Title: The pressure distribution on the soles of feet in the medium parallel turn in the alpine and the telemark technique of downhill skiing Objectives: The aim of this thesis is to compare the pressure distribution on the soles of feet in the medium parallel turn in the alpine and the telemark technique of downhill skiing. Methods: For the analysis of pressure distribution on the soles of feet in downhill skiing was used the pressure measurement system Pedar-X, which works for monitoring of plantar pressure (kPa) moreover. The pressure distribution measuring on the soles of feet was taking place in prepared track of the ski slope in two ways. The first one was the telemark technique and the second one was the alpine technique. For the evaluating and the processing of the results was selected in the right and in the left turn of each testing person in approximately the same part of the track. Results: The results of pressure distribution in the alpine and the telemark position turn have shown the significantly important difference in the intraindividual comparison in every technique. The significantly important difference was detected also in the interindividual comparison in both techniques each other. Keywords: downhill skiing, telemark, Pedar-X, pressure distribution

Orientador: Katia Maria Lucchesi Cavalca / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-04T03:12:40Z (GMT). No. of bitstreams: 1 Mastaler_Alexandre_M.pdf: 8070977 bytes, checksum: 67729451cedeb65f0b15eb1a17a3fead (MD5) Previous issue date: 2004 / Resumo: O comando de válvulas é um sistema utilizado em motores à combustão, que tem como função controlar a abertura e fechamento de válvulas de circulação dos gases envolvidos na combustão. Ele é composto por diversos subsistemas; Um desses subsistemas é o contato balancim/pivô, onde o comando aciona o balancim para que esse acione a válvula e utilize o pivô como elemento de suporte. O conhecimento desse subsistema é importante para a avaliação de desgastes e ruídos provenientes desse contato, assim como, avaliações do atrito para otimização geral do comando. Para que haja a redução de desgaste, o pivô deve girar em relação ao balancim, mas existem certas aplicações em que o giro do pivô não é possível. Baseando-se na equação de Reynolds, o filme de óleo ao redor do pivô será avaliado e calculado com relação à distribuição de pressão. Com o conhecimento da distribuição de pressão, poderemos saber quais as forças envolvidas no subsistema. Considerando-se o atrito e os momentos gerados pelo balancim no pivô, chegamos às condições de equilíbrio do sistema. Com essas avaliações observaremos as condições que permitam a rotação do pivô em relação ao balancim / Abstract: The Valve Train System used in combustion engines have the ability to command the opening and closure of gas circulation valves control that takes part in combustion. It is formed by many sub-systems. One of these systems is the finger follower/pivot contact, where the command starts the finger follower for valve starts and uses the pivot as a support element. The knowledge of this sub-system is important to ware and noise evaluation that came ftom this contact, as well as, ftiction evaluation for the command general optimization. To reduce wear, the pivot must turn in finger follower relation, but in some applications the pivot tum is not possible. The oil film around the pivot is ca1culated in relation of its pressure distribution as Reynolds Equation. Through the knowledge of pressure distribution, the forces in the sub-system are known. Considering the ftiction and the moments generated by the balancing in the pivot, we carne to balance conditions in the system. With these evaluations we noticed the condition that allows the pivot rotation in relation to the balancing / Mestrado / Mecanica dos Sólidos e Projeto Mecanico / Mestre em Engenharia Mecânica

Disc brake calipers are subjected to complex mechanical loading and interaction of individual components in a typical brake assembly makes design improvement very challenging. To analyse caliper behaviour, complex Finite Element models were created and successfully validated using a variety of experimental techniques, including exceptionally suitable Digital Image Correlation. A novel methodology to optimise caliper design was developed, using non-linear contact Finite Element Analysis and topology optimisation, to generate lightweight, high performance brake calipers. The method was used on a Formula 1 brake assembly and significant improvement in structural design was achieved, with the new caliper being lighter and stiffer than the original. The same approach was used on more conventional 4 pistons calipers using various boundary conditions with particular focus on mass reduction and considerably lighter designs were achieved. The influence of specific features of the optimised calipers on the structural performance was also successfully investigated.

O objetivo desse estudo é: (a) verificar o efeito do desgaste do calçado na Força de Reação do Solo (FRS) e na distribuição de pressão plantar e (b) verificar a influência do desgaste em calçados de diferentes destinações de uso. Três sujeitos participaram desse estudo, usando cada um quatro calçados de corrida, sendo dois de treinamento (T1 e T2) e dois de competição (C1 e C2). Os calçados foram submetidos ao uso correspondente a 300km. As coletas de dados foram feitas, com o calçado novo e após 100, 200 e 300km de uso, utilizando o sistema Gaitway e o sistema F-Scan. Nos calçados novos, na FRS, a Taxa de Crescimento1 (TC1) foi significativamente maior no calçado C2, do que nos calçados C1 e T2. Na distribuição de pressão plantar, pequena diferença foi observada na Área total (AT) e nos picos de pressão, entre os calçados. Na influência do desgaste nos resultados de grupo, na FRS, o TC1 apresentou valores semelhantes entre as condições Novo e 300km, portanto o choque mecânico não se alterou. Na fase ativa da FRS, oscilações pequenas foram observadas e atribuídas a possíveis variações naturais do movimento, conforme descrito por SERRÃO (1999) e WINTER (1991). Na distribuição de pressão, a AT apresentou um aumento significativo da condição Novo, para as demais condições de uso. O aumento da área foi atribuído à possível compactação do calçado, sendo que essa alteração justificaria a crença de que o calçado novo precise ser amaciado. Entre os picos de pressão analisados, apenas o Pico de Pressão do Antepé (PPA) apresentou diminuição significativa nos valores, da condição Novo para os 300km. Observou-se que após o desgaste imposto, o estresse mecânico se manteve ou se apresentou menor que nas condições iniciais. Na análise da influência do desgaste nos diferentes calçados, para TC1, as diferenças que inicialmente eram significativas tornaram-se não significativas, a partir dos 200km, entre os calçados C1, C2 e T2. Os parâmetros da fase ativa foram pouco influenciados, porém influenciados de forma distinta pelo desgaste, nos calçados analisados. Na distribuição de pressão plantar, a área de contato foi influenciada de forma distinta em cada calçado. Nos picos de pressão plantar, grandes variações foram observadas, porém não atribuíveis ao desgaste promovido no calçado. Conclui-se que o desgaste, correspondente a 300km, pouco alterou o choque mecânico e o estresse mecânico nos calçados analisados. Por meio da destinação de uso, não é possível prever a resposta de calçados de treinamento e de competição ao indivíduo, nem supor que a durabilidade do calçado de competição seja menor do que a do calçado de treinamento / The objective of this study is: (a) to verify the effect of footwear usage on the Ground Reaction Force (GRF) and on the Plantar Pressure Distribution and (b) to verify the influence of usage in footwear of different destinations of use. Three subjects had participated of this study, each one received four running shoes, two of them are designated for training regimen (T1 and T2) and two of them for competition (C1 and C2). The footwears were used for 300km. The data collections were made in four different moments, with new footwear and after 100, 200 and 300km of use, using the Gaitway system and the F-Scan system. When footwear was new, the Loading Rate1 (LR1) was significantly higher in footwear C2, than in the footwears C1 and T2. Analyzing plantar pressure distribution, small differences were observed in the Total Contact Area (TCA) and in the peak of pressure, between the footwears. In the analysis of the different usage stages, the LR1 presented similar values between the conditions New and 300km, therefore the mechanical shock did not enhanced. In the active phase of the GRF, small oscillations were observed and attributed to the possible natural variations of the movement itself, as described before by SERRÃO (1999) and WINTER (1991). In pressure distribution, the TCA showed a significant increase from the New condition, for the other conditions of use. The increase of contact area was attributed to the possible compactation of the footwear?s material, if so this would justify the belief that the new footwear needs to be softened. Considering all peak pressure variables, only Forefoot Peak Pressure (FPP) presented significant reduction in its values, from the New condition for 300km. Therefore it could be assumed that after corresponding usage of 300km, the mechanical stress remained the same or decreased compared with the earlier conditions of use. The shoes of different destinations when analyzed through the conditions, showed that the differences for LR1 that initially were significant had become not significant, from 200km, between the footwear C1, C2 and T2. In the pressure peaks plantar, great variations had been observed, however not attributable to the usage. The conclusion is that usage, correspondent 300km, has little effect on mechanical shock and on mechanical stress on the footwear analyzed in this study. By means of the use destination, it is not possible to foresee the answer of footwear to the individual, nor to assume that the durability of the footwear are worse in competition shoes than in training shoes

During papermaking, the internal structure of the fibrenetwork constituting the paper is to a dominating extentdetermined in the forming zone of the paper machine. Thisthesis is aimed at studying the pressure distribution in bladeforming sections, which is commonly considered to be a keyquantity of the process. Previous work has provided insight into the physics ofdifferent devices employed in blade forming. However, there hasbeen a lack of models enabling studies of the effects of theinteraction between different components on the pressuredistribution. In the thesis, a model is presented for a genericblade forming section consisting of three blades. The positionsof two of the blades are fix, and in between them is located asuction box. The third blade is applied by a prescribed forceto the opposing wire, in a position facing the suction box. Themodel admits the study of the interaction between the pulsesfrom the different blades in the blade/counterbladeconfiguration, and between the pulses and one-sidedsuction. The wires are modelled as tensioned and perfectly flexibleEuler-Bernoulli beams of negligible mass. The suspension istreated like an inviscid fluid. Consideration is taken to theinfluence of fibre deposition on the permeability of thefabrics. By assuming the ratio between the length scales in thethickness direction and the machine direction to be small, aquasi one-dimensional model is obtained. For maximum flexibility, the model domain is divided intomodules. Each module is solved individually using a finitedifference based discretisation. The solutions for thedifferent modules are matched with each other iteratively. A comparison with published results for a single bladeindicates that the model can be used to obtain qualitativelycorrect predictions of the pressure distribution. New resultsinclude a series of calculations showing the non-trivialinteraction between the pressure pulses when the blades arepositioned successively closer together, the effects of suctionon the pressure pulse generated by a blade applied to theopposing wire, and how blades of modest curvature do notnecessarily stay in contact with the fabric along their fullwidth and the implication of this on the pressure gradient. <b>Descriptors:</b>fluid mechanics, blade forming, pressuredistribution, suction, interaction, permeable fabric,modules / NR 20140805

Wind storms pose dangerous threats to human lives and are an enormous drain on the economy. Their damage to buildings usually starts with the failure of structural components that are subjected to excessive wind loads. In this dissertation, we investigate the characteristics of extreme loads on low-rise structures through analysis of full-scale and numerical data. We also use numerical simulations to evaluate different approaches to control the separated flow over a surface-mounted prism with the objective of reducing extreme pressure coefficients or loads on its surface. In the first part, we use a probabilistic approach to characterize peak loads as measured on a subject house during Hurricane Ivan on 2004. Time series of pressure coefficients collected on the roof of that house are analyzed. Rather than using peak values, which could vary due to the stochastic nature of the data, a probabilistic analysis is used to determine the probability of non-exceedence of specific values of pressure coefficients and associated wind loads. The results show that the time series of the pressure coefficients follow a three-parameter Gamma distribution, while the peak pressure follows a two-parameter Gumbel distribution. The results of the analysis are contrasted with the design values. In the second part, we perform numerical simulations of the flow over a surface-mounted prism as a simplified example for the flow over a low-rise structure. A Direct Numerical Simulation (DNS) code is developed to solve the unsteady two-dimensional incompressible Navier-Stokes equations of the flow past the prism. The pressure coefficients are then computed on the prism surface in order to assess the wind loads. The code is written on a parallel platform using the Message Passing Interface (MPI) library. We use the simulations to study the effects of inflow disturbances on the extreme loads on structures. The sensitivities of peak loads on a surface mounted prism to variations in incident gust parameters are determined. Latin Hypercube Sampling (LHS) is applied to obtain different combinations of inflow parameters. A non-intrusive polynomial chaos expansion is then applied to determine the sensitivities. The results show that the gust enhances the destabilization of the separation shear layer, forces it to break down and moves it closer to the roof of the prism. As for the sensitivities, the results show that the extreme loads are most sensitive to the transverse amplitude of the disturbance. Because the separated flow over sharp edges is responsible for the extreme pressure peaks, we investigate the use of active and passive control strategies to reduce wind loads. The studied active flow control strategies include blowing, suction, and synthetic jets. We implement them by using different flux injections, different slot locations and different angles. Investigation of the possible peak pressure reduction for two Reynolds numbers is performed. For Re = 1000, a reduction by nearly 50% of the peak pressure is obtained. For Re = 10, 000, the highest achieved reduction is nearly 25%. For passive control, we mount a flexible membrane on the top of the prism. In a two-dimensional framework, the membrane equation is modeled by a forced string equation. This mechanical equation is coupled with the DNS solver and integrated in time using a fourth order Hamming predictor corrector scheme. The results show that this strategy is as efficient as the active control approach, in terms of reducing extreme loads, for Re = 10, 000. / Ph. D.

In the advent of increasing the number of operable unmanned aerial systems (UAS) over the next years, a challenge exists in regard to the noise signature that these machines may generate. In this work, we perform advanced computational simulations to study the flow around an airfoil and the associated noise radiating to the near- and farield. The airfoil size and the freestream velocity are representative of a typical UAS. The study is aimed at investigating the characteristics of the aerodynamic noise radiating from an airfoil at various angles of attack, Reynolds number and Mach number. The numerical tool is a high-order compressible Navier-Stokes solver, using Runge-Kutta explicit time integration and dispersion-relation-preserving spatial discretization. Various results in terms of velocity and pressure distribution around the airfoil, and sound pressure level spectra calculated from different probe points located in the near- and farield are compared to each other and discussed.

An experimental study was carried out on a single-ply low-slope roof using a series of different underlayment layers to test and understand distributional characteristics of negative air pressure throughout the roof assembly, when subjected to suction pressure corresponding to different wind speeds. Various underlayments were tested at the Research & Demonstration Facility at Virginia Polytechnic Institute and State University to develop design guidelines for the installation of recently developed omni-directional roof vent on low slope membrane roofing systems. The newly designed and patented low-pressure roof vent works on Bernoulli and Venturi air flow principals and helps prevent uplift and detachment of the roofing membrane during storm or high wind conditions by creating a negative pressure zone underneath the roof membrane. The objective of this research is to further develop the Pressure Equalizing Vent System by testing the wind vent in combination with different underlayments and to determine the appropriate tributary area of each vent under dynamic wind conditions. The determined area of influence of each wind vent therefore serves as a guideline for appropriate spacing of the vents on the roof. It will also suggest the wind speed at which the pressure is lowered and its ability to weather storm events. The pressure sensors permanently installed beneath the membrane will continuously monitor the pressures in and around the wind vent. An additional objective of the research project is to understand the distributional characteristics of negative pressure in various layers of roof assembly in combination with varying underlayment membranes under different suctionals pressure to further develop the Pressure Equalizing Vent System. The proposal seeks to develop a cost effective roof assembly method, which can withstand the effect of extreme wind through improved understanding of air movement through different layers of roof assembly. The study explores the effect of various underlayments on spatial and distributional character of pressure field on the single ply flat roof deck in combination with omni-directional roof vent system. / Master of Science

The "Knuckle-walking Hominin Hypothesis" postulates that there was a knuckle-walking phase during the transition from quadrupedalism to bipedalism. To address this question, previous research has focused on the search for a "signal" within the wrist, and metacarpals of extant knuckle walkers that can be used to infer this locomotor pattern in extinct hominins. To date, the examined features have not yielded a clear, non-contested signal. I explore the Knuckle-walking Hominin Hypothesis in two ways: 1. by examining the hand postures and the manual pressure application of Pan and Gorilla during knuckle walking to determine whether there are species specific differences and 2. by examining the internal and external morphology of the manual phalanges in an attempt to isolate a clear "knuckle-walking signal". Chimpanzees are more variable in their preferred contact digits, and use both hand positions with equal frequency ("palm-in" - palm facing toward the body and "palm-back" - palm facing posteriorly). In contrast, gorillas consistently make contact with all four digits 2-5, maintain a pronated arm, and use the palm-back hand position. In both taxa, hand position affects which digit acts as the final touch-off element and therefore receives maximum pressure in a given step, and digit 5 receives significantly less pressure than the other rays. Gorillas are, in effect, practicing a refined subset of the variety of knuckle-walking postures used by the more arboreal chimpanzees. A clear knuckle-walking signal is seen in both the external and internal morphology of the phalanges. Chimpanzees and gorillas have the same middle phalangeal curvature profile with the greatest curvature found in digit 5 (5 > 2 > 3 > 4), the element that receives the least amount of pressure. This phalangeal curvature profile is a feature not shared with any of the included taxa practicing different modes of locomotion. They also have similar Indices of Relative Curvature (IRC-middle phalangeal curvature/proximal phalangeal curvature) for digits 2-5 that clearly delineate them with "flatter" middle phalanges and more curved proximal phalanges (IRCs = ~0.85), from quadrupeds with more curved middle than proximal phalanges (IRCs > 1), and suspensory primates with higher and more equal curvature values for both elements (IRCs = ~1). This ability to differentiate between locomotor groups holds if the IRCs are composed of elements from different rays of the same manus and from elements of different individuals. Within the trabecular bone structure, knuckle walkers are differentiated from quadrupeds and suspsensory primates in 3 locations: the metacarpal head, and the proximal ends of the middle and proximal phalanges. In particular, the metacarpal head shows distinct differences between the groups: knuckle walkers have a palmar-dorsal alignment of trabeculae and disc-like shape, suspensory taxa have a proximodistal alignment and rod-like shape and quadrupeds have a proximodistal alignment and disc-like shape. The ability to differentiate between locomotor categories using isolated zones increases the applicability of these signals to a fragmentary and limited fossil record. The morphological similarities, specifically the shared curvature profile, and the similar knuckle-walking kinematics employed by chimpanzees and gorillas point to a shared origin of knuckle walking.

No description available.