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1
Fay, Dale K. "Characterization of a constant force suspension mechanism." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0015/MQ48265.pdf.
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Weight, Brent L. "Development and design of constant-force mechanisms /." Diss., CLICK HERE for online access, 2001. http://contentdm.lib.byu.edu/ETD/image/etd137.pdf.
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Weight, Brent Lewis. "Development and Design of Constant-Force Mechanisms." BYU ScholarsArchive, 2002. https://scholarsarchive.byu.edu/etd/3.
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This thesis adds to the knowledge base of constant-force mechanisms (CFMs). It begins by reviewing past work done in the area of CFMs and then develops new nondimensionalized parameters that are used to simplify the calculations required to design a CFM. Comparison techniques are then developed that utilize these non-dimensionalized parameters to compare mechanisms based on stiffnesses, percent constant-force, actual lengths, normal displacements, and feasible design orientations. These comparison techniques are then combined with optimization to define new mechanisms with improved performance and range of capabilities. This thesis also outlines a design process, methods to identify mechanisms that are suitable for a given design problem, and relationships and trends between variables. The thesis concludes by discussing the adaptation of CFMs for use in electrical contacts and presenting the results of a design case study which successfully developed a constant-force electrical contact (CFEC).
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Dhanapala, Hembathanthirige Yasas. "Dielectric Constant Measurements Using Atomic Force Microscopy System." Wright State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=wright1347907325.
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Yemm, Richard William. "Development of constant-force tank-testing techniques and associated instrumentation." Thesis, University of Edinburgh, 1995. http://hdl.handle.net/1842/11644.
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Over the last ten years there has been a resurgence of interest in the detailed experimental testing of sailing yacht designs. Part 1 of this thesis reports work carried out with the aim of improving test realism and data quality. Reduction of the cost of testing by increasing the rate of data generation is also reported. Constant-Force towing methods in oblique seas were developed. Both Constant-Force and Constant-Velocity data is presented along with a detailed comparison between the two modes. This comparison shows an apparent, frequency dependent, difference of up to +-2% between the two testing modes. During the work on yacht testing techniques a novel stiff DC loadcell was developed to meet the specific requirements of the tank testing apparatus. Part 2 of this thesis reports the work carried out on the development of this transducer. The final prototype achieved a full scale deflection of 10 microns with an overload factor of more than 20 times the rated load.
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Naylor, Thomas Alexander. "Exploration of Constant-Force Wristbands for a Wearable Health Device." BYU ScholarsArchive, 2021. https://scholarsarchive.byu.edu/etd/9166.
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Wearable Health Devices (WHDs) are an emerging technology that enables continuous monitoring of vital signs during daily life. Issues with constant and consistent data acquisition have been found while WHD technology has developed. The force of the measurement area and movement of the sensors are key mechanical issues that need to be solved for WHDs to become a viable way to continuously monitor health conditions. This work explores Constant-Force Mechanisms (CFMs) as a solution to problems the current WHD industry faces. Additionally, the relationship between force provided from the mechanism, sensor pressure on the wrist, patient comfort, and sensor readings quality are explored and analyzed. Design requirements for a constant-force wristband were narrowed down to seven critical requirements (mechanism size vs. allowable travel, ability to be used on a curved surface, works well with existing clasps, ease of assembly, direction of travel, material, and force generation). These key requirements need to be considered for a WHD with an integrated CFM to be designed successfully. Two main concepts (buckling beams and tape springs) were prototyped and evaluated against the seven key requirements. The design and testing of a wrist worn sensing band used to gather relationship data among band tension, sensor pressure, patient comfort, and pulsatile signal quality is also presented. Human subject testing (IRB2020-268) was performed on a wristband with an integrated CFM and the wrist worn sensing band that were developed. The band with an integrated CFM compared pressure on the wrist for both a band with and without an integrated CFM for eight different movement activities. On average the band with the integrated CFM had a lower coefficient of variation for all except one of the activities. The data collected from the wrist worn sensing band shows that tension varies linearly with pressure, and that the pressure vs. tension slope increases with increasing wrist width. There also exists a linear relationship between tension and patient pain/comfort, but pressure does not show an effect on the patient discomfort or pain experienced. Signal quality when measured in the range of of 0-4 N and 0-20 kPa does not have a direct correlation to either tension or pressure.
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Meaders, John C. "An optimization-based framework for designing robust cam-based constant-force compliant mechanisms /." Diss., CLICK HERE for online access, 2008. http://contentdm.lib.byu.edu/ETD/image/etd2412.pdf.
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Meaders, John Christian. "An Optimization-Based Framework for Designing Robust Cam-Based Constant-Force Compliant Mechanisms." BYU ScholarsArchive, 2008. https://scholarsarchive.byu.edu/etd/1423.
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Constant-force mechanisms are mechanical devices that provide a near-constant output force over a prescribed deflection range. This thesis develops various optimization-based methods for designing robust constant-force mechanisms. The configuration of the mechanisms that are the focus of this research comprises a cam and a compliant spring fixed at one end while making contact with the cam at the other end. This configuration has proven to be an innovative solution in several applications because of its simplicity in manufacturing and operation. In this work, several methods are introduced to design these mechanisms, and reduce the sensitivity of these mechanisms to manufacturing uncertainties and frictional effects. The mechanism's sensitivity to these factors is critical in small scale applications where manufacturing variations can be large relative to overall dimensions, and frictional forces can be large relative to the output force. The methods in this work are demonstrated on a small scale electrical contact on the order of millimeters in size. The method identifies a design whose output force is 98.20% constant over its operational deflection range. When this design is analyzed using a Monte Carlo simulation the standard deviation in constant force performance is 0.76%. When compared to a benchmark design from earlier research, this represents a 34% increase in constant-force performance, and a reduction from 1.68% in the standard deviation of performance. When this new optimal design is evaluated to reduce frictional effects a design is identifed that shows a 36% reduction in frictional energy loss while giving up, however, 18.63% in constant force.
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Visner, John C. "Analytical and Experimental Analysis of the Large Deflection of a Cantilever Beam Subjected to a Constant, Concentrated Force, with a Constant Angle, Applied at the Free End." University of Akron / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=akron1196090494.
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Boyle, Cameron. "A Closed-Form Dynamic Model of the Compliant Constant-Force Mechanism Using the Pseudo-Rigid-Body Model." BYU ScholarsArchive, 2003. https://scholarsarchive.byu.edu/etd/53.
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A mathematical dynamic model is derived for the compliant constant-force mechanism, based on the pseudo-rigid-body model simplification of the device. The compliant constant-force mechanism is a slider mechanism incorporating large-deflection beams, which outputs near-constant-force across the range of its designed deflection. The equation of motion is successfully validated with empirical data from five separate mechanisms, comprising two configurations of compliant constant-force mechanism. The dynamic model is cast in generalized form to represent all possible configurations of compliant constant-force mechanism. Deriving the dynamic equation from the pseudo-rigid-body model is useful because every configuration is represented by the same model, so a separate treatment is not required for each configuration. An unexpected dynamic trait of the constant-force mechanism is discovered: there exists a range of frequencies for which the output force of the mechanism accords nearer to constant-force than does the output force at static levels.
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O'Connor, Kathleen Marie. "The Effects of Constant, Force-Drop and Variable Duration Training on Increasing the Useful Field of View." TopSCHOLAR®, 1991. http://digitalcommons.wku.edu/theses/1789.
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The Useful Field of View (UFOV) is the entire area in which information can be gathered without moving the head or eyes. It is generally found that the size of the UFOV shrinks with age. Additionally, research has shown that simple practice on the UFOV task can increase the size of the UFOV. However, simple practice may not be the most effective strategy for increasing the UFOV. The present study examined whether training directed toward a specific basis of UFOV loss (slower speed of processing) is more effective than simple practice at increasing field size.
Individuals received one or three types of training. Individuals who received variable duration training first performed the UFOV task at a pre-determined duration. Every time the individual obtained a field size of 30 degrees or greater across 2 consecutive blocks of trials, the duration of the visual display was decreased 25 milliseconds. Individuals who received force-drop training also initially performed the UFOV task at a pre-determined duration. On the third day of training, the duration of the visual display was decreased 25 milliseconds regardless of the individual’s performance. On the fifth day of training, the duration of the visual display was again decreased 25 milliseconds regardless of the individual’s performance. Individuals receiving constant training simply practiced the task at the pre-determined duration across all days of training.
Consistent with past research, training improved peripheral localization performance. Further, improvement in peripheral localization performance was greatest in the distractor condition among individuals receiving variable duration training. Variable duration training may be a more effective strategy for increasing the UFOV due to its challenging nature. Specifically, since the duration of the visual display is directly linked to the individual’s own performance, motivation and interest in the training task may be maintained for a longer period of time. Further, the heightened motivation and interest may facilitate a greater degree of learning in the training setting which in turn influences the amount of training that will be retained and utilized in real-world settings.
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Sarangapani, Krishna Kumar. "Characterizing selectin-ligand bonds using atomic force microscopy (AFM)." Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/11650.
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The human body is an intricate network of many highly regulated biochemical processes and cell adhesion is one of them. Cell adhesion is mediated by specific interactions between molecules on apposing cell surfaces and is critical to many physiological and pathological processes like inflammation and cancer metastasis. During inflammation, blood-borne circulating leukocytes regularly stick to and roll on the vessel walls, which consist in part, adhesive contacts mediated by the selectin family of adhesion receptors (P-, E- and L-selectin). This is the beginning of a multi-step cascade that ultimately leads to leukocyte recruitment in areas of injury or infection.
In vivo, selectin-mediated interactions take place in a hydrodynamic milieu and hence, it becomes imperative to study these interactions under very similar conditions in vitro. The goal of this project was to characterize the kinetic and mechanical properties of selectin interactions with different physiologically relevant ligands and selectin-specific monoclonal antibodies (mAbs) under a mechanically stressful milieu, using atomic force microscopy (AFM).
Elasticity studies revealed that bulk of the complex compliance came from the selectins, with the ligands or mAbs acting as relatively stiffer components in the stretch experiments. Furthermore, molecular elasticity was inversely related to selectin length with the Consensus Repeats (CRs) behaving as Hookean springs in series. Besides, monomeric vs. dimeric interactions could be clearly distinguished from the elasticity measurements. L-selectin dissociation studies with P-selectin Glycoprotein Ligand 1 (PSGL-1) and Endoglycan revealed that catch bonds operated at low forces while slip bonds were observed at higher forces. These results were consistent with previous P-selectin studies and suggested that catch bonds could contribute to the shear threshold for L-selectin-mediated rolling By contrast, only slip bonds were observed for L-selectin-antibody interactions, suggesting that catch bonds could be a common characteristic of selectin-ligand interactions. Force History studies revealed that off-rates of L-selectin-sPSGL-1 (or 2-GSP-6) interactions were not just dependent on applied force, as has been widely accepted but in fact, depended on the entire history of force application, thus providing a new paradigm for how force could regulate bio-molecular interactions.
Characterizing selectin-ligand interactions at the molecular level, devoid of cellular contributions, is essential in understanding the role played by molecular properties in leukocyte adhesion kinetics. In this aspect, data obtained from this project will not only add to the existing body of knowledge but also provide new insights into mechanisms by which selectins initiate leukocyte adhesion in shear.
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Chen, Xi Gang. "Design and analysis of a new parallel micro-manipulator utilizing bridge amplifier structure and constant force mechanism for precise assembly system." Thesis, University of Macau, 2018. http://umaclib3.umac.mo/record=b3948884.
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Ward, Christopher W. "The role of the apparent rate constant of cross-bridge transition from the strong binding state (ga̳p̳p̳) in skeletal muscle force production /." This resource online, 1996. http://scholar.lib.vt.edu/theses/available/etd-06062008-151126/.
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Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1996.On t.p. "a̳p̳p̳" is subscript. Vita. Abstract. Includes bibliographical references (leaves 76-80). Also available via the Internet.
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Ward, Christopher W. "The role of the apparent rate constant of cross-bridge transition from the strong binding state (G app ) in skeletal muscle force production." Diss., Virginia Tech, 1996. http://hdl.handle.net/10919/37983.
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Force regulation at the level of the actin-myosin cross-bridge (XB) can be
described by a 2 state model in which the XB's cycle between a strongly bound (SB), force
generating state and a weakly bound (WB), non-force generating state. This cycle can be
characterized by the apparent rate constants for transition into the SB state (fapp) and
returning to the WB state (gapp), Increases in XB force can be accounted for by an increase
in fapp a decrease in gapp., or both. While effort towards understanding XB force regulation
has focused on the notion that force production is primarily regulated by fapp the purpose
of this investigation was to determine if gapp continues to force regulation at the XB and
to determine whether gapp differs in,muscles with differing contractile characteristics.Ph. D.
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Esteban, i. Ferrer Daniel. "Electric polarization properties of single bacteria measured with electrostatic force microscopy. Theoretical and practical studies of Dielectric constant of single bacteria and smaller elements." Doctoral thesis, Universitat de Barcelona, 2014. http://hdl.handle.net/10803/284622.
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The present thesis is included in the field of nanobioelectricity. That is, understanding the electrical properties of biological specimens at the nanoscale (< 200 nm).
To do so we used an electrical variation of the Atomic Force Microscope called Electrostatic Force Microscope (EFM). By the application of a novel methodology (experimental and theoretical) we were able to obtain electrical polarization properties of single bacteria.
Firstly the methodology was applied to calibration samples were the dielectric constant was already known. The obtained value for a silicon nitride sample was 7.6 and the nominal value for this material is 6-8 (depending on stoichometry). Also a silicon oxide sample was studied obtaining a dielectric constant of 3.9 while the nominal value is 4. Both calculations validate the used methodology.
Moving to bacteria we found that the effective dielectric constant, for the four bacterial types investigated (Salmonella typhimurium, Escherchia coli, Lactobacilus sakei, and Listeria innocua) is around 3-5 under dry air conditions. Under ambient humidity, it increases to 6-7 for the Gram-negative bacterial types (S. typhimurium and E. coli) and to 15-20 for the Gram-positive ones (L. sakei and L. innocua). We show that the measured effective dielectric constants can be consistently interpreted in terms of the electric polarization properties of the biochemical components of the bacterial cell compartments and of their hydration state. These results demonstrate the potential of electrical studies of single bacterial cells.
Finally a comparison of these results with smaller ones (namely nanoparticles and viruses) was performed in the theoretical side obtaining that the geometrical factors of the sample have a larger influence in the small objects. Also it was concluded that while there exist some analytical approximations to work with them, these are not applicable to larger objects like bacteria.
This work confirms that dielectric measurements of single bacterial cells can be correlated with the electric polarization response of their biochemical constituents and their internal structure, thus opening interesting possibilities for analytical studies based on the biological electric polarization properties (also with smaller biological entities).La present tesi està inclosa en l'àmbit de la nanobioelectricitat. És a dir, la comprensió de les propietats elèctriques de les mostres biològiques a escala nanomètrica (< 200 nm ). Per a això es va utilitzar una variant elèctrica del Microscopi de Força Atòmica (AFM) anomenat Microscopi de Força Electrostàtica (EFM). Mitjançant l'aplicació d'una metodologia nova (experimental i teòrica) hem estat capaços d'obtenir propietats de polarització elèctrica de bacteris individuals. En primer lloc es va aplicar la metodologia a certes mostres de calibratge amb constant dielèctrica ja conegudes. El valor obtingut per a una mostra de nitrur de silici va ser de 8.2 i el valor nominal d'aquest material és de 7-8 (depenent de la estoicometria). Passant als bacteris, es va trobar que la constant dielèctrica efectiva, per als quatre tipus de bacteris investigats (Salmonella typhimurium, Escherichia coli, Lactobacilus sakei, i Listeria innocua) és al voltant de 3-5 en condicions d'aire sec. En virtut de la humitat ambiental, aquesta augmenta a 6-7 per als tipus de bacteris Gram-negatius (S. typhimurium i E. coli) i a 15-20 per als Gram-positius (L. sakei i L. innocua). Es demostra que les constants dielèctriques eficaces mesurades poden ser interpretades consistentment en termes de les propietats de polarització elèctriques dels components bioquímics dels compartiments cèl•lulars i del seu estat d'hidratació. Finalment una comparació d'aquests resultats amb objectes més petits (és a dir, nanopartícules i virus) en el seu aspecte teòric va concloure que els factors geomètrics de la mostra tenen una major influència en els objectes petits. També es va concloure que, si bé hi ha algunes aproximacions analítiques per treballar amb ells, aquestes no són aplicables a objectes més grans, com ara els bacteris. Aquest treball confirma que les mesures dielèctriques de cèl•lules bacterianes individuals es poden correlacionar amb la resposta de polarització elèctrica dels seus constituents bioquímics i la seva estructura interna, obrint així possibilitats interessants per als estudis analítics sobre la base de les propietats biològiques de polarització elèctrica (cosa també certa en entitats biològiques més petites).
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Meurk, Anders. "Force measurements using scanning probe microscopy : Applications to advanced powder processing." Doctoral thesis, Stockholm, 2000. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3023.
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Letellier, Richard. "Interpretation des modes vibrationnels des nucleosides entrant dans la constitution d'un adn." Paris 6, 1987. http://www.theses.fr/1987PA066131.
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Obtention d'un champ de force pour les nucleosides constitutifs de l'adn. Predictions sur l'evolution des spectres raman relatives au residu adenosine. A l'aide d'un calcul phenomenologique base sur la methode gf de wilson, il est rendu compte des modes vibrationnels des quatre nucleosides de l'adn
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Wattez, Thomas. "Détermination sous champ électrique du coefficient de diffusion effectif de l'eau au sein d'un matériau à base de liant hydraulique." Thesis, Toulouse, INSA, 2013. http://www.theses.fr/2013ISAT0032/document.
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La sûreté du stockage des déchets radioactifs repose en grande partie sur la capacité de confinement du conteneur et de l’ouvrage qui lui sont dédiés. Dans le cas des déchets radioactifs de Faible et Moyenne Activité à Vie Courte (FMA-VC), cette propriété de confinement, assurée par des matrices solides à base de matériaux cimentaires, est mesurée sur la base d’un essai de diffusion naturelle, consistant à faire traverser un traceur, de type radioactif, dans un échantillon représentatif, duquel on retire, a posteriori, un coefficient de diffusion. L’évolution de ces matériaux et les améliorations apportées à la fabrication de nouvelles enveloppes de confinement induisent des durées d’essai pouvant atteindre plusieurs années.L’objectif premier de ce travail consiste en la détermination du coefficient de diffusion effectif d’une espèce de référence, qui sera dans notre cas l’eau tritiée, dans un intervalle de temps réduit. L’approche théorique repose sur la compréhension du phénomène de transport d’espèces ioniques en solution soumises à un champ électrique. Sur les bases d’un protocole expérimental clairement établi et de la définition du facteur de formation, caractéristique topologique intrinsèque du réseau poreux, il a été possible de déterminer le coefficient de diffusion effectif de l’eau tritiée d’une gamme de bétons et de mortier d’intérêt, et cela en seulement quelques heures.Dans un second temps, la comparaison de l’essai de migration sous champ électrique constant, développé dans ce travail, avec l’essai classique de diffusion naturelle à l’eau tritiée a mis en exergue deux points cruciaux. La non-prise en compte de la décroissance radioactive du tritium dans l’interprétation de l’essai de diffusion naturelle à l’eau tritiée amène une sous-estimation non-négligeable de la valeur du coefficient de diffusion. La conservation, lors de leur phase de maturation, des matériaux d’essais dans des conditions inadaptées, induit des mesures selon la technique de migration sous champ électrique constant disparates et non répétables.Dans un dernier temps, la validation complète de la technique électrocinétique, sujet initial de ce travail, repose sur la vérification des hypothèses théoriques énoncées au préalable. Le facteur de formation, et a fortiori le coefficient de diffusion effectif, est une grandeur indépendante de la force ionique de la solution porale du matériau considéré, cela pour une gamme de solution courante dans le domaine des matériaux cimentaires. Le facteur de formation s’avère aussi indépendant de l’amplitude du champ électrique appliqué, aussi pour une gamme et des durées d’essai adaptées aux conditions de mesures définies dans le protocole. Enfin, lorsque les valeurs de coefficients de diffusion effectifs obtenues en migration et diffusion naturelle à l’eau tritiée sont comparées sur plusieurs formulations maîtrisées de matériaux cimentairesThe safety and the reliability of a radioactive waste repository rely essentially on the confinement ability of the waste package and the storing structure. In the case of the low-level and intermediate level short-lived radioactive waste, the confinement property, relying on solid matrices made of cement-based materials, is assessed through a natural diffusion test, using a radioactive tracer, from which an effective diffusion coefficient is deduced. The evolution of the materials and more particularly the enhancement of the confinement properties of cement-based materials lead to test duration from a couple of months to a couple of years.The main objective of the present work involves the determination of the effective diffusion coefficient of reference chemical species, in our case the tritiated water, within a shorter time. The theoretical foundation is based on the description of ionic species mass transfer under the effects of an electrical field. With the definitions of a precise experimental protocol and of a formation factor, considered as an intrinsic topological feature of the porous network, it is possible to determine the effective diffusion coefficient of tritiated water for various types of concretes and mortars, and this within a few hours only.The comparison between the developed accelerated test, based on the application of a constant electrical field, and the normed natural diffusion test, using tritiated water, underlined two critical issues. First, omitting the impact of the radioactive decay of tritium during a natural diffusion test, leads to a non-negligible underestimation of the effective diffusion coefficient. Second, maintaining samples in high relative humidity conditions after casting is essential in order to avoid contrasted and unrelated results when performing the electrokinetic tests.Eventually, the validation of the electrokinetics technique, main objective of this work, rests on the assessment of the theoretical hypothesis previously formulated. The formation factor, as well as the effective diffusion coefficient, does not depend on the ionic strength of the material pore solution, this being validated for solutions of different composition encompassing the cement materials pore solution diversity. The formation factor also does not vary when the amplitude of the applied electrical field varies, provided both the test duration and the electrical field amplitude are kept within acceptable boundaries. Finally, the comparison between the values of the effective diffusion coefficient obtained with both the constant field migration test and the natural diffusion techniques, for perfectly conditioned and prepared materials, leads us to invalidate the assumption that the effects of the double electrical layer are negligible
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Callergård, Robert. "An Essay on Thomas Reid´s Philosophy of Science." Doctoral thesis, Stockholms universitet, Filosofiska institutionen, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-1006.
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Though generally recognized as a formative force in his philosophy, Thomas Reid’s Newtonianism and his philosophy of science has not received due attention among scholars. My aim is to inaugurate a detailed survey. In ch. 1 it is shown that Reid demarcates physics as against metaphysics and theology, making his brand of Newtonianism different from first generation moral and religious Newtonianism. In ch. 2 it is argued that "Newtonian" is not an apt label on Reid’s call for a Science of the human mind. Neither his practice within the field, nor his methodological views, make lawlike connections the central kind of truth to be discovered. Ch. 3 is devoted to Reid’s account of the 1st and 2nd of Newton’s Regulae Philosophandi, and an ensuing notion of explanation which approaches the deductive-nomological model. It is shown that Reid’s account is very much his own, though presented as an explication of Newton’s intentions. Reid’s dismissive view towards simplicity as a guide in scientific reasoning leans on Bacon’s theory of idols and Reid’s theory of first principles of common sense. Ch 4 concerns hypotheses in connection with Newton’s phrase Hypotheses non fingo. It is argued that Reid does not mind speculation about unobservable or theoretical entities, and that his objections to particular ether theories are scientific rather than principled. Nonetheless, since Reid does not explain the difference between powerful conjecture and established truth, his notion of scientific reasoning remains elusive. Ch 5 concerns Reid’s views on the concept and ontology of forces of attraction. It is argued that Reid takes forces to be physical entities open for empirical enquiry, and that forces are neither active, nor efficient. Finally, Reid’s view of metaphysics is considered, and further differences with early Newtonians emphasised.
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Baumgärtel, C., and Martin Tajmar. "The Planck Constant and the Origin of Mass due to a Higher Order Casimir Effect." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2018. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-237708.
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The Planck constant is one of the most important constants in nature, as it describes the world governed by quantum mechanics. However, it cannot be derived from other natural constants. We present a model from which it is possible to derive this constant without any free parameters. This is done utilizing the force between two oscillating electric dipoles described by an extension of Weber electrodynamics, based on a gravitational model by Assis. This leads not only to gravitational forces between the particles but also to a newly found Casimir-type attraction. We can use these forces to calculate the maximum point mass of this model which is equal to the Planck mass and derive the quantum of action. The result hints to a connection of quantum effects like the Casimir force and the Planck constant with gravitational ones and the origin of mass itself.
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Pachon-Rodriguez, Edgar-Alejandro. "Étude de l’influence de la dissolution sous contrainte sur les propriétés mécaniques des solides : fluage du plâtre." Thesis, Lyon 1, 2011. http://www.theses.fr/2011LYO10284/document.
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L’importante augmentation de fluage des plaques de plâtre en milieu humide est un vieux problème dans l’industrie du bâtiment, dont l’origine n’est pas encore établie. Afin d’en comprendre le mécanisme une étude à trois échelles (macro : réponse mécanique, micro : cinétique de dissolution et nano : observation atomique) a été réalisée. Une corrélation forte existe entre le fluage du plâtre en immersion et la cinétique de dissolution du gypse. La concordance de cette corrélation avec une loi de déformation par dissolution sous contrainte, très utilisés en géologie, permet de proposer la dissolution sous contrainte comme un des mécanismes responsables du fluage du plâtre en immersion. L’évolution de la topographie de la surface du cristal de gypse immergé dans une solution aqueuse de gypse est observée par microscopie à force atomique (AFM). La cinétique de migration des marches atomiques est très dépendante de la sous-saturation de la solution, de la force d’appui de la pointe de l’AFM ainsi que des additifs utilisés. L’étude de l’influence de la force d’appui sur les vitesses des marches met en évidence la présence de deux mécanismes complètement différents. A fortes forces (> 15 nN) on observe un mécanisme d’usure de la surface, tandis qu’à faibles forces (< 10 nN) le mécanisme observé semble être la dissolution sous contrainte. L’évolution des vitesses des marches atomiques avec la force appliquée par la pointe est concordante avec une loi connue de dissolution sous contrainteThe huge enhancement of the creep of plasterboard by humid environments is an old problem in the building industry, but its origin remains unknown. To understand this mechanism a three scales study (macro : mechanical behavior, micro : dissolution kinetics, nano : atomic observation) has been done. There is a strong correlation between wet plaster creep and gypsum dissolution kinetics. The concordance between this correlation and the law of deformation by pressure solution, well-known in geology, permits to propose pressure solution as one of the mechanisms responsible of wet plaster creep. The topological evolution of the cleaved surface of a gypsum single crystal during its dissolution in a flowing under-saturated aqueous solution has been observed with an atomic force microscope. The kinetics of step migration strongly depends on the saturation state of the solution, the force applied by the tip on the surface, as well as the used additives. The study of the influence of the force applied by the tip on the step velocity evidence two different dissolution enhancement regimes. At high forces (> 15 nN) a corrosive wear behavior is observed, while at low forces (< 10 nN) pressure solution is the observed mechanism. The step velocity evolution with the force obeys the known kinetic law of pressure solution
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Neves, Katy Andrews. "Achilles Tendon Changes in Downhill, Level and Uphill Running." BYU ScholarsArchive, 2014. https://scholarsarchive.byu.edu/etd/4399.
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In this study, we examined how hill running affects the Achilles tendon, which is a common location for injuries in runners. Twenty females ran for 10 min on three randomly selected grades (-6%, 0%, +6%). Achilles tendon (AT) cross-sectional area (CSA) was imaged using Doppler ultrasound and peak vertical forces were analyzed using high-speed (240 Hz) videography. A metabolic cart and gas analyzer ensured a similar metabolic cost across grades. Data were analyzed using a forward selection regression. Results showed a decrease in AT CSA from pre-run to post-run (p = .0001). Peak vertical forces were different across grades (p = .0001) with the largest occurring during downhill running and smallest during uphill running. The results suggest that the Achilles tendon is affected by running and a decrease in CSA appears to be a normal response. The AT CSA does not differ between grade conditions when metabolic cost of running is matched, suggesting an adaptive effect of the AT. Coaches and athletes can use this knowledge to develop workout protocols that transition runners to downhill running and allow them to adapt to these greater forces.
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Ječmínka, Marek. "Využitelnost protlačovacích zkoušek na miniaturních discích (small punch test - SPT) pro stanovování materiálových charakteristik za vysokých teplot." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-230952.
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Diploma thesis is focused on mechanical properties testing by small punch test and comparison of these properties with mechanical properties obtained by conventional tensile test. Steels P92 and AISI 316L in a shape of discs were tested. There were determined values of mechanical properties, namely yield stress, and ultimate tensile stress, obtained by the small punch test – constant deflection rate in this thesis. Values of initial stress and residual stress were evaluated from relaxation small punch test. Mechanical properties obtained by small punch test – constant deflection rate, and small punch test – relaxation, respectively, are compared with mechanical properties obtained by conventional tensile test, and relaxation tensile test, respectively. There were proposed own empirical relationships for restatement of mechanical properties obtained by small punch test to mechanical properties obtained by conventional tensile test in the thesis. Relatively small agreement of results obtained by small punch test, and conventional tensile test was demonstrated by a comparison. Application of own empirical relationships resulted in better agreement. Very good agreement of results of small punch test – relaxation, and relaxation tensile test was shown by their comparison.
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Kaspryzk, Marie. "Strategically minded dynamic analysis of strategic flight bat maneuvers." Honors in the Major Thesis, University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETH/id/864.
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CATD was not only adequate for analyzing the pursuit of erratically moving prey but also worked well when analyzing the pursuit of prey that remained stationary. It cannot be fully concluded that bats utilize the CATD strategy to successfully capture erratically flying prey. The angle remains relatively constant but does not exhibit a zero change in angle as by definition. The large forces experienced by the bat were seen when the bat began to rotate its body about its pitch axis or when the bat made a large turn. Moments were seen specifically when the bat began to bank into its last and final turn towards its target.; Digital recordings of three different species of bats were studied in this thesis to determine the forces and moments that were experienced throughout the bat's flight. The recordings were also studied to determine the pursuit strategies that were most effective for the bat to quickly capture its prey. A pursuit strategy is a strategic way to travel that will allow a pursuer to capture/approach their target the quickest. Therefore when a bat utilizes a particular pursuit strategy, it will adjust its position/ direction vector in a particular way that will allow it to approach its target very quickly. Data was collected directly from the video by manual collection utilizing Microsoft Visual Studio to extract frames, collect and record the data. This research was conducted to determine when throughout the flight the bat would experience significant forces and moments. The location and magnitude of the forces were reported along with an explanation of why the bat was experiencing a peak at each specific time. The forces and moments that the bat experienced thought-out the flight pursuit were calculated by relative velocity and acceleration calculations. In all four scenarios the bat experienced forces in relation to rotating its body about its center of mass. Forces were specifically seen when the bat periodically began to rotate its body before the final plunge to capture its prey. Prey avoidance and pursuit strategies were also studied and observed in this thesis which included the constant bearing and the constant absolute target direction. The intent was to determine which pursuit strategy bats use to quickly capture their prey. The constant bearing strategy is utilized to pursue prey moving along a smooth path, on the other hand the Constant Absolute Target Direction (CATD) pursuit strategy is utilized to capture erratically moving prey. For most of the bats analyzed, it was seen that the CATD strategy proved to be the preferred pursuit strategy.B.S.M.E.
Bachelors
Mechanical, Material and Aerospace Engineering
Engineering and Computer Science
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Polesel, Jérôme. "Modélisations et Expérimentations en Microscopie à Force Atomique Dynamique en Ultra Vide." Phd thesis, Université Paul Sabatier - Toulouse III, 2005. http://tel.archives-ouvertes.fr/tel-00009666.
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La microscopie à force atomique (AFM) dynamique est née il y a maintenant presque quinze ans (Albrecht, 1991). Depuis la première image en résolution atomique (F. J. Giessibl, 1995), les avancées de cette technique de champ proche permettent aujourd'hui de manipuler des atomes à température ambiante (Oyabu, 2005) sur des surfaces conductrices ou isolantes. La compréhension du fonctionnement de cette machine complexe et l'optimisation des réglages des nombreux asservissements est un des objectifs de ce travail de thèse. A cette fin, un formalisme analytique provenant des méthodes de l'Automatique non linéaire (J. Ch. Gille, 1956) sera introduit pour traiter de façon naturelle les blocs de régulation de la machine mais aussi pour traiter l'interaction pointe-surface comme une fonction de transfert. Un outil numérique de simulation confirmera notre approche théorique. Dans un deuxième temps, le rôle capital de la sonde et sa caractérisation seront traités à travers une méthode expérimentale simple et originale. Cette méthode se base sur l'étude des changements des propriétés de résonance de la sonde oscillante sur des surfaces isolantes et conductrices. Les forces conservatives à longue portée du type électrostatique et van der Waals seront quantifiées. Les forces à courte portée essentiellement chimiques seront mises en évidence en mesurant la dissipation de la sonde oscillante en fonction de sa distance avec la surface. Nous finirons cette étude en montrant expérimentalement, sur un sytème MoS2/îlots d'or/molécules d'octanedithiol, la grande versatilité de ce microscope. En effet, cet appareil d'observation par sa complexité apparente laisse beaucoup de degrés de liberté à l'utilisateur pour aborder l'étude d'un tel système physicochimique. Des perspectives seront données pour améliorer la stabilité et le pouvoir de résolution des pointes qui permettraient de rendre pérenne cette technique de champ proche.
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Zerweck-Trogisch, Ulrich. "Auflösungsvermögen und Genauigkeit der Kelvinsonden-Rasterkraftmikroskopie und deren Anwendung an molekularen Systemen." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2007. http://nbn-resolving.de/urn:nbn:de:swb:14-1196782873906-79057.
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Die Arbeit befasst sich mit der Erforschung und Anwendung der Kelvinsonden-Rasterkraftmikroskopie. Die Technik wird bezüglich der Quantität der gemessenen Werte und der erzielbaren lateralen Auflösung untersucht und auf diverse Probensysteme angewandt. Die so erhaltenen nanoskopischen Werte werden mit markoskopischen Messergebnissen verglichen. Sowohl die elektrostatische Kraft zwischen der Messspitze und der Probenoberfläche als auch deren Gradienten können zur Minimierung der elektrostatischen Wechselwirkung herangezogen werden. Die Detektion des Kraftgradienten zum Aufbau eines Regelkreises erweist sich gegenüber der Kraftdetektion überlegen. Die experimentell ermittelten Befunde werden durch eine Rechnersimulation bestätigt. Diese zeigt die Möglichkeit von quantitativen Ergebnissen für laterale Objektgrößen im Bereich von einigen Nanometern. Im Experiment kann dies gezeigt werden. Es folgt die Anwendung der Kelvinsonden-Rasterkraftmikroskopie: Nanoskopisch ermittelte Werte der Austrittsarbeitsänderung von Metalleinkristall-Oberflächen durch die Adsorption von C_60 entsprechen Literaturwerten, die mit makroskopisch messenden Methoden ermittelt wurden. Sich zeitlich ändernde Oberflächenpotentiale von einer organischen Solarzelle und von lateral unterschiedlich dotiertem Silizium lassen sich quantitativ messen. Der sich bei der Adsorption von Oktadezyl-Phosphonsäure auf Glimmer und Graphit bildende elektrostatische Dipol wird untersucht und abgebildet. Das Wachstumsverhalten und die Austrittsarbeit der organischen Moleküle PTCDA und Alq_3 auf den teilweise mit KBr bedeckten Metallsubstraten Au und Ag wird untersucht. Schlussendlich wird gezeigt, dass mit der Kelvinsonden-Rasterkraftmikroskopie sogar der molekülinterne Dipol der vier Butyl-Gruppen von Tetra-3,5-di-ter-butyl-phenyl-Porphyrinen aufgelöst werden kann.
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Chater, Rabah. "Etude des antimonites MeSb 2 O 4 à basse température : évolution structurale, thermodynamique, propriétés élastiques et magnétiques anisotropes ; modélisation." Paris 6, 1986. http://www.theses.fr/1986PA066219.
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Etude par diffraction des RX et de neutrons, spectroscopie Raman et IR, chaleur massique, susceptibilité magnétique des antimonites (MNNifezn)sb2o4. Interprétation quantitative des anomalies de dilatation liées à Tltn dans le cas des composés de Ma et Fe. Définition d'un champ de force cohérent avec un potentiel de paires simplifié.
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Rannou, Isabelle. "Etudes sous pression de la transition de phase interpolytypique du sulfure de gallium." Paris 6, 1986. http://www.theses.fr/1986PA066063.
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Etude entre 0 et dollar GPA, permettant de mettre en évidence une transition de basse pression à 1,6 GPA; mesures de l'absorption optique et de l'indice de réfraction, de la diffusion Raman et de la diffusion Brillouin; analyse des variations a la transition. Description satisfaisante des variations des modes de vibration au moyen d'un modèle de dynamique réticulaire a forces centrales.
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Wallqvist, Viveca. "Interactions between non-polar surfaces in water: Fokus on talc, pitch and surface roughness effects." Doctoral thesis, KTH, Ytkemi, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-10283.
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The aim of this thesis work was to gain understanding of the interactions between talc mineral and surfaces, liquids and chemicals relevant for industrial applications, such as pulp and paper. Talc is used in the pulp and paper industry as a filler pigment, in control of pitch (lipophilic extractives) deposits and as a coating pigment. A deeper understanding of talc interactions will be beneficial in optimizing its use. Long-range attractive interactions between talc and hydrophobic model probes, as well as pitch probes, have been measured using the atomic force microscope (AFM) colloidal probe method. Two procedures for preparation of pitch colloidal probes were developed to allow these studies. Model hydrophobic, nanorough surfaces with surface energy characteristics similar to talc have also been prepared and their interactions with hydrophobic model probes compared to interactions between hydrophobic model probes and talc. It is demonstrated that talc mineral interacts with model hydrophobic particles, as well as with pitch, by long-range attractive forces, considerably stronger than the expected van der Waals force. The possible origin of the measured interaction forces is discussed, and the conclusion is that the main cause is an attractive capillary force due to formation of a gas/vapor capillary between the surfaces. Force measurements using model hydrophobic, nanorough surfaces show that a large-scale waviness does not significantly influence the range and magnitude of the capillary attraction, but large local variations in these quantities are found. It is demonstrated that a large variation in adhesion force corresponds to a small variation in local contact angle of the capillaries at the surfaces. The nature of the surface topographical features influences the capillary attraction by affecting the local contact angle and by pinning of the three-phase contact line. The effect is clearly dependent on the size of the surface features and whether they exist in the form of crevices or as extending ridges. Entrapment of air also affects the imbibition of water in pressed talc tablets. The effects of wetting and dispersion agents on the interactions between talc and hydrophobic probes have also been investigated. It is demonstrated that a common dispersing agent used for talc, poly(acrylic acid), does not affect the capillary attraction between talc and non-polar probes. In fact, the results strongly suggest that poly(acrylic acid) does not adsorb on the basal plane of talc. From this finding it is inferred that the stabilizing effect of this additive most likely is due to adsorption to the edges of talc. In contrast, a wetting agent (the non-ionic triblock copolymer Pluronic PE6400) removes the long-range capillary attraction. It is suggested that such an ability to replace air at the talc surface is of great importance for an efficient wetting agent. The Hamaker constant for talc has also been estimated by using optical data obtained from spectroscopic ellipsometry. It is demonstrated that a nanocrystalline talc mineral, cut in different directions displays very small differences in Hamaker constant between the different crystallographic orientations, whereas a microcrystalline sample displays a significantly higher value. The estimated Hamaker constants are discussed for different material combinations of relevance for the pulp- and paper industry, such as cellulose and calcium carbonate.Målet med detta avhandlingsarbete var att öka förståelsen för interaktioner mellan talkmineral och ytor, vätskor och kemikalier relevanta för industriella applikationer, såsom papper och massa. Talk används i pappers- och massaindustrin som fyllmedel, för kontroll av hartsrika (lipofila extraktivämnen) avsättningar och som bestrykningspigment. En djupare förståelse för talkinteraktioner kommer att vara användbart för att optimera dess användning. Långväga attraktiva interaktioner mellan talk och hydrofoba modellpartiklar, såväl som mellan talk och hartspartiklar, har uppmätts med hjälp av atomkraftsmikroskopi (AFM) genom att fästa kolloidala partiklar på kraftsensorn. Två metoder för att framställa partiklar gjorda av harts har utvecklats för att möjliggöra dessa studier. Hydrofoba, nanostrukturerade modellytor med ytenergier liknande de för talk har också tillverkats och deras växelverkan med hydrofoba modellpartiklar har jämförts med dem mellan talk och hydrofoba modellpartiklar. Studierna visar att talkmineral växelverkar med hydrofoba modellpartiklar, såväl som med harts, genom långväga attraktiva krafter som är betydligt starkare än den förväntade van der Waals kraften. Möjliga orsaker till de uppmätta växelverkanskrafterna diskuteras och slutsatsen blir att huvudorsaken är en attraktiv kapillärkraft som uppkommer genom att en gas-/ångkapillär bildas mellan ytorna. Kraftmätningar gjorda med hydrofoba nanostrukturerade modellytor visar att en storskalig vågighet inte nämnvärt påverkar storleken av kapillärattraktionen, men stora lokala variationer existerar. Det demonstreras att en stor variation i adhesionskraft motsvaras av en liten variation i lokal kontaktvinkel för kapillärerna på ytorna. Ytornas topografi påverkar kapillärattraktionen genom att påverka den lokala kontaktvinkeln samt genom att trefaskontaktlinjen inte kan röra sig fritt över ytan. Effekten är tydligt beroende av huruvida ytojämnheterna existerar i form av nedsänkningar eller upphöjningar. Instängd luft påverkar också pressade talktabletters uppsugningsförmåga av vatten. Vätnings- och dispergeringsmedels inverkan på växelverkan mellan talk och hydrofoba partiklar har undersökts. Resultaten visar att ett vanligt dispergeringsmedel för talk, polyakrylsyra, inte påverkar kapillärattraktionen. I själva verket tyder data på att polyakrylsyra inte adsorberas på talks basalplan. Utifrån dessa resultat dras slutsatsen att polyakrylsyra stabiliserar talkdispersioner genom att adsorbera på talkkanterna. Ett vanligt vätmedel (nonjonisk triblock sampolymer Pluronic PE6400) tar å andra sidan bort långväga kapillärattraktion. Detta antyder att egenskapen att ersätta luft på talkytan är av stor betydelse för effektiva vätmedel. Hamakerkonstanten för talk har uppskattats genom att utnyttja optiska data från ellipsometrimätningar. Det demonstreras att ett nanokristallint talkmineral kapat i olika riktningar uppvisar mycket små skillnader i Hamakerkonstant mellan de olika kristallografiska orienteringarna, medan ett mikrokristallint prov uppvisar ett betydligt högre värde. De beräknade Hamakerkonstanterna diskuteras för olika materialkombinationer relevanta för pappersindustrin, såsom cellulosa och kalciumkarbonat.
QC 20100813
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Le, My-Thuong, and 唐立明. "Design A Constant force gripper." Thesis, 2019. http://ndltd.ncl.edu.tw/cgi-bin/gs32/gsweb.cgi/login?o=dnclcdr&s=id=%22107NCHU5693020%22.&searchmode=basic.
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碩士國立中興大學
精密工程學系所
107
Physical pick-and-place promises specificity, precision, and programmed motion, a feature making microrobotic manipulation amenable to automation for the construction of microsystems. Despite the significant progress made, a long-standing difficulty is the release of micro objects from the end effector due to strong adhesion forces at the micro scale and move to another location without damaging it. This research focuses on the development of microelectromechanical systems (MEMS) based microgrippers that integrate an active release mechanism for pick-and-release micromanipulation.
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汪益適. "Fuzzy control of constant turning force." Thesis, 1992. http://ndltd.ncl.edu.tw/handle/98851503069129490839.
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Lin, En Saint, and 林恩聖. "Fuzzy Control in Constant Turning Force." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/65914066880830726046.
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Huang, Jian-Jie, and 黃建偕. "Intelligent Constant Force Feedback Controller Design for Atomic Force Microscopes." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/14944971416743306773.
Full textAbstract:
碩士東南科技大學
電機工程研究所
97
This paper develops a constant force feedback mechanism based on fuzzy logic for a tapping mode Atomic Force Microscope. Then, a PID-like fuzzy controller is designed to overcome the shortcomings of a traditional PID controller in a tapping mode Atomic Force Microscope. By using the PID-like fuzzy controller, the cantilever tip can track the surface of the sample rapidly and accurately even though the topology of the surface is arbitrary and not given a priori. The rapid tracking response allows us to observe high aspect ratio micro structure accurately and quickly. The tip crash resulting from overshoot in commercial AFM with a traditional PID controller could be avoided. Additionally, continuous gain tuning in commercial AFMs to schedule the controller efforts is alleviated. In final, a computer simulation is provided to demonstrate the effectiveness and confirm validity of the proposed controller.
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Jung-YuanWang and 王俊元. "Design and Experiment of Constant-Force Grippers." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/14395135934897920840.
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碩士國立成功大學
機械工程學系碩博士班
101
This research presents the design, simulation, and experiment of compliant grippers that can provide a constant gripping force to handle objects of various stiffness and size. Maintaining a proper gripping force is a challenging task of grippers used for manipulating delicate objects with uncertain sizes and stiffnesses. To avoid damage and provide a stable grip of an object, force feedback is often required so that the gripping force can be directly or indirectly regulated. Without using additional sensors and control, the proposed grippers passively maintain a constant contact force between fingertip and an object given a pre-specified force magnitude. Two types of grippers are designed to generate a nearly constant contact force regardless of object stiffness and size. The first gripper consists of a symmetric flexible mechanism that can generate a constant torque regardless of input rotation. The constant torque is converted to a constant force through an adjustable lever arm and then transmitted to fingertips. The other is designed to have a constant input force generated by a constant-force mechanism. Transmitted through a statically balanced mechanism, a constant gripping force is obtained at the fingertip. After a formulation to find the optimal gripper shape, both designs are verified by comparing with simulation results. Prototypes are illustrated with experimental demonstrations. These novel grippers are expected to serve as a reliable alternative for object manipulation.
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Huang, Chun-Han, and 黃俊翰. "Intelligent Control of Constant Cutting Force in Lathe." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/31041405806787889924.
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碩士國立臺北科技大學
車輛工程系碩士班
92
Many vehicular components were manufactured by turning process in the lathe; such as clutche pads, braking disks, transmission shafts, etc. The cutting force is variable with respect to the cutting conditions variation in high speed turning process. If the cutting force is large, the tool will rapidly wear so that the tool life is reduced and increases the cost of the equipment. If the cutting force is small, the cutting time of the workpiece will increase and the efficiency of the turning process will also reduce. This work refits an old lathe and develops graphic interface controllers to control it under Windows 2000 operation system, for evaluating the system control performance. Since the constant cutting force control is one of choice for improving the tool life and increasing the efficiency of the turning process. However, the refitted old lathe is a nonlinear and complicated system. Its mathematical model is difficult to be established or estimated. Therefore, it is hard to design a model base controller based on traditional control theory for achieving the purpose of the constant force control in turning process. The intelligent control strategy development has a mode free feature; it very suits to be employed for controlling nonlinear and complex systems. Hence, this study proposed three intelligent control strategies: (1) fuzzy controller (FC) , (2) grey-prediction fuzzy controller (GPFC) and (3) self-organizing fuzzy controller (SOFC), to control individually the nonlinear with complicated refitted old lathe system and evaluates further between their control performances. Experimental results verified that the grey-prediction fuzzy and the self-organizing fuzzy controllers have better control performance than traditional fuzzy controller alone for the constant cutting force control in turning process; but the self-organizing fuzzy controller needs more computation consumption in learning process for constant cutting force control for achieving better control performance than traditional fuzzy controller or grey prediction fuzzy controller used.
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羅平讚. "The control of constant cutting force and force tracking of X-Y-Table." Thesis, 1992. http://ndltd.ncl.edu.tw/handle/48654358122697457389.
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Yu-LingKuo and 郭彧伶. "Design of a Force Regulation Mechanism with Two-Dimensional Adjustable Constant-Force Outputs." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/dwbbxa.
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Liao, Tzu-Ching, and 廖子慶. "Fabrication of a constant-force bistable micromechanism by electroforming." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/68328566570910967888.
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碩士國立中興大學
精密工程學系所
101
Fabrication of a constant-force bistable micromechanism by electroforming is studied in this thesis. Glass substrate is used in the process. A titanium layer is sputtered as the conductive layer, copper layer is used as a sacrificial layer and nickel is selected as the structural layer. We focus on process improvement. The roughness of copper plating surface is improved by changing the current density and plating bath formulations. Alpha step surface profiler is used to measure the roughness of copper plating surface. Based on measurement results experimental parameters are confirmed to improve the roughness of copper plating surface.
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Wei-hung, Weng, and 翁偉宏. "The Research of Constant Force on High Speed Milling Operation." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/77835061486653202539.
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碩士國立海洋大學
機械與輪機工程學系
88
In high-speed-milling process, big cutting force will cause the cutting tool wear, breakage, short life, and bad machining quality. To avoid such situation, a grey fuzzy controller is designed to attain constant cutting force control in this thesis. The difference between fuzzy and grey fuzzy control systems is that the grey fuzzy control is according to the future state, which is predicted by the grey model. Thus there will be the advantage of prior control. On the other hand, the cutting process is a non-linear process. For the purpose of constant cutting force control, the feedrate will not change in proportion to the cutting depth linearly, and the metal removal rate will also change in such various cutting conditions. The auxiliary metal removal rate controller design will compensate the reduced feedrate by increasing the spindle speed to reach the effect of constant metal removal rate. The models of surface roughness and cutting forces in the milling system are found by experiment, and are put into the controlled system to have the milling force control process approach the reality. The results show the grey fuzzy control system can maintain constant cutting force and metal removal rate at the same time in various cutting conditions.
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盧建禎. "The Study of Developing A Constant Grind-Polishing Force Controller." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/55283661178933440159.
Full textAbstract:
碩士國立海洋大學
機械與輪機工程學系
91
The purpose of study is to develop a control algorithm of constant grind-polishing force for a compliance device. Using the dynamic compliance coefficients , Kz and Kx, and the technique of grey-fuzzy control algorithm, the manufacturing goals can be achieved. In addition, a control strategy of constant depth of cut for the compliance device is built. The staying time algorithm for the cutting tools is thus developed. To meet the cutting performances, such as surface roughness flatness and uniform, the manufacturing strategies stated above can be selected separate. The simulation results show the grey-fuzzy control system designed for constant grind-polishing and constant depth of cut are quite well. Hence the machining strategies for constant grind-polishing and cutting tool stay time can be implemented adequately.
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Zhang, Dun Xin, and 張敦信. "Fuzzy grey adaptive control of constant force in cutting operations." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/85719515965821755384.
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Lin, Chih-Kuang, and 林志光. "Constant Milling Force in High Speed and Constant Metal Removal Rate Operation Via Grey Fuzzy Controller System." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/39531475562245340338.
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碩士大同工學院
機械工程學系
84
In this study, a grey fuzzy controller (GFC) is developed to implement constant metal removal rate (MRR) on the constant milling force (CMF) in highspeed. The controller can automatically adjust the spindle speed to maintain the MRR at the desired stable value. The desired quality of workpiece, such as surface roughness and milling force, is due to the optimal values come from theexperiments. The fuzzy control techniques and the grey theory are combined todevelop a grey fuzzy controller (GFC) to the constant milling operation. GreyGrey model is a good predictor with high accurate forecasting ability.Fuzzy controlis effective for the control system with uncertain plantparameters. For thecomplex phenomenon of the high speed machining process,a experiment methodis adopted to find the force model describing the milling behavior. In thisexperiment, responce surface methodology (RSM) was used. In order to get thebetter machining quality, surface roughness model (Ra) was also acquired. Themodel is acceptable due to the variance results. In the allowable surfaceroughness levels, the relations between feedrate and cutting depth are obtainedFinally, grey fuzzy control system was applied to achieve constant MRR and CMF operation. Simulation result show that GFC system can easily achieve the desiredMRR and constant milling force under vary cutting condition.
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Shih, Yu-Ting, and 施禹廷. "The Design of Translating Cam Mechanisms for Constant-force Clamping Device." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/14809413697091926010.
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碩士國立清華大學
動力機械工程學系
102
Accompanied by the development of the machine tool industry, there’s an ever-rising requirement of the manufacturing precision standard for products. Clamping devices for machine tools, as an indispensable part of manufacturing, have crucial influence on the upgrading of the entire industry.In order to provide magnified constant clamping force, this work proposes systematic processes to design a clamping device applied to machine vices mainly with the combination of translating cam and toggle mechanism. The cam profiles, pitch curves, and paths of cutter are derived and expressed parametrically firstly by designing and calculating with given parameters. After a study of relationships between design parameters, an analysis of mechanism errors in the output of the devise causing by clearance has been undertaken so that the characteristics, utilities, and usefulness of the mechanism can be assessed.By combining linkages with the translating cam clamping mechanism, this work further synthesizes a self-centering clamping devise whose two clamping parts move the exact same distance in opposite direction simultaneously that can improve processing quality since it maintains the work-piece central position. Starting with the discussion of output forces of self-centering clamping mechanisms as well as summarizing feasible mechanism types, the influence of parameters on design result is then analyzed so as to propose some advices and directions while designing afterward.
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Chen, Chin-Tao, and 陳青濤. "A design of Predicted Fuzzy Controller for Constant Turning Force System." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/33813624835716801689.
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博士大同工學院
機械工程學系
84
A predicted fuzzy controller (PFC) incorporating a fixed metal removal rate(MRR) controller is designed in this disseration for the sake of the extention of the tool life and improving the cutting productivity. The fuzzy control techniques and the grey theory are integrated to develop a PFC to the constant turning force operation. The most important difference between the PFC and the conventional fuzzy control(FC) is that the fuzzy control signal is determined by the future predicted state value obtained by a grey model instead of the present state value used in the traditional fuzzy controller(FC). Hence, one can get the control signal in advance and avoid the system out of safety. On the other hand, an auxiliary fixed metal removal rate(MRR) controller, which can be determined by the lathe power or machining roughness or tool chatter...etc, on the constant turning force (CTF) operation is adopted. When the controlled plant is a nonlinear function, the productivity will always decrease due to the feed decreases much rapidly with the increases of cutting depth, thus MRR reduces accordingly. A reasonable solution is to increase the cutting speed. Consequently, the concept of the MRR is built in the auxiliary controller to improve the CTF control system. Because of the prediction ability of grey model, the two inputs of the fuzzy controller, error signal and error change signal, keep more stable than that without prediction model. The PFC system with MRR controller is more robust than that of the traditional FC system.
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Chiou, Ya-Lin, and 邱雅琳. "Identification of Cutting Dynamic Characteristic Systems for Constant Cutting Force Control." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/zn83vn.
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碩士國立臺灣大學
機械工程學研究所
105
During past decades the techniques of computer numerical control (CNC) machining centers has grown tremendously and their applications has expanded rapidly. Traditionally the operating parameters such as spindle speed or feed rate are prescribed conservatively by experienced technicians in order to protect the cutting tool or the machine. As a result, many processes run under inefficient operating conditions. For this reason, using adaptive constant cutting force control with adjustable feed rate can improve efficiency. Although there are already many researches for adaptive cutting force control, their methods of establishing dynamic systems are complicated and seldom take actual cutting dynamic characteristics of cutting process. The purpose of this study is to identifying cutting dynamics with consideration of actual cutting dynamic characteristics during cutting process in a simple way. Besides, most researches use dynamometer to measure cutting force, but dynamometer is expensive and limiting the working space. This study will use spindle current instead of cutting forces from dynamometer as input signals. In this study, we establishes cutting dynamic characteristic system by using sweep experiment. By using system identification with spindle current data to get a transfer function of system, we can design a proper controller based on this transfer function and verify the feasibility of constant cutting force control with spindle current.
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Hsieh, Meng-Hsun, and 謝孟勳. "An Electromotive-force Constant Estimation for a Permanent Magnet Synchronous Motor." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/6dmy99.
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碩士國立交通大學
電機與控制工程系所
92
Since the motor is invented, through people's constant improvement and innovation, the motor becomes a kind of indispensable important component in the industry now. We can nearly all see the existence of the motor in the products inside all offices, it is like a printer, CD-ROM drive, scanner ,etc.. So, how to control the motor becomes an important knowledge. There is a reaction EMF constant (or called the torsion constant)(the EMF constant under the metric system is Equal to the torsion constant) in the magnetic parameter of the permanent-magnet synchronous motor. It relates to value of the torque, rotational speed that can be operated, and the performance of the motor. So motor designer or user all take notice of it very much . If we can estimate it in advance, can be as a reference of designing the motor controller or selecting the permanent-magnet synchronous motor. This thesis utilize one new method which is using the characteristic of the motor when let motor rotate in single-phase mode, to calculate the reaction EMF constant fast. This experiment use driver IC(BA6849 ) and an ADDA(Analog to Digital and Digital to Analog) card to verify the feasibility of this method, and apply this method to the products actually. Hope that can accelerate the time of motor factory's measuring the reaction EMF constant. And then motor factory can make the measuring reaction EMF constant to the list of all products should be measure . In order to improve the quality of the products.
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Tang, Ming. "Computer Aided Manufacturing for gear grinding process using Constant Grinding Force method." 1986. http://catalog.hathitrust.org/api/volumes/oclc/15493841.html.
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Thesis (M.S.)--University of Wisconsin--Madison, 1986.Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 142-143).
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Ming-Ling, Shih, and 施明玲. "A Study on Fuzzy Control for The Constant Turning Force Contorl System." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/49184996769604590139.
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Daskalogiannakis, John. "Testing the constant force hypothesis : a clinical study of cuspid retraction using magnets." 1994. http://hdl.handle.net/1993/9804.
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