To see the other types of publications on this topic, follow the link: Vertical force.
Dissertations / Theses on the topic 'Vertical force'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Vertical force.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
de, Paula Santana Hugo A. "Relationship of Force Variables to Vertical Jumps Performance." Digital Commons @ East Tennessee State University, 2016. https://dc.etsu.edu/etd/2618.
Full textAbstract:
The isometric mid-thigh pull (IMTP) has been cited often in the scientific literature; however, there is still a lack of agreement as to the ideal body position used during this test, and how body position impacts the relationship between IMTP performance and dynamic performance. Thus, one aim of this dissertation was to compare two different IMTP positions and correlate the kinetic outputs from each position to vertical jump (VJ) performance. Another purpose of this dissertation was analyze which method of data normalization for IMTP force variables best correlates to squat jump (SJ) and countermovement jump (CMJ) performance.
In the first study, subjects presented higher force outputs for an upright position (hip angles 145°, knee 125°) when compared to a bent position (hip angles 125°, knee 125°). However, there were no statistical differences among correlations from the two positions when correlating to VJ performance. Thus, we suggest that the upright position should be the one used for research and monitoring due to higher force values presented.
The second part of this study was to compare correlations from non-normalized and normalized data from the IMTP to SJ and CMJ. Besides non-normalized data, five common methods of normalization were used – subtracting the body mass force, dividing the forces per body mass, allometric scale, scaling by height (Ford’s scale) and scaling by Sinclair coefficient value. In general, higher value correlations were presented with the non-normalized methods for both jumps – SJ and CMJ. Therefore, when using IMTP data to correlate with VJ performance, there is no need to normalize the data.
2
Mihelcic, Carolin Susan. "Hydrodynamic force coefficients of a vertical circular cylinder." Thesis, University of British Columbia, 1989. http://hdl.handle.net/2429/27939.
Full textAbstract:
The problem addressed in this thesis is that of the behaviour of large offshore structures subjected to ice and earthquake loading.
The theoretical formulation of the fluid force and associated added mass and damping coefficients acting on an isolated vertical surface-piercing rigid circular cylinder which is excited by sinusoidal unidirectional ground motions is presented. The closed-form solution is first developed on the basis of potential flow theory for arbitrary values of excitation frequency and, in addition, its asymptotic form for high frequencies is considered. The latter is found to be accurate in predicting the high-frequency added mass only for high structure radius-to-water depth ratios and the high-frequency damping for all radius-to-depth ratios. A computer method for numerical evaluation of the force coefficients is devised and theoretical results for different values of radius-to-depth ratios are thereby generated.
An experimental study has been conducted in the Earthquake Engineering Laboratory of the Department of Civil Engineering at the University of British Columbia to verify the theoretical results obtained for the vertical distribution of the force coefficients of a model cylinder which satisfies the large body regime of fluid-structure behaviour for which effects due to fluid viscosity are negligible. Owing to unanticipated technical problems, the current study is unsuccessful and data recorded in the sinusoidal tests are unrealistic, although the calculated coefficients appear to be independent of base displacement (an observation which indicates that viscous effects were insignificant during testing). Nevertheless, values of total force coefficients which were obtained experimentally for a similar model in a previous investigation are found to agree very well with the corresponding theoretical results for frequencies of up to 6 Hz.
It is concluded that the theoretical formulation provided for the hydrodynamic force coefficients of a vertical surface-piercing circular cylinder subjected to horizontal sinusoidal base motions of arbitrary frequency may be used to accurately predict the total added mass and damping of real structures satisfying the conditions imposed by the theory.Applied Science, Faculty of
Civil Engineering, Department of
Graduate
3
Arnold, Graham Phillip. "Development of a tri-axial (vertical and shear) force measurement foot platform." Thesis, University of Dundee, 2010. https://discovery.dundee.ac.uk/en/studentTheses/544efdc8-a1db-443e-a3e6-315e3f32df00.
Full textAbstract:
Plantar foot stress causing foot ulceration is a diabetic complication causing major economic burden throughout the world. It has long been thought that shear stresses on the plantar surface of the foot are a major contributing factor to the formation of these ulcers. Although there are many instruments available that measure the vertical foot pressure (vertical forces), there are currently no commercially available instruments to measure the horizontal or shear forces. It is the aim of this project to develop a platform instrument capable of measuring the three dimensional forces (i.e. vertical pressure and shear forces) across the plantar surface of the foot.
4
Sole, Christopher J. "Analysis of Countermovement Vertical Jump Force-Time Curve Phase Characteristics in Athletes." Digital Commons @ East Tennessee State University, 2015. https://dc.etsu.edu/etd/2549.
Full textAbstract:
The purposes of this dissertation were to examine the phase characteristics of the countermovement jump force-time curve between athletes based on jumping ability, examine the influence of maximal muscular strength on the countermovement jump force-time curve phase characteristics of athletes, and to examine the behavior of the countermovement jump force-time curve phase characteristics over the course of a training process in athletes of varying strength levels. The following are the major findings of these dissertations. The analysis of athletes by jumping ability suggested that proficient jumpers are associated with greater relative phase magnitude and phase impulse throughout the phases contained in the positive impulse of the countermovement jump force-time curve. Additionally, phase duration was not found to differ between athletes based on jumping ability or between male and female athletes. The analysis of athletes based on maximal muscular strength suggested that only unweighted phase duration differs between strong and less-strong athletes. Interestingly, in both investigations based on jumping ability and maximal strength indicated the relative shape of the stretching phase representing the rise in positive force was related to an athlete’s jumping ability (jump height). The results of the longitudinal analysis of countermovement jump force-time phase characteristics identified that these variables can be frequently assessed throughout a training process to provide information of regarding an athlete performance state. Furthermore, based on the contrasting behaviors of many of the countermovement jump force-time curve phase characteristics over time, an athlete’s level of muscular strength may influence how these characteristics are expressed in the context of a training process.
5
Leaf, Timothy D. "Investigation of the vertical distribution of seismic forces in the static force and equivalent lateral force procedures for seismic design of multistory buildings /." Available to subscribers only, 2006. http://proquest.umi.com/pqdweb?did=1136093311&sid=1&Fmt=2&clientId=1509&RQT=309&VName=PQD.
Full text
6
Scalley, Timothy Brian. "Vertical ground reaction force estimation using position data measured from a markerless motion capture system." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1345557063.
Full text
7
Pagnacco, Guido. "Vertical ground reaction force in the assessment of human postural balance /." The Ohio State University, 2000. http://rave.ohiolink.edu/etdc/view?acc_num=osu1488203857248106.
Full text
8
Shi, Jun-Mei, Horst-Michael Prasser, and Ulrich Rohde. "Turbulent dispersion of bubbles in poly-dispersed gas-liquid flows in a vertical pipe." Forschungszentrum Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-28046.
Full textAbstract:
Turbulence dispersion is a phenomenon of practical importance in many multiphase flow systems. It has a strong effect on the distribution of the dispersed phase. Physically, this phenomenon is a result of interactions between individual particles of the dispersed phase and the continuous phase turbulence eddies. In a Lagrangian simulation, a particle-eddy interaction sub-model can be introduced and the effect of turbulence dispersion is automatically accounted for during particle tracking. Nevertheless, tracking of particleturbulence interaction is extremely expensive for the small time steps required. For this reason, the Lagrangian method is restricted to small-scale dilute flow problems. In contrast, the Eulerian approach based on the continuum modeling of the dispersed phase is more efficient for densely laden flows. In the Eulerian frame, the effect of turbulence dispersion appears as a turbulent diffusion term in the scalar transport equations and the so-called turbulent dispersion force in the momentum equations. The former vanishes if the Favre (mass-weighted) averaged velocity is adopted for the transport equation system. The latter is actually the total account of the turbulence effect on the interfacial forces. In many cases, only the fluctuating effect of the drag force is important. Therefore, many models available in the literature only consider the drag contribution. A new, more general derivation of the FAD (Favre Averaged Drag) model in the multi-fluid modeling framework is presented and validated in this report.
9
Shi, Jun-Mei, Horst-Michael Prasser, and Ulrich Rohde. "Turbulent dispersion of bubbles in poly-dispersed gas-liquid flows in a vertical pipe." Forschungszentrum Dresden-Rossendorf, 2007. https://hzdr.qucosa.de/id/qucosa%3A21631.
Full textAbstract:
Turbulence dispersion is a phenomenon of practical importance in many multiphase flow systems. It has a strong effect on the distribution of the dispersed phase. Physically, this phenomenon is a result of interactions between individual particles of the dispersed phase and the continuous phase turbulence eddies. In a Lagrangian simulation, a particle-eddy interaction sub-model can be introduced and the effect of turbulence dispersion is automatically accounted for during particle tracking. Nevertheless, tracking of particleturbulence interaction is extremely expensive for the small time steps required. For this reason, the Lagrangian method is restricted to small-scale dilute flow problems. In contrast, the Eulerian approach based on the continuum modeling of the dispersed phase is more efficient for densely laden flows. In the Eulerian frame, the effect of turbulence dispersion appears as a turbulent diffusion term in the scalar transport equations and the so-called turbulent dispersion force in the momentum equations. The former vanishes if the Favre (mass-weighted) averaged velocity is adopted for the transport equation system. The latter is actually the total account of the turbulence effect on the interfacial forces. In many cases, only the fluctuating effect of the drag force is important. Therefore, many models available in the literature only consider the drag contribution. A new, more general derivation of the FAD (Favre Averaged Drag) model in the multi-fluid modeling framework is presented and validated in this report.
10
Saywell, Nicola Lesley. "Age dependent differences in attenuation of vertical ground reaction force during a step descent." AUT University, 2009. http://hdl.handle.net/10292/887.
Full textAbstract:
Aim: The aim of this study was to investigate the differences between older and younger adults in the attenuation of impact during descent from a step. Strategies that have been implicated in reducing either the magnitude of vertical ground reaction force (vertical GRF) or the time taken to reach the maximum vertical GRF in the stepping leg were explored. Study Design: The study was an experimental, laboratory based, repeated measures design. Participants: Twenty participants took part in this exploratory study. Ten in the older group of 60-80 years, mean 65.3 (SD 5) years and ten in the younger age group of 20-30 years, mean 22.8 (SD 2.5) years. Main Measures: The vertical GRF and the time taken to reach maximum vertical GRF were measured to ascertain impact during step descent. Electromyography and kinematic variables were measured to determine the effect they may have on the impact. The variables measured were the maximum joint range of motion of the hip and knee during early stance in step descent. Surface electromyography from four lower limb muscles was recorded to ascertain the magnitude of muscle activity at impact. The relationship in an antero-posterior direction of the upper body and stepping leg at initial contact (IC) was also investigated. Results: There was a significant difference in both the amount of knee flexion and the amount of activity of the vastus lateralis muscle during impact between older and younger adults. Older adults had significantly less knee flexion during a step descent activity than younger adults (F(1,18)=5.48; p=.031).Older adults had significantly more vastus lateralis activity during a step descent activity than younger adults (F(1,18)=5.21; p=.035). Conclusions: Older and younger adults use different strategies in both muscle activation and joint range of motion around the knee of the leading leg during the step descent. Older adults used more vastus lateralis activity perhaps to increase stiffness in the knee, leading to a reduction in range of motion at impact. Although no change in vertical GRF was detected in this study, both of these strategies have the potential to increase the impact of a step and therefore cause jarring and possible damage. This study recruited healthy active older adults and differences in impact may be observed in an older or less active population, or in those with joint pathology such as osteoarthritis.
11
Berardo-Cates, Alexander T. "Using an IMU for ground reaction force estimation during a vertical jump task." Thesis, California State University, Long Beach, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10167505.
Full textAbstract:
The purpose of this study was to determine if a single inertial measurement unit (IMU) could be used to estimate the vertical ground reaction force (vGRF) of a vertical jump. To do this 16 college-age participants (8 female, 8 male) preformed three counter movement jumps, three drop jumps, and three squat jumps. All jumps were simultaneously recorded with a force plate (1250 Hz) and an IMU (128 Hz) placed on the sacral-L5 junction. The peak rate of force development, reactive strength index, jump impulse, jump height determined from impulse (himp), jump height determined from flight time, and peak force were measured using both the force plate and IMU. There was a significant difference between measuring devices for all dependent variables (p < 0.05) except the himp (p = 0.341). In conclusion, this study does not provide a means of accurately estimating vGRF using an IMU.
12
Kraska, Jenna Marie. "The Relationship between Isometric Force Characteristics and Vertical Jump Height under Various Loading Conditions." Digital Commons @ East Tennessee State University, 2008. https://dc.etsu.edu/etd/1965.
Full textAbstract:
Purpose: to examine the relationship between isometric force characteristics (IF) and vertical jump height under various loading conditions. Sixty-three collegiate athletes participated in this investigation. Athletes performed static jump (SJ) and countermovement jumps (CMJ) with 0 and 20kg, and isometric mid-thigh pulls on a force plate. Force-time curve analysis was conducted for each isometric pull and jump to determine force related characteristics. Jump height (JH) was derived from flight time. Isometric forces were normalized using allometric scaling: absolute force/ (body mass(kg)0.67)= IPFa. Results: There was a strong positive correlation between isometric peak force and isometric rate of force development (IRFD). Stronger athletes had smaller decrements in jump height with additional loading. Conclusion: The ability to produce higher peak and instantaneous forces and IRFD is related to JH and smaller differences between weighted and unweighted jumps. A weighted jump may be a practical method of assessing relative strength levels.
13
Takagi, S., H. Sasaki, M. Shikida, and K. Sato. "Electrostatic Latch Mechanism for Handling Projection on Arrayed Vertical Motion System." IEEE, 2007. http://hdl.handle.net/2237/9556.
Full text
14
Pereira, Sandra São Thiago da Costa [UNESP]. "Estudo comparativo de um salto vertical praticado por indivíduos na água e no solo." Universidade Estadual Paulista (UNESP), 2009. http://hdl.handle.net/11449/97087.
Full textAbstract:
Made available in DSpace on 2014-06-11T19:28:34Z (GMT). No. of bitstreams: 0
Previous issue date: 2009-01-26Bitstream added on 2014-06-13T19:26:51Z : No. of bitstreams: 1
pereira_sstc_me_guara.pdf: 3610434 bytes, checksum: da234218018e1309611898e259e36014 (MD5)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
As atividades realizadas em meio aquático sofrem interferência das propriedades físicas peculiares ao mesmo. O salto vertical é uma habilidade esportiva muito utilizada em programas de reabilitação, principalmente em trabalhos de pliometria. O objetivo deste estudo foi pesquisar as forças envolvidas no salto vertical praticado em ambiente aquático e terrestre e as interdependências entre as variáveis cinéticas e cinemáticas dos mesmos. Para tal foi utilizada uma amostra composta por dez sujeitos, todos do sexo feminino, com idade média de 11,6 ± 1,35, praticantes de ginástica rítmica. Os sujeitos realizaram uma série de três saltos com contra movimento, consecutivos, sobre plataforma de força no solo, repetindo o mesmo procedimento dentro d’água. Para realização do experimento foi utilizada a técnica de cinemetria para mensuração de ângulo de flexão de joelhos e altura do salto e uma plataforma de força para mensuração das forças de reação vertical do solo. Os resultados foram analisados através da correlação de Pearson, com nível de significância de 5%. Através dos resultados obtidos observou-se que no salto executado em ambiente aquático a altura atingida, velocidade média e tempo de vôo foram maiores e a força de impacto em membros inferiores reduzida, comparados com os resultados obtidos no solo. As correlações foram evidentes entre altura do salto e velocidade de saída, em ambos ambientes. O presente trabalho deve servir como base para a elaboração de programas de treinamento envolvendo o salto, em meio aquático e terrestre, como em atividades de pliometria. Novas pesquisas devem ser realizadas, utilizando uma população praticante de modalidade esportiva que tenha o salto vertical como ação primordial para o bom desempenho na execução da mesma.
The activities carried out in the aquatic environment suffer interference from physical properties peculiar to it. The vertical jump is a sporting skill widely used in rehabilitation programs, especially in studies of plyometric. The aim of this study was to investigate the forces involved in the vertical jump practiced in aquatic and terrestrial environment and the interdependence of the kinetic and kinematic variables of the same. For this purpose we used a sample consisting of ten subjects, all female, with an average age of 11.6 ± 1.35, practicing rhythmic gymnastics. The subjects performed a series of three consecutive counter movement jumps on force platform on the ground, repeating the same procedure in the water. To conduct the experiment was used the technique of kinemetry measuring the angle of the knees push-up and height of the jump and a platform for measuring the strength of the forces of ground vertical reaction. The results were analyzed by the Pearson’s correlation, with a significance level of 5%. The results obtained showed that the jump in running time to reach the aquatic environment, average speed and time of flight were higher and the force of impact on lower limbs, compared with the results in the ground. This work should serve as basis for the development of training programs involving the jump in water and ground, as in activities of plyometric. New research should be carried out using a method of population practicing sports that has the vertical jump as a primary action for the good performance in implementing the same.
15
Lindblad, Paulina, and Filip Norberg. "Jämförelse av metoder för beräkning av höjd vid vertikala hopp." Thesis, Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-42338.
Full textAbstract:
The purpose of this project was to explore the possibility of using the accelerometer in a mobile device to measure acceleration instead of professional laboratory equipment. Five subjects performed ten vertical jumps each. The equipment used for the purpose of this project was a mobile device, force plate and a motion capture system, of which the last one mentioned was used as a reference for comparison against the others. The data from the mobile device was split into two groups of datasets, where the first one was the nominal acceleration from the raw data and the second one the acceleration when the phones orientation was taken into consideration. The height was calculated by using the double summation, take-off velocity and flight-time. All the data was compiled where the mean deviation, standard deviation, R-value and R-Squared was calculated for each method. The take-off velocity was later used as the final method to give it a fair and equal comparison. The result showed that the force plate was significantly better and more reliable than the mobile device. When comparing the different datasets from the phone, the orientation adapted data performed better than the raw data. The conclusion made from this project was that the force plate is still significantly better than the mobile device regardless of the type of data, but the orientation adapted data demonstrates a result in the right direction.
16
Kraska, Jenna M., Michael W. Ramsey, G. Gregory Haff, Nate Fethke, Anna M. Kinser, William A. Sands, Keith Painter, Margaret E. Stone, and Michael H. Stone. "Relationship Between Isometric Force Characteristics and the Difference in Un-weighted and Weighted Vertical Jump Height." Digital Commons @ East Tennessee State University, 2008. https://dc.etsu.edu/etsu-works/4093.
Full text
17
Standifird, Tyler W. "Lower Extremity Joint Moments During the Active Peak Vertical Ground Reaction Force in Three Different Running Conditions." BYU ScholarsArchive, 2012. https://scholarsarchive.byu.edu/etd/2982.
Full textAbstract:
The purpose of this study was to compare joint moments during the active peak vertical ground reaction force (PVGRF) when running in three conditions. Twenty-five subjects, sixteen male and nine female, were measured using 3-dimensional motion analysis while running barefoot, in Vibram FiveFingers® (VF®) minimalist running shoes and in traditional running shoes at a 7-minute-mile pace (3.84 m/s). Joint moment differences were calculated and compared using a mixed model analysis of variance. Results showed the VF® was effective at mimicking both the kinetic and kinematic attributes of barefoot running. The only significant difference found when comparing barefoot and VF® running was in the ankle angle (p < .005). All other variables in the lower extremity were the same for the two conditions. Though the subjects in our study had no previous experience with VF® (or barefoot) running they were able to closely mimic barefoot running upon initial running trials. Joint moments at the ankle were higher for barefoot and VF® running (p < .001) when compared with shod running. This may potentially lead to a greater risk of injury at the ankle joint when running barefoot or in VF®. The hip joint moments were only different when comparing the barefoot condition to the shod condition (p=.002), with the barefoot condition higher than shod running. The knee joint moment was smaller during the VF® and barefoot conditions when compared with shod running (p < .001) and may lead to a decrease in injury rates at the knee. Though a reduction in moments of the lower extremity may lead to a decrease of injury at the corresponding joint, it is important to consider the adaptations that take place as a result of varying stresses. According to Wolff's law, bone and surrounding tissue will adapt to the loads it is placed under. Taking this into consideration, it is important to remember that lower moments may lead to weaker bones and surrounding tissues and without compensation for these reduced loads, injury rates may remain the same over time.
18
Pereira, Sandra São Thiago da Costa. "Estudo comparativo de um salto vertical praticado por indivíduos na água e no solo /." Guaratinguetá : [s.n.], 2009. http://hdl.handle.net/11449/97087.
Full textAbstract:
Orientador: João Alberto de OliveiraBanca: Tamotsu Hirata
Banca: Luiz Alberto Batista
Resumo: As atividades realizadas em meio aquático sofrem interferência das propriedades físicas peculiares ao mesmo. O salto vertical é uma habilidade esportiva muito utilizada em programas de reabilitação, principalmente em trabalhos de pliometria. O objetivo deste estudo foi pesquisar as forças envolvidas no salto vertical praticado em ambiente aquático e terrestre e as interdependências entre as variáveis cinéticas e cinemáticas dos mesmos. Para tal foi utilizada uma amostra composta por dez sujeitos, todos do sexo feminino, com idade média de 11,6 ± 1,35, praticantes de ginástica rítmica. Os sujeitos realizaram uma série de três saltos com contra movimento, consecutivos, sobre plataforma de força no solo, repetindo o mesmo procedimento dentro d'água. Para realização do experimento foi utilizada a técnica de cinemetria para mensuração de ângulo de flexão de joelhos e altura do salto e uma plataforma de força para mensuração das forças de reação vertical do solo. Os resultados foram analisados através da correlação de Pearson, com nível de significância de 5%. Através dos resultados obtidos observou-se que no salto executado em ambiente aquático a altura atingida, velocidade média e tempo de vôo foram maiores e a força de impacto em membros inferiores reduzida, comparados com os resultados obtidos no solo. As correlações foram evidentes entre altura do salto e velocidade de saída, em ambos ambientes. O presente trabalho deve servir como base para a elaboração de programas de treinamento envolvendo o salto, em meio aquático e terrestre, como em atividades de pliometria. Novas pesquisas devem ser realizadas, utilizando uma população praticante de modalidade esportiva que tenha o salto vertical como ação primordial para o bom desempenho na execução da mesma.
Abstract: The activities carried out in the aquatic environment suffer interference from physical properties peculiar to it. The vertical jump is a sporting skill widely used in rehabilitation programs, especially in studies of plyometric. The aim of this study was to investigate the forces involved in the vertical jump practiced in aquatic and terrestrial environment and the interdependence of the kinetic and kinematic variables of the same. For this purpose we used a sample consisting of ten subjects, all female, with an average age of 11.6 ± 1.35, practicing rhythmic gymnastics. The subjects performed a series of three consecutive counter movement jumps on force platform on the ground, repeating the same procedure in the water. To conduct the experiment was used the technique of kinemetry measuring the angle of the knees push-up and height of the jump and a platform for measuring the strength of the forces of ground vertical reaction. The results were analyzed by the Pearson's correlation, with a significance level of 5%. The results obtained showed that the jump in running time to reach the aquatic environment, average speed and time of flight were higher and the force of impact on lower limbs, compared with the results in the ground. This work should serve as basis for the development of training programs involving the jump in water and ground, as in activities of plyometric. New research should be carried out using a method of population practicing sports that has the vertical jump as a primary action for the good performance in implementing the same.
Mestre
19
Kinser, Ann Marie. "Vibration and Stretching Effects on Flexibility and Explosive Strength in Gymnasts." Digital Commons @ East Tennessee State University, 2007. https://dc.etsu.edu/etd/2071.
Full textAbstract:
The purpose of this study was to determine the acute effects of stretching and local vibration on flexibility and explosive strength in competitive female gymnasts. Flexibility was measured in the forward-split position and jump characteristics were recorded using a force plate. Analysis included flight time (FT), jump height (JH), peak force (PF), instantaneous forces, and rates of force development (RFDs). Randomly assigned and counterbalanced groups were: simultaneous vibration-stretching (VS) (n=22), stretching-only (n=7), and vibration-only (n=8). VS showed statistically greater measures of flexibility in both the right and left leg, favored and non-favored legs pre- versus post-treatment. Vibration-only group resulted in statistically greater right forward-split flexibility and non-favored leg flexibility. There were no statistical differences in JH, FT, PF, instantaneous forces, or RFDs in the VS, stretching-only, and vibration-only groups' pre- versus post-treatment tests. The conclusion was simultaneous vibration-stretching greatly increased flexibility while not altering explosive strength.
20
Alkhatib, Rami. "Human locomotion analysis, classification and modeling of normal and pathological vertical ground reaction force signals in elderly." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSES029/document.
Full textAbstract:
La marche est définie par des séquences de gestes cycliques et répétées. Il a été déjà montré que la vitesse et la variabilité de ces séquences peuvent révéler des aptitudes ou des défaillances motrices. L’originalité de ce travail est alors d’analyser et de caractériser les foulées de sujets âgés à partir des signaux de pression issus de semelles instrumentées lors de la marche, au moyen d’outils de traitement du signal. Une étude préliminaire, sur les signaux de pression générés lors de la marche, nous a permis de mettre en évidence le caractère cyclo-stationnaire de ces signaux. Ces paramètres sont testées sur une population de 47 sujets. Tout d'abord, nous avons commencé par un prétraitement des signaux et nous avons montré dans la première de cette thèse que le filtrage peut éliminer une partie vitale du signal. C’est pourquoi un filtre adaptatif basé sur la décomposition en mode empirique a été conçu. Les points de retournement ont été filtrés ensuite en utilisant une technique temps-fréquence appelée «synochronosqueezing». Nous avons également montré que le contenu des signaux de force de marche est fortement affecté par des paramètres inquantifiables tels que les tâches cognitives qui les rendent difficiles à normaliser. C’est pourquoi les paramètres extraits de nos signaux sont tous dérivées par une comparaison inter-sujet. Par exemple, nous avons assimilé la différence dans la répartition de poids entre les pieds. Il est également recommandé dans ce travail de choisir le centre des capteurs plutôt que de compter sur la somme des forces issues du réseau de capteurs pour la classification. Ensuite, on a montré que l’hypothèse de la marche équilibrée et déséquilibrée peut améliorer les résultats de la classification. Le potentiel de cette hypothèse est montré à l'aide de la répartition du poids ainsi que le produit de l'âge × vitesse dans le premier classificateur et la corrélation dans le second classificateur. Une simulation de la série temporelle de VGRF basé sur une version modifiée du modèle de Markov non stationnaire, du premier ordre est ensuite dérivée. Ce modèle prédit les allures chez les sujets normaux et suffisamment pour les allures des sujets de Parkinson. On a trouvé que les trois modes: temps, fréquence et espace sont très utiles pour l’analyse des signaux de force, c’est pourquoi l’analyse de facteurs parallèles est introduite comme étant une méthode de tenseur qui peut être utilisée dans le futurWalking is defined as sequences of repetitive cyclic gestures. It was already shown that the speed and the variability of these sequences can reveal abilities or motorskill failures. The originality of this work is to analyze and characterize the steps of elderly persons by using pressure signals. In a preliminary study, we showed that pressure signals are characterized by cyclostationarity. In this study, we intend to exploit the nonstationarity of the signals in a search for new indicators that can help in gait signal classification between normal and Parkinson subjects in the elderly population. These parameters are tested on a population of 47 subjects. First, we started with preprocessing the vertical ground reaction force (VGRF) signals and showed in this first part of the thesis that filtering can remove a vital part of the signal. That is why an adaptive filter based on empirical mode decomposition (EMD) was built. Turning points are filtered using synochronosqueezing of time-frequency representations of the signal. We also showed that the content of gait force signals is highly affected by unquantifiable parameter such as cognitive tasks which make them hard to be normalized. That is why features being extracted are derived from inter-subject comparison. For example we equated the difference in the load distribution between feet. It is also recommended in this work to choose the mid-sensor rather than relying on summation of forces from array of sensors for classification purposes. A hypothesis of balanced and unbalanced gait is verified to be potential in improving the classification accuracy. The power of this hypothesis is shown by using the load distribution and Age×Speed in the first classifier and the correlation in the second classifier. A time series simulation of VGRF based on a modified version of nonstationary- Markov model of first order is derived. This model successfully predict gaits in normal subjects and fairly did in Parkinson’s gait. We found out that the three modes: time, frequency and space are helpful in analyzing force signals that is why parallel factor analysis is introduced as a tensor method to be used in a future work
21
Leconte, Sylvain. "Étude du transport vertical dans les hétérostructures à base de GaN pour les applications opto- et micro-électronique." Grenoble 1, 2009. http://www.theses.fr/2009GRE10039.
Full textAbstract:
L'objet de ce travail est d'étudier les propriétés de transport électronique le long de l'axe de croissance dans des hétérostructures à base de semi-conducteurs nitrures. La compréhension de ces phénomènes est de première importance dans l'amélioration du design de composants unipolaires, tels que les diodes tunnel résonantes, les photodétecteurs infrarouges à puits quantiques ou encore les lasers à cascade quantiques. Ce travail débute sur l'étude d'échantillons de GaN avec une barrière simple d'AlN ou d'AlGaN dont la croissance est effectuée par épitaxie par jets moléculaires à base de plasma d'azote. J'ai étudié les effets du champ électrique interne généré par la barrière et le rôle des dislocations. Pour ce faire, j'ai mis au point des techniques originales, comme les mesures de photoluminescence en tension ou la technique de microscopie à force atomique conductrice. La première a permis d'observer la répartition du champ électrique dans la structure sous l'effet d'un champ électrique externe, confirmant les résultats de simulation, la deuxième a mis en évidence le rôle des dislocations vis pures dans les courants de fuite. La densité de dislocations à l'origine de fuites est cinquante fois plus faible que la densité totale de dislocations dans le matériau, ce qui laisse envisager la possibilité de réaliser des composants exempts de défauts conducteurs en réduisant la taille du motif à des dimensions de l'ordre du micron. Ensuite, je décris les résultats de l'étude des échantillons à double barrière d'AlN dans du GaN. J'ai pu observer une résistance différentielle négative autour de 1,5 V sur des échantillons avec un puits de GaN de 0,5 nm. Ce pic n'est observé que lors de la première mesure en tension, et peut être récupéré en appliquant une tension négative de l'ordre de -4 V. Pour les échantillons avec un puits plus large, on relève aussi deux niveaux de courant, le premier étant attribué à des fuites à travers les dislocations et l'autre pourrait être lié à un courant tunnel non résonant et assisté par les défauts à travers la structure. Pour terminer, je présente deux types de composants utilisant les propriétés de transport vertical dans les hétérostructures nitrures : les modulateurs électro-optiques et les photodétecteur infrarouge à puits quantiques. Le bon fonctionnement des modulateurs réalisés révèle la possibilité de transfert tunnel de charges à travers une barrière d'AlN. Quand aux photodétecteurs, leur fonctionnement par effet photovoltaïque a été démontré, cependant des problèmes apparaissent lorsque l'on applique une tension aux bornes de la structure. Des études supplémentaires sont requises pour le développement de photodétecteurs infrarouge photoconducteursThe aim of this work is to study the vertical electronic transport along the growth axis in AlN/GaN heterostructures. The comprehension of this phenomenon is of first importance in order to improve the design of unipolar devices such as resonant tunneling diodes, quantum well infrared photodetector or quantum cascade lasers. This work begins with the study of GaN samples with a single AlN or AlGaN barrier, where the growth is performed by plasma-assisted molecular-beam epitaxy. I have analysed the effect of the internal electric field generated by the barrier, and the role of the dislocations. To do so, I have developed some original experiments, such as photomuminescence spectroscopy under bias and conductive atomic force microscopy. Optical measurements provided information on the repartition of the internal electric field in the structure when we applied an external electric field, which confirmed the results obtained by simulations. Local conduction characterization revealed that pure screw dislocations are the main source of leakage current. The density of this kind of dislocations is fifty times smaller than the total dislocation density in the material, which raises the possibility to design components without conductive defects by scaling the patterns down to the micrometer scale. In a second stage, I described the results of the study of samples with a double AlN barrier in a GaN matrix. Samples with a GaN quantum well width of 0. 5 nm display a negative differential resistance around 1. 5 V. This feature is observed only during the first measurement, and can be recovered only by applying a negative bias of about -4 V. In the samples with a wider well, we also observe two current states, the first one being attributed to leakage through dislocations and the second one to a non-resonnant tunneling current assited by defects. Finally, I present two kinds of devices which use the vertical electronic transport in nitride heterostructures: charge transfer electro-optical modulators and quntum well infrared photodetectors. The good performance of the modulators confirms the feasibility of tunnel transport through an AlN barrier. For the quantum well photodetectors, it was demonstrated that they can operate in the photovoltaïc mode, but problems appear under bias. Further studies are required for the developpement of photoconductive infrared photodetectors
22
Kraska, Jenna M., Michael W. Ramsey, G. Gregory Haff, Nate Fethke, William A. Sands, Margaret E. Stone, and Michael H. Stone. "Relationship between Strength Characteristics and Unweighted and Weighted Vertical Jump Height." Digital Commons @ East Tennessee State University, 2009. https://dc.etsu.edu/etsu-works/4129.
Full textAbstract:
Purpose: To investigate the relationship between maximum strength and differences in jump height during weighted and unweighted (body weight) static (SJ) and countermovement jumps (CMJ).
Methods: Sixty-three collegiate athletes (mean ± SD; age= 19.9 ± 1.3 y; body mass = 72.9 ± 19.6 kg; height = 172.8 ± 7.7 cm) performed two trials of the SJ and CMJ with 0 kg and 20 kg on a force plate; and two trials of mid-thigh isometric clean pulls in a custom rack over a force plate (1000-Hz sampling). Jump height (JH) was calculated from fight time. Force-time curve analyses determined the following: isometric peak force (IPF), isometric force (IF) at 50, 90, and 250 ms, and isometric rates of force development (IRFD). Absolute and allometric scaled forces, [absolute force/(body mass0.67)], were used in correlations.
Results: IPF, IRFD, F50a, F50, F90, and F250 showed moderate/strong correlations with SJ and CMJ height percent decrease from 0 to 20 kg. IPFa and F250a showed weak/moderate correlations with percent height decrease. Comparing strongest (n = 6) to weakest (n = 6): t tests revealed that stronger athletes (IPFa) performed superior to weaker athletes.
Conclusion: Data indicate the ability to produce higher peak and instantaneous forces and IRFD is related to JH and to smaller differences between weighted and unweighted jump heights. Stronger athletes jump higher and show smaller decrements in JH with load. A weighted jump may be a practical method of assessing relative strength levels.
23
Hinkel-Lipsker, Jacob Wesley. "EFFECT OF WARM-UP ACTIVITY ON VERTICAL GROUND REACTION FORCES IN BASKETBALL PLAYERS DURING DROP JUMP LANDINGS." DigitalCommons@CalPoly, 2013. https://digitalcommons.calpoly.edu/theses/1088.
Full textAbstract:
ABSTRACT
Effect of Warm-Up Activity on Vertical Ground Reaction Forces in Basketball Players During Drop Jump Landings
Jacob Hinkel-Lipsker
Purpose: The purpose of this study was to examine the effect of certain warm-up activities on vertical ground reaction forces (GRFv) during a drop jump landing. Methods: Eight women and twelve men (mean age 22.6 ± 1.82 years) completed three warm-up activities on three separate days in a counterbalanced order: a passive stretching warm-up, a dynamic warm-up, and a no warm-up control. After completing each activity, participants were asked to perform eight drop jump landings on a force platform. GRFv data was sampled at 1000 Hz during each landing, and the variables analyzed were: peak forefoot and rearfoot magnitude, forefoot and rearfoot rate of loading, and impulse. Results: The dynamic warm-up had significantly greater values (p < 0.05) for forefoot peak magnitude, rearfoot peak magnitude, and forefoot rate of loading compared to the passive stretching and control conditions. Also, there were no significant differences among all activities for rearfoot rate of loading and impulse. Conclusions: The significantly greater values for forefoot peak magnitude, rearfoot peak magnitude, and forefoot rate of loading that the dynamic warm-up produced indicates that this activity may be effective in increasing muscular stiffness in the lower limbs. The failure of the passive stretching warm-up to reach significance indicates that this activity may not be effective in decreasing lower extremity muscular stiffness.
24
Dyachuk, Eduard. "Aerodynamics of Vertical Axis Wind Turbines : Development of Simulation Tools and Experiments." Doctoral thesis, Uppsala universitet, Elektricitetslära, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-260573.
Full textAbstract:
This thesis combines measurements with the development of simulation tools for vertical axis wind turbines (VAWT). Numerical models of aerodynamic blade forces are developed and validated against experiments. The studies were made on VAWTs which were operated at open sites. Significant progress within the modeling of aerodynamics of VAWTs has been achieved by the development of new simulation tools and by conducting experimental studies. An existing dynamic stall model was investigated and further modified for the conditions of the VAWT operation. This model was coupled with a streamtube model and assessed against blade force measurements from a VAWT with curved blades, operated by Sandia National Laboratories. The comparison has shown that the accuracy of the streamtube model has been improved compared to its previous versions. The dynamic stall model was further modified by coupling it with a free vortex model. The new model has become less dependent on empirical constants and has shown an improved accuracy. Unique blade force measurements on a 12 kW VAWT were conducted. The turbine was operated north of Uppsala. Load cells were used to measure the forces on the turbine. A comprehensive analysis of the measurement accuracy has been performed and the major error sources have been identified. The measured aerodynamic normal force has been presented and analyzed for a wide range of operational conditions including dynamic stall, nominal operation and the region of high flow expansion. The improved vortex model has been validated against the data from the new measurements. The model agrees quite well with the experiments for the regions of nominal operation and high flow expansion. Although it does not reproduce all measurements in great detail, it is suggested that the presented vortex model can be used for preliminary estimations of blade forces due to its high computational speed and reasonable accuracy.
25
Mizuguchi, Satoshi, William A. Sands, H. S. Lamont, and Michael H. Stone. "Identification of Force-Time Curve Characteristics That Contribute to Net Impulse in Vertical Jumping – a Multiple Regression Analysis Approach." Digital Commons @ East Tennessee State University, 2012. https://dc.etsu.edu/etsu-works/4548.
Full text
26
Rivai, Kathryn. "Data analysis of experimental test results of a wave energy converter for the WECfarm project." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020.
Find full textAbstract:
There are different technologies to exploit marine energy, one of these is wave energy converters (WEC), that use the energy of the waves to produce electricity. To maximize the power production, the WECs are placed in arrays with specific geometric configurations, therefore it is important to study the interaction between the WECs (near-field interactions) and the effects of the WEC array on the waves behind the array (far-field effects).
A single ‘Master WEC’ is being developed, tested and fine-tuned prior to the array layout tests. The aim is to investigate and improve the behavior of the new WEC design, through tests in different waves conditions. The new shape of the WEC has been designed using a numerical study in order to improve the behavior of the WEC, reducing the surge force and increasing its radiation. The objective of this master dissertation is to study the behavior of the scale model (scale factor 0.525) of the hydrodynamic part of the WEC. Several tests were performed in the wave flume in the laboratory of Ghent University, and the obtained database was subsequently analyzed.
First a free decay test was performed to determine the natural period and the damping factor of the buoy.
Then the results from regular waves tests were analyzed to determine the interaction between two buoys using regular waves with different wave periods.
Several tests were conducted to quantify the horizontal and vertical forces acting on the buoy unit, with differing dispositions of the load cells and differing wave heights and periods.
All the tests were performed with a water depth of 0.65 m.
The data obtained from the measuring devices in the tests was processed with MATLAB to check the repeatability of the tests, to obtain graphs, averaged values of the forces and the acceleration acting on the buoy unit, amplitude and phase of the oscillatory motion of the buoy.
27
Son, Seong Jun. "Effects of TENS on Voluntary Quadriceps Activation and Vertical Ground Reaction Force During Walking in Subjects with Experimental Knee Pain." BYU ScholarsArchive, 2014. https://scholarsarchive.byu.edu/etd/5274.
Full textAbstract:
Context: Knee pain is a common symptom in knee pathology and is associated with alterations in quadriceps activation and movement patterns. Reducing pain through intervention may help reestablish neuromuscular function. The independent effects of knee pain are difficult to examine and unclear. Objective: To investigate the effects of transcutaneous electrical nerve stimulation (TENS) on quadriceps activation and vertical ground reaction force (VGRF) during walking. Design: Crossover. Setting: Laboratory. Subjects: 15 in the TENS group (10M and 5F, 23.5 ± 2.8 yrs, 70.5 ± 12.5 kg, 178.1 ± 7.4 cm), and 15 in the sham group (10M and 5F, 22.5 ± 2.0 yrs, 72.1 ± 13.7 kg, 177.5 ± 9.3 cm). Interventions: Subjects underwent three experimental conditions (pain, sham, and control). Measurements were recorded across four time points (preinfusion, infusion, treatment, and posttreatment). Hypertonic or isotonic saline, respectively, was infused into the infrapatellar fat pad for 48 minutes (total 7.7 mL). The TENS group received a 20-minute treatment. A sham treatment was administered to the sham group. Main Outcome Measures: Perceived knee pain on a 10-cm visual analog scale, knee extension maximum voluntary isometric contraction (MVIC) normalized to body mass, knee extension central activation ratio (CAR), and VGRF. Results: Knee pain peaked at 4 cm during infusion and remained consistent across time in the sham group (F2,28 = 49.90, P < 0.0001), while knee pain gradually decreased to 1.5 cm following TENS treatment (F2,28 = 23.11, P < 0.0001). A group x condition x time interaction was detected for both the MVIC (F6,168 = 2.92, P < 0.01) and CAR (F6,168 = 3.03, P < 0.008) measurements. Post hoc analysis revealed that the infusion of hypertonic saline reduced knee extension MVIC by 29% in the TENS group, and by 26% in the sham group (P < 0.05). However, while the MVIC remained depressed by 26% following sham treatment, the MVIC was found to improve by 12% following TENS treatment (P < 0.05). Similarly, a 10% decrease in CAR was detected in both sham and TENS groups prior to treatment. This 10% deficit held, with a 9% deficit following sham treatment, while the deficit of CAR was improved by 4% following TENS treatment (P < 0.05). For the TENS group, infusion of hypertonic saline changed VGRF at initial loading, midstance, and push-off phase. VGRF was only different at initial loading and push-off phase following TENS treatment. For the sham group however, sham treatment did not restore VGRF, showing alterations in initial loading, midstance, and push-off phase (α = 0.05). Conclusions: Infusion of hypertonic saline increased perceived knee pain, reduced knee extension MVIC, reduced CAR, and altered VGRF over some of stance phase. TENS lessened the deficits in MVIC, CAR, and VGRF, suggesting decreased muscle inhibition and improved movement function.
28
Field, Parker Lawrence. "Comparison of RANS and Potential Flow Force Computations for the ONR Tumblehome Hullfrom in Vertical Plane Radiation and Diffraction Problems." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/23123.
Full textAbstract:
The commercial CFD software STAR-CCM+ is applied as a RANS solver for comparison with potential flow methods in the calculation of vertical plane radiation and diffraction problems. A two-dimensional rectangular cylinder oscillating in an unbounded fluid is first considered, and the added mass result shown to agree well with the analytical potential flow solution. Hydrodynamic coefficients are then determined for the cylinder oscillating in heave and sway about a calm free surface. Predicted values are observed to coincide with available experimental and linear potential flow results for most amplitudes and frequencies of oscillation examined. A three-dimensional radiation problem is then studied in which 1-DoF heave and pitch motions are prescribed to the ONR Tumblehome hullform in calm water at zero forward speed and Fn 0.3. Combinations of amplitude and frequency of oscillation ranging from small to large are considered. Results are compared with several potential flow codes which utilize varying degrees of linearization. Differences in the force and moment results are attributed to particular code characteristics, and overall good agreement is demonstrated between RANS and potential flow codes which employ a nonlinear formulation. The ONR Tumblehome is next held static in incident head waves of small and large steepness and zero forward speed or Fn 0.3. Force and moment time histories of the periodic response are compared with the same set of potential flow codes used in the radiation problem. Agreement between potential flow and RANS is reasonable in the small wave steepness case. For large wave steepness, the nonlinear wave response is seen to be important and the RANS solution does not generally agree well with potential flow results.Master of Science
29
Ribeiro, Leonardo Lamas Leandro. "Treinamento de força máxima e potência: adaptações neurais, coordenativas e desempenho no salto vertical." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/39/39132/tde-23092008-151108/.
Full textAbstract:
Força máxima (TF) e potência (TP) são métodos de treinamento considerados distintos, na prática profissional e em diversos designs experimentais. O presente estudo testou a capacidade destes métodos promoverem o aumento do desempenho, assim como a similaridade das adaptações entre os métodos. Trinta e sete sujeitos foram divididos nos grupos: força (TF), potência (TP) e controle (C), sendo submetidos a oito semanas de treinamento nas seguintes zonas: TF (4-10 RM) e TP (30-60% 1RM). Os resultados significantes foram: força dinâmica máxima TF de 145,3 (±17,1) para 178,5 (±18,8) kg, TP de 147,2 (±16,8) para 171,6 (±19,9) kg; pico de força na contração voluntária isométrica máxima (CVIM) TF de 2240,52 (±448,76) para 2651,82 (±700,22) N, TP de 2249,86 (±427,95) para 2674,80 (±507,68) N; salto vertical a partir da posição de semi-agachamento (SJ) TF de 31,35 (±4,63) para 37,18 (±4,74) cm, TP de 34,44 (±3,90) para 39,61 (±4,70) cm. Apenas o TP gerou aumento no salto com contra-movimento (CMJ) de 35,52 (±4,43) para 38,50 (±4,34) cm. Nenhum dos protocolos promoveu o aumento do sinal eletromiográfico, seja na CVIM ou nos saltos. Verificou-se efeito principal para deslocamento do centro de gravidade, torque de joelho e quadril no SJ, assim como para o deslocamento excêntrico no CMJ. Observou-se similaridade entre os grupos em diversas variáveis analisadas, assim como a possível transferência coordenativa do TP para o CMJ. Assim, força máxima e potência parecem constituir estímulos de treinamento equivalentes em muitos aspectos e por isso, os padrões de especificidade atribuídos a ambos devem ser reconsideradosStrength and power are considered different training methods in promoting neuromuscular adaptations in practice and in several research designs as well. In the present research, the efficacy of these methods in improving performance and resultant neural adaptations in some motor tasks was investigated. Thirty sevens subjects were divided in groups: strength (TF), power (TP) and control (C) and submited to eight weeks of training in different zones: TF (4-10 RM) and TP (30%-60% 1RM). Results that reached significance were the following, pre and pos-test, respectively: Maximum dynamic strength TF:145,3 (±17,1) and 178,5(±18,8), TP:147,2 (±16,8) and 171,6 (±19,9). Peak force in maximum isometric voluntary contraction (MIVC) TF: 2240,52 (±448,76) and 2651,82 (±700,22), TP: 2249,86 (±427,95) and 2674,80 (±507,68). Squat jump (SJ) TF: 31,35 (±4,63) and 37,18 (±4,74), TP: 34,44 (±3,90) and 39,61 (±4,70). In countermovement jump (CMJ) only TP improved: 35,52 (±4,43) and 38,50 (±4,34). No method could improve electromiographical signal. A main effect was noticed for center of mass displacement, knee and hip moments in SJ and eccentric displacement in CMJ. Similar results for many parameters analysed could be observed. The results indicate a possible transference from TP to CMJ as well. This way, strength and power can be considered equivalent in promoting performance in many tasks. Therefore, specificity patterns between strength and power should be reconsidered
30
Thompson, William Kevin. "T2 Mapping of Muscle Activation During Single-Leg Vertical Jumping Exercise." Case Western Reserve University School of Graduate Studies / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=case1194982561.
Full text
31
Stone, Michael H., William A. Sands, Kyle C. Pierce, Michael W. Ramsey, and G. Gregory Haff. "Power and Power Potentiation among Strength-Power Athletes: Preliminary Study." Digital Commons @ East Tennessee State University, 2008. https://dc.etsu.edu/etsu-works/4138.
Full textAbstract:
Purpose: To assess the effects of manipulating the loading of successive sets of midthigh clean pulls on the potentiation capabilities of 7 international-level US weightlifters (4 men, 3 women).
Methods: Isometric and dynamic peak-force characteristics were measured with a force plate at 500 Hz. Velocity during dynamic pulls was measured using 2 potentiometers that were suspended from the top of the right and left sides of the testing system and attached to both ends of the bar. Five dynamic-performance trials were used (in the following order) as the potentiation protocol: women at 60, 80, 100, 120, and 80 kg and men at 60, 140, 180, 220, and 140 kg. Trials 2 vs 5 were specifically analyzed to assess potentiation capabilities. Isometric midthigh pulls were assessed for peak force and rate of force development. Dynamic lifts were assessed for peak force (PF), peak velocity (PV), peak power (PP), and rate of force development (RFD).
Results: Although all values (PF, PV, PP, and RFD) were higher postpotentiation, the only statistically higher value was found for PV (ICCα = .95, P = .011, η2 = .69).
Conclusions: Results suggest that manipulating set-loading configuration can result in a potentiation effect when heavily loaded sets are followed by a lighter set. This potentiation effect was primarily characterized by an increase in the PV in elite weightlifters.
32
Nolan, Karen J. "The influence of variations in shoe midsole density on the impact force and kinematics of landing in female volleyball players." See Full Text at OhioLINK ETD Center (Requires Adobe Acrobat Reader for viewing), 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=toledo1083796438.
Full textAbstract:
Thesis (Ph.D.)--University of Toledo, 2004.Typescript. "A dissertation [submitted] as partial fulfillment of the requirements of the Doctor of Philosophy degree in Exercise Science." Bibliography: leaves 119-125.
33
Pinho, Alexandre Severo do. "Estudo da distribuição do peso corporal entre retropé e antepé em blocos simuladores e calçados de salto." Universidade do Estado de Santa Catarina, 2005. http://tede.udesc.br/handle/handle/358.
Full textAbstract:
Made available in DSpace on 2016-12-06T17:07:11Z (GMT). No. of bitstreams: 1
Alexandre Pinho.pdf: 2648154 bytes, checksum: 89f3e208e24484e5c16db812840b299c (MD5)
Previous issue date: 2005-08-26Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
The aim of this work was to investigate the relation of the vertical component of the ground reaction forces and the plantar pressure distribution during standing position, acting under the forefoot and the rearfoot, using high heel shoes and high heel simulators (wooden blocks of different heights and angles of heel support). The subjects were 30 symptom-free volunteer women, with no apparent foot and leg pathologies, with body mass index (BMI) up to 30 (Pollock, 1993) who are used to wear high heel shoes at least once a week. To obtain the relations on the weight force application and the pressure distribution under the feet the subjects were positioned standing over two force plates AMTI (Massachusetts, EUA, 1991) at 60Hz, synchronized with a pair of pedar mobile insoles (pedar® novelgmbh © 2005) at 50Hz. The foot was divided in two areas and data was acquired in 10 seconds of self balanced position. Significant differences between the means of vertical force and plantar pressure were found related to the heights differences and angle differences (p< 0,001), at the wearing shoes situation and with the simulators. The results of force and pressure did not follow a linear relation but increased as the heel height support got higher in both situations.
Este trabalho visou investigar a aplicação da força peso relativo ao peso corporal em retropé através da componente vertical da força de reação do solo (Fz) e a distribuição de pressão plantar nas regiões do retropé e antepé, na posição estática, em apoio bipodal, através do uso de calçados de salto e simuladores de altura e de ângulo de apoio do calcâneo. Participaram deste estudo 30 mulheres voluntárias, sem histórico de patologias em membros inferiores nos últimos 12 meses, sem índices de massa corporal que indicassem padrões de obesidade, segundo Pollock, (1993) e habituadas a utilizar calçado de salto pelo menos uma vez por semana. Os indivíduos utilizando calçados variados e blocos simuladores se posicionaram sobre duas plataformas de força AMTI (Massachusetts, EUA, 1991) dispostas em série adquirindo dados a uma freqüência de 60 Hz de forma sincronizada a um sistema de medição de distribuição de pressão plantar através de palmilhas sensorizadas (pedar® novelgmbh © 2005) adquirindo a uma freqüência de 50 Hz pelo tempo de 10 segundos. Verificou-se para a variável força vertical (Fz) diferenças significativas entre as médias tanto em relação às alturas (p< 0,001), como entre os ângulos (p< 0,001), obtendo-se similarmente nas situações real e simulada, ao nível de significância de 5%, um padrão não linear de diminuição da força vertical (Fz) em retropé e da pressão plantar nesta mesma região à medida que a altura do apoio no calcâneo aumenta.
34
Borràs, Boix Xantal. "La valoració de la força de l’extremitat inferior en el voleibol. Test de salt vertical i determinació d’asimetries." Doctoral thesis, Universitat de Barcelona, 2010. http://hdl.handle.net/10803/31980.
Full textAbstract:
El salt vertical és una acció que està present en el voleibol. Forma part de la tècnica de remat, de bloqueig i dels serveis amb salt. També és utilitzat per col.locadors per tal d’anticipar el contacte amb la pilota i incrementar la velocitat del joc. S’ha observat que els jugadors de voleibol efectuen d’entre 65 i 136 salts en un partit de 5 sets.
Aquesta tesi doctoral té un doble objectiu; per una banda pretén realitzar una descripció de la força de l’extremitat inferior en jugadors de voleibol durant la realització del salt vertical. Per l’altra banda, té la intenció de desenvolupar un mètode per valorar la força i determinar la asimetria entre les extremitats que sigui aplicable al voleibol i a la resta d’esports.
S’ha realitzat un protocol de salt vertical en jugadors de la selecció espanyola de voleibol durant quatre temporades (2006-2009). Aquest protocol inclou la valoració de l’squat jump (SJ), el salt amb contramoviment (CMJ), el salt amb contramoviment i utilització de braços (CMJb) i el salt amb cursa d’aproximació (DJb). En les temporades 2006-2008 la valoració es va realitzar mitjançant una plataforma de contactes. Durant la temporada 2009, el salt vertical es va valorar, simultàniament, mitjançant una plataforma de contactes i dues plataformes de força, una sota de cada peu.
S’ha observat un increment del salt vertical entre les temporades 2006-2008 i una millora de les diferents manifestacions de la força, tot i que entre la temporada 2007 i 2008, l’índex d’elasticitat empitjora. En termes generals, la forma física de la selecció és millor any rere any. Els jugadors de voleibol no presenten asimetria ni en la força màxima, ni en l’impuls quan es compara cama dreta amb cama esquerra, però sí quan es compara cama forta amb cama feble, tot i que de mitjana no se supera el 15% de asimetria considerat com a factor de risc per patir lesions.
La plataforma de forces és un sistema més adequat que la plataforma de contactes per determinar l’alçada del salt vertical perquè no sobreestima l’alçada del salt. També permet avaluar de manera directa la potència mecànica i la força executada durant el salt, així com identificar un SJ correcte d’un altre que no ho és. No obstant, no és útil per determinar l’alçada del DJb degut a les reduïdes dimensions. S’ha observat que la potència màxima, sobretot quan es mostra relativa al pes corporal, és la variable que millor explica l’alçada del salt vertical. Això indica que l’entrenament per millorar l’alçada del salt ha d’anar orientat a la millora de la força a elevades velocitats d’execució.
És necessari estudiar l’evolució dels esportistes i aplicar la el mètode en altres esports. També és necessari realitzar un control de base que serveixi per proporcionar dades de normalitat i poder ajudar a diagnosticar el retorn a l’activitat després d’una lesió.The vertical jump is a common action in the volleyball game when spiking, blocking, serving and setting. Volleyball players jump among 65 and 136 times in a 5 set game. The aims of the study were: (1) to describe the lower extremity force during a vertical jump test and (2) to develop a methodology that, simultaneously, evaluates force and determines asymmetries between legs. Physical state of the National Spanish Team players was assessed, during four seasons (2006-2009), by means a vertical jump test protocol that included evaluation of squat jump (SJ), countermovement jump (CMJ), countermovement jump with arms movement (CMJa) and spike jump (DJb). During 2006-2008 vertical jump was evaluated by means of a contact mat. During 2009, vertical jump was evaluated simultaneously by means of a contact mat and two force platforms, one underneath each foot. The results indicated a better performance of explosive strength, elastic-explosive strength, reflexelastic-explosive strength and a better use of arms when jumping. Results also showed a maximal force and impulse symmetry when comparing right and left legs, but an asymmetry was observed when comparing weak and strong leg. Asymmetry index was lower than 15%. Force platform is considered a better instrument than the contact mat to evaluate vertical jump height because it does not overestimate jump height. Furthermore, power and force can also be evaluated during the assessment, and the force - time curve allows identifying a correct SJ jump. Nevertheless, it is not useful to evaluate DJb due to its reduced dimensions. Maximum relative power has a very high correlation with vertical jump height. The optimal training to improve vertical jump height is the one that increases force at high velocity rates. It would be necessary to perform a base control to all athletes to know normality data and to help in the return to competition diagnosis after an injury.
El salto vertical es una acción que está presente en el voleibol. Forma parte de la técnica del remate, del bloqueo i de los servicios con salto. También es utilizado por los colocadores para anticipar el contacto con la pelota e incrementar la velocidad del juego. Los jugadores de voleibol efectúan entre 65 y 136 saltos durante un partido de 5 sets. Esta tesis doctoral tiene un doble objetivo, por un lado pretende realizar una descripción de la fuerza de la extremidad inferior de los jugadores de voleibol durante la realización del salto vertical. Por otro lado, tiene la intención de desarrollar un método para evaluar a fuerza y determinar la asimetría entre las extremidades que sea aplicable al voleibol y a otros deportes. Se ha realizado una evaluación del salto vertical de los jugadores de la selección española de voleibol durante cuatro temporadas (2006-2009). Este protocolo incluye la valoración del salto desde el medio squat (SJ), el salto con contramovimiento (CMJ), el salto con contramovimiento y utilización de brazos (CMJb) i el salto con carrera de aproximación (DJb). Durante las temporadas 2006-2008 la valoración se realizó mediante una plataforma de contactos. Durante la temporada 2009 se evaluó simultáneamente con una plataforma de contactos y dos plataformas de fuerzas, una debajo de cada pie. Se ha observado que el salto vertical incrementa entre las temporadas 2006-2008. También mejoran las diferentes manifestaciones de la fuerza, aunque entre la temporada 2007 y 2008 el índice de elasticidad empeora. En términos generales, la forma física de la selección es mejor año tras año. Los jugadores de voleibol no presenten asimetría ni en la fuerza máxima, ni en el impulso cuando se compara pierna derecha con pierna izquierda, pero sí cuando se compara pierna fuerte con la débil, aunque de promedio, no se supera el 15% de asimetría considerado como factor de riesgo para sufrir lesiones. La plataforma de fuerzas es un sistema más adecuado que la plataforma de contactos para determinar la altura del salto vertical ya que no sobreestima la altura del salto. También permite evaluar de manera directa la potencia mecánica y la fuerza ejecutada durante el salto, así como identificar un SJ correcto de otro que no lo es. No obstante, no es útil para determinar la altura del salto del DJb debido a sus reducidas dimensiones. Se ha observado que la potencia máxima, sobretodo cuando se presenta relativa al peso corporal, es la variable que mejor explica a altura del salto vertical. Esto indica que el entrenamiento para mejorar la altura del salto tiene que ir orientado a la mejora de la fuerza a elevadas velocidades de ejecución. Es necesario estudiar la evolución de los deportistas y aplicar el método en otros deportes. También se necesita un control de base que sirva para proporcionar datos de normalidad y poder ayudar a diagnosticar el retorno a la actividad después de la lesión.
35
Samozino, Pierre. "Capacités mécaniques des membres inférieurs et mouvements explosifs. Approches théoriques intégratives appliquées au saut vertical." Phd thesis, Université Jean Monnet - Saint-Etienne, 2009. http://tel.archives-ouvertes.fr/tel-00483683.
Full textAbstract:
Le but de ce travail était d'étudier les capacités mécaniques des membres inférieurs et leur implication dans la performance lors de mouvements explosifs par l'utilisation d'approches théoriques intégratives. La première partie de ce travail a proposé et validé une nouvelle méthode simple d'évaluation des capacités mécaniques des membres inférieurs. Cette méthode, basée sur les principes fondamentaux de la dynamique, présente trois équations donnant les valeurs moyennes de force, de vitesse et de puissance développées lors d'un saut à partir de trois paramètres simples : la masse, la hauteur de saut et la distance verticale de poussée. Cette méthode, utilisable sur le terrain, permet d'obtenir la puissance produite lors d'un saut maximal et permet de tracer les relations force-vitesse à partir de sauts chargés, ces tests nécessitant jusqu'à présent des outils de mesures spécifiques. La deuxième partie de ce travail a proposé une nouvelle approche théorique intégrative pour appréhender l'implication des capacités mécaniques des membres inférieurs dans les sauts verticaux maximaux. Tout d'abord, la prise en compte des contraintes mécaniques du générateur de force (les membres inférieurs) et de la dynamique du mouvement (un corps accéléré linéairement) sur la production de force lors de la poussée a permis d'exprimer mathématiquement la hauteur maximale de saut qu'un individu peut atteindre en fonction de trois caractéristiques de ses membres inférieurs : leur capacité maximale de production de force, leur vitesse maximale d'extension et leur amplitude de déploiement. En plus de mettre en avant les variables mécaniques qui sont impliquées dans la performance en saut, cette équation a permis de montrer et de quantifier l'influence positive de ces trois caractéristiques mécaniques sur la hauteur de saut. Cette expression mathématique peut constituer une première étape importante dans l'analyse des différences de performances en saut entre les individus, entre les espèces, et pour un même individu entre deux moments différents. Ensuite, cette approche théorique intégrative a été utilisée pour approcher la notion de profil force-vitesse d'un individu et pour en étudier l'influence sur la performance en saut indépendamment de la puissance maximale. Cette notion de profil force-vitesse, appréciée par la pente de la relation force-vitesse, fait référence aux différentes combinaisons de force et vitesse maximales des membres inférieures pouvant induire les mêmes capacités de puissance. A partir de l'approche théorique proposée précédemment, la hauteur de saut a été exprimée mathématiquement en fonction de la distance de poussée, de la puissance maximale et de la pente de la relation force-vitesse. Cette analyse a permis de montrer que la performance en saut, et donc la capacité à produire une grande impulsion, est fortement liée à la puissance maximale des membres inférieurs, mais également à leur profil force-vitesse. Un profil force-vitesse optimal maximisant la hauteur de saut a été mis en évidence. Cette notion de profil force-vitesse d'un athlète, et la comparaison au profil optimal, semble intéressante à considérer pour optimiser les performances lors de mouvements explosifs visant à accélérer sa propre masse. En conclusion, ce travail de thèse a permis, au moyen d'approches théoriques intégratives, d'éclaircir les relations entre la performance en saut vertical et les caractéristiques mécaniques de la poussée, d'une part pour proposer une nouvelle méthode d'évaluation simple des capacités mécaniques des membres inférieurs, et d'autre part pour comprendre et quantifier l'implication de ces dernières dans la performance lors de mouvements explosifs. Produire une grande impulsion lors d'une phase d'extension des membres inférieurs requière une puissance maximale élevée et un profil force-vitesse optimal.
36
Nicholson, Joanne M. "The effects of a lower body moderate intensity resistance training program on the vertical force-time curve of a chair rise in the elderly." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq20845.pdf.
Full text
37
Quaine, Franck. "Analyse statique et dynamique de la posture en quadrupedie verticale." Université Joseph Fourier (Grenoble), 1996. http://www.theses.fr/1996GRE10204.
Full textAbstract:
L'objectif des etudes presentees dans ce memoire etait d'analyser la strategie d'equilibration d'un grimpeur associee au relachement volontaire d'une prise sur une base de quadrupedie verticale. Cette etude a ete realisee dans des positions plus ou moins eloignees du plan vertical des prises. Elle a permis de mettre en evidence que la strategie d'equilibration suite au delestage volontaire d'une prise, dans une position ou le centre de gravite du grimpeur se projetait dans la base de support se resumait a la gestion du poids de corps sur les appuis. Cette etude montre que lorsque le centre de gravite du grimpeur se projette a l'exterieur du polygone de sustentation, le grimpeur est assimile a un pendule inverse en rotation autour des prises de pied. Dans ces conditions, les forces de reactions horizontales appliquees sur les prises sont les forces stabilisatrices de la posture. Leur intensite est proportionnelle au couple destabilisateur engendre par le poids corporel. La perturbation occasionnee par le relachement d'un appui s'accompagne du transfert du poids de corps sur les trois appuis restants et du transfert des forces stabilisatrices sur la ligne d'appui controlaterale a la prise delestee. Cette strategie montre qu'elle permet de creer les conditions dynamiques favorables a l'execution du delestage volontaire, tout en assurant la base posturale. La caracterisation des contraintes mecaniques articulaires a permis de mettre en evidence la gestion particuliere des forces de pesanteur et des forces de stabilisation en quadrupedie verticale. La stabilite est geree de maniere passive au niveau des articulations du membre superieur controlateral, tandis que deux niveaux de gestion de la stabilite apparaissent sur les articulations du membre inferieur controlateral. L'articulation de la cheville controle la stabilite du grimpeur par rapport a la prise de pied, l'articulation de la hanche controle la posture du tronc par rapport au bassin
38
Gage, Matthew J. "The Effects of Abdominal Training on Postural Control, Lower Extremity Kinematics, Kinetics, and Muscle Activation." Diss., CLICK HERE for online access, 2009. http://contentdm.lib.byu.edu/ETD/image/etd3125.pdf.
Full text
39
McCarren, Gillian A. "The Impact of Dual Task Shooting on Knee Kinematics and Kinetics." Ohio University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1556214323893082.
Full text
40
Rizzo, Frank. "Does a Tailored Nine-week Training Intervention Improve Jump Height, Single-leg Stability, and Whole-body Stability Performance in Young Cross-country Skiers?" Thesis, Umeå universitet, Avdelningen för idrottsmedicin, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-181172.
Full textAbstract:
The purpose of this study was to investigate if a nine-week training intervention composed of different mobility and stability exercises intending to improve jump height, whole-body stability, and single-leg stability of junior cross-country skiers. It was also of interest to see if the test equipment could determine the study participants' potential risk of injury with a built-in injury predictor measurement, Musculoskeletal Health (MSK). A total of 16 cross-country skiers aged 16-20 years, 8 man and 8 women, performed the following tests on a force plate; Jump Scan (i.e., to characterize an individual's dynamic movement strategy), Plank Scan (i.e., to measure the individual's ability to control global static stability across each extremity), and Balance Scan (i.e., the individual's ability to maintain their center of mass over their center of pressure). After the initial scan, participants were assigned to the same nine-week intervention program, with Group 1 performing the program three times each week and Group 2 once each week before performing a post-intervention scan. Using two-way ANOVA showed no significant between-group differences. There was no significant difference when using three-way ANOVA within both intervention groups, except higher CMJ Load scores (p=0.032) and reduction in Plank scores, Plank Left (p=0.024) in male participants. When using logistic regression tests to determine the correlation between jump height (CMJ) outcomes effect on MSK injury risk between groups and within gender, a significant correlation in females was shown (p=0.0280, R=0.46). The present study's results suggest that a 9-week training intervention is not sufficient when training either one or three times per week for improving jump height, whole-body stability, and single-leg stability in junior cross-country skiers.
41
Fiedler, Holger. "Preparation and characterization of Carbon Nanotube based vertical interconnections for integrated circuits." Doctoral thesis, Universitätsbibliothek Chemnitz, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-149474.
Full textAbstract:
(ULSI) causes an increase of the resistance of the wiring system by increased scattering of electrons at side walls and grain boundaries in the state of the art Cu technology, which increases the RC delay of the interconnect system and thus degrades the performance of the device. The outstanding properties of carbon nanotubes (CNT) such as a large mean free path, a high thermal conductance and a large resistance against electromigration make them an ideal candidate to replace Cu in future feature nodes. The present thesis contributes to the preparation and properties of CNT based vertical interconnections (vias). In addition, all processes applied during the fabrication are compatible to ULSI and an interface between CNT based vias and a Cu metallization is studied. The methodology for the evaluation of CNT based vias is improved; it is highlighted that by measuring the resistance of one multiwall CNT and taking into account the CNT density, the performance of the CNT based vias can be predicted accurately. This provides the means for a systematic evaluation of different integration procedures and materials. The lowest contact resistance is obtained for carbide forming metals, as long as oxidation during the integration is avoided. Even though metal-nitrides exhibit an enhanced contact resistance, they are recommended to be used at the bottom metallization in order to minimize the oxidation of the metal-CNT contact during subsequent processing steps. Overall a ranking for the materials from the lowest to the highest contact resistance is obtained: Ta < Ti < TaN < TiN « TiO2 « Ta2O5 Furthermore the impact of post CNT growth procedures as chemical mechanical planarization, HF treatment and annealing procedures after the CNT based via fabrication are evaluated. The conductance of the incorporated CNTs and the applicable electrical transport regime relative to the CNT quality and the CNT length is discussed. In addition, a strong correlation between the temperature coefficient of resistance and the initial resistance of the CNT based vias at room temperature has been observedDie kontinuierliche Miniaturisierung der charakteristischen Abmessungen in hochintegrierten Schaltungen (ULSI) verursacht einen Anstieg des Widerstandes im Zuleitungssystem aufgrund der erhöhten Streuung von Elektronen an Seitenwänden und Korngrenzen in der Cu-Technologie, wodurch die Verzögerungszeit des Zuleitungssystems ansteigt. Die herausragenden Eigenschaften von Kohlenstoffnanoröhren (CNT), wie eine große mittlere freie Weglänge, hohe thermische Leitfähigkeit und eine starke Resistenz gegenüber Elektromigration machen diese zu einem idealen Kandidaten, um Cu in zukünftigen Technologiegenerationen zu ersetzen. Die vorliegende Arbeit beschreibt die Herstellung und daraus resultierenden Eigenschaften von Zwischenebenenkontakten (Vias) basierend auf CNTs. Alle verwendeten Prozessierungsschritte sind kompatibel mit der Herstellung von hochintegrierten Schaltkreisen und eine Schnittstelle zwischen den CNT Vias und einer Cu-Metallisierung ist vorhanden. Insbesondere das Verfahren zur Evaluierung von CNT Vias wurde durch den Einsatz verschiedener Methoden verbessert. Insbesondere soll hervorgehoben werden, dass durch die Messung des Widerstandes eines einzelnen CNTs, bei bekannter CNT Dichte, der Via Widerstand sehr genau vorausgesagt werden kann. Dies ermöglicht eine systematische Untersuchung des Einflusses der verschiedenen Prozessschritte und der darin verwendeten Materialien auf den Via Widerstand. Der niedrigste Kontaktwiderstand wird für Karbidformierende Metalle erreicht, solange Oxidationsprozesse ausgeschlossen werden können. Obwohl Metallnitride einen höheren Kontaktwiderstand aufweisen, sind diese für die Unterseitenmetallisierung zu empfehlen, da dadurch die Oxidation der leitfähigen Schicht minimiert wird. Insgesamt kann eine Reihenfolge beginnend mit dem niedrigsten zum höchsten Kontaktwiderstand aufgestellt werden: Ta < Ti < TaN < TiN « TiO2 « Ta2O5 Desweiteren wurde der Einfluss von Verfahren nach dem CNTWachstum wie die chemischmechanische Planarisierung, eine HF Behandlung und einer Temperaturbehandlung evaluiert, sowie deren Einfluss auf die elektrischen Parameter des Vias untersucht. Die Leitfähigkeit der integrierten CNTs und die daraus resultierenden elektrischen Transporteigenschaften in Abhängigkeit der CNT Qualität und Länge werden besprochen. Ebenso wird die starke Korrelation zwischen dem Temperaturkoeffizienten des elektrischen Widerstandes und des Ausgangswiderstandes der CNT basierten Vias bei Raumtemperatur diskutiert
42
Griswold, Emily K. "Comparison of Jump Landings in Figure Skaters While Barefoot and Wearing Skates." Ohio University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1490346788544816.
Full text
43
Hornsby, W. Guy, Jeremy A. Gentles, Christopher J. MacDonald, Satoshi Mizuguchi, Michael W. Ramsey, and Michael H. Stone. "Maximum Strength, Rate of Force Development, Jump Height, and Peak Power Alterations in Weightlifters across Five Months of Training." Digital Commons @ East Tennessee State University, 2017. https://dc.etsu.edu/etsu-works/4114.
Full textAbstract:
The purpose of this monitoring study was to investigate how alterations in training affect changes in force-related characteristics and weightlifting performance. Subjects: Seven competitive weightlifters participated in the study. Methods: The weightlifters performed a block style periodized plan across 20 weeks. Force plate data from the isometric mid-thigh pull and static jumps with 0 kg, 11 kg, and 20 kg were collected near the end of each training block (weeks 1, 6, 10, 13, 17, and 20). Weightlifting performance was measured at weeks 0, 7, 11, and 20. Results: Very strong correlations were noted between weightlifting performances and isometric rate of force development (RFD), isometric peak force (PF), peak power (PP), and jump height (JH). Men responded in a more predictable manner than the women. During periods of higher training volume, RFD was depressed to a greater extent than PF. JH at 20 kg responded in a manner reflecting the expected fatigue response more so than JH at 0 kg and 11 kg. Conclusions: PF appears to have been more resistant to volume alterations than RFD and JH at 20 kg. RFD and JH at 20 kg appear to be superior monitoring metrics due to their “sensitivity.”
44
Attiogbe, Amévi Elvis. "Facteurs d'influence de la relation détente verticale - puissance maximale musculaire des membres inférieurs." Thesis, Paris 10, 2019. http://www.theses.fr/2019PA100170.
Full textAbstract:
Ce travail s’inscrit à la frontière de la physiologie et de la biomécanique musculaires. Il avait pour objectifs d’expliquer les facteurs déterminant la relation détente verticale (DV)–puissance maximale des membres inférieurs sur ergocycle (Pmax). L’étude A, réalisée chez 106 sujets, a mis en évidence que DV avec contre-mouvement et balancer des bras (CMJA) était plus élevée chez les sujets d’origine Afro-Antillaise (WA) comparés à ceux d’origine Caucasienne (C) et que CMJA était supérieure chez les volleyeurs comparés aux étudiants STAPS non entrainés aux exercices de saut ou de pédalage. Il n’y avait pas d’effet de la pratique sportive ni de l’ethnicité (E) sur Pmax. Cependant, la relation CMJA-Pmax était différente entre C et WA (P=0,003). Ainsi, la prédiction de CMJA à partir de Pmax pourrait être sous-estimée chez WA. La même différence a été observée au niveau de la relation CMJA-Pmax des bras. L’étude B, réalisée chez 84 sujets, a mis en évidence des différences ethniques significatives (WA>C) lors de DV sur plateforme de force sans (SJ), avec contre- mouvement (CMJ) et pour CMJA, CMJA-CMJ, CMJA/CMJ. La taille de l’effet de E était élevée pour CMJA, CMJA-CMJ, CMJA/CMJ et moyenne pour CMJ et SJ. L’effet de E du contre-mouvement (CMJ-SJ) était non significatif. Dans l’étude C, réalisée chez 55 sujets, ont été explorés les effets des facteurs anthropométriques [taille du corps (BH), taille assise (SH), longueur du pied (FL), longueur de la jambe (LL), masse corporelle (BW), IMC, masse grasse corporelle (BF), BF/BW et les indices skélique (Sk=LL/SH) ou cormique (Co=SH/BH)] et E (C vs WA) sur SJ, CMJC et CMJA mesurés sur une plate-forme de force. Seuls SH, Sk et Co étaient significativement différents entre C et WA. Toutes les performances de DV étaient plus élevées chez WA. La différence ethnique de SH pourrait expliquer en partie les valeurs plus élevées de DV chez WAThe present thesis fits on the border of muscle physiology and biomechanics. Three studies investigated the factors influencing the relationship between vertical jump (DV) and maximal power out on cycle ergometer (Pmax). Study A, conducted on 106 participants from two groups (volleyball players, VB, and physical education students (PES) without specific training in jumping or cycling exercises) including 67 Caucasian (C) 39 West African (WA) origins, showed significant effects of sports practice (VB>PES) and enthnicity (E) (WA>C) on countermovement jump with arm swing (CMJA). However, the difference in Pmax was not significant between groups. The CMJA-Pmax relationships were different in C and WA (P=0.003). Therefore, CMJA predicted from Pmax would be underestimated in WA. The same difference was observed for CMJA-PmaxArms relationship. Study B, conducted on 84 participants, showed E significant difference (WA>C) in DV on a force platform in squat jump (SJ), countermovement jump (CMJ), CMJA, CMJA-CMJ, CMJA/CMJ. The effect sizes of E were large for CMJA, CMJA-CMJ, CMJA/CMJ and medium for CMJ and SJ. E effect of countermovement jump (CMJ-SJ) was not significant. In study C, the effects of anthropometric factors [body height (BH), sitting height (SH), foot length (FL), leg length (LL), Body Weight (BW), BMI, Body fat (BF), BF/BW and Skelic (Sk=LL/SH) or Cormic (Co=SH/BH) indices], and E (C vs WA) on SJ, CMJ and CMJA)] have been measured on a force platform in 55 PES [32 Caucasians (group C) and 23 West-Africans (group WA)]. Only SH, Sk and Co were significantly different in C and WA. All DV performances were higher WA The ethnic difference in SH could partly explain the higher DV values in WA
45
Carroll, Kevin M., Jake R. Bernards, Caleb D. Bazyler, Christopher B. Taber, Charles A. Stuart, Brad H. DeWeese, Kimitake Sato, and Michael H. Stone. "Divergent Performance Outcomes Following Resistance Training Using Repetition Maximums or Relative Intensity." Digital Commons @ East Tennessee State University, 2018. https://dc.etsu.edu/etsu-works/3773.
Full textAbstract:
Purpose: The purpose of our investigation was to compare repetition maximum (RM) to relative intensity using sets and repetitions (RISR) resistance training (RT) on measures of training load, vertical jump, and force production in well-trained lifters.
Methods: Fifteen well-trained (isometric peak force= 4403.61+664.69 N, mean+SD) males underwent RT 3 d·wk-1 for 10-weeks in either an RM group (n=8) or RISR group (n=7). Weeks 8-10 consisted of a tapering period for both groups. The RM group achieved a relative maximum each day while the RISRgroup trained based on percentages. Testing at five time-points included unweighted (
Results: Moderate between-group effect sizes were observed for all SJ and CMJ conditions supporting the RISR group (g=0.76-1.07). A small between-group effect size supported RISR for allometrically-scaled isometric peak force (g=0.20). Large and moderate between-group effect sizes supported RISR for rate of force development from 0-50ms (g=1.25) and 0-100ms (g=0.89). Weekly volume load displacement was not different between groups (p>0.05), however training strain was statistically greater in the RM group (p<0.05).
Conclusions: Overall, this study demonstrated that RISR training yielded greater improvements in vertical jump, rate of force development, and maximal strength compared to RM training, which may partly be explained by differences in the imposed training stress and the use of failure/non-failure training in a well-trained population.
46
Neves, Katy Andrews. "Achilles Tendon Changes in Downhill, Level and Uphill Running." BYU ScholarsArchive, 2014. https://scholarsarchive.byu.edu/etd/4399.
Full textAbstract:
In this study, we examined how hill running affects the Achilles tendon, which is a common location for injuries in runners. Twenty females ran for 10 min on three randomly selected grades (-6%, 0%, +6%). Achilles tendon (AT) cross-sectional area (CSA) was imaged using Doppler ultrasound and peak vertical forces were analyzed using high-speed (240 Hz) videography. A metabolic cart and gas analyzer ensured a similar metabolic cost across grades. Data were analyzed using a forward selection regression. Results showed a decrease in AT CSA from pre-run to post-run (p = .0001). Peak vertical forces were different across grades (p = .0001) with the largest occurring during downhill running and smallest during uphill running. The results suggest that the Achilles tendon is affected by running and a decrease in CSA appears to be a normal response. The AT CSA does not differ between grade conditions when metabolic cost of running is matched, suggesting an adaptive effect of the AT. Coaches and athletes can use this knowledge to develop workout protocols that transition runners to downhill running and allow them to adapt to these greater forces.
47
Oliveira, Luciane Marcela Filizola de. "Cisalhamento nas interfaces verticais de paredes de edifícios de alvenaria estrutural." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-04082009-145407/.
Full textAbstract:
Este trabalho apresenta a avaliação das tensões de cisalhamento nas interfaces verticais de paredes de alvenaria interconectadas em casos onde atuam simultaneamente carregamentos verticais e ações horizontais. Os valores obtidos para as máximas tensões de cisalhamento são comparados com as resistências estabelecidas na norma brasileira em vigor, NBR 10837 (ABNT, 1989), e no texto base para sua revisão. Os valores das referidas normas também são confrontados com valores experimentais, avaliando-se criticamente a aplicação dos limites normativos na prática de projetos de edifícios existentes. Adicionalmente, são avaliadas duas formas distintas de modelagem de edifícios de alvenaria estrutural, quando submetidos às ações horizontais. A primeira consiste em uma abordagem simplificada e bastante usual entre projetistas, a associação plana de paredes isoladas. Sua aferição é importante para fornecer ao projetista uma ferramenta que lhe permita obter resultados de maneira rápida e confiável. A segunda forma de modelagem é uma análise de pórtico tridimensional que permite uma análise mais completa das paredes de contraventamento, incluindo os efeitos das deformações por cisalhamento. Com o intuito de avaliar as diferenças observadas entre os dois modelos, foram empregados testes estatísticos, que permitem analisar se eles são estatisticamente iguais a um nível de significância de 5%. Para aquisição dos dados para as análises são feitos estudos de casos com quatro edifícios residenciais usuais, com diferentes arranjos arquitetônicos, variando-se o número de pavimentos em quatro, oito, doze e dezesseis, de modo a se obter maior representatividade dos resultados. Com os resultados obtidos nas avaliações, concluiu-se que os valores adotados como limites de resistência pelo texto base da revisão da NBR 10837 (ABNT, 1989) parecem ser rigorosos para realidade brasileira. Com relação à comparação dos modelos estudados, os testes estatísticos direcionam a uma conclusão importante, que é a de não haver diferença entre eles, para um nível de 5% de significância.This work presents the evaluation of the shear stress at the vertical interfaces of interconnected masonry walls simultaneously subjected to vertical and horizontal loads. The obtained maximum shear stress values are compared to the shear strengths prescribed by the current Brazilian code, NBR 10837 (ABNT, 1989), and by its review base text. The prescribed values are also confronted with experimental values, critically evaluating the application of the regulatory limits in the practical design of existing buildings. Additionally, two different ways of modeling the structural masonry buildings when submitted by horizontal actions are evaluated. The first one is a simple approach, largely used by designers, that consists in the two dimensional association of isolated walls. Its evaluation is important to provide the designer with a quick and reliable analytical tool. The second way of modeling is a three dimensional frame analysis, which allows a more complete simulation of the shear walls, including the shear strain effects. In order to evaluate the differences between the two models, statistical tests were employed for examining whether they are statistically equal at a significance level of 5%. Case studies were performed taking into account four residential buildings with different architectural arrangements. The number of floors was also varied considering four, eight, twelve and sixteen, in order to obtain more meaningful results. The developed analysis showed that the strength limits prescribed by the review base text of the NBR 10837 (ABNT, 1989) seem to be very much strict according to the Brazilian common practice. Regarding the comparison of the studied analytical models, the statistical tests showed that there is no difference between them at a significance level of 5%.
48
Fiedler, Holger. "Preparation and characterization of Carbon Nanotube based vertical interconnections for integrated circuits: Preparation and characterization of Carbon Nanotube based verticalinterconnections for integrated circuits." Doctoral thesis, Universitätsverlag der Technischen Universität Chemnitz, 2013. https://monarch.qucosa.de/id/qucosa%3A20091.
Full textAbstract:
(ULSI) causes an increase of the resistance of the wiring system by increased scattering of electrons at side walls and grain boundaries in the state of the art Cu technology, which increases the RC delay of the interconnect system and thus degrades the performance of the device. The outstanding properties of carbon nanotubes (CNT) such as a large mean free path, a high thermal conductance and a large resistance against electromigration make them an ideal candidate to replace Cu in future feature nodes. The present thesis contributes to the preparation and properties of CNT based vertical interconnections (vias). In addition, all processes applied during the fabrication are compatible to ULSI and an interface between CNT based vias and a Cu metallization is studied. The methodology for the evaluation of CNT based vias is improved; it is highlighted that by measuring the resistance of one multiwall CNT and taking into account the CNT density, the performance of the CNT based vias can be predicted accurately. This provides the means for a systematic evaluation of different integration procedures and materials. The lowest contact resistance is obtained for carbide forming metals, as long as oxidation during the integration is avoided. Even though metal-nitrides exhibit an enhanced contact resistance, they are recommended to be used at the bottom metallization in order to minimize the oxidation of the metal-CNT contact during subsequent processing steps. Overall a ranking for the materials from the lowest to the highest contact resistance is obtained: Ta < Ti < TaN < TiN « TiO2 « Ta2O5 Furthermore the impact of post CNT growth procedures as chemical mechanical planarization, HF treatment and annealing procedures after the CNT based via fabrication are evaluated. The conductance of the incorporated CNTs and the applicable electrical transport regime relative to the CNT quality and the CNT length is discussed. In addition, a strong correlation between the temperature coefficient of resistance and the initial resistance of the CNT based vias at room temperature has been observed.Die kontinuierliche Miniaturisierung der charakteristischen Abmessungen in hochintegrierten Schaltungen (ULSI) verursacht einen Anstieg des Widerstandes im Zuleitungssystem aufgrund der erhöhten Streuung von Elektronen an Seitenwänden und Korngrenzen in der Cu-Technologie, wodurch die Verzögerungszeit des Zuleitungssystems ansteigt. Die herausragenden Eigenschaften von Kohlenstoffnanoröhren (CNT), wie eine große mittlere freie Weglänge, hohe thermische Leitfähigkeit und eine starke Resistenz gegenüber Elektromigration machen diese zu einem idealen Kandidaten, um Cu in zukünftigen Technologiegenerationen zu ersetzen. Die vorliegende Arbeit beschreibt die Herstellung und daraus resultierenden Eigenschaften von Zwischenebenenkontakten (Vias) basierend auf CNTs. Alle verwendeten Prozessierungsschritte sind kompatibel mit der Herstellung von hochintegrierten Schaltkreisen und eine Schnittstelle zwischen den CNT Vias und einer Cu-Metallisierung ist vorhanden. Insbesondere das Verfahren zur Evaluierung von CNT Vias wurde durch den Einsatz verschiedener Methoden verbessert. Insbesondere soll hervorgehoben werden, dass durch die Messung des Widerstandes eines einzelnen CNTs, bei bekannter CNT Dichte, der Via Widerstand sehr genau vorausgesagt werden kann. Dies ermöglicht eine systematische Untersuchung des Einflusses der verschiedenen Prozessschritte und der darin verwendeten Materialien auf den Via Widerstand. Der niedrigste Kontaktwiderstand wird für Karbidformierende Metalle erreicht, solange Oxidationsprozesse ausgeschlossen werden können. Obwohl Metallnitride einen höheren Kontaktwiderstand aufweisen, sind diese für die Unterseitenmetallisierung zu empfehlen, da dadurch die Oxidation der leitfähigen Schicht minimiert wird. Insgesamt kann eine Reihenfolge beginnend mit dem niedrigsten zum höchsten Kontaktwiderstand aufgestellt werden: Ta < Ti < TaN < TiN « TiO2 « Ta2O5 Desweiteren wurde der Einfluss von Verfahren nach dem CNTWachstum wie die chemischmechanische Planarisierung, eine HF Behandlung und einer Temperaturbehandlung evaluiert, sowie deren Einfluss auf die elektrischen Parameter des Vias untersucht. Die Leitfähigkeit der integrierten CNTs und die daraus resultierenden elektrischen Transporteigenschaften in Abhängigkeit der CNT Qualität und Länge werden besprochen. Ebenso wird die starke Korrelation zwischen dem Temperaturkoeffizienten des elektrischen Widerstandes und des Ausgangswiderstandes der CNT basierten Vias bei Raumtemperatur diskutiert.
49
Claether, Daniel John. "Forces in the knee during vertical jumping and weightlifting." Thesis, Imperial College London, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.530474.
Full text
50
Cornett, Andrew Malcolm. "Short-crested wave forces on a rigid segmented vertical cylinder." Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/26688.
Full textAbstract:
This thesis investigates water particle kinematics and the wave forces exerted on a slender rigid vertical cylinder in regular bidirectional
wave fields. The instrumented portion of this cylinder is partitioned into nine independent segments enabling measurement of the vertical profile of hydrodynamic loading both in-line and transverse to the direction of wave propagation. Experiments conducted at the Hydraulics Laboratory of the National Research Council in Ottawa are described and some results are compared with the predictions of a wave force model based on the Morison equation and linear fluid kinematics. The influence of the crossing angle between the two wave components on the forces experienced by the column is determined.
These experiments consider short-crested wave behavior in intermediate
and deep water resulting from the interaction of two identical regular wave trains crossing at angles of 30, 60 and 90 degrees. The limit corresponding to unidirectional monochromatic waves is also investigated to provide a reference condition for comparison with the short-crested results. Conditions at the location of maximum short-crested wave height are of primary interest, however, forces at locations between the anti-node and node of the flow are also examined. In all, water surface elevations, flow velocities, and wave forces were measured in 24 short-crested and 8 different long-crested wave conditions
spanning the range of Keulegan-Carpenter number between 4 and 24.
The results of this study confirm the findings of previous researchers that short -crested waves with a certain period travel faster and rise higher before breaking than do their long-crested counterparts, but that in-line wave forces are not necessarily increased.
Lift force maxima equal to half the maximum in-line force were measured; these forces can contribute significantly to the magnitude and direction of the total force resultant.Applied Science, Faculty of
Civil Engineering, Department of
Graduate