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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.
231

Aspectos do glufosinato de amônio como principal ferramenta de controle no manejo de plantas daninhas na soja / Aspects of ammonium gluphosinate as the main control tool for weed management in soybean

Franzoni, Maiara Maria 14 March 2018 (has links)
A soja tolerante ao glufosinato de amônio (Liberty Link ®) foi lançada comercialmente no Brasil na safra 2016/2017, sendo pouco conhecido seu desempenho agronômico e impacto na nodulação e colonização micorrízica arbuscular. O objetivo foi avaliar o esse sistema de produção envolvendo o herbicida glufosinato de amônio nos seguintes aspectos: (i) eficácia de controle de plantas daninhas; (ii) seletividade para a cultura da soja; (iii) impacto dos cultivares de soja e do glufosinato de amônio sobre a nodulação e colonização micorrízica arbuscular. Para isso, foi desenvolvido experimento em campo, em área de produção comercial da cultura, em que tais aspectos foram avaliados em diferentes cultivares de soja (convencional, tolerante ao glifosato ou glufosinato de amônio) e em diferentes manejos de plantas daninhas (com e sem capina, aplicação de 1.440 g e.a. ha-1 de glifosato e 500 g i.a. ha-1 de glufosinato de amônio + 0,5 L ha-1 de óleo vegetal metilado). Foi conduzido experimento em casa de vegetação sobre seletividade dos herbicidas, nas mesmas doses e cultivares transgênicos do experimento em campo. Adicionalmente, foi realizado experimento em condições de casa de vegetação e em laboratório, avaliando a presença de glufosinato de amônio e glutamato na soja tolerante ou sensível ao glufosinato de amônio. Foi possível verificar baixa intoxicação das plantas de soja após aplicação do glufosinato de amônio, com rápida recuperação ao longo dos experimentos. Não houve diferença no controle de plantas daninhas (Alternanthera tenella, Sorghum halepense, Physalis angulata e Parthenium hysterophorus) e na produtividade de soja nos diferentes tratamentos. Pela representação de Draftsman foi possível observar que as espécies A. tenella, P.angulata e P. hysterophorus foram as que mais influenciaram na massa seca da comunidade infestante da cultura. Não houve diferença entre os tratamentos quanto à nodulação. Não se verificou influência da nodulação e micorrização sobre a produtividade. Embora a colonização micorrízica tenha sido significativamente menor na soja tolerante ao glufosinato com aplicação desse herbicida, isso não refletiu em redução da produtividade. Não foram constatados glufosinato de amônio e glutamato nas raízes das plantas que justificasse a diminuição da colonização micorrízica na soja tolerante ao glufosinato devido à aplicação do mesmo. O uso de glufosinato de amônio em soja tolerante ao herbicida, em comparação com outros sistemas utilizados, demonstrou ser seguro e similar à tecnologia tolerante ao glifosato, possibilitando outra opção de ferramenta de manejo de plantas daninhas na cultura da soja, sem interferência na produtividade final dos grãos, especialmente em condições nutricionais adequadas como ocorreu nesse estudo, sendo apenas alertado sobre seu possível impacto negativo na colonização micorrízica arbuscular. / The glufosinate-tolerant soybean (Liberty Link ®) was commercially launched in Brazil in the 2016/2017 harvest, with little knowledge of its agronomic performance and impact on nodulation and arbuscular mycorrhizal colonization. The aim was to evaluate the production system involving the soybean tolerant to the herbicide glufosinate ammonium in the following aspects: (i) weed management effectiveness; (ii) selectivity to the soybean crop; (iii) impact of soybean and ammonium glufosinate cultivars on nodulation and arbuscular mycorrhizal colonization. For this, a experiment was carried out in the field of commercial crop production, in which these aspects were evaluated in different soybean cultivars (conventional, tolerant to glyphosate or ammonium glufosinate) and different weed management (with and without weeding, application of glyphosate 1440 a.e. g ha-1 and ammonium glufosinate 500 a.i. g ha-1 + methylated vegetable oil 0.5 L ha-1). A experiment was conducted under greenhouse conditions on herbicide selectivity, in the same doses and transgenic cultivars of the field experiment. In addition, an experiment was carried out under greenhouse conditions and in the laboratory, evaluating the presence of ammonium glufosinate and glutamate in soybean tolerant to ammonium glufosinate or glyphosate. It was possible to verify low intoxication of soybean plants after application of ammonium glufosinate, with rapid recovery throughout the experiments. There was no difference in weed control (Alternanthera tenella, Sorghum halepense, Physalis angulata and Parthenium hysterophorus) and soybean yield in the different treatments. By the representation of Draftsman it was possible to observe that the species A. tenella, P.angulata and P. hysterophorus were the ones that most influenced the weed community dry mass of the culture. There was no difference among treatments in nodulation. There was no influence of nodulation and mycorrhization on productivity. Although mycorrhizal colonization was significantly lower in glufosinate tolerant soybean with application of this herbicide, it did not reflect a reduction in productivity. No glufosinate of ammonium and glutamate were found in the roots of the plants that justified the reduction of the mycorrhizal colonization in soybeans tolerant to glufosinate due to its application. The use of ammonium glufosinate in glufosinate-tolerant soybean, compared to other systems used, shows to be safe and similar to the glyphosate tolerant technology, allowing another option of weed management tool in the soybean crop, without interfering in the final productivity of the grains, especially in adequate nutritional conditions as occurred in this study, being only warned about its possible negative impact on arbuscular mycorrhizal colonization.
232

Estudo comparativo da produção de extrato seco de ´Bauhinia forficata` Link pelos processos ´spray-dryer` e leito de jorro / A comparative study of the production of dried extract of Bauhinia forficata Link by the spray-dryer and the spouted bed processes.

Souza, Claudia Regina Fernandes de 30 May 2003 (has links)
Este trabalho apresenta o desenvolvimento de uma metodologia experimental visando à produção de extrato seco padronizado de Bauhinia forficata Link. Um planejamento experimental de três fatores e três níveis tipo Box-Behnken e análise multi-resposta foram empregados na otimização do processo de extração. Dois processos distintos de secagem foram investigados: o processo leito de jorro e a secagem por nebulização (ou spray-drying). O objetivo foi avaliar a viabilidade e desempenho de ambos secadores para a produção de extrato seco. As variáveis estudadas foram a razão percentual entre a vazão mássica da solução extrativa alimentada ao sistema pela capacidade de evaporação, (Ws/Wmáx), a temperatura de entrada do gás de secagem, (Tge), a posição do sistema de atomização no leito de jorro (top spray e bottom spray) e a vazão do gás de secagem utilizada no spray-dryer, (Wg). O desempenho operacional dos secadores foi avaliado principalmente através da produtividade, da eficiência térmica do processo, da taxa de evaporação volumétrica, da razão entre a massa de ar usada/massa de água evaporada e da taxa de recuperação do produto. O produto seco foi caracterizado quanto a distribuição granulométrica, morfologia das partículas, teor de umidade residual, taxa de degradação dos flavonóides (marcadores químicos) e características farmacotécnicas. Os resultados reportados mostram que o leito de jorro apresentou significativa superioridade em todos os parâmetros estudados em relação ao processo spray-dryer, para as configurações e condições operacionais investigadas. Isso permite concluir que o secador de leito de jorro é uma alternativa tecnologicamente viável para a produção de extratos secos de plantas medicinais brasileiras apresentando maior eficiência e produtividade, fornecendo um produto de alta qualidade e valor comercial. / This work presents the development of an experimental methodology aiming to the production of standardized dried extracts of Bauhinia forficata Link. An experimental planning of three factors and three levels type Box-Behnken and multi-response analysis were used in the optimization of the extraction process. Two different drying processes were studied: the spouted bed and the spraydrying processes. The objective was the evaluation of the viability and of the performance of both dryers for the production of dry extract. The investigated parameters were the percentile ratio between the mass feed flow rate of extractive solution to the system by the evaporation capacity of the dryer, (Ws/Wmáx), the inlet temperature of the drying gas, (Tge), the position of the atomization system in the spouted bed (top spray and bottom spray) and the mass flow rate of the drying gas used in the spray-dryer, (Wg). The operational performance of the dryers was evaluated mainly by the productivity, thermal efficiency of the process, rate of volumetric evaporation, ratio between the mass of air used by the mass of evaporated water and by the product recovery rate. The dried product was characterized by the particle size distribution, particles morphology, moisture content, flavonoid degradation rate (chemical marker), and by evaluation of pharmacotechnical properties. The results reported show that the spouted bed process presented a significant superiority in all parameters evaluated relative to the spray-drying process, for the configurations and operational conditions investigated. These results lead to the conclusion that the spouted bed process is an alternative technologically viable for the production of dry extracts of medicinal Brazilian plants, presenting high thermal efficiency and productivity, yielding a product of high quality and commercial value.
233

O evento de 11 de setembro nos EUA e o discurso da internet / The attack of September 11th in the USA and the Internet\' s discourse

Campos, Sidney de 11 September 2006 (has links)
Este trabalho é uma análise do hipertexto veiculado pela Internet sob a ótica da Análise do Discurso e da Semântica Histórica da Enunciação. Temos como ponto de partida uma discussão sobre os aspectos do suporte digital de textos e as mudanças que podem causar no processo de construção do significado. O objetivo é estudar os movimentos efetuados durante a navegação pela Internet e verificar se o processo de abertura e fechamento de páginas pode afetar a construção de sentidos. O corpus foi coletado de um Website jornalístico (CNN.com), o qual cobriu as primeiras horas posteriores ao ataque de 11 de Setembro nos EUA. Esse ato inédito contra o território americano inspirou um grande volume de produção de textos, além de a Internet ter sua primeira chance de cobrir um evento dessa proporção. Assim, tanto o ataque quanto a cobertura dessa mídia podem ter gerado elementos novos que contribuíram para a formação de outros métodos de se escrever e ler a notícia. Em nossa análise, observamos elementos verbais e não-verbais, bem como a importância desses componentes que não apenas dão forma à identidade do hipertexto, mas também contribuem para o processo de apreensão de sentidos. A ativação desses elementos proporciona à Internet um sistema de operação intertextual que pode demonstrar algumas mudanças na maneira em que as informações são processadas por aqueles que as produzem e pelos outros que as lêem. / This is an analysis of the hypertext in the Internet using principles of Discourse Analysis and Historic Semantics which starts from a discussion about some features of the digital text support and the changes it may be causing in the process of signification. The objective is to study the movements made during the navigation of the Internet and verify if the process of opening and closing pages may affect the meaning formation. The corpus has been collected from a journalistic Website (CNN.com) that covered the first hours after the attack of September 11th in the USA. This unprecedented act against the American territory inspired an enormous amount of text production and the Internet had the first chance of covering an event of such a magnitude. Therefore both the attack and this media coverage may have provided firsthand elements that may have helped to found different methods of writing and reading the news. In the analysis we have observed verbal and non-verbal elements and the importance of these components that not only format the identity of the hypertext but also contribute to the process of meaning apprehension. The activation of these elements gives the Internet a system to operate inter-textual relations that may show some changes in the way information is processed by ones who produce it and the ones who read it.
234

Human capital resources, human resource management policies, and employee perceptions : an investigation of young professionals in the banking sector of Pakistan

Saqib, Syed Imran January 2018 (has links)
Situated within the human resource management and performance (HRM-P) link literature, this thesis explores the 'black box' of the mechanisms that link HRM practices and performance. By doing so, it sheds light on how and why HRM practices can lead to superior firm performance. Heeding calls for more nuanced and contextual work on understanding this link, this study uses qualitative responses from 79 industry experts, HR/senior managers, and young professionals, as well as artefacts and documents, to analyse the causal mechanisms that connect HRM policies, aimed at human capital resource (HCR) accumulation, to employee outcomes in five banking organizations in Pakistan. Using the strength of HR process conceptualization and the process model of HR, the thesis looks at the entire chain that connects intended, actual, and perceived HR policies to understand why HR managers' and young professionals' perceptions of both the content and the process of HR implementation varies, and how this is connected with the employee outcomes of turnover intentions and job satisfaction. The first set of findings reveals that there is considerable difference in how the quality of the content of HR systems is perceived from the point of view of young professionals in comparison with HR practitioners. Young professionals have strong negative perceptions of HR policies related to their long-term career development, which is explained in part by the incongruence and the lack of focus of HR on the goal of HCR accumulation. The second set of findings show that there are several processual factors that help to explain these varying perceptions, which dilute the implementation of HR practices. The analysis reveals that the competency of HR departments, the role of line managers, elements of the Pakistani culture, and the role of top management shape the quality of the HR system that is implemented. Connecting this to employee outcomes, the analysis reveals that the link between HR and performance is not straightforward; this helps to explain the moderate statistical effects noted in the extant HRM-P link research. Employee reactions are more related to their personal circumstances and other organizational factors rather than HR factors. The third set of findings expands the analysis to individual contexts of the five banks, further revealing that the mission of the organization, the presence of a strong HR leader, external economic factors, and the historical legacy of the organisation also shapes employee perceptions and, thus the effectiveness of HR policies and their implementation. The thesis makes a theoretical contribution to the HRM-P link literature by revealing that the competitive advantage that stems, in part, from the actions of HR departments derives from how well they navigate the various processual factors that can impede HR system implementation. It makes a methodological contribution by responding to calls for more in-depth qualitative research on the phenomenon, by using a specific segment of employees within the under-represented context of Pakistan. It makes a practical contribution by highlighting that many western prescriptions, such as talent management and bell curves, may be less effective if prevailing cultural constraints are not accounted for, especially in developing countries like Pakistan. Existing HRM-P link studies have not adequately considered these contextual and cultural factors in their analyses.
235

Aspectos do glufosinato de amônio como principal ferramenta de controle no manejo de plantas daninhas na soja / Aspects of ammonium gluphosinate as the main control tool for weed management in soybean

Maiara Maria Franzoni 14 March 2018 (has links)
A soja tolerante ao glufosinato de amônio (Liberty Link ®) foi lançada comercialmente no Brasil na safra 2016/2017, sendo pouco conhecido seu desempenho agronômico e impacto na nodulação e colonização micorrízica arbuscular. O objetivo foi avaliar o esse sistema de produção envolvendo o herbicida glufosinato de amônio nos seguintes aspectos: (i) eficácia de controle de plantas daninhas; (ii) seletividade para a cultura da soja; (iii) impacto dos cultivares de soja e do glufosinato de amônio sobre a nodulação e colonização micorrízica arbuscular. Para isso, foi desenvolvido experimento em campo, em área de produção comercial da cultura, em que tais aspectos foram avaliados em diferentes cultivares de soja (convencional, tolerante ao glifosato ou glufosinato de amônio) e em diferentes manejos de plantas daninhas (com e sem capina, aplicação de 1.440 g e.a. ha-1 de glifosato e 500 g i.a. ha-1 de glufosinato de amônio + 0,5 L ha-1 de óleo vegetal metilado). Foi conduzido experimento em casa de vegetação sobre seletividade dos herbicidas, nas mesmas doses e cultivares transgênicos do experimento em campo. Adicionalmente, foi realizado experimento em condições de casa de vegetação e em laboratório, avaliando a presença de glufosinato de amônio e glutamato na soja tolerante ou sensível ao glufosinato de amônio. Foi possível verificar baixa intoxicação das plantas de soja após aplicação do glufosinato de amônio, com rápida recuperação ao longo dos experimentos. Não houve diferença no controle de plantas daninhas (Alternanthera tenella, Sorghum halepense, Physalis angulata e Parthenium hysterophorus) e na produtividade de soja nos diferentes tratamentos. Pela representação de Draftsman foi possível observar que as espécies A. tenella, P.angulata e P. hysterophorus foram as que mais influenciaram na massa seca da comunidade infestante da cultura. Não houve diferença entre os tratamentos quanto à nodulação. Não se verificou influência da nodulação e micorrização sobre a produtividade. Embora a colonização micorrízica tenha sido significativamente menor na soja tolerante ao glufosinato com aplicação desse herbicida, isso não refletiu em redução da produtividade. Não foram constatados glufosinato de amônio e glutamato nas raízes das plantas que justificasse a diminuição da colonização micorrízica na soja tolerante ao glufosinato devido à aplicação do mesmo. O uso de glufosinato de amônio em soja tolerante ao herbicida, em comparação com outros sistemas utilizados, demonstrou ser seguro e similar à tecnologia tolerante ao glifosato, possibilitando outra opção de ferramenta de manejo de plantas daninhas na cultura da soja, sem interferência na produtividade final dos grãos, especialmente em condições nutricionais adequadas como ocorreu nesse estudo, sendo apenas alertado sobre seu possível impacto negativo na colonização micorrízica arbuscular. / The glufosinate-tolerant soybean (Liberty Link ®) was commercially launched in Brazil in the 2016/2017 harvest, with little knowledge of its agronomic performance and impact on nodulation and arbuscular mycorrhizal colonization. The aim was to evaluate the production system involving the soybean tolerant to the herbicide glufosinate ammonium in the following aspects: (i) weed management effectiveness; (ii) selectivity to the soybean crop; (iii) impact of soybean and ammonium glufosinate cultivars on nodulation and arbuscular mycorrhizal colonization. For this, a experiment was carried out in the field of commercial crop production, in which these aspects were evaluated in different soybean cultivars (conventional, tolerant to glyphosate or ammonium glufosinate) and different weed management (with and without weeding, application of glyphosate 1440 a.e. g ha-1 and ammonium glufosinate 500 a.i. g ha-1 + methylated vegetable oil 0.5 L ha-1). A experiment was conducted under greenhouse conditions on herbicide selectivity, in the same doses and transgenic cultivars of the field experiment. In addition, an experiment was carried out under greenhouse conditions and in the laboratory, evaluating the presence of ammonium glufosinate and glutamate in soybean tolerant to ammonium glufosinate or glyphosate. It was possible to verify low intoxication of soybean plants after application of ammonium glufosinate, with rapid recovery throughout the experiments. There was no difference in weed control (Alternanthera tenella, Sorghum halepense, Physalis angulata and Parthenium hysterophorus) and soybean yield in the different treatments. By the representation of Draftsman it was possible to observe that the species A. tenella, P.angulata and P. hysterophorus were the ones that most influenced the weed community dry mass of the culture. There was no difference among treatments in nodulation. There was no influence of nodulation and mycorrhization on productivity. Although mycorrhizal colonization was significantly lower in glufosinate tolerant soybean with application of this herbicide, it did not reflect a reduction in productivity. No glufosinate of ammonium and glutamate were found in the roots of the plants that justified the reduction of the mycorrhizal colonization in soybeans tolerant to glufosinate due to its application. The use of ammonium glufosinate in glufosinate-tolerant soybean, compared to other systems used, shows to be safe and similar to the glyphosate tolerant technology, allowing another option of weed management tool in the soybean crop, without interfering in the final productivity of the grains, especially in adequate nutritional conditions as occurred in this study, being only warned about its possible negative impact on arbuscular mycorrhizal colonization.
236

O evento de 11 de setembro nos EUA e o discurso da internet / The attack of September 11th in the USA and the Internet\' s discourse

Sidney de Campos 11 September 2006 (has links)
Este trabalho é uma análise do hipertexto veiculado pela Internet sob a ótica da Análise do Discurso e da Semântica Histórica da Enunciação. Temos como ponto de partida uma discussão sobre os aspectos do suporte digital de textos e as mudanças que podem causar no processo de construção do significado. O objetivo é estudar os movimentos efetuados durante a navegação pela Internet e verificar se o processo de abertura e fechamento de páginas pode afetar a construção de sentidos. O corpus foi coletado de um Website jornalístico (CNN.com), o qual cobriu as primeiras horas posteriores ao ataque de 11 de Setembro nos EUA. Esse ato inédito contra o território americano inspirou um grande volume de produção de textos, além de a Internet ter sua primeira chance de cobrir um evento dessa proporção. Assim, tanto o ataque quanto a cobertura dessa mídia podem ter gerado elementos novos que contribuíram para a formação de outros métodos de se escrever e ler a notícia. Em nossa análise, observamos elementos verbais e não-verbais, bem como a importância desses componentes que não apenas dão forma à identidade do hipertexto, mas também contribuem para o processo de apreensão de sentidos. A ativação desses elementos proporciona à Internet um sistema de operação intertextual que pode demonstrar algumas mudanças na maneira em que as informações são processadas por aqueles que as produzem e pelos outros que as lêem. / This is an analysis of the hypertext in the Internet using principles of Discourse Analysis and Historic Semantics which starts from a discussion about some features of the digital text support and the changes it may be causing in the process of signification. The objective is to study the movements made during the navigation of the Internet and verify if the process of opening and closing pages may affect the meaning formation. The corpus has been collected from a journalistic Website (CNN.com) that covered the first hours after the attack of September 11th in the USA. This unprecedented act against the American territory inspired an enormous amount of text production and the Internet had the first chance of covering an event of such a magnitude. Therefore both the attack and this media coverage may have provided firsthand elements that may have helped to found different methods of writing and reading the news. In the analysis we have observed verbal and non-verbal elements and the importance of these components that not only format the identity of the hypertext but also contribute to the process of meaning apprehension. The activation of these elements gives the Internet a system to operate inter-textual relations that may show some changes in the way information is processed by ones who produce it and the ones who read it.
237

Beam-Enabled Acoustic Link Establishment (BEALE) for underwater acoustic networks

Watkins, Karen Piecara 31 October 2013 (has links)
There is growing interest in developing reliable, high performance, underwater acoustic networks (UWANs). However, the acoustic communication channel, with its slow sound propagation, high signal attenuation, and low bandwidth, presents significant challenges to network designers. One advantage offered by the acoustic channel is the ability to form directional communication beams, which improve signal strength and reduce interference. The work presented here describes a novel medium access control protocol for UWANs designated Beam-Enabled Acoustic Link Establishment (BEALE). BEALE addresses the inherent challenges of the acoustic channel by incorporating two techniques: link-level scheduling and dynamic directional beam steering. BEALE neighbors exchange packets based on a link-level schedule negotiated between the two nodes. This scheduling allows nodes to steer transmit and receive beams in the appropriate direction at the appropriate time while minimizing control overhead. Using steered, directional beams increases the gain between sender and receiver, reduces the senders interference with other nodes, and, at the receiver, rejects possible interference from other nodes and noise sources common in the ocean, resulting in increased spatial reuse. The core protocol has been modeled in a UWAN simulator developed specifically for this research. The results demonstrate significant improvement in throughput and packet loss over two benchmark UWAN random access protocols when evaluated over a variety of spatial node topologies and traffic patterns. The core BEALE protocol is further enhanced herein by a Half-Duplex Sliding Window algorithm. The HDX Sliding window is shown through point-to-point simulation to markedly improve bandwidth utilization and error rate in large Bandwidth Delay Product (BDP) situations. Extension of the HDX Sliding Window to more complex multi-flow, two-way and multi-hop cases requires an additional level of communication coordination provided by the BEALE Sliding Window Scheduler presented here. The functional challenges and novel concept of the scheduler are described in detail. The BEALE protocol performance promotes a rich list of potential future research, such as rigorous characterization of the BEALE Sliding Window Scheduler, BEALE accommodation of mobile nodes, conceptual operability of a BEALE-enabled network of a central multi-beam sink node supporting large numbers of simple source nodes, and rate adaptation. / text
238

Soft-Switching High-Frequency AC-Link Universal Power Converters with Galvanic Isolation

Amirabadi, Mahshid 16 December 2013 (has links)
In this dissertation the ac-link universal power converters, which are a new class of power converters, are introduced and studied in detail. The inputs and outputs of these converters may be dc, ac, single phase, or multi-phase. Therefore, they can be used in a variety of applications, including photovoltaic power generation, wind power generation, and electric vehicles. In these converters the link current and voltage are both alternating and their frequency can be high, which leads to the elimination of the dc electrolytic capacitors and the bulky low-frequency transformers. Therefore, the ac-link universal power converters are expected to have higher reliability and smaller size. Moreover, these converters are soft switching, which results in negligible switching losses and minimized current and voltage stress over devices. In the first part of the dissertation, the parallel ac-link universal power converter is studied in detail. This converter is an extension of the buck-boost converter. The series ac-link universal power converter, which is dual of the parallel ac-link universal power converter, is proposed in the second part of this dissertation. This converter is an extension of the Cuk converter. A modified configuration with fewer switches, named sparse ac-link universal power converter is proposed in the third part of this dissertation. The sparse ac-link universal power converters can appear as parallel or series. The performance of all these configurations is evaluated through simulations and experiments.
239

Estudo comparativo da produção de extrato seco de ´Bauhinia forficata` Link pelos processos ´spray-dryer` e leito de jorro / A comparative study of the production of dried extract of Bauhinia forficata Link by the spray-dryer and the spouted bed processes.

Claudia Regina Fernandes de Souza 30 May 2003 (has links)
Este trabalho apresenta o desenvolvimento de uma metodologia experimental visando à produção de extrato seco padronizado de Bauhinia forficata Link. Um planejamento experimental de três fatores e três níveis tipo Box-Behnken e análise multi-resposta foram empregados na otimização do processo de extração. Dois processos distintos de secagem foram investigados: o processo leito de jorro e a secagem por nebulização (ou spray-drying). O objetivo foi avaliar a viabilidade e desempenho de ambos secadores para a produção de extrato seco. As variáveis estudadas foram a razão percentual entre a vazão mássica da solução extrativa alimentada ao sistema pela capacidade de evaporação, (Ws/Wmáx), a temperatura de entrada do gás de secagem, (Tge), a posição do sistema de atomização no leito de jorro (top spray e bottom spray) e a vazão do gás de secagem utilizada no spray-dryer, (Wg). O desempenho operacional dos secadores foi avaliado principalmente através da produtividade, da eficiência térmica do processo, da taxa de evaporação volumétrica, da razão entre a massa de ar usada/massa de água evaporada e da taxa de recuperação do produto. O produto seco foi caracterizado quanto a distribuição granulométrica, morfologia das partículas, teor de umidade residual, taxa de degradação dos flavonóides (marcadores químicos) e características farmacotécnicas. Os resultados reportados mostram que o leito de jorro apresentou significativa superioridade em todos os parâmetros estudados em relação ao processo spray-dryer, para as configurações e condições operacionais investigadas. Isso permite concluir que o secador de leito de jorro é uma alternativa tecnologicamente viável para a produção de extratos secos de plantas medicinais brasileiras apresentando maior eficiência e produtividade, fornecendo um produto de alta qualidade e valor comercial. / This work presents the development of an experimental methodology aiming to the production of standardized dried extracts of Bauhinia forficata Link. An experimental planning of three factors and three levels type Box-Behnken and multi-response analysis were used in the optimization of the extraction process. Two different drying processes were studied: the spouted bed and the spraydrying processes. The objective was the evaluation of the viability and of the performance of both dryers for the production of dry extract. The investigated parameters were the percentile ratio between the mass feed flow rate of extractive solution to the system by the evaporation capacity of the dryer, (Ws/Wmáx), the inlet temperature of the drying gas, (Tge), the position of the atomization system in the spouted bed (top spray and bottom spray) and the mass flow rate of the drying gas used in the spray-dryer, (Wg). The operational performance of the dryers was evaluated mainly by the productivity, thermal efficiency of the process, rate of volumetric evaporation, ratio between the mass of air used by the mass of evaporated water and by the product recovery rate. The dried product was characterized by the particle size distribution, particles morphology, moisture content, flavonoid degradation rate (chemical marker), and by evaluation of pharmacotechnical properties. The results reported show that the spouted bed process presented a significant superiority in all parameters evaluated relative to the spray-drying process, for the configurations and operational conditions investigated. These results lead to the conclusion that the spouted bed process is an alternative technologically viable for the production of dry extracts of medicinal Brazilian plants, presenting high thermal efficiency and productivity, yielding a product of high quality and commercial value.
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Fluxos de biomassa e padrões de desfolha em pastagem de papuã submetida a adubação nitrogenada / Biomass flows and defoliation patterns in alexandergrass pasture submitted to nitrogen fertilization

Hundertmarck, Anelise Pereira 26 February 2015 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The leaf biomass flows of Alexandergrass (Urochloa plantaginea (Link) Hitch), the intensity and frequency of defoliation were evaluated using Zero, 100, 200 or 300 kg ha-1 of nitrogen (N), in the form of urea. The grazing method was continuous with variable number of animals to keep the forage mass in 3000 kg ha-1 DM. The experimental animals were Angus heifers with age and initial average body weight of 15 months and 241.5±5.7 kg, respectively. The experimental design was completely randomized following a repeated measure arrangement measures with four treatments and variable number of experimental units. Application of 100 kg ha-1 N provided higher leaf blades growth flow. The senescence and intake fluxes and defoliation intensity were similar in N fertilizer rates used. The return frequency (days) was influenced by N rates and evaluation periods. It is recommended using 100 kg ha-1 N in Alexandergrass pasture. / Os fluxos de biomassa foliar do papuã (Urochloa plantaginea (Link) Hitch), a intensidade e frequência de desfolha foram avaliados com o uso de Zero, 100, 200 ou 300 kg ha-1 de nitrogênio (N), na forma de ureia. O método de pastejo foi contínuo com número variável de animais para manter a massa de forragem em 3000 kg ha-1 de MS. Os animais experimentais foram bezerras Angus com idade e peso corporal médio inicial de 15 meses e 241,5±5,7 kg, respectivamente. O delineamento experimental foi inteiramente casualizado, com medidas repetidas no tempo, com quatro tratamentos e número variável de unidades experimentais. O uso de 100 kg ha-1 de N proporcionou maior fluxo de crescimento de lâminas foliares. Os fluxos de senescência e de consumo e a intensidade de desfolha foram similares nas doses de N utilizadas. A frequência de retorno (dias) foi influenciada pelas doses de N e períodos de avaliação. É recomendada a utilização de 100 kg ha-1 de N em pastagem de papuã.

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