1,721,044 research outputs found
On self-similar solutions of the Navier-Stokes equations
No full textNecas, J.; Ruzicka, M.; Sverak, V.. (1995). On self-similar solutions of the Navier-Stokes equations. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/2775
A note on derivative estimates for a Hopf solution to the Navier- Stokes system in a three-dimensional cube
No full textProceedings of Conference in Madeira, 199
Bubble coalescence: effect of bubble approach velocity and liquid viscosity
No full textThe goal of this study is to present new experimental data on the effect of the bubble approach velocity and liquid viscosity on pairwise bubble coalescence. Measurements were performed to investigate the dynamics of bubble coalescence under well-defined laboratory conditions. Air and pure aqueous solutions of alginate (no surfactants) were the phases. The bubbles were formed from two vertical capillaries, under constant flow conditions. The coalescence process was recorded with a fast video and then image analysed, to evaluate the bubble growth, bubble expansion rate, the first bubble touch, bubble contact time T, bubble coalescence efficiency E. Three control parameters were tested. The bubble size D on contact was set by the spacing between the capillaries (D=1 and 1.5mm). The bubble approach velocity V was controlled by the gas input (V=0.031-39mm/s). The liquid viscosity μ was adjusted by the alginate content (μ=1.2-10.3mPas). It was found that the bubble contact time T monotonously increases with the liquid viscosity, passing through three stages: initial rise (low μ, coalescence), then jump (intermediate μ, transient region), and finally forming a plateau (high μ, non-coalescence). In the coalescent regime, the bubble contact time monotonously decreases with the bubble approach velocity obeying a power law, which for a typical 1mm bubble reads: T~V-0.85. The difference in the bubble size did not change the coalescence pattern qualitatively, but only quantitatively in a modest manne
Uncertainty of Estimated Rainflow Damage in Stationary Random Loadings and in Those Stationary per partes
Full text linkThe uncertainty of rainflow fatigue damage is evaluated for stationary loadings and for non-stationary switching loadings with a finite number of stationary states. The approach is based on confidence intervals constructed after direct analysis of stress-time histories. The accuracy of confidence intervals is verified first by numerical simulations, and then by experimental data measured in a mountain bike traveling under various driving and road surface conditions, yielding stationary and non-stationary switching loadings. Stationarity and non-stationarity of loading records is checked by a statistical method (run test). In experiments, a small set of records (validation set) is also collected and used to approximate the expected damage, which serves for verification purposes. Not only do numerical and experimental results confirm the correctness of the proposed confidence interval for damage, but they also emphasize its usefulness in real engineering applications
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
A probabilistic fatigue model based on nonlinear Kohout-Věchet function: Application to 42CrMo4+QT steel
No full textThis paper presents a fatigue model designed to provide probabilistic-stress-life (P-S-N) curves at any probability level. Grounded in the Weibull probabilistic model's framework, the model describes two scenarios: P-Case A, which considers deviations in stress, and P-Case B, centered on deviations in cycles to failure from the median S-N curve. A significant aspect of the proposed model is the incorporation of the Kohout-Vechet function as the representative median S-N curve, allowing for the Kohout-Vechet P-S-N curves across any probability level. To demonstrate the model's practical relevance, an experimental example focused on specimens made from 42CrMo4+QT steel and subjected to push-pull loading is explored. Not only do the results show the robustness of the model but they also emphasize the role of the characteristic P-S-N curves, especially at lower probability level, in assuring the safety of engineering components
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
- …
