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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.

Chattering suppression in sliding mode control system

Lee, Hoon, January 2007 (has links)
Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 131-136).

On the development of a dynamic cutting force model with application to regenerative chatter in turning

Cardi, Adam A. January 2009 (has links)
Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2009. / Committee Co-Chair: Bement, Matt; Committee Co-Chair: Liang, Steven; Committee Member: Griffin, Paul; Committee Member: Mayor, Rhett; Committee Member: Melkote, Shreyes; Committee Member: Zhou, Chen.

Chattering suppression in sliding mode control system

Lee, Hoon 10 December 2007 (has links)
No description available.

Modified Sliding Mode Control Algorithm for Vibration Control of Linear and Nonlinear Civil Structures

Wang, Nengmou 27 July 2011 (has links)
No description available.

Accelerated simulation of hybrid systems : method combining static analysis and run-time execution analysis / Simulation accélérée des systèmes hybrides : méthode combinant analyse statique et analyse à l'exécution

Aljarbouh, Ayman 05 September 2017 (has links)
Cette thèse apporte quatre principales contributions : une méthode d'éliminateur de phénomènes de ''chattering'' d'automates hybrides, par calcul d'une dynamique régulière équivalente à l'aide d'une convexification de Filippov ; une méthode d'accélération de la simulation de certains comportements Zénon, dits géométriques, pour certains automates hybrides ; des preuves de préservation par les méthodes ci-dessus d'une sémantique des automates hybrides à base d'analyse non-standard ; développement de trois logiciels prototypes, l'un sous la forme d'une bibliothèque Simulink, le second sous la forme d'un environnement de simulation de composants FMI, et le troisième étant une implémentation de la méthode de régularisation dans le langage de modélisation de systèmes hybrides Acumen. / This thesis deals with Zeno behavior of hybrid systems, and it has four main contributions : a method of eliminating "chattering" phenomena of hybrid automata, by computing an equivalent dynamics using a new convexification approach ; a method for accelerating the simulation of geometric-Zeno behavior in which the solution converges to a Zeno limit point according to a geometric series ; a proof of preservation by the above methods of a semantics of hybrid automata based on non-standard analysis ; a development of three prototype software, one in the form of a Simulink library, the other in the form of an FMI simulation environment, and the third being an implementation of the regularization method in the Modeling and simulation tool Acumen.

PVDF sensor based wireless monitoring of milling process

Ma, Lei 05 February 2013 (has links)
Analytical force and dynamic models for material removal processes such as end and face milling do not account for material and process related uncertainties such as tool wear, tool breakage and material inhomogeneity. Optimization of material removal processes thus requires not only optimal process planning using analytical models but also on-line monitoring of the process so that adjustments, if needed, can be initiated to maximize the productivity or to avoid damaging expensive parts. In this thesis, a Polyvinylidene Fluoride (PVDF) sensor based process monitoring method that is independent of the cutting conditions and workpiece material is developed for measuring the cutting forces and/or torque in milling. The research includes the development of methods and hardware for wireless acquisition of time-varying strain signals from PVDF sensor-instrumented milling tools rotating at high speeds and transformation of the strains into the measurand of interest using quantitative physics-based models of the measurement system. Very good agreement between the measurements from the low cost PVDF sensors and the current industry standard, piezoelectric dynamometer, has been achieved. Three PVDF sensor rosettes are proposed for measuring various strain components of interest and are shown to outperform their metal foil strain gauge counterparts with significantly higher sensitivity and signal to noise ratio. In addition, a computationally efficient algorithm for milling chatter recognition that can adapt to different cutting conditions and workpiece geometry variations based on the measured cutting forces/torque signals is proposed and evaluated. A novel complex exponential model based chatter frequency estimation algorithm is also developed and validated. The chatter detection algorithm can detect chatter before chatter marks appear on the workpiece and the chatter frequency estimation algorithm is shown to capture the chatter frequency with the same accuracy as the Fast Fourier Transform (FFT). The computational cost of the chatter detection algorithm increases linearly with data size and the chatter frequency estimation algorithm, with properly chosen parameters, is shown to perform 10 times faster than the FFT. Both the cutting forces/torque measurement methodology and the chatter detection algorithm have great potential for shop floor application. The cutting forces/torque measurement system can be integrated with adaptive feedback controllers for process optimization and can also be extended to the measurement of other physical phenomena.

Lois de commande par modes glissants du moteur pas-à-pas

Nollet, Frédéric Perruquetti, Wilfrid Floquet, Thierry. January 2008 (has links)
Reproduction de : Thèse de doctorat : Automatique et informatique industrielle : Villeneuve d'Ascq, Ecole centrale de Lille : 2006. / Titre provenant de la page de titre du document numérisé. Bibliogr. p. 223-228.


Swikir, Abdalla M Lamen January 2015 (has links)
No description available.


Gu, Hongyan 10 1900 (has links)
<p>This work detailed in this thesis has developed two new technologies for modifying polymer surfaces with variable chemistry and topography: 1. Surfadditive (surface-active-additive) approach for polymer surface chemistry modification during molding. This concept was demonstrated by the synthesis and application of two types of surfadditives. The first type of surfadditive is a block copolymer having the “head-neck-body” structure. The “head” and “neck” of the chain molecule provides functionality and enables the surfadditive to migrate to the surface, while the “body” of the molecule provides rooting to the bulk material. The second type of surfadditive is a magnetic nanoparticle having an iron core and PMMA/POSS block copolymer shell. Both surfadditives were successfully applied in the molding processes of PMMA samples for surface chemistry modification. Various factors affecting the migration processes were investigated; 2. A one step “cutting-edge” based on controlled chattering for surface topography construction (patterning). This technology was developed by using an oscillating diamond knife in ultramicrotomy and was operated at high cutting speed with controlled oscillation. One dimensional wavy patterns on PMMA and epoxy sample surfaces were successfully fabricated by this one-step method. The sizes of patterns were tunable form 30 nm to 3 µm through adjusting cutting speed and oscillation frequency. Besides, this technology was also able to fabricate nanowires structures with high aspect ratios (10,000) and adjustable sizes from a variety of materials.</p> / Doctor of Philosophy (PhD)

Fenômeno Fuller em problemas de controle ótimo: trajetórias em tempo mínino de veículos autônomos subaquáticos / Fuller Phenomenon in optimal control problems: minimum time path of autonomous underwater vehicles.

Eduardo Oda 03 June 2008 (has links)
As equações do modelo bidimensional de veículos autônomos subaquáticos fornecem um exemplo de sistema de controle não linear com o qual podemos ilustrar propriedades da teoria de controle ótimo. Apresentamos, sistematicamente, como os conceitos de formalismo hamiltoniano e teoria de Lie aparecem de forma natural neste contexto. Para tanto, estudamos brevemente o Princípio do Máximo de Pontryagin e discutimos características de sistemas afins. Tratamos com cuidado do Fenômeno Fuller, fornecendo critérios para decidir quando ele está ou não presente em junções, utilizando para isso uma linguagem algébrica. Apresentamos uma abordagem numérica para tratar problemas de controle ótimo e finalizamos com a aplicação dos resultados ao modelo bidimensional de veículo autônomo subaquático. / The equations of the two-dimensional model for autonomous underwater vehicles provide an example of a nonlinear control system which illustrates properties of optimal control theory. We present, systematically, how the concepts of the Hamiltonian formalism and the Lie theory naturally appear in this context. For this purpose, we briefly study the Pontryagin\'s Maximum Principle and discuss features of affine systems. We treat carefully the Fuller Phenomenon, providing criteria to detect its presence at junctions with an algebraic notation. We present a numerical approach to treat optimal control problems and we conclude with an application of the results in the bidimesional model of autonomous underwater vehicle.

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