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Search Results: 1 - 10 of 20567 matches for " Joao Pereira "
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A Practical and Automated Hall Magnetometer for Characterization of Magnetic Materials  [PDF]
Jefferson F. D. F. Araujo, Joao M. B. Pereira
Modern Instrumentation (MI) , 2015, DOI: 10.4236/mi.2015.44005
Abstract: A versatile Hall magnetometer has been developed, manufactured, calibrated, and turned operational for measurements of the magnetic properties of bulk materials and magnetic micro- and nanoparticles. The magnetometer was constructed from the combination of various equipments, which was usually available in most laboratories, such as a Hall effect sensor, an electromagnet, a current source, and a linear actuator. The achieved sensitivity to the magnetic moment was approximately 10-8 Am2. The results were compared to measurements performed with commercial vibrating-sample magnetometers and superconductor quantum interference devices (SQUID) and showed errors of around 1.7% and a standard deviation of 1.2% in relation to measures themselves. The constructed Hall magnetometer records a magnetic hysteresis loop of up to 1.2 T at room temperature. This magnetometer is cost-effective, versatile, and suitable for research.
Geographic Concentration in Portugal and Regional Specific Factors
Vitor Joao Pereira Domingues Martinho
Quantitative Finance , 2011,
Abstract: This paper pretends to analyze the importance which the natural advantages and local resources are in the manufacturing industry location, in relation with the "spillovers" effects and industrial policies. To this, we estimate the Rybczynski equation matrix for the various manufacturing industries in Portugal, at regional level (NUTS II) and for the period 1980 to 1999. Estimations are displayed with the model mentioned and for four different periods, namely 1980 to 1985, from 1986 to 1994, from 1980 to 1994 and from 1995 to 1999. The consideration of the various periods until 1994, aims to capture the effects of our entrance at the, in that time, EEC (European Economic Community) and the consideration of a period from 1995 is because the change in methodology for compiling statistical data taken from this time in Portugal. As a summary conclusion, noted that the location of manufacturing in Portugal is still mostly explained by specific factors, with a tendency to increase in some cases the explanation by these factors, having the effect "spillovers" and industrial policies little importance in this context.
Spatial Effects and Convergence Theory in the Portuguese Situation
Vitor Joao Pereira Domingues Martinho
Quantitative Finance , 2011,
Abstract: This study analyses, through cross-section estimation methods, the influence of spatial effects and human capital in the conditional productivity convergence (product per worker) in the economic sectors of NUTs III of mainland Portugal between 1995 and 2002. To analyse the data, Moran's I statistics is considered, and it is stated that productivity is subject to positive spatial autocorrelation (productivity develops in a similar manner to productivity in neighbouring regions), above all, in agriculture and services. Industry and the total of all sectors present indications that they are subject to positive spatial autocorrelation in productivity. On the other hand, it is stated that the indications of convergence, specifically bearing in mind the concept of absolute convergence, are greater in industry. Taking into account the estimation results, it is stated once again that the indications of convergence are greater in industry, and it can be seen that spatial spillover effects, spatial lag (capturing spatial autocorrelation through a spatially redundant dependent variable) and spatial error (capturing spatial autocorrelation through a spatially redundant error term), as well as human capital, condition the convergence of productivity in the various economic sectors of Portuguese region in the period under consideration (Martinho, 2011).
Spatial Autocorrelation and Verdoorn Law in the Portuguese NUTs III
Vitor Joao Pereira Domingues Martinho
Quantitative Finance , 2011,
Abstract: This study analyses, through cross-section estimation methods, the influence of spatial effects in productivity (product per worker), at economic sectors level of the NUTs III of mainland Portugal, from 1995 to 1999 and from 2000 to 2005 (taking in count the data availability and the Portuguese and European context), considering the Verdoorn relationship. From the analyses of the data, by using Moran I statistics, it is stated that productivity is subject to a positive spatial autocorrelation (productivity of each of the regions develops in a similar manner to each of the neighbouring regions), above all in services. The total sectors of all regional economy present, also, indicators of being subject to positive autocorrelation in productivity. Bearing in mind the results of estimations, it can been that the effects of spatial spillovers, spatial lags (measuring spatial autocorrelation through the spatially lagged dependent variable) and spatial error (measuring spatial autocorrelation through the spatially lagged error terms), influence the Verdoorn relationship when it is applied to the economic sectors of Portuguese regions. The results obtained for the two periods are different, as expected, and are better in second period, because, essentially, the European and national public supports (Martinho, 2011).
The Keynesian theory and the manufactured industry in Portugal
Vitor Joao Pereira Domingues Martinho
Quantitative Finance , 2012,
Abstract: About the economic growth the Keynesian theorists defend circular and cumulative processes, benefiting the rich localities and harming the poorest, without external interventions. In these processes the Verdoorn law has an important role. For Verdoorn (1949) the productivity growth rate is endogenous and depends of the output growth rate, capturing dynamic contexts, endogeneity of the factors and increasing economies of scale, namely in the industry. This relationship later becomes the second law of Kaldor (1966 and 1967). For Portugal there are few works or none, than those of the author, with the Verdoorn law. In this way, seem important analyze this relationship for the manufactured industry of the Portuguese regions and conclude about these contexts in Portugal. It was used data from two periods, 1986-1994 and 1995-1999, and panel data econometric methods. The two periods is to capture the effect of the Portuguese entrance in the European Economic Community and of the first Community Support Framework (1989-1993) for Portugal. As main conclusion, for the two periods, it is verified strong increasing returns in the manufactured industry and as consequence regional divergence of this sector.
International trade of fruits between Portugal and the world
Vitor Joao Pereira Domingues Martinho
Quantitative Finance , 2012,
Abstract: For Portugal there are few or none works about the international trade of fruits between Portugal and the other countries. In this work it aims to analyze the more recent data for the Portuguese international trade of fruits. They were used data for the years from 2006 to 2010, available by the INE (Statistics Portugal), gently given by the AICEP (Trade & Investment Agency). To complement this data analysis they were made some estimations with several econometrics method and based in the neoclassical theory, with the absolute convergence model. It was concluded that the biggest relationship, in the international trade of fruits, is with the European countries and there are not statistical regularity in the estimations and the data are not stationary.
International trade of flowers. Tendencies and policies
Vitor Joao Pereira Domingues Martinho
Quantitative Finance , 2012,
Abstract: There are few papers about the international trade of flowers, so it is believed that this paper, with this topic, could be an important contribution to the international scientific community. It is intended to analyze if the international trade flowers tendencies and policies are adapted to the actual world global context. For that it was used data about the import and export of flowers, in different forms, between Portugal and the world. This is an approach to understand the international trade flowers tendencies and policies. To better understand the data analyzed it is made several estimations based in the absolute convergence theory and an analyze of the data volatility. As main conclusions, there is a tendency to the countries trade the flowers between the neighbors and is needed a more coherent policy for the international trade of flowers.
Import and export of horticultural products in Portugal
Vitor Joao Pereira Domingues Martinho
Quantitative Finance , 2012,
Abstract: With this work it is analyzed the import and export of horticultural products between Portugal and the other world countries. It is used data about Portuguese international trade of vegetables from 2006 to 2010. The data were obtained from the INE (Statistics Portugal), gently given by the AICEP (Trade & Investment Agency). It is did some estimations taking into account the models from the convergence theory, with panel data and using methods by fixed effects, random effects and dynamic effects, for the Portuguese import and export of vegetables, separately. It is found convergence in all estimations. The volatility was also tested. All the tests show no stationary of the data. So, in statically means the data show weak regularity. In this way all the conclusion, must be did very carefully. This lack of regularity is a result of lack of a national coherent policy for the sector.
Sectoral Convergence in Output Per Worker Between Portuguese Regions
Vitor Joao Pereira Domingues Martinho
Quantitative Finance , 2011,
Abstract: The aim of this paper is to present a further contribution to the analysis of absolute convergence (and), associated with the neoclassical theory, and conditional, associated with endogenous growth theory, of the sectoral productivity at regional level. Presenting some empirical evidence of absolute convergence of productivity for each of the economic sectors and industries in each of the regions of mainland Portugal (NUTS II and NUTS III) in the period 1986 to 1994 and from 1995 to 1999. The finest spatial unit NUTS III is only considered for each of the economic sectors in the period 1995 to 1999. They are also presented empirical evidence of conditional convergence of productivity, but only for each of the economic sectors of the NUTS II of Portugal, from 1995 to 1999. The structural variables used in the analysis of conditional convergence is the ratio of capital/output, the flow of goods/output and location ratio. The main conclusions should be noted that the signs of convergence are stronger in the first period than in the second and that convergence is conditional, especially in industry and in all sectors (1)(Martinho, 2011).
Entrepreneurship: what's happening?
Vitor Joao Pereira Domingues Martinho
Quantitative Finance , 2011,
Abstract: Much has been said lately about entrepreneurship, so it seems important to leave here some personal analysis on this topic. The issues outlined here result from a work in about a year in which because a personal and professional obligations it was doing some research on these issues. This is an interesting topic that has not yet expired and on which there is much to research, do it is an area where there are many challenges.
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