Thèses : « Biomechanical energy »

1

Denault, Sebastian Ramirez. « Evaluation of smart-fabric approach to biomechanical energy harvesting ». Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/92178.

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Thesis: S.B., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2014.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 35-37).
This thesis evaluates the proposed use of piezoelectric energy harvesting methods as a power source for light-up sneakers. Light-up sneakers currently marketed for purposes of pedestrian visibility and personal fashion are powered by primary or secondary batteries; maintenance requirements could potentially be reduced or eliminated by introducing a renewable power source drawn from the wearer's body. A test was made to determine the possible power levels available from piezoelectric fiber elements mounted on the shoe upper; approximately 10nW of power was developed during walking. In addition to performance in terms of power generated, cost, durability, manufacturability, and user impact also need to be considered before applying this technology.
by Sebastian Ramirez Denault.
S.B.

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Andersson, Erik. « PHYSIOLOGICAL AND BIOMECHANICAL FACTORS DETERMINING CROSS-COUNTRY SKIING PERFORMANCE ». Doctoral thesis, Mittuniversitetet, Avdelningen för hälsovetenskap, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-27898.

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Cross-country (c.c.) skiing is a complex sport discipline from both physiological and biomechanical perspectives, with varying course topographies that require different proportions of the involved sub-techniques to be utilised. A relatively new event in c.c. skiing is the sprint race, involving four separate heats, each lasting 2-4 min, with diverse demands from distance races associated with longer durations. Therefore, the overall aim of the current thesis has been to examine the biomechanical and physiological factors associated with sprint c.c. skiing performance through novel measurements conducted both in the field (Studies I-III) and the laboratory (Studies IV and V). In Study I sprint skiing velocities and sub-techniques were analysed with a differential global navigation satellite system in combination with video recording. In Studies II and III the effects of an increasing velocity (moderate, high and maximal) on the biomechanics of uphill classical skiing with the diagonal stride (DS) (Study II) and herringbone (HB) (Study III) sub-techniques were examined. In Study I the skiers completed the 1,425 m (2 x 712 m) sprint time trial (STT) in 207 s, at an average velocity of 24.8 km/h, with multiple technique transitions (range: 21-34) between skiing techniques (i.e., the different gears [G2-7]). A pacing strategy involving a fast start followed by a gradual slowing down (i.e., positive pacing) was employed as indicated by the 2.9% faster first than second lap. The slower second lap was primarily related to a slower (12.9%) uphill velocity with a shift from G3 towards a greater use of G2. The maximal oxygen uptake ( O2max) was related to the ability to maintain uphill skiing velocity and the fastest skiers used G3 to a greater extent than G2. In addition, maximal speed over short distances (50 and 20 m) with the G3 and double poling (DP) sub-techniques exerted an important impact on STT performance. Study II demonstrated that during uphill skiing (7.5°) with DS, skiers increased cycle rate and cycle length from moderate to high velocity, while cycle rate increased and cycle length decreased at maximal velocity. Absolute poling, gliding and kick times became gradually shorter with an elevated velocity. The rate of pole and leg force development increased with elevated velocity and the development of leg force in the normal direction was substantially faster during skiing on snow than previous findings for roller skiing, although the peak force was similar in both cases. The fastest skiers applied greater peak leg forces over shorter durations. Study III revealed that when employing the HB technique on a steep uphill slope (15°), the skiers positioned their skis laterally (“V” between 25 to 30°) and planted their poles at a slight lateral angle (8 to 12°), with most of the propulsive force being exerted on the inside forefoot. Of the total propulsive force, 77% was generated by the legs. The cycle rate increased across all three velocities (from 1.20 to 1.60 Hz), while cycle length only increased from moderate to high velocity (from 2.0 to 2.3 m). Finally, the magnitude and rate of leg force generation are important determinants of both DS and HB skiing performance, although the rate is more important in connection with DS, since this sub-technique involves gliding. In Studies IV and V skiers performed pre-tests for determination of gross efficiency (GE), O2max, and Vmax on a treadmill. The main performance test involved four self-paced STTs on a treadmill over a 1,300-m simulated course including three flat (1°) DP sections interspersed with two uphill (7°) DS sections. The modified GE method for estimating anaerobic energy production during skiing on varying terrain employed in Study IV revealed that the relative aerobic and anaerobic energy contributions were 82% and 18%, respectively, during the 232 s of skiing, with an accumulated oxygen (O2) deficit of 45 mL/kg. The STT performance time was largely explained by the GE (53%), followed by O2 (30%) and O2 deficit (15%). Therefore, training strategies designed to reduce energetic cost and improve GE should be examined in greater detail. In Study V metabolic responses and pacing strategies during the four successive STTs were investigated. The first and the last trials were the fastest (both 228 s) and were associated with both a substantially larger and a more rapid anaerobic energy supply, while the average O2 during all four STTs was similar. The individual variation in STT performance was explained primarily (69%) by the variation in O2 deficit. Furthermore, positive pacing was employed throughout all the STTs, but the pacing strategy became more even after the first trial. In addition, considerably higher (~ 30%) metabolic rates were generated on the uphill than on the flat sections of the course, reflecting an irregular production of anaerobic energy. Altogether, a fast start appears important for STT performance and high work rates during uphill skiing may exert a more pronounced impact on skiing performance outdoors, due to the reduction in velocity fluctuations and thereby overall air-drag.

Vid tidpunkten för disputationen var följande delarbeten opublicerade: delarbete 5 inskickat

At the time of the doctoral defence the following papers were unpublished: paper 5 submitted

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Horstman, Christopher Larry. « BIOMECHANICAL AND METABOLIC CHANGES WITHIN RABBIT ARTICULAR CARTILAGE FOLLOWING TREATMENT WITH RADIOFREQUENCY ENERGY ». MSSTATE, 2005. http://sun.library.msstate.edu/ETD-db/theses/available/etd-11112005-081324/.

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The effects caused to articular cartilage by the remote use of arthroscopically-delivered RF energy to soft tissues in the joint are unknown. This investigation reported the short and long-term effects of bRF and mRF energy on the biomechanical properties and metabolic activity of articular cartilage. In addition, the effect of Cosequin® therapy was addressed. Thirty New Zealand white rabbits were randomly assigned to one of two treatment groups (Group 1 - placebo; Group 2 - Cosequin®). Histopathology, cell viability, GAG synthesis, and mechanical function of the articular cartilage were compared between groups. Data were analyzed using a mixed model ANOVA (p=0.05). Immediate chondrocyte death was created by both RF devices. This damage was noted to be superficial and did not lead to the progressive deterioration of the extracellular matrix or mechanical function of the articular cartilage. Cosequin® therapy was unable to demonstrate significant differences compared to the control group.

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Dixon, Stacey A. « Biomechanical analysis of coronary arteries using a complementary energy model and designed experiments ». Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/17599.

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Souza, Campos Flavio Ballerini. « Performance assessment of prosthetic heart valves using orifice area formulae and the energy index method ». FIU Digital Commons, 1993. http://digitalcommons.fiu.edu/etd/2432.

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Valve function is commonly assessed by effective orifice area (EOA) estimates using equations derived from conservation of mass and energy. Errors have been found with the method due to difficulties in determining the valve’s coefficient of discharge (Cd). The Cd, a factor that corrects the EOA for losses in the valvular wake region, has been shown previously to vary with the Reynolds number and valve geometry. In this study, a Cardio-Vascular Duplicator (CVD) is used to determine the Cd for three types of mitral valves, operating in modes ranging from normal to severely stenotic. Since orifice area methods do not account for regurgitant flow, the energy index (EI) method is derived and used in experiments with an aortic valve. Results show that the EI method is more powerful than the EOA because a single quantitative parameter is attributed to each valve, taking into account regurgitant, leakage and pressure losses.

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Gonjo, Tomohiro. « A comparison of biomechanical and physiological characteristics between front crawl and back crawl ». Thesis, University of Edinburgh, 2016. http://hdl.handle.net/1842/25462.

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Front crawl (FC) and back crawl (BC) are similar in terms of having alternating contributions of the arms combined with a six beat kick. However, the reason for the faster swimming times of FC than BC has not yet been established. There have been several studies in which the energy expenditure (Ė) of FC and BC were investigated. However, few researchers have compared Ė between the strokes. Also, although there have been some studies for FC using 3D motion analysis, few researchers have applied 3D motion analysis for BC. There have also been some studies in which the relationship between isokinetic torque produced on an isokinetic dynamometer and FC performance has been investigated, however, the relationship between isokinetic torque and BC performance is unclear. Therefore, the aim of this study was to determine why FC is faster than BC by investigating physiological and biomechanical differences between FC and BC. Ten Portuguese male national level swimmers were recruited for this study. Three studies were conducted to achieve the aim. In the first study, Ė of FC and BC at the same testing speed below the anaerobic threshold were investigated by measuring swimmers’ oxygen uptake. Kinematic variables of FC and BC below the anaerobic threshold were also measured by 3D motion analysis in the first study. In the second study, 3D motion kinematics of FC and BC at the same selected speeds were investigated. In the third study, kinematic differences between FC and BC at the same exercise intensities, and correlations between the kinematics and isokinetic muscular torques of the swimmer in FC and BC and their differences were assessed. Below the anaerobic threshold, Ė of the swimmers in BC was significantly greater than that in FC at the same speed although there were no differences in stroke frequency (SF), stroke length (SL) and stroke index (SI). Swimmers also had significantly higher Froude efficiency (ηF) in FC than in BC. Differences in several kinematic variables (range of motion of the foot, duration of non-propulsive phases, and intra-cycle velocity variation) suggested that swimmers expended greater energy in BC than in FC. Differences in other kinematic variables (body roll angle, hand speed/acceleration, yaw angle fluctuation, centre of mass displacement, and hand/foot displacements) suggested the possibility of resistive impulse being larger in BC than in FC during the stroke cycle. Thus, FC is more economical and efficient than BC because swimmers lose less energy to the water during the non-propulsive phase, and possibly have smaller resistive impulse in FC than in BC at speeds below the anaerobic threshold. At the same selected speeds above the anaerobic threshold, ηF in BC was significantly lower than that in FC, which was due to faster mean 3D hand speed during the stroke cycle in BC than in FC. The faster mean hand speed in BC than in FC was due to the faster 3D hand speed during the pull phase, and longer relative duration of the release and above-water phases in BC than in FC. SI was also larger in FC than in BC, which was due to longer SL in FC than in BC. The longer SL in FC than in BC was due to the longer duration of propulsive phases and probably smaller resistive impulse during the stroke cycle in FC than in BC. At the same selected exercise intensities, FC was faster than BC because of higher SF. The higher SF in FC than in BC was due to the longer duration of the above-water phase in BC than in FC, longer hand path distance during non-propulsive phases in BC than in FC, earlier timing of the hand entry in relation to the underwater phase of the other hand in FC than in BC. SF in both FC and BC was significantly correlated with shoulder adduction isokinetic torque of the swimmers, however, the effect of shoulder isokinetic torque on the difference in swimming performance between FC and BC required further investigation. In conclusion, FC is faster than BC because swimmers can achieve higher SF in FC than in BC, and FC is more economical and efficient than in BC with indirect evidence that resistive force are greater in BC than in FC.

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Eng, Carolyn Margaret. « An Anatomical and Biomechanical Study of the Human Iliotibial Band's Role in Elastic Energy Storage ». Thesis, Harvard University, 2014. http://dissertations.umi.com/gsas.harvard:11621.

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The iliotibial band (ITB) is a complex structure that is unique to humans among apes and is derived from the fascia lata (FL) of the thigh. Although the ITB evolved in the hominin lineage, it is unclear whether it evolved to improve locomotor economy, increase stability, or serve a different function. This dissertation tests the hypothesis that the ITB stores and recovers elastic energy during walking and running.
Human Evolutionary Biology

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Hall, Michael G. « Biomechanical and energy analysis of the ischial containment and quadrilateral sockets for the trans femoral amputee ». Thesis, University of Strathclyde, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248527.

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Marconi, Francesco. « Analysis of biomechanical in vitro tests on the human ribs ». Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/18581/.

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In questa Tesi viene descritto il processo di elaborazione dei dati ottenuti su costole umane sottoposte ad un carico flessionale e motiva i risultati ottenuti, con l’obiettivo di ottenere una loro caratterizzazione meccanica. L’elaborazione dei dati è stata suddivisa in tre fasi, che permettono uno studio dal punto di vista meccanico delle costole dall’aspetto globale fino a quello specifico. Dall’analisi globale si è potuto osservare un particolare andamento dei valori di carico di rottura e modulo elastico al variare delle posizioni delle costole nella gabbia toracica mentre i valori delle deformazioni calcolati dalle correlazioni non hanno prodotto alcun risultato notevole, se non indicare la presenza di un momento torcente agente sui provini oltre a quello flessorio impostato. I dati delle micro-CT invece confermano quanto detto legando le caratteristiche meccaniche ad una certa quantità di tessuto osseo. Inoltre i valori del rapporto Bone volume/Tissue volume indicano una possibile relazione sia con i carichi di rottura che con i moduli elastici.

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Fernandes, Fábio António Oliveira. « Biomechanical analysis of helmeted head impacts : novel materials and geometries ». Doctoral thesis, Universidade de Aveiro, 2017. http://hdl.handle.net/10773/21227.

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Doutoramento em Engenharia Mecânica
A cortiça é um material celular natural capaz de suster quantidades consideráveis de energia. Estas características tornam este material ideal para determinadas aplicações como a proteção de impactos. Considerando equipamentos de segurança passiva pessoal, os materiais sintéticos são hoje em dia os mais utilizados, em particular o poliestireno expandido. Este também é capaz de absorver razoáveis quantidades de energia via deformação permanentemente. Por outro lado, a cortiça além de ser um material natural, é capaz de recuperar grande parte da sua forma após deformada, uma característica desejada em aplicações com multi-impacto. Neste trabalho é efetuada uma avaliação da aplicabilidade da cortiça em equipamentos de segurança pessoal, especificamente capacetes. Vários tipos de cortiça aglomerada foram caracterizados experimentalmente. Impactos foram simulados numericamente para avaliar a validade dos modelos constitutivos e as propriedades utilizadas para simular o comportamento da cortiça. Capacetes foram selecionados como caso de estudo, dado as energias de impacto e repetibilidade de impactos a que estes podem ser sujeitos. Para avaliar os capacetes de um ponto de vista biomecânico, um modelo de cabeça humana em elementos finitos foi desenvolvido. Este foi validado de acordo com testes em cadáveres existentes na literatura. Dois modelos de capacete foram modelados. Um modelo de um capacete rodoviário feito de materiais sintéticos, o qual se encontra disponível no mercado e aprovado pelas principais normas de segurança de capacetes, que serve de referência. Este foi validado de acordo com os impactos da norma. Após validado, este foi avaliado com o modelo de cabeça humana em elementos finitos e uma análise ao risco de existência de lesões foi efetuado. Com este mesmo capacete, foi concluído que para incorporar cortiça aglomerada, a espessura teria de ser reduzida. Então um novo modelo de capacete foi desenvolvido, sendo este uma espécie de modelo genérico com espessuras constantes. Um estudo paramétrico foi realizado, variando a espessura do capacete e submetendo o mesmo a duplos impactos. Os resultados destes impactos e da análise com o modelo de cabeça indicaram uma espessura ótima de 40 mm de cortiça aglomerada, com a qual o capacete tem uma melhor resposta a vários impactos do que se feito de poliestireno expandido.
Cork is a natural cellular material capable of withstanding considerable amounts of energy. These features make it an ideal material for some applications, such as impact protection. Regarding personal safety gear, synthetic materials, particularly expanded polystyrene, are typically used. These are also able to absorb reasonable amounts of energy by deforming permanently. On the other hand, in addition to cork being a natural material, it recovers almost entirely after deformation, which is a desired characteristic in multi-impact applications. In this work, the applicability of agglomerated cork in personal safety gear, specifically helmets, is analysed. Different types of agglomerated cork were experimentally characterized. These experiments were simulated in order to assess the validity of the constitutive models used to replicate cork's mechanical behaviour. In order to assess the helmets from a biomechanical point of view, a finite element human head model was developed. This head model was validated by simulating the experiments performed on cadavers available in the literature. Two helmet models were developed. One of a motorcycle helmet made of synthetic materials, which is available on the market and certified by the main motorcycle helmets safety standards, being used as reference. This helmet model was validated against the impacts performed by the European standard. After validated, this helmet model was analysed with the human head model, by assessing its head injury risk. With this helmet, it was concluded that a thinner helmet made of agglomerated cork might perform better. Thus, a new helmet model with a generic geometry and a constant thickness was developed. Several versions of it were created by varying the thickness and subjecting them to double impacts. The results from these impacts and the analyses carried out with the finite element head model indicated an optimal thickness of 40 mm, with which the agglomerated cork helmet performed better than the one made of expanded polystyrene.

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Doulgeris, James. « Biomechanical Comparison of Titanium and Cobalt Chromium Pedicle Screw Rods in an Unstable Cadaveric Lumbar Spine ». Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4812.

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Pedicle screw-rod instrumentation is considered a standard treatment for spinal instability, and titanium is the most common material for this application. Cobalt-chromium has several advantages over titanium and is generating interest in orthopedic practice. The aim of this study was to compare titanium versus cobalt-chromium rods in posterior fusion, with and without transverse connectors, through in vitro biomechanical testing and determine the optimal configuration. Six cadaveric lumbar spines (L1-S1) were used. Posterior and middle column injuries were simulated at L3-L5 and different pedicle screw constructs were implanted. Specimens were subjected to flexibility tests and range of motion, intradiscal pressure and axial rotation energy loss were statistically compared among the following conditions: intact, titanium rods (without transverse connectors), titanium rods with transverse connectors, cobalt-chromium rods (without transverse connectors) and cobalt-chromium rods with transverse connectors. The novel measurement of energy loss was examined to determine its viability in fusion investigations. All fusion constructs significantly (p0.05) were observed in axial rotation among all conditions. Intradiscal pressure significantly increased (p≤0.01) after fusion, except for the cobalt-chrome conditions in extension (p≥0.06), and no significant differences (p>0.99) were found among fixation constructs. Energy loss, differences became significant between the cobalt-chrome with transverse connector condition with respect to the cobalt-chrome (p=0.05) and titanium (p There is not enough evidence to support that the cobalt-chrome rods performed biomechanically different than the titanium rods. The use of titanium rods may be more beneficial because there is a lower probability of corrosion. The inclusion of the transverse connector only increased stability for the cobalt-chromium construct in axial rotation, which suggests that it is beneficial in complete facetectomy procedures.

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Cai, Renye. « Original strain energy density functions for modeling of anisotropic soft biological tissue ». Thesis, Bourgogne Franche-Comté, 2017. http://www.theses.fr/2017UBFCA003/document.

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Cette thèse a porté sur la construction de densités d'énergie de déformation permettant de décrire le comportement non linéaire de matériaux anisotropes tels que les tissus biologiques souples (ligaments, tendons, parois artérielles etc.) ou les caoutchoucs renforcés par des fibres. Les densités que nous avons proposées ont été élaborées en se basant sur la théorie mathématique des polynômes invariants et notamment sur le théorème de Noether et l'opérateur de Reynolds. Notre travail a concerné deux types de matériaux anisotropes, le premier avec une seule famille de fibre et le second avec quatre familles. Le concept de polyconvexité a également été étudié car il est notoire qu'il joue un rôle important pour s'assurer de l'existence de solutions. Dans le cas d'un matériau comportant une seule famille de fibre, nous avons démontré qu'il était impossible qu'une densité polynomiale de degré quelconque puisse prédire des essais de cisaillement avec un chargement parallèle puis perpendiculaire à la direction des fibres. Une densité polynomiale linéaire combinée avec une fonction puissance a permis de contourner cet obstacle. Dans le cas d'un matériau comportant quatre familles de fibre, une densité polynomiale a permis de prédire correctement des résultats d'essai en traction bi-axiale extraits de la littérature. Les deux densités proposées ont été implémentées avec la méthode des éléments finis et en langage C++ dans le code de calcul universitaire FER. Pour se faire, une formulation lagrangienne totale a été adoptée. L'implémentation a été validée par des comparaisons avec des solutions analytiques de référence que nous avons exhibée dans le cas de chargements simples conduisant à des déformations homogènes. Des exemples tridimensionnels plus complexes, impliquant des déformations non-homogènes, ont également été étudiés
This thesis has focused on the construction of strain energy densities for describing the non-linear behavior of anisotropic materials such as biological soft tissues (ligaments, tendons, arterial walls, etc.) or fiber-reinforced rubbers. The densities we have proposed have been developed with the mathematical theory of invariant polynomials, particularly the Noether theorem and the Reynolds operator. Our work involved two types of anisotropic materials, the first with a single fiber family and the second with a four-fiber family. The concept of polyconvexity has also been studied because it is well known that it plays an important role for ensuring the existence of solutions. In the case of a single fiber family, we have demonstrated that it is impossible for a polynomial density of any degree to predict shear tests with a loading parallel and then perpendicular to the direction of the fibers. A linear polynomial density combined with a power-law function allowed to overcome this problem. In the case of a material made of a four-fiber family, a polynomial density allowed to correctly predict bi-axial tensile test data extracted from the literature. The two proposed densities were implemented in C++ language in the university finite element software FER by adopting a total Lagrangian formulation. This implementation has been validated by comparisons with reference analytical solutions exhibited in the case of simple loads leading to homogeneous deformations. More complex three-dimensional examples, involving non-homogeneous deformations, have also been studied

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Roser, Alexandra. « An Analysis of Including the Evolution Law for the Serial Element in the Musculoskeletal Modelling ». Thesis, Linköpings universitet, Mekanik och hållfasthetslära, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-172282.

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In the classic Hill model for muscle contraction, the split between the muscle and tendon is arbitrary and the problem lacks a unique solution. Instead of reformulating the problem to a differential-algebraic equation and solving for a set of initial conditions, a constant tendon length is commonly assumed in musculoskeletal simulation tools. This assumption has not been thoroughly tested and introduces errors of unknown magnitude to the simulations. In this thesis, the contractile element of the Hill model is modelled as a friction clutch in parallel to a viscous damper. This provides an evolution law for the muscle length by which the muscle speed is numerically calculated taking into account a non-zero tendon speed. A simple biceps curl is simulated with the friction clutch model and compared to corresponding commercial musculoskeletal simulations. Overall, the results are similar, in particular for the muscle lengths which are almost identical in every simulation (0.00-0.42% difference). The difference in tendon speed is 0.00-3.26%, with upwards tendencies. In general, the error percentage of the tendon speed appears to decrease by the same amount that the contraction speed is reduced. Conclusively, it can be said that the introduced friction clutch model delivers comparative outcomes to a commercial musculoskeletal simulation software, while not assuming a constant tendon length. However, while presenting a relatively simple solution, an increased computation time is to be expected due to the need of a differential equation solver. Further investigation regarding implementation and computing times in more complex simulations may provide an alternative approach to conventional musculoskeletal simulations.

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Bouzid, Asma. « Conception de micro-générateur piézoélectrique pour des micro-dispositifs médicaux autonomes ». Electronic Thesis or Diss., Université de Rennes (2023-....), 2024. http://www.theses.fr/2024URENS106.

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Cette thèse vise à développer un système intégré et autonome en utilisant la technologie piézoélectrique soit pour l’actionnement ou pour la récupération d’énergie. Nous avons testé cette configuration sur un Lab on Chip (LOC) destiné à des applications médicales et environnementales. Ce LOC est utilisé pour la surveillance des polluants et des toxines dans des échantillons d'eau ou d'air. Pour assurer son bon fonctionnement, le LOC doit intégrer trois éléments essentiels : un système de fluidique, un système de détection et un système d'alimentation. La combinaison de ces trois composantes primordiales permet d'obtenir un dispositif autonome et totalement intégré. Dans le cadre de ce travail de recherche, deux systèmes sont mis en place : le système fluidique et le système d'alimentation. Au sein du premier système, une micro pompe à une membrane piézoélectrique a été étudiée à travers des analyses théoriques et des simulations sur COMSOL Multiphysics, confirmant la capacité du design choisi à pomper des débits importants de deux types de fluides, notamment les gaz et les liquides. Les résultats obtenus de cette étude ont montré que la micro pompe capable de fonctionner à des tensions faibles tout en manipulant des débits importants, pouvant aller jusqu'à plusieurs dizaines de microlitres. Cette capacité permet de répondre aux exigences en matière de quantité de fluide nécessaire à la circulation dans la zone de détection du système de laboratoire sur puce. Une puissance énergétique de l’ordre milliwatt a été calculé pour le bon fonctionnement de la micro pompe et ses modules électroniques. Pour répondre aux exigences énergétiques du système, un micro générateur piézoélectrique a également été développé. Ce dispositif convertit l'énergie biomécanique générée par la flexion du genou en énergie électrique, à travers une poutre piézoélectrique fixée à la face arrière du genou. Pendant la marche, la flexion du genou se transforme en énergie électrique, laquelle est ensuite mise en forme par un circuit redresseur de type AC-DC, rendant cette puissance exploitable par les composants électroniques du système. Les résultats obtenus de cette conversion indiquent que les niveaux de puissance générés augmentent avec l'intensité de la flexion du genou, atteignant des valeurs de dizaines de milliwatts qui se situent dans la plage nécessaire pour garantir un fonctionnement continu et en temps réel de système fluidique. Cette approche contribue à la réalisation d'un système intégré et autonome, optimisé tant sur le plan énergétique que fonctionnel
This thesis aims to develop an integrated and autonomous system using piezoelectric technology for both actuation and energy harvesting. We have applied this configuration in a Lab on Chip (LOC) designed for medical and environmental applications. This LOC is used for monitoring pollutants and toxins in water or air samples. To ensure its optimal functionality, the LOC must integrate three key components: a fluidic system, a detection system, and a power supply system. The combination of these essential elements results in a fully autonomous and integrated device. This research work focuses on the establishment of two systems: the fluidic system and the power supply system. Within the first system, a piezoelectric membrane micropump has been studied through theoretical analyses and simulations using COMSOL Multiphysics, confirming the design's capability to pump significant flows of two types of fluids, namely gases and liquids. The results of this study demonstrated that the micropump can operate at low voltages while handling substantial flow rates, reaching up to several tens of microliters. This capability addresses the fluid quantity requirements necessary for circulation in the detection area of the Lab on Chip system. An energy requirement of the order of milliwatts has been calculated for the proper functioning of the micropump and its associated electronic modules. To meet the system's energy demands, a piezoelectric microgenerator has also been developed. This device converts biomechanical energy generated by knee flexion into electrical energy through a piezoelectric beam attached to the back of the knee. During walking, the flexion of the knee transforms into electrical energy, which is then rectified by an AC-DC circuit, making this power usable by the system's electronic components. The results obtained from this conversion indicate that the generated power levels increase with the intensity of knee flexion, reaching values in the tens of milliwatts, which fall within the necessary range to ensure continuous and real-time operation of the fluidic system. This approach contributes to the realization of an integrated and autonomous system, optimized both in terms of energy efficiency and functionality

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Argunsah, Bayram Hande. « Biomechanics of Prosthetic Knee Systems : Role of Dampening and Energy Storage Systems ». Cleveland State University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=csu1371689387.

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Roach, Neil. « The Biomechanics and Evolution of High-Speed Throwing ». Thesis, Harvard University, 2012. http://dissertations.umi.com/gsas.harvard:10609.

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Throwing with power and accuracy is a uniquely human behavior and a potentially important mode of early hunting. Chimpanzees, our closest living relatives, do occasionally throw, although with much less velocity. At some point in our evolutionary history, hominins developed the ability to produce high performance throws. The anatomical changes that enable increased throwing ability are poorly understood and the antiquity of this behavior is unknown. In this thesis, I examine how anatomical shifts in the upper body known to occur during human evolution affect throwing performance. I propose a new biomechanical model for how humans amplify power during high-speed throwing using elastic energy stored and released in the throwing shoulder. I also propose and experimentally test a series of functional hypotheses regarding how four key shifts in upper body anatomy affect throwing performance: increased torso rotational mobility, laterally oriented shoulders, lower humeral torsion, and increased wrist hyperextensability. These hypotheses are tested by collecting 3D body motion data during throws performed by human subjects in whom I varied anatomical parameters using restrictive braces to examine their effects on throwing kinematics. These data are broken down using inverse dynamics analysis into the individual motions, velocities, and forces acting around each joint axis. I compare performance at each joint across experimental conditions to test hypotheses regarding the relationship between skeletal features and throwing performance. I also developed and tested a method for predicting humeral torsion using range of motion data, allowing me to calculate torsion in my subjects and determine its effect on throwing performance. My results strongly support an important role for elastic energy storage in powering humans’ uniquely rapid throwing motion. I also found strong performance effects related to anatomical shifts in the torso, shoulder, and arm. When used to interpret the hominin fossil record, my data suggest high-speed throwing ability arose in a mosaic-like fashion, with all relevant features first present in Homo erectus. What drove the evolution of these anatomical shifts is unknown, but as a result the ability to produce high-speed throws was available for early hunting and likely provided an adaptive advantage in this context.
Anthropology

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McNally, Michael P. « Energetic Contributions to Performance and Upper Extremity Joint Kinetics in Baseball Pitching ». The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1543411893186982.

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Shadfan, Ramsey Harbi. « On the Energy Conserved in a Buckling Fung Hyperelastic Cylindrical Shell Subjected to Torsion, Internal Pressure and Axial Tension ». Thesis, The University of Texas at San Antonio, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10928944.

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A theoretical model is proposed for the buckling of a three-dimensional vein subjected to torsion, internal pressure, and axial tension using energy conservation methods. The vein is assumed to be an anisotropic hyperelastic cylindrical shell which obeys the Fung constitutive model. Finite deformation theory for thick-walled blood vessels is used to characterize the vessel dilation in the pre-buckling state.

The pre-buckling state is identified by its midpoint and then perturbed by a displacement vector field dependent on the circumferential and axial directions to define the buckled state. The total potential energy functional of the system is extremized by minimizing the first variation with respect to the elements of the set of all continuous bounded functions on R ³. The Euler-Lagrange equations form three coupled linear partial differential equations with Dirichlet boundary conditions characterizing the buckling displacement field under equilibrium.

A second solution method approximates the first variation of the total potential energy functional using a variational Taylor series expansion. The approximation is minimized and combined with equations of equilibrium derived from elasticity theory to yield a polynomial relating buckling eigenmodes, material parameters, geometric parameters, and the critical angle of twist which induces buckling. Various properties of the total potential energy functional specific to the problem are proved. Another solution method is outlined using the first variation approximation and the basis of the kernel of the linear transformation which maps buckling displacement amplitudes during static equilibrium.

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Seidel, Laura Ann. « Investigation of Brass Tubes as Energy Damper in the Underbody Blast Environment ». The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1492605643550189.

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Knezevic, Steven. « Energy expenditure during gait using the rewalk exoskeletal-assisted walking system for persons with paraplegia ». Thesis, The William Paterson University of New Jersey, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=1553060.

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The purpose of this study was to evaluate energy expenditure (EE) during powered exoskeleton–assisted walking in persons with paraplegia. Five male participants with paraplegia, aged 37–61 years, were recruited for this study. Able–bodied (AB) subjects were matched for height (±12.7 cm) weight (±6.8 kgs) and age (±5 yrs) were recruited to serve as a control group. EE measurements were obtained for 6 minutes while: seated, standing, walking, and seated recovery for three trials (Pre, Mid, Post) over 60 sessions. A portable metabolic cart was used to obtain all metabolic measurements. The results from this study suggest that over the course of 60 sessions, powered exoskeletal–assisted walking can: significantly improve an individual's oxygen consumption (p=0.04), significantly decrease RPE (p<0.001), and significantly increase the distance traveled per 6MWT (p=0.02). These improvements may potentially further enhance the quality of life of persons with paraplegia.

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Cruz, Folgar Ricardo Francisco. « Energy Harvesting from Human Body, Motion and Surroundings ». Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/102604.

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As human dependence on electronic devices grows, there is an emerging need on finding sustainable power sources for low power electronics and sensors. One of the promising possibilities in this space is the human body itself. Harvesting significant power from daily human activities will have a transformative effect on wearables and implantables. One of the main challenges in harvesting mechanical energy from human actions is to ensure that there is no effect on the body itself. For this reason, any intrusive mechanism will not have practical relevance. In this dissertation, novel non-intrusive energy harvesting technologies are investigated that can capture available energy from body, motion, and surroundings. Energy harvesting from the body is explored by developing a wrist-based thermoelectric harvester that can operate at low-temperature gradients. Energy harvesting from motion is investigated by creating a backpack and shoe sole. These devices passively store kinetic energy in a spring that is later released to a generator when it is not intrusive to the user kinematics. Lastly, energy harvesting from immediate surroundings is investigated by designing a two degree of freedom vibration absorber that is excited by electromagnetic fields found in common household appliances. These novel solutions are shown to provide consistent electrical power from wasted energy. Harvester designs are extensively modeled and optimized device architectures are manufactured and tested to quantify the relevant parameters such as output voltage and power density.
Doctor of Philosophy

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Long, Leroy L. III. « An Experiment in Human Locomotion : Energetic Cost and Energy-Optimal Gait Choice ». The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1313584497.

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Sharpes, Nathan Lowell. « Energy Harvesting from Human Motion for the Powering of Implantable, Wearable, and Peripheral Electronic Devices ». Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/82509.

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In the past two decades, the miniaturization of highly functional electronic devices has yielded the present condition where such devices are light enough, have a long enough battery life, are robust enough, and even stylish enough to be utilized for extended periods of time. Such devices can monitor activity and various bodily vital signs, and/or provide assistive actions. Due to the interrelationship between persons and assistive electronic devices, it is examined whether the actions (human motion) themselves can be used to power the electronic devices assisting those very actions. Such functionality results in a synergistic win-win interaction, rare in energy systems where trade-offs are pervasive. These interactions are studied in the context of the three types of solution spaces in implantable (inside the body), wearable (on the body), and peripheral (outside the body) devices. Specifically, it is studied whether heartbeats can power the pacemakers regulating the heartbeat; whether walking can power the portable communication equipment guiding the path; and whether movement within a smart building can power the occupancy measurement in automatic occupancy-drive lighting and climate control systems making the building habitable yet energy efficient. Novel energy harvesting solutions are developed for each category, with the impetus of harvesting sufficient energy to perform the desired function without encumbering the body.
Ph. D.

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Moradi, Rasoul. « Impact dynamics of mechanical systems and structures, and applications in crash energy management, impulse mitigation, and impact injury biomechanics ». Diss., Wichita State University, 2012. http://hdl.handle.net/10057/5363.

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Among the different load conditions on a mechanical system, impact loading and its contribution to the design process require special consideration. The static methods of stress, strain, and deflection analyses are not applicable under impact conditions. The main goal of this study is to address the fundamental aspects of impact and to examine its applications for different design requirements. First, different approaches to the impact phenomena, namely stereomechanics, contact mechanics, stress wave propagation, finite element method, and energy method are investigated in this dissertation. The advantages and disadvantages of each method are pointed out, and the areas of application of each method and the degree of accuracy are examined. Quantification of energy absorption during impact is the most complicated part of impact modeling and is one of the topics of interest addressed in this dissertation. Application of the impact analysis methodologies in vehicular accidents and protection of occupants are the eventual goals of this research, demonstrated using some case studies and applicable examples. Because occupant safety is a major concern in the automobile and aerospace industries, a crashworthy design must be able to dissipate the kinetic energy of impact in a controlled manner. Four test cases or applications related to impact energy management or dissipation, impulse mitigation, and impact injury biodynamics are thus presented. The application examples include the design of a truck side guard and quantification of its effects on reducing occupant injury in the collison of a small car with a truck; lumbar load attenuation for seated occupants of a rotorcraft; injuries to pedestrians impacted by a sport or utility vehicle equipped with a frontal guard; and investigation of a motorcyclist impact with roadside barriers. For each case, an analysis methodolgy is developed, and from the modeling and simulations, impact design issues are addressed.
Thesis (Ph.D.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering

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Willener, Astrid S. T. « Uncovering the onshore life of king penguins via energy expenditures : understanding their physiological stress response and the biomechanics of their pedestrian locomotion ». Thesis, University of Roehampton, 2014. https://pure.roehampton.ac.uk/portal/en/studentthesis/uncovering-the-onshore-life-of-king-penguins-via-energy-expenditures(fcb8f2bd-60e7-4c37-a2d1-132f1e2f87cf).html.

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Measuring energy expenditure using respirometery, heart rate and accelerometry can enable hitherto unknown aspects of a species’ energetic ecology to be uncovered. Due to the increased use of these methods, rigour is required to improve the accuracy of the results. As they can only feed in the sea, King penguins (Aptenodytes patagonicus) need to manage their onshore energetic budget well. During fasting periods, which can last up to one month, heavy individuals need to walk several kilometres to reach their zone of attachment, where they incubate and take care of the egg 24 hours a day. They then need to have sufficient energy reserves to return to sea, swim to the polar front and efficiently fish for prey. Consequently, knowing the energy expenditure of king penguins while onshore is key for understanding their future survival. By investigating the onshore energy expenditure of king penguins, this thesis generates new insights not only into their physiological stress response and the biomechanics of pedestrian locomotion, but also into proxy-based methods of measuring energy expenditure. The cardio-respiratory stress response was defined for this species, with some surprising findings, and the energetic cost of the stress response was demonstrated. Implications for the confounding effect of stressed states on energy proxy calibrations were considered and a standard protocol to alleviate this issue in future studies of king penguin energetics is proposed. The biomechanics and energetics of the pedestrian locomotion were investigated to enhance the understanding of the mechanisms developed to optimise king penguin gait in relation to their body mass. Following investigation of differences in walking between heavy and light penguins, no conclusive explanations were established, though future investigations are suggested to enhance this learning. Finally, using the data collected throughout the thesis, the energy expenditure of early and late breeders was investigated, enabling a better understanding of their energy budgets which can be fed into conservation projects for king penguins.

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Schroeder, Ryan T. « Gait entrainment in coupled oscillator systems : Clarifying the role of energy optimization in human walking ». Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2020. https://ro.ecu.edu.au/theses/2281.

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Empirical evidence suggests that parameters of human gait (e.g. step frequency, step length) tend to minimize energy expenditure. However, it is unclear if individuals can adapt to dynamic environments in real time, i.e. continuously optimize energy expenditure, and to what extent. Two coupled oscillator systems were used to test the learned interactions of individuals within dynamic environments: (1) experienced farmworkers carrying oscillating loads on a flexible bamboo pole and (2) individuals walking on a treadmill while strapped to a mechatronics oscillator system providing periodic forces to the body. Reductionist trajectory optimization models predicted energy-minimizing gait interactions within the coupled oscillator systems and were compared to experimental data assessed with linear mixed models. On average, pole carriers significantly adjusted step frequency by 3.3% (0.067 Hz, p=0.014) to accommodate the bamboo pole – consistent with model predictions of energy savings. Novice subjects entrained (i.e. synchronized) their step frequency with machine oscillations up to ±10% of preferred step frequency and at amplitudes as low as 5% body weight (or ~33 N). Still, some subjects rarely entrained at all, and many exhibited transient entrainment, i.e. they drifted in and out of step frequencies matching the machine oscillations. Overall, subject entrainment was more robust and consistent with lower frequencies and higher amplitudes (20-30% of body weight). Although no systematic difference was found between the metabolic consumption of subjects during and not during entrainment, the net mechanical work done on subjects by the force oscillations had a strong effect on metabolic output (p

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Dinato, Roberto Casanova. « A influência de diferentes sistemas de amortecimento do calçado esportivo na economia de corrida e no desempenho ». Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/39/39135/tde-20062018-095440/.

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O objetivo geral do estudo foi investigar o impacto do calçado minimalista e dos calçados esportivos com entressola de termoplástico Poliuretano expandido (TPE) sobre os parâmetros fisiológicos e o desempenho durante a corrida. O estudo 1 comparou o calçado minimalista e o calçado com TPE na economia de corrida (EC) e o desempenho. Doze corredores homens foram submetidos aos seguintes testes: a) teste progressivo até a exaustão para caracterização da amostra; b) duas corridas contrarrelógio de 3 km em uma pista de atletismo de 400 m e ao final dos testes responderam uma avaliação de conforto. c) quatro testes de corrida submáxima de 6 minutos em uma esteira para determinar a EC, o custo de oxigênio (CTO2) e a componente vertical da força reação do solo. Houve uma maior EC (~2,4%) (P = 0,01), aumento do primeiro pico (~15,8%) (P = 0,01) e diminuição da taxa de propulsão (~15,9%) (P = 0,01) no TPE em comparação ao calçado minimalista. No entanto, não houve diferenças significativas entre TPE e minimalistas para CTO2 (P = 0,61) e desempenho total de corrida (P = 0,61). Essas descobertas revelaram que o calçado TPE produz uma EC maior e uma taxa de propulsão mais baixa em comparação com calçados minimalistas, mas essas melhorias não foram acompanhadas por mudanças no CTO2 e, consequentemente, no desempenho na corrida. O estudo 2 comparou 3 calçados com diferenças percentuais de TPE inserido na entressola. As principais diferenças metodológicas foram a análise da EMG e o teste de corrida de 10 km. Não houve diferença estatística entre os calçados para as variáveis EC, componente vertical da força reação do solo (FRS), EMG e desempenho. A análise de regressão revelou que 96% do desempenho em uma prova de 10 km podem ser explicados pelas variáveis altura do arco e controle médio-lateral para o modelo de calçado TPE 55%. Nenhuma variável biomecânica analisada neste estudo foi capaz de identificar alguma diferença que pudesse estabelecer uma diferença entre os calçados que repercutisse em desempenho ou EC. Os resultados práticos dos estudos revelaram que correr com calçado TPE melhora a EC em comparação ao calçado minimalista. No entanto, a melhora na EC não se refletiu em desempenho no teste de corrida de 3 km. Diferentes porcentagens de TPE inseridos na entressola do calçado não produziram diferenças na EC e desempenho em uma prova de 10km. Desta forma, ainda não é possível dizer qual calçado é capaz de reduzir o tempo gasto em uma prova de corrida de curta ou longa duração
The overall objective of the study was to investigate the impact of minimalist footwear and sports shoes with midsole thermoplastic expanded polyurethane (TPE) on physiological parameters and performance during running. Study 1 compared minimalist shoes and TPE shoes in running economy and performance. Twelve male distance runners performed the following tests: a) a maximal incremental test to characterize the sample; b) two 3-km time-trials on an outdoor 400 m track and at the end of tests answered an evaluation of comfort. c) four 6-min submaximal running tests on a treadmill to determine the RE, energetic cost (CTO2) of 3 km running time-trial and ground reaction force parameters. The athletes performed the sub-maximal running tests and 3-km time trials using the TPE and minimalist shoes. There was a higher RE (~2.4%) (P = 0.01), increased first peak (~15.8%) (P = 0.01), and decrease push-off rate (~15.9%) (P = 0.01) in TPU compared with minimalist shoes. However, there were not significant differences TPU and minimalist shoes for CTO2 (P = 0.61) and overall running performance (P = 0.61). These findings revealed that TPU produces a higher RE and a lower push-off rate when compared to minimalist shoes, but these improvements were not accompanied by changes in CTO2 and, consequently in running performance. Study 2 compared 3 shoes with differences percentage TPE inserted in the midsole. The main methodological differences were the EMG analysis and the 10 km running time-trial. There was no statistical difference between shoes for the EC, vertical component of ground reaction force and EMG. Regression analysis revealed that 96% of the performance in a 10 km running time-trial can be explained by the variable height of the arch and medial-lateral control to the shoe model TPE 55%. No biomechanical variable analyzed in this study was able to identify any differences that could establish a difference between the shoes that had repercussions on RE or performance. The practical results of the studies have shown that running with TPE improves the RE compared to minimalist shoes. However, the improvement in RE was not reflected in performance in the 3-km running time-trial. Different percentages of TPE inserted in the shoe midsole did not produce differences in RE and performance in a 10km running time-trial. Thus, it is not possible to tell which shoes is able to reduce the time spent on a short or long running race

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Murgatroyd, J. « Impact energy absorption of playground surfaces ». Thesis, Queensland University of Technology, 1998.

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King, Jason. « Energy Release Management Through Manipulated Geometries of Surgical Devices ». University of Akron / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=akron1342730044.

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GRIMPAMPI, ELENI. « An integrated approach to whole-body vibration ». Doctoral thesis, Università degli Studi di Roma "Tor Vergata", 2009. http://hdl.handle.net/2108/897.

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Obiettivo di questa tesi è la determinazione e quantificazione degli effetti della whole-body vibration al corpo umano, in termini di consumo energetico, tramite un approccio globale e integrato. L’obiettivo è ottenuto considerando il corpo umano come una struttura organica complessa. Allo scopo di comprendere come questo risponda alle vibrazioni verticali, il consumo energetico del corpo umano è stato misurato per mezzo della variazione della temperatura superficiale con tecniche di misurazione a termografia infrarossa. Lo spostamento dei muscoli invece con il sistema di analisi di movimento Vicon MX. Infine, per quanto riguarda il consumo di ossigeno con il sistema telemetrico Cosmed K4. Il primo passo è stato l’istituzione di un protocollo appropriato che soddisfi l’obiettivo di questo studio. Infatti, la mancanza di coerenza nei protocollo di whole-body vibration che si trovano allo stato dell’arte, ha reso essenziale l’istituzione di un apposito protocollo, ed a questo scopo è stata definita la struttura dell’esperimento. Di conseguenza, è stata avviata una serie di prove per esaminare la risposta del corpo umano alle vibrazioni verticali, cambiando la durata e la frequenza della vibrazione, nonché la durata del periodo di riposo. In totale, quattro persone in piedi sono state sottoposte a vibrazioni verticali, in una pedana vibrante, a frequenze da 20 a 50 Hz. Dopo l’instaurazione del protocollo finale, sono stati avviate una serie di prove di laboratorio. In particolare, sono state scelte tre frequenze per le vibrazioni: 20, 30 e 45 Hz. I risultati ottenuti più interessanti di questo studio, riguardano il consumo di ossigeno, la temperatura superficiale e i coefficienti di trasmissibilità dell’accelerazione.
The objective of this thesis is to determine and quantify the effects of whole-body vibration to the human body in terms of energy expenditure, by means of a global and integrated approach. This objective is attained by considering the human body as a complex organic structure. In order to understand how it responds to vertical vibrations, the energy expenditure of the human body was measured by means of the variation in superficial temperature with the aid of infrared thermography, the displacement of the muscles with the aid of the Vicon MX motion analysis system and the oxygen uptake with the aid of the Cosmed K4 telemetric system. The establishment of an appropriate protocol which satisfies the aim of this study was the first goal. The lack of consistency in whole-body vibration protocols in the current published studies makes the establishment of an appropriate protocol essential, and in this sense, an experiment setup was implemented. Therefore, a series of experiments was conducted to examine the response of the human body to vertical vibrations, changing the duration and the frequency of vertical vibration, and the duration of rest period. A number of four persons were subjected to vertical vibrations on a vibrating table in a standing position at a frequency ranging from 20 to 50 Hz. After the establishment of the final protocol, a series of laboratory experiments took place. Three different vibration frequencies were chosen: 20, 30 and 45 Hz corresponding to three different tests. The most interesting findings regard the oxygen consumption, the superficial temperature evolution, and the transmissibility coefficients for the acceleration.

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Arsenovic, Paul. « Development and Validation of a Novel Resonant Energy Transfer (FRET) Biosensor to Measure Tensile Forces at the LINC Complex in Live Cells ». VCU Scholars Compass, 2017. https://scholarscompass.vcu.edu/etd/5116.

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There is a large body of evidence supporting the theory that cell physiology largely depends on the mechanical properties of its surroundings or micro-environment. More recently studies have shown that changes to intra-cellular mechanical properties can also have a meaningful impact on cell function and in some cases lead to the progression of ailments or disease. For example, small changes to the protein sequence of a structural nuclear envelope protein called lamin-A is known to cause a variety of neurological and musculoskeletal diseases referred to as laminopathies. Currently, there is little incite into how these mutations lead to disease progression due in part to an inability to measure protein-specific mechanical changes and how these alterations may relate to disruptions in intra-cellular signaling or function. \par To improve upon the ability to measure mechanical properties inside living cells, a previously validated, genetically-encoded resonant energy transfer (FRET)-force biosensor was modified to localize to the nuclear envelope. This biosensor integrated into the nuclear envelope protein Nesprin-2G and senses small deformations that are resolved by indirect measurements of spectroscopic fluctuations in the fluorescent emission of the sensor. To accurately measure these changes, a new spectral-imaging technique named SensorFRET was developed which can resolve small changes in the FRET sensor under varying levels of fluorescent intensity and with known absolute precision. Using SensorFRET, the Nesprin-2G biosensor (Nesprin-TS) reported changes in actomyosin contractility, nuclear shape, and nuclear deformation. Using Nesprin-TS, fibroblasts derived from patients with Hutchinson-Gilford progeria syndrome (HGPS) reported less force on Nesprin-2G molecules relative to healthy fibroblasts on average.\par To demonstrate how intra-cellular forces on the nucleus may impact normal cell physiology, bone-marrow derived mesenchymal stem cells (MSCs) were genetically modified such that the cytoskeleton was decoupled from the nucleus by saturating KASH binding proteins with a non-functional truncated protein called DN-KASH. MSCs treated with DN-KASH preferentially differentiated into osteocytes (bone cells) at a higher rate than MSCs exposed to osteogenic growth factors. This osteogenic preference after DN-KASH treatment was independent of the cell substrate topology and did not significantly alter integrin expression. However, this tendency to differentiate into osteocytes was dependent on substrate stiffness. Overall, the data imply that an intra-cellular force-dependent mechanism connected to the cell nucleus strongly influences MSC differentiation.

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Ribeiro, Marcel Cintra Pereira. « Correlações entre parâmetros cinemáticos da locomoção terrestre e energética em Cebus apella (macaco-prego) ». Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/41/41135/tde-24082007-115459/.

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O presente estudo teve como objetivo avaliar o custo energético e alguns aspectos da biomecânica associados à locomoção em Cebus apella (macaco-prego). Para tanto, medidas de taxa metabólica (consumo de oxigênio) e de parâmetros cinemáticos (freqüência de passos, tempo de contato das patas com o plano de apoio, comprimento dos passos e amplitudes de flexão e extensão de juntas e segmentos corpóreos) foram obtidas com os sujeitos experimentais se locomovendo sobre esteira rolante. Nossos resultados mostram que apesar da espécie estudada exibir freqüência de passos inferior ao esperado para mamíferos quadrúpedes de massa corpórea similar, esse parâmetro cinemático é o elemento preferencial do padrão de locomoção que é ajustado para que o animal possa suportar as novas condições do meio (alteração de velocidade). Em adição, os dados de consumo de oxigênio obtidos neste estudo indicam que diferenças significativas não devem ser esperadas entre o custo energético da locomoção de quadrúpedes primatas e não primatas. Sendo assim, foi possível inferir que um outro elemento, além da taxa de geração de força (inferida a partir da freqüência de passos), pode responder pela magnitude do custo energético da locomoção em primatas. Nossas inferências sugerem que características anatômicas de primatas (maior volume muscular associado aos membros posteriores) podem constituir-se no elemento central para o entendimento do custo metabólico exibido pela espécie estudada (similar a quadrúpedes não primatas). Por fim, deve ser salientado que nossos dados indicam que a flexão da coluna pode ser um importante mecanismo para armazenamento de energia (energia elástica) durante a locomoção em Cebus apella, sobretudo em velocidades mais altas.
This study aimed to evaluate the energy expenditure and biomechanical aspects associated to the locomotion of Cebus apella (capuchin monkey). Measurements of metabolic rate (oxygen consumption) and kinematic parameters (stride frequency, foot contact time, step length and degree of flexion-extension of the joints and body segments) were obtained with the experimental subjects moving on a motorized treadmill. Our results show that although the species studied displays a lower stride frequency than quadruped mammals with similar body masses, this is the kinematic parameter that is preferentially adjusted by the animal to cope with faster velocities. In addition, oxygen consumption data obtained in this study indicate that significant differences between the energy cost of locomotion of primates and nonprimates quadrupeds should not be expected. Based on this result, we suggest that another element besides the rate of generating force (inferred from the stride frequency) could explain the energy cost of locomotion in primates. We suggest that anatomic characteristics of primates (larger muscular volume associated with the hind limbs) might be a key element to understand the cost of locomotion showed by capuchin monkeys (similar to non-primate quadrupeds). Our results also indicate that flexion of the column can be an important mechanism for elastic energy storage during locomotion in Cebus apella particularly at higher velocities.

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Dean, Maureen A. « Predictions of Distal Radius Compressive Strength by Measurements of Bone Mineral and Stiffness ». Ohio University Art and Sciences Honors Theses / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ouashonors1461595642.

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Cifuentes, Quintero Jenny Alexandra. « Development of a new technique for objective assessment of gestures in mini-invasive surgery ». Thesis, Lyon, INSA, 2015. http://www.theses.fr/2015ISAL0056/document.

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L'une des tâches les plus difficiles de l'enseignement en chirurgie, consiste à expliquer aux étudiants quelles sont les amplitudes des forces et des couples à appliquer pour guider les instruments au cours d'une opération. Ce problème devient plus important dans le domaine de la chirurgie mini-invasive (MIS) où la perception de profondeur est perdue et le champ visuel est réduit. Pour cette raison, l'évaluation de l'habileté chirurgicale associée est devenue un point capital dans le processus d'apprentissage en médecine. Des problèmes évidents de subjectivité apparaissent dans la formation des médecins, selon l'instructeur. De nombreuses études et rapports de recherches concernent le développement de techniques automatisées d'évaluation du geste. La première partie du travail présenté dans cette thèse introduit une nouvelle méthode de classification de gestes médicaux 3D reposant sur des modèles cinématiques et biomécaniques. Celle-ci analyse de manière qualitative mais aussi quantitative les mouvements associés aux tâches effectuées. La classification du geste est réalisée en utilisant un paramétrage reposant sur la longueur d'arc pour calculer la courbure pour chaque trajectoire. Les avantages de cette approche sont l'indépendance du temps, un système de repérage absolu et la réduction du nombre de données. L'étude inclue l'analyse expérimentale de plusieurs gestes, obtenus avec plusieurs types de capteurs et réalisés par différents sujets. La deuxième partie de ce travail se concentre sur la classification reposant sur les données cinématiques et dynamiques. En premier lieu, une expression empirique, entre la géométrie du mouvement et les données cinématiques, sert à calculer une nouvelle variable appelée vitesse affine. Les expériences conduites dans ce travail de thèse montrent la nature constante de cette grandeur lorsque les gestes médicaux sont simples et identiques. Une dernière technique de classification a été implémentée en utilisant un calcul de l'énergie utilisée au cours de chaque segment du geste. Cette méthode a été validée expérimentalement en utilisant six caméras et un laparoscope instrumenté. La position 3-D de l'extrémité de l'effecteur a été enregistrée, pour plusieurs participants, en utilisant le logiciel OptiTrack Motive et des marqueurs réfléchissants montés sur le laparoscope. Les mesures de force et de couple, d'autre part, ont été acquises à l'aide des capteurs fixés sur l'outil et situés entre la pointe et la poignée de l'outil afin de capturer l'interaction entre le participant et le matériau manipulé. Les résultats expérimentaux présentent une bonne corrélation entre les valeurs de l'énergie et les compétences chirurgicales des participants impliqués dans ces expériences
One of the most difficult tasks in surgical education is to teach students what is the optimal magnitude of forces and torques to guide the instrument during operation. This problem becomes even more relevant in the field of Mini Invasive Surgery (MIS), where the depth perception is lost and visual field is reduced. In this way, the evaluation of surgical skills involved in this field becomes in a critical point in the learning process. Nowadays, this assessment is performed by expert surgeons observation in different operating rooms, making evident subjectivity issues in the results depending on the trainer in charge of the task. Research works around the world have focused on the development of the automated evaluation techniques, that provide an objective feedback during the learning process. Therefore, first part of this thesis describe a new method of classification of 3D medical gestures based on biomechanical models (kinematics). This new approach analyses medical gestures based on the smoothness and quality of movements related to the tasks performed during the medical training. Thus, gesture classification is accomplished using an arc length parametrization to compute the curvature for each trajectory. The advantages of this approach are mainly oriented towards time and location independence and problem simplification. The study included several gestures that were performed repeatedly by different subjects; these data sets were acquired, also, with three different devices. Second part of this work is focused in a classification technique based on kinematic and dynamic data. In first place, an empirical expression between movement geometry and kinematic data is used to compute a different variable called the affine velocity. Experiments carried out in this work show the constant nature of this feature in basic medical gestures. In the same way, results proved an adequate classification based on this computation. Parameters found in previous experiments were taken into account to study movements more complex. Likewise, affine velocity was used to perform a segmentation of pick and release tasks, and the classification stage was completed using an energy computation, based on dynamic data, for each segment. Final experiments were performed using six video cameras and an instrumented laparoscope. The 3-D position of the end effector was recorded, for each participant, using the OptiTrack Motive Software and reflective markers mounted on the laparoscope. Force and torque measurements, on the other hand, were acquired using force and torque sensors attached to the instrument and located between the tool tip and the handle of the tool in order to capture the interaction between participant and the manipulated material. Results associated to these experiments present a correlation between the energy values and the surgical skills of the participants involved in these experiments

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Appleton, Elizabeth Allyn. « Body Composition and Nutrition Trends in Club Triathlon Members ». The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1524056237786679.

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Arruda, Carla Prisco Arnoni de. « Análise do amortecimento de luvas de boxe e dos critérios subjetivos para escolha de luvas por atletas ». reponame:Repositório Institucional da UFABC, 2015.

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Orientador: Prof. Dr. Marcos Duarte
Dissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Engenharia Biomédica, 2015.
Luvas de boxe são utilizadas em lutas e treinamento principalmente para proteção das mãos do lutador. A segurança tanto do atleta que golpeia quanto do que recebe o golpe é prioridade para as federações de lutas que utilizam luvas. Desconhece-se estudos que tenham investigado as repostas mecânicas ao impacto de luvas nacionais. Neste contexto, este trabalho tem dois objetivos: medir quantitativamente as respostas mecânicas ao impacto de luvas brasileiras em comparação com as principais luvas estrangeiras vendidas no Brasil; e determinar qualitativamente, por meio de questionário, quais características subjetivas da luva de boxe são relevantes para o usuário. Para medição das respostas mecânicas serão empregados procedimentos similares ao estudo de Girodet e colaboradores (2009), somente com adaptações dos equipamentos, permitindo assim uma comparação direta dos resultados. O ensaio mecânico consistiu basicamente em deixar cair um corpo de prova sobre a parte da luva com função de amortecimento e medir o pico da força de impacto resultante dessa queda. Nosso experimento testou luvas de marcas diferentes, e cada um dos tipos representados por luvas de 12 e 14oz. Foram 30 tentativas com cada amostra (10 em cada altura de queda da massa de impacto). As tentativas com a marca "A" foram as que produziram menos força de impacto (maior amortecimento). Em segundo lugar, para todas as condições, ficou a marca "D". A diferença na absorção do impacto entre as luvas de mesma oz, mas de marcas diferentes, foi estatisticamente significante em metade das condições testadas, o que sugere a impossibilidade de indicar uma luva de maior proteção apenas pelo peso indicado pelo fabricante. Entre as luvas da mesma marca mas oz diferentes (12 e 14oz), onde esperava-se diferença significativa na absorção do impacto, na maior parte das condições as luvas mostraram-se iguais estatisticamente. Esse resultado também indica a fragilidade das variáveis utilizadas para definir os tipos de luvas que podem oferecer maior proteção ao usuário. Os resultados encontrados pelo ensaio do presente estudo também foram consistentes aos descritos por Girodet e colaboradores (2009). A menor força de impacto (maior amortecimento) foi verificada nas tentativas com as luvas de composição aparentemente mais simples (espuma injetada).
Boxing gloves are used in fights and training for hand protection. The safety of both, the athlete striking and the athlete receiving the blow, is a priority for the associations of fights witch use gloves. Studies that investigated the responses to mechanical impact of national gloves are unknown. In this context, this study has two objectives: to measure quantitatively the mechanical responses to the impact of Brazilian gloves compared to the main foreign gloves sold in Brazil; and determine qualitatively, through a questionnaire, which subjective characteristics of the boxing glove are relevant to the user. For measurement of mechanical responses, we used similar procedures to the study of Girodet and colleagues (2009), only with adjustments to the equipment, thus allowing a direct comparison of results. The mechanical test consisted in dropping a weight on the part of the glove and measure the peak of the resulting impact force this fall. Our experiment tested four different brands of gloves, and each of the types represented by 12 and 14oz gloves. There were 30 trials in each sample (10 in each drop height of the impact mass). Attempts with the brand "A" were those that produced less impact force. Second, for all conditions was the brand "B". The difference in impact absorption between the glove with the same oz but different brands was statistically significant in half of conditions tested, suggesting that it is impossible to indicate a greater protection only by the weight indicated by the manufacturer. Among the gloves of the same brand but different oz (12 and 14oz), where was expected significant difference in the impact absorption, in most conditions the gloves proved was statistically equal. This result also indicates the fragility of the variables used to define the types of gloves which can offer greater protection to the user. The results of the present study were also consistent with the test described by Girodet and col (2009). The lower impact strength was observed in attempts with the seemingly simple composition gloves (injected foam).

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Yang, Lixiang. « Modeling Waves in Linear and Nonlinear Solids by First-Order Hyperbolic Differential Equations ». The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1303846979.

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Handford, Matthew Lawrence. « Simulating human-prosthesis interaction and informing robotic prosthesis design using metabolic optimization ». The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1539707296618987.

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Flores, Nicolas. « Influence des propriétés mécaniques des chaussures sur la performance en course à pied d'endurance : analyses à court terme et lors d'une course à pied de durée prolongée ». Thesis, Aix-Marseille, 2019. http://www.theses.fr/2019AIXM0222.

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Tandis que les bénéfices physiologiques de chaussures de référence dans le milieu de la course à pied d’endurance sont montrés dans la littérature scientifique, les effets spécifiques et contrôlés de certaines propriétés mécaniques des chaussures demeurent peu connus. L’objectif général de ce travail de thèse était d’étudier les effets du retour d’énergie des semelles intermédiaire des chaussures et de la raideur en flexion des chaussures sur la performance physiologique et biomécanique en course à pied d'endurance. Que ce soit à court-terme ou lors d’une course à pied prolongée, le coût énergétique métabolique (critère utilisé pour évaluer la performance en course à pied) n’était pas significativement modifié par les propriétés mécaniques testées en moyenne parmi le groupe complet de participants. En revanche, les réponses spécifiques aux participants, à la fois à court-terme et lors d’une course à pied prolongée, ont permis de mettre en évidence des combinaisons de réponses biomécaniques et de caractéristiques intrinsèques aux participants expliquant les variations du coût énergétique métabolique en fonction des propriétés mécaniques chaussantes. Une nouvelle stratégie a notamment été mise en évidence chez les participants bénéficiant de la raideur en flexion des chaussures qui se traduisait par une redistribution descendante des activations musculaires des articulations de la hanche et du genou vers l’articulation de la cheville avec la durée de course. Ce travail de thèse soulignait l’importance de considérer une offre de conception de chaussures adaptées à des groupes de coureurs aux réponses biomécaniques et/ou aux caractéristiques intrinsèques similaires
While physiological benefits of baseline running racing shoes are shown in the scientific literature, the specific and controlled effects of some shoe mechanical features remain not well known. The main purpose of this work was to study the effects of the midsole energy return and the shoe longitudinal bending stiffness on the physiological and biomechanical performance during endurance running. In both short-term and prolonged running duration, the metabolic energetic cost (criteria used to evaluate the endurance running performance) was not significantly altered by the tested mechanical features in average over the group of participants. The main finding was that the shoe mechanical features induced different effects on the metabolic energetic cost depending on the participants. Taking into account the participant-specific responses (in both short-term and during a prolonged running duration) enabled to highlight combinations of biomechanical responses and intrinsic participant characteristics explaining the variations of the metabolic energetic cost as a function of shoe mechanical features. A novel strategy has been highlighted in participants benefiting from the shoe longitudinal bending stiffness resulting in descendant redistribution of the muscular coordination from the hip and knee joints to the ankle joint with the running duration. This work showed the importance of considering a footwear design offer suitable to groups of runners with similar biomechanical responses and/or intrinsic characteristics

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Warner, Holly E. « Simulation and Control at the Boundaries Between Humans and Assistive Robots ». Cleveland State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=csu1577719990967925.

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Ekizos, Antonis. « Dynamic stability control and human energetics ». Doctoral thesis, Humboldt-Universität zu Berlin, 2018. http://dx.doi.org/10.18452/19545.

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Die Bewegungs-kontrollstrategien kontextabhängig und abhängig von unterschiedlichen Kriterien ausgewählt werden. Einerseits ist die Stabilität in den Bewegungszuständen wie der Fortbewegung ausschlaggebend für die ungestörte Ausführung bestimmter Handlungen und erfordert eine effektive Steuerung durch das zentrale Nervensystem. Andererseits wird die Bewegungsstrategieauswahl durch das zentrale Nervensystem dadurch bestimmt, dass die Energiekosten minimiert werden soll. Beide Konzepte (d.h. die Aufrechterhaltung der Stabilität und die Energiekostenminimierung) spielen eine fundamentale Rolle bei der Frage, warum sich Menschen so bewegen, wie sie es tun. Unklar ist dabei allerdings, auf welche Weise das zentrale Nervensystem beide Prinzipien gegeneinander gewichtet. In den letzten 20 Jahren haben uns wissenschaftliche Konzepte wie die Chaostheorie oder die Theorie komplexer Systeme eine neue Herangehensweise an diese Fragen ermöglicht. Diese Arbeit untersucht die dynamische Stabilität menschlicher Fortbewegung mit Hilfe des Konzepts der Ljapunowanalyse. Als erstes wird eine methodologische Untersuchung der Verlässlichkeit des maximalen Ljapunowexponenten beim Gehen und Laufen durchgeführt (Kapitel 2). Danach wird verglichen zwischen dem Laufen unter normalen Umständen und dem darauffolgenden Laufen ohne Schuhe, wobei letzteres eine Abnahme der Stabilität nach dem Übergang zu den neuen Umständen zur Folge hat (Kapitel 3). In der letzten Untersuchung wurde ein unterschiedlich langes Training zur Verbesserung der Laufenergetik durchgeführt, in einer Gruppe nur über einen kurzen und in einer anderen Gruppe über einen etwas längeren Zeitraum (Kapitel 4). Die Ergebnisse zeigen, dass Bewegungskontrollfehler für die Energiekosten beim Laufen eine Rolle spielen können, und legen somit eine flexible Priorisierung der Bewegungskontrolle nahe.
Motor control strategies are chosen in a context dependent manner, based on different criteria. On the one hand stability in dynamic conditions such as locomotion, is crucial to uninterrupted task execution and requires effective regulation by the central nervous system. On the other, minimization of the energetic cost of transport is instrumental in choosing the locomotion strategy by the central nervous system. Both these concepts, (i.e. maintaining stability and optimization of energetic cost of locomotion) have a fundamental role on how and why humans move in the way they do. However, how the human central nervous system prioritizes between the different goals is unknown. In the last 20 years, ideas from scientific paradigms such as chaos theory and complex systems have given us novel tools to approach these questions. The current thesis examines the dynamic stability during human locomotion under such an approach using the concept of Lyapunov analysis. At first a methodological examination of the reliability of the maximum Lyapunov exponent in walking and running has been conducted (chapter 2). Afterwards, an examination between the habitual running condition and after removal of footwear was conducted, exhibiting a decrease in stability following the acute transition to the new condition (chapter 3). In the last study, a training intervention aiming at improvements in running energetics was performed using a short-term and a long-term intervention group (chapter 4). The results evidence that motor control errors can have a role in the energy cost of running and thus, a flexible prioritization of the motor control output.

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Grenier, Jordane. « Effets des équipements de fantassin modernes sur la locomotion et la fatigue neuromusculaire du soldat déployé : simulation opérationnelle ». Phd thesis, Université Jean Monnet - Saint-Etienne, 2012. http://tel.archives-ouvertes.fr/tel-00978768.

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La problématique du port de charges par l'Homme est l'objet de questionnements scientifiques depuis plus d'un siècle, notamment dans les armées où les soldats doivent remplir des objectifs opérationnels tout en emportant des équipements lourds, distribués de façon complexe autour de leur corps, et cela au cours d'efforts allant de quelques heures à plusieurs jours. Aussi, avec le développement des nouvelles technologies et l'arrivée des systèmes fantassins futurs sur le marché de la défense, cette problématique continue de se complexifier puisque la masse totale emportée tend encore à croître. Objectif général : Le but de ce travail de thèse était d'étudier l'impact biomécanique, métabolique et neuromusculaire du port d'un système fantassin moderne chez le soldat expérimenté. Plus précisément, une première recherche a été menée pour caractériser les effets aigus du port d'un tel équipement sur la biomécanique et le coût métabolique de la marche. Puis, une seconde recherche a été consacrée à l'étude des conséquences neuromusculaires et locomotrices d'une mission militaire (simulation sur le terrain) de durée " extrême " réalisée avec ce système fantassin moderne. Première partie : L'analyse de la marche sur tapis roulant dynamométrique a permis de montrer que le port du système fantassin en configurations de " combat " et de " marche d'approche " (principales configurations du théâtre militaire, représentant respectivement ~30 % et ~50 % de la masse corporelle des sujets) altérait le pattern spatio-temporel par rapport à la marche sans charge. Par ailleurs, le travail mécanique appliqué au centre de masse et le coût métabolique de la marche augmentaient parallèlement lors du port des deux configurations du système fantassin, ce qui résultait en un maintien du rendement locomoteur constant dans toutes les conditions testées. Le mécanisme de transfert d'énergie en pendule inversé (méthode Cavagna), permettant de minimiser les coûts mécanique et métabolique de transport, était également similaire dans toutes les conditions avec et sans charge. Enfin, bien que complexement organisés autour du corps du soldat, les équipements militaires n'induisaient pas d'effets mécaniques et métaboliques sensiblement plus importants que ceux rapportés lors du port de masses positionnées symétriquement autour de la taille ; ce mode de portage étant pourtant considéré comme l'un des plus optimisés, abstraction faite des techniques de portage sur la tête inadaptées au contexte militaire. Deuxième partie : La réalisation d'une mission simulée, incluant 21 h d'activités militaires sur le terrain et le port constant d'un système fantassin, résultait en une fatigue neuromusculaire (mesure des forces, électrostimulation et EMG) relativement modérée des muscles locomoteurs extenseurs du genou et fléchisseurs plantaires chez les soldats expérimentés inclus dans ce travail. Les origines de cette fatigue neuromusculaire étaient essentiellement périphériques, mais s'accompagnaient d'une fatigue subjective importante. Enfin, la réalisation de la mission, et donc la fatigue des muscles locomoteurs notamment associée à cette dernière, n'affectait pas sensiblement les paramètres mécaniques et métaboliques de la marche. Conclusion générale : Ce travail rapporte les premières données relatives aux effets biomécaniques, métaboliques et neuromusculaires du port d'un système fantassin moderne chez le soldat expérimenté, et ce par le biais d'une simulation opérationnelle visant à reproduire les conditions militaires

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Felden, Luc. « Mechanical optimization of vascular bypass grafts ». Thesis, Available online, Georgia Institute of Technology, 2005, 2005. http://etd.gatech.edu/theses/available/etd-04112005-145422/unrestricted/felden%5Fluc%5F200505%5Fmast.pdf.

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Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2005.
David N. Ku, Committee Chair ; Alexander Rachev, Committee Co-Chair ; Elliot L. Chaikof, Committee Member. Includes bibliographical references.

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Niu, Penglin. « Biomechanical energy conversion / ». 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3301203.

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Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2007.
Source: Dissertation Abstracts International, Volume: 69-02, Section: B, page: 1218. Adviser: Patrick L. Chapman. Includes bibliographical references (leaves 105-109) Available on microfilm from Pro Quest Information and Learning.

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Alves, Tiago Marques da Costa. « Biomechanical Energy-Harvesting based on triboelectric nanomaterials as a portable power source for electronics ». Master's thesis, 2021. https://hdl.handle.net/10216/136562.

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Rosario, Michael Devera. « Biomechanics of Hierarchical Elastic Systems ». Diss., 2015. http://hdl.handle.net/10161/11385.

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Elastic energy plays important roles in biology across scales, from the molecular to organismal level, and across the tree of life. The ubiquity of elastic systems in biology is partly due to the variety of useful functions they permit such as the simplification of motor control in running cockroaches and the efficient recycling of kinetic energy in hopping kangaroos. Elastic energy is also responsible for ultrafast movements; the fastest movements in animals are not powered directly by muscle, but instead by elastic energy stored in a spring. By demonstrating that the power required to generate ultrafast movements exceeds the limits of muscle, many studies conclude that energy storage is necessary; but, what these studies do not explain is how the properties of a biological structure affect its capacity for energy storage. In this dissertation, I test the general principles of energy storage by investigating elastic systems at three hierarchical levels of organization: a single structure, multiple connected structures, and a spring system connected to muscle. By using a multi-level approach, my aim is to demonstrate, at each of the mentioned levels, how properties of the spring system affect where or how much energy is stored in the system as well as how these conclusions can be combined to inform our understanding of the biomechanics of hierarchical elastic systems.

When considering spring systems at the level of a single structure, morphology is one major structural aspect that affects mechanics. Continuous changes in morphology are capable of dividing a structure into regions that are responsible for the two contradicting functions that are essential for spring function: energy storage (via deformation) and structural support (via resistance to deformation). Using high quality micro computed tomography scans, I quantify the morphology of the mantis shrimp (Stomatopoda) merus, a single structure of the raptorial appendage hypothesized to store the elastic energy that drives ultrafast strikes. Comparing the morphology among the species, I find that the merus in smashers, species that depend heavily on elastic energy storage, have relatively thicker ventral regions and more eccentric cross-sections than spearers, species that strike relatively slower. I also conclude that differential thickening of a region can provide structural support for resisting spring compression as well as facilitate structural deformation by inducing bending. This multi-level morphological analysis offers a foundation for understanding the evolution and mechanics of monolithic systems in biology.

When two or more structures are connected, their relative physical properties determine whether the structures store energy, provide structural support, or some combination of both. Although the majority of elastic energy is stored via large deformations of the merus in smashers, some spearer species show relatively little meral deformation, and it is unclear whether elastic energy is stored in these systems. To determine whether the apodeme (arthropod tendon) provides energy storage in species that exhibit low meral deformation, I measure the physical properties of the lateral extensor apodeme and the merus to which it is connected. Comparisons of these properties show that in the spearer species I tested, the merus has a relatively higher spring constant than the apodeme, which results in the merus providing structural support and the apodeme storing the majority of elastic energy. Comparing the material properties of the apodemes with those of other structures reveals that apodemes and other biological spring systems share similar material characteristics. This study demonstrates that in order to understand the biomechanics of spring systems comprised of connected structures, it is necessary to compare their relative mechanical properties.

Finally, because muscles are responsible for loading spring systems with potential energy, muscle dynamics can affect elastic energy storage in a spring system. Although spring systems can circumvent the limits imposed by muscle via power amplification, they are not entirely independent from muscle dynamics. For example, if an organism has relatively low time to prepare and stretch the spring prior to the onset of movement, the limits of muscle power can dominate energy storage. To test the effects of muscle dynamics on spring loading, I implement a mathematical model that connects a Hookean spring model to a Hill-type muscle model, representing the muscle-tendon complex of the hindlimbs of American bullfrogs, in which the muscle dynamics are well understood and the duration of spring loading is low. I find that the measured spring constants of the tendons nearly maximize energy storage within the duration of in vivo spring loading. Additionally, the measured spring constants are lower than those predicted to produce maximal energy storage when infinite time is available for spring loading. Together, these results suggest that the spring constants of the tendons of American bullfrogs are tuned to maximize elastic energy for small durations of spring loading. This study highlights the importance of assessing muscle dynamics and their effect on energy storage when assessing the functional significance of spring constants.

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Ridgway, Heather. « STRENGTH REQUIREMENTS AND ENERGY EFFICIENCY OF DIFFERENT STAIR-STEPPING STRATEGIES IN PERSONS WITH CHRONIC STROKE AND HEALTHY ADULTS ». Thesis, 2013. http://hdl.handle.net/1974/8367.

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The majority of stroke survivors return to living in the community; however, muscle weakness and cardiovascular deconditioning can restrict mobility, limit community access and independence, particularly when challenging activities like stair negotiation are involved. A “step-by-step” (SBS) strategy (both feet per step) may be adopted in lieu of a “step-over-step” (SOS) method (one foot per step) to increase stability and off-load the paretic limb though the physical demands of the two methods are unknown. The main objective of this thesis was to investigate the strength and energy demands of the two stair-stepping strategies in chronic stroke compared to healthy adults. The first study identified the relative strength and aerobic demands of both strategies. The results showed that the stroke group produced similar peak joint moments compared to controls, despite their slower cadence suggesting that the stroke group exerts comparable ‘effort’ to move more slowly. The SBS method was associated with lower strength costs (relative to individuals’ maximum strength output) than SOS, however aerobic cost was significantly higher. The second study identified the mechanical energy expenditures (MEEs) and transfers related to both strategies. The MEEs were found to be lower when the SBS strategy was used. Though expenditures were similar between groups, the stroke group had higher expenditures associated with the work of the less affected knee extensors (lead limb) during ascent and descent and controls exhibited higher expenditures for the plantarflexors during ascent. The reduced output of the trail (affected) limb plantarflexors likely resulted in the increased workload of the knee extensors. Overall, the aerobic cost per step was higher in stroke, particularly during descent, suggesting that in addition to reducing cadence, persons with stroke may be co-contracting to increase stabilization during descent, thus increasing oxygen demands. This thesis provides novel information on the physical demands associated with two methods of stair negotiation demonstrating that the SBS strategy might be better suited to persons with chronic stroke by minimizing the strength demands on the paretic side, but the benefit comes at an elevated aerobic cost. This information is valuable to rehabilitation professionals engaged in retraining mobility to facilitate community reintegration.
Thesis (Master, Rehabilitation Science) -- Queen's University, 2013-09-30 13:42:08.209

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Fey, Nicholas Phillip. « The influence of prosthetic foot design and walking speed on below-knee amputee gait mechanics ». Thesis, 2011. http://hdl.handle.net/2152/ETD-UT-2011-12-4686.

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Unilateral below-knee amputees commonly experience asymmetrical gait patterns and develop comorbidities in their intact (non-amputated) and residual (amputated) legs, with the mechanisms leading to these asymmetries and comorbidities being poorly understood. Prosthetic feet have been designed in an attempt to minimize walking asymmetries by utilizing elastic energy storage and return (ESAR) to help provide body support, forward propulsion and leg swing initiation. However, identifying the influence of walking speed and prosthetic foot stiffness on amputee gait mechanics is needed to develop evidence-based rationale for prosthetic foot selection and treatment of comorbidities. In this research, experimental and modeling studies were performed to identify the influence of walking speed and prosthetic foot stiffness on amputee walking mechanics. The results showed that when asymptomatic and relatively new amputees walk using clinically prescribed prosthetic feet across a wide range of speeds, loading asymmetries exist between the intact and residual knees. However, knee intersegmental joint force and moment quantities in both legs were not higher compared to non-amputees, suggesting that increased knee loads leading to joint disorders may develop in response to prolonged prosthesis usage or the onset of joint pathology over time. In addition, the results showed that decreasing ESAR foot stiffness can increase prosthesis range of motion, mid-stance energy storage, and late-stance energy return. However, the prosthetic foot contributions to forward propulsion and swing initiation were limited due to muscle compensations needed to provide body support and forward propulsion in the absence of residual leg ankle muscles. A study was also performed that integrated design optimization with forward dynamics simulations of amputee walking to identify the optimal prosthetic foot stiffness that minimized metabolic cost and intact knee joint forces. The optimal stiffness profile stiffened the toe and mid-foot while making the ankle less stiff, which decreased the intact knee joint force during mid-stance while reducing the overall metabolic cost of walking. These studies have provided new insight into the relationships between prosthetic foot stiffness and amputee walking mechanics, which provides biomechanics-based rationale for prosthetic foot prescription that can lead to improved amputee mobility and overall quality of life.
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Zhao, Ruogang. « The Development and Application of Tools to Study the Multiscale Biomechanics of the Aortic Valve ». Thesis, 2012. http://hdl.handle.net/1807/33866.

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Calcific aortic valve disease (CAVD) is one of the most common causes of cardiovascular disease in North America. Mechanical factors have been closely linked to the pathogenesis of CAVD and may contribute to the disease by actively regulating the mechanobiology of valve interstitial cells (VICs). Mechanical forces affect VIC function through interactions between the VIC and the extracellular matrix (ECM). Studies have shown that the transfer of mechanical stimulus during cell-ECM interaction depends on the local material properties at hierarchical length scales encompassing tissue, cell and cytoskeleton. In this thesis, biomechanical tools were developed and applied to investigate hierarchical cell-ECM interactions, using VICs and valve tissue as a model system. Four topics of critical importance to understanding VIC-ECM interactions were studied: focal biomechanical material properties of aortic valve tissue; viscoelastic properties of VICs; transduction of mechanical deformation from the ECM to the cytoskeletal network; and the impact of altered cell-ECM interactions on VIC survival. To measure focal valve tissue properties, a micropipette aspiration (MA) method was implemented and validated. It was found that nonlinear elastic properties of the top layer of a multilayered biomaterial can be estimated by MA by using a pipette with a diameter smaller than the top layer thickness. Using this approach, it was shown that the effective stiffness of the fibrosa layer is greater than that of the ventricularis layer in intact aortic valve leaflets (p<0.01). To characterize the viscoelastic properties of VICs, an inverse FE method of single cell MA was developed and compared with the analytical half-space model. It was found that inherent differences in the half-space and FE models of single cell MA yield different cell viscoelastic material parameters. However, under particular experimental conditions, the parameters estimated by the half-space model are statistically indistinguishable from those predicted by the FE model. To study strain transduction from the ECM to cytoskeleton, an improved texture correlation algorithm and a uniaxial tension release device were developed. It was found that substrate strain fully transfers to the cytoskeletal network via focal adhesions in live VICs under large strain tension release. To study the effects of cell-ECM interactions on VIC survival, two mechanical stimulus systems that can simulate the separate effects of cell contraction and cell monolayer detachment were developed. It was found that cell sheet detachment and disrupted cell-ECM signaling is likely responsible for the apoptosis of VICs grown in culture on thin collagen matrices, leading to calcification. The studies presented in this thesis refine existing biomechanical tools and provide new experimental and analytical tools with which to study cell-ECM interactions. Their application resulted in an improved understanding of hierarchical valve biomechanics, mechanotransduction, and mechanobiology.

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Alotaibi, Ahmed Mohammed. « Development of a Mechatronics Instrument Assisted Soft Tissue Mobilization (IASTM) Device to Quantify Force and Orientation Angles ». Thesis, 2016. http://hdl.handle.net/1805/10333.

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Indiana University-Purdue University Indianapolis (IUPUI)
Instrument assisted soft tissue mobilization (IASTM) is a form of massage using rigid manufactured or cast devices. The delivered force, which is a critical parameter in massage during IASTM, has not been measured or standardized for most clinical practices. In addition to the force, the angle of treatment and frequency play an important role during IASTM. As a result, there is a strong need to characterize the delivered force to a patient, angle of treatment, and stroke frequency. This thesis proposes two novel mechatronic designs for a specific instrument from Graston Technique(Model GT3), which is a frequently used tool to clinically deliver localize pressure to the soft tissue. The first design is based on compression load cells, where 4-load cells are used to measure the force components in three-dimensional space. The second design uses a 3D load cell, which can measure all three force components force simultaneously. Both designs are implemented with IMUduino microcontroller chips which can also measure tool orientation angles and provide computed stroke frequency. Both designs, which were created using Creo CAD platform, were also analyzed thorough strength and integrity using the finite element analysis package ANSYS. Once the static analysis was completed, a dynamic model was created for the first design to simulate IASTM practice using the GT-3 tool. The deformation and stress on skin were measured after applying force with the GT-3 tool. Additionally, the relationship between skin stress and the load cell measurements has been investigated. The second design of the mechatronic IASTM tool was validated for force measurements using an electronic plate scale that provided the baseline force values to compare with the applied force values measured by the tool. The load cell measurements and the scale readings were found to be in agreement within the expected degree of accuracy. The stroke frequency was computed using the force data and determining the peaks during force application. The orientation angles were obtained from the built-in sensors in the microchip.

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Thèses sur le sujet « Biomechanical energy »

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