As bobinas ativamente blindadas (actively shielded) melhoram a performance das bobinas de gradiente ao cancelar o campo magnético na parte externa da bobina primária, evitando a degradação do campo no seu interior devido às correntes induzidas (eddy currents). O presente trabalho resultou na construção de um conjunto de bobinas de gradientes ativamente blindadas (Gx, Gy e Gz ), de geometria cilíndrica e acesso axial, com diâmetro de volume útil de 10cm para imagens (field of view), com campos de gradiente de aproximadamente 8.0 G/cm para r=0, com uma máxima distorção de campo de 5% neste volume, onde foi observado um efetivo cancelamento do campo externo, o que evita correntes induzidas nas partes metálicas internas do magneto OXFORD de 2.0 Tesla horizontal de 30cm de diâmetro, no qual serão empregadas. Alguns resultados prévios foram obtidos com um protótipo transversal, em apenas uma direção, e também com um conjunto de bobinas de gradiente para utilização em obtenção de imagens microscópicas de ESR pulsado. As bobinas foram projetadas utilizando-se a técnica de densidade de corrente, que se baseia na abordagem de campo alvo (target field) e também foi empregado o método de \"simulated annealing\" para otimização do desenho. Este sistema de gradientes apresenta também uma baixa indutância, o que permitirá chaveamentos rápidos (~0.1 ms). Na análise do campo de gradiente gerado foi utilizado o método de diferença de fase, confirmando a eficiência da técnica de densidade de corrente utilizada nos cálculos para a construção destas bobinas de gradiente / Actively shielded coils are designed to improve the performance of a gradient coil set by canceling the magnetic field in the region outside the body of the coil, avoiding degradation of the field in its interior due to eddy currents induced in the electric vicinity. The present work resulted on the construction of a shielded gradient coil set (Gx, Gy e Gz) with cylindrical geometry and axial access, with volume diameter of 1 O cm (imaging FOV) and gradient field intensity of 8.0 Gauss/cm in r=0. The maximum gradient distortion aim was 5% inside that volume, along with an effective cancellation of the field close to the inner metallic parts of the OXFORD 2.0 Tesla 31 cm bore horizontal magnet. Preliminary results were obtained with a prototype, which included only one transverse channel, and a miniature set with the same geometry was specially designed to perform micro imaging experiments using pulsed Electron Paramagnetic Resonance. Coils were designed using the current density technique, which is based on the target field approach and simulated annealing for optimization. The gradient systems described here present also a low inductance necessary to perform fast switching (~0.1 ms). For the analysis of the performance of the gradients we used the method of phase reference, confirming the efficiency of the current density technique used on the design of the gradient sets

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1981. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Vita. / Includes bibliographical references. / by Joseph Vito Minervini. / Ph.D.

No description available.

Hot rolling process is heat input process. The heat energy in hot rolled steel coils can be utilized. At SSAB Strip Product Borlänge when the hot rolled steel coils came out of the hot rolling mill they are at the temperature range of 500°C to 800°C. Heat energy contained by the one hot rolled steel coil is about 1981Kwh whereas the total heat energy for the year 2008 is 230 GWh/year.The potential of heat is too much but the heat dissipation rate is too slow. Different factors on which heat dissipation rate depends are discussed.Three suggestions are proposed to collect the waste heat from hot rolled steel coils.The 2nd proposal in which water basin is suggested would help not only to collect the waste heat but to decrease in the cooling time.

Η διδακτορική διατριβή αναφέρεται στην χρήση των πηνίων λήψης κατά την απεικόνση μαγνητικού συντονισμού. Στα πλαίσια της ερευνητικής εργασίας προσομοιώθηκε ένα σύστημα πηνίων φασικής συνάφειας 4 ορθογωνικών στοιχείων με διαστάσεις μικρότερες των συμβατικών πηνίων για την βελτίωση του σηματοθορυβικού λόγου στις εξετάσεις του ανθρώπινου προστάτη. Το σύστημα αυτό στη συνέχεια σχεδιάστηκε και υλοποιήθηκε χρησιμοποιώντας συγκεκριμένες τεχνικές αποσύζευξης των γειτονικών στοιχείων, συντονισμού στη συχνότητα Larmor, προσαρμογής του φορτίου στα 50 Ohm και ελέγχου διακοπής. Η τελική μορφή του πηνίου εφαρμόστηκε σε κλινικό μαγνητικό τομογράφο 1.5Τ, όπου πραγματοποιήθηκαν μετρήσεις σε ομοιώματα και σε μία μεσαίου μεγέθους ανθρώπινη πυελική περιοχή. Τα αποτελέσματα συγκρίθηκαν με εκείνα των συμβατικων πηνίων (flex 4-channel cardiac coil), ενώ οι in vivo εξετάσεις έδειξαν σημαντική βελτίωση στο τελικό σήμα της εικόνας όταν χρησιμοποιούμε περισσότερο εντοπισμένα παραθύρα απεικόνισης (FOV). / The doctoral thesis refers to the use of receiver coils during MR imaging experiments. We simulated a 4-channel phased array system of orthogonal elements with reduced size compare to the conventional coils in order to improve the signal-to-noise ratio in prostate MR imaging. That system was then designed and developed using particular decoupling, tuning, matching and switching techniques. The final design was tested clinically on a 1.5T MRI system using phantoms at first and then an average sized human pelvic region. The results were compared to those extracted from a conventional flex 4-channel cardiac coil, while the in vivo images showed considerable improvement in contrast when we used more localized field of views.

Alpha-helical coiled-coils are common protein structural motifs with varied mechanical roles, such as, tropomyosin in muscle contraction or neck-stalks of kinesins and myosins, in motor proteins. Using computer simulations, we characterized elastic properties of coiled-coils both, globally and locally. Normal mode analysis for global elastic properties revealed a buckling instability due to inherently present weak non-bonded forces. We characterized this using a critical buckling length (lc). For coiled-coils, lc was significantly less than their persistence length thereby governing the filament conformation. We also found that mutations to the hydrophobic residues at the knob-into-hole interface affect elasticity of coiled-coils significantly. We built a flexibility map of tropomyosin using a local fluctuation analysis and found regional variations in flexibilities due to such breaks in the knob-into-hole packing. Overall, flexibility varies by more than twofold and increases towards the C-terminal region of the molecule. Actin binding sites in zones and broken core regions due to acidic residues at the hydrophobic face such as, the Asp137 and the Glu218, are found to be the most labile with moduli for splay and broad face bending as 70 nm and 116 nm, respectively. Such variations in flexibility could be relevant to the tropomyosin function, especially for moving across the non-uniform surface of F-actin to regulate myosin binding. Non-claret disjunction (Ncd), is a Kinesin-14 family protein that walks to the microtubule's minus end. Although available structures show its alpha-helical coiled-coil neck in either pre- or post-stroke orientations, little is known about the transition between these two states. Using a combination of molecular dynamics simulations and structural analyses, we find that the neck travel is a guided diffusion involving sequential intermediate contacts with the motor head. The post-stroke is at a higher free-energy minimum than the pre-stroke. The importance of intermediate contacts correlates with the existing motility data including those of mutant Ncds and other members of the kinesin-14 family. While the forward motion has a ~4.5 kBT (kB: Boltzmann constant, T = 300 K) free energy barrier, recovery stroke goes nearly downhill in free energy. The hysteresis in forward and reverse neck motion energetics arises from the mechanical compliance of the protein, and together with guided diffusion, it may be key for the directed motility of Ncd. Although it is known that neighboring Ncds on a microtubule (MT) have an attractive interaction and a group of Ncds act cooperatively, the physical basis of neither this attraction nor the cooperativity is known. From structural analysis of Ncd neighbors on an MT lattice we find that steric hindrances between the coiled-coil neck-stalks of longitudinal neighbors drive synchrony among a group of Ncds on a single protofilament. Across lateral dimers, surface loop L2 of the motor-head (MH) that is not bound to the MT (unbound-MH) in a pre-stroke dimer, is seen to have strong attraction to the nucleotide pocket in the MH that is bound to MT (bound-MH) of its off-axis neighbor. Such an attraction will however impede the motility in both the dimers. We hence propose rules that drive motor binding to an MT site in the presence of immediate neighbors such that motility of the group is not compromised. The unbound-MH, whose role in the walking step of an Ncd was unclear, is thus seen to regulate MT decoration.

Orientador: Paulo César Razuk / Banca: Augusto Ronchi Junior / Banca: Waldemar Gastoni Venturini Filho / Resumo: A fermentação alcólica, processo central da indústria cervejeira é um processo que libera uma grande quantidade de calor. Sendo assim, os recipientes de fermentação devem estar equipados com instalações de refrigeração para o correto controle da temperatura. A presente pesquisa tem como objetivo a análise da troca de calor de fermentadores cilindrocônicos dotados de sistema de refrigeração direta através de serpentina meia-cana. Para a consecução desse objetivo foi necessária a elaboração de um roteiro de cálculo seguro baseado em equações e experiências encontradas em renomadas literaturas. A análise dos resultados encontrados foi realizada a partir dos valores obtidos através do programa de cálculo atualmente utilizado em uma das maiores empresas fornecedoras deste tipo de equipamento para o mercado cervejeiro, a Dedini Indústrias de Base. Constatou-se que os valores obtidos pelo roteiro apresentado na presente dissertação foram maiores do que os calculados no programa, concluindo-se que as diferenças e dificuldades de resfriamento encontradas em equipamentos semelhantes fornecidos a clientes distintos podem ter origem na quantidade de refrigerante. As estimativas para o coeficiente global de transferência de calor independem do roteiro de cálculo seguido, pois há uma variação máxima de 3,5 % nos resultados para o cálculo deste. O mesmo é verificado para as vazões mássicas de amônia requerida, onde esta variação é ainda menor (cerca de 3,0%) / Abstract: Alcoholic fermentation, brewery industry's central process that liberates a great amount of heat. Therefore, the fermentation containers should be equipped with cooling installations for correct temperature control. The present research aims to analyze the heat exchange in cylindroconical fermenters endowed with a halp-pipe coil direct cooling system. To achieve this objective, the elaboration of a sate calculation route based on equations and experiences found in renowned references was necessary. The validation of the results was accomplished from the values obtained through the calculation program now used in one the largest supplying companies of this kind of equipment for the brewer market, Dedini indústrias de Base. It was verified that the flow of ammonia for the cooling system obtained by the itinerary introduced in the present article was larger than the one calculated in the program, and it can be concluded that the differences and cooling difficulties found in similar equipments supplied to different customers can have origin in the amount of ammonia used in the cooling system. The values for the overal heat transfer coefficient do not depend on the calculation itinerary followed, because there is a maximum variation of 3.5% in the results for the calculation of the coeffiecient. The same is verified for the mass flows of requested ammonia, where this variation is still smaller (about 3.0%) / Mestre

Made available in DSpace on 2014-06-11T19:25:27Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-06-25Bitstream added on 2014-06-13T19:32:32Z : No. of bitstreams: 1 silveira_rg_me_bauru.pdf: 2564361 bytes, checksum: 59979913e85e47f8a21eb524c379df8e (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A fermentação alcólica, processo central da indústria cervejeira é um processo que libera uma grande quantidade de calor. Sendo assim, os recipientes de fermentação devem estar equipados com instalações de refrigeração para o correto controle da temperatura. A presente pesquisa tem como objetivo a análise da troca de calor de fermentadores cilindrocônicos dotados de sistema de refrigeração direta através de serpentina meia-cana. Para a consecução desse objetivo foi necessária a elaboração de um roteiro de cálculo seguro baseado em equações e experiências encontradas em renomadas literaturas. A análise dos resultados encontrados foi realizada a partir dos valores obtidos através do programa de cálculo atualmente utilizado em uma das maiores empresas fornecedoras deste tipo de equipamento para o mercado cervejeiro, a Dedini Indústrias de Base. Constatou-se que os valores obtidos pelo roteiro apresentado na presente dissertação foram maiores do que os calculados no programa, concluindo-se que as diferenças e dificuldades de resfriamento encontradas em equipamentos semelhantes fornecidos a clientes distintos podem ter origem na quantidade de refrigerante. As estimativas para o coeficiente global de transferência de calor independem do roteiro de cálculo seguido, pois há uma variação máxima de 3,5 % nos resultados para o cálculo deste. O mesmo é verificado para as vazões mássicas de amônia requerida, onde esta variação é ainda menor (cerca de 3,0%) / Alcoholic fermentation, brewery industry's central process that liberates a great amount of heat. Therefore, the fermentation containers should be equipped with cooling installations for correct temperature control. The present research aims to analyze the heat exchange in cylindroconical fermenters endowed with a halp-pipe coil direct cooling system. To achieve this objective, the elaboration of a sate calculation route based on equations and experiences found in renowned references was necessary. The validation of the results was accomplished from the values obtained through the calculation program now used in one the largest supplying companies of this kind of equipment for the brewer market, Dedini indústrias de Base. It was verified that the flow of ammonia for the cooling system obtained by the itinerary introduced in the present article was larger than the one calculated in the program, and it can be concluded that the differences and cooling difficulties found in similar equipments supplied to different customers can have origin in the amount of ammonia used in the cooling system. The values for the overal heat transfer coefficient do not depend on the calculation itinerary followed, because there is a maximum variation of 3.5% in the results for the calculation of the coeffiecient. The same is verified for the mass flows of requested ammonia, where this variation is still smaller (about 3.0%)

abstract: A cerebral aneurysm is an abnormal ballooning of the blood vessel wall in the brain that occurs in approximately 6% of the general population. When a cerebral aneurysm ruptures, the subsequent damage is lethal damage in nearly 50% of cases. Over the past decade, endovascular treatment has emerged as an effective treatment option for cerebral aneurysms that is far less invasive than conventional surgical options. Nonetheless, the rate of successful treatment is as low as 50% for certain types of aneurysms. Treatment success has been correlated with favorable post-treatment hemodynamics. However, current understanding of the effects of endovascular treatment parameters on post-treatment hemodynamics is limited. This limitation is due in part to current challenges in in vivo flow measurement techniques. Improved understanding of post-treatment hemodynamics can lead to more effective treatments. However, the effects of treatment on hemodynamics may be patient-specific and thus, accurate tools that can predict hemodynamics on a case by case basis are also required for improving outcomes.Accordingly, the main objectives of this work were 1) to develop computational tools for predicting post-treatment hemodynamics and 2) to build a foundation of understanding on the effects of controllable treatment parameters on cerebral aneurysm hemodynamics. Experimental flow measurement techniques, using particle image velocimetry, were first developed for acquiring flow data in cerebral aneurysm models treated with an endovascular device. The experimental data were then used to guide the development of novel computational tools, which consider the physical properties, design specifications, and deployment mechanics of endovascular devices to simulate post-treatment hemodynamics. The effects of different endovascular treatment parameters on cerebral aneurysm hemodynamics were then characterized under controlled conditions. Lastly, application of the computational tools for interventional planning was demonstrated through the evaluation of two patient cases. / Dissertation/Thesis / Ph.D. Bioengineering 2013

As bobinas ativamente blindadas (actively shielded) melhoram a performance das bobinas de gradiente ao cancelar o campo magnético na parte externa da bobina primária, evitando a degradação do campo no seu interior devido às correntes induzidas (eddy currents). O presente trabalho resultou na construção de um conjunto de bobinas de gradientes ativamente blindadas (Gx, Gy e Gz ), de geometria cilíndrica e acesso axial, com diâmetro de volume útil de 10cm para imagens (field of view), com campos de gradiente de aproximadamente 8.0 G/cm para r=0, com uma máxima distorção de campo de 5% neste volume, onde foi observado um efetivo cancelamento do campo externo, o que evita correntes induzidas nas partes metálicas internas do magneto OXFORD de 2.0 Tesla horizontal de 30cm de diâmetro, no qual serão empregadas. Alguns resultados prévios foram obtidos com um protótipo transversal, em apenas uma direção, e também com um conjunto de bobinas de gradiente para utilização em obtenção de imagens microscópicas de ESR pulsado. As bobinas foram projetadas utilizando-se a técnica de densidade de corrente, que se baseia na abordagem de campo alvo (target field) e também foi empregado o método de \"simulated annealing\" para otimização do desenho. Este sistema de gradientes apresenta também uma baixa indutância, o que permitirá chaveamentos rápidos (~0.1 ms). Na análise do campo de gradiente gerado foi utilizado o método de diferença de fase, confirmando a eficiência da técnica de densidade de corrente utilizada nos cálculos para a construção destas bobinas de gradiente / Actively shielded coils are designed to improve the performance of a gradient coil set by canceling the magnetic field in the region outside the body of the coil, avoiding degradation of the field in its interior due to eddy currents induced in the electric vicinity. The present work resulted on the construction of a shielded gradient coil set (Gx, Gy e Gz) with cylindrical geometry and axial access, with volume diameter of 1 O cm (imaging FOV) and gradient field intensity of 8.0 Gauss/cm in r=0. The maximum gradient distortion aim was 5% inside that volume, along with an effective cancellation of the field close to the inner metallic parts of the OXFORD 2.0 Tesla 31 cm bore horizontal magnet. Preliminary results were obtained with a prototype, which included only one transverse channel, and a miniature set with the same geometry was specially designed to perform micro imaging experiments using pulsed Electron Paramagnetic Resonance. Coils were designed using the current density technique, which is based on the target field approach and simulated annealing for optimization. The gradient systems described here present also a low inductance necessary to perform fast switching (~0.1 ms). For the analysis of the performance of the gradients we used the method of phase reference, confirming the efficiency of the current density technique used on the design of the gradient sets