Search results for "Friction force"
showing 6 items of 6 documents
Tentacle-shaped mesh for fixation-free repair of umbilical hernias
2019
Purpose: Mesh fixation and broad overlap represent an open issue in umbilical hernia repair. A proprietary-designed implant with tentacle straps at its boundary has been developed to ensure a suture-free repair and a broader coverage of the abdominal wall. The study describes the results of umbilical hernia procedures carried out with the tentacle-shaped implant and the related surgical technique. Methods: A proprietary tentacle-shaped flat mesh having a central body with integrated radiating arms at its edge was used to repair large umbilical hernias in 62 patients. The implant was placed in preperitoneal sublay. The friction of the straps, crossing the abdominal wall thanks to a special n…
Application of 5E model for learning Mechanics through inquiry in secondary education
2018
En este trabajo se examina el proceso de resolución de una actividad de indagación sobre las leyes de Newton que consiste en diseñar un montaje con el cuál averiguar qué superficie es la más adecuada para arrastrar cajas de ropa en un almacén. Los participantes son 23 estudiantes de 4º de ESO. Para la toma de datos se recogen sus respuestas escritas relativas al diseño del dispositivo, a la toma de datos, interpretación de resultados y establecimiento de conclusiones. Para el análisis se examinan utilizando como herramienta el modelo de instrucción 5E. Los resultados principales apuntan a ciertas dificultades en los desempeños del alumnado relativos a la elaboración del montaje y a la expli…
Orthodontic brackets friction changes after clinical use : a systematic review
2019
Background To evaluate the bracket-wire friction force after clinical use. Material and methods A systematic search of several electronic databases (PubMed, Embase, Web of Science, Scopus, The Cochrane Library, Lilacs and Google Scholar) without limitations regarding publication year or language, was performed. In-vitro studies analyzing the changes in friction force of orthodontic brackets before/after their clinical use were considered. Risk of Bias was assessed with Downs and Black checklist. All methodological features that could interfere in the results were specifically described. Results Seven studies satisfied the inclusion criteria and were included in the review. All 7 studies rep…
Coupling of heat flux and vortex polarization in superfluid helium
2020
We consider a macroscopic description of the mutual influence between heat flux and vortex polarization in superfluid helium, in which the vortices produce a lateral deviation of the heat flux, and the heat flux produces a lateral drift of vortices. This coupling is a consequence of a microscopic Magnus force and mutual friction force between the vortices and the flow of excitations carrying the heat. We keep track of these effects with simplified macroscopic equations, and we apply them to second sound propagation between rotating concentric cylinders and to spatial distribution of polarization across a rectangular channel with vortices polarized orthogonally to the channel in the presence…
Non-equilibrium thermodynamics analysis of rotating counterflow superfluid turbulence
2010
In two previous papers two evolution equations for the vortex line density $L$, proposed by Vinen, were generalized to rotating superfluid turbulence and compared with each other. Here, the already generalized alternative Vinen equation is extended to the case in which counterflow and rotation are not collinear. Then, the obtained equation is considered from the viewpoint of non-equilibrium thermodynamics. According with this formalism, the compatibility between this evolution equation for $L$ and that one for the velocity of the superfluid component is studied. The compatibility condition requires the presence of a new term dependent on the anisotropy of the tangle, which indicates how the…
Atomistic Simulations of Solid Friction
2002
Friction between two solid bodies in relative sliding motion takes place on a large spectrum of length and time scales: From the nanometer/second scale in an atomic force microscope up to the extremely macroscopic scales of tectonic motion. Despite our familiarity with the effects of friction, fundamental questions remain unanswered. The atomistic origins of well-established phenomenological friction laws are controversial. Many explanations, seemingly well-established, have recently been called into question by new experimental results. Computer simulations have also revealed flaws in previous theoretical approaches and led to new insights into the atomistic processes responsible for frict…