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Impact of energy storage technologies in a distribution grid : An analysis of Key Performance Indicators relating to a local grid’s performance characteristicsDaun, Kevin January 2021 (has links)
The energy system is undergoing a transformation on a never before witnessed scale. The changes are driven by global market forces and technological advancements, improving on a seemingly exponential scale. This in turn has led to the price of both renewables and the accompanying technology decrease over time, making the transition into renewables more economically viable. The drawback of variable renewable energy is that it is variable and dependent on the surrounding environment. Therefore, storing the energy during hours of production, to be used at a later stage when energy demand is higher is becoming ever more important and an attractive option. The purpose of this degree project is to, from a set of performance indicators, evaluate three different energy storage technologies and their respective impact on a distribution grid. The examined storage technologies are: Batteries, Capacitators and a H2 Fuel cell. A literature study was performed in order to find out how grid performance is evaluated, and how the different storage technologies operate. The obtained literature comes from scientific reports, and papers, found by utilizing Mälardalens University library-database. A model representing a Swedish grid with a connection point to the distribution side was created. The model is taken from previous credited work, and customized to fit the operational parameters of a Swedish grid. It was decided that the key indicators for evaluating the state of a grid was to look at the: voltage- and frequency variations, load factor, capacity factor and the overall system efficiency. The simulation is a discrete time simulation that utilizes parameters indicative of one full day of data. The results showed that, from a technological standpoint, the supercapacitor performed better in more categories than the Li-ion battery and H2 fuel cell. However, the Li-ion battery reduced the peaks of the frequency measurements which is a key metric when deciding on grid health. Also, there is the added benefit of the battery and fuel cell of having a longer operational time before the state of charge is depleted. This increases the flexibility of the technology and could therefore be more beneficial in other applications where power supply is more scarce.
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Formulação H2/Hoo do controle LQR robusto aplicado a domínios convexos e fechados /Caun, Rodrigo da Ponte. January 2019 (has links)
Orientador: Edvaldo Assunção / Resumo: A principal contribuição dessa tese é propor a representação H2/Hoo do regulador linear quadrático (LQR) para sistemas lineares invariantes no tempo e incertos. A motivação está em atender simultaneamente a minimização da função custo garantido e dos efeitos de entradas exógenas. De início, apresenta-se uma revisão da formulação do problema LQR usando-se a função de Lyapunov quadrática e, posteriormente, sua extensão aos modelos de incertezas. Neste ponto, a literatura volta-se exclusivamente ao uso de funções de Lyapunov com uma única matriz P para testar a estabilidade de todo o domínio de incerteza politópica, que naturalmente conduz a algum conservadorismo. Em vista de reduzir o pressuposto conservadorismo explorou-se técnicas de relaxação matricial através de lemas consolidados na literatura, i.e. Lema de Finsler e Lema da Projeção Recíproca. As novas formulações de síntese robusta permitem obter condições suficientes em desigualdades matriciais lineares (LMIs) por meio de funções de Lyapunov dependentes de parâmetros, embora não considere os efeitos da perturbação no processo de síntese de controle. Logo, o estudo da rejeição à perturbações permitiu obter condições LMIs inéditas envolvendo as normas H2/Hoo . Adicionalmente, é proposto o estudo da robustez da planta em malha fechada, via descrição combinada de incertezas nas matrizes de estados e de entradas, e do controlador, aplicando técnicas de fragilidade via incertezas limitadas por norma. Por fim, propõe-se um mét... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The main contribution of this thesis is to propose the H2/Hoo representation of the Linear Quadratic Regulator (LQR) for linear time-invariant uncertain systems. The motivation is to achieve the minimization of guaranteed cost and the effects of exogenous inputs, simultaneously. Initially, a review of the LQR problem formulation using the quadratic Lyapunov function is presented and after, its extension to the uncertain models. At this point, the literature turns to the use of Lyapunov functions with only one matrix P to test the stability of the whole polytopic domain, which naturally leads to some conservatism. The proposed to reduce the assumption conservatism allowed to explore techniques of matrix relaxation through classic lemmas in the literature, i.e. Finsler and Reciprocal Projection lemmas. The new robust synthesis formulations allow to obtain sufficient conditions in Linear Matrix Inequalities (LMIs) control by means of parameter-dependent Lyapunov functions; however, do not consider the perturbation effects on the control synthesis process. Thus, the study of disturbance rejection allowed to obtain new sufficient conditions via mixed H2/Hoo control. Furthermore, robustness studies of the closed-loop plant are proposed based on a mixed representation of uncertainties in the state and input matrices, and the controller robustness, by applying non-fragile theories via norm-bounded uncertainty. Finally, an LQR gain scheduling control method applied to linear time-vary... (Complete abstract click electronic access below) / Doutor
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Diseño de materiales carbonosos porosos de alta durabilidad y bajo coste para el almacenamiento y producción de energíaChaparro-Garnica, Jessica 17 December 2021 (has links)
Esta Tesis Doctoral se centra en una metodología innovadora para la síntesis de productos de alto valor añadido (carbón activado) usando como material de partida residuos de biomasa, los cuales son tratados mediante una carbonización hidrotermal asistida con ácido fosfórico (H3PO4) antes del proceso de activación. Con esta metodología se logra disminuir la concentración de agente activante y aumentar el rendimiento del carbón activado. Una vez sintetizados los carbones activados, estos fueron modificados mediante la introducción de grupos funcionales nitrogenados. En primer lugar, los carbones activados fueron usados como electrodos de supercondensadores tanto en electrolito acuoso como en electrolito orgánico, evaluando la influencia de la introducción de nitrógeno en el comportamiento electroquímico de los carbones activados. Posteriormente, se prepararon catalizadores basados en paladio (Pd) usando como soporte los carbones activados sintetizados tanto modificados con nitrógeno como sin modificar y se evaluó el comportamiento catalítico de estos catalizadores en la reacción de deshidrogenación de ácido fórmico para la producción de hidrógeno. Finalmente para demostrar que la metodología implementada para la obtención de carbones activados a partir de residuos de biomasa puede ser considerada como una alternativa sostenible para la obtención de productos de alto valor añadido, se planteó el aprovechamiento no solo de la fase sólida sino también de la fase líquida obtenida de la carbonización hidrotermal para la producción de ácido levulínico. Para esto, se empleó la metodología del análisis del ciclo de vida (LCA, del inglés Life Cycle Assessment) como herramienta para evaluar los impactos ambientales generados en cada etapa del proceso. En general, se logró demostrar las oportunidades que ofrece el aprovechamiento de los residuos de biomasa empleando protocolos de síntesis sencillos y más respetuosos con el medio ambiente para la obtención de productos de alto valor añadido.
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Infrared Spectroscopy of H<sub>2</sub> Trapped in Metal Organic FrameworksHopkins, Jesse Bennett January 2009 (has links)
No description available.
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CALCIUM LOOPING PROCESSES FOR CARBON CAPTURERamkumar, Shwetha 30 August 2010 (has links)
No description available.
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On Integral Quadratic Constraint Theory and Robust Control of Unmanned Aircraft SystemsFry, Jedediah Micah 11 September 2019 (has links)
This dissertation advances tools for the certification of unmanned aircraft system (UAS) flight controllers. We develop two thrusts to this goal: (1) the validation and improvement of an uncertain UAS framework based on integral quadratic constraint (IQC) theory and (2) the development of novel IQC theorems which allow the analysis of uncertain systems having time-varying characteristics.
Pertaining to the first thrust, this work improves and implements an IQC-based robustness analysis framework for UAS. The approach models the UAS using a linear fractional transformation on uncertainties and conducts robustness analysis on the uncertain system via IQC theory. By expressing the set of desired UAS flight paths with an uncertainty, the framework enables analysis of the uncertain UAS flying about any level path whose radius of curvature is bounded. To demonstrate the versatility of this technique, we use IQC analysis to tune trajectory-tracking and path-following controllers designed via H2 or H-infinity synthesis methods. IQC analysis is also used to tune path-following PID controllers. By employing a non-deterministic simulation environment and conducting numerous flight tests, we demonstrate the capability of the framework in predicting loss of control, comparing the robustness of different controllers, and tuning controllers. Finally, this work demonstrates that signal IQCs have an important role in obtaining IQC analysis results which are less conservative and more consistent with observations from flight test data.
With regards to the second thrust, we prove a novel theorem which enables robustness analysis of uncertain systems where the nominal plant and the IQC multiplier are linear time-varying systems and the nominal plant may have a non-zero initial condition. When the nominal plant and the IQC multiplier are eventually periodic, robustness analysis can be accomplished by solving a finite-dimensional semidefinite program. Time-varying IQC multipliers are beneficial in analysis because they provide the possibility of reducing conservatism and are capable of expressing uncertainties that have unique time-domain characteristics. A number of time-varying IQC multipliers are introduced to better describe such uncertainties. The utility of this theorem is demonstrated with various examples, including one which produces bounds on the UAS position after an aggressive Split-S maneuver. / Doctor of Philosophy / This work develops tools to aid in the certification of unmanned aircraft system (UAS) flight controllers. The forthcoming results are founded on robust control theory, which allows the incorporation of a variety of uncertainties in the UAS mathematical model and provides tools to determine how robust the system is to these uncertainties. Such a foundation provides a complementary perspective to that obtained with simulations. Whereas simulation environments provide a probabilistic-type analysis and are oftentimes costly, the following results provide worst-case guarantees—for the allowable disturbances and uncertainties—and require far less computational resources. Here we take two approaches in our development of certification tools for UAS. First we validate and improve on an uncertain UAS framework that relies on integral quadratic constraint (IQC) theory to analyze the robustness of the UAS in the presence of uncertainties and disturbances. Our second approach develops novel IQC theorems that can aid in providing bounds on the UAS state during its flight trajectory. Though the applications in this dissertation are focused on UAS, the theory can be applied to a wide variety of physical and nonphysical problems wherein uncertainties in the mathematical model cannot be avoided.
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Production of Solar Fuels Employing Different Materials Via Photocatalytic or Photothermal PathwaysSzalad, Horatiu 19 June 2025 (has links)
Tesis por compendio / [ES] El consumo actual de combustibles fósiles supone la emisión de millones de megatones de CO2 cada año, lo que ha tenido consecuencias potencialmente catastróficas como el efecto invernadero, la acidificación de los océanos y la eutrofización de las aguas, entre otras. Por lo tanto, la utilización de CO2 para la producción de combustibles y productos químicos de valor ha atraído mucho interés a lo largo de los años, especialmente empleando luz solar. A lo largo de los años, se han probado una gran variedad de materiales para tecnologías fotocatalíticas, principalmente TiO2, CdS, LDH, MOF y nitruros de carbono, entre otros. A pesar de esto, todos estos materiales adolecen de importantes inconvenientes, como una insuficiente captación de luz, estabilidad o baja producción. Y, por lo tanto, su aplicación en posibles tecnologías industriales fotocatalíticas es muy limitada a nivel industrial. Además de los procesos fotocatalíticos, que se componen principalmente de portadores de carga fotogenerados que facilitan las reacciones redox, los procesos fototérmicos representan una alternativa atractiva para las futuras tecnologías solares. La amplia utilización del espectro solar, el rápido calentamiento por irradiación de luz a través de "nanocalentadores" y "electrones calientes" que interactúan con sustratos son algunas de las características que conducen a los altos rendimientos catalíticos que generalmente se observan en las reacciones fototérmicas.
En la presente tesis doctoral, se han empleado diferentes materiales, como clústeres de Fe incrustados en grafeno dopado con nitrógeno, hidroxiapatita dopada con Co y nanopartículas de Ru soportadas sobre titanato de estroncio, como catalizadores fototérmicos para la hidrogenación selectiva de CO2 a CO o metano, tanto en flujo discontinuo como continuo. Admás, se han investigado muchos factores que influyen en esta reacción, como la naturaleza de los grupos/nanopartículas metálicas incrustadas, las cantidades de dopantes y la influencia de la irradiación incidente, entre otros.
Además de la catálisis fototérmica, la actual tesis doctoral también aborda procesos fotocatalíticos como la ruptura del agua o la reducción del O2 a H2O2, empleando nuevos compuestos de nitruro de carbono. Ya sea sensibilizando el fotocatalizador para la absorción de luz visible o mejorando las propiedades electrónicas mediante la formación de heterouniones, se lograron resultados fotocatalíticos notables. / [CA] El consum actual de combustibles fòssils suposa l'emissió de milions de megatons de CO2 cada any, cosa que ha tingut conseqüències potencialment catastròfiques com l'efecte hivernacle, l'acidificació dels oceans i l'eutrofització de les aigües, entre d'altres. Per tant, la utilització de CO2 per a la producció de combustibles i productes químics de valor ha atret molt interès al llarg dels anys, especialment emprant llum solar. Al llarg dels anys, s'han provat una gran varietat de materials per a tecnologies fotocatalítiques, principalment TiO2, CdS, LDH, MOF i nitrurs de carboni, entre d'altres. Tot i això, tots aquests materials pateixen importants inconvenients, com una insuficient captació de llum, estabilitat o baixa producció. I, per tant, la seva aplicació a possibles tecnologies industrials fotocatalítiques és molt limitada a nivell industrial. A més dels processos fotocatalítics, que es componen principalment de portadors de càrrega fotogenerats que faciliten les reaccions redox, els processos fototèrmics representen una alternativa atractiva per a les futures tecnologies solars. L'àmplia utilització de l'espectre solar, l'escalfament ràpid per irradiació de llum a través de "nanoescalfadors" i "electrons calents" que interactuen amb substrats són algunes de les característiques que condueixen als alts rendiments catalítics que generalment s'observen en les reaccions fototèrmiques.
En aquesta tesi doctoral, s'han emprat diferents materials, com clústers de Fe incrustats en grafè dopat amb nitrogen, hidroxiapatita dopada amb Co i nanopartícules de Ru suportades sobre titanat d'estronci, com a catalitzadors fototèrmics per a la hidrogenació selectiva de CO2 a CO o metà, tant en flux discontinu com continu. A més, s'han investigat molts factors que influeixen en aquesta reacció, com ara la naturalesa dels grups/nanopartícules metàl·liques incrustades, les quantitats de dopants i la influència de la irradiació incident, entre d'altres.
A més de la catàlisi fototèrmica, l'actual tesi doctoral també aborda processos fotocatalítics com ara la ruptura de l'aigua o la reducció de l'O2 a H2O2, emprant nous compostos de nitrur de carboni. Ja sigui sensibilitzant el fotocatalitzador per a l'absorció de llum visible o millorant les propietats electròniques mitjançant la formació d'heterounions, es van assolir resultats fotocatalítics notables. / [EN] Fossil fuel consumption accounts for millions of megatons of CO2 emitted every year, which has led to potentially catastrophic consequences such as the greenhouse effect, ocean acidification and water eutrophication, besides others. Thus, the utilization of CO2 for fuels and value chemicals has attracted much interest over the years, especially employing solar light. Over the years, a variety of promising materials have undergone trial for potential photocatalytic technologies, mainly TiO2, CdS, LDHs, MOFs and carbon nitrides among others, yet all these materials suffer from important drawbacks such as insufficient light harvesting, stability, or low production outputs, hence limiting their application in potential photocatalytic industrial technologies. Besides photocatalytic processes, mainly comprising of photogenerated charge carriers that facilitate redox reactions, photothermal processes represent an attractive alternative for future solar technologies. Broad utilization of the solar spectrum, strong heating upon light irradiation through "nano-heaters" and possibly "hot electrons" interacting with either semiconductors or substrate molecules are some characteristics that lead to the high catalytic outputs generally observed in photothermal reactions.
In the current doctoral thesis, different materials such as Fe clusters imbedded on nitrogen doped graphene, Co doped hydroxyapatite and Ru nanoparticles supported on strontium titanate have been employed as photothermal catalysts for the photothermal hydrogenation of CO2 to either CO or methane, under both batch and flow conditions. Thus, many factors influencing this reaction have been investigated, such as the nature of embedded metallic clusters/nanoparticles, dopant amounts and the power of incident irradiation among others.
Besides photothermal catalysis, the current doctoral thesis also addresses photocatalytic processes such as water splitting or O2 reduction to H2O2, employing novel carbon nitride composites. By either sensitizing the photocatalyst for visible light absorption or enhancing the electronic properties through heterojunction formation, remarkable photocatalytic outputs were achieved. / Szalad, H. (2024). Production of Solar Fuels Employing Different Materials Via Photocatalytic or Photothermal Pathways [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/206848 / Compendio
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Estudo fitoquímico e biológico do cambucá Plinia edulis (Vell.) Sobral - Myrtaceae / Phytochemical and Biological Studies of cambucá - Plinia edulis (Vell.) Sobral MyrtaceaeIshikawa, Tati 10 November 2008 (has links)
Plinia edulis (Myrtaceae), espécie arbórea popularmente conhecida como cambucá, é nativa da Mata Atlântica brasileira. Apesar do emprego na medicina tradicional em diversas moléstias, incluindo distúrbios gástricos, não existem estudos relacionando as atividades biológicas e os constituintes químicos da espécie. Esta tese relata a avaliação da gastroproteção, da atividade antioxidante, da citotoxicidade e da mutagenicidade do extrato etanol/água de folhas de P. edulis e das frações. Com o objetivo de correlacionar os metabólitos secundários com a eficácia da droga vegetal na medicina tradicional, o extrato foi submetido à partição e posterior fracionamento cromatográfico. O extrato apresentou atividade gastroprotetora significativa em modelo de indução de úlceras por etanol acidificado em ratos em doses de 100, 200 e 400 mg/kg via oral, sendo mais ativo que o fármaco de referência lansoprazol. Entre as frações, a hexânica (100 mg/kg p.o.) foi a mais eficaz, mas apresentou menor atividade do que o extrato bruto. A gastroproteção do ácido ursólico também foi avaliada, mas embora outros triterpenos sejam conhecidos como gastroprotetores, o ácido ursólico (50 mg/kg p.o.) reduziu a área lesionada, mas não apresentou atividade significativa no modelo empregado. O extrato não evidenciou mutagenicidade na concentração de 20 mg/placa no Ensaio de Ames e apresentou atividade antioxidante pronunciada, com CE50 de 5,75 µg/mL no ensaio com DPPH e valor de ORAC de 3.948 µmol de Trolox/g de extrato. O extrato e as frações foram avaliados quanto à citotoxicidade em linhagens de células tumorais humanas de UACC62 (melanoma), MCF-7 (mama), NCI 460 (pulmão), OVCAR03 (ovário), PC-03 (próstata), HT-29 (cólon), 786-0 (rins), NCI-ADR (mama com fenótipo de resistência a múltiplos fármacos) e linhagem de células normais de ovário de hamster chinês (CHO) in vitro. O extrato e as frações apresentaram citotoxicidade seletiva dose-dependente em células cancerígenas e atividade proliferativa em células normais. A partir das frações de hexano e acetato de etila foram identificados β-amirina, lupeol, β-sitosterol, ácido oleanólico, ácido ursólico, ácido maslínico, ácido corosólico, galato de etila, ácido gálico, quercitrina, miricitrina e quercetina por meio de análises espectrométricas. Estes resultados dão suporte à utilização popular desta espécie e estão provavelmente associados à presença dos flavonóides e triterpenos identificados no extrato. / Plinia edulis (Myrtaceae), an arboreous species popularly known as cambucá, is native in Brazilian Atlantic Rain Forest. Despite its traditional uses in many diseases, which include gastric disorders, no reports are available on the relationship between the biological activities of its extract and its chemical constituents. This thesis reports the evaluations of the the aqueous ethanol extract of leaves of P. edulis and its fractions on gastroprotective effect, antioxidant capacity, cytotoxicity and mutagenicity of. In order to correlate the secondary metabolites and the efficacy of the crude drug in traditional medicine, the extract was submitted to solvent partition followed by chromatographic fractionation. The extract exhibited significant gastroprotective effect on HCl/ethanol-induced ulcers in rats at doses of 100, 200 and 400 mg/kg p.o., even more active than the reference drug lansoprazole. Among the fractions, the hexane fraction (100 mg/kg p.o.) was the most effective, but showed lower activity than the crude extract. In addition, the gastroprotective effect of ursolic acid was evaluated. Although others triterpenes are well known as gastroprotective agents, ursolic acid (50 mg/kg p.o.) reduced the lesion area, but did not show significant activity on this model. The extract did not show mutagenicity at the concentration of 20 mg/plate in the Ames test and exhibited high antioxidant activity, with EC50 of 5.75 µg/mL on the DPPH assay and ORAC value of 3948 µmol Trolox/g of extract. The extract and its fractions were evaluated for cytotoxic activity against human tumour cell lines as UACC62 (melanoma), MCF-7 (breast), NCI 460 (lung, non-small cells), OVCAR03 (ovarian), PC-03 (prostate), HT-29 (colon), 786-0 (renal), NCI-ADR (breast expressing phenotype multiple drugs resistance) and CHO (Chinese Hamster Ovary) normal cell line in vitro. The extract and its fractions showed selectively dose-dependent cytotoxicity against cancer cells and proliferative activity in normal cells. The hexane and ethyl acetate fractions yielded β-amyrin, lupeol, β-sitosterol, oleanolic acid, ursolic acid, maslinic acid, corosolic acid, ethyl gallate, gallic acid, quercitrin, myricitrin and quercetin, which were identified based on spectrometric analyses. These results provide scientific support to the traditional use of this species, which are probably associated with the flavonoids and triterpenoids identified in the extract.
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Atividades antiúlcera e antioxidante de Syzygium jambos (L.) Alston / Antiulcer and antioxidant activities of Syzygium jambos (L.) AlstonPasquale, Raquel Donatini De 20 October 2008 (has links)
O jambeiro (Syzygium jambos (L.) Alston) constitui uma das diversas espécies frutíferas e medicinais pertencentes à família Myrtaceae. O extrato hidroetanólico a 70% liofilizado de folhas de S. jambos apresentou atividade dose-dependente em modelo de úlcera gástrica induzida por etanol acidificado, sendo que a dose de 400 mg/kg reduziu significativamente a Área Total de Lesão (81,64%) e a Área Relativa de Lesão (65,11 %), em comparação ao grupo controle. Nesta dose, o extrato apresentou-se mais eficaz que o fármaco empregado como referência (lansoprazol 30 mg/kg). No modelo de indução de úlcera gástrica por ácido acético, o extrato (400 mg/kg) não apresentou resultados significativos na cura das lesões. A atividade antioxidante do mesmo extrato e de quatro frações foi avaliada através da medida da capacidade seqüestrante de radicais 1,1-difenil-2-picrilidrazila. O extrato hidroetanólico a 70% liofilizado apresentou CE50 de 5,36 ± 0,06 µg/mL, valor comparável ao do Trolox (CE50 =4,98 ± 0,04 µg/mL) , substância antioxidante de referência. As frações clorofórmica, acetato de etila, etanólica e hidroetanólica a 50% apresentaram CEso de, respectivamente, 64,06 ± 0,68 µg/mL, 19,02 ± 0,22 µg/mL, 6,89 ± 0,12 µg/mL e 8,47 ± 0,05 µg/mL. Da fração clorofórmica do extrato foi isolado o triterpeno ácido ursólico. Na avaliação da toxicidade subcrônica através da administração oral a ratos Wistar, durante 30 dias, de três diferentes doses do extrato (400, 1000 e 2500 mg/kg), não foram observados sinais clínicos de toxicidade. As análises macroscópica e microscópica dos órgãos não mostraram alterações dignas de nota para nenhuma das doses empregadas. Não houve diferenças estatisticamente significativas nos resultados das análises bioquímicas do sangue dos animais. Os resultados revelam o potencial do extrato no tratamento de úlceras gástricas, sendo necessários estudos mais aprofundados do mecanismo de ação desta atividade, bem como de toxicidade crônica. / Syzygium jambos (L.) Alston is one of the species of Myrtaceae with medicinal properties. The dried 70% hydroethanolic extract of the leaves showed a doseresponse effect in ethanol/HCI-induced ulcers, significantly decreasing the total lesion area (81,64%) and relative lesion area (65,11 %) compared to control group. At this dose the extract was more effective than lansoprazol (30 mg/kg), used as reference drug. The same extract at 400 mg/kg was not effective on healing acetic acid-induced ulcers. Antioxidant activity of S. jambos extract and four fractions was measured using 1,1-diphenyl-2-picryl-hydrazyl radical scavenging ability. The EC50 value for the extract was 5,36 ± 0,06 µg/mL, while Trolox, antioxidant substance of reference, showed EC50 of 4,98 ± 0,04 µg/mL. The tested fractions (chloroform, ethyl acetate, ethanol and 50% ethanol) showed EC50 of 64,06 ± 0,68 µg/mL, 19,02 ± 0,22 µg/mL, 6,89 ± 0,12 µg/mL e 8,47 ± 0,05 µg/mL, respectively. Ursolic acid was identified in the chloroformic fraction of the extract. Subchronic toxicity studies were performed by oral administration of the leaf extract to rats, during 30 days, at three different doses (400, 1000 and 2500 mg/kg). The extract did not show any clinicai sign of toxicity. Macroscopic and microscopic analysis of the organs demonstrated no alterations for the three doses tested. There were no statistically differences between results of biochemical analysis of blood. These results show the potential of the extract in treatment of gastric ulcer, although more studies of mechanism of action and chronic toxicity are necessary.
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Entwurf einer fehlerüberwachten Modellreduktion basierend auf Krylov-Unterraumverfahren und Anwendung auf ein strukturmechanisches Modell / Implementation of an error-controlled model reduction based on Krylov-subspace methods and application to a mechanical modelBernstein, David 17 October 2014 (has links) (PDF)
Die FEM-MKS-Kopplung erfordert Modellordnungsreduktions-Verfahren, die mit kleiner reduzierter Systemdimension das Übertragungsverhalten mechanischer Strukturen abbilden. Rationale Krylov-Unterraum-Verfahren, basierend auf dem Arnoldi-Algorithmen, ermöglichen solche Abbildungen in frei wählbaren, breiten Frequenzbereichen. Ziel ist der Entwurf einer fehlerüberwachten Modelreduktion auf Basis von Krylov-Unterraumverfahren und Anwendung auf ein strukturmechanisches Model.
Auf Grundlage der Software MORPACK wird eine Arnoldi-Funktion erster Ordnung um interpolativen Startvektor, Eliminierung der Starrkörperbewegung und Reorthogonalisierung erweitert. Diese Operationen beinhaltend, wird ein rationales, interpolatives SOAR-Verfahren entwickelt. Ein rationales Block-SOAR-Verfahren erweist sich im Vergleich als unterlegen. Es wird interpolative Gleichwichtung verwendet. Das Arnoldi-Verfahren zeichnet kleiner Berechnungsaufwand aus. Das rationale, interpolative SOAR liefert kleinere reduzierte Systemdimensionen für gleichen abgebildeten Frequenzbereich. Die Funktionen werden auf Rahmen-, Getriebegehäuse- und Treibsatzwellen-Modelle angewendet.
Zur Fehlerbewertung wird eigenfrequenzbasiert ein H2-Integrationsbereich festgelegt und der übertragungsfunktionsbasierte, relative H2-Fehler berechnet.
Es werden zur Lösung linearer Gleichungssysteme mit Matlab entsprechende Löser-Funktionen, auf Permutation und Faktorisierung basierend, implementiert. / FEM-MKS-coupling requires model order reduction methods to simulate the frequency response of mechanical structures using a smaller reduced representation of the original system. Most of the rational Krylov-subspace methods are based on Arnoldi-algorithms. They allow to represent the frequency response in freely selectable, wide frequency ranges. Subject of this thesis is the implementation of an error-controlled model order reduction based on Krylov-subspace methods and the application to a mechanical model. Based on the MORPACK software, a first-order-Arnoldi function is extended by an interpolative start vector, the elimination of rigid body motion and a reorthogonalization. Containing these functions, a rational, interpolative Second Order Arnoldi (SOAR) method is designed that works well compared to a rational Block-SOAR-method. Interpolative equal weighting is used. The first-order-Arnoldi method requires less computational effort compared to the rational, interpolative SOAR that is able to compute a smaller reduction size for same frequency range of interest. The methods are applied to the models of a frame, a gear case and a drive shaft. Error-control is realized by eigenfrequency-based H2-integration-limit and relative H2-error based on the frequency response function. For solving linear systems of equations in Matlab, solver functions based on permutation and factorization are implemented.
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