Desarrollo de electroimanes reconfigurables para uso en resonancia magnética nuclear y metrología magnética

Una técnica experimental de creciente interés en la comunidad internacional es la relaxometría magnética nuclear, la cual posee un amplio campo de aplicabilidad en la industria farmacéutica, alimentaria, petrofísica, caucho, cosmética y plástico, entre otras. Actualmente se desarrolla en el LaRTE (Laboratorio de Relaxometría y Técnicas Especiales) un prototipo alfa de un instrumento unico de resonancia magnética nuclear con campo magnético ciclado, que permitirá no solamente realizar estudios relaxométricos en muestras de hasta 35cm3, sino que posibilitará la obtención de imágenes y mediciones de difusión a diferentes valores de campo. El corazón de este aparato es un electroimán particular logrado con tecnología propia, el cual posee excelentes características al compararlo con el estado del arte. Este logro da sustento al desarrollo en marcha, el cual será posiblemente transferido a una empresa espín-off del laboratorio (Trovintek Advanced Magnetic Systems) en el futuro para un desarrollo beta. En esta dirección, este proyecto propone profundizar el desarrollo de los imanes logrados, tratando de alcanzar sistemas reconfigurables adaptivos según las características del campo requerido y según demande la aplicación (homogeneidad, velocidad de conmutación e intensidad). A su vez, estos mismos sistemas de imanes prometen excelente aplicabilidad en el campo de la metrología magnética, dirección en la cual el LaRTE ya ha comenzado a trabajar conjuntamente con la Unidad Técnica Electrónica del INTI (Córdoba). Dichos electroimanes pueden devenir, en si mismos, en dispositivos especialmente diseñados para tal aplicación.

Potencial da ressonância magnética multiparamétrica na deteção de carcinoma da próstata localizado e valor do coeficiente de difusão aparente como possível preditor da agressividade tumoral : revisão de uma técnica em expansão

Trabalho Final do Curso de Mestrado Integrado em Medicina, Faculdade de Medicina, Universidade de Lisboa, 2014

Polémica religioso-frenolójico-magnética sostenida ante el tribunal eclesiástico de Santiago en el expediente que ha seguido con motivo de la denuncia suscitada contra los libros y lecciones de frenolojía y magnetismo de D.Mariano Cubi y Soler, cuya causa ha terminado ultimamente por sobreseimiento dejando a salvo la persona y sentimiento del Sr. Cubí /

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Sistema de conversão de energia eólica baseado no gerador de indução duplamente alimentado: análise e contribuição ao controle da máquina

The humanity reached a time of unprecedented technological development. Science has achieved and continues to achieve technologies that allowed increasingly to understand the universe and the laws which govern it, and also try to coexist without destroying the planet we live on. One of the main challenges of the XXI century is to seek and increase new sources of clean energy, renewable and able to sustain our growth and lifestyle. It is the duty of every researcher engage and contribute in this race of energy. In this context, wind power presents itself as one of the great promises for the future of electricity generation . Despite being a bit older than other sources of renewable energy, wind power still presents a wide field for improvement. The development of new techniques for control of the generator along with the development of research laboratories specializing in wind generation are one of the key points to improve the performance, efficiency and reliability of the system. Appropriate control of back-to-back converter scheme allows wind turbines based on the doubly-fed induction generator to operate in the variable-speed mode, whose benefits include maximum power extraction, reactive power injection and mechanical stress reduction. The generator-side converter provides control of active and reactive power injected into the grid, whereas the grid-side converter provides control of the DC link voltage and bi-directional power flow. The conventional control structure uses PI controllers with feed-forward compensation of cross-coupling dq terms. This control technique is sensitive to model uncertainties and the compensation of dynamic dq terms results on a competing control strategy. Therefore, to overcome these problems, it is proposed in this thesis a robust internal model based state-feedback control structure in order to eliminate the cross-coupling terms and thereby improve the generator drive as well as its dynamic behavior during sudden changes in wind speed. It is compared the conventional control approach with the proposed control technique for DFIG wind turbine control under both steady and gust wind conditions. Moreover, it is also proposed in this thesis an wind turbine emulator, which was developed to recreate in laboratory a realistic condition and to submit the generator to several wind speed conditions.

Síntese e caracterização estrutural, magnética e térmica da hidroxiapatita dopada com ferro

In this work, composites were prepared using high energy mechanical milling from the precursors hydroxyapatite - HAp (Ca10(PO4)6(OH)2) and metallic iron ( -Fe ). The main goal here is to study composites in order to employ them in magnetic hyperthermia for cancer therapy. The produced samples were characterized by X-ray di raction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), magnetization curves as a function of applied eld (MxH), and nally measurements of magnetic hyperthermia. The XRD patterns of the milled samples HAp/Fe revealed only the presence of precursor materials. The SEM showed clusters with irregular shapes. The magnetization curves indicated typical cases of weak ferromagnetic behavior. For samples submitted to grinding and annealing, the identi ed phases were: HAp (Ca10(PO4)6(OH)2), hematite (Fe2O3) and Calcium Iron Phosphate (Ca9Fe(PO4)7). Analyzing the results of MxH, there was a reduction of the saturation magnetization, given that the Fe was incorporated into HAp. Hysteresis curves obtained at 300 K are characteristics of samples possessing over a phase. At 77 K, the behavior of the hysteresis curve is in uenced by the presence of hematite, which is antiferromagnetic. Already at T = 4.2 K, it is observed a weak ferromagnetic behavior. Furthermore, there is the e ect of exchange bias. Regarding the magnetic hyperthermia, the results of temperature measurements as a function of the alternating eld are promising for applications in magnetic hyperthermia and other biomedical applications.

Estudo de um sistema de frenagem eletromagnética empregando correntes parasitas

This work deals with the analytical, computational and experimental study of phenomena related to the Eddy current induction in low permeability means for embedded electromagnetic braking systems applications. The phenomena of forces generation in opposing to the variation of stationary magnetic flux produced by DC power supplies, set in motion by the application of an external propulsive force are addressed. The study is motivated by search for solving the problem of speed control of PIGs used to verifying and maintaining pipelines, and is led based on the analytical models synthesis, validated by means of computer simulations in Finite Elements environment, provided by engineering support software; and with experimental tests conducted under controlled laboratory conditions. Finally, a damping systems design methodology based on analyzes results conducted throughout the study is presented

Não-extensividade no contexto da atividade magnética solar: o problema da assimetria hemisférica

Solar activity indicators, each as sunspot numbers, sunspot area and flares, over the Sun’s photosphere are not considered to be symmetric between the northern and southern hemispheres of the Sun. This behavior is also known as the North-South Asymmetry of the different solar indices. Among the different conclusions obtained by several authors, we can point that the N-S asymmetry is a real and systematic phenomenon and is not due to random variability. In the present work, the probability distributions from the Marshall Space Flight Centre (MSFC) database are investigated using a statistical tool arises from well-known Non-Extensive Statistical Mechanics proposed by C. Tsallis in 1988. We present our results and discuss their physical implications with the help of theoretical model and observations. We obtained that there is a strong dependence between the nonextensive entropic parameter q and long-term solar variability presents in the sunspot area data. Among the most important results, we highlight that the asymmetry index q reveals the dominance of the North against the South. This behavior has been discussed and confirmed by several authors, but in no time they have given such behavior to a statistical model property. Thus, we conclude that this parameter can be considered as an effective measure for diagnosing long-term variations of solar dynamo. Finally, our dissertation opens a new approach for investigating time series in astrophysics from the perspective of non-extensivity.

Síntese e caracterizações estrutural e magnética das ferritas de cobalto-manganês (Co1-xMnxFe2O4 E Co1,2Fe1,8-xMnxO4)

The cobalt-manganese ferrites (Co1¡xMnxFe2O4 and Co1,2Fe1,8¡xMnxO4) has a mixed structure of spinel type and it has been regarded as one of candidates for petitive wide variety of applications in devices from ultrasonic generation and detection, sensors, transformers, as well as in medical industry. Ferrites cobalt-manganese nanostructured were produced via mechanical alloying with subsequent heat treatment and were characterized by X-ray diffraction, X-ray fluorescence, scanning electron microscopy and magnetization. Samples of Co1¡xMnxFe2O4 and Co1,2Fe1,8¡xMnxO4 were obtained from the precursor powders Fe3O4, Co3O4 and Mn3O4 which were stoichiometrically mixed and ground by 10h and heat treated at 900°C for 2h. The diffraction confirmed the formation of the pure nanocrystalline phases to series Co1,2Fe1,8¡xMnxO4 with an average diameter of about 94nm. It was found that the lattice parameter increases with the substitution of Fe3Å by Mn3Å. The x-ray fluorescence revealed that the portions of metals in samples were close to the nominal stoichiometric compositions. The microstructural features observed in micrographs showed that the particles formed show very different morphology and particle size. The magnetic hysteresis measurements performed at low temperature showed that the saturation magnetization and remanence increased as the concentration of manganese, while the coercive field decreased. The anisotropy constant (Ke f ), was estimated from the data adjustments the law of approaching saturation. It was found that the anisotropy decreases substantially with the substitution of Fe by Mn.

Anisotropia magnética em nanofilmes com assimetria cristalográfica

This Thesis comprises a theoretical study about the influence of the magnetocrystalline anisotropy on the static and dynamic magnetic properties of nanofilms: monolayers and trilayers coupled through the bilinear and biquadratic exchange fields, for situations in which the systems are grown in unusual [hkl] asymmetric directions. Using a theory based on a realistic phenomenological model for description of nanometric systems, we consider the total free magnetic energy including the Zeeman interaction, cubic and uniaxial anisotropies, demagnetizing and surface anysotropy energies, as well as the exchange terms. Numerical calculations are conducted by minimizing the total magnetic energy from the determination of equilibrium static configurations. We consider experimental parameters found in the literature to illustrate our results for Fe/Cr/Fe trilayer systems. In particular, a total of six different magnetic scenarios are analyzed for three regimens of exchange fields and the [211] and [321] asymmetric growth directions. After numerically minimize the total energy, we use the equilibrium configurations to calculate magnetization and magnetoresistance curves with the respective magnetic phases and corresponding critical fields. These results are also used to establish the boundary for occurrence of saturated states. Within the context of the spin waves, we solve the equation of motion for these systems in order to find the respective associated dispersion relations. The results show similar magnetization and magnetoresistance curves for both [211] and [321] growth scenarios, including an equivalent magnetic transition behavior. However, the combination of those peculiar symmetries and influence of the exchange energies results in attractive properties, including the generation of magnetic states as a function of the asymmetric degree imposed in the [hkl] growth orientations. There is also an increasing incompatibility between the values of saturation fields of magnetization and magnetoresistance for the cases in which a magnetic field acts along intermediate cubic anisotropic axes, particularly in the situations where the bilinear and biquadratic exchange fields are comparable. The dispersion relations and static results are consistent, the corresponding magnetic states are also present in both acoustic and optical modes. Furthermore, Goldstone excitations are also observed for that particular cases of a magnetic field acting in the intermediate axes, an effect related to transitions of second order and to the spontaneous symmetry breaking imposed by the combination of the biquadratic energy with the cubic and uniaxial anisotropies.

Análise da força propulsora do motor de indução linear alimentado com imposição de corrente

This work intent to study the motive power provided by the plane linear induction motor, in a lock condition. It uses a method of imposition of the electric current to the stator via a frequency convertor PWM driven by a refed platform. The reading of the motive power was performed by a load cell using an electronic circuit for reading and conditioning of the signal. Aiming a complete analysis of the linear motor, it was performed a computational modeling that employs all relevant parameters to the study of the locked machine. At the end it was held a theoric-experimental confrontation that evaluated the effectiveness of the proposed method.

Utilização de pulsos de radiofrequência fortemente modulados no processamento de informação quântica via ressonância magnética nuclear

Nesta dissertação apresentamos um trabalho de desenvolvimento e utilização de pulsos de radiofreqüência modulados simultaneamente em freqüência, amplitude e fase (pulsos fortemente modulados, SMP, do inglês Strongly Modulated Pulses) para criar estados iniciais e executar operações unitárias que servem como blocos básicos para processamento da informação quântica utilizando Ressonância Magnética Nuclear (RMN). As implementações experimentais foram realizas em um sistema de 3 q-bits constituído por spins nucleares de Césio 133 (spin nuclear 7/2) em uma amostra de cristal líquido em fase nemática. Os pulsos SMP´s foram construídos teoricamente utilizando um programa especialmente desenvolvido para esse fim, sendo o mesmo baseado no processo de otimização numérica Simplex Nelder-Mead. Através deste programa, os pulsos SMP foram otimizados de modo a executarem as operações lógicas desejadas com durações consideravelmente menores que aquelas realizadas usando o procedimento usual de RMN, ou seja, seqüências de pulsos e evoluções livres. Isso tem a vantagem de reduzir os efeitos de descoerência decorrentes da relaxação do sistema. Os conceitos teóricos envolvidos na criação dos SMPs são apresentados e as principais dificuldades (experimentais e teóricas) que podem surgir devido ao uso desses procedimentos são discutidas. Como exemplos de aplicação, foram produzidos os estados pseudo-puros usados como estados iniciais de operações lógicas em RMN, bem como operações lógicas que foram posteriormente aplicadas aos mesmos. Utilizando os SMP\'s também foi possível realizar experimentalmente os algoritmos quânticos de Grover e Deutsch-Jozsa para 3 q-bits. A fidelidade das implementações experimentais foi determinadas utilizando as matrizes densidade experimentais obtidas utilizando um método de tomografia da matriz densidade previamente desenvolvido.

Dispositivo de rotación de tubos de resonancia magnética nuclear

La invención un dispositivo especialmente diseñado para llevar a cabo la agitación de un tubo de resonancia magnética nuclear (RMN) que comprende: un soporte (2) al que está fijado un motor (3) eléctrico de eje horizontal; un adaptador (4) de tubos (100) de resonancia magnética nuclear fijado al eje del motor (3) eléctrico; un sensor Hall (5) dispuesto para detectar una posición inicial de dicho eje; un medio (6) de procesamiento conectado al motor (3) eléctrico y al sensor Hall (5); un módulo (7) de comunicaciones para llevar a cabo la programación del medio (6) de procesamiento; y una interfaz (8) de control y visualización conectada al medio (5) de procesamiento para operar el dispositivo (1) y visualizar datos acerca de su funcionamiento.

Quitosana na indução de resistência ao tombamento de plântulas de espécies olerícolas e no controle de fitopatógenos in vitro

Induction of resistance is defined as the activation of a state of resistance against diseases which is induced systemically in plants by the use of biotic or abiotic agents without any modification of the plant genome, occurring non-specific way, by activating genes coding for various plant defense responses. Chitosan is a polymer derived from the deacetylation of chitin, which is found in large quantities in crustacean shell, and studied with the potential to control plant pathogens, both by its direct fungistatic action, as the ability to induce protection of plants, indicating the presence of molecules of elicitoras characteristics. Three experiments with objective of evaluating the potential of chitosan in the seedling resistance induction were developed, beet (Beta vulgaris) seeds, cucumber (Cucumis sativus) seeds and tomato (Solanum lycopersicum) seeds, and the control of Fusarium sp., Rhizoctonia solani K¨uhn e Pythium sp. in vitro conditions. The experimental design was completely randomized, with four replications. Beet seeds, tomato and cucumber were submerged in chitosan solution for 20 minutes, in concentrations of 0.25, 0.5, 1 and 2% in the control and distilled water. Seeds were sown in trays containing Plantmax Florestalr substrate sterilized and inoculated with Fusarium sp., Rhizoctonia solani K¨unh and Pythium sp., respectively for the three cultures. The experiment was conducted for 14 days in growth chamber with controlled temperature (25 C 2 C), light (12 hour photoperiod) and humidity (70% 10%). The evaluations were seed emergency, seedling damping-off, seedling length, fresh weight and activity of the enzymes phenylalanine amˆonia-liase (PAL), chitinase and b-1,3-glucanase. It was also rated the mycelial growth of Fusarium sp., Pythium sp. and R. solani on P.D.A. (Potato-Dextrose and Agar) culture medium containing chitosan at the same concentrations evaluated in seeds. For beet growing, seed treatment with chitosan presented higher emergence and the length of the seedlings, and reduced the percentage of tipping. Treatment with chitosan activated the systemic acquired resistance with expression of chitinase and b-1,3-glucanase enzymes. For the tomato crop in chitosan concentration of 0.25% favored the emergency of seedlings, reduced the incidence of tipping and activated the PAL enzymes, chitinase and b-1,3-glucanase. In cucumber on the concentration of up 0.5% favored seedlings emergence and reduces the incidence of tipping. Chitosan activated the PAL enzymes and b-1,3-glucanase. Chitosan also presented fungistatic action on the initial growth of Pythium sp. and R. solani in vitro conditions, however, such action did not prevail until the end of the experiment. To Fusarium sp. the concentration of chitosan resulted in the reduction of mycelial growth in vitro.

Potencial do óleo de Aloysia citriodora Palau no controle de fitopatógenos e na indução de resistência ao tombamento de plântulas de feijão, pepino e beterraba

The crops are affected by pests and diseases that decrease productivity. Among them are the damping off of seedlings that can occur in pre and post-emergence. In bean crops, cucumber and beet these diseases occur, being caused by various pathogens, especialy fitopathogenic fungi. Several measures are used for the controle of such diseases, among them, is the chemical seed treatment fungicides. However, society has become increasingly concerned about the quality and food and environmental contamination, generation a growting search for sensitive products to humans and the environment. The use of essential oils to control plant pathogens is an example of alternative tested by science in the search for less aggressive technologies. This study aimed to evaluate the efficiency of the use of essential oil Aloysia citriodora, in control of pathogens causing damping off in beans, cucumber and beet. This thesis was divided in four chapters, the introductory first, and the other addressing the control of Pythium sp. in beans, Sclerotinia sclerotiorum on cucumber, and Fusarium sp. on beet. The methodology consisted of four experiments in each pathosystem, with all the work done at the Federal Technological University of Parana, Campus Dois Vizinhos. In the first experiment evaluated the fungistatic and fungicidal effect of the essential oil of A. citriodora on PDA in vitro in mycelial growth of pathogens studied. In the second experiment evaluated the in vitro effect of essential oil concentrations of A. citriodora in BD medium on microscope slides, on the germination of sporangia Pythium sp. and conidia Fusarium sp., and in Petri dishes with PDA medium, the sclerotia germination speed index of S. sclerotiorum. In the third experiment, we evaluated in germination test in paper roll (PR), the phytotoxic effect or not the use of essential oil concentrations of A. citriodora in dry bean seed, cucumber and beet. The variables used to assess this experiment were the germination percentage, mediun green mass per plant and average length of seedlings. In the fourth experiment we assessed the effect of treating bean seeds, cucumber and beet with essential oil contents of A. citriodora, seeds in their subsequent substrates contamined with pathogens studied, Pythium sp., S. sclerotiorum and Fusarium sp. In this experiment we used the following variables: percentage of emergence, percentage of post-emergence damping off, green average mass per plant, average length per plant and biochemical analyzes. The biochemistry of plant tissues evaluated were as follows: protein content, enzymatic activities of peroxidases, phenylalanine ammonia-liase (PAL), chitinases and β-1,3-glucanases. The in vitro results show that the essential oil has fungistatic and fungicidal effect on mycelial growth, on sporangia germination, conidia and sclerotia of the pathogens studied in this work, wich may be related to its major components, citral and limonene. The oil also exhibits low phytotoxicity to seeds of the species studied, only in beans decreases germination in most studied dosage (0,25%), cucumber also in the higher dosage (0,25%) reduce the length of seedlings, and beet there were no negative effects to the seedlings. In the test in substrate contaminated with the pathogens, the use of essential oil: increased germination and decreased post emergence damping off of beans seedlings; at a concentration of 0,0625% decreases post emergence damping off in cucumber. In biochemical analyzes found an increase in the enzymatic activity of peroxidases and β-1,3-glucanases on beans, and glucanases on cucumber, and increased enzyme activity of peroxidases on beet, showing action in resistance induction at damping off.

Indução de resistência e tratamento de sementes de soja com fosfitos de potássio

The use of inputs containing phosphites have been presenting results in many studies, taking on importance to the control of diseases in some cultures and demonstrating the resistance induction in seedlings, with ability to activate defense mechanisms, conferring protection to plants against microorganisms. The soybean crop is recognized for its importance in providing grains and derivatives for human consumption, animal, production of biofuels, pharmaceuticals, among others. Positive results obtained through studies based on resistance inducers in some cultures arouse the interest for further study. The objective of this study was to evaluate the effect of potassium phosphites on the resistance induction and treatment of soybean seeds. Therefore were conducted four laboratory studies at the Federal Technological University of Paraná, Campus of Dois Vizinhos. In the first study it was evaluated the quality attributes of the seeds and the resistance induction as seed treatment. Then it was verified that phosphites have action upon the seedlings metabolism in due to seed treatment, having the phosphite Reforce® contributed to seed quality attributes and phosphites FitofosK® and Fitofos K Plus® induced the resistance increasing the activity of β-1,3-glucanase. In the second study it was evaluated the the resistance induction in soybean cotyledons, in which the phosphites demonstrated induction potential of phytoalexin gliceolin. In the third study It was evaluated the soybean seed health treated with potassium phosphites.. it was observed that the phosphites reduced the incidence of many fungi on seeds, especially of storage fungi like Aspergillus sp. and Fusarium semitectum. In the fourth study it was evaluated the in vitro effect of potassium phosphites on pathogenic fungi of the culture. And it was found direct action of phosphites on the mycelial growth of Fusarium semitectum, Pythium sp. and Sclerotinia sclerotiorum. Based on these results, we concluded that potassium phosphites have potential in seeds treatment, as resistance inducer and on in vitro control of phytopathogens.