Propagación de ondas de Rayleigh en medios con grietas

Olivera-Villaseñor, E.; Núñez-Farfán, J.; Flores-Guzmán, Norberto; Carbajal-Romero, Manuel; Rodríguez-Castellanos, Alejandro; Sánchez-Sesma, F. J.

doi:10.1016/j.rimni.2012.08.005

Cited by 3 publications

(2 citation statements)

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“…After adequate training in the use of the registration instrument and the observational instrument, rigor in the coding process was guaranteed [ 23 ] by controlling the quality of the data to be registered with two expert observers in wrestling by calculating intra- and inter- observer agreement, using Cohen’s Kappa coefficient [ 24 ] and calculated using LINCE software [ 5 , 19 , 25 ]. Both concordances were performed with bouts not belonging to the final sample, in a number equivalent to one third of the final sample (n = 42).…”

Section: Methodsmentioning

confidence: 99%

The temporal structure of male freestyle wrestling bouts in 65, 86 and 125 kg categories

et al. 2023

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In freestyle wrestling, how regulatory breaks and micro pauses affect the efforts during combat has been studied very little. The objective of the study was to determine the temporal structure of fights in male freestyle wrestling in the 65, 86 and 125 kg categories. All wrestlers from the categories (n = 115) who competed in the 2019 senior wrestling world championship (Nur-Sultan, Kazakhstan) participated. Using observational methodology, we analyzed all fights (n = 127). We used different statistical techniques: descriptive, normality tests, Kruskall-Wallis, one-way ANOVA and chi-square. The significance level was ρ<0.05. The results show that most fights finish in the last minute (73.5% in 65 kg, 74.5% in 86 kg and 80.6% in 125 kg) and the total fight time is consumed (67.3% in 65 kg, 70.2% in 86 kg and 77.4% in 125 kg). Differences in 18 variables were found when comparing the three weights were found in the temporal and sequential parameters of the combat. When we compare these parameters to the different fight minutes, we find that there are differences in 17 variables in 65 kg, 20 variables in 86 kg and 10 variables in 125 kg. The results define a temporal structure of male freestyle wrestling bouts in the three categories, and therefore, it will be possible to prepare adequate trainings for these athletes. We conclude that in the three weight categories, they wrestle longer standing than while on the ground. There are clear differences between the three categories. In the 125 kg category, the temporal and sequential parameters are more stable throughout the different minutes of the fight, and in 65 and 86 kg, there is an instability. In the three weights, the regulatory break modulates the duration of the pauses and the actions performed by the wrestlers in different fight minutes.

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Section: Methodsmentioning

confidence: 99%

The temporal structure of male freestyle wrestling bouts in 65, 86 and 125 kg categories

et al. 2023

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“…After attending a training course on the use of previously mentioned instruments, two expert evaluators used the Lince program to observe and record the data of the combats. In order to guarantee the thoroughness of the registration process ( Blanco-Villaseñor and Anguera, 2000 ), the quality of the recorded data was controlled by the concordance calculations of intra and interobservers using the Cohen’s kappa coefficient ( Cohen, 1968 ) calculated with LINCE software. The intra-observer concordance was used in previous combats that did not belong to the definitive sample, in an amount that adds up to one third of the final sample (n = 77), reaching a 0.96 kappa value in observer 1 and 0.94 in observer 2.…”

Section: Methodsmentioning

confidence: 99%

Should Blind Judokas and Partially Sighted Judokas Compete Together? A Reflection from the Study of the Temporal Structure of Combat

Gutiérrez-Santiago¹,

Prieto-Lage²,

Paramés-González³

et al. 2023

Journal of Human Kinetics

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The investigation of the temporal structure of Para judo combat according to sport classes or visual categories (B1, B2 and B3) has only been carried out in women. The objectives of the study were to analyze the differences in the temporal structure of combat between the male para-judokas sport classes, and to determine whether the blind judokas and partially sighted judokas should compete together. All para-judokas who competed in the 2018 IBSA Judo World Championships (172 men) participated. Using observational methodology, we analyzed all the combats (<i>n</i>=232). To obtain the results, we used different analysis techniques: descriptive, one-way ANOVA, t-test for independent simples and effect size. The significance level established for the study was <i>ρ</i> ≤ 0.05. The results determine that during the pauses, the time dedicated to the displacement is increased when there is a B1 judoka in the pairing, causing the pauses to be significantly longer. Coaches should take this into account. We conclude that there are differences between the visual categories. B1 judokas have longer pauses, perform more ground fighting sequences and win fewer combats. The competition is not on equal terms. More research is needed in order to know if the new regulations have modified the combat temporality.

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Creep in the Fundamental Frequency and Stability of a Slender Wooden Column of Composite Section

2016

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-Creep is a phenomenon that can occur in wooden structures since wood is a viscoelastic material. Creep may change the purely elastic parameters determined in wood characterization initial tests, as its behavior depends on the rheology of the material, even under a constant stress level. Mathematically, creep can be characterized by models in which the immediate elastic deformation is increased by a viscous deformation, resulting in a temporal function. For this reason, the calculation of the natural frequency of vibration and the stability verification of a slender column should include the reducing effects of stiffness both of axial force and creep. The first one can be considered through the geometrical portion and the second one by the introduction, in the conventional portion, of a variable elasticity modulus over time, obtained in relation to the adopted rheological model. A numerical simulation was performed to evaluate the aspects above, considering a bar compressed by a force at the free end equivalent to 10% of the Euler critical force, plus its own weight, adopting a rheological model with three parameters for the variation of the elasticity modulus. The results show differences of 60% and 50% for the frequency and elasticity modulus, besides defining the exact instant of column collapse in the case of its non-observance.Keywords: Three-parameter model; Vibration; Stability.A FLUÊNCIA NA FREQUÊNCIA FUNDAMENTAL E NA ESTABILIDADE DE UMA COLUNA ESBELTA DE MADEIRA DE SEÇÃO COMPOSTA RESUMO -A fluência é um fenômeno que pode ocorrer em estruturas de madeira por ser esse um material viscoelástico. A fluência pode alterar os parâmetros puramente elásticos determinados nos ensaios iniciais de caracterização da madeira, pois o seu comportamento depende da reologia do material, mesmo com um nível de tensão constante. Matematicamente, a fluência pode ser caracterizada por modelos onde a deformação elástica imediata é acrescida de uma deformação viscosa, resultando em uma função temporal. Por essa razão, o cálculo da frequência natural de vibração e a verificação da estabilidade de uma coluna esbelta devem incluir os efeitos redutores da rigidez tanto da força axial quanto da fluência. O primeiro pode ser considerado por meio da parcela geométrica e o segundo pela introdução, na parcela convencional, de um módulo de elasticidade variável com o tempo, obtido em relação ao modelo reológico adotado. Para avaliar os aspectos mencionados, foi realizada uma simulação numérica, considerando uma peça comprimida por uma força na extremidade livre equivalente a 10% da força crítica de Euler, mais o seu peso próprio, adotando-se um modelo reológico de três parâmetros para a variação do módulo de elasticidade. Os resultados indicaram diferenças de 60% e 50% para a frequência e para o módulo de elasticidade, além de definir o instante exato de colapso da coluna em caso de sua inobservância.Palavras-chave: Modelo de três parâmetros; Vibração; Estabilidade.

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Propagación de ondas de Rayleigh en medios con grietas

Cited by 3 publications

References 22 publications

The temporal structure of male freestyle wrestling bouts in 65, 86 and 125 kg categories

The temporal structure of male freestyle wrestling bouts in 65, 86 and 125 kg categories

Should Blind Judokas and Partially Sighted Judokas Compete Together? A Reflection from the Study of the Temporal Structure of Combat

Creep in the Fundamental Frequency and Stability of a Slender Wooden Column of Composite Section

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