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1
Jensen, Brian D. "Identification of Macro- and Micro-Compliant Mechanism Configurations Resulting in Bistable Behavior." BYU ScholarsArchive, 2003. https://scholarsarchive.byu.edu/etd/83.
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The purpose of this research is to identify the configurations of several mechanism classes which result in bistable behavior. Bistable mechanisms have use in many applications, such as switches, clasps, closures, hinges, and so on. A powerful method for the design of such mechanisms would allow the realization of working designs much more easily than has been possible in the past. A method for the design of bistable mechanisms is especially needed for micro-electro-mechanical systems (MEMS) because fabrication and material constraints often prevent the use of simple, well-known bistable mechanism configurations. In addition, this knowledge allows designers to take advantage of the many benefits of compliant echanisms, especially their ability to store and release energy in their moving segments. Therefore, an analysis of a variety of mechanism classes has been performed to determine the configurations of compliant segments or rigid-body springs in a mechanism which result in bistable behavior. The analysis revealed a relationship between the placement of compliant segments and the stability characteristics of the mechanism which allows either analysis or synthesis of bistable mechanisms to be performed very easily. Using this knowledge, a method of type synthesis for bistable mechanisms has been developed which allows bistable mechanisms to be easily synthesized. Several design examples have been presented which demonstrate the method. The theory has also been applied to the design of several bistable micromechanisms. In the process of searching for usable designs for micro-bistable mechanisms, a mechanism class was defined, known as "Young" mechanisms, which represent a feasible and useful way of achieving micro-mechanism motion similar to that of any four-bar mechanism. Based on this class, several bistable micro-mechanisms were designed and fabricated. Testing demonstrated the ability of the mechanisms to snap between the two stable states. In addition, the mechanisms showed a high degree of repeatability in their stable positions.
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Alfattani, Rami. "Design of Shape-Morphing Structures Consisting of Bistable Compliant Mechanisms." Scholar Commons, 2019. https://scholarcommons.usf.edu/etd/7725.
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This dissertation presents a design concept for shape-morphing structures that have two stable configurations. The design concept defines the methodology of transforming a planar structural shape into spatial structural shape using bistable compliant mechanisms. Bistable complaint mechanisms are used to achieve structural stable configurations. The dissertation incorporating geometrical relationships for the mechanisms that form the primary structure described in step-by-step process. This dissertation implements the design layouts for designer to creating shape-morphing structures including origami. The novel contribution of the work is classified in three models. The first model presents a methodology to induce bistability behavior into an origami reverse fold and partially spherical compliant mechanism. The second model presents the design and development of a bistable triangle-shaped compliant mechanism with motion limits and dwell behavior at the two stable configurations. This mechanism can be arrayed to create shape-morphing structures. The third model presents a design and development for a collapsible bistable compliant mechanism used for a shape morphing lamina-emergent frustum. Finally, physical prototypes of all models are presented as proof of concept.
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Cerminara, Adriano. "Boundary-layer receptivity and breakdown mechanisms for hypersonic flow over blunt leading-edge configurations." Thesis, University of Southampton, 2017. https://eprints.soton.ac.uk/412641/.
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Direct numerical simulations have been performed to study receptivity and breakdown mechanisms for hypersonic flow over blunt leading-edge configurations with imposed freestream acoustic disturbances. Both two-dimensional (2D) and three-dimensional (3D) fast and slow acoustic wave models have been used. The former has been adopted for 2D simulations over a blunt-nose wedge probe designed to measure freestream noise levels in hypersonic wind tunnels; the latter has been used to perform 3D simulations for a span-periodic blunt wedge in unswept and swept configurations, and for a three-dimensional generic forebody model. In the 2D wedge simulations, an analysis of the post-shock wave structure shows that fast acoustic waves are efficiently transmitted across the shock as refracted waves, while slow acoustic waves generate convected waves. The wall response to the fast mode highlights a resonance-modulation behaviour in the nose region. An estimation of the freestream noise levels in the DLR high-enthalpy (HEG) and low-enthalpy (RWG) hypersonic wind tunnels has been performed, showing higher noise levels for the HEG wind tunnel at high Mach numbers. The 3D wedge simulations have been used to study the characteristics of the receptivity and breakdown mechanisms associated with different wave types (fast/slow), disturbance amplitudes, and sweep angles. The fast-mode induced transition has been observed to be a much more rapid and powerful process than the slow-wave related transition, because of the role played by the fast-mode resonance mechanism at the leading edge. Finally, the numerical simulations performed for a generic forebody geometry have enabled comparison with a recent transition experiment carried out in the Mach 6 Purdue hypersonic wind tunnel in noisy conditions. In this case, slow acoustic waves show the most similar transition patterns to the experimental case, and, in particular, are more efficient than fast waves in triggering nonlinear growth of streamwise streaks, related to crossflow inflectional instabilities located in the off-centerline leading-edge region.
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Habib, Farooq. "Interplay between network configurations and network governance mechanisms in supply networks a systematic literature review." Thesis, Cranfield University, 2012. http://dspace.lib.cranfield.ac.uk/handle/1826/7879.
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Purpose: This work systematically reviews the extant academic management literature on supply networks. It specifically examines how network configurations and network governance mechanisms influence each other in supply networks.
Design: 125 analytical and empirical studies were identified using an evidence-based approach to review the literature mainly published between 1985 and 2012.
Synthesis: Drawing on a multi-disciplinary theoretical foundation, this work develops an integrative framework to identify three distinct yet interdependent themes that characterize the study of supply networks: a) Network Configurations (structures and relationships); b) Network Governance Mechanisms (formal and informal); and c) The Interplay between Network Configurations and Network Governance Mechanisms.
Findings: Network configurations and network governance mechanisms mutually influence each other and cannot be considered in isolation. Formal and informal governance mechanisms provide better control when used as complements rather than as substitutes. The choice of governance mechanism depends on the nature of exchange; role of management; desired level of control; level of flexibility in formal contracts; and complementary role of formal and informal governance mechanism.
Research implications: This nascent field has thematic and methodological research opportunities for academics. Comparative network analysis using longitudinal case studies offers a rich area for further study.
Practical Implications: The complexity surrounding the conflicting roles of managers at the organisation and network levels poses a significant challenge during the development and implementation stage of strategic network policies.
Originality/value: This review reveals that formal and informal governance mechanisms provide better control when used as complements rather than as substitutes.
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Ozdemir, Mustafa. "Inverse Dynamics Control Of Parallel Manipulators Around Singular Configurations." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/3/12609212/index.pdf.
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In this thesis, a technique for the motion of parallel manipulators through drive singularities is investigated. To remedy the problem of unbounded inverse dynamics solution in the neighborhood of drive singularities, an inverse dynamics controller which uses a conventional inverse dynamics control law outside the neighborhood of singularities and switches to the mode based on the formerly derived modified equations inside the neighborhood of singularities is proposed. As a result, good tracking performance is obtained while the actuator forces remain within the saturation limits of the actuators around singular configurations.
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Ferrigno, Giulio. "Strategic alliances: value creation and appropriation mechanisms, configuration, and portfolio evolution." Doctoral thesis, Università di Catania, 2018. http://hdl.handle.net/10761/3863.
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The object of this dissertation is to provide a better understanding of strategic alliances with a specific focus on value creation and value appropriation mechanisms, alliance configuration, and the evolution of alliance portfolios. In more detail, the purpose of the dissertation is threefold:
(I) to summarize the existing alliance research around value creation and value appropriation processes, which are the two distinct, dynamic and interrelated processes underlying alliance partners performance. In doing so, it aims to shed lights on the theoretical underpinnings that explain the key value creation and value appropriation mechanisms that lie beneath the two processes. In addition, it aims to clarify the interdependence between the two processes, thereby advancing a contribution that conceptually tackles the need to treat value creation and value appropriation jointly (e.g., Di Minin and Faems, 2013; Lepak et al., 2007);
(II) to rejoin the challenge to explore the relationship between R&D alliances and alliance partners innovation performance, by relying on the theoretical lens of the knowledge-based view of the alliances (Grant & Baden-Fuller, 2004; Vasudeva & Anand, 2011). Specifically, by adopting this theoretical lens we challenge the issue to identify the major factors that lead alliance partners to achieve high innovation performance by means of R&D alliances. Additionally, a challenge of the research is to revamp a key research stream in the alliance literature (i.e., alliance configuration) by examining the combinatory effects that inevitably occur among these factors;
(III) to explore the features that epitomize alliance strategy with regards to the management of alliance portfolio. In particular, the dissertation aims to undertake an investigation of the existing body of research on alliance portfolio management in order to elucidate its main features. In addition, the dissertation is aiming to complement extant research with an investigation of these features in a case study (Ericsson) in order to provide insights on alliance strategy, from the managerial point of view (Hoffman, 2005).
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Habibi, Rabeb. "Les mécanismes de performance de la diversification des business models : une analyse QCA des compagnies aériennes." Electronic Thesis or Diss., Université de Lille (2022-....), 2024. https://pepite-depot.univ-lille.fr/ToutIDP/EDSJPG/2024/2024ULILD020.pdf.
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Malgré le nombre croissant d'entreprises déployant plusieurs Business Models simultanément, peu de recherches se sont intéressées au lien entre la diversification des Business Models et la performance. L'objectif de cette thèse est d’appréhender cette relation en étudiant les mécanismes qui lui sont sous-jacents. En utilisant des données provenant de l'industrie mondiale du transport aérien, nous avons réalisé dix-huit analyses QCA et documenté les choix relatifs aux mécanismes d'exploitation des synergies et de réduction des anti-synergies au sein des compagnies aériennes qui exploitent simultanément un Business Model Low-Cost parallèlement à leur Business Model originel à service complet. La mobilisation d’une approche configurationnelle, nous a permis d’identifier les configurations de mécanismes expliquant la performance et la haute performance d’un portefeuille de Business Models. Nos résultats suggèrent que les mécanismes d'exploitation des synergies et de réduction des anti-synergies sont complémentaires et interdépendants. Contrairement à ce que suggèrent certaines recherches, il ressort que l'exploitation des synergies liées aux ressources n'est pas suffisante pour expliquer la performance des portefeuilles de Business Models. En outre, nos résultats montrent une divergence des combinaisons de mécanismes d'exploitation des synergies liées aux ressources. Cependant, ces derniers n'ont pas révélé de différence majeure entre les configurations de mécanismes à court et à moyen terme. Par ailleurs, l'analyse des cas typiques et déviants nous a permis d'identifier une nouvelle typologie de synergies et d'anti-synergies, qui tient compte des dimensions temporelle et interactionnelle de ces mécanismes. Les contributions de la thèse soulignent la nature équifinale, non linéaire et asymétrique des configurations de mécanismes expliquant la performance des portefeuilles de Business ModelsDespite the growing number of companies deploying multiple Business Models simultaneously, few studies have explored the link between Business Model diversification and performance. The objective of this thesis is to study this relationship by examining the underlying mechanisms. Using data from the global airline industry, we conducted eighteen QCA analyses and documented the choices related to the mechanisms of exploiting synergies and reducing anti-synergies within airlines that simultaneously operate a low-cost Business Model and their original full-service Business Model. The deployment of a configurational approach allowed us to identify the configurations of mechanisms explaining both performance and high performance in a portfolio of Business Models. Our results suggest that the mechanisms for exploiting synergies and reducing anti-synergies are complementary and interdependent. Contrary to what some research suggests, it emerges that the exploitation of resource-related synergies alone is not sufficient to explain the performance of Business Model portfolios. Furthermore, our results reveal a divergence in the combinations of mechanisms for exploiting resource-related synergies. Meanwhile, our results did not reveal a significant difference between short-term and medium-term mechanism configurations. Additionally, the analysis of typical and deviant cases allowed us to identify a new typology of synergies and anti-synergies that considers the temporal and interactional dimensions of these mechanisms. The contributions of the thesis highlight the equifinal, non-linear and asymmetric nature of the configurations of mechanisms explaining the performance of Business Model portfolios
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Williams, Robert L. "Planar robotic mechanisms: analysis and configuration comparison." Diss., Virginia Polytechnic Institute and State University, 1988. http://hdl.handle.net/10919/54462.
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Robotic mechanisms are defined in this dissertation to be closed-loop, in-parallel actuated mechanical devices possessing several degrees-of-freedom. Parallel robotic mechanisms have recently received attention in the robotics literature as a potential alternative to the existing serial industrial robot. Serial robots are in a cantilever configuration which makes them relatively compliant and Ieads to poor accuracy. Many serial manipulators have motors that are carried on moving links which limits dynamic performance. Robotic mechanisms are in a parallel configuration which provides excellent stiffness, load-bearing, and accuracy. Robotic mechanisms combine the advantages of serial robots and closed-loop single-degree-of-freedom mechanisms to form a versatile new robotic tool.
This dissertation presents theoretical kinematic analysis and design of planar robotic mechanisms. The topics covered are type and number synthesis, kinematic position solution, velocity and acceleration analysis, kinetostatic analysis, workspace optimization, and link interference avoidance. Throughout this work, comparisons are made among three general manipulator configurations: serial, parallel-serial, and fully parallel. Strengths and limitations are discussed for each configuration type.
This investigation provides the analytical foundation for implementation of planar robotic mechanisms. Closed-form solutions to the kinematic position, velocity, and acceleration problems are presented. Manipulator reachable hand areas are maximized. An underlying theme of this work is tradeoffs between competing factors relating to various configurations of parallel robotic mechanisms; these tradeoffs are important design considerations. The recommendation of this dissertation is to pursue practical development of robotic mechanisms for general industrial manipulation tasks.Ph. D.
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Pohl, Eric David. "Analysis of singular configurations for robotic manipulators." Thesis, Georgia Institute of Technology, 1988. http://hdl.handle.net/1853/18368.
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Hanna, Brandon Holbrook. "Modeling and Testing of Bistable Waterbomb Base Configurations." BYU ScholarsArchive, 2014. https://scholarsarchive.byu.edu/etd/4336.
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Origami is making an impact in engineering as solutions to problems are being found by applying origami principles (eg. flat-foldability) and using specific crease patterns as inspiration. This thesis presents an in-depth analysis of a particular origami fold -- the waterbomb base -- to facilitate its use in future engineering problems. The watebomb base is of interest due to its familiarity to the origami community, simple topology (can be made by folding a single sheet of paper four times), scalability, generalizability, and interesting kinetic behavior. It can behave as a nonlinear spring as well as a one- or two-way bistable mechanism. This thesis presents models of the kinetic behavior of the traditional waterbomb base as well as some non-traditional variants to be used as tools in future development of waterbomb-base-inspired mechanisms. In all cases considered here, developability as well as rotational symmetry in both the geometry and motion of the mechanisms are assumed. The thesis provides an introduction to origami and reviews some of the ways in which it has been studied and applied in engineering fields. The waterbomb base is also presented as a specific origami fold with practical application potential. Models for the behavior of the traditional waterbomb base are introduced and its potential usefulness as a testbed for actuation methods is discussed. Models are developed for its kinematic and bistable behavior, including the forces needed to transition between stable states. These models are validated by comparison to physical prototype testing and finite element analysis. The thesis introduces the generalized waterbomb base (WB) and generalized split-fold waterbomb base (SFWB). The WB maintains the pattern of alternating mountain and valley folds around the vertex but in this generalized case any even number of folds greater than or equal to 6 is allowed. An SFWB is created by splitting each fold of a WB into two “half folds”, effectively doubling the number of folds and links but halving the deflection at each fold. The same models that were developed for the traditional waterbomb base are developed for the WB and the SFWB and a few potential applications are discussed.
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Song, Jiwen. "Organizational control mechanisms and employee outcomes : processes and configuration /." View abstract or full-text, 2005. http://library.ust.hk/cgi/db/thesis.pl?MGTO%202005%20SONG.
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Zhu, Ting 1971. "Atomistic characterization of stress-driven configurational instability and its activation mechanisms." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/17954.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2004.Includes bibliographical references (p. 145-156).
Cleavage decohesion and shear dislocation nucleation are two basic modes of localized deformation in crystal lattices, which normally result from instability of the atomic configuration driven by mechanical forces. The critical state of instability and its thermal activation mechanisms can be quantitatively determined by analyzing the energetics of the lattice system. In this thesis, the unit processes of configurational instability of crystal lattices under various non-uniform structural and/or chemical environments are characterized by systematically probing the atomistic potential energy landscape of each system using the state of the art configurational space sampling schemes. The problems studied are homogeneous dislocation nucleation in a perfect crystal by nanoindentation, dislocation emission and cleavage decohesion at atomically sharp crack tips, and chemically-enhanced bond breaking in a wet silica nanorod. These processes are studied in a unified manner such that two important types of properties are determined: one is the athermal load at which the instability takes place instantaneously without the aid of thermal fluctuations, and the other is the stress-dependent activation energy used for an estimate of the kinetic rate of transition. Along the way, important aspects concerning the atomistic characterization of configurational instability are revealed. Of particular note is extending the continuum instability criterion to detect atomic defect nucleation. We demonstrate that a local instability criterion can be applied to identify dislocation nucleation in the case of indentation, considering that the relatively small strain gradient beneath the indenter will lead to a mode of long wavelength phonon instability suitable for a study
(cont.) by the local continuum approach. In addition, the chemical effect on stress-driven lattice instability is revealed via the study on reactivity of a silica nanorod with water. We identify distinct competing mechanisms of hydrolysis which are rate-controlling at different load regimes. The ensuing stress-mediated switch of rate-limiting steps of hydrolysis quantitatively demonstrates the impact of finding the detailed molecular mechanisms on a realistic estimate of the activation rate when configurational instability occurs within a chemically reactive environment. Implications regarding the analysis of chemically-assisted brittle fracture are also discussed.
by Ting Zhu.
Ph.D.
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Gavelin, Anders. "Studies on structural and biomechanical responses in seat integrated safety belt configurations." Doctoral thesis, Luleå, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-26683.
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The common 3-point safety belt usually has some anchor points on the car body. However, it is also possible to mount all anchor points on the seat structure. In general, different studies show some advantages with seat integrated safety belts. Thus, further investigations are motivated. One safety advantage appears in the case of so-called small overlap crashes. Also, the ride-down distance of the occupant may be increased by allowing controlled energy absorbing deformation of the seat structure. Further, methods that can be used to minimize the weight of seat structures with integrated safety belts are of interest. A complement to full scale crash tests is the use of numerical models and numerical simulation, typically finite element (FE) analysis. Research and development of numerical models are constantly improved. In general, any type of numerical model needs to be evaluated to physical tests in order to make it behave as realistic as possible. The purpose of the present thesis was to study seat structures with integrated safety belts with a design that may intentionally deform and absorb energy during a crash. The approach was to use numerical models and numerical simulation and to investigate both biomechanical and mechanical responses. The aim is to create a basis for future research in the design of seat structures with integrated safety belts. In Paper A and B, parametric studies comparing integrated 3- and 4-point safety belt configurations relative to common 3-point configurations are presented. A number of mechanical parameters were varied. Biomechanical responses of the Hybrid III (HIII) FE-dummy model used as occupant were studied. In Paper C, the creation and evaluation of a human FE-model of a 50th percentile male is presented. The evaluation was made to results from studies with post mortem human subjects (PMHS). In Paper D, a conceptual methodology for mass minimization of a property based model (PBM) of a seat structure with an integrated 3-point safety belt configuration and with a HIII FE-dummy model used as occupant is presented. Both mechanical and biomechanical constraints were used as well as different start values of the design variables. In Paper E, the evaluation of FE-models of simplified seat structures with integrated 3-point safety belt configurations to a number of full scale experiments in the form of sled tests with a HIII crash test dummy used as occupant is presented. The studies in Paper A and B reveals that with an adequate combination of mechanical properties of the seat structure it should be possible to achieve equal or lower biomechanical responses of the occupant with a seat integrated safety belt configuration compared to a common. The seat integrated 4-point configurations in these studies performed poorer than the corresponding 3-point in general. An important issue is that belt- webbing distribution between lap and torso belt parts is allowed. The study in Paper C showed that the created and evaluated human FE-model could be used to further explore injury producing mechanisms. However, in order to achieve a fully evaluated human FE-model there is a need for both further development and more reference tests with PMHS. In Paper D, the study showed that the presented methodology may be used in a concept phase of a design process. The optimization runs with different start values of the design variables found a number of different local minima instead of one global minimum. The dynamics of the system was highly non-linear. To find an optimal combination of mechanical properties and biomechanical responses, a compromise appears to be needed. The evaluated FE-model in Paper E may be used in simulations that consider both biomechanical and mechanical responses. The majority of the simulated responses showed good agreement with or slightly underestimated the experimental responses. Some issues of the FE-model suggest areas for further development. The FE-model could be used as a base for further studies.Godkänd; 2008; 20080404 (ysko)
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Li, Wei. "The dynamics of perfect steering bogie vehicles and its improvement with a reconfigurable mechanism." Thesis, Loughborough University, 1995. https://dspace.lboro.ac.uk/2134/25488.
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Even since railway vehicles were invented, railway scientists and engineers have been putting a lot of effort in finding the solution to the fundamental conflict between vehicle stability in the lateral plane and vehicle's capability of negotiating curves. Many configurations of railway bogie vehicles have been proposed and applied to minimise the conflict. The purpose of the research project is i) to create new configurations that can decouple the basic conflict, ii) to investigate dynamic behaviour of the new configurations and iii) to conceive a new mechanism that can improve the dynamics of the new configurations. Three configurations of body-steered bogie vehicles have been set up in the research. The sufficient conditions for them to be capable of perfect steering have been derived. They are called perfect steering vehicles when they satisfy these sufficient conditions. Their curving ability, stability and ride performance have been investigated. To overcome the disadvantages of the perfect steering vehicles, the reconfigurable mechanism has been conceived. The improvement in the dynamic behaviour of the perfect steering vehicles with the reconfigurable mechanism has been demonstrated. A computer program has been developed to undertake the simulation. The steering capability of the perfect steering vehicles is much better than that of conventional bogie vehicles. There are two modes of instability in the perfect steering vehicles: low conicity instability and conventional instability in the perfect steering vehicle. The perfect steering vehicles can decouple the conflict between their conventional stability and curving. The improvement of stability and ride performance of the perfect steering vehicles is, however, limited by the low conicity instability. When the reconfigurable mechanism is applied, a body-steered bogie vehicle can become a perfect steering vehicle when on curves and can become a conventional bogie vehicle when in other circumstances. Low conicity instability can be eliminated when the reconfigurable mechanism is used. This class of vehicles possess the advantages of both conventional bogie vehicles and perfect steering vehicles, and thus, provide a very valuable solution for the fundamental conflicts between the stability and steering ability and between ride performance and stability of railway vehicles. The findings in this thesis have great significance in developing perfect steering vehicles.
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Vernon, Russell A. "Discovering optimal unit cell configurations when designing for additive manufacturing using lattice structures." Thesis, California State University, Long Beach, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10108174.
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According to Wohlers Report 2014, the worldwide 3D printing industry is now expected to grow from $3.07B in revenue in 2013 to $12.8B by 2018, and exceed $21B in worldwide revenue by 2020. With 3D printing rapidly evolving from a prototype commodity to a means to produce full production items, lattice structures are becoming of great interest due to their superior structural characteristics and lightweight nature. Within design, lattice structures have typically been defined by preset beam configurations within a cube. Certain configurations have been proven analytically to be optimal for certain load functions, but never has there been optimization performed to discover or verify the optimal lattice shapes and sizes within a predefined cubic space. By performing optimization on these cubic cells, a design guideline can be created for designers of lattice structures. In this thesis, several lattice configurations are analyzed both from a micro level (single unit cell) as well as a macro level (a simple series of unit cells). Optimization is performed with respect to stiffness and compliance to identify strategic configurations for bending, torsion, compression and tension. Only cubic base cells are analyzed (i.e. no hexagonal). Knowing optimal lattice configurations from a structural standpoint enables designers to further reduce weight and increase structural efficiencies when designing for additive manufacturing. The results of this study yield a well-defined guideline for design engineers to utilize when lattice structures are incorporated in a structural design. With this design guideline information available to design engineers, further utilization of lattice structures can be exploited by efficiently applying strategic unit cell configurations to the overall design.
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Grudić, Gregory Z. "Iterative inverse kinematics with manipulator configuration control and proof of convergence." Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/42018.
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A complete solution to the inverse kinematics problem for a large class of practical manipulators,
which includes manipulators with no closed form inverse kinematics equations, is presented in this
thesis. A complete solution to the inverse kinematics problem of a manipulator is defined as a method
for obtaining the required joint variable values to establish the desired endpoint position, endpoint
orientation, and manipulator configuration; the only requirement being that the desired solution
exists. For all manipulator geometries that satisfy a set of conditions (THEOREM I), an algorithm
is presented that is theoretically guaranteed to always converge to the desired solution (if it exists).
The algorithm is extensively tested on two complex 6 degree of freedom manipulators which have no
known closed form inverse kinematics equations. It is shown that the algorithm can be used in real
time manipulator control. Applications of the method to other 6 DOF manipulator geometries and to
redundant manipulators are discussed.Applied Science, Faculty of
Electrical and Computer Engineering, Department of
Graduate
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Hao, Jingyan [Verfasser]. "Araneiform terrain on Mars — spatial configuration and mechanism of formation / Jingyan Hao." Berlin : Freie Universität Berlin, 2020. http://d-nb.info/1219904821/34.
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Avén, Joakim. "Analysis of the Z-wing configuration." Thesis, Mälardalens högskola, Akademin för innovation, design och teknik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-12135.
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This thesis will analyze the Z-wing configuration. The Z-wing configuration is basically an airplane that has one of the wings placed at the forward section of the fuselage and the other wing placed on the other side far aft at the fuselage. This configuration creates a lot of different and unwanted forces and moments due to a differential in lift and drag between both the wings and the main objective with this thesis is to get a Z-wing to fly straight and level flight without these strange and unwanted forces and moments over it. Therefore the contribution of the wings different parameters to different moments and forces have been mapped out. Parameters such as the angle of incidence, wing span, dihedral, placement of wings etc. All the calculations done regarding the aerodynamic forces on the Z-wing have been performed in the Tornado, which is a program that runs in MATLAB and uses Vortex Lattice Method for its calculations. The outcome was that a steady level flight was possible. The configuration does have a lot of disadvantages. It will be very difficult to control in pitch, yaw and roll, although a backwards sweep of the front wing and a backwards sweep of the aft wing made roll control much better.
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Mjöberg, Mårten, and Axel Stenfors. "CPTu Configuration Impact on Evaluated Undrained Shear Strength." Thesis, KTH, Jord- och bergmekanik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-279465.
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This thesis evaluates the commonly used geotechnical probing method CPTu, on how different probe configurations impact the resulting evaluated undrained shear strength in soft clay deposits, in comparison to each other and laboratory methods. This is done by performing field investigations on Lindefältet, Södermanlands län, Sweden. Comparison is done on the two Swedish manufacturers of CPTu probes, by different calibration limits, filter types and whether overloading the probe over the calibration limit affects the evaluated undrained shear strength registered. The main conclusions are that one of the manufacturers’ probes registers deviating results in one configuration, that calibration limit has a noticable impact on the results, and that overloading on the probe and filter choice has negliable impact on the results.I detta examensarbete utvärderas den vanligt förekommande geotekniska sonderingsmetoden CPTu, på hur olika konfigurationer av sonder påverkar den resulterande utvärderade odränerade skjuvhållfastheten i lösa leravlagringar, 9i jämförelse med varandra och med laboratoriemetoder. Detta är genomfört genom fältundersökningar på Lindefältet, Södermanlands län. Jämförelsen gjordes på de två svenska CPTu-tillverkarnas sonder. Detta är gjort med hänsyn till olika kalibreringar av konspetstryck, filtertyper, och huruvida sonden har varit överlastad påverkar den utvärderade skjuvhållfastheten som registreras. De huvudsakliga slutsatserna är att en av tillverkarnas sonder registerar udda värden i en konfiguration, att kalibreringar av konspetstryck har en märkbar påverkan på de resulterande värdena på utvärderade odränerade skjuvhållfastheten, samt att överlastning av sonder och val av filtertyp har liten till omärkbar påverkan på resultatet.
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SONG, NAN, and JINPING ZHU. "Knowledge transfer and global R & D operations within MNC." Thesis, Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-19605.
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With the development of globalization, increasingly more companies began to use worldwide resources to do product or service research and development. Multinational corporations (MNC) became to more rely on their subunits that located in different countries to conduct innovations. As a result, keep a good knowledge transfer between headquarter and subunits or among peer subunits is crucial for MNC to operate R & D activities. This study explores the relationship between knowledge transfer and R & D operations through two knowledge transfer mechanisms and three categories of R & D configurations. By applying the qualitative strategy with a focus on four case companies (three are from Sweden, one is from China), we conduct a cross case analysis and the result shows that both expatriate management policy and communication frequency are very important knowledge transfer mechanisms for MNC to keep a good knowledge transfer in global R & D operations. In terms of expatriate management policy, it is very important for MNC sending engineers from headquarter to subunits or between peer subunits in order to transfer technology knowledge and facilitate R & D operations. Moreover, send top managers from headquarter to subunits could also help transfer process knowledge and keep overall control of subunits. In terms of communication frequency, if MNC employs a concentrated development in headquarter (or R & D center), it is very important to maintain a frequent communication between headquarter and subunits so as to keep a smooth knowledge transfer between them. And if MNC applies a dispersed research and development configuration, keep a frequent communication between peer subunits is crucial. In addition, this study also found certain connections between innovation process and R & D configurations.
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Marcos, Jay M. "Computational and Experimental Comparison of a Powered Lift, Upper Surface Blowing Configuration." DigitalCommons@CalPoly, 2013. https://digitalcommons.calpoly.edu/theses/1099.
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In the past, 2D CFD analysis of Circulation Control technology have shown poor comparison with experimental results. In Circulation Control experiments, typical results show a relationship between lift coefficient, CL, vs blowing momentum coefficient, Cμ. CFD analysis tend to over-predict values of CL due to gridding issues and/or turbulence model selection. This thesis attempted to address both issues by performing Richardson’s Extrpolation method to determine an acceptable mesh size and by using FLUENT’s 2-equation turbulence models. The experimental results and CAD geometry were obtained from Georgia Tech Research Institute for comparison with the CFD analysis.
The study showed that 3D CFD analysis of circulation control showed similar results of over-predicting CL, which can also be attributed to gridding issues and turbulence model selection. When compared to the experimental results, the k − ω turbulence model produced the lowest errors in CL of approximately 15-17%. The other turbulence models produced errors within 5% of k − ω. A fully unstructured volume mesh with prismatic cells on the surfaces was used as the grid. The CCW con- figuration was analyzed with and without wind tunnel walls present, which produced errors of 20% and 15% in CL, respectively, when compared to experimental results. Despite the large errors in CL, CFD was able to capture the trend of increasing CL as Cμ was increased. Results reported in this thesis can be further calibrated to allow the CFD model to be used as a predictive tool for other CCW applications.
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Pousse, Alexandre. "Le quasi-satellites et autres configurations remarquables en résonance co-orbitale." Thesis, Paris Sciences et Lettres (ComUE), 2016. http://www.theses.fr/2016PSLEO006/document.
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L'ensemble des travaux menés au cours de cette thèse concerne l'étude de la résonance co-orbitale. Ce domaine de trajectoires particulières, où un astéroïde et une planète gravitent autour du Soleil avec la même période de révolution, possède une dynamique très riche liée aux célèbres configurations équilatérales de Lagrange, L4 et L5, ainsi qu'aux configurations alignées de Euler, L1, L2 et L3. Un exemple majeur dans le système solaire est donné par les astéroïdes « troyens » qui accompagnent Jupiter au voisinage des équilibres L4 et L5. Une deuxième configuration étonnante est donnée par les satellites Janus et Épiméthée qui gravitent autour de la planète Saturne ; suite à la forme décrite par la trajectoire d’un des satellites dans un repère tournant avec l’autre, la dynamique résultante est appelée « fer-à-cheval ». Un nouveau type de dynamique a été récemment misen évidence dans le contexte de la résonance coorbitale : les « quasi-satellites ». Il s’agit de configurations remarquables où, dans un repère tournant avec la planète, la trajectoire de l’astéroïde correspond à celle d’un satellite rétrograde. Des astéroïdes accompagnant les planètes Venus, Jupiter et la Terre ont notamment été observés dans ces configurations. La dynamique des quasi-satellites possède un grand intérêt, pas seulement parce qu’elle relie les différents domaines de la résonance co-orbitale (voir les travaux de Namouni, 1999) mais aussi parce qu’elle semble faire le pont entre les notions de satellisation et celles de trajectoires héliocentriques. Cependant, bien que le terme « quasi-satellite" soit devenu dominant dans la communauté de mécanique céleste, certains auteurs utilisent plutôt la terminologie « satellite rétrograde » révélant ainsi une ambiguïté sur la définition de ces trajectoires. Les récentes découvertes autour des exo-planètes ont motivé le développement de travaux concernant la résonance co-orbitale dans le problème des trois corps planétaire. Dans ce contexte Giuppone et al. (2010) ont mis en évidence (par une méthode numérique) les quasisatellites ainsi que des nouvelles familles de configurations remarquables : les orbites « anti-Lagrange ». La troisième partie de thèse présente alors une méthode analytique pour l'étude planétaire, permettant de révéler analytiquement les orbites anti-Lagrange ainsi qu'une esquisse d'étude des quasisatellites en adaptant à ce contexte plus général la méthode présentée dans la seconde partie. Pour ces raisons, la première partie de cette thèse a consisté à clarifier la définition de ces orbites en revisitant le cas circulaire-plan (trajectoires coplanaires avec la planète qui gravite sur une orbite circulaire) dans le cadre du problème moyen. Dans la deuxième partie de cette thèse, nous avons développé une méthode analytique apte à explorer le domaine des quasi-satellites dans le cadre du problème moyen. Nous avons réalisé cette exploration dans le cas circulaire-plan et proposé une extension aux cas excentrique-plan et circulaire-spatialThis work of thesis focuses on the study of the coorbital resonance. This domain of particular trajectories, where an asteroid and a planet gravitate around the Sun with the same period possesses a very rich dynamics connected to the famous Lagrange’s equilateral configurations L4 and L5, as well as to the Eulerian’s configurations L1, L2 and L3. A major example in the solar system is given by the “Trojan” asteroids harboured by Jupiter in the neighborhood of L4 and L5. A second astonishing configuration is given by the system Saturn-Janus-Epimetheus; this peculiar dynamics is known as “horseshoe”. Recently, a new type of dynamics has been highlighted in the context of co-orbital resonance: the quasi-satellites. They correspond to remarkable configurations : in the rotating frame with the planet, the trajectory of the asteroid seems the one of a retrograde satellite. Some asteroids harboured by Venus, Jupiter and the Earth have been observed in this kind of configuration. The quasi-satellite dynamics possesses great interest not only because it connects the different domains of the co-orbital resonance (see works of Namouni, 1999), but also because it seems to bridge the gap between satellization and heliocentric trajectories. However, despite the term quasi-satellite has become dominant in the celestial mechanics community, some authors rather use the term “retrograde satellite”. This reveals an ambiguity on the definition of these trajectories. For these reasons, the first part of this thesis consisted in clarifying the definition of these orbits by revisiting the planar-circular case (planet on circular motion) in the framework of the averaged problem. In the second part of this thesis, we developed an analytic method to explore the quasi-satellite domain in the averaged problem. We realized this exploration in the planar-circular case and proposed an extension to the planar-eccentric and spatial-circular cases. The recent discoveries around the exo-planets motivated some works on the co-orbital resonance in the planetary Three-Body Problem. In this context, Giuppone et al. (2010) highlighted (numerically) the quasi-satellite as well as new families of remarkable configurations: the “anti-Lagrange”. Then the third part of this thesis presents an analytical method for the planetary problem that allows to reveal the anti-Lagrange orbits as well as a sketch of study of quasi-satellite trajectories
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Maurini, Corrado. "ELECTROMECHANICAL COUPLING OF DISTRIBUTED PIEZOELECTRIC TRANSDUCERS FOR PASSIVE DAMPING OF STRUCTURAL VIBRATIONS: COMPARISON OF NETWORK CONFIGURATIONS." Phd thesis, Virginia Tech, 2002. http://tel.archives-ouvertes.fr/tel-00994396.
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In this work passive piezoelectric devices for vibration damping are studied. It is developed the basic idea of synthesizing electrical wave guides to obtain an optimal electro-mechanical energy exchange and therefore to dissipate the mechanical vibrational energy in the electric form. Modular PiezoElectroMechanical (PEM) structures are constituted by continuous elastic beams (or bars) coupled, by means of an array of PZT transducers, to lumped dissipative electric networks. Both refined and homogenized models of those periodic systems are derived by an energetic approach based on the principle of virtual powers. Weak and strong formulation of the dynamical problem are presented having in mind future studies involving the determination of numerical solutions. In this framework the effectiveness of the proposed devices for the suppression of mechanical vibrations is investigated by a wave approach, considering both the extensional and flexural oscillations. The optimal values of the electric parameters for a fixed network topology are derived analytically by a pole placement technique. Their sensitivities on the dimensions of the basic cell of the periodic system and on the design frequency are studied. Moreover the dependence of damping performances on the frequency is analyzed. Comparing the performances of different network topological configurations, the advantages of controlling a mechanical structure with an electric analog are shown. As a consequence of those results, new interconnections of PZT transducers are proposed. An experimental setup for the validation of the analytical and numerical results is proposed and tested. A classical experience on resonant shunted PZT is reproduced. Future experimental work is programmed.
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Oh, Yoonchan. "Multi-physics investigation on the failure mechanism and short-time scale wave motion in flip-chip configuration." Texas A&M University, 2004. http://hdl.handle.net/1969.1/2719.
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The demands for higher clock speeds and larger current magnitude in high-performance flip-chip electronic packaging configurations of small footprint have inevitably raised the concern over rapid thermal transients and large thermal spatial gradients that could severely compromise package performance. Coupled electrical-thermal-mechanical multi-physics were explored to evaluate the concern and to establish the knowledge base necessary for improving flip-chip reliability. It was found that within the first few hundred nanoseconds upon power-on, there were fast attenuating, dispersive shock waves of extremely high frequency propagating in the package. The notions of high cycle fatigue, power density and joint time-frequency analysis were employed to characterize the waves and the various failure modes associated with the moving of these short-lived dynamical disturbances in bulk materials and along interfaces. A qualitative measure for failure was also developed which enables the extent of damages inflicted by short-time wave propagation to be calculated in the probability sense. Failure modes identified in this study are all in agreement with what have been observed in industry. This suggests that micron cracks or interfacial flaws initiated at the short-time scale would be further propagated by the CTE-induced thermal stresses at the long-time scale and result in eventual electrical disruptions.
Although epoxy-based underfills with fillers were shown to be effective in alleviating thermal stresses and improving solder joint fatigue performance in thermal cycling tests of long-time scale, underfill material viscoelasticity was found to be insignificant in attenuating short-time scale wave propagation. On the other hand, the inclusion of Cu interconnecting layers in flip-chips was shown to perform significantly better than Al layers in suppressing short-time scale effects. These results imply that, if improved flip-chip reliability is to be achieved, all packaging constituent materials need to be formulated to have well-defined short-time scale and long-time scale properties. In addition, the results also suggest that the composition and layout of all packaging components be optimized to achieve discouraging or suppressing short-time scale dynamic effects. In summary, results reported herein and numerical procedures developed for the research would not just render higher packaging manufacturing yield, but also bring out significant impact on packaging development, packaging material formulation and micro-circuit layout design.
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Hazelton, William Donald. "Configuration mixing of quark states in nucleons and other baryons in the MIT bag model /." Thesis, Connect to this title online; UW restricted, 1997. http://hdl.handle.net/1773/9770.
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Malvezzi, Fernando. "Avaliação do comportamento cinemático de um mecanismo paralelo tridimensional." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/3/3151/tde-08012008-085930/.
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Este trabalho propõe uma nova estrutura cinemática paralela tridimensional com três graus de mobilidade que pode ser aplicada como robô manipulador. O volume do espaço de trabalho disponível é empregado como índice para avaliar o desempenho cinemático do mecanismo. As cinemáticas de posição e velocidade são desenvolvidas, tendo em vista o levantamento das configurações singulares e do espaço de trabalho. Os resultados obtidos com as cinemáticas direta e inversa são comparados de modo a verificar a correspondência entre eles. São levantadas diversas configurações singulares que correspondem ao alinhamento entre as barras das cadeias ativas do mecanismo e uma família de singularidades para uma das cadeias ativas é apresentada. O volume do espaço de trabalho do mecanismo é calculado pelo método da discretização, de modo a avaliar o volume do espaço de trabalho disponível, bem como a identificação da influência dos parâmetros dimensionais do mecanismo sobre este volume. O volume do espaço de trabalho com os parâmetros ótimos é expressivo, quando comparado com aqueles alcançados por manipuladores robóticos convencionais.This dissertation proposes a novel three-degree-of-freedom parallel kinematic structure in order to be applied as a three-dimensional robot manipulator. The volume of the available workspace is employed as a performance index to evaluate the kinematic behavior of the mechanism. The position and velocity kinematics are developed for mapping singular configurations and evaluating the workspace. The results obtained by performing the direct and inverse kinematics are compared in order to verify the consistency between them. It is demonstrated that most of singular configurations is represented by the alignment of the links that belong to each active chain. In addition, a family of singularities for one of the active chains is presented. The volume of the workspace is calculated by using the discretization method not only for evaluating the feasible workspace but also for identifying the influence of dimensional parameters with respect to this volume. The achieved workspace by employing the optimal parameters is comparable to that reached by conventional robot manipulators.
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Bchir, Lahsen. "Etude theorique et experimentale d'un moteur eolien darrieus : application a l'entrainement de pompes solenoides dans diverses configurations." Paris 6, 1988. http://www.theses.fr/1988PA066046.
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Un systeme original de pompage eolien est propose. Il est constitue d'une eolienne darrieus et d'une pompe solenoide. Dans la premiere partie, l'etude theorique se developpe autour de deux modeles aerodynamiques distincts selon la valeur du rapport de vitesse. L'etude experimentale s'est effectuee avec des machines d'architectures differentes. En particulier nous avons demontre et verifie qu'un rotor darrieus judicieusement concu demarre de lui meme et sous la seule action du vent. Dans la seconde partie, l'etude hydraulique s'est effectuee sur divers prototypes de pompes solenoides. Ces dernieres possedent une cylindree et ne contiennent aucun organe interne excepte les clapets anti-retour
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Delerba, Frédéric. "Modélisation géométrique et mécanique tridimensionnelle du rachis thoracique et lombaire en configuration de choc automobile." Phd thesis, Paris, ENSAM, 2001. http://tel.archives-ouvertes.fr/tel-00005772.
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La thèse " Modélisation mécanique et géométrique tridimensionnelle du rachis thoracique et lombaire en configuration de choc automobile " est une coopération entre le Laboratoire de Biomécanique de l'ENSAM de Paris (LBM) et le Laboratoire d'Accidentologie et Biomécanique (LAB) crée par les constructeurs PSA - Peugeot Citroën - et Renault. Elle porte sur la réalisation d'un modèle numérique du rachis thoracique et lombaire, représenté en position assise, et validé dans le domaine statique et surtout dynamique. Il a pour vocation d'être intégré au sein d'un modèle entier d'" être humain ", ce qui permettra d'améliorer la réponse lésionnelle de ce dernier lors d'une simulation de choc automobile.Le sujet se divise en trois parties : une recherche bibliographique dans laquelle nous avons recensé les articles portant sur les axes instantanés de rotation de segments rachidiens ainsi que les auteurs ayant étudié le comportement expérimental du rachis en dynamique. Enfin, nous avons recensé les articles portant sur la modélisation de la colonne vertébrale et sur la validation de ces modèles ; une partie expérimentale dans laquelle nous avons étudié le comportement dynamique de segments rachidiens thoraciques, thoraco-lombaires et lombaires. Les sollicitations dynamiques, imposées sous forme d'impacts, reproduisent des mouvements purs de flexion, torsion et inflexion. Les influences ligamentaires ont été quantifiées par des sections successives sur chaque spécimen. La volonté d'imposer des couples les plus purs possibles a nécessité la réalisation d'un banc d'essais complémentaire afin de connaître les positions des axes instantanés de rotation des spécimens testés ; une partie modélisation qui consiste à réaliser un modèle " éléments finis " du rachis lombaire et thoracique validé en statique par les données de la littérature et en dynamique par les expérimentations décrites précédemment.
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Cezar, Henrique Musseli. "Implementação e desenvolvimento de algoritmo eficiente para deformação intramolecular com o método Monte Carlo." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-19102018-165856/.
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Com o avanço do poder computacional nas últimas décadas, a modelagem molecular de problemas em diversas áreas se tornou mais acessível, sendo hoje uma ferramenta fundamental para o entendimento de diversos processos. Em especial, simulações moleculares com campos de força clássicos vem sendo importante para a amostragem de propriedades termodinâmicas, para a determinação de estruturas e população de confôrmeros, e seleção de configurações para utilização com métodos que combinam mecânica quântica com mecânica molecular. Os principais métodos de simulação atualmente utilizados são a dinâmica molecular (MD, do inglês molecular dynamics) e o Monte Carlo (MC). Ambos os métodos são a princípio equivalentes quando o objetivo é a amostragem configuracional, tendo a MD a vantagem de permitir a análise da dinâmica e evolução temporal, e o MC a vantagem de poder gerar configurações de forma probabilística, sem a necessidade de seguir um caminho sobre a superfície de energia potencial, o que pode resultar em uma amostragem mais eficiente. Contudo, não há ainda uma metodologia de MC que possa ser considerada eficiente e bem estabelecida para a amostragem dos graus de liberdade internos de moléculas com complexidade arbitrária. Visando avançar no desenvolvimento de métodos que trabalham nesse sentido, neste trabalho o método apresentado por Shah e Maginn [1] foi implementado e aprimorado. No método, a molécula é fragmentada em partes menores, formadas de graus de liberdade rígidos, que não variam drasticamente durante a simulação. Esses fragmentos por sua vez são conectadas por graus de liberdade maleáveis, os diedros e termos não ligados da energia. Durante a simulação a molécula tem fragmentos apagados, e então é reconstruída utilizando um esquema de Configurational Bias Monte Carlo (CBMC). A contribuição deste trabalho para a metodologia consiste em generalizar os tipos de fragmentos possíveis dentro do método, a simplificação do critério de aceitação e extensões com vieses adicionais, como é o caso do viés no potencial eletrostático e no critério de aceitação da amostragem preferencial com o CBMC. A validade da implementação do método foi avaliada através de simulações em dois sistemas simples: o octano e o 1,2-dicloroetano. Comparando a amostragem e os resultados obtidos para as populações de confôrmeros com resultados de MD e experimentais ou obtidos com outros métodos de MC da literatura foi possível verificar que a implementação reproduz os resultados esperados. Além disso, o equilíbrio conformacional da molécula de óxido mesityl (MOx) que possui duas conformações: syn e anti, foi estudado. Graças a barreira de potencial entre as duas conformações de cerca de 10 kcal/mol, a MD não é capaz de realizar uma amostragem ergódica, enquanto o CBMC realiza a amostragem sem problemas. Na simulação CBMC, a inversão da população dominante em fase gasosa e em água foi observada. Simulações do MOx em acetonitrila e metanol mostraram que a população de confôrmeros anti de fato aumenta conforme a polaridade do solvente. Entretanto, devido ao estiramento da ligação C = O do MOx em metanol devido as ligações de hidrogênio, a contribuição conformacional à posição do máximo da banda de absorção não segue a tendência da polaridade, tendo um deslocamento para o azul maior na acetonitrila do que em metanol. O estiramento da ligação C = O só pode ser observado graças a introdução da amostragem de fragmentos com deslocamentos Cartesianos e algoritmo de Metropolis ao método CBMC original. Esse efeito devido ao estiramento é compensado pelo efeito solvente, de modo que a contribuição total à energia de transição segue a polaridade do solvente. De uma maneira geral, concluímos que o desempenho do método CBMC utilizado é excelente para os casos estudados, e é inclusive superior ao da MD em alguns casos. A implementação no software DICE deixa um legado importante para diversos grupos de pesquisa, não somente por introduzir o CBMC, mas também por melhorias gerais como paralelização, lista de vizinhos e modernização do código, que foram introduzidas ao decorrer do projeto.With the increase of computational power in the last decades, the molecular modeling of problems in several areas has become more accessible, being today a fundamental tool used to understand several processes. In particular, molecular simulations with classical force fields have been important for the sampling of thermodynamic properties, for the determination of structures and population of conformers, and for the selection of configurations to be used with methods that combine quantum mechanics with molecular mechanics. The most common simulation methods used nowadays are molecular dynamics (MD) and Monte Carlo (MC). Both methods are in principle equivalent when the goal is configurational sampling, with MD having the advantage of allowing the analysis of the dynamics and temporal evolution, while MC has the advantage of generating the configurations in a probabilistic manner, not necessarily following a path in the potential energy surface, possibly resulting in a more efficient sampling. However, there is no MC methodology that can be considered efficient and established to sample the internal degrees of freedom of molecules with arbitrary complexity. In order to advance in the development of methods that want to achieve this goal, in this work the method presented by Shah e Maginn [1] has been implemented and improved. In the method, the molecule is fragmented into smaller parts, each one composed by the hard degrees of freedom, which do not vary dramatically during the simulation. Those fragments are then connected by soft degrees of freedom, the dihedral and non-bonded terms of the energy. During the simulation the molecule has some of its fragments deleted, and is reconstructed using a Configurational Bias Monte Carlo (CBMC) approach. The contribution of this work to the methodology is generalizing the fragment types within the method, the simplification of the acceptance criteria and some extensions with additional biases, such as electrostatic potential bias and the acceptance criterion of the preferential sampling with the CBMC. The implementation was evaluated through simulations in two simple systems: octane and 1,2-dichloroethane. Comparing the sampling and results obtained for the populations of conformers with MD results, experimental data or values obtained with different MC methods present in the literature, we verified that the implementation reproduces the expected results. Beyond that, the conformational equilibrium of the mesityl oxide (MOx) molecule which has two conformers: syn and anti, was investigated. Due to the potential energy barrier between the two conformers of about 10 kcal/mol, the MD does not perform an ergodic simulation, while the CBMC does the same sampling accordingly. In the CBMC simulation, the inversion of the dominant conformer in gas phase and water was observed. The MOx simulation in acetonitrile and methanol showed that the frequency of the anti conformer indeed increases with the solvent polarity. Nonetheless, due to the stretch of the C = O bond of MOx in methanol, attributed to the hydrogen bonds formed with the solvent, the conformational contribution to the maximum of the absorption band does not follow the polarity tendency, having a larger blue shift in acetonitrile than in methanol. The C = O bond stretch can only be seen because the Cartesian displacement sampling with the Metropolis method was introduced to the original CBMC method. This effect attributed to the stretch is compensated by the solvent, in a way that the total contribution to the transition energy follows the solvent polarity. In general, we conclude that the performance of the developed CBMC method is excellent to the studied cases, being even superior to MD in some cases. The implementation in DICE leaves an important legacy to several research groups, not only for introducing the CBMC method, but also due to general improvements such as parallelization, neighbor list and code modernization, which were introduced during the project.
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Ballard, Andrew. "Kinetics and mechanism of H D exchange reactions and racemisation in aqueous solutions : configurational stability of ester and amide arylglycine derivatives." Thesis, Cardiff University, 2011. http://orca.cf.ac.uk/55130/.
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The configurational stability of a range of stereogenic centres in aqueous media has been studied, with the goal of understanding the structural and environmental factors contributing to configurational instability. This information will be of use to the pharmaceutical industry, for which the chiral integrity of drug compounds is imperative. Chapter 1 outlines the background to this project, providing an overview of pharmacological racemisation including potential mechanisms, examples from literature, and the methodology used. Chapter 2 focuses on database mining studies undertaken on AstraZeneca compound libraries, the results of which guided the structures investigated in the rest of the thesis. Most compounds in the libraries do not appear at risk of racemisation. Of those that do, stereogenic centres with proton, carbonyl, aromatic and nitrogen substituents appear most frequently. Chapter 3 discusses experimental work determining rate constants of proton-deuterium exchange (as a model for racemisation) under physiological conditions, for a set of TV-acetyl arylglycine methyl esters. These rate constants suggest that such compounds are susceptible to in vivo racemisation through an SeI mechanism. Chapter 4 outlines experimental work determining rate constants of proton-deuterium exchange, for a set of N-substituted phenylglycine amides. These compounds undergo H/D exchange through an SeI mechanism, although the rate at which H/D exchange occurs suggests they would not be at risk of in vivo racemisation. These results show that an amide substituent is far weaker than a methyl ester in facilitating racemisation. Chapter 5 reports the results of computational studies performed on the compounds investigated in Chapters 3 and 4. The energy gap between a molecule and its anion when deprotonated at the stereogenic centre was correlated with the experimentally determined data, suggesting that prediction of configurational instability for novel compounds may be possible. This correlation only holds when the PCM solvent model is used in calculations.
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Da, Silva Veith Alexandre. "Quality of Service Aware Mechanisms for (Re)Configuring Data Stream Processing Applications on Highly Distributed Infrastructure." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSEN050/document.
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Une grande partie de ces données volumineuses ont plus de valeur lorsqu'elles sont analysées rapidement, au fur et à mesure de leur génération. Dans plusieurs scénarios d'application émergents, tels que les villes intelligentes, la surveillance opérationnelle de grandes infrastructures et l'Internet des Objets (Internet of Things), des flux continus de données doivent être traités dans des délais très brefs. Dans plusieurs domaines, ce traitement est nécessaire pour détecter des modèles, identifier des défaillances et pour guider la prise de décision. Les données sont donc souvent rassemblées et analysées par des environnements logiciels conçus pour le traitement de flux continus de données. Ces environnements logiciels pour le traitement de flux de données déploient les applications sous-la forme d'un graphe orienté ou de dataflow. Un dataflow contient une ou plusieurs sources (i.e. capteurs, passerelles ou actionneurs); opérateurs qui effectuent des transformations sur les données (e.g., filtrage et agrégation); et des sinks (i.e., éviers qui consomment les requêtes ou stockent les données). Nous proposons dans cette thèse un ensemble de stratégies pour placer les opérateurs dans une infrastructure massivement distribuée cloud-edge en tenant compte des caractéristiques des ressources et des exigences des applications. En particulier, nous décomposons tout d'abord le graphe d'application en identifiant quelques comportements tels que des forks et des joints, puis nous le plaçons dynamiquement sur l'infrastructure. Des simulations et un prototype prenant en compte plusieurs paramètres d'application démontrent que notre approche peut réduire la latence de bout en bout de plus de 50% et aussi améliorer d'autres métriques de qualité de service. L'espace de recherche de solutions pour la reconfiguration des opérateurs peut être énorme en fonction du nombre d'opérateurs, de flux, de ressources et de liens réseau. De plus, il est important de minimiser le coût de la migration tout en améliorant la latence. Des travaux antérieurs, Reinforcement Learning (RL) et Monte-Carlo Tree Searh (MCTS) ont été utilisés pour résoudre les problèmes liés aux grands nombres d’actions et d’états de recherche. Nous modélisons le problème de reconfiguration d'applications sous la forme d'un processus de décision de Markov (MDP) et étudions l'utilisation des algorithmes RL et MCTS pour concevoir des plans de reconfiguration améliorant plusieurs métriques de qualité de serviceA large part of this big data is most valuable when analysed quickly, as it is generated. Under several emerging application scenarios, such as in smart cities, operational monitoring of large infrastructure, and Internet of Things (IoT), continuous data streams must be processed under very short delays. In multiple domains, there is a need for processing data streams to detect patterns, identify failures, and gain insights. Data is often gathered and analysed by Data Stream Processing Engines (DSPEs).A DSPE commonly structures an application as a directed graph or dataflow. A dataflow has one or multiple sources (i.e., gateways or actuators); operators that perform transformations on the data (e.g., filtering); and sinks (i.e., queries that consume or store the data). Most complex operator transformations store information about previously received data as new data is streamed in. Also, a dataflow has stateless operators that consider only the current data. Traditionally, Data Stream Processing (DSP) applications were conceived to run in clusters of homogeneous resources or on the cloud. In a cloud deployment, the whole application is placed on a single cloud provider to benefit from virtually unlimited resources. This approach allows for elastic DSP applications with the ability to allocate additional resources or release idle capacity on demand during runtime to match the application requirements.We introduce a set of strategies to place operators onto cloud and edge while considering characteristics of resources and meeting the requirements of applications. In particular, we first decompose the application graph by identifying behaviours such as forks and joins, and then dynamically split the dataflow graph across edge and cloud. Comprehensive simulations and a real testbed considering multiple application settings demonstrate that our approach can improve the end-to-end latency in over 50% and even other QoS metrics. The solution search space for operator reassignment can be enormous depending on the number of operators, streams, resources and network links. Moreover, it is important to minimise the cost of migration while improving latency. Reinforcement Learning (RL) and Monte-Carlo Tree Search (MCTS) have been used to tackle problems with large search spaces and states, performing at human-level or better in games such as Go. We model the application reconfiguration problem as a Markov Decision Process (MDP) and investigate the use of RL and MCTS algorithms to devise reconfiguring plans that improve QoS metrics
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Олексієвич, Андрій Мирославович, and Andriy Oleksiievych. "Дослідження верстату пірамідальної компоновки на основі механізмів паралельної структури." Master's thesis, Тернопільський національний технічний університет імені Івана Пулюя, 2018. http://elartu.tntu.edu.ua/handle/lib/26996.
Full textAbstract:
In the thesis of the master the analysis of development of configurations of machines with mechanisms of parallel structure is carried out. The main ways of shaping of surfaces of a detail like "Case" are considered and technological process of its production is developed. Development of configuration of the machine of pyramidal configuration and a design of its main knots is carried out. The research of kinematics of mechanisms of parallel structure is conducted. The developed practical recommendations about improvement of boring-and-milling machines with mechanisms of parallel structure. The offered designs of frame configurations of machines with mechanisms of parallel structure. Done technical and economic feasibility of technical solutions. Thesis work includes issues related to the industrial safety, human ecology and the safety of human life.Метою роботи є оцінка стану розвитку верстатів з механізмами паралельної структури та розробка їх нових конструкцій з покращеними технологічними можливостями. В дипломній роботі магістра здійснено аналіз розвитку компонувань верстатів з механізмами паралельної структури. Розглянуто основні способи формоутворення обробки поверхонь деталі типу «Корпус» та розроблено технологічний процес її виготовлення. Здійснено розробку компонування верстату пірамідальної компоновки, розроблено конструкції її основних вузлів. Здійснено дослідження кінематики механізмів паралельної структури. Розроблені практичні рекомендації по удосконаленню свердлильно-фрезерних верстатів з МПС. Запропоновані конструкції каркасних компоновок верстатів з МПС. Вирішені питання техніко-економічного обґрунтування прийнятих технічних рішень. Також розкриті питання охорони праці та безпеки в надзвичайних ситуаціях, екології.
Вступ; Аналітичний розділ; Оптимізація схем формоутворення на проектованому верстаті і оптимізація його компоновки; Вибір та обгрунтування вихідних даних на розробку верстатного обладнання. Технологічний розрахунок.; Проектування конструкції верстатного обладнання; Спеціальна частина; Науково-дослідний розділ; Обгрунтування економічної ефективності; Охорона праці та безпека в надзвичайних ситуаціях; Екологія ; Висновки.
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Jarman, Ben. "Essays in optimal auction design." University of Sydney, 2008. http://hdl.handle.net/2123/4627.
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Doctor of Philosophy (Economics)Auctions are an ancient economic institution. Since Vickrey (1961), the development of auction theory has lead to an extremely detailed description of the often desirable characteristics of these simple selling procedures, in the process explaining their enduring popularity. Given the pervasiveness of auctions, the question of how a seller should engineer the rules of these mechanisms to maximize her own profits is a central issue in the organization of markets. The seminal paper of Myerson (1981) shows that when facing buyers with Independent Private Values (IPVs) a standard auction with a specifically selected reserve price (or prices) is optimal, that is, maximizes a seller's expected profits among all conceivable selling mechanisms. In this model, it is assumed that the buyers have perfect information as to the existence of gains from trade. We shall argue that the consequences of this assumption for the design of the optimal auction are not well understood, which motivates our analysis. The three essays of this thesis relax the `known seller valuation' assumption by examining the optimal auction program when the seller (and principal) holds private information representing her reservation value for the good. In the first essay we provide an original technique for comparing ex ante expected profits across mechanisms for a seller facing N>1 potential buyers when all traders hold private information. Our technique addresses mechanisms that cannot be ranked point-by-point through their allocation rules using the Revenue Equivalence Theorem. We find conditions such that the seller's expected profits increase in the slope of each buyer's allocation probability function. This provides new intuition for the fact that a principal does not benefit from holding private information under risk neutrality. Monopoly pricing induces steep probability functions so the seller/principal benefits from announcing a fixed price, and implicitly her private information. An application is presented for the well known k double auction of the bilateral trade literature. In the second and third essays of this thesis, we extend the above framework to allow for informational externalities. Specifically, we allow for the situation in which the seller's private information represents a common value component in buyers' valuations. Thus the seller's private information (say regarding the quality of the good) is of interest to bidders independently of any strategic effects. In recent work Cai, Riley and Ye (2007) have demonstrated that a seller who holds private information about the quality of a good faces an extra consideration in designing an auction; the reserve price signals information to bidders. In a separating equilibrium signalling is costly in the sense that reserves are higher than would be optimal under complete information. We examine the returns to the seller in an English auction from using different types of secret reserve regimes. We find that immediate disclosure of a reserve is preferable to announcement after the auction in the form of a take-it-or-leave-it offer to the winning bidder. Sale occurs less often during the auction for a given reserve price strategy under secret reserve regimes, which increases the incentive for the seller to report more favourable information though the reserve price offer. Separating equilibria involving later announcement therefore generate even lower expected profits to the seller (signalling is more costly) than under immediate disclosure. In the third essay we compare the benchmark signalling equilibrium of immediate disclosure to a screening regime which we call the Right of Refusal. In this extreme form of a secret reserve the seller never announces the reserve price, she simply accepts or rejects the auction price. We find that the Right of Refusal dominates immediate disclosure if the seller's valuation is a sufficient statistic for the private information of interest. Thus a seller with market-relevant private preference information can benefit from not exercising monopoly price setting power. The result also provides conditions under which a competitive screening equilibrium is more efficient than a signalling mechanism. Broadly speaking, screening is better when the common value aspect in the preferences of the informed and uninformed parties are `aligned', and potential gains from trade to the uninformed party are significant. We believe this conclusion to be of particular interest to the design of privatization schemes.
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Pain, R. "Simulation numérique, analyse physique et contrôle d'écoulements massivement décollés. Application au buffeting culot et à l'ovalisation de la tuyère sur des configurations de lanceur." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2013. http://tel.archives-ouvertes.fr/tel-01009854.
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Le développement de l'accès à l'espace s'inscrit dans le contexte scientifique et économique actuel comme un enjeu majeur de l'industrie et de la recherche. Un des objectifs principaux est d'augmenter la capacité et le confort de la charge utile pour réduire les coûts de transport vers l'espace. L'exploitation des données en vol du lanceur Ariane 5 a mis en évidence la présence de fluctuations de pression pouvant induire des efforts instationnaires repris par les vérins du moteur Vulcain. Ces efforts s'exercent dans la zone décollée du culot d'un lanceur normalement à l'axe de la poussée, et sont qualifiés de charges latérales. Cette observation conduit à l'étude de deux aspects. Dans un premier temps, la dynamique des écoulements massivement décollés d'arrière-corps, à haut nombre de Reynolds et en régime compressible est considérée au moyen de simulations numériques ZDES. Une analyse approfondie des champs instantanés, moyens et fluctuants est réalisée au moyen de post-traitements avancés. Notamment, le champ tri-dimensionnel de pression fluctuante dans la région du culot fait l'objet d'analyses spectrales (Fourier) et modales (DMD) massives. Ensuite, le contrôle des phénomènes potentiellement nuisibles au confort de la charge utile à savoir le buffeting culot et l'ovalisation de tuyère est abordé. L'analyse physique de l'écoulement sur une géométrie tri-corps permet la conception d'un dispositif de contrôle adapté. Enfin, l'effet de deux dispositifs retenus (quatre jets équirépartis en azimut sur le corps central et augmentation de la section de passage entre les trois corps) est évalué au moyen des outils d'analyse de la dynamique de la configuration non contrôlée.
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Poling, Dana B. "Spherically-actuated platform manipulator." Ohio : Ohio University, 2000. http://www.ohiolink.edu/etd/view.cgi?ohiou1172775949.
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Ambrozková, Anna. "Geometrické struktury a objekty z hlediska aplikací v mechanice." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-417093.
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This Master's thesis relates to continuum mechanics and its connection with selected directions of modern differential geometry, which deal with geometric structures and objects. These are mainly tensors, bundles, varieties and jets. The first part is devoted to the mechanics of the continuum itself and its description in several areas, others deal with mathematical concepts and their possible application in mechanics.
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Karakoc, Ali. "Multi-disciplinary Design And Optimization Of Air To Surface Missiles With Respect To Flight Performance And Radar Cross Sectio." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613903/index.pdf.
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This study focuses on the external configuration design of a tactical missile based on maximizing flight range while minimizing the radar signature which is a crucial performance parameter for survivability. It is known that shaping of a missile according to aerodynamic performance may have significant negative effects on the radar cross section. Thus, the impact of the geometry changes on the aerodynamic performance and the radar cross section is investigated. Suggorage models for the flight range, control effectiveness and the radar cross section (RCS) at an X band frequency are established by employing Genetic Algorithm. Accuracies of surrogate models are discussed in terms of statistical parameters. Seventeen geometrical parameters are considered as the design variables. Optimum combinations for the design variables are sought such that flight range is
maximized while the radar cross section is minimized. The multi objective optimization problem is solved by imposing the static stability margin as a hard nonlinear constraint. Weighted sum approach is utilized to compare results with known missile configurations. Weights for flight range and Radar Cross Section are varied to obtain Pareto optimal solutions.
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Boutalib, Abderrahim. "Etude théorique de la surface de potentiel du système HO::(2) + H. : Influence de la corrélation électronique." Pau, 1986. http://www.theses.fr/1986PAUU3009.
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Calcul des géométries du points de sille et des barrières d'activation pour les réactions d'abstraction (HO::(2) + H->H::(2) + O::(2)) et d'approche concertée (HO::(2) + H->H::(2)O + O) pour la méthode SDCI à l'ordre d'une base DZ dans la région de valence, augmentée par des orbitales de polarisation de type D sur chaque atome O. Evaluation des paramètres cinétiques dans le cadre de la théorie de l'état de transition : énergies d'activation et constantes de vitesse. Faible probabilité du mécanisme de réaction concertée
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Buck, Dietrich. "Mechanics of Cross-Laminated Timber." Licentiate thesis, Luleå tekniska universitet, Träteknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-68729.
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Increasing awareness of sustainable building materials has led to interest in enhancing the structural performance of engineered wood products. Wood is a sustainable, renewable material, and the increasing use of wood in construction contributes to its sustainability. Multi-layer wooden panels are one type of engineered wood product used in construction. There are various techniques to assemble multi-layer wooden panels into prefabricated, load-bearing construction elements. Assembly techniques considered in the earliest stages of this research work were laminating, nailing, stapling, screwing, stress laminating, doweling, dovetailing, and wood welding. Cross-laminated timber (CLT) was found to offer some advantages over these other techniques. It is cost-effective, not patented, offers freedom of choice regarding the visibility of surfaces, provides the possibility of using different timber quality in the same panel at different points of its thickness, and is the most well-established assembly technique currently used in the industrial market. Building upon that foundational work, the operational capabilities of CLT were further evaluated by creating panels with different layer orientations. The mechanical properties of CLT panels constructed with layers angled in an alternative configuration produced on a modified industrial CLT production line were evaluated. Timber lamellae were adhesively bonded in a single-step press procedure to form CLT panels. Transverse layers were laid at a 45° angle instead of the conventional 90° angle with respect to the longitudinal layers’ 0° angle. Tests were carried out on 40 five-layered CLT panels, each with either a ±45° or a 90° configuration. Half of these panels were evaluated under bending: out-of-plane loading was applied in the principal orientation of the panels via four-point bending. The other twenty were evaluated under compression: an in-plane uniaxial compressive loading was applied in the principal orientation of the panels. Quasi-static loading conditions were used for both in- and out-of-plane testing to determine the extent to which the load-bearing capacity of such panels could be enhanced under the current load case. Modified CLT showed higher stiffness, strength, and fifth-percentile characteristics, values that indicate the load-bearing capacity of these panels as a construction material. Failure modes under in- and out-of-plane loading for each panel type were also assessed. Data from out-of-plane loading were further analysed. A non-contact full-field measurement and analysis technique based on digital image correlation (DIC) was utilised for analysis at global and local scales. DIC evaluation of 100 CLT layers showed that a considerable part of the stiffness of conventional CLT is reduced by the shear resistance of its transverse layers. The presence of heterogeneous features, such as knots, has the desirable effect of reducing the propagation of shear fraction along the layers. These results call into question the current grading criteria in the CLT standard. It is suggested that the lower timber grading limit be adjusted for increased value-yield. The overall experimental results suggest the use of CLT panels with a ±45°-layered configuration for construction. They also motivate the use of alternatively angled layered panels for more construction design freedom, especially in areas that demand shear resistance. In addition, the design possibility that such 45°-configured CLT can carry a given load while using less material than conventional CLT suggests the potential to use such panels in a wider range of structural applications. The results of test production revealed that 45°-configured CLT can be industrially produced without using more material than is required for construction of conventional 90°-configured panels. Based on these results, CLT should be further explored as a suitable product for use in more wooden-panel construction.External cooperation: Martinson Group AB and Research Institutes of Sweden (RISE)
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BELLOSTA, DECHAVANNE VERONIQUE. "Contribution a l'etude de la reactivite de derives glucidiques vis-a-vis d'organometalliques : nouvelles syntheses stereospecifiques de c-glycosides." Paris 6, 1987. http://www.theses.fr/1987PA066256.
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Deux nouvelles methodes de syntheses stereospecifiques de desoxy-2 c-glucosides possedant une fonction ester d'enol sont presentees : - l'addition conjuguee d'organocuprates cyanes sur des hexeno-1 pyrannuloses-3 peracetyles (l'anhydride acetique piegeant l'enolate intermediaire) permet d'obtenir des aryl-alpha -d-c-glycosides. Cette methode est detendue avec succes en serie furannose; - l'arylation de glycals catalysee par des sels de palladium fournit les composes voulus en une seule etape a partir de derives glucidiques commerciaux. L'etude de la configuration des c-glycosides obtenus est effectuee et de nombreuses donnees structurales sont exposees
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WU, LONG-YONG, and 吳隆庸. "On the singular configurations of planar linkage mechanisms." Thesis, 1987. http://ndltd.ncl.edu.tw/handle/60383199890501186363.
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Lai, Ying-Ren, and 賴盈任. "Computational Studies of the Adsorption Configurations and Dehydrogenation Mechanisms of Ethanol on the Rh/γ-Al2O3(110) Surface." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/47155491079969183630.
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碩士國立臺灣師範大學
化學系
95
We applied periodic density-functional theory (DFT) to investigate the adsorption configurations and decomposition paths of ethanol on a Rh/γ-Al2O3(110) surface. Adsorption of ethanol onto a Al atom in the surface performs a larger adsorption energy than it adsorbed onto a Rh atom. But it is well known that the acidic support, γ-Al2O3 promotes dehydration of ethanol to ethylene. Therefore, we consider another ethanol adsorption configuration for the calculation of ethanol dehydrogenation pathways. In this configuration, ethanol adsorbed onto a Rh via α-cabon, two α-hydrogen atoms from ethanol are first eliminated; the barriers for abstraction of this two α-hydrogen atoms are calculate to be 2.59 and 7.35 kcal/mol, respectively. The dehydrogenation continues with the loss of one hydrogen from the O-H, forming an intermediate species CH3C(a)O + 3H(a), for which the successive barrier is 10.13 kcal/mol. Cleavage of the C-C bond occurs at this stage with a dissociation barrier Ea = 12.06 kcal/mol, to form C(a)H3 + C(a)O + 3H(a). The aforementioned reaction mechanism was also proposed and discussed by experiment.
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Pan, Meng-Ching, and 潘孟青. "Computational Study on Decomposition Mechanisms of Cyanomidyl Radical with Doublet and Quartet Configurations, and the RCCN (R = H, F, Cl, Br, CN, NH2, CH3) Substituted Radicals React with NO." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/42451309249518944746.
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碩士中國文化大學
應用化學研究所
99
The reaction mechanisms of (1) the decomposition reaction of cyanomidyl radical (HNCN), and (2) the reaction of RCCN (R=H, F, Cl, Br, CN, NH2, and CH3) radicals with the NO have been investigated by the highlevel ab initio molecular orbital method. The species involved have been optimized at the B3LYP/6-311++G (3df,2p) level and their singlepoint energies are refined by the CCSD(T)/aug-cc- PVQZ//B3LYP /6-311+G(3df,2p) method. For the HNCN decomposition reaction system with two different configurations (doublet and quartet states), our calculated results indicate that there exists two and three favorable paths for the formations of CH + N2. For doublet state case, these two paths are HNCN→TS1→IM4→TS4→ IM2→TS8→CH+N2, and HNCN→TS3→ IM1→TS2→IM2→TS8→CH+N2, respectively. For quartet state case, these three paths are R→TS4→IM5→TS5→IM2→TS7→IM3→TS12→ CH+N2, R→TS9→IM4→TS13→IM1→TS11→IM3→TS12→CH+N2, and R→TS4→IM5→TS10→IM1→TS11→ IM3→TS12 →CH+N2, respectively. In addition, employing the Fukui functions and HSAB theory we are able to rationalize the scenario of these calculated outcomes. For the reaction of RCCN (R=H, F, Cl, Br, CN, NH2, and CH3) radicals with the NO system, our calculated results clearly show that if the substituted RCCN are electron donating groups (for R = F, NH2 and CH3 cases), their corresponding barrier heights for transition states will be slightly decreased. The possible explanations for the decreased and/or increased energy barriers of the substituted RCCN are also analyzed in this part.
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楊義成. "Mechanism configuration synthesis and." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/50861797216011162404.
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Liu, Nien-Te, and 劉念德. "Configuration Synthesis of Mechanisms with Variable Chains." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/15041717110972569961.
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博士國立成功大學
機械工程學系
89
Mechanisms can be classified into the following three types according to the topological structures: closed chains, open chains, and variable chains. In the past years, there have been some important articles regarding the configuration synthesis of the mechanisms with closed chains or open chains. However, the method for synthesizing mechanisms with variable chains has not been available. The designers usually design basing on the experiences and inspiration. Therefore, the purpose of this work is to provide a systematic design methodology for mechanisms with variables chains. This work starts by classifying mechanisms and investigating the mechanisms with variables chains. Then, the variable joints using on the mechanisms with variable joints are studied and defined. Including revolute joints, prismatic joints, cam joints, fixed joints, and separated joints, are illustrated. Four representations, mechanism topology matrix, graphs, joint codes, and finite state machine, are provided for presenting and analyzing the mechanisms with variable chains. By reviewing and modifying the methodology for the configuration synthesis of mechanisms with closed or open chains, a methodology for configuration synthesis of mechanisms with variable chains is provided and the can-opener is taken as an example to illustrating the procedure. Finally, the double-dwell slider-crank mechanism, the stopper mechanical lock, and the antenna deployment mechanism are taken as examples to verify the feasibility of the methodology, 7 new double-dwell slider-crank mechanisms, 5 new stopper mechanical lock, and 7 new deployment mechanisms are obtained. The method provided by this work is not only used in mechanisms with variable chains, but also can be used in mechanisms with closed chains or open chains. The result of this work is necessary for concept evaluation, detail design, and patent application.
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Kang, Chen-Hsiung, and 康振雄. "Configuration Synthesis of Mechanisms with Variable Topologies." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/05962348600494125289.
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博士國立成功大學
機械工程學系碩博士班
96
Mechanisms with multiple topological structures during the operation process are called mechanisms with variable topologies (MVTs), and their corresponding kinematic chains are called variable chains. The kinematic joints whose types and/or motion orientations are changeable during the operation process of an MVT are called variable joints. The MVTs are usually designed for satisfying multiple design requirements. This work presents a systematic design methodology for MVTs and determines the variability configurations of mechanisms subject to the design requirements at each stag. First, locutions of mechanisms with multiple configurations including kinematotropic, metamorphic, discontinuously movable mechanisms, and MVTs are introduced. Then, the topological characteristics of variable joints subject to input motions are investigated. The operation as well as its principles are defined, and the concept of mapping functions of variable joints is provided. A mapping function method is provided to describe the topological characteristics of mechanisms and to determine the relationships of mechanism configurations between different stages. Moreover, fundamental synthesizing corollaries are established. Then, the concept of the simplified unified graph that represents topological changes in an MVT is used to address the configuration of MVTs. A sawing mechanism and a mechanical lock with variable passwords are exemplified to analyze their topological characteristics and configuration transformations of MVTs. Finally, according to the fundamental concepts, simplified unified graph, coordinate sequence, and mobility criterion at each stage, a design methodology is proposed for the configuration synthesis of MVTs. A mechanical lock with invariable passwords, a sawing mechanism, and a mechanical lock with variable passwords are exemplified to verify the feasibility of the design methodology. And, one new mechanical lock with invariable passwords, twenty-three new sawing mechanisms, and five new mechanical locks with variable passwords are obtained.
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Yang, Yi-Chen, and 楊義成. "Mechanism Configuration Synthesis and Machining Analysis." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/99089271632265774362.
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博士國立成功大學
機械工程學系
88
The purpose of this paper is to investigate the characteristics of wire-cut electric discharge machines in all respects, including: mechanism configuration synthesis, machining error analysis and algorithm for CAD/CAM system. Firstly, the mechanism configuration synthesis for wire-cut EDM machine is proposed. The mechanism tree-graph representations are introduced to conclude the topology and motion characteristics of wire-cut EDM. The design requirements are studied and the structure configurations are synthesized. The design process starts by investigating existing mechanisms and concludes their topology and motion characteristics. The second step is to describe the topology structures of existing mechanisms. The third step is to transform these mechanisms into their corresponding generalized tree graphs. The fourth step is to obtain all possible tree graph. The fifth step is to assign certain type of links and joints. Finally, the atlas mechanisms are obtained. As the result, for the wire-cut EDM machine, the number of possible configurations is 248. Secondly, using the Denavit-Hartenburg matrix to describe the motion of the wire and to generate the function of the ruled surface. Then, applied the error of each link and joint to analysis the error matrix of each link. Finally, using the differential method to calculate the machining error. Two examples are shown to compare the current mechanism and new mechanism synthesized from chapter 3. Finally, this paper proposes a CAD/CAM mathematical foundation to design ruled surfaces for wire-cut EDM. This method combines the boundary plane concept, the Plucker coordinate representation of lines, control lines and design function to generate free form ruled surfaces. The tool motion and offset surface can also be generated simply by the same approach for computer numerical control (CNC) wire-cut EDM. The algorithm, being different from conventional methods, can present a surface or tool path concisely and uniquely.
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陳福成. "Mechanism configuration synthesis of machining centers." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/31016292246842966408.
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Lin, Dong-Lei, and 林東磊. "Automated Network Mechanism Testing Configuration Tools." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/dta8g7.
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碩士中原大學
資訊工程研究所
104
Performing adequate network experiments is important in developing new network mechanisms or network security systems. However, setting up a high-fidelity testing environment is a complicated task and requires a lot of considerations in details. In this thesis, we proposed a set of tools to assist users to automate the process of setting up network testing environments and regenerate the corresponding network activities according to the network traffic records provided by the users. The tool consists of two components: One is the configuration component which analyzes a given network traffic record to obtain relevant network topology information and map the topology to the targeted testing platform. The other is the background traffic generator which regenerates the network activity specified in the same network traffic record. The proposed tool set reduces the burden of the user in designing and carry out network experiments and allow the users to concentrate their effort on the development of new mechanisms.
50
Lin, Hun-shung, and 林宏舜. "Configuration Synthesis of Static Balancing Mechanism." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/83715325427864051582.
Full textAbstract:
碩士國立臺灣大學
機械工程學研究所
88
The static balancing mechanism is a mechanism, which balances the weight of objects via springs. Such as supporting frames and surgical lights, SCM is broadly applied to support and pick-and-place objects. To ensure the safety of the objects in manufacture process, the static balancing mechanism can be balanced at arbitrary rest configuration and moves objects stably without aids of actuators. The design of SCM can be separated into two sections, the configuration synthesis and the spring-design. Since there is no systematic procedure about the configuration synthesis, the configuration is always four-bar parallelogram mechanism. A systematic design procedure for one-dof four- and six-link static balancing mechanisms is developed in this study. Structural characteristics for the two-link static balancing mechanism are investigated, from which general structural characteristics for up-to-six link static balancing mechanisms can be generated. According to these structural characteristics, an atlas of valid configurations for up-to-six link static balancing mechanisms is obtained. It will be shown that a static balancing mechanism can be synthesized by connecting multiple one-dof static balancing mechanisms to adapt to versatile design requirements. It is believed that the proposed approach provides better physical comprehension in the design process and is beneficial to extent the application of static balancing mechanisms.