To see the other types of publications on this topic, follow the link: Mechanisms design.
Dissertations / Theses on the topic 'Mechanisms design'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Mechanisms design.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Chen, Yan. "Design of structural mechanisms." Thesis, University of Oxford, 2003. http://ora.ox.ac.uk/objects/uuid:6423e5a6-5438-496a-835d-242fe1d5cd97.
Full textAbstract:
In this dissertation, we explore the possibilities of systematically constructing large structural mechanisms using existing spatial overconstrained linkages with only revolute joints as basic elements. The first part of the dissertation is devoted to structural mechanisms (networks) based on the Bennett linkage, a well-known spatial 4R linkage. This special linkage has been used as the basic element. A particular layout of the structures has been identified allowing unlimited extension of the network by repeating elements. As a result, a family of structural mechanisms has been found which form single-layer structural mechanisms. In general, these structures deploy into profiles of cylindrical surface. Meanwhile, two special cases of the single-layer structures have been extended to form multi-layer structures. In addition, according to the mathematical derivation, the problem of connecting two similar Bennett linkages into a mobile structure, which other researchers were unable to solve, has also been solved. A study into the existence of alternative forms of the Bennett linkage has also been done. The condition for the alternative forms to achieve the compact folding and maximum expansion has been derived. This work has resulted in the creation of the most effective deployable element based on the Bennett linkage. A simple method to build the Bennett linkage in its alternative form has been introduced and verified. The corresponding networks have been obtained following the similar layout of the original Bennett linkage. The second effort has been made to construct large overconstrained structural mechanisms using hybrid Bricard linkages as basic elements. The hybrid Bricard linkage is a special case of the Bricard linkage, which is overconstrained and with a single degree of mobility. Starting with the derivation of the compatibility condition and the study of its deployment behaviour, it has been found that for some particular twists, the hybrid Bricard linkage can be folded completely into a bundle and deployed to a flat triangular profile. Based on this linkage, a network of hybrid Bricard linkages has been produced. Furthermore, in-depth research into the deployment characteristics, including kinematic bifurcation and the alternative forms of the hybrid Bricard linkage, has also been conducted. The final part of the dissertation is a study into tiling techniques in order to develop a systematic approach for determining the layout of mobile assemblies. A general approach to constructing large structural mechanisms has been proposed, which can be divided into three steps: selection of suitable tilings, construction of overconstrained units and validation of compatibility. This approach has been successfully applied to the construction of the structural mechanisms based on Bennett linkages and hybrid Bricard linkages. Several possible configurations are discussed including those described previously. All of the novel structural mechanisms presented in this dissertation contain only revolute joints, have a single degree of mobility and are geometrically overconstrained. Research work reported in this dissertation could lead to substantial advancement in building large spatial deployable structures.
2
Douglas, Graeham Rees. "Design of stent expansion mechanisms." Thesis, University of British Columbia, 2012. http://hdl.handle.net/2429/42137.
Full textAbstract:
Stents are widely used in the treatment of vascular disease and they represent one of the most valuable medical device markets. It has been observed that the mechanical characteristics of a stent influences clinical outcomes.
This thesis is concerned with the design of expansion mechanisms of balloon expandable stents based on the principles of lattice mechanics. Balloon expandable vascular stents are mesh-like, tubular structures used mainly to prop open narrowed arteries, and also to provide sealing and anchorage in a stent-graft for treatment of aneurysms or dissections. Presence of a spatially repeating geometric pattern of a `unit' or a cell is a striking feature of stents. Lattice mechanics deals with such spatially periodic materials and structures.
The focus is on the plastic expansion phase of a stent from the initial crimped configuration. The elastic post-expansion phase is also considered. Eight unit cell-based stent designs are selected for this work. Their expansion characteristics are analyzed and measured. Analytical methods based on kinematics of stent expansion mechanisms are presented first which are then validated with more detailed Finite Element (FE) calculations. Analytical methods developed in this work aid rapid design calculations in selecting appropriate unit cell geometries. Three of the designs are manufactured through laser micromachining and tested for their expansion characteristics.
The analytical methods were validated as they predicted similar expansion characteristics as finite element and experiment. Additionally, the study confirmed that stent designs with positive, negative, or zero axial strain over expansion is possible. Finally, the study suggest that unit cell design can be tailored to obtain desired length-diameter and pressure-diameter characteristics over the expansion phase of stenting.
3
Can, Fatih Cemal. "Inertial Parameter Design Of Spatial Mechanisms." Master's thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/1254895/index.pdf.
Full textAbstract:
In this thesis, the inertial parameters of a spatial mechanism are used in order to optimize various aspects of the dynamic behaviour of the mechanism (such as minimizing actuator torque/ force fluctuations, shaking force/moment balancing, etc.) while the effects of loads are considered as well. Here, inertial parameters refer to the mass, 6 elements of the inertia tensor and coordinates of the center of mass of the links.
The concept of Force Fluctuation Number (FFN) is utilized to optimize the dynamic behaviour of the mechanism. By using the FFN concept, one obtains a number of linear equations to be satisfied by the optimal inertial parameters. In general, the number of such equations is less than the number of the inertial parameters. Therefore, some of the inertial parameters may be selected freely in order to satisfy other design constraints.
Using MATHEMATICA, a program has been developed to obtain the linear equations to be satisfied by the optimal inertial parameters. The developed program includes a kinematic and force analysis module, which
can be used independently for a complete kinematic and dynamic analysis of any one degree of freedom, single loop, spatial mechanism. The different closures of the mechanism may be identified by using the developed package and these analyses can be performed on any selected closure of the mechanism.
4
Demir, Eralp. "Kinematic Design Of Mechanisms In A Computer Aided Design Environment." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606012/index.pdf.
Full textAbstract:
CADSYN (Computer Aided Design SYNthesis) is a visual, interactive computer
program working under Computer Aided Design (CAD) enviroment, which
accomplishes the synthesis and analysis of planar four-bar mechanisms. The
synthesis tasks are motion generation, path generation and function generation.
During synthesis, the dyadic approach is utilized which introduces vector pairs and
complex number algebra to model the motion. The possible solutions can be limited
for link dimensions, the center circle point curves within a certain region,
transmission angle characteristics, branch and order defects. The designed
mechanism can be analyzed for velocity, acceleration and transmission angle and any
of the data can be exported to Excel®for further analysis. The software is designed to provide the user maximum feasible number of solutions. In four multiply separated position synthesis, if there is flexibility in the value(s) of one or any number of input parameter(s), designer can obtain different Burmester curves by changing those parameter(s). Designer can also simulate the kinematics of the mechanism by using drawing functions that are available from the CAD iv enviroment at any time. Drawing parts in the design plane can be attached to any link of the mechanism and can be simulated throughout the motion as part of the link it is attached. As a whole, this computer program is designed to satisfy the needs of mechanism designers while working in CAD enviroment.
5
Chen, Li. "Information and Preferences in Matching Mechanisms." Doctoral thesis, Universite Libre de Bruxelles, 2016. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/235227.
Full textAbstract:
This thesis consists of three independent essays on the design of matching markets, with a primary goal to understand how information interacts with matching mechanisms especially in the applications to school choice and college admissions. The first chapter compares theoretically the non-strategyproof Boston mechanism and the strategy-proof deferred acceptance mechanism when taking into account that students may face uncertainty about their own priorities when submitting preferences, one important variation from the complete information assumption. The second chapter evaluates the effectiveness of a strategy-proof mechanism when students have to submit preferences before knowing their priorities using both theory and data. The third chapter turns attention to a new mechanism that is sequentially implemented and can encourage truth-telling. Nevertheless, such implementation often faces time constraint. This chapter therefore offers an inquiry of the pros and cons of the time-constrained sequential mechanism.Doctorat en Sciences économiques et de gestion
info:eu-repo/semantics/nonPublished
6
Weight, Brent L. "Development and design of constant-force mechanisms /." Diss., CLICK HERE for online access, 2001. http://contentdm.lib.byu.edu/ETD/image/etd137.pdf.
Full text
7
Li, Qin. "Design and analysis of electronic feedback mechanisms." Thesis, Royal Holloway, University of London, 2012. http://repository.royalholloway.ac.uk/items/4fe8fab3-7727-645b-7ab3-88fcb9eb0942/9/.
Full textAbstract:
With the advent and development of modern information technology, such as the Internet, the difficulty in transmitting data has been reduced significantly. This makes it easier for entities to share their experience to a larger extent than before. In this thesis, we study the design and analysis of feedback mechanisms, which are the information systems that enable entities to learn information from others' experience. We provide a framework for feedback mechanisms. We first provide an abstract model of a feedback mechanism which defines the scope of our concept and identifies the necessary components of a feedback mechanism. We then provide a framework for feedback mechanisms. This provides a global and systematic view of feedback mechanisms. We also use our model and framework to decompose and analyse several existing feedback mechanisms. We propose an electronic marketplace which can be used for trading online services such as computational resources and digital storage. This marketplace incorporates a dispute prevention and resolution mechanism that is explicitly designed to encourage the good conduct of marketplace users, as well as providing important security features and being cost-effective. We also show how to incorporate the marketplace into Grid computing for exchanging computational resources. We propose a novel feedback mechanism for electronic marketplaces. In this setting, the role of feedback is no longer a “shadow of the future”, but a “shadow of the present”. In other words, feedback directly impacts on the seller's payoff for the current transaction instead of future transactions. This changes the fundamental functionality of feedback, which solves many inherent problems of reputation systems that are commonly applied in electronic marketplaces. We provide a novel announcement scheme for vehicular ad-hoc networks (VANETs) based on a reputation system in order to evaluate message reliability. This scheme features robustness against adversaries, efficiency and fault tolerance to temporary unavailability of the central server.
8
Lumbers, Jeremy. "Rotating biological contactors : mechanisms, modelling and design." Thesis, Imperial College London, 1988. http://hdl.handle.net/10044/1/47161.
Full text
9
Weight, Brent Lewis. "Development and Design of Constant-Force Mechanisms." BYU ScholarsArchive, 2002. https://scholarsarchive.byu.edu/etd/3.
Full textAbstract:
This thesis adds to the knowledge base of constant-force mechanisms (CFMs). It begins by reviewing past work done in the area of CFMs and then develops new nondimensionalized parameters that are used to simplify the calculations required to design a CFM. Comparison techniques are then developed that utilize these non-dimensionalized parameters to compare mechanisms based on stiffnesses, percent constant-force, actual lengths, normal displacements, and feasible design orientations. These comparison techniques are then combined with optimization to define new mechanisms with improved performance and range of capabilities. This thesis also outlines a design process, methods to identify mechanisms that are suitable for a given design problem, and relationships and trends between variables. The thesis concludes by discussing the adaptation of CFMs for use in electrical contacts and presenting the results of a design case study which successfully developed a constant-force electrical contact (CFEC).
10
Mackay, Allen Boyd. "Large-displacement linear-motion compliant mechanisms /." Diss., CLICK HERE for online access, 2007. http://contentdm.lib.byu.edu/ETD/image/etd1845.pdf.
Full text
11
Olsen, Brian Mark. "A Design Framework that Employs a Classification Scheme and Library for Compliant Mechanism Design." BYU ScholarsArchive, 2010. https://scholarsarchive.byu.edu/etd/2298.
Full textAbstract:
Limited resources are currently available to assist engineers in implementing compliant members into mechanical designs. As a result, engineers often have little to no direction incorporating compliant mechanisms. This thesis develops a conceptual design framework and process that utilizes a proposed classification scheme and a library of mechanisms to help engineers incorporate compliant mechanisms into their applications. As the knowledge related to the synthesis and analysis of compliant mechanisms continues to grow and mature, and through the classification scheme established in this thesis, compliant mechanisms may become more extensively used in commercial mechanical designs. This thesis also demonstrates a design approach engineers can use to convert an existing rigid-body mechanism into a compliant mechanism by using the established classification scheme and a library of compliant mechanisms. This approach proposes two possible techniques that use rigid-body replacement synthesis in conjunction with a compliant mechanism classification scheme. One technique replaces rigid-body elements with a respective compliant element. The other technique replaces a complex rigid-body mechanism by decomposing the mechanism into simpler functions and then replacing a respective rigid-body mechanism with a compliant mechanism that has a similar functionality. These techniques are then demonstrated by developing and designing a competitive and feasible compliant road bicycle brake system.
12
Malik, Akhtar Nawaz. "The design of spatial parallel platform-type mechanisms." Thesis, University of Salford, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305883.
Full text
13
Pouyan, Peyman. "Reliability-aware memory design using advanced reconfiguration mechanisms." Doctoral thesis, Universitat Politècnica de Catalunya, 2015. http://hdl.handle.net/10803/328718.
Full textAbstract:
Fast and Complex Data Memory systems has become a necessity in modern computational units in today's integrated circuits. These memory systems are integrated in form of large embedded memory for data manipulation and storage. This goal has been achieved by the aggressive scaling of transistor dimensions to few nanometer (nm) sizes, though; such a progress comes with a drawback, making it critical to obtain high yields of the chips. Process variability, due to manufacturing imperfections, along with temporal aging, mainly induced by higher electric fields and temperature, are two of the more significant threats that can no longer be ignored in nano-scale embedded memory circuits, and can have high impact on their robustness.
Static Random Access Memory (SRAM) is one of the most used embedded memories; generally implemented with the smallest device dimensions and therefore its robustness can be highly important in nanometer domain design paradigm. Their reliable operation needs to be considered and achieved both in cell and also in architectural SRAM array design.
Recently, and with the approach to near/below 10nm design generations, novel non-FET devices such as Memristors are attracting high attention as a possible candidate to replace the conventional memory technologies. In spite of their favorable characteristics such as being low power and highly scalable, they also suffer with reliability challenges, such as process variability and endurance degradation, which needs to be mitigated at device and architectural level.
This thesis work tackles such problem of reliability concerns in memories by utilizing advanced reconfiguration techniques. In both SRAM arrays and Memristive crossbar memories novel reconfiguration strategies are considered and analyzed, which can extend the memory lifetime. These techniques include monitoring circuits to check the reliability status of the memory units, and architectural implementations in order to reconfigure the memory system to a more reliable configuration before a fail happens.Actualmente, el diseño de sistemas de memoria en circuitos integrados busca continuamente que sean más rápidos y complejos, lo cual se ha vuelto de gran necesidad para las unidades de computación modernas. Estos sistemas de memoria están integrados en forma de memoria embebida para una mejor manipulación de los datos y de su almacenamiento. Dicho objetivo ha sido conseguido gracias al agresivo escalado de las dimensiones del transistor, el cual está llegando a las dimensiones nanométricas. Ahora bien, tal progreso ha conllevado el inconveniente de una menor fiabilidad, dado que ha sido altamente difícil obtener elevados rendimientos de los chips. La variabilidad de proceso - debido a las imperfecciones de fabricación - junto con la degradación de los dispositivos - principalmente inducido por el elevado campo eléctrico y altas temperaturas - son dos de las más relevantes amenazas que no pueden ni deben ser ignoradas por más tiempo en los circuitos embebidos de memoria, echo que puede tener un elevado impacto en su robusteza final. Static Random Access Memory (SRAM) es una de las celdas de memoria más utilizadas en la actualidad. Generalmente, estas celdas son implementadas con las menores dimensiones de dispositivos, lo que conlleva que el estudio de su robusteza es de gran relevancia en el actual paradigma de diseño en el rango nanométrico. La fiabilidad de sus operaciones necesita ser considerada y conseguida tanto a nivel de celda de memoria como en el diseño de arquitecturas complejas basadas en celdas de memoria SRAM. Actualmente, con el diseño de sistemas basados en dispositivos de 10nm, dispositivos nuevos no-FET tales como los memristores están atrayendo una elevada atención como posibles candidatos para reemplazar las actuales tecnologías de memorias convencionales. A pesar de sus características favorables, tales como el bajo consumo como la alta escabilidad, ellos también padecen de relevantes retos de fiabilidad, como son la variabilidad de proceso y la degradación de la resistencia, la cual necesita ser mitigada tanto a nivel de dispositivo como a nivel arquitectural. Con todo esto, esta tesis doctoral afronta tales problemas de fiabilidad en memorias mediante la utilización de técnicas de reconfiguración avanzada. La consideración de nuevas estrategias de reconfiguración han resultado ser validas tanto para las memorias basadas en celdas SRAM como en `memristive crossbar¿, donde se ha observado una mejora significativa del tiempo de vida en ambos casos. Estas técnicas incluyen circuitos de monitorización para comprobar la fiabilidad de las unidades de memoria, y la implementación arquitectural con el objetivo de reconfigurar los sistemas de memoria hacia una configuración mucho más fiables antes de que el fallo suceda
14
Grubbström, Thomas. "Mechanical Design of Stylus Mechanisms for Mobile Phones." Thesis, KTH, Maskinkonstruktion (Inst.), 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-100675.
Full textAbstract:
Detta examensarbete är ett produktutvecklingsprojekt som har genomförts i samarbete med Sony Ericsson Mobile Communications vid avdelningen för Mechanical Development i Kista. Ett kännetecken för Sony Ericssons open platform-mobiltelefoner är pekskärmen med det tillhörande pekdonet. Fastsättandet av pekdonets delar samt retain-release-mekanismen för pekdonet skulle utvecklas ytterligare mekaniskt. Delen av detta examensarbete som rörde fastsättandet av de ingående delarna av pekdonet gavs en mindre del än utvecklandet av retainrelease- mekanismen. Studier kring examensarbetets två områden visade mer exakt på vad som behövdes utvecklas. Kartläggningen utfördes genom att studera intern dokumentation, externa produkter och användarrelaterade frågor. I fallet med fastsättandet av delarna av pekdonet upptäcktes det att skruvgängan, vilket är det vanligaste sättet att sätta samman delarna, är en dyr lösning. Vidare upptäcktes det att det är möjligt för en användare att demontera pekdonet, samt att limmet som tillsätts och ytbehandlingen av delarna är dyr. Det upptäcktes även att ergonomin inte är optimal. Retain-release-mekanismen för pekdonet på senare mobiltelefoner har en relativt enkel konstruktion. Den består vanligtvis av en trådfjäder eller en bladfjäder. Dessa fjädrar håller enbart pekdonet i ett bestämt läge inuti mobiltelefonen vilket leder till att användaren måste pilla ut pekdonet. Avsikten var att göra detta utförande mer elegant. Konceptgenereringen resulterade i två stycken koncept för fastsättande av pekdonets delar; ett kortsiktigt koncept som kunde implementeras omedelbart och ett långsiktigt koncept som behövde mer studier och utveckling. Ett koncept på retain-release-mekanism för pekdonet slutfördes med unik konstruktion liknande push-push-mekanismer som finns i vanliga kulspetspennor. Prototyper beställdes och utvärderades och de slutgiltiga koncepten modifierades för att bli optimala.This Master of Science Thesis is a product development project that has been carried out in cooperation with Sony Ericsson Mobile Communications at the Department of Mechanical Development in Kista. A distinctive feature on Sony Ericsson’s open platform mobile phones is the touch screen with the accompanying stylus pen. This was to be developed further mechanically in terms of the joints of the stylus parts and the retain-release mechanism for the stylus. The part of the thesis that concerned the joints of the stylus parts was to be given smaller space than the development of the retain-release mechanism. Studies in the fields of the two areas of the thesis were done which elucidated more precisely what was needed to develop. This was done by studying internal documentation, external products and user-related issues. In the case of the joints of the stylus parts it was discovered that the screw threaded joint, which is the most common joint on later styli, is expensive. Furthermore, it is possible to disassemble the stylus by the user and the glue that is added to the joints and the painting of the parts are expensive. Another thing that was discovered was that the ergonomics of most styli has to be improved. The retain-release mechanism on later mobile phones has a relatively simple design. This consists usually of a wire spring or a leaf spring. These stylus springs only retains the stylus in the mobile phone which leads to that the user has to pick the stylus out. The aim was to make this release more elegant. The concept generating processes resulted in two final concepts for the joints of the stylus parts; one short-term concept that could be implemented immediately and one long-term concept that needed more studies and development. One concept of the retain-release mechanism was finalized which has a unique design similar of push-push mechanisms that are found in many pens. Prototypes were ordered and evaluated and the final concepts were modified to be optimal
15
Martins, Pires Rui Miguel. "Design methodology for wing trailing edge device mechanisms." Thesis, Cranfield University, 2007. http://hdl.handle.net/1826/3393.
Full textAbstract:
Over the last few decades the design of high lift devices has become a very
important part of the total aircraft design process. Reviews of the design process
are performed on a regular basis, with the intent to improve and optimize the
design process.
This thesis describes a new and innovative methodology for the design and
evaluation of mechanisms for Trailing Edge High-Lift devices. The initial research
reviewed existing High-Lift device design methodologies and current flap systems
used on existing commercial transport aircraft. This revealed the need for a design
methodology that could improve the design process of High-Lift devices, moving
away from the conventional "trial and error" design approach, and cover a wider
range of design attributes. This new methodology includes the use of the
innovative design tool called SYNAMEC. This is a state-of-the-art engineering
design tool for the synthesis and optimizations of aeronautical mechanisms. The
new multidisciplinary design methodology also looks into issues not usually
associated with the initial stages of the design process, such as Maintainability,
Reliability, Weight and Cost.
The availability of the SYNAMEC design tool and its ability to perform Synthesis
and Optimization of mechanisms led to it being used as an important module in
the development of the new design methodology. The SYNAMEC tool allows
designers to assess more mechanisms in a given time than the traditional design
methodologies.
A validation of the new methodology was performed and showed that creditable
results were achieved.
A case study was performed on the ATRA
-
Advance Transport Regional Aircraft,
a Cranfield University design project, to apply the design methodology and select
from within a group of viable solutions the most suitable type of mechanism for the
Variable Camber Wing concept initially defined for the aircraft. The results show
that the most appropriate mechanism type for the ATRA Variable Camber Wing is
the Link /Track Mechanism. It also demonstrated how a wide range of design
attributes can now be considered at a much earlier stage of the design.
16
Diez, Jacob A. "Design for additive fabrication : building miniature robotic mechanisms." Thesis, Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/17668.
Full text
17
Lee, Mern Keat. "Design for manufacturability of speed-reduction cam mechanisms." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=31056.
Full textAbstract:
Cam mechanisms are widely used in industry, in applications requiring quick-return and indexing motions. A current research effort at the Robotic Mechanical Systems Laboratory of McGill University's Centre for Intelligent Machines aims at the application of cam mechanisms as speed reducers. The accuracy required in these mechanisms is of the utmost importance, especially when cams are rotating at a high speed.In this thesis, the design for manufacturability of planar speed-reduction cam mechanisms is studied. In particular, the thesis focuses on a speed reducer with a rotating follower to couple shafts of parallel axes, termed planar Speed-o-Cam. Principles of the design for manufacturability are applied to Speed-o-Cam and a unified method for obtaining the optimum parameters satisfying the curvature constraints and pressure-angle bounds is developed. These two factors are relatively important because Numerically Controlled and Computer Numerically Controlled machine tools could be very sensitive to changes of curvature of the workpiece, especially when milling complex shapes such as those of cam plates.
Cam-mechanism balancing is also studied because unbalance in a high-speed rotating element can cause severe vibrations and greatly affect the bearings and hence, the performance of the machine. This is done by not only adding counterweights, which unavoidably increase the weight and volume of the mechanism, but also by removing material.
18
Johnson, Andrew David Kenneth. "On the design of multi-platform parallel mechanisms." Thesis, Heriot-Watt University, 2017. http://hdl.handle.net/10399/3386.
Full textAbstract:
Parallel mechanisms have been examined in more and more detail over the past two decades. Parallel mechanisms are essentially the same design layout, a base, multiple legs/limbs, and a moving platform with a single end-effector to allow the mechanism to complete its desired function. Recently, several research groups have begun looking into multiple-platform parallel mechanisms and/or multiple end-effectors for parallel mechanisms. The reason for the research in this new form of parallel mechanism stems from multiple sources, such as applications that would require multiple handling points being accessed simultaneously, a more controlled gripper motion by having the jaws of the gripper being attached at different platforms, or to increasing the workload of the mechanism. The aim of the thesis is to modify the design process of parallel mechanisms so that it will support the development of a new parallel mechanism with multiple platforms capable of moving relative to each other in at least 1-DOF and to analyse the improvements made on the traditional single platform mechanism through a comparison of the power requirements for each mechanism. Throughout the thesis, a modified approach to the type synthesis of a parallel mechanism with multiple moving platforms is proposed and used to create several case study mechanisms. Additionally, this thesis presents a new series of methods for determining the workspace, inverse kinematic and dynamic models, and the integration of these systems into the design of a control system. All methods are vetted through case studies where they are judged based on the results gained from existing published data. Lastly, the concepts in this thesis are combined to produce a physical multi-platform parallel mechanism case study with the process being developed at each stage. Finally, a series of proposed topics of future research are listed along with the limitations and contributions of this work.
19
Nohavec, Donald R. (Donald Richard). "Magnetic bearing design for interferometric mirror-scanning mechanisms." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/10487.
Full text
20
Roberts, Benjamin Geoffrey. "Incentive mechanisms for the design of shared infrastructures." Thesis, University of Cambridge, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609676.
Full text
21
Leeke, Matthew. "Towards the design of efficient error detection mechanisms." Thesis, University of Warwick, 2011. http://wrap.warwick.ac.uk/52394/.
Full textAbstract:
The pervasive nature of modern computer systems has led to an increase in our reliance on such systems to provide correct and timely services. Moreover, as the functionality of computer systems is being increasingly defined in software, it is imperative that software be dependable. It has previously been shown that a fault intolerant software system can be made fault tolerant through the design and deployment of software mechanisms implementing abstract artefacts known as error detection mechanisms (EDMs) and error recovery mechanisms (ERMs), hence the design of these components is central to the design of dependable software systems. The EDM design problem, which relates to the construction of a boolean predicate over a set of program variables, is inherently difficult, with current approaches relying on system specifications and the experience of software engineers. As this process necessarily entails the identification and incorporation of program variables by an error detection predicate, this thesis seeks to address the EDM design problem from a novel variable-centric perspective, with the research presented supporting the thesis that, where it exists under the assumed system model, an efficient EDM consists of a set of critical variables. In particular, this research proposes (i) a metric suite that can be used to generate a relative ranking of the program variables in a software with respect to their criticality, (ii) a systematic approach for the generation of highly-efficient error detection predicates for EDMs, and (iii) an approach for dependability enhancement based on the protection of critical variables using software wrappers that implement error detection and correction predicates that are known to be efficient. This research substantiates the thesis that an efficient EDM contains a set of critical variables on the basis that (i) the proposed metric suite is able, through application of an appropriate threshold, to identify critical variables, (ii) efficient EDMs can be constructed based only on the critical variables identified by the metric suite, and (iii) the criticality of the identified variables can be shown to extend across a software module such that an efficient EDM designed for that software module should seek to determine the correctness of the identified variables.
22
Rodkey, Elizabeth A. "INHIBITOR RESISTANCE MECHANISMS AND INHIBITOR DESIGN IN ¿¿-LACTAMASES." Case Western Reserve University School of Graduate Studies / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=case1354463033.
Full text
23
Marras, Alexander Edison. "Design, Control, and Implementation of DNA Origami Mechanisms." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1500576490237821.
Full text
24
Pendleton, Tyler M. "Design and Fabrication of Rotationally Tristable Compliant Mechanisms." Diss., CLICK HERE for online access, 2006. http://contentdm.lib.byu.edu/ETD/image/etd1552.pdf.
Full text
25
Riutort, Kevin T. "Applied design and implementation of straight-line mechanisms." Thesis, This resource online, 1996. http://scholar.lib.vt.edu/theses/available/etd-09182008-063202/.
Full text
26
Zhu, Leon Yang. "Dominant strategy double auction mechanisms design and implementation /." [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0011354.
Full text
27
Deshpande, Aasawari G. "Design and comparison of intelligent auto adjusting mechanisms." [Gainesville, Fla.] : University of Florida, 2009. http://purl.fcla.edu/fcla/etd/UFE0041346.
Full text
28
Cahill, Daniel. "Utilising information in architectural design drawings." Thesis, Heriot-Watt University, 2000. http://hdl.handle.net/10399/1143.
Full text
29
Zografos, George L. "The design of collision free mechanisms using constraint modelling." Thesis, Brunel University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.295193.
Full text
30
Jensen, Brian D. "Identification of Macro- and Micro-Compliant Mechanism Configurations Resulting in Bistable Behavior." BYU ScholarsArchive, 2003. https://scholarsarchive.byu.edu/etd/83.
Full textAbstract:
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.
31
Lusk, Craig P. "Ortho-Planar Mechanisms for Microelectromechanical Systems." Diss., CLICK HERE for online access, 2005. http://contentdm.lib.byu.edu/ETD/image/etd902.pdf.
Full text
32
Chacón, Pérez Jonathan 1986. "Community platform management mechanisms to support integrated Learning Design." Doctoral thesis, Universitat Pompeu Fabra, 2016. http://hdl.handle.net/10803/360849.
Full textAbstract:
This PhD Thesis contributes to the domain of Educational Technologies, and more specifically to the Learning Design (LD) research field, which focuses on supporting teachers in the creation of effective computer-supported learning activities considering the needs of their educational contexts. Research in LD has provided a myriad of tools and methods. Yet, existing tools lack collaboration support for communities of teachers engaged in learning (co-)design. Moreover, scope of tools is varied in terms of representations used, pedagogical approaches supported, and design phases targeted (from conceptualization to authoring and implementation). This diversity of tools contrasts with lack of articulation of their synergies to offer meaningful, manageable and integrated LD ecosystems for teachers and communities of teachers. This Thesis is framed in this problem area. Its guiding research question is: How can community platform management mechanisms support teachers in integrated learning design ecosystems? This question is addressed by more specific investigation towards addressing four specific research objectives. The first objective is explorative, focused on understanding needs for
management mechanisms in LD community platforms. The resulting contribution includes participation in building and evaluating LD community platforms (LdShake, Learning design Sharing and co-edition, and ILDE, Integrated Learning Design Environment) in the context of Spanish and European projects, and the identification of needs tackled in the following three research objectives.
The second objective deals with enabling flexible management of learning (co-)design processes that involve use of several LD tools. The associated contribution is a model and implementation for LD Workflows, which shape orchestrated uses of selected LD tools that can be applied to LD Projects. The third objective focuses on supporting management of multiple learning design versions in scenarios of reuse and co-design. The contribution is a model and visualization strategy based on a family tree metaphor. The fourth objective concerns the need for interoperability between co-(design) tools and platforms, and in particular focuses on design patterns as structured LD representations of
special interest because they collect repeatable good teaching practices. The contribution is a pattern ontology for computationally representing a pattern language (working case of design patterns in Computer-Supported Collaborative Learning) and a derived model together with an architecture for interoperable management of patterns across LD tooling. Contributions have been implemented in LdShake and ILDE community platforms, showing feasibility, enabling proofof-concept in significant scenarios and user studies involving teachers.Las contribuciones de esta Tesis Doctoral se enmarcan en el ámbito de las Tecnologías Educativas, y más concretamente en el campo de investigación del Diseño de Aprendizaje (LD acrónimo en inglés). Este campo se centra en dar apoyo a los profesores en la creación de actividades educativas apoyadas por ordenador teniendo en consideración sus contextos educativos. La investigación en el campo de LD ha proporcionado gran cantidad de herramientas y métodos. Sin embargo, estas herramientas todavía carecen de mecanismos que posibiliten la colaboración en comunidades de profesores involucradas en el (co-)diseño de aprendizaje. Además, el alcance de las herramientas es muy variado en cuanto a las representaciones utilizadas, los enfoques pedagógicos utilizados, y fases de diseño a las que van dirigidas (desde la conceptualización, hasta la autoría y hasta la implementación). Esta diversidad de herramientas contrasta con la falta de articulación de sus sinergias para ofrecer ecosistemas LD significativos, manejables e integrados para profesores y comunidades de profesores. Esta problemática motiva la investigación realizada en esta Tesis. La pregunta de investigación que la guía es: ¿Cómo pueden apoyar los mecanismos de gestión de plataformas comunitarias dar soporte en ecosistemas de diseño de aprendizaje integrado? Esta cuestión se aborda en la investigación más concreta de cuatro objetivos específicos. El primer objetivo es exploratorio, se centra en la comprensión de las necesidades de mecanismos de gestión en plataformas para comunidades en LD. La contribución resultante incluye la participación en la implementación y evaluación de las plataformas para comunidades en LD (LdShake, acrónimo en inglés de Learning design Sharing and co-edition, e ILDE, acrónimo en inglés de Integrated Learning Design Environment) en el contexto de proyectos españoles y europeos, así como la identificación de las necesidades abordadas en los tres siguientes objetivos de la investigación. El segundo objetivo busca permitir una gestión flexible de los procesos de (co-)diseño de aprendizaje que implique el uso de varias herramientas de LD. La contribución asociada es un modelo e implementación de los flujos de trabajo de LD (LD Workflows en inglés). Los LD Workflows se definen para permitir la representación de las herramientas de LD seleccionadas que se pueden aplicar a proyectos de LD (LD Projects, en inglés). El tercer objetivo se centra en el apoyo a la gestión de múltiples versiones de diseño de aprendizaje en escenarios de reutilización y (co-)diseño. La contribución es un modelo y una visualización basada en una metáfora del árbol familiar (family tree, en inglés). El cuarto objetivo trata la necesidad de interoperabilidad entre herramientas de (co-)diseño y plataformas de LD, y en particular, se centra en los patrones de diseño como representaciones LD estructuradas de especial interés ya que recogen buenas prácticas docentes repetibles. La contribución es una ontología de patrones que representa computacionalmente un lenguaje de patrones (centrándose en los patrones de CSCL, del inglés:Computer-Supported Collaborative Learning) y un modelo derivado junto con una arquitectura para la gestión interoperable de patrones a través de herramientas de LD. Las contribuciones se han implementado en las plataformas de comunidades de LD LdShake e ILDE mostrando su viabilidad, ofreciendo la prueba de conceptos en escenarios significativos y estudios con profesores en entornos reales.
33
Marras, Alexander Edison. "DNA Origami Mechanisms and Machines." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1366227349.
Full text
34
Binder, Bernd. "Design principles and control mechanisms of signal transduction networks." Doctoral thesis, [S.l. : s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=975655868.
Full text
35
Lan, Chao-Chieh. "Computational Models for Design and Analysis of Compliant Mechanisms." Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/14076.
Full textAbstract:
We consider here a class of mechanisms consisting of one or more compliant members, the manipulation of which relies on the deflection of those members. Compared with traditional rigid-body mechanisms, compliant mechanisms have the advantages of no relative moving parts and thus involve no wear, backlash, noises and lubrication. Motivated by the need in food processing industry, this paper presents the Global Coordinate Model (GCM) and the generalized shooting method (GSM) as a numerical solver for analyzing compliant mechanisms consisting of members that may be initially straight or curved.
As the name suggests, the advantage of global coordinate model is that all the members share the same reference frame, and hence, greatly simplifies the formulation for multi-link and multi-axis compliant mechanisms. The GCM presents a systematic procedure with forward/inverse models for analyzing generic compliant mechanisms. Dynamic and static examples will be given and verified experimentally. We also develop the Generalized Shooting Method (GSM) to efficiently solve the equations given by the GCM. Unlike FD or FE methods that rely on fine discretization of beam members to improve its accuracy, the generalized SM that treats the boundary value problem (BVP) as an initial value problem can achieve higher-order accuracy relatively easily.
Using the GCM, we also presents a formulation based on the Nonlinear Constrained Optimization (NCO) techniques to analyze contact problems of compliant grippers. For a planar problem it essentially reduces the domain of discretization by one dimension. Hence it requires simpler formulation and is computationally more efficient than other methods such as finite element analysis.
An immediate application for this research is the automated live-bird transfer system developed at Georgia Tech. Success to this development is the design of compliant mechanisms that can accommodate different sizes of birds without damage to them. The feature to be monolithic also makes complaint mechanisms attracting in harsh environments such as food processing plants. Compliant mechanisms can also be easily miniaturized and show great promise in microelectromechanical systems (MEMS). It is expected that the model presented here will have a wide spectrum of applications and will effectively facilitate the process of design and optimization of compliant mechanisms.
36
Lum, Guo Zhan. "Optimal Design of Miniature Flexural and Soft Robotic Mechanisms." Research Showcase @ CMU, 2017. http://repository.cmu.edu/dissertations/1090.
Full textAbstract:
Compliant mechanisms are flexible structures that utilize elastic deformation to achieve their desired motions. Using this unique mode of actuation, the compliant mechanisms have two distinct advantages over traditional rigid machines: (1) They can create highly repeatable motions that are critical for many high precision applications. (2) Their high degrees-of-freedom motions have the potential to achieve mechanical functionalities that are beyond traditional machines, making them especially appealing for miniature robots that are currently limited to only having simple rigid-body-motions and gripping functionalities. Unfortunately, despite the potential of compliant mechanisms, there are still several key challenges that restrict them from realizing their full potential. To facilitate this discussion, we first divide the compliant mechanisms into two categories: (1) the stiffer flexural mechanisms that are ideal for high precision applications, and (2) the more compliant miniature soft robots that can reshape their geometries to achieve highly complex mechanical functionalities. The key limitation for existing flexural mechanisms is that their stiffness and dynamic properties cannot be optimized when they have multi-degrees-of-freedom. This limitation has severely crippled the performance of flexural mechanisms because their stiffness and dynamic properties dictate their workspace, transient responses and capabilities to reject disturbances. On the other hand, miniature soft robots that have overall dimensions smaller than 1 cm, are unable to achieve their full potential because existing works do not have a systematic approach to determine the required design and control signals for the robots to generate their desired time-varying shapes.
37
Szost, Blanka Angelika. "Hydrogen trapping in bearing steels : mechanisms and alloy design." Thesis, University of Cambridge, 2013. https://www.repository.cam.ac.uk/handle/1810/244934.
Full textAbstract:
Hydrogen embrittlement is a problem that offers challenges both to technology and to the theory of metallurgy. In the presence of a hydrogen rich environment, applications such as rolling bearings display a significant decrease in alloy strength and accelerated failure due to rolling contact fatigue. In spite of these problems being well recognised, there is little understanding as to which mechanisms are present in hydrogen induced bearing failure. The objective of this thesis are twofold. First, a novel alloy combining the excellent hardness of bearing steels, and resistance to hydrogen embrittlement, is proposed. Second, a new technique to identify the nature of hydrogen embrittlement in bearing steels is suggested. The new alloy was a successful result of computer aided alloy design; thermodynamic and kinetic modelling were employed to design a composition and heat treatment combining (1) fine cementite providing a strong and ductile microstructure, and (2) nano-sized vanadium carbide precipitates acting as hydrogen traps. A novel technique is proposed to visualise the migration of hydrogen to indentation-induced cracks. The observations employing this technique strongly suggest that hydrogen enhanced localised plasticity prevails in bearing steels. While proposing a hydrogen tolerant bearing steel grade, and a new technique to visualize hydrogen damage, this thesis is expected to aid in increasing the reliability of bearings operating in hydrogen rich environments.
38
Atkins, Margaret Stella. "The role of exception mechanisms in software systems design." Thesis, University of British Columbia, 1985. http://hdl.handle.net/2429/25555.
Full textAbstract:
Exception handling is a crucial aspect of practical programming, particularly in systems allowing logical concurrency such as multi-process distributed systems.
First, a survey of existing exception handling mechanisms in operating systems is performed, which shows a diversity of implementations, depending on the process model and the method of inter-process communication. The thesis then develops a model for designing software which exploits the different mechanisms for handling normal and exceptional events. The model is applicable in many multi-process programming environments, and not only preserves modularity, but also enhances efficiency and reliability, while often increasing concurrency.
To derive such a model, exceptions in multi-process software are classified primarily according to the program level at which they are detected and handled. Server-to-client exceptions are of particular interest because of their ubiquity; these are exceptions detected by a server and handled by a client.
The model treats systems programs as event driven, and proposes dividing the events into normal or exceptional, according to the cost and mechanisms for handling them. Techniques are described for designing software according to three criteria: minimising the average run-time, minimising the exception processing time, and incrementally increasing the program's functionality.
Many examples are given which illustrate the use of the general model.
Program paradigms in several languages and in several systems are introduced to model features which are system dependent, through illustrative examples for asynchronous i/o multiplexing, and for exception notification from a server to its client or clients. Finally, some programs which have been implemented according to the rules of the model are described and compared with their more conventional counterparts. These programs illustrate the practicality and usefulness of the model for diverse systems and concurrent environments.Science, Faculty of
Computer Science, Department of
Graduate
39
Chopra, Vikram. "Design of innovative clutching mechanisms for hybrid automotive transmissions." Thesis, McGill University, 2014. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=123009.
Full textAbstract:
Innovative clutching mechanisms for hybrid automotive transmissions that yield low losses, while still satisfying the conflicting requirements of compactness, quick response, and high power density are explored in this thesis. Moreover, a systematic approach to automotive-transmission clutch design is proposed. The goal is to provide a complementary tool to aid the designer's judgment. The various design variants chosen serve two purposes, to demonstrate the foundation and to showcase approaches and solutions to specific problems that have a direct application in transmission design. The analysis of design variants goes into sufficient depth to be useful to both practicing automotive design engineers and academics.The phenomenon of "spin loss" is well known in the automotive industry, for it affects all transmissions. One energy sink identified in this regard lies in traditional wet clutches and brakes, wherein an open clutch or, correspondingly, an open brake, creates drag on the transmission because of the oil churning around and between the rotating friction plates. A second source of spin loss, or energy sink, is of electromagnetic origin, as it occurs by virtue of spinning inactive motors that carry permanent magnets. Apart from spin losses, the hydraulic actuation of clutches and brakes suffers from head losses. Seals, pumps and valves incur leakages that cause energy loss.Using the techniques outlined in this thesis, two separate novel clutch variants are demonstrated to improve clutch and brake technology. One variant, the electromechanical clutch actuator, is based on a high-performance screw joint with a built-in locking mechanism. The screw joint was tested with two sub-variants, namely, a lead screw and a ball screw. One prototype of each of the two sub-variants was installed on a testbed, to mimic the installation of the actuator in place of the corresponding hydraulic components. To better reflect the elastostatic behaviour of the clutch disk assembly, a new model for its stiffness as a hardening spring was formulated. Proof-of-concept tests of both sub-variants, lead and ball screws, demonstrated their feasibility.The second variant, the electromagnetic dog clutch, is directly aimed at minimizing spin and hydraulic actuation losses for clutched electric motors, wherein the motor is connected to a clutch. The system includes a unique contactless electromagnetic synchronizer and a synchronizing sleeve with dog teeth on the input and output components. The design study, focused on the electromagnetic part, strives to reduce clutch slip and control torque. The novel design features claw-like stator and salient rotor poles with good machinability within a restrictive design volume. A complete design analysis with physical proof-of-concept testing was conducted.Reducing "spin-loss" in transmission assemblies will improve system efficiency and yield better fuel economy. The technologicalimpact will benefit not only the user, who will obtain more mileage for her or his dollar, but also the environment.Dans cette thèse sont étudiés des mécanismes innovants d'embrayage pour transmissions automobiles hybrides qui n'engendrent que de faibles pertes, tout en satisfaisant les besoins parfois conflictives de compacité, de haute vitesse de réaction et de haute densité d'énergie. Une approche systématique de la conception de transmissions automobiles est proposée, dont l'objectif est d'offrir un outil complémentaire au jugement du concepteur. Les divers alternatives choisises servent à présenter les concepts fondamentaux, ainsi qu'à mettre en valeur les différentes approches et solutions à des problèmes spécifiques qui ont une application directe dans le domaine des conceptions de transmissions. L'analyse d'alternatives de conception va suffisamment en profondeur pour être utile à la fois aux ingénieurs de conception automobile et aux théoriciens.Le phénomène de pertes d'énergie cinétique de rotation (PECR) est bien connu dans l'industrie automobile, car cela affecte toutes les transmissions. Un puits d'énergie mis en évidence à ce propos concerne les embrayages et freins traditionnels à fluides, pour lesquels un embrayage ouvert ou un frein ouvert, crée une traînée dans la transmission parce que l'huile tourbillonne autour et dans les plaques tournantes de friction. Un second puits d'énergie est d'origine électromagnétique, car générée par la rotation de moteurs inactifs contenant des aimants permanents. Hormis le PECR, l'actionnement hydraulique d'embrayages ou de freins entraîne des pertes de charges. Les joints, pompes et valves encourent des fuites qui engendrent de puits d'énergie.En utilisant les techniques mises en avant dans cette thèse, deux nouvelles alternatives d'embrayages démontrent leurs capacités à améliorer les technologies des freins et des embrayages. L'une de ces alternatives, l'actionneur {\em électromécanique d'embrayage}, est basée sur une liaison à vis et dispose d'un mécanisme intégré de verrouillage. La liaison à vis a été testée au travers de deux sous-alternatives, à savoir une vis à filet trapézoïdal et une vis à billes. Un prototype de chacune des alternatives a été installé sur un banc d'essai, afin de reproduire l'installation de l'actionneur en lieu et place des composants hydrauliques correspondants. Pour mieux refléter le comportement élastostatique de l'assemblage des disques d'embrayage, un nouveau modèle de sa raideur, assimilée à un ressort durcissant, a été formulé. Des tests de preuve de concept des deux variantes, vis à filet trapézoïdal et vis à billes, ont montré leur faisabilité.La seconde variante, l'embrayage électromagnétique à interférence, est directement utilisable pour minimiser les pertes en rotation et en actionnement hydraulique pour les moteurs électriques à embrayage, pour lesquels un moteur est connecté à un embrayage. Le système inclut un unique synchronisateur et des bagues de synchronisation avec des dents-de-chien sur les composants en entrée et en sortie. Le travail de conception a été concentré sur la partie électromagnétique, qui essaie de réduire le glissement de l'embrayage et le couple de commande. Le nouveau système conception est doté d'un stator en forme de griffes et des pôles de rotor saillants faciles à usiner et à installer dans un espace restreint dans la voiture. Une étude complète de conception avec des tests concrets de preuve de concept a été accomplie.Rééduire le PECR dans les assemblages de transmissions améliorera l'efficience du système et mènera à davantage d'économie de carburant. L'impact technologique sera ainsi bénéfique non seulement pour l'utilisateur, qui profitera d'un kilométrage plus élevé pour son argent, mais aussi pour l'environnement.
40
Holland, Neil. "Direct design of mechanisms for mechanical handling and manipulators." Thesis, University of Salford, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.244822.
Full text
41
DiBiasio, Christopher M. (Christopher Michael). "Design and modeling of carbon nanotube-based compliant mechanisms." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/38544.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Page 110 blank.
Includes bibliographical references (p. 97-100).
The objective of this research is to generate the knowledge required to adapt macro- and microscale compliant mechanism theory to design carbon nanotube-based nano-scale compliant mechanisms. Molecular simulations of a nano-scale parallel guiding mechanism uncovered three regions of behavior. Region I is governed by the bulk deformation of the carbon nanotubes. Region II is characterized by hinge-like flexing of four "kinks" that occur due to buckling of the carbon nanotube walls. Region III, an intermediate region, exhibits direction dependant behavior. We report on the ability of a conventional compliant mechanism modeling approach, the pseudo-rigid-body model, to predict the region I behavior of a nano-scale parallel guiding mechanism that uses single-walled (5,5) carbon nanotubes as the flexural elements. Van der Waals forces were found to affect the kinematic and elastomechanic behavior of the nano-scale parallel guiding mechanism. A modified value of the pseudo-rigid-body model stiffness coefficient is presented to capture the affect of van der Waals interactions within (5,5) nanotubes during region I operation.
(cont.) Molecular simulation of region I behaviors match the modified pseudo-rigid-body model predictions of (1) kinematic behavior with less than 7.3 % error and (2) elastomechanic behavior with less than 8 % error. Although region I is of the most interest because of its well-defined and stable nature, region II motion is also investigated to provide a basis for establishing future work in this region.
by Christopher M. DiBiasio.
S.M.
42
Sung, Edward S. M. Massachusetts Institute of Technology. "Design and analysis of diagnostic machines utilizing compliant mechanisms." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/68861.
Full textAbstract:
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, June 2011."June 2011." Cataloged from PDF version of thesis.
Includes bibliographical references (p. 44).
In this paper, the design and testing of an ankle rehabilitation device is presented. The purpose of the research done is to provide physicians with a diagnostics tool that can quantitatively measure the severity of an injury by measuring the ankle joint's functional output. Torque and power output have been shown to be correlated with functional performance of the ankle joint. The device can measure torque and power output over the full range of motion of the ankle joint complex. Such a device has the potential to enable more accurate diagnoses and improve the efficacy of treatment and rehabilitation. The device allows rotation about the three orthogonal axes in the Cartesian plane. The rotations are linked in series to simulate ankle subjoint coupling. Cartwheel flexures with strain gages are aligned with the rotational axes and used as torque sensors. Strain gages are placed in a Wheatstone bridge circuit to mitigate environmental factors. Trials measured torque of the right ankle joint of test subjects from a standing position. Results show that the coupling of the two modes of ankle joint rotation (plantarflexion/dorsiflexion and inversion/eversion) are dependent on a subject's own development.
by Edward Sung.
S.B.
43
Radhakrishnan, Pradeep 1984. "Automated design of planar mechanisms." Thesis, 2014. http://hdl.handle.net/2152/24806.
Full textAbstract:
The challenges in automating the design of planar mechanisms are tremendous especially in areas related to computational representation, kinematic analysis and synthesis of planar mechanisms. The challenge in computational representation relates to the development of a comprehensive methodology to completely define and manipulate the topologies of planar mechanisms while in kinematic analysis, the challenge is primarily in the development of generalized analysis routines to analyze different mechanism topologies. Combining the aforementioned challenges along with appropriate optimization algorithms to synthesize planar mechanisms for different user-defined applications presents the final challenge in the automated design of planar mechanisms. The methods presented in the literature demonstrate synthesis of standard four-bar and six-bar mechanisms with revolute and prismatic joints. But a detailed review of these methods point to the fact that they are not scalable when the topologies and the parameters of n-bar mechanisms are required to be simultaneously synthesized. Through this research, a comprehensive and scalable methodology for synthesizing different mechanism topologies and their parameters simultaneously is presented that overcomes the limitations in different challenge areas in the following ways. In representation, a graph-grammar based scheme for planar mechanisms is developed to completely describe the topology of a mechanism. Grammar rules are developed in conjunction with this representation scheme to generate different mechanism topologies in a tree-search process. In analysis, a generic kinematic analysis routine is developed to automatically analyze one-degree of freedom mechanisms consisting of revolute and prismatic joints. Two implementations of kinematic analysis have been included. The first implementation involves the use of graphical methods for position and velocity analyses and the equation method for acceleration analysis for mechanisms with a four-bar loop. The second implementation involves the use of an optimization-based method that has been developed to handle position kinematics of indeterminate mechanisms while the velocity and acceleration analyses of such mechanisms are carried out by formulating appropriate linear equations. The representation and analysis schemes are integrated to parametrically synthesize different mechanism topologies using a hybrid implementation of Particle Swarm Optimization and Nelder-Mead simplex algorithm. The hybrid implementation is able to produce better results for the problems found in the literature using a four-bar mechanism with revolute joints as well as through other higher order mechanisms from the design space. The implementation has also been tested on three new challenge problems with satisfactory results subject to computational constraints. The difficulties in the search have been studied that indicates the reasons for the lack of solution repeatability. This dissertation concludes with a discussion of the results and future directions.text
44
Chao-Chia, Yang, and 楊肇嘉. "Design of Disk Changer Mechanisms." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/15426224261978489143.
Full textAbstract:
碩士國立中山大學
機械工程研究所
86
Disks have successfully applied on audio and CD-ROM systems, so the disk changer mechanisms become a necessary entertainment and information instrument in modern life. The purpose of this work is to develop a systematic methodology for the creative design of disk changer mechanisms. First, the function structure of disk changer mechanisms is constructed by functional analysis method. Next, the desired design requirements and constraints are deduced. All the possible motion variants are synthesized for disk changer mechanisms. Then, all the possible mechanisms for each motion variant are enumerated by using the desing catalog. Finally, all design concept variants can be synthesized by using morphological chart method. Several design concepts can be created for new disk changer mechanisms. The results of this work are of benefit to the development and design of new disk changer mechanisms.
45
Nishimura, Takeshi, and 健. 西村. "Optimal Design of Procurement Mechanisms." Thesis, 2014. https://doi.org/10.15057/26476.
Full text
46
"On Advancing the Topology Optimization Technique to Compliant Mechanisms and Robots." Thesis, 2015. http://hdl.handle.net/10388/ETD-2015-03-1971.
Full textAbstract:
Compliant mechanisms (CMs) take advantage of the deformation of their flexible members to transfer motion, force, or energy, offering attractive advantages in terms of manufacturing and performance over traditional rigid-body mechanisms (RBMs). This dissertation aims to advance the topology optimization (TO) technique (1) to design CMs that are more effective in performing their functions while being sufficiently strong to resist yield or fatigue failure; and (2) to design CMs from the perspective of mechanisms rather than that of structures, particularly with the insight into the concepts of joints, actuations, and functions of mechanisms. The existing TO frameworks generally result in CMs that are much like load-bearing structures, limiting the applications of CMs. These CMs (1) do not have joints, (2) are actuated by a translational force, and (3) can only do simple work such as amplifying motion or gripping.
Three TO frameworks for the synthesis of CMs are proposed in this dissertation and they are summarized below.
First, a framework was developed for the design of efficient and strong CMs. The widely used stiffness-flexibility criterion for CM design with TO results in lumped CMs that are intrinsically efficient in transferring motion, force, or energy but are prone to high localized stress and thus weak to resist yield or fatigue failure. Indeed, distributed CMs may have a better stress distribution than lumped CMs but have the weakness of being less efficient in motion, force, or energy transfer than lumped CMs. Based on this observation, the proposed framework rendered the concept of hybrid systems, hybrid CMs in this case. Further, the hybridization was achieved by a proposed super flexure hinge element and a design criterion called input stroke criterion in addition to the traditional stiffness-flexibility criterion. Both theoretical exploration and CM design examples are presented to show the effectiveness of the proposed approach. The proposed framework has two main contributions to the field of CMs: (1) a new design philosophy, i.e., hybrid CMs through TO techniques and (2) a new design criterion—input stroke.
Second, a systematic framework was developed for the integrated design of CMs and actuators for the motion generation task. Both rotary actuators and bending actuators were considered. The approach can simultaneously synthesize the optimal structural topology and actuator placement for the desired position, orientation, and shape of the target link in the system while satisfying the constraints such as buckling constraint, yield stress constraint and valid connectivity constraint. A geometrically nonlinear finite element analysis was performed for CMs driven by a bending actuator and CMs driven by a rotary actuator. Novel parameterization schemes were developed to represent the placements of both types of actuators. A new valid connectivity scheme was also developed to check whether a design has valid connectivity among regions of interest based on the concept of directed graphs. Three design examples were constructed and a compliant finger was designed and fabricated. The results demonstrated that the proposed approach is able to simultaneously determine the structure of a CM and the optimal locations of actuators, either a bending actuator or a rotary actuator, to guide a flexible link into desired configurations.
Third, the concept of a module view of mechanisms was proposed to represent RBMs and CMs in a general way, particularly using five basic modules: compliant link, rigid link, pin joint, compliant joint, and rigid joint; this concept was further developed for the unified synthesis of the two types of mechanisms, and the synthesis approach was thus coined as module optimization technique—a generalization of TO. Based on the hinge element in the finite element approach developed at TU Delft (Netherlands in early 1970), a beam-hinge model was proposed to describe the connection among modules, which result in a finite element model for both RBMs and CMs. Then, the concept of TO was borrowed to module optimization, particularly to determine the “stay” or “leave” of modules that mesh a design domain. The salient merits with the hinge element include (1) a natural way to describe various types of connections between two elements or modules and (2) a provision of the possibility to specify the rotational input and output motion as a design problem. Several examples were constructed to demonstrate that one may obtain a RBM, or a partially CM, or a fully CM for a given mechanical task using the module optimization approach.
47
Liu, Chung-Ping, and 劉仲平. "Conceptual Design of Coaxial Clutching Mechanisms." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/51717744006769288403.
Full textAbstract:
碩士國立臺灣大學
機械工程研究所
82
Coaxial clutching mechanisms is a kind of mechanism which has two states - separation and conjuction. This mechanism is simalar to clutch devices, but there are mainly two differerces. First, it is purely a mechanism, not including the hydraulic transmission devices nor the electronically controlled situations. Secondly, the switching of the states is controlled by torque, angular velocity or angular acceleration, not by the direct manipulating of the position of the parts. A systematic method of conceptual design of coaxial clutching mechanisms is proposed in this study. With this method, the coaxial clutching mechanisms with up to six links can be found effeciently, and also the coaxial clutching mechanisms with more than six links can be explored. A simple type of coaxial clutching mechanisms named " original mechanisms " is discussed first. On the synthesis of the original mechanism, graph theory is adopted to synthesize its structure, and its functional combinations are undertaken according to the structural graph. Structure-and- function combination tables can be obtained through the combination of structural graphs and the functional combination tables. Choosing the permissible structure-and-function combination among the tables, and selecting the suitable joints between the links, original mechanisms can be found directly. After the original mechanisms is obtained, it can be transformed into versatile coaxial clutching mechanisms.
48
Lin, Hao-Xiang, and 林浩翔. "The design of new keyboard mechanisms." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/03647055793725181984.
Full textAbstract:
碩士國立中山大學
機械工程學系研究所
88
Abstract A piano is called “the king of instruments”. Almost every great musician writes good compositions for piano, and they are also good pianoists. Piano almost appears in every concert. Bartolomeo Cristofori made the first instrument that we recognize as a piano today in 1709.It is an important invention in music history. The basic structure of a modern piano was approximately decided in 19 century. Many patents were designed to improve the performance of piano in these years, but they didn’t change the basic structure of piano. The research adopts the method of structure synthesis to design new piano and brings up a new idea “linkage controls a hammer” to improve the performance of a piano.
49
Haung, Haung-Bin, and 黃炳皇. "Design of Cartridge Disk Loading Mechanisms." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/15972225732389559045.
Full textAbstract:
碩士國立中山大學
機械工程學系
87
The purpose of this research is to develop a systematic methodology for the creative design of disk cartridge loading mechanisms. First, basic characteristics of disk cartridge loading mechanisms are deduced. Next, all possible variants of functional structure are ynthesized by using the functional analysis method. Next, a system of kinematic notation is used to generate the priciple solutions of each function in a functional structure and all prossible design concepts of disk cartridge loading mechanisms are created. Then, promising design concepts are evaluated by using the decision matrix method. Finally, four potential design concepts of disk cartridge loading mechanisms are provided, and then optimum cartridge disk loading mechanisms can be synthesized by using the theory of kinematic design. The results of this work are of benefit to the development and design for new disk cartridge loading mechanisms.
50
Tsai, Kuo Chang, and 蔡國昌. "DESIGN OF MOTORCYCLE REAR SUSPENSION MECHANISMS." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/24573522830768245547.
Full text