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1
Gurney, Frederick. "Wheels within wheels : an examination of Witold Lutoslawski's Trois poèmes d'Henri Michaux /." Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/11262.
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Wood, Alice. "Of wings and wheels." Thesis, University of Edinburgh, 2007. http://hdl.handle.net/1842/2022.
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What are the biblical cherubim? In the Hebrew Bible, the physical appearance and cultic role of the cherubim are never explicitly elucidated. Largely, the authors assume their audience is familiar with the form and function of these heavenly beings. Yet the portrayal of the cherubim varies from text to text and, sometimes, we are given conflicting information. Previous studies of the cherubim have placed too great an emphasis on archaeological and etymological data. This thesis presents a new synthetic study which prioritises the evidence supplied by the biblical texts. Biblical exegesis, using literary and historical-critical methods, forms the large part of the investigation (chapter 2). The findings arising from the exegetical discussion provide the basis upon which comparison with etymological and archaeological data is made (chapters 3 and 4). It is argued that, with the exception of the book of Ezekiel, the biblical texts are quite consistent in their portrayal of the cherubim. Cherubim are intimately connected with the manifestation of Yahweh and have an apotropaic function in relation to sacred space. They are envisaged with one face and one set of wings. Ps 18:11 = 2 Sam 22:11 suggests that they are quadrupedal. The traditions in the final form of Ezekiel 1-11 mark a shift in the conception of the biblical cherubim. Physically, the cherubim are transmogrified and become enigmatic beasts with four faces and four wings. Their function also changes. Depicted elsewhere as menacing guardians, in Ezekiel they become agents of praise. The results suggest that traditions envisaging the cherubim as tutelary winged quadrupeds were supplanted by traditions that conceived of them as more enigmatic, obeisant beings. In the portrayal of the cherubim in Ezekiel and Chronicles, we can detect signs of a conceptual shift that prefigures the description of the cherubim in post-biblical texts, such as The Songs of the Sabbath Sacrifice and the Enochic texts.
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Baker, Brittany S. M. Massachusetts Institute of Technology. "Reconfigurable wheels : re-inventing the wheel for the next generation of planetary rovers." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/71459.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 84-85).
Experiences with Spirit and Opportunity, the twin Mars Exploration Rovers, showed that one of the major issues that needs to be addressed in order to expand the exploration capabilities of planetary rovers is that of wheel traction. The relationships governing how much traction a wheel can produce are highly dependent on both the shape of the wheel and terrain properties. These relationships are complex and not yet fully understood. The amount of power required to drive a wheel is also dependent on its shape and the terrain properties. Wheel sizes that tend to maximize traction also tend to require more power. In the past, it has always been a challenge to find the right balance between designing a rover wheel with high traction capabilities and low power requirements. More recently, researchers invented the idea of a reconfigurable wheel which would have the ability to change its shape to adapt to the type of terrain it was on. In challenging terrain environments, the wheel could configure to a size that would maximize traction. In less challenging terrain environments, the wheel could configure to a size that would minimize power. Theoretical simulation showed that the use of reconfigurable wheels could improve tractive performance and some initial prototyping and experimental testing corroborated those findings. The purpose of this project was to extend that prototyping and experimenting. Four reconfigurable wheels were designed, built, and integrated onto an actual rover platform. A control methodology whereby the wheels could autonomously reconfigure was also designed, implemented, and demonstrated. The rover was then tested in a simulated Martian environment to assess the effectiveness of the reconfigurable wheels. During the tests, the power consumption and the distance traveled by the rover were both measured and recorded. In all tests, the wheels were able to successfully reconfigure and the rover continued to advance forward; but as was expected, the reconfigurable wheel system consumed more power than a non-reconfigurable wheel system. In the end, the results showed that if maximizing vehicle traction was weighed more heavily than minimizing power consumption, the use of reconfigurable wheels yielded a net gain in performance.
by Brittany Baker.
S.M.
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Lawton, Natalie. "Planetary Rover Wheel and Lower Leg Structural Design to Reduce Rock Entanglements." Thesis, Luleå tekniska universitet, Institutionen för system- och rymdteknik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-78565.
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This thesis looks at the SherpaTT planetary rover. The rover is a hybrid walking and driving rover that has been developed and built by DFKI and has already been deployed on several Mars analogue field studies. The SherpaTT rover wheels were found to become entangled in rocks during the last field deployment in Morocco. As human intervention would be impossible on Mars the aim is to reduce the possibility of rock entanglements by performing a mechanical redesign of the wheels. During this redesign care is taken to ensure the current traction, slip-resistance, weight and strength are not adversely affected. In addition, the durability of the wheels is investigated in terms of materials to review whether the current wheels are suitable for a mars deployment. An investigation into the grousers design results in a changed design that aims to both reduce rock entanglements and increase wheel performance by optimising the grouser height and number over several different wheel and terrain cases. Wheels are produced for four scenarios, a rigid wheel on hard ground, a rigid wheel on soft ground, a flexible wheel on hard ground and a flexible wheel on soft ground. A conceptual investigation into the wheel fork design is carried out to examine the effects of changing three properties of the wheel fork. The magnitude and location of the stress is compared for each. Materials are investigated resulting in the recommendation of several potential material choices which provide an increase in the overall strength and hardness. While SherpaTT is still in development the 6000 class of aluminium is recommended due to the relative ease with which it can be worked with. Once SherpaTT moves onto the final stages it is recommended that at least the grousers are made from the 7000 class of aluminium, which have higher levels of strength and hardness.
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Lock, Julia. "Cyclodextrins : molecular wheels for supramolecular chemistry /." Title page, table of contents and abstract only, 2004. http://web4.library.adelaide.edu.au/theses/09PH/09phl8131.pdf.
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Thesis (Ph.D.)--University of Adelaide, School of Chemistry and Physics, Discipline of Chemistry, 2005?"July 2004" Includes copies of publications by the author as appendix. Includes bibliographical references.
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Moore, Jaclyn Kate. "Aerodynamics of High Performance Bicycle Wheels." Thesis, University of Canterbury. Mechanical Engineering, 2008. http://hdl.handle.net/10092/1800.
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This thesis presents the work undertaken to assess potential improvements in high performance bicycles. There are several wheel options available for elite riders to use in competition and this research has investigated the aerodynamic properties of different wheel type. The research has also developed CFD and FEA models of carbon fibre bicycle wheels to assist in the wheel improvements process.
An accurate and repeatable experimental test rig was developed to measure the aerodynamic properties of bicycle wheels in the wind tunnel, namely translational drag, rotational drag and side force. Both disk wheels and spoked wheels were tested.
It was found that disk wheels of different hub widths have different aerodynamic properties with the 53mm wide Zen disk wheel requiring the lowest total power of the wheels tested. There was little difference between the translational power requirements of the wheels but there was greater variation in the rotational power requirements.
Compression spoked wheels of 3 and 5 spokes were found to require less power than wire spoked wheels. There was little difference between the total power requirements of the compression spoked wheels tested, with the differences at 50km/hr being less than the experimental uncertainty.
The Zipp 808 wheel demonstrated considerably lower axial force than all other wheels at 10° yaw angle, confirming Zipp design intention to have optimum wheel performance between 0-20°. The Zen 3-spoke wheel showed the lowest axial drag and side force at yaw of the compression spoked wheels tested and had similar side force results to the Zipp 808.
CFD models of the disk and 3-spoke wheel achieved good agreement with the experimental results in terms of translational drag. Rotational drag did not agree so well, most likely due to the turbulence model being designed for higher Reynolds number flows.
A FE model of the disk wheel was validated with experimental testing. In order to simplify modelling, the FE model of the 3-spoke wheel did not include the hub, which led to a large discrepancy with experimental results for the particular loading scenario.
The experimental rig and CFD models were used to develop aerodynamic improvements to the wheel and the FE models were used to identify the implication of geometric changes to the wheel structural integrity. These improvements are not reported in this thesis due to the results being commercially sensitive.
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Brash, Benjamin. "Distortions of Press Quenched Crown Wheels." Thesis, KTH, Materialvetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-170022.
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Scania has experienced difficulties with large variations of the slope of the back plane after press quenching of case hardened crown wheels of especially type R780 Steg supplied from ingot cast material. This leads to that a large number of crown wheels has to be remeasured and sorted according to back slope which is time consuming for operators. Also, after sorting of the crown wheels, hard machining has to be adjusted according to the different slopes of the back plane of the crown wheels. In some cases, it also leads to scrapping of the crown wheels.This master’s thesis was divided in two parts. The aim of the first part was to confirm that the crown wheel type and casting technique that exhibits the largest variations in slope of the back plane is the R780 Steg originating from ingot cast material. The crown wheel types that were compared were the R780 Steg, R780 Slät and R885 Slät. Crown wheels manufactured from ingot cast material and from continuous cast material were compared. Hence, 6 combinations were examined. The slope of the back plane was measured with the measuring probe FARO after press quenching. The slope of the crown wheels was found to depend on both casting technique and the geometry of the crown wheel. The results confirmed that the crown wheel type and supplier combination that by far yields the largest variations in slope of the back plane is the R780 Steg supplied by Steel Plant A who uses the ingot casting technique. For this combination the variation exceeds 0,1 mm. All other combinations of crown wheels and suppliers yield acceptable variations.The second part of this master’s thesis was composed of determining if segregations in the cast ingot are the cause of the variations in slope of the back plane of the crown wheel type R780 Steg. This was done by measuring if there is a correlation between the slope of the back plane of the crown wheel after press quenching, the chemical composition and the original position of the crown wheel in the ingot. As in the first part of the study, the distortion was measured by the measuring probe FARO. The samples were sent to Degerfors Laboratorium for chemical analysis. Analyses of C, S and N were made by using combustion analyses. For As, P, B and Al optic spectrometry (spark) was used. All other elements were analysed by x-ray fluorescence. Segregations were found to be present and in combination with the geometry of R780 Steg to be the cause of the large variations in slope of the crown wheels.The results of this thesis show that, for the crown wheel type R780 Steg, Scania should not use suppliers that employ the ingot casting technique. Instead, only suppliers using the continuous casting technique should be used. However, for the other crown wheel types ingot or continuously cast material can be used.
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Taghizadeh, Mohammad. "Robot with Three Independently Steerable Wheels." Thesis, California State University, Long Beach, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10784154.
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Technology in robotics has improved significantly in recent years. While the majority of research has focused on improving existing methods, it is advantageous to challenge these established methodologies and develop new solutions. This new research centers on a novel method of robot movement design. The proposed model concentrates on a robot containing three steerable wheels, allowing the mobile robot to reach the desired orientation and coordinates with minimal movement. This goal is accomplished by simultaneously moving and rotating the robot while moving in a straight path, unlike the movement provided by standard wheeled vehicles. This method provides greater control of performance and more power of movement on various surfaces, compared to using Omni wheels, which contains the design with the greatest similarity to this proposed method. While this new method may result in added complexity due to the goal-based flexible constraints in speed, wheel rotation, and overall movement, this complication may be mitigated by using appropriate software and hardware.
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Hojnik, Tim. "Dynamically configurable centre of rotation wheels." Thesis, Queensland University of Technology, 2021. https://eprints.qut.edu.au/212361/1/Tim_Hojnik_Thesis.pdf.
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This thesis reinvents the wheel to develop a locomotion system that exhibits high efficiency and exceptional obstacle clearing ability, the Posable Hub. This is achieved by using a rigid rim with an actively movable centre hub, through the use of linear actuators. The centre hub can be adjusted in a number of ways, exhibiting functionality that ultimately increases the wheel’s traversability.
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VENTURINI, SIMONE. "Design methodologies for automotive steel wheels." Doctoral thesis, Politecnico di Torino, 2022. http://hdl.handle.net/11583/2971317.
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Flores, Álvarez Pedro Alonso. "Modelling, simulation and experimental verification of a wheeled-locomotion system based on omnidirectional wheels." Master's thesis, Pontificia Universidad Católica del Perú, 2016. http://tesis.pucp.edu.pe/repositorio/handle/123456789/7554.
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The following work focuses on the kinematic and dynamic study of a four-wheeled robot,
which is equipped with omnidirectional Mecanum wheels. The main objective of the
thesis is to obtain a mathematical model from which both the kinematics and kinetics of
the robot can be analyzed. Furthermore, the study presents a methodology to optimize
the torques (and subsequent associated voltages) provided by each of the motors on the
robot for a given trajectory.
A system in which a non-powered trailer pulled by the robot is also analyzed at a
kinematic level. In this stage, four different cases are considered. The construction of the
trailer is also described on this work.
In the first chapter, the global state of the art on analysis and control of omnidirectional
robots (with focus on robots with Mecanum wheels) is presented. In the second chapter,
the physical considerations for the general movement of the robot are analyzed, in order
to derive the kinematic constrain equations of the locomotion system. The differential
equation of motion is then derived using Lagrange-equations with multipliers. This
chapter presents as well the kinematic analysis for a robot-trailer system. The third
chapter describes the general process on the design of the trailer, including the rejected
ideas for its construction. The fourth chapter focuses on verifying the final results of the
design process, as well as tests to check the mobility of the system. Conclusions and
future work are analyzed on the final part of the document, as well as the references and
the acknowledgments to all the people involved in the project.Tesis
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Simonson, Carey James. "Heat and moisture transfer in energy wheels." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0014/NQ27431.pdf.
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Avril, Nicolas Joseph. "Manufacturing glass-fiber reinforcement for grinding wheels." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/38432.
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West, Mark. "Design of omnidirectional vehicles with ball wheels." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/10657.
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Baker, Michael Lloyd. "Antiferromagnetic wheels probed by inelastic neutron scattering." Thesis, University of Manchester, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.542789.
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Jo, Jinmyun. "Residual stress measurement in railroad car wheels." Diss., Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/54206.
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A new failure criterion for discriminating good and bad (overheated) railroad car wheels is proposed. This criterion can replace the conventional “four inch" discoloration rule. The procedure for the new discrimination criterion is based on the fluctuations of the azimuthal residual stress in the tread of the wheel. This criterion is based on a maximum likelihood statistical analysis of data obtained from six different wheels as deterrmined by x-ray diffraction. Of these locations, the analysis showed the tread, and perhaps a critical point on the top of the flange, to be the most sensitive to residual stress. The variance analysis showed that fluctuations in stress at the most sensitive location in the tread appeared to be related to the service history. The residual stresses showed an oscillatory pattern in the hoop direction around the wheels.
Extension of the measurement technology to the use of magnetoelastic stress measurement is proposed. To evaluate the inaccuracy in stress data possible from a large sample with curved surface, corrections for a deliberate tilt of the plane of the x-ray diffractometer from the normal to the sample surface have been developed. Analysis of different misalignments are discussed. To validate our x-ray residual stress data, residual stresses were also measured by hole drilling. Excellent agreement between two techniques was found. Finally, stress variation with depth below surface was determined by the hole drilling technique.Ph. D.
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Al-Ghamdi, Abdulmajeed Saeed. "ANALYSIS OF AIR-TO-AIR ROTARY ENERGY WHEELS." Ohio University / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1146201291.
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McKinnon, Mona Claire. "A study of Vancouver-Richmond meals-on-wheels." Thesis, University of British Columbia, 1985. http://hdl.handle.net/2429/26002.
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Little is known about Meals-on-Wheels organizations, though they exist in many western countries.
The purpose of this study is to examine the Vancouver-Richmond Meals-on-Wheels service as an organization and from that examination to provide information about clients, volunteers, staff, and organizational management.
The literature was searched for guidance on the concept of Meals-on-Wheels. Was there any definition of an ideal organization? Similarly, discussions with government officials in the Province of British Columbia were conducted to determine what they thought this organization might contribute to the province's social support services. The prescriptions were vague and it was found that many assumptions were made. It seemed that organization theory might help to expose the gaps in these prescriptions.
An examination of the organization by observation, interviews, use of secondary data for client profiles, questionnaires for volunteers, and interviews of present clients led to the development of a descriptive account which was arranged using a model developed by Donabedian to assess the quality of patient care, namely, inputs, process, structure, and outcomes. It became clear that organizational theory might assist in diagnosis of some managerial problems as the findings showed that client turnover was high. Analysis of available data had shown the clients to be in the category of "old, old," fairly evenly distributed throughout the area, and self-referred. Those volunteers who responded to a questiononaire were long-term, reasonably satisfied, and strongly committed. The clients interviewed were unstinting in their praise for the volunteers and appreciative of the service. They were dissatisfied with certain aspects of the food and their lack of opportunity for input into this aspect of Meals-on-Wheels. The employees found it difficult to communicate with the investigator and with other important community representatives. Internal and external relationships seemed to be tense.
It seemed that by developing a prescription for "best practices" for a Meals-on-Wheels organization working in this context, comparisons of the existing organization with this prescription might assist with the diagnosis of managerial problems and lead to identification of possible remedies. This course was followed.Medicine, Faculty of
Population and Public Health (SPPH), School of
Graduate
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Adams, David Edwin. "On the gracefulness of girders and big wheels." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ40021.pdf.
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Rodriguez, Jesus. "Simulation of wheels in nonlinear, flexible, multibody systems." Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/12068.
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Faragalli, Michele. "Multi-objective design optimization of compliant lunar wheels." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=117030.
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The development of the wire-mesh wheel of the Apollo Lunar Roving Vehicle was realized through a time consuming trial and error design process, primarily driven by manufacturability and physical testing. Recent wheel development, motivated by renewed interest in lunar surface exploration, utilizes more sophisticated numerical simulation tools. However, many researchers still employ trial and error or parametric approaches to designing the wheels. This thesis proposes a systematic approach to the design optimization of compliant lunar wheels. The problem is decomposed into system and component level analyses. The system level analysis investigates the effect of elastic wheel behaviour on rover and mission performance metrics. This is realized by optimizing concept independent wheel design variables using multi-disciplinary models coupled with optimization algorithms. Wheel concepts are explored by prototyping and physical testing, as well as numerical modelling. The mobility performance metrics of cellular, segmented and iRings wheels are compared to a baseline rubber wheel. In the component level analysis, a multi-objective optimization algorithm is coupled with numerical simulations of wheel-ground interaction to find optimal cellular wheel designs. The effectiveness of the methodology to optimize cellular wheel concepts is verified, and the limitations of the approach examined. Finally, a discussion to extend the proposed methodology to alternative wheel concepts is provided.Le développement de la roue treillis métallique de l'Apollo Lunar Roving Vehicle a été réalisé par un processus d'essais et d'erreurs. Les récents développements de roues flexibles, motivé par un regain d'intérêt pour l'exploration lunaire, ont maintenant à leur disposition des outils de simulation numérique plus sophistiqués. Cependant, la majorité des chercheurs emploient toujours des méthodes expérimentales ou paramétriques pour développer leurs roues. Cette thèse propose une nouvelle approche systématique pour l'optimisation de concepts de roues lunaires flexibles. Le problème est décomposé en deux analyses se rapportant au niveau du système et celui des composantes. L'analyse au niveau du système étudie l'effet du comportement de la roue élastique sur des mesures de performance lors d'une mission du rover. Ceci est réalisé en optimisant les paramètres décrivant une roue flexible à l'aide de modèles multidisciplinaires. Différents concepts de roues sont explorés à l'aide de prototypes et d'essais physiques, ainsi que de modélisations numériques. La performance de chacun des concepts de roues flexibles cellulaires, iRings et segmentés sont comparées à un pneu standard. L'analyse au niveau des composantes effectue une optimisation multi-objective afin de déterminer, par le biais de simulations numériques, le concept optimal de roues flexibles cellulaires. L'efficacité de la méthodologie pour optimiser la roue cellulaire est ensuite vérifiée et les limites de cette approche sont examinées en détail. Finalement, une discussion sur l'application de la méthodologie proposée à des concepts de roues arbitraires est abordée.
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Moreland, Scott J. "Traction Processes of Wheels in Loose, Granular Soil." Research Showcase @ CMU, 2013. http://repository.cmu.edu/dissertations/278.
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This dissertation presents analyses of subsurface motions of soil beneath different traction devices and develops new explanations of traction processes of wheels operating in loose granular soil based on these observations. This dissertation shows how these findings are useful for the development of planetary rover mobility systems.
Shear Interface Imaging Analysis (SIIA), is a new technique, developed as part of this thesis research. SIIA is employed for visualizing the effects of wheel operation on the soil beneath a rim, in richer detail than before possible. SIIA relies on high-speed imaging of sub-surface soil and on computer vision software to produce soil displacement fields, of high fidelity. The resulting data provides new insight and can reveal misconceptions about how wheels generate traction.
Two comprehensive studies relying on SIIA are undertaken: the investigation of wheel grouser mechanics and the investigation of push-roll locomotion. Soil forward motion, at a wheel leading edge, is identified as a key behavior for the grousered wheels. As a result, an equation for grouser height/spacing relationship to achieve a higher performance grouser configuration is developed and validated. This expression relates grouser configuration to wheel parameters (wheel radius) and operational parameters (sinkage and slip).
The soil mechanics behind Push-roll locomotion for high net traction and soft ground applications are presented. SIIA reveals that high thrust generated by push-roll locomotion is due to ground failure of the soil. Confirmation of the type of soil failure and of the application of operation in soft ground (where most vehicles would be embedded), brings forward the mobility gains of this non-typical locomotion mode and as a possible use for future planetary missions.
Additionally, insight into fundamental traction processes such as thrust, sinkage and motion resistance, are discussed with experimental evidence from soil displacement fields. This research proves that accounting for soil motion is of the utmost importance for the understanding of traction in loose, granular soils.
As a result of the specific technique utilized for directly studying soil motion, this research enables improved analysis and new design relevant to planetary rover mobility.
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Jerrett, Charles Francis Arthur. "The effects of forward spray from aircraft wheels." Thesis, University of Hertfordshire, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.394075.
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Cai, Rui. "Assessment of vitrified CBN wheels for precision grinding." Thesis, Liverpool John Moores University, 2002. http://researchonline.ljmu.ac.uk/4972/.
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Florence, Lea C. "Rural-Urban Variations in Meals on Wheels Programs." Digital Commons @ East Tennessee State University, 2020. https://dc.etsu.edu/etd/3700.
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Older adults are living longer than ever before. By 2060, the U.S. population aged 65 or older is projected to reach 98 million. As adults age, the prevalence of chronic diseases and disabilities increases. The need for Meals on Wheels (MOW) services is growing alongside the aging population. Yet, little is known about the geographic variation of services. Little is documented about the organizational capacity of MOW organizations in terms of geography. The current policies supporting home-and community-based services, including MOW, may be insufficient to support all older adults in all types of communities. An analysis of the More Than a Meal® Comprehensive Network Study was conducted to determine geographic variation in services delivered through MOW programs and to document organizational capacity by geography. Chi-squared analyses were performed to identify relationships between twenty services offered through MOW organizations and categorial offerings within nutrition, in-home safety, socialization, and community connections categories. Spidergrams were created to document organizational capacity holistically and for three individual organizations for each of the geographic areas: Rural Only, Partial Rural, and Non-rural Service Areas. Using these findings, a policy analysis was conducted to determine policy recommendations to inclusively support rural older adults.
Older adults living in rural areas access the full complement of services provided by MOW programs differently than do their non-rural counterparts. Specifically, a statistically significant relationship was found between the stratified component of in-home safety for rural, partial rural and non-rural service areas. When evaluated on the individual service offering level, statistically significant relationships between rurality and congregate meals, nutrition education, nutrition assessment, coordination of USDA food assistance programs, and telephone reassurance were seen. Spidergram documentation of capacity created visual representations of geographic similarities and differences. The policy analysis produced three potentially viable policy additions for the Older Americans Act around a provision for innovation programs, a report on in-home safety, and business acumen provisions. This work lays the foundation for further analysis of existing data with a lens of geographic specificity, as well as articulates the importance of looking at organizational capacity as a part of policy recommendations for understanding rural community-based organizations.
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Carthy, Laura. "Linking Wheels for use in quantum information processing." Thesis, University of Manchester, 2010. https://www.research.manchester.ac.uk/portal/en/theses/linking-wheels-for-use-in-quantum-information-processing(ca5addcd-5ce1-4e9d-86f5-e56405a4092c).html.
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Heterometallic Cr7Ni-containing wheels have been identified as potential qubits for use in quantum information processing. The work described in this thesis details attempts to form a variety of multi-qubit systems for the purposes of better understanding the interactions occurring between the wheels and also forming potential 2-qubit quantum gates using redox/photo-active links. Mono-substituted wheels of type [Pr2NH2][Cr7MF8(O2CCMe3)15(L)], where L is acarboxylate with a pendant coordinating group, have been synthesised for use as bulky ligands in coordination chemistry with metal complexes. Various carboxylates have been substituted into the wheels and the products reacted with first row transition metal complexes in order to extend the series of linked-wheel systems. Many of these novel complexes have been characterised by X-ray crystallography, and in certain cases EPR studies have been undertaken to probe the strength of interactions occurring via different bridging units. The first well-established substituted wheel, [Pr2NH2][Cr7NiF8(O2CCMe3)15(O2CPy)] (Py= pyridine), has also been used in reactions with second and third row transition metal centres to show its ability to act as a ligand under more harsh conditions. In addition, the disubstituted product [Pr2NH2][Cr7NiF8(O2CCMe3)14(O2CPy)2] has been reacted with a copper complex in order to form a polymeric structure. Purple wheels of type [Cr7NiF3(O2CCMe3)15(EtGu)(H2O)] have been linked through a variety of extended organic molecules containing a minimum of two pendent pyridyl groups. Use of a ligand containing four pyridyl groups, 2,2´:4,4´´:4´,4´´´-quaterpyridyl(qpy) produced a three-wheel-containing system, creating an interesting modification of the wheel backbone not seen before. A series of transition metal complexes, containing qpy and its extended derivative bbpe, has been synthesised in order to form linked-wheel systems. While none of these systems has to date yielded a crystal structure, a significant amount of evidence has been collected to confirm successful formation of the desired products. UV-vis spectroscopic and electrochemical measurements show that these compounds are photo and/or redox-active,and preliminary luminescence studies indicate that the presence of the wheels quenches the emission from metal-to-ligand charge-transfer excited states. A series of mixed-wheel systems has been synthesised by reacting four different monosubstituted green wheels with four purple wheels (Cr7M, where M = Ni, Co, Mn or Zn). A total of fourteen novel systems has been formed, with two of the attempted reactions failing to occur. EPR studies on Cr7Ni-Cr7Ni linked systems show that the strongest interaction occurs when using isonicotinate as a link, with 4-pyridazinecarboxylate giving the weakest coupling. Studies have also been undertaken on Cr7Ni-Cr7Mn and Cr7Ni-Cr7Zn systems, with the former showing interactions and the latter showing none. Initial work to link wheels together indirectly via their templates was ultimately unsuccessful, but a variety of potential linker molecules were synthesised and are described.
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Docherty, Rebecca Jennifer. "EPR spectroscopy of antiferromagnetically-coupled Cr3+ molecular wheels." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/epr-spectroscopy-of-antiferromagneticallycoupled-cr3-molecular-wheels(d8e2f345-f60f-425a-a630-5b0334601ce5).html.
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Currently, there is interest in the development of molecular-scale devices for use in quantum information processing (QIP). With this application in mind, physical studies on antiferromagnetically coupled molecular wheels [Cr7MF3(Etglu)(O2CtBu)15(phpy)], where M is a divalent metal cation (M = Mn2+, Zn2+, Ni2+) have been pursued. The heterometallic wheels contain an octagon of metal centres, which are bridged by fluoride ions, pivalate groups and a chiral N-ethyl-D-glutamine molecule which is penta-deprotonated and bound to the metal sites through all available O-donors. They are deep purple in colour and they have been named purple-Cr7M. There is antiferromagnetic coupling between adjacent metal centres, J » -8 cm-1, resulting in a non-zero net spin ground state. The spin-Hamiltonian parameters of this family have been determined.At the heterometal site of purple-Cr7M wheels there is a terminal ligand which can be substituted for a variety of N-donor organic ligands. A series of bidentate N-donor linkers has been used to link Cr7Ni wheels (each wheel Seff = 1/2) to create prototype two-qubit systems. Multi-frequency EPR spectroscopy and SQUID magnetometry has been used to extract the spin-Hamiltonian parameters of this family. It has been shown that the single wheels can be linked together electronically as well as chemically. It has been found that for the unsaturated linkers, there is a weaker interaction between Cr7Ni wheels when longer linkers are used. The strength of interaction is smaller for the saturated linkers than for the unsaturated linkers.The formation of 'green'-Cr7M wheels is different, being templated around a cation. Two new types of wheels have been studied: [tBuCONHC6H12NH2C6H12NHCOtBu][Cr7M2+F8(O2CtBu)16] and [Cs?Cr7MF8(O2CtBu)16]·0.5MeCN (where, M = Mn2+, Zn2+, Ni2+), where the former is templated around a long dialkylammonium group and the latter around a caesium cation. The effect of the templating cation on spectroscopic properties has been determined.Physical studies on a family of antiferromagnetically-coupled homometallic clusters have been pursued. They consist of cyclic arrays of homometallic Cr3+ ions in either a octametallic wheel or hexametallic horseshoes. The horseshoes have the general formula: [CrxFx+5L2x-2]n3- (where L = carboxylate). Cr3+ centres are bridged by pivalate groups and fluorides, while Cr3+ centres at the ends of the chain have terminal fluorides completing their coordination sphere. These terminal fluoride groups are labile enough to be substituted, e.g. [EtNH2][Cr6F7(O2CtBu)10(acac)2] is the product of a substitution reaction with acetylacetone.
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Kakar, Seena Gill. "Nutrition on wheels business plan: A strategic analysis." CSUSB ScholarWorks, 2006. https://scholarworks.lib.csusb.edu/etd-project/3047.
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Describes the business plan for an entrepreneurial venture called Nutrition on Wheels, which will be the first locally owned and operated gourmet diet food delivery service in the Coachella Valley of California. The service will provide customized meals to fit the specific dietary needs of its customers. Covers the essential components of the business plan for Nutrition on Wheels including industry analysis, market potential, marketing plans, organization and operational plans, strategic management and a financial plan.
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pogni, matteo. "Numerical study of bicycle racing wheels aerodynamic performances." Doctoral thesis, Università degli studi di Padova, 2017. http://hdl.handle.net/11577/3423273.
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Improving the aerodynamic performance in one of the major challenges in the engineering research
applied to racing bicycle. In fact, aerodynamic drag is the main source of losses in cycling and causes
between 70% and 90% of total losses in flat road pace (i.e., when not climbing).
Moreover, also lateral forces imposed by crosswinds play an important role because they can
destabilize the bike itself.
The body of the cyclist is actually the most important source of drag, because of its relevant frontal
area. However, it is necessary to improve also the bike’s components aerodynamics, which account
for about the 33% of the total drag. This quite relevant percentage is mainly due to the wheels and
the frame design.
According to Greenwell, wheel drag is responsible for 10% to 15% of total aerodynamic drag;
therefore improving the design of this component can reduce the resistance of the bicycle by 2-3%.
These numbers, in view of the high level required by either the today’s competitions or the bicycle
market justify the effort involved in cycling components aerodynamics.
The aim of this work isto assess the capability of CFD RANS simulations to predict the aerodynamic
performance of modern racing bicycle wheels, and therefore build a numerical testing method to
help the comparison between different solution and design.
The Thesis is subdivided in five chapters after an introduction to bicycle aerodynamics and a
literature review of the previous literature regarding the wheel aerodynamics; we give a look at the
theory regarding the computational fluid dynamics and the different model used in this work.
An initial method is build tested validated and refined showing the capabilities of the CFD to resolve
the aerodynamic forces on a rotating wheel using a simpler steady-state analysis, applying the MRF
method imposing a rotating frame to the region containing the wheel.
Different wheels were tested and the results compared with wind tunnel results obtained by
Campagnolo; using this method we compared different design and introduced a performance index
to characterize the wheel performances.
We performed brief analysis using and unsteady state model and a rigid body motion to compare
the method with the steady model.
Good agreement with experimental wind tunnel studies suggests that the approach we outline
holds considerable promise. Owing to the flexibility of this methodology, it is now possible to use
CFD to provide more definitive answers on some of the open questions within the competitive
cycling and triathlon communities.
Additional word regard the testing of an open-source code, because commercial codes are indeed
expensive, we tried a simple three-spoke model with the OpenFOAM code, and highlight the pro
and the cons of an open-source code.
Finally, there is a brief description of different force balance layouts.Migliorare l'aerodinamica delle biciclette da competizione è molto importante, infatti, a seconda delle condizioni, la resistenza aerodinamica è tra il 70% e il 90% della resistenza totale, oltretutto le forze laterali possono influire la stabilità del veicolo. Questo lavoro si occupa principalmente dell'aerodinamica delle ruote per biciclette da competizione nel tentativo di sviluppare un modello matematico CFD per calcolare le prestazioni di diversi profili e configurazioni, le ruote infatti sono responsabili tra il 10% e il 15% del drag di una moderna bici da competizione. Il lavoro è suddiviso in 5 capitoli, nella prima è dedicata alla letteratura scientifica sull'argomento, sull'aerodinamica della bici e delle ruote in specifico, la seconda è dedicata alla teoria delle simulazioni fluidodinamiche, poi si passa alla costruzione del metodo di lavoro, al primo modello sviluppato, i primi risultati e le conseguenti modifiche al modello e alla validazione con dati della galleria del vento, ottenendo un buon livello di validazione del metodo, in seguito ho sviluppato un modello su software opensource OpenFoam. In conclusione una breve descrizione di possibili pedane di forza utilizzabili per i test in galleria del vento.
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Agahi, Maryam. "Grinding polycrystalline diamond using a diamond grinding wheel." Access electronically, 2006. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20061114.150854/index.html.
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Lake, Kavan O. "Saving lives and money two wheels at a time." Thesis, Monterey, California : Naval Postgraduate School, 2010. http://edocs.nps.edu/npspubs/scholarly/theses/2010/Mar/10Mar%5FLake.pdf.
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Thesis (M.S. in Manpower Systems Analysis)--Naval Postgraduate School, March 2010.Thesis Advisor: Henderson, David R. ; Hatch, William D. "March 2010." Author(s) subject terms: Motorcycle safety training, motorcycle accident, motorcycle fatality, motorcycle injury, motorcycle life insurance cost, motorcycle hospitalization cost, military occupational specialty cost. Includes bibliographical references (p. 69-70). Also available in print.
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Gerrard, Douglas R. "Dynamic control of a vehicle with two independent wheels." Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1997. http://handle.dtic.mil/100.2/ADA340452.
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Thesis (M.S. in Electrical Egnineering) Naval Postgraduate School, September 1997."September 1997." Thesis advisor(s): Xiaoping Yun. Includes bibliographical references (p. 27). Also available online.
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HassabAllah, AbdulRahman Adam. "Modelling the interaction between rigid wheels and deformable soils." Thesis, University of Newcastle Upon Tyne, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239236.
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Ewin, Nathan. "Traction control for electric vehicles with independently driven wheels." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:dfc99786-fe17-4225-bd91-3ab83416981f.
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The necessity to reduce climate related emissions is driving the electrication of transportation. As well as reducing emissions Electric Vehicles (EV) have the capability of improving traction and vehicle stability. Unlike a conventional vehicle that uses a single Internal Combustion Engine (ICE) to drive one or both axles, an EV can have an electric machine driving each of the wheels independently. This opens up the possibility of using the electric machines as an actuator for traction control. In conventional vehicles the hydraulic brakes together with the ICE are used to actuate traction control. The advantages of electric machines over hydraulic brakes are precise measurable torque, higher bandwidth, bidirectional torque and kinetic energy recovery. A review of the literature shows that a wide range of control methods is used for traction control of EVs. These are mainly focused on control of an individual wheel, with only a minority being advanced to the experimental stage of verication. Integrated approaches to the control of multiple wheels are generally lacking, as well as verication that tests the vehicle's directional stability. A large body of the literature uses the slip ratio of the wheel as the key control variable. A signicant challenge for slip-based traction control is the detection of vehicle velocity together with the calculation of slip around zero vehicle velocity. A traction control method that does not depend upon vehicle velocity detection or slip ratio is Maximum Transmissible Torque Estimation (MTTE), after Yin et al. (2009). In this thesis an MTTE based method is developed for a full size electric vehicle with independently driven rear wheels. The original MTTE method for a single wheel is analysed using a simple quarter vehicle model. The simulation results of Yin et al. (2009) are in general reproducible although a lack of data in the original research prevents a quantitative comparison. A modication is proposed to the rate compensation term. Simulation results show that the proposed modication ensures that the torque demand is delivered to the wheel under normal driving conditions, this includes negative torque demand which is not possible for MTTE, Yin et al. (2009). Enabling negative torque demands means that the proposed traction control is compatible with higher level stability control such as torque vectoring. The performance of the controller is veried through a combination of simulation and vehicle based experiments. Compared with experiments, simulations are fast and inexpensive and can provide greater insight as all of the variables are observable. To simulate the controller a high delity vehicle model is required. To achieve this it is necessary to initially validate the model against experimental data. Simulation verication using a validated vehicle model is lacking in the literature. A full vehicle model is developed for this thesis using Dymola, a multi-body system software tool. The model includes the full suspension geometry of the vehicle. Pacejka's "Magic Formula" is used for the tyre model. The model is validated using Delta Motorsport's E4 coupe. The two Wheel Independent Drive (2WID) MTTE-based traction controller is derived from the equations of motion for the vehicle. This shows that the maximum transmissible torque for one driven wheel is dependent on the friction force of both driven wheels, which has not been shown before. An equal torque strategy is proposed to maintain vehicle directional stability on mixed-μ roads. For verication the 2WID-MTTE controller is simulated on the validated vehicle model described above. The proposed 2WID-MTTE controller is benchmarked against a similar method without the equal torque strategy, termed Independent MTTE, as well as a method combining Direct Yaw Control (DYC) and Independent MTTE. The three controllers are simulated for a vehicle accelerating onto a split-μ road. The results show that the proposed 2WID-MTTE controller prevents the vehicle spinning o the road when compared to Independent MTTE. 2WID-MTTE is found to be as eective as DYC+Independent MTTE but is simpler in design and requires fewer sensors. The proposed 2WID-MTTE controller is also simulated for a vehicle accelerating from a low- to high-μ road. This is done to assess the controller's ability to return to normal operation after a traction event, and because there are no simulations of this type for MTTE control on a high delity vehicle model in the literature. The results show that oscillations in the tyre-road friction force as the wheel transitions across the change in μ somewhat impede the return of the controller's output torque to the torque demand. The 2WID-MTTE controller is implemented on Delta Motorsport's E4 coupe by integrating it into the vehicle's Powertrain Control Module (PCM). This is experimentally tested for the vehicle accelerating across a range of surfaces at the MIRA proving ground. The experimental tests include high- to low-μ, low- to high-μ and split-μ roads. The results for the high- to low-μ road tests show that 2WID-MTTE control prevents the vehicle spinning when compared to no control. Similar to the simulation, the results of the low- to high-μ road experiment show that the controller output torque is also impeded from returning to the demand torque. Observation of the estimated friction force together with the on-board accelerometers conrm that this is due to tyre friction oscillating after the transition. This justies the use of a tyre model with transient dynamics. The proposed 2WID-MTTE controller uses wheel velocity and torque feedback to estimate friction torque. These signals are obtained from the vehicle's motor controllers via a Controlled Area Network (CAN) bus. The 2WID-MTTE controller is benchmarked against Independent MTTE that uses wheel velocity measured directly from the wheel hub sensors and the torque demand to estimate friction torque. The results show that the delays introduced by the CAN bus increase wheel slip for the 2WID-MTTE controller. However, the equal torque strategy means that 2WID-MTTE controller maintains greater vehicle directional stability, which is more important than the pursuit of greater acceleration.
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Jensen, Emilie. "Measuring cost effectiveness of product wheels in food manufacturing." Thesis, Kansas State University, 2014. http://hdl.handle.net/2097/32786.
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Master of AgribusinessDepartment of Agricultural Economics
Keith Harris
The focus of this research is to create a production schedule that will increase capacity while staying within business constraints of shelf life and warehouse space in a industrial food processing environment. The results support that product wheels maximize process responsiveness by lengthening production runs, and increasing safety stock inventory. In doing so, it maintains acceptable customer service levels and minimizes overtime costs. This study develops a model that simulates the relevant variables impacting the performance of the operation. The results show significant cost reductions are achieved by eliminating changeovers, increasing line capacity, safety stock levels protect against 99% of order variation, and warehouse space is available to house increased cycle stock and safety stock. Given the results on this line, I recommend expanding the model to other food processing locations within the business to further increase capacity and decrease overtime expenses.
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MacCarthy, Nigel Hugh. "An experimental study of the aerodynamics of exposed wheels." Thesis, Imperial College London, 2010. http://hdl.handle.net/10044/1/8488.
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Sun, Xun. "Design of Piezoelectric Reaction Wheels for Nanosatellite Attitude Control." Thesis, The University of Sydney, 2019. https://hdl.handle.net/2123/22135.
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The Attitude control system is one of the most critical subsystems for nanosatellite missions, especially those missions which carry pointed payloads. A precise attitude control system can increase the payload compatibility and discover the new potential of nanosatellites. In this thesis, novel attitude control actuators and control algorithm base on piezoelectric ultrasonic motors were developed to overcome the limitations of size and power of nanosatellites, and the disadvantages of conventional nano reaction wheels. This design consists of a miniaturised driving circuit design for piezoelectric ultrasonic motors and actuators; a linear ultrasonic motor base gimbal design; a dual actuator reaction wheel design and a modified backstepping controller design for dual actuator attitude control systems of nanosatellites. The results of experiments and simulations show that the piezoelectric ultrasonic motors can be a part of nanosatellites attitude control actuators. The piezoelectric ultrasonic motors and actuators can significantly improve the accuracy and the low-speed control linearity of conventional reaction wheels of nanosatellites.
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Tolley, Rebecca. "Disco, Tattoos and Tutus: Blue Collar Performances on Wheels." Digital Commons @ East Tennessee State University, 2012. https://dc.etsu.edu/etsu-works/5739.
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Thompson, Kevin A. Rich Beverly Susan Meier Sherry L. "Students' understanding of trigonometry enhanced through the use of a real world problem improving the instructional sequence/." Normal, Ill. : Illinois State University, 2007. http://proquest.umi.com/pqdweb?index=0&did=1417799391&SrchMode=1&sid=14&Fmt=2&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1207668571&clientId=43838.
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Thesis (Ph. D.)--Illinois State University, 2007.Title from title page screen, viewed on April 8, 2008. Dissertation Committee: Beverly S. Rich, Sherry L. Meier (co-chairs), M. A. (Ken) Clements, Anthony W. Lorsbach. Includes bibliographical references (leaves 217-222) and abstract. Also available in print.
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García, Estébanez Jesús. "GPS-IMU Integration for a Snake Robot with Active Wheels." Thesis, Norwegian University of Science and Technology, Department of Engineering Cybernetics, 2009. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-9107.
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A snake robot will be defined herein as any multilink robot for whose shape and motion capabilities are reminiscent of a snake like PiKo [1]. PiKo is a five links snake robot with active wheels designed by SINTEF in collaboration with the Norwegian University of Science and Technology (NTNU). Researchers have been greatly interested in the development of robots like PiKo because of its shape versatility and motion capacity in difficult terrains. These skills and properties are useful for rescue teams working in earthquakes, pipe inspection operations and other utilities where access and movement in the terrain are typically difficult. When a working team decides to develop a snake robot, an important point to consider is the development of an efficient navigation system that reaches an accurate position of the robot. Technically speaking, it is prudent to design at the same time a state observer that gives us at least the real time position and velocity information of the robot body to be controlled. The relevance of this information is derived from every control action applied to the robot will require some information about the situation of the robot over time. The controller will need feedback about the robot dynamics and the effect that the control actions have caused. Typically this information has three sources: the information that comes from external sensors, that from internal sensors that transmitting to the control place the measurements from the sensors in the robot body and estimated data from a physical model. All of these feedback sources have some advantages and disadvantages. Implementing an external observer, with external sensors, will not cause space problem with sensors location in the robot body, but when the robot is working inside a pipe, underground or in another hard environment where the optical, magnetic or radio frequency contact is difficult or impossible, the information reception from an external observer is too difficult and expensive or simply impossible. Locating internal sensors in the body of the robot may solve has the problem with the measurements reception, but still pose some difficulties which must be considered by the designer. Many times space becomes a problem when locating some sensors inside the robot body due to size and weight constraints within the robot body. Basing the navigation system instead on a physical model that simulates the robot motion invites the possibility of error due to simplifications taken during the mathematical and physical development. It is impossible to develop a perfect physical model since all the variables, forces, and parameters that depend on the nature characteristics usually are random process and we can just raise a useful factor estimating the average of these effects in our concrete situation. In this thesis a navigation system with a GPS (Global Positioning System) and IMU (Inertial Measurement Unit) fusion was achieved. This navigation system will be work as long the GPS signal is available. The application of the fusion technique further reduces one order the potential errors inherent in using only the GPS navigation system. When the robot will encounter locations where the GPS signal is impossible, this thesis will present a set of tools that not being a universal solution, it will be a set of mathematical tools that depending on the case could give us an accurate navigation system. During the time the GPS signal reception is impossible, this thesis presents the development and implementation of a physical model for a snake robot with active wheels which simulates the snake robot running behavior and studies the possibility to use the trajectory estimated by the model for reaching an accurate navigation system.
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Clarsen, Georgine. "The vote on wheels : Australian women and motoring, 1915-1945 /." Connect to thesis, 1997. http://eprints.unimelb.edu.au/archive/00000649.
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Ward, Michael James. "Practical models for ring-rolling of railway wheels and tyres." Thesis, University of Manchester, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.616283.
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The ring-rolling process was first developed in the UK in the mid nineteenth century and is still widely used as the preferred method of forming seamless rings for many aerospace and automotive applications, as well as for producing railway wheels and tyres. This thesis describes the development of a finite element based mathematical model that can be used to simulate the process. The model has been developed with the intention of practical application within railway wheel manufacturer Adtranz New Wheel Products Division. A detailed review of previous research on the process is presented. The key observation from that review is that all attempts at modelling ring rolling have suffered from severe run time difficulties which are predominantly due to lack of constraint and the large number of increments required to complete a simulation. Based on this fact the focus of development activities has been on identifying ways in which the simulation can be run in realistic time frames. The usefulness of a simplified 2D method is assessed, with the conclusion that while some beneficial information might be gained by such an approach, 3D simulation is the only way of fully representing material deformation during the process. Attempts at improving run time of 3D modelling have focused on two main areas. Firstly an efficient arbitrary Lagrangian Eulerian finite element flow formulation has been adopted. This gives the advantages of allowing mesh density to be concentrated on roll gap regions, and removing some of the convergence problems associated with frequent contact changes. Secondly the issue of solution of the discretised flow formulation equations is examined in some detail. A range of well known solution methods are considered as potential ways of improving on direct methods, with limited success. Significant potential benefits are found to result however from a new approach, the successive preconditioned conjugate gradient method. This method, together with tests of its effectiveness, is described in some detail. The resulting model is tested against experimental work performed by previous authors. Attempts to integrate the work into Adtranz are also described. These have included consideration of usability and management issues, and illustrative case studies.
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PEREIRA, MARCELO DA CRUZ. "POSITION CONTROL OF AN IN-PLANE PENDULUM USING REACTION WHEELS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2011. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=19095@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROEsse trabalho apresenta o estudo, manipulação e controle de um sistema de 2 graus de liberdade conhecido como pêndulo planar usando rodas de reação para alcançar certa posição, sendo o conceito básico desse sistema fundamentado na dinâmica de um pêndulo invertido. Utilizou-se o controle clássico PID e também controle Fuzzy, sendo gerado um modelo matemático simulado valendo-se de MatLab para análise desses controles, através da ferramenta Simulink que permite um auto ajuste para o controle do sistema. O PID foi construído de acordo com esse auto ajuste e também usando o método de Ziegler Nichols discutindo-se as diferenças entre os dois procedimentos. O controle Fuzzy foi elaborado montando-se o banco de regras adaptando a estratégia de controle para que se torne mais propícia para o sistema. Atritos nas juntas, e no motor foram contabilizados no modelo matemático. Por fim foi montado um modelo real usando uma placa de aquisição de dados em conjunto com o LabView para controle e uma placa micro controlada chamada Arduino e um encoder para aquisição de ângulos. Erros de medição e desbalanceamento do sistema são problemas que não puderam ser totalmente eliminados, mas tentou-se reduzir ao máximo seus efeitos. Resultados numéricos e experimentais são apresentados comparando cada controle e cada montagem e analisando as diferenças.
This paper presents the study, manipulation and control of a two degrees of freedom system, known as planar pendulum, using reaction wheels to achieve a certain position, the basic concept of this system being the dynamics of an inverted pendulum. The classic PID controller was proposed as well as a Fuzzy control. The mathematical model was generated to be used in MatLab numerical simulations of these controls, using the Simulink tool which allows a self-adjustment of the controller of the system. The PID control was built according to the self-tuning of Simulink and also using the Ziegler Nichols method. The differences between both are discussed. Fuzzy control was designed, creating the bank of rules and looking for a control strategy more suitable for the system. Friction in joints, and drives were taken in account in the mathematical modeling. Finally a real model was built using a data acquisition board in conjunction with LabView for control and a microcontroller board called Arduino, as well as an encoder for the acquisition of angles. Measurement errors and unbalance of the system are problems that could not be completely eliminated, but were kept to a minimum. Numerical and experimental results were compared for each control and for each assembly and their differences were discussed.
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Woolfson, Robert. "Spins in rings : new chemistry and physics with molecular wheels." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/spins-in-rings-new-chemistry-and-physics-with-molecular-wheels(1cce143a-105e-4f8c-ac19-388f793fddc4).html.
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This thesis explores the synthesis and characterisation of a range of molecular wheels containing unpaired electron spins. These molecular spin systems are of considerable interest, both for the insight they provide into the physics of such systems and for their potential as quantum bits ("qubits") in a quantum information processing device. In particular, this thesis explores using these wheels to meet criteria 1 and 5 of the DiVincenzo criteria. The synthesis of a novel homometallic and nonametallic ring of CrIII ions is introduced, along with extensive physical characterisation. Inelastic Neutron Scattering measurements suggest that the molecule has an almost degenerate S = 1/2 ground state with only 0.1 meV separation, making this ring a near perfect example of a Type I frustrated spin system. Chemical modification of the heterometallic {Cr7M} family of wheels with both hard and soft Lewis base functionality is also explored. Using a triphenylphosphine derivative, the coordination chemistry of a highly sterically hindered mono-substituted triphenylphosphine derivative with gold is explored, yielding new arrangements of the wheels. Changes in the electronic and steric properties of the system are studied by a combination of 31P NMR spectroscopy and DFT modelling, revealing dramatic changes in the phosphorus donor properties. The effect of this ligand substitution on the anisotropy tensor of CoII contained in a heterometallic {Cr7Co} ring is explored using variable temperature 1H NMR spectroscopy. Using a combination of the experimentally observed 1H NMR dipolar shifts and computational modelling, a significant change in the anisotropy tensor of the cobalt is found. Finally, as part of a g-engineering approach to qubit design the chemistry of the octametallic {Cr7Ni} ring functionalised with triphenylphosphine oxide is introduced. Initial efforts towards developing a hybrid {Cr7Ni}2Ln (Ln = Gd, Eu) qubit system, along with characterisation by EPR and luminescence spectroscopy, suggest that this may be a route to developing a qubit with the capacity for optical control of the communication.
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Biju, Dona. "A parametric study of oil-jet lubrication in gear wheels." Thesis, Linköpings universitet, Mekanisk värmeteori och strömningslära, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-150786.
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A parametric study of oil-jet lubrication in gear wheels is conducted using Computational Fluid Dynamics (CFD) to study the effect of the different design parameters on the cooling performance in a gearbox. Flow in oil jet lubrication is found to be complex with the formation of oil ligaments and droplets. Various hole radii of 1.5, 2 and 2.5 mm along with five oil velocities is analyzed and it is found that at lower volumetric rates, velocity has more effect on the cooling and at higher volumetric rates, hole size has more effect on the cooling. At higher velocities, the heat transfer is much greater than the actual heat production in the gear wheel, hence these velocity ratios are considered less suitable for jet lubrication. At low velocity ratios of below 2, the oil doesn’t fully impinge the gear bottom land and the sides leading to low cooling. Based on the cooling, impingement length and amount of oil lost to the casing surface, 2 mm hole with a velocity ratio of 2.225 is selected for a successful oil jet lubrication. Varying the inlet position in X, Y and Z directions (horizontal, vertical and lateral respectively) is found to have no improvement on the cooling. Making the oil jet hit the gear wheel surface at an angle is found to increase the cooling. Analysis with the use of a pipe to supply oil was conducted with circular and square inlet and it was found that the heat transfer decreases in both cases due to the splitting of oil jet caused by the combination of the effects of high pressure from the pipe and vorticity in the air field. A method has been developed for two gear analysis using overset meshes which can be used for further studies of jet lubrication in multi-gear systems. Single inlet is found to be better for cooling two gear wheels as it would require a reduced volumetric flow rate compared to double inlets. Oil system requirements for jet lubrication was studied and it was concluded that larger pumps have to be used to provide the high volumetric rates and highly pressurized oil required. On comparing the experimental losses from dip lubrication and the analytical losses for jet lubrication, dip lubrication is found to have lesser loses and more suitable for this case. Good quality lubrication would reduce the fuel consumption and also increase the longevity of gearboxes and hence more research into analyzing alternate lubrication systems can be carried out using the results from this thesis.
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de, Miranda Adriana. "Water architecture in the lands of Syria : the water-wheels." Thesis, SOAS, University of London, 2006. http://eprints.soas.ac.uk/28678/.
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This thesis aims to evaluate the typology of water-wheels in Syria as an ancient type of water architecture which has had a fundamental role, over the centuries, for irrigation and supplying water to houses and public constructions. So far these devices have been studied in terms of their hydraulic and technological aspects, while their architectural and artistic qualities have often been neglected. The research provides a historical, architectural and iconographical study of these structures, focusing on those located in West Syria, where most water-wheels were built and have high artistic value. The study looks at their architectural aspects and artistic significance, and identifies precise classifications by examining the shape and design of the installations. The thesis develops in three parts. The first part presents a detailed analysis of the typology and sources related to its origin and development. The second part, mainly based on architectural material and on the results of fieldwork done on the sites, highlights the cultural, historical and architectural value of the Syrian installations, showing their significant characteristics and advantages, the reasons of their uniqueness and of their wide diffusion until recent times. The third part deals with the relationship between water-wheels and modern irrigation systems, and attempts to evaluate the feasibility of renovating water-wheels as a sustainable system, as well as an example of historical and cultural heritage.
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Naarumanchi, Anuroop. "WEAR MECHANISM OF INTERMETALLIC BONDED DIAMOND COMPOSITE FOR GRINDING WHEELS." OpenSIUC, 2014. https://opensiuc.lib.siu.edu/theses/1572.
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In the present work, wear mechanism of intermetallic bonded diamond is studied, and wear of intermetallic bonded diamond is compared to current grinding wheel and tungsten carbide. In previous work research conducted on IBD's, diamonds are successfully dispersed in intermetallic alloy of nickel aluminde and tungsten carbide, sintered at 1400⁰C without forming graphite. IBD samples are outperforming materials used for wear resistance replacing tungsten carbide cermets, polycrystalline diamond composites. Rubbing current grinding wheel against IBD, if current grinding wheel wear is more than diamond containing IBD, then IBD will be a better grinding wheel.
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Pruti, Faruk. "Development of composite grinding wheels for hard and soft metals." Thesis, University of East London, 2012. http://roar.uel.ac.uk/1440/.
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This research investigates the performance of grinding wheel in terms of its internal granular particles and their effect on the surface finish for both soft and hard metals subjected to both dry and wet conditions of use. The study considers the properties of materials of construction including hardness of the granular particles and their size and distributions that affects the grinding wheel efficiency in abrading of soft and hard metal surfaces. Furthermore, in order to improve grinding performance, the mechanism of clogging the cutting surface of the grinding wheel as a function of for example, the surface properties of granular particles and the chips formed during the grinding operation have been considered. Objective of this project is to study the overall sharpness of the grinding wheel in terms of its internal granular particles and their effect on the surface finish for both soft and hard metals at different conditions of use. The properties of materials of construction including hardness of the granular particles that affects the grinding wheel efficiency in abrading of soft and hard metal surfaces have been studied. During this project two novel grinding wheels, namely single grooved and crossed grooved wheels, have been developed and their performance has been compared with a selected commercial grinding wheel, the design of grinding wheels incorporated an innovative surface profile which has been shown to be capable of taking potentially large depths of cut at high wheel and workpiece speeds to create a highly efficient material removal process. This aggressive processing generated high temperatures in the contact zone between the wheel and workpiece. The voltage measured by oscilloscope during grinding of different workpiece materials including mild steel, brass and aluminium bars was related to the temperature generated between wheels and workpiece materials. Temperatures in the ground surface can be predicted with a knowledge of the specific grinding energy and the grinding parameters used. Specific grinding voltage recorded at high specific material removal rates demonstrated a constant value of specific grinding heat dependent on cutting and contact conditions, improving accuracy of the predictive model. 4 Cutting and contact conditions in the different grinding wheels vary dependent on their surface patterns. This thesis shows how temperature, contact stresses, material removal rates vary with the surface profile, size and orientation of the abrasive particles of the grinding wheel, affecting the performance of the grinding wheel during the grinding operations. Redesigning grinding wheels by making grooves on surface of wheel, material removal rate was increased and less voltage has been recorded. Also, time for redressing wheels was reduced. The wheel surface of crossed grooves shape showed a significant improvement in grinding of soft materials e.g. aluminium. Finally, the different stress distribution, including von_Mises, principal stresses and shear stresses, in the grinding wheels and the three workpiece bars during the grinding process were investigated using Finite Element Analysis (FEA) technique. The maximum von-Mises stress value of the brass bar was found to be 173.2 MPa. Hence the strength of produced grinding wheel calculated as 207 MPa which was extensively higher than the maximum von-Mises stress value obtained from FEA profile, resulting 19.5% higher strength in crossed grooves wheel.
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QUARANTA, EMANUELE. "Investigation and optimization of the performance of gravity water wheels." Doctoral thesis, Politecnico di Torino, 2017. http://hdl.handle.net/11583/2674225.
Full textAbstract:
Water wheels are rotating hydraulic machines that were introduced thousands of years ago to generate energy from water. Gravity water wheels are driven by the weight of the water flow and a portion of the flow kinetic energy. In the last decades, due to the increasing diffusion of micro hydropower plants (installed power less than 100 kW), gravity water wheels are being recognized as attractive hydraulic machines to produce electricity. Unfortunately, most of the engineering knowledge on water wheels is dated back to the XIX century, with several gaps and uncertainty. Additional work is still needed to fully understand the power losses and the performance within water wheels, that could lead to further improvements in efficiency.
The scope of the present thesis is the investigation and improvement of the performance of gravity water wheels. This aim was achieved using physical experiments to quantify water wheels performance under different hydraulic conditions, theoretical models to estimate and predict the efficiency, and numerical simulations to optimize the design. Undershot, breastshot and overshot water wheels were investigated, in order to give a wide overview on all the kinds of gravity water wheels.
Sagebien and Zuppinger undershot wheels were investigated at Southampton University, under the supervision of prof. Gerald Muller, from October 2015 until April 2016. These two wheels differ based on the shape of the blades. The blades of Sagebien wheels are optimized to reduce the inflow power losses, while those of Zuppinger wheels are conceived to minimize the outflow power losses. The objective of the experiments was to understand which of the two designs is better in term of efficiency. The tests showed that the Sagebien type exhibits a more constant efficiency as a function of the flow rate and the hydraulic head than the Zuppinger type. The maximum efficiency (excluding leakages) was identified as 88%.
Breastshot water wheels were investigated experimentally, theoretically and using numerical Computational Fluid Dynamic (CFD) methods at Politecnico di Torino. The maximum experimental efficiency was estimated as 75% using a sluice gate inflow. A vertical inflow weir was also investigated, and found to have a more constant efficiency versus the rotational speed of the wheel, but with similar maximum values. A theoretical model that was developed to estimate the power output, power losses and efficiency, had a discrepancy with the experiments of 8%. A dimensionless law was also developed to estimate the power output. Numerical CFD simulations were performed to understand the effects of the number and shape of the blades on the efficiency. The optimal number of blades was 48 for the investigated wheel, and the efficiency can be improved using a circular shape. The numerical discrepancy with experiments was less than 6%.
Overshot water wheels were investigated using a similar approach as done for breastshot wheels, and were found to have a maximum experimental efficiency of 85%. A theoretical model was developed to estimate the power losses and the efficiency, in particular to quantify the volumetric losses at the top of the wheel, that is the fraction of the flow which can not enter into the buckets and that is lost. Then, numerical simulations will be started to try to improve the wheel efficiency, reducing the previous volumetric losses. More specifically, a circular wall around the periphery of the wheel was added to the original design, leading to a performance improvement up to 60%.
The results of this work show that water wheels can be considered attractive hydropower converters.
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WEN, CHAO-YUAN, and 溫兆源. "Control of single spherical wheel robot driven by omni wheels." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/02545169972589006627.
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碩士中華大學
電機工程學系碩士班
99
This thesis mainly discusses the control of a spherical robot using Omni wheels to drive a spherical wheel. The dynamical model is derived from Euler Lagrange approach. Therefore, seven different control methods are presented which can achieve a constant speed at a vertical balance altitude. The proposed control methods can be categorized into two algorithms. The first algorithm is the variable structure system control (VSSC) in which the time needed to enter the sliding surface or to reach the stable point can be adjusted by parameters. The second one is the nonlinear feedback, but its smoothing input is different from the switching input of variable structure system control (VSSC). The constant speed of the spherical robot with vertical balance altitude can be achieved by both algorithms and be verified by simulations.