Bibliografías temáticas / Fluctuation de tension

Literatura académica sobre el tema "Fluctuation de tension"

Autor: Grafiati

Publicado: 4 de mayo de 2024

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Artículos de revistas sobre el tema "Fluctuation de tension"

SCHMID, FRIEDERIKE. "FLUCTUATIONS IN LIPID BILAYERS: ARE THEY UNDERSTOOD?" Biophysical Reviews and Letters 08, n.º 01n02 (junio de 2013): 1–20. http://dx.doi.org/10.1142/s1793048012300113.

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We review recent computer simulation studies of undulating lipid bilayers. Theoretical interpretations of such fluctuating membranes are most commonly based on generalized Helfrich-type elastic models, with additional contributions of local "protrusions" and/or density fluctuations. Such models provide an excellent basis for describing the fluctuations of tensionless bilayers in the fluid Lαphase at a quantitative level.However, this description is found to fail for membranes in the gel phase and for membranes subject to high tensions. The fluctuations of tilted gel membranes (Lβ′phase) show a signature of the modulated ripple structure Pβ′, which is a nearby phase observed in the pretransition regime between the Lαand Lβ′state. This complicates a quantitative analysis on mesoscopic length scales. In the case of fluid membranes under tension, the large-wavelength fluctuation modes are found to be significantly softer than predicted by theory.In the latter context, we also address the general problem of the relation between frame tension and the fluctuation tension, which has been discussed somewhat controversially in recent years. Simulations of very simple model membranes with fixed area show that the fluctuations should be controlled by the frame tension, and not by the internal tension.

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Shiba, Hayato, Hiroshi Noguchi y Jean-Baptiste Fournier. "Monte Carlo study of the frame, fluctuation and internal tensions of fluctuating membranes with fixed area". Soft Matter 12, n.º 8 (2016): 2373–80. http://dx.doi.org/10.1039/c5sm01900a.

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Three types of surface tensions are investigated for lipid membranes using a lattice Monte Carlo simulation: the internal tension,σ, conjugated to the real membrane area, the mechanical frame tension,τ, conjugated to the projected area, and the “fluctuation tension”,r, obtained from the height fluctuation spectrum.

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Chen, Xiaohang y Weiwei Ye. "Analysis of Factors Affecting Strand Tension in Cable-Twisting Equipment and Method for Equilibrated Control". Applied Sciences 13, n.º 8 (7 de abril de 2023): 4690. http://dx.doi.org/10.3390/app13084690.

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To address the issue of tension fluctuations and deviations among the strands during cable-twisting production, it is necessary to establish a relationship model between the centrifugal force, frictional force, and tension experienced by each strand in a single span range under the state of traveling and rotating. Considering the differences of strand alignment at the distribution reel, the effects of centrifugal force and friction on strand tension under different twisting-deflection paths and cylinder-traveling paths should be analyzed. In our study, different stress states of each strand were applied to simulate and verify the tension fluctuations and deviations of every strand under various traveling and deflection paths. The experimental results show that the increasing travel path of the strand cylinder will cause an increase in the average strand tension. Different deflection paths in the distribution reel will affect the range of the strand tension fluctuation. A sliding mode controller based on a discrete system was designed in MATLAB to control the tension fluctuation and deviation among the strands. The results indicated that this control method can effectively reduce the tension deviation between strands, and the average tension fluctuation range of each strand was reduced by 79.5%.

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Zhao, Hai Xia y Ting Chu. "Analysis of Working Characteristics of Coreless Disc Tensioner in Winding Machine". Advanced Materials Research 821-822 (septiembre de 2013): 1446–49. http://dx.doi.org/10.4028/www.scientific.net/amr.821-822.1446.

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The paper introduces the structure and working principle of coreless disc tensioner, using Euler tension formula to calculate the output tension, analyzing the yarn diameterin ideal and actual situations and getting amplification characteristics of the disc tensioner against tension fluctuation. It is found that the tension disc will not expand the tension fluctuation amplitude in ideal condition, and its own performance has certain compensation for the tension fluctuation, which provides a the oretical basis for the design of the coreless disc tensioner and its wide application.

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Joachimi, B., F. Köhlinger, W. Handley y P. Lemos. "When tension is just a fluctuation". Astronomy & Astrophysics 647 (marzo de 2021): L5. http://dx.doi.org/10.1051/0004-6361/202039560.

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Summary statistics of likelihood, such as Bayesian evidence, offer a principled way of comparing models and assessing tension between, or within, the results of physical experiments. Noisy realisations of the data induce scatter in these model comparison statistics. For a realistic case of cosmological inference from large-scale structure, we show that the logarithm of the Bayes factor attains scatter of order unity, increasing significantly with stronger tension between the models under comparison. We develop an approximate procedure that quantifies the sampling distribution of the evidence at a small additional computational cost and apply it to real data to demonstrate the impact of the scatter, which acts to reduce the significance of any model discrepancies. Data compression is highlighted as a potential avenue to suppressing noise in the evidence to negligible levels, with a proof of concept demonstrated using Planck cosmic microwave background data.

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PRIVMAN, VLADIMIR. "FLUCTUATING INTERFACES, SURFACE TENSION, AND CAPILLARY WAVES: AN INTRODUCTION". International Journal of Modern Physics C 03, n.º 05 (octubre de 1992): 857–77. http://dx.doi.org/10.1142/s0129183192000531.

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We present an introduction to modern theories of interfacial fluctuations and the associated interfacial parameters: surface tension and surface stiffness, as well as their interpretation within the capillary wave model. Transfer matrix spectrum properties due to fluctuation of an interface in a long-cylinder geometry are reviewed. The roughening transition and properties of rigid interfaces below the roughening temperature in 3d lattice models are surveyed with emphasis on differences in fluctuations and transfer matrix spectral properties of rigid vs. rough interfaces.

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Li, Yan, Zhe Che, Chenggan Zheng, Zhi Li, Han Wang, Liang Cheng y Junxia Jiang. "Modeling of Precise Tension with Passive Dancers for Automated Fiber Placement". Actuators 13, n.º 2 (12 de febrero de 2024): 70. http://dx.doi.org/10.3390/act13020070.

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This paper modeled the tension fluctuation during automated fiber placement (AFP), which depicted the tension variations under different operating conditions. The stability and validity of the model were demonstrated using Bode plots and experiments, respectively. According to the model, the tension fluctuations of AFP at different stages were obtained. Additionally, the passive dancer parameters with the better system performance were determined using the evaluation methodology presented in this paper. Moreover, it was discovered that the damping coefficient affects the tension variation more significantly than the elasticity coefficient. Finally, the placement experiments showed that the determined passive dancer parameters improved the laying quality significantly.

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INDEKEU, J. O. "LINE TENSION AT WETTING". International Journal of Modern Physics B 08, n.º 03 (30 de enero de 1994): 309–45. http://dx.doi.org/10.1142/s0217979294000129.

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A review is presented of recent theoretical advances on a fundamental problem in statistical mechanics that concerns the three-phase contact line ℒ and its tension τ near a wetting phase transition. In addition to answering the intriguing question whether or not ℒ and τ vanish at wetting, recent work has also revealed that τ displays universal singular behavior, reflecting critical phenomena associated with the wetting transition. Three factors are crucial for determining the fate of ℒ and τ at wetting: the order of the wetting transition, the range of the intermolecular forces, and the upper critical dimension du, above which mean-field theory holds and below which fluctuations dominate. For most systems studied experimentally, du < 3, so that the mean-field predictions should be correct in d = 3. In the thermal fluctuation regime, for d < du, hyperscaling predicts the value 2(d – 2)/(d – 1) for the critical exponent of τ(θ), in the limit that the contact angle θ approaches 0.

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Tojo, Naoki, Mitsuya Otsuka y Atsushi Hayashi. "Comparison of intraocular pressure fluctuation before and after cataract surgeries in normal-tension glaucoma patients". European Journal of Ophthalmology 29, n.º 5 (26 de septiembre de 2018): 516–23. http://dx.doi.org/10.1177/1120672118801163.

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Purpose: Cataract surgeries have been shown to reduce intraocular pressure. We used a Sensimed Triggerfish® contact lens sensor to compare intraocular pressure levels and their fluctuation between before and after cataract surgeries in patients with normal-tension glaucoma. Methods: This was a prospective open-label study. Thirteen patients with normal-tension glaucoma were included. All patients underwent a 1-month washout and discontinued glaucoma medications during this study. In each eye, intraocular pressure fluctuations over 24 h were measured with the contact lens sensor before and at 3 months after the cataract surgery. We compared intraocular pressure levels and their fluctuation between before and after cataract surgeries. We used two approaches to evaluate the amplitude of intraocular pressure fluctuations: dual-harmonic regression analysis, and measurement of the difference between the maximum and the minimum value. Results: The mean pre-operative intraocular pressure was 14.7 ± 2.2 mm Hg and mean post-operative intraocular pressure was 11.4 ± 2.2 mm Hg. Cataract surgery significantly decreased intraocular pressure (p = 0.0005). In both methods, the post-operative fluctuations in intraocular pressure over 24 h were significantly smaller than their pre-operative counterparts (dual-harmonic regression analysis: p = 0.0171; difference between the maximum and the minimum: p = 0.0398). Conclusion: Cataract surgery decreased both intraocular pressure values and intraocular pressure fluctuations in normal-tension glaucoma patients.

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Chen, Hong Ren y Yi Yong Yao. "The Method of Tension Control with Gravity Balance". Applied Mechanics and Materials 590 (junio de 2014): 3–7. http://dx.doi.org/10.4028/www.scientific.net/amm.590.3.

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Carbon fiber is a fiber material, so the tension must be kept constant in the placement process. The attitude of carbon fiber placement head will change with the change of a placement path. Focusing on the problem of tension fluctuation caused by the attitude of carbon fiber placement head, gravity balance characteristic of symmetrical objects is adopted to propose a tension control method for eliminating the tension fluctuation and tension measuring error caused by gravity. In this way, the tension is kept constant depending on tension feedback control. Mathematical model and theoretical analysis show that the tension control method with gravity balance can eliminate the gravity influence on tension and make the tension keep constant.

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Tesis sobre el tema "Fluctuation de tension"

Дзюба, Л. Ф., І. Т. Ребезнюк, М. І. Пилипчук y О. Ю. Чмир. "ЕКСПЕРИМЕНТАЛЬНЕ ДОСЛІДЖЕННЯ ЗМІНИ СИЛИ НАТЯГУ СТРІЧКОВОЇ ПИЛКИ". Thesis, https://conferences.vntu.edu.ua/index.php/prmt/pmrt2021/paper/viewFile/13420/11294, 2021. https://sci.ldubgd.edu.ua/jspui/handle/123456789/9942.

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The change of the bandsaw tension force during wood cutting was investigated on the experimental installation created on the basis of the band saw machine. Experimental time dependen ce indicators of the tension force change in a narrow bandsaw during wood cutting were obtained. The influence ofthe pre-tension strain, the width of the saw blade and the cutting height on the pre-tension force change of the band saw was investigated.

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Balena, Rosianita. "Estudo analítico-numérico das vibrações induzidas por vórtices em trecho vertical de riser rígido, sujeito à variação de tração, e sua influência na fadiga". Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/3/3135/tde-18082010-162014/.

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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 aumento da profundidade, aumentam-se os esforços de tração sobre essas estruturas. Em águas profundas, essa desvantagem pode ser diminuída com a utilização de configurações mais complexas, dentre as quais se destaca a riser tower, que é foco do presente estudo. Este sistema é composto por vários dutos unidos ao longo de um tubo vertical único, sustentado por uma bóia de subsuperfície. Um grande atrativo desta configuração é a redução da fadiga devido às ondas, uma vez que a bóia e parte significativa dos risers rígidos verticais não sofrem efeitos relevantes das ondas de superfície. No entanto, dois problemas de interação fluido-estrutural persistem: um associado ao fenômeno de VIV Vibração Induzida pela Emissão de Vórtices no riser vertical e outro relativo ao VIM - Movimento Induzido pela Emissão de Vórtices na bóia. Devido ao fato da correnteza ser quase permanente, bem como das altas frequências passíveis de excitação, tem-se um número de ciclos de tensão bastante elevado, associados à flexão, o que pode ser importante no estudo de fadiga do material que compõe as referidas estruturas. De maneira mais completa, no que compete à fenomenologia das interações fluidoestruturais mencionadas, o presente trabalho propõe-se a estudar numérica e analiticamente a dinâmica transversal e longitudinal do conjunto formado pelo riser rígido e pela bóia de subsuperfície, particularmente focado nos efeitos da dinâmica sobre a vida útil do riser vertical.
The offshore oil production is performed with platforms, floating in most cases, which are connected to the well through pipes. These pipes are called risers and are responsible for the transport of crude oil, gas and water from seabed to the platform and vice-versa. From the structural standpoint, these risers can be rigid or flexible. However, independently of the type, the topside tension of these structures increases with the water depth. In deep water this disadvantage can be reduced by using more complex configurations, for example the riser tower, which is the focus of the current study. The riser tower is a system composed by pipes bundled around a central steel tube supported by a subsurface buoyancy tank. This configuration is attractive due to the reduction on waves fatigue since the buoy and most of the vertical risers length is not impacted by the effects of the surface waves. Nevertheless, two issues from the fluid-structural interaction still persist: one related to the VIV phenomena vortex-induced vibration on the vertical riser and the other associated to the VIM vortex induced motion on the buoyancy tank. Considering the almost permanent nature of the offshore currents associated to the high frequencies that can be excited, during the operational life, the riser is subjected to a large amount of stress cycles which are important for the evaluation of the structural integrity in terms of fatigue. In a more complete sense, considering the phenomenology of the fluid-structure interactions, the purpose of the present work is studying numerical and analytically the inline and cross-flow dynamics of the riser tower system especially focused on the impact of the dynamics on the vertical riser operational life.

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Etchart-Salas, Ramuntxo. "Projection par plasma d’arc de particules submicroniques en suspension : approche expérimentale et analytique des phénomènes impliqués dans la reproductibilité et la qualité des dépôts". Limoges, 2007. https://aurore.unilim.fr/theses/nxfile/default/648caa0a-0d53-4f45-8323-e7a1f0a5609b/blobholder:0/2007LIMO4058.pdf.

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Aujourd’hui, les « nanomatériaux » ouvrent des perspectives importantes dans diverses applications : énergie, aéronautique, automobile, etc. . . Un procédé relativement récent, la projection plasma de suspension, permet la formation de dépôt céramique finement voire nanostructuré avec de faibles épaisseurs (entre 5 µm et 10 µm). Néanmoins, la microstructure des dépôts obtenus passe par la compréhension d��un grand nombre de paramètres, et notamment l’injection de la suspension. Ces travaux ont particulièrement montré l’intérêt de l’injection et de la fragmentation de la suspension pour son traitement dans le plasma. L’injection de la suspension a été observée à l’aide d’un système optique qui permet de déclencher l’acquisition de l’image sur une valeur de tension d’arc de la torche. Ce système permet d’observer la trajectoire et la fragmentation de la suspension correspondante à un état instantané du jet de plasma. Cette étude a montré l’importance des fluctuations du jet de plasma sur la fragmentation et la trajectoire de la suspension. Il a été observé une grande différence de traitement de la suspension selon que l’on utilise un plasma Ar/H2 ou Ar/He. Le traitement des gouttes avec un plasma argon-hydrogène se fait de manière hétérogène, cette différence de traitement est due aux fluctuations de tension de la torche, et la porosité des dépôts formés en est directement liée. La diminution de ces instabilités avec un plasma Ar/He, par exemple, permet d’homogénéiser le traitement des gouttes de suspension. La diminution de la dispersion des trajectoires dans le plasma limite les particules infondues dans le dépôt, et par conséquent sa porosité. Ces travaux ont permis d’élaborer des dépôts de zircone avec une épaisseur de l’ordre de 10 µm et une faible porosité (~ 4%). Plusieurs dépôts denses (porosité de 4%) ont été formés que ce soit avec un plasma argon-hydrogène ou argon-hélium, à condition d’adapter l’injection de suspension avec les conditions plasmagènes de tir
Nanostructured coatings exhibits unique properties in various applications, such as aeronautics, energy, automotive, etc. . . Suspension Plasma Spraying (SPS) seems to be a promising technique to elaborate finely structured coatings with low thickness (between 5 µm to 10 µm). Nevertheless, SPS parameters which lead to control the microstructure of the deposit are not yet clearly identify, particularly for the injection of suspension. It has been shown that injection and fragmentation of the suspension into the plasma jet plays a key role in their further heat treatment. The injection of the suspension has been observed with a fast shutter camera coupled with a laser flash and triggered by a defined instantaneous voltage level of the plasma torch. Hence, the trajectories and fragmentations of the drops can be observed and correlated to an instantaneous plasma state. A particular attention is paid to the treatment of suspension jet or drops according to the importance of voltage fluctuations (linked to those of arc root) and depending on the different spray parameters such as the plasma forming gas mixture and the suspension momentum. A significant difference has been highlighted between argon-hydrogen and argon-helium plasma, mainly due to their strong fluctuation particularities. The heterogeneity of drops treatment using argon-hydrogen plasma is due to arc voltage fluctuations, and the enhancement of the coating porosity has been observed in this case. The stabilization of the interaction plasma jet-suspension increases when using plasmas with low arc voltage instabilities like Ar-He. The reduction of the drops dispersion into the plasma flow decreases the rate of unmellted particles into the coating and thus it porosity. These works have also allowed the formation of zirconia coatings with low thicknesses (~10 µm) and dense structure (~ 4% of porosity). Different dense deposits have been elaborated using either argon-hydrogen or argon-helium plasma, when the interaction plasma-suspension is controlled and adapted

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Wu, Chun-Hsien. "Quantum fluctuations of the stress tensor /". Thesis, Connect to Dissertations & Theses @ Tufts University, 2002.

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Thesis (Ph.D.)--Tufts University, 2002.
Adviser: L. H. Ford. Submitted to the Dept. of Physics. Includes bibliographical references (leaves 161-165). Access restricted to members of the Tufts University community. Also available via the World Wide Web;

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Moghaddam, Amir. "Dynamics of transformation and fragmentation of composite liquid nano-particles". Thesis, Queensland University of Technology, 2010. https://eprints.qut.edu.au/31776/1/Amir_Moghaddam_Thesis.pdf.

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Recent research on particle size distributions and particle concentrations near a busy road cannot be explained by the conventional mechanisms for particle evolution of combustion aerosols. Specifically they appear to be inadequate to explain the experimental observations of particle transformation and the evolution of the total number concentration. This resulted in the development of a new mechanism based on their thermal fragmentation, for the evolution of combustion aerosol nano-particles. A complex and comprehensive pattern of evolution of combustion aerosols, involving particle fragmentation, was then proposed and justified. In that model it was suggested that thermal fragmentation occurs in aggregates of primary particles each of which contains a solid graphite/carbon core surrounded by volatile molecules bonded to the core by strong covalent bonds. Due to the presence of strong covalent bonds between the core and the volatile (frill) molecules, such primary composite particles can be regarded as solid, despite the presence of significant (possibly, dominant) volatile component. Fragmentation occurs when weak van der Waals forces between such primary particles are overcome by their thermal (Brownian) motion. In this work, the accepted concept of thermal fragmentation is advanced to determine whether fragmentation is likely in liquid composite nano-particles. It has been demonstrated that at least at some stages of evolution, combustion aerosols contain a large number of composite liquid particles containing presumably several components such as water, oil, volatile compounds, and minerals. It is possible that such composite liquid particles may also experience thermal fragmentation and thus contribute to, for example, the evolution of the total number concentration as a function of distance from the source. Therefore, the aim of this project is to examine theoretically the possibility of thermal fragmentation of composite liquid nano-particles consisting of immiscible liquid v components. The specific focus is on ternary systems which include two immiscible liquid droplets surrounded by another medium (e.g., air). The analysis shows that three different structures are possible, the complete encapsulation of one liquid by the other, partial encapsulation of the two liquids in a composite particle, and the two droplets separated from each other. The probability of thermal fragmentation of two coagulated liquid droplets is discussed and examined for different volumes of the immiscible fluids in a composite liquid particle and their surface and interfacial tensions through the determination of the Gibbs free energy difference between the coagulated and fragmented states, and comparison of this energy difference with the typical thermal energy kT. The analysis reveals that fragmentation was found to be much more likely for a partially encapsulated particle than a completely encapsulated particle. In particular, it was found that thermal fragmentation was much more likely when the volume ratio of the two liquid droplets that constitute the composite particle are very different. Conversely, when the two liquid droplets are of similar volumes, the probability of thermal fragmentation is small. It is also demonstrated that the Gibbs free energy difference between the coagulated and fragmented states is not the only important factor determining the probability of thermal fragmentation of composite liquid particles. The second essential factor is the actual structure of the composite particle. It is shown that the probability of thermal fragmentation is also strongly dependent on the distance that each of the liquid droplets should travel to reach the fragmented state. In particular, if this distance is larger than the mean free path for the considered droplets in the air, the probability of thermal fragmentation should be negligible. In particular, it follows form here that fragmentation of the composite particle in the state with complete encapsulation is highly unlikely because of the larger distance that the two droplets must travel in order to separate. The analysis of composite liquid particles with the interfacial parameters that are expected in combustion aerosols demonstrates that thermal fragmentation of these vi particles may occur, and this mechanism may play a role in the evolution of combustion aerosols. Conditions for thermal fragmentation to play a significant role (for aerosol particles other than those from motor vehicle exhaust) are determined and examined theoretically. Conditions for spontaneous transformation between the states of composite particles with complete and partial encapsulation are also examined, demonstrating the possibility of such transformation in combustion aerosols. Indeed it was shown that for some typical components found in aerosols that transformation could take place on time scales less than 20 s. The analysis showed that factors that influenced surface and interfacial tension played an important role in this transformation process. It is suggested that such transformation may, for example, result in a delayed evaporation of composite particles with significant water component, leading to observable effects in evolution of combustion aerosols (including possible local humidity maximums near a source, such as a busy road). The obtained results will be important for further development and understanding of aerosol physics and technologies, including combustion aerosols and their evolution near a source.

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Gallet, François. "La nature de la transition rugueuse : l'exemple des cristaux d'hélium 4". Paris 6, 1986. http://www.theses.fr/1986PA066402.

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Mesures précises de la tension de surface, de l'énergie de gradin et de la vitesse de croissance pour l'orientation (0001), au voisinage de la transition rugueuse à t = 1,28 k; mise en évidence de la croissance par nucléation bidimensionnelle et de l'élargissement dynamique de la transition. Très bon accord avec les prévisions de la théorie critique qui apparente cette transition aux transitions de Kosterlitz-Thouless.

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Karkan, Delara M. "Spontaneous fluctuations of oxygen tension in tissue is similar to vasomotion of isolated pressurized arterioles". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape9/PQDD_0033/NQ38909.pdf.

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Schiappacasse, Enrico D. "Beyond Semiclassical Gravity| Quantum Stress Tensor Fluctuations in the Vacuum". Thesis, Tufts University, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10812605.

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Large vacuum fluctuations of a quantum stress tensor can be described by the asymptotic behavior of its probability distribution. Here we focus on stress tensor operators which have been averaged with a sampling function in time. The Minkowski vacuum state is not an eigenstate of the time-averaged operator, but can be expanded in terms of its eigenstates. We calculate the probability distribution and the cumulative probability distribution for obtaining a given value in a measurement of the time-averaged operator taken in the vacuum state. In these calculations, we use the normal ordered square of the time derivative of a massless scalar field in Minkowski spacetime as an example of a stress tensor operator. We analyze the rate of decrease of the tail of the probability distribution for different temporal sampling functions, such as compactly supported functions and the Lorentzian function. We find that the tails decrease relatively slowly, as exponentials of fractional powers, in agreement with previous work using the moments of the distribution. Our results lead additional support to the conclusion that large vacuum stress tensor fluctuations are more probable than large thermal fluctuations, and may have observable effects.

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Domenech, Fuertes Guillem. "Inflationary Cosmology in Scalar-Tensor Theories". Kyoto University, 2017. http://hdl.handle.net/2433/227579.

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Moubdi, Nabila. "Méthodes de compensation des fluctuations des procédés de fabrication en vue d'ajustement des performances temporelles et énergétiques d'un système-sur-puce". Thesis, Montpellier 2, 2010. http://www.theses.fr/2010MON20096.

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L'ère des technologies CMOS fortement submicroniques et des circuits à hautes performances temporelles et énergétiques exige la réduction de l'impact sur les circuits : de la fluctuation du procédé de fabrication (P), de la tension d'alimentation (V) et de la température (T). Il est donc nécessaire de mettre en place des capteurs ou ring oscillateurs sur puce dédiés à la qualification intrinsèque des circuits intégrés en termes de PVT. Les capteurs seront activés pendant la phase de test des circuits ou pendant leur phase de fonctionnement normal, et les mesures seront converties en données numériques permettant de classifier les performances temporelles et énergétiques du système-sur-puce. Dans ce cadre, la présente thèse en milieu industriel a permis le développement de techniques et d'algorithmes de compensations post-fabrication en réduisant la consommation et/ou augmentant la vitesse du circuit. Précisément, les algorithmes validés au niveau silicium utilisent l'ajustement de la tension d'alimentation pour une compensation à gros-grain, ainsi que l'ajustement de la tension des substrats des transistors NMOS et PMOS pour une compensation à fin-grain
The new requirement for nanometer CMOS technologies enabling optimal speedand power performances is to increase the integrated circuits' robustness under thefluctuation of the PVT parameters: Process (P), Voltage (V), and Temperature (T). In thisway, identifying the exact process on a die per die basis using on-chip sensors or ringoscillators becomes a necessity. This hardware (sensors) is used to measure the intrinsicperformance of the silicon either during industrial test or while applications are running. Thesensors' data are converted to a digital format in order to classify parts at the manufacturingstage (speed binning). Within this context, the present thesis has focused on the developmentof post-manufacturing compensation algorithms in order to minimise power consumptionand/or maximise speed. More precisely, the algorithms validated at the silicon level combineboth the voltage scaling for large-grain tuning, and the body biasing for fine-grain tuning

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Libros sobre el tema "Fluctuation de tension"

Pelkmans, Mathijs. Conclusion. Cornell University Press, 2017. http://dx.doi.org/10.7591/cornell/9781501705137.003.0008.

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This book has studied the relationship between sociopolitical instability and conviction by focusing on how secular and religious collective ideas fared in conditions of existential uncertainty in Kokjangak. It has also examined the precarious attempts of “secularists” to position themselves between fading Soviet atheism and assertions of new forms of religiosity and how spiritual practitioners who were sometimes labeled “shamans” operated in unpredictable spiritual fields. This conclusion considers the pulsation and dynamics of conviction and introduces a conceptual framework to show how collective ideas gain and lose force. The term “pulsation” emphasizes impermanence and fluctuation as key characteristics of ideational power. Three aspects of pulsation are discussed involving hope, tension, and effervescence: voicing, responding, and reverberating, respectively.

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Allen, Michael P. y Dominic J. Tildesley. Inhomogeneous fluids. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780198803195.003.0014.

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In this chapter, the special techniques needed to simulate and calculate properties for inhomogeneous systems are presented. The estimation of surface properties, such as the interfacial tension, may be accomplished by a variety of methods, including the calculation of the stress tensor profiles, the change in the potential energy on scaling the surface area at constant volume, the observation of equilibrium capillary wave fluctuations, or direct free energy measurement by cleaving. The structure within the interface is also of interest, and ways of quantifying this are described. Practical issues such as system size, preparation of a two-phase system, and equilibration time, are discussed. Special application areas, such as liquid drops, fluid membranes, and liquid crystals, are described.

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Deruelle, Nathalie y Jean-Philippe Uzan. Primordial quantum perturbations. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198786399.003.0062.

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This chapter shows that fluctuations of quantum origin are generated during inflation and that this process supplies initial conditions compatible with the observations. These fluctuations are therefore an important prediction of inflationary models. The chapter thus begins with a study of perturbations during inflation, proceeding in a similar manner to the previous chapter by finding the perturbation of the energy–momentum tensor of the scalar field. Another method of deriving the equations of motion of the perturbations is to start from the action of general relativity coupled to a scalar field, and expand to second order in the metric and scalar field perturbations. The chapter then proceeds with the determination of the initial conditions and the slow-roll inflation.

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Maggiore, Michele. Gravitational Waves. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198570899.001.0001.

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A comprehensive and detailed account of the physics of gravitational waves and their role in astrophysics and cosmology. The part on astrophysical sources of gravitational waves includes chapters on GWs from supernovae, neutron stars (neutron star normal modes, CFS instability, r-modes), black-hole perturbation theory (Regge-Wheeler and Zerilli equations, Teukoslky equation for rotating BHs, quasi-normal modes) coalescing compact binaries (effective one-body formalism, numerical relativity), discovery of gravitational waves at the advanced LIGO interferometers (discoveries of GW150914, GW151226, tests of general relativity, astrophysical implications), supermassive black holes (supermassive black-hole binaries, EMRI, relevance for LISA and pulsar timing arrays). The part on gravitational waves and cosmology include discussions of FRW cosmology, cosmological perturbation theory (helicity decomposition, scalar and tensor perturbations, Bardeen variables, power spectra, transfer functions for scalar and tensor modes), the effects of GWs on the Cosmic Microwave Background (ISW effect, CMB polarization, E and B modes), inflation (amplification of vacuum fluctuations, quantum fields in curved space, generation of scalar and tensor perturbations, Mukhanov-Sasaki equation,reheating, preheating), stochastic backgrounds of cosmological origin (phase transitions, cosmic strings, alternatives to inflation, bounds on primordial GWs) and search of stochastic backgrounds with Pulsar Timing Arrays (PTA).

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Capítulos de libros sobre el tema "Fluctuation de tension"

Shiraishi, Maresuke. "Fluctuations in Inflation". En Probing the Early Universe with the CMB Scalar, Vector and Tensor Bispectrum, 5–11. Tokyo: Springer Japan, 2013. http://dx.doi.org/10.1007/978-4-431-54180-6_2.

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Meunier, J. "Surface Tension and Rigidity: Role of the Fluctuations and Optical Measurements". En Springer Proceedings in Physics, 118–23. Berlin, Heidelberg: Springer Berlin Heidelberg, 1987. http://dx.doi.org/10.1007/978-3-642-83202-4_15.

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Shiraishi, Maresuke. "Fluctuations in Cosmic Microwave Background Radiation". En Probing the Early Universe with the CMB Scalar, Vector and Tensor Bispectrum, 13–50. Tokyo: Springer Japan, 2013. http://dx.doi.org/10.1007/978-4-431-54180-6_3.

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Könözsy, László. "Three-Dimensional Anisotropic Similarity Theory of Turbulent Velocity Fluctuations". En A New Hypothesis on the Anisotropic Reynolds Stress Tensor for Turbulent Flows, 67–103. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-13543-0_4.

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Na, Hyuntae, Tu-Liang Lin y Guang Song. "Generalized Spring Tensor Models for Protein Fluctuation Dynamics and Conformation Changes". En Advances in Experimental Medicine and Biology, 107–35. Cham: Springer International Publishing, 2013. http://dx.doi.org/10.1007/978-3-319-02970-2_5.

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Cárdenas-Navia, L. Isabel, Rod Braun, Kristina Lewis y Mark W. Dewhirst. "Comparison of Fluctuations of Oxygen Tension in FSA, 9L, and R3230AC Tumors in Rats". En Advances in Experimental Medicine and Biology, 7–12. Boston, MA: Springer US, 2003. http://dx.doi.org/10.1007/978-1-4615-0205-0_2.

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Moretti, Valter. "Local ζ -functions, stress-energy tensor, field fluctuations, and all that, in curved static spacetime". En Springer Proceedings in Physics, 323–32. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-19760-4_30.

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McCallum, Sarah L. "Warriors in Love". En Elegiac Love and Death in Vergil's Aeneid, 99–122. Oxford University PressOxford, 2023. http://dx.doi.org/10.1093/oso/9780192863003.003.0005.

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Abstract This chapter examines two striking aetiological myths that are embedded within the epic catalogues of the Italian Iliad. As Vergil enumerates the mustering Italian forces (A. 7.641–817) and the fleet of Aeneas’ Etruscan allies (A. 10.163–817), he shifts the focus from each spectacle of arma to a tale of metamorphosis: Hippolytus’ resurrection and transformation into Virbius (A. 7.765–77); and the avian transfiguration of Cycnus (A. 10.185–88). By interweaving each mythological tale with amatory and funerary elegiac material, Vergil creates exceptional aesthetic and thematic vignettes that exist in productive tension with the surrounding martial context. The aesthetic fluctuation between epic and elegy articulates the crucial tension between arma, amor, and mors that drives the narrative of the maius opus. Moreover, the intra- and intertextual reveberations of these episodes reveals Vergil’s enduring commitment to Alexandrian aesthetic principals, his intense engagement with the recent innovations of Propertius and Tibullus, and his perpetuation of the poetic legacy of Gallus.

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"Fluctuations around an Embedded Positive–Tension Minkowski Brane". En Brane-Localized Gravity, 133–66. WORLD SCIENTIFIC, 2005. http://dx.doi.org/10.1142/9789812703132_0017.

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"Fluctuations around an Embedded Negative–Tension Minkowski Brane". En Brane-Localized Gravity, 167–87. WORLD SCIENTIFIC, 2005. http://dx.doi.org/10.1142/9789812703132_0018.

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Actas de conferencias sobre el tema "Fluctuation de tension"

Myslivets, E., C. Lundström, S. Moro, A. O. J. Wiberg, C.-S. Bres, N. Alic, P. A. Andrekson y S. Radic. "Dispersion Fluctuation Equalization Nonlinear Fibers by Spatially Controlled Tension". En Optical Fiber Communication Conference. Washington, D.C.: OSA, 2010. http://dx.doi.org/10.1364/ofc.2010.otua5.

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Lim, H. O., M. J. Seo, Y. Kang y K. W. Jun. "Solid Fluctuations and Dispersion in Liquid-Solid Fluidized Beds With Low Surface Tension Media". En ASME-JSME-KSME 2011 Joint Fluids Engineering Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/ajk2011-09003.

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Fluctuations and dispersion of solid particles were investigated in a liquid-solid fluidized bed of which diameter was 0.102 m and 2.5 m in height. Effects of liquid velocity (0.005 ∼ 0.13 m/s), particle size (0.5 ∼ 3.0 × 10−3 m) and surface tension of continuous liquid media (56 ∼ 72 × 10−3 N/m) on the fluctuation frequency and dispersion coefficient of fluidized solid particles were determined. The fluctuating frequency and dispersion coefficient of particles were estimated by means of the relaxation model based on the stochastic theory. Both of fluctuating frequency and dispersion coefficient of particles showed maximum values with a variation of liquid velocity and increased with an increase in the particle size or surface tension of liquid media. The values of fluctuating frequency and dispersion coefficient of fluidized solid particles were well correlated in terms of dimensionless groups as well as operating variables.

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Balaji, Raghavan y Eric M. Mockensturm. "Dynamic Analysis of a Serpentine Belt Drive With a Decoupler/Isolator". En ASME 2004 International Mechanical Engineering Congress and Exposition. ASMEDC, 2004. http://dx.doi.org/10.1115/imece2004-61662.

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Belt drives employing a single, flat serpentine belt tensioned by a passive tensioner are found in automotive engine Front End Accessory Drive (FEAD) where the crankshaft supplies power to accessories like alternators, air-conditioning compressors, pumps, etc. [1]. When the FEAD undergoes forced vibration due to crankshaft excitation, dynamic tension fluctuations can cause the belt to slip on the accessory pulleys [2]. The probability of belt slip increases with the peak drop in belt tension over the pulley during steady state operation [3]. In this paper, one possible solution is analyzed, using a decoupler to isolate/separate the accessory inertia (e.g. alternator) from the FEAD system. This is achieved by placing between the pulley and the accessory a combination of a one-way rigid clutch and an isolator spring. In this study, the rotational response of a typical FEAD is extended to include the clutch and isolator. An analytical solution is then obtained by considering it as a piecewise-linearized system moving about an equilibrium angular displacements. The performance of the ordinary FEAD with regard to tension fluctuation is then compared to that of the system equipped with a decoupler/isolator. The results obtained indicate that within the practical working range of engine speeds, use of either an isolator or a decoupler-isolator could significantly lower the dynamic tension drop across the accessory pulley.

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Masamoto, Kazuto, Kotaro Oka, Hirosuke Kobayashi, Yuki Sannohe, Naosada Takizawa y Kazuo Tanishita. "Distribution of Oxygen Tension in Neocortical Areas in the Rat Somatosensory Cortex". En ASME 2000 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/imece2000-2627.

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Abstract The purpose of this study is to identify the localized differentiation of oxygen transport in the brain. We measured oxygen tension in three neocortical areas (FL, HL, and Tr) of the rat somatosensory cortex by microcoaxial needle electrodes. The structure of neocortical area is characterized by the variation of cell shape, spatial distribution and size, which results in the following three types of the oxygen tension distribution; random, fluctuation, and hypoxia.

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Conwell, James C., Glen E. Johnson y S. W. Peterson. "Experimental Investigation of the Forces in a Link Side Plate During Normal Operation of a Roller Chain Drive". En ASME 1992 Design Technical Conferences. American Society of Mechanical Engineers, 1992. http://dx.doi.org/10.1115/detc1992-0091.

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Abstract The fluctuation in the tension of a chain link during normal operation is very likely the root cause of chain stretch and fatigue in roller chain drives. In this paper we present the results from a recent experimental investigation of this tension variation phenomenon. The experimental procedure is described, and data are presented for a wide range of initial tensions, transmitted loads, and chain speeds. At low speeds, the data give reasonable agreement with previously published theoretical models for quasi-static load distribution. However, at higher speeds (where inertia effects are more significant) the experimental results indicate that quasi-static models do not provide an adequate explanation. The differences are noted and discussed. An empirical equation for “tight side” chain tension is presented in terms of torque transmitted, sprocket pitch radius, mass per unit length of chain, and linear chain speed. This paper is accompanied by companion papers that describe the design and construction of the test machine and the measurement of the impact force as a roller seats on the sprocket.

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TIAN, Ye. "Mechanical behavior and flow curve modeling of AZ31B magnesium alloy under low frequency vibration assisted tension". En Material Forming. Materials Research Forum LLC, 2024. http://dx.doi.org/10.21741/9781644903131-76.

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Abstract. This study aimed to investigate the impact of the low-frequency vibration field on the mechanical behavior of AZ31B magnesium alloy. To achieve this, a series of low-frequency vibration-assisted tensile tests were conducted at room temperature. The effect of various vibration parameters on the mechanical characteristics of AZ31B was studied. The findings indicate that the introduction of low-frequency vibration field during the traditional tensile process leads to periodic oscillations in the flow stress of the material. Moreover, the maximum stress value was greater than the condition without vibration. The vibration hardening value is not significantly affected by the vibration frequency, but rather depends on the amplitude. The magnitude of the vibration hardening value increases with the increasing amplitude, and this relationship is non-linear. On this basis, a modified Hockett-Sherby hardening model was constructed by incorporating the vibration parameters. Statistical analysis of stress-strain curve, vibration hardening and stress fluctuation values were conducted to identify the model parameters. By comparing with the experimental result, the stress change of AZ31B magnesium alloy under low frequency vibration tension could be well predicted by this model.

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Chen, Tao y Zhichao Hou. "Summation Resonance of Parametrically Excited Moving Viscoelastic Belts". En ASME 2003 International Mechanical Engineering Congress and Exposition. ASMEDC, 2003. http://dx.doi.org/10.1115/imece2003-43995.

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The nonlinear dynamic analysis is performed on parametrically excited, viscoelastic moving-belts at summation resonance. The belt material behavior is described by a Voigt-Kelvin model. Closed-form solutions are derived at the first order approximation. Focus is put on the stability of the nontrivial solutions. The explicit expressions on the stability conditions are obtained, and then simplified through numerical simulations. The influences of moving speed and tension fluctuation on the stability of the nontrivial solutions are also demonstrated.

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Branscomb, David J., David G. Beale y Royall M. Broughton. "Application of Machine Vision Techniques for Fault Diagnostics and System Examination of Braid". En ASME 2010 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/detc2010-29012.

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Important factors of braid formation are yarn motion, yarn tension and intra-yarn frictional forces. In order to improve quality of braided structures the effects of yarn tension and resulting braid formation position must be understood and controlled. This paper reports the effect of yarn tension on braid formation (braid point) motion along with the radial and longitudinal motion of the braid point in the initial, transient, and final positions. Visual observations utilizing low cost webcams are also presented as well as a diagnostic tool which can recognize the onset of defects and provide some insight into what might be causing the fault. Optimal braid performance is observed which serves as the baseline for comparing the behavior of faults. Radial fluctuation of braid point position is a good indicator of mechanical faults of the tensioning mechanisms. The experiments performed will provide the foundation for further work with applications for improving braiding quality in ropes, tethers, and structural composites. Finally, this experimental study and dynamic characterization will be useful for assessing future passive and active control methods, along with sensing.

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Suzuki, Hideyuki, Kotaro Takano, Kazuo Enomoto y Noriaki Oka. "Axial and Lateral Coupled Response of a Deepsea Riser for Scientific Drilling". En ASME 2004 23rd International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2004. http://dx.doi.org/10.1115/omae2004-51094.

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Axial and lateral coupled response of deepsea drilling risers in hang-off condition was investigated. Lateral oscillation of riser has a possibility of being excited by axial tension fluctuation. The lateral response can be described by Mathieu’s equation of parametric oscillation. Numerical analysis method was formulated and verified by comparisons with experimental results. Stability conditions were clarified using the numerical method. Stability of the 4,000m riser for Scientific Drilling was also investigated and guideline for design of ultra deepwater risers was proposed.

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Chen, Li-Qun. "Principal Parametric Resonance of Axially Accelerating Viscoelastic Strings". En ASME 2005 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2005. http://dx.doi.org/10.1115/detc2005-84435.

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The steady-state transverse responses and the stability of an axially accelerating viscoelastic string are investigated. The governing equation is derived from the Eulerian equation of motion of a continuum, which leads to the Mote model for transverse motion. The Kirchhoff model is derived from the Mote model by replacing the tension with the averaged tension over the string. The method of multiple scales is applied to the two models in the case of principal parametric resonance. Closed-form expressions of the amplitudes and the existence conditions of steady-state periodical responses are presented. The Lyapunov linearized stability theory is employed to demonstrate that the first (second) nontrivial steady-state response is always stable (unstable). Numerical calculations show that the two models are qualitatively the same, but quantitatively different. Numerical results are also presented to highlight the effects of the mean axial speed, the axial speed fluctuation amplitude, and the viscoelastic parameters.

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Informes sobre el tema "Fluctuation de tension"

Liu y Nixon. L52305 Probabilistic Analysis of Pipeline Uplift Resistance. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), junio de 2010. http://dx.doi.org/10.55274/r0000002.

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To investigate the feasibility of probabilistic analyses of the peak uplift resistance in frozen soils by varying parameters that are known to be important for the development of the uplift resistance under the upward movement of a pipe. A buried pipeline will be subjected to a variety of forces, both internal and external, including the interaction of the pipe with the surrounding soil. The soil-pipe interaction in permafrost regions have to account for the behavior of frozen and unfrozen soil, and transitions between the two as the pipeline traverses in a discontinuous permafrost zone. The variations in the properties and behavior of frozen soils are expected to be substantial in three dimensions of the Right-of-Way (ROW) and with time (seasonal fluctuations and changes with the history of pipeline operation). Given the uncertainties with frozen soil properties and the changes in behavior with time and location, a large variation in soil-pipe interaction characteristics can exist. The uplift resistance of a pipeline is one of these soil-pipe interactions that can be impacted by a variation in soil condition and state. A need was identified to outline the use of a probabilistic analysis of pipe uplift resistance in an attempt to capture the magnitude of these variations and uncertainties of frozen soil and the impact on the soil-pipe interaction. The probabilistic analysis allows the designer of a pipeline to consider a range of uplift resistance to a certain confidence level that would represent the likely values that a pipe may be subjected to. The work presented in this report is more focused on the methodology of the probabilistic approach, rather than the analysis itself for a specific design case, even though an example is provided for illustration purposes. A series of numerical simulations using Fast Lagrangian Analysis of Continua (FLAC) were completed varying one parameter with each run to develop a library of peak uplift resistances for a variety of different temperatures, soil properties and pipe parameters. The FLAC model was previously developed for PRC, a summary of this report is provided here to outline important parameters that were used to complete this analysis. The simulations were used to develop a correlation of peak uplift resistance as a function of soil tensile strain limit, modulus of deformation, and creep of frozen soils. Each of these parameters is dependent of the pipeline conditions such as temperature, displacement rate, and effective frozen cover depth. It is noted that the scope of the work was to develop a probabilistic method of estimating peak uplift resistance in frozen soils. Even though some sensitivity analysis were carried out, as outlined later in this report, to assess the impacts of the variable, detailed uncertainty analysis or risk assessment were not performed.

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