This paper deals with the integration of Walras' law into Keynesian macroeconomics and the attempts at a consistent specification of period models (beginning- vs. end-of-period-equilibrium). Three examples are examined where neglect of a consistent specification led to erroneous results: (1) the identification of the IS-condition with equilibrium of the "flow market" for bonds, (2) superficial treatments of the liquidity trap, and (3) the assumptions on the stochastic structure of monetary and real shocks in determining the optimal monetary instrument. (author's abstract) / Series: Department of Economics Working Paper Series

Thesis (M.Com. (Economics))--North-West University, Potchefstroom Campus, 2008.

Thesis (M.Com. (Economics))--North-West University, Potchefstroom Campus, 2008.

South Africa's North West Province is dependent on gold and platinum exports for its economic growth and employment. Whether this specialisation is optimal from an economic growth, employment creation and welfare point of view, or whether greater export diversification should be encouraged, can most appropriately be evaluated using a general equilibrium framework. Moreover, the answer of whether such specialisation or rather diversification is appropriate may differ depending on the spatial level of analysis that is taken. For instance, export diversification or specialisation on a national level might differ from export diversification or specialisation on sub-national (e.g. provincial) level. A general equilibrium framework is most appropriate for investigating the potential differences between these levels as it takes into consideration a region's economic structure, and the economy-wide linkages between demand, supply, production structure and income distribution. In this light this thesis proposes a regional applied general equilibrium (RAGE) model for the North West Province to address these issues. The question asked is, how can a RAGE model be formulated and implemented for the North West Province of South Africa in order to study the differential impacts of greater export specialisation versus greater export diversification? In answering this question this thesis provides policy makers at regional/provincial level with access to a potentially useful modelling tool, to analyse regional economic issues; it contributes to better understanding the spatial concentration and spatial dynamics of economic activity in the North West Province; and contributes toward the practical policy debate in South Africa. This thesis reviews the literature on export diversification and specialisation, by investigating the extent of export diversification and specialisation in the North West Province over the period 1995-2006 and its relationship to GDP per capita, and using a RAGE model to investigate the economy-wide impacts of greater export diversification versus greater export speciaRsation. These results are contrasted by investigating the economy-wide impacts of greater export diversification versus greater export specialisation on the national level, using a country-wide applied general equilibrium (AGE) model for South Africa. It is found that greater export diversification results in a more substantial increase in exports (of between 0.95 and 1.73 per cent) than in the case of greater export specialisation. In fact it was found that if the North West Province were to specialise in mining exports, such exports would need to grow or increase from the base year by approximately 78 per cent (with no increase in the export demand for other sectors) to result in the same level of growth of total export volumes as is found under export diversification. Avenues for further research are identified. These are a need for more research on elasticities and parameters at regional level, an expansion of the transport services sector in the model, incorporating Tourism Satellite Accounts, BEE and SMME aspects into the model, etc. In conclusion, the thesis implemented the first provincial regional applied general equilibrium model for South Africa, and illustrated that it can make an important contribution to the policy debate on a provincial level in South Africa. The construction of Social Accounting Matrices (SAMs) for all of South Africa's provinces, and the maintenance of these provincial databases could therefore make further contributions to the quantitative assessment of policy options facing government on both the national and provincial level. / Thesis (Ph.D. (Economics))--North-West University, Potchefstroom Campus, 2008.

This thesis consists of five chapters, based on four different articles. All of them are devoted to different aspects of spatial heterogeneity and its impact on economic equilibrium in space. The concept of heterogeneous continuous space is discussed in the introductory chapter.The first model "Equilibrium in Continuous Space under Decentralized Production" addresses the issue of the impact of differences across locations in exogeneous productivity on the structure of equilibrium prices, production and trade. The goal is to describe the general equilibrium in a spatially decentralized economy, when production, consumption and markets are distributed in continuous space and transportation costs are essentially linear. It is shown that an autarky equilibrium can exist only if transport costs are high enough. In the general case, the general equilibrium in this model includes some endogeneously determined trade areas, with flows of goods across space, and autarky areas where production and consumption activities take place only at the same point. An analytical solution in explicit functions is obtained; it contains equilibrium prices, labor supply and flows of goods as functions of the spatial variable. The model can be applied to a set of practical questions in regional economics. In particular, it is able to describe persistent price differentials across regions and non-local consequences of road construction and transportation cost shocks for the economy. The differences across locations in population density may have either historical or economic reasons.The second model "Hotelling's Revival" extends a well-known research of H.Hotelling (1929) to the two-dimensional case with spatially heterogeneous demand density, preserving the rest of his classical assumptions. It is shown that the problem of demand discontinuity in the one-dimensional model, which was discovered by d'Aspremont, Gabszewich and Thisse (1979), disappears in this case. This also holds for any bounded distribution of consumers on any compact set on a plane, which can describe real geographical situations. Demand continuity still holds for any transport costs, strictly increasing in distance and not necessarily linear. Although this is sufficient for the existence of Nash equilibrium in mixed strategies, in pure strategies it exists only for some subset of cases. Examples of both existence and non-existence are constructed, and for some family of densities the separation point between the two cases is found.The third model addresses locational choice of heterogeneous consumers, when land is also heterogeneous in quality. It is based on two articles. The first, "Dacha Pricing", is presented in chapter 4 and studies the problem of locational rent in a city-neighbourhood when utility includes both the impact of transport costs and time for transportation. For the case of identical agents the problem is solved explicitly and comparative statics with respect to exogeneous changes in transport cost and speed is studied. For the case of agents who are heterogeneous with respect to their income, a solution is also obtained. The model explains some evidence about dacha pricing in Russia and its dynamics during the transition period. The second article related to this model is "Location and Land Size Choice by Heterogeneous Agents". It generalizes the first one and form a separate chapter 5. A new approach about the general equilibrium allocation of heterogeneous divisible good (like land) among a continuum of heterogeneous consumers is proposed. The model is based on continuity of primitives which allow not only to finding a general equilibrium solution in a class of continuous functions, but also to treat the solution to a continuous problem as the limit of the corresponding sequence of discrete problems. This solves one of Berliant's paradoxes, related to spatial economics. The multiplicity of equilibria is shown to take place.

Orientador: Maria Alvina Krahenbuhl / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-08T18:45:17Z (GMT). No. of bitstreams: 1 Silva_LucianaYumiAkisawa_M.pdf: 3646991 bytes, checksum: ba62402781e91d287e8cc031d8f12f30 (MD5) Previous issue date: 2007 / Resumo: No projeto de processos de separação é essencial o conhecimento do comportamento das fases que estão em equilíbrio. O presente trabalho consistiu no estudo do equilíbrio de fases de misturas contendo acetona, água e cumeno. Estes componentes são de grande importância para a indústria do fenol. Os componentes água e cumeno são parcialmente miscíveis e na destilação da mistura de acetona, água e cumeno ocorre a formação de três fases (líquido-líquido-vapor), por isso é muito importante a determinação de um único conjunto de parâmetros dos modelos de GE que possa representar adequadamente o equilíbrio líquido-líquido simultaneamente. Determinou-se dados de equilíbrio líquido-vapor dos sistemas acetona + água,acetona + cumeno e acetona + água+ cumeno e dados de equilíbrio líquido-líquido do sistema água + cumeno a 760 mmHg. O Princípio da Máxima Verossimilhança foi utilizado no ajuste dos parâmetros de interação binária dos modelos NRTL e UNIQUAC.Os parâmetros obtidos neste trabalho foram comparados em trabalho anterior,Mafra (2005,) no qual se procedeu ao ajuste de dados ternários de equilíbrio líquido-líquido a 50 °C, e buscou-se o conjunto de parâmetros que melhor representa o equilíbrio líquido-vapor e líquido-líquido simultaneamente. Os resultados obtidos revelaram que o modelo NRTL com parâmetros determinados a partir de dados binários representa satisfatoriamente os equilíbrios líquido-vapor e líquido-líquido de sistemas binários e ternário envolvendo acetona, água e cumeno / Abstract: On projecting separation processes it is essential the knowledge of the behavior of the phases in equilibrium. The present work involved the study of the phase equilibrium of mixtures containing acetone, water and cumene, which are very important in the phenol industry. The components water and cumene are partially miscible, and in the distillation of the mixture of acetone, water and cumene occurs the simultaneous formation of three phases, two liquids and one vapor. In such a way this it is important the determination of only one set of parameters for GE models that can represent appropriately the vapor-liquid and liquid-liquid equilibrium. It has been determined vapor-liquid equilibrium data of acetone + water, acetone + cumene and acetone + water -"o cumene systems and liquid-liquid equilibrium data of water + cumene system at 760 mmHg. The Maximum Likelihood Principle was used for the estimation of the interaction parameters for the NRTL and UNIQUAC models. The parameters obtained in this work were compared with the parameters found by Mafra (2005). who realized the reduction of ternary liquid-liquid equilibrium data at 50°C. and it has been analyzed which set of parameters gives the best representation of the vapor-liquid and the liquid-liquid equilibrium simultaneously. The results have shown that the NRTL model with parameters determined by binary data represents properly the vapor-liquid and liquid-liquid equilibrium of binary and ternary systems containing acetone, water and cumene / Mestrado / Desenvolvimento de Processos Químicos / Mestre em Engenharia Química

Orientadores: Reginaldo Guirardello, Gustavo Paim Valença / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-11T21:02:10Z (GMT). No. of bitstreams: 1 Silva_ConsueloCristinaGomes_D.pdf: 880306 bytes, checksum: 03591a26f7fd91be754c07ee7eae34c7 (MD5) Previous issue date: 2008 / Resumo: Essa pesquisa consiste em aplicar métodos de otimização global para o cálculo do equilíbrio químico e de fases combinados para misturas com gás de síntese. O gás de síntese tem grande interesse industrial, pelas inúmeras possibilidades de produção de diversos compostos químicos. Dessa forma, é fundamental conhecer as condições termodinâmicas que favoreçam a obtenção de determinado produto. A aplicação de métodos de otimização global é de grande interesse para a determinação do equilíbrio, uma vez que permite realizar em um único procedimento o cálculo de equilíbrio e a análise de estabilidade de fases. Como estudos de caso, o método é aplicado em um conjunto de situações que consiste em 280 compostos em potencial que geram como produtos: o gás de síntese a partir do metano e vapor d¿água ¿ já que os reatores operam em condições próximas ao equilíbrio; a produção de hidrocarbonetos e a produção de metanol a partir do gás de síntese. Afim de atingirmos o objetivo dessa pesquisa, observamos que apenas as situações para produção de gás de síntese não necessitam de restrições para incluir a influência do catalisador. Os demais produtos derivados requerem algum tipo de restrição adicional, como evitar a formação de metano e coque. Trabalhamos com o software comercial GAMS, aplicamos o solver CONOPT 2 o qual utiliza-se da PNL (Programação Não-Linear) para a resolução, o modelo caracteriza-se como convexo. Aplicamos métodos de programação matemática diferenciados no intuito de estudarmos o desempenho de cada um / Abstract: This research consists of applying methods of global optimization for chemical equilibrium calculation and combined phases for mixtures with synthesis gas. The synthesis gas has great industrial interest, for the innumerable possibilities of various chemical composite productions. Of this form, is basic to know the thermodynamic conditions which favor the attainment of definitive product. The application of methods of global optimization has great interest for the determination of the equilibrium, a time that allows determining through in an only procedure the calculation of equilibrium and the analysis of stability of phases. As case study, the method is applied in a set of reactions that generate as product the synthesis gas. Since the reactors operate in conditions near the equilibrium, we will apply methods of similar mathematical programming differentiated to study the performance of each one / Doutorado / Desenvolvimento de Processos Químicos / Doutor em Engenharia Química

Orientador: Maria Alvina Krahenbuhl / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-04T13:24:40Z (GMT). No. of bitstreams: 1 Mafra_MarcosRogerio_D.pdf: 5218448 bytes, checksum: 82785bbe534f8328a5b2d6c5c2a8c306 (MD5) Previous issue date: 2005 / Resumo: O estudo dos fenômenos físico-químicos presentes nos processos químicos industriais é de extrema relevância, desde o projeto ata a operação das unidades que compõem a planta. Dentre as etapas do processo, a separação e purificação costumam concentrar os maiores custos do projeto. Um importante segmento da indústria petroquímica é a produção de fenol, empregando na fabricação de resinas. Nesse processo duas colunas de destilação e um decantador são responsáveis pela purificação do fenol e recuperação da matéria-prima (cumeno). O equilíbrio de fases é um dos fenômenos mais importantes dessas unidades, havendo a possibilidade de ocorrer em alguns pratos o equilíbrio trifásico (LLV). Embora termodinamicamente possível, as tentativas de descrever essa forma de equilíbrio, utilizando dados exclusivamente bifásicos (LL /ou LV), não apresentam bons resultados. Este trabalho teve como objetivo o estudo termodinâmico do equilíbrio líquido-líquido e líquido-vapor na região próxima ao equilíbrio líquido-líquido-vapor de sistemas que compõem as etapas de separação do processo de produção fenol (água, acetona, 'alfa¿-metil estireno, cumeno e fenol), de forma a contribuir com o estudo do equilíbrio trifásico, presente nesse processo. Foram obtidos dados isotérmicos de equilíbrio líquido-líquido a 50 e ¿60 GRAUS¿C e dados isobáricos de equilíbrio líquido-vapor à 760 mmHg... Observação: O resumo, na íntegra, poderá ser visualizado no texto completo da tese digital / Abstract: Studies concerning physical and chemical phenomena are very important for the chemical industry, form the early stages of design up to full plant operation. Among the many units that make up a chemical plant, the last steps of separation and purification stands as the most expensive. Phenol, used to produce resins as well as other products, is an important feedstock to petrochemical industries. Two distillations columns and one decanter are used to purify phenol and separate cumene in the phenol production process, in which phase equilibrium plays an important role. In a tray distillation tower, one may find two liquid phases and one vapor phase in equilibrium (VLLE). Although possible, attempts to describe this equilibrium condition from two phase equilibrium conditions, either liqui-liquid (LLE) or vapor-liquid (VLE), haven¿t succeed. The objective of this work was to study the LLE and VLE of systems comprising components of the phenol production process, i.e., water, acetone, cumene, phenol and 'alfa¿-methyl styrene, at conditions close to the liquid-liquid-vapor equilibrium. Equilibrium data were successfully obtained at ¿50 DEGREES¿C and ¿60 DEGREES¿C and at 760 mmHg for a variety of compositions. Unfortunately data at high acetone contents could not be obtained due to the high pressure generated in the experimental apparatus... Note: The complete abstract is available with the full electronic digital thesis or dissertations / Doutorado / Desenvolvimento de Processos Químicos / Doutor em Engenharia Química

>Magister Scientiae - MSc / HIV/AIDS is nowadays considered as the greatest public health disaster of modern time. Its progression has challenged the global population for decades. Through mathematical modelling, researchers have studied different interventions on the HIV pandemic, such as treatment, education, condom use, etc. Our research focuses on different compartmental models with emphasis on the effect of public health education. From the point of view of statistics, it is well known how the public health educational programs contribute towards the reduction of the spread of HIV/AIDS epidemic. Many models have been studied towards understanding the dynamics of the HIV/AIDS epidemic. The impact of ARV treatment have been observed and analysed by many researchers. Our research studies and investigates a compartmental model of HIV with treatment and education campaign. We study the existence of equilibrium points and their stability. Original contributions of this dissertation are the modifications on the model of Cai et al. [1], which enables us to use optimal control theory to identify optimal roll-out of strategies to control the HIV/AIDS. Furthermore, we introduce randomness into the model and we study the almost sure exponential stability of the disease free equilibrium. The randomness is regarded as environmental perturbations in the system. Another contribution is the global stability analysis on the model of Nyabadza et al. in [3]. The stability thresholds are compared for the HIV/AIDS in the absence of any intervention to assess the possible community benefit of public health educational campaigns. We illustrate the results by way simulation The following papers form the basis of much of the content of this dissertation, [1 ] L. Cai, Xuezhi Li, Mini Ghosh, Boazhu Guo. Stability analysis of an HIV/AIDS epidemic model with treatment, 229 (2009) 313-323. [2 ] C.P. Bhunu, S. Mushayabasa, H. Kojouharov, J.M. Tchuenche. Mathematical Analysis of an HIV/AIDS Model: Impact of Educational Programs and Abstinence in Sub-Saharan Africa. J Math Model Algor 10 (2011),31-55. [3 ] F. Nyabadza, C. Chiyaka, Z. Mukandavire, S.D. Hove-Musekwa. Analysis of an HIV/AIDS model with public-health information campaigns and individual with-drawal. Journal of Biological Systems, 18, 2 (2010) 357-375. Through this dissertation the author has contributed to two manuscripts [4] and [5], which are currently under review towards publication in journals, [4 ] G. Abiodun, S. Maku Vyambwera, N. Marcus, K. Okosun, P. Witbooi. Control and sensitivity of an HIV model with public health education (under submission). [5 ] P.Witbooi, M. Nsuami, S. Maku Vyambwera. Stability of a stochastic model of HIV population dynamics (under submission).

The main ambition of this doctoral thesis is to contribute to the development of interdisciplinary application of the concept of moral hazard developedin economic and insurance theory to the context of the inter-state conflicts with potential international intervention. The basic theoretical framework used in the thesis is derived from the concept of moral hazard of humanitarian intervention by Alan Kuperman who claims that the newly established norm of humanitarian intervention may well have unintended negative consequences. Kuperman argues that if the mere existence of insurance creates sufficient incentive for the insured to modify their behavior to the extent that they engage in the riskier behavior due to the fact that they are insured against the consequences of their actions, the rebels may well optimize their behavior in the same way. Currently, the transfer of the moral hazard theory to the context of interventions is hindered by a number of existing obstacles stemming from the differences in these areas. This thesis concentrates on reduction of three main identified drawbacks and addresses them by formulating three main research questions and derived hypothesis. The aim of this approach is to examine the limits of application and create the space for development of the concept of moral hazard of humanitarian intervention in the future research. (1) What is the interpretation potential, value added and limits of application of economic theory of moral hazard to the context of humanitarian intervention from the theoretical perspective? Hypothesis 1:The concept of moral hazard represents an efficienttool for evaluation of humanitarian intervention. (2) What is the potential of causal mechanism established by the Kuperman´s hypothesis to explain the reasons why in certain cases the state decides to escalate the inter-state conflict despite the public threats of intervention at a general level of research? Hypothesis 2: The threat of intervention causes the escalation of the inter-state conflict. (3) To what extent does Kuperman´s hypothesis modified to the conflict in Kosovo correspond with the actual state of affairs and their development? Hypothesis 3: The threat of intervention NATO/USA caused the escalation of conflict in Kosovo.