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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.

Sediment dynamics on the inner continental shelf of the Basque country (N. Spain)

Uriarte, Adolfo January 1998 (has links)
No description available.

Essays in Growth and Development

January 2013 (has links)
abstract: This dissertation consists of three essays that broadly deal with the growth and development of economies across time and space. Chapter one is motivated by the fact that agricultural labor productivity is key for understanding aggregate cross-country income differences. One important proximate cause of low agricultural productivity is the low use of intermediate inputs, such as fertilizers, in developing countries. This paper argues that farmers in poor countries rationally choose to use fewer intermediate inputs because it limits their exposure to large uninsurable risks. I formalize the idea in a dynamic general equilibrium model with incomplete markets, subsistence requirements, and idiosyncratic productivity shocks. Quantitatively, the model accounts for two-thirds of the difference in intermediate input shares between the richest and poorest countries. This has important implications for cross-country productivity. Relative to an identical model with no productivity shocks, the addition of agricultural shocks amplifies per capita GDP differences between the richest and poorest countries by nearly eighty percent. Chapter two deals with the changes in college completion in the United States over time. In particular, this paper develop a dynamic lifecycle model to study the increases in college completion and average IQ of college students in cohorts born from 1900 to 1972. I discipline the model by constructing historical data on real college costs from printed government reports covering this time period. The main finding is that that increases in college completion of 1900 to 1950 birth cohorts are due primarily to changes in college costs, which generate a large endogenous increase in college enrollment. Additionally, evidence is found that supports cohorts born after 1950 underpredicted sharp increases in the college earnings premium they eventually received. Combined with increasing college costs during this time period, this generates a slowdown in college completion, consistent with empirical evidence for cohorts born after 1950. Lastly, the rise in average college student IQ cannot be accounted for without a decrease in the variance of ability signals. This is attributed the increased precision of ability signals primarily to the rise of standardized testing. Chapter three again deals with cross-country income differences. In particular, it is concerned with the fact that cross-country income differences are primarily accounted for by total factor productivity (TFP) differences. Motivated by cross-country empirical evidence, this paper investigates the importance individuals who operate their own firms because of a lack of other job opportunities (need-based entrepreneurs). I develop a dynamic general equilibrium labor search model with with entrepreneurship to rationalize this misallocation across occupations and assess its role for understanding cross-country income differences. Developing countries are assumed to have tighter collateral constraints on entrepreneurs and lower unemployment benefits. Because these need-based entrepreneurs actually have a comparative advantage as workers, they operate smaller and less productive firms, lowering aggregate TFP in developing countries. / Dissertation/Thesis / Ph.D. Economics 2013

Sustainable Food Production : Farmers’ management of their agroforestry  systems in Tanzania.

Hägglund, Johanna January 2015 (has links)
The future of food production contains some challenges. The production needs to increase in order to feed a growing population, but at the same time there is an increased need to transi- tion to more sustainable ways of cultivation. This can be a challenge since increased intensity and sustainability is not always compatible. Agroforestry systems have shown potential as sustainable food production system in previous research. The area where this study was con- ducted, Haraa in Babati District, has a long history of agroforestry. The aim of this study was to answer what resources agroforestry farmers used to manage their farms, to determine if the agroforestry systems could be regarded as sustainable. Circular economy was used as a theo- retical framework and resource flow as an analytical tool. This study investigated how the resource flow looked like on six agroforestry farms in a Haraa, a village in Tanzania. The empirical data was gathered with semi-structured interviews from 8 informants. The analysis showed that the farmers were dependent on few external resources and could produce or pre- form most of the needed resources inside their own system. The farms had a circular flow to a large extent, but some of the farms have room for improvement in the management regarding sustainability.

Some results on bilinear control systems with rank-one inputs

Chou, Yonggang January 1995 (has links)
No description available.


2016 January 1900 (has links)
Pulse crops included in a crop rotation can reduce nitrogen (N) requirements via biological N2 fixation (BNF) and provide greater carbon (C) inputs to soil than non-pulse crops in rotation. The goal of this research was to estimate the BNF and C input to soil by various pulse crops (chickpea, lentil and field pea) grown in rotation with pulse crops and non-pulse crops. Soil cores from three crop rotations (chickpea-wheat, lentil-wheat and pea-wheat) were collected from Swift Current, SK. Additional soil cores from two rotations (canola-wheat and wheat-canola) were extracted from a field used for commercial cropping in Central Butte, SK. The 15N dilution method and continuous labelling with depleted 13CO2 were used to estimate BNF and 13C input to soil by pulse crops grown in a greenhouse. The continuous labelling with depleted 13CO2 was effective in depleting 13C in plants. The movement of 13C from plant to soil C pools via rhizodeposition was also observed. However, an accurate amount of 13C transferred was not measurable. Different pulse crop performed differently in rotation. Pea had the greatest amount of BNF and produced the most residue-C (pods, stems, leaves and roots) compared to chickpea and lentil. The crop grown in the first year of the three-year rotation also influenced the pulse crops grown in the third year of the rotation. Cropping the same first year and third year pulse crop in rotation (chickpea-wheat-chickpea and lentil-wheat-lentil) performed better than growing different first year and third year pulse crops in rotation (pea-wheat-chickpea and pea-wheat-lentil). Pulse crops grown immediately after wheat yielded better and fixed more N than those after canola. Growing a pulse crop after canola is not recommended in this soil zone.

Uma proposta de método de inteligência competitiva para empresas de insumos do agronegócio / A framework proposal for competitive intelligence for agribusiness input companies

Monaco Neto, Lourival Carmo 31 May 2019 (has links)
O conhecimento e consequentemente a inteligência passaram a ser umas das principais fontes de vantagem competitiva das empresas, dadas as grandes mudanças nas conjunturas dos mercados. Essa necessidade de inteligência, permeia todos os agentes produtivos que compõem o mercado, inclusive o do agronegócio. Tendo isso em mente, o objetivo central desta pesquisa foi propor um método para o processo de inteligência competitiva que consolide e integre a literatura de inteligência e contemple os aspectos críticos da indústria de insumos agropecuários no Brasil, considerando a hipótese de que que os métodos contemplam de forma superficial às necessidades específicas desse setor, e que um método mais específico poderia ser construído. Para atingir esse objetivo foram empregadas as seguintes estratégias de pesquisa: a) Pesquisa bibliográfica (desk research) e análise documental como um método de pesquisa integrado e complementar; b) Realização de entrevistas com especialistas; e c) Construção de método. Dessa forma, o resultado foi a construção de um método de inteligência competitivo para empresas de insumos do agronegócio brasileiro composto de nove etapas. A hipótese foi aceita e concluiu-se que este método atendeu aos objetivos propostos, pois reuniu a literatura existente, inclusive com conceitos digitais atuais (Big Data e Data Mining), além de atender às necessidades e especificidades do setor ao focar em seus aspectos críticos / The knowledge, and therefore, intelligence became one of the most important sources of competitive advantage for companies, given the markets\' major recent changes. This need for accurate intelligence, for those who really need it and on the time that it is needed permeates all agents, of all markets, in all sectors, including the agribusiness, one of the Brazil\'s most important economic sectors, specially the agribusiness input companies. With that in mind, this research\'s the main objective was to propose a framework for the competitive intelligence process that consolidates the literature regarding competitive intelligence and contemplates the Brazilian agribusiness\' input sector critical aspects. The hypothesis was that the existing frameworks contemplate superficially the sector\'s specific needs, due to the concepts\' generality and that a more specific framework could be built, taking into consideration the characteristics of that sector. To achieve this objective the following research strategies were employed: a) Bibliographic research (desk research) and documental analysis as an integrated research method; b) Interviews with specialists; and c) Framework construction. Therefore, the result was the construction of a competitive intelligence framework form Brazilian agribusiness\' input companies with nine phases. The hypothesis was accepted and in conclusion, this framework met the proposed objectives because it integrated the existing intelligence literature, including contemporary digital concepts such as Big Data and Data Mining, in addition to answering the sector\'s specific needs by focusing on its\' critical aspects

Estudo da cristalização, caracterização polimórfica e influência sobre a dissolução in vitro do tenoxicam em insumos e produtos farmacêuticos disponíveis no mercado nacional

Fries, Aline Tais January 2015 (has links)
O polimorfismo é um fenômeno relativamente comum entre os compostos farmacêuticos, e um dos principais problemas na produção e desenvolvimento de medicamentos. Sua presença pode acarretar prejuízos para a saúde da população e forte impacto econômico para as indústrias farmacêuticas ao influenciar diretamente nas propriedades mecânicas e biofarmacêuticas de insumos e produtos acabados. A investigação de polimorfismo associado aos oxicans, grupo pertencente à classe dos fármacos anti-inflamatórios não esteróides (AINEs), sofreu um incremento nos últimos anos, e para o fármaco tenoxicam relata-se a existência de quatro formas polimórficas na literatura. O objetivo deste trabalho foi caracterizar a presença de diferentes formas polimórficas de tenoxicam em insumos farmacêuticos ativos e formulações farmacêuticas orais e avaliar a influência sobre a dissolução in vitro. Com base na literatura, a análise inicial com a substância química de trabalho (SQT) demonstrou padrão difratométrico forma III. Diferentes condições para formação de formas polimórficas de tenoxicam foram aplicadas conforme Cantera et al. (2002), contudo, os diferentes processos de preparação de polimorfos do tenoxicam não conduziram a modificações na estrutura cristalina original da SQT. Dados complementares foram obtidos através da espectrofotometria no IV e DSC, que indicaram a inexistência de modificações no espectro original e ausência de eventos térmicos atípicos. A caracterização dos insumos farmacêuticos do tenoxicam, provenientes de diferentes fornecedores, por IV, DRX e perfil de dissolução indicou presença da estrutura cristalina (forma III), sem apresentar diferenças significativas entre os perfis de dissolução in vitro. As especialidades farmacêuticas do tenoxicam disponíveis no mercado nacional, ao serem submetidas à análise por DRX, também apresentaram estruturas cristalinas forma III. Apesar de ocorrer perfis de dissolução diferentes entre as formulações, estas não apresentaram comprometimento em sua qualidade. Contudo, muitas vezes as transformações pós-processamento podem induzir a alterações na estrutura cristalina e por consequência, problemas biofarmacêuticos. Tal fato demonstra a importância do estudo do polimorfismo, ao avaliar e correlacionar a presença de estruturas cristalinas com alterações na qualidade e desempenho de insumos e produtos farmacêuticos. / Polymorphism is a relatively common phenomenon among pharmaceutical compounds, and one of the main problems in producing and developing drugs. Its presence may harm people’s health and have a strong economic impact on the pharmaceutical industries by directly influencing the mechanical and biopharmaceutical properties of inputs and finished products. The investigation of polymorphism associated with oxycans, a group belonging to the class of non-steroidal anti-inflammatory drugs (NSAIDs), has grown in recent years, and it is reported that there are four polymorphic forms for tenoxycam the literature. The purpose of this study was to characterize the presence of different polymorphic forms in active pharmaceutical inputs and oral pharmaceutical formulations and evaluate their influence on in vitro dissolution. Based on the literature, the initial analysis with the reference standard showed a form III diphractometric pattern. Polymorphic forms of tenoxycam were prepared according to Cantera et al. (2002), but the different preparation processes of tenoxycam polymorphs did not lead to modifications of the original crystalline structure of the reference standard. Complementary data were obtained by spectrophotometry in IV and DSC, indicating that there were no modifications in the original spectrum and no atypical thermal events. The characterization of the pharmaceutical inputs of tenoxycam, from different suppliers, as IV, DRX and dissolution profile indicated the presence of a crystalline structure (Form III), without presenting significant differences between the in vitro dissolution profiles. The pharmaceutical specialties of tenoxycam available on the national market, on being analyzed by DRX also presented crystalline structures Form III. Although there was different dissolution profiles between the formulations, they showed no impairment in their quality. However, often the post-processing transformations can induce alterations in the crystalline structure and, consequently, biopharmaceutical problems. This shows the importance of the study of polymorphism with the evaluation and correlation of the presence of crystalline structures with alterations in the quality and performance of pharmaceutical inputs and products.

Gaussian Two-Way Channel with Constellation-based Input

Banijamali, Seyedershad January 2013 (has links)
Achieving a higher transmission rate had always been a goal in the field of communications. Having a two-way channel in which two nodes transmit and receive data at the same time, is an important tool to achieve this goal. A two-way channel is the first step from point-to-point communication channel toward multi-user networks. In its ideal form, we can transmit data two times faster by using a perfect two-way channel. However, the area of two-way channels had not been of interest of researchers during the past years and number of articles on this area is considerably low comparing to other types of multi-user communication networks, such as multiple-access channel, broadcast channel and interference channel. On the other hand, use of analog-to-digital converters (ADC) is a must in modern systems to enable us to analyze data faster; nevertheless, presence of ADC add some other difficulties to the system. In this thesis, different scenarios about two-way channel are studied. The Shannon's model of two-way channel and his inner and outer bounds on the capacity of this channel are presented. For the Gaussian Two-Way Channel with quantized output, in which the ambient noise has a Gaussian distribution, the expression of Shannon's inner bound for both Gaussian and discrete inputs are derived. The best uniform quantizer to obtain the maximum achievable rate for Gaussian input is found numerically. Then we will evaluate the additive noise model for the quantizer from an information theoretic point of view. For the discrete input, the method of rotating one input with respect to other one is employed to enlarge the achievable rate region. At last, two scenarios will be studied in which, minimizing the power of interference, does not necessarily maximizes the transmission rate.

Essays on Efficiency Analysis

Asava-Vallobh, Norabajra 2009 May 1900 (has links)
This dissertation consists of four essays which investigate efficiency analysis, especially when non-discretionary inputs exist. A new approach of the multi-stage Data Envelopment Analysis (DEA) for non-discretionary inputs, statistical inference discussions, and applications are provided. In the first essay, I propose a multi-stage DEA model to address the non-discretionary input issue, and provide a simulation analysis that illustrates the implementation and potential advantages of the new approach relative to the leading existing multi-stage models of non-discretionary inputs, such as Ruggiero's 1998 model and Fried, Lovell, Schmidt, and Yaisawarng's 2002 model. Furthermore, the simulation results also suggest that the constant returns to scale assumption seems to be preferred when observations have similar sizes, but variable returns to scale may be more appropriate when their scales are different. In the second essay, I make comments on Simar and Wilson work of 2007. My simulation evidence shows that traditional statistical inference does not underperform the bootstrap process proposed by Simar and Wilson. Moreover, my results also show that the truncated model recommended by Simar and Wilson does not outperform the tobit model in terms of statistical inference. Therefore, the traditional method, t-test, and the tobit model should continue to be considered applicable tools for a multi-stage DEA model with non-discretionary inputs, despite contrary claims by Simar and Wilson. The third essay raises an example of applying my new approach to data from Texas school districts. The results suggest that a lagged variable (e.g. students' performance in the previous year), a variable which has been used in the literature, may not play an important role in determining efficiency scores. This implies that one may not need access to panel data on individual scores to study school efficiency. My final essay applies a standard DEA model and the Malmquist productivity index to commercial banks in Thailand in order to compare their efficiency and productivity before and after Thailand?s Financial Sector Master Plan (FSMP) that was implemented in 2004.

Micro and small-scale generation in urban distribution networks

Acosta Alvarez, Jorge Luis January 2013 (has links)
As the world moves towards a more sustainable development, the energy coming from fossil fuels still produces the greenhouse gases that threaten the world’s climate. The UK government has established targets for the penetration of renewable energy generation and low-carbon alternatives for the electricity production. One of these technologies is microgeneration. In 2006, the UK government launched the Microgeneration Strategy pushing forward micro and small-scale generation as a supplementary source of energy for the country’s growing electricity demand. The proposal is focused on several technologies, including micro-wind and micro-PV, among others. These microgeneration technologies are now a reality and widespread across the distribution networks. Therefore, the analysis of the impact of these systems connected to distribution grids and the benefits of these technologies, alongside with their negative effects on the network is an important research area. Correct modelling of micro and small-scale renewablebased generation technologies implemented in urban areas, however, is not a simple task, as it requires an adequate representation of highly dispersed and uncontrolled generation systems. These systems are small in size, but high in numbers and usually experience large variations in available renewable energy inputs. This thesis presents aggregate models of urban micro and small-scale PV and wind generation systems, which are connected to low-voltage networks. The thesis analyses impact of urban PV and wind generation on the steady-state network performance (power flows and voltage profiles), taking into account variability of energy inputs. The presented analysis is of particular importance for the analysis of the future of power system supplies, which will have significantly higher penetration levels of renewable-based distributed generation technologies, resulting in a much wider range of interactions between microgeneration systems, loads and transmission/distribution networks. In order to perform this analysis, the resource assessment for urban areas has to be carried out to both quantify the potential for each technology and help in their modelling. This has been a challenge since the aggregation of microgeneration systems is far from simple, as the parameters, performance and size varies between different technologies. A solution presented in this thesis is an approach for simple yet accurate aggregation of microgeneration technologies. This approach allows to quantify and analyse their impact and effect on the power supply systems directly in terms of penetration levels and general technology characteristics.

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