Дисертації з теми "Preloads"
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Woodend, Dianne. "The effect of sucrose and safflower oil preloads on satiety, mood and memory." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0021/MQ49777.pdf.
Повний текст джерелаNettles, A. T. "The effects of tensile preloads on the impact response of carbon/epoxy laminates." Diss., This resource online, 1996. http://scholar.lib.vt.edu/theses/available/etd-06062008-154902/.
Повний текст джерелаRegan, Paula J. "Influence of macronutrient preloads on appetite and metabolic parameters in liver and renal transplant recipients." Thesis, Queen Margaret University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.271521.
Повний текст джерелаJakel, Roland. "Analyzing a bolted, conical hub-shaft-connection with finite friction contact in Creo Simulate 3.0: Best practices for working with large displacement analysis, bolt preloads and finite friction contact." Technische Universität Chemnitz, 2018. https://monarch.qucosa.de/id/qucosa%3A21441.
Повний текст джерелаThe presentation describes how to analyze a flywheel with axially bolted hub-shaft- connection using a conical press fit with help of the finite friction contact model in Creo Simulate 3.0. Since Creo Simulate 3.0 from PTC offers a finite friction contact model implementation just for large displacement analysis, but not for simple analyses with small displacements, the user has to work around a couple of code specific limitations. Best practices are proposed how to do this. Special attention is paid on bolt modeling and preload adjustment. Analysis results are compared with analytical solutions.
Xu, Weiwei. "Effect of Bolted Joint Preload on Structural Damping." Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4794.
Повний текст джерелаLundin, Malin. "Left atrial functions: effects of increased and decreased preload." Thesis, Örebro universitet, Institutionen för hälsovetenskap och medicin, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-44928.
Повний текст джерелаThomas, Anthony H. 1981. "Strain based preload measurement in drive axle pinion bearings." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/30322.
Повний текст джерелаIncludes bibliographical references (leaf 44).
Bearing setting has a significant impact on bearing life and system performance. A strain based load measurement technique that has been previously developed and patented will be used to measure preload in automotive drive axle pinion bearings. This technique utilizes strain gages placed in notches that have been machined into the outer diameter of a bearing cup. The performance of two gage types, semiconductor and metal foil, are compared. Preload in the pinion bearings is simulated in a machine by applying an axial load to a bearing assembly. The bearing assembly is rotated at various speeds and temperatures for each set of axial loads. Two notch geometries are compared for each set of tests conducted. An effort has been made to develop a finite element model that can be used to verify the results of the gage calibration. The results of the calibration reveal that metal foil and semiconductor gages can provide preload measurements that are accurate to within 3.7% and 7.7% of the full scale input load (73 lbs. and 155 lbs.) respectively.
by Anthony H. Thomas, II.
S.M.and S.B.
Jacobs, Nicholas R. "Displacement of Screw-Retained Single Crowns into New Generation Narrow Diameter Implants with Conical and Conical/Hex Internal Connections and their Performance when Cyclically Loaded." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1566144926275455.
Повний текст джерелаPreuss, Jason Lee. "Design and analysis of a composite flywheel preload loss test rig." Thesis, Texas A&M University, 2004. http://hdl.handle.net/1969.1/100.
Повний текст джерелаÅkerblom, Mats. "Gearbox noise : Correlation with transmission error and influence of bearing preload." Doctoral thesis, KTH, Maskinkonstruktion (Inst.), 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-9899.
Повний текст джерелаQC 20100923
Åkerblom, Mats. "Gearbox noise : correlation with transmission error and influence of bearing preload /." Stockholm : Maskinkonstruktion, Kungliga Tekniska högskolan, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-9899.
Повний текст джерелаWang, Lu, and 王璐. "Post-compressed plates for strengthening preloaded reinforced concretecolumns." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hub.hku.hk/bib/B50162664.
Повний текст джерелаpublished_or_final_version
Civil Engineering
Doctoral
Doctor of Philosophy
Lin, Alvin Lai. "Design and implementation of a preload electronics architecture for a MEMS accelerometer." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/62988.
Повний текст джерелаCataloged from PDF version of thesis.
Includes bibliographical references (p. 99-101).
This thesis describes the design and implementation of an electronics system to provide rebalancing and readout for a force-rebalanced microelectromechanical accelerometer. A feedback control loop is devised using a novel preload architecture, compensating the proof mass of the sensor and providing an accurate acceleration measurement. This architecture is compared to alternative methods of linearizing the control loop. The electronics system is divided into analog and digital subsystems. The design is analyzed at several abstraction levels. The system is implemented for prototype testing with discrete components on a printed circuit board with a MEMS sensor attached. A computer program is implemented to receive and process the readout data using the serial port. The design methodology consists of a top-down design flow based on simulation. At each iteration in the design process, the lower level abstraction is verified with the previous model. Eventually, the design reaches the level of synthesizable digital logic and discrete analog components. This thesis describes the design process and implementation details for creating an accelerometer system prototype ready for lab testing. Detailed simulations indicate that the implemented design is likely to meet the design goals for a personal navigation system suitable for a human or land vehicle. Conclusions on design methodology and verification techniques are also presented.
by Alvin Lai Lin.
M.Eng.
Kovacs, Michelle. "The Effects of Caloric Preload and Dietary Restraint on Smoking and Eating Behavior." Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4524.
Повний текст джерелаRoan, Earl Taylor. "Design of an STM and EPL control system and linear actuator preload diaphragm." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/40310.
Повний текст джерелаThis electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (p. 53-54).
Increasing demand for nano-scale machining processes in the semiconductor industry necessitates new mechanisms for nano-machining. A system capable of nano-scale machining of conductive material via Electronic Pen Lithography (EPL) may fit this niche. The purpose of this research is to develop a system capable of EPL based on a HexFlex six axis nano-manipulator. The system will also be capable of Scanning Tunneling Microscopy (STM), which is will locate the surface with the precision necessary for EPL and also allow the user to confirm the machined features immediately after machining. The import of this work is the development of a low-cost and compact system for nano-machining and nano-scale imaging. The impact of this work may improve the process for manufacturing semiconductors including circuitry, MEMS, and NEMS. The continued development of full six axis machining techniques may allow for the construction of features hitherto impossible to fabricate. This segment of the project focuses on the integration of the HexFlex, a micron stepper motor, precision mounts, a preload diaphragm, and an advanced control system capable of automated EPL and STM verification. Steady electron tunneling is first demonstrated, followed by STM imaging functionality. However, high-speed, high-accuracy EPL machining techniques are reserved for future work.
by Earl Taylor Roan.
S.B.
Oliveira, Marcio Rodrigo de. "Estudo e implementação da otimização de Preload de dados usando o processador XScale." [s.n.], 2005. http://repositorio.unicamp.br/jspui/handle/REPOSIP/276447.
Повний текст джерелаDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Computação
Made available in DSpace on 2018-08-06T14:27:52Z (GMT). No. of bitstreams: 1 Oliveira_MarcioRodrigode_M.pdf: 1563381 bytes, checksum: 52e2e029998b3539a26f5c2b76284d88 (MD5) Previous issue date: 2005
Resumo: Atualmente existe um grande mercado para o desenvolvimento de aplicações para sistemas embutidos, pois estes estão fazendo parte crescente do cotidiano das pessoas em produtos de eletrônica de consumo como telefones celulares, palmtop's, agendas eletrônicas, etc. Os produtos de eletrônica de consumo possuem grandes restrições de projeto, tais como custo reduzido, baixo consumo de potência e muitas vezes alto desempenho. Deste modo, o código produzido pelos compiladores para os programas executados nestes produtos, devem executar rapidamente, economizando energia de suas baterias. Estes melhoramentos são alcançados através de transformações no programa fonte chamadas de otimizações de código. A otimização preload de dados consiste em mover dados de um alto nível da hierarquia de memória para um baixo nível dessa hierarquia antes deste dado ser usado. Este é um método que pode reduzir a penalidade da latência de memória. Este trabalho mostra o desenvolvimento da otimização de preload de dados no compilador Xingo para a plataforma Pocket PC, cuja arquitetura possui um processador XScale. A arquitetura XScale possui a instrução preload, cujo objetivo é fazer uma pré-busca de dados para a cache. Esta otimização insere (através de previsões) a instrução preload no código intermediário do programa fonte, tentando prever quais dados serão usados e que darão miss na cache (trazendo-os para esta cache antes de seu uso). Com essa estratégia, tenta-se minimizar a porcentagem de misses na cache de dados, reduzindo o tempo gasto em acessos à memória. Foram usados neste trabalho vários programas de benchmarks conhecidos para a avaliação dos resultados, dentre eles destacam-se DSPstone e o MiBench. Os resultados mostram que esta otimização de preload de dados para o Pocket PC produz um aumento considerável de desempenho para a maioria dos programa testados, sendo que em vários programas observou-se uma melhora de desempenho maior que 30%!
Abstract: Nowadays, there is a big market for applications for embedded systems, in products as celIular phones, palmtops, electronic schedulers, etc. Consumer electronics are designed under stringent design constraints, like reduced cost, low power consumption and high performance. This way, the code produced by compiling programs to execute on these products, must execute quickly, and also should save power consumption. In order to achieve that, code optimizations must be performed at compile time. Data preload consists of moving data from a higher leveI of the memory hierarchy to a lower leveI before data is actualIy needed, thus reducing memory latency penalty. This dissertation shows how data preload optimization was implemented into the Xingo compiler for the Pocket PC platform, a XScale based processor. The XScale architecture has a preload instruction, whose main objective is to prefetch program data into cache. This optimization inserts (through heuristics) preload instructions into the program source code, in order to anticipate which data will be used. This strategy minimizes cache misses, allowing to reduce the cache miss latency while running the program code. Some benchmark programs have been used for evaluation, like DSPstone and MiBench. The results show a considerable performance improvement for almost alI tested programs, subject to the preload optimization. Many of the tested programs achieved performance improvements larger than 30%
Mestrado
Otimização de Codigo
Mestre em Ciência da Computação
Cui, Zheng. "FUEL: A Runtime Methodology to Preload Time Consuming UI-APIs for Android Apps." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu158768332631699.
Повний текст джерелаSubasic, Mustafa. "The effect of preload on the fatigue strength of additively manufactured 316L stainless steel." Thesis, KTH, Hållfasthetslära, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-285818.
Повний текст джерелаI detta examensarbete presenteras en undersökning på effekten av förbelastning på utmattningsbeteendet hos additivt tillverkade (AM) komponenter av 316L rostfritt stål med mindre än 5 % porositet, för både horisontell och vertikal byggriktning. Provstavarana tillverkades genom selektiv lasersmältning (SLM) och skars ut med trådgnist (EDM). Förspänningar i två olika storlekar användes, under och över materialets sträckgräns, och utmattningstester utfördes på provstavarna med och utan förspänningarna. Dessutom genomfördes mikrostrukturella analyser för att illustrera / kvantifiera defekterna och effekten av förspänningen med användning av vitt ljusinterferometri (WLI), SEM och FEM-modellering. Det visade sig att utmattningslivslängden och utmattningsgränsen tydligt ökar med ökad förspänning i båda byggriktningarna, även om förspänningens betydelse kan variera för olika riktningar. Denna positiva effekt på utmattningen kommer från de kompressiva restspänningarna och avstumpningen av skarpa defekter som uppstår efter förbelastningen.
Paye, Anco Alex Aurelio, Castillo José Peña, and Sanchez Juan Franco. "Propuesta para la utilización de losas de entrepisos prefabricados y su evaluación costo-tiempo." Universidad Peruana de Ciencias Aplicadas (UPC), 2014. http://hdl.handle.net/10757/337192.
Повний текст джерелаEvans, Brandon A. (Brandon Adam). "Development of kinematic coupling preload guidelines through design and testing of an adjustable micromanufacturing fixture." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/92063.
Повний текст джерелаThis electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 111-117).
In the growing field of non-lithographic micromanufacturing, the ability to properly align a workpiece to a machine limits the attainable tolerances in micro-electro-mechanical-systems (MEMS) prototyping. This limit has created the need for a standard adjustable base for implementation into multiple precision machines, allowing for six-axis adjustment and alignment of workpiece stages that are moved between these machines. Such a fixture--a hybrid positioning fixture (HPF)--has been designed, fabricated, and tested. This HPF has demonstrated <50 nm and <1.5 [mu]rad 2[sigma] (95% confidence) static positional repeatability over 1000 separation-engagement cycles and equivalent 2[sigma] (95% confidence) path-following accuracy when used as a dynamic nano-stage. The HPF has also demonstrated adequate stiffness to ensure <50 nm positional accuracy over an adjustment range of ±5 [mu]m and ±100 [mu]rad in response to 2 N normal and lateral forces during micro-milling operations. The HPF is based upon a kinematic coupling concept, and experiments have been completed that show highly repeatability coupling can be obtained by loading the Hertzian kinematic contacts of the HPF past the fully plastic half-groove material limit. This is a novel result that allows for stiffness increases of ~2.5 and load capacity increases of ~15.5 over conventional kinematic couplings, which are typically loaded to the sub-surface elastic limit.
by Brandon A. Evans.
S.M.
Turk, Amanda C. (Amanda Christine). "Design and fabrication of a device to characterize spindle performance as a function of bearing preload." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/75453.
Повний текст джерелаThis electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Page 98 blank. Cataloged from student submitted PDF version of thesis.
Includes bibliographical references (p. 83-84).
This paper describes the design and fabrication of an apparatus to characterize the performance of lathe spindles as a function of spindle bearing preload. The apparatus will be used to assist undergraduate students enrolled in 2.72 in understanding mechanical design concepts. In order to assess spindle performance, the apparatus measures the radial stiffness, radial error motion, and running torque of a spindle at different preload levels. The data obtained using the apparatus can be used by students to select the optimal preload level for a spindle. The apparatus was designed as four subsystems (one for each measurement) that were integrated into a cohesive measurement system. The apparatus is designed to be as small, light, and user-friendly as possible, in order for students to use it effectively. The apparatus is capable of measuring bearing preload up to 10,000 lbs with a linearity of 0.05% and radial error motion with an accuracy of +/-0.00012 in. (3 [mu]m). It can measure the radial stiffness of the spindle for applied loads up to 500 lbs and running torque up to 443 in-lbs (50 N-m). The fabrication and assembly of the mechanical apparatus, as designed, were completed.
by Amanda C. Turk.
S.B.
Braxton, Joi Requan. "Effect of preload on the response of mouse trachea smooth muscle to cholinergic stimulation a thesis /." San Antonio : UTHSC, 2008. http://learningobjects.library.uthscsa.edu/cdm4/item_viewer.php?CISOROOT=/theses&CISOPTR=33&CISOBOX=1&REC=10.
Повний текст джерелаCierocka, Joanna, and Jiayue Tang. "Vibrational tests of preloaded rubber vibration isolators : A cam controlled displacement excitation." Thesis, Linnéuniversitetet, Institutionen för maskinteknik (MT), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-53703.
Повний текст джерелаDunn, Jonathan Mark. "Determining the stiffness characteristics of a preloaded bolted joint using finite element analysis." Thesis, University of Bath, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320326.
Повний текст джерелаRichards, Jason Halbert. "Turn-of-the-nut tightening of anchor bolts." Texas A&M University, 2004. http://hdl.handle.net/1969.1/443.
Повний текст джерелаCravotta, Stefan, and Emanuele Grimolizzi. "Simulation of vehicle impact into a steel building : A parametric study on the impacted column end-connections." Thesis, KTH, Bro- och stålbyggnad, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-172341.
Повний текст джерелаScherer, Rebecca Elizabeth. "Settlement Analyses of Grade Supported Tanks Constructed with the Use of Prefabricated Wick Drains and an Earth Preload." ScholarWorks@UNO, 2011. http://scholarworks.uno.edu/td/1345.
Повний текст джерелаAndersson, Amanda, and Adam Eklund. "Vidareutveckling av friktionsbetingat förband för fixering av tankar." Thesis, Mälardalens högskola, Akademin för innovation, design och teknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-40251.
Повний текст джерелаScania CV AB är ett av de världsledande företagen inom tunga fordon. Deras utbud av lastbilar är brett, och lastbilarna är utrustade med gas-, eller bränsletankar, beroende på fordonets drivmedel. Lastbilarna är även utrustade med trycktankar som används vid inbromsning och luftfjädring. Tankarna är monterade med spännband, där gummimellanlägg utgör ett skydd mellan tank och spännband för att skydda tanken mot nötning. Vid installation av olika lastbilstankar finns behov av element i förbandet som ökar friktionen, kompenserar formfel, förhindrar nötning, och medger elektrisk isolation. Detta har traditionellt gjorts genom att använda gummimellanlägg i förbandet. Gummimellanlägg ökar dock osäkerheten i den faktiska förspänningen av förbandet, samt rörelser i konstruktionen ofta får mellanlägget att vandra ur position. Syftet med projektet är att skapa förståelse för vilka egenskaper och förutsättningar som påverkar prestandan av ett friktionsbetingat förband, samt att hitta konceptuell lösning på grundproblematiken. För att kunna fullgöra syftet har följande frågeställningar utformats:F1: Vilka orsaker ligger till grund för att förspänningen i spännbanden släpper vid montering av diverse fordonstankar?F2: Vilka orsaker ligger till grund för att gummimellanlägg tenderar att vandra ur position i olika tankinstallationer?F3: Vilka åtgärder kan vidtas för att motverka att förspänningen i spännbanden släpper och att gummimellanläggen vandrar ur position? I arbetet har en fallstudie och en litteraturstudie genomförts. Litteraturstudien utfördes för att skapa övergripande förståelse i ämnen som kan vara relevanta för arbetet. Den insamlade informationen härrör från böcker, forskningsavhandlingar och vetenskapliga artiklar. Data har även samlats in i form av intervjuer, tekniska rapporter, felrapporter, lagkrav, ritningar, statistik i fältkvaliteten, och observationer i produktionen. Fallstudien baseras på en produktutvecklingsprocess där flera produktutvecklingsverktyg har använts. I fallstudien ingår även materialprov i form av friktion och sättning. Arbetet resulterade i ett koncept i form av ett gummimellanlägg och baseras på Scanias befintliga lösning. Lösningen består av fyra komponenter: geometrilåsning i form av flänsar och så kallade grantoppar, rundade kortsidor och gropig undersida. Storleken kan däremot variera på grund av spännbandens och tankarnas breda storleksspann. Arbetet har även resulterat i en design-guideline, som ska ge riktlinjer och vägledning för fortsatt arbete och framtida konstruktion.
Aron, Adrian. "The utility of bioimpedance cardiography in assessing the influence of obstructive sleep apnea hypopnea syndrome on cardiac function." Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/72996.
Повний текст джерелаPh. D.
Zimandy, Adam Joseph Charles. "Prevailing Torque Locking Feature Wear-out." Scholar Commons, 2012. http://scholarcommons.usf.edu/etd/4424.
Повний текст джерелаWatral, Adrienne. "Design and engineering of low-cost centimeter-scale repeatable and accurate kinematic fixtures for nanomanufacturing equipment using magnetic preload and potting." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/65317.
Повний текст джерелаCataloged from PDF version of thesis.
Includes bibliographical references (p. 127-130).
This paper introduces a low-cost, centimeter-scale kinematic coupling fixture for use in nanomanufacturing equipment. The fixture uses magnetic circuit design techniques to optimize the magnetic preload required to achieve repeatability on the order of 100 nanometers. The fixture achieves accuracy to within one micrometer via an adjustable interface composed of UV curing adhesive between the mating kinematic coupling components. The fixture is monitored by a micro-vision system and moved by a six-axis nanopositioner until proper alignment is achieved, at which point the fixture position is permanently set by UV light. This thesis presents design rules and insights for design of a general accurate and repeatable kinematic fixture and presents a case study of fixtures used for tool exchange on dip pen nanolithography machines. A prototype fixturing assembly was fabricated and tested for repeatability and stability in six degrees of freedom. The test results concluded that the fixture has a 1-o- 3-D translational repeatability of 87 nanometers and a 3-D stability of 344 nanometers over 48 hours. This is an order of magnitude improvement on past low-cost accurate and repeatable fixture designs. This optimized accurate and repeatable kinematic fixture will enable repeatable, accurate, quick, and elegant tool change, thus advancing the manufacturing capabilities of nanofabrication techniques.
by Adrienne Watral.
S.M.
Cheatham, Christopher. "Statistical analysis of fastener vibration life tests." [Tampa, Fla.] : University of South Florida, 2007. http://purl.fcla.edu/usf/dc/et/SFE0002275.
Повний текст джерелаHernandez, Alan. "Use of Anaerobic Adhesive for Prevailing Torque Locking Feature on Threaded Product." Scholar Commons, 2015. http://scholarcommons.usf.edu/etd/5700.
Повний текст джерелаRamadoss, Vivek. "Analysis of capillary forces in electrowetting and precision self assembly." [Tampa, Fla] : University of South Florida, 2008. http://purl.fcla.edu/usf/dc/et/SFE0002439.
Повний текст джерелаCheyne, William Spencer. "The effect of negative intrathoracic pressure on heart-lung interaction in the presence of elevated lung volume and increased right ventricular preload and afterload." Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/55262.
Повний текст джерелаGraduate Studies, College of (Okanagan)
Graduate
Cyprian, Rudolf. "Aktivní řízení předpětí hlavy obráběcího stroje." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-230921.
Повний текст джерелаSalam, Jamal Mohamad. "Application of cyclic uniaxial compression testing to investigate the effects of preload and other factors on the structural properties of concrete affected by alkali silica reaction." Thesis, Queen Mary, University of London, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261641.
Повний текст джерелаLaine, Daniel Petri. "Effect of axial preloads on confined concrete." 2004. http://link.library.utoronto.ca/eir/EIRdetail.cfm?Resources__ID=94923&T=F.
Повний текст джерела"The Effects of Meal Preloads on Glycemia, Insulinemia and Satiety." Master's thesis, 2012. http://hdl.handle.net/2286/R.I.14935.
Повний текст джерелаDissertation/Thesis
M.S. Nutrition 2012
Watson, Linda Ernestine. "A novel nutritional approach to the management of type 2 diabetes: effects of nutritional preloads on postprandial blood glucose and gastric emptying in type 2 diabetes mellitus." Thesis, 2018. http://hdl.handle.net/2440/115410.
Повний текст джерелаThesis (Ph.D.) (Research by Publication) -- University of Adelaide, Adelaide Medical School, 2018
Patel, Vipulkumar Ishvarbhai. "Nonlinear inelastic analysis of concrete-filled steel tubular slender beam-columns." Thesis, 2013. https://vuir.vu.edu.au/22015/.
Повний текст джерелаEsfahbod, Behdad. "Preload: An adaptive prefetching Daemon." 2006. http://link.library.utoronto.ca/eir/EIRdetail.cfm?Resources__ID=450330&T=F.
Повний текст джерелаLuo, Kai Hong, and 羅凱鴻. "Detection of Ball Screw Preload." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/86621045755210910448.
Повний текст джерела國立中正大學
機械工程學系暨研究所
99
This study aims to establish the relation between the ball screw preload and the ball pass frequency; and then develop an intelligent on-line system for detecting whether the ball screw preload still takes effect. The ball screw vibration spectra blurred by the unsteady ball passing in the recycling tube is improved using the Vold-Kalman -filter order tracking(VKFOT) technique. Two methods that quantify the preload in a ball screw are proposed. The first is to determine the ball passing order ni a ball screw vibration spectra for ball screws with varying preload. The second is to quantify the participation in percentage of each vibration order during the period that the nut is traveling on the ball screw. And these two measures can be represented in a single tine-order plot. With these two measures, detecting the preload in a ball screw automatically and intelligently becomes feasible. Results from experiments show that the ball passing order is 11.5 for a ball screw with a preload of 1.5%; and 11.1 for a ball screw with a preload of 4% approximately. That is, the ball passing order of a ball screw with large preload is smaller than that with a light preload. With the proposed technique, the diagnostic system can detect whether the preload of a ball screw is still in effect with accuracy higher than 80%.
Ibrahim, Safwat A. H. "Preloaded frame structures." Thesis, 1987. http://spectrum.library.concordia.ca/3975/1/ML35555.pdf.
Повний текст джерелаTuan, Yu-Chiang, and 段玉強. "Preload-Controlled and Friction Compensation with Ballscrew." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/42505851193249393044.
Повний текст джерела國立中正大學
機械工程學系
85
AbstractHigh speed precise positioning is very important technology in industry. To improve accuracy and to increase products, like semiconductor and MEMs technology, high speed precise positioning is used. So the goal of this research is high speed precise positioning.There is a backlash program in ballscrew, so if we want to eliminate backlash and increase stiffness, we get preload to ballscrew. But the preload is high so that the friction is increase. So we design a preload tuning machine to change preload of ballscrew and fine tuning of positioning.The coarse positioning using ballscrew , the controller is used the traditional PID controller and IP control, and the position accuracy is up to 1 mm, and change to piezoactuator to fine tune and the position accuracy is up to 0.1mm.
Li, Chi-Rung, and 李起榮. "Development of Ball Screw Preload Detection Technology." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/55987538877378499067.
Повний текст джерела國立中正大學
機械工程學系暨研究所
101
There are two purposes of this research. Firstly, a technique based on the method of Angular Velocity Vold-Kalman Filtering Order Tracking (AV VKF-OT) for monitoring the occurrence of preload loss of a ball screw in a feed drive system is proposed. Secondly, a method to measuring the ball screw friction torque induced by the preload is introduced. In detecting the preload loss in a ball screw feed drive system, it is worthy of noting that both the ball pass order and the vibration amplitude change corresponding to the major ball pass order along the screw shaft are monitored. It shows that the vibration amplitude of the ball screw without preload is not only higher than those with preloads but also varies strongly when the nut is traveling along the ball screw shaft. It also shows that the vibration amplitude variation along the shaft without preload is much larger than those with preload. Taking not only the change of BPO but also the vibration amplitude variation as well into account, experimental results show that the accuracy in detecting the occurrence of preload loss can be improved up to 93% approximately. On the other hand, the ball pass order changes little as the temperature rises from 25.5℃to 36.3℃. It concludes that the preload appears to be unaffected in this temperature range. For measuring the ball screw friction torque induced by the preload, a platform that consists of loadcells and accelerometers is introduced. The torque measured using this platform does not include the friction torque from bearings and thus it reflects the torque induced only by the preload on the ball screw.. Experiment results show that the torque induced by ball screw preload is 71% to 80% of that measured using the traditional torque sensor. That is, for a ball screw feed drive system, the ball screw preload costs 71-80% of the torque from motor, whereas the bearing accounts for the remaining 20-30%.
Huang, Hung-Chun, and 黃弘竣. "Technology development of ball screw preload detection technology." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/56840817465277235150.
Повний текст джерела國立中正大學
機械工程學系暨研究所
100
A technique based on the method of Angular Velocity Vold-Kalman Filtering Order Tracking (AV VKF-OT) for monitoring the occurrence of preload loss of a ball screw in a feed drive system is proposed. Experimental results show that the friction caused by the preload tends to reduce the ball pass frequency. Therefore, the proposed technique focuses on measuring the change of the ball pass frequency instead of the ball screw vibration when the nut is traveling on the ball screw shaft. Results from both simulations and experiments show that the AV VKF-OT can successfully detect the small order change in an order spectrum of a preloaded ball screw and and provides a much better performance as compared to the traditional order tracking in terms of order resolution and order accuracy. Tests also conducted in several ball screw drive systems with varying preloads ranging from 1.5% to 7% provided by the ball screw manufacturer to access the performance of the proposed method. It concludes that the proposed technique so far has an accuracy of 70% approximately in determining whether the preload of ball screw exists. Simply attaching an accelerometer near the return tube, the proposed method provides an economic and reliable way in detecting the preload loss and is easy to be integrated in a prognosis system for ball screw.
Chian, Shin-Yan, and 錢信諺. "Diagnosis of Ball Screw Preload Loss by Acoustic signals." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/98581380192628287141.
Повний текст джерела國立彰化師範大學
機電工程學系
99
The ball screws of mechanical transmission elements are used as the fast moving components in recent years. There are some issues when the inner elements of ball screw operate in high speed: (1) impact force of internal ball rolling and sliding on the raceway and returning pipe (2) friction and heat due to poor lubrication (3) wear effect when ball screw operates for a longtime and renders the preload loss problem. In this thesis, the microphone was used to detect and distinguish the sounds from the background noise, motor, coupling, ball screw and nut when the feed system in operation. Both of accelerometer and microphone validate the data acquisition signals for diagnosis. Hilbert Huang transform (HHT), Short-Term Fourier Transform (STFT) and Marginal Spectrum are used to analyze the characteristics of ball screw stiffness. The experiment results show (1) optimization method for finding microphone position is provided. (2) The dominated frequency of the 2%, 4% and 6% preload ball screw is about 320Hz, 450 Hz and 850 Hz through sound and vibration signals (3) Different preload ball screws by using the HHT and STFT analysis can be realized through the acoustic signals. This diagnosis method realizes the purposes of prognostic effectiveness on knowing the preload loss and utilizing convenience.
Sun, Ming-Hua, and 孫明華. "Experimental Investigation on Preload for Wear of Ball Screw." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/37872409121680029546.
Повний текст джерела國立中興大學
機械工程學系
90
Ball screw is often used in the precise positioning which is the key technique of processing and mechanism motion. The friction force can be highly reduced by using the ball screw, because it transmits the power through rolling contact between the ball and nut, and between the ball and screw. But after operating for a period, wear will happen on the screw, ball, and nut, which will generate the clearance and cause the effect of preload disappear gradually. In this paper, the wear conditions of ball screw under different preloads and external loads have been discussed. The main factors of causing wear are the applied force on the ball and the rolling distance of the ball. Wear equations obtained from other researches have been studied in this paper to understand the relationships of the wear parameters. An analysis of the ball rolling the surface also have been done to understand the applied force on the ball under preload and external load. In order to understand the wear conditions of the ball screw under operation, a testing platform has been set up. By adjusting the preload and external load on the ball screw, different applied force conditions on the ball can be obtained. The wear amount was measured under different rolling distance to study the relationships between the wear conditions and the preload and external load. Also the factor of assembly and disassembly during the testing was analyzed in this research. The purpose of this research is trying to provide the information of wear conditions of ball screw under different loading conditions which can help the machine designers to understand more about the characteristic of the ball screw.
Huang, Jing-ting, and 黃靖婷. "Gel preloaded microchips for DNA analysis." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/38493746211245001543.
Повний текст джерела國立成功大學
化學工程學系碩博士班
95
In this study, we proposed and demonstrated fabrication of the gel preloaded microchips for DNA analysis. The photocurable polyacrylamide gel solution was first pre-loaded inside the open microchannels, followed by UV curing and drying. The microchannels with dried gel were covered with a PMMA film and sealed via vacuum and heating. The results showed that distribution of the dried gel in microchannels was uniform, and the apparent swelling ratio of the gel in the microwell was larger than its free swelling ratio. Furthermore, there is no race tracking observed in the microchannel and the pore size distribution inside the microchannel is similar to that obtained by using common fabrication technique. DNA separation was also reasonably well. This fabrication technique yields excellent packaging of the polymer based DNA separation microchips ready for use with fast loading capability and increased portability.