Dissertations / Theses: 'Sliding'

1

Borowicz, Betrus Melissa. "SKY SLIDING." Miami University / OhioLINK, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=miami1055794396.

Full text

APA, Harvard, Vancouver, ISO, and other styles

2

Fosstveit, Håvar Aambø. "Intelligent Sliding Doors." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for datateknikk og informasjonsvitenskap, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-18343.

Full text

Abstract:

You can see sliding doors everywhere, be it at the grocery store or the hospital. These doors are today mostly based on naive, motion sensing, and hence not very intelligent in deciding to open or not. I propose a solution by replacing the traditional sensor with the more sophisticated Microsoft Kinect depth mapping sensor allowing for skeletal tracking and feature extraction. I have applied hidden markov models to the behavioural features to understand the human intentions. Combined with a few simple rules, this solution proved to be accurate in 4 out of 5 times in understanding the user's intention in a controlled laboratory test.

APA, Harvard, Vancouver, ISO, and other styles

3

Solem, John Sverre. "Intention-aware Sliding Doors." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for datateknikk og informasjonsvitenskap, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-13696.

Full text

Abstract:

In this project I have designed a model of features, human behavior and intentions. The model suggests a set of features that can be used to describe the interaction between a human being and an automated sliding door. The model also defines symbols representing value sets for the features. The symbols are then combined in order to describe different events, mapping features to intentions. This model provides a framework guiding the capturing process as well as the reasoning process.Further, I have designed a mechanism for capturing human movement and extracting the features as suggested by the model of features, human behavior and intentions. The solution components are based on research done within computer vision, where different tools and algorithms were reviewed and evaluated. Parts of the suggested solution are provided as software libraries, while others had to be implemented. The solution includes using an Xbox Kinect as a sensor device, and the OpenNI framework together with the middleware NITE for Human body tracking and skeletal joint extraction.A reasoning mechanism was designed, that utilizes the designed model in order to reach a conclusion about the intention of a human interacting with the door. Different reasoning techniques were reviewed in context of the sliding doors problem. Based on the review I suggest using rule-based reasoning. By using the events described in the model and by giving values to the different symbols I was able to form the rules for the reasoning process.The designed mechanisms were put together in an implementation in C/C++ comprising depth and RGB image capture, body tracking, user handling and feature extraction, rule-based reasoning and door control.A motorized sliding door was built, together with a door controller allowing a computer to interface with the door, giving open and close commands.Finally, the door was tested both through a live demo and a laboratory style, structured observation. The door proved a superior performance to the traditional sliding doors when it came to identifying negative intentions, thus reducing the number of false positives drastically. However, both false positives and false negatives occurred, leaving room for improved accuracy.With my solution I have managed to interpret the intention of a user interacting with an automated sliding door. I have lifted the reasoning process to a symbolic level, dealing with symbols and events easy to understand. Although the model is limited to a very specific domain, and the solution has got some limitations and weaknesses, this is a good starting point for further work.

APA, Harvard, Vancouver, ISO, and other styles

4

Kato, Hirotaka. "Sliding wear of nitrided steels." Thesis, Brunel University, 1993. http://bura.brunel.ac.uk/handle/2438/5200.

Full text

Abstract:

The unlubricated sliding wear behaviour of gas nitrided, plasma nitrided, and ferritic nitrocarburized BS970,905M39 (EN41B) steels was investigated systematically from an engineering point of view. Commercial nitriding processes were employed, and the wear studies were carried out using a pin-on-disc machine over a wide range of sliding speeds and applied loads. The worn specimens and wear debris were examined by several techniques; including optical and electron microscopy and X-ray analysis. A sharp wear rate transition between mild and severe regimes was identified by varying the load for both untreated and gas nitrided steels. The wear rate was reduced by gas nitriding by up to two orders of magnitude, depending on the sliding condition. Moreover, gas nitriding expanded the mild wear region toward higher loads and sliding speeds. In the mild regime an oxidative wear mechanism operated, contrasting with the metallic wear in the severe regime. Wear maps for untreated and gas nitrided steels have been constructed, which show the dominant regimes of the wear mechanisms. A "wear-face-limited" gas nitrided pin test showed that the benefit of the treatment was lost once the effective surface layer was completely worn away. It is suggested that hardness has a crucial role in determining the wear rate through nitrided diffusion layers. A thick and porous compound layer produced by gas nitriding showed a poor wear behaviour owing to its brittleness, while a thin nitrocarburized E-Fe3N compound layer exhibited a low wear rate. There was no significant difference between the nitride steels in terms of transition load and wear rate. However, the wear lives of the nitrided layers were dependent on their case depth. Severe wear should be avoided in engineering component design, and operating conditions should ensure that only mild wear occurs. Both the hardness profiles and the cost performance of nitriding processes should be considered in the selection of nitriding treatments.

APA, Harvard, Vancouver, ISO, and other styles

5

Rorrer, Ronald Alvin Lee. "Frictional oscillations in elastomeric sliding." Diss., This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-07282008-134509/.

Full text

APA, Harvard, Vancouver, ISO, and other styles

6

Salomon, Johan. "New materials in sliding bearings." Thesis, KTH, Maskinkonstruktion (Inst.), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-175891.

Full text

Abstract:

Increasing demands for lower emissions from heavy trucks and buses creates new demands on the components in the engine. One such component is the journal bearing which is used at many positions in the engine. Implementing a start-stop system in a truck engine leads to that the crankshaft journal bearing gets worn out too quickly. A journal bearing is a sliding bearing with a constant flow of oil. When the journal starts rotating an oil film is formed between the bearing and the journal, separating the journal from the bearing surface when the rotational speed is high enough. When this happens a hydrodynamic oil film is formed. During start and stop the bearing and journal passes through boundary and mixed lubrication regimes. The increase in starts and stops leads to a vast increase in the time that the bearing is experiencing boundary and mixed lubrication. During these regimes the journal comes in contact with the bearing surface and eventually leads to wear. This thesis has compared two new materials provided by Höganäs AB with an existing bearing as a reference material. The new materials were laser cladded onto bearing shells and sent to Scania for grinding and testing. The thought was to use a start-stop test rig at KTH that simulates start-stop cycles. The reference bearings were first run in the test rig, but when the shells with the new materials arrived it turned out that they would not fit in the test rig. This created the need for a new test method on a short notice and a reciprocating tribometer at Scania was chosen. The tribometer underwent a number of modifications to be able to fit the samples. Five tests with each new material and the reference material were carried out. The tests ran for 60 minutes except for a long term test that ran for 600 minutes. The results showed that the material designated “S”, which had a solid lubricant, had a coefficient of friction similar to the reference material, but produced less wear and could handle a higher load. The thesis has also proved that the start-stop test rig at KTH works well and can deliver reliable results.
På grund av skärpta miljökrav för tunga lastbilar och bussar ökar kraven på motorns komponenter. En av dessa komponenter är radialglidlager som används på många platser i motorn. Implementering av start-stoppsystem i en lastbilsmotor leder till att vevaxellagren slits ut i förtid. Ett radialglidlager är ett glidlager med ett kontant tillflöde av olja. När axeln börjar rotera skapas det en oljefilm mellan lagerytan och axeln. När rotationshastigheten är tillräckligt hög bär oljefilmen lasten och separerar axeln och lagerytan. Då har det bildats en fullfilm. Under start och stopp passerar lagret genom smörjregimerna gränsskiktssmörjning och blandsmörjning. Ökningen av start och stopp leder till en stor ökning av tiden som lagret upplever gränsskiktsoch blandsmörjning. Under dessa regimer är axeln och lagerytan i kontakt vilket leder till nötning. Detta examensarbete har jämfört två nya material från Höganäs AB med ett existerande lager som referens. De två nya materialen påsvetsades på lagerskålar och skickades till Scania för att slipas och testas. Tanken var att använda en start-stopprigg på KTH som simulerar startstoppcykler. Till att börja med kördes referenslagren i riggen, men när lagerskålarna med de nya materialen levererades visade det sig att de inte passade i testriggen. Detta innebar att en ny testmetod behövdes tas fram med kort varsel och valet föll på en reciprocerande tribometer på Scania. Tribometern var tvungen att modifieras för att proverna skulle passa. Fem test med varje material utfördes. Varje test tog 60 minuter, förutom ett långtidstest som kördes under 600 minuter. Resultaten visade att materialet kallat ”S”, vilket inkorporerade ett fast smörjmedel, hade en friktionskoefficient som liknade referensmaterialets, men producerade mindre nötning och klarade av en högre last. Examensarbetet har också kunnat påvisa att start-stoppriggen på KTH fungerar väl och kan leverera konsekventa resultat.

APA, Harvard, Vancouver, ISO, and other styles

7

Marcus, Kashif. "Micromechanisms of polymer sliding wear." Doctoral thesis, University of Cape Town, 1993. http://hdl.handle.net/11427/22408.

Full text

Abstract:

A study has been made concerning the tribological behaviour of ultrahigh molecular weight polyethylene (UHMWPE) during water-lubricated reciprocating sliding wear. The experimental work has been extended to study also the effect of molecular weight, fillers, lubrication, counterface roughness and sliding configuration on the polymer's transfer characteristics. The wear behaviour of polytetrafluoroethylene (PTFE) has been included for comparative studies. The worn material was studied using stylus profilometry, optical microscopy, scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS), Transmission electron microscopy (TEM), X-ray fluorescence (XRF), X-ray diffraction (XRD), differential scanning calorimetry (DSC), infrared spectroscopy (IR) and mass spectrometry. The effect of two fillers, namely glass beads and a titanium-based inorganic filler on the friction and wear behaviour of UHMWPE has been investigated as a function of counterface roughness (Rₐ). It was found that the filled material exhibited lower wear rates than the unfilled material on the rougher counterface. The filled material was also found to be more sensitive to a change in Rₐ and showed higher wear rates than the unfilled polymer on the smooth counterface. A uniform and coherent transfer film is found on the rougher counterface but the transfer film for the titanium-based filler was patchy on the smooth counterface. No coherent transfer film was found when sliding was conducted parallel to the grinding direction on the steel counterface, resulting in relatively high wear rates. Polymer transfer was patchy, the amount increasing as the sliding distance increased. The observed phenomena are explained in terms of mechanical interlocking and chemical bonding of the polymeric material with the metal counterface. An increase in molecular weight did not significantly improve the wear resistance of the UHMWPE. Small variations in counterface roughness values (Rₐ) were found to have a much greater effect on the wear rates than changes in molecular weight. The steady-state wear rate of the polymer was furthermore found to be more dependent on an adherent transfer film rather than a change in bulk morphology. Although PTFE exhibited low friction coefficients, the high wear rates obtained by this polymer is explained by the polymer's inability to form a transfer film under water lubrication, while any film that forms under dry sliding wear is easily peeled off the surface. Significant improvements in wear are found when fillers are added to the polymer. The wear rates for PTFE under dry sliding are similar to those obtained for UHMWPE under water lubrication. Transfet of UHMWPE material to the metal counterface during sliding wear involves interlamellar shear of the polymer and results in the development of a highly oriented transfer film. Significant differences have been found in the degree of crystallinity, crystallite size and orientation in the deformed surface layers of the polymer and debris compared with those of the bulk polymer. The worn surface of the polymer shows slightly increased crystallinity but the crystallinity of the debris is much higher than that of the bulk whilst the crystallite size is much reduced.

APA, Harvard, Vancouver, ISO, and other styles

8

Laine, Antoine. "Sliding Friction at the nanoscale." Thesis, Université de Paris (2019-....), 2020. http://www.theses.fr/2020UNIP7076.

Full text

Abstract:

Dans ce manuscrit, nous utilisons des méthodes dérivées de la microscopie à force atomique afin de mesurer, à l'échelle nanométrique, la réponse mécanique de différents systèmes. L'accent est porté sur la mise en lumière de la réponse frictionnelle et des mécanismes de dissipation à l'échelle du contact unique, où matières molle et condensée se confondent.Nous présentons premièrement le développement d'un nouvel outil expérimental permettant des mesures de nano-rhéologie et de nano-tribologie en environnement contrôlé. L'étude des propriétés mécaniques de liquides ioniques nano-confinés, avec cet instrument, nous révèle le caractère vitreux de ces électrolytes denses aux interfaces métalliques.Nous étudions par la suite les phénomènes de dissipation à l'échelle ultime, pour des jonctions métalliques de quelques atomes de diamètre. De l'absence de défauts découle une réponse plastique aux antipodes de notre expérience macroscopique.In fine, nous mettons l'accent sur l'étude de la dynamique d'une interface métallique de quelques atomes et développons de nouvelles stratégies expérimentales afin de résoudre la réponse frictionnelle du système soumis à une contrainte harmonique. Nos mesures, quantitativement reproduites numériquement, révèlent un mécanisme de friction quantifiée à l'échelle atomique
In this manuscript, we use methodes inherited from Atomic Force Microscopy in order to measure the nanoscale mechanical response of different systems. The focus is put on highlighting the frictional response and dissipation mechanisms taking place at the single asperity level, where soft and hard condensed matter meet.We first present the development of a new experimental tool allowing nanorheology and nanotribology measurement in controlled environment. The study of mechanical properties of nanoconfined RTILs with this apparatus revealed the glassy nature of these dense electrolytes at metallic interfaces.We then study the dissipation phenomena at the ultimate scale for metallic nanojunctions made of a few atoms. The absence of defects rationalizes their unexpected mechanical properties in striking difference with the macroscopic realm.In fine, we focus on the dynamics of a metallic interface made of a few atoms and develop new experimental strategies to probe the frictional response of the interface under harmonic applied stress. Our measurements are quantitatively reproduced numerically and reveal an atomic-scale quantized slip friction mechanism

APA, Harvard, Vancouver, ISO, and other styles

9

Haskara, Ibrahim. "Sliding mode controllers and observers." Connect to resource, 1996. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1157562285.

Full text

APA, Harvard, Vancouver, ISO, and other styles

10

Yan, Zhang. "Control and observation of electric machines by sliding modes." Columbus, Ohio : Ohio State University, 2002. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1039227737.

Full text

Abstract:

Thesis (Ph. D.)--Ohio State University, 2002.
Title from first page of PDF file. Document formatted into pages; contains xv, 156 p.; also includes graphics (some col.). Includes abstract and vita. Co-advisors: Vadim I. Utkin, Giorgio Rizzoni, Dept. of Electrical Engineering. Includes bibliographical references (p. 153-156).

APA, Harvard, Vancouver, ISO, and other styles

11

Jogineedi, Rohit. "Development of Comparative Wear Test of ASTM G75 Standard." OpenSIUC, 2017. https://opensiuc.lib.siu.edu/theses/2240.

Full text

Abstract:

AN ABSTRACT OF THE THESIS OF ROHIT JOGINEEDI, for the Master of Science degree in Mechanical Engineering and Processes, presented on 11/06/2017, at Southern Illinois University Carbondale. TITLE: DEVELOPMENT OF COMPARATIVE WEAR TEST FOR ASTM G75 STANDARD MAJOR PROFESSOR: Dr. Peter Filip Industries related to tribology field invest huge amounts in testing products they handle. Most of their budget goes into running tests on corresponding friction, wear or lubrication testing instruments. These tests are observed to be consuming more time with an increase in operational costs. This gained importance among industries for developing economical testing methods designed to run on one or more machines to study tribological conditions. As friction and wear are system properties, change in system variables like distance, velocity, time and area can have notable impact on those properties. This paper discusses about various approaches to develop comparative test on sub scale testers for ASTM G75 standard. Scaling Laws of Physics and comparison of wear mode are two approaches used in this paper to justify the comparative test developed for ASTM G75 on a bench top tester developed by Bruker. Results from the ASTM G75 standard and the UMT are compared and concluded that scaling strategies cannot be used to replicate the standard test methods on sub scale testers but comparison of wear mode could help. This proposed comparative test for ASTM G75 is observed to have lower operational costs thereby decreasing the amount of investment on testing friction or wear products in an industry.

APA, Harvard, Vancouver, ISO, and other styles

12

Nilsson, Rickard. "On wear in rolling/sliding contacts." Doctoral thesis, KTH, Machine Design (Div.), 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-122.

Full text

Abstract:

The aim of this thesis is to increase the understanding of wear in rolling/sliding contacts such as the wheel-rail contact for railroads and the roller-washer contact for roller bearings.

The Stockholm commuter train network has been the subject of papers A and B in this thesis in which the wear and surface cracks on rails has been observed for a period of three years. By comparing the wear depth with the crack length, equilibrium between these two damage mechanisms was found for a lubricated rail. By using a lubricant with friction modifiers the stresses was low enough to prevent crack propagation; at the same time, the rail was hard enough to reduce the wear rate. This is probably the most favourable state in terms of rail maintenance cost.

Roller bearings subjected to lubricant borne particles have been the subject of papers C, D and E in this thesis. Particles in the lubricating oil can have a significant impact on the wear in lubricated contacts. Even at low concentration levels can self-generated particles cause significant wear. The here presented results shows that filtration during run-in can significantly reduce both the mass loss and the number of self generated particles. A series of experiments has been carried out to study the wear of roller bearings by ingested lubricant borne hard particles. The form of the worn profile and the length of wear scratches correspond closely to the sliding within the contact. A count of the number of wear scratches on the rolling element surface indicates that the contact concentrates particles. A novel wear model based on the observation of a single point on the contacting surface when a concentration of particles passes through it has been developed and the necessary data for the model has been determined from the experiments. Comparison of the simulation results with the experimental results shows good qualitative agreement for the form change of the washer surfaces.

APA, Harvard, Vancouver, ISO, and other styles

13

Sigfridsson, Jenny, and Josefin Frisk. "Robotstyrning med metoden Sliding Mode Control." Thesis, Linköping University, Department of Electrical Engineering, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-2813.

Full text

Abstract:

The task in this thesis is the steering of one of Saab Bofors Dynamics robots using Sliding Mode Control, a method they never used before. The robot constitutes a system which in addition to perturbations and uncertainties due to modeling imprecision, hold the difficulty of being highly time variant. In order to be able to keep required performance with uncertainties and modeling imprecision present, the use of robust control methods like Sliding Mode Control is necessary. SMC is based on the states of the system being forced to stay on or in the direct vicinity of a hyper plane in the state space which is chosen in a way that gives the system dynamics desired properties. Other advantages with sliding mode are reduced order dynamics on the switching surface and total insensitivity to some uncertainties and perturbations. The existing metod for controlling the robot is Linear Quadratic Control. To evaluate the SMC-methodology and compare it with the existing solution simulations using SMC and LQ-control are made with uncertainties and modeling imprecision. Our tests show that a control law based on SMC is robust and seems to be a very good alternative to the existing solution.

APA, Harvard, Vancouver, ISO, and other styles

14

Feng, Ping. "Probabilistic treatment of the sliding wedge." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq23300.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

15

Behdinan, Kamran. "Dynamics of geometrically nonlinear sliding beams." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ32734.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

16

Shepit, Blaine M. "Mixed objective LQ/Sliding Mode Control." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0017/MQ49684.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

17

Toolan, Timothy M. "Advances in sliding window subspace tracking /." View online ; access limited to URI, 2005. http://0-wwwlib.umi.com.helin.uri.edu/dissertations/dlnow/3206257.

Full text

APA, Harvard, Vancouver, ISO, and other styles

18

Ettinger, Ran. "Refactoring via program slicing and sliding." Thesis, University of Oxford, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.442400.

Full text

APA, Harvard, Vancouver, ISO, and other styles

19

Klinker, Henrike. "ATP-dependent nucleosome sliding by ISWI." Diss., Ludwig-Maximilians-Universität München, 2014. http://nbn-resolving.de/urn:nbn:de:bvb:19-180992.

Full text

APA, Harvard, Vancouver, ISO, and other styles

20

Barceinas-Sanchez, Jose Dolores Oscar. "Sliding wear mechanisms of oxide ceramics." Thesis, University of Sheffield, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267177.

Full text

APA, Harvard, Vancouver, ISO, and other styles

21

Misawa, Eduardo Akira. "Nonlinear state estimation using sliding observers." Thesis, Massachusetts Institute of Technology, 1988. http://hdl.handle.net/1721.1/14549.

Full text

APA, Harvard, Vancouver, ISO, and other styles

22

Chen, De-Shiou. "Sliding mode observers for automotive alternator." The Ohio State University, 1998. http://rave.ohiolink.edu/etdc/view?acc_num=osu1384448652.

Full text

APA, Harvard, Vancouver, ISO, and other styles

23

Ku, Ingrid Siu Ying. "Lubrication of high sliding silicon micromachines." Thesis, Imperial College London, 2010. http://hdl.handle.net/10044/1/6876.

Full text

Abstract:

A major challenge in silicon devices based on micro-electro-mechanical systems (MEMS) is the provision of effective lubrication for sliding parts. This greatly limits the development and exploitation of MEMS devices, with current designs avoiding sliding contacts where possible. This thesis describes research aimed at lubricating high sliding MEMS devices. A micro-scaled tribometer has been constructed to obtain measurements of friction between two sliding silicon surfaces. This work focuses on lubricating MEMS with liquids, a self-replenishing lubrication method which had been dismissed previously as they were assumed to carry too much viscous drag. The major finding is that ferromagnetic fluids make excellent lubricants for sliding MEMS surfaces. These fluids provide low friction at high speeds, and reduce the boundary friction at low speeds when the hydrodynamic film is absent. The properties of such fluids allow the liquid to be contained in the presence of a magnetic field, meaning that only a small, localised amount is required. Low viscosity liquids were also shown to provide acceptably low friction at high speeds. These results agreed reasonably well with theory. Friction modifier (FM) additives were added to low viscosity liquids in order to reduce boundary friction by forming boundary films, when no hydrodynamic film is generated at low speeds. Drag has also been shown to be insignificant. A study of the wear of silicon surfaces under prolonged sliding was conducted. Previous studies have focussed on dry coatings and apparently untreated surfaces. In this thesis, the effects of different surface preparations, the use of low viscosity liquids and vapour phase lubrication on wear have been studied. This thesis concludes that it is feasible to use liquids to lubricate sliding MEMS. High sliding MEMS is possible and practicable in future if self-replenishing methods, such as those studied in this work, are employed in real devices.

APA, Harvard, Vancouver, ISO, and other styles

24

Venkataramanan, Ramanarayanan Middlebrook R. D. Ćuk Slobodan. "Sliding mode control of power converters /." Diss., Pasadena, Calif. : California Institute of Technology, 1986. http://resolver.caltech.edu/CaltechETD:etd-09222006-170253.

Full text

APA, Harvard, Vancouver, ISO, and other styles

25

Lee, Hoon. "Chattering suppression in sliding mode control system." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1192823756.

Full text

APA, Harvard, Vancouver, ISO, and other styles

26

Duffy, Caroline M. "Structural Mechanisms of the Sliding Clamp and Sliding Clamp Loader: Insights into Disease and Function: A Dissertation." eScholarship@UMMS, 2016. https://escholarship.umassmed.edu/gsbs_diss/844.

Full text

Abstract:

Chromosomal replication is an essential process in all life. This dissertation highlights regulatory roles for two critical protein complexes at the heart of the replication fork: 1) the sliding clamp, the major polymerase processivity factor, and 2) the sliding clamp loader, a spiral-shaped AAA+ ATPase, which loads the clamp onto DNA. The clamp is a promiscuous binding protein that interacts with at least 100 binding partners to orchestrate many processes on DNA, but spatiotemporal regulation of these binding interactions is unknown. Remarkably, a recent disease-causing mutant of the sliding clamp showed specific defects in DNA repair pathways. We aimed to use this mutant as a tool to understand the binding specificity of clamp interactions, and investigate the disease further. We solved three structures of the mutant, and biochemically showed perturbation of partnerbinding for some, but not all, ligands. Using a fission yeast model, we showed that mutant cells are sensitive to select DNA damaging agents. These data revealed significant flexibility within the binding site, which likely regulates partner binding. Before the clamp can act on DNA, the sliding clamp loader places the clamp onto DNA at primer/template (p/t) junctions. The clamp loader reaction couples p/t binding and subsequent ATP hydrolysis to clamp closure. Here we show that composition (RNA vs. DNA) of the primer strand affects clamp loader binding, and that the order of ATP hydrolysis around the spiral is likely sequential. These studies highlight additional details into the clamp loader mechanism, which further elucidate general mechanisms of AAA+ machinery.

APA, Harvard, Vancouver, ISO, and other styles

27

Duffy, Caroline M. "Structural Mechanisms of the Sliding Clamp and Sliding Clamp Loader: Insights into Disease and Function: A Dissertation." eScholarship@UMMS, 2007. http://escholarship.umassmed.edu/gsbs_diss/844.

Full text

Abstract:

Chromosomal replication is an essential process in all life. This dissertation highlights regulatory roles for two critical protein complexes at the heart of the replication fork: 1) the sliding clamp, the major polymerase processivity factor, and 2) the sliding clamp loader, a spiral-shaped AAA+ ATPase, which loads the clamp onto DNA. The clamp is a promiscuous binding protein that interacts with at least 100 binding partners to orchestrate many processes on DNA, but spatiotemporal regulation of these binding interactions is unknown. Remarkably, a recent disease-causing mutant of the sliding clamp showed specific defects in DNA repair pathways. We aimed to use this mutant as a tool to understand the binding specificity of clamp interactions, and investigate the disease further. We solved three structures of the mutant, and biochemically showed perturbation of partnerbinding for some, but not all, ligands. Using a fission yeast model, we showed that mutant cells are sensitive to select DNA damaging agents. These data revealed significant flexibility within the binding site, which likely regulates partner binding. Before the clamp can act on DNA, the sliding clamp loader places the clamp onto DNA at primer/template (p/t) junctions. The clamp loader reaction couples p/t binding and subsequent ATP hydrolysis to clamp closure. Here we show that composition (RNA vs. DNA) of the primer strand affects clamp loader binding, and that the order of ATP hydrolysis around the spiral is likely sequential. These studies highlight additional details into the clamp loader mechanism, which further elucidate general mechanisms of AAA+ machinery.

APA, Harvard, Vancouver, ISO, and other styles

28

Reinsnes, Ståle E. "Stabilization of slugging by sliding mode control." Thesis, Norwegian University of Science and Technology, Department of Engineering Cybernetics, 2009. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-9958.

Full text

Abstract:

The objective of this master thesis is to design, implement, and evaluate sliding mode control (SMC) applied to stabilize slugging using only the downhole pressure as measurement. The pros and cons of the resulting output-feedback sliding mode controller are to be evaluated against the conventional PI controller. The thesis is based on, and a continuation of the work and conclusions of my project thesis, where the conclusion was that the SMC might have a significant potential for increased oil production and recovery. The clear limitation was however the uncertainty regarding the validity of the van Der Pol model used, and the fact that the SMC was provided the real time-derivative states. Therefore the original main tasks of this thesis was to implement a high fidelity simulation model of severe riser slugging, and to design (and test) differentiators with the purpose of evaluating the output-feedback performance of the SMC. As it turn out that I was not able to achieve the task of stabilizing the pressure with SMC on the chosen OLGA model, the focus of this thesis has in agreement with my supervisors been changed quite a lot from the task requested in the project description. Possible reasons for the lack of results, and the chosen focus of the thesis is presented in the introduction chapter. The thereby chosen focus became the task of designing testing differentiators for the SMC, but with testing on the van Der Pol model. Before presenting and arguing for this change of focus in the section about task and limitation, the introduction chapter starts by giving a brief overview of the environment or setting the controlling challenge is a part of, and follows up by presenting the work and conclusion of that project thesis. In the end of the chapter, the structure of the thesis is shortly listed. The introduction is followed up by giving a further insight to the slug problematic. An overview of the historical development, and a description of some research within the field are provided. The last part of the chapter gives a quite thorough description on the riser slugging phenomenon. Thereby the sliding mode controller (SMC) is presented in chapter 3. The challenge concerning chattering is also discussed, and the approach of using boundary layer to suppress the chattering is introduced. In chapter 4, the empirical van der Pol based model is derived, and the model is augmented to use the valve rate as control input. Chapter 6 gives a discussion on why the SMC should be performed on the choke rate and not directly on the choke opening. This section also designs the SMC that will be used for testing, and the needed time-derivatives for testing the SMC are derived. The chosen main focus of this thesis is to evaluate if there is possible to design observers (differentiators) that meets the requirements for the designed SMC to stabilize slugging. The tests are performed on the van Der Pol model. This task is introduced through chapter 7, that present general observer theory, theory about using observers combined with SMC, and finally the two observers chosen for further testing; the high gain observer (HGO) and the robust high-order sliding mode differentiator (RHOSMD). The first stage in evaluating the HGO and RHOSMD is open loop testing, and is described in chapter 8. The observers perform well for the ideal case of no disturbance, but in the presence of measurement noise the conclusion is that estimations of the higher order time-derivatives do likely not meet the very demanding requirements of the SMC. The biggest problem is probably the time-delay of the estimation, but the correctness of the amplitude might also be a problem. In chapter 9 the observers was tested further in a SMC controlled closed loop system to get a more precise indication on how well the observers are fitted for their intended task of providing the SMC with the required estimations. As for the open loop tests, the 'isolated' estimation performance of the required states was considered, but the main focus was the performance of the output-feedback SMC compared to the performance of manual choking, the PI controller, and the performance of the state-feedback SMC. This chapter confirmed the assumption from the open loop testing that in presence of measurement noise, the observers is not able to meet the demanding requirements of the designed SMC. For the theoretical ideal case of no disturbance the results is very good, especially for the HGO. In the case of measurement noise, the RHOSMD perform slightly better. In both chapter 8 and 9, tuning is considered and discussed. However, since the conclusions of the observer testing is negative, the SMC is not tested further. The results will be negative for output-feedback testing, and a quite extensive state-feedback testing of the SMC is performed in the project thesis. The main results and conclusions throughout the thesis, are presented in chapter 10. The chapter also contain a short discussion where it is concluded that the alternative designs, SMC with direct choke rate control and SMC of the choke acceleration, will not be a solution on the state-feedback SMC problems described in this thesis. There is also a short discussion regarding CPU and system requirements for the observers and the controller. At the very end, further work is discussed.

APA, Harvard, Vancouver, ISO, and other styles

29

André, Benny. "Nanocomposites for Use in Sliding Electrical Contacts." Doctoral thesis, Uppsala universitet, Tillämpad materialvetenskap, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-160809.

Full text

Abstract:

In this thesis nanocomposite materials for use in high performance electrical contacts are tested. Self mating silver as coatings on cupper substrates are the most used material combination in power connectors today. In this work two new concepts were tested. The first one was to change one of the mating surfaces to a hard thin coating and keep the other surface made of silver. Tested coatings were nanocomposites with hard carbides in a matrix of amorphous carbon. TiC/a-C and Ti-Ni-C/a-C were tested both electrically and tribologically. The total amount of carbon and the amount of carbon matrix was important, both for the electrical and the tribological properties. The Ti-Ni-C coating also showed that substituting Ti in TiC with the weak carbide former Ni changed the stability of the carbides. The substitution resulted in more a-C matrix and less C in the carbides. Thin coatings of nc-TiC/a-C and Ti-Ni-C/a-C showed high potential as material candidates for use in electrical contacts. The other tested concept was to modify the used silver instead of replacing it. This was done by embedding nanoparticles of solid lubricant IF-WS2 in the silver. The results from reciprocating sliding displayed low friction and high wear resistance. The modified silver surfaces lasted for 8000 strokes with a friction of about 0.3 while at the same time allowing for a low contact resistance. The results for surfaces of pure silver coating displayed a friction of 0.8-1.2 and that the silver was worn through already after 300 strokes. A new method to investigate inherent hardness and residual stress of thin coatings, on complex geometries or in small areas, was also developed. An ion beam was used to create stress free coating as free standing micro pillars. Hardness measured on the pillars and on as-deposited coating were then used to calculate the residual stress in the coatings.

APA, Harvard, Vancouver, ISO, and other styles

30

Golab, Lukasz. "Sliding Window Query Processing over Data Streams." Thesis, University of Waterloo, 2006. http://hdl.handle.net/10012/2930.

Full text

Abstract:

Database management systems (DBMSs) have been used successfully in traditional business applications that require persistent data storage and an efficient querying mechanism. Typically, it is assumed that the data are static, unless explicitly modified or deleted by a user or application. Database queries are executed when issued and their answers reflect the current state of the data. However, emerging applications, such as sensor networks, real-time Internet traffic analysis, and on-line financial trading, require support for processing of unbounded data streams. The fundamental assumption of a data stream management system (DSMS) is that new data are generated continually, making it infeasible to store a stream in its entirety. At best, a sliding window of recently arrived data may be maintained, meaning that old data must be removed as time goes on. Furthermore, as the contents of the sliding windows evolve over time, it makes sense for users to ask a query once and receive updated answers over time.

This dissertation begins with the observation that the two fundamental requirements of a DSMS are dealing with transient (time-evolving) rather than static data and answering persistent rather than transient queries. One implication of the first requirement is that data maintenance costs have a significant effect on the performance of a DSMS. Additionally, traditional query processing algorithms must be re-engineered for the sliding window model because queries may need to re-process expired data and "undo" previously generated results. The second requirement suggests that a DSMS may execute a large number of persistent queries at the same time, therefore there exist opportunities for resource sharing among similar queries.

The purpose of this dissertation is to develop solutions for efficient query processing over sliding windows by focusing on these two fundamental properties. In terms of the transient nature of streaming data, this dissertation is based upon the following insight. Although the data keep changing over time as the windows slide forward, the changes are not random; on the contrary, the inputs and outputs of a DSMS exhibit patterns in the way the data are inserted and deleted. It will be shown that the knowledge of these patterns leads to an understanding of the semantics of persistent queries, lower window maintenance costs, as well as novel query processing, query optimization, and concurrency control strategies. In the context of the persistent nature of DSMS queries, the insight behind the proposed solution is that various queries may need to be refreshed at different times, therefore synchronizing the refresh schedules of similar queries creates more opportunities for resource sharing.

APA, Harvard, Vancouver, ISO, and other styles

31

Deguchi, Kengo. "Finite amplitude solutions in sliding Couette flow." 京都大学 (Kyoto University), 2013. http://hdl.handle.net/2433/174925.

Full text

APA, Harvard, Vancouver, ISO, and other styles

32

Bartsch, Ralf, Jens Sumpf, and André Bergmann. "Friction Temperature of POM–PE Sliding Contacts." Universitätsbibliothek Chemnitz, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-231659.

Full text

Abstract:

The design of traction mechanisms of continuous conveying units (e. g. plastic chains) is so far based on a purely mechanical dimensioning. However, mechanical limits are only applicable in a limited way to avoid system failure. With higher speeds or pressure, especially the thermal stress increases, which results in system failure based on softening or melting of the materials at a certain temperature. By means of systematic studies, correlations between friction temperature, coefficient of friction, wear and process parameters are examined. On this basis, a model for calculating the friction temperature is developed
Die Konstruktion von Zugmitteln für kontinuierliche Fördereinheiten (z. B. Kunststoffketten) beruht bisher auf einer rein mechanischen Dimensionierung. Allerdings sind mechanische Grenzwerte zur Vermeidung von Systemausfall nur bedingt anwendbar. Bei größeren Geschwindigkeiten oder Druck erhöht sich insbesondere die thermische Beanspruchung, was bei einer bestimmten Temperatur zum Systemausfall durch Erweichung oder Schmelzen der Werkstoffe führt. In systematischen Untersuchungen wurden die Korrelationen zwischen Reibungstemperatur, Reibungskoeffizient, Verschleiß und den Prozessparametern untersucht. Auf dieser Basis wurde ein Modell zur Berechnung der Reibungstemperatur entwickelt

APA, Harvard, Vancouver, ISO, and other styles

33

McCarthy, Donald. "Lubrication of sliding bearings for hydropower applications." Licentiate thesis, Luleå, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-26457.

Full text

Abstract:

The term "sliding bearing" refers to types of bearing where two conformal surfaces (usually the stationary bearing and a moving shaft) slide relative to one another with load distributed directly across the interface. A suitable lubricant may be employed to reduce the friction between these two surfaces. In "fluid film" bearings, this lubricant builds up a layer of sufficient thickness such that the two surfaces are completely separated. Examples include journal and thrust bearings and shaft bushings. Unlike ball or roller bearings which have a limited lifespan, sliding bearings have, at least in theory, an indefinite operational lifespan. As long as an oil film of sufficient thickness is maintained and contamination is avoided, the bearing may continue to do its job indefinitely. However, more and more onerous demands are being placed on such bearings and their associated methods of lubrication in order to maximise performance in terms of efficiency and load carrying capacity, for example in hydroelectricity generators and turbines. Given the sensitivity of operating any form of mechanical equipment in the vicinity of watercourses, often the source of drinking water for major population centres, the hydropower industry has a duty of responsibility in ensuring that as much as possible is done to minimise the risk of contamination of the water or damage to flora and fauna. Two aims - increased output, decreased environmental impact - are currently the major driving forces behind Research and Development in the hydroelectric power generation industry. Looking at these from a tribological (friction and lubrication) point of view, three areas of particular interest can be identified. These are: 1) How can the load carrying capacity of thrust bearings be increased whilst at the same time improving performance within existing dimensional constraints? 2) What is the influence on bearings of transient events (rapid changes in speed or loading) and what impact do they have on the machinery components? 3) How does the use of Environmentally Adapted Lubricants (as opposed to mineral oils) influence friction and wear etc, specifically with reference to shaft bushings, and what is the impact of fluid ageing (oxidation) on their performance? Each of these three points has been studied in the course of the work carried out for this thesis.
Godkänd; 2005; 20061214 (haneit)

APA, Harvard, Vancouver, ISO, and other styles

34

Bag, Sujit Kumar. "Robust sliding mode control using output information." Thesis, University of Leicester, 1997. http://hdl.handle.net/2381/30166.

Full text

Abstract:

The thesis considers the development of robust output feedback sliding mode controllers for linear time invariant uncertain systems where output information alone is available to the controller. Two approaches to controller design are discussed. The first uses only the plant dynamics and is called static output feedback sliding mode control. It is shown that a quadratically stable sliding motion may be attained for a bounded uncertain system if and only if the system is minimum phase and a particular subsystem triple satisfies the output feedback design criteria. Sliding mode controllers are sensitive to unmatched uncertainty. Hence a robust design is considered which minimises the effect of uncertainty. The second approach is developed for systems which have design difficulties when only the plant dynamics are considered. Extra dynamics are added and the method is called dynamic output feedback sliding mode control. Closed-loop analysis is carried out and stability of the augmented system is observed. Both controllers guarantee a stable sliding motion despite the presence of bounded uncertainty. Finally, two practical uncertain multivariate industrial examples demonstrate the theoretical developments. The first application is a helicopter model. The open loop dynamics have unstable poles with two stable invariant zeros, variations in model parameters and exhibit high levels of cross coupling. A model following sliding mode controller is used to force the plant outputs to track the outputs of an ideal model. Nonlinear simulation results show the practicality of the method. The second application considers the dynamic output feedback sliding mode control of an aircraft model. The system possesses unstable invariant zeros and requires a dynamic output feedback technique. Simulation results are obtained at different operating points to show the effect of unstable invariant zeros. The examples illustrate the benefits of these robust output feedback based sliding mode control developments.

APA, Harvard, Vancouver, ISO, and other styles

35

Bhatti, Aamer Iqbal. "Advanced sliding mode controllers for industrial applications." Thesis, University of Leicester, 1998. http://hdl.handle.net/2381/30243.

Full text

Abstract:

This thesis deals with the industrial application of sliding mode controllers. Sliding mode controllers based on both linear models and nonlinear-models are considered. Special attention is paid to the nonlinear modelling of the systems for sliding mode controller design. The possibility of using neural networks for model generation is explored. Novel schemes for uncertainty bounds estimation are introduced and subsequently used for robust sliding mode controller design. Later, a novel approach for sliding mode based parameter estimation for a nonlinear model with known structure but unknown parameters is introduced. This parameter estimation scheme is integrated with sliding mode controller design to provide an overall controller design framework. The stability of these schemes is proven through quadratic stability concepts. The sliding mode controller design frameworks mentioned above are verified and tested on challenging industrial examples. The temperature control of a high temperature multiburner industrial furnace is a highly coupled and extremely nonlinear problem. A multiburner furnace nonlinear simulation facility is established and used for linear identification and subsequently linear model based sliding mode controller testing. For comparison purposes a two degree of freedom H controller is also designed and tested. Then a nonlinear model based controller is tested on a single burner furnace simulation. Idle speed control of an automobile engine is an extremely difficult control problem characterised with severe nonlinearities, gross disturbances and huge time delays. A sliding mode controller is designed for this problem and successfully implemented on a test rig. Later on, a nonlinear model based sliding mode controller is designed for the same problem and successfully tested.

APA, Harvard, Vancouver, ISO, and other styles

36

Wang, Bin, and s3115026@student rmit edu au. "On Discretization of Sliding Mode Control Systems." RMIT University. Electrical and Computer Engineering, 2008. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080822.145013.

Full text

Abstract:

Sliding mode control (SMC) has been successfully applied to many practical control problems due to its attractive features such as invariance to matched uncertainties. The characteristic feature of a continuous-time SMC system is that sliding mode occurs on a prescribed manifold, where switching control is employed to maintain the state on the surface. When a sliding mode is realized, the system exhibits some superior robustness properties with respect to external matched uncertainties. However, the realization of the ideal sliding mode requires switching with an infinite frequency. Control algorithms are now commonly implemented in digital electronics due to the increasingly affordable microprocessor hardware although the essential conceptual framework of the feedback design still remains to be in the continuous-time domain. Discrete sliding mode control has been extensively studied to address some basic questions associated with the sliding mode control of discrete-time systems with relatively low switching frequencies. However, the complex dynamical behaviours due to discretization in continuous-time SMC systems have not yet been fully explored. In this thesis, the discretization behaviours of SMC systems are investigated. In particular, one of the most frequently used discretization schemes for digital controller implementation, the zero-order-holder discretization, is studied. First, single-input SMC systems are discretized, stability and boundary conditions of the digitized SMC systems are derived. Furthermore, some inherent dynamical properties such as periodic phenomenon, of the discretized SMC systems are studied. We also explored the discretization behaviours of the disturbed SMC systems. Their steady-state behaviours are discussed using a symbolic dynamics approach under the constant and periodic matched uncertainties. Next, discretized high-order SMC systems and sliding mode based observers are explored using the same analysis method. At last, the thesis investigates discretization effects on the SMC systems with multiple inputs. Some conditions are first derived for ensuring the

APA, Harvard, Vancouver, ISO, and other styles

37

Edmonds, Shane. "Discrete sliding mode control of magnetic bearings." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0021/MQ49674.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

38

Sakurai, Atsuhiko. "Sliding mode control of switched reluctance motors." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/MQ63026.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

39

Sloetjes, Jan Willem. "Micro-elastohydrodynamic lubrication in concentrated sliding contacts." Enschede : University of Twente [Host], 2006. http://doc.utwente.nl/57640.

Full text

APA, Harvard, Vancouver, ISO, and other styles

40

McCarthy, Donald M. C. "Lubrication of sliding bearings for hydropower applications /." Luleå, 2005. http://epubl.luth.se/1402-1757/2005/75.

Full text

APA, Harvard, Vancouver, ISO, and other styles

41

Gorbatikh, Larissa G. "Analytical modeling of non-uniform frictional sliding /." Thesis, Connect to Dissertations & Theses @ Tufts University, 2001.

Find full text

Abstract:

Thesis (Ph.D.)--Tufts University, 2001.
Submitted to the Dept. of Mechanical Engineering. Adviser: Mark Kachanov. Includes bibliographical references (leaves 126-128). Access restricted to members of the Tufts University community. Also available via the World Wide Web;

APA, Harvard, Vancouver, ISO, and other styles

42

Godwin, Bryan. "Discrete sliding mode control of drug infusions." Thesis, Georgia Institute of Technology, 1991. http://hdl.handle.net/1853/16806.

Full text

APA, Harvard, Vancouver, ISO, and other styles

43

Kong, Hosung. "Friction and wear at sliding ceramic surfaces." Thesis, University of Cambridge, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386230.

Full text

APA, Harvard, Vancouver, ISO, and other styles

44

Yim, Shon W. 1973. "Dynamics of sliding mechanisms in nanoscale friction." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/8142.

Full text

Abstract:

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2002.
Includes bibliographical references.
Nanotribology is the study of friction and wear at the nanoscale, with relevance to such applications as micromechanical systems (MEMS) and thin, hard coatings. For these systems, classical laws of friction are inappropriate due to the small dimensions of the sliding elements and the lack of excessive plastic deformation. This thesis presents a theoretical investigation of friction at the sliding interface by Molecular Dynamics (MD) simulations of ideal Lennard-Jones solids. The effect of the interfacial structure on the frictional behavior is investigated by simulating a variety of interface configurations: commensurate, noncommensurate (or grain boundary), and amorphous. The effect of adhesion on the frictional behavior is also explored through a parametric study. For the commensurate interface, the degree of adhesion determines whether sliding occurs in the frictional or "frictionless" regime; the former is distinguishable by the presence of jump phenomena, the principal mechanism of friction in the MD model. The Sigma-5 [100](310) symmetric tilt grain boundary exhibits three distinct sliding regimes which are, in the order of increasing adhesion, frictionless sliding, frictional sliding, and sliding coupled with grain boundary migration. Twist grain boundaries of the (111) plane exhibit frictionless sliding for all degrees of adhesion. Among the structures simulated, the grain boundary systems have the lowest friction due to the intrinsic misorientation at the sliding interface. In the amorphous system, sliding occurs by a series of random local slips due to the individual atomic motion associated with the disordered structure.
(cont.) Increasing the adhesion leads to the initiation of a shear-induced crystallization process followed by an extremely rapid growth of the crystalline cluster. Friction in the amorphous system increases with adhesion only up to a certain limit due to the onset of bulk deformation. Similar trends have been observed in AFM measurements of the friction of thin, hard coatings.
by Shon W. Yim.
Ph.D.

APA, Harvard, Vancouver, ISO, and other styles

45

Herselman, Emile Johan. "An investigation of sliding wear of Ti6Al4V." Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/20327.

Full text

Abstract:

Thesis (MScEng)--Stellenbosch University, 2012.
ENGLISH ABSTRACT: Sliding wear is a complicated form of wear involving different factors. The factors affecting the process are the mechanical properties of the materials, sliding distance, sliding speed, and normal force applied to the contact. An experimental study was conducted to assess the performance of Ti6Al4V in self-mated and various counterface material contact couples subjected to linear reciprocating dry sliding motion. The normal force was varied for all the experiments to understand the effect it had on specific couples. Sliding wear experiments were also conducted on cemented carbides coupled with Ti6Al4V. In certain applications carbide coatings are used and could possibly come into contact with Ti6Al4V. Cemented carbides used in the study were manufactured through spark plasma sintering and liquid phase sintering. An in depth study was conducted to assess the spark plasma sintered materials and compare these to those manufactured through liquid phase sintering. The experimental study revealed that an increase in normal force, in sliding experiments, led to an increase in friction and wear volume loss of the Ti6Al4V pin. In addition the experiments found that Ti6Al4V was prone to adhesion and surface oxidation.
AFRIKAANSE OPSOMMING: Glyslytasie is 'n gekompliseerde slytasievorm wat verskillende faktore behels.Die faktore wat die proses beïnvloed is die meganiese eienskappe van die materiale,gly-afstand,glyspoed en normale druk(krag) wat op die kontakoppervlakte toegepas word. 'n Eksperimentele studie om die werksverrigting van Ti6Al4V in verenigde en verskeie teenwerkende materiaal kontakpare wat onderwerp is aan lineêre omgekeerde droë gly-aksie te assesseer is uitgevoer.Die normale krag vir al die eksperimente om die effek wat dit op die spesifieke pare gehad het te verstaan is gevarieer. Glyslytasie-eksperimente is ook op gesementeerde karbiedes wat met Ti6Al4V gekoppel is,uitgevoer. In sekere toepassings is karbiedlae gebruik en kon moontlik met Ti6Al4V in kontak gekom het. Gesementeerde karbiedes wat in die studie gebruik is, is deur vonkplasmasinter en vloeibare fase-sinter vervaardig. 'n Indieptestudie is ook uitgevoer om die vonkplasmasintermateriale en dié materiale wat deur vloeibare fasesinter vervaardig is te vergelyk. Die eksperimentele studie het getoon dat 'n toename in normale krag in glyeksperimente gelei het tot 'n toename in wrywing en slytasievolumeverlies van die Ti6Al4V pin. Bykomend tot die eksperimente is gevind dat Ti6Al4V geneig was tot adhesie en oppervlakteoksidasie.

APA, Harvard, Vancouver, ISO, and other styles

46

Yang, Lee Shi, and 李旭陽. "Sliding Mode Controller Design With Contrrolled Sliding Dynamics." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/17415208925829734529.

Full text

APA, Harvard, Vancouver, ISO, and other styles

47

Zhu, Zhi-Hong, and 朱智鴻. "Discrete-Time Sliding Mode Controller Design with Weak Sliding Condition." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/45156255420128283193.

Full text

Abstract:

碩士
國立成功大學
航空太空工程學系
86
In control system design, it is often required that the system behavior is insensitive to the parameter variations and external disturbances. To this problem, variable structure system control is developed and widely applied. Traditional sliding mode control possesses the characteristics that the controlled system is invariant to model uncertainty and external disturbance when the state enters the sliding surface, and the system response follows the dynamics of the sliding surface. However, when the sliding mode controller is realized by digital computer, it is impossible for the control input to switch in a very high frequency and the sliding mode motion will not occurred. The respective robustness vanishes, and the system may become unstable when the sampling period is too long. In this dissertation, a discrete-time sliding control law, which is applied immediately after sensing the system states, is developed to guarantee the existence of the weak-pseudo-sliding mode along the prescribed hyperplane. Due to the effect of the computational delay, an one-sample-delay discrete-time sliding mode control law is developed. Concept of the "modified weak- pseudo-sliding mode" is proposed. The upper bounds of the sampling periods are also determined to ensure the stability.

APA, Harvard, Vancouver, ISO, and other styles

48

Su, Jui-Yiao, and 蘇瑞堯. "Fuzzy Sliding Mode Controller Design with Fuzzy Sliding Mode Observer." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/53082941533057208869.

Full text

Abstract:

碩士
大同工學院
電機工程研究所
87
This thesis addresses the design of the decoupled fuzzy sliding mode controller and the fuzzy sliding mode observer on the basis of the Takagi-Sugeno’s (T-S) fuzzy model. A large class of fourth-order system such as a cart-pole system could be controlled in both the pole-hyperplane and the cart-hyperplane simultaneously without increasing the number of fuzzy rules. The main ideas of this thesis are as follows: 1. The fuzzification of the sliding surface improves the high frequency switching (chattering phenomena) near the sliding surface and has better performance. 2. The concept of decoupling the system makes the simultaneously control of two distinguish targets possible. 3. With the same fuzzy sliding mode theory, a reduced order estimator can well estimate the true states of the complex system. The numerical simulation of the car-pole system confirms the validity of the proposed approaches.

APA, Harvard, Vancouver, ISO, and other styles

49

Chen, Chin Chi, and 陳清祺. "Design of Sliding-and-Classical Controllers Using Sliding Mode Technique." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/46781566567644811987.

Full text

Abstract:

碩士
國立中山大學
電機工程研究所
82
This thesis is concerned with the development and improvement of an existing method for designing a hybrid sliding mode and classical controller. The idea is based on defining the sliding variable in such a way that once the system gets into sliding, not only the classical controller transfer function can be realized, but also the noise enhancement phenomena can be eliminated when realizing an improper controller. The advantage of this sliding-and-classical controller are that it can retain all the merits of both types of controllers on one hand and eliminates their respective limitations on the other. For the improvement of the existing design method, the number of diffe- rentiator of the sliding surface variable is reduced, and the theoretical part of processing noise problem is also provided. The proposed method is robust and can be applied to non-minimum phase systems as well as systems with structural uncertainties. Finally, the sliding-and-classical controller is applied to a real electrohydraulic system.

APA, Harvard, Vancouver, ISO, and other styles

50

Ge, Chang. "Bitemporal Sliding Windows." Thesis, 2014. http://hdl.handle.net/10012/8385.

Full text

Abstract:

The bitemporal data model associates two time intervals with each record - system time and application time - denoting the validity of the record from the perspective of the database and of the real world, respectively. One issue that has not yet been addressed is how to efficiently answer sliding window queries in this model. In this work, we propose and experimentally evaluate a main-memory index called BiSW that supports sliding windows on system time, application time, and both time attributes simultaneously. Our experimental results show that BiSW outperforms existing approaches in terms of space footprint, maintenance overhead and query performance.

APA, Harvard, Vancouver, ISO, and other styles

Dissertations / Theses on the topic 'Sliding'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles