Tension Fluctuation
Mostrando 1-10 de 10 artigos, teses e dissertações.
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1. Analytic-Numerical study of Vortex-Induced Vibrations in a vertical rigid riser, subjected to tension fluctuation and its influence in fatigue. / Estudo analítico-numérico das vibrações induzidas por vórtices em trecho vertical de riser rígido, sujeito à variação de tração, e sua influência na fadiga.
A produção de petróleo em ambiente marítimo é feita através de plataformas, em geral flutuantes, conectadas aos reservatórios através de dutos, os chamados risers, responsáveis pelo transporte de petróleo bruto, gás ou água. Do ponto de vista estrutural, estes risers podem ser rígidos ou flexíveis, porém, independente do tipo empregado, com o
Publicado em: 2010
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2. THE RESEARCH AND DEVELOPMENT OF AN DRIVER FOR STEP MOTOR OPERATING IN LOW TENSION / PESQUISA E DESENVOLVIMENTO DE UM ACIONAMENTO PARA MOTOR DE PASSO OPERANDO EM BAIXA TENSÃO
The research and development of an driver for step motor operating in low tension presents the development of a chopper driver intended to drive 2- phase step motors. The driver was designed to operate between 12 and 18 V which makes it very attractive for automations in vehicles and robots which carry their own batteries. Contrary to the usual design, where
Publicado em: 2005
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3. Calculation of volume fluctuation for globular protein models.
The extent of volume fluctuation is calculated for two simple geometrical models of globular protein molecules subjected to a potential that is proportional to the surface area freshly generated by the thermal breathing motion. The proportionality constant, gamma, has the unit of surface tension. The calculated values are compared with estimates made from th
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4. Flickering Analysis of Erythrocyte Mechanical Properties: Dependence on Oxygenation Level, Cell Shape, and Hydration Level
Erythrocytes (red blood cells) play an essential role in the respiratory functions of vertebrates, carrying oxygen from lungs to tissues and CO2 from tissues to lungs. They are mechanically very soft, enabling circulation through small capillaries. The small thermally induced displacements of the membrane provide an important tool in the investigation of the
The Biophysical Society.
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5. Buckling, stiffening, and negative dissipation in the dynamics of a biopolymer in an active medium
We present a generic theory for the dynamics of a stiff filament under tension, in an active medium with orientational correlations, such as a microtubule in contractile actin. In sharp contrast to the case of a passive medium, we find the filament can stiffen, and possibly oscillate or buckle, depending on both the contractile or tensile nature of the activ
National Academy of Sciences.
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6. Dimensional and mechanical dynamics of active and stable edges in motile fibroblasts investigated by using atomic force microscopy
The atomic force microscope (AFM) was employed to investigate the extension and retraction dynamics of protruding and stable edges of motile 3T3 fibroblasts in culture. Such dynamics closely paralleled the results of earlier studies employing video microscopy that indicated that the AFM force-mapping technique does not appreciably perturb these dynamics. For
The National Academy of Sciences.
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7. Influence of Oxygen on Development of Nitrate Respiration in Bacillus stearothermophilus
A denitrifying mutant of Bacillus stearothermophilus NCA 2184, strain 2184-D, was used to explore the development of nitrate respiration in relation to oxygen respiration. Aerobically grown wild-type cultures could acquire the ability to use nitrate as a result of selection of nitrate-respiring mutants by the presence of nitrate and a reduced oxygen tension.
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8. A robotic system for 18F-FMISO PET-guided intratumoral pO2 measurements
An image-guided robotic system was used to measure the oxygen tension (pO2) in rodent tumor xenografts using interstitial probes guided by tumor hypoxia PET images. Rats with ∼1 cm diameter tumors were anesthetized and immobilized in a custom-fabricated whole-body mold. Imaging was performed using a dedicated small-animal PET scanner (R4 or Focus 120 micro
American Association of Physicists in Medicine.
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9. Efferent discharges recorded from single skeletomotor and fusimotor fibres in man.
Experiments were performed on awake human subjects in which single nerve fibre activity was recorded in the lateral peroneal nerve using tungsten micro-electrodes as described by Hagbarth & Vallbo (1967, 1968a). The discharge of twelve single efferent fibres innervating the tibialis anterior muscle (t.a.) or the extensor digitorum longus muscle (e.d.l.) was
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10. The effect of small changes in arterial carbon dioxide tension on carotid chemoreceptor activity in the cat.
The hypothesis that the fluctuations in carotid chemoreceptor discharge represent more than a simple proportional response to respiratory oscillations of Pa, CO2 has been examined. Simultaneous recordings of the activity in few- or multi-fibre chemoreceptor preparations of the cut carotid sinus nerve and oscillations of carotid arterial pH have been made in