution of the Czech yield curve. Their impact to the Czech yield curve is estimated in a time-varying regression which results show that the impact of the global factors is stronger during the years of the interventions of the Czech National Bank and thus suggests that the interventions help to transmit the global low interest rates to the Czech economy.

En utilisant des données haute-fréquence inédites, cette thèse étudie trois types de regroupements (“clusters”) présents dans le marché des changes: la concentration d'ordres sur certains prix, la concentration des transactions dans le temps et l'existence de groupes d'investisseurs prenant les mêmes décisions. Nous commençons par étudier les propriétés statistiques du carnet d'ordres EBS pour les paires de devises EUR/USD et USD/JPY et l'impact d'une réduction de la taille du tick sur sa dynamique. Une grande part des ordres limites est encore placée sur les anciens prix autorisés, entraînant l'apparition de prix-barrières, où figurent les meilleures limites la plupart du temps. Cet effet de congestion se retrouve dans la forme moyenne du carnet où des pics sont présents aux distances entières. Nous montrons que cette concentration des prix est causée par les traders manuels qui se refusent d’utiliser la nouvelle résolution de prix. Les traders automatiques prennent facilement la priorité, en postant des ordres limites un tick devant les pics de volume.Nous soulevons ensuite la question de l'aptitude des processus de Hawkes à rendre compte de la dynamique du marché. Nous analysons la précision de tels processus à mesure que l'intervalle de calibration est augmenté. Différent noyaux construits à partir de sommes d'exponentielles sont systématiquement comparés. Le marché FX qui ne ferme jamais est particulièrement adapté pour notre but, car il permet d’éviter les complications dues à la fermeture nocturne des marchés actions. Nous trouvons que la modélisation est valide selon les trois tests statistiques, si un noyau à deux exponentielles est utilisé pour fitter une heure, et deux ou trois pour une journée complète. Sur de plus longues périodes la modélisation est systématiquement rejetée par les tests à cause de la non-stationnarité du processus endogène. Les échelles de temps d'auto-excitation estimées sont relativement courtes et le facteur d'endogénéité est élevé mais sous-critique autour de 0.8. La majorité des modèles à agents suppose implicitement que les agents interagissent à travers du prix des actifs et des volumes échangés. Certains utilisent explicitement un réseau d'interaction entre traders, sur lequel des rumeurs se propagent, d'autres, un réseau qui représente des groupes prenant des décisions communes. Contrairement à d'autres types de données, de tels réseaux, s'ils existent, sont nécessairement implicites, ce qui rend leur détection compliquée. Nous étudions les transactions des clients de deux fournisseur de liquidités sur plusieurs années. En supposant que les liens entre agents sont déterminés par la synchronisation de leur activité ou inactivité, nous montrons que des réseaux d'interactions existent. De plus, nous trouvons que l'activité de certains agents entraîne systématiquement l’activité d'autres agents, définissant ainsi des relations de type “lead-lag” entre les agents. Cela implique que le flux des clients est prévisible, ce que nous vérifions à l'aide d'une méthode sophistiquée d'apprentissage statistique. / The aim of this thesis is to study three types of clustering in foreign exchange markets, namely in price, trades arrivals and investors decisions. We investigate the statistical properties of the EBS order book for the EUR/USD and USD/JPY currency pairs and the impact of a ten-fold tick size reduction on its dynamics. A large fraction of limit orders are still placed right at or halfway between the old allowed prices. This generates price barriers where the best quotes lie for much of the time, which causes the emergence of distinct peaks in the average shape of the book at round distances. Furthermore, we argue that this clustering is mainly due to manual traders who remained set to the old price resolution. Automatic traders easily take price priority by submitting limit orders one tick ahead of clusters, as shown by the prominence of buy (sell) limit orders posted with rightmost digit one (nine).The clustering of trades arrivals is well-known in financial markets and Hawkes processes are particularly suited to describe this phenomenon. We raise the question of what part of market dynamics Hawkes processes are able to account for exactly. We document the accuracy of such processes as one varies the time interval of calibration and compare the performance of various types of kernels made up of sums of exponentials. Because of their around-the-clock opening times, FX markets are ideally suited to our aim as they allow us to avoid the complications of the long daily overnight closures of equity markets. One can achieve statistical significance according to three simultaneous tests provided that one uses kernels with two exponentials for fitting an hour at a time, and two or three exponentials for full days, while longer periods could not be fitted within statistical satisfaction because of the non-stationarity of the endogenous process. Fitted timescales are relatively short and endogeneity factor is high but sub-critical at about 0.8.Most agent-based models of financial markets implicitly assume that the agents interact through asset prices and exchanged volumes. Some of them add an explicit trader-trader interaction network on which rumors propagate or that encode groups that take common decisions. Contrarily to other types of data, such networks, if they exist, are necessarily implicit, which makes their determination a more challenging task. We analyze transaction data of all the clients of two liquidity providers, encompassing several years of trading. By assuming that the links between agents are determined by systematic simultaneous activity or inactivity, we show that interaction networks do exist. In addition, we find that the (in)activity of some agents systematically triggers the (in)activity of other traders, defining lead-lag relationships between the agents. This implies that the global investment flux is predictable, which we check by using sophisticated machine learning methods.

This thesis describes methods for applying secondary water effects as spray, foam, splashes and mist to a fluid simulation system. For an art direction control over the base fluid flow a Fluid Implicit Particle solver with custom fields is also presented. The methods build upon production techniques within the visual effects industry, fluid dynamics and relevant computer graphics research. The implementation of the methods is created within Side Effects Software Houdini.

This thesis concerns with problematic of FX risk management in a mid-sized export-oriented company. The theoretic part of the paper explains fundamental and origin of FX risk and summarizes process of its management with emphasis on specifics of mid-sized companies. Further, selected hedging techniques and instruments are introduced. With employment of available statistics and analysis, main advantages and disadvantages of hedging are demonstrated. For practical application of theory presented, real data from mid-sized company are used. After analyzing financial and accounting statements, concrete risks arising from exchange rate volatility are identified. Finally, concrete recommendations for the management are offered, which could lead to lowering FX exposure and reducing impact of changes in exchange rates on economy of the firm.

<p>Terrain generation is a convoluted and a popular topic in the VFX industry. Whether you are part of the film/TV or gaming industry, a terrain, is a highly nuanced feature that is usually present. Regardless of walking on a desert like terrain in the film, Blade Runner 2049 or fighting on different planets like in Avatar, 3D terrains is a major part of any digital media. The purpose of this thesis is about developing a workflow for large-scale terrains using complex data sets and utilizing this workflow to maintain a balance between the procedural content and the artistic input made especially for smaller companies which cannot afford an enhanced pipeline to deal with major technical complications. The workflow consists of two major elements, development of the tool used to optimize the workflow and the recording and maintaining of the efficiency in comparison to the older workflow. </p> <p> </p> <p> My research findings indicate that despite the increase in overall computational abilities, one of the many issues that are still present is generating a highly advanced terrain with the added benefits of the artists and users’ creative variations. Reducing the overall time to simulate and compute a highly realistic and detailed terrain is the main goal, thus this thesis will present a method to overcome the speed deficiency while keeping the details of the terrain present.</p>