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Analýza pohybu dolních končetin při sportovním pohybu člověka - dřep. / Motion analysis of lower extremity during squatting.Varga, Pavel January 2017 (has links)
Title: Motion analysis of lower extermity during squatting Aims: The aim of the thesis is to compare the squat without and with external load in a group of people who work under professional guidance and have experience with this movement, contrary to the people of the common population. Another objective will be the compasion this movement among men and women of the common population. In the theoretical part, the main objective is to describe the basic characteristic of the squat, describe the kinesiological and biomechanical findings and the risks of this movement on the locomotive apparatus. The experimental part will focus on the observation of the determined kinematic parameters of squats and their comparison in the mentioned set of persons. The results of the work should clarify the possible side effects of the squat. Methods: Kinematic analysis will be performed using Qualisys instrumentation. Infrared cameras accurately record and further perform a motion action through passive or active reflection markers. Data from the device will be processed in Microsoft Office Excel software and further evaluated statistically. Results: The results show that there are significant variations in the performance of the movement among groups of men actively engaged in squats under professional guidance and...
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Performance characteristics of a deep tilling rotavatorMarenya, Moses Okoth 11 June 2010 (has links)
This study was undertaken to develop an analytical model that is capable of predicting the torque requirements of a rotavator fitted with commercially available L-shaped blades. An analytical approach based on the limit equilibrium analysis was used to develop the proposed model. The proposed model was verified by comparing the model and measured torque requirements at predetermined rotavator blade angular positions from the horizontal for a down-cut rotavator. The study findings indicated that there was an optimum set tillage depth for each rotavator configuration and operational conditions at which the resultant horizontal thrust generated was greatest. This unique depth was influenced by the bite length. The validation of the proposed model showed that the predicted and measured torque requirements, at different angular blade positions from the horizontal, correlated reasonably well for all the set tillage depths. As the depth of tillage increased, however, the curve for the measured torque requirements exhibited a cyclic behaviour after the peak torque requirements value had been recorded. The cyclic behaviour was probably due to the re-tilling and the instability of the tool-frame carrier, which increased with the set tillage depth. The knowledge contributed by this research will afford the designers of active tillage tools a better understanding of the operations of the rotavator, particularly in deep tillage. The modelling approach, and instrumentation technique used in this research, can be extended to analyze the performance of rotavators fitted with other types of commercial blades. / Thesis (PhD)--University of Pretoria, 2010. / Civil Engineering / unrestricted
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Modelling of friction stir spot weldingReilly, Aidan January 2013 (has links)
Friction stir spot welding (FSSW) is a solid-state welding process which is especially useful for joining precipitation-hardened aluminium alloys that undergo adverse property changes during fusion welding. It also has potential as an effective method for solid-state joining of dissimilar alloys. In FSSW, heat generation and plastic flow are strongly linked, and the scale of the process in time and space is such that it is difficult to separate and control the influence of all the relevant input parameters. The use of modelling is well-established in the field of welding research, and this thesis presents an analysis of the thermal and mechanical aspects of FSSW, principally using the finite element (FE) technique. Firstly, a thermal FE model is shown, which is subsequently validated by reference to experimental temperature data in both aluminium-to-aluminium and aluminium-to-steel welds. Correlations between high-quality welds and temperature fields are established, and predictions are made for peak temperatures reached under novel welding conditions. Deformation and heating are strongly linked in FSSW, but existing modelling tools are poorly suited to modelling flow processes in the conditions extant in FSSW. This thesis discusses the development and optimisation of two novel techniques to overcome the limitations of current approaches. The first of these uses greatly simplified constitutive behaviour to convert the problem into one defined purely by kinematics. In doing so, the boundary conditions reduce to a small number of assumptions about the contact conditions between weld material and tool, and the model calculation time is very rapid. This model is used to investigate changes in the slip condition at the tool to workpiece interface without an explicit statement of the friction law. Marker experiments are presented which use dissimilar composition but similar strength alloys to visualise flow patterns. The layering behaviour and surface patterns observed in the model agree well with observations from these experiments. The second approach extends the FE method to include deformation behaviour without the need for a fully-coupled approach, guided by the kinematic model. This is achieved using an innovative sequential small-strain analysis method in which thermal and deformation analyses alternate, with each running at a very different timescale. This technique avoids the requirement to either remesh the model domain at high strains or to use an explicit integration scheme, both of which impose penalties in calculation time and model complexity. The method is used to relate the purely thermal analysis developed in the work on thermal modelling to welding parameters such as tool speed. The model enables predictions of the spatial and temporal evolution of heat generation to be made directly from the constitutive behaviour of the alloy and the assumed velocity profile at the tool-workpiece interface. Predictions of the resulting temperature history are matched to experimental data and novel conditions are simulated, and these predictions correlate accurately with experimental results. Hence, the model is used to predict welding outcomes for situations for which no experimental data exists, and process charts are produced to describe optimum welding parameters. The methods and results presented in this thesis have significant implications for modelling friction stir spot welding, from optimising process conditions, to integration with microstructural models (to predict softening in the heat-affected zone, or the formation of intermetallics at the interface in dissimilar welds). The technique developed for sequential small strain finite element analysis could also be investigated for use in other kinematically constrained solid-state friction joining processes.
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Towards Automated Design of Toggle Switch MechanismsKalyan Ramana, G January 2016 (has links) (PDF)
This work deals with addressing the issues related to design of double toggle switch mechanisms with emphasis on structural, dimensional and dynamic aspects. Currently, almost all the issues related to electrical switches are dealt from electromagnetic point of view; the operating mechanism is hardly touched. It is observed that kinematic parameters influence electrical performance of switch significantly. Therefore, there is a need to develop methodologies for supporting exploration of diverse kinematic chains (KCs) for this purpose. Visual inspection is tedious and error prone even when a complete list of design criteria is available, hence, the work presented in the thesis contributes towards automated design of toggle switch mechanisms.
In this context, in house modular kinematics data structure is found useful for using it as a tool in the design of toggle switch. Modular kinematics, typically used for kinematic analysis, works on the principle of finding the configuration of a mechanism using a given set of modules by a procedure called module sequence. This module sequence is used and interpreted in a number of ways for its effective use in various design stages. Structurally, a set of seven conditions must be satisfied by a KC to exhibit double toggle. These conditions are broadly classified into three categories: criteria for KC, function assignment criteria and criteria for stoppers. These three criteria are to be checked automatically by use of module sequence in the same order as mentioned.
In the criteria for KC, one of the conditions is that, the KC should not have fractionated degrees of freedom (d.o.f.). Hence, detection of fractionation in a KC is inevitable. In literature, is was found that the algorithms for detection operate at their worst case complexity, O(n4), and some of them do not report joint fractionation. Thus, the algorithms are not only robust but also computationally expensive. Therefore, a frugal and comprehensive method O(n2) is implemented to detect fractionation using modular kinematics. Also, inherent structural pattern embedded in fractionated KCs is hardly studied in literature. It is found that the way body and joint fractionation is defined in fractionated KCs is inconsistent. So, fractionation is interpreted as symbolic partitioning of joints and links in the traditional body and joint fractionation types respectively. Based on the number of ways of partitioning, simple and multiple types of fractionation are recognized. Valid partitions are identified using the notion of fractionating and non-fractionating subchains. Relative locations of these subchains influence distribution of d.o.f. across the fractionated KC. Conventional representation of KCs as links and joints or graphs is difficult to comprehend this distribution. For this, a novel concept of fractionation graph is introduced that gives d.o.f. distribution information and the relative locations of the constituent subchains across the KC. Modular kinematics gives a constructive description of fractionated KCs. Characterization of fractionated KCs, based on presence of multiple separation links, is introduced as order of fractionation. Uniqueness for a given order of fractionation is also justified.
After the criteria for KC, a KC is tested for feasibility for function assignment criteria. This requires recognition of active and passive subchains of the KC with respect to input and output pairs. For this, module sequence is characterized for recognition of the subchains. Based on these subchains, locations of stoppers are derived. Using this information, an algorithmic approach to assign functions (functions like spring, ground link, input link, etc.) to derive distinct driving mechanisms provided isomorphic elements (links and joints) of the KC are known beforehand, is introduced.
The design parameters influencing dimensional synthesis have been identified as dimensions of links, spring anchor points and stopper locations. Sub-problems associated with each parameter are analyzed. It is found out that optimum location of stoppers for selecting operational range of motion is necessary by taking into account the considerations of timing of switch and impact velocity. Based on the analysis, an algorithmic way to design single toggle switch mechanisms is introduced.
Timing for closing or opening of a switch is one of the critical measure that determines its performance. Timing should be as low as possible without exceeding the impact velocity at the instant contacts meet each other. Timing of a switch depends on the dimensions of the links, inertial parameters, spring stiffness etc. For a given timing for a mechanism, dynamic synthesis, in this thesis, deals with finding the inertial parameters of the links using Quinn's energy distribution method, modular kinematics, and Nelder and Mead's downhill simplex method for optimization. This thesis helps the designer to use modular kinematics as a potential automated tool to select a valid design to make the solution space more meaningful in the design of toggle switch mechanisms.
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Análise biomecânica de atividades de vida diária realizadas por pessoas com osteoartrite de joelho / Biomechanical analysis of daily activities carried out by people with knee osteoarthritisRoberto Bianco 23 January 2017 (has links)
O objetivo do trabalho é investigar como as condições biomecânicas de portadores de Osteoartrite (OA) de joelho afetam a capacidade de realizar atividades de vida diária. Participaram desse estudo 39 indivíduos, sendo 18 indivíduos com OA de joelho bilateral grau 3, na escala Kellgren Lawrence, e 21 indivíduos saudáveis. Foram utilizadas duas plataformas de força (AMTI) para registrar a Força de Reação do Solo, cinco câmeras (Sistema Vicon) para registrar as variações angulares das articulações do quadril, joelho e tornozelo, nos planos sagital e frontal, e cinco sensores de eletromiografia wireless (Sistema Noraxon) para registrar as atividades dos músculos reto femoris (RF), vastus lateralis (VL), biceps femoris (BF), tibialis anterior (TA) e gastrocnemius lateralis (GL) no segmento dominante (segmento D) dos sujeitos do grupo controle e no segmento com maior gravidade de lesão nos indivíduos com OA (segmento OA). Também foram calculados por meio de dinâmica inversa os momentos articulares nos planos sagital e frontal. Três atividades de vida diária foram investigadas, a marcha, o levantar e sentar em uma cadeira e o descer de um degrau de 20cm. Nos resultados, foi observada uma menor variação angular de forma geral nas articulações do quadril e joelho. Não foi observada diferença nas cargas mecânicas aplicadas ao aparelho locomotor. Nas três atividades cotidianas, os indivíduos com OA apresentaram adução no quadril e abdução no joelho, que denota um alinhamento em valgo durante a execução das tarefas. Poucas diferenças foram observadas nos momentos articulares flexores e extensores, nas três atividades de vida diária investigadas. No levantar e sentar menores momentos extensores foram observados no joelho durante as duas fases do movimento. Nos momentos adutores, poucas diferenças foram observadas na marcha. No levantar e sentar, o segmento OA não apresentou momentos adutores de joelho maiores que nos outros segmentos. No descer degrau, o segmento CL apresentou maior momento adutor que o segmento OA e D. De forma geral, as diferenças na ativação muscular indicam maior intensidade de ativação no grupo controle. O músculo VL nas três atividades apresentou intensidade de ativação menor nos indivíduos com OA. Observou-se maior co-ativação na marcha e no descer degrau, mas não no levantar e sentar. Na marcha a maior co-ativação ocorreu nas três articulações. No descer degrau, ocorreu no quadril e no joelho. Nas três atividades, maior co-contração foi observada e principalmente no joelho. Conclui-se que as alterações na técnica de movimento mostram-se tarefa dependente. As alterações na execução do movimento no plano sagital não foram suficientes para afetar o controle das cargas mecânicas, na marcha e no descer degrau. Apenas na tarefa de levantar e sentar surgiu algum indicio de que a eficiência seria pior. O alinhamento no joelho e os momentos adutores não sugerem maior magnitude de força no compartimento medial do joelho. Aparentemente, as características temporais sejam mais sensíveis à presença da OA no joelho do que a intensidade de ativação / The aim of this study is to investigate the biomechanical characteristics of patients with knee osteoarthritis (OA) and hoe it affects the ability to perform daily living activities. Thirty nine subjects participated in this study, 18 subjects with bilateral knee OA grade 3 Kellgren Lawrence scale) and 21 healthy individuals. Two force platforms (AMTI) were used to register the Grourd Reaction Force (GRF). Five cameras (System Vicon) were used to register the angular variations of the hip, knee and ankle in the sagittal and frontal planes. Five electromyographic electrodes (Noraxon System) were used to record the activities of the rectus femoris (RF), vastus lateralis (VL), biceps femoris (BF), tibialis anterior (TA) and gastrocnemius lateralis (GL) in the dominant segment (D segment) on control group and the segment with greater severity of injury in individuals with OA (OA segment). Inverse dynamics was used to calculate joint moments sagittal and frontal planes. Three daily living activities were investigated, the gait, the Sit-to stand and Stand-to-sit and Stepping down from a 20cm height step. In results, there was a smaller angular variation in hip and knee joints. No difference was observed in the mechanical loads applied to the locomotor system. In the three daily activities, people with knee OA showed hip adduction and knee abduction, in the three daily activities, which suggests an alignment valgus in the knee. Few differences were observed in joint moments in the three daily living activities. In sit-to-stand and stand-to-sit lower peak extensor moments were observed in the knee. Few differences were observed in adductor moments in gait. In sit-to-stand and stand-to-sit, no difference was observed in knee adductor moments. In stepping down, the CL segment showed greater adductor moment than OA segment and D. In general, differences in muscle activation indicate greater activation intensity in the control group. The VL muscle showed lower activation intensity in individuals with OA in all three activities. A higher co-activation was observed in gait and in stepping down, but not in sit-to-stand and stand-to-sit. In gait the higher co-activation occurred subjects with knee OA in the three joints. In stepping down, higher co-activation occurred in the hip and knee. In the three activities, greater co-contraction was observed and especially in the knee. It can be concluded that changes in movement technique appears to be task dependent. Changes in movement technique in the sagittal plane were not enough to affect the control of the mechanical loads on gait and stepping down movements. Only in sit-to-stand and stand-to-sit some indication of worse efficiency to perform the task was observed. Knee alignment and knee adductor moments do not suggest greater magnitude of force in the medial compartment of the knee. Apparently, the temporal characteristics of muscle activity are more sensitive to the presence of knee OA than the intensity of activation
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Contributions to Pen & Touch Human-Computer InteractionMartín-Albo Simón, Daniel 01 September 2016 (has links)
[EN] Computers are now present everywhere, but their potential is not fully exploited due to some lack of acceptance. In this thesis, the pen computer paradigm is adopted, whose main idea is to replace all input devices by a pen and/or the fingers, given that the origin of the rejection comes from using unfriendly interaction devices that must be replaced by something easier for the user.
This paradigm, that was was proposed several years ago, has been only recently fully implemented in products, such as the smartphones. But computers are actual illiterates that do not understand gestures or handwriting, thus a recognition step is required to "translate" the meaning of these interactions to computer-understandable language. And for this input modality to be actually usable, its recognition accuracy must be high enough. In order to realistically think about the broader deployment of pen computing, it is necessary to improve the accuracy of handwriting and gesture recognizers. This thesis is devoted to study different approaches to improve the recognition accuracy of those systems.
First, we will investigate how to take advantage of interaction-derived information to improve the accuracy of the recognizer. In particular, we will focus on interactive transcription of text images. Here the system initially proposes an automatic transcript. If necessary, the user can make some corrections, implicitly validating a correct part of the transcript. Then the system must take into account this validated prefix to suggest a suitable new hypothesis. Given that in such application the user is constantly interacting with the system, it makes sense to adapt this interactive application to be used on a pen computer. User corrections will be provided by means of pen-strokes and therefore it is necessary to introduce a recognizer in charge of decoding this king of nondeterministic user feedback. However, this recognizer performance can be boosted by taking advantage of interaction-derived information, such as the user-validated prefix.
Then, this thesis focuses on the study of human movements, in particular, hand movements, from a generation point of view by tapping into the kinematic theory of rapid human movements and the Sigma-Lognormal model. Understanding how the human body generates movements and, particularly understand the origin of the human movement variability, is important in the development of a recognition system. The contribution of this thesis to this topic is important, since a new technique (which improves the previous results) to extract the Sigma-lognormal model parameters is presented.
Closely related to the previous work, this thesis study the benefits of using synthetic data as training. The easiest way to train a recognizer is to provide "infinite" data, representing all possible variations. In general, the more the training data, the smaller the error. But usually it is not possible to infinitely increase the size of a training set. Recruiting participants, data collection, labeling, etc., necessary for achieving this goal can be time-consuming and expensive. One way to overcome this problem is to create and use synthetically generated data that looks like the human. We study how to create these synthetic data and explore different approaches on how to use them, both for handwriting and gesture recognition.
The different contributions of this thesis have obtained good results, producing several publications in international conferences and journals.
Finally, three applications related to the work of this thesis are presented. First, we created Escritorie, a digital desk prototype based on the pen computer paradigm for transcribing handwritten text images. Second, we developed "Gestures à Go Go", a web application for bootstrapping gestures. Finally, we studied another interactive application under the pen computer paradigm. In this case, we study how translation reviewing can be done more ergonomically using a pen. / [ES] Hoy en día, los ordenadores están presentes en todas partes pero su potencial no se aprovecha debido al "miedo" que se les tiene. En esta tesis se adopta el paradigma del pen computer, cuya idea fundamental es sustituir todos los dispositivos de entrada por un lápiz electrónico o, directamente, por los dedos. El origen del rechazo a los ordenadores proviene del uso de interfaces poco amigables para el humano.
El origen de este paradigma data de hace más de 40 años, pero solo recientemente se ha comenzado a implementar en dispositivos móviles. La lenta y tardía implantación probablemente se deba a que es necesario incluir un reconocedor que "traduzca" los trazos del usuario (texto manuscrito o gestos) a algo entendible por el ordenador. Para pensar de forma realista en la implantación del pen computer, es necesario mejorar la precisión del reconocimiento de texto y gestos. El objetivo de esta tesis es el estudio de diferentes estrategias para mejorar esta precisión.
En primer lugar, esta tesis investiga como aprovechar información derivada de la interacción para mejorar el reconocimiento, en concreto, en la transcripción interactiva de imágenes con texto manuscrito. En la transcripción interactiva, el sistema y el usuario trabajan "codo con codo" para generar la transcripción. El usuario valida la salida del sistema proporcionando ciertas correcciones, mediante texto manuscrito, que el sistema debe tener en cuenta para proporcionar una mejor transcripción. Este texto manuscrito debe ser reconocido para ser utilizado. En esta tesis se propone aprovechar información contextual, como por ejemplo, el prefijo validado por el usuario, para mejorar la calidad del reconocimiento de la interacción.
Tras esto, la tesis se centra en el estudio del movimiento humano, en particular del movimiento de las manos, utilizando la Teoría Cinemática y su modelo Sigma-Lognormal. Entender como se mueven las manos al escribir, y en particular, entender el origen de la variabilidad de la escritura, es importante para el desarrollo de un sistema de reconocimiento, La contribución de esta tesis a este tópico es importante, dado que se presenta una nueva técnica (que mejora los resultados previos) para extraer el modelo Sigma-Lognormal de trazos manuscritos.
De forma muy relacionada con el trabajo anterior, se estudia el beneficio de utilizar datos sintéticos como entrenamiento. La forma más fácil de entrenar un reconocedor es proporcionar un conjunto de datos "infinito" que representen todas las posibles variaciones. En general, cuanto más datos de entrenamiento, menor será el error del reconocedor. No obstante, muchas veces no es posible proporcionar más datos, o hacerlo es muy caro. Por ello, se ha estudiado como crear y usar datos sintéticos que se parezcan a los reales.
Las diferentes contribuciones de esta tesis han obtenido buenos resultados, produciendo varias publicaciones en conferencias internacionales y revistas.
Finalmente, también se han explorado tres aplicaciones relaciones con el trabajo de esta tesis. En primer lugar, se ha creado Escritorie, un prototipo de mesa digital basada en el paradigma del pen computer para realizar transcripción interactiva de documentos manuscritos. En segundo lugar, se ha desarrollado "Gestures à Go Go", una aplicación web para generar datos sintéticos y empaquetarlos con un reconocedor de forma rápida y sencilla. Por último, se presenta un sistema interactivo real bajo el paradigma del pen computer. En este caso, se estudia como la revisión de traducciones automáticas se puede realizar de forma más ergonómica. / [CAT] Avui en dia, els ordinadors són presents a tot arreu i es comunament acceptat que la seva utilització proporciona beneficis. No obstant això, moltes vegades el seu potencial no s'aprofita totalment. En aquesta tesi s'adopta el paradigma del pen computer, on la idea fonamental és substituir tots els dispositius d'entrada per un llapis electrònic, o, directament, pels dits. Aquest paradigma postula que l'origen del rebuig als ordinadors prové de l'ús d'interfícies poc amigables per a l'humà, que han de ser substituïdes per alguna cosa més coneguda. Per tant, la interacció amb l'ordinador sota aquest paradigma es realitza per mitjà de text manuscrit i/o gestos.
L'origen d'aquest paradigma data de fa més de 40 anys, però només recentment s'ha començat a implementar en dispositius mòbils. La lenta i tardana implantació probablement es degui al fet que és necessari incloure un reconeixedor que "tradueixi" els traços de l'usuari (text manuscrit o gestos) a alguna cosa comprensible per l'ordinador, i el resultat d'aquest reconeixement, actualment, és lluny de ser òptim. Per pensar de forma realista en la implantació del pen computer, cal millorar la precisió del reconeixement de text i gestos. L'objectiu d'aquesta tesi és l'estudi de diferents estratègies per millorar aquesta precisió.
En primer lloc, aquesta tesi investiga com aprofitar informació derivada de la interacció per millorar el reconeixement, en concret, en la transcripció interactiva d'imatges amb text manuscrit. En la transcripció interactiva, el sistema i l'usuari treballen "braç a braç" per generar la transcripció. L'usuari valida la sortida del sistema donant certes correccions, que el sistema ha d'usar per millorar la transcripció. En aquesta tesi es proposa utilitzar correccions manuscrites, que el sistema ha de reconèixer primer. La qualitat del reconeixement d'aquesta interacció és millorada, tenint en compte informació contextual, com per exemple, el prefix validat per l'usuari. Després d'això, la tesi se centra en l'estudi del moviment humà
en particular del moviment de les mans, des del punt de vista generatiu, utilitzant la Teoria Cinemàtica i el model Sigma-Lognormal. Entendre com es mouen les mans en escriure és important per al desenvolupament d'un sistema de reconeixement, en particular, per entendre l'origen de la variabilitat de l'escriptura. La contribució d'aquesta tesi a aquest tòpic és important, atès que es presenta una nova tècnica (que millora els resultats previs) per extreure el model Sigma-
Lognormal de traços manuscrits.
De forma molt relacionada amb el treball anterior, s'estudia el benefici d'utilitzar dades sintètiques per a l'entrenament. La forma més fàcil d'entrenar un reconeixedor és proporcionar un conjunt de dades "infinit" que representin totes les possibles variacions. En general, com més dades d'entrenament, menor serà l'error del reconeixedor. No obstant això, moltes vegades no és possible proporcionar més dades, o fer-ho és molt car. Per això, s'ha estudiat com crear i utilitzar dades sintètiques que s'assemblin a les reals.
Les diferents contribucions d'aquesta tesi han obtingut bons resultats, produint diverses publicacions en conferències internacionals i revistes.
Finalment, també s'han explorat tres aplicacions relacionades amb el treball d'aquesta tesi. En primer lloc, s'ha creat Escritorie, un prototip de taula digital basada en el paradigma del pen computer per realitzar transcripció interactiva de documents manuscrits. En segon lloc, s'ha desenvolupat "Gestures à Go Go", una aplicació web per a generar dades sintètiques i empaquetar-les amb un reconeixedor de forma ràpida i senzilla. Finalment, es presenta un altre sistema inter-
actiu sota el paradigma del pen computer. En aquest cas, s'estudia com la revisió de traduccions automàtiques es pot realitzar de forma més ergonòmica. / Martín-Albo Simón, D. (2016). Contributions to Pen & Touch Human-Computer Interaction [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/68482 / TESIS
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Utváření mazacího filmu v poddajném kontaktu / Lubricant film formation in compliant contactJaroš, Tomáš January 2017 (has links)
This diploma thesis deals with the study of film formation in compliant contact. Primary attention is dedicated to the influence of the entrainment speed and slide-to-roll ratio (SRR) on the central film thickness. Based on a research study of the available experimental methods, the fluorescence microscopy was used to achieve the aim of the work. Experiments were realized in ball-on-disk configuration. Firstly, a validation of the method was performed where the solid contact of the ceramic ball and the glass disk was analyzed. Since the measured values were in a good agreement with the theoretical prediction, a ball of NBR rubber material, which is commonly used for production of lip seals and o-rings, was subsequently used. The experimental measurements were performed under pure rolling and rolling/sliding conditions when the entrainment speeds varied in the range from 10 to 400 mm / s. A constant load of 0.2 N was applied. The measured data were then compared to the theoretical predictions for compliant contacts. The results showed that the thickness of the lubricating film gradually increases with increasing entrainment speed, which corresponds to theoretical assumption. Against expectations, evident influence of SRR on the film formation has been observed. In the last part of the thesis the measured data are confronted with previously published studies. Finally, some limitations of this study are discussed and recommendations for further improvement of the used experimental method are suggested.
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Řešení kinematických veličin mechanismu a deformačně-napěťová analýza jeho členů při zablokování / Finding kinematic quantities of a mechanism and a structural analysis of its members after blockageZvozil, Ondrej January 2018 (has links)
Diplomová práca, ktorá vznikla v spolupráci so spoločnosťou AUFEER DESIGN (AFD), sa zaoberá analýzou konkrétneho stieračového mechanizmu automobilu. Najprv je uvedená stručná história stieračov. Stieracie sústavy sú potom rozdelené podľa ich usporiadania a spôsobu pohonu. V nasledujúcej kapitole je formulovaná problémová situácia, problém a systém podstatných veličín. Kinematické veličiny kľúčových bodov mechanizmu sú určené analytickým aj numerickým prístupom. Výpočtový model pre kinematickú analýzu je vyvinutý v Matlabe a SimMechanics. Ďalšia časť je venovaná vytváraniu konečno-prvkového modelu v programe ANSA. Všetky deformačne-napäťové analýzy sú vykonané v programe Abaqus. Prvá z nich je parametrická štúdia, ktorá odhaľuje kritické polohy mechanizmu z hľadiska tlakového namáhania určitých súčastí. Mechanizmus v kritických polohách je potom zaťažovaný so zablokovanými ramenami stieračov. Nakoniec sú urobené lineárne analýzy straty vzpernej stability súčastí, u ktorých môže nastať, nasledované nelineárnymi analýzami so zahrnutými imperfekciami.
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Pokročilá analýza signálů z laboratoře chůze. / Advanced analysis of signals from gait laboratory.Húsková, Michaela January 2019 (has links)
The aim of the thesis is a realization of advanced analysis of signals from gait laboratory. The introductory part deals with the gait cycle and its relation to the joints kinematic is discussed. Additionally, the work is focused on the description of the gait laboratory and the definition of the indexes in order to quantify patient´s overall gait in kinematic analysis. In the practical part, kinematic data analysis was implemented in the MATLAB environment and the results of healthy individuals and patients with cerebral palsy were compared. Kinematic analysis included peak detection in specific kinematic variables. In the last part a graphical user interface for visualization was implemented.
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Elektronická stabilizace podvozku Formule Student / Electronic Stability Control for Formula StudentBařinka, Martin January 2020 (has links)
Goal of this semestral thesis is development of chassis electronic stability control ESP. Thesis analyze kinematic model of chassis, design of dynamic model, which is used for simulation of designed systems. Final system will be used in Formule Student monopost.
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