Modeling and forecasting long-term natural gas (NG) consumption in Iran, using particle swarm optimization (PSO)

The gradual changes in the world development have brought energy issues back into high profile. An ongoing challenge for countries around the world is to balance the development gains against its effects on the environment. The energy management is the key factor of any sustainable development program. All the aspects of development in agriculture, power generation, social welfare and industry in Iran are crucially related to the energy and its revenue. Forecasting end-use natural gas consumption is an important Factor for efficient system operation and a basis for planning decisions. In this thesis, particle swarm optimization (PSO) used to forecast long run natural gas consumption in Iran. Gas consumption data in Iran for the previous 34 years is used to predict the consumption for the coming years. Four linear and nonlinear models proposed and six factors such as Gross Domestic Product (GDP), Population, National Income (NI), Temperature, Consumer Price Index (CPI) and yearly Natural Gas (NG) demand investigated.

On choice of technique in the Robinson-Solow-Srinivasan model

We report results on the optimal \choice of technique" in a model originally formulated by Robinson, Solow and Srinivasan (henceforth, the RSS model) and further discussed by Okishio and Stiglitz. By viewing this vintage-capital model without discounting as a speci c instance of the general theory of intertemporal resource allocation associated with Brock, Gale and McKenzie, we resolve longstanding conjectures in the form of theorems on the existence and price support of optimal paths, and of conditions suÆcient for the optimality of a policy rst identi ed by Stiglitz. We dispose of the necessity of these conditions in surprisingly simple examples of economies in which (i) an optimal path is periodic, (ii) a path following Stiglitz' policy is bad, and (iii) there is optimal investment in di erent vintages at di erent times. (129 words)

Desalinhamento cambial no Brasil após o plano real: uma análise empírica

Filiando-se a discussão sobre os efeitos da apreciação cambial no país, o trabalho procura contribuir para o debate acerca da posição correta da taxa de câmbio e suas possíveis dinâmicas de ajustamento no curto e longo prazo. Neste sentido, apresenta evidências econométricas para possíveis desalinhamentos do câmbio real no Brasil desde 1994. A partir de uma base de dados mensais que abarca o período de janeiro de 1995 até setembro de 2006, realiza-se uma análise econométrica para estudar o comportamento do câmbio real e de equilíbrio no Brasil no período recente

Assets, markets and poverty in Brazil

Esse artigo estabelece uma base para pesquisas que tratam da relação entre pobreza, distribuição de recursos e operação do mercado de capitais no Brasil. O principal objetivo é auxiliar a implementação de políticas de reforço de capital dos pobres. A disponibilidade de novas fontes de dados abriu condições inéditas para implementar uma análise de posse de ativos e pobreza nas áreas metropolitanas brasileiras. A avaliação de distribuição de recursos foi estruturada sobre três itens: Capital físico, capital humano e capital social. A estratégia empírica seguida é de analisar três diferentes tipos de impactos que o aumento dos ativos dos pobres podem exercer no nível de bem estar social. A primeira parte do artigo avalia a posse de diferentes tipos de capitais através da distribuição de renda. Esse exercício pode ser encarado como uma ampliação de medidas de pobreza baseadas em renda pela incorporação de efeitos diretos exercidos pela posse de ativos no bem estar social. A segunda parte do artigo descreve o impacto de geração de renda que a posse de ativos pode ter sobre os pobres. Estudamos como a acumulação de diferentes tipos de capital impactam os índices de pobreza baseados na renda usando regressões logísticas. A terceira parte estuda o efeito que o aumento da posse de ativos dos pobres tem no melhoramento da habilidade dos indivíduos pobres em lidar com choques adversos da renda. Estudamos a interação entre a dinâmica da renda, imperfeições do mercado de capitais e comportamentos financeiros levando em consideração diferentes horizontes de tempo. As questões de longo prazo estão relacionadas com o estudo das flutuações de renda de baixa freqüência e ciclo da vida da posse de ativos usando análise de coorte. As questões de curto prazo estão relacionadas com o comportamento do pobre e as perdas de bem estar ao lidar com hiatos de alta freqüência entre renda e consumo desejado. A análise da dinâmica de renda e pobreza é conduzida a partir da combinação de dados de painel de renda com dados qualitativos sobre comportamento financeiro de curto prazo das famílias.

Using common features to understand the behavior of metal-commodity prices and forecast them at different horizons

The objective of this article is to study (understand and forecast) spot metal price levels and changes at monthly, quarterly, and annual horizons. The data to be used consists of metal-commodity prices in a monthly frequency from 1957 to 2012 from the International Financial Statistics of the IMF on individual metal series. We will also employ the (relatively large) list of co-variates used in Welch and Goyal (2008) and in Hong and Yogo (2009) , which are available for download. Regarding short- and long-run comovement, we will apply the techniques and the tests proposed in the common-feature literature to build parsimonious VARs, which possibly entail quasi-structural relationships between different commodity prices and/or between a given commodity price and its potential demand determinants. These parsimonious VARs will be later used as forecasting models to be combined to yield metal-commodity prices optimal forecasts. Regarding out-of-sample forecasts, we will use a variety of models (linear and non-linear, single equation and multivariate) and a variety of co-variates to forecast the returns and prices of metal commodities. With the forecasts of a large number of models (N large) and a large number of time periods (T large), we will apply the techniques put forth by the common-feature literature on forecast combinations. The main contribution of this paper is to understand the short-run dynamics of metal prices. We show theoretically that there must be a positive correlation between metal-price variation and industrial-production variation if metal supply is held fixed in the short run when demand is optimally chosen taking into account optimal production for the industrial sector. This is simply a consequence of the derived-demand model for cost-minimizing firms. Our empirical evidence fully supports this theoretical result, with overwhelming evidence that cycles in metal prices are synchronized with those in industrial production. This evidence is stronger regarding the global economy but holds as well for the U.S. economy to a lesser degree. Regarding forecasting, we show that models incorporating (short-run) commoncycle restrictions perform better than unrestricted models, with an important role for industrial production as a predictor for metal-price variation. Still, in most cases, forecast combination techniques outperform individual models.

Using common features to understand the behavior of metal-commodity prices and forecast them at different horizons

The objective of this article is to study (understand and forecast) spot metal price levels and changes at monthly, quarterly, and annual frequencies. Data consists of metal-commodity prices at a monthly and quarterly frequencies from 1957 to 2012, extracted from the IFS, and annual data, provided from 1900-2010 by the U.S. Geological Survey (USGS). We also employ the (relatively large) list of co-variates used in Welch and Goyal (2008) and in Hong and Yogo (2009). We investigate short- and long-run comovement by applying the techniques and the tests proposed in the common-feature literature. One of the main contributions of this paper is to understand the short-run dynamics of metal prices. We show theoretically that there must be a positive correlation between metal-price variation and industrial-production variation if metal supply is held fixed in the short run when demand is optimally chosen taking into account optimal production for the industrial sector. This is simply a consequence of the derived-demand model for cost-minimizing firms. Our empirical evidence fully supports this theoretical result, with overwhelming evidence that cycles in metal prices are synchronized with those in industrial production. This evidence is stronger regarding the global economy but holds as well for the U.S. economy to a lesser degree. Regarding out-of-sample forecasts, our main contribution is to show the benefits of forecast-combination techniques, which outperform individual-model forecasts - including the random-walk model. We use a variety of models (linear and non-linear, single equation and multivariate) and a variety of co-variates and functional forms to forecast the returns and prices of metal commodities. Using a large number of models (N large) and a large number of time periods (T large), we apply the techniques put forth by the common-feature literature on forecast combinations. Empirically, we show that models incorporating (short-run) common-cycle restrictions perform better than unrestricted models, with an important role for industrial production as a predictor for metal-price variation.

Information learning and the stability of fiat money

We analyze the stability of monetary regimes in a decentralized economy where fiat money is endogenously created, information about its value is imperfect, and agents only learn from their personal trading experiences. We show that in poorly informed economies, monetary stability depends heavily on the government's commitment to the long run value of money, whereas in economies where agents gather information more easily, monetary stability can be an endogenous outcome. We generate a dynamics on the acceptability of fiat money that resembles historical accounts of the rise and eventual colIapse of overissued paper money. Moreover, our results provide an explanation of the fact that, despite its obvious advantages, the widespread use of fiat money is a very recent development.

Fazer a ponte para a escola de todos(as)

The purpose of this study is to understand what are the matrix elements in which everyday activities of social author/authors, actor/actors and actress/actresses are embedded, in order to carry out the Escola da Ponte s political and pedagogic process (PPP). Thus, the object of this study is to reflect on an experience developed in a public school supported by the Portuguese State within the scenario of institutions that are committed to building up a school of the people by investing in democratization and community participation in their management process. The methodological course of action was targeted at the presuppositions of qualitative research (WOODS, 1999; BURGESS, 1997; MILLS, 1982; OLIVEIRA, 1998; BOGDAN and BIKLEN, 1994; MACEDO, 2000; CASAL, 1996; GEERTZ, 2000), with data collected from random word association (MACHADO and CARVALHO, 2003), the discourse of the interviewed (KAUFMANN, 1996; SILVA, 2006; 2002), observation notes and documents (ELIAS, 1997). Based on a multiple reference and theoretical framework, the investigation revealed elements that are construed as the raw material and pillars supporting the bridge of a school of the people, as well as the self-organization of the school community which emerges as a dimension that binds together all the elements and brings new arrangements into the school dynamics by moving from the individual to the society (DUPUY, 1990). Along this line, the central argument is that in the short and long run the public school quality does not spring from macro educational policies, nor from ephemeral mass-production programs, projects or governmental policies, but from the intent of the professionals working there in becoming authors and characters in the process of building up and carrying out the PPP. The Project has been conceived in the light of the needs and intentionality of the community whose support comes from the participation and social control held by the students families and the community s power to force to action public administration central agencies aiming at having the State fulfill its responsibilities

Numerical exploration of resonant dynamics in the system of Saturnian major satellites

We numerically investigate the long-term dynamics of the Saturnian system by analyzing the Fourier spectra of ensembles of orbits taken around the current orbits of Mimas, Enceladus, Tethys, Rhea and Hyperion. We construct dynamical maps around the current position of these satellites in their respective phase spaces. The maps are the result of a great deal of numerical simulations where we adopt dense sets of initial conditions and different satellite configurations. Several structures associated to the current two-body mean-motion resonances, unstable regions associated to close approaches between the satellites, and three-body mean-motion resonances in the system, are identified in the map. (C) 2010 Elsevier Ltd. All rights reserved.

Ciclos clássicos num ambiente de racionalidade limitada

O presente trabalho toma como ponto de partida o modelo macrodinâmico de Richard M. Goodwin, apresentado no clássico artigo A Growth Cycle (1967). Neste modelo a interação entre distribuição de renda e acumulação de capital gera um ciclo de crescimento que oscila em torno de uma trajetória de crescimento equilibrado. O objetivo do presente trabalho é investigar a possibilidade de existência de ciclos goodwinianos com heterogeneidade de salários e de taxas de lucro. Essa análise é realizada considerando o processo de concorrência entre trabalhadores num ambiente de racionalidade limitada. Para formalizar o processo de concorrência entre trabalhadores foram utilizados dois recursos: (i) a alegoria das ilhas , que tem sido amplamente adotada na macroeconomia moderna, a fim de apreender situações de informação imperfeita; e (ii) os instrumentos analíticos desenvolvidos pela teoria dos jogos evolucionários aplicada a ambientes sociais. O modelo construído combina o modelo de Goodwin com uma formalização estilizada do fluxo de trabalho como um processo de imitação num ambiente de racionalidade limitada (dinâmica de replicação num contexto social). Neste modelo demonstra-se a possibilidade de o sistema econômico não convergir para um estado de equilíbrio de longo prazo e a possibilidade do sistema econômico convergir para um ciclo goodwiniano caracterizado por heterogeneidade de salários e de taxas de lucro.

From hard-peg to hard landing?: recent experiences of Argentina and Ecuador

Includes bibliography

Weak expansions: a distinctive feature of the business cycle in Latin America and the Caribbean

Using two standard cycle methodologies (Classical and Deviation Cycle) and a comprehensive sample of 83 countries worldwide, including all developing regions, we show that the Latin American and Caribbean cycle exhibits two distinctive features. First, and most importantly, its expansion performance is shorter and for the most par less imtense than that of the rest of the regions considered, and in particular than that of East Asia and the Pacific, East Asia and the Pacific's expansions last five years longer than those of LAC, and its output gain is 50% greater than that of LAC. Second, LAC tends to exhibit contractions that are not significantly different in terms of duration and amplitude than t those of other regions. Both these features imply that the complete Latin American and Caribbean cycle has, overall, the shortest duration and smallest amplitude in relation to other regions. The specificities of the Latin American and Caribbean cycle are not confined to the short run. These are also reflected in variables such as productivity and investment, which are linked to long-run growth. East Asia and the Pacific's cumulative gain in labor productivity during the expansionary phase is twice that of LAC. Moreover, the evidence also shows that the effects of the contraction in public investment surpass those of the expansion leading to a declining trend over the entire cycle. In this sense we suggest that policy analysis needs to increase its focus on the expansionary phase of the cycle. Improving our knowledge of the differences in the expansionary dynamics of countries and regions, can further our understanding of the differences in their rates of growth and levels of development. We also suggest that while, the management of the cycle affects the short-run fluctuations of economic activity and hence volatility, it is not trend neutral. Hence, the effects of aggregate demand management policies may be more persistent over time and less transitory than currently thought.

Savings, investment and growth in the global age: analytical and policy issues

Includes bibliography

The employment situation in Latin America and the Caribbean: Labour productivity and distribution issues

Although the economies of Latin America and the Caribbean grew more slowly in 2011 than in 2010, there were some improvements on the employment front. Workers benefited from the region’s satisfactory economic performance in an increasingly complex international setting. The unemployment rate fell from 7.3% in 2010 to 6.7% in 2011 thanks to a halfpercentage- point gain in the urban employment rate. Both rates are at levels that have not been seen for a long time. The proportion of formal jobs with social benefits rose as well, and underemployment declined. The average wage and the minimum wage both increased in real terms, albeit only moderately. Economic performance and the employment situation varied widely among the subregions. The unemployment rate dropped by 0.6 percentage points in South America but 0.4 percentage points in the countries of the northern part of Latin America. In the countries of the Caribbean, the employment rate was up by 0.2 percentage points. The data show that substantial labour market gaps and serious labour-market insertion issues remain. This is especially the case for women and young people, for whom unemployment rates and other labour indicators are still unfavourable. The second part of this report looks at whether the fruits of economic growth and rising productivity have been distributed equitably between workers and companies. Between 2002 and 2008 (the most recent expansionary economic cycle), wages as a percentage of GDP fell in 13 of the 21 countries of the region for which data are available and rose in just 8. This points to redistribution that is unfavourable to workers, which is worrying in a region which already has the most unequal distribution of income in the world. Underlying this trend is the fact that, worldwide, wages have grown less than productivity. Beyond the ethical dimension of this issue, it jeopardizes the social and economic sustainability of growth. For example, one of the root causes of the recent financial crisis was that households in the United States responded to declining wage income by borrowing more to pay for consumption and housing. This turned out to be unsustainable in the long run. Over time, it undermines the labour market’s contribution to the efficient allocation of resources and its distributive function, too, with negative consequences for democratic governance. Among the triggers of this distributive worsening most often cited in the global debate are market deregulation and its impact on financial globalization, technological change that favours capital over labour, and the weakening of labour institutions. What is needed here is a public policy effort to help keep wage increases from lagging behind increases in productivity. Some countries of the region, especially in South America, saw promising developments during the second half of the 2000s in the form of a positive trend reversal in wages as a percentage of GDP. One example is Brazil, where a minimum wage policy tailored to the dynamics of the domestic market is considered to be one of the factors behind an upturn in the wage share of GDP. The region needs to grow more and better. Productivity must grow at a steady pace, to serve as the basis for sustained improvements in the well-being of the populace and to narrow the gap between the economies of Latin America and the Caribbean and the more advanced economies. And inequality must be decreased; this could be achieved by closing the productivity gap between upgraded companies and the many firms whose productivity is low. As set out in this report, the region made some progress between 2002 and 2010, with labour productivity rising at the rate of 1.5% a year. But this progress falls short of that seen in other regions such as Sub-Saharan Africa (2.1%) and, above all, East Asia (8.3%, not counting Japan and the Republic of Korea). Moreover, in many of the countries of the region these gains have not been distributed equitably. Therein lies a dual challenge that must be addressed: continue to increase productivity while enhancing the mechanisms for distributing gains in a way that will encourage investment and boost worker and household income. The Economic Commission for Latin America and the Caribbean (ECLAC) and the International Labour Organization (ILO) estimate that the pace of economic growth in the region will be slightly slower in 2012 than in 2011, in a global economic scenario marked by the cooling of several of the main economic engines and a high degree of uncertainty concerning, above all, prospects for the euro zone. The region is expected to continue to hold up well to this worsening scenario, thanks to policies that leveraged more favourable conditions in the past. This will be felt in the labour markets, as well, so expectations are that unemployment will edge down by as much as two tenths of a decimal point.

Stability and dynamics of terrestrial planets in binary star systems: application on Alpha Centauri

Binary stars are frequent in the universe, with about 50% of the known main sequence stars being located at a multiple star system (Abt, 1979). Even though, they are universally thought as second rate sites for the location of exo-planets and the habitable zone, due to the difficulties of detection and high perturbation that could prevent planet formation and long term stability. In this work we show that planets in binary star systems can have regular orbits and remain on the habitable zone. We introduce a stability criterium based on the solution of the restricted three body problem and apply it to describe the short period planar and three-dimentional stability zones of S-type orbits around each star of the Alpha Centauri system. We develop as well a semi-analytical secular model to study the long term dynamics of fictional planets in the habitable zone of those stars and we verify that planets on the habitable zone would be in regular orbits with any eccentricity and with inclination to the binary orbital plane up until 35 degrees. We show as well that the short period oscillations on the semi-major axis is 100 times greater than the Earth's, but at all the time the planet would still be found inside the Habitable zone.