11 |
Utveckling av testmetod för och utvärdering av Butterfly Bridge : Ett experimentellt examensarbete på uppdrag av KlättermuseSellström, Marcus, Forsberg, Clara January 2022 (has links)
Ryggsäckar används vid mängder av aktiviteter och har många fördelar jämfört med andra väskor, särskilt när det kommer till att bära tungt. Emellertid blir dåligt utformade ryggsäckar med bristande hänsyn till ergonomiska faktorer obekväma och kan i värsta fall orsaka skador. Studier har visat att belastningen på axlar är den främst begränsande faktorn vid ryggsäcksbärande. Klättermusen har försökt lösa detta problem med innovationen Butterfly Bridge som är tänkt att fördela lasten över axeln på ett mer skonsamt sätt. Projektet genomfördes i syfte att bredda kunskapen kring ryggsäckars påverkan på kroppen samt bidra med information om Butterfly Bridges effekt till uppdragsgivaren. Mer specifikt var målet med projektet att utveckla lämplig metod för att mäta effekten och utvärdera huruvida Butterfly Bridge fungerar som beskrivet och har en mätbar effekt på tryckfördelning mellan ryggsäck och axel. Den inledande litteraturstudien visade på ett antal tillgängliga metoder för att mäta och bedöma en ryggsäcks påverkan på kroppen. För att utvärdera Butterfly Bridges effekt valdes en kvantitativ metod med experimentella tester på testdocka. Trycket mellan axelrem och dockan mättes med taktila trycksensorer från Tekscan. Mätningar gjordes med och utan Butterfly Bridge för två ryggsäckar från Klättermusen, Grip 60L och Ymer 65L. Resultaten visade inte på någon skillnad mellan att använda Butterfly Bridge eller inte. Tryckbilder från mätningarna visade inga synliga skillnader i tryckfördelning och det kan utifrån mätningarna i denna studie inte bevisas att Butterfly Bridge har någon effekt på tryckfördelningen. Slutsatsen är att Tekscan F-Scan kan användas för att mäta skillnader i tryck mellan olika ryggsäckar men metoden är på intet sätt felfri. Fler tester krävs för att bestämma Butterfly Bridges effekt. / <p>2022-07-01</p>
|
12 |
OPTIMIZACIÓN HEURISTICA MULTIOBJETIVO DE CIMENTACIONES DE SOPORTES EN MEDIANERIACano Pérez, Carlos 05 April 2016 (has links)
[EN] The main goal of this Thesis is the application of a suitable heuristic optimization algorithm that allows finding optimal solutions to the structural problem of faced brackets foundation, when one of them is located in a sharecropping, and therefore, the disposition of its foundation is prevented in one direction.
Since there are various structural models to solve the problem, it is the most commonly used in current practice. Isolated footings, constant width combined footing, asymmetrical combined footing, and beam brace eccentric shoe are the structural models finally selected.
Also, it has been confirmed the existence of various analytical models to solve the problem. Included in this Thesis is the simplest analysis model, commonly used inprofessional practice, and a more complex model that we call elastic simplified method.
The first is the named "Rigid foundation", which is based on the premise of a rigid behavior foundation. This implies the assumption of a linear distribution of the pressure transmitted to the ground. On the other hand, it will also analyze a model of analysis that does not limit the performance of the foundation only to the case of rigid foundation,modeling the terrain with springs through the so-called 'subgrade reaction'.
As a further aim of the Thesis, is to determine the structural model and the most suitable analysis model for solving the problem and determine the differences with other commonly used models.
Another objective of the thesis will be to evaluate the different objective functions, so that they may assess the optimal solution in terms of economic, environmental and ease of construction. From the literature review, it has noted the existence of numerous optimization studies conducted in search of economic optimum (cost of the solution, solution weight) and from the environmental point of view (CO2 emissions, energy consumption,
solution weight). From the standpoint of ease of construction of the solution, studies are lower, including parameters 'Armed uniformity, number of reinforcing bars or number of different bar types'. In this Thesis all these objective functions will be evaluated, incorporating environmental features such as the study of water consumption of the constituent materials and from the point of view of ease of construction, the
perimeter / area ratio and the parameter average diameter of the solution, which will be defined later.
Another of the objectives set for the thesis has been to be able to compare the results obtained by applying the "Simulated Annealing" algorithm, with the results that have been obtained in routine practice, following the usual process of structural calculation.A sample calculation in joint shoe is included in the book "Cálculo de estructuras de cimentacion" 4th edition from Calavera, comparing the values of objective functions of
the solution provided in the book, with those achieved after application of optimization SA algorithm and those collected after using a structural calculation software widely used in practice, as is "Cypecad ver 2014".
Finally, the ultimate goal of the thesis has been conducting a parametric study that allows providing the optimal solutions for a wide range of the problem under study configurations / [ES] El objetivo fundamental de la presente Tesis es la aplicación de un algoritmo de optimización heurístico adecuado, que permita localizar soluciones óptimas al problema estructural consistente en la cimentación de dos soportes enfrentados, cuando uno de ellos se sitúa en una medianería, y por tanto, tiene impedida en una dirección la disposición de su cimiento.
Dado que existen diversos modelos estructurales que permiten solucionar el problema, se ha seleccionado entre ellos, los más habitualmente utilizados en la práctica actual.. Los modelos estructurales finalmente seleccionados han sido los constituidos por zapatas aisladas, zapata combinada de ancho constante, zapata combinada asimétrica y zapata excéntrica con viga riostra.
También se ha podido confirmar la existencia de diversos modelos de análisis para la solución del problema, incuyéndose en la tesis tanto el modelo más sencillo de análisis, utilizado habitualmente en la práctica profesional, como un modelo más complejo que denominaremos, modelo elástico simplificado. El primero de ellos será el denominado 'Cimiento Rígido', donde se partirá de la premisa de un comportamiento rígido del
cimiento, lo que implicará la suposición de que presión transmitida al terreno sigue una distribución lineal. Por otro lado, se analizará también un modelo de análisis que no limitará el comportamiento del cimiento únicamente al caso de cimiento rígido, modelizando el terreno mediante muelles a través del denominado 'Módulo de Balasto'.
Como objetivo adicional de la tesis se establecerá el poder determinar el modelo estructural y el modelo de análisis más adecuado para la resolución del problema y determinar las diferencias con el resto de modelos usualmente utilizados.
Otro de los objetivos de la tesis será el de poder evaluar distintas funciones objetivo, de forma que se pueda evaluar el óptimo de una solución desde el punto de vista económico, medioambiental y de facilidad constructiva. De la revisión bibliográfica realizada, se ha podido constatar la existencia de numerosos estudios de optimización realizados en busca de óptimos económicos (coste de la solución, peso de la solución) y desde el punto de vista medioambiental (emisiones de CO2, consumo de energía, peso de la solución). Desde el punto de vista de la facilidad constructiva de la solución, los estudios realizados son menores, incluyéndose parámetros de 'Uniformidad de Armado, Número de barras de armado o número de tipo de barras distintos'. En la presente tesis se evaluarán todas estas funciones objetivo, incorporándose como funciones de tipo medioambiental, el estudio de consumo de agua de los materiales constituyentes de la solución y desde el punto de vista de la facilidad constructiva, la relación Perímetro/ Área y el parámetro Diámetro Medio de la solución, que se definirán más tarde.
Otro de los objetivos establecidos para la tesis ha sido el de poder comparar los resultados obtenidos mediante la aplicación del algoritmo de Simulated Annealing, con los resultados que se hubieran obtenido en la práctica profesional habitual, siguiendo los procesos habituales de cálculo estructural. Para ello, se desarrolla un ejemplo de cálculo de zapata en medianería incluido en el libro "Cálculo de estructuras de cimentación"
Edición 4, de Calavera, comparando los valores de las funciones objetivo de la solución aportada en el libro, con las alcanzadas tras la aplicación del algoritmo de optimización de SA y las conseguidas tras el uso de un software de cálculo estructural ampliamente utilizado en la práctica, como es 'Cypecad ver 2014'.
Por último, el objetivo final de la tesis ha sido la realización de un estudio paramétrico, que permita aportar las soluciones óptimas de un amplio abanicos de configuraciones del problema en estudio. / [CA] L'objectiu fonamental de la present Tesi és l'aplicació d'un algoritme d'optimització heurístic adequat, que permeta localitzar solucions òptimes al problema estructural consistent en la fonamentació de dos suports enfrontats, quan un d'ells se sitúa en una paret mitgera, i per tant, té impedida en una direcció la disposició del seu fonament.Atés que hi ha diversos models estructurals que permeten solucionar el problema, s'ha
seleccionat entre ells, els més habitualment utilitzats en la pràctica. Els models estructurals finalment seleccionats han sigut els constituïts per zapatas aïllades, zapata combinada d'ample constant, zapata combinada asimètrica i zapata excèntrica amb biga riostra.
També s'ha pogut confirmar l'existència de diversos models d'anàlisi per a la solució del problema, incuyéndose en la tesi tant el model més senzill d'analisis, utilitzat habitualment en la pràctica professional, com un model més complex que denominarem, model elàstic simplificat. El primer d'ells serà el denominat 'Cimiento Rígido', on es partirà de la premissa d'un comportament rígid del fonament, la qual cosa implicarà la
suposició que pressió transmesa al terreny seguix una distribució lineal. D'altra banda, s'analitzarà també un model d'anàlisi que no limitarà el comportament del fonament unicamente al cas de fonament rígid, odelizando el terreny per mitjà de molls a través del denominat 'Módulo de Balasto'.
Com a objectiu addicional de la tesi s'establirà el poder determinar el model estructural i el model d'anàlisi més adequat per a la resolució del problema i determinar les diferències amb la resta de models usualment utilitzats.
Un altre dels objectius de la tesi sera el de poder avaluar distintes funcions objectiu, de manera que es puga avaluar l'òptim d'una solució des del punt de vista econòmic, mediambiental i de facilitat constructiva. De la revisió bibliogràfica realitzada, s'ha pogut constatar l'existència de nombrosos estudis d'optimització realitzats a la cerca d'òptims econòmics (cost de la solució, pes de la solució) i des del punt de vista mediambiental
(emissions de CO2, consum d'energia, pes de la solució). Des del punt de vista de la facilitat constructiva de la solució, els estudis realitzats són menors, incloent-se paràmetres de 'Uniformidad d'Armat, nombre de barres d'armat o nombre de tipus de barres distintos'. En la present tesi s'avaluaren totes estàs funciones objectiu, incorporant-se com funciones de tipus mediambiental, l'estudi de consum d'aigua dels materials
constituents de la solució i des del punt de vista de la facilitat constructiva, la relació Perímetro/ Àrea i el paràmetre Diàmetre Mitjà de la solució, que es definirà més tard.
Un altre dels objectius establits per a la tesi ha sigut el de poder comparar els resultats obtinguts per mitjà de l'aplicació de l'algoritme de Simulated Annealing, amb els resultats que s'hagueren obtingut en la pràctica professional habitual, seguint els processos habituals de càlcul estructural. Per a això, es desenrotlla un exemple de càlcul de zapata en paret mitgera inclòs en el llibre "Cálculo d'estructures de cimentacion" Edició 4, de
Calavera, comparant els valors de les funcions objectiu de la solució aportada en el llibre, amb les aconseguides després de l'aplicació de l'algoritme d'optimització de SA i les aconseguides després de l'ús d'un programari de càlcul estructural ampliament utilitzat en la pràctica, com és 'Cypecad ver 2014'
Finalment, l'objectiu final de la tesi ha sigut la realització d'un estudi paramètric, que permeta aportar la solucions òptimes d'un ampli espectre de configuracions del problema en estudi / Cano Pérez, C. (2016). OPTIMIZACIÓN HEURISTICA MULTIOBJETIVO DE CIMENTACIONES DE SOPORTES EN MEDIANERIA [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/62208
|
13 |
Towards Automatic Generation of Personality-Adapted Speech and Emotions for a Conversational Companion Robot / Mot Automatisk Generering av Personlighets Anpassade Tal och Känslor för en Samtalskunnig Sällskaps RobotGalatolo, Alessio January 2022 (has links)
Previous works in Human-Robot Interaction have demonstrated the positive potential benefit of designing highly anthropomorphic robots. This includes physical appearance but also whether they can express emotions, behave in a congruent manner, etc. This work wants to explore the creation of a robot that is able to express a given personality consistently throughout a dialogue while also manifesting congruent emotional expressions. Personality defines many aspects of the character of a person and it can influence how one speaks, behaves, reacts to events, etc. Here, we only focus our attention on language and on how it changes depending on one particular personality trait, the extraversion. To this end, we tested different language models to automate the process of generating language according to a particular personality. We also compared large language models such as GPT-3 to smaller ones, to analyse how size can correlate to performance in this task. We initially evaluated these methods through a fairly small user study in order to confirm the correct manipulation of personality in a text-only context. Results suggest that personality manipulation and how well it is understood highly depend on the context of a dialogue, with a more ‘personal’ dialogue being more successful in manifesting personality. Also, the performance of GPT-3 is comparable to smaller models, specifically trained, with the main difference only given in the perceived fluency of the generations. We then conducted a follow-up study where we chose to use a robot that is capable of showing different facial expressions used to manifest different emotions, the Furhat robot. We integrated into the robot the generations from our language models together with an emotion classification method that is used to guide its facial expressions. Whilst the output of our models did trigger different emotional expressions, resulting in robots which differed both in their language and nonverbal behaviour, resultant perception of these robots’ personality only approached significance (p ∼ 0.08). In this study, GPT3 performed very similarly to much smaller models, with the difference in fluency also being much smaller than before. We did not see any particular change in the perception of the robots in terms of likeability nor uncanniness. / Tidigare arbeten inom Människa-robotinteraktion har visat den positiva potentiella fördelen med att designa mycket antropomorfa robotar. Detta inkluderar fysiskt utseende men också huruvida de kan uttrycka känslor, bete sig på ett kongruent sätt, etc. Detta arbete vill utforska skapandet av en robot som kan uttrycka en given personlighet konsekvent under en dialog samtidigt som den manifesterar kongruenta känslomässiga uttryck. Personlighet definierar många aspekter av en persons karaktär och den kan påverka hur man talar, beter sig, reagerar på händelser etc. Här fokuserar vi vår uppmärksamhet endast på språket och på hur det förändras beroende på ett särskilt personlighetsdrag, extraversion. För detta ändamål testade vi olika språkmodeller för att automatisera processen att skapa språk enligt en viss personlighet. Vi jämförde även stora språkmodeller som GPT-3 med mindre, för att analysera hur storlek kan relatera till prestanda i denna uppgift. Vi utvärderade inledningsvis dessa metoder genom en mindre användarstudie för att bekräfta att personligheten kan manipuleras på rätt sätt i en textbaserad kontext. Resultaten tyder på att personlighetsmanipulation och hur väl den förstås i hög grad beror på sammanhanget i en dialog, där en mer ‘personlig’ dialog är mer framgångsrik när det gäller att manifestera personlighet. Prestandan hos GPT-3 är också jämförbar med mindre modeller, specifikt tränade på en uppgift, där den största skillnaden var i den genererade textens upplevda flyt. Vi gjorde sedan en uppföljningsstudie där vi valde att använda en robot som är kapabel att visa olika ansiktsuttryck och därigenom kapabel att manifestera olika känslor, Furhat-roboten. Vi integrerade talet som genererades från våra språkmodeller i roboten tillsammans med en känsloklassificeringsmetod som används för att styra dess ansiktsuttryck. Medan resultatet av våra modeller framkallade olika känslomässiga uttryck, vilket resulterade i robotar som skilde sig åt både i språk och icke-verbal kommunikation, närmade sig endast den resulterande uppfattningen av dessa robotars personlighet signifikans (p ∼ 0.08). I denna studie presterade GPT-3 mycket likartat med mycket mindre modeller, med skillnaden i flyt också mycket mindre än tidigare. Vi såg ingen speciell förändring i uppfattningen av robotarna när det gäller sympati eller obehaglighet.
|
14 |
Seismic Design Of Cold Formed Steel Structures In Residential ApplicationsUygar, Celaletdin 01 May 2006 (has links) (PDF)
iv
ABSTRACT
SEISMIC DESIGN OF COLD FORMED STEEL STRUCTURES IN
RESIDENTIAL APPLICATIONS
Uygar, Celaletdin
M.Sc., Department of Civil Engineering
Supervisor: Prof. Dr. Ç / etin Yilmaz
May 2005, 82 pages
In this study, lateral load bearing capacities of cold formed steel framed wall panels are investigated. For this purpose lateral load bearing alternatives are analyzed numerically by computer models and results are compared with already done
experimental studies and approved codes.
In residential cold formed steel construction, walls are generally covered with cladding material like oriented strand board (OSB) or plywood on the exterior wall surface and these sheathed light gauge steel walls behave as shear walls with significant capacity. Oriented strand board is used in analytical models since OSB claddings are most commonly used in residential applications. The strength of shear walls depends on different parameters like screw spacing, strength of sheathing, size of fasteners used and aspect ratio. SAP2000 software is used for structural analysis of walls and joint force outputs are collected by Microsoft Excel.
The yield strength of shear walls at which first screw connection reaches its shear capacity is calculated and load carrying capacity per meter length is found. The nonlinear analysis is also done by modeling the screw connections between OSB and frame as non-linear link and the nominal shear capacities of walls are calculated for different screw spacing combinations. The results are consistent with the values in shear wall design Guide and International Building Code 2003. The other lateral load bearing method is flat strap X-bracing on wall surfaces. Various parameters like wall frame section thickness, flat strap area, aspect ratio and bracing number are investigated and results are evaluated.
The shear walls in which X-bracing and OSB sheathing used together are also analyzed and the results are compared with separate analyses.
|
15 |
Fatigue life enhancement of aircraft structures through bonded crack retarders (BCR)Doucet, Jeremy January 2015 (has links)
The trend in aircraft design is to produce greener airplanes through lighter structures and/or structures with extended life and reduced maintenance. Bonded crack retarders (BCR) are one of the solutions towards that objective. BCR are reinforcing straps bonded to the structure in order to improve the fatigue and damage tolerance properties of the assembly. The aim of this study was to demonstrate that the BCR hybrid technology – beneficial for upper wing cover – could also be applied to lower wing covers. The project also focused on evaluating BCR most important parameters. The fatigue life improvement obtained from BCR was evaluated through a series of coupons and skin-stringer assemblies tested under constant and variable amplitude loading. While the coupon tests demonstrated a life improvement of only 17% under constant amplitude loading, the variable amplitude load tests performed on the skin-stringer assembly demonstrated increased fatigue lives with a factor of 5 and reduced crack growth rates with a factor of 5 to 6. A finite element calculation tool was developed in order to conduct a parametric analysis of BCR geometry through the evaluation of the substrate stress intensity factor in the case of fatigue loading. The main difficulty was to include the interacting mechanism of the substrate lead crack and the disbond of the adhesive layer. The novelty of the approach was to incorporate the fatigue delamination calculation in order to evaluate the fatigue disbond propagation with crack growth. This was embedded in a 3D finite element design tool ReSLIC (Reinforced Structures Life Improvement Calculation). A necessary step to the development of ReSLIC was the analysis of fatigue properties of the adhesive system in order to provide input data for fatigue delamination calculations. To that end, a series of fatigue tests were performed in pure Mode I, pure Mode II and mixed mode with ratios of 25%, 50% and 75% of mode II ... [cont.].
|
16 |
Avaliação experimental da interação solo coesivo-fita polimérica sob condições de teor de umidade variáveis. / Experimental evaluation of the effect of soil moisture content on cohesive soil-geosynthetic strap interaction.Orlando, Patrícia Del Gaudio 20 March 2015 (has links)
Em geral, as recomendações normativas sugerem a utilização de materiais granulares para a construção de estruturas em solo reforçado, principalmente devido à sua elevada resistência ao cisalhamento e boa capacidade de drenagem. No entanto, nem sempre há disponibilidade deste tipo de material no entorno das obras, tornando o uso dos solos finos imperativo para a viabilização desta solução. No Brasil, solos residuais finos são encontrados em abundância e, muitas vezes, apresentam excelentes parâmetros de resistência ao cisalhamento e baixa compressibilidade. Contudo, o seu uso pode induzir poro-pressões indesejáveis durante a construção ou cisalhamento do aterro reforçado. Por outro lado, as elevadas sucções matriciais que podem persistir em seu interior geram um aumento na estabilidade dos maciços reforçados. Neste contexto, este trabalho apresenta os resultados experimentais e discute o efeito da variação climática (umedecimento e secagem) na resistência de interface solo coesivo-fita polimérica de uma estrutura de contenção em solo reforçado. Os ensaios foram realizados com amostras compactadas de um solo residual de gnaisse típico da cidade de São Paulo e uma fita polimérica de alta aderência. Os corpos de prova foram submetidos a ensaios de cisalhamento direto e de arrancamento sob três diferentes níveis de tensão normal e de sucção, além da condição inundada. Ensaios triaxiais saturados (CU) e não saturados (CW) foram realizados para a determinação da envoltória de resistência tridimensional do solo, avaliação da eficiência da interação solo-reforço e para a verificação do comportamento da água intersticial durante o cisalhamento. Os resultados indicam que o solo coesivo em questão apresenta excelentes parâmetros de resistência ao cisalhamento, elevada capacidade de se manter sob pressões negativas da água intersticial e uma eficiente interação com as fitas poliméricas, o que possibilitaria a execução de estruturas estáveis quanto ao arrancamento dos reforços. Além disso, sugerem um crescimento não linear da máxima resistência de interface com o aumento da sucção matricial do solo e uma tendência de redução dos coeficientes de atrito aparente solo-reforço (f*) com o umedecimento das amostras. Porém, mostraram que a sucção matricial exerce pouca influência na resistência residual da interface solo reforço. / Current specifications for reinforced soil structures generally require the use of granular backfill due to their high strength, well drainage capacity and low volume change potential. However, in cases where granular fills are not easily and readily available, poorly draining soils should be used to enable the implementation of a mechanically stabilized earth wall (MSEW). In Brazil, the fine-grained residual soils that cover large areas of its territory frequently present high shear strengths and low compressibility. However, the use of cohesive soils can cause unwanted effects in structure stability due to the water content variations of the backfill soil, and the potential development of pore-water pressures or loss of strength. On the other hand, matric suctions may increase the soil-geosynthetic interface shear strength. In this context, this study presents the experimental results and discusses the effects of seasonal climatic variations (wetting and drying) on shear strength of soil-geosynthetic straps interfaces under unsaturated conditions. For the laboratory investigation, a compacted residual soil of gneiss composed of 80% silty sand passed through a 0.075mm sieve, sourced from São Paulo city, and a high-tenacity polyester strap were used. Direct shear and pullout tests were conducted with three different net normal stresses and levels of matric suction, besides the inundated condition. Triaxial tests under saturated (CU) and unsaturated (CW) conditions with suction measurement using a high capacity tensiometer were performed in order to evaluate the shear strength parameters of the unsaturated soil, the interface efficiency of the soil-geosynthetic strap and the pore water pressure variations during shear. The results indicate that the cohesive soil used in this study has excellent shear strength parameters, a high capacity to maintain negative pore water pressures and presents an efficient interaction with the geosynthetics straps, which would allow the implementation of a stable MSEW for failure by pullout. Furthermore they reveal that the peak shear strength of the soil-geosynthetic strap interface increases nonlinearly with the soil suction, while the apparent friction factor (f*) decreases with the increase in molding moisture contents. On the other hand, the effect of suction on the post-peak shear strength of the interface was negligible.
|
17 |
Contrainte biomécanique unilatérale versus contrainte biomécanique bilatérale : rééquilibrage des acapacités fonctionnelles et amélioration de la performance dans une tâche locomotrice / Unilateral biomechanical constraint versus bilateral biomechanical constraint : Rebalancing of functional capacities and improvement of performance on locomotive taskDelafontaine, Arnaud 12 December 2013 (has links)
Dans la littérature, les résultats, dans le domaine de la rééducation neurologique des patients hémiplégiques, montraient que la performance motrice du membre atteint était améliorée lorsque les deux membres homolatéraux étaient mobilisés dans des mouvements symétriques. Il a alors été suggéré que le système nerveux avait plus de facilité à adapter une commande bilatérale symétrique, qu’une commande bilatérale asymétrique.L’objet des travaux dans cette thèse est de tester la généralité de ces résultats dans le cas du processus d’initiation de la marche (IM). Le handicap est simulé par une hypomobilité de la cheville, induite avec strapping et orthèse unilatéralement ou bilatéralement. Les résultats montrent que, dès la présence d’une contrainte, la biomécanique et les activités électromyographiques, des phases de préparation posturale et d’exécution du processus d’IM, sont modifiées. De plus, la performance motrice est également perturbée. Toutefois, il apparaît des différences « locales » selon où s'applique la contrainte. Un résultat est à souligner tout particulièrement : comme pour les patients hémi-handicapés, la performance motrice (i.e. vitesse du centre des masses à la fin du premier pas) est supérieure dans la condition « contrainte bilatérale i.e. hypomobilité des deux chevilles » versus « contrainte unilatérale i.e. hypomobilité du pied d’appui ». L’ensemble des résultats est discuté dans le cadre des processus d’adaptation de la commande motrice face aux contraintes biomécaniques unilatérales et bilatérales induites sur les appuis. En d'autres termes, tout se passe comme si un rééquilibrage des capacités fonctionnelles s’opère, permettant ainsi de générer une meilleure performance motrice. Enfin, les résultats permettent d’envisager des perspectives dans le domaine de la rééducation fonctionnelle. / In the literature, the rehabilitation of hemiplegic patients showed that motor performance of the affected limb is improved when both limbs are mobilised in a symmetrical movement. It has been suggested that it was easier for the nervous system to adapt to symmetrical bilateral command. The aim of this dissertation is to test the validity of these results in gait initiation (GI). Handicap was simulated by means of blocking the ankle unilaterally or bilaterally with a strap or orthosis.Results showed that in the presence of a constraint, electromyographic activity and the kinematics of both postural preparation and step execution phase of GI declined. Furthermore, the motor performance was also perturbed.However, « Local » differences appeared according to the localisation of the constraint, reflecting the adaptation of the motor command. Nonetheless, a result needs to be particularly underlying.Like in hemi-handicapped patients, the motor performance (i.e. centre of mass velocity at the end of the first step) was higher in « bilateral constraint, hypomobility on both ankles » versus « unilateral constraint, hypomobility on stance ankle ».In the dissertation, the results are discussed in terms of the adaptation of the motor command of unilateral and bilateral induced biomechanical constraint. More specifically, we discuss how rebalancing the functional capacity of both legs should allow to increase motor performance. These results put forward new perspectives in the domain of functional rehabilitation.
|
18 |
Avaliação experimental da interação solo coesivo-fita polimérica sob condições de teor de umidade variáveis. / Experimental evaluation of the effect of soil moisture content on cohesive soil-geosynthetic strap interaction.Patrícia Del Gaudio Orlando 20 March 2015 (has links)
Em geral, as recomendações normativas sugerem a utilização de materiais granulares para a construção de estruturas em solo reforçado, principalmente devido à sua elevada resistência ao cisalhamento e boa capacidade de drenagem. No entanto, nem sempre há disponibilidade deste tipo de material no entorno das obras, tornando o uso dos solos finos imperativo para a viabilização desta solução. No Brasil, solos residuais finos são encontrados em abundância e, muitas vezes, apresentam excelentes parâmetros de resistência ao cisalhamento e baixa compressibilidade. Contudo, o seu uso pode induzir poro-pressões indesejáveis durante a construção ou cisalhamento do aterro reforçado. Por outro lado, as elevadas sucções matriciais que podem persistir em seu interior geram um aumento na estabilidade dos maciços reforçados. Neste contexto, este trabalho apresenta os resultados experimentais e discute o efeito da variação climática (umedecimento e secagem) na resistência de interface solo coesivo-fita polimérica de uma estrutura de contenção em solo reforçado. Os ensaios foram realizados com amostras compactadas de um solo residual de gnaisse típico da cidade de São Paulo e uma fita polimérica de alta aderência. Os corpos de prova foram submetidos a ensaios de cisalhamento direto e de arrancamento sob três diferentes níveis de tensão normal e de sucção, além da condição inundada. Ensaios triaxiais saturados (CU) e não saturados (CW) foram realizados para a determinação da envoltória de resistência tridimensional do solo, avaliação da eficiência da interação solo-reforço e para a verificação do comportamento da água intersticial durante o cisalhamento. Os resultados indicam que o solo coesivo em questão apresenta excelentes parâmetros de resistência ao cisalhamento, elevada capacidade de se manter sob pressões negativas da água intersticial e uma eficiente interação com as fitas poliméricas, o que possibilitaria a execução de estruturas estáveis quanto ao arrancamento dos reforços. Além disso, sugerem um crescimento não linear da máxima resistência de interface com o aumento da sucção matricial do solo e uma tendência de redução dos coeficientes de atrito aparente solo-reforço (f*) com o umedecimento das amostras. Porém, mostraram que a sucção matricial exerce pouca influência na resistência residual da interface solo reforço. / Current specifications for reinforced soil structures generally require the use of granular backfill due to their high strength, well drainage capacity and low volume change potential. However, in cases where granular fills are not easily and readily available, poorly draining soils should be used to enable the implementation of a mechanically stabilized earth wall (MSEW). In Brazil, the fine-grained residual soils that cover large areas of its territory frequently present high shear strengths and low compressibility. However, the use of cohesive soils can cause unwanted effects in structure stability due to the water content variations of the backfill soil, and the potential development of pore-water pressures or loss of strength. On the other hand, matric suctions may increase the soil-geosynthetic interface shear strength. In this context, this study presents the experimental results and discusses the effects of seasonal climatic variations (wetting and drying) on shear strength of soil-geosynthetic straps interfaces under unsaturated conditions. For the laboratory investigation, a compacted residual soil of gneiss composed of 80% silty sand passed through a 0.075mm sieve, sourced from São Paulo city, and a high-tenacity polyester strap were used. Direct shear and pullout tests were conducted with three different net normal stresses and levels of matric suction, besides the inundated condition. Triaxial tests under saturated (CU) and unsaturated (CW) conditions with suction measurement using a high capacity tensiometer were performed in order to evaluate the shear strength parameters of the unsaturated soil, the interface efficiency of the soil-geosynthetic strap and the pore water pressure variations during shear. The results indicate that the cohesive soil used in this study has excellent shear strength parameters, a high capacity to maintain negative pore water pressures and presents an efficient interaction with the geosynthetics straps, which would allow the implementation of a stable MSEW for failure by pullout. Furthermore they reveal that the peak shear strength of the soil-geosynthetic strap interface increases nonlinearly with the soil suction, while the apparent friction factor (f*) decreases with the increase in molding moisture contents. On the other hand, the effect of suction on the post-peak shear strength of the interface was negligible.
|
19 |
Bezpečnost zařízení pro upínání obrobků / Safety of workpiece clamping deviceMahel, Petr January 2018 (has links)
Master’s thesis is dealing with safety of workpiece clamping device. In the first part we are describing possibilities of clamping workpiece on different machines, legislative conditions in EU and CR in engineering devices, and general demands that refer to harmonized standards for different types of clamping devices. The main target of the thesis are the lists of requirements for hydraulic three-jaw chucks and proposal of two chosen safety applications. The first safety application refers to safety of clamping workpiece in hydraulic chuck. The second safety application is aimed at clamping of workpiece with the help of strap clamps. There is a description of the procedure of calculation of safe tightening moment during assembly of the nut.
|
20 |
The Effects of Multi-Axial Loading on Adhesive JointsMcFall, Bruce Daniel 01 June 2018 (has links)
No description available.
|
Page generated in 0.0466 seconds