Made available in DSpace on 2014-08-20T14:33:03Z (GMT). No. of bitstreams: 1 dissertacao_liana_viviam_ferreira.pdf: 1066029 bytes, checksum: b8436d77d50bb76efeddb4cb96df3326 (MD5) Previous issue date: 2013-03-04 / The cultivation of edible pod peas in greenhouse and hydroponic system can be a viable alternative for obtaining high pods yield in winter and early spring crop-seasons. In addition, this crop system optimizes productive resources and causes reduced environmental impact. Currently, little information is available about edible pods pea crop, especially in greenhouse and hydroponic cultivation conditions. The adoption of this system presupposes to adequate plant density, as well as to produce knowledge and information regarding growth (dry matter production and partitioning) and yield of different genotypes. In this sense, two experiments were conducted with edible pods pea crop grown in hydroponic and greenhouse in winter/spring crop-season at the Campus of the Universidade Federal de Pelotas , in Capão do Leão, RS. The first experiment aimed to evaluate the effect of plant density on dry matter production and partitioning and yield components of edible pods pea crop 'Luana Gigante®'. Five planti densities (3.9, 4.7; 5.9, 7.8 and 11.8 plants m-2) were evaluated from May to November 2011. The second experiment aimed to characterize the growth and production dynamics of two edible pea pods genotypes ('Luana Gigante®' and 'MK10®') in a bifactorial model from May to November 2012. Genotypes composed the plots and evaluation dates composed subplots (0, 15, 30, 45, 60, 75, 95, 115 and 135 days after setting/DAS). In both experiments, biomass was quantified by dry weight of different above-ground plant organs and yield by pods fresh weight. The results obtained in the first experiment indicated that increasing of plant density in the range from 3.9 to 11.8 plants m-2 reduced linearly the growth of all organs and the individual plants pods yield. However, it increased linearly the absolute crop dry matter production and the pods yield per square meter. It did not affect the dry matter partitioning among different plant organs. The vegetative shoot plant organs were the major sinks for photoassimilates, comprising 61.5% of total plant dry matter, while the pods represented 31.7%. Among the yield components, only the number of harvested pods per plant was reduced and there were not negative effects on average pods fresh weight and the percentage of marketable pods. Therefore, we can recommend the plant density of 11.8 plants m-2 for pea crop 'Luana Gigante'. In the second experiment, it was observed that 'Luana Gigante' and 'MK10' presented a sigmoidal type plant growth curve as a function of time. MK10 presented higher vegetative shoot plant parts and crop growth than 'Luana Gigante'. 'MK10' also presented higher pods growth at 95 DAS, but both genotypes presented similar pods growth and yield at the end of the crop cycle. Pods comprised 36% and 43% of the total above-ground dry matter production, respectively, for 'MK10' and 'Luana Gigante' at the end of the crop cycle. Thus 'Luana Gigante' presents greater ability to assimilate distribution to pods growth than 'MK10'. The vegetative shoot organs are the strongest sinks for assimilates of the plant and stems are more beneficed in relation to the partition of dry matter than leaves. / A produção de ervilha torta em ambiente protegido e sistema hidropônico pode ser uma alternativa viável para a obtenção de alto rendimento de vagens no período de inverno e início de primavera, além de proporcionar melhor otimização dos recursos produtivos e reduzido impacto ambiental. Atualmente, existem poucas informações disponíveis sobre esta cultura, principalmente em condições de ambiente protegido e cultivo hidropônico. A adoção deste sistema pressupõe a adequação da densidade de plantio, assim como, produzir conhecimentos e informações referentes ao crescimento (produção e partição de massa seca) e comportamento produtivo de genótipos. Neste sentido, dois experimentos foram realizados com a cultura da ervilha torta em sistema hidropônico e ambiente protegido em ciclo de inverno/primavera no Campus da Universidade Federal de Pelotas, no município de Capão do Leão, RS. O primeiro experimento, realizado de maio a novembro de 2011, objetivou avaliar o efeito da densidade de plantio sobre a produção e a partição da massa seca e os componentes do rendimento de ervilha torta Luana Gigante® , em experimento unifatorial com cinco densidades de plantio (3,9; 4,7; 5,9; 7,8 e 11,8 plantas m-2). O segundo experimento objetivou caracterizar a dinâmica do crescimento e da produção de dois genótipos de ervilha torta ( Luana Gigante e MK10 ) em esquema bifatorial no período de maio a novembro de 2012. As parcelas foram constituídas pelos genótipos e as subparcelas pelas épocas de avaliação das plantas (aos 0, 15, 30, 45, 60, 75, 95, 115 e 135 dias após o transplante). Para ambos os experimentos, a biomassa foi quantificada através da massa seca dos diferentes órgãos aéreos da planta e o rendimento através da massa fresca de vagens. Em relação aos resultados obtidos no primeiro experimento, observou-se que o aumento da densidade de plantio no intervalo entre 3,9 a 11,8 plantas m-2 reduz o crescimento de todos os órgãos e a produtividade individual das plantas de forma linear. Porém, aumenta de forma linear a produção absoluta da massa seca da cultura bem como a produtividade por unidade de área e não afeta a partição proporcional de massa seca entre os diferentes órgãos da planta. Os órgãos vegetativos aéreos são os principais drenos de fotoassimilados, representando 61,5% da massa seca total das plantas, enquanto as vagens representam 31,7%. Entre os componentes do rendimento, somente o número de vagens colhidas por planta é reduzido, não havendo efeitos negativos sobre a massa fresca média das vagens e a porcentagem de vagens comerciais colhidas. Portanto, recomenda-se a densidade de 11,8 plantas m-2 para a ervilha torta Luana Gigante . No segundo experimento, observou-se que Luana Gigante e MK10 expressam crescimento da planta do tipo sigmoidal em relação ao acúmulo de MS ao longo do ciclo de cultivo. MK10 apresenta maior crescimento dos órgãos vegetativos aéreos e da cultura do que Luana Gigante . MK10 também apresenta maior crescimento de vagens aos 95 DAT, porém os genótipos se assemelham em relação ao crescimento e à produção de vagens ao final do ciclo de cultivo. As vagens representam 36% e 43% da massa seca aérea da planta, respectivamente de MK10 e Luana Gigante , ao final do ciclo de cultivo. Assim, Luana Gigante apresenta maior capacidade de destinar assimilados para o crescimento de vagens do que MK10 . O conjunto dos órgãos vegetativos aéreos são os principais drenos de assimilados da planta, sendo os caules priorizados na partição de MS em relação às folhas.

Made available in DSpace on 2014-08-20T14:33:07Z (GMT). No. of bitstreams: 1 Dissertacao_Marcelo_ de_ Queiroz_ Rocha.pdf: 725823 bytes, checksum: baf6fa097603da126ae27ec658aca762 (MD5) Previous issue date: 2009-03-27 / The use of a new production system demand to know the behavior of cultures and establish the most appropriate management. It is necessary to understand the relationships that control the operation of the plant, and then understand the way in which these relations are dazzling together to result in final income. The growth dynamic, the fenological characterization and yield components of the red cherry tomato crop (Lycopersicon esculentum var. cerasiforme), cultivated in hydroponic system during summer-autumn 2008 crop season, were studied through two experiments conducted in plastic greenhouse, in the Campus of the Universidade Federal de Pelotas, RS. The first experiment was carried out to study the effect of different levels of ionic concentration of the nutrient solution on growth and yield components of cherry tomato (number of fruits, fruit mean weight and fruit yield). This experimental factor was assessed in four different levels: standard nutrient solution, containing 100% of the concentration of nutrients recommended by "Japan Horticultural Experimental Station", corresponding to an initial electrical conductivity (ECi) of 2,3 dS m-1, nutrient solution with reductions of 25 and 50% and with increment of 25% in the concentration of nutrients in relation to the standard solution, corresponding to ECis of 1,3; 1,8 and 2,8 dS m-1, respectively. Another experimental factor in this study was the position of flower cluster and its influence on the yield components. The second experiment was conducted to verify the effect of low sink demand on the vegetative growth in plants cultivated with standard nutrient solution. Two treatments were established: low sink demand (no fruit on the plant by removing 11 all inflorescences) and high sink demand (by maintaining of inflorescences and allowing the fruit to the plant). In both experiments, from the data of dry matter and leaf area accumulated during the experimental period, the production and distribution of dry matter among the different organs of the plant and growth index were determined. The results obtained in the first experiment allow to concluded that: the vegetative stage comprised 30,9% of the crop cycle and the number of the flowers is not dependent on the inflorescence position on the main stem; the position of floral cluster in the plant does not affect the yield components number and weight of the fruit, with little influence on the production of fruits per cluster of cherry tomato; the change of the ion concentration of the nutrient solution (in a range from 1,3 to 2,8 dS m-1) does not affect the number of fruits per plant, but an EC higher than 2,3 dS m-1 causes a reduction in mean weight of the fruits; the leaf expansion, the fruit growth and yield of cherry tomato decrease when the ionic concentration of the nutrient solution increases in the range from 1,8 to 2,8 dS m-1 and when it is reduced from 1,8 to 1,3 dS m-1; the nutrient solution of 1,8 dS m-1 EC can be recommended to increase the fruit yield of cherry tomato in hydroponic system in the summer-autumn crop season. The results observed in the second experiment showed that the fruits corresponded to approximately 26% of the total dry matter of plants in which the fruits are allowed. Thus, in red cherry tomato plants, fruits were not the biggest sink of photoassimilates, since the leaves represented approximately 39% of total dry matter of plants which the fruits are allowed. Thus, the leaf fraction was characterized as the largest source and at the same time as the largest sink of photoassimilates. The fruits has competed more strongly with the leaves than the stems by photoassimilates, indicating that stem and leaves are not characterized as a single compartment for storage of photoassimilates. / O emprego de um novo sistema de produção demanda conhecer o comportamento das culturas e definir o manejo mais adequado. É necessário, portanto, conhecer as relações que regem o funcionamento da planta e, em seguida, compreender a forma segundo a qual todas essas relações se encandeiam entre si para resultar no rendimento final. A dinâmica do crescimento, a caracterização fenológica e os componentes do rendimento da cultura do tomate cereja vermelho (Lycopersicon esculentum var. cerasiforme), cultivado em sistema hidropônico durante o ciclo de verão-outono de 2008, foram estudados através de dois experimentos conduzidos em estufa plástica, no Campus da Universidade Federal de Pelotas, RS. O primeiro experimento foi realizado objetivando-se estudar o efeito de diferentes níveis de concentração iônica da solução nutritiva sobre o crescimento e os componentes do rendimento do tomateiro cereja (número de frutos, peso médio do fruto e produção de frutos). Este fator experimental foi avaliado em quatro diferentes níveis: solução nutritiva padrão, contendo 100% da concentração de nutrientes recomendada pela Japan Horticultural Experimental Station , correspondendo a uma condutividade elétrica inicial (CEi) de 2,3 dS m-1; soluções nutritivas com reduções de 25% e 50% e com incremento de 25% da concentração de nutrientes em relação à solução padrão, correspondendo a CEi de 1,3; 1,8 e 2,8 dS m-1, respectivamente. Outro fator experimental estudado neste experimento foi a posição do cacho floral e sua influência sobre os componentes do rendimento. As avaliações fenológicas foram realizadas em plantas conduzidas na solução padrão. O segundo experimento foi conduzido a fim de verificar o efeito da baixa demanda de drenos sobre o crescimento vegetativo em plantas cultivadas com solução 9 nutritiva padrão. Dois tratamentos foram estabelecidos: baixa demanda de drenos (ausência de frutos na planta através da remoção de todas as inflorescências) e alta demanda de drenos (através da permanência das inflorescências e permitindo-se a frutificação na planta). Em ambos os experimentos, a partir dos dados de matéria seca e da área foliar acumuladas ao longo do período experimental, determinou-se a produção e distribuição de matéria seca entre os diferentes órgãos aéreos da planta e os índices de crescimento. Através dos resultados obtidos no primeiro experimento conclui-se que: a fase vegetativa corresponde a 30,9% do ciclo de cultivo e o número de flores emitidas independe da posição da inflorescência na haste principal; a posição do cacho floral na planta não afeta os componentes do rendimento número e peso médio do fruto, exercendo pouca influência sobre a produção de frutos por cacho do tomateiro cereja; a variação da concentração iônica da solução nutritiva (na faixa entre 1,3 e 2,8 dS m-1) não afeta o número de frutos colhidos por planta mas uma CE superior a 2,3 dS m-1 provoca uma redução no peso médio do fruto; a expansão foliar, o crescimento de frutos e a produtividade do tomateiro cereja diminuem quando a concentração iônica da solução nutritiva aumenta no intervalo entre 1,8 e 2,8 dS m-1 e quando é reduzida de 1,8 para 1,3 dS m-1; a solução nutritiva com CE de 1,8 dS m-1 pode ser recomendada para aumentar a produtividade do tomateiro cereja em sistema hidropônico no ciclo de verão-outono. Os resultados observados no segundo experimento mostram que os frutos corresponderam à aproximadamente 26% da matéria seca total das plantas nas quais se permitiu a frutificação. Desta forma, no tomateiro cereja vermelho, os frutos não foram os maiores drenos de fotoassimilados, uma vez que as folhas representaram aproximadamente 39% da matéria seca total das plantas que frutificaram. Assim, a fração folhas caracterizou-se como a maior fonte e, ao mesmo tempo, como o maior dreno de fotoassimilados. Os frutos competem mais fortemente com as folhas do que com o caule pelos assimilados, indicando que caule e folhas não se caracterizam como um compartimento único de estocagem de fotoassimilados.

La capacité ultime du canal dans les systèmes de transmission optique à longue distance est limitée par les effets non linéaires liés à la propagation dans les fibres optiques. Des techniques de compensation des effets non-linéaires, tel que la DBP (Digital Back Propagation), ont été proposées pour surmonter ces limitations et accroître la capacité. Compte tenu de leur complexité d’implémentation, leur gain en performance reste très limité. Cela a déclenché très récemment la recherche de nouvelles techniques de communication prenant en compte la non-linéarité de la fibre. Une nouvelle méthode de communication en régime non-linéaire, basée sur la théorie de la transformation spectrale inverse (IST pour Inverse Spectral Transform), a été proposée pour surmonter la limitation induite par ces effets. Cette méthode, proposée à l'origine par Hasegawa en 1993, encore appelée communication aux valeurs propres (ou multi-solitons), est basée sur l'observation fondamentale selon laquelle le spectre non linéaire d'un signal optique est invariant (à l'exception d'un déphasage linéaire trivial) lors de la propagation dans la fibre optique, comme décrit par l’équation non linéaire de Schrödinger (NLSE pour Non-Linear Schrödinger Equation). Cela signifie que si la transformée spectrale directe (DST) (également appelée NFT pour Nonlinear Fourier Transform) du signal reçu peut être calculée, le spectre de valeurs propres peut être entièrement récupéré.Cette thèse porte sur une technique de communication de type NFT connue sous le nom de multiplexage non linéaire en fréquence (NFDM pour Non-Linear Fourier Transform). Différentes configurations de systèmes optiques NFDM ont été évalués numériquement et validés expérimentalement. Dans un premier temps, la structure d’un système NFDM en mono-polarisation utilisant le spectre continu des fréquences non-linéaires dans une fibre en régime de dispersion normale est décrite. Pour ce faire, une forme NFT du vecteur NLSE, encore appelé système de Manakov, a été développé numériquement. Sur la base de ces algorithmes, la méthode NFDM a été étendue aux systèmes multiplexés par division de polarisation (PMD) et validée expérimentalement pour la première fois en utilisant le spectre continu. Finalement, l’expérience a été répliquée en régime de dispersion anormale. Afin d'étudier les contraintes de mise en œuvre, des études numériques supplémentaires ont été effectués pour la transmission de signaux NFDM utilisant la modulation du spectre continu. / Nonlinear effects in optical fiber set the ultimate limit to the channel capacity in long-haul optical transmission systems. Advanced nonlinear compensation techniques such as digital backpropagation (DBP) have been proposed as a solution to overcome the channel capacity crunch. However, given theircomputational complexity, in a practical environment their performance gainremains very limited. This triggered a search for a novel communication system design that takes fiber nonlinearity into consideration. A new nonlinearcommunication method, based on the theory of the inverse spectral transform, has been proposed to overcome the nonlinear capacity crunch. Thismethod, originally proposed by Hasegawa in 1993 and called eigenvalue (ormulti-soliton) communication, is based on the fundamental observation thatthe nonlinear spectrum of an optical signal is invariant (except for a triviallinear phase shift) upon propagation in the fiber channel, as described bythe nonlinear Schrödinger equation (NLSE). This means that if the directspectral transform (also known as nonlinear Fourier transform (NFT)) ofthe received signal can be computed, the eigenvalue spectrum can be fullyrecovered.This thesis focuses on a NFT-based communication technique known as nonlinear frequency division multiplexing (NFDM). The NFDM optical systemis numerically assessed and experimentally demonstrated. First, the structure of the proposed single-polarization NFDM system using the continuousspectrum in the normal dispersion regime is presented. To that end, theNFT of the vector NLSE, or Manakov system, was numerically developed.Based on these algorithms the NFDM method was extended to polarizationdivision multiplexed (PMD) systems, and experimentally validated for thefirst time using the continuous spectrum. Finally, the experiment will bereplicated in the anomalous dispersion regime.Additional numerical studies are presented, in order to investigate the implementation challenges of the proposed NFDM techniques for the continuousspectrum modulation.

This research extends the capabilities of Non-oscillatory Forward-in-Time (NFT) solvers operating on unstructured meshes to allow for accurate simulation of incompressible turbulent flows. This is achieved by the development of Large Eddy Simulation (LES) and Detached Eddy Simulation (DES) turbulent flow methodologies and the development of parallel option of the flow solver. The effective use of LES and DES requires a development of a subgrid-scale model. Several subgrid-scale models are implemented and studied, and their efficacy is assessed. The NFT solvers employed in this work are based on the Multidimensional Positive Definite Advection Transport Algorithm (MPDATA) that facilitates novel implicit Large Eddy Simulation (ILES) approach to treating turbulence. The flexibility and robustness of the new NFT MPDATA solver are studied and successfully validated using well established benchmarks and concentrate on a flow past a sphere. The flow statistics from the solutions are compared against the existing experimental and numerical data and fully confirm the validity of the approach. The parallel implementation of the flow solver is also documented and verified showing a substantial speedup of computations. The proposed method lays foundations for further studies and developments, especially for exploring the potential of MPDATA in the context of ILES and associated treatments of boundary conditions at solid boundaries.

Submitted by Gabriela Lopes (gmachadolopesufpel@gmail.com) on 2016-09-23T14:12:33Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) TESE ISABELITA PORTELA.pdf: 1041077 bytes, checksum: ab07041b4f5b288211c6050c4c56dfd1 (MD5) / Made available in DSpace on 2016-09-23T14:12:33Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) TESE ISABELITA PORTELA.pdf: 1041077 bytes, checksum: ab07041b4f5b288211c6050c4c56dfd1 (MD5) Previous issue date: 2015-07-28 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Os sistemas de cultivo sem solo vêm avançando de forma acelerada no Brasil e surgem como alternativas para suprir as dificuldades de mão de obra e reduzir a aplicação de agrotóxicos nas lavouras de morango. Porém, predominam os sistemas “abertos” de cultivo, com drenagem perdida da solução nutritiva. Assim, por razões econômicas e ambientais, é imperativo desenvolver sistemas de cultivo “fechados”, que promovem a recirculação do lixiviado. Com o objetivo de se estudar o crescimento, a produtividade e a qualidade das frutas de morangueiro de cultivares de dia curto e de dia neutro em sistemas de cultivo sem solo com recirculação da solução nutritiva, dois experimentos foram realizados em condições de estufa plástica, no Campus da Universidade Federal de Pelotas, RS. O primeiro experimento, realizado no ano agrícola 2011/12, teve o objetivo de estudar diferentes sistemas de cultivo sem solo “fechados” para a cultivar de dia neutro Albion: a) sistema hidropônico NFT; b) sistema hidropônico NFT com brita na base do canal; c) cultivo em casca de arroz carbonizada (CAC); d) cultivo em casca de arroz in natura (CAIN). No segundo experimento, realizado em 2012/13, estudou-se o comportamento de cultivares de dia curto (Camarosa, Palomar e Ventana) e de dia neutro (Aromas, Monterey e Portola) em sistema “fechado” de cultivo com substrato de CAC. Em ambos os experimentos, avaliaram-se a matéria fresca e seca de folhas, coroa e frutas, o número, a massa média, o teor de sólidos solúveis e a acidez total titulável das frutas. Adicionalmente, no segundo experimento, a área foliar das plantas também foi avaliada. Os resultados obtidos no primeiro experimento indicam que o sistema NFT e o cultivo em CAC promoveram o crescimento e a produtividade das frutas (respectivamente, 420 e 437 g planta-1). O sistema com CAC aumentou também o crescimento vegetativo das plantas, o que elevou a massa média das frutas (14,8 g). Os sistemas de cultivo estudados afetaram o crescimento e a produtividade, mas não alteraram a distribuição da colheita e a qualidade das frutas no que se refere à concentração de açúcares e à acidez. Os resultados obtidos no segundo experimento indicam que as cultivares de dia neutro Portola, Aromas e Monterey apresentaram produtividades similares 9 (respectivamente, 619,2, 610,2 e 547,1 g planta-1). Entre as cultivares de dia curto, ‘Camarosa’ foi mais produtiva (408,7 g planta-1), seguida de ‘Ventana’ (333,8 g planta-1) e ‘Palomar’ (309,3 g planta-1). Em relação às características físicas e químicas das frutas, entre as cultivares de dia neutro, destacaram-se ‘Portola” pela maior massa média, ‘Aromas’ pelas maiores concentração de açúcares e acidez e ‘Monterey’ pela maior uniformidade de tamanho; entre as cultivares de dia curto, destacou-se ‘Ventana’ pelas maiores massa média, concentração de açúcares e acidez. A partir dos resultados, pode-se concluir que: a) os sistemas NFT e com substrato de CAC são os que apresentam maior potencial para a cultura do morangueiro com solução nutritiva recirculante; b) as cultivares de dia neutro tem o seu crescimento reprodutivo e produtividade beneficiados, com prolongamento da colheita durante os meses de janeiro e fevereiro, em relação às cultivares de dia curto. Assim, as três cultivares de dia neutro avaliadas representam boas opções para o cultivo em CAC com solução recirculante e colheita na entressafra na região de Pelotas/RS. / Soilless cultivation systems are largely growing in Brazil and represent alternatives to solve lack of labour and pesticides use problems in strawberry crop. However, open soilless systems with drained nutrien solution leaching are most used. Thus, due to environmental and economical reasons, it is imperative to develop closed soilless systems, which promote drained nutrient solution collect and reuse. In this sense, two experiments were conducted in greenhouse conditions at the campus of the Federal University of Pelotas, RS, in order to study plant growth, fruit yield and quality of short-days and neutral-days strawberry cultivars grown in closed soilless cultivation systems. The first experiment was conducted in 2011/12 and aimed to study different closed soilless growing systems to be used for neutral-day cultivar Albion: a) NFT hydroponic system; b) NFT hydroponic system with gravel on the troughs; c) carbonized rice husk (CRH) substrate cultivation system; d) raw rice husk (RRH) substrate cultivation system. In the second experiment, conducted in 2012/13, short-day (Camarosa, Palomar and Ventana) and neutral-day varieties (Aromas, Monterey and Portola) grown in closed CRH system were evaluated. Leaves, crown and fruit dry matter production, fresh matter, number, average weight and soluble solids content and titratable acidity of fruits were evaluated in both experiments. Additionally, plant leaf area was also evaluated in the second experiment. The obtained results in the first experiment indicated that NFT and CRH cultivation systems promoted fruit growth and yield (respectively, 420 and 437 g plant-1). CRH system also increased vegetative growth, which promoted the average fruit weight (14.8 g). The evaluated cultivation systems affected plant growth and fruit yield, but did not alter the harvest distribution and the fruit quality in relation to the sugar content and acidity. The results from the second experiment indicated Portola, Aromas and Monterey day-neutral varieties presented similar fruit yields (respectively, 619.2, 610.2 and 547.1 g plant-1). Among the short-day varieties, Camarosa presented the highest fruit yield (408.7 g plant-1), followed by 'Ventana' (333.8 g plant-1) and 'Palomar’ (309.3 g plant-1). Regarding the quality of the fruit, among the day-neutral varieties, 'Portola' was distinguished by the highest average 11 fruit weight, 'Aromas' by the largest concentration of sugars and acidity and 'Monterey' by the more uniform fruit size; among short-day varieties, 'Ventana' was distinguished by the highest average fruit weight, concentration of sugars and acidity. From the results, we can conclude that: a) NFT and CRH substrate systems present higher potential for strawberry crop in recirculating solution soilless cultivation; b) the neutral-day varieties reproductive growth and fruit yield were benefited, with prolongation of the harvest period during the months of January and February in relation to short-day varieties. Thus, the three evaluated neutral-day varieties represent good options for growing in recirculating nutrient solution CRH system and offseason harvesting in Pelotas/RS.

Fraudulent behaviour within the art sector has been around since the Roman empire. The difficulty of proving provenance and authenticity has led to various art scandals around the world. The use of NFTs with their underlying blockchain technology has been described as a solution to these problems when applied to artworks. The recent public interest for NFT- applied to digital art and its perceived functionality is the motivation to investigate the usage of NFT digital art. Therefore, this study discusses the potential advantages and disadvantages of NFT-applied digital art. The results are based on (i) a literature analysis of previously identified advantages and disadvantages, (ii) the use of Practice Theory to investigate underlying motives to engage in the practice and (iii) an empirical review of nine respondents involved with NFTs applied to digital art. Potential advantages a majority of the respondents supported were the following: The advantage of royalty sharing, versatile utilization, provenance and exposure to larger markets. Potential disadvantages a majority of the respondents supported were the following: The disadvantage of the false belief of provenance, fraudulent behaviour, environmental aspects, legal aspects and that NFTs are currently not blockchain agnostic. The underlying motives the respondents expressed were financially driven and curiosity about the technology. The contribution of this paper will be useful for potential NFT-stakeholders to assess whether it is worth engaging in the area based on its current potential advantages and disadvantages. Furthermore, by highlighting the technology’s potential disadvantages, the paper also describes potential improvement factors which the NFT-community would benefit from resolving.

Background. Blockchain technologies are one of the most relevant examples of computer science today. Blockchain technologies have a lot of both existing and theoretical applications. Given the speed of development of this sub-industry, the standards by which it will operate are far from ideal and there are regrettably few peer-reviewed scientific articles on this topic. Therefore, there will be links to current security standards in the industry and to the results of various events to identify and test vulnerabilities in these algorithms, as well as links to real cases and articles on the theory of algorithmization. This work will explore and test several technologies and standards in terms of information security concepts and risk assessment, as well as the use of blockchain, including smart contract technology using the example of Non-Fungible Tokens (NFT) and decentralized finance, in the application, and the risks associated with it. This paper explores the question of how secure is the current level of NFT technologies and decentralized finance, in particular what problems of Accessibility and Integrity do exist in Blockchain Projects? It is proposed to answer this question by studying cases of recent years, as well as checking the performance of some exploits, some of which have been around for a couple of years and are still an urgent problem. In this work, a blockchain application is a part of a blockchain project that is the implementation of blockchain technology in practice, together with the architecture, depending on the purpose of the project, such a combination is called a blockchain project.Objectives. The purpose of this work is to study the security of the practical implementation of blockchain projects, using the example of decentralized finance, smart contracts in the Ethereum blockchain, since they are the most common. Particular attention is paid to the centralized approach to the use of blockchain technology in practice on the example of the Ethereum blockchain anddecentralized finance.Methods. Methods include multivocal literature review, Proof of Concept evidence-based approach using several vulnerabilities as an example, as well as a review of current case studies of blockchain projects in the period from 2020 to 2022.Results. The result of this work is the answer to research questions, namely the found correlation of the use of a centralized approach to the implementation of blockchain projects in practice and the vulnerabilities found associated with this approach. Based on the results of the work done, it was concluded that the current level of security of blockchain technologies working with smart contracts is unsatisfactory given the number of unresolved problems regarding the current capitalization of the industry / <p>Defence was held online</p>

Developments are reported of unstructured-mesh methods for simulating stratified, turbulent and shear flows. The numerical model employs nonoscillatory forward in-time integrators for anelastic and incompressible flow PDEs, built on Multidimensional Positive Definite Advection Transport Algorithm (MPDATA) and a preconditioned conjugate residual elliptic solver. Finite-volume spatial discretisation adopts an edge-based data structure. Tetrahedral-based and hybrid-based median-dual options for unstructured meshes are developed, enabling flexible spatial resolution. Viscous laminar and detached eddy simulation (DES) flow solvers are developed based on the edge-based NFT MPDATA scheme. The built-in implicit large eddy simulation (ILES) capability of the NFT scheme is also employed and extended to fully unstructured tetrahedral and hybrid meshes. Challenging atmospheric and engineering problems are solved numerically to validate the model and to demonstrate its applications. The numerical problems include simulations of stratified, turbulent and shear flows past obstacles involving complex gravity-wave phenomena in the lee, critical-level laminar-turbulence transitioning and various vortex structures in the wake. Qualitative flow patterns and quantitative data analysis are both presented in the current study.

Made available in DSpace on 2014-08-20T14:33:12Z (GMT). No. of bitstreams: 1 Dissertacao_Leandro_Andrade_da_Fonseca.pdf: 858649 bytes, checksum: 8a0d708c9f5d017489319548e3afe4c0 (MD5) Previous issue date: 2010-12-06 / Lettuce presents a great ability of nitrate accumulation, especially in hydroponics in which the ion availability is high. Nonetheless, nitrate accumulation depends primarily on genotype and light intensity. The objective of this work was to evaluate daily and seasonal variation of nitrate contents, growth and yield of lettuce cultivars according to the crop season in NFT system. Three experiments were conducted in three crop-seasons: spring of 2008, autumn and winter of 2009, in Pelotas RS. Four cultivars (Green Garden, Red Garden, Great Lakes Iceberg and Vera Sunny lettuce types) and four harvest times (8:00 am, 2:00 pm, 6:00 pm and 11:00 pm) were studied. In spring-summer, the lowest average nitrate contents were found at 6:00 pm and 11:00 pm (2058 and 2244 mg kg-1) and in Great Lakes Iceberg leaves (1825 mg kg-1). However, in this crop season, this cultivar did not present an appropriate head formation. Red Garden cultivar showed lower total plant fresh mass and yield than the other cultivars (236.7 against 389.4 g plant-1 obtained as the average of the remained cultivars, and 2724.2 against 4480.9 g m-2 as average from the other cultivars, respectively). In autumn, the lowest average nitrate contents were observed at 8:00 am (1378 against 1620 mg kg-1 obtained as average of the other harvest times) and for Red Garden and Great Lakes Iceberg cultivars (1360 and 1448 mg kg-1). Great Lakes Iceberg presented leaf dry mass, total plant dry and fresh mass higher than all other cultivars, and leaf area greater than Green Garden and Vera Sunny cultivars. In winter, Green Garden and Red Garden presented similar nitrate 10 contents (mean of 2182 mg kg-1) and for both cultivars the lowest nitrate contents was observed at 8:00 am (1545 against the average of 2394 mg kg-1 of the other harvest times). Great Lakes Iceberg presented lower nitrate accumulation than Vera Sunny (1915 and 2679 mg kg-1, respectively) and the harvest at 2:00 pm lead to a lower content than at 6:00 pm (2054 and 2454 mg kg-1, respectively). Great Lakes Iceberg presented higher total fresh mass production and yield (472.0 g planta-1 and 5590.1 g m-2, respectively) than the other cultivars, and it did not differ of Green Garden (390.2 g planta-1 and 4580.6 g m-2, respectively). In general, we can conclude that the lowest average nitrate accumulation is obtained in autumn (1559 against 2526 and 2189 mg kg-1 obtained in spring and winter, respectively). Vera Sunny cultivar in average presents the highest nitrate accumulation independently on the crop-season and Great Lakes Iceberg is the lowest nitrate accumulation cultivar. Late afternoon is the most recommended period for harvest in early summer day and the period of early-morning is the most indicated for lettuce harvest in autumn. On the other hand, in winter cloudy days, the period from morning to early afternoon is the most indicated for lettuce harvest. In spring, we can recommend Vera Sunny cultivar due its adequate growth, yield and absence of bolting tendency although its higher nitrate contends and considering that they are found in the acceptable consumption range. In autumn as well as in winter Great Lakes Iceberg represents an interesting alternative, due to its highest growth and the best yield responses in association to its leaves lowest values of nitrate. In winter, Green Garden cultivar can ocupy part of the NFT system, due to its also low nitrate contents and proper growth and yield. / A alface apresenta grande capacidade de acumular nitrato, especialmente em sistemas hidropônicos, nos quais a disponibilidade do íon é elevada. No entanto, o acúmulo de nitrato depende principalmente do genótipo e da intensidade luminosa. O objetivo deste trabalho foi avaliar a flutuação diária do acúmulo de nitrato, o crescimento e a produtividade de cultivares de alface de acordo com a estação de cultivo, em sistema NFT. Foram realizados três experimentos em três estações de cultivo: primavera-verão de 2008, outono e inverno de 2009, em Pelotas, RS. Quatro cultivares (Mimosa Verde, Mimosa Roxa, Americana Great Lakes e Crespa Vera) e quatro horários de colheita (8:00h, 14:00h, 18:00h e 23:00h) foram estudados. Na primavera, os menores acúmulos médios de nitrato foram observados às 18 e às 23 horas (2058 e 2244 mg kg-1) e nas folhas da cultivar Americana Great Lakes (1825 mg kg-1). Porém, nesta estação esta cultivar não apresentou boa formação de cabeça. A cultivar Mimosa Roxa apresentou massa fresca total de planta e produtividade inferiores às demais (respectivamente, 236,7 contra 389,4 g planta-1, média das demais cultivares, e 2724,2 contra 4480,9 g m-2, média das demais cultivares). No outono, os menores acúmulos médios de nitrato foram observados às 8 horas (1378 contra 1620 mg kg-1, média dos demais horários de colheita) e nas cultivares Mimosa Roxa e Americana Great Lakes (1360 e 1448 mg kg-1, respectivamente). A cultivar Americana Great Lakes apresentou produção de massa seca de folhas, massa seca e fresca totais e produtividade superiores às demais 8 (11,05, 13,91, 424,4 g planta-1 e 5314,1 g m-2, respectivamente), e área foliar superior a das cultivares Mimosa Verde e Crespa Vera. No inverno, as cultivares Mimosa Verde e Mimosa Roxa apresentaram acúmulos de nitrato semelhantes (média de 2182 mg kg-1) e para ambas as cultivares o menor acúmulo foi observado às 8 horas (1545 contra a média de 2394 mg kg-1 dos demais horários de colheita). A cultivar Americana Great Lakes apresentou menor acúmulo médio de nitrato que a cultivar Crespa Vera (1915 e 2679 kg mg-1, respectivamente) e a colheita das 14 horas apresentou menor acúmulo do que a das 18 horas (2054 e 2454 mg kg-1, respectivamente para estas duas cultivares). A cultivar Americana Great Lakes apresentou produção de massa fresca total e produtividade superiores às demais (472,0 g planta-1 e 5590,1 g m-1-2, respectivamente) sem diferir da cultivar Mimosa Verde (390,2 g planta-1 e 4580,6 g m-2, respectivamente). De maneira geral, pode-se concluir que o menor acúmulo médio de nitrato é obtido no outono (1559 mg kg-1 contra 2526 e 2189 mg kg-1 obtidos na primavera e no inverno, respectivamente). A cultivar Crespa Vera apresenta os maiores acúmulos médios de nitrato independentemente da estação de cultivo, e a cultivar Americana Great Lakes é a menos acumuladora. O período do final da tarde é o mais indicado para colheita em dia de início de verão e o período do início da manhã o mais indicado para colheita em dia de outono. Para colheita no inverno, em dias nebulosos, o período entre a manhã e o início da tarde é o mais indicado. Na primavera, pode-se recomendar a cultivar Crespa Vera por apresentar adequado crescimento e produtividade e ausência de tendência ao pendoamento e, mesmo apresentando os maiores valores de nitrato em suas folhas, esse se encontra dentro de parâmetros permissíveis para o consumo. Tanto no outono como no inverno, a cultivar Americana Great Lakes apresenta-se como uma alternativa interessante, devido ao seu maior crescimento e as melhores respostas relacionadas à produtividade, associados aos menores valores de nitrato em suas folhas. Ainda no inverno, a cultivar Mimosa Verde pode ser indicada para ocupar parte do sistema produtivo hidropônico, uma vez que também apresenta baixos valores de nitrato, crescimento e produtividades adequados.

Peer-to-peer (P2P) reputation systems, such as those used by eBay and Amazon, servean important role on the web, especially in E-commerce, as online reputation serves asa primary guiding factor for consumers in making informed decisions. The importanceof these systems, and also the increasing popularity of P2P and distributed systems, theissue of how to prevent and resist sybil and re-entry attacks becomes an important area ofresearch as they can impinge the integrity of those systems. To address this issue, in thisthesis, we propose an approach that encompasses a software architecture and processeswhich serves as a proof-of-concept of how to mitigate sybil and re-entry attacks on review based P2P distributed reputation systems. The architecture uses novel technologiessuch as blockchain, smart contracts, and non-fungible tokens (NFT) in conjunction withSwedish E-id provider BankID to build a sybil and re-entry attack resistant reputationsystem. To validate the feasibility of our approach, we developed a prototype and used itto run experiments to evaluate the functional correctness of the architecture as a mitigation solution