Search results for "Mecànica"
showing 10 items of 25 documents
Nonlinear plasmonic amplification via dissipative soliton-plasmon resonances
2017
In this contribution we introduce a new strategy for the compensation of plasmonic losses based on a recently proposed nonlinear mechanism: the resonant interaction between surface plasmon polaritons and spatial solitons propagating in parallel along a metal/dielectric/Kerr structure. This mechanism naturally leads to the generation of a quasi-particle excitation, the so-called soliplasmon resonance. We analyze the role played by the effective nonlinear coupling inherent to this system and how this can be used to provide a new mechanism of quasi-resonant nonlinear excitation of surface plasmon polaritons. We will pay particular attention to the introduction of asymmetric linear gain in the …
Effect of the upper material of running shoes on muscle mechanical power transfer on lower limbs
2022
This study focuses on determining the effects of the upper material of running shoes on the mechanical power flows of the muscles of the lower limbs during the support phase of running. Two models of running shoes—differentiated only by the upper structure and material—have been used, being randomly assigned to 19 participants. Five measurements of each participant per shoe model were obtained at 3.3 m·s−1 to perform inverse dynamic analysis with the data obtained. Statistically significant differences have been found between the two models for the muscle power flow variables in the ankle, knee and hip joints, as well as at the ends of adjacent segments. The KNIT-upper model (model 2) pres…
Efectos de los soportes plantares sobre la termorregulación de las plantas de los pies durante la carrera
2015
Accésit Congreso SIBB 2015 Existe una gran controversia acerca de si el uso de soportes plantares puede reducir el riesgo de padecer lesiones por sobreuso en corredores. Se ha observado una relación entre las cargas plantares y la temperatura superficial de los pies, por lo que el tipo de soporte plantar podría afectar a la temperatura de la planta del pie. El objetivo del estudio fue, analizar los efectos de los soportes plantares en la temperatura superficial, así como en la simetría térmica, de las plantas de los pies tras la carrera. 12 corredores entrenados realizaron 3 test de 30 minutos de carrera (10 de calentamiento y 20 de prueba al 80% de su Velocidad Aeróbica Máxima) con soporte…
Comparison of lower limb segments kinematics in taekwondo kick. an approach to the proximal to distal motion
2015
Abstract In taekwondo, there is a lack of consensus about how the kick sequence occurs. The aim of this study was to analyse the peak velocity (resultant and value in each plane) of lower limb segments (thigh, shank and foot), and the time to reach this peak velocity in the kicking lower limb during the execution of the roundhouse kick technique. Ten experienced taekwondo athletes (five males and five females; mean age of 25.3 ±5.1 years; mean experience of 12.9 ±5.3 years) participated voluntarily in this study performing consecutive kicking trials to a target located at their sternum height. Measurements for the kinematic analysis were performed using two 3D force plates and an eight came…
Test-Retest Reliability of Task Performance for Golf Swings of Medium- to High-Handicap Players
2022
Background: Golf swing performance in medium- to high-handicap players must be reliably measured to use this variable in both research studies and in applied settings. Nevertheless, there are no studies published on this topic and test–retest evidence is only available for low-handicap players. The aim of this study was to determine the number of attempts necessary to obtain a reliable measurement protocol for swing performance variables in medium- to high-handicap players. Methods: Ten amateur players (55.67 (13.64) years, 78.4 (11.4) kg, 1.75 (7.95) m) took part in a test–retest study in two experimental sessions one week apart. In each one, fifteen swings with a six iron and a driver wer…
Trunk and lower limb muscle activation in linear, circular and spin back kicks
2015
Background and Study Aim: As any martial art, taekwondo can be classified as a specialty that requires high technical skills, such as a fine motor control both in static and dynamic conditions. Practitioners predominantly use kicks with high amplitude in both combat and technique (poomse) modalities. The aim of this study was the knowledge about trunk and lower limb muscle activation according to the type of kick (circular, linear and spin back kick) in the taekwondo technique modality. Material and Methods: Twelve healthy and elite male taekwondo athletes voluntarily participated in this study. Surface electromyography (EMG) during maximal isometric voluntary contractions (MVC) and executi…
Effects of a training program on stable vs unstable surfaces on postural stability.
2019
The training surface can modulate the body's response to training stimuli. The purpose of the article was to determine the influence of two types of training programs on stable/unstable surfaces on postural stability. 20 physically active participants with no history of lower limb injuries were randomly assigned to 3 groups (Control, Unstable Training, Stable Training), and performed supervised training in 16 sessions. Dynamic postural stability and static stability were assessed and tests were performed at baseline after completion of the training and 1, 2 and 4 weeks after the training process. The stable surface training group improved dynamic stability between the pre-test and the two f…
Characterization of gas flow through low-permeability claystone: laboratory experiments and two-phase flow analyses
2014
For the characterization of gas migration through a low-permeability clay host rock for deep underground repositories, a comprehensive understanding of the relevant phenomena of gas and fluid flow through low-permeability clay is required. The National Cooperative for the Disposal of Radioactive Waste (Nagra) in Switzerland has developed a comprehensive programme to characterize gas flow in low-permeability Opalinus Clay through laboratory tests and detailed numerical analyses for developing appropriate constitutive models. Laboratory tests were performed on cores by two different laboratories, the Laboratory for Soil Mechanics at EPFL and the Department of Geotechnical Engineering and Geos…
Mecànica II
2020
El document forma part dels materials docents programats mitjançant l'ajut del Servei de Política Lingüística de la Universitat de València Apunts de l'assignatura de Mecànica II, amb tres temaris principals: Formulació Lagrangiana (part 1), Formulació Hamiltoniana (part 2) i Relativitat Especial (part 3). Notes of the course 'Mecànica II', with three main topics: Lagrangian formulation (part 1), Hamiltonian formulation (part 2) and Special Relativity (part 3).
Mecànica I: notes docents de l'assignatura
2023
El material docent ha estat revistat pel Servei de Política Lingüística de la Universitat de València. Aquestes són les notes de classe emprades al grup de valencià de l'assignatura de Mecànica I impartida durant el segon curs del Grau en Física. El contingut de l'assignatura inclou la mecànica clàssica necessària per a qualsevol estudiant de física.