To see the other types of publications on this topic, follow the link: Actuation thermale.
Dissertations / Theses on the topic 'Actuation thermale'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Actuation thermale.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Razzaq, Wasif. "Microfluidic spinning of polymer microfibers : effect of operating parameters on morphology and properties towards the development of novel and smart materials." Thesis, Strasbourg, 2022. http://www.theses.fr/2022STRAE004.
Full textAbstract:
Le filage microfluidique est une technologie émergente pour la production de micro/nanofibres qui ont un fort potentiel pour des applications telles que l’ingénierie tissulaire, l’électronique portable, les systèmes de délivrance de principes actifs et la collecte des eaux. En filage microfluidique, des fibres de diamètres et morphologies contrôlée peuvent être obtenues en manipulant précisément le débit des fluides et la géométrie du dispositif microfluidique. Le but de ce projet doctoral est de développer une expertise et des compétences dans le domaine du filage microfluidique pour produire des fibres polymères par photopolymérisation sous irradiations UV à partir de monomères en utilisant un dispositif microfluidique à base de capillaires avec les objectifs suivants : (1) la mise en place d’une relation empirique pour prédire le diamètre des fibres en prenant en compte les différents paramètres opératoires et de matériaux, (2) la production de fibres Janus/Hecate à partir de monomères ayant différentes propriétés chimiques et physiques avec un contrôle des propriétés morphologiques et mécaniques qui ont été exploitées pour adsorber simultanément des colorants chargés positivement ou négativement, mais aussi pour préparer des actuateurs à partir de fibres Janus thermorépondantes, et (3) le développement d’une approche de modification de surface des fibres pendant leur productionMicrofluidic spinning is an emerging technology to produce micro/nanofibers which have a significant potential in advanced applications such as tissue engineering, wearable electronics, drug delivery, and water harvesting. In microfluidic spinning, fibers with controlled diameters and morphologies could be easily produced by precisely manipulating the fluids flow and the geometry of the microfluidic device. The purpose of this doctoral project was to develop expertise and skills in the field of microfluidic spinning to produce polymer fibers using UV photopolymerization of the monomers using a capillary-based microfluidic device with the following objectives : (1) the development of an empirical relationship to predict the fiber diameter considering the different operating and materials parameters, (2) the production of Janus/Hecate fibers from monomers with different chemical and physical properties with controllability of morphological and mechanical properties that were explored to remove simultaneously cationic and anionic dyes and to prepare thermoresponsive Janus fiber actuators, and (3) the development of an in-process rapid surface modification approach to modify the surface of fibers
2
Miralles, Vincent. "Migration of biphasic systems by thermal actuation in microconfinement." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066365/document.
Full textAbstract:
Cette thèse propose deux applications originales du contrôle de la température dans des microsystèmes, abordant des problématiques d'hydrodynamique et de matière molle.Dans une première partie, nous nous intéressons au contrôle du drainage de mousses 2D en confinement micrométrique par effet Marangoni. Pour ce faire, nous appliquons un gradient de température constant à une mousse bidimensionnelle confinée dans une cellule de Hele-Shaw, et observons que l'effet thermocapillaire induit génère un écoulement surfacique capable de contre-balancer le drainage gravitaire naturel. L'équation de conservation de la masse permet de définir des temps caractéristiques inhérents à chacun de ces effets, aboutissant au contrôle du drainage dans notre système modèle.Dans une seconde partie, nous développons une méthode polyvalente pour la microfluidique digitale, basée sur l'effet thermomécanique. Cet effet consiste à chauffer localement un matériau déformable (i.e. du PDMS), dont la dilatation est mise à profit pour réaliser toutes les opérations élémentaires de microfluidique digitale, telles que la génération de gouttes, leur mise en mouvement, piégeage, stockage, tri, brisure ... notre méthode étant opérationnelle pour des gouttes d'eau dans l'huile ou d'huile dans l'eauThis thesis offers two original applications involving temperature control in microsystems, dealing with hydrodynamics and soft matter. The first part focuses on the drainage control of 2D microfoams by Marangoni effect. To this end, we apply a constant temperature gradient throughout a 2D foam confined in a Hele-Shaw cell, and observe that the induced thermocapillary stress is strong enough to counterbalance and even overcome the natural effect of gravity drainage. The mass conservation in the cell leads to the definition of characteristic drainage times inherent to each effect at play, paving the way to the accurate control of the drainage dynamics in our model system.In a second part, we develop a versatile technology for digital microfluidics, based on thermomechanical effect. This effect consists in locally heating a deformable material (i.e. PDMS), which dilation is used to perform all the elementary operations encountered in digital microfluidics, such as droplet generation, motion, storage, sorting, splitting ... our technology being effective for both oil-in-water and water-in-oil droplets
3
Baker, Michael S. "On-Chip Actuation of Compliant Bistable Micro-Mechanisms." BYU ScholarsArchive, 2003. https://scholarsarchive.byu.edu/etd/52.
Full textAbstract:
Two compliant bistable micro-mechanisms have been developed which can be switched in either direction using on-chip thermal actuation. The energy storage and bistable behavior of the mechanisms are achieved through the elastic deflection of compliant segments. The pseudo-rigid-body model was used for the compliant mechanism design, and for analysis of the large-deflection flexible segments. To achieve on-chip actuation, the mechanism designs were optimized to reduce their required rotation, allow them to be switched using linear-motion thermal actuators. The modeling theory and analysis are presented for several design iterations. Each iteration was successfully fabricated and tested using either the MUMPs or SUMMiT surface micromachining technology.
4
Wilcox, Daniel L. "Fully Compliant Tensural Bistable Mechanisms (FTBM) with On-Chip Thermal Actuation." Diss., CLICK HERE for online access, 2004. http://contentdm.lib.byu.edu/ETD/image/etd526.pdf.
Full text
5
Lammers, Zachary A. "Thermal Management of Electromechanical Actuation System for Aircraft Primary Flight Control Surfaces." University of Dayton / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1399021324.
Full text
6
Smith, Byron Fitzgerald. "Development and Characterization of a Mechanically Prestressed Piezoelectric Composite." VCU Scholars Compass, 2008. http://scholarscompass.vcu.edu/etd/869.
Full textAbstract:
Piezoelectric composites have been investigated for use in a variety of areas, including flow control, structural control, energy harvesting, and fuel ignition systems. While many of the investigations conducted in these areas have utilized traditional piezo actuation systems, such as unimorphs or stack actuators, a growing number of research groups are examining the increased performance derived from the mechanical advantage, and enhanced domain rotation, found in prestressed unimorph designs. Prestressed devices, like Thunder® and LIPCA, have been shown well suited for a number of applications; however, the price associated with these devices can often prevent them from being implemented. In an effort to produce a low cost unimorph device that possesses a performance-enhancing curved form, the present investigation presents a novel technique for manufacturing prestressed piezoelectric actuators that are capable of meeting the same high displacement and load bearing capabilities exhibited by conventional prestressed devices. The newly proposed mechanically prestressed composite device, or MPC, is similar in form and function to well-documented thermally prestressed devices like Thunder®. However, rather than deriving its characteristic curved form from a thermally induced stress, the present class of devices relies on the resorting force incited in the piezoelectric ceramic upon adhesion to a mechanically deformed substrate to provide both the performance-enhancing prestress and final form of the device. To aid in refinement of the newly proposed design, beam theory was used to model the stress developed within the device. The model allowed designers to investigate the limitations imposed on the performance-enhancing curved form of the device by the stresses developed in the ceramic as a result of the curvature. Findings derived from the model were experimentally verified before a finalized design was specified for the composite, and a number of devices were manufactured. An initial characterization of the device was carried out based on the composite's response to mechanical and electrical loading. By determining the slope of the electrically and mechanically induced displacement response of the device, the investigation was able to define the center displacement constant and effective spring constant of the unimorph. These parameters not only allow designers to predict the displacement that will occur in response to a given electric field or tensile load, but also to allow for comparison with various devices. In the present investigation, the performance characteristics of mechanically prestressed composites were assessed as a function of substrate thicknesses and adhesive properties. With composites constructed using substrates approximately 9.2cm in length, devices were found to have typical center displacement constants on the order of 1.59 to 7.78kV/mm2 while retaining an effective stiffness between 4.5 to 7.5N/mm. These values were found to be similar to the .71 to 3.85kV/mm2 center displacement constants demonstrated by similarly sized and shaped Thunder® devices, which posses an effective stiffness in the range of 10 to 16.3N/mm. A comprehensive presentation of the test methods and procedures used to determine these values, along with other performance characteristics, are provided.
7
Minav, Tatiana, Luca Papini, and Matti Pietola. "A Thermal Analysis of Direct Driven Hydraulics." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-200125.
Full textAbstract:
This paper focuses on thermal analysis of a direct driven hydraulic setup (DDH). DDH combines the benefits of electric with hydraulic technology in compact package with high power density, high performance and good controllability. DDH enables for reduction of parasitic losses for better fuel efficiency and lower operating costs. This one-piece housing design delivers system simplicity and lowers both installation and maintenance costs. Advantages of the presented architecture are the reduced hydraulic tubing and the amount of potential leakage points. The prediction of the thermal behavior and its management represents an open challenge for the system as temperature is a determinant parameter in terms of performance, lifespan and safety. Therefore, the electro-hydraulic model of a DDH involving a variable motor speed, fixed-displacement internal gear pump/motors was developed at system level for thermal analysis. In addition, a generic model was proposed for the electric machine, energy losses dependent on velocity, torque and temperature was validated by measurements under various operative conditions. Results of model investigation predict ricing of temperature during lifting cycle, and flattened during lowering in pimp/motor. Conclusions are drawn concerning the DDH thermal behavior.
8
Lott, Christian D. "Electrothermomechanical Modeling of a Surface-micromachined Linear Displacement Microactuator." BYU ScholarsArchive, 2005. https://scholarsarchive.byu.edu/etd/306.
Full textAbstract:
The electrothermomechanical characteristics of an electrically-heated polycrystallinesilicon microactuator are explored. Using finite-difference techniques, an electrothermal model based on the balance of heat dissipation and heat losses is developed. For accurate simulation, the relevant temperature dependent properties from the microactuator material are included in the model. The electrothermal model accurately predicts the steady-state power required to hold position, and the energy consumed during the thermal transient. Thermomechanical models use the predictions of temperature from the electrothermal solution to calculate displacement and force from pseudo-rigid-body approximations and commercial finite-element code. The models are verified by comparing experimental data to simulation results of a single leg-pair on a particular configuration of the device.
The particular microactuator studied is called a Thermomechanical In-plane Microactuator, or TIM, and was fabricated with surface micromachining technology. A TIM requires a single releasable structural layer, is extremely flexible in design, and can operate with simple drive and control circuitry. The TIM produces linear motion of a center shuttle when slender legs on either side move the shuttle as a result of constrained thermal expansion.
In a single example, when the current through a leg with dimensions 250×3×3.5 µm^3 and suspended 2 µm off the substrate is sufficient to maintain an average temperature of 615 C in air and vacuum environments, model simulated temperatures along the leg have a peak of 860 C in air and 1100 C in vacuum. The final measured and predicted displacement is 14 µm. In air, the power predicted by the model needed to maintain this average temperature profile is 95 mW while consuming 16.4 µJ in 0.22 ms to reach 90 percent of the final average temperature. In a vacuum, only 6.4 mW are required to maintain the same average temperature with 97.6 µJ consumed in 18.5 ms. Simulation results suggest that short-duration high-current pulses can improve the transient response and energy consumed in a vacuum when steady-state temperatures are not required. For a TIM leg with the dimensions above, the maximum measured force is approximately 47 µN per leg-pair when enough current is provided to move the TIM 8 µm as a result of ohmic heating and thermal expansion.
9
Cragun, Rebecca. "Thermal Microactuators for Microelectromechanical Systems (MEMS)." BYU ScholarsArchive, 2003. https://scholarsarchive.byu.edu/etd/54.
Full textAbstract:
Microactuators are needed to convert energy into mechanical work at the microscale. Thermal microactuators can be used to produce this needed mechanical work. The purpose of this research was to design, fabricate, and test thermal microactuators for use at the microscale in microelectromechanical systems (MEMS). The microactuators developed were tested to determine the magnitude of their deflection and estimate their force. Five groups of thermal microactuators were designed and tested. All of the groups used the geometrically constrained expansion of various segments to produce their deflection. The first group, Thermal Expansion Devices (TEDs), produced a rotational displacement and had deflections up to 20 µm. The second group, Bi-directional Thermal Expansion Devices (Bi-TEDs) were similar to the TEDs. The difference, as the name implies, was that the Bi-TEDs deflected up to 6 µm in two directions. Thermomechanical In-plane Micromechanisms (TIMs) were the third group tested. They produced a linear motion up to 20 µm. The fourth group was the Rapid Expansion Bi-directional Actuators (REBAs). These microactuators were bi-directional and produced up to 12 µm deflection in each direction. The final group of thermal microactuators was the Joint Actuating Micro-mechanical Expansion Systems (JAMESs). These thermal microactuators rotated pin joints up to 8 degrees. The thermal microactuators studied can be used in a wide variety of applications. They can move ratchets, position valves, move switches, change devices, or make connections. The thermal microactuator groups have their own unique advantages. The TIMS can be tailored for the amount of deflection and output force they produce. This will allow them to replace some microactuator arrays and decrease the space used for actuation. The Bi-TEDs and REBAs are bi-directional and can possibly replace two single direction micro-actuators. The JAMESs can be attached directly to a pin joint of an existing mechanism. These advantages allow these thermal microactuator groups to be used for a wide variety of applications.
10
Messenger, Robert K. "Modeling and Control of Surface Micromachined Thermal Actuators." Diss., CLICK HERE for online access, 2004. http://contentdm.lib.byu.edu/ETD/image/etd434.pdf.
Full text
11
Marzette, Russell K. Jr. "A Feasibility Study of Thin-Shell Deformable Mirrors with Adaptive Truss Support for Spaced-Based Telescopes." Thesis, Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/16214.
Full textAbstract:
Space-based telescopes are limit by the payload requirements of existing launch vehicles. Thus, despite distinct advantages the resolution of terrestrial telescopes exceeds space-based telescopes due to larger size and powerful adaptive optics. To overcome payload limitations, a primary mirror technology that is lighter in weight, but no less effective, is required. As this will result in new structural conditions, new approaches to maintaining the optical shape (figure) of the mirror will also be required.
This thesis culminates work at the Georgia Institute of Technology in modelling a hexagonal thin-shell deformation mirror manipulated by an adaptive truss. This research specifically examines the feasibility of a surface parallel actuated (SPA) thin-shell CuZr deformable mirror (DM) as an alternative to a typical surface normal actuated (SNA) based mirror. It is believed that by using a thin-shell mirror (100 m or less in thickness) with a light weight substrate, such as a truss, that a significant weight-savings will occur, thus enabling larger space based telescopes.
This thesis advances the SPA DM concept by 1) creating a representative model, 2) developing design evaluation methods, 3) evaluating the FEA simulated response of the deformable mirror over Zernike error modes, 4) evaluating the FEA simulated response to select thermal loads, and 5) evaluating the ability of the DM to remove thermal error, and the forces required to do so. Finally, it is concluded that overall the SPA DM concept is feasible.
12
Upadhyay, Vandana. "Design and fabrication of a re-configurable micromirror array for an optical microspectrometer." [Tampa, Fla.] : University of South Florida, 2005. http://purl.fcla.edu/fcla/etd/SFE0001138.
Full text
13
Dhakal, Binod. "Characterization of a 3D Multi-Mechanism SMA Material Model for the Prediction of the Cyclic "Evolutionary" Response of NiTi for Use in Actuations." University of Akron / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1384506213.
Full text
14
Qiu, Shipeng. "INVESTIGATION OF THERMAL, ELASTIC AND LOAD-BIASED TRANSFORMATION STRAINS IN NITI SHAPE MEMORY ALLOYS." Doctoral diss., University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3338.
Full textAbstract:
Polycrystalline NiTi shape memory alloys have the ability to recover their original, pre-deformed shape in the presence of external loads when heated through a solid-solid phase transformation from a lower-symmetry B19' martensite phase to a higher-symmetry B2 austenite phase. The strain associated with a shape memory alloy in an actuator application typically has thermal, elastic and inelastic contributions. The objective of this work was to investigate the aforementioned strains by recourse to in situ neutron diffraction experiments during selected combinations of heating, cooling and/or mechanical loading. The primary studies were conducted on polycrystalline Ni49.9Ti50.1 specimens on the Spectrometer for MAterials Research at Temperature and Stress (SMARTS) at Los Alamos National Laboratory. Quantitative information on the phase-specific strain, texture and phase fraction evolution was obtained from the neutron data using Rietveld refinement and single-peak analyses, and compared with macroscopic data from extensometry. First, the lattice strain evolution during heating and cooling in an unloaded sample (i.e., free-recovery experiment) was studied. The lattice strain evolution remained linear with temperature and was not influenced by intergranular stresses, enabling the determination of a thermal expansion tensor that quantified the associated anisotropy due to the symmetry of B19' NiTi. The tensor thus determined was subsequently used to obtain an average coefficient of thermal expansion that was consistent with macroscopic dilatometric measurements and a 30,000 grain polycrystalline self-consistent model. The accommodative nature of B19' NiTi was found to account for macroscopic shape changes lagging (with temperature) the start and finish of the transformation. Second, the elastic response of B19' martensitic NiTi variants during monotonic loading was studied. Emphasis was placed on capturing and quantifying the strain anisotropy which arises from the symmetry of monoclinic martensite and internal stresses resulting from intergranular constraints between individual variants and load re-distribution among variants as the texture evolved during variant reorientation and detwinning. The methodology adopted took into account both tensile and compressive loading given the asymmetric response in the texture evolution. Plane specific elastic moduli were determined from neutron measurements and compared with those determined using a self-consistent polycrystalline deformation model and from recently reported elastic stiffness constants determined via ab initio calculations. The comparison among the three approaches further helped understand the influence of elastic anisotropy, intergranular constraint, and texture evolution on the deformation behavior of polycrystalline B19' NiTi. Connections were additionally made between the assessed elastic properties of martensitic NiTi single crystals (i.e., the single crystal stiffness tensor) and the overall macroscopic response in bulk polycrystalline form. Lastly, the role of upper-cycle temperature, i.e., the maximum temperature reached during thermal cycling, was investigated during load-biased thermal cycling of NiTi shape memory alloys at selected combinations of stress and temperature. Results showed that the upper-cycle temperature, under isobaric conditions, significantly affected the amount of transformation strain and thus the work output available for actuation. With the objective of investigating the underlying microstructural and micromechanical changes due to the influence of the upper-cycle temperature, the texture evolution was systematically analyzed. While the changes in transformation strain were closely related to the evolution in texture of the room temperature martensite, retained martensite in the austenite state could additionally affect the transformation strain. Additionally, multiple thermal cycles were performed under load-biased conditions in both NiTi and NiTiPd alloys, to further assess and understand the role of retained martensite. Dimensional and thermal stabilities of these alloys were correlated with the volume fraction and texture of retained martensite, and the internal strain evolution in these alloys. The role of symmetry, i.e., B19' monoclinic martensite vs. B19 orthorhombic martensite in these alloys was also assessed. This work not only established a methodology to study the thermal and elastic properties of the low symmetry B19' monoclinic martensite, but also provided valuable insight into quantitative micromechanical and microstructural changes responsible for the thermomechanical response of NiTi shape memory alloys. It has immediate implications for optimizing shape memory behavior in the alloys investigated, with extension to high temperature shape memory alloys with ternary and quaternary elemental additions, such as Pd, Pt and Hf. This work was supported by funding from NASAÂ s Fundamental Aeronautics Program, Supersonics Project (NNX08AB51A) and NSF (CAREER DMR-0239512). It benefited additionally from the use of the Lujan Neutron Scattering Center at Los Alamos National Laboratory, which is funded by the Office of Basic Energy Sciences (Department of Energy) and is operated by Los Alamos National Security LLC under DOE Contract DE-AC52-06NA25396.Ph.D.
Department of Mechanical, Materials and Aerospace Engineering
Engineering and Computer Science
Materials Science & Engr PhD
15
Eckert, Paulo Roberto. "Metodologia de projeto de atuador eletromagnético linear para sistemas de suspensão semiativa e ativa." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2016. http://hdl.handle.net/10183/143941.
Full textAbstract:
Este trabalho apresenta uma metodologia de projeto de atuadores eletromagnéticos lineares inovadora para aplicação em sistemas de suspensão semiativa e ativa. A metodologia, apresentada na forma de fluxograma, define critérios para determinar os requisitos de força e curso que um atuador deve desenvolver considerando um sistema mecânico vibratório com um grau de liberdade com excitação harmônica de base quando o método de controle skyhook é aplicado. Um atuador eletromagnético linear de bobina móvel com duplo arranjo de quase-Halbach que apresenta elevada densidade de força, reduzida massa móvel, ausência de força de relutância e baixa ondulação de força é definido como estudo de caso. Um modelo numérico parametrizado em elementos finitos do comportamento eletromagnético de um passo polar do dispositivo é criado e analisado, considerando restrições dimensionais, com os objetivos de projeto definidos como: elevada densidade de força e reduzida ondulação de força com acionamento brushless CA. Com base no modelo de um passo polar do dispositivo, define-se o volume ativo que o mesmo deve apresentar e, a partir deste, todas as dimensões são definidas de forma a atender os requisitos de projeto. Uma vez definidas as dimensões do atuador com base no modelo eletromagnético, realiza-se a modelagem térmica numérica que permite avaliar qual a máxima densidade de corrente elétrica aplicável de forma que a temperatura, estipulada como máxima, nos enrolamentos não seja excedida. Ainda, a distribuição térmica permite determinar a temperatura de operação dos ímãs permanentes que têm curva de operação dependente da temperatura. A partir dos resultados da simulação térmica e do modelo eletromagnético para um passo polar, realizou-se o acoplamento eletromagnético-térmico por meio da correção das propriedades dos ímãs permanentes e aplicando uma densidade de corrente eficaz dependente das dimensões do modelo parametrizado. O modelo acoplado é simulado e analisado, de modo que as dimensões finais do atuador podem ser obtidas atendendo aos mesmos objetivos de projeto previamente mencionados, respeitando os limites de operação térmica. Adicionalmente, são apresentados modelos analíticos do comportamento eletromagnético e térmico do atuador que podem servir de base para implementação da metodologia proposta, se esta for baseada em modelos analíticos, e podem futuramente ser empregados para a aplicação de otimização matemática do dispositivo. Por fim, um protótipo do dispositivo é construído de forma a validar a metodologia proposta. Com este protótipo são realizados ensaios de densidade de fluxo magnético no entreferro, tensão induzida a vazio, força estática e ensaio dinâmicos com o dispositivo instalado em uma bancada de testes de vibrações controladas desenvolvida durante o projeto. Os resultados mostram a eficácia da metodologia proposta, uma vez que os resultados experimentais mostraram boa concordância com os resultados esperados.This work presents an innovative linear electromagnetic actuator design methodology for application in semi-active and active suspension systems. The methodology, synthesized in a flowchart, sets criteria to determine requirements such as axial force and stroke that an actuator should develop considering a vibration system with one degree of freedom with harmonic base excitation when the skyhook control method is applied. A linear moving-coil electromagnetic actuator with dual quasi-Halbach arrays of permanent magnets that presents high force density, low moving-mass, no reluctance force and low force ripple is defined as a case study. A finite element numerical parameterized model that describes the electromagnetic behavior of one pole pitch of the device is created and analyzed, considering dimensional constraints, with the design objectives defined as: high force density and low ripple of force with brushless AC drive. Based on the model of one pole pitch of the device the active volume and all dimensions are defined in order to meet the design requirements. Once the actuator dimensions are defined, based on the electromagnetic model, a numerical thermal model was constructed, which allows to evaluate the maximum applicable electric current density so that the maximum temperature at the windings is not exceeded. Furthermore, the thermal distribution gives the operating temperature of the permanent magnets, which present performance highly dependent on temperature. With the results of the thermal simulation, the electromagnetic-thermal coupling is performed by correcting permanent magnet properties and by applying a parametric-dependent effective current density. The coupled model is simulated and analyzed so that the final dimensions of the actuator can be obtained with the same design objectives previously mentioned, while respecting thermal operating limits. In addition, the work presents analytical models of the electromagnetic and thermal behavior of the actuator that can be the basis for implementation of the proposed methodology, if it is based on analytical models, and can further be used for the application of mathematical optimization of the device. Finally, a prototype was built to validate the proposed method. Measurements were carried out to assess magnetic flux density in the air gap, open-circuit induced voltage, static force and dynamic tests with the device installed in a test bench that was developed during this work. The results show the effectiveness of the proposed method since experimental results have shown good agreement with the expected results.
16
Colmenares, David. "Design and Control of a Resonant, Flapping Wing Micro Aerial Vehicle Capable of Controlled Flight." Research Showcase @ CMU, 2017. http://repository.cmu.edu/dissertations/1032.
Full textAbstract:
Small scale unmanned aircraft, such as quadrotors, that are quickly emerging as versatile tools for a wide range of applications including search and rescue, hazardous environment exploration, or just shooting great video, are known as micro air vehicles (MAVs). However, for millimeter scale vehicles with weights under 10 grams, conventional flight technologies become greatly inefficient and instead inspiration is drawn from biology. Flapping wing MAVs (FWMAVs) have been created based on insects and hummingbirds in an effort to emulate their extreme agility and ability to hover in place. FWMAVs possess unique capabilities in terms of maneuverability, small size, and ability to operate in dynamic environments that make them particularly well suited for environmental monitoring and swarm applications such as artificial crop pollination. Despite their advantages, significant challenges in fabrication, power, and control must be overcome in order to make FWMAVs a reliable platform. Current designs suffer from high mechanical complexity and often rely on off-board power, sensing, and control, which compromises their autonomy and limits practical applications. The goal of my research is to develop a simple FWMAV design that provides high efficiency and controllability. An efficient, simple, and controllable vehicle design is developed utilizing the principles of resonance, emulation of biological flight control, and under-actuation. A highly efficient, resonant actuator is achieved by attaching a spring in parallel to the output shaft of a commercial geared DC micro-motor. This actuator directly drives the wings of the vehicle, allowing them to be controlled precisely and independently. This direct control strategy emulates biology and differs from other FWMAV designs that utilize complicated transmissions to generate flapping from rotary motor output. Direct control of the wings allows for emulation of biological wing kinematics, resulting in control based on wing motion alone. Furthermore, under-actuation is employed to mimic the rotational motion of insect wings. A rotational joint is added between the motor and wing membrane such that the wing rotates passively in response to aerodynamic forces that are generated as the wing is driven. This design is realized in several stages, initial prototyping, simulation and development of the actuator and wings, then finally a control system is developed. First the system was modeled and improved experimentally in order to achieve lift off. Improvements to the actuator were realized through component variation and custom fabrication increasing torque and power density by 161.1% and 666.8% respectively compared to the gearmotor alone and increased the resonant operating frequency of the vehicle from 4 Hz to 23 Hz. Advances in wing fabrication allowed for flexible wings that increased translational lift production by 35.3%, aerodynamic efficiency by 41.3%, and the effective lift coefficient by 63.7% with dynamic twisting. A robust control architecture was then developed iteratively based on a date driven system model in order to increase flight time from 1 second (10 wing strokes) to over 10 seconds (230 wing strokes). The resulting design improves lift to weight by 166%, allowing for a payload capacity of approximately 8.7 g and offers the potential for fully autonomous operation with all necessary components included on-board. A thermal model for micro-motors was developed and tuned to accurately predict an upper limit of system operation of 41 seconds as well as to optimize a heatsink that increases operating time by 102.4%.
17
Jensen, Kimberly A. "Analysis and Design of Surface Micromachined Micromanipulators for Out-of-Plane Micropositioning." BYU ScholarsArchive, 2003. https://scholarsarchive.byu.edu/etd/230.
Full textAbstract:
This thesis introduces two ortho-planar MEMS devices that can be used to position microcomponents: the XZ Micropositioning Mechanism and the XYZ Micromanipulator. The displacement and force relationships are presented. The devices were fabricated using surface micromachining processes and the resulting mechanisms were tested. A compliant XYZ Micromanipulator was also designed to reduce backlash and binding. In addition, several other MEMS positioners were fabricated and tested: the Micropositioning Platform Mechanism (MPM), the Ortho-planar Twisting Micromechanism (OTM), and the Ortho-planar Spring Micromechanism (OSM).
18
Samel, Björn. "Novel Microfluidic Devices Based on a Thermally Responsive PDMS Composite." Doctoral thesis, KTH, Mikrosystemteknik, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4470.
Full textAbstract:
The field of micro total analysis systems (μTAS) aims at developments toward miniaturized and fully integrated lab-on-a-chip systems for applications, such as drug screening, drug delivery, cellular assays, protein analysis, genomic analysis and handheld point-of-care diagnostics. Such systems offer to dramatically reduce liquid sample and reagent quantities, increase sensitivity as well as speed of analysis and facilitate portable systems via the integration of components such as pumps, valves, mixers, separation units, reactors and detectors. Precise microfluidic control for such systems has long been considered one of the most difficult technical barriers due to integration of on-chip fluidic handling components and complicated off-chip liquid control as well as fluidic interconnections. Actuation principles and materials with the advantages of low cost, easy fabrication, easy integration, high reliability, and compact size are required to promote the development of such systems. Within this thesis, liquid displacement in microfluidic applications, by means of expandable microspheres, is presented as an innovative approach addressing some of the previously mentioned issues. Furthermore, these expandable microspheres are embedded into a PDMS matrix, which composes a novel thermally responsive silicone elastomer composite actuator for liquid handling. Due to the merits of PDMS and expandable microspheres, the composite actuator's main characteristic to expand irreversibly upon generated heat makes it possible to locally alter its surface topography. The composite actuator concept, along with a novel adhesive PDMS bonding technique, is used to design and fabricate liquid handling components such as pumps and valves, which operate at work-ranges from nanoliters to microliters. The integration of several such microfluidic components promotes the development of disposable lab-on-a-chip platforms for precise sample volume control addressing, e.g. active dosing, transportation, merging and mixing of nanoliter liquid volumes. Moreover, microfluidic pumps based on the composite actuator have been incorporated with sharp and hollow microneedles to realize a microneedle-based transdermal patch which exhibits on-board liquid storage and active dispensing functionality. Such a system represents a first step toward painless, minimally invasive and transdermal administration of macromolecular drugs such as insulin or vaccines. The presented on-chip liquid handling concept does not require external actuators for pumping and valving, uses low-cost materials and wafer-level processes only, is highly integrable and potentially enables controlled and cost-effective transdermal microfluidic applications, as well as large-scale integrated fluidic networks for point-of care diagnostics, disposable biochips or lab-on-a-chip applications. This thesis discusses several design concepts for a large variety of microfluidic components, which are promoted by the use of the novel composite actuator. Results on the successful fabrication and evaluation of prototype devices are reported herein along with comprehensive process parameters on a novel full-wafer adhesive bonding technique for the fabrication of PDMS based microfluidic devices.QC 20100817
19
Belháč, Jakub. "Optimalizace pohybu termoelektrického lineárního aktuátoru." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2011. http://www.nusl.cz/ntk/nusl-229391.
Full textAbstract:
The thesis describes movement optimization of a linear thermoelectric actuator that is used for operating floor heating valves in modern buildings. Featuring experimental nature, the thesis deals with a problem specified by an industrial company within the following steps; definition of possible solutions based on problem research, experimental verification of selected propositions, the best solution selection resulting from the analysis of executed measurements, final verification with all product versions, benchmarking.
20
Deng, Kangfa, Gerald Gerlach, and Margarita Guenther. "Force-compensated hydrogel-based pH sensor." SPIE, 2015. https://tud.qucosa.de/id/qucosa%3A35185.
Full textAbstract:
This paper presents the design, simulation, assembly and testing of a force-compensated hydrogel-based pH sensor. In the conventional deflection method, a piezoresistive pressure sensor is used as a chemical-mechanical-electronic transducer to measure the volume change of a pH-sensitive hydrogel. In this compensation method, the pH-sensitive hydrogel keeps its volume constant during the whole measuring process, independent of applied pH value. In order to maintain a balanced state, an additional thermal actuator is integrated into the close-loop sensor system with higher precision and faster dynamic response. Poly (N-isopropylacrylamide) (PNIPAAm) with 5 mol% monomer 3-acrylamido propionic acid (AAmPA) is used as the temperature-sensitive hydrogel, while poly (vinyl alcohol) with poly (acrylic acid) (PAA) serves as the pH-sensitive hydrogel. A thermal simulation is introduced to assess the temperature distribution of the whole microsystem, especially the temperature influence on both hydrogels. Following tests are detailed to verify the working functions of a sensor based on pH-sensitive hydrogel and an actuator based on temperature-sensitive hydrogel. A miniaturized prototype is assembled and investigated in deionized water: the response time amounts to about 25 min, just half of that one of a sensor based on the conventional deflection method. The results confirm the applicability of the compensation method to the hydrogel-based sensors.
21
Casalena, Lee. "Multimodal Nanoscale Characterization of Transformation and Deformation Mechanisms in Several Nickel Titanium Based Shape Memory Alloys." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1499568013015563.
Full text
22
Байда, Євген Іванович. "Мультифізичні моделі високовольтних вакуумних вимикачів з бістабільними поляризованими актуаторами в динамічних режимах." Thesis, НТУ "ХПІ", 2018. http://repository.kpi.kharkov.ua/handle/KhPI-Press/37466.
Full textAbstract:
Дисертація на здобуття наукового ступеня доктор технічних наук за спеціальністю 05.09.01 "Електричні машини і апарати" (141 – електрична інженерія). – Національний технічний університет "Харківський політехнічний інститут", м. Харків, 2018 р.
У дисертаційній роботі розглянуто проблеми створення мультифізичних моделей, що використовуються при дослідженні і проектуванні вакуумних вимикачів середньої напруги. Об'єкт дослідження – нестаціонарні електромагнітні процеси в неоднорідному, нелінійному, рухомому середовищі, що проводить електричний струм і включає в себе висококоерцитивні постійні магніти; процеси, пов'язані з теорією пружності, механікою твердого тіла, явищами в нестаціонарних теплових полях і теорією механіки суцільних середовищ. Предмет дослідження – вакуумні вимикачі з бістабільними поляризованими актуаторами та закономірності їхньої роботі в динамічних режимах; закономірності та механізм статичної і динамічної деформації контактної системи вимикача під впливом актуатора; здатність вимикача до вмикання та його термічна стійкість під дією аварійних надструмів; рідинні демпфери; електричні схеми керування актуатором. Методи дослідження – дослідження електромагнітних, механічних, теплових процесів і процесів течії рідини базуються на аналітичних і чисельних математичних моделях, які враховують найбільш суттєві лінійні та нелінійні взаємозв'язки між явищами. Чисельні розв'язання диференційних рівнянь в часткових похідних проводяться в спеціальних прикладних пакетах програм, достовірність результатів яких багаторазово перевірена і не викликає сумнівів, а також програмах, написаних здобувачем, які перевірені експериментально. В роботі отримані такі наукові результати. Вперше розроблена модель динаміки поляризованого бістабільного актуатора з постійними магнітами, що базується на розрахунках нестаціонарного електромагнітного поля в нелінійному неоднорідному середовищі, що проводить електричний струм та містить постійні магніти з урахуванням руху частин актуатора у взаємодії з нелінійними рівняннями електричного кола і руху. Розраховані параметри форсованого підключення актуаторів та надано рекомендації щодо конструкції та параметрів актуаторів. Розроблено мультифізичні моделі дослідження впливу параметрів актуаторів на статичні і динамічні механічні напруження в сильфоні вакуумної камери, отримані рекомендації з вибору оптимальної конструкції сильфона і його довговічності, розрахована його втомна витривалість. Розроблено модель впливу параметрів актуаторів на динамічні механічні напруження в контактній системі та механізмі вимикача, що базується на теорії пружності, завдяки чому була розрахована геометрія приводного вала та обраний його матеріал та підшипники. Вперше розроблено мультифізичні моделі, що дозволяють визначити вплив динамічних характеристик актуатора на здатність вимикача до вмикання аварійного надструму: визначена динаміка зіткнення і час вібрації контактів; вирішена теплова задача Стефана з урахуванням теплоти фазових переходів і визначена можлива сила зварювання контактів; надано рекомендації щодо зниження швидкості зіткнення контактів за рахунок застосування рідинного демпфера засновані на рівняннях Нав'є – Стокса і динаміки руху актуатора; розроблена модель нагріву і деформації контактної поверхні і на її основі надані рекомендації щодо розрахунків необхідної сили контактного натискання і геометрії контактів за умов термічної стійкості. Досліджено та проаналізовано оригінальні моделі схем підключення котушок актуатора до різних джерел електричної енергії, надано рекомендації щодо їх практичної реалізації. Результати дослідження були перевірені на макетах, дослідних зразках які підтвердили отримані рекомендації та висновки і використовувались при розробці вакуумних вимикачів. Впровадження основних наукових і практичних результатів дисертаційної роботи знайшло відображення: в договірній роботі з ТОВ «АВМ Ампер» договір № 33 / 98-12 між НТУ «ХПІ» та ТОВ «АВМ Ампер», «Вплив параметрів бістабільного поляризованого актуатора вакуумного вимикача на його здатність до вмикання», м. Кременчук; науково-дослідній та дослідно-конструкторській роботі, яка була виконаної на замовлення ТОВ НВП «Укренергокомплекс-2», «Бістабільні актуатори в установках контролю і розподілу потоків рідини», м. Харків та навчальному процесі. Акти впровадження додаються.Dissertation for the degree of Doctor of Technical Sciences in specialty 05.09.01 "Electric Machines and Apparatus" (141 – Electrical Engineering). – National Technical University "Kharkov Polytechnic Institute", Kharkov, 2018. In the dissertation work the problems of creation of multiphysical models used in the research and designing of medium voltage vacuum switching devices are considered. The object of the study is transient electromagnetic processes in a heterogeneous, nonlinear, moving medium conducting electric current and including high-coercive permanent magnets; processes related to the theory of elasticity, solid state mechanics, phenomena in non-stationary thermal fields, and the theory of continuum mechanics. Subject of research – vacuum switching devices with bistable polarized actuators; dynamics of actuators; static and dynamic deformation of the contact system of the circuit breaker and the mechanism under the influence of the actuator; the ability of the circuit breaker to switch on and the thermal stability of the circuit breaker under the influence of emergency overvoltage's; liquid dampers; electromagnetic actuator’s control circuit. Research methods – the investigations of electromagnetic, mechanical, thermal processes and fluid flow processes are based on analytical and numerical mathematical models that take into account the most significant linear and nonlinear interconnections between phenomena. Numerical solutions of partial differential equations are carried out using special application software packages, the reliability of which is repeatedly confirmed and does not cause doubts, as well as codes written by the applicant. The following scientific results have been obtained in the work. For the first time a model of dynamics of a polarized bistable actuator with permanent magnets has been developed based on calculations of transient electromagnetic field in a nonlinear non-uniform medium conducting electric current and containing permanent magnets taking into account the motion of parts of the actuator in conjunction with nonlinear equations of electric circuit and motion. The parameters of forced switching on of actuators are calculated and recommendations on the design and parameters of actuators are given. The multiphysical models of studying the influence of actuator parameters on static and dynamic mechanical stresses in a vacuum chamber bellows have been developed, recommendations have been obtained for choosing the optimal structure of a bellows and its durability, its fatigue endurance is calculated. A model of the influence of actuator parameters on dynamic mechanical stresses in the contact system and the switching mechanism based on the theory of elasticity was developed, due to which the geometry of the drive shaft was calculated and its material was chosen. For the first time, multiphysical models have been developed to determine the effect of the actuator's dynamic characteristics on the ability of the circuit breaker to activate the emergency overloads: shock dynamics and contact vibration time are defined; the Stefan thermal problem solved, the heat of phase transitions is taken into account, and the possible strength of contact welding is determined; recommendations for reducing the contact collision rate due to the use of a liquid damper based on the Navies-Stokes equation and dynamics of the actuator are given; the model of heating and deformation of the contact surface was developed and on its basis recommendations were given regarding calculations of the required force of contact pressure and the geometry of the contacts in the conditions of thermal stability. The original models of circuits connecting actuator coils to different sources of electric energy have been investigated and analyzed, and recommendations on their practical implementation have been given. The results of the study were checked on layouts, prototypes and used in the development of vacuum circuit breakers, tests of which models were confirmed by the obtained recommendations and conclusions. Implementation of the main scientific and practical results of the dissertation work was reflected: in agreement with «ABM Ampere», Kremenchk agreement No. 33/98-12 between NTU «KhPI» and «ABM Ampere» LLC «Influence of the parameters of a bistable polarized vacuum actuator of the circuit breaker on its ability to switch on», research and development work performed by order of Ukrenergokompleks-2 LLC, Kharkov «Bistable actuators in control plants and distribution of liquid flows», the acts of implementation are added.
23
Байда, Євген Іванович. "Мультифізичні моделі високовольтних вакуумних вимикачів з бістабільними поляризованими актуаторами в динамічних режимах." Thesis, НТУ "ХПІ", 2018. http://repository.kpi.kharkov.ua/handle/KhPI-Press/37464.
Full textAbstract:
Дисертація на здобуття наукового ступеня доктор технічних наук за спеціальністю 05.09.01 "Електричні машини і апарати" (141 – електрична інженерія). – Національний технічний університет "Харківський політехнічний інститут", м. Харків, 2018 р.
У дисертаційній роботі розглянуто проблеми створення мультифізичних моделей, що використовуються при дослідженні і проектуванні вакуумних вимикачів середньої напруги. Об'єкт дослідження – нестаціонарні електромагнітні процеси в неоднорідному, нелінійному, рухомому середовищі, що проводить електричний струм і включає в себе висококоерцитивні постійні магніти; процеси, пов'язані з теорією пружності, механікою твердого тіла, явищами в нестаціонарних теплових полях і теорією механіки суцільних середовищ. Предмет дослідження – вакуумні вимикачі з бістабільними поляризованими актуаторами та закономірності їхньої роботі в динамічних режимах; закономірності та механізм статичної і динамічної деформації контактної системи вимикача під впливом актуатора; здатність вимикача до вмикання та його термічна стійкість під дією аварійних надструмів; рідинні демпфери; електричні схеми керування актуатором. Методи дослідження – дослідження електромагнітних, механічних, теплових процесів і процесів течії рідини базуються на аналітичних і чисельних математичних моделях, які враховують найбільш суттєві лінійні та нелінійні взаємозв'язки між явищами. Чисельні розв'язання диференційних рівнянь в часткових похідних проводяться в спеціальних прикладних пакетах програм, достовірність результатів яких багаторазово перевірена і не викликає сумнівів, а також програмах, написаних здобувачем, які перевірені експериментально. В роботі отримані такі наукові результати. Вперше розроблена модель динаміки поляризованого бістабільного актуатора з постійними магнітами, що базується на розрахунках нестаціонарного електромагнітного поля в нелінійному неоднорідному середовищі, що проводить електричний струм та містить постійні магніти з урахуванням руху частин актуатора у взаємодії з нелінійними рівняннями електричного кола і руху. Розраховані параметри форсованого підключення актуаторів та надано рекомендації щодо конструкції та параметрів актуаторів. Розроблено мультифізичні моделі дослідження впливу параметрів актуаторів на статичні і динамічні механічні напруження в сильфоні вакуумної камери, отримані рекомендації з вибору оптимальної конструкції сильфона і його довговічності, розрахована його втомна витривалість. Розроблено модель впливу параметрів актуаторів на динамічні механічні напруження в контактній системі та механізмі вимикача, що базується на теорії пружності, завдяки чому була розрахована геометрія приводного вала та обраний його матеріал та підшипники. Вперше розроблено мультифізичні моделі, що дозволяють визначити вплив динамічних характеристик актуатора на здатність вимикача до вмикання аварійного надструму: визначена динаміка зіткнення і час вібрації контактів; вирішена теплова задача Стефана з урахуванням теплоти фазових переходів і визначена можлива сила зварювання контактів; надано рекомендації щодо зниження швидкості зіткнення контактів за рахунок застосування рідинного демпфера засновані на рівняннях Нав'є – Стокса і динаміки руху актуатора; розроблена модель нагріву і деформації контактної поверхні і на її основі надані рекомендації щодо розрахунків необхідної сили контактного натискання і геометрії контактів за умов термічної стійкості. Досліджено та проаналізовано оригінальні моделі схем підключення котушок актуатора до різних джерел електричної енергії, надано рекомендації щодо їх практичної реалізації. Результати дослідження були перевірені на макетах, дослідних зразках які підтвердили отримані рекомендації та висновки і використовувались при розробці вакуумних вимикачів. Впровадження основних наукових і практичних результатів дисертаційної роботи знайшло відображення: в договірній роботі з ТОВ «АВМ Ампер» договір № 33 / 98-12 між НТУ «ХПІ» та ТОВ «АВМ Ампер», «Вплив параметрів бістабільного поляризованого актуатора вакуумного вимикача на його здатність до вмикання», м. Кременчук; науково-дослідній та дослідно-конструкторській роботі, яка була виконаної на замовлення ТОВ НВП «Укренергокомплекс-2», «Бістабільні актуатори в установках контролю і розподілу потоків рідини», м. Харків та навчальному процесі.Dissertation for the degree of Doctor of Technical Sciences in specialty 05.09.01 "Electric Machines and Apparatus" (141 – Electrical Engineering). – National Technical University "Kharkov Polytechnic Institute", Kharkov, 2018. In the dissertation work the problems of creation of multiphysical models used in the research and designing of medium voltage vacuum switching devices are considered. The object of the study is transient electromagnetic processes in a heterogeneous, nonlinear, moving medium conducting electric current and including high-coercive permanent magnets; processes related to the theory of elasticity, solid state mechanics, phenomena in non-stationary thermal fields, and the theory of continuum mechanics. Subject of research – vacuum switching devices with bistable polarized actuators; dynamics of actuators; static and dynamic deformation of the contact system of the circuit breaker and the mechanism under the influence of the actuator; the ability of the circuit breaker to switch on and the thermal stability of the circuit breaker under the influence of emergency overvoltage's; liquid dampers; electromagnetic actuator’s control circuit. Research methods – the investigations of electromagnetic, mechanical, thermal processes and fluid flow processes are based on analytical and numerical mathematical models that take into account the most significant linear and nonlinear interconnections between phenomena. Numerical solutions of partial differential equations are carried out using special application software packages, the reliability of which is repeatedly confirmed and does not cause doubts, as well as codes written by the applicant. The following scientific results have been obtained in the work. For the first time a model of dynamics of a polarized bistable actuator with permanent magnets has been developed based on calculations of transient electromagnetic field in a nonlinear non-uniform medium conducting electric current and containing permanent magnets taking into account the motion of parts of the actuator in conjunction with nonlinear equations of electric circuit and motion. The parameters of forced switching on of actuators are calculated and recommendations on the design and parameters of actuators are given. The multiphysical models of studying the influence of actuator parameters on static and dynamic mechanical stresses in a vacuum chamber bellows have been developed, recommendations have been obtained for choosing the optimal structure of a bellows and its durability, its fatigue endurance is calculated. A model of the influence of actuator parameters on dynamic mechanical stresses in the contact system and the switching mechanism based on the theory of elasticity was developed, due to which the geometry of the drive shaft was calculated and its material was chosen. For the first time, multiphysical models have been developed to determine the effect of the actuator's dynamic characteristics on the ability of the circuit breaker to activate the emergency overloads: shock dynamics and contact vibration time are defined; the Stefan thermal problem solved, the heat of phase transitions is taken into account, and the possible strength of contact welding is determined; recommendations for reducing the contact collision rate due to the use of a liquid damper based on the Navies-Stokes equation and dynamics of the actuator are given; the model of heating and deformation of the contact surface was developed and on its basis recommendations were given regarding calculations of the required force of contact pressure and the geometry of the contacts in the conditions of thermal stability. The original models of circuits connecting actuator coils to different sources of electric energy have been investigated and analyzed, and recommendations on their practical implementation have been given. The results of the study were checked on layouts, prototypes and used in the development of vacuum circuit breakers, tests of which models were confirmed by the obtained recommendations and conclusions. Implementation of the main scientific and practical results of the dissertation work was reflected: in agreement with «ABM Ampere», Kremenchk agreement No. 33/98-12 between NTU «KhPI» and «ABM Ampere» LLC «Influence of the parameters of a bistable polarized vacuum actuator of the circuit breaker on its ability to switch on», research and development work performed by order of Ukrenergokompleks-2 LLC, Kharkov «Bistable actuators in control plants and distribution of liquid flows».
24
Dunbabin, Matthew D. "The influence of temperature on PZT sensors & actuators for active vibration control of flexible structures." Thesis, Queensland University of Technology, 2002. https://eprints.qut.edu.au/36162/7/36162_Digitised%20Thesis-4_Redacted.pdf.
Full textAbstract:
In real operating environments, flexible structures exhibiting dynamic oscillations such as aircraft and spacecraft can experience large changes in temperature during their normal operating cycle, typically in the range -70 to 80 degrees Celsius. The use of piezoelectric actuators and sensors to control these dynamic oscillations have been widely explored at constant temperature, although only limited studies have been conducted on the effect that varying temperature has on the active control of flexible structures.
The objective of this research is to study the influence of PZT sensors and actuators for vibration control of flexible structures where nonlinearities in piezoelectric and structural material properties change as the system temperatures vary significantly with time. This involved the development of a set of data based parameters that enabled the accurate modelling of a nonlinear flexible system in which its dynamics are actively controlled via the use of piezoelectric sensors and actuators. These parameters determined the design of a control scheme to actively control the system over a large range of operating temperatures, and give an optimised control performance throughout its operating regime.
The work reported in this thesis describes selected methods for rapidly examining a number of the more common nonlinear properties of PZT associated with vibration control. An extensive numerical and experimental investigation is performed which shows that when used in active vibration control applications, the variations in PZT properties with temperature can ultimately affect the ability of the piezoelectric actuator and sensors to suppress vibration in flexible structures.
Accurate simulation models of the lightweight piezo-actuated cantilevered structures were developed to evaluate the performance of a number of common vibration control schemes subject to significant temperature variations. This research was then extended to an innovative scaled wing-type structure subjected to temperature variations. A suitable adaptive self-tuning control scheme was developed and investigated numerically and experimentally, illustrating the benefit of adaptive control in this instance. The adaptive control technique was shown numerically and experimentally to provide improved settling times and damping ratios over equivalent fixed gain controllers for the class of structures investigated where limited control authority exists.
The experimental investigation of PZT sensors and actuators has provided further understanding of the nonlinear behaviour of various light, flexible structures where temperature effects on the system dynamics and control are significant. This research has unveiled previously unreported nonlinearities and has expanded on traditional nonlinearities. These results can assist with the detailed design of applications involving PZT sensors and actuators in for example the aerospace and automotive industries.
25
Debien, Antoine. "Étude électromécanique et optimisation d'actionneurs plasmas à décharge à barrièrediélectrique – Application au contrôle de décollement sur un profil d'aile de type NACA0015." Thesis, Poitiers, 2013. http://www.theses.fr/2013POIT2253/document.
Full textAbstract:
Cette thèse est effectuée dans le cadre du projet Européen "PlasmAero" dont le but est de développer et d'étudier des actionneurs plasmas, et de démontrer leur capacité à contrôler des écoulements aérodynamiques. L'actionneur plasma à Décharge à Barrière Diélectrique (DBD) de surface est un moyen innovant pour contrôler un écoulement en utilisant le vent électrique induit par la force électrohydrodynamique (EHD) générée au sein du gaz ionisé. Une première partie est dédiée à l'étude des actionneurs plasmas. L'influence de la géométrie de l'électrode active d'une DBD est précisée par des mesures électriques, optiques et mécaniques. Les régimes de la décharge de surface peuvent être totalement modifiés, tout commel'évolution de la force EHD en fonction du temps, calculée ici par bilan intégral. Une géométrie optimisée permet de supprimer le régime de décharge streamer et d'augmenter l'efficacité de l'actionneur de 0,65 à 0,97 mN/W. De plus, des configurations à multi-électrodes (sliding discharge et multi-DBD) sont étudiées et développées. Une multi-DBD à potentiels alternés a permis d'obtenir un vent électrique record de 10,5 m/s.L'étude du contrôle d'un écoulement décollé à mi-corde ou en bord de fuite sur l'extrados d'un profil NACA 0015 fait l'objet de la seconde partie de la thèse. Une DBD standard à deux électrodes, une multi-DBD à six électrodes et une DBD de type "nanoseconde" sont utilisées pour agir sur une séparation à des nombres de Reynolds atteignant 1,3μ106, avec une transition naturelle ou déclenchée. Les résultats démontrent que le contrôle permet de repousser efficacement la séparation, améliorant ainsi les performances aérodynamiques du profilThis work is conducted in the framework of the European PlasmAero project that aims to demonstrate how plasma actuators can be used to control aircraft aerodynamic. Surface Dielectric Barrier Discharge (DBD) is an innovative solution to control a flow with the electric wind induced by the electrohydrodynamic (EHD) force produced by a surface discharge. A first part is dedicated to plasma actuators study. The exposed electrode shape of a DBD actuator is investigated by electrical, optical and mechanical characterization. Discharges properties and EHD force evolution is fully dependent of exposed electrode shape. With an optimized active electrode shape, streamer discharge is cancelled while actuator effectiveness is increased from 0.65 to 0.97 mN/W. Flow field induced by multiple electrode design is also investigated. An innovative multi-DBD design is proposed. Inhibition of mutual interaction between successive DBD actuators and exposed electrode shape optimization conduct to an electric wind velocity of 10.5 m/s. In a second part, the control of boundary layer separation on a NACA 0015 airfoil is investigated. An ac DBD, a multi-DBD and a nanosecond DBD are used to manipulate separation at a Reynolds number Re = 1.3μ106, with tripped and natural boundary layer. Results show that actuators can effectively remove the separation existing without actuation
26
Plantegenet, Thibaud. "Analyse expérimentale de l'effet Morton." Thesis, Poitiers, 2019. http://www.theses.fr/2019POIT2319.
Full textAbstract:
Cette thèse a pour objectif d’étudier expérimentalement l’effet Morton pour différents types de paliers et un rotor rigide ou flexible. L’effet Morton est un phénomène d’instabilité thermique se produisant dans les paliers hydrodynamiques qui a pour conséquence d’influencer le comportement vibratoire du système rotor-palier. L’introduction permet d’évoquer les différents phénomènes d’instabilité thermique, en se concentrant dans un premier temps sur l’effet Newkirk pour en décrire mathématiquement son fonctionnement et comprendre la philosophie des phénomènes d’instabilité thermique. L’étude bibliographique de l’effet Morton est ensuite détaillée (cas industriels, modélisation numérique et analyse expérimentale). La première analyse expérimentale est réalisée pour un rotor rigide supporté par un palier cylindrique. Avant l’analyse des essais dans cette configuration, le banc d’essais est détaillé, les caractéristiques dynamiques du palier sont identifiées expérimentalement. Les essais réalisés à vitesse constante montrent la présence de l’effet Morton « stable ». La seconde étude est conduite avec un rotor flexible et permet de mettre en évidence l’influence du temps de démarrage sur l’apparition d’un comportement instable. La dernière étude expérimentale est réalisée avec le rotor flexible supporté par un palier à patins oscillants à pivots flexibles. Le palier étant d’une conception particulière, une étude bibliographique permet de comprendre son fonctionnement, ses points forts et ses applications. Sa conception, son dimensionnement et sa caractérisation expérimentale sont ensuite détaillés, puis les résultats expérimentaux montrent l’influence du balourd initial sur la stabilité. Pour finir, les résultats expérimentaux de chaque configuration sont comparés et permettent de mieux appréhender le comportement de l’effet Morton dans les paliers hydrodynamiques et son influence sur la dynamique du rotorThe main goal of this thesis is the experimental study of the Morton effect in hydrodynamic bearing for rigid and flexible rotors. The Morton effect is a thermally induced increase of the synchronous vibration phenomenon that appears in journal bearing. The introduction part permits to describe the thermal instabilities with firstly a focus on the Newkirk effect and its mathematical description to understand the philosophy of thermal instabilities. Bibliography study of the Morton effect is fully described (case studies, numerical analyses, experimental analyses). The first experimental analysis is conduct for a rigid rotor on a plain journal bearing. In this configuration, the test rig is detailed, the dynamic characteristics of the bearing are experimentally identified and then the tests at constant rotational speed show the “stable” Morton effect. The second study is achieved with a flexible rotor and permits to show the influence of the start-up time on the Morton effect stability. The last experimental study is realized with the flexible rotor on a tilting pad journal bearing with flexible pivot. This bearing being of a particular design, a bibliography allows to understand its principles, its pros and cons and its applications. Its design and its experimental characterization are detailed and then the experimental results show the unbalance influence on stability. To conclude, experimental results are compared and allow a better understanding of the Morton effect in the journal bearing and its influence on the rotordynamic
27
Tsai, Tsung-Ying, and 蔡宗穎. "Design , Fabrication and Actuation of Thermal Actuating XY-stage for Image Stabilization." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/77068698764761899459.
Full textAbstract:
碩士國立交通大學
電控工程研究所
99
This research presents a MEMS micro electro - thermal actuating XY-stage fabricated by SOI process, and an image-sensor or a micro-lens can be mounted on this stage. A suitable fabrication process is designed to fabricate the stage in this research. The design-flow, fabrication process and measurements are all shown in the paper. The first step is to survey and set up the specification of the XY-stage. The main goals of this research are smaller device size, lower driving voltage and larger actuating displacement, besides, establishing decoupling function and increasing linearity and controllability are our goals, too. The stiffness, Young’s module, coefficient of thermal expansion and distribution of heat are the important factors which will affect the driving efficiency of the stabilizer, so we will pay most attention on design them. To increase yield, the promotion of fabrication process and design skills are presented in this research.
28
Tseng, Ke-hsin, and 曾可欣. "Single-Cell Separation by Thermal Bubble Actuation in Microfluidic Chips." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/56159713231576343818.
Full text
29
Wang, Chun-Chieh, and 王俊傑. "A CMOS micromachined resonant sensor with thermal actuation and piezoresistive sensing." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/11809649355899236369.
Full textAbstract:
碩士國立交通大學
機械工程系所
98
Micromachined resonant sensors have the advantages of robust measurement and quasi-digital output and thus have been applied to various applications such as: pressure measurement, bio-molecular detection, and etc. Realizing these devices with industrial IC CMOS processes is attractive for low cost. However, it can be very challenging for engineers to optimize the device performance. This study intends to develop a resonant sensor using commercially available CMOS process (TSMC, 2P4M) and one post-process step. This resonant sensor is excited by the electro-thermal actuations and the motions are measured by the piezoresistive sensing. The design procedures are discussed in details to indicate that this could be an optimal design with this fabrication process. Besides, different to most sensor applications that acquired piezoresistivity of a film by experiments, this study intend to develop theoretical models to predict it from the film conditions. The existing models cannot be applied because they were all developed for P-type silicon with low doping concentrations. However, it is highly doped, N-type polysilicon in this process.
30
Chou, Chi-En, and 周吉恩. "Thermal actuation and creep performance of Polyethylene terephthalate (PET) artificial muscle." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/88vqhz.
Full text
31
Liu, Kang-Chung, and 劉康仲. "Thermal-Fluid Characteristics of a Phase-Change-Material Thermal Actuator." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/30227103481744724855.
Full textAbstract:
碩士國立成功大學
機械工程學系碩博士班
90
Results of an experimental and numerical investigation on thermal-fluid characteristics of a phase-change-material ( PCM ) thermal actuator consisting of a rectangular enclosure with a moveable upper wall are reported. The working principle of thermal actuator is utilizing volume change associated with melting process of the PCM. The parameters considered in the simulation are as follows：Asp = 2,3,4,6 and 12；Pr=41.7；Ste=0.1,0.3 and 0.5；Sc=0； . Simulation results reveal that the little influence of Rayleigh number on the displacement of upper moveable wall and the average Nusselt number of heated wall of the rectangular enclosure tends to degrade greatly with the increase of the aspect ratio. The numerical results of the displacement of the upper movableof the enclosure during melting process are found to be quite close to those predicted from the one-dimensional conduction analytical analysis. Moreover, in comparison with the experimental data for a rectangular enclosure of aspect ratio 12, the numerical results for the displacement of the upper movable wall appear somewhat overpredicted.
32
"Thermal Actuation and Fluidic Characterization of a Fluorescence-Based Multiplexed Detection System." Master's thesis, 2018. http://hdl.handle.net/2286/R.I.50454.
Full textAbstract:
abstract: This work describes efforts made toward the development of a compact, quantitative fluorescence-based multiplexed detection platform for point-of-care diagnostics. This includes the development of a microfluidic delivery and actuation system for multistep detection assays. Early detection of infectious diseases requires high sensitivity dependent on the precise actuation of fluids.
Methods of fluid actuation were explored to allow delayed delivery of fluidic reagents in multistep detection lateral flow assays (LFAs). Certain hydrophobic materials such as wax were successfully implemented in the LFA with the use of precision dispensed valves. Sublimating materials such as naphthalene were also characterized along with the implementation of a heating system for precision printing of the valves.
Various techniques of blood fractionation were also investigated and this work demonstrates successful blood fractionation in an LFA. The fluid flow of reagents was also characterized and validated with the use of mathematical models and multiphysics modeling software. Lastly intuitive, user-friendly mobile and desktop applications were developed to interface the underlying Arduino software. The work advances the development of a system which successfully integrates all components of fluid separation and delivery along with highly sensitive detection and a user-friendly interface; the system will ultimately provide clinically significant diagnostics in a of point-of-care device.Dissertation/Thesis
Masters Thesis Biomedical Engineering 2018
33
張黃超. "Thermal actuations of carbon nanotubes coated bi-layered polymer films." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/69315299811160142161.
Full textAbstract:
碩士國立清華大學
材料科學工程學系
100
This thesis discusses the thermal actuations of polyethylene terephthalate (PET) and polymethyl methacrylate (PMMA) bi-layers. Thermal actuating is firstly verified by radiation heating. Heat source is then replaced by joule heating (or ohmic heating) arising from carbon nanotubes (CNTs) coated onto one side of bilayered films. Comparisons are made between CNTs-free and -coated actuators at various driving voltages.
34
Yang, PENG. "DEVELOPMENT OF MICRO THERMAL ACTUATOR WITH CAPACTIVE SENSOR." Thesis, 2009. http://hdl.handle.net/1974/1981.
Full textAbstract:
This thesis describes a finite element analysis (FEA) model of an indirect heating thermal actuator. The heat transfer mechanisms are investigated and the conductive heat transfer is found to be the dominant heat transfer mode. A model simplification method is discussed and used in the analysis to reduce the degrees of freedom and avoid meshing failures. The device is fabricated with the MetalMUMPs process. Measurements of the displacement as a function of the driving voltage are made to verify the FEA model. The results show that the simulation result of the FEA model produced a reasonable agreement with the experimental data. The difference between the FEA result and test result is investigated. A novel thermal actuator with integrated capacitive position sensor is also investigated. This new thermal actuator with an integrated capacitive sensor uses the indirect heating thermal actuator discussed in the first part of the thesis to achieve a new integration method. The displacement of the actuator provided by the sensor enables a feedback control capability. The analytical model, FEA and test results for the capacitive sensor are presented to validate the design concept. The test results show a reasonable agreement with the analytical analysis and the FEA. Finally, a manual displacement tuning application and a PI feedback control application with the designed thermal actuator with integrated capacitive sensor are documented.Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2009-07-03 16:17:02.633
35
Lin, Yue-Jheng, and 林岳正. "Micro Thermal Actuator Characterized with Low Driving Voltage." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/71312451332500348633.
Full textAbstract:
碩士淡江大學
機械與機電工程學系碩士班
95
This thesis applies the materials that can achieve the effect of experiment to fabricating the thermo-buckled micro actuators working in the appropriate temperature. This study chooses parylene as major materials and successfully fabricates a novel diaphragm type thermo-buckled microactuator with only a driving voltage of 2.5V and under a working temperature below 40℃. According to the method, the study also fabricates the thermo-reversible coil-like actuators and the diaphragm type micropumps to extend its application. The thermo-reversible coil-like actuators are a single beam structure. It can be transferred to a 3D spiral reversibly by proper heating the embedded electrodes. The term “reversibility” of this device means that the spiral device restores to the original beam structure after stopping the power supply of heating. The maximum twisting angle is 7 degrees under the heating voltage of 2.5V DC. The diaphragm type pumps of sub-mm size driven by a low voltage without apparent temperature rise. The micropumps have the maximum flow rate of 7.05 μm /s. The fabricated thermo-buckled type micropump could be integrated into the implantable bio-sensing system for microfludic driving, and drug delivery.
36
Chen, Wen-Chih, and 陳文誌. "A Single Layer Out-of-plane Micro Electro-Thermal Actuator." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/99837998006278553167.
Full textAbstract:
碩士國立清華大學
動力機械工程學系
89
Out-of-plane electro-thermal actuators have been applied to a variety of fields. Among them, the actuators whose driving method is bi-metal effect have the advantage of simple fabrication processes and are thus most commonly used. However, such an actuator experiences a shear force at the interface of different materials, while actuated. Delamination consequently takes place and therefore decreases its lifetime. In an attempt to overcome the drawback inherent in a bi-metal actuator, a novel bi-directional out-of-plane electro-thermal actuator of single layer thin film material is proposed. The presented actuator comprises four parallel, identical beams. The two inner beams connect the two outer beams with a step, which enables the inner beams and the outer ones located at different planes. While a current only flows through the inner beams, they would experience a temperature rise; the accompanying thermal expansion therefore enables the actuator to bend upwards. On the contrary, while a current only flows through the outer beams, the actuator would bend downwards. The bi-directional out-of-plane motion is thus achieved. The design was examined in light of finite element analysis. The potential application lies in micro-relays, variable capacitors, and optical scanning system.
37
Yang, Sheng-Shing, and 楊盛行. "Two Hot Arm Electro-Thermal Actuator Optimization Using Differential Evolution." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/63368903634784610424.
Full textAbstract:
碩士大同大學
機械工程學系(所)
98
In Micro-Electro-Mechanical Systems, electro-thermal actuator is the power of the device. In order to improve the performance of the device, the researchers try to apply the optimization method or a new design approach to change the design. Two hot arms electro-thermal actuator is adapted from the traditional one hot arm electro-thermal actuator for increasing the tip deflection and force output. There are some studies in design optimization of one hot arm electro-thermal actuator, but no research of optimization of two hot arms electro-thermal actuator is found. In this study, the differential evolution is integrated with commercial finite element program ANSYS for design optimization of two hot arms electro-thermal actuator. First, the one hot arm electro-thermal actuator is investigated and the optimal result is compared with the reference to verify that the architecture and the optimization method used in this study are capable and feasible for optimization of one hot arm electro-thermal actuator. Then same architecture and method are applied to optimize the two hot arms electro-thermal actuator for finding the best dimension of the device. From the comparison of results of the optimum solution this study and the design in the reference, the tip deflection of reference design was increased by more than two times using optimization architecture of this study.
38
Wu, Liang-Chieh, and 吳亮潔. "Motion Control of Thermal Actuator with Incorporated Active Heat Sink." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/84172937680712299895.
Full textAbstract:
博士國立臺灣大學
機械工程學研究所
96
In the micro-electro-mechanical systems (MEMS) regime, thermal actuators have been known for its advantages of high output force, low driving voltage and simple fabrication processes. This dissertation focuses on the dynamic control of the thermal actuation. For thermal actuators using heat resistor effect, the relation between input current and output heat is nonlinear, which also makes the relation between input current and output displacement nonlinear. To make the dynamic control feasible, a proper active heat sink is provided. A theoretical model taking into account the thermoelastic coupling is first developed. The thermoelastic coupling arises from the coupling of the strain rate to the temperature field of the heat transport. The dynamic responses for a harmonically varying thermal load are simulated using the eigenmode expansion method. The thermoelastic coupling effects on the resonant frequency and the quality factor are evaluated for each eigenmode resonance of the deflection. In addition, the dynamic characteristic of thermal actuators is dominated by the first-order characteristic of the heat conduction. Influences of thermal cut-off frequency, thermal diffusivity, thermal convection, and thermal radiation on the dynamic thermal responses are then studied. The active heat sink utilizes the commercial thermoelectric cooler. For thermal actuators operating under a DC/AC composite input current, active heat sink is designed to eliminate the effect of the nonlinear heat on the displacement. Therefore the thermal actuators can be actuated synchronously with the input current. Based on the control equations of the active heat, the scheme to control the input heat of thermal actuators is proposed. A bimorph micro-cantilever beam was fabricated using micromachining techniques. Dynamic responses of thermal actuators were measured using laser Doppler vibrometer. For DC/AC composite input current with AC component being a single-frequency sinusoidal waveform, the measured waveform of the tip velocity is generally agreed with the simulation. The displacement amplitude is 90.4% of the simulated one. The influence of the generated double-frequency heat on the displacement can be reduced by incorporating the active heat sink. The displacement amplitude from double-frequency heat is reduced to 46.5 %. For input current with AC component composed of two sinusoidal frequencies, the displacement stemmed from the generated nonlinear heat can also be reduced with discrepancies from the simulation. In this study, the thermo-mechanical behavior of thermal actuators was investigated theoretically and experimentally. The developed method for the dynamic control of the thermal actuators was also verified. The obtained results provide insights which enable and facilitate further optimization of the dynamic control of thermal actuators.
39
Zheng, Li-Sheng, and 鄭立昇. "Design of A Closed-Loop Controlled CMOS-MEMS Thermal actuator." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/09977163525912382289.
Full textAbstract:
碩士國立清華大學
電子工程研究所
93
We present the design and characterization of a large-displacement thermal actuator fabricated in a conventional TSMC 0.35μm 2P4M CMOS process. The thermally-driven microstructure contains multi-layers of metal, silicon dioxide, and polysilicon, and is fabricated by two dry etching steps after completion of CMOS. To avoid thermal drift caused by change of ambient temperature, we adopt a capacitive sensing scheme that makes use of vertically sensed comb finger electrodes with a nominal sensing capacitance at 11 fF. The microactuator is characterized by static and dynamic measurements, with a measured out-of-plane motion up to 24 μm at 17 mW, a thermal time constant at 0.24 ms, and a mechanical resonant frequency at 25.2 kHz, By external measurement, we understand the relationship of supply power, ambient temperature and actuating displacement. We integrate the actuator and the capacitive sensing circuit within one chip. The measured results show that the device’s sensitivity is 4020 (V/m), and the measured minimum input-referred noise voltage of the sensing pre-amplifier is 5.9 μV/rt.Hz, corresponding to a minimum input-referred noise displacement of 0.15 nm. Because the open-loop operation can’t handle external disturbance, so we design a closed-loop control system to promote the device’s stability.
40
Lee, hong-da, and 李宏達. "Design and Fabrication of The Novel Planar Electro-thermal Actuator." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/82109330746110699053.
Full textAbstract:
碩士國立中興大學
精密工程研究所
92
The electrothermal actuators have been known as their large displacement and high force output. There are two well-studied electrothermal actuators, i.e., the U-shaped actuator and V-beam actuator. Both actuators can provide one directional displacement in the static actuation operation. This characteristic is attributed by that static displacement generated from electrothermal actuators is formed by net volume expansion due to the thermal expansion difference distributed over the whole actuator structure. Since the net volume expansion is always pointing to one direction. In the application of optical switch, it is common to require the on-off operation from the device view point. Thus the actuator is demanded to provide the two-way motion, i.e., forward and backward, for optical switch application. This thesis first presents the comprehensive study on a new electrothermal actuator, denoted as H-shape X-beam actuator. This new actuator can provide large static displacement and force output. Briefly speaking, we compared several different types of H-shape X-beam actuators. According to the simulated results and the measured results, we can find out the optimal design parameters are beam width of 8μm , beam angle of 0.5 degree, and it can achieve maximum displacement of 86μm, under driving voltage of 23 V. Secondly, we proposed a new bi-directional movable electrothermal actuator, denoted as H-beam actuator. We verified the design of H-beam actuators by experimental data based on three types of structures. The best design, type 1 design, of H-beam actuator can generate forward maximum displacement of 52μm, under driving voltage of 40V, and backward maximum displacement of 52μm, under driving voltage of 40 V. Finally, the derived 2x2 optical switch using type 1 H-beam actuator can achieve performance including: IL=-0.96dB, BR=-50dB and PDL=-0.01dB(Transmission State) under driving voltage of 29 V; IL=-0.96dB, BR=-50dB and PDL=-0.01dB(Switching State) under driving voltage of 29V. Forward Switching time is 6.8ms, and backward Switching time is 1.96ms.
41
Heber, André. "Application of Single Optically Heated Gold Nanoparticles to Sensing and Actuation." Doctoral thesis, 2017. https://ul.qucosa.de/id/qucosa%3A16860.
Full textAbstract:
Diese Dissertation demonstriert die Nutzung von einzelnen optisch geheizten Goldnanopartikeln als
Sensoren f ¨ur die Untersuchung von W¨armetransport und als Intensit¨atsmodulator f ¨ur Licht. Die
beschriebenen Experimente basieren auf der photothermischen Mikroskopie, die die selektive Abbildung
and Untersuchung von einzelnen absorbierenden Objekten erm¨oglicht. Goldnanopartikel
werden optisch angeregt. Die Relaxation erfolgt durch nichtstrahlende Prozesse, die zu einer lokalen
Erh¨ohung der Temperatur f ¨uhren. Die Erw¨armung f ¨uhrt zu einer Verringerung der Brechzahl, die als
thermische Linse wirkt und dadurch die Ausbreitung eines zweiten nicht absorbierten Lichtstrahls
vera¨ndert. Da die thermische A¨ nderung der Brechzahl sehr gering ist, wird das photothermische
Signal durch das moduliertes Detektionsverfahren verst¨arkt.
Der Heizlaserstrahl wird intensit¨atsmoduliert und erzeugt dadurch eine geringe Modulation der
Strahlbreite des Detektionslaserstahls. Damit ver¨andert sich die Leistung, die durch eine Blende
transmittiert wird. Diese Modulationsamplitude and Phaseverz¨ogerung werden mittels eines phasenempfindlichen
Gleichrichters detektiert. Amplitude und Phase h¨angen von Modulationsfrequenz
und thermischer Diffusivit¨at ab. Die frequenzaufgel¨oste Messung der beiden Gr¨oßen und deren
Modellierung mittels einer verallgemeinerten Lorenz–Mie Theorie erm¨oglicht die Messung von der
thermischen Diffusivit¨at des Mediums, das das Goldnanopartikel umgibt. In der zweiten Variante
wird die Ausbreitung der W¨arme beobachtet. Ein Nanopartikel wird optisch geheizt und die ausgedehnte
thermische Linse wird mit Hilfe der Ablenkung eines zweiten Laserstrahls vermessen. Das
Ablenkungssignal wird mittels eines strahlenoptischen Models berechnet, um die thermische Diffusivit
¨at des Materials zu bestimmen, das das Nanopartikel umgibt.
In einem weiteren Experiment wird das große Potential von optisch geheizten Nanopartikeln verdeutlicht.
Einzelne Goldnanopartikel werden in eine d¨unne nematische Fl¨ussigkristallschicht eingebettet,
deren Dicke darauf abgestimmt ist, dass die Schicht eine l/2-Platte darstellt. Die Goldnanopartikel
werden optisch geheizt und steuern damit den Phasen¨ubergang von der nematischen zur isotropen
Phase. Damit wird die Transmission eines zweiten Laserstrahls im Polarisationskontrast ge¨andert.
Mit Hilfe dieser Anordnung kann die Intensit¨at eines Lichtstrahls um bis zu 100% moduliert werden.This dissertation demonstrates the use of individual optically heated gold nanoparticles as sensors for investigations of heat transport and intensity modulation of light. The experiments employ the photothermal effect, which allows the selective detection and investigation of individual absorbers. The photothermal contrast is based on absorbing particles that are optically excited and relax via nonradiative processes. The absorbers act as nanosources of heat. The local temperature elevation leads to a local refractive index change due to thermal expansion which then acts as a lens. This thermal lens alters the propagation of a second non-absorbed beam of light. As the refractive index change with temperature is minuscule, the transmission changes of the detection are tiny as well. The photothermal signal is amplified by the use of a modulated detection scheme which enables the methods high sensitivity and provides a time scale for the measurement of thermal transport. The heating laser beam is intensity-modulated and thereby produces a small modulation of the beam waist of the detection laser beam and thus the transmitted power through an aperture. This modulation amplitude and phase are detected by a lock-in amplifier. Amplitude and phase depend on the modulation frequency and the thermal diffusivity of the material surrounding the nanoparticle. The frequency-resolved measurement of the two observables and their modeling using a generalized Lorenz–Mie theory allows the measurement of thermal diffusivities. In the second variant, the spread of heat into space is observed. A nanoparticle is optically heated, and the extended thermal lens is characterized by the deflection of a second laser beam. The deflection signal is modeled using ray optics to determine the thermal diffusivity of the material surrounding the nanoparticle. In a further experiment, the great potential of optically heated nanoparticles is demonstrated. Individual gold nanoparticles are embedded in a thin nematic liquid-crystal layer acting as a half-wave plate. The gold particles are optically heated. They control the transmission of a detection laser set up in polarization contrast. The intensity of the detection beam is modulated by up to 100%.
42
Sitaraman, Hariswaran. "Magneto-hydrodynamics simulation study of high density thermal plasmas in plasma acceleration devices." 2013. http://hdl.handle.net/2152/21618.
Full textAbstract:
The development of a Magneto-hydrodynamics (MHD) numerical tool to study high density thermal plasmas in plasma acceleration devices is presented. The MHD governing equations represent eight conservation equations for the evolution of density, momentum, energy and induced magnetic fields in a plasma. A matrix-free implicit method is developed to solve these conservation equations within the framework of an unstructured grid finite volume formulation. The analytic form of the convective flux Jacobian is derived for general unstructured grids. A Lower Upper Symmetric Gauss Seidel (LU-SGS) technique is developed as part of the implicit scheme. A coloring based algorithm for parallelization of this technique is also presented and its computational efficiency is compared with a global matrix solve technique that uses the GMRES (Generalized Minimum Residual) algorithm available in the PETSc (Portable Extensible Toolkit for Scientific computation) libraries. The verification cases used for this study are the MHD shock tube problem in one, two and three dimensions, the oblique shock and the Hartmann flow problem. It is seen that the matrix free method is comparatively faster and shows excellent scaling on multiple cores compared to the global matrix solve technique. The numerical model was thus verified against the above mentioned standard test cases and two application problems were studied. These include the simulation of plasma deflagration phenomenon in a coaxial plasma accelerator and a novel high speed flow control device called the Rail Plasma Actuator (RailPAc). Experimental studies on coaxial plasma accelerators have revealed two different modes of operation based on the delay between gas loading and discharge ignition. Longer delays lead to the detonation or the snowplow mode while shorter delays lead to the relatively efficient stationary or deflagration mode. One of the theories that explain the two different modes is based on plasma resistivity. A numerical modeling study is presented here in the context of a coaxial plasma accelerator and the effect of plasma resistivity is dealt with in detail. The simulated results pertaining to axial distribution of radial currents are compared with experimental measurements which show good agreement with each other. The simulations show that magnetic field diffusion is dominant at lower conductivities which tend to form a stationary region of high current density close to the inlet end of the device. Higher conductivities led to the formation of propagating current sheet like features due to greater convection of magnetic field. This study also validates the theory behind the two modes of operation based on plasma resistivity. The RailPAc (Rail Plasma Actuator) is a novel flow control device that uses the magnetic Lorentz forces for fluid flow actuation at atmospheric pressures. Experimental studies reveal actuation ~ 10-100 m/s can be achieved with this device which is much larger than conventional electro-hydrodynamic (EHD) force based plasma actuators. A magneto-hydrodynamics simulation study of this device is presented. The model is further developed to incorporate applied electric and magnetic fields seen in this device. The snowplow model which is typically used for studying pulsed plasma thrusters is used to predict the arc velocities which agrees well with experimental measurements. Two dimensional simulations were performed to study the effect of Lorentz forcing and heating effects on fluid flow actuation. Actuation on the order of 100 m/s is attained at the head of the current sheet due to the effect of Lorentz forcing alone. The inclusion of heating effects led to isotropic blast wave like actuation which is detrimental to the performance of RailPAc. This study also revealed the deficiencies of a single fluid model and a more accurate multi-fluid approach is proposed for future work.text
43
WANG, CHEN-YA, and 王貞雅. "Development and Biomedical Application of Microfluidic Biochip Fabrication Technology with Centrifugal Force Actuation and Thermal Control Mechanism." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/20892729701801245966.
Full textAbstract:
碩士長庚大學
醫療機電工程研究所
94
There is currently great interest in combining the functional components that are necessary for performing complex chemical and biochemical analyses into small, integrated units and Micro-Electro-Mechanical Systems (MEMS) are developed quickly in the field of biomedical devices and lab test for the miniaturization of object, which stands for faster reaction, higher efficiency, less specimen and less space. Microfluidic devices, from single element to integrated micro-total-analysis-system (μTAS) or lab-on-a-chip are under development and are expected to speed up and simplify important biological operations. However, the pumping and valving designs of biochip are fabricated by semi-conductor or LIGA process so that the processes not only are complicated but also cost a lot of money. In order to overcome the short- comings of the conventional lab-on-a-chip fabrication, depending on the pumps and valves, this research utilizes centrifugal propulsion to actuate fluid flow in the microfluidic channels and proposes a new lab-on-a-chip fabrication method, “microfluidic biochip fabrication technology with centrifugal force actuation and thermal control mechanism”, and the new fabrication technology will be verified by biomedical applications to test its feasibility. This research comprises of three different stages. The first stage is the microfluidic design of the biochip system. The microfluidic design includes analysis of microfluidic propulsion theory, thermal Conductivity theory, design of functional microfluidic patterns, incision of microfluidic and evaluation of microfluidic quality. The working solution includes using SolidWorks for pattern design, ANSYS for pattern simulation, PowerMill and Visual Basic to design the software window platform for computer numerical control (CNC) programming profile and CNC machine for pattern engraving. FRT and FTA machines are also used to evaluate the microfluidic surface quality. The second stage is the platform design of microfluidic biochip fabrication including capability study and design guideline and hardware design. The hardware design of microfluidic platform includes heat press device to seal the lab-on-a-CD (compact disk), temperature control device, centrifugal actuation device and electronic stroboscopes device. The heat press device with temperature feedback control is designed to seal the biochip. A servo motor within the centrifugal actuation device is used to generate centrifugal force which will lead the sample move through the microfluidic channel instead of pumps and valves. The temperature control device is designed to provide constant temperature for microfluidc channels. The electronic stroboscopes device is mainly used to observe fluid routes in high-speed rotation. The third stage is the clinical biomedical applications. The protocol of clinical test is pre-process and preservation of specimen, quantitative and qualitative biochemical reaction of specimen, and post-process of specimen or sewage. The separation, mixing and heating of specimen are so common in the clinical test that our biochip fabrication technology is verified by blood separation test, hexokinase method and BCG method. Hexokinase method is the measurement of blood sugar and BCG is the measurement of albumin. Seven cases are involved in either control or test group. Each case needs 10 c.c. of blood sample. The microfluidic biochip is applied in the test group and the conventional method offered by Chang Gung Memorial Hospital was applied in the control group. The statistical method, SPSS, was used to verify the value of this technique. In the statistical results of our microfluidic biochip and clinical data, the P-value is 0.115 in the blood sugar test, and 0.075 in the albumin test. To sum up, there is no remarkable different between our novel biochip and clinical test method. Our centrifugal microfluidic fabrication technology with temperature controlled developed in this study is a desk-top device and can use in laboratory or clinical biomedical tests. Furthermore, this biochip can also be used in other clinical tests in near future.
44
Wijeweera, Gayan. "Design of a micromachined electric field sensor using a thermal actuating shutter." 2008. http://hdl.handle.net/1993/21304.
Full text
45
Schick, Justin Ryan. "Transformation Induced Fatigue of Ni-Rich NiTi Shape Memory Alloy Actuators." 2009. http://hdl.handle.net/1969.1/ETD-TAMU-2009-12-7636.
Full textAbstract:
In this work the transformation induced fatigue of Ni-rich NiTi shape memory alloys (SMAs) was investigated. The aerospace industry is currently considering implementing SMA actuators into new applications. However, before any new applications can be put into production they must first be certified by the FAA. Part of this certification process includes the actuator fatigue life. In this study, as-received and polished at dogbone SMA specimens underwent transformation induced fatigue
testing at constant loading. The constant applied loading ranged from 100 MPa to 200 MPa. Specimens were thermally cycled through complete actuation (above Af to below Mf ) by Joule heating and environmental cooling. There were three cooling environments studied: liquid, gaseous nitrogen and vortex cooled air. It was shown that polished specimens had fatigue lives that were two to four times longer than those of as-received specimens. Test environment was also found to have an effect on fatigue life. Liquid cooling was observed to be corrosive, while the gaseous nitrogen and vortex air cooling were observed to be non-corrosive. The two non-corrosive cooling environments performed similarly with specimen fatigue lives that were twice that of specimens fatigue tested in the corrosive cooling environment. Transformation induced fatigue testing of polished specimens in a non-corrosive environment at 200 MPa had an average fatigue life of 14400 actuation cycles; at 150 MPa the average fatigue life was 20800 cycles and at 100 MPa it was 111000 cycles. For all specimens constant actuation from the beginning of testing until failure was observed, without the need for training. Finally, a microstructural study showed that the Ni3Ti precipitates in the material were one of the causes of crack initiation and propagation in the actuators.
46
Lin, Yih Min, and 林益民. "The analysis of micro thermal buckling actuator in the micro fluidic system." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/84247646693257303935.
Full textAbstract:
碩士國立成功大學
機械工程學系
86
The micro fluidic parts which use micro fabricated technique, not only control the fluid accurately, but also respond rapidly, and their volume are tiny. We will take the actuator structure on the thermally buckling valve as the subject here, to discuss the behavior of the valve. We consider the behavior of the actuator during the switch up process here, discuss the effect of the actuation due to the geometric dimension and different boundary conditions of the actuator, to design a perfect micro valve ;analyze the stress distribution in the buckled structure to prevent it from fatigue, and its transient state at the same time, to control its displacement and frequency appropriately. The numerical method that we describe and discuss the driven behavior of the structure is finite element analysis method. From this study, we can find that different boundary condition, thermal load and geometric dimension of the structure will affect its actuated behavior more. We also get the knowledge about its stress distribution in the structure and its transitional behavior. With them, we may design the perfect micro thermal buckling valve.
47
Lin, Yu-Hsin, and 林郁欣. "Development of Integrated Micro Platinum Temperature Sensors in A Novel Thermal Bubble Actuator." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/82793153336198820933.
Full textAbstract:
碩士國立成功大學
航空太空工程學系碩博士班
92
In this thesis, novel thermal bubble actuator has been designed and fabricated for bubble actuator studies. Micro platinum heaters and temperature sensors are integrated within the actuator to study the detailed dynamics of the thermal bubble actuator. Each actuator contains four sets of microheaters/microsensors in the firing chamber, and one set of microheater for the surface tension breaker at the nozzle exit. By actuating the microheater array, the bubble can be generated to eject the liquid droplet out of micro nozzle. According to the number of the microheater actuated, the volume of the liquid droplet can be controlled. Bubbles generated in the firing chamber not only function as a pump, but also serve as a flow regulator between the chamber and the liquid supply. This mechanism can eliminate the bottleneck design, which is use for hydrodynamics cross talk in a conventional inkjet printhead. To investigate the dynamics of the novel thermal bubble actuator, a high speed microscopic imaging system was developed. The high-speed microscopic imaging system will help us diagnose the bubble nucleation, bubble growth and collapse, droplet breakup process, as well as the refilling process. From testing results of the experiment by using a commercial actuator HP ink-jet printhead, the performance of HPc6614d No.20 ink-jet printhead still has plenty of room to be improved. For example, the satellite droplets are found in HP printhead. Satellite droplets means non-uniform droplet sizes, which will degrade the printing quality. For the current thermal bubble actuator, surface tension breaker was design to manipulate the surface tension at the nozzle exit, which use to eliminate satellite droplets.
48
d'Entremont, Rene. "DEVELOPMENT OF NOVEL 2 DOF THERMAL MICRO ACTUATORS AND A COMPARISON OF DIFFERENT DISPLACEMENT MEASUREMENT TECHNIQUES." 2011. http://hdl.handle.net/10222/14021.
Full textAbstract:
This thesis examines the development and testing of a novel 2 DOF (Degrees of
Freedom) thermal actuator using Micro Electro Mechanical Systems (MEMS)
technology. A out-of-plane displacement measurement technique based on optical focus
adjustments is also implemented and tested. In-plane displacement measurement
techniques are also compared.
Existing MEMS actuator can either move in-plane or out-of-plane but no reported
actuators were found to move in a user selectable combination of both domains. The
novel actuator fabricated using the PolyMUMPs process is capable of displacements of 5
?m out-of-plane and 1.5 ?m in-plane. A Finite Element Analysis (FEA) was performed
as a proof of concept prior to physical construction. FEA was also used to characterize
the actuator.
Measuring out-of-plane displacements of MEMS devices is difficult to
accomplish using only a standard microscope and camera setup. Methods have included
tilting the chip so the vertical motion has a planar component. The most common
commercial measurement technique uses interferomery but special expensive equipment
is necessary. A method adapted from biological autofocus is proposed in which multiple
images (100+) are taken at various focal planes. An algorithm is applied which extracts
the most focused image. An out-of-plane displacement measurement can be extracted
between two image sets. Results were compared to optical profiler measurements and the
results had an average error of 0.47 ?m
A comparison of planar displacement measurement methods, which included two
variations of both edge detection and pattern matching along with measurements using
the optical profiler, was accomplished. Consistent planar displacement results were
collected for all techniques except for the simple edge detection.
49
Qiu, Jun-Da, and 邱俊達. "Design and Analysis of a Compliant Bistable Mechanism Actuated by an Electro-thermal Actuator." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/08136025164417595107.
Full textAbstract:
碩士國立中興大學
精密工程學系所
95
A compliant bistable mechanism is designed in this research. It is actuated by an electro-thermal actuator. The main characteristics of the actuator, such as the amount of displacement, the direction of movement, actuating voltage, and temperature distribution etc., are studied with consideration of the effects of surface thermal conduction, thermal convection and heat radiation. With voltage applied to the electro-thermal actuator, the amount of displacement and the variation of the reaction force of the compliant bistable mechanism is studied. A commercial finite element analysis software, ABAQUS 6.4, is used for the simulation. We simulate the stable thermal field of the electro-thermal actuator and the deformation of its structure, and the amount of displacement and the variation of the reaction force of the compliant bistable mechanism. A fabrication process of the compliant bistable mechanism and the electro-thermal actuator is proposed. Keywords: MEMS , Compliant bistable mechanism , Electro-thermal actuator
50
Chen, Po-Yen, and 陳博彥. "Study of a Thermal Flow Sensor integrated with a Valveless One-side Actuating Diaphragm Micropump." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/87406871762117474596.
Full textAbstract:
碩士國立臺灣大學
機械工程學研究所
100
In this study, a new flow sensor combined with the valveless one-side actuating piezoelectric micropump has been successfully developed. The dimension of the flow sensor is 80 mm × 30 mm × 20 mm. The flow sensor uses a silicone heater that is fixed on the top of the microchannel and dissipates the heat by the flow inside the channel. Under constant heating power, we can obtain the relationship between the surface temperature of the heater and the flow rate and use it to measure the flow rate. The maximum flow rate of the valveless micropump is 1.13 mL/s at 150 Hz; while the maximum pump head can reach 1366.0 Pa. The experimental results indicate that the performance of the flow sensor is dominated by the heating power and the flow rate, and the performance is enhanced with increasing the heating power or decreasing the flow rate. Besides, the design of the microchannel suspended from the substrate to improve thermal isolation also proves better performance.