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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

[en] DETERMINATION OF AS AND MN IN DIESEL, GASOLINE E NAPHTHA BY GF AAS AND OF CU, FE, NI AND V IN PETROLEUM USING SS-GF AAS / [pt] DETERMINAÇÃO DE AS E MN EM DIESEL, GASOLINA E NAFTA POR GF AAS E DE CU, FE, NI E V EM PETRÓLEO UTILIZANDO SS-GF AAS

GEISAMANDA PEDRINI BRANDAO 01 April 2008 (has links)
[pt] O petróleo é uma mistura complexa de hidrocarbonetos (50 a 95 por cento) contendo traços de compostos inorgânicos (principalmente de S, N, O e metais pesados). Elementos traço são normalmente encontrados no petróleo como ocorrência natural, associados ao processo de formação. Embora presentes apenas em quantidades pequenas (níveis de microgramag−1 ou ng g−1), sua determinação é de grande importância, devido seu alto potencial de contaminação do meio ambiente e de interferência durante o processo de refino. Estes elementos podem causar corrosão nas torres de refino, envenenar catalisadores e/ou causar reações secundárias indesejáveis nas operações de refino. Além disso, os metais pesados, quando presentes nos derivados de petróleo, são relacionados ao seu mau desempenho, redução da sua estabilidade térmica por catalisar reações oxidativas e, no caso da nafta, interferência nos processos petroquímicos. Os riscos ambientais dependem da toxidade e da concentração de cada elemento, bem como a interferência no refino depende do metal e de sua concentração. Assim, foram estudados procedimentos rápidos, simples, exatos e precisos para a determinação de elementos traço em petróleo e alguns derivados pela espectrometria de absorção atômica com forno de grafite. Para amostras de diesel, gasolina e nafta, são propostos procedimentos para a determinação de As e Mn em nível de ng mL−1. A estabilização das amostras foi necessária e obtida pela formação de sistemas de três componentes, preparadas pela mistura de volumes adequados da amostra, do propan-1-ol e da solução aquosa de HNO3, resultando em um meio unifásico, indefinidamente estável. A utilização de modificação de matriz foi investigada. A otimização multivariada definiu a composição ótima da microemulsão, bem como o programa de temperatura. Os limites de detecção nas amostras originais para As foram 1,8, 1,2 e 1,5 ng mL−1 e para Mn foram 0,6, 0,5 e 0,3 ng mL−1 para diesel, gasolina e nafta, respectivamente. A exatidão dos métodos foi confirmada por testes de recuperação e por análise de um conjunto de amostras comerciais por procedimentos comparativos independentes. Para amostras de petróleo, são propostos procedimentos para a determinação direta de Ni, Cu, Fe e V, usando um acessório de amostragem de sólidos, sem qualquer prétratamento da amostra. Uma solução de Pd + Triton X-100 foi utilizada como modificador químico. As temperaturas de pirólise e atomização, bem como a massa do Pd foram definidas por otimização multivariada. Os limites de detecção nas condições otimizadas foram 230, 10, 200 e 800 pg de Ni, Cu, Fe e V, respectivamente. A exatidão dos métodos foi confirmada pela análise de materiais de referência certificados de petróleo, bem como por comparação com métodos independentes. Para todos os procedimentos propostos, a calibração com solução analítica aquosa foi possível. / [en] Petroleum is a complex mixture of hydrocarbons (50 to 95 percent) and nonhydrocarbons (mainly S, N, O and heavy metal compounds). Metallic traces are normally found in petroleum as naturally occurring elements associated to the formation process. Although present only in small amounts (Microgram −1 or ng g−1 levels), their determination is of great interest because of their high potential of environmental contamination and interference in the refining process. They may corrode refinery equipment, poison and foul catalysts and/or cause undesirable side reactions in refinery operations. Moreover, heavy metals present in petroleum derivates such as diesel, gasoline and naphtha are related to poor performance and reduction of their thermal stability. Thus, fast, simple and reliable procedures for the determination of trace metals in petroleum and its derivates by graphite furnace atomic absorption spectrometry were studied. For diesel, gasoline and naphtha samples, procedures for the determination of As and Mn (ng mL−1 levels) are proposed. Sample stabilization was necessary and achieved by the formation of three component system prepared by mixing appropriate volumes of the samples, propan-1-ol and nitric acid aqueous solution, resulting in a one-phase medium indefinitely stable (microemulsion). The use of matrix modification was also investigated. Multivariate optimization defined the optimum microemulsion composition as well as the temperature program. The limits of detection in the original samples for As were 1.8, 1.2 and 1.5 ng ml−1 while for Mn they were 0.6, 0.5 and 0.3 ng mL-1 for diesel, gasoline and naphtha, respectively. Methods accuracies were confirmed by recoveries tests and the analysis of a set of commercial samples by the proposed and independent comparative procedures. For petroleum samples, procedures for the direct determination of Ni, Cu, Fe and V using a solid sampling accessory, without any sample pre- treatment, are proposed. A Pd+Triton X-100 solution was used as chemical modifier. The pyrolysis and atomization temperatures, as well as the Pd mass were defined by multivariate optimization. The limits of detection at the optimized conditions were 230, 10, 200 and 800 pg for Ni, Cu, Fe and V, respectively. Methods` accuracies were confirmed by the analysis of oil certified reference materials as well as by comparison with independent methods. For all proposed procedures, calibration using aqueous analytical solutions was possible.
12

Criação e desvio de comércio no Mercosul e no Nafta / Trade creation and trade diversion in Mercosur and Nafta

Morais, Adriano Giacomini 01 November 2005 (has links)
A integração comercial entre países vem ocorrendo através de negociações multilaterais e acordos regionais. As teorias de comércio internacional dizem que as primeiras provocam aumento de bem-estar. Entretanto, não há consenso sobre os efeitos dos segundos. O papel deste trabalho é justamente avaliar os impactos de dois acordos comerciais, o Mercosul e o Nafta, sobre dois critérios de bem-estar, a criação e o desvio de comércio. Isso é feito através da estimação de equações gravitacionais para dados em painel, com a inclusão de variáveis dummy para captar a relação intra e extra-bloco, conforme metodologia apresentada por Endoh (1999). Os resultados apontaram que não ocorreu criação de comércio em ambos os acordos. O Nafta foi seguido por desvio de comércio e o Mercosul apresentou dificuldades na mensuração do mesmo. / The commercial integration between countries has been taking place through multilateral negotiations and regional agreements. Economic theories of international trade say that the first one improves welfare. However, there is no consensus about the second one. The aim of this dissertation is just to evaluate the effects of two agreements, Mercosur and Nafta, on two concepts of welfare, trade creation and trade diversion. This is done through the estimation of gravity equations by panel data methods, with dummy variables to detect intra-bloc and extra-bloc relations, according to the methodology of Endoh (1999). The results suggested that trade creation has not occurred in both agreements. Nafta was followed by trade diversion and Mercosur presented difficulties in measuring this component.
13

Criação e desvio de comércio no Mercosul e no Nafta / Trade creation and trade diversion in Mercosur and Nafta

Adriano Giacomini Morais 01 November 2005 (has links)
A integração comercial entre países vem ocorrendo através de negociações multilaterais e acordos regionais. As teorias de comércio internacional dizem que as primeiras provocam aumento de bem-estar. Entretanto, não há consenso sobre os efeitos dos segundos. O papel deste trabalho é justamente avaliar os impactos de dois acordos comerciais, o Mercosul e o Nafta, sobre dois critérios de bem-estar, a criação e o desvio de comércio. Isso é feito através da estimação de equações gravitacionais para dados em painel, com a inclusão de variáveis dummy para captar a relação intra e extra-bloco, conforme metodologia apresentada por Endoh (1999). Os resultados apontaram que não ocorreu criação de comércio em ambos os acordos. O Nafta foi seguido por desvio de comércio e o Mercosul apresentou dificuldades na mensuração do mesmo. / The commercial integration between countries has been taking place through multilateral negotiations and regional agreements. Economic theories of international trade say that the first one improves welfare. However, there is no consensus about the second one. The aim of this dissertation is just to evaluate the effects of two agreements, Mercosur and Nafta, on two concepts of welfare, trade creation and trade diversion. This is done through the estimation of gravity equations by panel data methods, with dummy variables to detect intra-bloc and extra-bloc relations, according to the methodology of Endoh (1999). The results suggested that trade creation has not occurred in both agreements. Nafta was followed by trade diversion and Mercosur presented difficulties in measuring this component.
14

Naftos kainų pokyčiai ir jų įtaka ekonomikai / Oil price developments and their influence to economy

Pranskūnas, Vaidotas 21 June 2010 (has links)
Šio magistro baigiamojo darbo tikslas – išanalizuoti naftos kainų kitimą ir kitimo įtaką ekonomikai. Pirmojoje darbo dalyje aptariama naftos kainų kaitos istoriniai kitimo aspektai, pateikiami autorių naftos kainų kitimo traktavimo ypatumai, apžvelgiami svarbiausi naftos paklausos ir pasiūlos veiksniai, įrodoma naftos kainų kitimo svarba bei išsamiai išanalizuojami prognozavimo modeliai. Antrojoje dalyje atliekama išsami naftos kainos kitimo poveikio globaliai rinkai analizė, naftos kainų kitimo įtakai ekonominiam augimui apskaičiuoti naudojama regresinė analizė. Trečiojoje dalyje pateikiamos naftos kainų kitimo ateityje perspektyvos, naudojantis prognozavimo agentūrų ateities tendencijomis, sukuriamas trijų scenarijų naftos kainos kitimo modelis. Atliktas tyrimas parodė, kad naftos kainos kitimas priklauso nuo labai daug skirtingų kintamųjų, kitimas turi didelę reikšmę makroekonominiams procesams, tarp jų ir ekonominiam augimui. Tad labai svarbu ištirti naftos kainų kitimo priežastis. Buvo apžvelgta ir įvertinta plati naftos kainų kitimo ir numatymo bei jų poveikio literatūros analizė. Regresine analize buvo nustatyta naftos kainų kitimo ir ekonominio augimo sąveika. Buvo pateikti ateities naftos kainos kititmo ypatumai, sukurti trys ateities naftos kainos kitimo scenarijai. / This master thesis aim – to analyze the dynamics of oil prices and oil price changes effects on the economy. The first part deals with oil price changes in the historical aspects of the change, the authors’ opininion on oil price changes are revealed, most important oil supply and demand factors are revealed, as evidenced by oil price developments and the importance of forecasting models are analyzed in detail. The second part consists of rigorous impact of oil price movements of global market analysis, to calculate oil price changes impact on the economic grwth, regression analysis is used. The third part presents the changes in oil prices in the future prospects of using future trends forecasting agencies, created three scenarios of oil price changes in the model. An investigation showed that the price of oil varies from a very range of variables, changes have significant variation in the macroeconomic process, including economc growth. So it is important to investigate the reasons for variation in oil prices. It has been reviewed and evaluated a wide variation in oil prices and anticipation of their impact on literary analysis. Regression analysis was the change in oil prices and economic growth interface. It was the future of oil prices changes features to create three future scenarios of oil price movements.
15

The Impact of the U.S. and Mexican Monetary Policy on Mexican GDP and Prices

Rodríguez Hernández, Lorenzo January 2015 (has links)
No description available.
16

Preferential Trade Agreements and Globalization: The Impact of a Common Foundation

Rothe, Holly M January 2004 (has links)
Thesis advisor: Robert Murphy / Given the increasing proliferation of preferential trade agreements, this work seeks to investigate the economic, political, and cultural relationships that may be built from the common foundation of a trade agreement. It evaluates the experiences of the European Union and the North American Free Trade Agreement and makes predictions and suggestions for future preferential trading partners, as well as analyzing the potential impact that PTAs will have on globalization and international relations. / Thesis (BA) — Boston College, 2004. / Submitted to: Boston College. College of Arts and Sciences. / Discipline: International Studies. / Discipline: College Honors Program.
17

O conflito de jurisdição entre sistemas de soluções de controvérsias multilateral e regional

Santos, Ruth Maria Pereira dos January 2013 (has links)
Submitted by Haia Cristina Rebouças de Almeida (haia.almeida@uniceub.br) on 2015-03-05T17:43:50Z No. of bitstreams: 1 61100076.pdf: 957663 bytes, checksum: 4abb255d7310b6713af2913df034df4f (MD5) / Made available in DSpace on 2015-03-05T17:43:50Z (GMT). No. of bitstreams: 1 61100076.pdf: 957663 bytes, checksum: 4abb255d7310b6713af2913df034df4f (MD5) / Este trabalho visa a analisar os conflitos de jurisdição existentes entre os sistemas de solução de controvérsias regional e multilateral. Primeiramente se faz o cotejo da evolução dos dois sistemas de comércio internacional, de modo a comprovar que ambos partem de uma mesma vertente, não sendo contraditórios, podendo atuar conjuntamente, uma vez que não há hierarquia entre a Organização Mundial do Comércio (OMC) e os Acordos Regionais. Contudo, há uma ausência de normas que discipline a relação entre os mecanismos de resolução de litígio. Para tanto, trata-se de mecanismos existentes no Direito Público, a fim de verificar a aplicabilidade no Direito Internacional Econômico, tais como os institutos oriundos da Teoria Geral do Processo, a conexão, a litispendência e a coisa julgada. Além das cláusulas de eleição de foro que estão inseridas em alguns textos normativos dos acordos regionais, bem como, os princípios do foro non conveniens e foro conveniens. Assim, descreve-se o posicionamento da jurisprudência da OMC e atuação dos mecanismos regionais em dois casos em que houve conflito de jurisdição entre a OMC e os blocos regionais (NAFTA e MERCOSUL).
18

Separation of light naphtha for the octane upgrading of gasoline : adsorption and membrane technologies and new adsorbents

Bárcia, Patrick da Silva January 2010 (has links)
Tese de doutoramento. Engenharia Química e Biológica. Faculdade de Engenharia. Universidade do Porto. 2010
19

Mexican refugees in Canada post-NAFTA and the effects of immigration and refugee policy reforms: 1994-2012

Hashman, Emma Therese 01 May 2013 (has links)
Canada and Mexican relations have not been written about in much length past Canada's Temporary Foreign Worker Program (TFWP) recruiting Mexican laborers. In recent years, migration from Mexico to Canada has increased at an exponential rate. The most significant and notable increase has been in the number of refugee claims from Mexicans wanting to seek asylum in Canada. It is found that Canada is the number one destination for Mexican refugees, while Canada accepts their claims at an alarmingly low rate compared to claims from other nations, even in Latin America. I argue the reason Mexicans chose Canada to claim refugee status is Canada's long history of an open immigration policy and especially their economic and temporary labor agreements with Canada. These policies give the impression to Mexicans they are very much welcome in Canada. This is proved to be untrue when Canada changed their immigration and refugee policies in response, specifically, to the overwhelming number of Mexican refugee claims.
20

The Effect of Neoliberalism on Capabilities: Evaluating the Case of Mexico

Walker, James Paul 20 October 2015 (has links)
The goal of this thesis is to examine the effect of neoliberalism on developing nations. Specifically it will look at how neoliberalism has affected Mexico via the North American Free Trade Agreement. Mexico was chosen because since its depression in 1982 it has adopted continuing neoliberal policy, which according to its leaders, United States leaders, and international governmental bodies, is the path to development and the improvement of the standard of living for all people. This work begins by examining the historical path of neoliberalism to provide context for choosing Mexico for the focal point of this thesis, as well as context for the situation occurring in Mexico. It then examines neoliberalism via its scholars who are in support of it and against it. This is followed by an evaluation method based off of Amarya Sen's capability approach to development. Then several previous studies are examined to prove qualitatively that there have been adverse effects experienced under NAFTA in Mexico, by all of the established evaluation parameters. Then this thesis turns to a discussion of some descriptive statistics relating to the approach set up by Sen. It concludes with quantitative approach showing over interesting correlations of neoliberalism, to other variables indicative of capabilities via linear regression.

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