To achieve economic development, regional authorities have to address issues that relate to climate change, efficient information flow in the market place, and health care. This dissertation presents three essays on current issues of concern to economic development in Africa. Climate change is examined in terms of its effects on the Egyptian agricultural sector; transmission of world price to small scale growers is examined in Uganda; and the benefits of insecticide-treated bed nets use is examined in Africa. In essay I, to address the impact of climate change on the Egyptian agricultural sector under alternative population growth rates, water use and crop yield assumption; the Egyptian Agricultural Sector Model (EASM) is updated and expanded to improve hydrological modeling and used to portray agricultural activity and hydrological flow. The results indicate that climate change will cause damages (costs) to the Egyptian agricultural sector and these will increase over time. Egypt may reduce these future damages by controlling its population growth rate and using water conservation strategies. In essay II, I use vector autoregressive analysis to examine the transmissions of price information to Uganda coffee growers; using monthly coffee price data on retail, futures, farmgate and world prices from 1994 to 2010. Improved transmission of world prices to farmers may increase their decision making to obtain a better market price. Directed acyclic graphs reveal that there is a causal flow of information from the indicator price to the London futures price to the Uganda grower?s price in contemporaneous time. Forecast error variance decomposition indicates that at moving ahead 12 months, the uncertainty in Uganda grower price is attributable to the indicator price (world spot price), own price (farmgate), London future and Spain retail price in rank order. In essay III, the cost of malaria in children under five years and the use of insecticide treated bed nets is examined in the context of 18 countries in Africa. I examine the direct and indirect cost of malaria in children under five years and the benefit of investing in insecticide treated mosquito nets as a preventative strategy in 18 African countries. The results indicate that the use of mosquito treated nets reduces the number of malaria cases in children; and this can induce 0.5% reduction in outpatient treatment costs, 11% reduction in inpatient treatment costs, 11% reduction in productivity loss, and 15% reduction in disability adjusted life years (DALY) annually.

Europe is in the midst of its deepest crisis since the 1930s where unsustainable debt-to-GDP levels are among the most alarming issues. It is so critical that it is unsure if the Euro can be saved. The risk of moral hazard increases within EMU when governments are taking too much risk in their public debt policies due to the anticipation that ECB or other Member States would eventually bail them out. Moreover, the SGP imposes restrictions on government deficits and debts but have previously failed to enforce them. The weakness seen in the past is that no sanctions have been put in place once the limits have been breached and the SGP is therefore incredible. Previous research on common pool and debt spillovers in a monetary union point to an upward drift of public debt as countries join the EMU. Does this argument hold true? In order to find out, 25 OECD countries between the years of 1995 and 2010 are analyzed using System GMM Arellano-Bover/Blundell-Bond one-step estimator. The primary balance, the interest payments, and GDP growth are regressed respectively in order to see through what channel EMU displays its effect. One regression will cover the entire time period and another will only cover the years from 1995 to 2007 in order to isolate the effects of the current crisis. The results, based on the years over the entire time period (including the crisis) suggest that the effect of an EMU Membership goes via the Interest payments which it is connected to positively. By using the equation of debt dynamics, the fact that net debt interest payments are higher for a country within EMU indicates, all else equal, that they have on average higher levels of debt. Nevertheless, this realization might be a crisis phenomenon and the implication of this is not clear. However more importantly, the regressions based on the years of 1995 and 2007 (prior to the crisis) did not display any significant results. These results indicate that there is no significant relationship between a country’s membership in EMU and its level of debt prior to the crisis.

This study examines the comparative impact of multilateral trade agreements on intra-regional trade in the Southern African Development Community (SADC) and the Economic Community of West African States (ECOWAS) regions in Africa. Annual data was gathered from 2000 to 2018 and dynamic panel data and econometric techniques were used to control for individual country characteristics, endogeneity, serial correlation, heteroscedasticity and interdependencies between the countries in each region. Two estimations were done, one using the tariff measures of multilateral agreements, the second using non-tariff measures of multilateral agreement. The results of the empirical analysis show that the SADC region has a slight edge over ECOWAS in terms of technological progress and investment, especially in trade infrastructure. However, the ECOWAS levels of employment and economic growth are higher than those in the SADC region. These differences further translate into differences that drive intra-African trade in these regions, and how they relate to the role of multilateral agreements in intra-African trade in each of these regions. While technology and investment are key drivers and enhancers of intra-African trade in SADC countries, economic growth and employment stand out as key enhancers of intra-African trade in ECOWAS, especially where multilateral agreement is represented by tariff measures. This study reports that when non-tariff measures are used to represent multilateral agreements, export trade costs, in addition to investment and technology, are the key drivers of intra-African trade in SADC countries. For ECOWAS, under non-tariff measures of multilateral agreements, only economic growth drives intra-African trade. / Business Management / D. Phil. (Business Management)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Diseases and environment are closely related, especially with regard to air temperature and relative humidity. The weather data tend to follow a daily pattern of temporal variation, which derives mainly from the daily variation of the surface radiation balance. Based on this, this study aimed to make a qualitative and quantitative description of the database of the Automatic Meteorological Station of the Instituto Nacional de Meteorologia (INMET) in Santa Maria, RS, determine the hours of greatest frequency of occurrence of daily extreme air temperatures in Santa Maria, develop models to estimate hourly values of air temperature (T) and relative humidity (RH), based on values measured in "UTC standard times" and on the daily minimum air temperature and to determine the risk of fungal diseases occurrence during the developmental cycle of potato in different planting dates, using the Blitecast forecasting system. Models were fitted to estimate air T and partial vapor pressure of water at different times of the day. RH was indirectly obtained from partial vapor pressure of water and saturation vapor pressure, calculated from estimated T values. The database of Principal Climatological Station of Santa Maria was transformed to an hourly estimated T and RH database and the Blitecast's calculated severity values (CSV) were obtained for 14 planting dates in 43 years. The automatic weather station of Santa Maria, RS, belonging to INMET, shows 90.1% of the days of flawless data records in 10 years, from 2002 to 2011. The minimum daily air temperature in Santa Maria occurs more frequently at 09AM UTC, corresponding to 6AM on local official time, from September to February. From March through August, this time is delayed, and its occurrence to be more frequent at 10 h UTC. The precision of the estimates ranged from 0.7 ºC to 1.5 ºC, with average deviation of 0.65 °C for T and 0.7 % to 1.2 %, with average deviation of up to 4% for RH depending on the time. Potato crops during the Fall growing season require on average 54% more fungicide applications compared to the Spring season. In the Spring growing season the most probable number of sprayings ranged from two to four and from six to seven in the Fall growing season. Potato crops planted in August and March were demanded a lower economic, ecological and farmer health cost in crop protection against late blight than earlier crops (July and February). / Doenças e ambiente estão intimamente relacionados, especialmente no que se refere à temperatura e umidade relativa do ar. Os elementos meteorológicos tendem a seguir um padrão de variação temporal diária, que deriva principalmente da variação diária do balanço de radiação da superfície. Com base nisso, o objetivo desse trabalho foi descrever qualitativa e quantitativamente do banco de dados da Estação Meteorológica Automática do Instituto Nacional de Meteorologia de Santa Maria (INMET), determinar os horários de maior frequência de ocorrência das temperaturas extremas diárias do ar em Santa Maria, desenvolver modelos para estimativa dos valores horários de temperatura (T) e umidade relativa do ar (UR) e determinar o risco de ocorrência de requeima no ciclo de desenvolvimento da batata, em diferentes datas de plantio. Foram ajustados modelos analíticos para estimativa da T e da pressão parcial de vapor no ar nos diferentes horários do dia. A UR foi obtida indiretamente, com base nos valores de pressão parcial de vapor no ar estimados e nos valores de pressão de saturação de vapor no ar, calculados com base na T estimada. O banco de dados da Estação Climatológica Principal de Santa Maria foi transformado em um banco de dados horários estimados de T e UR e foram obtidos os valores de severidade calculada (VSC) pelo sistema Blitecast em 14 datas de plantio da batata em 43 anos agrícolas. A estação meteorológica automática de Santa Maria, RS, pertencente ao INMET, apresenta 90,1% dos dias sem falhas de registros de dados em 10 anos, de 2002 a 2011. A temperatura mínima diária do ar em Santa Maria ocorreu com maior frequência às 09 h UTC, correspondendo às 06 h no horário oficial local, nos meses de setembro a fevereiro. De março até agosto, esse horário é atrasado, sendo a sua ocorrência mais frequente às 10 h UTC. A precisão das estimativas variou de 0,7 oC a 1,5 oC, com desvio médio de até 0,65oC para T do ar e de 0,7 % a 1,2 %, com desvio médio de até 4 %, para UR, dependendo do horário. Cultivos de batata no período de safrinha necessitam, em média, de um número 54 % maior de aplicações de fungicida em relação ao período de safra. Na safra o número mais provável de pulverizações oscila entre duas e quatro e na safrinha entre seis e sete. Plantios de batata realizados em agosto e em março exigiram um menor custo econômico, ecológico e de saúde do produtor na proteção da cultura contra a requeima do que plantios mais precoces (julho e fevereiro).

One of the major applications of wireless sensor networks is to sense accurate and reliable data from the physical environment with or without a priori knowledge of data statistics. To extract accurate data from the physical environment, we investigate spatial data correlation among sensor nodes to develop data accuracy models. We propose three data accuracy models namely Estimated Data Accuracy (EDA) model, Cluster based Data Accuracy (CDA) model and Distributed Cluster based Data Accuracy (DCDA) model with a priori knowledge of data statistics. Due to the deployment of high density of sensor nodes, observed data are highly correlated among sensor nodes which form distributed clusters in space. We describe two clustering algorithms called Deterministic Distributed Clustering (DDC) algorithm and Spatial Data Correlation based Distributed Clustering (SDCDC) algorithm implemented under CDA model and DCDA model respectively. Moreover, due to data correlation in the network, it has redundancy in data collected by sensor nodes. Hence, it is not necessary for all sensor nodes to transmit their highly correlated data to the central node (sink node or cluster head node). Even an optimal set of sensor nodes are capable of measuring accurate data and transmitting the accurate, precise data to the central node. This reduces data redundancy, energy consumption and data transmission cost to increase the lifetime of sensor networks. Finally, we propose a fourth accuracy model called Adaptive Data Accuracy (ADA) model that doesn't require any a priori knowledge of data statistics. ADA model can sense continuous data stream at regular time intervals to estimate accurate data from the environment and select an optimal set of sensor nodes for data transmission to the network. Data transmission can be further reduced for these optimal sensor nodes by transmitting a subset of sensor data using a methodology called Spatio-Temporal Data Prediction (STDP) model under data reduction strategies. Furthermore, we implement data accuracy model when the network is under a threat of malicious attack.

This study examines the fundamental determinants of bilateral trade flows between South Africa and BRIC countries. This is done by exploring the magnitude of exports among these countries. The Gravity model approach is used as the preferred theoretical framework in explaining and evaluating successfully the bilateral trade flows between South Africa and BRIC countries The empirical part of this study uses panel data methodology covering the time period 2000-2012 and incorporates the five BRICS economies in the sample. The results of the regressions are subject to panel diagnostic test procedures. The study reveals that, on the one hand, there are positive and significant relationships between South African export flows with the BRICs and distance, language dummy, the BRICs’ GDP, the BRICs’ openness and population in South Africa. On the other hand, GDP in South Africa, real exchange rate and time dummy are found to be negatively related to export flows. / Economics / M. Com. (Economics)

觀光產業為現在世界主要產業之一，稱之為「無煙囪產業」，因其汙染少且外部成本相較許多工業產業來的低，許多國家都致力於發展觀光業，投入許多政策吸引觀光客到訪。我國政府近年來也推動許多政策是針對外籍旅客觀光計畫。如民國92年的「觀光客倍增計畫」預期於2008年達成目標，於是在同年於「觀光發展條例」中增訂的「外籍旅客購物退稅」，外籍旅客購物退稅的實施更是發展觀光產業的重要措施之一，觀光產業在觀光較為發達的已開發國家中，都十分重視旅客購物退稅這項措施，臺灣政府於民國92年實施政策至今，經歷了幾次重大改制，本文致力於研究於民國100年7月實施的「現場小額退稅」措施，是否對來臺外籍旅客的消費行為有顯著影響，並對今年實施的新制退稅措施是否再次影響旅客消費意願作出預期。 本研究以外籍旅客國籍及其消費金額之追蹤資料進行迴歸分析，蒐集位於臺北市區的某特定營業人2009年8月至2015年12月的外籍旅客退稅資料，針對來自七個國家及地區的外籍遊客消費行為建立來臺觀光需求模型。以政府實施的「現場小額退稅」措施當作主要的政策變數，並選取幾個影響旅客需求的重要變數為控制變數，建立以旅客總消費量、平均消費量、特定營業人之營業額為因變數的三個模型，觀察政策變數及其他控制變數對於外籍旅客消費行為的影響。 以全體樣本實證結果發現，本政策變動對於旅客總消費量、商店之營業額均有顯著正向影響，對於旅客平均消費量也是正面的影響；本文也將七個國家及地區分別討論，以美國、日本及中國旅客對於政策效果的影響最為顯著且正向，其他國家雖不顯著但多為正向關係。顯見政策的推動確實有助於提升外籍旅客來臺及消費意願，對發展臺灣觀光旅遊產業是一項助益。 / According to UNWTO, tourism industry has experienced continuous growth and become one of the fastest growing economic sectors in the world. Many countries have committed themselves to developing tourism industry nowadays due to lower externality. Taiwanese government also has some implemented plans on tourism industry of which foreigners are allowed to apply for “VAT Refund”, hoping that the increase in international tourist may give the economy a boost. Our study has conducted an empirical analysis on the policy of On-Site Small Amount Tax Refund, which is mainly concentrated in panel data estimation. The purpose of this thesis is to find out the effect of this policy. First, we use Dummy variable as a main variable to capture the influence of the policy. Second, we introduce both the demand factors and the supply factors to explain tourism spending in Taiwan. The span of the data is from August 2009 to December 2015, using Tax Refund data of foreigners from 7 countries and districts. Our empirical analysis show that the Tax Refund policy has had significantly positive effect on both dependent variables, including total consumption and store revenue, especially these from U.S.A., Japan and China. These three countries show the strongest response to the dependent variables. It also shows that implementation of this Tax Refund policy really contributes to our tourism industry by increasing international tourism receipts of Taiwan.

Les fluctuations économiques représentent les mouvements de la croissance économique. Celle-ci peut connaître des phases d'accélération (expansion) ou de ralentissement (récession), voire même de dépression si la baisse de production est persistente. Les fluctuations économiques sont liées aux écarts entre croissance effective et croissance potentielle. Elles peuvent s'expliquer par des chocs d'offre et demande, ainsi que par le cycle du crédit. Dans le premier cas, les conditions de la production se trouvent modifiées. C'est le cas lorsque le prix des facteurs de production (salaires, prix des matières premières) ou que des facteurs externes influençant le prix des produits (taux de change) évolue. Ainsi, une hausse du prix des facteurs de production provoque un choc négatif et ralentit la croissance. Ce ralentissement peut être également dû à un choc de demande négatif provoqué par une hausse du prix des produits causée par une appréciation de la devise, engendrant une diminution des exportations. Le deuxième cas concerne les variables financières et les actifs financiers. Ainsi, en période d'expansion, les agents économiques s'endettent et ont des comportements spéculatifs en réaction à des chocs d'offre ou demande anticipés. La valeur des titres et actifs financiers augmente, provoquant une bulle qui finit par éclater et provoquer un effondrement de la valeur des biens. Dès lors, l'activité économique ne peut plus être financée. C'est ce qui génère une récession, parfois profonde, comme lors de la récente crise financière. Cette thèse inclut trois essais sur les fluctuations macroéconomiques et les cycles économiques, plus précisément sur les thèmes décrit ci-dessus. Le premier chapitre s'intéresse aux anticipations sur la politique monétaire et sur la réaction des agents écononomiques face à ces anticipations. Une emphase particulière est mise sur la consommation de biens durables et l'endettement relié à ce type de consommation. Le deuxième chapitre aborde la question de l'influence des variations du taux de change sur la demande de travail dans le secteur manufacturier canadien. Finalement, le troisième chapitre s'intéresse aux retombées économiques, parfois négatives, du marché immobilier sur la consommation des ménages et aux répercussions sur le prix des actifs immobiliers et sur l'endettement des ménages d'anticipations infondées sur la demande dans le marché immobilier. Le premier chapitre, intitulé ``Monetary Policy News Shocks and Durable Consumption'', fournit une étude sur le lien entre les dépenses en biens durables et les chocs monétaires anticipés. Nous proposons et mettons en oeuvre une nouvelle approche pour identifier les chocs anticipés (nouvelles) de politique monétaire, en les identifiant de manière récursive à partir des résidus d’une règle de Taylor estimée à l’aide de données de sondage multi-horizon. Nous utilisons ensuite les chocs anticipés inférer dans un modèle autorégressif vectoriel structurel (ARVS). L’anticipation d’une politique de resserrement monétaire mène à une augmentation de la production, de la consommation de biens non-durables et durables, ainsi qu’à une augmentation du prix réel des biens durables. Bien que les chocs anticipés expliquent une part significative des variations de la production et de la consommation, leur impact est moindre que celui des chocs non-anticipés sur les fluctuations économiques. Finalement, nous menons une analyse théorique avec un modèle d’équilibre général dynamique stochastique (EGDS) avec biens durables et rigidités nominales. Les résultats indiquent que le modèle avec les prix des biens durables rigides peut reproduire la corrélation positive entre les fonctions de réponse de la consommation de biens non-durables et durables à un choc anticipé de politique monétaire trouvées à l’aide du ARVS. Le second chapitre s'intitule ``Exchange Rate Fluctuations and Labour Market Adjustments in Canadian Manufacturing Industries''. Dans ce chapitre, nous évaluons la sensibilité de l'emploi et des heures travaillées dans les industries manufacturières canadiennes aux variations du taux de change. L’analyse est basée sur un modèle dynamique de demande de travail et utilise l’approche en deux étapes pour l'estimation des relations de cointégration en données de panel. Nos données sont prises d’un panel de 20 industries manufacturières, provenant de la base de données KLEMS de Statistique Canada, et couvrent une longue période qui inclut deux cycles complets d’appréciation-dépréciation de la valeur du dollar canadien. Les effets nets de l'appréciation du dollar canadien se sont avérés statistiquement et économiquement significatifs et négatifs pour l'emploi et les heures travaillées, et ses effets sont plus prononcés dans les industries davantage exposées au commerce international. Finalement, le dernier chapitre s'intitule ``Housing Market Dynamics and Macroprudential Policy'', dans lequel nous étudions la relation statistique suggérant un lien collatéral entre le marché immobilier and le reste de l'économique et si ce lien est davantage entraîné par des facteurs de demandes ou d'offres. Nous suivons également la littérature sur les chocs anticipés et examinons un cyle d'expansion-récession peut survenir de façon endogène la suite d'anticipations non-réalisées d'une hausse de la demande de logements. À cette fin, nous construisons un modèle néo-Keynésien au sein duquel le pouvoir d’emprunt du partie des consommateurs est limité par la valeur de leur patrimoine immobilier. Nous estimons le modèle en utilisant une méthode Bayésienne avec des données canadiennes. Nous évaluons la capacité du modèle à capter les caractéristiques principales de la consommation et du prix des maisons. Finalement, nous effectuons une analyse pour déterminer dans quelle mesure l'introduction d'un ratio prêt-à-la-valeur contracyclique peut réduire l'endettement des ménages et les fluctuations du prix des maisons comparativement à une règle de politique monétaire répondant à l'inflation du prix des maisons. Nous trouvons une relation statistique suggérant un important lien collatéral entre le marché immobilier et le reste de l'économie, et ce lien s'explique principalement par des facteurs de demande. Nous constatons également que l'introduction de chocs anticipés peut générer un cycle d'expansion-récession du marché immobilier, la récession faisant suite aux attentes non-réalisées par rapport à la demande de logements. Enfin, notre étude suggère également qu'un ratio contracyclique de prêt-à-la-valeur est une politique utile pour réduire les retombées du marché du logement sur la consommation par l'intermédiaire de la valeur garantie. / Economic fluctuations represent the movements of economic growth. It may experience acceleration phases (expansion) or deceleration (recession), and even depression if the decline in production is persistent. Economic fluctuations are related to differences between actual growth and potential growth. They can be explained by supply and demand shocks, as well as by the credit cycle. In the first case, the conditions of production are modified. This is the case when the price of production factors (wages, raw materials prices) or external factors influencing the price of products (exchange rate) evolve. Thus, an increase in the price of production factors causes a negative shock and slows growth. This slowdown may also be due to a negative demand shock caused by an increase in product prices caused by a currency appreciation, causing a decrease in exports. The second case concerns the financial variables and financial assets. Thus, in a period of expansion, economic agents borrow more and have speculative behaviors in response to anticipated supply and demand shocks. The value of securities and financial assets increases, causing a bubble that eventually burst, causing a collapse in the value of assets. Therefore, economic activity cannot be funded. This is what generates a recession, sometimes profound, as in the recent financial crisis. This thesis includes three essays on macroeconomic fluctuations and economic cycles, specifically on the topics described above. The first chapter deals with expectations about monetary policy and on the reaction of econonomic agents on these expectations. A particular emphasis is placed on the consumption of durable goods and indebtedness related to this type of consumption. The second chapter discusses the influence of fluctuations in foreign exchange rates on labour demand in the Canadian manufacturing sector. Finally, the third chapter focuses on spillover, sometimes negative, of the real estate market on household consumption and the impact on property prices and household debt of demand expectations in the property market. The first chapter, entitled ``Monetary Policy News Shocks and Durable Consumption'', provides insight on the link between durable goods spending and monetary policy news shocks. We propose and implement a new approach to identifying news shocks about future monetary policy. News shocks are identified recursively from the residuals of a monetary policy rule estimated using U.S. multi-horizon survey data. We then use those inferred news shocks in a structural VAR (SVAR). An expected monetary policy tightening leads to an increase in output, non-durable and durable goods consumption, and real price of durable goods. Although news shocks account for a significant fraction of output and consumption fluctuations, they contribute less than surprise shocks to economic fluctuations. We then carry out theoretical analysis using a dynamic stochastic general equilibrium (DSGE) model with durable goods and nominal rigidities. Results indicate that a model with sticky durable goods price can reproduce the positive correlation between the response functions of durable and non-durable goods consumption to policy news shocks that was found from the SVAR. The second chapter is entitled ``Exchange Rate Fluctuations and Labour Market Adjustments in Canadian Manufacturing Industries''. In this chapter, we estimate the impact of exchange rate fluctuations on hours worked and jobs in Canadian manufacturing industries. The analysis is based on a dynamic model of labour demand and the econometric strategy employs a panel two-step approach for cointegrating regressions. Our data is drawn from a panel of 20 manufacturing industries, from Statistics Canada's KLEMS database, and covers a long sample period that includes two full exchange rate appreciation and depreciation cycles. We find that exchange rate fluctuations have economically and statistically significant effects on the labour decisions of Canadian manufacturing employers, and that these effects are stronger for trade-oriented industries. Finally, the last chapter, entitled ``Housing Market Dynamics and Macroprudential Policy'', studies the statistical evidence suggesting a collateral link between the housing market and the rest of the economy and if the link is more demand- or supply-driven. We also followed the \textit{news shocks} literature and look if a housing-market boom-bust can arise endogenously following unrealized expectations of a rise in housing demand. To this end, we construct a New Keynesian model in which a fraction of households borrow against the value of their houses. We estimate the model with Canadian data using Bayesian methods. We assessed the model's ability to capture key features of consumption and house price data. Finally, we performed an analysis to determine how well the introduction of a countercyclical loan-to-value (LTV) ratio can reduced household indebtedness and housing price fluctuations compare to a monetary policy rule augmented with house price inflation. We find statistical evidence suggesting an important collateral link between the housing market and the rest of the economy, and this link is mainly driven by demand factors. We also find that the introduction of news shocks can generate a housing market boom-bust cycle, the bust following unrealized expectations on housing demand. Finally, our study also suggests that a countercyclical loan-to-value ratio is a useful policy to reduce the spillover from housing market to consumption via the collateral value.

L'objectif de cette thèse est d'étudier le problème de la détection de données dans le système de communication sans fil, à la fois pour le cas de l'information d'état de canal parfaite et imparfaite au niveau du récepteur. Comme on le sait, la complexité de MLSE est exponentielle en la mémoire de canal et la cardinalité de l'alphabet symbole est rapidement ingérable, ce qui force à recourir à des approches sousoptimales. Par conséquent, en premier lieu, nous proposons une nouvelle égalisation itérative lorsque le canal est inconnu à l'émetteur et parfaitement connu au niveau du récepteur. Ce récepteur est basé sur une approche de continuation, et exploite l'idée d'approcher une fonction originale de coût d'optimisation par une suite de fonctions plus dociles et donc de réduire la complexité de calcul au récepteur.En second lieu, en vue de la détection de données sous un canal dynamique linéaire, lorsque le canal est inconnu au niveau du récepteur, le récepteur doit être en mesure d'effectuer conjointement l'égalisation et l'estimation de canal. De cette manière, on formule une représentation de modèle état-espace combiné du système de communication. Par cette représentation, nous pouvons utiliser le filltre de Kalman comme le meilleur estimateur des paramètres du canal. Le but de cette section est de motiver de façon rigoureuse la mise en place du filltre de Kalman dans l'estimation des sequences de Markov par des canaux dynamiques Gaussien. Par la présente, nous interprétons et explicitons les approximations sous-jacentes dans les approaches heuristiques.Enfin, si nous considérons une approche plus générale pour le canal dynamique non linéaire, nous ne pouvons pas utiliser le filtre de Kalman comme le meilleur estimateur. Ici, nous utilisons des modèles commutation d’espace-état (SSSM) comme modèles espace-état non linéaires. Ce modèle combine le modèle de Markov caché (HMM) et le modèle espace-état linéaire (LSSM). Pour l'estimation de canal et la detection de données, l'approche espérance et maximisation (EM) est utilisée comme approche naturelle. De cette façon, le filtre de Kalman étendu (EKF) et les filtres à particules sont évités. / The aim of this thesis is to study the problem of data detection in wireless communication system, for both case of perfect and imperfect channel state information at the receiver. As well known, the complexity of MLSE being exponential in the channel memory and in the symbol alphabet cardinality is quickly unmanageable and forces to resort to sub-optimal approaches. Therefore, first we propose a new iterative equalizer when the channel is unknown at the transmitter and perfectly known at the receiver. This receiver is based on continuation approach, and exploits the idea of approaching an original optimization cost function by a sequence of more tractable functions and thus reduce the receiver's computational complexity. Second, in order to data detection under linear dynamic channel, when the channel is unknown at the receiver, the receiver must be able to perform joint equalization and channel estimation. In this way, we formulate a combined state-space model representation of the communication system. By this representation, we can use the Kalman filter as the best estimator for the channel parameters. The aim in this section is to motivate rigorously the introduction of the Kalman filter in the estimation of Markov sequences through Gaussian dynamical channels. By this we interpret and make clearer the underlying approximations in the heuristic approaches. Finally, if we consider more general approach for non linear dynamic channel, we can not use the Kalman filter as the best estimator. Here, we use switching state-space model (SSSM) as non linear state-space model. This model combines the hidden Markov model (HMM) and linear state-space model (LSSM). In order to channel estimation and data detection, the expectation and maximization (EM) procedure is used as the natural approach. In this way extended Kalman filter (EKF) and particle filters are avoided.

This study examines the fundamental determinants of bilateral trade flows between South Africa and BRIC countries. This is done by exploring the magnitude of exports among these countries. The Gravity model approach is used as the preferred theoretical framework in explaining and evaluating successfully the bilateral trade flows between South Africa and BRIC countries The empirical part of this study uses panel data methodology covering the time period 2000-2012 and incorporates the five BRICS economies in the sample. The results of the regressions are subject to panel diagnostic test procedures. The study reveals that, on the one hand, there are positive and significant relationships between South African export flows with the BRICs and distance, language dummy, the BRICs’ GDP, the BRICs’ openness and population in South Africa. On the other hand, GDP in South Africa, real exchange rate and time dummy are found to be negatively related to export flows. / Economics / M. Com. (Economics)