Dissertations / Theses on the topic 'Linear springs'
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Schjølberg, Martin. "Planned Test of the Prototype 2B Linear Machine with Gas-Springs for Energy Harvesting from Waves." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for elkraftteknikk, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-14766.
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This paper describes a proposed test plan for harvesting energy from waves with a linear machine that uses gas-springs. The linear machine “Prototype 2B” has been put into production and will be finished. The machine has been constructed to withstand 300 bars of gas pressure and the maximum speed of the rotor is set to 10 m/s due to the sealing. The model made in [5] uses the fundamental equations and describes the system behavior of a linear machine with gas springs. The model has been slightly improved and the input specifications for the “Prototype 2B” have been used. The simulations shows that one needs to feed electric energy in some parts of the cycle, but the whole cycle will yield a positive net contribution of electrical energy. The model is not optimized, and hence should be improved due to the time consuming simulations. Steel profiles have been proposed to use for the frame of the test-bench. The first draft of the drawing has been sent to NTNU and the workers have started to build the frame. To ensure the vibration energy to spread itself into the surroundings, isolators need to be selected and adapted. The natural frequency of the test bench with four chosen isolators was calculated to 18,17Hz. The chosen isolators are therefore most likely good enough since the lowest operating frequency of the machine was simulated to 55 Hz.Transferring the energy from the high-force-low-speed source (the wave) to the resonator has been discussed and some suggestions have been proposed. The energy transfer is done by raising pressure in a freestanding actuator with a hose connected to the gas spring. Hence, increasing the actuator pressure will increase the gas spring pressure and the force acting on the rotor will be significantly higher. A procedure to select the correct components are discussed and a Matlab script for analyzing the choice has been made. The high-force-low-speed source has been discussed. Two solutions where a hydraulic system is used have been further investigated, and some calculations and analysis have been performed. Simulations show that one need to apply a maximum force of 24115N at one actuator with a 32mm effective piston area. The regulation of the high-force-low-speed source could be crucial to obtain a good test result since the regulation of the wave must adapt itself to the resonating force of the rotor. The regulation must therefore be investigated further as it can have tremendous impact on the possibility of extracting energy from the machine.The electrical source and regulation control have been discussed. Timing of the electrical energy supplied is crucial and three operational simulations have been performed to investigate when the positive net contribution is at it`s highest. In order to extract the maximum possible net energy from the machine, the right electrical control is very important to implement. Two of the control systems have been proposed, where perhaps the simple proportional controller should be chosen to prove the concept. Later on a more sophisticated electrical controller should be applied since the efficiency of the wave energy converter could increase significantly.The non-linear compression event in the gas-springs is not proportional to the electrical extracted energy. Simulations show that when the pressure increases in the springs one could extract more energy, but the non-linear event could not be recognized. Simulations show that the efficiency of the system varies significantly with the controlling of the machine. If a simple proportional controller is adapted, the theoretical efficiency becomes 2,87% and with a more sophisticated controller one could get 10,02%. This means that there must be done more research on the electrical operating control system if energy harvesting could be profitable.
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Kilic, Mehmet. "Design And Development Of A Mechanically Adjustable Linear Torsion Spring Using Cams." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/3/12610960/index.pdf.
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Linear springs with variable stiffnesses find some key roles in robotic applications. They are implemented into robotic devices for two main reasons, to increase energy efficiency of walking-running robots and prosthesis, and to get safe human-robot interaction at industrial robots. Being inspired from the human actuation system, a mathematical method to get mechanically adjustable linear springs is noted in the literatureantagonistically working two quadratic springs method. But the proposed solution requires two non-linear springs with quadratic spring characteristics and they are not readily available. Several solutions have been noted in the literature for the acquisition of such non-linear springs. At this thesis work, the solution is realized with a string wrapping around cam mechanism. Two different prototypes were designed and constructed and the second one was physically tested to validate the linear spring behavior. The results displayed good linear spring characteristics with different levels of adjustable spring stiffness. Beside the antagonistically working two quadratic springs method, three novel methods to get mechanically adjustable linear springs are introduced at this thesis. They are based on using hanging weights, an exponential characteristic spring and a linear translation spring respectively. The real prototypes were not manufactured but sample designs using string wrapping around cam mechanisms are made.
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Oliveira, Fernando Emerenciano Nunes de. "Controles semiativos e observador de estados não linear aplicados em suspensão veicular com amortecedor magneto-reológico." Universidade Tecnológica Federal do Paraná, 2017. http://repositorio.utfpr.edu.br/jspui/handle/1/2904.
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Comprovadamente, o sistema de suspensão veicular passivo é uma proposta confiável e econômica de solução tanto para redução dos níveis de vibração do chassi e da roda, quanto para a redução dos níveis de aceleração do chassi. Embora este sistema seja amplamente empregado nos veículos, ele apresenta a desvantagem que seus parâmetros não podem ser modificados de acordo com as variações geradas pela pista. Com isso surge o emprego da utilização do sistema de suspensão ativa, que possibilita a variação dos parâmetros da suspensão a tempo real, no entanto, o emprego deste tipo de suspensão requer um elevado nível de energia para o funcionamento correto de seus atuadores, acarretando na inviabilidade de algumas aplicações. Para solucionar as desvantagens encontradas para o sistema de suspensão passivo e ativo, surge o sistema de suspensão semiativo, que reúne as vantagens do sistema ativo, porém com um menor consumo de energia, gerando consequentemente uma opção de controle confiável e econômica de solução para os problemas de dirigibilidade e conforto veicular. O presente trabalho pretende realizar duas avaliações, sendo a primeira, a avaliação e comparação de um sistema de suspensão passivo com o desempenho de quatro controladores semiativos (on/off, skyhook, groundhook e híbrido) e a segunda é testar os mesmos controladores, porém considerando a dinâmica de um amortecedor magnético-reológico através do modelo de LuGre. Estes controladores serão aplicados a um modelo não linear de um quarto de carro com dois graus de liberdade, sendo as suas variáveis estimadas, através de um observador de estados não linear. A análise para a comparação dos sistemas será realizada através de simulações numéricas utilizando o software MatLab®. As simulações dos distúrbios gerados pela pista serão realizadas através de uma função degrau e uma função pulso com o objetivo de avaliar o desempenho de cada controlador. Após a implementação dos algoritmos de controle, foi possível verificar que o sistema de suspensão semiativo, frente às excitações propostas, apresentou um desempenho superior em relação ao conforto. Contudo, não tão significativas quanto ao do conforto, o sistema controlável também, comparativamente ao sistema passivo, apresentou melhoras no requisito dirigibilidade.Proven, the passive vehicle suspension system is a reliable and cost-effective solution solution for both chassis and wheel vibration levels reduction and chassis acceleration levels reduction. Although this system is widely used in vehicles, it has the disadvantage that its parameters can not be modified according to the variations generated by the track. This results in the use of the active suspension system, which allows the variation of the parameters of the suspension in real time, however, the use of this type of suspension requires a high level of energy for the correct operation of its actuators, resulting in the unfeasibility of some applications. To solve the disadvantages found for the passive and active suspension system, the semiactive suspension system arises, which combines the advantages of the active system, but with a lower energy consumption, consequently generating a reliable and economical solution control option to the problems of maneuverability and vehicular comfort. The present work intends to perform two evaluations, the first being the evaluation and comparison of a passive suspension system with the performance of four semi-active controllers (on/off, skyhook, groundhook and hybrid) and the second is to test the same controllers, but considering the dynamics of a magneticrheological damper through the LuGre model. These controllers will be applied to a nonlinear model of a quarter-car with two degrees of freedom, with its variables being estimated through a nonlinear state observer. The analysis for the comparison of the systems will be performed through numerical simulations using MatLab® software. The simulations of the disturbances generated by the track will be performed through a step function and a pulse function in order to evaluate the performance of each controller. After the implementation of the control algorithms, it was possible to verify that the system of semi-active suspension against the proposed excitations presented a superior performance in relation to comfort. However, not as significant as comfort, the controllable system alo compared to the passive system, presented improvements in the steerability requirement.
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Ganzarolli, Francisco. "Influência das frequências de ride no conforto e dirigibilidade veiculares na faixa linear de uso do veículo." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/18/18149/tde-05092012-073800/.
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O tema do conforto na automobilística é bastante extenso e possuidor de muitas interpretações. A ideia central deste trabalho é definir e direcionar alguns métricos para que, durante as fases de conceituação e desenvolvimento de um veículo, seja possível ter um direcional de definição de componentes e atributos veiculares de modo a facilitar o direcionamento dos atributos no programa veicular, e assim atingir suas necessidades. Como exemplo empregado, é empregado um veículo de plataforma tipo B em desenvolvimento por uma montadora, o qual teve as molas de suspensão definidas e rigidezes laterais de eixos com base em material técnico interno equivalente aos estudos apresentados neste trabalho. É adotada uma abordagem inicialmente empírica conforme os primeiros estudos de suspensões independentes realizados neste continente, depois o trabalho é complementado com exigências de normas especificas para vibrações (ISO2361, ISO5008, BS6055) de modo a caracterizar energia vibracional e a interpretação pelo ser humano. Porém como hoje em dia as suspensões automotivas são muito mais complexas, existem componentes específicos para as várias condições de solicitação, deste modo a análise é limitada a situações de ride (conforto) primário e handling (dirigibilidade) em situações de sublimite na faixa linear (cerca de 0,5 g). Como conclusão dos estudos, é possível ter em um veículo atributos de estabilidade sem necessariamente prejudicar o conforto, pois sendo definidos corretamente os componentes elásticos da dinâmica vertical para situações estacionárias e de ride primário, é definido seu equilíbrio estacionário e assim não é necessário comprometimento dos atributos de outros componentes para compensar alguma deficiência existente.The range of assumptions for ride comfort is considered very wide in the automotive world and they can assume lots of possible interpretations. The central idea in this work is define and manage some metrics that, during the concept and development phases of a vehicular program, be possible to follow a better direction for the attributes development and so reach the program targets. As the example in this work, a B platform typical vehicle is used and it is under development in a carmaker, its suspension springs and axle roll stiffness were setup with technical information similar to the ones presented in this work. The initial approach is empiric as occurred with the first independent suspension system studies in this continent and in the sequence, the work is complemented with standards for vibrational issues (ISO2361, ISO5008, BS6055), after this, finally how the vibrational energy is defined and perceived by human beings. The automotive suspensions of current days are very complex and there are lots of specific components to do a specific work, so the analysis are limited to primary ride and sub limit handling (up to 0,5 g). As conclusion, its possible setup a car that is comfortable and stable in the same time, since the elastic components for the vertical dynamics and steady state conditions are correctly set, so its correct balance is reached and no other components attributes are compromised to compensate any deficiency.
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Švrček, Jakub. "Třísítný vibrační třídič." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-416620.
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This diploma thesis deals with the design of an inclined three-sided vibrating screen, which is designed for sorting bulk aggregates. The aim of the diploma thesis is primarily to make a construction design with a specific comparison of various design solutions, considering the calculated operating parameters. In the construction design, is used not only the experience of the manufacturer of this type of machine, but also recommendations based on the manu-facturers of screens component. The design also includes a comparison of two types of flex-ible mounting, which is one of the basic structural units of the entire vibrating screen. The thesis is conceived from the basics, with emphasis on the simplicity and functionality of the device.
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Laing, Kara Louise. "Non-linear deformation of a helical spring." Thesis, University of East Anglia, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.323220.
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Hill, Bradford K. Greene Michael E. "A linear CMOS tunable active resistor." Auburn, Ala, 2008. http://repo.lib.auburn.edu/EtdRoot/2008/SPRING/Electrical_and_Computer_Engineering/Thesis/Hill_Bradford_35.pdf.
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Rubalcaba, Roberto Ramon Johnson Peter D. "Fractional domination, fractional packings, and fractional isomorphisms of graphs." Auburn, Ala., 2005. http://repo.lib.auburn.edu/EtdRoot/2005/SPRING/Mathematics/Dissertation/RUBALCABA_ROBERT_56.pdf.
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Hall, Anthony R. "The Pseudo-Rigid-Body Model for Fast, Accurate, Non-Linear Elasticity." BYU ScholarsArchive, 2013. https://scholarsarchive.byu.edu/etd/3869.
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We introduce to computer graphics the Pseudo-Rigid-Body Mechanism (PRBM) and the chain algorithm from mechanical engineering, with a unified tutorial from disparate source materials. The PRBM has been used successfully to simplify the simulation of non-linearly elastic beams, using deflections of an analogous spring and rigid-body linkage. It offers computational efficiency as well as an automatic parameterization in terms of physically measurable, intuitive inputs which fit naturally into existing animation work flows for character articulation. The chain algorithm is a technique for simulating the deflection of complicated elastic bodies in terms of straight elastic elements, which has recently been extended to incorporate PRBM beam-elements in three dimensions. We present a new, mathematically equivalent optimization of the 3D PRBM chain algorithm, from its former asymptotic complexity of O(n^2) in the number of elements n, to O(n). We also extend an existing PRBM for combined moment-force loads to 3D, where the existing 3D PRBM chain algorithm was limited to 3D PRBM elements for a moment-only load. This optimization and extension are validated by duplicating prior experimental results, but substituting the new optimization and combined-load elements. Finally, a loose road-map is provided with several key considerations for future extension of the techniques to dynamic simulations.
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Evans, Megan Elizabeth. "Determining a Relationship Between Posterior Chain Flexibility and Linear Sprint Speed." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/47430.
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One very common axiom amongst Strength and Conditioning Professionals and Athletic Performance Coaches is that the least flexible athletes usually produce the fastest 40-yard dash times. Flexibility, in this case specifically refers to posterior chain flexibility (PCF). This is usually measured by athletes ability to perform a sit-and-reach test. This train of thought has been widely accepted within the human performance professions, even though it is void of any scientific investigation or measured validity. The purpose of this study is to determine if there is a relationship between posterior chain flexibility using the sit-and-reach test and speed in the 40-yard dash.
All test subjects were male between the ages of 18-22, and members of a Division I university football team. All 95 test subjects had participated in at least one semester of a strength and conditioning program designed by Certified Strength and Conditioning Specialists. Similar of the study done by Johnson (2001), each athlete was placed in a group based on position, line of scrimmage groups (LOS), Skill group (receivers, cornerbacks, rover linebackers, whip linebackers, and safeties), Combo group (inside linebackers, tight ends, quarterbacks, tailbacks, fullbacks, and defensive ends), Specialist group (place- kickers, kick-off specialists, holders, and punters).
Each test subject was tested in the 40-yard dash, the sit-and-reach flexibility test, as well as other tests for strength and power such as the bench press, front squat, push jerk, power clean, vertical jump, and agility tests. Body weight and height was also measured.
This study used a simple linear regression on the data where the Sit-and-Reach test results were the dependent variable and the subjects timed results in a 40 yard dash was the independent variable. There appears to be no significant relationship between a low flexibility score and the sprint speed of an athlete for the entire group population.
The results also show that there is no significant relationship between flexibility of the posterior chain and linear speed as measured in the 40-yard dash when looking at football players that fall under the Combo, Skill, or LOS position groups. There was however a significant relationship for the specialist group. The theory that the least flexible athletes usually produce the fastest 40-yard dash times is not true for those specific groups.Ph. D.
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Guinot, François. "Déploiement régulé de structures spatiales : vers un modèle unidimensionnel de mètre ruban composite." Thesis, Aix-Marseille 1, 2011. http://www.theses.fr/2011AIX10019.
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Dans un contexte où l'utilisation de structures déployables s'est généralisée, le département Recherche de la société Thales Alenia Space étudie un nouveau concept de télescope spatial dont le miroir secondaire est déployé grâce au déroulement de six mètres rubans. Des études antérieures ont permis la mise au point d'un prototype constitué de rubans métalliques dont le déploiement s'est avéré trop violent. Dans ce travail de thèse nous proposons d'une part un nouveau type de ruban à la vitesse de déroulement maîtrisable et d'autre part un modèle original décrivant le comportement dynamique de tels rubans, permettant de mieux appréhender les phénomènes complexes pouvant intervenir lors de scénarios de pliage, de déploiement ou de déroulement. La solution envisagée pour contrôler la vitesse de déroulement repose sur l'exploitation des propriétés mécaniques d'une couche de matériau viscoélastique collée à la surface du ruban. Ces propriétés variant avec la température permettent de garantir un maintien de la position enroulée à froid et assurent un déroulement régulé grâce à un réchauffage localisé. Ces phénomènes ont été mis en évidence expérimentalement et numériquement. La lourdeur des méthodes classiques de modélisation et le manque de richesse des méthodes simplifiées nous ont conduit à développer un modèle de poutre à section fortement déformable permettant de décrire le comportement dynamique des rubans en grands déplacements. Partant d'un modèle de coque, l'originalité de la méthode repose essentiellement sur l'introduction d'une cinématique de type elastica pour décrire les grandes variations de forme de la section. Un modèle énergétique 1D est obtenu en intégrant dans la section et le problème est résolu à l'aide du logiciel de modélisation par éléments finis COMSOL. On propose finalement un modèle continu 1D à 4 paramètres cinématiques qui permet de rendre compte d'une large gamme de phénomènes intervenant dans des scénarios complexes de pliage, de déroulement et de déploiement dynamiqueThe research department of Thales Alenia Space is studying new concepts of space telescopes whose secondary mirror is deployed thanks to the unreeling of six tape-springs. A breadboard using metallic tape-springs has been built during preliminary studies and has exhibited a deployment that is too energetic and induce too important shocks.In this thesis a new kind of tape-spring with a controlled uncoiling speed is introduced. Secondly a rod model with highly deformable thin-walled cross-sections describing the dynamic behaviour of tape-springs is derived.In order to over come the deployment speed of a tape spring, a viscoelastic layer is stuck on its sides. Thanks to its properties varying with the temperature, the viscoelastic layer is used to maintain the tape-spring in a coiled configuration at low temperature whereas a local heating leads to a controlled uncoiling. These phenomenons have been underlined experimentally and numerically.Because of the high complexity of classical shell models and the lack of details of simplified models, smart modelling methods need to be developed to describe the highly non linear behaviour of a tape-spring. A planar rod model with highly deformable thin-walled cross-sections that accounts for large displacements and large rotations in dynamics is proposed. Starting from a classical shellmodel, the main additional assumption consists in introducing an elastica kinematics to describe thelarge changes of the cross-section shape with very few parameters. The expressions of the strain andkinetic energies are derived by performing an analytical integration over the section. The Hamilton principle is directly introduced in a suitable finite element software to solve the problem. Several examples (folding, coiling and deployment of a tape spring) are studied through the FEM software COMSOL to demonstrate the ability of the 4-parameter model to account for several phenomena: creation of a single fold and associated snap-through behaviour, splitting of a fold into two, motion of a fold along the tape during a dynamic deployment, scenarios of coiling and uncoiling of a bistable tape-spring
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Stahlin, Simon. "Non-Linear FE-Analysis of a Composite Action Girder with Coiled Spring Pins as Shear Connectors." Thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-74008.
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For bridges to cope with increased requirements such as increased loads, strengthening work can be carried out. In cases where older steel-concrete bridges do not have a composite action, an alternative is to create composite-action to achieve a higher flexural strength. It is introduced by post-installing shear connectors. There are many different alternatives of shear connectors that can be used, hence a number that can be installed from below the bridge to minimize the impact on the traffic. Coiled Spring Pins are of the interference fit type connector and are put in place from below the bridge by first drilling a hole upward through the upper steel flange and then into the concrete slab. Then, the spiral bolt is pushed up into the drilled hole by means of a hydraulic hammer. Using data from push-out tests and non-linear material models for steel and concrete, a non-linear finite element analysis was created using the commercial finite element software Abaqus. The analysis is based on dimensions and load cases that will mimic a planned full-scale beam test that will be carried out later in 2019. To verify that the material and the model behave in a realistic manner, an analysis was initially performed on a beam without composite-action, and a full-composite action beam with infinitely rigid connectors. These were then compared with hand calculations according to Eurocode. When the material models were verified, it is seen that the materials steel and concrete work for themselves in the analysis without composite-action and together in the analysis with full composite-action. The data for the spiral bolts is than defined instead of infinitely rigid connectors and new analyzes were performed to see the effect of the coiled spring pins properties. The results show that a significant increase in the point load in the middle of the beam can take place before failure occurs after installation of this type of shear connector. Already at a low number of connectors and a low shear connection-ratio, a significant increase in the flexural strength is seen in the beam. By using partial-composite action, with a lower number of spiral bolts, a significant higher flexural strength can be achieved in an economical way.När kraven på att broar ska klara av ökade laster, kan förstärkningsarbeten utföras. I de fall där äldre stål-betongbroar saknar samverkanseffekt, är det ett alternativ att inför samverkan för att uppnå en högre böj-hållfastighet. Det införs genom att man installerar skjuvförbindare i efterhand. Det finns många olika alternativ av skjuvförbindare som kan användas, därav ett antal som går att installera underifrån bron för att minimera påverkan på trafiken. Spiralbultar (Coiled Spring Pins) är av typen presspassnings-förbindare och sätts på plats underifrån bron genom att det först borras ett hål uppåt genom övre stålflänsen och sedan upp i betongplattan. Därefter pressas spiralbulten upp i det borrade hålet med hjälp av en hydraulisk hammare. Med hjälp av data ifrån push-out-tester samt icke-linjära material modeller för stål och betong, skapades en icke-linjär analys i det finita element metods programmet Abaqus. Analysen är uppbyggd med dimensioner och lastfall som ska efterlikna ett planerat full-skaligt balktest som kommer utföras under 2019. För att verifiera att materialet och modellen beter sig realistiskt, utförs en analys på en balk utan samverkan, samt en full-samverkans balk med oändligt styva förbindare. Dessa jämförs sedan med handberäkningar enligt Eurokod. När materialmodellerna var verifierade sågs det att materialen stål och betong arbetar för sig själva i analysen utan samverkan och tillsammans i analysen med full-samverkan. Data för spiralbultarna lades sedan in istället för oändligt styva förbindare och nya analyser utförs för att se påverkan av spiralbultarnas egenskaper. Resultaten visade att en betydande ökning av punklasten i mitten av balken kan ske innan brott uppstår vid installation i efterhand av denna typen skjuvförbindare. Redan vid ett lågt antal förbindare och ett lågt skjuv-förhållande ses en betydande ökning av böj-hållfastigheten i balken. Genom att använda delvis-samverkan med ett lägre antal spiralbultar kan man på ett ekonomiskt sätt uppnå en betydligt högre böj-hållfasthet.
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Miller, James. "Changes in Sprint Kinematics Between Phase Potentiation and Linear PRogressive Models of Resistance Training." Digital Commons @ East Tennessee State University, 2017. https://dc.etsu.edu/etd/3309.
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Fifteen well-trained males, mid-thigh pull peak force (IPF 4403.61 ± 664.69N) and isometric peak force allometrically scaled (IPFa 226.04 ± 25.81) were assigned to two groups: repetition maximum training (RM) and relative intensity training (RI) for a twelve-week training intervention. The main effect of time showed a statistically significant difference in mean sprint performance and IPFa at the different time points (p < 0.001). There was a larger magnitude of within-subject effect with respect to sprint performance pre – post with the RI group (ES = 1.06, 7.19%) as compared to the RM group (ES = 0.567, 4.23%, p < 0.001), as well as a larger magnitude of within-subject effect with respect to IPFa pre – post with the RI group (ES = 0.426, 7.51%) as compared to the RM group (ES = 0.270, 13.29%). Furthermore, there was a non-statistically significant, moderate between-group difference in the change in IPFa from pre-post in favor of the RI group (ES=.75), and a large between-group difference in the change in sprint performance pre-post in favor of the RI group (ES=1.50). Results lead investigators to suggest the utilization of RI training tactics for the development of sprint performance when minimal sprint skill training is available.
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Nigrowsky, Pierre. "Variable structure control of robot manipulators (the example of the SPRINTA)." Thesis, Brunel University, 2000. http://bura.brunel.ac.uk/handle/2438/4827.
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The subject of this thesis is the design and practical application of a model-based controller with variable structure control (VSC). Robot manipulators are highly non-linear systems, however they form a specific class in the non-linear group. Exact mathematical descriptions of the robot dynamics can be achieved and further, robot manipulators have specific useful properties that can be used for the design of advanced controllers. The inclusion of the inverse dynamic description of the robot manipulator as a feedforward term of the controller (model-based controller) is used to transform two non-linear systems i.e. the controller and the robot, into one linear system. The limitation of this technique arises from the accuracy of the inverse dynamic model. The linearisation only takes place if the model is known exactly. To deal with the uncertainties that arise in the model, a control methodology based on variable structure control is proposed. The design of the controller is based on a Lyapunov approach and engineering considerations of the robot. A candidate Lyapunov function of a pseudo-energy form is selected to start the controller design. The general form of the controller is selected to satisfy the negative definiteness of the Lyapunov function. The initial uncertainties between the actual robot dynamics and the model used in the controller are dealt with using a classical VSC regulator. The deficiencies of this approach are evident however because of the chattering phenomenum. The model uncertainties are examined from an engineering point of view and adjustable bounds are then devised for the VSC regulator, and simulations confirm a reduction in the chattering. Implementation on the SPRINTA robot reveals further limitations in the proposed methodology and the bound adjustment is enhanced to take into account the position of the robot and the tracking errors. Two controllers based on the same principle are then obtained and their performances are compared to a PID controller, for three types of trajectory. Tests reveal the superiority of the devised control methodology over the classic PID controller. The devised controller demonstrates that the inclusion of the robot dynamics and properties in the controller design with adequate engineering considerations lead to improved robot responses.
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Hedrich, Philipp, Maik Johe, and Peter F. Pelz. "Design and Realization of an Adjustable Fluid Powered Piston for an Active Air Spring." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-199924.
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In this paper, we present a new compact hydraulic linear actuator. The concept is developed to change the rolling piston diameter of an active air spring during usage. By doing so, the air spring can actively apply pressure and tension forces. The actuator is designed for small movements at high forces. It is insensitive to side forces, which are introduced by the bellows rolling on the rolling piston of the air spring. A diaphragm sealing is used to minimize friction. Hence a precise adjustment of small displacements at high dynamics is possible and the system is completely leakage-free. We describe the design and development of this actuator and show first measurement results from preliminary tests to show its functionality.
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Springer, Phillip [Verfasser], and Stephan W. [Akademischer Betreuer] Koch. "Linear and Nonlinear Optical Properties of Germanium and Dilute Nitride Containing Semiconductors / Phillip Springer. Betreuer: Stephan W. Koch." Marburg : Philipps-Universität Marburg, 2016. http://d-nb.info/1103658204/34.
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Aschenbrenner, Anna-Katharina [Verfasser], and Otmar [Akademischer Betreuer] Spring. "Die linearen Drüsenhaare der Sonnenblume : Morphologie, Verbreitung, Metabolitprofil und Sesquiterpenbiosynthese / Anna-Katharina Aschenbrenner. Betreuer: Otmar Spring." Hohenheim : Kommunikations-, Informations- und Medienzentrum der Universität Hohenheim, 2014. http://d-nb.info/1063014735/34.
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McCabe, Carla. "Effects of 50m and 400m race paces on three-dimensional kinematics and linear kinetics of sprint and distance front crawl swimmers." Thesis, University of Edinburgh, 2008. http://hdl.handle.net/1842/3300.
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Many authors have proposed that sprint and distance front crawl swimmers differ in their stroke characteristics, however little three-dimensional quantitative data is provided to support these assumptions. It is currently unknown whether sprint and distance swimmers exhibit distinct stroke characteristics when swimming at the same pace. There were two main purposes of this study: 1) to determine whether there are distinct kinematic and kinetic differences between sprint and distance front crawl swimmers, and 2) to investigate whether stroke characteristics of front crawl swimmers, in terms of kinematic and kinetic variables change with swimming speed. Fifteen male national/international front crawl swimmers (17.87 +/- 2.33yrs; 73.87 +/- 8.72kg; 183.02 +/- 6.84cm) volunteered to participate in this study. This sample was composed of seven sprint (SG) and eight distance (DG) swimmers. Each testing session required swimmers to perform four 25m sprints and one 400m max effort (front crawl), with no pacing strategy, in a randomised order. Each trial was performed through a 6.75m3 calibrated space and recorded by six gen-locked JVC KY32 CCD cameras (4 below and 2 above water) sampling at a frequency of 50 fields per second. All trials were processed using ‘APAS’ software to obtain 3D coordinate data. Anthropometric measures were quantified using the elliptical zone method. Both data sets were entered into a bespoke MATLAB program which output: average swim velocity (Vav), stroke length (SL), stroke frequency (SF), stroke index (SI), vertical and lateral displacement for each segment, shoulder and hip roll angle, and elbow joint angle variables (1st back, shoulder x, end back, hand exit and recovery elbow angle). Stroke phase (entry, pull, push and recovery) durations (%) were quantified at instants corresponding to percentiles of the stroke cycle. Centre of mass position data were obtained from the digitised 3D data using a 14 segment rigid link body model in conjunction with the body segment parameter data obtained by the elliptical zone method. Component whole body velocity (VCOMHor), acceleration (accCOM) and net force (forceCOM) were derived from the centre of mass position data. Variables were statistically analysed in SPSS v.14.0, using a General Linear Model, repeated measures analysis of variance. The results indicated that the groups differed (p<0.05) with respect to the duration of the pull phase, the occurrence of max left and right shoulder roll and the temporal sequencing of the shoulders and hips rolling at both sprint and distance pace. Other variables approached significance between the groups, particularly when distance swimming, such as the duration of the push phase (p=0.082), the Vav (p=0.071) and average VCOMHor (p=0.071). The stroke kinematic variables that changed between paces (p<0.05) were the duration of the entry, pull, push, hand exit and recovery phases; the elbow angle at the end back position and the push phase range; total shoulder and hip roll; the sum average vertical displacement of the foot; the time to max vertical and lateral displacement of the finger; the time at max right elbow extension; the average VCOMHor, Min VCOMHor and Max VCOMHor. The stroke kinetic variables that changed between paces (p<0.05) were the Min accCOM, Max accCOM, range of accCOM, min forceCOM and max forceCOM. Other variables approached significance between the paces such as the entry elbow angle (p=0.084), the max right elbow extension (p=0.056), the finger lateral range (p=0.067) and the time to max accCOM (p=0.079). The SG displayed shorter durations of the pull and push phases than the DG for both paces, which was linked to the faster horizontal velocity and/or vertical acceleration of the hand. The sequencing order of the shoulders and hips changed between groups and paces, which was speculated to be controlled by the magnitude of the leg-kick. The main changes between paces were the greater magnitude of elbow angle at both the end back position and the push phase range, which contributed to the adjustment of kinetic variables. SL, SF, SI, Vav and the duration of the all the stroke phases changed between sprint and distance pace in order to meet the physiological requirements of the race distance. The prolonged duration of the entry phase, when distance swimming, resulted in a delayed attainment of the catch position and maximum stroke depth. Moreover, the magnitude of shoulder and hip roll increased at distance compared to sprint pace, which in turn influenced the magnitude of average vertical and range of lateral displacement of the finger between paces. In conclusion, contrary to the literature, SG and DG differed only with respect to the duration of the pull and push stroke phases and the sequencing order of the shoulders and hips. All swimmers adjust the majority of kinematic and kinetic variables depending on the swim pace in order to optimise performance for that race distance.
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稲垣, 瑞穂, Mizuho INAGAKI, 幸男 石田, Yukio ISHIDA, 晃正 林, and Akimasa HAYASHI. "クリアランス内で衝突を伴うロータの非線形強制振動と自励振動 (非線形ばね・減衰モデルによる分数調波振動の解析)." 日本機械学会, 2005. http://hdl.handle.net/2237/9040.
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Štafa, Michal. "Trojrozměrné pružinové sítě a jejich aplikace." Doctoral thesis, Vysoké učení technické v Brně. Fakulta stavební, 2017. http://www.nusl.cz/ntk/nusl-355601.
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The presented work highlights the remarkable potential of physical discretization – lattice model FyDiK in three-dimensional modelling of non-linear problems in structural mechanics. To achieve the objectives a software application, that implements the model FyDiK along with the 3D graphical user interface has been developed and thus is able to assemble a spring network model. Such a model was used for modelling the formation of cracks and fracture in the concrete specimens and also to model a plastic behaviour of steel I-beam. The calculations were performed by a massive parallelization on CUDA platform. In the first part the basic principles on which the work is based are introduced. Subsequently, a detailed description of individual parts of the model and the issue of parallelization by graphics cards are presented. In the next part the creation of the required software and improving of the model properties of mentioned materials are described. That is followed by evaluation of the achieved results with the comparison of other modelling software. The conclusion summarizes the achievements and suggestions for the further development possibilities of the presented method of modelling.
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Hegana, Ashenafi B. "Low Temperature Waste Energy Harvesting by Shape Memory Alloy Actuator." University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1461631046.
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Mackura, Mark. "Nano-confinement Effects of Crystalline Walls on the Glass Transition of a Model Polymer." University of Akron / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1366815752.
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Kenfack, Pierre. "La conception, l'étude théorique et expérimentale, d'une génératrice électrique linéaire à structure polyentrefer à lamesguidées ou frottantes." Thesis, Montpellier, 2018. http://www.theses.fr/2018MONTS006/document.
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La génératrice électrique linéaire est destinée à être accouplée à une machine thermique (thermoacoustique) pour la conception d'un groupe électrogène à source de chaleur externe (Récupération de la chaleur d'une machine thermique). Cette thèse porte sur l'adaptation au fonctionnement en génératrice, plus précisément au fonctionnement en régime permanent à facteur de marche unitaire. Une attention toute particulière est portée aux aspects tribologiques liés au guidage des lames constituants les parties fixes et mobiles de la structure électromagnétique. Une revue de littérature est présentée avant de passer à une discussion théorique sur les notions fondamentales relatives au calcul électromagnétique. Les paramètres du circuit équivalent en régime permanent et le rendement de la génératrice sont calculés à partir des caractéristiques dimensionnelles et structurales de la génératrice. La conception et les performances en régime permanent de la génératrice sont validées par la méthode par éléments finis. Le modèle numérique est intégré dans un processus d’optimisation multi-objets par un ensemble des meilleurs compromis facilitant le choix de dimensionnement de la génératrice et une solution à plus haut rendement est retenue comme concept final. La validation par la méthode des éléments finis est faite avec ANSYS. La validité est vérifiée par une bonne concordance entre les résultats expérimentaux et numérique.Le principal problème rencontré dans la conception des génératrices électriques linéaires à structure polyentrefer à lames guidées ou frottantes est dans le contrôle des jeux mécaniques nécessaires pour permettre le déplacement permanent des parties mobiles. Ce problème est très difficile à contrôler en raison de l'entrefer magnétique qui doit être aussi faible que possible pour éviter de pénaliser la pression magnétique tangentielle. Les pièces mobiles sont de faible épaisseur dans la structure polyentrefer, donc moins rigide. Les lames mobiles, par conséquent, ont tendance à frotter contre les parties fixes. Le triboguidage participe à la résolution de ce problème. La tribologie est l'étude du frottement et de la lubrification appliquée aux problèmes d'usure. Son objectif est d'atténuer l'usure et le frottement dans le but d'améliorer les performances de la génératrice électrique linéaire à structure polyentrefer à lames guidées ou frottantes. Le dispositif qui permet de compenser, voire d’annuler les efforts de friction qui apparaissent entre les deux stators fixes et la lame mobile en translation a été conçu et réalisé. Ce dispositif de compensation est un système de vis de pression agissant sur les ressorts. Le principe est de reprendre exactement la force d’attraction entre la partie mobile et les stators grâce à une force d’écartement réglable (action sur un ensemble de vis de pression sur des ressorts) entre les statorsThe linear electric generator is intended to be coupled to a thermal (thermoacoustic) machine for the design of a generator set with external heat source (heat recovery of a thermal machine). This thesis deals with the adaptation to generator operation, more precisely to steady-state operation with a unit power factor. Special attention is paid to tribological aspects related to guiding the fixed and moving parts of the electromagnetic structure.A literature review is presented before moving on to a theoretical discussion on the fundamental concepts relating to electromagnetic computation. Equivalent steady-state circuit parameters and generator efficiency are calculated from the dimensional and structural characteristics of the generator. The design and steady-state performance of the generator are validated by the finite element method. The numerical computation is integrated into a multi-object optimization process by a set of the best compromises facilitating the choice of generator sizing and a high efficiency solution is retained as the final concept. Validation by the finite element method employed in ANSYS is done. Validity is verified by a good match between the experimental and numerical results.The main problem encountered in the design of linear electric generators multi air-gap structure guided or sliding plates is in the control of the mechanical clearance necessary to allow the permanent displacement of moving parts. This problem is very difficult to control because the magnetic air-gap must be as small as possible to avoid penalising the tangential magnetic pressure. The moving parts are of low thickness in the multi air-gap structure, therefore less rigid. The moving plates, therefore, tend to rub against the fixed parts. The triboguiding helps solve this problem. The tribology is the study of friction and lubrication applied to wear problems. Its objective is to reduce wear and friction in order to improve the performance of linear electric generator multi air-gap structure guided or sliding plates.The device has been designed and implemented to compensate or even cancel the friction forces that appear between the two fixed stators and the moving plate in translation. This device is a system to compensate for reaction force based on pressure screws acting on springs. The principle is to return the exact force of attraction between the mover and the stators thanks to an adjustable spacing force (the action of a set of pressure screws on springs) between the stators
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Fléchon, Elsa. "Définition d'un modèle unifié pour la simulation physique adaptative avec changements topologiques." Thesis, Lyon 1, 2014. http://www.theses.fr/2014LYO10284/document.
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Les travaux réalisés pendant mon doctorat répondent à la problématique de la simulation physique, en temps interactif, du comportement d'objets déformables soumis à des changements topologiques. Mes travaux ont abouti à la définition d'un nouveau modèle unifié couplant un modèle topologique complet et un modèle physique, pour la simulation physique d'objets déformables décomposés en éléments surfaciques comme volumiques, tout en réalisant pendant cette simulation des changements topologiques comme la découpe ou la subdivision locale d'un élément du maillage. Cette dernière opération a permis de proposer une méthode adaptative où les éléments du maillage sont raffinés selon un critère géométrique au cours de la simulation. Nous avons fait le choix des cartes combinatoires et plus particulièrement celui des complexes cellulaires linéaires, comme modèle topologique de notre modèle unifié. Ils ont l'avantage d'être génériques par rapport à la dimension de l'objet représenté mais également par rapport à la topologie des cellules en lesquelles l'objet est décomposé. Le système masses-ressort a, quant à lui, été choisi comme modèle physique de notre modèle unifié. L'avantage de ce dernier réside dans la simplicité de ses équations, son implémentation intuitive, son interactivité et sa facilité à gérer les changements topologiques. Enfin, la définition d'un modèle unifié nous a permis de proposer un modèle évitant la redondance d'informations et facilitant la mise à jour de ces dernières suite à des changements topologiquesThe work made during my PhD, respond to the problematic of physical simulation of the behavior of deformable objects subject to topological changes in interactive time. My work resulted in the definition of a new unified model coupling a complete topological model and a physical model for physical simulation of deformable objects decomposed in surface as volume elements, while performing during this simulation topological changes such as cutting or subdivision local of a mesh element. This operation allowed us to propose an adaptive method where mesh elements are refined during the simulation according to a geometric criterion. For the topological model of our unified model, we made the choice of combinatorial maps and more particularly linear cellular complexes. Their main advantage of the latter is the simplicity of its equations, its intuitive implementation, its interactivity and its ease to handle topological changes. Finally, the definition of a unified model allowed us to propose a model avoiding duplication of information and facilitate the update after topological changes
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Silva, Fabiano Leite da. "Metrópole corporativa e fragmentada: a urbanização da Península do Ribeirão Cocaia - Grajaú em São Paulo." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/8/8136/tde-02122016-131109/.
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O presente trabalho tem por objetivo discutir e problematizar a ocupação de uma área de manancial inserida na Zona Sul da cidade de São Paulo, a Península do Ribeirão Cocaia. Para a discussão desse processo, trabalhou-se com a relação entre diferentes escalas, associando processos mais gerais da metropolização da cidade de São Paulo e a constituição da metrópole corporativa e mostrando como isso refletiu de forma decisiva nesse importante lugar da cidade, que havia sido, em um determinado momento, concebido como um importante espaço estratégico de conservação dos recursos hídricos, mas que veio a se transformar em um espaço principalmente de moradia de trabalhadores de baixa renda. Em que pesem as transformações recentes com a melhoria de alguns bairros na Península do Ribeirão Cocaia, ainda existem áreas de grande precariedade nessa região. Dessa maneira, realizou-se um recorte espacial de três bairros que constituem a Península: o Grajaú, no período da instalação da Cohab Bororé, nos anos 1970; o Parque Residencial Cocaia, com base em loteamentos clandestinos nos anos 1980; e o Cantinho do Céu, com a intensificação da ocupação a partir dos anos 1990. Este trabalho problematiza a questão do uso e da ocupação de áreas de mananciais, refletindo como se deu esse processo e o que tem sido feito até agora, procurando chamar a atenção das autoridades e da população para esse fato tão preocupante.This paper discuss the occupation of a watershed area that is inserted in the South Zone of São Paulo, Ribeirão Cocaia Peninsula. To discuss this process sought to work with the relation between different scales, relating more general process of expansion of the city of São Paulo, and the establishment of corporate metropolis and how it reflected in this important area of the city, which had been considered as an important strategic area of conservation of water resources and that turned into a mostly housing low-income workers. Despite the recent changes with the improvement of parts of some neighborhoods in Ribeirão Cocaia peninsula, there are still areas of great precariousness in this space of the city. In this way we tried to make a spatial area three districts that make up the Peninsula: The Grajaú, during the installation of Cohab Bororé in the 70s; the Cocaia Residential Park, based in illegal settlements in the 1980s, and the Corner of Heaven, where the occupancy gains strength in the 1990s. This paper discusses the question of the use and occupation of watershed areas, reflecting on how this process took place, and what has been done so far, trying to draw attention to this issue.
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Singh, Subrat, and Shreedhara Sreehari Veditherakal. "CAE modelling of cast aluminium in automotive structures." Thesis, Linköpings universitet, Mekanik och hållfasthetslära, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-162190.
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In the automobile industry, there is a big push for the automotive car manufacturers to base engineering decisions on the results of Computer Aided Engineering (CAE) solutions, and to transform the prototyping and testing, from a costly iterative process to a final verification and validation step. The variability in components material properties and environmental conditions together with the lack of knowledge about the underlying physics of complex systems often make it impractical to make reliable predictions based on only deterministic CAE models. One such area is the CAE modelling of cast aluminium components. These cast aluminium components have gained a huge relevance in the automobile industries due to their commendable mechanical properties. The advantage of the cast aluminium alloys are being a well-established alloy system in manufacturing processes, their functional integrity and relatively low weight. However, the presence of pores and micro-voids obtained during the manufacturing process constitutes a specific material behaviour and establishes a challenge in modelling of the cast materials. Furthermore, the low ductility of the materialdemands for the advanced numerical model to predict the failure. The main focus of this master thesis work is to investigate modelling technique of a cast aluminium alloy component, a spring tower, for a drop tower test and validate the predicted behaviour with the physical test results. Volvo Car Corporation currently uses a material model provided by MATFEM for cast aluminium parts which are explored in this thesis work, to validate the material model for component level testing. The methodology used to achieve this objective was to develop a boundary condition to perform component level tests in the drop tower and to correlate these with the obtained results found by using various modelling techniques in the explicit solver LS-DYNA. Therefore, precise and realistic modelling of the drop tower is crucial because the simulation results can be influenced by major design changes. A detailed finite element model for the spring tower has been developed from the observations made during the physical testing. The refined model showed good agreement with the existing model for the spring tower and observations from physical tests.
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Dureau, Maxime. "Characterization and simulation of the mechanical forces that control the process of Dorsal Closure during Drosophila melanogaster embryogenesis." Thesis, Lyon, École normale supérieure, 2015. http://www.theses.fr/2015ENSL0999/document.
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Le travail de thèse présenté ici vise à caractériser et simuler les forces mécaniques impliquées dans le processus de fermeture dorsale chez l’organisme Drosophila melanogaster. Ce processus participe à l’acquisition par l’embryon de sa forme finale. Ainsi, l’objectif du travail présenté ici est d’approfondir nos connaissances sur la mécanique des tissus,ainsi que sur leur rôle dans l’embryogenèse.La fermeture dorsale est un processus similaire à la cicatrisation, dans lequel la fermeture du trou dorsal est réalisée par l'amnioséreuse, qui couvre le trou dorsal, et la rangée la plus dorsale des cellules de l'épiderme: les leading edge cells.Une partie du travail présenté ici étudie aussi les mouvements des cellules du leading edge,dans le but de comprendre l’effet du câble d’actine sur la dynamique de la fermeture dorsale.Un algorithme permettant de détecter les contours des cellules, leur position ainsi que celle de leurs jonctions multiples a été développé, ainsi qu'un interface utilisateur.Différents modèles dynamiques ont ensuite été construits, prenant en compte différents comportements mécaniques, selon l’approche lagrangienne. Les systèmes d’équations ont été résolus numériquement, et leurs prédictions comparées aux données biologiques selon l’approche des moindres carrés. Les résultats ont été validés par le test de la fonction d’auto corrélation.Les résultats présentés dans cette thèse nous permettent de mieux comprendre les processus mécaniques impliqués dans les oscillations des cellules de l’amnioséreuse. Ils nous donnent aussi des indices sur leurs caractéristiques biologiques. Ils nous permettent enfin de mieux appréhender le rôle du cabled’actine dans ce processusThe work presented here aims at characterizing and simulating the mechanical forces involved in the process of Dorsal Closure in the organism Drosophila melanogaster, an embryonic process. In particular, Dorsal Closure participates in the acquisition of the final form of the embryo. Therefore, the work presented here aims at fathoming our knowledge on tissues mechanics, as well as their role in the acquisition of shape. The tissues involved in Dorsal Closure are the epidermis and the amnioserosa. At this stage of development, the epidermis surrounds almost all the embryo. Nevertheless, the amnioserosa still covers a large area of the dorsal side called dorsal hole. Hence, Dorsal Closure aims at shutting this hole and joining the lateral sides of the epidermis, in a process similar to wound healing. In order to fuse the two sides of the epidermis on the dorsal line, the epidermis must be drawn dorsalward. This movement is driven by the amnioserosa on the one hand, and by the dorsalmost row of the epidermis (called Leading Edge cells) on the other hand. The latter first form a transcellular Actin Cable around the dorsal hole. The cable, contracting, will reduce the area of the dorsal hole, covered by the amnioserosa. Second, the Leading Edge cells emit protrusions that will attach to the opposite Leading Edge and drag it toward themselves, untill the two sides of the epidermis fuse. These protrusions have a limited range, hence the dragging and fusion only take place at the ends of the dorsal hole (called canthi), where the distance between the two Leading Edges is small enough. The Amnioserosa also drags the epidermis toward the dorsal line. Its cells produce a contractile network. Interstingly, Amnioserosa cells see the area of their top side (apical side) vary in a periodic way. Although these variations have been widely studied, their role in Dorsal Closure remains unknown. This PhD aims at improving our knowledge of the mechanical concepts involved in these oscillations, and to build a physical model representing these movements. The work presented here also studies the movements of the Leading Edge cells, in order to understand the effect of the Actin Cableon the dynamics of Dorsal Closure. In order to study the cells movements and the role of the tissues involved in Dorsal Closure, an algorithm was developped, allowing to detect the cells edges, their position, as well as those of their vertices (multiple junction between three or four cells) and to track them over time. A user interface was also developped, in order to facilitate the adjustment of the parameters allowing the detection, as well as the correction of possible errors. Various dynamical models were then built following the lagrangian approach. The systems of equations deriving from the Euler-Lagrange equations were numerically solved, and their predictions compared to the biological data extracted thanks to the algorithm presented earlier, following the least square approach. The model validation was performed thanks to the autocorrelation function test. Finally, the Leading Edge dynamics was studied characterising the cellular movements at the interface between the epidermis and the amnioserosa. Wild type embryos dynamics were compared to those of mutated embryos showing specific defects in the Actin Cable formation. The results presented in this manuscript allow a better understanding of the processes involved in in Amnioserosa cells oscicllations. They also give clues on their biological characteristics. Finally, they assess the role of the actin cable in this process similar to wound healing
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喜弘, 山梶, and Yoshihiro Yamakaji. "車両駆動系トーショナルダンパにおける非線形振動に関する研究." Thesis, https://doors.doshisha.ac.jp/opac/opac_link/bibid/BB13158482/?lang=0, 2021. https://doors.doshisha.ac.jp/opac/opac_link/bibid/BB13158482/?lang=0.
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年々増大するエンジントルク変動を低減するために広角トーショナルダンパの適用例が増してきているが，それらに起因する非線形振動のメカニズムや振動低減のための研究例は少ない．本論文の目的は，これらに関する非線形振動の解明および改善，および精度と計算コストを両立するモデルの開発である．そのため，実験検証に基づくモデルを開発し，非線形振動を大幅に削減する手法を検討した．さらに，計算コストを増加させることなく解析精度を改善する不等ピッチ離散化モデル化手法を検討した．博士(工学)
Doctor of Philosophy in Engineering
同志社大学
Doshisha University
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Cgu, Cheng-Chung, and 朱政仲. "Toward the Constant-Torque Linkage-Type Mechanisms Using Linear Springs." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/64082568982689815327.
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碩士國立臺灣科技大學
機械工程系
105
This study explores the design possibility of a spring-type rigid-link mechanism that produces a constant torque. The mechanism we aim to devise should have rigid links and a spring only without the use of flexible rods and cams. In this thesis, we firstly reviewed the development of the torsional mechanisms. We then put forward two possible mechanism concepts to output constant-torque, and use these two concepts to design three nearly constant-torque mechanisms. Then we analyzed the output torque of each mechanism, and then use Matlab and Adams software to verify the design results. Finally, we chose the most feasible design, performing its geometrical optimization. The design result shows that the average fluctuation of the output torque is only 5.67% during 60 degrees to 110 degrees of the crank motion.
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CHEN, XIAOMIN, and 陳曉敏. "Development and Verification of the Normal and Tangential Equivalent Linear Contact Springs of Egg Shape Particles." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/799hnj.
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碩士國立中央大學
土木工程學系
102
In this thesis, equivalent linear contact spring constants are developed for the contact between deformable particles such as spherical particles and egg-shaped particles, based on the Hertz contact theory and Mindlin contact theory of tangential stiffness. The physical significance of this study is that we can adopt an equivalent linear spring stiffness to model the non-linear contact behavior of Hertz’s contact; It’s shown that the theory normal equivalent linear contact spring stiffness is related to the initial relative velocity of the two contact particles, elastic constant and geometry of contact area; tangential stiffness is related to the normal mutual approach distance of the two particles and elastic constant. The newly developed egg-shaped particles are designed by the revolution of an ellipse, formed by four connected arcs, about the major axis passing through its centroid. Surface of egg-shaped particles can be divided into two spherical surfaces and a curved surface. Mainly contact can be divided into spherical surface contact and curved surface contact. The surface of egg-shaped particles belongs to rotating surface, so that we can quickly determine the principal radius of curvatures in the two contacted curves. Numerical simulations for granular assemblies used equivalent linear contact spring stiffness, simulate the behavior of direct impact and oblique impact and compare the result with theoretical solution.
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Ni, Yen-Yih. "A linear programming approach to the analysis, design and failure prediction of layered springs with frictional contacts." 1996. http://catalog.hathitrust.org/api/volumes/oclc/36488108.html.
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Thesis (Ph. D.)--University of Wisconsin--Madison, 1996.Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 139-145).
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(7847843), Rahul Deshmukh. "Influence of geometry and placement configuration on side forces in compression springs." Thesis, 2019.
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A leading cause of premature failure and excessive wear and tear in mechanical components that rely on compression springs for their operation is the development of unwanted side forces when the spring is compressed.
These side forces are usually around 10% - 20% of the magnitude of the axial load and point in different directions in the plane perpendicular to the axis of the spring.
The magnitude and direction of the resultant of side forces varies very non-linearly and unpredictably even though the axial force behavior of the spring is very consistent and predictable.
Since these side forces have to be resisted by the housing components that hold the spring in place, it is difficult to design these components for optimal operation.
The hypothesis of this study is that side forces are highly sensitive to small changes in spring geometry and its placement configuration in the housing.
Several experiments are conducted to measure the axial and side forces in barrel springs and two different types of finite element models are developed and calibrated to model the spring behavior.
Spring geometry and placement are parameterized using several control variables and an approach based on design of experiments is used to identify the critical parameters that control the behavior of side-forces.
The models resulted in deeper insight into the development of side forces as the spring is progressively loaded and how its contact interactions with the housing lead to changes in the side force.
It was found that side-forces are indeed sensitive to variations in spring geometry and placement.
These sensitivities are quantified to enable designers to and manufacturers of such springs to gain more control of side force variations between different spring specimens.
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Ho, Chi-Hwa, and 何其驊. "Development and Research of Flat-Circular Spring Linear Guiding System." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/51741485486285968515.
Full textAbstract:
碩士國立臺灣大學
機械工程學系
85
The aim of the research is to develop a kind of spring linear guiding system named flat-circular spring linear guiding system, which bases on curved foil. The flat-circular spring linear guiding system, as other ordinary spring linear guiding system, has spectaculars as followed: 1.no coulomb friction force 2.no abrasion between parts of composition 3.simple structure 4.low requirement to operating environment 5.smooth guiding movement. Besides, it has larger stroke than ordinary spring linear guiding system and adjustable restoring force. The mechanical properties of the flat-circular guiding system and guiding errors under different operating circumstances are estimated by using finite element analysis. According these results, the criteria of design to different application restriction can be concluded.
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Hsu, Chin-Long, and 許金隆. "The Development and Performance Research of Electrostatic Flat- Circular Spring Linear Actuator." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/52732441204006536125.
Full textAbstract:
碩士國立臺灣大學
機械工程學系
85
The objection of this research is to develop an electrostatic driving linear actuator, and to discuss the property of electrostatic driving force. In the theoretical analysis, the changes of shape and maximum stress of the flat- circular spring that is loaded by the side force are analyzed by the finite element method. According to the shape, the electrostatic driving force of spring is calculated. By the process of the design method, the entire actuator systems are developed, analyzed, and chosen to be proceed the deeper research. The solutions of the subsystem are developed by the conceptual design, and elected by the experiment or evaluation. After the prototype is designed, manufactured and tested, the performance of the actuator is realized, and the factors are revealed that affect the motion of actuator. From the result of experiment and the analysis of theory, the movement modal of actuator is constructed. Three major subsystems are flat- circular spring with guiding function, driven move part, and the component that generates electrostatic force.
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Xu, Jin-Long, and 許金隆. "The Development and Performance Research of Electrostatic Flat- Circular Spring Linear Actuator." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/65327217592123156707.
Full text
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Min-YenTsai and 蔡旻諺. "Verification of Equivalent linear spring on the Experiment of the Scoured Piled Bridge." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/f42268.
Full textAbstract:
碩士國立成功大學
土木工程學系
106
In Taiwan, there are many bridges that were destroyed by the nature disasters every year. Although the civil engineers did the best on designing the bridges, the nature disasters would decrease the seismic capacity of the bridges. The survey of the collapsed bridge pointed out that the scoured depths increased by the hydraulic and the seismic capacity decreased. In this study mainly discusses the structural behavior of the composite structure, ie, the structural behavior of the foundation exposed to erosion and exposed to seismic loads. In the study, the equivalent linear soil springs proposed by previous researchers ,the American Petroleum Institute（API） and Japanese Road Association（JRA） soil spring were used respectively. This study used different soil springs to analyze the vibration behavior of shaking table experiments after bare pile erosion, and compare with the existing single and group pile foundation experiments. The discussion and comparison of the applicability of the soil springs on exposed structure shows that the response of the experiment can be more effectively simulated by using the equivalent linear spring model. The most important is that the model using equivalent linear spring under near-fault earthquakes completely simulate the behavior of the structure after the shock.
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Getting, Roger Llewellyn. "Response of linear prairie remnants to seven years of annual spring burning evaluated in terms of guilds." 2003. http://catalog.hathitrust.org/api/volumes/oclc/51766676.html.
Full textAbstract:
Thesis (M.S.)--University of Wisconsin--Madison, 2003.Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 95-102).
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HU, CHUN-MING, and 胡俊明. "Study of Nonlinearity Effect from the Fixed Boundary of Leaf Spring on the Linear Piezoelectric Vibratory Conveyor." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/3g2845.
Full textAbstract:
碩士國立臺北科技大學
機械工程系機電整合碩士班
107
Vibratory conveyor is an indispensable equipment in the process of automated manufacturing assembly. The resonance of the machine is likely to loosen the structure or reduce the structural stability. This study mainly discusses the fixed boundary of a linear vibratory conveyor. The nonlinear phenomenon generated by the stage motion is obtained by adjusting the tightening torque of the screw on fixed end to obtain the relationship between the stiffness of the fixed boundary and the natural frequency of the structure. If the leaf spring is installed on the base with the same tightening torque, it is found that the greater the rigidity of the leaf spring itself, the greater the nonlinear phenomenon emerges. In other words, if the bonding strength of the fixed boundary is too small, it will cause more obvious nonlinear phenomenon in the system dynamics. From this study, the fixed boundary of the leaf spring can have a certain influence on the natural frequency of the vibratory conveyor. The greater the rigidity of the leaf spring, the greater the tightening strength of the leaf spring at the fixed end is required to reduce the nonlinearity of the machine. In addition, the distribution of clamping force on the fixed boundary will also have impact on the natural frequency and stability of the mechanism. More uniform distribution of the force on both sides of the fixed end can not only increase the natural frequency, but also reduce the nonlinear phenomenon and make the mechanism run more stably.
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Nascimento, Vítor Emanuel Morais. "Desenvolvimento de conceito - bateria MAD – (MAgnetic spring Disk)." Master's thesis, 2018. http://hdl.handle.net/10316/86046.
Full textAbstract:
Dissertação de Mestrado Integrado em Engenharia Mecânica apresentada à Faculdade de Ciências e TecnologiaA integração de sistemas de armazenamento de energia (ESS) na gestão da produção e planeamento de grandes centrais elétricas é um dos objetivos mais cobiçados da atualidade. As tecnologias existentes não são ainda suficientemente capazes de responder ao problema e, não só o planeta mas também a economia começam a sentir as consequências. A ciência e a engenharia têm feito progressos no melhoramento das tecnologias atuais no sentido de alargar as suas aplicabilidades.Na presente dissertação pretende-se explorar um conceito inovador de ESS baseado na interação magnética entre ímanes permanentes, a bateria MAD. O texto começará por dar a conhecer alguns dos principais sistemas de armazenamento de energia da atualidade, bem como os vários tipos de áreas onde estes se aplicam e também as características que permitem diferenciar as demais tecnologias. Neste contexto, abordam-se as principais vantagens de ESS incorporados na rede de gestão e produção de energia elétrica bem como as consequências da utilização deficiente dos mesmos. Seguir-se-á um estudo numérico para averiguar qual a melhor configuração e geometria para posterior construção do modelo MAD, utilizando o software EMS da EMWorks. O desenho mais promissor encontrado segue o principio de uma mola linear como base para o armazenamento de energia potencial, no entanto, este efeito mola surge de forças atrativas e repulsivas entre campos magnéticos. Cumprindo as premissas resultantes dos estudos numéricos, o texto termina com a construção do modelo proposto, com o objetivo de servir de prova de conceito a esta nova tecnologia. Algumas das conclusões mais importantes deste trabalho são a possibilidade de conceber um ESS com auto-descarga nula e a demonstração da viabilidade de um conceito alternativo de armazenar energia de forma compacta, sem impactos ambientais negativos e com a vestalidade de poder ser aplicado em qualquer parte do mundo, independentemente de quaisquer fatores geológicos ou geográficos.
Integrating energy storage systems (ESS), in large management of energy production is probably one of the holy grails of the present days. The existing solutions are not yet enough to face the problem and, not only the environment but also the economy are starting to feel the consequences. Progress is being made to improve the current technologies, to make them viable for such applications. This paper explores a new concept of ESS, the MAD Battery, based on force interactions between permanent magnets. At first, the reader will be introduced with some of the most important ESS technologies in the market, as well as the tools needed to compare them. At this point, it is going to be discussed some of the most important advantages of integrating ESS on the electric grid, as well as the consequences of the lack of investment in this area. Later on, will be considered a numeric approach making use of EMS software by EMWorks to find the best suitable design before any model construction or experiments. The most promising design found follows the principle of a linear spring as the basis for the storage of potential energy, however, this spring effect arises from attractive and repulsive forces between magnetic fields.Following the principles that resulted in the numeric studies, this paper ends with what concerns the construction of a model that proves this new MAD concept.Some of the most important conclusions are the possibility of conceiving an ESS technology without self-discharge, no environmental impacts and with the versatility to be implemented in any place, regardless of any geologic or geographical factors.
Universidade de Coimbra - Financiamento para aquisição de materiais para contrução do modelo proposto.
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Deng, Chih-ying, and 鄧志瑛. "A Study on the Relationship Among Customers Satisfaction and Repurchase Intention for Hop-Spring Consumers-Hierarchical Linear Model (HLM) Approach." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/31076807534243399142.
Full textAbstract:
碩士東吳大學
國際貿易學系
94
This study aims to analyze the relationship among service quality, customer satisfaction and repurchase intention for hop-spring leisure activities. By the time living lifestyle improves, consumers are demanding more kinds of leisure activities than before. In order to have more customers, improving service quality is one of the most important management aspects for hot-spring hotels. This study was used a perfect analysis method, called Hierarchical Linear Modeling to evaluate the relationship between customer and service quality. Using 28 hot-spring hotels from the North, Central, South and East of the Taiwan hot-spring area as research area, 598 questionnaires were distributed to find out the precise relationship among service quality, customers satisfaction and repurchase intention, in order to provide better suggestions for future studies and hot springs practitioners. The results show that high service quality can lead to better customers’ satisfaction. Even though consumers put their trust on service quality, but customer satisfaction is still the intermediate factor between service quality and customer repurchase intention. Key words: hierarchical linear modeling, hot spring, service quality, customers’ satisfaction, repurchase intention.
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Yu, Li-Feng, and 游麗鳳. "A Hierarchical Linear Model of Organizational Performance, Service Quality and Customer Satisfaction-Evidence from Hot Spring Industry in Hsinchu Area." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/47018455589405758592.
Full textAbstract:
碩士中華大學
企業管理學系碩士班
99
With the increase of personal income and leisure time, more and more people are engaged in outdoor activities surrounding by the natural environment for stress ease or mental and physical relaxation. The most important one is the hot spring outdoor consumption activities. Its physical and mental nursing functions and tourism values are tremendous for tourism development. Thus the most important issues for the hot spring industry are how to improve service quality, customer satisfaction for contributing to the organizational performance. This study aims to explore whether the service quality and customer satisfaction have a positive impact on the organizational performance of the services and whether the organizational performance of the service has interference effects on the service quality and customer satisfaction. In this study, questionnaires have been distributed to the hot spring hotels’ owners and the consumers. A total of 500 consumer questionnaires were issued and 460 questionnaires are valid samples while 45 for hot spring industry owners and 40 are valid. SPSS and HLM are employed as the statistical analysis tools. The statistical data analysis approaches include analysis of demographic variables, reliability and validity analysis, correlation analysis, HLM, and interference analysis. The empirical results show that: 1.The hot spring industry's service quality has a positive impact on customer satisfaction. 2.The organizational performance does not have a positive impact on service quality in the hot spring industry. 3.The organizational performance does not have the interference effect on service quality and customer satisfaction . The managerial implications in the study can provide the hot spring industry in Hsinchu area as references for management and assessment of service performance.
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Riedel, Lukáš. "Rozšíření platformy pro analýzu datových toků o podporu knihoven na vkládání závislostí." Master's thesis, 2021. http://www.nusl.cz/ntk/nusl-448316.
Full textAbstract:
Data lineage forms an important aspect of today's enterprise environment. MANTA Flow is a data lineage analysis platform that already has basic support for analysis of Java programs, provided by one of its components called Bytecode Scanner. Neverthe- less, there are very few applications in today's enterprise environment that do not use dependency injection at least in a very limited way. Therefore, we present an extension of Bytecode Scanner in the MANTA Flow platform to support data lineage analysis of dependency injection frameworks as well. The extension is able to process even complex definitions of standard dependency injection containers. Since the dependency injec- tion influences a selection of method call targets, we also provide a description of call graph structure and its modification to support dependency injection. Last, we use this infrastructure to design and implement a plugin into Bytecode Scanner for the Spring Framework, a popular dependency injection framework targeting Java Platform. The plugin has been successfully tested on a small but realistic software system that can read data from a file, transform them, and write them into a database. 1
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(6620237), Sokheang Thea. "Identification of Stiffness Reductions Using Partial Natural Frequency Data." Thesis, 2019.
Find full textAbstract:
In vibration-based damage detection in structures, often changes in the
dynamic properties such as natural frequencies, modeshapes, and derivatives of
modeshapes are used to identify the damaged elements. If only a partial list of
natural frequencies is known, optimization methods may need to be used to
identify the damage. In this research, the algorithm proposed by Podlevskyi & Yaroshko (2013) is used to determine
the stiffness distribution in shear building models. The lateral load resisting
elements are presented as a single equivalent spring, and masses are lumped at
floor levels. The proposed method calculates stiffness values directly, i.e., without optimization, from the known partial list of natural frequency data and mass
distribution. It is shown that if the number of stories with reduced
stiffness is smaller than the number of known natural frequencies, the stories
with reduced stiffnesses can be identified. Numerical studies on building
models with two stories and four stories are used to illustrate the solution
method. Effect of error or noise in given natural frequencies on stiffness
estimates and, conversely, sensitivity of natural frequencies to changes in
stiffness are studied using 7-, 15-, 30-, and 50-story numerical models. From
the studies, it is learnt that as the number of stories increases, the natural
frequencies become less sensitive to stiffness changes. Additionally, eight
laboratory experiments were conducted on a five-story aluminum structural
model. Ten slender columns were used in each story of the specimen. Damage was
simulated by removing columns in one, two, or three stories. The method can
locate and quantify the damage in cases presented in the experimental studies. It
is also applied to a 1/3 scaled 18-story steel moment frame building tested on
an earthquake simulator (Suita et al., 2015) to identify the reduction in the
stiffness due to fractures of beam flanges. Only the first two natural
frequencies are used to determine the reductions in the stiffness since the
third mode of the tower is torsional and no reasonable planar spring-mass model
can be developed to present all of the translational modes. The method produced possible cases of the
softening when the damage was assumed to occur at a single story.
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喜弘, 山梶, and Yoshihiro Yamakaji. "車両駆動系トーショナルダンパにおける非線形振動に関する研究." Thesis, 2003. http://id.nii.ac.jp/1707/00028174/.
Full textAbstract:
年々増大するエンジントルク変動を低減するために広角トーショナルダンパの適用例が増してきているが，それらに起因する非線形振動のメカニズムや振動低減のための研究例は少ない．本論文の目的は，これらに関する非線形振動の解明および改善，および精度と計算コストを両立するモデルの開発である．そのため，実験検証に基づくモデルを開発し，非線形振動を大幅に削減する手法を検討した．さらに，計算コストを増加させることなく解析精度を改善する不等ピッチ離散化モデル化手法を検討した．博士(工学)
Doctor of Philosophy in Engineering
同志社大学
Doshisha University